TheerbB-3 Gene in human pancreatic cancer

Concurrent HER or PI3K Inhibition Potentiates the Antitumor Effect of the ERK Inhibitor Ulixertinib in Preclinical Pancreatic Cancer Models

Effective treatment for pancreatic ductal adenocarcinoma (PDAC) is an urgent, unmet medical need. Targeting KRAS, the oncogene that is present in >95% of PDAC, is a heavily pursued strategy, but remains unsuccessful in the clinic. Therefore, targeting key effector cascades of KRAS oncoprotein, particularly the mitogenic RAF-MEK-ERK pathway, represents the next best strategy. However, RAF or MEK inhibitors have failed to show clinical efficacy in PDAC. Several studies have shown that cancer cells treated with RAF or MEK inhibitors adopt multiple mechanisms to reactivate ERK signaling. Therefore, development of ERK-specific inhibitors carries the promise to effectively abrogate this pathway. Ulixertinib (or BVD-523) is a first-in-class ERK-specific inhibitor that has demonstrated promising antitumor activity in a phase I clinical trial for advanced solid tumors with NRAS and BRAF mutations, providing a strong rationale to test this inhibitor in PDAC. In this study, we show that ulixertinib effectively inhibits in vitro growth of multiple PDAC lines and potentiates the cytotoxic effect of gemcitabine. Moreover, we found that PDAC cells treated with ulixertinib upregulates the parallel PI3K-AKT pathway through activating the HER/ErbB family proteins. Concurrent inhibition of PI3K or HER proteins synergizes with ulixertinib in suppressing PDAC cell growth in vitro and in vivo Overall, our study provides the preclinical rationale for testing combinations of ulixertinib with chemotherapy or PI3K and HER inhibitors in PDAC patients. Mol Cancer Ther; 17(10); 2144-55. ©2018 AACR.

MicroRNA-148a Suppresses the Proliferation and Migration of Pancreatic Cancer Cells by Down-regulating ErbB3

OBJECTIVES

ErbB3 (HER3) has been associated with pancreatic cancer progression, but little is known about its regulatory mechanisms. We investigated whether microRNAs (miRNAs) regulate levels of ErbB3 in pancreatic cancer cells.

METHODS

We used bioinformatic analyses to search for miRNAs that can potentially target ERBB3. Furthermore, the biological consequences of the targeting of ERBB3 by miR-148a were examined by cell proliferation and migration assays in vitro.

RESULTS

We identified an inverse correlation between miR-148a and ErbB3 protein levels in pancreatic cancer tissue samples and cell lines. We identified that miR-148a directly recognizes the 3'-UTR of the ErbB3 transcript and regulates ErbB3 expression. We demonstrated that the repression of ERBB3 by miR-148a suppressed the proliferation and migration of pancreatic cancer cells. In PANC-1 pancreatic cancer cells, the repression of ErbB3 by miR-148a inhibited the phosphorylation of ERK1/2 and AKT, which eventually repressed the proliferation and migration of these cells.

CONCLUSIONS

Taken together, the present study provides the first evidence that miR-148a plays a significant role in the suppression of pancreatic tumorigenesis via the inhibition of ErbB3 translation.

Norepinephrine inhibits the migratory activity of pancreatic cancer cells

We have shown previously that norepinephrine induces migratory activity of tumour cells from breast, colon and prostate tissue via activation of beta-2 adrenergic receptors. Consequently, this effect can be inhibited pharmacologically by clinically established beta-blockers. Tumour cell migration is a prerequisite for metastasis formation, and accordingly we and others have shown that breast cancer patients, which take beta-blockers due to hypertension, have reduced metastasis formation and increased survival probability as compared to patients without hypertension or using other anti-hypertensive medication. Unlike the aforementioned tumour cells, pancreatic cancer cells show a reduced migratory activity upon norepinephrine treatment. By means of our three-dimensional, collagen-based cell migration assay, we have investigated the signal transduction pathways involved in this phenomenon. We have found that this conflicting effect of norepinephrine on pancreatic cancer cells is due to an imbalanced activation of the two pathways that usually mediate a pro-migratory effect of norepinephrine in other tumour cell types. Firstly, the inhibitory effect results from activation of a pathway which causes a strong increase of the secondary cell signalling molecule, cAMP. In addition, activation of phospholipase C gamma and the downstream protein kinase C alpha were shown to be already activated in pancreatic cancer cells and cannot be further activated by norepinephrine. We hypothesize that this constitutive activation of the phospholipase C gamma pathway is due to a cross-talk with receptor tyrosine kinase signalling, and this might also deliver an explanation for the unusual high spontaneous migratory activity of pancreatic cancer cells.

HER3 overexpression as an independent indicator of poor prognosis for patients with curatively resected pancreatic cancer

OBJECTIVE

The association between human epidermal growth factor receptor 3 (HER3) overexpression and survival in patients with curatively resected pancreatic cancer was investigated.

METHODS

Tissue samples from 126 pancreatic cancers without hematogenous or peritoneal metastases recovered from macroscopically curative resection were fixed with formalin, embedded in paraffin and subjected to immunohistochemical staining. Semiquantitative scores of zero (no staining or staining in less than 10% of cancer cells), 1+, 2+, or 3+ were assigned to each sample based on the intensity of staining. Scores of 2+ or 3+ were defined as HER3-positive staining, i.e., HER3 overexpression.

RESULTS

HER3 overexpression was observed in 52 of the 126 tissue samples (41.3%). There were no associations between HER3 overexpression and clinicopathological factors, including tumor location, tumor size, tumor differentiation, T/N categories according to the International Union against Cancer, and serum carbohydrate antibody 19-9 level (CA19-9). Univariate analysis demonstrated the median survival time of patients with HER3 overexpression was 37.2 months, while that of patients with HER3-negative samples was 58.6 months (p = 0.008). HER3 overexpression, lymph node metastasis, and elevated serum CA19-9 level were independent predictors of poor prognosis based on multivariate survival analysis.

