Aromatase activity and its gene expression in tumor tissue of smokers and non-smokers with breast cancer

Tissue was sampled from 121 tumors of the breast. The activity of aromatase (estrogen synthetase) was assessed by radiobiochemical means in 61 cases; gene expression was evaluated with the aid of polymerase chain reaction in 14 and the same--by the dot-blot procedure in 46 patients. Inveterate smokers (15 years and more) made up 16.5%. The smokers revealed a distinct tendency towards aromatase activity decreasing in tumor tissue (chiefly in menopausal patients) as well as lower intensity of aromatase gene expression assessed in terms of polymerase chain reaction. Alongside with other evidence, our finding point to long-term-smoking-related sensitivity of intratissular estrogen synthesis being higher than in general circulation. It also demonstrated local aromatization inhibition in tumor tissue, the latter being a possible mechanism which causes tumor tissue hormone sensitivity to change in smokers and affects course of disease.