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BCL-2 family inhibitors enhance histone deacetylase inhibitor and sorafenib lethality via autophagy and overcome blockade of the extrinsic pathway to facilitate killing.

ABSTRACT: We examined whether the multikinase inhibitor sorafenib and histone deacetylase inhibitors (HDACI) interact to kill pancreatic carcinoma cells and determined the impact of inhibiting BCL-2 family function on sorafenib and HDACI lethality. The lethality of sorafenib was enhanced in pancreatic tumor cells in a synergistic fashion by pharmacologically achievable concentrations of the HDACIs vorinostat or sodium valproate. Overexpression of cellular FLICE-like inhibitory protein (c-FLIP-s) or knockdown of CD95 suppressed the lethality of the sorafenib/HDACI combination (sorafenib + HDACI). In immunohistochemical analyses or using expression of fluorescence-tagged proteins, treatment with sorafenib and vorinostat together (sorafenib + vorinostat) promoted colocalization of CD95 with caspase 8 and CD95 association with the endoplasmic reticulum markers calnexin, ATG5, and Grp78/BiP. In cells lacking CD95 expression or in cells expressing c-FLIP-s, the lethality of sorafenib + HDACI exposure was abolished and was restored when cells were coexposed to BCL-2 family inhibitors [ethyl [2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)]-4H-chromene-3-carboxylate (HA14-1), obatoclax (GX15-070)]. Knockdown of BCL-2, BCL-XL, and MCL-1 recapitulated the effects of GX15-070 treatment. Knockdown of BAX and BAK modestly reduced sorafenib + HDACI lethality but abolished the effects of GX15-070 treatment. Sorafenib + HDACI exposure generated a CD95- and Beclin1-dependent protective form of autophagy, whereas GX15-070 treatment generated a Beclin1-dependent toxic form of autophagy. The potentiation of sorafenib + HDACI killing by GX15-070 was suppressed by knockdown of Beclin1 or of BAX + BAK. Our data demonstrate that pancreatic tumor cells are susceptible to sorafenib + HDACI lethality and that in tumor cells unable to signal death from CD95, use of a BCL-2 family antagonist facilitates sorafenib + HDACI killing via autophagy and the intrinsic pathway.

SUBMITTER: Martin AP

PROVIDER: S-EPMC2713125 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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BCL-2 family inhibitors enhance histone deacetylase inhibitor and sorafenib lethality via autophagy and overcome blockade of the extrinsic pathway to facilitate killing.

Martin Aditi Pandya AP Park Margaret A MA Mitchell Clint C Walker Teneille T Rahmani Mohamed M Thorburn Andrew A Häussinger Dieter D Reinehr Roland R Grant Steven S Dent Paul P

Molecular pharmacology 20090529 2

We examined whether the multikinase inhibitor sorafenib and histone deacetylase inhibitors (HDACI) interact to kill pancreatic carcinoma cells and determined the impact of inhibiting BCL-2 family function on sorafenib and HDACI lethality. The lethality of sorafenib was enhanced in pancreatic tumor cells in a synergistic fashion by pharmacologically achievable concentrations of the HDACIs vorinostat or sodium valproate. Overexpression of cellular FLICE-like inhibitory protein (c-FLIP-s) or knockd ...[more]

PMID: 19483105

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Project description:Objective: identify novel and relevant aspects of Sorafenib action on liver cancer cells. We found that in rat hepatocholangiocarcinoma (LCSC-2) cells, exposure to the MEK/multikinase inhibitor sorafenib did not inhibit ERK phosphorylation nor induced appreciable cell death in the low micromolar range; instead, the drug elicited a raise of intracellular reactive oxygen species (ROS) accompanied by a severe decrease of oxygen consumption and intracellular ATP levels, all changes consistent with mitochondrial damage. Moreover, Sorafenib induced depolarization of isolated rat liver mitochondria, indicating a possible direct effect on the organelle. Microarray analysis of gene expression in sorafenib-trated cells revealed a metabolic reprogramming toward aerobic glycolysis, that likely accounts for resitance to drug toxicity in this cell line. Importantly, cytotoxicity was strongly potentiated by glucose withdrawal from the culture medium or by the glycolytic inhibitor 2-deoxy-glucose, a finding also confirmed in the highly malignant melanoma cell line B16F10. Mechanistic studies revealed that ROS are pivotal to cell killing by the Sorafenib + 2DG combination, and that a low content of intracellular oxidants is associated with resistance to the drug; instead, Thr172phosphorylation/activation of the AMP-activated protein kinase (AMPK), induced by Sorafenib, may exert protective effects, since cytotoxicity was enhanced by an AMPK specific inhibitor and prevented by the AMPK activator Metformin. Overall, this study identifies novel and relevant aspects of Sorafenib action on liver cancer cells, including mitochondrial damage, induction of ROS and a metabolic cell reprogramming towards “glucose addiction”, potentially exploitable in therapy. Microarray analysis of gene expression in sorafenib-trated cells. LCSC-2 cells were incubated with sorafenib 2.5 mM under serum deprivation for 12 hours. The total RNA was isolated from LCSC2, 24h after treatment, using the RNeasy mini kit (Qiagen, Hilden, Germany), RNA was quantified using a UV spectrophotometer and RNA quality and integrity were assessed Agilent 2100 Bioanalyzer (Agilent, Santa Clara, CA, USA). The resulting total RNA was then used to create the biotin-labeled library to be hybridized on GeneChip Rat Gene expression 1.0 st Array (Affymetrix, Santa Clara, CA, USA), according to the recommended experimental protocols provided by the suppliers. The CEL files resulting from the hybridization were analyzed using the Partek® Genomic Suite™ (Partek GS). Gene-level calculation was performed by Robust Multichip Average and normalization by quantile sketch.

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BCL-2 family inhibitors enhance histone deacetylase inhibitor and sorafenib lethality via autophagy and overcome blockade of the extrinsic pathway to facilitate killing.

Publications

BCL-2 family inhibitors enhance histone deacetylase inhibitor and sorafenib lethality via autophagy and overcome blockade of the extrinsic pathway to facilitate killing.

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