Relation between the Expression of K-ras in Hep-2 Cells and Development of Laryngeal Carcinoma~*

Objective： To investigate the expression of K-ras in human laryngeal squamous cell carcinoma cell lines （Hep-2） and its significance for establishing a solid foundation for further study of the relationship between human laryngeal squamous cell carcinoma and K-ras gene point mutations. Methods： The expression of K-ras in human laryngeal squamous cell carcinoma cell lines （Hep-2） and human pancreatic carcinoma cell lines （MIAPaCa-2） was detected by using RT-PCR. Results： The expression of K-ras mRNA in Hep-2 and MIAPaCa-2 was strong and positive. Conclusion： The expression of K-ras mRNA in human laryngeal squamous cell carcinoma cell lines （Hep-2） is positive. Development of laryngeal carcinoma might be related to the activation of K-ras gene point mutation.

Tumor necrosis factor a accelerates Hep-2 cells proliferation by suppressing TRPP2 expression

TRPP2, a Ca2＋-permeable non-selective cation channel, has been shown to negatively regulate cell cycle, but the mechanism underlying this regulation is unknown. Tumor necrosis factor a （TNF-a） is a proinflammatory cytokine extensively involved in immune system regulation, cell proliferation and cell survival. However, the effects and mechanisms for the role of TNF-a in laryngeal cancer remain unclear. Here, we demonstrated using western blot analyses and intracellular Ca〉 concentration measurements that TNF-a treatment suppressed both TRPP2 expression and ATP-induced Ca2＋ release in a laryngeal cancer cell line （Hep-2）. Knockdown of TRPP2 by a specific siRNA significantly decreased ATP-induced Ca2＋ release and abolished the effect of TNF-a on the ATP-induced Ca2＋ release. TNF-a treatment also enhanced Hep-2 cell proliferation and growth, as determined using cell counting and flow cytometry cell cycle assays. Moreover, TNF-a treatment down-regulated phosphorylated protein kinase R-like endoplasmic reticulum kinase （p-PERK） and phosphorylated eukaryotic translation initiation factor （p-elF2c0 expression levels, without affecting PERK and elF2ct expression levels in Hep-2 cells. We concluded that suppressing TRPP2 expression and TRPP2-mediated Ca2＋ signaling may be one mechanism underlying TNF〈t-enhanced Hep-2 cell proliferation. These results offer new insights into the mechanisms of TNF-a-mediated laryngeal cancer cell proliferation, and provide evidences showing a potential role of TNF-a in the development of laryngeal cancer.