Ur raw and normalized microarray information is publically available at the Gene Expression Omnibus database

in Juvenile Rats May Expression of NES-hTERT in Cancer Cells Delays Cell Cycle Progression and Increases Sensitivity to Genotoxic Stress Olga A. Kovalenko Abstract Telomerase is a reverse transcriptase associated with cellular immortality through telomere maintenance. This enzyme is activated in Citation: Kovalenko OA, Kaplunov J, Herbig U, deToledo S, Azzam EI, et al. Expression of NES-hTERT in Cancer Cells Delays Cell Cycle Progression and Increases Sensitivity to Genotoxic Stress. PLoS ONE Introduction these approaches is that several weeks to months are required for the effects as they mostly rely on extensive telomere shortening. Nonetheless, telomerase inhibitors are currently in clinical trials. We have recently shown that a mutant hTERT defective in its nuclear export signal failed to maintain telomeres and "healthy"mitochondria in both primary and SVMay NES-hTERT Impacts Cell Cycle cancer cells and sensitized at least one type of cancer cells to both oxidative stress and c-radiation. Taken together, our results suggest targeting the NES of hTERT or its intracellular movement as a novel strategy to effectively counteract tumor cell growth. Results Overexpression of NES-hTERT in skin and prostate cancer cell lines rapidly blocks cell cycle progression Interestingly, no change in cell number was detected for the first NES-hTERT. Overexpression of NES-hTERT in skin and prostate cancer cells decreases colony formation potential in vitro A number of transformations are required for cells to become tumorigenic, including increased growth rate and ability to grow in an anchorage-independent manner. The ability of transformed cells to form colonies in soft agar is a useful in vitro predictor of tumor formation in vivo. We sought to investigate whether the observed effects on proliferation rate after introduction of NES-hTERT in skin and prostate cancer cells would impact their ability to form colonies in soft agar. To this end, we plated equal number of SQMay NES-hTERT Impacts Cell Cycle May NES-hTERT Impacts Cell Cycle formed in weeks Expression of NES-hTERT does not alter the endogenous levels of telomerase enzymatic activity but increases the levels of telomeric and extra-telomeric DNA damage Ectopic expression of a catalytically inactive mutant hTERT that behaved as a dominant negative was shown to efficiently inhibit telomerase enzymatic activity, leading to telomere erosion and decreased proliferation of various cancer cell types. Increased spontaneous apoptosis, decreased colony growth in soft agar and diminished tumor formation in nude mice were also observed. Although NES-hTERT is enzymatically active in vitro, it is unable to elongate telomeres in vivo. Thus, it is possible that in the telomerase-positive SQ mutant. However, no changes in telomerase enzymatic activity were observed by expression of the mutant protein as judged by TRAP, indicating that NES-hTERT does not exert a dominant negative effect upon the endogenous protein at least in terms of enzymatic activity. In telomerase negative fibroblasts, expression of NES-hTERT leads to telomeric and extra-telomeric DNA damage. Thus, another possible explanation for the decrease in proliferation rate is that NES-hTERT induces DNA damage in the cancer cells, which in turn slows down their ability to progress through the cell cycle. We tested this In the very last decades, the PV interfacing systems gained a fantastic deal of consideration hypothesis by evaluating the presence of the phosphorylated form of the histone H May NES-hTERT Impacts Cell Cycle lesions reflects