DPC4 gene status of the primary carcinoma correlates with patterns of failure in patients with pancreatic cancer.

PURPOSE: Contrary to the extensive data accumulated regarding pancreatic carcinogenesis, the clinical and molecular features characteristic of advanced stage (stage III and IV) disease are unknown. A comprehensive study of pancreatic cancers from patients who have succumbed to their disease has the potential to greatly expand our understanding of the most lethal stage of this disease and identify novel areas for intervention. MATERIALS AND METHODS: Rapid autopsies were performed on 76 patients with documented pancreatic cancer. The histologic features of end stage disease were determined and correlated to the stage at initial diagnosis, patterns of failure (locally destructive v metastatic disease) and the status of the KRAS2, TP53, and DPC4 genes. RESULTS: At autopsy, 30% of patients died with locally destructive pancreatic cancer, and 70% died with widespread metastatic disease. These divergent patterns of failure found at autopsy (locally destructive v metastatic) were unrelated to clinical stage at initial presentation, treatment history, or histopathologic features. However, Dpc4 immunolabeling status of carcinoma tissues harvested at autopsy, a sensitive marker of DPC4 genetic status, was highly correlated with the presence of widespread metastasis but not with locally destructive tumors (P = .007). CONCLUSION: Pancreatic cancers are represented by distinct genetic subtypes with significantly different patterns of failure. Determinations of DPC4 status at initial diagnosis may be of value in stratifying patients into treatment regimens related to local control versus systemic therapy.

Frequent genomic copy number gain and overexpression of GATA-6 in pancreatic carcinoma.

Multiple genetic alterations are well recognized as contributing to pancreatic carcinogenesis, although the finding of recurrent copy number changes indicates additional targets remain to be found. The objective of this study was to identify novel targets of genetic alteration that contribute to pancreatic cancer development or progression. We used Representational Oligonucleotide Microarray Analysis (ROMA) to identify copy number changes in pancreatic cancer xenografts, and validated these findings using FISH, quantitative PCR, Western blotting and immunohistochemical labeling. With this approach, we identified a 0.36-Mb amplification at 18q11.2 containing two known genes, GATA-6 and cTAGE1. Using a cutoff value of 3.0 fold compared to haploid controls, copy number gain or amplification was confirmed in 4 of 42 (9.5%) pancreatic carcinomas analyzed. Combined genetic and transcriptional analyses showed consistent overexpression of GATA-6 in all carcinomas with 18q11.2 gain, as well as in the majority of pancreatic cancers examined (17 of 30 cancers, 56.7%) that did not have gain of this region. By contrast, overexpression of cTAGE1 was rare in these same cancers suggesting GATA-6 is the true target of this copy number increase. GATA-6 mRNA overexpression corresponded to robust nuclear protein expression in cancer cell lines and resected tissues consistent with its role as a transcription factor. Intense nuclear labeling was significantly increased in PanIN-3 lesions and infiltrating carcinomas compared to normal duct epithelium (p < 0.000001 and p < 0.003, respectively). Forced overexpression of GATA6 in MiaPaca2 cells resulted in increased proliferation and growth in soft-agar. Gain and overexpression of the development-related transcription factor GATA-6 may play an important and hitherto unrecognized role in pancreatic carcinogenesis.

Evaluation of GATA-4 and GATA-5 methylation profiles in human pancreatic cancers indicate promoter methylation patterns distinct from other human tumor types.