CONCLUSION

A new prognostic predictor, HER3 overexpression, was identified for resected pancreatic cancer.

Targeting ErbB3-mediated stromal-epithelial interactions in pancreatic ductal adenocarcinoma

Background:

We sought to investigate the role of ErbB3-mediated signalling on the interaction between pancreatic cancer-associated fibroblasts (CAF) and carcinoma cells in an effort to disrupt tumourigenic pancreatic ductal adenocarcinoma (PDAC) stromal–epithelial cross-communication.

Methods:

Primary CAF cultures were established from human PDAC surgical specimens. AsPC-1 pancreatic cancer cell murine subcutaneous xenografts were developed in the presence and absence of CAF and were subsequently treated with epidermal growth factor receptor (EGFR) inhibitors (erlotinib) and ErbB3 inhibitors (MM-121, monoclonal ErbB3 antibody).

Results:

Cancer-associated fibroblasts were found to secrete neuregulin-1 (NRG-1), which promoted proliferation via phosphorylation of ErbB3 and AKT in AsPC-1 PDAC cells. This signalling cascade was effectively inhibited both in vitro and in vivo by specific ErbB3 blockade with MM-121, with greater degree of tumourigenesis inhibition when combined with erlotinib. The CAF–AsPC-1 pancreatic cancer xenografts reached significantly greater tumour volume than those xenografts lacking CAF and were resistant to the anti-tumour effects of EGFR inhibition with erlotinib.

Conclusion:

Cancer-associated fibroblasts-derived NRG-1 promote PDAC tumourigenesis via ErbB3-AKT signalling and overcomes single-agent EGFR inhibition. Disruption of this stromally mediated tumourigenic mechanism is best obtained through combined EGFR-ErbB3 inhibition with both erlotinib and MM-121. We have identified the NRG-1/ErbB3 axis as an attractive molecular target for the interruption of tumourigenic stromal–epithelial interactions within the PDAC microenvironment.

Nuclear HER3 is associated with favorable overall survival in uveal melanoma

HER3 is a member of the epidermal growth factor receptor (EGFR) family and is expressed in several types of cancer. Both the cytoplasmic and nuclear appearances of the receptor have been reported. Here, we investigate the expression and subcellular distribution of HER3 in uveal melanoma (UM) cells and tissues and its potential impact on clinical outcome of patients. Paraffin-embedded samples from 128 consecutive UM patients, enucleated without alternative treatment on UM diagnosis, were evaluated for HER3 using immunohistochemistry. Immunoreactivity was scored for frequency, intensity of positive cells, and subcellular distribution. The results were correlated with the established clinicopathological parameters using univariate and multivariate statistical analyses. HER3 expression was shown in 70% of the cases (89/128). This contrasts with the other EGFR family receptors (EGFR, HER2 and HER4) that are infrequently expressed in UM. Surprisingly, HER3 was found to be localized solely in the cell nuclei in 56 cases. The remaining 33 HER3 positive cases showed diffuse distribution (cytoplasmic ± nuclear). Nuclear HER3 was independently correlated with a more favorable overall survival (p = 0.043 and hazard ratio = 0.618) compared to cases with diffuse and/or no HER3. Nuclear localization of HER3 was also confirmed in fresh UM material and in UM cell lines. In conclusion, HER3 is frequently localized solely in the cell nuclei in UM and as such it predicts a more favorable overall survival.

Challenges of drug resistance in the management of pancreatic cancer

The current treatment of choice for metastatic pancreatic cancer involves single-agent gemcitabine or a combination of gemcitabine with capecitabine or erlotinib (a tyrosine kinase inhibitor). Only 25–30% of patients respond to this treatment and patients who do respond initially ultimately exhibit disease progression. Median survival for pancreatic cancer patients has reached a plateau due to inherent and acquired resistance to these agents. Key molecular factors implicated in this resistance include: deficiencies in drug uptake, alteration of drug targets, activation of DNA repair pathways, resistance to apoptosis and the contribution of the tumor microenvironment. Moreover, for newer agents including tyrosine kinase inhibitors, overexpression of signaling proteins, mutations in kinase domains, activation of alternative pathways, mutations of genes downstream of the target and/or amplification of the target represent key challenges for treatment efficacy. Here we will review the contribution of known mechanisms and markers of resistance to key pancreatic cancer drug treatments.

EGFR(s) in aging and carcinogenesis of the gastrointestinal tract

Cells of the gastrointestinal (GI) mucosa are subject to a constant process of renewal which, in normal adults, reflects a balance between the rates of cell production and cell loss. Detailed knowledge of these events is, therefore, essential for a better understanding of the normal aging processes as well as many GI diseases, particularly malignancy, that represent disorders of tissue growth. In general, many GI dysfunctions, including malignancy, increase with advancing age, and aging itself is associated with alterations in structural and functional integrity of the GI tract. Although the regulatory mechanisms for age-related increase in the incidence of GI-cancers are yet to be fully delineated, recent evidence suggests a role for epidermal growth family receptors and its family members {referred to as EGFR(s)} in the development and progression of carcinogenesis during aging. The present communication discusses the involvement of EGFR(s) in regulating events of GI cancers during advancing age and summarizes the current available therapeutics targeting these receptors. The current review also describes the effectiveness of ErbB inhibitors as well as combination therapies. Additionally, the involvement of GI stem cells in the development of the age-related rise in GI cancers is emphasized.

