Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Histone H2A variant H2AX is a dose-dependent suppressor of oncogenic chromosome translocations. H2AX participates in DNA double-strand break repair, but its role in other DNA repair pathways is not known. In this study, role of H2AX in cellular response to alkylation DNA damage was investigated. Cellular sensitivity to two monofunctional alkylating agents (methyl methane sulfonate and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)) was dependent on H2AX dosage, and H2AX null cells were more sensitive than heterozygous cells. In contrast to wild-type cells, H2AX-deficient cells displayed extensive apoptotic death due to a lack of cell-cycle arrest at G(2)/M phase. Lack of G(2)/M checkpoint in H2AX null cells correlated well with increased mitotic irregularities involving anaphase bridges and gross chromosomal instability. Observation of elevated poly(ADP) ribose polymerase 1 (PARP-1) cleavage suggests that MNNG-induced apoptosis occurs by PARP-1-dependent manner in H2AX-deficient cells. Consistent with this, increased activities of PARP and poly(ADP) ribose (PAR) polymer synthesis were detected in both H2AX heterozygous and null cells. Further, we demonstrate that the increased PAR synthesis and apoptotic death induced by MNNG in H2AX-deficient cells are due to impaired activation of mitogen-activated protein kinase pathway. Collectively, our novel study demonstrates that H2AX, similar to PARP-1, confers cellular protection against alkylation-induced DNA damage. Therefore, targeting either PARP-1 or histone H2AX may provide an effective way of maximizing the chemotherapeutic value of alkylating agents for cancer treatment.
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PMID:Histone H2AX is a critical factor for cellular protection against DNA alkylating agents. 1854 54

DNA has been identified as a primary target for anticancer drug design and remains one of the most promising biological receptors for the development of chemotherapeutic agents. We have previously demonstrated that ruthenium complex [Ru(bmbp)(phen)Cl]ClO(4) (RuBmP; bmbp = 2,6-bis(4-methylbenzimidazol-2-yl)pyridine) is a novel apoptosis-inducer by triggering mitochondria-mediated ROS overproduction in cancer cells. In the present work, the underlying mechanisms of the anticancer action of RuBmP were further elucidated by evaluating its DNA interaction properties and the regulating signalling pathways. Our results showed that RuBmP could effectively activate DNA strand breaks in A375 cells in a dose-dependent manner after cellular internalization. Phosphorylation of a DNA damage marker Histone H2A.X (Ser139) was thus up-regulated in treated cells. DNA damage subsequently activated p53 phosphorylation and inhibited the expression of Bcl-xL, resulting in activation of caspase-3, -8 and -9, and cleavage of poly(ADP-ribose) polymerase (PARP). The interactions between the complexes and cancer cell chromosomal and calf thymus DNA were characterized by UV-vis absorption, fluorescence intensity and viscosity measurements, which clearly demonstrated the intercalative binding of the complexes to DNA. Taken together, these results suggest that RuBmP, as a promising anticancer agent, induces cancer cell apoptosis by triggering DNA damage-mediated p53 phosphorylation.
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PMID:Ruthenium complexes containing 2,6-bis(benzimidazolyl)pyridine derivatives induce cancer cell apoptosis by triggering DNA damage-mediated p53 phosphorylation. 2296 64

The mechanistic target of Rapamycin (MTOR) protein is a crucial signaling regulator in mammalian cells that is extensively involved in cellular biology. The function of MTOR signaling in keratinocytes remains unclear. In this study, we detected the MTOR signaling and autophagy response in the human keratinocyte cell line HaCaT and human epidermal keratinocytes treated with MTOR inhibitors. Moreover, we detected the impact of MTOR inhibitors on keratinocytes exposed to the common carcinogenic stressors ultraviolet B (UVB) and UVA radiation. As a result, keratinocytes were sensitive to the MTOR inhibitors Rapamycin, everolimus, Torin 1, and pp242, but the regulation of MTOR downstream signaling was distinct. Next, autophagy induction only was observed in HaCaT cells treated with Rapamycin. Furthermore, we found that MTOR signaling was insensitive to UVB but sensitive to UVA radiation. UVB treatment also had no impact on the inhibition of MTOR signaling by MTOR inhibitors. Finally, MTOR inhibition by Rapamycin, everolimus, or pp242 did not affect the series of biological events in keratinocytes exposed to UVB, including the downregulation of BiP and PERK, activation of Histone H2A and JNK, and cleavage of caspase-3 and PARP. Our study demonstrated that MTOR inhibition in keratinocytes cannot always induce autophagy, and the MTOR pathway does not play a central role in the UVB triggered cellular response.
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PMID:Impact on Autophagy and Ultraviolet B Induced Responses of Treatment with the MTOR Inhibitors Rapamycin, Everolimus, Torin 1, and pp242 in Human Keratinocytes. 2840 Sep 12