Sensitivity of fresh and cultured ovarian tumor cells to tumor necrosis factor, interferon-alpha 2, and OK-432

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Abstract
The in vitro sensitivity to rTNF, rIFN-α2, and OK-432 of 11 freshly derived human ovarian tumors and 2 established tumor cell lines was examined in a cytotoxic assay using the 51Cr release test. Nine fresh lines were sensitive to rTNF, 8 to OK-432, and only 2 were sensitive to rIFN-α2. Cytotoxicity by rIFN-α2 was of lesser magnitude than the cytotoxicity mediated by rTNF or OK-432. The time of exposure and the concentration of BRM required for maximal cytotoxicity varied from line to line. Two fresh tumor cell lines and 1 established cell line (PA-1) were sensitive to all 3 BRMs, while 2 other FOCs and 1 cell line (SKOV-3) were resistant to all BRMs. The remaining FOC showed an intermediate degree of sensitivity. These results demonstrate the existence of heterogeneity of ovarian carcinoma tumor cell lines to lysis by BRMs. Among the FOCs, the 2 endometrioid carcinomas tested were highly sensitive to rTNF, whereas the serous carcinomas were more sensitive to OK-432. Low grade tumors were more sensitive to BRM than high grade tumors, and tumor extension did not correlate with sensitivity to the BRM. When tumor targets were exposed to more than 1 BRM added either simultaneously or sequentially, the net cytotoxic effect achieved was usually inferior to the sum cytotoxicity obtained by each BRM alone. Furthermore, rTNF and OK-432 were cytostatic to most ovarian tumor cell lines examined. The results of this study demonstrate that certain BRMs exert a direct effect on fresh ovarian tumor cells independently of host factors. These findings suggest that in vitro screening of a patient's tumor cells for sensitivity to a particular BRM prior to therapy could be beneficial for the proper identification of patients most likely to benefit from the treatment.