Insulin-like Growth Factor-I Receptor Mediates the Prosurvival Effect of Fibronectin (2007)

We recently showed that extracellular matrix (ECM) proteins, which are abundant in desmoplastic pancreatic tumor, are as potent as growth factors in inhibiting apoptosis in pancreatic cancer (PaCa) cells. Here we show that fibronectin, a major ECM component, engages insulin-like growth factor-I receptor (IGF-IR) to inhibit PaCa cell death. We found that fibronectin-induced protection from apoptosis is fully mediated by IGF-IR and is independent of IGF-I. Pharmacologic and molecular inhibitions of IGF-IR stimulated apoptosis and prevented the prosurvival effect of fibronectin in PaCa cells. Our data indicate that fibronectin protects from apoptosis through trans-activation of IGF-IR. We showed that fibronectin stimulated complex formation between its receptor β3 integrin and protein-tyrosine phosphatase SHP-2. This process of complex formation, in turn, prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation of IGF-IR and leading to the downstream activation of Akt kinase, up-regulation of antiapoptotic BclxL, and inhibition of apoptosis. Among ECM proteins tested only fibronectin and laminin but not vitronectin and collagen I stimulated trans-activation of IGF-IR. Interaction of fibronectin with β3 but not β1 integrin receptors mediates the survival pathway. In contrast, fibronectin-induced adhesion is mediated through β1 integrin receptor and is IGF-IR-independent. Thus, our results indicate that the prosurvival effect of fibronectin in PaCa cells is mediated by trans-activation of IGF-IR induced by the β3 integrin receptor. The data suggest IGF-IR as a key target for prevention of the prosurvival effects of ECM proteins and growth factors in pancreatic cancer. We recently showed that extracellular matrix (ECM) proteins, which are abundant in desmoplastic pancreatic tumor, are as potent as growth factors in inhibiting apoptosis in pancreatic cancer (PaCa) cells. Here we show that fibronectin, a major ECM component, engages insulin-like growth factor-I receptor (IGF-IR) to inhibit PaCa cell death. We found that fibronectin-induced protection from apoptosis is fully mediated by IGF-IR and is independent of IGF-I. Pharmacologic and molecular inhibitions of IGF-IR stimulated apoptosis and prevented the prosurvival effect of fibronectin in PaCa cells. Our data indicate that fibronectin protects from apoptosis through trans-activation of IGF-IR. We showed that fibronectin stimulated complex formation between its receptor β3 integrin and protein-tyrosine phosphatase SHP-2. This process of complex formation, in turn, prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation of IGF-IR and leading to the downstream activation of Akt kinase, up-regulation of antiapoptotic BclxL, and inhibition of apoptosis. Among ECM proteins tested only fibronectin and laminin but not vitronectin and collagen I stimulated trans-activation of IGF-IR. Interaction of fibronectin with β3 but not β1 integrin receptors mediates the survival pathway. In contrast, fibronectin-induced adhesion is mediated through β1 integrin receptor and is IGF-IR-independent. Thus, our results indicate that the prosurvival effect of fibronectin in PaCa cells is mediated by trans-activation of IGF-IR induced by the β3 integrin receptor. The data suggest IGF-IR as a key target for prevention of the prosurvival effects of ECM proteins and growth factors in pancreatic cancer. Pancreatic cancer is the fourth most common cause of death in western countries with almost the same rate of incidence and mortality per year (1Giancotti F.G. Ruoslahti E. Science. 