ErbB3 expression promotes tumorigenesis in pancreatic adenocarcinoma

Historically, ErbB3 has been overlooked within the ErbB receptor family due to its perceived lack of tyrosine kinase activity. We have previously demonstrated that in pancreatic cancer ErbB3 is the preferred dimerization partner of EGFR, ErbB3 protein expression level directly correlates with the anti-proliferative effect of erlotinib (an EGFR-specific tyrosine kinase inhibitor), and transient knockdown of ErbB3 expression results in acquired resistance to EGFR-targeted therapy. In this study, we develop a stable isogenic model of ErbB3 expression in an attempt to decipher ErbB3's true contribution to pancreatic cancer tumorigenesis and to examine how this receptor affects cellular sensitivity to EGFR-targeted therapy. Analysis of the EGFR-ErbB3 heterodimer demonstrates that ligand-induced PI3K-AKT signaling is limited to ErbB3-expressing cells and that this signaling cascade can be partially abrogated by inhibiting EGFR function with erlotinib. Using our model of exogenous ErbB3 expression we showed a direct relationship between ErbB3 protein levels and increased pancreatic cancer cell proliferation in vitro. In vivo, ErbB3(+)PANC-1 xenografts had a significantly larger tumor volume than PANC-1 control xenografts (ErbB3-PANC-1) and displayed increased sensitivity to EGFR-targeted therapy. In pancreatic cancer, ErbB3 appears to be critically involved in EGFR signaling as evidenced by its profound effect on cellular proliferation and its ability to influence response to EGFR-targeted therapy.

c-erbB3 protein expression in ovarian cancer

Aims-To study the prevalence of overexpression of c-erbB3 growth factor receptor in ovarian carcinomas and to analyse its relation to histological subtype, stage and grade of the tumours.Methods-Ninety eight ovarian carcinomas were evaluated immunohistochemically using the RTJ1 monoclonal antibody raised against a synthetic peptide, the sequence of which was derived from the cytoplasmic domain of the c-erbB3 protein.Results-Of the tumours, 16% (16/98) overexpressed c-erbB3 protein relative to normal ovarian epithelium, whereas 22% (22/98) were completely negative. There was a statistically significant association between overexpression and well differentiated grade.Conclusions-These findings suggest that c-erbB3 protein overexpression occurs in a significant proportion of ovarian cancers and is correlated with differentiation. Overexpression may merit further investigation as a potential prognostic indicator and as a target for new treatment.

HER3 comes of age: new insights into its functions and role in signaling, tumor biology, and cancer therapy

The human epidermal growth family (HER) of tyrosine kinase receptors underlies the pathogenesis of many types of human cancer. The oncogenic functions of three of the HER proteins can be unleashed through amplification, overexpression, or mutational activation. This has formed the basis for the development of clinically active targeted therapies. However, the third member HER3 is catalytically inactive, not found to be mutated or amplified in cancers, and its role and functions have remained shrouded in mystery. Recent evidence derived primarily from experimental models now seems to implicate HER3 in the pathogenesis of several types of cancer. Furthermore, the failure to recognize the central role of HER3 seems to underlie resistance to epidermal growth factor receptor (EGFR)- or HER2-targeted therapies in some cancers. Structural and biochemical studies have now greatly enhanced our understanding of signaling in the HER family and revealed the previously unrecognized activating functions embodied in the catalytically impaired kinase domain of HER3. This renewed interest and mechanistic basis has fueled the development of new classes of HER3-targeting agents for cancer therapy. However, identifying HER3-dependent tumors presents a formidable challenge and the success of HER3-targeting approaches depends entirely on the development and power of predictive tools.

Pancreatic cancer: advances in medical therapy

Progress in the treatment of pancreatic cancer has been notably slow and modest in contrast to other cancers of the GI tract over the last 5 years. Pancreatic cancer still continues to be a devastating illness that is marked by the appearance of early metastatic disease, despite curative surgery and the relative chemoresistance of the disease. However, small incremental benefits have been seen, and point to areas of research and development over the subsequent years. Developments in adjuvant chemotherapy and the use of gemcitabine in combination with other cytotoxic agents or with biological agents have changed clinical practice. Given its poor outlook and the paucity of active therapies, even modest gains can lead to regulatory approval and, therefore, pancreatic cancer represents a common target for pharmaceutical companies. Newer agents are in development with the promise of further refinement in treatment selection based on molecular tumor characteristics.

The ERBB3 receptor in cancer and cancer gene therapy

ERBB3, a member of the epidermal growth factor receptor (EGFR) family, is unique in that its tyrosine kinase domain is functionally defective. It is activated by neuregulins, by other ERBB and nonERBB receptors as well as by other kinases, and by novel mechanisms. Downstream it interacts prominently with the phosphoinositol 3-kinase/AKT survival/mitogenic pathway, but also with GRB, SHC, SRC, ABL, rasGAP, SYK and the transcription regulator EBP1. There are likely important but poorly understood roles for nuclear localization and for secreted isoforms. Studies of ERBB3 expression in primary cancers and of its mechanistic contributions in cultured cells have implicated it, with varying degrees of certainty, with causation or sustenance of cancers of the breast, ovary, prostate, certain brain cells, retina, melanocytes, colon, pancreas, stomach, oral cavity and lung. Recent results link high ERBB3 activity with escape from therapy targeting other ERBBs in lung and breast cancers. Thus a wide and centrally important role for ERBB3 in cancer is becoming increasingly apparent. Several approaches for targeting ERBB3 in cancers have been tested or proposed. Small inhibitory RNA (siRNA) to ERBB3 or AKT is showing promise as a therapeutic approach to treatment of lung adenocarcinoma.

