Multispecies-compatible antitumor effects of a cross-species small-interfering RNA against mammalian target of rapamycin.

Successful development of sequence-specific siRNA (small interfering RNA)-based drugs requires an siRNA design that functions consistently in different organisms. Utilizing the CAPSID program previously developed by our group, we here designed siRNAs against mammalian target of rapamycin (mTOR) that are entirely complementary among various species and investigated their multispecies-compatible gene-silencing properties. The mTOR siRNAs markedly reduced mTOR expression at both the mRNA and protein levels in human, mouse, and monkey cell lines. The reduction in mTOR expression resulted in inactivation of both mTOR complex I and II signaling pathways, as confirmed by reduced phosphorylation of p70S6K (70-kDa ribosomal protein S6 kinase), 4EBP1 (eIF4E-binding protein 1), and AKT, and nuclear accumulation of FOXO1 (forkhead box O1), with consequent cell-cycle arrest, proliferation inhibition, and autophagy activation. Moreover, interfering with mTOR activity in vivo using mTOR small-hairpin RNA-expressing recombinant adeno-associated virus led to significant antitumor effects in xenograft and allograft models. Thus, the present study demonstrates that cross-species siRNA successfully silences its target and readily produces multispecies-compatible phenotypic alterations-antitumor effects in the case of mTOR siRNA. Application of cross-species siRNA should greatly facilitate the development of siRNA-based therapeutic agents.

Clevudine demonstrates potent antiviral activity in naïve chronic hepatitis B patients.

OBJECTIVES: Clevudine has demonstrated antiviral potency in the treatment of naïve chronic hepatitis B patients in pivotal studies. The objectives of this study were to evaluate the safety and efficacy of a 1-year treatment with clevudine in chronic hepatitis B patients. METHODS: This is a post-marketing surveillance using case report forms which were submitted to the health authorities. RESULTS: Analysis of individual data showed that hepatitis B virus (HBV) DNA after a 1-year treatment was <141,500 copies/ml in 96% of hepatitis B e antigen (HBeAg)-positive and 100% of HBeAg-negative patients. The proportion of patients with HBV DNA <2,000 copies/ml after a 1-year treatment was 74%: 71% of HBeAg-positive and 93% of HBeAg-negative patients. Most of the patients with HBV DNA below the detection limit with each assay at week 24 showed sustained viral suppression up to week 48. The proportion of patients who showed normal alanine aminotransferase at week 48 was 86% in HBeAg-positive patients and 87% in HBeAg-negative patients. The rates of HBeAg-loss were 21%. Two patients showed viral breakthrough during treatment. CONCLUSION: Clevudine monotherapy demonstrates potent antiviral activity as well as biochemical and serological response with a 0.7% rate of viral breakthrough in naïve chronic hepatitis B patients.

Antiviral protection against enterovirus 71 mediated by autophagy induction following FLICE-inhibitory protein inactivation.

Even with the recent awareness of enterovirus 71 (EV71) as a major public health issue, there are no preventive or therapeutic agents that are effective against EV71 infection. Although FLICE-like inhibitory protein (FLIP) has been identified as a factor that modulates virus pathogenesis, there are no reports regarding its effects on EV71 infection. The aim of the present study was to identify whether FLIP influences EV71 pathogenesis and to understand the underlying mechanisms. Virus replication was markedly reduced in MRC5 cells preincubated with anti-FLIP peptides, and infected cells were rescued from the cytopathic effects of the virus. The anti-FLIP peptides induced autophagy by disrupting intrinsic FLIP functions. The antiviral activity of these peptides was reduced when autophagy was inhibited by treatment with siRNA targeted to beclin-1. Thus, the present study provides evidence that anti-FLIP peptides induce autophagy by inactivating cFLIP, and that this is associated with antiviral effects against EV71.