BETA-ADRENERGIC RECEPTORS IN BREAST TUMOR CELL LINES

ARIANA BRUZZONE, CECILIA PÉREZ, LILIAN CASTILLO AND ISABEL A. LUTHY

Buenos Aires

Jornada; VIII Jornadas Multidisciplinarias de la Sociedad Argentina de Biología; 2006

Sociedad Argentina de Biología

BETA-ADRENERGIC RECEPTORS IN BREAST TUMOR CELL LINES. Ariana Bruzzone, Cecilia Pérez, Lilian Castillo and Isabel A. Lüthy. Instituto de Biología y Medicina Experimental – CONICET, Buenos Aires, Argentina. e-mail: bruzzone@dna.uba.ar Our group has previously described the presence of Alpha2-adrenergic receptors (A2-AR) in different human and murine breast cancer cell lines. We have found the presence of different subtypes of A2-AR in the human HS-578T cell line by RT- PCR and by immunofluorescence in the murine MC4-L5 tumor cell line. Specific Alpha2-adrenergic agonists enhanced cell proliferation in both cell lines. The presence of Alpha2-adrenergic receptors was observed by other groups in the human breast cancer cell lines MCF-7 and MDAMB- 231. In order to further characterize adrenergic receptors in breast cancer cell lines, we have evaluated the presence of Beta-adrenergic receptors in the human HS-578T cell line and in the murine MC4-L5 one. We have seen positive staining for Beta2-AR and Alpha2-AR by immunocytochimestry and immunofluorescence in both cell lines. Both essays were performed using specific antibodies against Beta2-AR and A2-AR in 1:50 final dilution. In order to study the biological effect of these receptors, we have analyzed cell proliferation using the [3H]-thymidine incorporation method in the presence of the natural adrenergic agonist (epinephrine, EPI) and a specific Beta-adrenergic specific agonist (isoproterenol, ISO). Cell proliferation was significantly enhanced after the treatment with EPI in both cell lines, the murine MC4-L5 showing an EC50=0.13 pM, whereas the human HS-578T cell line showing an EC=0.16 nM. On the other side, ISO induced a significant decline in [3H]-thymidine incorporation in both cell lines with values of EC=1.4 pM and 17nM for MC4-L5 and HS-578T respectively. The results obtained agree with those previously observed in our laboratory using other breast tumor cell lines and suggest that epinephrine should be acting mainly trough Alpha2-ARs, which are associated with enhanced cell proliferation and not trough Beta-ARs associated with a decline in cell division.