EXPRESSION OF P-GLYCOPROTEIN INFLUENCES RESISTANCE AGAINST ANTHRACYCLINES IN CLINICAL GASTRIC CARCINOMAS

In 58 human gastric cancers, the expression of P-glycoprotein (P-gp) w as evaluated immunohistochemically and chemosensitivity was determined using the in vitro succinate dehydrogenase inhibition (SDI) test. Tum ors which contained over 75% stained cells were scored as positive, an d 14 of 58 cases (24%) were positive. There was no significant correla tion between P-gp expression and clinicopathologic features. The succi nate dehydrogenase (SD) activity for each drug of P-gp positive and ne gative tumors was as follows: 81.8 +/- 15.2% vs. 66.3 +/-16.1% for Adr iamycin (ADM), 75.5 +/- 14.2% vs. 59.1 +/- 17.6% for aclacinomycin A ( ACR), 71.7 +/- 15.0% vs. 61.1 +/- 14.0% for mitomycin C (MMC), and 57. 5 +/- 18.4% vs. 47.0 +/- 16.7% for cisplatin (CDDP). The increase in S D activity was evident in P-gp positive tumors compared with negative ones in cases of ADM (P = 0.0044), ACR (P = 0.0105), and MMC (P = 0.03 53). We suggested that P-gp expression is closely related to chemosens itivities of human gastric cancers to anthracyclines. (C) 1994 Wiley-L iss, Inc.