Targeting PRMT5 enhances the radiosensitivity of tumor cells grown in vitro and in vivo.

PRMT5 is a widely expressed arginine methyltransferase that regulates processes involved in tumor cell proliferation and survival. In the study described here, we investigated whether PRMT5 provides a target for tumor radiosensitization. Knockdown of PRMT5 using siRNA enhanced the radiosensitivity of a panel of cell lines corresponding to tumor types typically treated with radiotherapy. To extend these studies to an experimental therapeutic setting, the PRMT5 inhibitor LLY-283 was used. Exposure of the tumor cell lines to LLY-283 decreased PRMT5 activity and enhanced their radiosensitivity. This increase in radiosensitivity was accompanied by an inhibition of DNA double-strand break repair as determined by γH2AX foci and neutral comet analyses. For a normal fibroblast cell line, although LLY-283 reduced PRMT5 activity, it had no effect on their radiosensitivity. Transcriptome analysis of U251 cells showed that LLY-283 treatment reduced the expression of genes and altered the mRNA splicing pattern of genes involved in the DNA damage response. Subcutaneous xenografts were then used to evaluate the in vivo response to LLY-283 and radiation. Treatment of mice with LLY-283 decreased tumor PRMT5 activity and significantly enhanced the radiation-induced growth delay. These results suggest that PRMT5 is a tumor selective target for radiosensitization.

Hydroxybenzamide derivatives protect pancreatic ß cell by suppressing unfolded protein response activation.

Endoplasmic reticulum (ER) stress-induced Pancreatic ß-cell dysfunction and death plays important roles in the development of diabetes. The 1,2,3-triazole derivative 1 is one of only a few structures that have thus far been identified that protect ß cells against ER stress, but it is limited for its narrow activity range. In this study, we designed and synthesized a series of hydroxybenzamide (HBA) derivatives in which the triazole pharmacophore was substituted with an amide linker. Structure-activity relationship studies identified WO3i (3-hydroxy-N-(4-[trifluoromethyl]benzyl)benzamide) that possesses ß-cell protective activity against ER stress at a 100% maximal activity with EC50 at 0.19 µM). We showed that WO3i suppresses the expression of CHOP, a key mediator of ER stress-induced apoptosis, and the activation of apoptotic genes. Mechanistically, we further showed that WO3i suppresses the ER stress-induced activation of all three pathways of unfolded protein response-ATF6, IRE1α, and PERK. Identification of this novel ß-cell-protective scaffold thus provides a new promising modality for the potential for drug development for the treatment of diabetes.

Sequence and phylogenetic analysis of the VP6 and NSP4 genes of human rotavirus strains: evidence of discordance in their genetic linkage.

NSP4 and VP6 genes of a total of 118 rotavirus strains detected in adolescent and adult cases of acute gastroenteritis (AGE) in 1993-1996 and 2004-2007 were characterized to determine their diversity and genetic linkage. Eighty-two percent and 89% of the strains showed amplification of NSP4 and VP6 genes respectively in RT-PCR. Sequencing and phylogenetic analysis of the VP6 genes showed distribution of genogroups in the lineages I-1 (1.4%), I-2 (50.7%) and II-4 (47.9%) in the 1990s and I-2 (73.5%) and II-4 (26.5%) in 2000s, indicating diversity in genogroups at both time points. Amino acid divergence within the genogroup II strains from 1990s and genogroup I strains from the 2000s was noteworthy (4.7-6.7%). Sequencing and phylogenetic analysis of the NSP4 genes showed almost equal distribution (45.0-55.0%) of genotypes A and B however, higher amino acid divergence within the genotype B strains (up to 9.3%) than in genotype A strains (up to 2.9%) at the two-time points. Nearly 70% of the strains showed NSP4-A-VP6-I or NSP4-B-VP6-II genetic linkage. The discordance in the linkage noted in 29.7% of the strains was predominated by NSP4-B and VP6-I combination and appeared strikingly high in the infections caused by unusual and mixed rotavirus strains. This is the first report to describe the phylogenetic analysis of rotavirus NSP4 and VP6 genes and their discordance in adolescent and adult cases with AGE from India. The extensive diversity within the rotavirus genes and their relationship revealed by this study emphasizes the need for evaluation of the rotavirus vaccines being used currently.