The levels and relations of prostaglandins in pregnant and non-pregnant tumor-bearing mice.

Tissue levels of prostaglandins PGE1, PGE2, PGF1 alpha and PGF2 alpha were determined in muscle tissues of pregnant, and in tumor tissue of pregnant tumor-bearing female syngeneic Balb/c mice bearing a transplanted methylcholanthrene-induced fibrosarcoma. Tests were done on the 7th, 10th, and 15th days of tumor growth/pregnancy using a thin-layer chromatography method. The results showed significantly increased levels of prostaglandins in tumor-bearing animals as well as in pregnant tumor-bearing hosts when compared to controls. Changes in the levels of PGE1 in pregnant mice were the most prominent among all prostaglandins tested. In these animals, the mutual relations between prostaglandin subclasses were not affected. In tumor-bearing mice, especially those which were pregnant, the inversion of prostaglandins of the E series was observed. Tumor changed the levels of the E series prostaglandins in favour of PGE2. However, it did not change the relation between those of the F series. The levels of PGE2 were more expressed in pregnant tumor-bearing hosts than in their non-pregnant counterparts. This has led us to the conclusion that, besides the malignant tumor, the pregnancy itself also potentiates immunosuppression. Blocking of PGE2 production in tumor-bearing animals might have potential therapeutic implications.