ABT-737 ameliorates docetaxel resistance in triple negative breast cancer cell line

PURPOSE: This study aimed to validate the synergistic effect of ABT-737 on docetaxel using MDA-MB-231, a triple negative breast cancer (TNBC) cell line overexpressing B-cell lymphoma-2 (Bcl-2). METHODS: Western blot analysis was performed to assess expression levels of Bcl-2 family proteins and caspase-related molecules. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle distribution was determined by flow cytometry analysis. Benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (z-VAD-fmk) was used for pretreatment to assess the role of caspases. RESULTS: Cell viability of MDA-MB-231 after combination treatment with ABT-737 and docetaxel was significantly lower than that after docetaxel or ABT-737 monotherapy based on MTT assay (both P < 0.001), with a combination index of 0.41. The proportion of sub-G1 population after combination treatment was significantly higher than that after docetaxel or ABT-737 monotherapy (P = 0.001, P = 0.003, respectively). Pretreatment with z-VAD-fmk completely restored cell viability of MDA-MB-231 from apoptotic cell death induced by combination therapy (P = 0.001). Although pro-caspase-8 or Bid did not show significant change in expression level, pro-casepase-9 showed significantly decreased expression after combination treatment. Cleaved caspase-3 showed increased expression while poly (ADP-ribose) polymerase cleavage was induced after combination treatment. However, hypoxia-inducible factor 1-alpha and aldehyde dehydrogenase 1 totally lost their expression after combination treatment. CONCLUSION: Combination of ABT-737 with docetaxel elicits synergistic therapeutic effect on MDA-MB-231, a TNBC cell line overexpressing Bcl-2, mainly by activating the intrinsic pathway of apoptosis. Therefore, adjunct of ABT-737 to docetaxel might be a new therapeutic option to overcome docetaxel resistance of TNBCs overexpressing Bcl-2.

Transfection of SV 40 Large T Antigen into Corneal Endothelial Cells

The coeneal endothelium is essential for the maintenance of normal corneal hydration, thickness, and transparency. However, corneal endothelial cells are incapable of significant proliferation in vivo. As we age, the density of corneal endothelial (CEN) cells gradually decreases. The goal of our study is to explore the possibility of enhancing the proliferation of corneal endothelial cells by introduction of SV 40 large T antigen, a transforming protein. To this end, introduction of protein into CEN cells was assessed by liposome assisted beta-galactosidase transfection in vivo, ex vivo, and in vivo. In all cases, cells treated with liposome-protein complex have shown dramatic blue stain in beta-galactosidase activity staining. This result convinced us that we could artificially introduce a foreign protein into a cell. To ascertain where SV 40 large T antigen is localized in the cell, purified SV 40 large T antigen was transfected into the cells using liposome and its presence was determined immunohistochemically. We show that the liposome delivered SV 40 large is localized in the nucleus and mitotic figures which may suggest its functional activity.