|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Prepublished online as a Blood First Edition Paper on February 6, 2003; DOI 10.1182/blood-2002-01-0324.
NEOPLASIA
From the Renal Unit, Massachusetts General
Hospital, Charlestown, MA; the Department of Surgery, Beth Israel
Deaconess Medical Center, Boston, MA; the Division of Nephrology,
Albert Einstein College of Medicine, Bronx, NY; Institut de
Hematologié, Hôpital Saint-Louis, Paris, France; and the
Department of Dermatology, Brigham and Women's Hospital, Boston,
MA.
Hairy cell leukemia (HCL) is a chronic lymphoproliferative
disease, the cause of which is unknown. Diagnostic of HCL is abnormal expression of the gene that encodes the Hairy cell leukemia (HCL) or leukemic
reticuloendotheliosis represents approximately 2% of adult leukemias
and is characterized by pancytopenia, hepatomegaly, splenomegaly,
leukocytosis, and neoplastic mononuclear cells in the peripheral blood,
bone marrow, liver, and spleen.1 The name of the disease
is derived from the presence of broad-based undulating ruffles on the
surface of the leukemic cells that appear under the phase contrast
microscope as cytoplasmic projections or "hairs." These cells can
be derived both from B and T lymphocytes as demonstrated by their
expression of B- or T-cell-specific antigens and are characterized
biochemically by their abnormal expression of the integrin heterodimer
CD11c/CD18.2-4 Under normal circumstances the gene
encoding the CD18 component of this marker is transcribed both in
lymphocytes and myeloid cells, whereas the gene encoding the CD11c
component is transcribed primarily in cells of the myeloid
lineage.5 The CD11c/CD18 heterodimer is, therefore,
normally largely restricted in its expression to the surface of myeloid
cells dictated by the myeloid-specific transcription of the
CD11c gene. In hairy cell leukemia the CD11c/CD18 heterodimer is present on not only myeloid cells but also on the neoplastic lymphocytes. Diagnostic of this disease is, therefore, the
abnormal regulation of CD11c gene transcription.
Consequently, elucidation of the molecular causes of this abnormal
regulation are likely to result in insights into the molecular basis of
hairy cell leukemia. Using this rationale we isolated the human
CD11c gene and identified the cis-acting elements
that control its transcription. The most important of these elements
interacts with activator protein-1 (AP-1) encoded by the
jun and fos families of proto-oncogenes. In hairy
cells an AP-1 complex containing JunD exhibits a constitutive pattern
of expression, whereas in other cell types it is functionally expressed
only upon induction with phorbol ester. The use of dominant-negative mutants in transfection assays demonstrated that both AP-1 and its
upstream activator Ras are necessary for CD11c
expression in hairy cells. In addition, exogenous expression of a
dominant-positive mutant of Ras was able to activate the
CD11c promoter in nonhairy cells to a level equivalent to
that seen in hairy cells. Taken together, these results indicate that
activation of the proto-oncogenes junD and ras
underlie the abnormal expression of the CD11c gene characteristic of HCL.
Cell culture
Plasmid construction
Transfection Cells were transfected10-12 with 24 µg luciferase test plasmid together with 1 µg pRSV- , which
contains the lacZ gene. Each transfection of p11Wt and
p11 A to p11H was performed in parallel with a transfection of the
negative control plasmid pATLuc. At 16 hours after electroporation,
cells were processed for assay of -galactosidase and luciferase
activity. Transfections that used the effector plasmids RSV-hjD,
pTAM67, pRasN17, or pRasV12 were performed as described above
except that 8 µg luciferase plasmids were mixed with 16 µg effector plasmid and 1µg pRSV-. As controls for these
experiments, parallel transfections were performed with the empty
parental vectors from which the effector plasmids were derived.
Electrophoretic mobility shift assay (EMSA) Nuclear extracts were prepared as described by Farokhzad et al.12 DNA probes were generated by annealing complementary oligonucleotides that had been radiolabeled at their 5' ends using T4 polynucleotide kinase and [ 32P] adenosine
triphosphate. Nuclear extract (1.3 µg) was incubated at 4°C
for 15 minutes in 70 mM KCl, 5 mM NaCl, 20 mM
tris(hydroxymethyl)aminomethane-HCl (pH 7.5), 0.5 mM
ethylenediaminetetraacetic acid, 1 mM dithiothreitol, 10% (vol/vol)
glycerol, 2.4 µg poly d(I:C).poly d(I:C), and a 500 molar excess of
unlabeled competitor probe where indicated. Radiolabeled probe (10 000
cpm, 0.05-0.15 ng) was then added and the incubation continued for 30 minutes prior to native polyacrylamide gel electrophoresis. Gels were
dried and subjected to autoradiography. Electrophoretic mobility
supershift assays were performed in the same way as the standard EMSA
analyses except that, prior to the addition of DNA probes, nuclear
extracts were preincubated for 15 minutes at 4°C with either 1 µL
rabbit preimmune serum or 1 µL rabbit polyclonal antibody. All
antibodies were obtained from Santa Cruz Biotechnology (Santa Cruz,
CA). The double-stranded oligonucleotides used in analysis of the
nuclear proteins that interact with the CD11c promoter were
as follows: CD11c Box E, 5'-CCCCTCTGACTCATGCTGA-3' and
3'-GGGGAGACTGAGTACGACT-5'; Consensus AP-1,
5'-CTAGTGATGAGTCAGCCGGATC-3' and 3'-GATCACTACTCAGTCGGCCTAG-5' (Stratagene Cloning Systems, La Jolla, CA); and
Consensus Sp1, 5'-GATCGATCGGGGCGGGGCGATC-3' and
3'-CTAGCTAGCCCCGCCCCGCTAG-5' (Stratagene Cloning Systems).
Flow cytometric analysis Flow cytometry was performed by incubating 5 × 105 cells with a fluorescein isothiocyanate (FITC)-conjugated monoclonal antibody to CD11c (Accurate Chemical & Scientific, Westbury, NY) or immunoglobulin G1 FITC (Pharmingen, San Diego, CA). After staining, cells were fixed with 1% paraformaldehyde and analyzed using a FACScan flow cytometer (Becton Dickinson, Franklin Lakes, NJ).
The wild-type CD11c promoter directs expression in hairy cells We have previously isolated the human CD11c gene and determined the nucleotide sequence of the 5'-flanking region (C.S.S., E.P.B., O.C.F., M.A.A., GenBank accession no. L19440). A fragment of the CD11c gene representing nucleotides 128 to + 36 relative to the major transcription
initiation site was cloned immediately upstream of a
luciferase reporter gene to generate the construct p11Wt.
