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

다국어 초록 (Multilingual Abstract)

Purpose 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.

Materials and Methods 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.

Results 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).

Conclusion 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.

참고문헌 (Reference)

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