Oncogenes in cancer of the pancreas

Aberrant transcription factors in the cancers of the pancreas

Transcription factors (TFs) are essential for proper activation of gene set during the process of organogenesis, differentiation, lineage specificity. Reactivation or dysregulation of TFs regulatory networks could lead to deformation of organs, diseases including various malignancies. Currently, understanding the mechanism of oncogenesis became necessity for the development of targeted therapeutic strategy for different cancer types. It is evident that many TFs go awry in cancers of the pancreas such as pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine neoplasms (PanNENs). These mutated or dysregulated TFs abnormally controls various signaling pathways in PDAC and PanNENs including RTK, PI3K-PTEN-AKT-mTOR, JNK, TGF-β/SMAD, WNT/β-catenin, SHH, NOTCH and VEGF which in turn regulate different hallmarks of cancer. Aberrant regulation of such pathways have been linked to the initiation, progression, metastasis, and resistance in pancreatic cancer. As of today, a number of TFs has been identified as crucial regulators of pancreatic cancer and a handful of them shown to have potential as therapeutic targets in pre-clinical and clinical settings. In this review, we have summarized the current knowledge on the role and therapeutic usefulness of TFs in PDAC and PanNENs.

Expression of c-fos was associated with clinicopathologic characteristics and prognosis in pancreatic cancer

It has long been regarded that pancreatic cancer (PC) is a life-threatening malignant tumor. Thus, much attention has been paid for factors, especially relative molecules, predictive for prognosis of PC. However, c-fos expression in PC was less investigated. In addition, its association with clinicopathologic variables and prognosis remains unknown. In the present study, expression of c-fos was detected by tissue microarray-based immunohistochemical staining in cancer and adjacent tissues from 333 patients with PC. The staining results were correlated with clinicopathologic parameters and overall survival. Furthermore, prognostic significance of c-fos in subsets of PC was also evaluated. It was shown that low expression of c-fos was more often in cancer than in adjacent tissues of PC (P<0.001). Besides, high cancerous c-fos expression was significantly associated with tumor site and T stage, whereas peri-neural invasion was of a borderline significant relevance. Log-rank test revealed that high expression of c-fos in cancer tissues was a significant marker of poor overall survival, accompanied by some conventional clinicopathologic variables, such as sex, grade, peri-neural invasion, T and N stages. More importantly, cancerous c-fos expression was identified as an independent prognosticator in multivariate analysis. Finally, the prognostic implication of c-fos expression was proven in four subsets of patients with PC. These data suggested that c-fos expression was of relationships with progression and dismal prognosis of PC.

Pancreatic ductal adenocarcinoma and transcription factors: role of c-Myc

INTRODUCTION

Deregulated expression/activation of transcription factors is a key event in the establishment and progression of human cancer. Furthermore, most oncogenic signaling pathways converge on sets of transcription factors that ultimately control gene expression patterns resulting in cancer development, progression, and metastasis.

METHODS

Ductal pancreatic adenocarcinoma (PDA) is the main type of pancreatic cancer and the fourth leading cause of cancer mortality in the Western world. The early stage of the disease is characterized by pancreatic intraepithelial neoplasia lesions bearing mutations in the K-RAS proto-oncogene, which progress to malignant PDA by accumulating additional mutations in the tumor suppressor gene CDKN2A (p16) and in SMAD4 and TP53 transcription factors. The involvement of other signaling pathways in PDA development and progression is an active area of research which may help to clarify the critical steps of this devastating disease.

RESULTS

In this regard, several in vitro and in vivo data have demonstrated the contribution of the transcription factor c-Myc to pancreatic carcinogenesis although the molecular mechanisms are poorly understood. c-Myc is a proto-oncogene which has a pivotal function in growth control, differentiation and apoptosis and is known to act as a downstream transcriptional effector of many signaling pathways involved in these processes. It is regulated at multiple levels and its abnormal expression contributes to the genesis of many human tumors.

CONCLUSIONS

This review focuses on the role of c-Myc in pancreatic embryonic development and homeostasis as well as its involvement on pancreatic tumorigenesis. Evidences showing that c-Myc function is highly dose and cell context dependent, together with its recently demonstrated ability to reprogram somatic cells towards a pluripotent stem cell-like state, indicate that the role of c-Myc in pancreas pathophysiology might have been previously underscored.

