Nitric oxide and cancer: the emerging role of S-nitrosylation.

Nitric oxide (NO˙) is a short-lived, endogenously produced gas that is highly diffusible across cell membranes and acts as a signaling molecule in the body. The redox state and chemistry of NO˙ facilitate its interaction with various proteins thus regulating various intracellular and intercellular events. One of the key mechanisms by which NO˙ regulates the function of various target proteins is through the coupling of a nitroso moiety from NO-derived metabolites to a reactive cysteine leading to the formation of a S-nitrosothiol (SNO), a process commonly known as S-nitrosylation. S-nitrosylation signaling events within the cell have led to the discovery of many other physiological functions of NO˙ in many other types of cells including cancer cells. Only recently are the diverse roles of S-nitrosylation in cancer beginning to be understood. In the present review we discuss the recent evidence for the diverse roles of NO˙/SNO-related mechanisms in cancer biology and therapy, including the participation of NO˙ in the pathogenesis of cancer, its duality in protecting against or inducing cancer cell death and the contribution of NO˙ to metastatic processes. In addition, NO˙ can be therapeutically used in the reversal of tumor cell resistance to cytotoxic drugs and as a sensitizing agent to chemo- and radiotherapy. Finally, recent studies providing evidence for NO-related mechanisms of epigenetic gene expression regulation will also be discussed. Undoubtedly, new exciting results will contribute to this rapidly expanding area of cancer research.

Breast cancer screening: another point of view.

The breast cancer screening programmes (BCSP) are very controversial at the present time. They are evaluated by different socio-economic sectors, each with its own particular point of view. Large numbers of breast cancer cases are concentrated in the Oncology Services, which are, therefore, sensitive to the changes that these programmes could bring about. All patients attending the medical oncology and radiotherapy services of the Reina Sofia University Hospital, Cordoba from January 1994 until January 2003 were reviewed. Of 1785 patients, 829 went to these services after the start of the BCSP introduced in March 1999 and 956 before it. The variables analysed were age, presentation form, stage and treatment received. In conclusion, the BCSP has produced favourable changes with respect to stage (increasing the percentage of early breast cancer) and therapeutic management (increasing conservative surgery and decreasing the number of adjuvant treatments (radiotherapy and chemotherapy)). These changes are more outstanding in the population group covered by the BCSP.