Transfection experiments using this construct indicated that it was
able to direct expression that was induced during activation of the
monocytic cell line U937 and the T-lymphocytic cell line Jurkat
(C.S.S., unpublished observations, October 1993). In order to
establish whether p11Wt was able to direct expression in hairy cells it
was transfected into the hairy cell lines Mo, EH, and HK (Figure
1). These cell lines were
established from different patients with hairy cell leukemia. Mo cells
are derived from T cells, whereas EH and HK cells are derived from B
cells.7,13,14 Transfection analysis demonstrated that in
Mo, EH, and HK cells p11Wt is able to direct expression levels that
averaged, respectively, 246-, 151-, and 94-fold above the background
level conferred by the negative control plasmid pATLuc. In the
B-lymphocytic cell line IM-9, which is not of hairy cell origin, p11Wt
directed expression that averaged 31-fold above background.
A potential AP-1 binding site is critical for CD11c promoter activity in both hairy and nonhairy cells treated with PMA Taken together, our transfection data indicate that the CD11c promoter spanning nucleotides 128 to + 36
contains the cis-acting elements sufficient to direct
expression in hairy cells (Figure 1). Within the 128/+ 36 region,
8 putative cis-acting elements were identified. These
elements are herein referred to as Boxes A to H (Figure
2). Box A binds the transcription factors
PyRo1, Sp1, and Sp3.15-18 Box B binds Sp1, Sp3, and
Pur .15-17,19 Box C contains a consensus
recognition site for the Ets family of transcription factors and
overlaps a site demonstrated to bind c-Myb.20,21 The c-Myb
binding site overlapping Box C also represents a potential binding site
for the basic helix-loop-helix group of transcription
factors.22 Box D binds Sp1, Sp3, and
Pur.15-17,19 Box E contains an AP-1 binding site and
includes the sequence CTGAC, which, with its repeat, starting 6 nucleotides downstream, may represent a retinoic acid response
element.23-26 Box F binds Pur and Ets transcription
factors,19,27 and Box G binds the Ets factors PU.1 and
GABP2.28 The sequence of Box G also resembles the
terminal deoxynucleotidyl transferase group of "initiator" elements.29,30 Box H contains a consensus recognition site for the Ets family, overlaps consensus binding sites for C/EBP and
c-Myb, and contains part of the sequence TTCCTGCAA representing a
possible GAS element, which could mediate the induction of gene expression by both type I and type II
interferons.31-33
In order to determine the relevance of Boxes A to H to the
transcriptional activity of the CD11c gene in hairy cells,
linker scanning was used to test the effect of their specific mutation. This mutational analysis (Figure 3A)
demonstrated that, with the exception of Box A and Box C, all the
putative control elements identified by sequence analysis make
significant contributions to promoter activity in PMA-treated Mo hairy
cells. However, particularly important is Box E, representing a
potential site of interaction with AP-1. Disruption of this element
results in an 80% reduction in expression. In addition to being the
most important element directing expression in PMA-treated hairy cells,
Box E also represents the element most critical to PMA-induced
expression of the CD11c promoter in Jurkat lymphocytic cells
and U937 monocytic cells (Figure 3B-C).
The potential AP-1 site is critical to CD11c promoter activity in untreated hairy cells Box E is clearly vital to the activity of the CD11c promoter in PMA-treated hairy and nonhairy cells. However, given that Box E represents a putative AP-1 binding site and the normal pattern of AP-1 expression is induction with PMA, the importance of Box E to CD11c promoter activity in PMA-treated cells is unsurprising. Therefore, we tested the importance of Box E to CD11c promoter activity in hairy cells untreated with PMA. The Box E mutant p11E was transfected into the hairy cell
lines Mo, EH, and HK untreated with PMA in parallel with the wild-type
CD11c promoter construct p11Wt (Figure
4). After correction for transfection
efficiency these experiments demonstrated that the mutant promoter
exhibits expression levels that are 55%, 96%, and 92% reduced
compared with wild-type in Mo, EH, and HK, respectively. Consequently, Box E appears critical to the constitutive activity of the
CD11c promoter in untreated hairy cells.
Hairy cells exhibit abnormal expression of an AP-1 complex containing JunD The inappropriate expression of the CD11c gene in HCL can be due to 2 occurrences. The first is a mutation in or near the gene itself, and the second is abnormal regulation of the control factors with which the gene interacts. The activity in hairy cells of the wild-type CD11c promoter suggests the latter possibility. To further investigate this possibility, we performed EMSA analysis of the putative control factors expressed in hairy cells that interact with Box E, the most important of the functional cis-acting elements within the CD11c promoter. These analyses indicated that in both hairy cell lines and hairy cells isolated directly from a patient, Box E interacts specifically with a DNA binding activity that is immunologically indistinguishable from AP-1 (Figure 5, upper panel). However, the AP-1 complex expressed in hairy cells differs from that expressed in nonhairy cells in 2 important respects. First, in hairy cells AP-1 is expressed constitutively, whereas in other cell types it is expressed only after induction with phorbol ester (Figure 5, lower panel). Second, the AP-1 complex expressed in hairy cells interacts only with an antibody directed against the product of the proto-oncogene junD, whereas in nonhairy cells the AP-1 complex expressed upon phorbol ester treatment is composed of a mixture of JunD, c-Jun, JunB, and members of the Fos family (Figure 5, upper panel).
AP-1 expression is necessary for CD11c promoter activity in hairy cells, but expression of JunD is insufficient to activate the CD11c promoter in nonhairy cells Our observation that hairy cells exhibit abnormal chronic expression of AP-1 suggests that this may be responsible for their support of CD11c promoter activity. If this hypothesis is correct then inhibition of AP-1 would be expected to inhibit the activity of the CD11c promoter. TAM67 is a cDNA that encodes a c-Jun protein lacking a transactivation domain.34 The TAM67 protein forms heterodimers with wild-type AP-1 proteins to form transactivation-deficient AP-1 complexes. TAM67 expression, therefore, exhibits a dominant-negative effect on AP-1 function. This dominant-negative mutant has been used previously in vitro to inhibit AP-1 activity.34,35 In order to assess the affect of transient TAM67 expression on the activity of the CD11c promoter in hairy cells, this mutant was transfected into the Mo hairy cell line in combination with either pATLuc or p11Wt (Figure 6A). Under these conditions, the level of luciferase activity directed by p11Wt reached, on average, 37 times that conferred by pATLuc. In contrast, in the presence of the plasmid vector empty of the TAM67 mutant, p11Wt produced levels of activity that were, on average, 200-fold above the level directed by pATLuc. Consequently, TAM67 expression results in more than an 80% reduction in the activity of the CD11c promoter in hairy cells.
