Key points are not available for this paper at this time.
Bcr-Abl is the constitutively active protein-tyrosine kinase expressed as a result of the Philadelphia translocation in chronic myelogenous leukemia. Bcr-Abl is coupled to many of the same signaling pathways normally regulated by hematopoietic cytokines. Recent work shows that Hck, a member of the Src tyrosine kinase family with myeloid-restricted expression, associates with and is activated by Bcr-Abl. Here we investigated the mechanism of Hck interaction with Bcr-Abl and the requirement for Hck activation in Bcr-Abl transformation signaling. Binding studies demonstrated that the Hck SH3 and SH2 domains are sufficient for interaction with Bcr-Ablin vitro. Hck binding localizes to the Abl SH2, SH3, and kinase domains as well as the distal portion of the C-terminal tail. To address the requirement for endogenous Src family kinase activation in Bcr-Abl signaling, a kinase-defective mutant of Hck was stably expressed in the cytokine-dependent myeloid leukemia cell line DAGM. Kinase-defective Hck dramatically suppressed Bcr-Abl-induced outgrowth of these cells in the absence of cytokine compared with a control cell line expressing β-galactosidase. In contrast, kinase-defective Hck did not affect cell proliferation in response to interleukin-3, suggesting that the effect is specific for Bcr-Abl. These data show that Hck interacts with Bcr-Abl through a complex mechanism involving kinase-dependent and -independent components and that interaction with Hck or other Src family members is essential for transformation signaling by Bcr-Abl. Bcr-Abl is the constitutively active protein-tyrosine kinase expressed as a result of the Philadelphia translocation in chronic myelogenous leukemia. Bcr-Abl is coupled to many of the same signaling pathways normally regulated by hematopoietic cytokines. Recent work shows that Hck, a member of the Src tyrosine kinase family with myeloid-restricted expression, associates with and is activated by Bcr-Abl. Here we investigated the mechanism of Hck interaction with Bcr-Abl and the requirement for Hck activation in Bcr-Abl transformation signaling. Binding studies demonstrated that the Hck SH3 and SH2 domains are sufficient for interaction with Bcr-Ablin vitro. Hck binding localizes to the Abl SH2, SH3, and kinase domains as well as the distal portion of the C-terminal tail. To address the requirement for endogenous Src family kinase activation in Bcr-Abl signaling, a kinase-defective mutant of Hck was stably expressed in the cytokine-dependent myeloid leukemia cell line DAGM. Kinase-defective Hck dramatically suppressed Bcr-Abl-induced outgrowth of these cells in the absence of cytokine compared with a control cell line expressing β-galactosidase. In contrast, kinase-defective Hck did not affect cell proliferation in response to interleukin-3, suggesting that the effect is specific for Bcr-Abl. These data show that Hck interacts with Bcr-Abl through a complex mechanism involving kinase-dependent and -independent components and that interaction with Hck or other Src family members is essential for transformation signaling by Bcr-Abl. chronic myelogenous leukemia acute lymphocytic leukemia polyacrylamide gel electrophoresis glutathioneS-transferase interleukin β-galactosidase 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide Several human leukemias are characterized by the presence of the Philadelphia chromosome which results from the translocation of the c-abl locus on chromosome 9 and the bcr locus chromosome 22 (reviewed in Refs. 1.Gotoh A. Broxmeyer H.E. Curr. Opin. Hematol. 1997; 4: 3-11Crossref PubMed Scopus (64) Google Scholar and 2.Sawyers C.L. N. Engl. J. Med. 1999; 340: 1330-1340Crossref PubMed Scopus (1293) Google Scholar). This translocation results in the expression of a family of chimeric Bcr-Abl oncoproteins associated with specific leukemias (3.de Klein A. van Kessel A.D. Grosveld G. Bartram C.R. Hagemeijer A. Bootsma D. Spurr N.K. Heisterkamp N. Groffen J. Stephenson J.R. Nature. 