Expression of a truncated EGF receptor is associated with inhibition of pancreatic cancer cell growth and enhanced sensitivity to cisplatinum.

Human pancreatic cancers over-express the epidermal growth factor receptor (EGF-R) and all 5 known ligands of the EGF family, including EGF, transforming growth factor-alpha (TGF-alpha), amphiregulin, betacellulin and heparin-binding EGF-like growth factor (HB-EGF). The aim of the present study was to confirm the presence of EGF-R-dependent autocrine loops in a human pancreatic cancer cell line and to explore the possibility that interrupting EGF-R activation by introducing a truncated receptor abrogates pancreatic cancer cell growth. The anchorage-independent growth of PANC-1 human pancreatic cancer cells, previously shown to express TGF-alpha, was inhibited by specific anti TGF-alpha antibodies. PANC-1 cells were then either transfected with an expression plasmid encoding a kinase-deficient EGF-R cDNA (HER653) or infected with the same EGF-R cDNA using a retroviral vector. Multiple transfected and infected clones co-expressed the truncated EGF-R and endogenous EGF-R as revealed by Northern blot analysis and immunoblots. In these clones, there was a marked attenuation in EGF- and TGF-alpha-mediated EGF-R tyrosine phosphorylation and c-fos induction. There was also a significant decrease in colony formation in soft agar by comparison with control cells and a significant increase in the effect of the growth-inhibitory effect of the alkylating agent cisplatinum in these clones. Our observations indicate that dominant negative inhibition of EGF-R may have therapeutic potential in pancreatic cancer.

Epidermal growth factor receptor expression in pancreatic lesions induced in the rat by azaserine.

In the present study, the expression of the epidermal growth factor receptor (EGFR) was investigated in putative preneoplastic and neoplastic acinar cell lesions induced in the rat pancreas by azaserine, using Northern blotting, in situ hybridisation (ISH) and immunohistochemistry. EGFR protein levels were decreased in putative preneoplastic eosinophilic acinar cell lesions (atypical acinar cell nodules, AACN) in comparison with normal acinar cells of the pancreas. However, EGFR mRNA expression correlated positively with the volume of AACN in pancreatic homogenates and ISH showed equal or stronger EGFR mRNA expression in AACN than in the surrounding normal acinar cells. Neither EGFR protein nor EGFR mRNA was detected in more advanced lesions such as acinar adenocarcinomas (in situ). Moreover, EGFR protein expression showed an inverse relationship with the mitotic rate of the acinar cells. These findings suggest that down-regulation of EGFR at the protein level may abrogate negative constraints on cell growth, which may stimulate the development of putative preneoplastic AACN to more advanced lesions and, ultimately, acinar adenocarcinomas.

Cytotoxic effects of TGF-alpha-Pseudomonas exotoxin A fusion protein in human pancreatic carcinoma cells.

The epidermal growth factor (EGF) receptor is overexpressed in human pancreatic cancers and cultured cell lines. TP40 is a chimeric protein composed of transforming growth factor-alpha (TGF-alpha) linked to a modified Pseudomonas exotoxin A (PE40) that exerts growth inhibitory effects on cells bearing a high number of EGF receptors. Therefore, we compared the effect of TP40 on the growth of Chinese hamster ovary (CHO), cells expressing varying levels of the EGF receptor and on the growth of two human pancreatic cancer cell lines. The growth of CHO cells devoid of endogenous EGF receptors was minimally altered by high concentrations of TP40, even following a 72-h incubation period. In contrast, in CHO cells expressing approximately 95,000 and 438,000 EGF receptors per cell, one-half maximal growth inhibition occurred at 5 and 3 ng/ml TP40, respectively. Following a 72-h incubation in T3M4 and COLO 357 human pancreatic cancer cells, one-half maximal growth inhibition occurred at 0.2 and 0.4 ng/ml TP40, respectively. This effect was significantly greater than that of native Pseudomonas exotoxin A. These findings indicate that human pancreatic cancer cells are markedly sensitive to the growth inhibitory effects of TP40 and raise the possibility that TP40 may have a therapeutic role in this disorder.