The use of the dominant-negative mutant TAM67 demonstrates that in hairy cells constitutive expression of AP-1 is necessary for CD11c promoter activity. Next, we wanted to determine if constitutive expression of JunD in nonhairy cells was sufficient to activate the CD11c promoter. In order to test this possibility we used the T-lymphocytic cell line Jurkat in which activation of the CD11c promoter has been demonstrated previously using phorbol esters (C.S.S., unpublished observation, October 1993). A construct constitutively expressing human JunD was transfected into Jurkat cells in combination with either pATLuc or p11Wt (Figure 6B). In the presence of exogenous JunD, the level of luciferase activity directed by p11Wt reached, on average, 154 times that conferred by pATLuc. In the presence of the plasmid vector empty of junD coding sequences, p11Wt produced levels of activity that were, on average, 158-fold above the level directed by pATLuc. Consequently, in isolation, constitutive JunD expression appears insufficient to activate the CD11c promoter in nonhairy cells. Ras activation is necessary for CD11c promoter activity in hairy cells and sufficient to activate the CD11c promoter in nonhairy cells JunD is a member of the AP-1 family of transcription factors. The function of this family is subject to a host of control mechanisms.39 Because the simple overexpression of JunD fails to activate the CD11c promoter in nonhairy cells, abnormalities in these upstream control mechanisms may account for the activity of JunD in hairy cells. One of the principal means by which AP-1 function is controlled is by phosphorylation events mediated by cascades of c-Jun NH2-terminal/stress-activated protein kinases (JNK/SAPK).39 An early event in the activation of JNK/SAPK is activation of the products of the ras proto-oncogenes. Consequently, we sought to determine the role of Ras in CD11c expression. First, we used the ras dominant-negative mutant RasN1736 in transient transfection studies of hairy cells. In the hairy cell line Mo, expression of RasN17 caused a 36% reduction in the transcriptional activity of the CD11c promoter (Figure 6A). These results demonstrated that Ras activation, like AP-1 production, contributes to the expression of the CD11c promoter in hairy cells. Next, we used the ras dominant-positive mutant RasV1238 in transient transfection studies of the nonhairy cell line Jurkat. In contrast to constitutive JunD expression, constitutive Ras activation resulted in the induction of the CD11c promoter. (Figure 6B). Specifically, RasV12 induced 3.5-fold the transcriptional activity of the CD11c promoter present in p11Wt. This induced level of transcription averaged 131 times the level of transcription exhibited by the promoter-less construct pATLuc also treated with RasV12. Thus, in nonhairy cells constitutive Ras activation causes the activity of CD11c promoter to rise to levels equivalent to those seen in hairy cells.An inhibitor of Ras signaling alters the activity of the CD11c promoter in hairy cells Our experiments with dominant-positive and dominant-negative mutants indicate that Ras plays an important role in controlling the activity of the CD11c promoter. Ras influences gene expression through 4 main signaling pathways. The central components of these distinct but interrelated pathways are Raf/MEK/ERK, Rac/Rho, Ral guanine exchange factors, and phosphatidylinositol 3-kinase/Akt.40-46 The Raf/MEK/ERK pathway is inhibited by the drug U0126, which blocks the activity of MEK1/2.47 We treated the 3 hairy cell lines Mo, EH, and HK with U0126 to further verify the involvement of Ras in constitutive expression of the CD11c promoter. Following transfection with the construct p11Wt, cells were treated with 8 µM U0126 for 24 hours prior to harvesting and the measurement of luciferase and galactosidase activities (Figure 7). This series of transfections demonstrated that U0126 does indeed influence CD11c promoter activity in hairy cells. However, this influence is clearly cell-specific, with U0126 inhibiting by 54% promoter activity in EH cells but inducing activity by 54% and 57% in Mo and HK cells, respectively. These results indicate that in different hairy cells different Ras signaling pathways are involved in driving CD11c expression. Thus, the pathways in EH cells are MEK1/2 dependent, whereas in Mo and HK cells they are MEK1/2 independent.
U0126 reduces cell-surface expression of CD11c In EH hairy cells the Ras signaling inhibitor U0126 represses the CD11c gene promoter when the promoter is present in an extrachromosomal plasmid (Figure 7). Therefore, next we investigated the possibility that U0126 also causes a reduction in surface expression of the CD11c protein, which would reflect repression of the endogenous CD11c gene. In 3 independent experiments, EH cells were either left untreated or treated in parallel for 48 hours with 8 µM U0126, and then surface expression of CD11c was assessed using flow cytometry (Table 1). This analysis established that treatment with U0126 causes, on average, a 44% decrease in CD11c expression. Consequently, in EH cells inhibition of Ras signaling through MEK1/2 inhibits endogenous as well as exogenous CD11c expression.
U0126 specifically reduces the proliferation of hairy cells Abnormal expression of CD11c represents one of the molecular hallmarks of HCL. The finding that this expression is dependent upon Ras signaling through MEK1/2 suggests that inhibition of this pathway may represent a useful therapeutic strategy. Consequently, we assessed the ability of the MEK1/2 inhibitor U0126 to block HCL proliferation (Figure 8). After treatment with 8 µM U0126 for 24, 48, and 72 hours the number of EH hairy cells was reduced, on average, by 12%, 33%, and 39%, respectively, relative to untreated controls. In contrast, treatment of the promonocytic cell line U937, which was derived from a patient with diffuse histiocytic lymphoma,48 caused no significant change in proliferation. Therefore, inhibition of MEK1/2 appears to specifically inhibit the proliferation of hairy cells.
