Pax9 mediated cell survival in oral squamous carcinoma cell enhanced by c-myb.

Paired box gene 9 (Pax9) and c-myb are transcription factors that regulate the expression of the genes involved in mediating cell proliferation, resistance to apoptosis, and migration. However, the function of Pax9 in oral squamous cell carcinoma (OSCC) is virtually unknown. This study examined the anti-apoptotic roles of Pax9 and c-myb, and clarified interaction between the two genes in KB cells. Inhibition of Pax9 caused the induction of apoptosis with enhanced cleavage of caspase-3 and PARP, accelerated Bax, and reduced Bcl-2 expression. Transducing c-myb cells with adenovirus c-myb (Ad/c-myb) were induced cell growth and inhibited apoptosis, but dominant-negative myb cells (Ad/DN-myb) were not affected. Pax9 was upregulated in the Ad/c-myb cells with simultaneous decrease in the Ad/DN-myb infection. However, c-myb remained unaffected in the Pax9 small interfering RNA (siRNA) transfected cells. Moreover, the Pax9 siRNA transfected cells and Ad/DN-myb infected cells were able to arrest the cell cycle at the G(0) phase. This suggests that Pax9 and c-myb expression in KB cells is essential for cell growth, and survival is enhanced by c-myb. Disrupting the function of c-myb and Pax9 could be a potential target for cancer treatment.