Somatic mutations of the epidermal growth factor receptor and non-small-cell lung cancer

Frequent overexpression of epidermal growth factor receptor (EGFR) in non-small-cell lung cancer (NSCLC) makes EGFR a new therapeutic target. Two specific EGFR tyrosine kinase inhibitors, gefitinib (ZD1839, Iressa) and erlotinib (OSI-774, Tarceva), have been developed and approved by the US Food and Drug Administration for second-line and third-line treatment of advanced NSCLC. Clinical trials have shown considerable variability in the response rate between different patients with NSCLC, which led to the discovery of somatic EGFR-activating mutations. This brief review summarises the discovery and functional consequences of the mutations, their clinicopathological features and significant implications in the treatment and prognosis of NSCLC.

Expression and differential signaling of heregulins in pancreatic cancer cells

The EGF family of ligands and receptors plays an important role in the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) and contributes to its aggressiveness. A number of molecular approaches have been developed to block these pathways, and studies have already proven the clinical benefit of this concept in PDAC. In the present study, we sought to determine the potential role of heregulins (HRGs), a family of EGF-like growth factors, in PDAC. Quantitative RT-PCR analysis revealed that HRGs as well as its signaling ErbB receptors were present in 4 of 4 human pancreatic cancer cell lines (PCCL). HRG-beta1 stimulated the growth of 3 of 4 PCCL, whereas HRG-alpha1 inhibited cell growth in 3 of 4 cell lines. Responses towards HRGs could in part be predicted by ErbB2 and ErbB3 expression levels. HRGs induced phosphorylation of different ErbB receptors as well as activation of MAPK, p38MAPK, JNK and PI3K in a cell- and ligand-specific manner. In vivo, HRG was upregulated in pancreatic cancer tissues and localized predominantly in the cancer cells. High HRG-beta levels but not HRG-alpha levels were associated with decreased patient survival. In conclusion, HRG is expressed by pancreatic cancer cells and influences pancreatic cancer cell growth and patient survival.

Detailed tissue expression of bcl-2, bax, bak and bcl-x in the normal human pancreas and in chronic pancreatitis, ampullary and pancreatic ductal adenocarcinomas

BACKGROUND

The aim of this study was to evaluate expression of the bcl-2 family of apoptosis regulating proteins in normal and diseased human pancreatic tissues.

METHOD

Expression of bcl-2, bax, bcl-x, bak and p53 was determined in formalin-fixed paraffin wax-embedded archival specimens of normal pancreatic tissue (n = 7), chronic pancreatitis (n = 7), pancreatic ductal adenocarcinoma (n = 23) and ampullary cancer (n = 7) by immunohistochemistry using specific antibodies.

RESULTS

In normal pancreas and chronic pancreatitis tissues, bcl-2, bax and bcl-x were predominantly expressed in ductal epithelial cells while p53 was not detected. In pancreatic ductal adenocarcinoma and ampullary cancer, bcl-2 was not detected compared with expression seen in normal acini (p < 0.01), minor (p < 0.001) and major ducts (p < 0.01), bax expression was reduced with respect to minor ducts (p < 0.01) but no different from normal acini or major ducts. bak and bcl-x were more strongly expressed in malignant epithelia compared with acini and major ducts but reduced when compared with minor ducts (p < 0.01). Overexpression of p53 was identified in 11 (48%) of 23 pancreatic adenocarcinomas and 4 (57%) of 7 ampullary cancers. Differential survival of individual patients was predicted by the relative level of bcl-x expression but not bax or bak, such that strong expression of bcl-x was associated with a median postoperative survival of 171 days when compared with 912 days for diminished expression (p < 0.001) of bcl-x.

CONCLUSION

Pancreatic and ampullary cancer are associated with absent bcl-2 expression. bax, bak and bcl-x expression was reduced compared with normal minor ducts whilst bak and bcl-x expression was increased when compared with major ducts. bcl-x expression correlates with survival following resection and may represent a potential prognosis marker.

The significance of immunohistochemistry in the diagnosis and therapy of neoplasms

This review article details the diagnostical significance of immunohistochemistry, which has developed during the last quarter of the century. Certainly, the advancement of monoclonal antibody technology has been of great significance in assuring the place of immunohistochemistry in the modern accurate microscopic diagnosis of human neoplasms, as a method of choice in histopathology. The fact still remains that in order to properly assess any immunohistochemical reactivity used for differential diagnostic purposes, the target cells have to be identified as neoplastically transformed cells by routine histopathological techniques. Selected groups of target molecules of great significance in cancer biology are discussed. The discovery of neoplasm-associated antigens has not only made the more accurate diagnosis of human cancer feasible but has also shed light on the extensive immunophenotypical heterogeneity of even the most closely linked human malignancies. The identification of disseminated neoplastically transformed cells by immunohistochemistry has allowed for a clearer picture of cancer invasion and metastasis, as well as the evolution of the tumour cell associated immunophenotype towards increased malignancy. Some possibilities of neoplasm-associated antigen targeted, receptor-directed immunotherapy are discussed and reviewed in this manuscript. Future antineoplastic therapeutical approaches should see the inclusion of a variety of immunotherapies, in the form of an individualised 'cocktail' specific for the particular immunophenotypical pattern associated with each individual patient's neoplastic disease.

