An inhibition of p62/SQSTM1 caused autophagic cell death of several human carcinoma cells.
Bottom Line: Therefore, in this study, we examined the effects of p62 inhibition on the regulation of autophagy and cell survival in p62-positive carcinoma cells. p62-silencing dramatically suppressed cell proliferation and induced autophagy in p62 expressing PC9 and A549 cells.Electron microscopical analysis revealed the formation of autophagosomes with multilayer membranes caused by p62-silencing. p62 silencing-mediated reduced cell viability was restored by both genomic and pharmacological inhibition of autophagy but not that of apoptosis.These findings were also detected in several types of carcinoma cell lines including adenocarcinomas and squamous cell carcinomas.
Affiliation: Department of Pathology, School of Medicine, Tohoku University, Sendai, Japan.Show MeSH
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Mentions: We then examined the roles of p62 using p62 low-expressing (Fig.1a) H23 cells. p62-silencing slightly suppressed cell viability of H23 cells (Fig.6a). We then constructed p62 expression vector and transfected in H23 cells. p62 expression was increased by the transfection of p62 expression vector in a concentration dependent manner, but cell viability was not changed (Fig.6b,c). Because p62 inhibition also induced autophagy via mTOR inactivation (Fig.2a), we then hypothesized that exogenous p62-overexpression could influence the autophagy-activated cells. Figure6(d) demonstrated that the starvation-induced cell death was attenuated by p62-overexpression, which suggested that starvation-induced autophagy caused autophagic cell death in p62 low-expressing H23 cells, and exogenous p62-overexpression contributed to autophagy maturation. In addition, exogenous p62-overexpression decreased the effects of p62-silencing in PC9 cells (Fig.6e).
Affiliation: Department of Pathology, School of Medicine, Tohoku University, Sendai, Japan.