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

The Role of Autophagy in Liver Cancer: Crosstalk in Signaling Pathways and Potential Therapeutic Targets

Autophagy is an evolutionarily conserved lysosomal-dependent pathway for degrading cytoplasmic proteins, macromolecules, and organelles. Autophagy-related genes (Atgs) are the core molecular machinery in the control of autophagy, and several major functional groups of Atgs coordinate the entire autophagic process. Autophagy plays a dual role in liver cancer development via several critical signaling pathways, including the PI3K-AKT-mTOR, AMPK-mTOR, EGF, MAPK, Wnt/β-catenin, p53, and NF-κB pathways. Here, we review the signaling pathways involved in the cross-talk between autophagy and hepatocellular carcinoma (HCC) and analyze the status of the development of novel HCC therapy by targeting the core molecular machinery of autophagy as well as the key signaling pathways. The induction or the inhibition of autophagy by the modulation of signaling pathways can confer therapeutic benefits to patients. Understanding the molecular mechanisms underlying the cross-link of autophagy and HCC may extend to translational studies that may ultimately lead to novel therapy and regimen formation in HCC treatment.

Bioactivity Guided Fractionation and Elucidation of Anti-Cancer Properties of Imperata Cylindrica Leaf Extracts

BACKGROUND

In our earlier study, we reported the anticancer effect of methanolic extracts of, I. cylindrica leaf (ICL) against human oral squamous cell carcinoma cell lines SCC-9. The cytotoxic effect of ICL methanolic extract was specific to the cancer cells and not to the normal cells. The present study aimed to fractionate the ICL methanolic extract to derive anticancer bioactives.

METHODS

The ICL methanolic extract was subjected to a bioactivity guided fractionation. Cytotoxic, cell cycle inhibitory, apoptosis and caspase gene expression inducing activity of the active fractions were evaluated using MTT assay, FACS analysis, Annexin V binding assay and RT-PCR respectively.

RESULTS

The hexane fraction of ICL methanolic extract (ICLH) was observed to be the most bioactive fraction. It was shown to possess effective cytotoxic and cell cycle inhibitory activities against SCC-9 cells. The hexane fraction also induced apoptosis in SCC-9 cells which was further established at the level of caspase 3 and 8 gene expressions.

CONCLUSION

Overall, the results clearly establish the potential of ICLH extract to inhibit cell proliferation and induce apoptosis in the SCC-9 cells. Further analysis of the ICLH fraction could result in development of effective anticancer therapeutics. The natural abundance of I. cylindrica with its wide geographic distribution could make it a preferred natural resource for obtaining novel, cost-effective, anticancer therapeutics with minimal systemic side effects.

Toll-like receptor 3 (TLR3) functions as a pivotal target in latent membrane protein 1 (LMP1)-mediated nasopharyngeal carcinoma cell proliferation

Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) activation of NF-κB is pivotal for EBV-infected B lymphocyte survival. Herein, we found that LMP1 markedly rescued the suppressed the proliferation of several nasopharyngeal carcinoma (NPC) cell lines caused by a Toll-like receptor 3 (TLR3) ligand poly (I:C). We profiled the expression alterations of TLR3 and LMP1 within these NPC cell lines in response to poly (I:C) treatment, and found a high correlation between them ws found, suggesting potential involvement of TLR3 in LMP1 signaling. Then, cells deficient in TLR3 were used to assess its role in poly (I:C)-induced inhibition of cell proliferation and LMP1-mediated NF-κB activation. NF-κB p65 activation and the consequent pro-inflammatory responses were unresponsive to poly (I:C) stimulation after TLR3 knockdown (KD), and NOS2 and MMP9 were substantially suppressed in CNE1-745, but nearly normal in LMP1-overexpressed CNE1-LMP1-745 cells. This suggests an alternative pathway that LMP1 may depend on, in terms of NOS2 and MMP9 regulation, whereas an unusual TLR3-dependent expression of c-Myc was identified. Consistently, poly (I:C)-induced retarded growth was reversed by TLR3 silencing, which was especially enhanced in LMP1-overexpressed cells. TLR3 is essential for poly (I:C)-incited NPC cell death, and occupies a critical role in LMP1-mediated NF-κB activation. Our findings provide new insight into the mechanism underlying LMP1-involved EBV-associated pathogenesis of refractory NPC, thereby potentially improving treatment outcome.