The GATA-4 and GATA-5 transcription factors are increasingly recognized as playing a role in carcinogenesis of human tumors derived of endodermal and mesodermal origin. The pancreas is derived from endodermal tissues suggesting GATA-4 and GATA-5 gene methylation may play a critical role in the biology of human pancreatic cancer as well. We investigated GATA-4 and -5 by methylation-specific PCR (MSP) in normal and neoplastic pancreatic tissues, including isogenic xenografts or cultured cell lines derived from the coexistent primary cancer and/or metastases in patients with pancreatic carcinoma. The relationship of promoter methylation was correlated with mRNA expression for each gene, and methylation patterns were correlated with known clinicopathologic features of patients. GATA-4 demonstrated a significantly lower methylation frequency than GATA-5 in low passage pancreatic cancer xenografts or cell lines (1/34 versus 21/34, p < 0.001). GATA-4 and -5 were also evaluated in microdissected samples of normal duct epithelium and cancer from pancreas cancer tissues which confirmed infrequent GATA-4 methylation in pancreatic cancers as well as in normal duct epithelium. GATA-4 was frequently overexpressed at the mRNA level with 27 of 30 (90%) pancreatic cancers showing >5.0-fold overexpression compared to normal duct epithelial cells. By contrast, high frequency methylation of GATA-5 was confirmed in pancreatic cancers tissues, but was rarely methylated in normal duct epithelium, indicating hypermethylation of this gene during pancreatic cancer development. GATA-5 mRNA expression did not correlate with its promoter hypermethylation, and treatment with the demethylating agent 5-aza-2'-deoxycytidine only partially restored mRNA expression suggesting additional regulatory mechanisms of GATA-5 expression. The presence of GATA-5 methylation showed a trend towards worse long-term survival (14.0 +/- 9.2 months versus 19.5 +/- 3.9 months, p = 0.06). While hypermethylation of GATA-5 seems to be a universal feature among human tumors, infrequent methylation of GATA-4, and its corresponding overexpression, appears unique to pancreatic cancer from other tumor types reported thus far.

Patterns of EphA2 protein expression in primary and metastatic pancreatic carcinoma and correlation with genetic status.

EphA2 is a transmembrane receptor tyrosine kinase that functions in the regulation of cell growth, survival, angiogenesis, and migration and EphA2 targeting has been proposed as a novel therapeutic strategy for neoplasms that overexpress this protein. EphA2 overexpression has been correlated with increased invasive and metastatic ability in pancreatic cancer cell lines. However, the patterns of EphA2 expression in human pancreatic cancers and associated metastases is unknown, as are the genetics of EphA2 in this tumor type. We collected clinicopathologic data and paraffin-embedded materials from 98 patients with primary and/or metastatic pancreatic cancer and performed immunohistochemical labeling for EphA2 protein. EphA2 protein immunolabeling was found in 207 of 219 samples (95%). The expression was predominantly cytoplasmic, although predominant membranous staining was observed in a minority of cases. When evaluated specifically for labeling intensity, primary and metastatic carcinomas were more strongly positive compared to benign ducts and PanIN lesions (P < 0.00001 and P < 0.01, respectively) and poorly differentiated carcinomas were more strongly positive for EphA2 than well and moderately differentiated tumors (P < 0.005). When primary carcinomas without metastatic disease were specifically compared to carcinomas with associated metastatic disease, the advanced carcinomas showed relatively less strong positive labeling for EphA2 (P < 0.008). Moreover, decreased EphA2 labeling was more commonly found in liver (P < 0.002), lung (P < 0.004) or peritoneal metastases (P < 0.01) as compared to distant lymph node metastases (P < 0.01). Genetic sequencing of the tyrosine kinase domain of EPHA2 in 22 samples of xenograft enriched pancreatic cancer did not reveal any inactivating mutations. However, EPHA2 amplification was found in 1 of 33 pancreatic cancers corresponding to a lymph node metastasis, indicating EPHA2 genomic amplification may underlie EphA2 overexpression in a minority of patients. Our data confirms that EphA2 is overexpressed in pancreatic cancer, but suggests a relative loss of EphA2 in co-existent pancreatic cancer metastases as well as a role for EPHA2 in organ specific metastasis.

Identification of chromosomal imbalances in pancreatic carcinoma using comparative genomic hybridization.

OBJECTIVE: To identify genetic abnormalities in primary pancreatic carcinoma in humans. METHODS: Comparative genomic hybridization (CGH) was used to investigate genomic imbalances in 27 cases of pancreatic carcinomas. Multiple deletions and gains were observed in all tumor specimens. RESULTS: Losses affecting chromosomes 9p, 17p, 4q and 6p and gains involving 8q, 7q, 3q and 1q were commonly observed. CONCLUSIONS: There are multiple regions of chromosomes with changes copy number in pancreatic carcinoma. The altered chromosomal regions may contain several candidate genes which are involved in the development and progress of pancreatic carcinogenesis.