SERUM PYRROLIDONE CARBOXYPEPTIDASE ACTIVITY IS MODIFIED IN POSTMENOPAUSAL BUT NOT PREMENOPAUSAL WOMEN WITH BREAST CANCER

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189 Citation: Maturitas Volume 63, Supplement 1, May 2009, Page S51 SERUM PYRROLIDONE CARBOXYPEPTIDASE ACTIVITY IS MODIFIED IN POSTMENOPAUSAL BUT NOT PREMENOPAUSAL WOMEN WITH BREAST CANCER M.J. Ramirez-Exposito, M.P. Carrera-Gonzalez, B. Duenas, J.M. Martinez-Martos 1 University of Jaen, Jaen, Spain; University of Jaen, Health Sciences, Jaen, Spain; Complejo Hospitalario de Jaen, Jaen, Spain Objectives: Pyrrolidone carboxypeptidase (Pcp) (E.C. 3.4.19.3), is an omega peptidase widely distributed in fluids and tissues and hydrolyses N-terminal pyroglutamic residues from biologically active peptides such as gonadotropin releasing hormone (GnRH). Previous results obtained by us showed a decrease in human breast cancer tissue Pcp activity, suggesting that this enzyme activity or its putative substrates may play a major role in breast cancer pathogenesis. The aim of the present work is to analyse serum Pcp activity in preand postmenopausal women with breast cancer and to compare it with their respective controls. Methods: We measured fluorometrically serum Pcp activity using pyroglutamyl-beta-naphthylamide as substrate in 57 women diagnosed with ductal infiltrating carcinomas. Results: Healthy postmenopausal women showed higher values of Pcp activity than premenopausal women (98.69±4.94.vs 79.06±4.37 pmol/min/mg protein). On the contrary, no differences were found in serum Pcp activity between preand postmenopausal women with breast cancer (75.62±4.42 vs 79.71±4.63 pmol/min/mg protein). Conclusions: The present results document changes in Pcp activity in serum of postmenopausal but not premenopausal women with breast cancer. These changes may reflect the functional status of the enzyme substrates, which can be selectively activated or inhibited as a result of specific conditions brought about by the tumor under different hormonal conditions. In this connection, GnRH receptors and GnRH mRNA have been found in breast tissue, raising the possibility of a local role for GnRH in the human mammary gland.