Under normal circumstances CD11c gene expression is largely restricted to differentiating myeloid cells and a limited set of activated lymphocytes. However, in HCL, CD11c is constitutively expressed on the surface of the neoplastic lymphocytes and represents a diagnostic marker for the disease. Our transfection analysis established that constitutive expression of the CD11c gene in hairy cells is directed by the promoter region extending from 128 bp upstream to 36 bp downstream of the 5' major transcription initiation site. Within the CD11c promoter, 8 individual cis-acting control elements were identified and designated Boxes A to H. Mutation of these elements established that Box E is the most critical to the transcriptional activity of the CD11c promoter in hairy cells, activated myeloid cells, and activated lymphocytic cells. Box E interacts with the AP-1 family of transcription factors. EMSA analysis demonstrated that AP-1 expression correlates with the activity of the CD11c promoter. Thus, AP-1 is constitutively expressed in hairy cells and is induced in nonhairy cells concomitant with induction of CD11c gene expression. Expression of the AP-1 family is normally transient and tightly controlled as these factors regulate the progression of the cell cycle during cellular proliferation and differentiation.49 Consequently, the chronic constitutive expression of AP-1 exhibited by hairy cells is abnormal. A breakdown in control mechanisms, resulting in persistent AP-1 expression and chronic cellular proliferation, has been implicated in the development of melanoma, brain tumors, ovarian cancer, and asbestos-induced cancer,50-53 and the induction of malignant cell transformation in vitro.54-58 Our work suggests that such chronic cell proliferation, induced by persistent AP-1 expression, may contribute to the pathogenesis of HCL. The AP-1 complex induced in nonhairy cells upon phorbol ester treatment is composed of a mixture of JunD, c-Jun, JunB, and members of the Fos family. However, in the AP-1 complex constitutively expressed in hairy cells only JunD was detected. Although constitutive expression of JunD appears linked to HCL, our transfection studies indicate that chronic expression of JunD is not sufficient to induce CD11c promoter activity in nonhairy cells. Several explanations of these observations are possible. The first is that our transfection analyses used an expression construct that produced wild-type JunD, and hairy cells may produce mutant JunD. In this regard it is worthy of note that several AP-1 gene mutations, including mutations of junD, have been implicated in oncogenesis.59-68 Whether such mutations contribute to the neoplastic transformation responsible for HCL remains to be established. Other explanations as to why chronic JunD expression fails to induce the CD11c promoter in nonhairy cells may lie in its activity being controlled by the formation of heterodimers and by upstream control mechanisms. These interacting partners and upstream mechanisms are probably intact in nonhairy cells but may be defective in hairy cells. HCL is not the only hematopoietic malignancy in which constitutive expression of the proto-oncogene junD has been observed. Previous studies have shown that adult T-cell leukemia (ATL) and cutaneous T-cell lymphoma (CTCL) are both associated with chronic expression of JunD.69,70 HCL, ATL, and CTCL are all tartrate-resistant acid phosphatase positive, are associated with infection with types of the human T-cell lymphotropic virus (HTLV), are slow-developing diseases, and have neoplastic lymphocytes that move out of the circulation to infiltrate other areas of the body.71-76 In ATL and CTCL, infiltration occurs in the skin. In HCL, infiltration can also occur in the skin but is more common in the bone marrow, spleen, and liver. The related nature of HCL, ATL, and CTCL is further underscored by the finding that HCL and ATL as well as HCL and CTCL can coexist in the same patient.77-81 In addition, HCL, ATL, and CTCL share the characteristic of being amenable to treatment with pentostatin or chlorodeoxyadenosine.82-86 The molecular and pathogenic similarities of HCL, ATL, and CTCL tend to suggest these malignancies share common origins. The mechanisms by which the expression of the AP-1 family is controlled act both at the transcriptional and posttranscriptional level.59,60,87-100 The posttranscriptional mechanisms include regulation of mRNA stability and the redox modification, phosphorylation, and dimerization of the translated proteins. Phosphorylation is regulated by kinase cascades mediated by the Ras, Rac, and Cdc42 small guanosine triphosphate-binding proteins.101-103 In addition, the products of the dbl and ost proto-oncogenes, which act as exchange factors for Cdc42 and Rac, have also been shown to activate AP-1 kinase signaling.102-105 The activity of Rac and Cdc42 in HCL is particularly intriguing given that these proteins have been shown to regulate the formation of lamellipodia and microspikes/filopodia, respectively.106,107 It is particularly provocative that the formation of these distinct cytoskeletal structures is characteristic of HCL. The products of the ras proto-oncogenes act upstream of both Rac and Cdc42. In addition, Ras can transform fibroblasts in cooperation with JunD,108 and H-Ras has been shown to be chronically expressed in the hairy cell line ESKOL.109 Consequently, we envisioned that chronic Ras activation may play a role in the transformation process associated with HCL and may explain the characteristic appearance of the hairy cell membrane. We sought to determine the role of Ras in HCL and CD11c expression first by inhibiting its expression with the dominant-negative mutant RasN17. The use of this mutant in transient transfection assays inhibited CD11c promoter activity in Mo hairy cells. Consequently, Ras activation appears to contribute to CD11c expression in hairy cells. Next, we expressed in nonhairy cells the dominant-positive ras mutant RasV12. In contrast to exogenous expression of JunD, exogenous expression of RasV12 induced the activity of the CD11c promoter in nonhairy cells. Consequently, Ras activation appears sufficient to induce the CD11c promoter. Ras signals changes in gene expression through 4 main pathways.40-46 One of these pathways is mediated by the kinases MEK1 and MEK2, which are specifically inhibited with the drug U0126.47 Consequently, we used U0126 to further demonstrate the role of Ras in controlling hairy cell expression of CD11c. In the hairy cell line EH, U0126 repressed both the activity of the CD11c promoter and the surface expression of the CD11c protein. However, in the hairy cell lines Mo and HK, U0126 activated the CD11c promoter. Consequently, in EH cells, Ras signals to the CD11c promoter in a manner dependent upon MEK1/2, whereas in Mo and HK cells it signals in a way that is MEK1/2 independent. These results suggest that in EH cells, activating mutations are present at or upstream of MEK1/2 in the Raf/MEK/ERK pathway of Ras signaling. U0126 then acts to block the downstream events resulting from these mutations including expression of CD11c. In contrast, our data suggest that in Mo and HK cells, activating mutations are present either downstream of MEK1/2 and/or in Ras signaling pathways other than that composed of Raf/MEK and ERK. Under these circumstances, treatment with U0126 serves only to divert signaling to occur more vigorously down alternative Ras pathways, causing CD11c induction. In conclusion, the data presented here establish a link between HCL and activation of the proto-oncogenes junD and ras. These findings thus provide a basis for the development of new therapeutic strategies. The potential for development of such novel approaches to the treatement of HCL is indicated by the observation that the MEK1/2 inhibitor U0126 specifically blocks the proliferation of the hairy cell line EH.
We would like to thank Stratford May, Ken Bridges, Tom Wileman, and Guy Faguet for providing, respectively, the cell lines MEG-01, K562, Jurkat, and EH and HK. James Brayer provided expert technical assistance and Gregory Tyler provided expert advice relating to the culture of the MEG-01 cell line. Russell L. McBride provided invaluable help in the culturing of the hairy cell line HK, and we are indebted to Michael Birrer for the use of his pCMV and pTAM67 constructs. We would like to thank John Kyriakis for kindly providing the expression constructs pRasN17 and pRasV12 and Yosef Shaul for providing the expression construct RSV-hjD. Finally, we would like to thank Alessandro Alessandrini for invaluable discussions during the preparation of the manuscript.
Submitted January 31, 2002; accepted December 5, 2002.
Prepublished online as Blood First Edition Paper, February 6, 2003; DOI 10.1182/blood-2002-01-0324.
