Down-regulation of mediator complex subunit 19 (Med19) induces apoptosis in human laryngocarcinoma HEp2 cells in an Apaf-1-dependent pathway.

Mediator 19 (Med19) is a component of the mediator complex which is a co-activator for DNA-binding factors that activate transcription via RNA polymerase II. Accumulating evidence has shown that Med19 plays important roles in cancer cell proliferation and tumorigenesis. The physiological mechanism by which Med19 exerts its promoting effects in laryngocarcinoma is not yet fully understood. Here, we found that the expression of Med19 was increased in laryngocarcinoma samples from patients compared to normal bone tissues. Med19 knockdown significantly induced growth inhibition and suppressed migration in the HEp2 cell lines. Med19 knockdown also induced apoptosis in HEp2 cells via activation of caspase-3, 9 and Apaf-1. In addition, The tumorigenicity of Med19 short hairpin RNA (shRNA)-expressing cells were decreased after inoculating into nude mice. Taken together, our data suggest that Med19 acts as an oncogene in laryngocarcinoma via a possible caspase modulation pathway.