PM2.5 promotes Drp1-mediated mitophagy to induce hepatic stellate cell activation and hepatic fibrosis via regulating miR-411.

BACKGROUND: Particulate matter≤ 2.5 µm (PM2.5) is a type of environmental agent associated with air pollution, which induces hepatic fibrosis. However, the function and mechanism of PM2.5 on hepatic stellate cell (HSC) proliferation and fibrosis remain largely unknown. METHODS: Human HSC line (LX-2) and murine HSCs were exposed to various doses of PM2.5. microRNA (miR)-411 expression was detected via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell proliferation, fibrosis, mitochondrial dynamics dysfunction and mitophagy were determined via cell counting kit-8 (CCK-8), qRT-PCR, Western blotting and immunofluorescence. RESULTS: PM2.5 facilitated HSC proliferation and fibrosis via increasing the levels of ACTA2, Collagen 1, TIMP1 and TGF-ß1. PM2.5 reduced miR-411 expression, and contributed to mitochondrial dynamics dysfunction via increasing Drp1 and decreasing OPA1, TOM20 and PGC-1α levels. PM2.5 promoted mitophagy by upregulating the levels of Beclin-1, LC3II/I, PINK1 and Parkin. miR-411 overexpression or autophagy blockage using 3-methyladenine (3-MA) relieved PM2.5-mediated cell proliferation and fibrosis-associated factor expression in HSCs. Drp1 was targeted by miR-411. miR-411 mitigated PM2.5-induced mitophagy via targeting Drp1. Drp1 overexpression abolished the inhibitory role of miR-411 in cell proliferation and fibrosis-associated factor levels in HSCs. CONCLUSION: PM2.5 induced HSC activation and fibrosis via promoting Drp1-mediated mitophagy by decreasing miR-411, thereby causing liver fibrosis.

Knockdown of Ubiquitin Associated Protein 2-Like (UBAP2L) Inhibits Growth and Metastasis of Hepatocellular Carcinoma.

BACKGROUND The aim of this study was to explore the influence of ubiquitin associated protein 2-like (UBAP2L) on the growth and metastasis of hepatocellular carcinoma (HCC) and its potential underlying mechanism. MATERIAL AND METHODS UBAP2L gene was knocked down in SMMC-7721 by RNA interference and cell function experiments were performed. A subcutaneous xenograft tumor model was constructed to examine the effect of UBAP2L silence on HCC growth. Finally, the whole genomic microarrays were used to screen the potential mechanism of UBAP2L in regulating the biological function of HCC. RESULTS Compared with those in the control group, the cell proliferation and clone formation were significantly reduced, cell cycle was arrested in G2/M phase, the number of apoptotic cells was remarkably increased, and the abilities of vascular formation and cell migration and metastasis were dramatically weakened in the shUBAP2L group (All P<0.05). UBAP2L knockdown significantly suppressed the tumor growth of HCC in vivo. Moreover, a total of 320 genes changed significantly after UBAP2L knockdown, among which, 159 genes were upregulated and 161 genes were downregulated. Then, gene enrichment analysis revealed that PI3K/AKT and P53 signal pathway were the most significant in the top 10 enrichments. Finally, Western blot analysis verified that UBAP2L knockdown caused the increase of P21 and PTEN and decrease of CDK1, CCNB1, p-PI3K, and p-AKT. CONCLUSIONS UBAP2L plays an oncogenic role in HCC, and knockdown of its expression significantly inhibits HCC growth and metastasis, which may be related to the regulation of PI3K/AKT and P53 signaling pathways by UBAP2L.