The actions and interactions of nitric oxide in solid tumours

The small molecule nitric oxide (NO) has undergone an image change since its identification as a biological messenger in 1987. It is a free radical, with a diverse range of actions in both physiological and pathological processes. Whilst over 30 000 research papers have been written to date on NO, its role in tumour biology remains incompletely understood and research in this field is still in its infancy. NO would appear to have both tumour promoting and inhibiting effects which are presumed to be dependent on its local concentration within the tumour. Recently the relationships of NO to the tumour suppressor gene p53 have been experimentally elucidated, demonstrating how mutations of p53 may adversely affect the host by enhancing NO production. This review summarizes the brief history of this molecule, outlines its roles in the common solid tumours and suggests areas for future research.