1999; 285: 1028-1032Crossref PubMed Scopus (3829) Google Scholar, 2Parker S.L. Tong T. Bolden S. Wingo P.A. CA Cancer J. Clin. 1997; 47: 5-27Crossref PubMed Scopus (2355) Google Scholar). The disease is very resistant to radio- and/or chemotherapies. One reason for that is the resistance of pancreatic cancer (PaCa) 2The abbreviations used are:PaCapancreatic cancerECMextracellular matrixIGFinsulin-like growth factorIGF-IRinsulin-like growth factor-I receptorAMCaminomethylcoumarinp-phospho-polyHEMApoly(2-hydroxyethyl methacrylate)siRNAsmall interfering RNAAnVAnnexin VPIpropidium iodideCHAPS3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acidELISAenzyme-linked immunosorbent assayANOVAanalysis of variancePI3Kphosphatidylinositide 3-kinase cells to apoptosis (3Westphal S. Kalthoff H. Mol. Cancer. 2003; 2: 6Crossref PubMed Scopus (136) Google Scholar). pancreatic cancer extracellular matrix insulin-like growth factor insulin-like growth factor-I receptor aminomethylcoumarin phospho- poly(2-hydroxyethyl methacrylate) small interfering RNA Annexin V propidium iodide 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid enzyme-linked immunosorbent assay analysis of variance phosphatidylinositide 3-kinase Pancreatic adenocarcinoma is a fibrotic tumor, which is characterized by a high level of extracellular matrix (ECM) proteins. ECM mediates adhesion and invasiveness of cancer cells. Cell survival also depends on adequate connections with ECM proteins through specific integrin receptors. We recently showed that ECM proteins are key mediators of PaCa cell survival (4Sekharam M. Zhao H. Sun M. Fang Q. Zhang Q. Yuan Z. Dan H.C. Boulware D. Cheng J.Q. Coppola D. Cancer Res. 2003; 63: 7708-7716PubMed Google Scholar, 5Vaquero E.C. Edderkaoui M. Pandol S.J. Gukovsky I. Gukovskaya A.S. J. Biol. Chem. 2004; 279: 34643-34654Abstract Full Text Full Text PDF PubMed Scopus (312) Google Scholar) and that detachment from ECM stimulates PaCa cell death. The mechanisms through which ECM proteins protect PaCa cells from death are not fully understood. Fibronectin is a major ECM protein of pancreatic adenocarcinoma; its receptors, β3 and β1 integrins, are up-regulated in pancreatic cancer cells (6Linder S. Castanos-Velez E. von Rosen A. Biberfeld P. Hepatogastroenterology. 2001; 48: 1321-1327PubMed Google Scholar). Fibronectin stimulates invasion and adhesion and markedly increases survival of pancreatic cancer cells (7Edderkaoui M. Hong P. Vaquero E.C. Lee J.K. Fischer L. Friess H. Buchler M.W. Lerch M.M. Pandol S.J. Gukovskaya A.S. Am. J. Physiol. 2005; 289: G1137-G1147Crossref PubMed Scopus (116) Google Scholar, 8Vaquero E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). The importance of fibronectin and other extracellular matrix proteins in pancreatic cancer is underscored by several findings. Pancreatic adenocarcinoma is one of the most lethal of human cancers with a 5-year survival rate of less than 5% (9Jemal A. Siegel R. Ward E. Murray T. Xu J. Smigal C. Thun M.J. CA Cancer J. Clin. 2006; 56: 106-130Crossref PubMed Scopus (5532) Google Scholar). This cancer has a characteristic of marked desmoplasia, which is a remarkable increase in extracellular matrix that infiltrates and envelopes the cancer (10Mollenhauer J. Roether I. Kern H.F. Pancreas. 1987; 2: 14-24Crossref PubMed Scopus (120) Google Scholar). Importantly there is at least one report that demonstrates that greater amounts of intratumor extracellular matrix in pancreatic cancer patients are correlated with more aggressive disease and more rapid death (11Watanabe I. Hasebe T. Sasaki S. Konishi M. Inoue K. Nakagohri T. Oda T. Mukai K. Kinoshita T. Pancreas. 2003; 26: 326-333Crossref PubMed Scopus (61) Google Scholar). Finally recent studies in animal models of pancreatic cancer show that tumors grow more rapidly when the fibroblastic cells of the cancer called stellate cells are included in inocula with cancer cells (12Bachem M.G. Schunemann M. Ramadani M. Siech M. Beger H. Buck A. Zhou S. Schmid-Kotsas A. Adler G. Gastroenterology. 