Attenuated ALK5 receptor expression in human pancreatic cancer: correlation with resistance to growth inhibition.

Transforming growth factor-beta (TGF-beta) receptors constitute a family of transmembrane proteins that bind TGF-beta ligands. In this study we assessed the growth responsiveness to TGF-beta 1 in pancreatic cancer cell lines and characterized the levels of expression of TGF-beta receptors in these cell lines and in human pancreatic cancer tissues. COLO 357 cells were most sensitive to the growth inhibitory actions of TGF-beta 1, PANC-1 cells exhibited moderate sensitivity, Hs766T cells exhibited slight sensitivity and MIA PaCa-2 and T3M4 cells were resistant to TGF-beta 1. Only COLO 357 cells expressed high levels of ALK5, the major type I TGF-beta receptor (T beta RI). Hs766T and PANC-1 cells expressed high levels of SKR1, another T beta RI subtype. Only MIA PaCa-2 cells did not exhibit the type II TGF-beta receptor (T beta-RII) transcript, whereas type III TGF-beta receptor (T beta-RIII) mRNA levels were elevated in this cell line and in HS766T cells. All the cell lines expressed TGF-beta 1, but TGF-beta 2 and TGF-beta 3 mRNA levels were variable. ALK5 and SKR1 mRNA levels were 6.8- and 9-fold greater in the pancreatic tumors in comparison with the corresponding levels in the normal pancreas. However, in the cancer cells, ALK5 immunoreactivity was faint, whereas T beta RII immunoreactivity was focal and intense. Conversely, in ductal cells adjacent to cancer cells ALK5 immunoreactivity was strong, whereas T beta RII immunoreactivity was weak. Since ALK5 heterodimerization with T beta RII is crucial for TGF-beta-mediated signaling, our findings suggest that low levels of ALK5 in pancreatic cancer cells within a tumor may protect against growth inhibition.

Single-strand conformation polymorphism analysis of the epidermal growth factor receptor at codon 497.

A variant human epidermal growth factor (EGF) receptor (HER) with a transition (G to A) at codon 497, resulting in a substitution of a lysine for an arginine, was recently demonstrated in several human pancreatic cancer cell lines. In the present study, we compared the frequency of expression of wild-type (HER497R) and variant (HER497K) EGF receptors in normal and malignant pancreatic tissue samples using single-strand conformation polymorphism analysis. Both receptors were expressed in normal (42%) and malignant (46%) tissues. Three samples (two normal and one cancer) expressed only HER497K. The cancer sample that was homozygous for HER497K exhibited strong EGF receptor immunoreactivity. The high frequency of HER497K expression suggests that it is due to a relatively common polymorphism in the HER coding region. Its presence in some of the cancer samples suggests that, like the wild-type receptor, HER497K also has a role in pancreatic cancer.

Overexpression of transforming growth factor-alpha and epidermal growth factor receptor, but not epidermal growth factor, in exocrine pancreatic tumours in hamsters.

