Bcl-2 is one of the cytoplasmic oncoproteins, and has been shown to suppress apoptotic cell death. In this study, we investigated the relationship between Bcl-2 expression and effects of chemotherapeutic agents on human breast cancer cells. We examined 26 surgically resected breast tumors with preoperative trans-arterial administration of chemotherapeutic agents and 30 control cases using immunohistochemical methods. In all 26 cases in the chemotherapy group, the breast cancer cells were focally degenerated to various degrees, associated with inflammation and stromal desmoplastic changes. Bcl-2 expression was found in 46% (12/26) of the chemotherapy group and in 67% (20/30) of controls. Of the 12 Bcl-2-positive cases in the chemotherapy group, 5 were diffusely positive [Bcl-2(2+)] and 7 were focally positive [Bcl-2(+)]. Of the 20 Bcl-2-positive cases in the control group, 18 were diffusely positive and 2 were focally positive. We speculate that Bcl-2 expression was down-regulated by trans-arterial administration of chemotherapeutic agents and was associated with apoptosis and degeneration of breast cancer cells.

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