2005; 128: 907-921Abstract Full Text Full Text PDF PubMed Scopus (511) Google Scholar). The addition of the stellate cells results in the experimental tumors taking on the characteristics of the human cancer with the extracellular matrix infiltrating and enveloping the cancer cells. In addition, another powerful mediator of PaCa cell survival is insulin-like growth factor-I (IGF-I). Both IGF-I and IGF-I receptor (IGF-IR) are overexpressed in human pancreatic tumors as well as in pancreatic cancer cell lines (13Bergmann U. Funatomi H. Yokoyama M. Beger H.G. Korc M. Cancer Res. 1995; 55: 2007-2011PubMed Google Scholar, 14Karna E. Surazynski A. Orlowski K. Laszkiewicz J. Puchalski Z. Nawrat P. Palka J. Int. J. Exp. Pathol. 2002; 83: 239-245Crossref PubMed Scopus (65) Google Scholar). Blockade of the IGF-IR by a dominant negative inhibitor suppresses tumorigenicity both in vitro and in vivo and increases sensitivity of pancreatic tumors to radiation and chemotherapy-induced apoptosis. The key event in IGF-I-induced signaling is phosphorylation of IGF-I receptor kinase followed by the activation of the phosphatidylinositide 3-kinase (PI3K)/Akt pathway, which mediates the antiapoptotic effect of IGF-I (4Sekharam M. Zhao H. Sun M. Fang Q. Zhang Q. Yuan Z. Dan H.C. Boulware D. Cheng J.Q. Coppola D. Cancer Res. 2003; 63: 7708-7716PubMed Google Scholar). Another important step in IGF-I-induced signaling is phosphorylation of adapter protein SHPS-1 leading to the recruitment of Src homology 2-containing phosphotyrosine phosphatase SHP-2. SHP-2 is a negative regulator of IGF-IR signaling. It dephosphorylates IGF-IR resulting in the inhibition of its signaling (15El Annabi S. Gautier N. Baron V. FEBS Lett. 2001; 507: 247-252Crossref PubMed Scopus (21) Google Scholar). Very little is known on the role of IGF-IR in the effects of ECM proteins. In contrast the contribution of integrins in the signaling induced by exogenous IGF-I cells was established in several publications mostly in smooth muscle cells (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar, 17Ling Y. Maile L.A. Badley-Clarke J. Clemmons D.R. J. Biol. Chem. 2005; 280: 3151-3158Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar). In these cells IGF-I-induced phosphorylation of β3 integrins results in recruitment of phosphatase SHP-2, which is required for proper IGF-IR phosphorylation. Both β3 and SHP-2 knock-downs result in the inhibition of functional IGF-I responses, and (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar). Here we show that prosurvival effects of fibronectin are mediated by IGF-IR and which effect on cell not IGF-IR. is not required for fibronectin-induced IGF-IR IGF-IR is not in fibronectin-induced adhesion of PaCa cells. Fibronectin IGF-IR by receptor Fibronectin stimulates complex formation between its receptor β3 integrin and protein-tyrosine phosphatase SHP-2. This in prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation of IGF-IR and leading to the downstream activation of Akt kinase, up-regulation of BclxL, and inhibition of apoptosis. Our results indicate that between IGF-IR and β3 integrin a role in the effects of fibronectin and IGF-I. of apoptosis by fibronectin is mediated by SHP-2 from IGF-IR and is by SHP-2 In contrast IGF-I signaling as well as downstream and are by SHP-2 (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar). was from SHP-2, BclxL, and from and β3 integrins and the β1 and β3 integrins from and IGF-I from was from Cell was from and growth factor was from other from Cell pancreatic adenocarcinoma cell the and the from the and cells in with and at in a 5% and used between and and cells at a of on with poly(2-hydroxyethyl methacrylate) fibronectin, collagen fibronectin for to in and for the prevents both cell on and cell matrix J. A. PubMed Scopus Google Scholar). with of in to and with with we but less in cells on on with J. 2006; PubMed Scopus Google Scholar). with human fibronectin, collagen fibronectin by at the protein for at for the