Using immunohistochemistry, Northern blotting and a semi-quantitative PCR technique, epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) expression were studied in the pancreas of N-nitrosobis(2-oxopropyl)-amine (BOP)-treated hamsters. After initiation pancreatic carcinogenesis was modulated by a high fat diet or by injections with the cholecystokinin analogue caerulein. Autopsies were performed 6 and 12 months after the last injection with BOP. Immunohistochemistry revealed a weak expression of TGF-alpha in nomal acinar cells and a stronger expression in ductular and centro-acinar cells. Over-expression of TGF-alpha was observed in advanced putative preneoplastic lesions (classified as borderline lesions) and in ductular adenocarcinomas. EGFR immunoreactivity was present only in ductular adenocarcinomas. EGF peptide expression was observed both in acinar and ductular normal and tumorous cells and the level of expression did not change significantly during carcinogenesis. Moreover, the post-initiation treatments did not cause differences in EGF, TGF-alpha or EGFR peptide or mRNA levels, except for a significantly lower expression of TGF-alpha mRNA in hamsters fed a high fat diet when compared with those fed a low fat diet. TGF-alpha mRNA levels increased, whereas EGF mRNA levels decreased significantly in total pancreatic homogenates of BOP-treated hamsters in comparison with untreated controls. Also, in ductular adenocarcinomas TGF-alpha and EGFR (but not EGF) mRNA levels were significantly higher than in normal pancreatic homogenates. In pancreatic homogenates obtained 6 months after the last BOP injection, these differences were less pronounced in comparison with those obtained after 12 months. The present results indicate that TGF-alpha (but not EGF) might act in a paracrine or autocrine manner in pancreatic tumours in BOP-treated hamsters via simultaneously expressed EGFR. However, TGF-alpha, EGF and EGFR do not seem to be involved in the modulating effects of a high fat diet or caerulein treatment on pancreatic carcinogenesis in BOP-treated hamsters.

Enhanced erbB-3 expression in human pancreatic cancer correlates with tumor progression.

The erbB-3 gene encodes a transmembrane protein that is related to the epidermal growth factor (EGF) receptor and erbB-2. We compared erbB-3 expression in the normal human pancreas, human pancreatic carcinomas, and cultured human pancreatic cancer cell lines. Northern blot analysis of total RNA revealed the anticipated 6.2-kb mRNA transcript in all 19 normal pancreatic samples. In 17 of 27 pancreatic cancers, there was a 6.7-fold increase (P < 0.001) in erbB-3 mRNA levels. Southern blot analysis did not reveal erbB-3 gene amplification. Four of six pancreatic cancer cell lines exhibited the 6.2-kb erbB-3 mRNA transcript, and all four cell lines coexpressed the epidermal growth factor receptor and erbB-2. Using a highly specific antibody, we determined that faint to moderate erbB-3 immunoreactivity was present in the ductal cells in the normal pancreas. In 47% (27/58) of the pancreatic cancers, there were many cancer cells with intense erbB-3 immunostaining. The presence of erbB-3 in the cancer cells was associated with advanced tumor stage and shorter survival postoperatively. These data indicate that a significant proportion of human pancreatic cancers overexpress erbB-3, and that erbB-3 may contribute to disease progression in this disorder.

Increased expression of keratinocyte growth factor in human pancreatic cancer.

Keratinocyte growth factor (KGF) is a member of the fibroblast growth factor (FGF) group of heparin-binding polypeptides. In the present study we sought to determine whether KGF is expressed in human pancreatic cancers. Using reverse transcriptase polymerase chain reaction (RT-PCR), a cDNA fragment of KGF was cloned and used to analyze Northern blots of RNA isolated from normal and cancerous human pancreatic tissues. Seven of 16 (44%) pancreatic cancer samples revealed significant overexpression of the 2.4 kilobase KGF mRNA transcript by comparison with the normal pancreas. Northern blot analysis failed to reveal the KGF transcript in several cultured human pancreatic cancer cell lines. However, by PCR analysis, some of the cell lines expressed KGF mRNA. Furthermore, 5 of 7 tested cell lines expressed the KGF receptor, and the growth of one cell line was enhanced by human recombinant KGF. These results suggest that KGF may participate in aberrant paracrine and autocrine pathways in human pancreatic cancer.

Induction of platelet-derived growth factor A and B chains and over-expression of their receptors in human pancreatic cancer.