Supported by the Centre National de la Recherche Scientifique; the Fondation pour la Recherche Medicale; National Institutes of Health grants DK50305, DK43351, and DK50779; grant DHP-116 from the American Cancer Society; a research grant from Ortho Biotech; a Cancer Research Institute Fellowship award (C.S.S.); and an American Cancer Society Fellowship award (O.C.F.). Additional support was provided by grant DAMD17-00-1-0255. In regard to this grant, the US Army Medical Research Acquisition Activity (Fort Detrick, MD) is the awarding and administering acquisition office.
The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734.
Reprints: Carl Simon Shelley, Renal Unit, Massachusetts General Hospital, 149 13th St, Charlestown, MA 02129; e-mail: shelley{at}receptor.mgh.harvard.edu.
1.
Bouroncle BA, Wiseman BK, Doan CA.
Leukemic reticuloendotheliosis.
Blood.
1958;13:609-630
2.
Schwarting R, Stein H, Wang CY.
The monoclonal antibodies 3. Golde DW, Stevens RH, Quan SG, Saxon A. Immunoglobulin synthesis in hairy cell leukemia. Brit J Haematol. 1977;35:359-365[Medline] [Order article via Infotrieve].
4.
Saxon A, Stevens RH, Golde DW.
T-lymphocyte varient of hairy-cell leukemia.
Ann Int Med.
1978;88:323-326
5.
Arnaout MA.
Structure and function of the leukocyte adhesion molecules CD11/CD18.
Blood.
1990;75:1037-1050
6.
Ogura M, Morishima Y, Ohno R, et al.
Establishment of a novel human megakaryoblastic leukemia cell line, MEG-01, with positive Philadelphia chromosome.
Blood.
1985;66:1384-1392
7.
Faguet GB, Satya-Prakash KL, Agee JF.
Cytochemical, cytogenetic, immunophenotypic and tumorigenic characterization of two hairy cell lines.
Blood.
1988;71:422-429
8.
Shelley CS, Farokhzad OC, Arnaout MA.
Identification of cell-specific and developmentally regulated nuclear factors that direct myeloid and lymphoid expression of the CD11a gene.
Proc Natl Acad Sci U S A.
1993;90:5364-5368
9.
López-Cabrera M, Nueda A, Vara A, Garcia-Aguilar J, Tugores A, Corbí AL.
Characterization of the p150,95 leukocyte integrin
10.
Potter H, Weir L, Leder P.
Enhancer-dependent expression of human kappa immunoglobulin genes introduced into mouse pre-B lymphocytes by electroporation.
Proc Natl Acad Sci U S A.
1984;81:7161-7165
11.
Shelley CS, Arnaout MA.
The promoter of the CD11b gene directs myeloid-specific and developmentally regulated expression.
Proc Natl Acad Sci U S A.
1991;88:10525-10529 12. Farokhzad OC, Shelley CS, Arnaout MA. Induction of the CD11b gene during activation of the monocytic cell line U937 requires a novel nuclear factor MS-2. J Immunol. 1996;157:5597-5605[Abstract].
13.
Saxon A, Stevens RH, Golde DW.
T-lymphocyte varient of hairy-cell leukemia.
Ann Intern Med.
1978;88:323-326
14.
Saxon A, Stevens RH, Quan SG, Golde DW.
Immunologic characterization of hairy cell leukemias in continuous culture.
J Immunol.
1978;120:777-782 15. Noti JD, Reinemann BC, Petrus MN. Sp1 binds two sites in the CD11c promoter in vivo specifically in myeloid cells and cooperates with AP1 to activate transcription. Mol Cell Biol. 1996;16:2940-2950[Abstract].
16.
López-Rodríguez C, Chen H-M, Tenen DG, Corbí AL.
Identification of Sp1-binding sites in the CD11c (p150,95
17.
Noti JD.
Sp3 mediates transcriptional activation of the leukocyte integrin genes CD11C and CD11B and cooperates with c-Jun to activate CD11C.
J Biol Chem.
1997;272:24038-24045
18.
Farokhzad OC, Teodoridis JM, Park H, Arnaout MA, Shelley CS.
CD43 gene expression is mediated by a nuclear factor which binds pyrimidine-rich single-stranded DNA.
Nucleic Acids Res.
2000;28:2256-2267
19.
Shelley CS, Teodoridis JM, Park H, Farokhzad OC, Böttinger EP, Arnaout MA.
During differentiation of the monocytic cell line U937, Pur
20.
Karim FD, Urness LD, Thummel CS, et al.
The ETS domain: a new DNA-binding motif that recognizes a purine-rich core DNA sequence.
Genes Dev.
1990;4:1451-1453
21.
Rubio MA, López-Rodríguez C, Nueda A, et al.
Granulocyte-macrophage colony-stimulating factor, phorbol ester, and sodium butyrate induce the CD11c integrin gene promoter activity during myeloid cell differentiation.
Blood.
1995;86:3715-3724 22. Lassar AB, Buskin JN, Lockshon D, et al. MyoD is a sequence-specific DNA binding protein requiring a region of myc homology to bind to the muscle creatine kinase enhancer. Cell. 1989;58:823-831[CrossRef][Medline] [Order article via Infotrieve]. 23. López-Rodríguez C, Kluin-Nelemans HC, Corbí AL. AP-1 regulates the basal and developmentally induced transcription of the CD11c leukocyte integrin gene. J Immunol. 1996;156:3780-3787[Abstract].
24.
Aragonés J, López-Rodríguez C, Corbí A, et al.
Dithiocarbamates trigger differentiation and induction of CD11c gene through AP-1 in the myeloid lineage.
J Biol Chem.
1996;271:10924-10931 25. Noti JD, Reinemann BC, Petrus MN. Regulation of the leukocyte integrin gene CD11c is mediated by AP1 and Ets transcription factors. Mol Immunol. 1996;33:115-127[CrossRef][Medline] [Order article via Infotrieve]. 26. Vivanco Ruiz Md M, Bugge TH, Hirschmann P, Stunnenberg HG. Functional characterization of a natural retinoic acid responsive element. EMBO J. 1991;10:3829-3838[Medline] [Order article via Infotrieve]. 27. Corbí AL, López-Rodríguez C. CD11c integrin gene promoter activity during myeloid differentiation. Leuk Lymphoma. 1997;25:415-425[Medline] [Order article via Infotrieve]. 28. López-Rodríguez C, Corbí AL. PU.1 negatively regulates the CD11c integrin gene promoter through recognition of the major transcriptional start site. Eur J Immunol. 1997;27:1843-1847[Medline] [Order article via Infotrieve]. 29. Smale ST, Baltimore D. The initiator as a transcriptional control element. Cell. 1989;57:103-113[CrossRef][Medline] [Order article via Infotrieve]. 30. Weis L, Reinberg D. Transcription by RNA polymerase II: initiator-directed formation of transcription-competent complexes. FASEB J. 1992;6:3300-3309[Abstract]. 31. Akira S, Isshiki H, Sugita T, et al. A nuclear factor for IL-6 expression (NF-IL6) is a member of a C/EBP family. EMBO J. 1990;9:1897-1906[Medline] [Order article via Infotrieve].
