A pivotal role for Pim-1 kinase in esophageal squamous cell carcinoma involving cell apoptosis induced by reducing Akt phosphorylation.

It is well documented that Provirus integration site for Moloney murine leukemia virus 1 (Pim-1), as a proto-oncogene encoding a serine/threonine kinase with multiple cellular functions, is tightly associated with the occurrence and development of tumors. Overexpression of Pim-1 plays a critical role in the progression of several different tumors. In this study, esophageal squamous cell carcinoma (ESCC) EC9706 cells with Pim-1 siRNA treatment resulted in a clear decrease of Pim-1 levels, followed by inhibiting cell proliferation and inducing apoptosis. Further, Pim-1 siRNA reduced phosphorylation of Akt and Bad, and increased cleaved caspase-3/-9 activities and expression levels. These data suggest that Pim-1 siRNA-mediated apoptosis is closely related to the decrease in Akt and Bad phosphorylation and increase in cleaved caspase-3/-9 activities, and thus manipulation of Pim-1 is a potential target for molecular therapy in the clinical treatment of patients with ESCC.