Expression of platelet-derived growth factor (PDGF) and PDGF receptors was examined in cultured human pancreatic cancer cells, in the normal human pancreas and in pancreatic adenocarcinomas. mRNA transcripts encoding PDGF A and B chains, and PDGF receptor beta (PDGFR beta) were present in PANC-I and HPAF human pancreatic cancer cells. Transforming growth factor beta I (TGF-beta I), but not PDGF-AA or -BB, enhanced PDGF A and B chain mRNA levels in both cell lines. In the normal human pancreas PDGF A chain mRNA levels were relatively abundant, whereas PDGF B chain mRNA levels were not detected and PDGF receptor alpha (PDGFR alpha) and beta mRNA transcripts were present at low levels. PDGF immunoreactivity was present in islet cells, and PDGFR alpha was present in acinar cells, whereas PDGFR beta was present in acinar cells and in the connective tissue. In the pancreatic cancers, PDGF A chain mRNA transcripts were also abundant, and 6 of 13 samples exhibited the PDGF B chain mRNA transcript. In addition, there was a 7-fold increase in the levels of PDGFR alpha and PDGFR beta in the cancer samples by comparison with the normal pancreas. By immunohistochemistry, PDGF and both PDGF receptors were present in the cancer cells, and PDGFR beta was abundant in fibroblasts and endothelial cells within the connective tissue.

A variant epidermal growth factor receptor exhibits altered type alpha transforming growth factor binding and transmembrane signaling.

Epidermal growth factor (EGF) and type alpha transforming growth factor (TGF-alpha) bind to a specific region in subdomain III of the extracellular portion of the EGF receptor (EGFR). Binding leads to receptor dimerization, auto-and transphosphorylation on intracellular tyrosine residues, and activation of signal transduction pathways. We compared the binding and biological actions of EGF and TGF-alpha in Chinese hamster ovary (CHO) cells expressing either wild-type human EGFR (HER497R) or a variant EGFR that has an arginine-to-lysine substitution in the extracellular domain at codon 497 (HER497K) within subdomain IV of EGFR. Both receptors exhibited two orders of binding sites with radioiodinated EGF (125I-EGF). Similar results were obtained with 125I-TGF-alpha in cells expressing HER497R. In contrast, only one order of low-affinity binding sites was seen with 125I-TGF-alpha in the case of HER497K. Although EGF and TGF-alpha enhanced tyrosine phosphorylation of both receptors, CHO cells expressing HER497K exhibited an attenuated growth response to EGF and TGF-alpha and a reduced induction of the protooncogenes FOS, JUN, and MYC. Moreover, high concentrations of TGF-alpha (5 nM) inhibited growth in these cells but not in cells expressing HER497R. These findings indicate that a region in subdomain IV of EGFR regulates signal transduction across the cell membrane and selectively modulates that binding characteristics of TGF-alpha.

Chronic pancreatitis is associated with increased concentrations of epidermal growth factor receptor, transforming growth factor alpha, and phospholipase C gamma.

The epidermal growth factor (EGF) receptor is a transmembrane protein that binds EGF and transforming growth factor alpha (TGF alpha), and that stimulates phospholipase C gamma 1 (PLC gamma 1) activity. In this study the role of the EGF receptor in chronic pancreatitis was studied. By immunohistochemistry, the EGF receptor, TGF alpha, and PLC gamma 1 were found to be expressed at high concentrations in pancreatic ductal and acinar cells from chronic pancreatitis patients. Northern blot analysis showed that, by comparison with normal controls, 19 of 27 chronic pancreatitis tissues exhibited a 5.7-fold increase in EGF receptor mRNA concentrations, and 20 of 27 chronic pancreatitis tissues exhibited a sixfold increase in TGF alpha mRNA concentrations. In situ hybridisation confirmed that overexpression occurred in ductal and acinar cells, and showed that both mRNA moieties colocalised with their respective proteins. These findings suggest that TGF alpha may act through autocrine and paracrine mechanisms to excessively activate the overexpressed EGF receptor in the two major cell types of the exocrine pancreas, thereby contributing to the pathobiology of this disorder.

Recombinant Vgr-1/BMP-6-expressing tumors induce fibrosis and endochondral bone formation in vivo.

