Abstract
Oral squamous cell carcinoma (OSCC) is the most common malignant epithelial cancer occurring in the oral cavity, where it accounts for nearly 90% of all oral cavity neoplasms. The c-MYC transcription factor plays an important role in the control of programmed cell death, normal-to-malignant cellular transformation, and progression of the cell cycle. However, the role of c-MYC in controlling the proliferation of OSCC cells is not well known. In this study, c-MYC gene was silenced in OSCC cells (ORL-136T), and molecular and cellular responses were screened. To identify the pathway through which cell death occurred, cytotoxicity, colony formation, western blotting, caspase-3, and RT-qPCR analyzes were performed. Results indicated that knockdown of c-MYC has resulted in a significant decrease in the cell viability and c-MYC protein synthesis. Furthermore, caspase-3 was shown to be upregulated leading to apoptosis via the intrinsic pathway. In response to c-MYC knockdown, eight cell proliferation-associated genes showed variable expression profiles: c-MYC (-21.2), p21 (-2.5), CCNA1(1.8), BCL2 (-1.4), p53(-3.7), BAX(1.1), and CYCS (19.3). p27 expression was dramatically decreased in c-MYC-silenced cells in comparison with control, and this might indicate that the relative absence of c-MYC triggered intrinsic apoptosis in OSCC cells via p27 and CYCS.