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Inhibition of the formation of autophagosome but not autolysosome augments ABT-751-induced apoptosis in TP53-deficient Hep-3B cells.

Ren-Jie WeiWen-Ren WuCheng-Tang PanChun-Yen YuChien-Feng LiLih-Ren ChenShih-Shin LiangYow-Ling Shirley Shiue
Published in: Journal of cellular physiology (2018)
The objective was to investigate the upstream mechanisms of apoptosis which were triggered by a novel antimicrotubule drug, ABT-751, in a tumor protein p53 ( TP53)-deficient hepatocellular carcinoma-derived Hep-3B cells. A series of in vitro assays indicated that ABT-751 caused the disruption of the mitotic spindle structure, collapse of mitochondrial membrane potential, generation of reactive oxygen species, DNA damage, G 2 /M cell cycle arrest, inhibition of anchorage-independent cell growth and apoptosis in Hep-3B cells accompanied by alteration of the expression levels of several DNA damage checkpoint proteins and cell cycle regulators. Subsequently, ABT-751 triggered apoptosis along with markedly upregulated several proapoptotic proteins involving in extrinsic, intrinsic, and caspase-mediated apoptotic pathways. A pan-caspase inhibitor suppressed ABT-751-induced apoptosis. ABT-751 also induced autophagy soon after the occurrence of apoptosis through the suppression of AKT serine/threonine kinase/mechanistic target of rapamycin signaling pathway. Exogenous expression of the TP53 gene significantly incurred both apoptosis and autophagy in Hep-3B cells. Pharmacological inhibition of autophagosome (early autophagy) but not autolysosome (late autophagy) enhanced ABT-751-induced apoptosis in TP53-deficient Hep-3B cells. Our study provided a new strategy to augment ABT-751-induced apoptosis in TP53-deficient cells.
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