Members of the TGF-beta superfamily appear to modulate mesenchymal differentiation, including the processes of cartilage and bone formation. Nothing is yet known about the function of the TGF-beta-related factor vgr-1, also called bone morphogenetic protein-6 (BMP-6), and only limited studies have been conducted on the most closely related factors BMP-5, osteogenic protein-1 (OP-1) or BMP-7, and OP-2. Because vgr-1 mRNA has been localized in hypertrophic cartilage, this factor may play a vital role in endochondral bone formation. We developed antibodies to vgr-1, and documented that vgr-1 protein was expressed in hypertrophic cartilage of mice. To further characterize the role of this protein in bone differentiation, we generated CHO cells that overexpressed recombinant murine vgr-1 protein. Western blot analysis documented that recombinant vgr-1 protein was secreted into the media and was proteolytically processed to yield the mature vgr-1 molecule. To assess the biological activity of recombinant vgr-1 in vivo, we introduced the vgr-1-expressing CHO cells directly into the subcutaneous tissue of athymic nude mice. CHO-vgr-1 cells produced localized tumors, and the continuous secretion of vgr-1 resulted in tumors with a strikingly different gross and histological appearance as compared to the parental CHO cells. The tumors of control CHO cells were hemorrhagic, necrotic, and friable, whereas the CHO-vgr-1 tumors were dense, firm, and fibrotic. In contrast with control CHO tumors, the nests of CHO-vgr-1 tumor cells were surrounded by extensive connective tissue, which contained large regions of cartilage and bone. Further analysis indicated that secretion of vgr-1 from the transfected CHO tumor cells induced the surrounding host mesenchymal cells to develop along the endochondral bone pathway. These findings suggest that endochondral bone formation.

Induction and expression of amphiregulin in human pancreatic cancer.

The epidermal growth factor receptor is activated by a family of polypeptides that includes the growth factor amphiregullin (AR). Using Northern blot analysis and the polymerase chain reaction, we now report that AR mRNA is expressed in human pancreatic cancer cell lines, and that this expression is enhanced in several of these cell lines by tetradecanoyl phorbol acetate and transforming growth factor alpha. AR was also expressed in normal and malignant pancreatic tissues. However, in the normal pancreas, AR immunostaining was most evident in the nuclei of ductal cells. In contrast, in many carcinomas, AR was also present in the cytoplasm of the ductal-like cancer cells. Cytoplasmic localization of AR was associated with a more advanced clinical stage. These findings suggest that AR may contribute to aberrant activation of the epidermal growth factor receptor in human pancreatic cancer, and may enhance disease progression.

Induction and expression of heparin-binding EGF-like growth factor in human pancreatic cancer.

Heparin-binding EGF-like growth factor (HB-EGF) is a polypeptide with an apparent molecular weight of 22 kilodalton that is related to epidermal growth factor (EGF) and that binds and activates the EGF receptor. We examined HB-EGF biological action and expression in human pancreatic cancer cell lines, and compared HB-EGF expression in normal and cancerous pancreatic tissues. HB-EGF enhanced the growth of human pancreatic cancer cells in a dose-dependent manner. Several cell lines expressed HB-EGF mRNA transcripts, and the transcript level was enhanced by HB-EGF, as well as by 12-O-tetradecanoylphorbol-13-acetate and transforming growth factor-alpha (TGF-alpha). By comparison with the normal pancreas, HB-EGF mRNA levels were increased in human pancreatic cancer tissues. These findings suggest that HB-EGF may participate in aberrant autocrine and paracrine activation of the EGF receptor, thereby contributing to pancreatic cancer cell growth.

A subgroup of patients with chronic pancreatitis overexpress the c-erb B-2 protooncogene.

