Therapeutic biology: Checkpoint pathway activation therapy, HIV Tat, and transkingdom RNA interference

Synthesis and antitumor activity of selenium-containing quinone-based triazoles possessing two redox centres, and their mechanistic insights

Selenium-containing quinone-based 1,2,3-triazoles were synthesized using click chemistry, the copper catalyzed azide-alkyne 1,3-dipolar cycloaddition, and evaluated against six types of cancer cell lines: HL-60 (human promyelocytic leukemia cells), HCT-116 (human colon carcinoma cells), PC3 (human prostate cells), SF295 (human glioblastoma cells), MDA-MB-435 (melanoma cells) and OVCAR-8 (human ovarian carcinoma cells). Some compounds showed IC50 values < 0.3 μM. The cytotoxic potential of the quinones evaluated was also assayed using non-tumor cells, exemplified by peripheral blood mononuclear (PBMC), V79 and L929 cells. Mechanistic role for

NAD(P)H

Quinone Oxidoreductase 1 (NQO1) was also elucidated. These compounds could provide promising new lead derivatives for more potent anticancer drug development and delivery, and represent one of the most active classes of lapachones reported.

High-Content Fluorescent-Based Assay for Screening Activators of DNA Damage Checkpoint Pathways

Activation of DNA damage checkpoint pathways, including Chk2, serves as an anticancer barrier in precancerous lesions. In an effort to identify small-molecule activators of Chk2, the authors developed a quantitative cell-based assay using a high-content analysis (HCA) platform. Induction of phosphorylated Chk2 was evaluated using several different parameters, including fold induction, Kolmogorov-Smirnov score, and percentage of positively stained cells. These measurements were highly correlated and provided an accurate method for compound ranking/binning, structure-activity relationship studies, and lead identification. Screening for Chk2 activators was undertaken with a target-focused library and a diversified library from ArQule chemical space. Several compounds exhibited submicromolar EC 50 values for phosphorylated Chk2 induction. These compounds were further analyzed for Chk2-dependent cytotoxicity, as assessed through a high-content cell death assay in combination with siRNA silencing of Chk2 expression. Several compounds were identified and showed specific inhibition or lethality in a target-dependent manner. Therefore, identification of DNA damage checkpoint pathway activators by HCA is an attractive approach for discovering the next generation of targeted cancer therapeutics. ( Journal of Biomolecular Screening 2008:538-543)

RNA interference and its therapeutic potential against HIV infection

BACKGROUND

HIV-1 infection is the major cause of AIDS. RNA interference (RNAi) has great potential to work as a powerful tool against HIV infection. Therefore, the possibilities of use of siRNA (small-interfering RNA) as a tool to deal with HIV infection are discussed in this article.

OBJECTIVE

Highly active anti retroviral therapy (HAART) has been successful in reducing the rate of progression to AIDS, but HIV utilizes various tricks to escape from the inhibitory effect of HAART. Therefore, new tools are required to delay progression of infection or block the replication cycle of HIV.

METHODS

This article has been written on the basis of informations available in the form of published literature in various journals.

CONCLUSION

RNAi is a very promising strategy that in principle will provide many new targets against HIV infection. The mechanism of sequence complementarity utilized by siRNAs against their targets provides a new approach to fight against HIV infection. However, this technology still needs many fine refinements before its potential for HIV treatment strategies can be utilized. This review discusses the possibilities of using siRNA as a therapeutic tool for HIV treatment.