Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively is able to increase apoptosis in cancer cells as agent with minimum toxicity to noncancerous cells. However, all cancer cells are not sensitive to TRAIL-induced apoptosis. In this study, we showed the sub-lethal concentrations of a lysosomotropic autophagy inhibitor, IITZ-01, sensitizes cancer cells (renal, lung, and breast carcinoma) to TRAIL-induced apoptosis through DR5 upregulation and survivin downregulation through ubiquitin-proteasome pathway. Knockdown of DR5 or overexpression of survivin inhibited combined treatment with IITZ-01 and TRAIL-induced apoptosis. IITZ-01 downregulated protein expression of Cbl, ubiquitin E3 ligase, and decreased expression level of Cbl markedly led to increase DR5 protein expression and TRAIL sensitivity. Moreover, IITZ-01 decreased expression level of survivin protein via downregulation of deubiquitinase ubiquitin-specific protease 9X (USP9X) expression. Taken together, these results provide the first evidence that IITZ-01 enhances TRAIL-mediated apoptosis through DR5 stabilization by downregulation of Cbl and USP9X-dependent survivin ubiquitination and degradation in renal carcinoma cells.
Highlights
Lysosomes are acidic organelles within cells that degrade and reuse macromolecules through endocytosis, autophagy and phagocytosis, and are involved in regulation of cellular homeostasis [1,2].Lysosomotropic agents can selectively diffuse, accumulate into lysosomes, and induce pHCancers 2020, 12, 2363; doi:10.3390/cancers12092363 www.mdpi.com/journal/cancersCancers 2020, 12, 2363 alteration, decrease of enzyme activity and inhibition of calcium signaling in lysosome [3]
We examined whether IITZ-01 could augment Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human renal carcinoma cells
DR5 upregulation in IITZ-01 plus we investigated the importance of the DR5 upregulation in IITZ-01 plus TRAIL-induced apoptosis, TRAIL-induced apoptosis, Caki-1 and cells were transiently transfected with
Summary
Lysosomes are acidic organelles within cells that degrade and reuse macromolecules through endocytosis, autophagy and phagocytosis, and are involved in regulation of cellular homeostasis [1,2].Lysosomotropic agents can selectively diffuse, accumulate into lysosomes, and induce pHCancers 2020, 12, 2363; doi:10.3390/cancers12092363 www.mdpi.com/journal/cancersCancers 2020, 12, 2363 alteration, decrease of enzyme activity and inhibition of calcium signaling in lysosome [3]. Lysosomes are acidic organelles within cells that degrade and reuse macromolecules through endocytosis, autophagy and phagocytosis, and are involved in regulation of cellular homeostasis [1,2]. Several lysosomotropic drugs break down phagocytosis, endocytosis and autophagy by disrupting membrane fusion between intracellular organelles [4,5,6]. Chloroquine (CQ) and hydroxychloroquine (HCQ), well-known lysosomotropic drugs, increase lysosomal membrane permeabilization by neutralizing intracellular lysosomal pH, resulting in the induction of apoptotic cell death in cancer [7,8]. Two lysosomotropic agents can potentiate anti-cancer effect to various chemotherapeutic drugs and overcome resistance to anti-cancer drugs or irradiation in many cancer cells [9,10,11,12,13]. Lysosomotropic agents are capable of increasing therapeutic efficacy of tumors, but the underlying molecular mechanism is not clear
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