K-ras oncogene subtype mutations are associated with survival but not expression of p53, p16(INK4A), p21(WAF-1), cyclin D1, erbB-2 and erbB-3 in resected pancreatic ductal adenocarcinoma

Previous studies of molecular prognostic markers following resection for exocrine pancreatic cancer have produced conflicting results. Our aim was to undertake a comprehensive analysis of potentially useful molecular markers in a large, multicentre patient population and to compare these markers with standard pathological prognostic variables. Formalin-fixed, paraffin-embedded specimens of pancreatic ductal adenocarcinoma were analysed from 157 patients [100 men and 57 women with a median (range) age of 60 (33-77) years] who had undergone pancreatectomy. Immunohistochemistry was used to detect expression of p16(INK4), p53, p21(WAF1), cyclin D1, erbB-2 and erbB-3. Mutations in codons 12 and 13 of the K-ras oncogene were detected by SSCP and sequencing following DNA extraction and amplification by PCR. The median (range) survival post-resection was 12.5 (3-83) months. Abnormalities of p16(INK4), p53, p21(WAF1), cyclin D1, erbB-2 and erbB-3 expression were found in 87%, 41%, 75%, 72%, 33% and 57% of cases, respectively. There was no significant correlation between expression of any of these markers and patient survival. K-ras mutations were found in 73 (75%) of 97 cases with amplifiable DNA. The presence of K-ras mutation alone did not correlate with survival, but there were significant differences in survival according to the type of K-ras mutation (p = 0.0007). Reduced survival was found in patients with GaT, cGT and GcT K-ras mutations compared to GtT, aGT and GaC mutations. In conclusion, survival was associated with type of K-ras mutation but not expression of p16(INK4), p53, p21(WAF1), cyclin D1, erbB-2 and erbB-3.

Molecular biology of pancreatic cancer; oncogenes, tumour suppressor genes, growth factors, and their receptors from a clinical perspective

Pancreatic cancer represents the fourth leading cause of cancer death in men and the fifth in women. Prognosis remains dismal, mainly because the diagnosis is made late in the clinical course of the disease. The need to improve the diagnosis, detection, and treatment of pancreatic cancer is great. It is in this type of cancer, in which the mortality is so great and the clinical detection so difficult that the recent advances of molecular biology may have a significant impact. Genetic alterations can be detected at different levels. These alterations include oncogene mutations (most commonly, K-ras mutations, which occur in 75% to more than 95% of pancreatic cancer tissues), tumour suppressor genes alterations (mainly, p53, p16, DCC, etc.), overexpression of growth factors (such as EGF, TGF alpha, TGF beta 1-3, aFGF, bTGF, etc.) and their receptors (i.e., EGF receptor, TGF beta receptor I-III, etc.). Insights into the molecular genetics of pancreatic carcinogenesis are beginning to form a genetic model for pancreatic cancer and its precursors. These improvements in our understanding of the molecular biology of pancreatic cancer are not simply of research interest, but may have clinical implications, such as risk assessment, early diagnosis, treatment, and prognosis evaluation.

Proteins expressed by pancreatic duct cells and their relatives

Significant progress has been made in the characterization of the structure and function of pancreatic ductal cells. Our understanding at this point in time extends to knowledge of specific molecules that provide for the structural composition of the ductal cells, their interactions with the local environment, and the regulation of their growth and properties of differentiation. Knowledge of the molecular composition and structure of the secretory products of epithelial cells in the pancreas also has increased so that we now understand the individual contributions of several secretory products to the overall function of pancreatic juice. Further study of these parameters will give us important insight into the normal function of the ductal cells and into how these processes are altered during the development and progression of diseases of the pancreas such as pancreatitis and cancer.

Growth factors and cytokines in pancreatic carcinogenesis

Pancreatic cancer is a deadly disease challenging basic and clinical researchers alike in characterizing its pathobiology and finding better treatment options. A number of molecular alterations including gene mutations such as k-ras, p53, and Smad4 and aberrant expression of a variety of genes have been identified in recent years. This review focuses on two families of growth factors and growth factor receptors which are representative for the molecular alterations observed in pancreatic cancer: the transforming growth factor-beta superfamily of serine-threonine kinase receptors and their ligands, which usually act as negative growth regulators, and the epidermal growth factor receptor family and their ligands, which have the potential to act as growth promoters in pancreatic cancer. In addition, we will discuss the role of the cytokines TNF-alpha, IFN-gamma, and IL-6 and its effects on pancreatic cancer cell proliferation in vitro and in vivo. Pancreatic cancer cell biology consists of complex interactions of various factors, and a better understanding of the molecular pathogenesis of this disorder might lead to better treatment strategies in the near future.

Serum and correspondent tissue measurements of epidermal growth factor (EGF) and epidermal growth factor receptor (EGF-R). Clinical relevance in pancreatic cancer and chronic pancreatitis

CONCLUSION

The results of this study show that routine measurements of epidermal growth factor (EGF) and epidermal growth factor receptor (EGF-R) cannot improve screening for pancreatic cancer despite the frequently present tissue overexpression. Both values fail to reveal this malignancy in a serum test. Patients with chronic pancreatitis exhibit no or very low concentrations of EGF. In cases where preoperative diagnosis is difficult the noninvasive EGF and EGF-R serum measurements may be helpful in discriminating between pancreatic cancer and chronic pancreatitis.

BACKGROUND

EGF and EGF-R are frequently overexpressed in the tissue of patients suffering from ductal pancreatic cancer and to lesser degree in patients with chronic pancreatitis. The aim of this study was to determine the value of serum measurements in these patients to detect malignant pancreatic disease. In cases of pancreatic cancer, the tissue expression of EGF and EGF-R was evaluated by immunohistochemistry.

METHOD

Thirty-five patients with chronic pancreatitis and 31 patients with pancreatic cancer were evaluated; 71 patients admitted for routine surgery (hernia repair, cholecystectomy, goiter surgery) served as controls.

RESULTS

EGF and EGF-R values were not significantly different in pancreatic cancer as compared to controls and did not correlate with other tumor markers (CA 19-9, carcinoembryonic antigen [CEA], tumor polypeptide antigen [TPA]) or with the stage of the disease. Fourteen patients (67%) with pancreatic cancer displayed tissue overexpression for EGF and 11 patients for EGF-R (52%). These patients, however, also failed to exhibit any significant pathological changes in serum concentration. In chronic pancreatitis, EGF and EGF-R were significantly decreased as compared to pancreatic cancer and controls. This was an unexpected finding. There was a positive correlation to clinical exocrine insufficiency.

