Expression of Bcl-2 family modulated through p53-dependent pathway in human hepatocellular carcinoma

The biological behavior of hepatocellular carcinoma (HCC) is, in part, relevant to apoptosis. A systematic investigation of the apoptosis-related Bcl-2 family modulated by p53 in HCC is lacking. A total of 22 HCC patients were studied. The expression of p53 protein in HCC was assessed using the immunohistochemical method, which categorized the HCC patients into two groups: group 1, with immunonegative p53 (N = 7); and group 2, with immunopositive p53 (N = 15). The expression of p53, p21, Bcl-2, Bax, Bcl-x_L, and Bcl-x_S in the 22 HCC cases detected by western bioting was quantified with a densitometer. The apoptosis of the 22 HCC cases was determined by terminal deoxynucleotidyltransferase-mediated UTP end-labeling (TUNEL). We found that Bcl-2 was remarkably up-regulated in group 2 (14 of 15), but was down-regulated in group 1 (5 of 7). Bax was up-regulated in both group 1 (6 of 7) and group 2 (13 of 15). Bcl-x_L was up-regulated in both group 1 (5 of 7) and group 2 (9 of 15). Bcl-x_S was remarkably down-regulated in group 2 (14 of 15) compared to group 1 (4 of 7). The apoptosis indexes of groups 1 and 2 were 0.82 ± 0.26% and 0.33 ± 0.17%, respectively (P = 0.023). The long-term survival of group 1 was superior to that of group 2 (log-rank test, P = 0.001). In conclusion, Bcl-2 and Bcl-x_S represented the most significant anti- and proapoptotic proteins, respectively, modulated through a p53-dependent pathway in HCC.