1982; 300: 765-767Crossref PubMed Scopus (1059) Google Scholar, 4.Groffen J. Stephenson J.R. Heisterkamp N. de Klein A. Bartram C.R. Grosfeld G. Cell. 1984; 36: 93-99Abstract Full Text PDF PubMed Scopus (1263) Google Scholar, 5.Heisterkamp N. Stephenson J.R. Groffen J. Hansen P.F. de Klein A. Bartram C.R. Grosveld G. Nature. 1983; 306: 239-242Crossref PubMed Scopus (630) Google Scholar, 6.Shtivelman E. Lifshitz B. Gale R.P. Canaani E. Nature. 1985; 315: 550-554Crossref PubMed Scopus (1277) Google Scholar). Chronic myelogenous leukemia (CML)1 results from the 210-kDa form of Bcr-Abl (p210), while acute lymphocytic leukemia (ALL) is associated with a 185-kDa form (p185) (7.Ben-Neriah Y. Daley G.Q. Mes-Masson A.M. Witte O.N. Baltimore D. Science. 1986; 233: 212-214Crossref PubMed Scopus (662) Google Scholar, 8.Hermans A. Heisterkamp N. von Lindern M. van Baal S. Meijer D. van der Plas D. Wiedemann L.M. Groffen J. Bootsma D. Grosveld G. Cell. 1987; 51: 33-40Abstract Full Text PDF PubMed Scopus (308) Google Scholar). Both forms of Bcr-Abl are constitutively active protein-tyrosine kinases that have been shown to transform cells in culture and to produce CML- and ALL-like syndromes in transgenic mice, providing strong evidence that Bcr-Abl is responsible for the development of these leukemias (9.Daley G.Q. Baltimore D. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 9312-9316Crossref PubMed Scopus (512) Google Scholar, 10.Daley G.Q. Van Etten R.A. Baltimore D. Science. 1990; 247: 824-830Crossref PubMed Scopus (1934) Google Scholar, 11.Heisterkamp N. Jenster G. ten Hoeve J. Zovich D. Pattengale P.K. Groffen J. Nature. 1990; 344: 251-253Crossref PubMed Scopus (596) Google Scholar). Bcr-Abl has been shown to activate multiple signal transduction pathways normally associated with the growth, survival, and differentiation of hematopoietic cells. For example, tyrosine-phosphorylated Bcr-Abl can interact directly with the Grb-2/Sos guanine nucleotide exchange factor, leading to the activation of Ras (12.Pendergast A.M. Quilliam L.A. Cripe L.D. Bassing C.H. Dai Z. Li N. Batzer A. Rabun K.M. Der C.J. Schlessinger J. Gishizky M.L. Cell. 1993; 75: 175-185Abstract Full Text PDF PubMed Scopus (595) Google Scholar, 13.Puil L. Liu J. Gish G. Mbamalu G. Bowtell D. Pelicci P.G. Arlinghaus R. Pawson T. EMBO J. 1994; 13: 764-773Crossref PubMed Scopus (401) Google Scholar). Bcr-Abl can also activate Ras via Shc, an adaptor protein that couples the receptors for many growth factors and cytokines to the Grb2/Sos complex (14.Goga A. McLaughlin J. Afar D.E.H. Saffran D.C. Witte O.N. Cell. 1995; 82: 981-988Abstract Full Text PDF PubMed Scopus (257) Google Scholar). Other work has identified Crk-L as a binding partner and substrate for Bcr-Abl (15.Senechal K. Halpern J. Sawyers C.L. J. Biol. Chem. 1996; 271: 23255-23261Abstract Full Text Full Text PDF PubMed Scopus (119) Google Scholar, 16.Heaney C. Kolibaba K. Bhat A. Oda T. Ohno S. Fanning S. Druker B.J. Blood. 1997; 89: 297-306Crossref PubMed Google Scholar). Crk-L may couple Bcr-Abl to the guanine-nucleotide exchange factor C3G, providing an additional connection to Ras activation (17.Nosaka Y. Arai A. Miyasaka N. Miura O. J. Biol. Chem. 1999; 274: 30154-30162Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar). In addition to the Ras pathway, Bcr-Abl is coupled to PI-3K signaling and activation of Akt/PKB kinases downstream (18.Skorski T. Bellacosa A. Nieborowska-Skorska M.N. Majewski M. Martinez R. Choi J.K. Trotta R. Wlodarski P. Perrotti D. Chan T.O. Wasik M.A. Tsichlis P.N. Calabretta B. EMBO J. 1997; 16: 6151-6161Crossref PubMed Scopus (559) Google Scholar). This pathway may promote cytokine-independent survival by Bcr-Abl (19.Franke T.F. Kaplan D.R. Cantley L.C. Cell. 1997; 88: 435-437Abstract Full Text Full Text PDF PubMed Scopus (1529) Google Scholar, 20.Zhou S.Y. Baltimore D. Cantley L.C. Kaplan D.R. Franke T.F. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 11345-11350Crossref PubMed Scopus (324) Google Scholar). Other studies have demonstrated that Bcr-Abl induces activation of Stat transcription factors, which have also been implicated in proliferative and survival signaling in a wide variety of hematopoietic cell types (21.Carlesso N. Frank D.A. Griffin J.D. J. Exp. Med. 1996; 183: 811-820Crossref PubMed Scopus (436) Google Scholar, 22.Ilaria Jr., R.L. Van Etten R.A. J. Biol. Chem. 1996; 271: 31704-31710Abstract Full Text Full Text PDF PubMed Scopus (439) Google Scholar, 23.Shuai K. Halpern J. ten Hoeve J. Rao X.P. Sawyers C.L. Oncogene. 