Expression of bcl2 family proteins and active caspase 3 in classical Hodgkin's lymphomas

The expression of various bcl2 family proteins has been reported in Hodgkin and Reed-Sternberg cells, but the proteins bad, bid, and bim have not been analyzed in classical Hodgkin's lymphomas (HLs). This study aimed to investigate the expression of the proteins bcl2, bcl-xl, mcl1, bax, bak, bad, bid, bim, and active caspasc 3, and the TUNEL (terminal deoxynucleotidyl transferasemediated in situ labeling) index to gain further insight into the apoptosis profile of classical HLs. A high expression of the proteins bcl2, bcl-xl, mcl1, bax, bak, bad, bid, and bim in HRS cells was found in 27 of 10 1 (27%), 95 of 101 (94%), 27 of 97 (29`%), 73 of 95 (77%), 37 of 102 (36%), 85 of 94 (90%), 19 of 109 (17%), and 43 of 91 (47%) cases, respectively. The high expression of bcl-xl, bax, and bad in HRS cells in most classical HLs indicates that these proteins may play predominant roles in the regulation of apoptosis in classical HLs. Active caspase 3-positive and TUNEL-positive Reed-Sternberg cells were detected in 47 of 70 (67%; range, 0%-12%) and 60 of 71 (85%; range, 0%-19%) cases, respectively. Significant positive correlations were found between bax/bcl2 (P=.002), bad/bcl2 (P=.020), bad/bclxl (P=.003), and biro/mcl1 (P=.036). Based on these findings, it could be hypothesized that the antiapoptotic proteins bcl2, bcl-xl, and incl l may counteract the expression of the proapoptotic proteins bax, bad, and bim, thereby contributing to the survival of Reed-Sternberg cells. (c) 2007 Elsevier Inc. All rights reserved.