Expression of c-erbB3 protein in primary breast carcinomas

Expression of c-erbB3 protein was investigated in 104 primary breast carcinomas comprising nine comedo ductal carcinoma in situ (DCIS), 91 invasive ductal carcinomas and four invasive lobular carcinomas using two monoclonal antibodies, RTJ1 and RTJ2. Of the 91 invasive ductal carcinomas, seven contained the comedo DCIS component adjacent to the invasive component. An immunohistochemical technique was used to evaluate the association between expression of c-erbB3 and clinical parameters and tumour markers such as epidermal growth factor receptor (EGFR), c-erbB2, cathepsin-D and p53 in archival formalin-fixed paraffin-embedded tumour tissues. Our results indicated that RTJ1 and RTJ2 gave identical staining patterns and concordant results. It was found that the overexpression of c-erbB3 protein was observed in 67% (6/9) of comedo DCIS, 52% (44/84) of invasive ductal carcinomas, 71% (5/7) of carcinomas containing both the in situ and invasive lesions and 25% (1/4) of invasive lobular carcinomas. A significant relationship (P < 0.05) was observed between strong immunoreactivity of c-erbB3 protein and histological grade, EGFR and cathepsin-D, but not with expression of c-erbB2, p53, oestrogen receptor status, lymph node metastases or age of patient. However, we noted that a high percentage of oestrogen receptor-negative tumours (59%), lymph node-positive tumours (63%) and c-erbB2 (63%) were strongly positive for c-erbB3 protein. We have also documented that a high percentage of EGFR (67%), c-erbB2 (67%), p53 (75%) and cathepsin-D-positive DCIS (60%) were strongly positive for c-erbB3. These observations suggest that overexpression of c-erbB3 protein could play an important role in tumour progression from non-invasive to invasive and, also, that it may have the potential to be used as a marker for poor prognosis of breast cancer.

Increased expression of erbB3 in colorectal cancer is associated with concomitant increase in the level of erbB2

ErbB3 is a transmembrane signaling molecule that shares close structural homology with epidermal growth factor receptor (EGFR), erbB2, and erbB4. They have all been implicated in cell transformation and tumor pathogenesis, but very little is known about the role of erbB3 in normal colon and colorectal cancer. Therefore, in the current study, we determined whether erbB3 is found in normal human colon and whether its expression is altered in colorectal cancer. Because of some evidence that erbB3 might interact with erbB2 and EGFR, respectively, by heterodimerization, we also included erbB2 and EGFR analysis with special regard to coexpression. The study was performed on 35 patients operated on for colorectal carcinoma. The normal human colon showed weak erbB3 and erbB2 immunostaining, predominantly in surface epithelial cells. EGFR immunoreactivity in normal colon varied from weak to strong. In contrast, in 31 of 35 (89%) and in 29 of 35 (83%) colonic cancers, moderate to strong immunoreactivity for erbB3 and erbB2, respectively, was present in most epithelial cancer cells. A concomitant erbB3 and erbB2 immunostaining advantage could be found in 77% of cancerous tissues in comparison with the normal colon. No difference in EGFR immunostaining was evident between normal colon and cancer. Northern blot analysis showed an increase in erbB3 and erbB2 mRNA levels in 64% of cancers in comparison with normal colon samples. By densitometry, 2.3-fold and a 1.5-fold significant increases in erbB3 and erbB2 mRNA levels, respectively, were calculated in the cancerous tissues. Eighty-five percent of cancers with erbB3 mRNA overexpression showed an increase in erbB2 mRNA. Southern blot analysis did not indicate any gene amplification or rearrangement responsible for erbB2 or erbB3 overexpression. EGFR, however, was decreased in cancer on mRNA level. These findings indicate that erbB2 and erbB3, but not EGFR, may contribute to tumor growth and disease progression in colon cancer. The correlation between increased erbB2 and erbB3 expression in both Northern blots and immunohistochemical analysis suggests a co-overexpression of erbB2 and erbB3 and might support the hypothesis that these two growth factor receptors act together by heterodimer formation.

Comparative phenotypic studies of duct epithelial cell lines derived from normal human pancreas and pancreatic carcinoma

We have investigated the mRNA/protein expression of several tyrosine kinase receptors, growth factors, and p16INK4A cyclin inhibitor in cell lines derived from normal human pancreatic duct epithelium (HPDE) and compared them with those of five pancreatic ductal carcinoma cell lines. Cultured HPDE cells express low levels of epidermal growth factor receptor (EGFR), erbB2, transforming growth factor (TGF)-alpha, Met/hepatocyte growth factor receptor (HGFR), vascular endothelial growth factor (VEGF), and keratinocyte growth factor (KGF). They also expressed high levels of amphiregulin but did not express EGF and cripto. The expression levels were similar in primary normal HPDE cells and those expressing transfected E6E7 genes of human papilloma virus-16, but their immortalization appeared to enhance the expression of EGFR and Met/HGFR. In comparison, pancreatic carcinoma cell lines commonly demonstrated overexpression of EGFR, erbB2, TGF-alpha, Met/HGFR, VEGF, and KGF, but they consistently showed marked down-regulation of amphiregulin mRNA expression. In contrast to all carcinoma cell lines that showed deletions of the p16 gene, HPDE cells consistently demonstrated normal p16 genotype and its mRNA expression. This is the first report that compares the phenotypic expression of cultured pancreatic ductal carcinoma cells with epithelial cell lines derived from normal human pancreatic ducts. The findings confirm that malignant transformation of human pancreatic duct cells commonly results in a deregulation of expression of various growth factors and receptors.