OBJECTIVE: Chronic pancreatitis (CP) is a chronic condition associated with pancreatic fibrosis. A small subgroup of patients with CP develop enlargement of the head of the pancreas (EHP). This study examined some of the mechanisms that may lead to the development of EHP. SUMMARY BACKGROUND: The c-erb B-2 protooncogene encodes a 185-kDa transmembrane growth factor receptor (p185) that regulates cell growth and differentiation. METHODS: The authors analyzed c-erb B-2 expression in samples obtained from the head of the pancreas from 26 patients with CP (5 women, 21 men) using immunohistochemical and molecular technique. A diagnosis of CP with EHP was made when the vertical pancreatic head diameter was greater than 4 cm (14 patients), as determined by contrast-enhanced computed axial tomography scan. Pancreatic tissues from 15 healthy organ donors served as control subjects. RESULTS: In all patients without EHP and in the healthy control subjects, p185 immunoreactivity was present at low levels. In contrast, strong p185 immunoreactivity was observed in acinar and ductal cells in all patients with EHP. By in situ hybridization, c-erb B-2 messenger ribonucleic acid (mRNA) grains were expressed at high levels in patients with CP with EHP in both ductal and acinar cells. Northern blot analysis demonstrated a 4.5-fold increase (p < 0.001) in c-erb B-2 mRNA levels in patients with EHP compared with patients without EHP and healthy control subjects. Southern blot analysis did not reveal c-erb B-2 gene amplification or rearrangement. CONCLUSIONS: These findings indicate the c-erb B-2 is not overexpressed in most patients with CP. However, its overexpression in patients with CP with EHP suggest that c-erb B-2 may contribute to the pathophysiologic processes that lead to pancreatic head enlargement.

Cripto, a member of the epidermal growth factor family, is over-expressed in human pancreatic cancer and chronic pancreatitis.

Cripto is a 188 amino-acid protein containing a central segment that shares amino-acid sequence homology with epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). The EGF receptor, EGF and TGF-alpha are expressed in the normal human pancreas, and are over-expressed in human pancreatic cancer. Therefore, in the present study we sought to determine whether cripto is found in the normal human pancreas and whether its expression is altered in pancreatic cancer. Because chronic pancreatitis (CP) is associated with interstitial fibrosis similar to that observed in pancreatic cancer, we also examined cripto expression in pancreatic tissues from patients with CP. In the normal pancreas, cripto immunoreactivity was found at moderate levels in most ductal cells and was present very faintly in a rare acinar cell. In 26 of 58 pancreatic cancers, cripto immunoreactivity was present in many cancer cells. Its presence was associated with advanced tumor stage, but not with shorter post-operative survival. Cripto was also present in acinar and ductal cells adjacent to the cancer cells, and in many ductal atrophic acinar cells in the CP samples. Northern blot analysis revealed a marked increase in cripto mRNA levels in the cancer and CP samples. By densitometry, there was a 11- and 4-fold increase in cripto mRNA levels in pancreatic cancer and CP respectively. Southern blot analysis did not reveal an increase in gene copies encoding cripto either in cancer or in CP. These findings indicate that cripto expression may contribute to disease progression in pancreatic cancer, and implicate cripto in the histopathological alterations that occur in the pancreas both in cancer and in CP.

Increased expression of acidic and basic fibroblast growth factors in chronic pancreatitis.

Acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) belong to a family of mitogenic polypeptides that are involved in cellular proliferation and differentiation. In this study we investigated the potential role of aFGF and bFGF in chronic pancreatitis (CP), a fibrotic condition associated with acinar cell dedifferentiation and atrophy, and fibroblastic proliferation. By immunohistochemistry, aFGF and bFGF were abundant in pancreatic ductal and acinar cells in pancreatic tissues from CP patients. Immunoblotting with the same highly specific monoclonal antibodies demonstrated a marked increase in aFGF and bFGF in pancreatic homogenates from CP patients by comparison with the normal pancreas. Northern blot analysis indicated that, by comparison with normal controls, 16 of 21 CP tissues exhibited a 14-fold increase in aFGF mRNA levels, and 19 of 21 CP tissues exhibited a 15-fold increase in bFGF mRNA levels. In situ hybridization confirmed that this overexpression occurred in ductal and acinar cells, and indicated that both mRNA moieties colocalized with their respective proteins. These findings suggest that aFGF and bFGF may either be involved in the pathobiological mechanisms that occur in CP, or that their overexpression may be the consequence of other perturbations that occur in this disorder.

