Action of tamoxifen on the uterus of rats bearing experimental mammary tumors.

SAMBUCO L; ACTIS A; CROCI M; MARTIN G; CRICCO G; MOHAMAD N; GUTIERREZ A; RIVERA E; BERGOC R

Pinamar. Argentina

Congreso; 10th Congress-Panamerican Association for Biochemistry and Molecular Biology XLI Reunión Anual de la Sociedad Argentina de Investigación Bioquímica Biología Molecular XX Reunión anual de la Sociedad Argentina de Neuroquímica; 2005

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Extended tamoxifen (Tam) administration in breast cancer therapy leads to an increased risk for endometrial neoplasia. The objective of this work was to analyze the effect of Tam on the uterus of rats bearing N-nitrose-N-methylurea induced mammary tumors: A) Tam (1 mg/kg.day, sc) was administered for 120 days beginning when rats were 40 days old. B) Tam was administered for 30 days. Control groups not receiving Tam treatment or NMU injection were included. Results disclosed in the investigated uteri were: in A) highly significant decrease of uterine weight and absence of steroid receptors expression. Histological studies showed very thin, nearly atrophic endometrial mucosae and also atrophic smooth muscle wall. In B) significant diminution of estrogen receptor expression, increase of progesterone receptor and cystic glandular endometrial hyperplasia. Data were correlated with the expression of: PCNA, c-fos, bax, bcl-2 and insulin growth factor type-I. In A and B, rat estral cycle was arrested at diestrum (o.m. analysis of vaginal smears). Nuclear anisocaryosis and hyperchromasia was observed in the endometrium of NMU-injected rats regardless of Tam treatment. Results show the wide range of biological interrelations established at the end of treatments. poster