The use of molecular technology in the differentiation of pancreatic cancer and chronic pancreatitis

CONCLUSION

It is concluded that currently there are limitations in the use of some of the proposed tests, whereas in the future, further progress in our understanding of the molecular biology of pancreatic disease and the development and application of existing techniques should have a greater impact on clinical practice.

BACKGROUND

Fifteen to 20% of patients with pancreatic cancer present with a resectable mass in the head of the pancreas, but there is a subgroup of patients for whom it is difficult to reach the correct diagnosis.

METHOD

This article addresses how molecular technology can be used to aid in the diagnosis of this group of patients. The clinical and scientific literature is reviewed by accessing papers through the Medline database.

RESULTS

This article reviews the limitations of conventional imaging techniques and the limitations of fine needle aspiration cytology and cytological examination of pancreatic duct secretions. The molecular biology of both pancreatic cancer and chronic pancreatitis is then reviewed with emphasis on the common molecular defects seen in these diseases. The current use of molecular techniques in the examination of cytological and histological specimens, stool, blood, and pancreatic duct secretions and how this helps discriminate between benign and malignant lesions of the pancreas is addressed. Finally, the use of novel serum screening tests in groups at high risk of pancreatic cancer is discussed.

Overexpression and activation of the tyrosine kinase Src in human pancreatic carcinoma

Src family tyrosine kinases participate in the regulation of cell adhesion, cell growth and differentiation. Here, we examine for the first time the potential role of Src for growth regulation of human pancreatic carcinoma cells. By immunohistochemical analysis, Src was overexpressed in 13/13 pancreatic carcinoma tissue but not in 6 normal pancreatic tissue specimen. In Western blots of total cellular extracts, Src protein expression was elevated in 14/17 carcinoma cell lines as compared to normal pancreas or cultured human pancreatic duct cells. Kinase activity was only detectable in cancer cells and did not correlate with the amount of kinase protein or with the expression of the regulatory kinase Csk, indicating that Src is not regulated through protein expression or through expression of Csk. The Src-specific tyrosine kinase inhibitor herbimycin A decreased cell growth in a dose-dependent manner. We suggest that Src family kinases participate in growth regulation of pancreatic cancer cells.

ErbB3 is required for normal cerebellar and cardiac development: a comparison with ErbB2-and heregulin-deficient mice

Heregulins bind directly to ErbB3 and ErbB4 receptors, leading to multiple dimerization possibilities including heterodimerization with the ErbB2 receptor. We have generated ErbB3-, ErbB2- and heregulin-deficient mice to assess their roles in development and differentiation. Heregulin(−/−) and ErbB2(−/−) embryos died on E10.5 due to a lack of cardiac ventricular myocyte differentiation; ErbB3(−/−) embryos survived until E13.5 exhibiting cardiac cushion abnormalities leading to blood reflux through defective valves. In ErbB3(−/−) embryos, the midbrain/hindbrain region was strikingly affected, with little differentiation of the cerebellar plate. Cranial ganglia defects, while present in all three nulls, were less severe in ErbB3(−/−) embryos. The cranial ganglia defects, along with a dramatic reduction in Schwann cells, enteric ganglia and adrenal chromaffin cells, suggests a generalized effect on the neural crest. Numerous organs, including the stomach and pancreas also exhibited anomalous development.

The molecular genetics of pancreatic cancer

Pancreatic cancer is the fifth leading cause of cancer death in the United States, and despite improvements in the results of surgical treatment for this disease, little impact has been made upon overall mortality. New advances in treatment will depend upon improved adjuvant therapy, early diagnosis, and a better understanding of tumor biology. This article summarizes the results of molecular genetic studies in pancreatic cancer and their potential clinical significance. Familial predisposition to pancreatic cancer, cytogenic studies, DNA ploidy analysis, and examination of specific oncogenes and tumor suppressor genes are reviewed. The most frequent mutations detected have been in the K-ras oncogene, which occur in 80% of pancreatic cancers. These mutations do not correlate with tumor stage or survival, but can be useful in differentiating pancreatic exocrine from endocrine tumors and chronic pancreatitis. Mutations in the p53 gene occur in approximately 50% of tumors, and appear to be an independent prognostic factor for patient survival. Mutations in the CDKN2 gene are frequently seen in sporadic pancreatic cancers, and have been implicated in cases of familial pancreatic cancer. The significance of mutations in APC, MCC, DCC, c-erbB-2, RB-1, and mismatch repair genes in the genesis of pancreatic cancer is less clear.

Expression of the type 1 tyrosine kinase growth factor receptors EGF receptor, c-erbB2 and c-erbB3 in bladder cancer

Expression of the c-erbB3 protein was determined in transitional cell carcinoma of the bladder by immunohistochemistry. Strong membrane staining was observed in 10 per cent of cases (7/70) and cytoplasmic and membrane overexpression in 20 per cent (14/70). Overexpression of the epidermal growth factor (EGF) receptor (36 per cent, 25/70) and c-erbB2 proteins (9 per cent 6/70) was determined in the same series of cases. c-erbB3 overexpression was positively correlated with EGF receptor expression (P < 0.025) but appeared to be inversely associated with c-erbB2 overexpression.

