DIRECT RELATION BETWEEN INTEGRIN b1 AND PMEK PROTEIN EXPRESSION IN MDA-231 BREAST CANCER CELL LINE.

Aliakbar Taherian ¹, Thomas A. Haas ²

ABSTRACT

Introduction: Breast cancer is the most common malignancy and accounts for one-third of all incidents of cancer in women in North America. Research on breast cancer cell lines and their detailed molecular analysis may yield a better diagnostic or therapeutic method. Integrins are a large family of heterodimeric proteins that mediate cell-cell and cell-extra cellular matrix adhesion.

Methods: Using flow cytometry the expression of a_vb₃, a_vb₆, a_vb₅, b₅, b₁, a₁ and a_IIb integrins was compared in three different breast cancer cell lines (MDA-MB-435, MDA-MB-231, and MCF7) and a non-breast cancer cell line (Hek-293). MAPK signaling pathway proteins were measured by western blot analysis.

Results: Only MDA-MB-435 expressed a_vb₃ that apparently didn’t have any effect on binding to different substrates in adhesion assays. b₁ integrin was the most prominent integrin in all the cancer cell lines examined and the highest level was in MDA-231. There was a direct relation between pMek and b₁ expression, i.e. pMek level in MDA-231 was more than MDA-435 and in MCF7 was the least and this could be related to their invasive potential, since MDA-231 cell line has much higher invasive potential than MCF7 cells.

An interesting part of the result was the intense expression of pErk in MCF7 after PMA treatment, while no pMek was expressed in the same samples. Since pMek is the only known protein to phosphorylate Erk via Ras-Raf-Mek-Erk pathway, PMA might activate a different signaling pathway to phosphorylate Erk. In our experiments, the non-breast cancer cell line Hek-293 could be differentiated from breast cancer cell lines by expressing a lower expression of FAK and a higher expression of phospho Src (T517) and phospho ERK.

Conclusion: Overall b1 is a good marker of breast cancer cells and different response to PMA, shows that different signaling pathways are active in different cell lines, so more research is needed to find a better prognostic and treatment markers.

¹Department of Anatomy & Cell Biology, University of Saskatchewan, Health Science Building, 107 Wiggins Road, Saskatoon, S7N 5E5, Canada.

²Deptartment of Histology/Pathology, Kashan University of Medical Science, Kashan, Iran