1996; 13: 247-254PubMed Google Scholar, 24.Nieborowska-Skorska M. Wasik M.A. Slupianek A. Salomoni P. Kitamura T. Calabretta B. Skorski T. J. Exp. Med. 1999; 189: 1229-1242Crossref PubMed Scopus (245) Google Scholar). All of these signaling pathways involve components with SH2 and SH3 domains and are dependent upon tyrosine phosphorylation. Although Bcr-Abl possesses a constitutively active tyrosine kinase domain, recent work suggests that it may initiate signaling by activating other nonreceptor tyrosine kinases, including members of the Fps/Fes and Src families (25.Danhauser-Riedl S. Warmuth M. Druker B.J. Emmerich B. Hallek M. Cancer Res. 1996; 56: 3589-3596PubMed Google Scholar, 26.Warmuth M. Bergmann M. Priess A. Hauslmann K. Emmerich B. Hallek M. J. Biol. Chem. 1997; 272: 33260-33270Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar, 27.Ernst T.J. Slattery K.E. Griffin J.D. J. Biol. Chem. 1994; 269: 5764-5769Abstract Full Text PDF PubMed Google Scholar, 28.Lionberger J.M. Smithgall T.E. Cancer Res. 2000; 60: 1097-1103PubMed Google Scholar). Regarding the Src family, Bcr-Abl has been shown to associate directly with Lyn and Hck in 32Dcl3 cells. This interaction correlates with increased Lyn and Hck tyrosine kinase activity (25.Danhauser-Riedl S. Warmuth M. Druker B.J. Emmerich B. Hallek M. Cancer Res. 1996; 56: 3589-3596PubMed Google Scholar). More recently, Hck has been shown to phosphorylate p210 Bcr-Abl on Tyr 177, the site responsible for direct recruitment of Grb-2/Sos through the Grb-2 SH2 domain (26.Warmuth M. Bergmann M. Priess A. Hauslmann K. Emmerich B. Hallek M. J. Biol. Chem. 1997; 272: 33260-33270Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar). This result suggests that Src family kinases may facilitate the coupling of Bcr-Abl to Ras and other signaling pathways related to transformation. In this study, we investigated the mechanism of Hck interaction with Bcr-Abl. We observed that the Hck SH2 and SH3 domains bind strongly to recombinant Bcr-Ablin vitro. Constitutive binding was observed with the SH3 domain, while SH2-mediated binding was found to require Bcr-Abl autophosphorylation. In reciprocal experiments, we observed that multiple regions of Abl, including the SH3, SH2, and kinase domains as well as the distal portion of the C-terminal region interact directly with Hck. We also found that a kinase-inactive mutant of Hck strongly suppressed Bcr-Abl proliferative signals in cytokine-dependent myeloid leukemia cells, suggesting that activation of Hck or other members of the Src kinase family is required for Bcr-Abl transformation signaling. Activation of Src family kinases by Bcr-Abl may contribute to the diversity of signaling pathways activated by this transforming tyrosine kinase. Construction of pGEX-2T vectors and expression of the noncatalytic regions of Hck as GST fusion proteins is described elsewhere (29.Briggs S.D. Bryant S.S. Jove R. Sanderson S.D. Smithgall T.E. J. Biol. Chem. 1995; 270: 14718-14724Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar). Briefly,Escherichia coli DH5α were transformed with pGEX-Hck constructs, and GST fusion protein expression was induced with isopropyl-β-d-thiogalactopyranoside. Following induction, recombinant fusion proteins were isolated from clarified cell extracts with glutathione-agarose beads. The concentration of each protein was determined on Coomassie-stained gels by two-dimensional laser densitometry using bovine serum albumin as a standard. For the binding reactions, wild-type and kinase-defective forms of Bcr-Abl were expressed in Sf-9 insect cells using recombinant baculoviruses as described elsewhere (28.Lionberger J.M. Smithgall T.E. Cancer Res. 2000; 60: 1097-1103PubMed Google Scholar). Immobilized GST fusion proteins (20 μg) or GST alone as a negative control were added