in the of the same of was to the the cells. In the of cells and was and of and cells with was to the IGF-IR was for a The IGF-IR used as a with SHP-2 was the same with SHP-2 and SHP-2 as a IGF-IR IGF-I was The of by of the was in both and cell The of IGF-IR and SHP-2 and IGF-IR and IGF-I was by to the human in a for at The was with and and at Cell for at and proteins by and to was with 5% in in and for with the and for with with the was to the and Cell as in the for at and protein was The was to the and the specific and in a and at for The was with the The was with and by as of was by the Cell to the was with the from as we E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). and at a of cells in of of Annexin V and propidium iodide in the for at and by was by a assay in cell as a as we E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). The was with in a at which with and was a for with The adhesion assay was as M. Cancer Res. Google Scholar) with the cells with and the was at IGF-I level was the to the are as from at least independent analysis was to between analysis of variance and the used to between several and of IGF-IR the of Fibronectin in Pancreatic Cancer with our publications (7Edderkaoui M. Hong P. Vaquero E.C. Lee J.K. Fischer L. Friess H. Buchler M.W. Lerch M.M. Pandol S.J. Gukovskaya A.S. Am. J. Physiol. 2005; 289: G1137-G1147Crossref PubMed Scopus (116) Google Scholar, 8Vaquero E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google fibronectin and IGF-I apoptosis in pancreatic cancer cells Importantly of fibronectin and IGF-I not apoptosis in with fibronectin IGF-I that the prosurvival of IGF-I and fibronectin through the same prosurvival target as IGF-IR. the role of IGF-IR activation in the prosurvival effect of fibronectin, we showed that the effects of fibronectin on of apoptosis prevented by the inhibitor to the the IGF-IR M. A. A. E. D. 1997; PubMed Scopus Google Scholar). In in the of fibronectin not and and not the survival rate in PaCa cells of and cells with IGF-IR in cells on fibronectin the prosurvival effect of fibronectin was in cells with IGF-IR Thus, the results of and indicate that IGF-IR mediates the effect of fibronectin in pancreatic cancer of IGF-IR the prosurvival effect of and cells on fibronectin for and cells with IGF-IR and for on cells with IGF-IR and for on was the Cell are to for cells with and and on and on fibronectin are on on fibronectin was by and for to Fibronectin IGF-IR the of Fibronectin on IGF-IR with on the effect of fibronectin on the phosphorylation level of IGF-IR we and cells for the on fibronectin prevents cells from and also prevents extracellular matrix J. A. PubMed Scopus Google Scholar). that fibronectin the level of IGF-IR phosphorylation in and and and cells that IGF-IR is by The increase in IGF-IR phosphorylation was at and was at It in and in cells and was sustained for to and in IGF-IR phosphorylation in cells on in the same the effect of other on IGF-IR we cells on collagen and fibronectin and on in the of fibronectin for and the phosphorylation level of IGF-IR. that on collagen and vitronectin not increase phosphorylation of IGF-IR as with that on vitronectin collagen I PaCa cell survival of IGF-IR was only in cells on fibronectin and to a on laminin and fibronectin to PaCa cell survival Thus, the of ECM proteins to inhibit apoptosis with to increase the level of IGF-IR phosphorylation and integrin receptors for vitronectin and collagen I are in cells with fibronectin indicate that fibronectin stimulates IGF-IR phosphorylation in cells. The of IGF-IR and from of effects of fibronectin on IGF-IR phosphorylation to the level of IGF-I in extracellular and its with IGF-IR. the role of IGF-I in the effects of fibronectin we used several we the effect of fibronectin on the extracellular level of IGF-I in and cells. that in cells on fibronectin the extracellular level