Overexpression of acidic and basic fibroblast growth factors in human pancreatic cancer correlates with advanced tumor stage.

Acidic fibroblast growth factor (aFGF) and basic FGF (bFGF) are mitogenic polypeptides that may contribute to cancer cell proliferation. In the present study we examined aFGF and bFGF expression in human pancreatic cancer. Northern blot analysis of total RNA isolated from 12 pancreatic cancers revealed elevated aFGF and bFGF mRNA levels in 12 and 10 samples, respectively, by comparison with the normal human pancreas. Immunostaining demonstrated the presence of aFGF and bFGF in many cancer cells and in the atrophic acini and ducts adjacent to the cancer cells, but to a much lesser extent in the surrounding fibroblasts. By in situ hybridization, both mRNA moieties colocalized with their respective proteins and were abundant in many cancer cells. Immunoblotting confirmed that cancer tissues with increased aFGF and bFGF immunoreactivity contained elevated levels of both proteins. To determine the significance of aFGF and bFGF expression in the pancreatic cancer cells, immunohistochemical analysis of 78 human pancreatic carcinomas was performed. aFGF and bFGF immunoreactivity was present in the cancer cells in 47 (60%) and 44 (56%) of the tumors, respectively. There was a significant correlation between the presence of either aFGF or bFGF in the cancer cells and advanced tumor stage, and the presence of bFGF and shorter patient survival. These data suggest that aFGF and bFGF are overexpressed in a significant proportion of human pancreatic carcinoma cells and that this overexpression may contribute to disease progression.

Aberrant expression of type I fibroblast growth factor receptor in human pancreatic adenocarcinomas.

Acidic and basic fibroblast growth factors are mitogenic polypeptides that are overexpressed in pancreatic cancer. To determine whether fibroblast growth factors may exert direct effects on pancreatic cancer cells in vivo, we compared the expression of the high-affinity type I fibroblast growth factor receptor (FGFR-1) in human pancreatic tissues. In the normal pancreas, FGFR-1 immunostaining was seen mainly in acinar cells. In pancreatic cancers, FGFR-1 was abundant in ductal-like cancer cells which also exhibited many FGFR-1 mRNA in situ hybridization grains. Analysis by the polymerase chain reaction and RNase protection revealed that the 2-immunoglobulin-like and the 3-immunoglobulin-like forms of FGFR-1 were expressed in all tissue samples, and that the 2-immunoglobulin-like form was overexpressed in the cancer tissues by comparison with the normal tissues. These findings suggest that the 2-immunoglobulin-like form of FGFR-1 may contribute to aberrant autocrine and paracrine pathways in pancreatic cancer.

Overexpression of HER2/neu oncogene in human pancreatic carcinoma.

The HER2/neu oncogene encodes a transmembrane protein that possesses intrinsic tyrosine kinase activity. Its overexpression has been associated with the malignant phenotype. In this study we examined HER2/neu expression in the normal and cancerous human pancreas. In the normal pancreas HER2/neu immunostaining was observed in acinar and ductal cells. HER2/neu immunoreactivity was expressed in 34 of 76 (45%) pancreatic carcinomas. There was a significant correlation between tumors with well-differentiated histology and HER2/neu expression. Northern blot analysis demonstrated HER2/neu mRNA expression in the normal pancreas and in situ hybridization confirmed its distribution in both acinar and ductal cells. In cancer tissues Northern blot analysis indicated that HER2/neu mRNA levels were elevated in 13 of 25 (52%) of the tumors in comparison with the normal tissues. In addition, in situ hybridization demonstrated a strong but heterogenous distribution of mRNA grains in these tumors. Southern blot analysis did not demonstrate HER2/neu gene amplification in any of the tumors. These data indicate that the HER2/neu protein is synthesized in the normal exocrine pancreas and is frequently overexpressed in well-differentiated adenocarcinomas of the pancreas as a result of increased HER2/neu mRNA levels.