Targeting MYC and HDAC8 with a Combination of siRNAs Inhibits Neuroblastoma Cells Proliferation In Vitro and In Vivo Xenograft Tumor Growth

HDAC8, c MYC and MYCN are involved in the tumorigenesis of neuroblastoma. A mouse Neuroblastoma (NB) tumor model was used to understand the role of miRNA, miR-665 in NB tumorigenesis and cellular differentiation. During cellular differentiation of NB cells there is an up regulated miRNA-665. We found that HDAC 8, c MYC and MYCN are the direct targets of mimic miR-665 which was validated by luciferase reporter plasmid with 3’ UTR and ELISA. Mimic miR-665 inhibited cell proliferation, arrested cells in G1 stage and decreased S Phase in cell cycle. miR-665 increased the acetylation of histones and activated Caspase 3. This is the first report to recognize miRNA 665 as a suppressor miRNA of NB. The effects of miR-665 were confirmed with the transfection of siRNA for HDAC8 and siRNA for MYC. Individual siRNA- HDAC8 or siRNA-MYC inhibited 40–50% of cell proliferation in vitro, however, the treatment with the combination of both siRNA-MYC + siRNA- HDAC8 inhibited 86% of cell proliferation. Indicating that both the targets c MYC and HDAC 8 should be reduced to obtain a significant inhibition of cell proliferation. Intratumoral treatment of xenograft tumors in mice with the combination of siRNA-MYC + siRNA- HDAC8 reduced the levels of target c-MYC protein by 64% and target HDAC 8 protein by 85% and the average tumor growth reduced by 80% compared to control tumors treated with NC-siRNA. Our results suggest the potential therapeutic effect of suppressor miR-665 and the combination of siRNA-MYC + siRNA-HDAC8 for neuroblastoma treatment.

Targeting Myc and Hdac8 with a Combination of SiRNAs Inhibits Tumor Growth in a Murine Neuroblastoma Xenograft Model

Neuroblastoma is a common tumor of the peripheral nervous system in children. Highly aggressive MYC-drivenneuroblastoma is defined by increased MYC and/or MYCN expression. HDAC8 overexpression is associated with advanced neuroblastoma. Previously, we have demonstrated that transient knockdown of both Myc and Hdac8 using siRNA significantly suppressed neuroblastoma cells proliferation compared to knockdown of either target in vitro. In this study, we further investigated whether combinational targeting Myc and Hdac8 in neuroblastoma xenograft mice model is consistent with our previous findings. Intratumoral treatment with siRNA-MYC and siRNA-HDAC8 reduced the levels of the target MYC protein by 64% and HDAC8 by 85%; in addition, we found that the average tumor growth was reduced by 80% compared to that of control tumors treated with NC-siRNA. Our results suggest the potential therapeutic effect of the combination of siRNA-MYC and siRNA-HDAC8 for neuroblastoma treatment.

Evaluation of the antifibrotic potency by knocking down SPARC, CCR2 and SMAD3

The genes of SPARC, CCR2, and SMAD3 are implicated in orchestrating inflammation and fibrosis in scleroderma and other fibrotic disorders. Aim of the studies was to examine synergistic effect of inhibition of these genes in treating fibrosis. The peptide nanoparticles were used to deliver the siRNAs in bleomycin-induced fibrotic mice. Triple combination of siRNAs targeting on Sparc, Ccr2 and Smad3 achieved favorable anti-inflammatory and anti-fibrotic effects. Inhibition of inflammation was evidenced by reduced inflammatory cells and proinflammatory cytokines in the BALF and/or the tissues. Activation of fibroblasts was suppressed in mouse tissues in which α-Sma and collagens were significantly reduced. Aberrant expression of the genes in fibroblasts, monocytes/macrophage, endothelial and epithelial cells were reinstalled after the treatment. In addition, transcriptome profiles indicated that some bleomycin-induced alterations of multiple biological pathways were recovered to varying degrees by the treatment. The results indicated that the triple combination of siRNAs systemically reinstated multiple biopathways, probably through controlling on different cell types including fibroblasts, monocytes/macrophages, endothelial cells and others. The multi-target-combined therapeutic approach examined herein may represent a novel and effective therapy for fibrosis.

Combinations of siRNAs against La Autoantigen with NS5B or hVAP-A Have Additive Effect on Inhibition of HCV Replication

Hepatitis C virus is major cause of chronic liver diseases such as chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Presently available direct-acting antiviral drugs have improved success rate; however, high cost limits their utilization, especially in developing countries like India. In the present study, we evaluated anti-HCV potential of several siRNAs targeted against the HCV RNA-dependent RNA polymerase NS5B and cellular factors, La autoantigen, PSMA7, and human VAMP-associated protein to intercept different steps of viral life cycle. The target genes were downregulated individually as well as in combinations and their impact on viral replication was evaluated. Individual downregulation of La autoantigen, PSMA7, hVAP-A, and NS5B resulted in inhibition of HCV replication by about 67.2%, 50.7%, 39%, and 52%, respectively. However, antiviral effect was more pronounced when multiple genes were downregulated simultaneously. Combinations of siRNAs against La autoantigen with NS5B or hVAP-A resulted in greater inhibition in HCV replication. Our findings indicate that siRNA is a potential therapeutic tool for inhibiting HCV replication and simultaneously targeting multiple viral steps with the combination of siRNAs is more effective than silencing a single target.