to 1 ml aliquots of clarified Sf-9 cell lysates and rotated at 4 °C for 2 h. Fusion proteins were pelleted by centrifugation and washed once with 1.0 ml Hck lysis buffer (50 mm Tris-HCl, pH 7.4, 50 mmNaCl, 1 mm EDTA, 10 mm MgCl2, 1% Triton X-100) followed by three washes with RIPA buffer (50 mm Tris-HCl, pH 7.4, 50 mm NaCl, 1 mm EDTA, 10 mm MgCl2, 1% Triton X-100, 1% sodium deoxycholate, 0.1% SDS). Precipitated proteins were solubilized in SDS-PAGE sample buffer and associated Bcr-Abl was detected by immunoblotting. The coding sequences for the human Abl SH3 and SH2 domains (Gly57–Thr224) and kinase domain (Tyr215–Ile489) were amplified by polymerase chain reaction and subcloned into the baculovirus transfer vector pVL-GST (30.Rogers J.A. Read R.D. Li J. Peters K.L. Smithgall T.E. J. Biol. Chem. 1996; 271: 17519-17525Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar). The C-terminal region of Abl was similarly amplified as a series of four sequences encoding residues Pro480–Gly638 (CT1), Arg639–Leu813 (CT2), Ile801–Ala993 (CT3), and Gly994–Arg1130 (CT4), which were subcloned into the same vector. The resulting pVL-GST constructs were to recombinant baculoviruses for the expression of these Abl regions as GST fusion Sf-9 cells were with each of the baculoviruses a GST baculovirus as a negative and an Hck the cells were in 1.0 ml of Hck lysis and GST fusion proteins were with glutathione-agarose of a The were washed three with 1.0 ml of RIPA and proteins were by in SDS-PAGE sample were on gels and to Hck was by with Hck The of fusion protein in each reaction was determined by with expression of Hck in each culture was by of the clarified cell The of Hck and fusion protein in each was determined by densitometry and the of Hck was to the of fusion protein in each of the Hck wild-type and kinase-inactive into the expression vector A.M. M. D.R. Witte O.N. Cell. Biol. PubMed Scopus Google has been described elsewhere S.D. M. M. Smithgall T.E. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google Scholar). The coding for β-galactosidase was subcloned from the expression vector into constructs the coding sequences for the p210 and forms of Bcr-Abl were from To of cells were with of each and an vector using the described elsewhere S.D. M. M. Smithgall T.E. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google Scholar, J.A. Smithgall T.E. Cell. Biol. 1999; PubMed Scopus Google Scholar, J. Smithgall T.E. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). were and with and at myeloid leukemia cells (14.Goga A. McLaughlin J. Afar D.E.H. Saffran D.C. Witte O.N. Cell. 1995; 82: 981-988Abstract Full Text PDF PubMed Scopus (257) Google were in bovine 50 and were with or Hck and with at of Hck proteins in the cell was by immunoblotting. Hck and control cells were with Bcr-Abl or control as cells were in ml of in the presence of 4 To culture were at for 4 at °C T. J.A. J. 1995; PubMed Scopus Google Scholar). The was with and and the for h. For of cells were washed of cytokine and 4 cells were in of in each well of a To cell cells in each well were with of in and for 4 at The reaction was by of lysis buffer in and pH were at and the of each well was at were in a in the presence of For a well culture and cells as a control for the studies have shown that Bcr-Abl forms a complex with endogenous Hck and Lyn in 32Dcl3 myeloid leukemia cells and that interaction correlates with activation of these Src family kinases (25.Danhauser-Riedl S. Warmuth M. Druker B.J. Emmerich B. Hallek M. Cancer Res. 1996; 56: 3589-3596PubMed Google Scholar). To the for this we expressed a family of GST fusion proteins each of the noncatalytic domains of Hck SH3, and SH2 alone or in in E. coli and on glutathione-agarose beads. of each fusion protein were with lysates from Sf-9 cells expressing the p210 form of a kinase-defective form of p210 or the form of Bcr-Abl. were by and associated Bcr-Abl was by immunoblotting. shown in fusion proteins the Hck SH2 or SH3 domains p210 and Bcr-Abl. In contrast, binding was detected with a GST fusion protein of the region of Hck, GST or the glutathione-agarose To for the