Effects of Triple Effective RNA (teRNA) on the Inhibition of Hepatocellular Carcinoma Cells

The occurrence and development of hepatocellular carcinoma (HCC) is a complicate process involved in genetic mutation and epigenetic regulation. Successful HCC therapy needs multi-targets be involved. The aim of this study was to provide a triple effective RNA (teRNA) which composed of the specific siRNAs targeting NET-1 and VEGF and dsRNA activating TLR3, and explored its anti-HCC roles and mechanism. Real-time quantitative PCR (RT-qPCR), Western blot, immunofluorescence staining, MTT, Annexin V-FITC flow cytometry, Transwell and in-vitro Angiogenesis assay were used to measure the cell biological functions and protein expression analysis. Furthermore in in-vivo mouse model, teRNA inhibited tumor growth were detected by immunohistochemistry and TUNEL assay. Results showed that the proliferation, migration and angiogenesis of HCC cells were inhibited by teRNA effectively, the cell apoptosis also was induced, and further tumor growth was suppressed in-vivo. The gene silencing mechanism of teRNA was in an Ago2-dependent manner with no interferon response. The study suggests that NET-1, VEGF and TLR3 might be better targets for HCC treatment and combined these targets in form of a multi-target small RNA, teRNA could be a stagey for the development of anti-HCC drugs.

Up-regulation of miR-146a increases the sensitivity of non-small cell lung cancer to DDP by downregulating cyclin J

Background

Cisplatin (DDP)-based chemotherapy is the common first-line therapy for lung cancer. However, their efficacy is often limited by primary drug resistance and/or acquired drug resistance. The aim of this study was to investigate the function of miRNA-146a (miR-146a) in DDP-resistant non-small cell lung cancer (NSCLC), as well as the underlying mechanisms.

Methods

The effect of overexpression of miR-146a and/or knockdown of cyclin J (CCNJ) in A549/DDP and SPC-A1/DDP cells were investigated as follows. The cellular sensitivity to DDP, cell apoptosis, cell cycle and cell mobility were detected by CCK-8, flow cytometry, hoechst staining and cell invasion/migration assay, respectively. The effects of miR-146a overexpression in NSCLC resistant cells were further analyzed in a nude mouse xenograft model.

Results

Overexpression of miR-146a and/or knockdown of CCNJ significantly increased the sensitivity to DDP in A549/DDP and SPC-A1/DDP cells compared to NC group via arresting cell cycle, enhancing cell apoptosis, inhibiting cell viability and motility in vitro and in vivo. Furthermore, miR-146a could specially degrade the mRNA of CCNJ, as examined by dual luciferase report assay.

Conclusion

The study indicates a crucial role of miR-146a in the development of acquired drug resistance to DDP in NSCLC cells. Further understanding of miR-146a mediated crosstalk networks may promote the clinical use of miR-146a analogue in NSCLC therapy.

The apoptotic effect of 1'S-1'-Acetoxychavicol Acetate (ACA) enhanced by inhibition of non-canonical autophagy in human non-small cell lung cancer cells

Autophagy plays a role in deciding the fate of cells by inducing either survival or death. 1’S-1-acetoxychavicol acetate (ACA) is a phenylpropanoid isolated from rhizomes of Alpinia conchigera and has been reported previously on its apoptotic effects on various cancers. However, the effect of ACA on autophagy remains ambiguous. The aims of this study were to investigate the autophagy-inducing ability of ACA in human non-small cell lung cancer (NSCLC), and to determine its role as pro-survival or pro-death mechanism. Cell viability assay was conducted using MTT. The effect of autophagy was assessed by acridine orange staining, GFP-LC3 punctate formation assay, and protein level were analysed using western blot. Annexin V-FITC/PI staining was performed to detect percentage of cells undergoing apoptosis by using flow cytometry. ACA inhibits the cell viability and induced formation of cytoplasmic vacuoles in NSCLC cells. Acidic vesicular organelles and GFP-LC3 punctate formation were increased in response to ACA exposure in A549 and SK-LU-1 cell lines; implying occurrence of autophagy. In western blot, accumulation of LC3-II accompanied by degradation of p62 was observed, which further confirmed the full flux of autophagy induction by ACA. The reduction of Beclin-1 upon ACA treatment indicated the Beclin-1-independent autophagy pathway. An early autophagy inhibitor, 3-methyaldenine (3-MA), failed to suppress the autophagy triggered by ACA; validating the existence of Beclin-1-independent autophagy. Silencing of LC3-II using short interfering RNA (siRNA) abolished the autophagy effects, enhancing the cytotoxicity of ACA through apoptosis. This proposed ACA triggered a pro-survival autophagy in NSCLC cells. Consistently, co-treatment with lysosomal inhibitor, chloroquine (CQ), exerted a synergistic effect resulting in apoptosis. Our findings suggested ACA induced pro-survival autophagy through Beclin-1-independent pathway in NSCLC. Hence, targeting autophagy pathway using autophagy inhibitor such as CQ represented a novel promising approach to potentiate the cytotoxicity of ACA through apoptosis in NSCLC.