Molecular oncology in pancreatic cancer

Cancer of the pancreas still has a very poor prognosis despite improved diagnostic methods and therapeutic regimens. The reasons for the aggressiveness of this cancer are not known, and the molecular mechanisms that govern the growth of pancreatic cancer cells are still not clearly defined. During the past two decades the development of new molecular biological techniques has offered new perspectives for a better understanding of pancreatic cancer. Tumor markers such as CA19-9 and CEA are used for diagnosis and for following the postoperative course of cancer patients. Characterization of pancreatic cancer cells using several molecular biological techniques has revealed overexpression or altered expression of growth factors and adhesion molecules, implying altered cell-cell and growth-regulatory interactions. In pancreatic cancer mutations in oncogenes and tumor suppressor genes are frequently detected in p53 and K-ras. This article reviews the possible molecular approaches for diagnosis, prognosis, or even therapy of pancreatic cancer.

Overexpression of different members of the type 1 growth factor receptor family and their association with cell proliferation in periampullary carcinoma

The expression of epidermal growth factor receptor (EGFR), c-erbB-2, and c-erbB-3 was examined immunohistochemically in 57 cases of periampullary carcinoma. The percentage of Ki-67-positive cells was also examined in the same tissue, to determine the relationship between the expression of the members of the type I growth factor receptor family and cell proliferation. In carcinoma of the head of pancreas, the percentage of cases with overexpression of c-erbB-3 was significantly higher than with overexpression of c-erbB-2 and EGFR. In contrast, in lower bile duct carcinoma and carcinoma of the ampulla of Vater, the percentages of cases with overexpression of c-erbB-2 was greater than with overexpression of other growth factor receptors. A higher percentage of cases with overexpression of c-erbB-3 in pancreatic head carcinoma and overexpression of c-erbB-2 in carcinoma of the ampulla of Vater was found in Ki-67 antigen-positive cases. Moreover, the overexpression of c-erb-3 in pancreatic head carcinoma, c-erb-2 in ampulla of Vater carcinoma, and Ki-67 in both carcinomas was found to be associated with poor patient outcome. These results demonstrate that different members of the type I growth factor receptor family are overexpressed in different carcinomas of the periampullary region.

Molecular and immunohistochemical study of class I growth factor receptors in squamous cell lung carcinomas

The class I growth factor receptor family includes epidermal growth factor receptor, i.e. c-erbB-1, c-erbB-2 and c-erbB-3 molecules. These receptors have a significant sequence homology and play an important role in cell growth and differentiation. To further investigate their implication in squamous cell lung carcinomas (SqCLCs), we studied the protein expression by immunohistochemistry and examined for possible gene amplification by a novel semi-quantitative differential polymerase chain reaction (DPCR) technique. Expression of c-erbB-1, c-erbB-2 and c-erbB-3 was present in 65%, 28% and 10% respectively, of 40 SqCLCs cases. Seven of the 11 cases that expressed c-erbB-2, as well as all 4 c-erbB-3 expressing cases, also stained with the anti-c-erbB-1 mAb. Expression of c-erbB-1, but not of c-erbB-2 or c-erbB-3, correlated with the grade of tumor differentiation (100%, 64% and 36% positive cases of well, moderately and poorly differentiated cases respectively, p < 0.003). In addition, c-erbB-1 expression correlated with the presence of regional lymph node metastases within the moderately differentiated group. The c-erbB-1 gene was amplified in 11/40 (28%) cases, all of which overexpressed c-erbB-1 protein, while c-erbB-2 gene amplification was detected in only one case. There was no c-erbB-3 gene amplification in any of the 40 SqCLCs cases. These findings suggest that c-erbB-1, c-erbB-2 and c-erbB-3 receptors do not have a common role and are of different physiological importance, at least at the stage of clinically overt tumor in human SqCLCs.

Frequent expression of genes for receptor tyrosine kinases and their ligands in human pancreatic cancer cells

Limited information is available concerning the involvement of growth factor receptors and their ligands in the pathogenesis of human pancreatic cancer. We analyzed 12 human pancreatic cancer cell lines by Northern blot analysis for the expression of 9 receptor tyrosine kinase (RTKs) and 6 growth factors. The effect of a monoclonal antibody (MAb) against transforming growth factor-alpha (TGF-alpha) on in vitro pancreatic cancer cell growth was also assessed, mRNA for EGF-R, c-erbB-2 and c-erbB-3 was expressed in 12 (100%), 12 (100%), and 7 (58%), respectively, of the cell lines examined. In addition, 8 (67%) cell lines expressed the c-met/receptor for hepatocyte growth factor. As for ligands, TGF-alpha mRNA was detected in 10 (83%) cell lines; MAb against TGF-alpha inhibited growth of the 2 cell lines examined. Furthermore, mRNA for amphiregulin (AR) was expressed in 10 (83%) cell lines. Coexpression of TGF-alpha, AR, and EGF-R was observed in 9 (75%) cell lines. These results support the concept that several specified types of RTKs and their ligands are closely involved in regulation of the growth of human pancreatic cancer cells.

c-erbB-3 protein expression in human breast cancer: comparison with other tumour variables and survival

c-erbB-3 protein expression was investigated immunohistochemically in a series of 97 malignant breast tumours using the monoclonal antibody RTJ1. Twenty-eight cases (28.8%) showed c-erbB-3 overexpression, 31 cases (32%) showed normal levels of c-erbB-3 and 38 cases (39.2%) were c-erbB-3 negative. c-erbB-3 overexpression was positively but not significantly related to negative lymph node status and survival over a 10-year follow-up period.

The type I growth factor receptors in human breast cancer

The type 1 family of growth factor receptors includes the EGFR, c-erbB2, c-erbB3, and c-erbB4. All four members of the family are expressed in breast cancer. The EGFR gene and more frequently the c-erbB2 gene are amplified in a proportion of cases. In addition to increased expression as a result of gene amplification, overexpression of perhaps all of the receptors also appears to occur, probably as a result of increased mRNA transcription. Overexpression may have prognostic value and may predict response to current therapies. Finally these GFR proteins represent targets for new types of chemotherapeutic agents.