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Studying the Effect of Downregulating Autophagy-Related Gene LC3 on TLR3 Apoptotic Pathway Mediated by dsRNA in Hepatocellular Carcinoma Cells.

ABSTRACT: The purpose of this study is to examine the role of the double-stranded RNA (dsRNA) activated Toll-interleukin-1 receptor domain-containing adaptor inducing interferon ? (TRIF) signal pathway in triggering apoptosis in hepatocellular carcinoma (HCC) cells.First, siRNA targeted autophagy-related gene LC3 (pU6H1-LC3 siRNA and siLC3) and a dsRNA used as a Toll-like receptor 3 (TLR3) ligand was constructed and synthesized, respectively. Then, a human HCC cell line was transfected with dsRNA, siLC3, and cotransfected with siLC3 and dsRNA (siLC3+dsRNA), respectively. Finally, quantification real-time polymerase chain reaction, western blotting, and immunofluorescence staining were used in the HCC line (SMMC7721), and MTT assay, flow cytometry, terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling, and transmission electron microscopy were used in an HCC xenograft model of nude mice. Human umbilical vein endothelial cell tube forming assay, color Doppler ultrasonographic flow image examination, and CD34-positive microvessel density were used in vitro and in vivo.Compared with untreated cells, the protein and mRNA expression of TLR3 and TRIF was up-regulated, in order, siLC3+dsRNA, dsRNA, and siLC3. Expression of LC3 was obviously down-regulated and the autophagosomes were significantly decreased in siLC3+dsRNA and siLC3, whereas in dsRNA (p < 0.05). LC3 and TRIF colocation was observed in HepG2 cells. Decreased cell viability, increased apoptosis, decrease in xenograft tumor volume, and angiogenesis potential were also observed in order (p < 0.05).Suppression of intracellular autophagy resulted in decreased degradation of TRIF protein, which can promote triggering of apoptosis by the TLR3-TRIF pathway. dsRNA and siLC3 could play anticancer roles in coordination.

SUBMITTER: Wang G

PROVIDER: S-EPMC5266382 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Studying the Effect of Downregulating Autophagy-Related Gene LC3 on TLR3 Apoptotic Pathway Mediated by dsRNA in Hepatocellular Carcinoma Cells.

Wang Guilan G Zhang Maona M Li Yunlong Y Zhou Jiaming J Chen Li L

Cancer research and treatment 20160613 1

<h4>Purpose</h4>The purpose of this study is to examine the role of the double-stranded RNA (dsRNA) activated Toll-interleukin-1 receptor domain-containing adaptor inducing interferon β (TRIF) signal pathway in triggering apoptosis in hepatocellular carcinoma (HCC) cells.<h4>Materials and methods</h4>First, siRNA targeted autophagy-related gene LC3 (pU6H1-LC3 siRNA and siLC3) and a dsRNA used as a Toll-like receptor 3 (TLR3) ligand was constructed and synthesized, respectively. Then, a human HCC ...[more]

PMID: 27338037

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Project description:Hedgehog (Hh) signaling plays an important role in embryonic development and in the regulation of a variety of cellular functions. Aberrant activation of Hh signaling has been implicated in several human cancers including hepatocellular carcinoma (HCC). In this study we examined the pathobiological functions and molecular mechanisms of the Hh signaling pathway in HCC cells. Treatment of cultured human HCC cells (Huh7, Hep3B, and HepG2) with the Hh signaling ligand (recombinant Shh) or agonist, SAG and purmorphamine, prevented the induction of autophagy. In contrast, GANT61 (a small molecule inhibitor of Gli1 and Gli2) induced autophagy, as determined by immunoblotting for microtubule-associated protein light chain 3 (LC3) and p62, GFP-LC3 puncta, monodansylcadaverine (MDC) staining, and transmission electron microscopy. Hh inhibition-induced autophagy was associated with up-regulation of Bnip3, as determined by immunoblotting and real-time polymerase chain reaction (PCR) assay. Knockdown of Bnip3 by RNAi impaired GANT61-induced autophagy. Additionally, Hh inhibition-induced autophagy was associated with Bnip3-mediated displacement of Bcl-2 from Beclin-1, as determined by immunoblotting and immunoprecipitation assays. Furthermore, inhibition of Hh signaling increased HCC cell apoptosis and decreased cell viability, as determined by caspase and WST-1 assays. Pharmacological or genetic inhibition of autophagy by 3-methyladenine (3-MA) or Beclin-1 small interfering RNA (siRNA) partially suppressed GANT61-induced cell apoptosis and cytotoxicity. In a tumor xenograft model using SCID mice inoculated with Huh7 cells, administration of GANT61 inhibited tumor formation and decreased tumor volume; this effect was partially blocked by the autophagy inhibitor, 3-MA.These findings provide novel evidence that Hh inhibition induces autophagy through up-regulation of Bnip3 and that this mechanism contributes to apoptosis. Therefore, the status of autophagy is a key factor that determines the therapeutic response to Hh-targeted therapies.

Project description:BACKGROUND:The role of autophagy-related markers as the prognostic factor of post-operative hepatocellular carcinoma (HCC) recurrence remained controversial. METHODS:Overall, 535 consecutive HCC patients undergoing curative resection from 2010 to 2014 were followed and classified with early (ER, <2 years) or late recurrence (LR). Autophagy-related markers, LC3, Beclin-1, and p62 expression was immunohistochemically assessed in HCC and adjacent non-tumor (ANT) tissues. RESULTS:HCC recurred in 245 patients: 116 with ER and 129 with LR. The cumulative incidence of recurrence at 1, 3, 5, and 7 years was 9.7%, 33.9%, 53.3%, and 66.3%, respectively. In multivariate analysis, HCC recurrence was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (hazard ratio/95% confidence interval: 6.12/2.473-17.53, 4.18/1.285-13.61, and 1.89/1.299-2.757) and macrovascular invasion (1.63/1.043-2.492) and cirrhosis (1.59/1.088-2.326). ER was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (6.54/2.934-15.81, 3.26/1.034-10.27, and 2.09/1.313-3.321) and macrovascular and microvascular invasion (2.65/1.306-5.343 and 2.55/1.177-5.504). LR was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (5.02/1.372-18.83, 3.19/1.13-12.09, and 1.66/1.051-2.620) and cirrhosis (1.66/1.049-2.631). Patients with low and high LC3 expression in tumor and ANT tissues showed a 5-year cumulative recurrence of 94.3% and 41.7%, respectively (p?<?0.001). CONCLUSIONS:The high LC3 expression in the tumor and liver microenvironments is significantly associated with lower HCC recurrence. Furthermore, tumor characteristics and liver microenvironment were also significantly associated with ER and LR, respectively. TRANSLATIONAL IMPACT:The analysis for LC3 expression in both the HCC and ANT tissues could identify patients at risk of HCC recurrence.

Dataset Information

Studying the Effect of Downregulating Autophagy-Related Gene LC3 on TLR3 Apoptotic Pathway Mediated by dsRNA in Hepatocellular Carcinoma Cells.

Publications

Studying the Effect of Downregulating Autophagy-Related Gene LC3 on TLR3 Apoptotic Pathway Mediated by dsRNA in Hepatocellular Carcinoma Cells.

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