of these on Bcr-Abl tyrosine a was with extracts from Sf-9 cells expressing the kinase-defective form of p210 Bcr-Abl. shown in this mutant was to bind to the isolated Hck SH2 domain, strongly suggesting that of Bcr-Abl a specific binding site for the SH2 domain of Hck. In contrast, the kinase-defective mutant to the fusion proteins the SH3 domain to the same as as for an These results that multiple for Src family kinases Bcr-Abl. Recent studies have shown that SH3 and SH2 is sufficient to activate Src kinases in a variety of The interaction of Hck with Bcr-Abl may a for of Hck activation by Bcr-Abl in To the regions of Bcr-Abl that interact with Hck, a series of fusion proteins was with wild-type Hck in Sf-9 cells. The of these fusion proteins are shown in 2 and the the kinase domain, and the C-terminal as a series of four fusion The proteins were from cell lysates with glutathione-agarose and associated Hck was by immunoblotting. shown in regions of Abl to Hck, including the the kinase domain, and the distal portion of the C-terminal tail. Hck did not bind to the Abl C-terminal fusion proteins sequences in SH3 binding to the Crk-L adaptor protein C. Kolibaba K. Bhat A. Oda T. Ohno S. Fanning S. Druker B.J. Blood. 1997; 89: 297-306Crossref PubMed Google Scholar). These results that Hck interacts with the Abl portion of Bcr-Abl through multiple that may a interaction with the C-terminal domain interacts with multiple regions of fusion proteins shown in 2 GST alone as negative were with Hck in Sf-9 insect cells. The fusion proteins were from clarified cell lysates with glutathione-agarose washed with RIPA and associated Hck was by of each GST fusion protein was determined by an of the with The the of the fusion To expression of Hck in each an of the was also with The of Hck and fusion proteins were determined by and the of Hck to are at the This was three with studies have demonstrated a direct interaction of Bcr-Abl with Hck and Lyn in myeloid leukemia cells, suggesting that activation of Src kinases may contribute to Bcr-Abl signaling (25.Danhauser-Riedl S. Warmuth M. Druker B.J. Emmerich B. Hallek M. Cancer Res. 1996; 56: 3589-3596PubMed Google Scholar). To interaction with endogenous Src kinases is required for Bcr-Abl signal we the effect of kinase-inactive Hck on Bcr-Abl-induced transformation of the myeloid leukemia cell DAGM. of Bcr-Abl into these cells with a recombinant has been shown to result in cytokine-independent proliferation (14.Goga A. McLaughlin J. Afar D.E.H. Saffran D.C. Witte O.N. Cell. 1995; 82: 981-988Abstract Full Text PDF PubMed Scopus (257) Google Scholar). cells were with recombinant the kinase-defective form of Hck or β-galactosidase as a negative were in the presence of and and expression of was by not The cell stably expressing or were with p210 or the proliferation was using an and the results are in and p210 Bcr-Abl induced outgrowth in the control cell with the presence of kinase-defective Hck dramatically suppressed cell outgrowth by forms of Bcr-Abl to the control cells. outgrowth was observed with of the cell with the control that transformation to cytokine is dependent upon Bcr-Abl. These data the evidence that Src kinases an essential in transformation signaling downstream of To expression of kinase-defective Hck a of proliferative the of cells expressing as well as the control cells were with and outgrowth was using the shown in of the cells in the presence of suggesting that the of are specific for Bcr-Abl and are not the result of a effect on cell proliferation or In a control we of wild-type Hck p210 Bcr-Abl-induced of cells to cytokine were which stably expressed wild-type Hck, or kinase-defective Hck as described in the These cell were with p210 Bcr-Abl or the and cytokine-independent proliferation was using the shown in wild-type Hck suppressed Bcr-Abl-induced of cells to cytokine to the In contrast, kinase-defective Hck a in with the data shown in All three of these cell proliferative in the presence of not The of wild-type Hck suggests that activation of multiple Src family members may contribute to survival and proliferative signaling