The BH3-mimetic ABT-737 targets the apoptotic machinery in cholangiocarcinoma cell lines resulting in synergistic interactions with zoledronic acid

Abstract

Purpose: In TFK-1 and EGI-1 cholangiocarcinoma cell lines zoledronic acid (ZOL) determines a S-phase block without apoptosis. Here we investigated the occurrence of apoptosis stigmata when ZOL is associated to the BH3-mimetic ABT-737. Methods:In EGI-1 and TFK-1 cholangiocarcinoma cell lines untreated or treated with ABT-737 alone or in combination with ZOL, the pro-survival proteins pattern (BCL-2, BCL-XL, MCL-1, HSP72, HSP27) was investigated by biochemical criteria along with the occurrence of mitochondrial damage evaluated by cytofluorimetric analysis using a cationic dye.Results: ABT-737 induced growth inhibition and significantly affected the colony-forming ability of both EGI-1 and TFK-1 cells. However, activated PARP-1 or/and caspase-3 cleavage (apoptosis markers) were detected only at the highest ABT-737 concentrations used. Combined treatment showed synergistic effect by converting the predominant cytostatic effect of ZOL into a cytotoxic one as shown by striking increment of mitochondrial-harmed cells along with PARP-1 activation and caspase-3 cleavage. Conclusion:The lacking of apoptosis following ZOL treatment in these cholangiocarcinoma cell lines appears to be multifactorial and could be ascribed to the large constitutive expression of prosurvival proteins. The efficacy of ZOL treatment requires a concomitant unleashing of apoptosis by using a selective BH3-mimetic as ABT-737. The rational targeting of specific components of the apoptotic pathway may appear a useful approach to improve the treatment of refractory or relapsed cholangiocarcinoma. Combined treatment could be further explored in vivo tumor model of cholangiocarcinoma

Prognostic Impact of Bcl-2 Depends on Tumor Histology and Expression of MALAT-1 lncRNA in Non–Small-Cell Lung Cancer

“…The slides were incubated for 60 min with the primary monoclonal antibodies against Bcl-2 (clone 100, epitope: amino acids 41-54; mouse IgG1, 1:100), [38][39][40] against Bcl-xl (clone H-5, epitope: C-terminus, mouse IgG1, 1:1000), 41,42 and against Mcl-1 (clone RC-13, epitope: amino acids 1-327; mouse IgG1, 1:2000). 43,44 The three antibodies were purchased from Santa Cruz Biotechnology (Heidelberg, Germany). Moreover, a fourth antibody against acidic nuclear phosphoprotein 32A epitope (pp32/PHAPI; clone RJ1, mouse IgG1, 1:2000; Alexis Biochemicals Grünberg, Germany) was applied.…”

The sphingosine kinase 2 inhibitor ABC294640 inhibits cervical carcinoma cell growth

“…Third, Bcl-2 inhibition, mutation or depletion could significantly sensitize the anti-cancer activity by a number of molecule-targeted agents [ 36 – 40 ]. Bcl-2 pharmacological inhibitors were then applied, including the specific Bcl-2 inhibitor GDC-0199 (also known as ABT-199) [ 41 , 42 ] and the pan Bcl-2 inhibitor ABT-737 [ 37 , 40 , 43 ]. As shown in Figure 4A , ABC294640 (5 μmol/L)-induced C33A cell growth inhibition (MTT OD reduction) was largely potentiated with co-treatment of the Bcl-2 inhibitors, which also dramatically facilitated ABC294640-induced cell apoptosis (TUNEL assay, Figure 4B ).…”

“…To exclude the off-target effect of the above inhibitors, i.e. ABT-737 [ 37 , 40 , 43 ], we utilized shRNA method to selectively knockdown Bcl-2 in C33A cells. Two distinct Bcl-2 shRNAs (“-a/-b”), with non-overlapping sequences, were applied.…”

Preferential targeting of cancer stem cells in the radiosensitizing effect of ABT-737 on HNSCC

“…ABT-737 binds Bcl-2 and Bcl-X L with high affinity and has shown single-agent efficacy against multiple cell lines as well as in combination with standard therapy in human leukemia and multiple myeloma models [ 3 , 25 ], lymphoma [ 26 ], melanoma [ 13 ], cholangiocarcinoma [ 14 ] or HNSCC [ 8 ]. Except some reports on Hela cells [ 27 ], non-small-cell-lung cancer cells [ 19 ] and breast cancer cells [ 20 , 28 ], no more data are available on a synergistic effect of BH3-mimetics with radiation, especially on HNSCC.…”