Horm Metab Res 2003; 35(8): 502-505
DOI: 10.1055/s-2003-41809
Original Clinical
© Georg Thieme Verlag Stuttgart · New York

Serum Pyrrolidone Carboxypeptidase Activity in N-methyl Nitrosourea Induced Rat Breast Cancer

M.  P.  Carrera1 , M.  J.  Ramírez-Expósito1 , M.  T.  Valenzuela2 , M.  J.  García1 , M.  D.  Mayas1 , J.  M.  Martínez-Martos1
  • 1Departamento de Ciencias de la Salud, Área de Fisiología, Universidad de Jaén, Jaén, Spain
  • 2Departamento de Radiología y Medicina Física, Unidad Mixta de Investigaciones Médicas, Universidad de Granada, Hospital Universitario San Cecilio, Granada, Spain
Further Information

Publication History

Received 13 December 2002

Accepted after revision 4 February 2003

Publication Date:
02 September 2003 (online)

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Abstract

Pyrrolidone carboxypeptidase (Pcp) (E.C. 3.4.19.3) is an omega peptidase widely distributed in animal 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 Pcp activity, suggesting that this enzyme activity or its putative substrates may play a mayor role in breast cancer pathogenesis. The aim of the present work is to analyse serum Pcp activity in N-methyl-nitrosourea (NMU) induced rat mammary tumours using pyroglutamyl-β-naphthylamide as substrate. Serum Pcp activity was significantly lower in NMU-treated rats than in controls. Moreover, multiple regression analysis showed a significant correlation between Pcp activity and the number and size of tumours and the body weight of the animals. Since NMU-induced carcinomas are mainly oestrogen-dependent, the decrease observed in Pcp activity may reflect an increase in circulating levels of GnRH that lead to an increase in gonadal steroid hormones production responsible, at least in part, for the initiation and promotion of the disease.