32.
Pearse RN, Feinman R, Shuai K, Darnell JE Jr, Ravetch JV.
Interferon 33. Graf T. Myb: a transcriptional activator linking proliferation and differentiation. Curr Opin Genet Dev. 1992;2:249-255[CrossRef][Medline] [Order article via Infotrieve]. 34. Brown PH, Alani P, Preis LH, Szabo E, Birrer MJ. Suppression of oncogene-induced transformation by a deletion mutant of c-jun. Oncogene. 1993;8:877-886[Medline] [Order article via Infotrieve].
35.
Dong Z, Birrer MJ, Watts RG, Matrisian LM, Colburn NH.
Blocking of tumor promoter-induced AP-1 activity inhibits induced transformation in JB mouse epidermal cells.
Proc Natl Acad Sci U S A.
1994;91:609-613
36.
Feig LA, Cooper GM.
Inhibition of NIH 3T3 cell proliferation by a mutant ras protein with preferential affinity for GDP.
Mol Cell Biol.
1988;8:3235-3243 37. Berger I, Shaul Y. The human junD gene is positively and selectively autoregulated. DNA Cell Biol. 1994;13:249-255[Medline] [Order article via Infotrieve]. 38. Sweet RW, Yokoyama S, Kamata T, Feramisco JR, Rosenberg M, Gross M. The product of ras is a GTPase and the T24 oncogenic mutant is deficient in this activity. Nature. 1984;311:273-275[CrossRef][Medline] [Order article via Infotrieve]. 39. Karin M, Liu ZG, Zandi E. AP-1 function and regulation. Curr Opin Cell Biol. 1997;9:240-246[CrossRef][Medline] [Order article via Infotrieve]. 40. Shields JM, Pruitt K, McFall A, Shaub A, Der CJ. Understanding Ras: `it ain't over `til it's over.' Trends Cell Biol. 2000;10:147-154[CrossRef][Medline] [Order article via Infotrieve]. 41. Avruch J, Khokhlatchev A, Kyriakis JM, et al. Ras activation of the Raf kinase: tyrosine kinase recruitment of the MAP kinase cascade. Recent Prog Horm Res. 2001;56:127-155[Abstract]. 42. Kerkhoff E, Rapp UR. The Ras-Raf relationship: an unfinished puzzle. Adv Enzyme Regul. 2001;41:261-267[CrossRef][Medline] [Order article via Infotrieve]. 43. Bar-Sagi D, Hall A. Ras and Rho GTPases: a family reunion. Cell. 2000;103:227-238[CrossRef][Medline] [Order article via Infotrieve]. 44. Jun T, Gjoerup O, Roberts TM. Tangled webs: evidence of cross-talk between c-Raf-1 and Akt. Sci STKE. 1999;1999:PE1. 45. Feig LA, Urano T, Cantor S. Evidence for a Ras/Ral signaling cascade. Trends Biochem Sci. 1996;21:438-441[CrossRef][Medline] [Order article via Infotrieve]. 46. Wolthuis RM, Bos JL. Ras caught in another affair: the exchange factors for Ral. Curr Opin Genetic Dev. 1999;9:112-117[CrossRef][Medline] [Order article via Infotrieve].
47.
Favata MF, Horiuchi KY, Manos EJ, et al.
Identification of a novel inhibitor of mitogen-activated protein kinase kinase.
J Biol Chem.
1998;273:18623-18632 48. Sundstrom C, Nilsson K. Establishment and characterization of a human histiocytic lymphoma cell line (U-937). Int J Cancer. 1976;17:565-577[Medline] [Order article via Infotrieve]. 49. Shaulian E, Karin M. AP-1 in cell proliferation and survival. Oncogene. 2001;20:2390-2400[CrossRef][Medline] [Order article via Infotrieve].
50.
Heintz NH, Janssen YM, Mossman BT.
Persistent induction of c-fos and c-jun expression by asbestos.
Proc Natl Acad Sci U S A.
1993;90:3299-3303 51. Yamanishi DT, Buckmeier JA, Meyskens FL Jr. Expression of c-jun, jun-B, and c-fos proto-oncogenes in human primary melanocytes and metastatic melanomas. J Invest Dermatol. 1991;97:349-353[CrossRef][Medline] [Order article via Infotrieve]. 52. Fujimoto M, Sheridan PJ, Sharp ZD, Weaker FJ, Kagan-Hallet KS, Story JL. Proto-oncogene analysis in brain tumors. J Neurosurg. 1989;70:910-915[Medline] [Order article via Infotrieve]. 53. Neyns B, Katesuwanasing D, Vermeij J, et al. Expression of the jun family of genes in human ovarian cancer and normal ovarian surface epithelium. Oncogene. 1996;12:1247-1257[Medline] [Order article via Infotrieve]. 54. Miller AD, Curran T, Verma IM. c-fos protein can induce cellular transformation: a novel mechanism of activation of a cellular oncogene. Cell. 1984;36:51-60[CrossRef][Medline] [Order article via Infotrieve].
55.
Lee WMF, Lin C, Curran T.
Activation of the transforming potential of the human fos proto-oncogene requires message stabilization and results in increased amounts of partially modified fos protein.
Mol Cell Biol.
1988;8:5521-5527 56. Raymond V, Atwater JA, Verma IM. Removal of an mRNA destabilizing element correlates with the increased oncogenicity of proto-oncogene fos. Oncogene Res. 1989;5:1-12[Medline] [Order article via Infotrieve].
57.
Schütte J, Minna JD, Birrer MJ.
Deregulated expression of human c-jun transforms primary rat embryo cells in cooperation with an activated c-Ha-ras gene and transforms Rat-1a cells as a single gene.
Proc Natl Acad Sci U S A.
1989;86:2257-2261 58. Schütte J, Viallet J, Nau M, Segal S, Fedorko J, Minna JD. jun-B inhibits and c-fos stimulates the transforming and trans-activating activities of c-jun. Cell. 1989;59:987-997[CrossRef][Medline] [Order article via Infotrieve].
59.
Abate C, Patel L, Rauscher FJ III, Curran T.
Redox regulation of fos and jun DNA-binding activity in vitro.
Science.
