Distinct epithelial cadherin protein expresión pattern in human breast cancern cell lines IBH-4 and IBH-6

LENTZ EM; CASTILLO L; ZACCHI N; LÜTHY I; VAZQUEZ-LEVIN MH

Buenos Aires, Argentina

Congreso; VII Jornadas Multidisciplinarias de la Sociedad Argentina de Biologia; 2005

Sociedad Argentina de Biologia

 Epithelial cadherin (E-cad) is a 120 KDa membrane glycoprotein that participates in Ca2+-dependent cell-cell adhesion (1). Aberrations in E-cad (i.e. decreased gene expression, presence of mutations, protein processing) have been associated with increased tumor malignancy and invasiveness in cancer cell lines in vitro. This study was aimed at evaluating E-cad protein expression analysis in IBH-4 and IBH-6 human breast cancer estrogen and progesterone-sensitive cell lines developed from patient’s primary tumors (2), and compare it with that obtained with the MCF-7 cell line. Materials & Methods: Total protein extracts were prepared in Laemmli sample buffer from IBH-4, IBH-6 and MCF-7 cell cultures and from 2 days-Serum free (SF)-conditioned medium. E-cad protein forms were identified by Western immunoblotting using antibodies towards three different E-cad domains Results: As previously reported, the whole protein and the soluble E-cad ectodomain were identified in MCF-7 cell extracts and SF-conditioned medium, respectively. Contrasting, very low levels of full-length E-cad were detected in protein extracts from IBH-4 and IBH-6; moreover, two truncated isoforms of 89 and 82 KDa were identified, both lacking the intracellular epitope, suggesting a different C-terminal end. In IBH-4 and IBH-6 SF-conditioned media, soluble E-cad could not be detected even after 20 times medium concentration. Conclusion: A distinct E-cad expression pattern was identified in IBH-4 and IBH-6 human breast cancer cell lines compared to MCF-7. Changes could result from alterations in post-transcriptional and/or post-translational processing, and may be related to the invasive behavior reported for these cell lines.