Quantitative biochemical analysis of lactate dehydrogenase in human ovarian tissues: correlation with tumor grade

In an attempt to identify glycolytic capacity of normal and neoplastic human ovary, total lactate dehydrogenase (LDH) activity was measured in tissue cytosol originating from 69 patients (18 with benign ovarian tumor, 34 with ovarian carcinoma, six with nonepithelial ovarian malignant tumors, and 11 with tumor metastatic to ovary) and compared to the LDH activity of normal ovarian tissues (n = 19). Median value of total LDH-specific activity expressed as U/mg protein was 0.546 in normal tissues, 0.584 in benign tumors, 1.071 in malignancies metastatic to ovaries, 0.872 in nonepithelial primary ovarian tumors, and 0.818 in primary carcinomas. A significant rise in LDH-specific activity was found in malignant primary and secondary tumors of epithelial and nonepithelial origin, but not in benign neoplasms, compared to the activity in normal tissue. Ovarian carcinomas of serous histologic type did not differ in LDH activity from mucinous tumors. However, poorly differentiated carcinomas (grade 3) showed significantly enhanced activity of this glycolytic enzyme when compared to its grade 1 counterpart. The subgroup of grade 1 tumors did not differ in LDH activity from normal and benign ovarian tissue. Obtained results suggest that direct correlation might exist between ovarian epithelial tumor grade and lactate dehydrogenase activity.