1990;249:1157-1161 60. Boyle WJ, Smeal T, Defize LHK, et al. Activation of protein kinase C decreases phosphorylation of c-jun at sites that negatively regulate its DNA-binding activity. Cell. 1991;64:573-584[CrossRef][Medline] [Order article via Infotrieve]. 61. Van Beveren C, Van Straaten F, Curran T, Méller R, Verma IM. Analysis of FBJ-MuSV provirus and c-fos (mouse) gene reveals that viral and cellular fos gene products have different carboxy termini. Cell. 1983;32:1241-1255[CrossRef][Medline] [Order article via Infotrieve]. 62. Van Beveren C, Enami S, Curran T, Verma IM. FBR murine osteosarcoma virus, II: nucleotide sequence of the provirus reveals that the genome contains sequences acquired from two cellular genes. Virology. 1984;135:229-243[CrossRef][Medline] [Order article via Infotrieve].
63.
Nishizawa M, Goto N, Kawai S.
An avian transforming retrovirus isolated from a nephroblastoma that carries the fos gene as the oncogene.
J Virol.
1987;61:3733-3740
64.
Maki Y, Bos TJ, Davis C, Starbuck M, Vogt PK.
Avian sarcoma virus 17 carries the jun oncogene.
Proc Natl Acad Sci U S A.
1987;84:2848-2852 65. Forrest D, Curran T. Crossed signals: oncogenic transcription factors. Curr Opin Genet Dev. 1992;2:19-27[CrossRef][Medline] [Order article via Infotrieve]. 66. Curran T, Miller AD, Zokas L, Verma IM. Viral and cellular fos proteins: a comparative analysis. Cell. 1984;36:259-268[CrossRef][Medline] [Order article via Infotrieve].
67.
Curran T, Van Beveren C, Ling N, Verma IM.
Viral and cellular fos proteins are complexed with a 39,000-dalton cellular protein.
Mol Cell Biol.
1985;5:167-172
68.
Kameda T, Akahori A, Sonobe MH, Suzuki T, Endo T, Iba H.
JunD mutants with spontaneously acquired transforming potential have enhanced transactivating activity in combination with Fra-2.
Proc Natl Acad Sci U S A.
1993;90:9369-9373
69.
Qin J-Z, Dummer R, Burg G, Döbbeling U.
Constitutive and interleukin-7/interleukin-15 stimulated DNA binding of Myc, Jun, and novel Myc-like proteins in cutaneous T-cell lymphoma cells.
Blood.
1999;93:260-267
70.
Mori N, Fujii M, Iwai K, et al.
Constitutive activation of transcription factor AP-1 in primary adult T-cell leukemia cells.
Blood.
2000;95:3915-3921
71.
Blayney DW, Jaffe ES, Blattner WA, et al.
The human T-cell leukemia/lymphoma virus associated with American adult T-cell leukemia/lymphoma.
Blood.
1983;62:401-405 72. Naeim F, Capostagno VJ, Johnson CE Jr, Lehrer R, Gatti RA. Sézary syndrome: tartrate-resistant acid phosphatase in the neoplastic cells. Am J Clin Pathol. 1979;71:528-533[Medline] [Order article via Infotrieve]. 73. Usui T, Konishi H, Sawada H, Uchino H. Existence of tartrate-resistant acid phosphatase activity in differentiated lymphoid leukemic cells. Am J Hematol. 1982;12:47-54[Medline] [Order article via Infotrieve]. 74. Gallo RC. Kaplan memorial lecture: the family of human lymphotropic retroviruses called HTLV:HTLV-I in adult T-cell leukemia (ATL), HTLV-II in hairy cell leukemias, and HTLV-III in AIDS. Princess Takamatsu Symp. 1984;15:13-38[Medline] [Order article via Infotrieve]. 75. Wachsman W, Golde DW, Chen IS. Hairy cell leukemia and human T cell leukemia virus. Semin Oncol. 1984;11:446-450[Medline] [Order article via Infotrieve]. 76. Clore LS Jr, Stafford CT. Chronic urticaria as a presenting sign of hairy cell leukemia. Allergy Asthma Proc. 1999;20:51-55[Medline] [Order article via Infotrieve]. 77. Crump M, Sutton DM, Pantalony D. Sézary syndrome in a patient with hairy cell leukemia in remission. Cancer. 1991;68:829-833[CrossRef][Medline] [Order article via Infotrieve].
78.
Zucker-Franklin D, Amorosi EL, Ritz ND.
Evolution of Sézary syndrome in the course of hairy cell leukemia.
Blood.
1982;59:1181-1190
79.
Demeter J, Paloczi K.
Observations on the development of T-cell leukaemia in the patient successfully treated by interferon-
80.
Knecht H, Sarraj A, Delacretaz F, Bachmann E, Clement F.
Genotypic and phenotypic evidence of T-cell leukemia in a patient successfully treated by interferon- 81. Paolini R, Poletti A, Ramazzina E, et al. Co-existence of cutaneous T-cell lymphoma and B hairy cell leukemia. Am J Hematol. 2000;64:197-202[CrossRef][Medline] [Order article via Infotrieve]. 82. Dearden CE, Matutes E, Catovsky D. Clinical overview of pentostatin (Nipent) use in lymphoid malignancies. Semin Oncol. 2000;27:22-26[Medline] [Order article via Infotrieve]. 83. Ho AD, Suciu S, Stryckmans P, et al. Pentostatin (Nipent) in T-cell malignancies: Leukemia Cooperative Group and the European Organization for Research and Treatment of Cancer. Semin Oncol. 2000;27:52-57[Medline] [Order article via Infotrieve]. 84. Beutler E. Cladribine (2-chlorodeoxyadenosine). Lancet. 1992;340:952-956[CrossRef][Medline] [Order article via Infotrieve].
85.
Piro LD.
2-Chlorodeoxyadenosine treatment of lymphoid malignancies.
Blood.
1992;79:843-845 86. Piro LD, Carrera CJ, Carson DA, Beutler E. Lasting remissions in hairy-cell leukemia induced by a single infusion of 2-chlorodeoxyadenosine. N Engl J Med. 1990;322:1117-1121[Abstract]. 87. Angel P, Imagawa M, Chiu R, et al. Phorbol ester-inducible genes contain a common cis element recognized by a TPA-modulated trans-acting factor. Cell. 1987;49:729-739[CrossRef][Medline] [Order article via Infotrieve]. 88. Lamph WW, Wamsley P, Sassone-Corsi P, Verma IM. Induction of proto-oncogene JUN/Ap-1 by serum and TPA. Nature. 1988;334:629-631[CrossRef][Medline] [Order article via Infotrieve]. 89. Angel P, Hattori K, Smeal T, Karin M. The jun proto-oncogene is positively autoregulated by its product, Jun/Ap-1. Cell. 1988;55:875-885[CrossRef][Medline] [Order article via Infotrieve]. 90. Wilson T, Treisman R. Removal of poly(A) and consequent degradation of c-fos mRNA facilitated by 3' AU-rich sequences. Nature. 1988;336:396-399[CrossRef][Medline] [Order article via Infotrieve]. 91. Nakamura T, Datta R, Kharbanda S, Kufe D. Regulation of jun and fos gene expression in human monocytes by the macrophage colony-stimulating factor. Cell Growth Differ. 1991;2:267-272[Abstract]. 92. Abate C, Luk D, Curran T. A ubiquitous nuclear protein stimulates the DNA-binding activity of fos and jun indirectly. Cell Growth Differ. 1990;1:455-462[Abstract].