The immunocytokine scFv23/TNF targeting HER-2/neu induces synergistic cytotoxic effects with 5-fluorouracil in TNF-resistant pancreatic cancer cell lines

Human pancreatic tumor cells are highly resistant to both tumor necrosis factor (TNF) and to chemotherapeutic agents. HER-2/neu expression has been proposed as a negative prognostic marker in pancreatic intraepithelial neoplasia. Our approach was to utilize HER-2/neu expression on the surface of tumor cells as a therapeutic target employing scFv23/TNF, immunocytokine composed of a single chain Fv antibody (scFv23) targeting the HER-2/neu and the cytokine TNF as the cytotoxic moiety, to deliver TNF directly to TNF-resistant pancreatic tumor cells. Using a panel of human pancreatic cell lines, which overexpress HER-2/neu, we evaluated the in vitro response of cells to TNF, scFv23/TNF, Herceptin, and a combination of scFv23/TNF with various chemotherapeutic agents. We found that all pancreatic cancer cell lines were highly resistant to the cytotoxic effects of TNF and that scFv23/TNF was highly cytotoxic to TNF-resistant HER-2/neu-expressing pancreatic cancer cell lines at levels rivaling that of conventional chemotherapeutic agents. Combination studies demonstrated a synergistic cytotoxic effect of scFv23/TNF with 5-fluorouracil (5-FU) in TNF-resistant pancreatic cancer cell lines. Mechanistic studies demonstrated that the 5-FU plus scFv23/TNF combination specifically resulted in a down-regulation of HER-2/neu, p-Akt and Bcl-2 and up-regulation of TNF-R1. In addition, the combination 5-FU plus scFv23/TNF induced apoptosis and this synergistic effect was dependent on activation of caspase-8 and caspase-3. Delivery of the cytokine TNF to HER-2/neu expressing pancreatic tumor cells, which are inherently resistant to TNF using scFv23/TNF may be an effective therapy for pancreatic cancer especially when utilized in combination with 5-FU.

c-Myc-induced chemosensitization is mediated by suppression of cyclin D1 expression and nuclear factor-kappa B activity in pancreatic cancer cells

PURPOSE

Pancreatic cancer is a highly aggressive disease that remains refractory to various chemotherapeutic agents. Because the proto-oncogene c-myc can modulate apoptosis in response to cytotoxic insults and is commonly overexpressed in pancreatic cancer, we investigated the value of c-myc as a potential modulator of cellular response to various chemotherapeutic agents.

EXPERIMENTAL DESIGN

Stable overexpression or small interfering RNA (siRNA)-mediated knockdown of c-myc and restoration of cyclin D1 were done in the Ela-myc pancreatic tumor cell line. Cell viability after cisplatin treatment of c-myc-overexpressing, control, and siRNA-transfected cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and drug-induced apoptosis was measured by DNA fragmentation, sub-G(1), and poly(ADP-ribose) polymerase cleavage analyses. Protein expression profile after cisplatin treatment was determined by Western blotting and DNA binding activity of nuclear factor-kappaB was examined by electrophoretic mobility shift assay.

RESULTS

Ectopic overexpression of c-myc in murine and human pancreatic cancer cell lines, Ela-myc and L3.6pl, respectively, resulted in increased sensitivity to cisplatin and other chemotherapeutic drugs. Increased sensitivity to cisplatin in c-myc-overexpressing cells was due, in part, to the marked increase in cisplatin-induced apoptosis. Conversely, down-regulation of c-myc expression in stable c-myc-overexpressing cells by c-myc siRNA resulted in decreased sensitivity to cisplatin-induced cell death. These results indicate an important role of c-myc in chemosensitivity of pancreatic cancer cells. The c-myc-induced cisplatin sensitivity correlated with inhibition of nuclear factor kappaB activity, which was partially restored by ectopic cyclin D1 overexpression.

CONCLUSIONS

Our results suggest that the c-myc-dependent sensitization to chemotherapy-induced apoptosis involves suppression of cyclin D1 expression and nuclear factor kappaB activity.

Expression of Ki-67, p53, and K-ras in chronic pancreatitis and pancreatic ductal adenocarcinoma

AIM: To examine surgical specimens of pancreas with either chronic pancreatitis or pancreatic cancer in order to study whether ductal hyperplasia and dysplasia in pancreas represent precursor lesions for pancreatic cancer.