of IGF-I was by than of Fibronectin not increase the level of extracellular IGF-I. the of IGF-I in cell the same as the in cells on and Finally we showed that the of IGF-I with IGF-I not the level of IGF-IR in cells on fibronectin Blockade of IGF-I also not inhibition of apoptosis by fibronectin that the prosurvival effect of fibronectin is not mediated through exogenous IGF-I. contrast, IGF-I the phosphorylation of IGF-IR and inhibition of apoptosis induced by the growth factor IGF-I and the of IGF-I in the prosurvival effect of fibronectin we cells with IGF-I that fibronectin apoptosis in and with IGF-I data indicate that the effects of fibronectin on IGF-IR phosphorylation and apoptosis are not to increase in exogenous IGF-I. which and growth factor T. R. J. Clin. PubMed Scopus Google Scholar, R. J. R. G. 2006; PubMed Scopus Google Scholar). of and growth factor not the fibronectin-induced increase in IGF-IR Src kinase inhibitor Src kinase the fibronectin-induced IGF-IR of Src kinase Thus, our data suggest that IGF-I is not a mediator of the effects of fibronectin on IGF-IR phosphorylation. We that IGF-I at very in extracellular and to the IGF-IR phosphorylation. Our data also not of proteins in the effects of fibronectin on IGF-I. β3 the of β1 in Cell the of β3 and β1 integrins in the IGF-IR we and that to of fibronectin with the integrins Lee S.J. Lee J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar, K. L. M. R. R. T. D. N. P. C. Cancer Res. 2003; 63: Google Scholar). The fibronectin-induced increase in phosphorylation of IGF-IR was in cells on fibronectin in the of the β3 In contrast, of β1 integrin IGF-IR phosphorylation data indicate that IGF-IR trans-activation is mediated by β3 but not β1 suggest that β1 inhibition of fibronectin with β3 The increase in IGF-IR phosphorylation induced by β1 to less between β1 and β3 integrins to with we the role of adhesion in the effects of fibronectin on IGF-IR phosphorylation. that fibronectin increases adhesion of and cells. The effect of fibronectin on adhesion was also β3 integrin effect on adhesion of cells and only adhesion of cells at contrast, β1 integrin adhesion in both and cells at tested data indicate that β1 than β3 integrin mediates PaCa cell the effects of and on the adhesion and on IGF-IR phosphorylation in cells for on of β3 integrin adhesion but markedly prevented IGF-IR inhibition of β1 integrin adhesion but in IGF-IR phosphorylation data suggest that the fibronectin-induced activation of IGF-IR is not with cell SHP-2 the of IGF-IR by fibronectin-induced increase in phosphorylation level of IGF-IR mediated by several up-regulation of the IGF-IR protein of IGF-IR kinase inhibition of the IGF-IR the inhibitor of protein prevented the phosphorylation of IGF-IR by fibronectin that the increase in phosphorylation was not to the protein level of IGF-IR. The protein phosphatase inhibitor stimulated IGF-IR phosphorylation in cells on of Importantly in the of fibronectin not phosphorylation that the fibronectin effect is mediated by phosphatase inhibition SHP-2 IGF-IR signaling in other cells Y. Maile L.A. Badley-Clarke J. Clemmons D.R. J. Biol. Chem. 2005; 280: 3151-3158Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar). we tested phosphatase SHP-2 IGF-IR phosphorylation in PaCa cells. with SHP-2 the phosphorylation level of IGF-IR in cells on that SHP-2 phosphorylation of IGF-IR. Importantly in cells with SHP-2 fibronectin not IGF-IR phosphorylation that the fibronectin-induced phosphorylation of IGF-IR is mediated by SHP-2 We showed that β3 integrin and SHP-2 are in pancreatic cancer cells. analysis SHP-2 in β3 integrin and β3 integrin in SHP-2 of β3 integrin with SHP-2 was greater in pancreatic cancer cells on fibronectin than in on and of the same not β3 integrin SHP-2, of the The results of suggest SHP-2 as a mediator of the fibronectin-induced up-regulation of IGF-IR