Radiosensitization of Prostate Cancer Cells by 2-Deoxyglucose

Abstract

Prostate cancer is the most common malignancy of men. Treatment options include radiotherapy with or without hormonal manipulation and radical prostatectomy. However, there is no effective treatment for disseminated disease. A hallmark of malignancy is abnormal metabolism which also confers survival advantages and contributes to resistance to therapy. In response to exposure to ionizing radiation, metabolic pathways are activated which can protect the cell from irreversible injury. Tumor cell glycolytic activity is elevated and correlates with aggressiveness and radio resistance, indicating that targeting glucose metabolism may sensitize cancer cells to radiation. We have demonstrated that the clonogenic kill of PC3 cells induced by exposure to x-rays was enhanced by the glycolytic inhibitor 2-deoxyglucose (2DG). In contrast, treatment with 2DG failed to inhibit growth of multicellular spheroids derived from LNCaP cells. However, 2DG treatment, in the absence of irradiation, induced similar toxicity to PC3 and LNCaP cells cultured as monolayers. Radiation-induced cell cycle arrest was prevented by the simultaneous administration of 2DG in both cell lines, indicating a possible mechanism underlying sensitization. Therefore, we hypothesise that observed differences in cellular response to incubation with 2DG in the presence or absence of ionizing radiation resulted from variation in metabolic processes between tumor cell types. We conclude that inhibition of glucose metabolism by 2DG is an effective method for sensitizing prostate cancer cells to experimental radiotherapy and that this may occur by preventing DNA repair during radiation-induced cell cycle arrest.