METHODS: We examined expression of Ki-67, CEA, p53, and K-ras, in the surgical specimens of pancreas with adenocarcinomas (n = 11) and chronic pancreatitis (n = 12). Cellular proliferation was assessed by Ki-67 proliferation index using the proliferation marker Ki-67. In specimens with pancreas cancer, we divided pancreas epithelium into normal (n = 7), ductal hyperplasia (n = 3), dysplasia (n = 4), and cancerous lesion (n = 11) after hematoxylin and eosin staining, Ki-67, and CEA immunohistochemical staining. In cases with chronic pancreatitis, the specimen was pathologically examined as in cases with pancreas cancer, and they were also determined as normal (n = 10), ductal hyperplasia (n = 4), or dysplasia (n = 5). p53 and K-ras expression were also studied by immunohistochemical staining.

RESULTS: In pancreatic cancer, the Ki-67 index was 3.73±3.58 in normal site, 6.62±4.39 in ductal hyperplasia, 13.47±4.02 in dysplasia and 37.03±10.05 in cancer tissue, respectively. Overall, p53 was positive in normal ducts, ductal hyperplasia, dysplasia, and carcinoma cells in 0 of 14 (0%), 0 of 7 (0%), 7 of 9 (78%), and 10 of 11 (91%), respectively, and K-ras was positive in 0 of 8 (0%), 1 of 3 (33%), 4 of 6 (67%), 4 of 5 (80%), respectively.

CONCLUSION: Our results favorably support the hypothesis that ductal hyperplasia and dysplasia of the pancreas might be precursor lesions for pancreas cancer. Further evaluation of oncogenes by the molecular study is needed.

Assessment of HER-2 status in pancreatic adenocarcinoma: correlation of immunohistochemistry, quantitative real-time RT-PCR, and FISH with aneuploidy and survival

HER-2 is a transmembrane growth factor receptor recognized in overexpression as an independent adverse prognostic factor in several cancers. This study measured HER-2 overexpression in pancreatic adenocarcinoma at the genetic, transcriptional, and translational level. Expression was gauged with regard to stage, grade, and survival. Pancreatic adenocarcinoma samples (n = 30) were analyzed with immunohistochemical labeling for HER-2 protein, Quantitative real-time reverse transcriptase polymerase chain reaction (Q-RT-PCR) measurement of HER-2 mRNA and fluorescence in situ hybridization (FISH) analysis of HER-2 gene expression. HER-2 expression in benign pancreatic lesions (n = 10) provided a control. Five (17%) of the pancreatic adenocarcinomas scored maximal 3+ immunohistochemistry (IHC) labeling, seven (23%) had significantly increased expression of HER-2 mRNA, while only one (3%) exhibited low level HER-2 gene amplification. Ten (33%) tumors demonstrated aneuploidy. In general, concordance between methodologies was poor, but the best agreement was seen between FISH aneuploidy status and Q-RT-PCR mRNA overexpression (80% agreement), followed by IHC and Q-RT-PCR (73% agreement). The least agreement was seen between IHC and FISH aneuploidy status (67% agreement). Tumor stage was positively associated with HER-2 mRNA and protein expression, but tumor grade and other patient characteristics did not reach statistical significance. A poor survival outcome was demonstrated with positive HER-2 status in all three measures of overexpression (Kaplan-Meier log-rank score; P < 0.01 [IHC], P = 0.05 [Q-RT-PCR], P = 0.02 [FISH]). Discordance in expression at the nuclear, cytoplasmic, and cell surface levels highlights the limitations of immunohistochemical evaluation alone and stresses the need for further evaluation of response to anti-HER-2 targeted therapies in tumors displaying overexpression in gene copy, mRNA, and receptor protein.

Human aspartyl (asparaginyl) beta-hydroxylase monoclonal antibodies: potential biomarkers for pancreatic carcinoma

INTRODUCTION

Pancreatic adenocarcinoma is among the top 10 leading causes of death due to cancer in the United States. The lack of reliable and sensitive biomarkers for this disease makes it difficult to render an early diagnosis.

AIMS

To evaluate carcinoma-associated monoclonal antibodies (MoAbs), including AF-20, SF-25, and FB-50, for their binding specificity to pancreatic adenocarcinoma relative to normal pancreatic tissue. In addition, binding of the Th9 MoAb to human Reg 1 protein was studied because of its potential role in cell growth.

METHODOLOGY

Adjacent histologic sections were immunostained with each of the MoAbs and graded on a scale of 0 to 4+, corresponding to the relative distribution and intensity of immunoreactivity within the tumor and normal adjacent tissue.