phosphorylation. to fibronectin, β3 integrins and SHP-2 from dephosphorylating IGF-IR. β3 and SHP-2 the of that the antiapoptotic effect of fibronectin is mediated through β3 integrin we cells on fibronectin in the of β3 integrin demonstrates that β3 integrin prevents the fibronectin-induced inhibition of data are in with the results in that of β3 integrin prevented the fibronectin-induced IGF-IR phosphorylation. In we showed that fibronectin stimulates of protein-tyrosine phosphatase SHP-2 with β3 and that SHP-2 with in cells on results in phosphorylation of IGF-IR to that induced by that SHP-2 in cells on to the same as In cells with SHP-2 and on fibronectin there was in apoptosis The results of and and that the antiapoptotic effect of fibronectin is mediated through β3 integrin leading to complex formation between β3 and SHP-2 that results in IGF-IR phosphorylation. IGF-I was to β3 integrin recruitment in smooth muscle cells through β3 phosphorylation by Src In contrast, in the pancreatic cancer cells fibronectin stimulates β3 complex formation in the of β3 integrin phosphorylation Src kinase inhibitor not the fibronectin-induced IGF-IR phosphorylation IGF-IR the of the fibronectin-induced protection from apoptosis in pancreatic cancer cells is mediated by the J. 2006; PubMed Scopus Google Scholar). inhibition of by its inhibitor in cells on fibronectin The fibronectin-induced Akt phosphorylation was in the of the inhibitor of of IGF-IR in Akt phosphorylation inhibition of Akt phosphorylation is another downstream in the prosurvival of Our data indicate that inhibition of IGF-IR by the protein level of in cells on fibronectin Importantly SHP-2 Akt phosphorylation in cells on to fibronectin these results indicate that SHP-2 recruitment by fibronectin results in sustained IGF-IR phosphorylation followed by activation of antiapoptotic signaling in activation of Akt and up-regulation of ECM protein fibronectin and growth factor IGF-I are major factors PaCa cells from death E.C. Edderkaoui M. Pandol S.J. Gukovsky I. Gukovskaya A.S. J. Biol. Chem. 2004; 279: 34643-34654Abstract Full Text Full Text PDF PubMed Scopus (312) Google Scholar, M. Hong P. Vaquero E.C. Lee J.K. Fischer L. Friess H. Buchler M.W. Lerch M.M. Pandol S.J. Gukovskaya A.S. Am. J. Physiol. 2005; 289: G1137-G1147Crossref PubMed Scopus (116) Google Scholar). Our was to the role of IGF-IR in the antiapoptotic effect of We used and human pancreatic cell which both and characteristic for pancreatic cancer PubMed Scopus Google Scholar). The is on our on the effects of extracellular matrix proteins on cancer cell survival E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). Our key is that the prosurvival effect of fibronectin is mediated through activation of IGF-IR We used several lines of to the of IGF-IR and its phosphorylation in the antiapoptotic effect of We showed that fibronectin-induced recruitment and inhibition of the phosphatase SHP-2 mediates the of IGF-IR phosphorylation and the downstream antiapoptotic pathway. In we showed that inhibition as well as molecular of IGF-IR apoptosis in PaCa cells on IGF-IR phosphorylation in cells on by SHP-2 the prosurvival effect of results show that fibronectin apoptosis through the and antiapoptotic protein M. J. S. G. M. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus (136) Google Scholar). We found that of IGF-IR in cells on fibronectin prevented both Akt phosphorylation and data indicate that trans-activation of IGF-IR is a key the prosurvival effect of fibronectin in PaCa cells. In contrast to fibronectin, cancer cells on vitronectin collagen I was effect on apoptosis rate IGF-IR phosphorylation. the other ECM proteins that a prosurvival fibronectin, and fibronectin, IGF-IR phosphorylation that the prosurvival effect of ECM proteins in PaCa cells IGF-IR. We found that the β3 integrin receptor but not major fibronectin receptor β1 