[Research advances on tumor therapy via nitric oxide]

Nitric oxide (NO) is a short-lived pleiotropic molecule involved in many physiological and pathological processes in the organism. As an important biologic mediator, nitric oxide has been focused in tumor study and therapy for its function in the process of tumor genesis, progression,and death. It is documented that nitric oxide plays a dual role:induction or suppression of tumorigenesis, which is dependent on different conditions, such as the concentration, time,and position of NO products. Tumor growth can be promoted by continuous low NO concentration, while cytotoxicity and apoptosis to tumor cells can be induced by quite high NO concentration. Currently, the concentration-dependent principle is the theoretical basis of tumor therapy mediated by NO. These tumor therapies can be classified into several types: firstly, drug treatments including chemotherapy, nitric oxide synthase inducer and inhibitor, together with related research from Chinese traditional medicine; secondly, radiotherapy and photodynamic therapy; thirdly, genic level therapy; and so on. Thus, the paper states the relationship and mechanism between NO and tumor, and summarizes research advances on tumor therapy via nitric oxide.