Deregulation of 2 Potassium Channels in Pancreas Adenocarcinomas Implication of KV1.3 Gene Promoter Methylation

Objectives: The aim of this study was to examine expression of 2 potassium (K+) channels in pancreatic adenocarcinoma. Methods: The immunohistochemical and mRNA expression of GIRK1 (G-protein inwardly rectifying K+ channel 1) and K(V)1.3 channel (voltage-dependent K+ channel) was studied in 55 and 18 adenocarcinomas and 33 and 8 normal pancreas specimens, respectively. The methylation status of K(V)1.3 promoter was studied by methyl-specific polymerase chain reaction in 33 pancreatic adenocarcinomas. The results were correlated with the patients' prognosis. Results: GIRK1 was highly expressed in 80% (44/55) of adenocarcinoma samples versus 57.6% (19/33) of normal samples (P = 0.03), as confirmed by reverse transcriptase-polymerase chain reaction results (P = 0.007). K(V)1.3 expression was decreased in pancreatic adenocarcinomas compared with normal tissue (7.3% vs 39.4%; P = 0.0005). K(V)1.3 down-expression was associated with metastatic tumors (P = 0.018). K(V)1.3 promoter methylation was observed in 69.7% (22/33) of adenocarcinomas. Conclusion: This is the first report of deregulation of 2 K+ channels in pancreatic adenocarcinoma. GIRK1 was highly expressed in pancreatic adenocarcinomas, corresponding to its role in cell proliferation. Methylation of K(V)1.3 gene promoter could explain the decrease of K(V)1.3 expression in adenocarcinomas. New therapeutic agents, such as DNA methylation inhibitors, could be useful against this dramatic cancer.