by Bcr-Abl in this the of Src family kinases with Bcr-Abl and show for the that these may required for Bcr-Abl transformation signaling. Regarding the mechanism of binding that the SH2 and SH3 domains of Hck are sufficient to bind Bcr-Abl in binding through a as a kinase-defective mutant of Bcr-Abl was to bind to the Hck SH2 These data a mechanism to that interaction with Bcr-Abl Hck and Lyn (25.Danhauser-Riedl S. Warmuth M. Druker B.J. Emmerich B. Hallek M. Cancer Res. 1996; 56: 3589-3596PubMed Google Scholar). Binding of Src family kinases to other proteins through SH2 SH3 domains is sufficient for For example, the interaction of Hck with the protein of to Hck activation and transformation of S.D. M. M. Smithgall T.E. J. Biol. Chem. 1997; 272: Full Text Full Text PDF PubMed Scopus Google Scholar, S.D. Smithgall T.E. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). This effect is to the of to the SH3 domain of Hck from an interaction with the the SH2 and kinase domains M. M. J. Nature. 1997; PubMed Scopus Google Scholar). with binding of the tyrosine-phosphorylated region to the SH2 domain, interaction is a of negative of Src family kinases J. Curr. Opin. Biol. 1997; PubMed Scopus Google Scholar). Binding of Hck or other Src kinases to Bcr-Abl through SH3 and SH2 domains may result in kinase activation a mechanism involving of regions the Abl portion of Bcr-Abl demonstrated strong with Hck, including the the kinase domain, and the distal portion of the C-terminal tail. Binding of the Abl region to Hck may through of Hck tyrosine the the SH2 and kinase of the Abl SH3 domain with the Hck contribute to Hck activation by as described the region of Bcr-Abl has been shown to a in the activation of direct interaction of Bcr-Abl with not to a M. Wasik M.A. Slupianek A. Salomoni P. Kitamura T. Calabretta B. Skorski T. J. Exp. Med. 1999; 189: 1229-1242Crossref PubMed Scopus (245) Google Scholar). that the region of Bcr-Abl is in the recruitment of Hck suggests that Src kinases may as Bcr-Abl to activation and downstream survival signaling. involving the Abl C-terminal region also Fusion proteins the C-terminal regions of Abl with for other proteins as Crk-L did not interact strongly with Hck 2 the other the fusion protein the C-terminal of Abl associated strongly with Hck, the of tyrosine or an This region of Abl the binding domain and is required for Bcr-Abl transforming activity J.R. Cell. Biol. 1993; 13: PubMed Scopus Google Scholar, J.R. EMBO J. 1993; PubMed Scopus Google Scholar, J.R. Cell. Biol. PubMed Google Scholar). or not this region also to with kinases in require In addition to the mechanism of Bcr-Abl interaction with Src kinases, we also evidence that activation of Hck or other Src family members may required for transformation signaling by Bcr-Abl in myeloid cells. of Bcr-Abl with a kinase-defective mutant of Hck strongly suppressed and p210 Bcr-Abl signals for cytokine-independent outgrowth of the myeloid leukemia cell line This result is with the binding data shown in as forms of Bcr-Abl demonstrated binding to the SH2 and SH3 domains of Hck. In contrast, kinase-defective Hck effect on cell a effect of Hck on proliferation These results that the kinase-defective mutant of Hck interacts directly with Bcr-Abl and for with endogenous Src family kinases, resulting in the observed of cell The effect of wild-type Hck in this suggests that activation of Src kinase family member may contribute to survival and proliferative signaling. of wild-type Hck may for activation of other Src family members required for a while the signal from Hck. with this is the that Lyn and associate with the same regions of Bcr-Abl as Hck in not studies have shown that kinase-defective and other Src can with growth factor and cytokine signal transduction and growth factor induced into the cell in (reviewed in C.L. Exp. Res. 2000; PubMed Scopus Google Scholar). or not Src kinases are required to couple Bcr-Abl to proliferative and survival signaling pathways the development of require We for the Bcr-Abl and the cell
Lionberger et al. (Thu,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: