Enhancement of antineoplastic effect and attenuation of sister chromatid exchanges by prostaglandin E2 in Ehrlich ascites tumour cells treated with cyclophosphamide in vivo

Cytoprotective and genotoxic effects of vitamins K1 and B1 on irinotecan in vitro

Cultured human lymphocytes were treated with vitamins K₁ and B₁, potential anticancer agents, either alone or in combination with irinotecan, a semisynthetic analogue of camptothecin. The frequency of sister chromatid exchanges (SCEs) was measured as an indicator of genotoxicity and the proliferation rate index (PRI) and mitotic index (MI) was measured as indicators of cytostatic effect. Vitamin K₁ alone did not induce SCEs at the concentrations tested and combined with irinotecan does not increase SCE rates induced by irinotecan alone. Vitamin B₁ significantly increased SCEs and, in combination with irinotecan, increased rates further (p < 0.05). Vitamin K₁ decreased PRI and MI in combination with irinotecan, there were further increases in MI. At a low concentration, vitamin B₁ reduced the levels of SCE and increased PRI induced by irinotecan. The use of these vitamins in combination with antitumor agents might reduce clinical side effects of the antineoplastics.

Enhancement of cytogenetic damage and of antineoplastic effect in lymphoid L1210 leukemia cells treated with prostaglandin E2 and cyclophosphamide in vivo

An enhanced frequency of sister-chromatid exchanges (SCEs) and increased cell division delays induced by cyclophosphamide (CP) were observed when lymphoid L1210 leukemia cells were post-treated in vivo with prostaglandin E2 (PGE2). CP gave a slight, non-significant increase in survival while PGE2 gave a slight, non-significant decrease in survival. However, PGE2 in combination with CP was found to have a non-significant potentiating effect on survival in comparison with mice treated with CP alone. In mice treated with the combined CP (5 micrograms/g b.w.) plus PGE2 (2 micrograms/g b.w.) treatment, a significant (P < 0.01) enhancement of survival time in comparison with the untreated controls was observed.