RESULTS

Intense levels (grade 3 or 4) of FB50 immunoreactivity were detected in 19 of 19 tumors but not in normal adjacent pancreatic tissue. In addition, increased levels of FB50 immunoreactivity were detected in at least 75% of the tumor cells in 18 of the 19 cases. SF-25 immunoreactivity similarly distinguished pancreatic adenocarcinoma from normal pancreas in 14 of 19 cases. In contrast, AF20 immunoreactivity was detected in 6 of 19 pancreatic adenocarcinomas, and for the most part, the labeling was focal and of a low level. TH9 immunoreactivity was detected in 5 of 19 tumors but also in normal as well as inflamed adjacent pancreatic tissue.

CONCLUSION

These results suggest that the FB50 and SF25 MoAbs represent excellent potential biomarkers of pancreatic adenocarcinoma and could be configured in an immunoassay for detecting pancreatic adenocarcinoma cells in biologic fluids.

c-MYC activation in primary and metastatic ductal adenocarcinoma of the pancreas: incidence, mechanisms, and clinical significance

Amplification and overexpression of c-MYC is a common event in various neoplasias. Recently, comparative genomic hybridization (CGH) of primary pancreatic adenocarcinomas revealed a distinct high-level amplification of 8q23-qter, suggesting that c-MYC located on 8q24 may be a candidate oncogene. To evaluate the biological significance and prognostic value of c-MYC activation in pancreatic carcinoma, we performed interphase fluorescence in situ hybridization (FISH) and immunohistochemistry on a series of 69 primary pancreatic adenocarcinomas, 19 corresponding lymph node metastases, and 5 pancreatic intraductal lesions. Dual color FISH using a probe for c-MYC (8q24) and a centromeric probe for chromosome 8 revealed amplification of c-MYC in 32.3% and 29.4% of primary and metastatic tumors, respectively. Immunostaining identified c-MYC protein overexpression in 43.5% of primaries and 31.6% of metastases. Low concordance between positive FISH and immunostaining (13.4%) suggests multiple independent regulatory pathways of c-MYC activation. Statistical evaluation revealed significant correlation (alpha = 0.033) between c-MYC protein overexpression and histopathological tumor grade but absence of correlation with tumor stage or lymph node status. Analysis of pancreatic intraductal lesions showed c-MYC amplification and protein overexpression in two of five cases in which invasive carcinoma exhibited identical aberrations. We conclude that deregulation of c-MYC protein is common in pancreatic cancer and that it may be involved in early neoplastic development and progression rather than in locoregional spread of invasive cancer.

Molecular biology of pancreatic cancer: potential clinical implications

The development of cancer involves the accumulation of genetic changes. Over the past decade there has a been spectacular advance in the knowledge of the genetic basis of cancer, mainly as a result of the rapid progression of molecular technology. Pancreatic cancer is one of the most lethal cancers. Conventional therapeutic approaches have not had much impact on the course of this aggressive neoplasm. Knowledge of the molecular biology of pancreatic cancer has grown rapidly. Genetic alterations in pancreatic cancer include oncogene mutations (most commonly K-ras mutations), and tumour suppressor gene alterations (mainly p53, p16, DCC, etc.). These advances have potential implications for the management of this deadly disease. Identification of a hereditary genetic predisposition to pancreatic cancer has led to the formation of pancreatic cancer registries around the world, with voluntary screening of patients and siblings for the hereditary genetic defect. Asymptomatic population screening remains unrealistic, but the recognition of subpopulations at increased risk from pancreatic cancer, along with novel and sensitive detection techniques, means that targeted population screening is a step closer. Intensive research is performed in specialist laboratories to improve the diagnostic approach in patients with pancreatic cancer. The use of such molecular diagnostic methods is likely to expand. Molecular biology may also have a great impact on the treatment of pancreatic cancer, and many therapeutic approaches are being evaluated in clinical trials, including gene replacement therapy, genetic prodrug activation therapy, antisense immunology and peptide technology. The 'molecular age' has the promise of delivering still better results. This review summarises recent data relating to the molecular biology of pancreatic cancer, with emphasis on features that may be of clinical significance for diagnosis and/or therapy.

Instability of chromosome 8 as an indicator of aggressive tumor phenotype in pancreatic cancer

BACKGROUND AND OBJECTIVES

Chromosomal instability is a common feature of pancreatic carcinoma, but its biological significance remains unclear. In this study, we investigated the association between chromosomal instability and biological aggressiveness in human pancreatic cancer cells.