mediates trans-activation of IGF-IR by which β3 not that β3 is but not for IGF-IR phosphorylation. Cell adhesion and cell survival are major of Our data show that fibronectin-induced survival and adhesion are mediated through is mediated through IGF-IR adhesion β1 and is independent of IGF-IR. fibronectin also IGF-IR and that adhesion is not required for the prosurvival effect of The inhibition of apoptosis by fibronectin in survival of cancer cells that are from the but fibronectin on and cells apoptosis when from This cells from the Cell Biol. 2001; PubMed Scopus Google Scholar). In contrast, cells detachment from the ECM are of and to The mechanisms are not fully adhesion is a to survival by kinase, which is in to adhesion J. Exp. 1995; PubMed Scopus Google and kinase, which is to adhesion both in survival signaling induced by We showed that not in PaCa cells E.C. Edderkaoui M. Nam K.J. Gukovsky I. Pandol S.J. Gukovskaya A.S. Gastroenterology. 2003; 125: 1188-1202Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar). The results of show that fibronectin apoptosis in PaCa cells through activation of IGF-IR and that is growth factors and IGF-I in are major prosurvival factors in PaCa cells E.C. Edderkaoui M. Pandol S.J. Gukovsky I. Gukovskaya A.S. J. Biol. Chem. 2004; 279: 34643-34654Abstract Full Text Full Text PDF PubMed Scopus (312) Google Scholar). Thus, to inhibit apoptosis fibronectin a major antiapoptotic signaling in PaCa cells. Our results indicate that fibronectin stimulated complex formation between β3 integrin and protein-tyrosine phosphatase SHP-2. This complex prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation and activation of IGF-IR. little is known on the role of growth factor receptors in the signaling by ECM proteins, the role of integrins in the effects of growth factors has in in smooth muscle cells (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar, 17Ling Y. Maile L.A. Badley-Clarke J. Clemmons D.R. J. Biol. Chem. 2005; 280: 3151-3158Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar). The data from our are from in the publications on the smooth muscle cells (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar, 17Ling Y. Maile L.A. Badley-Clarke J. Clemmons D.R. J. Biol. Chem. 2005; 280: 3151-3158Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar, L.A. Clemmons D.R. 2002; PubMed Scopus Google Scholar). Our that fibronectin-induced activation of IGF-IR is independent of IGF-I in PaCa cells. In contrast, in the smooth muscle cells IGF-I is required and in with to IGF-IR phosphorylation. our data indicate that fibronectin recruitment and of SHP-2 from dephosphorylating and SHP-2 the effect of fibronectin on apoptosis. In contrast, in the smooth muscle cells SHP-2 is by β3 integrin to IGF-IR and SHP-2 the IGF-I-induced and in these cells (16Maile L.A. Badley-Clarke J. Clemmons D.R. Mol. Biol. Cell. 2003; 14: 3519-3528Crossref PubMed Google Scholar). In we show that the prosurvival effect of fibronectin is mediated through trans-activation of IGF-IR leading to the downstream activation of Akt kinase, up-regulation of BclxL, and inhibition of apoptosis survival and adhesion are mediated through is mediated through the β3 integrin receptor and IGF-IR activation and not adhesion the β1 integrin receptor and is independent of IGF-IR. We showed that fibronectin stimulated complex formation between its integrin and protein-tyrosine phosphatase SHP-2. This complex prevents SHP-2 from dephosphorylating IGF-IR resulting in sustained phosphorylation and activation of IGF-IR. Our data suggest the inhibition of the IGF-IR as a to inhibit prosurvival mechanisms induced in PaCa cells by both growth factors and ECM proteins and to pancreatic cancer resistance to and radiation In the importance of the extracellular matrix in the of pancreatic cancer as in the our results key that used to at mechanisms the of the