Growth inhibitory effect of the ternary complex factor Net on human pancreatic carcinoma cell lines

Pancreatic carcinoma is one of the most aggressive malignancies and carries the most dismal prognoses of all cancers. A better understanding of the genes involving in tumor development may allow us to tackle this rapidly progressive disease. The Net gene belongs to the ternary complex transcription factor (TCF) family and is regulated by the Ras/mitogen-activated protein kinase-signaling pathway. Under basal conditions, Net shows strong repressing function on transcription of proto-oncogene gene c-fos. Moreover, the lower expression of Net has been noted in some carcinoma cells, such as cervical cancer. To study the effect of Net on c-fos expression and its potential role in the growth of pancreatic carcinoma, we developed a recombinant plasmid, a pEGFP-N1-Net, which codes for Net-EGFP fusion proteins, and stably transfected it into BxPC-3 human pancreatic carcinoma cells. Using stable transformants, we were able to show that overexpression of Net decreased the expression of c-fos and inhibited pancreatic cancer cell proliferation. Cell cycle analysis demonstrated that Net overexpression inhibited cell cycle progression. These findings suggested that loss of Net repression could augment c-fos expression and further trigger neoplastic cell proliferation, which was involved in the pathogenesis of pancreatic cancer. Therefore, Net might be a potential target for the treatment of c-fos-positive pancreatic cancer.