METHODS

Fluorescence in situ hybridization was performed to examine changes in chromosomal numbers in a total of 13 pancreatic cancer cell lines. We also assessed the potential for tumor aggressiveness within cancer cells by in vitro migration and invasion assay and by subcutaneous implantation into nude mice.

RESULTS

Chromosomal instability, characterized by numerical variations in copy numbers of chromosome 8, was observed in most cell lines, and the magnitude of instability was correlated well with both motility (P < 0.001) and invasion rate (P < 0.001) of these cells. Furthermore, a significant positive correlation existed between chromosome instability and tumor growth in vivo (P < 0.01).

CONCLUSIONS

These results suggest that the increased level of chromosomal instability may play a critical role in the development of aggressive tumor phenotype during pancreatic cancer progression. J. Surg. Oncol. 2001;76:181-187.

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.

DNA copy number changes and evaluation of MYC, IGF1R, and FES amplification in xenografts of pancreatic adenocarcinoma

We analyzed eight samples of xenografted human pancreatic tumors and two metastases developed in mice by comparative genomic hybridization (CGH). The most recurrent changes were: gains on chromosomes 8 (8q24-qter; 7/8 cases), 15 (15q25-q26; 6/8 cases), 16 (16p in 6/8 cases; 16q in 5/8 cases), 20 (20q; 6/8 cases), and 19 (19q; 5/8 cases); and losses on chromosomes 18 (18q21; 6/8 cases), 6 (6q16-q21 and 6q24-qter; 5/8 cases each), and 9 (9p23-pter; 5/8 cases). The two metastases maintained the aberrations of the original pancreatic tumor plus gain of 11q12-q13 and 22q. Loss of heterozygosity analysis was carried out for 10p14-pter, a region that was lost in 3/8 samples. All of them presented allelic imbalance for all the informative loci. Fluorescence in situ hybridization and Southern analysis were performed to test some candidate oncogenes in 8q24 (MYC) and 15q25-qter (IGF1R and FES). Two of seven tumors showed high-level amplification of MYC relative to the centromere (> 3-fold), another two tumors had low-level amplification (1.5- to 3.0-fold), and one displayed 5.5 MYC signals/cell. In relation to the FES gene, low-level amplification was found in three tumors. Southern analysis showed five cases with a low-level amplification of IGF1R. Our data suggest that either few extra gene copies may be enough for cancer progression or other genes located in these regions are responsible for the amplifications found by CGH.

Multi-step pancreatic carcinogenesis and its clinical implications

The poor prognosis of pancreatic cancer relates mainly to its delayed diagnosis. It has been repeatedly shown that earlier diagnosis of pancreatic cancer is associated with a better outcome. Molecular diagnostic methods (mainly detection of K-ras mutations in pure pancreatic or duodenal juice, on specimens obtained by percutaneous fine-needle aspirations or in stool specimens) can achieve earlier diagnosis in selected subgroups of patients, such as patients with chronic pancreatitis (especially hereditary), adults with recent onset of non-insulin-dependent diabetes mellitus and patients with some inherited disorders that predispose to the development of pancreatic cancer. There is increasing evidence that pancreatic carcinogenesis is a multi-step phenomenon. Screening procedures for precursor lesions in these selected subgroups of patients may reduce the incidence and mortality from pancreatic cancer.

Pancreatic cancer in patients with chronic pancreatitis: a challenge from a surgical perspective

Chronic pancreatitis (CP) is generally considered as a risk factor for pancreatic adenocarcinoma (PAC). However, the cumulative risk differs among the epidemiological studies. In the individual patient, the differential diagnosis between PAC and CP cannot be always resolved preoperatively and even intraoperatively. In those cases, the uncertainty can only be answered with histological studies of the resected specimen after a radical resection, provided that this type of surgery can be performed with a reasonable risk in a surgically fit patient. The type of resection depends on the location of the suspicious mass. For masses in the tail of the pancreas, a distal pancreatectomy is the procedure of choice. For suspicious lesions in the head of the pancreas, a pancreatoduodenectomy (PD) should be performed. The surgeon and the patient should also acknowledge that a radical resection will occasionally be performed for a suspected malignancy only to find that another etiology (i.e. CP) accounts for the suspicious pancreatic mass. In the presence of a strong suspicion for an underlying malignancy in a patient with head dominant CP, PD should probably be preferred over the newer organ-preserving Beger and Frey procedures, since it is an adequate procedure for both CP and PAC.