93.
Abate C, Luk D, Gentz R, Rauscher FJ III, Curran T.
Expression and purification of the leucine zipper and DNA-binding domains of Fos and Jun: both Fos and Jun contact DNA directly.
Proc Natl Acad Sci U S A.
1990;87:1032-1036 94. Xanthoudakis S, Curran T. Identification and characterization of Ref-1, a nuclear protein that facilitates AP-1 DNA-binding activity. EMBO J. 1992;11:653-665[Medline] [Order article via Infotrieve].
95.
Curran T, Morgan JI.
Superinduction of c-fos by nerve growth factor in the presence of peripherally active benzodiazepines.
Science.
1985;229:1265-1268
96.
Barber JR, Verma IM.
Modification of fos proteins: phosphorylation of c-fos, but not v-fos, is stimulated by 12-tetradecanoyl-phorbol-13- acetate and serum.
Mol Cell Biol.
1987;7:2201-2211 97. Müller R, Bravo R, Müller D, Kurz C, Renz M. Different types of modification in c-fos and its associated protein p39: modulation of DNA binding by phosphoylation. Oncogene Res. 1987;2:19-32[Medline] [Order article via Infotrieve].
98.
Franza BR Jr, Rauscher FJ III, Josephs SF, Curran T.
The Fos complex and Fos-related antigens recognize sequence elements that contain AP-1 binding sites.
Science.
1988;239:1150-1153 99. Pulverer BJ, Kyriakis JM, Avruch J, Nikolakaki E, Woodgett JR. Phosphorylation of c- jun mediated by MAP kinases. Nature. 1991;353:670-674[CrossRef][Medline] [Order article via Infotrieve].
100.
Franklin CC, Sanchez V, Wagner F, Woodgett JR, Kraft AS.
Phorbol ester-induced amino-terminal phosphorylation of human JUN but not JUNB regulates transcriptional activation.
Proc Natl Acad Sci U S A.
1992;89:7247-7251
101.
Minden A, Lin A, McMahon M, et al.
Differential activation of ERK and JNK mitogen-activated protein kinases by Raf-1 and MEKK.
Science.
1994;266:1719-1723 102. Coso OA, Chiariello M, Yu J-C, et al. The small GTP-binding proteins Rac1 and Cdc42 regulate the activity of the JNK/SAPK signaling pathway. Cell. 1995;81:1137-1146[CrossRef][Medline] [Order article via Infotrieve]. 103. Minden A, Lin A, Claret F-X, Abo A, Karin M. Selective activation of the JNK signaling cascade and c-Jun transcriptional activity by the small GTPases Rac and Cdc42Hs. Cell. 1995;81:1147-1157[CrossRef][Medline] [Order article via Infotrieve].
104.
Hart MJ, Eva A, Zangrilli D, et al.
Cellular transformation and guanine nucleotide exchange activity are catalyzed by a common domain on the dbl oncogene product.
J Biol Chem.
1994;269:62-65 105. Horii Y, Beeler JF, Sakaguchi K, Tachibana M, Miki T. A novel oncogene, ost, encodes a guanine nucleotide exchange factor that potentially links Rho and Rac signaling pathways. EMBO J. 1994;13:4776-4786[Medline] [Order article via Infotrieve]. 106. Ridley AJ, Hall A. The small GTP-binding protein rho regulates the assembly of focal adhesions and actin stress fibers in response to growth factors. Cell. 1992;70:389-399[CrossRef][Medline] [Order article via Infotrieve]. 107. Ridley AJ, Paterson HF, Johnston CL, Diekmann D, Hall A. The small GTP-binding protein rac regulates growth factor-induced membrane ruffling. Cell. 1992;70:401-410[CrossRef][Medline] [Order article via Infotrieve]. 108. Vandel L, Montreau N, Vial E, Pfarr CM, Binetruy B, Castellazzi M. Stepwise transformation of rat embryo fibroblasts: c-Jun, JunB, or JunD can cooperate with Ras for focus formation, but a c-Jun-containing heterodimer is required for immortalization. Mol Cell Biol. 1996;16:1881-1888[Abstract]. 109. Harvey WH, Harb OS, Kosak ST, Sheaffer JC, Lowe LR, Heerema NA. Interferon-alpha-2b downregulation of oncogenes H-ras, c-raf-2, c-kit, c-myc, c-myb and c-fos in ESKOL, a hairy cell leukemic line, results in temporal perturbation of signal transduction cascade. Leuk Res. 1994;18:577-585[CrossRef][Medline] [Order article via Infotrieve].
© 2003 by The American Society of Hematology.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
 |
|
  T. Ito, C. Nishiyama, N. Nakano, M. Nishiyama, Y. Usui, K. Takeda, S. Kanada, K. Fukuyama, H. Akiba, T. Tokura, et al. Roles of PU.1 in monocyte- and mast cell-specific gene regulation: PU.1 transactivates CIITA pIV in cooperation with IFN-{gamma} Int. Immunol., July 1, 2009; 21(7): 803 - 816. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Galiegue-Zouitina, L. Delestre, C. Dupont, X. Troussard, and C. S. Shelley Underexpression of RhoH in Hairy Cell Leukemia Cancer Res., June 15, 2008; 68(12): 4531 - 4540. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Chaigne-Delalande, L. Deuve, E. Reuzeau, C. Basoni, D. Lafarge, C. Varon, F. Tatin, G. Anies, R. Garand, I. Kramer, et al. RhoGTPases and p53 Are Involved in the Morphological Appearance and Interferon-{alpha} Response of Hairy Cells Am. J. Pathol., February 1, 2006; 168(2): 562 - 573. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Vanhentenrijk, C. De Wolf-Peeters, and I. Wlodarska Comparative expressed sequence hybridization studies of hairy cell leukemia show uniform expression profile and imprint of spleen signature Blood, July 1, 2004; 104(1): 250 - 255. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 2003 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
Top
Abstract
Introduction
