Adenovirus-mediated high expression of BCL-6 in CV-1 cells induces apoptotic cell death accompanied by down-regulation of BCL-2 and BCL-X-L

The BCL-6 proto-oncogene encodes a 92- to 98-kDa transcriptional repressor containing the BTB/POZ domain at its N-terminal region and the zinc finger domain at its C-terminal region, respectively. In the present study, we exa mined the function of BCL-6 by using a recombinant adenovirus expressing BC L-6 (Ax1CA-BCL-6) and the lacZ reporter gene (Ax1CA-lacZ), Viability of CV- 1 and HeLa cells infected, with Ax1CA-BCL-6 was markedly reduced due to apo ptosis, suggesting that BCL-6-overexpression induces apoptosis in CV-1 and HeLa cells. FAGS analysis revealed that BCL-6-overexpressing cells are accu mulated not only at the sub-G1 but also at G2/M phase. Induction of apoptos is by BCL-6 was preceded by down-regulation of apoptosis repressors BCL-2 a nd BCL-X-L. These results suggest that BCL-6 induces apoptosis by regulatin g the expression of these apoptosis-regulating genes.