ROS production by circulating phagocytes and Guerin carcinoma resistance to cisplatin.

Abstract

Tumor drug resistance remains a primary cause of unsuccessful cancer therapy. The search for biological markers of the sensitivity/resistance of malignant neoplasms to drug therapy is an urgent and important task, the solution of which will increase the effectiveness of anticancer chemotherapy. To study the relationship between the functional activity (parameters of the phagocytosis and reactive oxygen species (ROS) production) of neutrophils and monocytes in the peripheral blood of rats with transplanted Guerin carcinoma and the degree of its sensitivity to cisplatin (Cpt). The original and Cpt-resistant variants of Guerin carcinoma were transplanted to female Wistar rats 2.5months old. The parameters of the phagocytic activity of circulating neutrophils and monocytes were determined by the degree of ingestion of inactivated and FITC-labeled staphylococci using flow cytometry. The number of ROS-generating cells and the intensity of ROS production by phagocytes were determined by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate. The growth of both variants of Guerin carcinoma caused a statistically significant decrease in the intensity of neutrophil phagocytosis by more than 47% with a tendency to the reduction of the intensity of phagocytosis by monocytes. The phagocytic activity of circulating neutrophils and monocytes did not differ significantly between the groups of animals with the original and Cpt-resistant variant of Guerin carcinoma. In contrast, the intensity of ROS generation by both monocytes and neutrophils in the peripheral blood of animals with Cpt-resistant tumor increased by more than 86% as compared to original carcinoma-bearing rats. This study provides evidence that the intensity of ROS production by circulating monocytes and neutrophils may reflect the degree of tumor sensitivity to Cpt. Increased intensity of ROS production could serve as a pretreatment predictor of the formation of tumor drug resistance.