Immunohistochemical evaluation of K-ras, p53, and HER-2/neu expression in hyperplastic, dysplastic, and carcinomatous lesions of the pancreas: evidence for multistep carcinogenesis

The pathobiology of precursor lesions leading to invasive pancreatic adenocarcinoma remains a controversial area, but knowledge of the mechanisms of tumorigenesis may lead to possibly earlier detection, prevention, and treatment in the future. We hypothesize that ductal hyperplasia and dysplasia of the pancreas represent precursor lesions and are part of a continuous developmental spectrum evolving into ductal adenocarcinoma of the pancreas. To further define this sequence, we studied the immunohistochemical markers HER-2/neu, K-ras, and p53 in 15 adenocarcinomas and 15 nonmalignant specimens of the pancreas. The 15 nonmalignant specimens of the pancreas included both normal pancreas and chronic pancreatitis. Overall, HER-2/neu was positive in normal ducts, ductal hyperplasia, dysplasia, and carcinoma cells in 0 of 30, 11 of 20 (55%), 10 of 15 (67%), and 12 of 15 (80%), respectively, with progressive increase in the intensity of staining; p53 was positive in 1 of 30 (3%), 0 of 20, 3 of 15 (20%), and 13 of 15 (80%), respectively, and K-ras was positive in 1 of 30 (3%), 6 of 20 (30%), 11 of 15 (73%), and 8 of 15% (53%), respectively. These data support the hypothesis that ductal hyperplasia and dysplasia of the pancreas represent precursor lesions, and, in a fashion similar to that in colorectal tumorigenesis, pancreatic cancer seems to accumulate progressive genetic alterations.

Chromosomal imbalances in primary and metastatic pancreatic carcinoma as detected by interphase cytogenetics: basic findings and clinical aspects

To date, cytogenetic studies on pancreatic carcinoma are rare, and little is known about the frequency of cytogenetic aberrations in primary carcinomas compared with metastatic tumour cells. We therefore evaluated the frequency of chromosomal aberrations in 12 primary pancreatic carcinomas and in effusion specimens from 25 patients with pancreatic cancer by using interphase fluorescence in situ hybridization (FISH) and a panel of four centromeric probes. Hyperdiploidy and chromosomal imbalances, predominantly affecting chromosome 8, were a constant finding in metastatic effusion cells, whereas concordant gain of chromosomes or relative loss of chromosome 18 characterized primary pancreatic carcinomas. The potential role of oncogenes located on chromosome 8 for pancreatic cancer progression was further investigated by double-hybridization studies of aneuploid effusion cells with a probe to 8q24 (MYC) and a centromeric probe to chromosome 8, which demonstrated amplification of the MYC oncogene in two of ten cases (20%). Finally, a potential application of basic findings in the clinical setting was tested by searching for micrometastatic cells in effusions from pancreatic cancer patients primarily negative by FISH. Two-colour FISH in combination with extensive screening (>10,000 nuclei) seems to be a useful tool to unequivocally identify micrometastatic cells by demonstrating hyperdiploidy and intranuclear chromosomal heterogeneity.

Comparative genomic hybridization reveals frequent gains of 20q, 8q, 11q, 12p, and 17q, and losses of 18q, 9p, and 15q in pancreatic cancer

Comparative genomic hybridization (CGH) was used to screen for genomic imbalances in 24 exocrine pancreatic carcinomas, including II low-passage cell lines (4-8 subcultures) and 13 uncultured samples. Aberrations were found in all cell lines and in seven of the 13 biopsies. The most frequent changes in the cell lines were gains of 20q (91%), 11q (64%), 17q (64%), 19q (64%), 8q, 12p, 14q, and 20p (55%), and losses of 18q (100%), 9p (91%), 15q(73%), 21q (64%), 3p (55%), and 13q (55%). High-levels gains (tumor to normal ratio over 1.5) were detected at 3q, 6p, 7q, 8q, 12p, 19q, and 20q. Among the tumor biopsies, overrepresentations of 7p and 8q were most common (31%), followed by 5p, 5q, 11p, 11q, 12p, and 18q (23%), whereas the most frequent losses involved 18p and 18q (31%) and 6q and 17p (23%). The genetic changes in nine samples obtained from metastatic lesions did not differ significantly from those in 15 primary carcinomas. Most of the gains and losses detected in this CGH study correspond well to those identified in previous cytogenetic and molecular genetic investigations of pancreatic carcinomas. However, frequent gain of 12p and loss of 15q have not been previously reported. Molecular genetic analyses of these chromosome arms are warranted, and may lead to the discovery of novel genes important in pancreatic carcinogenesis.