Increased expression of the bcl6 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas

There is increasing evidence that bc16 and CD10 expression may be related to apoptosis and cell cycle progression. Therefore, 79 cases of de novo diffuse large B-cell lymphomas were studied for the expression of bc16 and CD10 proteins in relation to 1) the apoptotic index, 2) the proliferation-associated proteins Ki67, cyclin A, and cyclin B1; and 3) the expression of the bc12, p53, Rb, p16, and p27 proteins. Expression of bc16, CD10, and bc12 proteins was found in 54/79 (68%), 28/79 (35%), and 47/74 (63%) cases, respectively. The bc16/CD10 patterns were as follows: bc16+/CD10+ (26 cases, 32%), bc16+/CD10- (28 cases, 33%), bc16-/CD10- (23 cases, 31%), and bc16-/CD10+ (2 cases, 4%). Significant positive correlations were found between bc16/Ki67 (r = .328, P = .003), bc16/cyclin A (r = .265, P = .018), bc16/apoptotic index (r = .327, P = .010), CD10/Ki67 (r = .296, P = .008), and CD10/ apoptotic index (r = .397, P = .001). In addition, high expression of bc16 showed significant correlation with negative (null/low) bc12 expression (chi(2) test, P = .002). The above findings indicate that increased expression of the bc16 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas. The association between increased bc16 expression and enhanced apoptosis might be due, at least in part, to the null/low bc12 expression because previous in vitro data showed that bc16 overexpression induces apoptosis accompanied by bc12 and bcl-xl downregulation. Moreover, significant correlation was found between increased apoptotic index and the bc16+/CD10+ pattern (t test: P = .014, Mann-Whitney test: P = .046). This finding and the positive correlation of the apoptotic index with bc16 and CD 10 expression may be related to previous results showing that the expression of these proteins has favorable effects on the clinical outcome of diffuse large B-cell lymphomas.