MBR REARRANGEMENT AND P-GLYCOPROTEIN EXPRESSION ARE NOT INDEPENDENT PROGNOSTIC FACTORS LIKE P53 PROTEIN IN MALIGNANT-LYMPHOMA

Non-Hodgkin's lymphomas (NHL) are B-cell malignancies which generally present molecular abnormalities, such as bcl-2 translocation t(14; 18) predominantly in the follicular subgroup. Other molecular events have been described in NHL, including p53 gene mutation and overexpression of one chemoresistance mechanism, the multidrug resistance system, P- glycoprotein (MDR1/P-gp). In this study, we analysed samples from 44 N HL patients with the presence of the bcl-2 major breakpoint region (MB R) rearrangement in 23 and without in 15. Immunochemical analysis reve aled that 39 samples were positive for bcl-2 protein expression in tum oral cells (88.6%). Seventeen (38.6%) patients expressed P-gp and 9 (2 0.5%) expressed p53 proteins. Eleven patients expressed both bcl-2 and P-gp proteins, four expressed bcl-2 and p53 proteins whereas four exp ressed bcl-2, p53 and P-gp proteins. Our results confirm the importanc e of p53 expression as a key prognostic factor, and no objective respo nse (OR) was found in patients with p53 positivity. MBR rearrangement was not associated with poor response to chemotherapy (62.1% OR in MBR positive patients v. 60% OR in MBR negative patients). The clinical i mpact of P-gp cannot be identified because no relationship was observe d between P-gp expression and prognosis (58.8% OR in P-gp positive pat ients v. 63% OR in P-gp negative patients).