Background:Poly(ADP-ribosyl)ation (PARylation) catalyzed mainly by PARP1 is a highly regulated posttranslational modification associated with several pathways in cellular physiology and genotoxic deoxyribonucleic acid (DNA) damage response. PAR polymers and PARP enzyme function in DNA integrity maintenance and several PARP inhibitors have entered clinical phase studies for cancer therapies.Material and methods:The effect of bosutinib, a dual Src/Abl kinase inhibitor, on PARylation was fluorometrically measured. The cytotoxic and chemosensitizing effects were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of DNA repair proteins and PARP enzyme were examined by immunoblotting.Results:In this study, bosutinib is characterized as a novel PARP inhibitor. Bosutinib inhibited oxidative stress-induced cellular PARylation and nuclear foci formation by downregulating PARP1 levels. Bosutinib was found to be more cytotoxic on Capan1 cells with BRCA2 mutation. Furthermore by acting as a chemosensitizer, bosutinib enhanced the cytotoxicity of doxorubicin (DOXO) and etoposide (ETP) by decreasing phosphorylation of DNA repair enzymes checkpoint kinase 1 (Chk1) and ataxia-telangiectasia mutated (ATM).Conclusion:By inhibition of both PARP and DNA damage checkpoint kinases, bosutinib increased the phospho-H2AX levels, an early indicator of DNA double strand breaks.

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Endoplasmic reticulum-associated degradation (ERAD) is a well-characterized mechanism of protein quality control by removal of misfolded or unfolded proteins. The tight regulation of ERAD is critical for protein homeostasis as well as lipid metabolism. Although the mechanism is complex, all ERAD branches converge on p97/VCP, a key protein in the retrotranslocation step. The multifunctionality of p97/VCP relies on its multiple binding partners, one of which is the endogenous ERAD inhibitor, SVIP (small VCP-interacting protein). As SVIP is a promising target for the regulation of ERAD, we aimed to assess its novel physiological roles. We revealed that SVIP is highly expressed in the rat adrenal gland, especially in the cortex region, at a consistently high level during postnatal development, unlike the gradual increase in expression seen in developing nerves. Steroidogenic stimulators caused a decrease in SVIP mRNA expression and increase in SVIP protein degradation in human adrenocortical H295R cells. Interestingly, silencing of SVIP diminished cortisol secretion along with downregulation of steroidogenic enzymes and proteins involved in cholesterol uptake and cholesterol biosynthesis. A certain degree of SVIP overexpression mainly increased the biosynthesis of cortisol as well as DHEA by enhancing the expression of key steroidogenic proteins, whereas exaggerated overexpression led to apoptosis, phosphorylation of eIF2α, and diminished adrenal steroid hormone biosynthesis. In conclusion, SVIP is a novel regulator of adrenal cortisol and DHEA biosynthesis, suggesting that alterations in SVIP expression levels may be involved in the deregulation of steroidogenic stimulator signaling and abnormal adrenal hormone secretion.

The hydrazones of 4-hydrazinylpyridinium bearing alkylphenyl groups on pyridinium nitrogen were synthesized and evaluated for their cytotoxic activity against MCF-7, PC3, U2OS, and HEK293 cell lines by Wst1 cell proliferation assay. Cytotoxic activity results indicated that d derivatives having butylene chain; 4 and 5 series having naphthalene and anthracene ring systems showed high cytotoxic activity (IC = 3.27-8.54 μm) on cancer cells. 3d (4-(2-(4-hydroxybenzylidene)hydrazinyl)-1-(4-phenylbutyl)pyridinium bromide) was the most cytotoxic compound with IC value of 3.27 μm against MCF-7. The most active derivatives (1d, 2d, 3d, 4, and 5 series) were selected to investigate for the effects on autophagy by analyzing the expression of autophagy marker proteins. The conversion of LC3-I to its lipidated form LC3-II is essential for autophagy and related to autophagosomes. According to our results, all tested compounds except for 3d induced lipidated form LC3-II accumulation. Then, the effects of the compounds on p62 protein level were also analyzed by the immunoblotting as the autophagy inhibition results in accumulation of p62. Further molecular mechanistic studies including morphological analysis and live-death assays indicated that all tested compounds (1d, 2d, 3d, 4, and 5 series) are potent antitumoral molecules and all except for 3d have potential to inhibit autophagic flux.

Poly (ADP-ribose) polymerase (PARP) enzyme catalyzes the transfer of ADP-ribose into target proteins.Therefore, PARP is responsible for DNA repair, cell proliferation, and cell death. In this study, potential PARP enzyme inhibitors were designed and synthesized. The synthesized compounds were elucidated by Fourier-transform infrared spectroscopy, 1 H NMR, 13 C NMR, heteronuclear single-quantum correlation, and mass spectrometry, and their purity was checked via thin-layer chromatography, high-performance liquid chromatography, and elemental analysis. A total of 63 newly synthesized compounds were screened in terms of PARP inhibition by cellular PARylation assay in the HeLa cell line. It was found that 19 compounds significantly inhibited the H 2 O 2 -induced cellular PARylation. The chemosensitizer effect of these compounds in cancer cells treated with doxorubicin (doxo) was investigated. It was found that the combination of potent PARP inhibitors with doxo potentiated a cytotoxic effect, similar to that of olaparib. The results of the molecular docking and absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis revealed that compound 60 might be classified as a potential PARP inhibitor candidate. Taken together, all of the results suggested that carbohydrazide derivatives could be a promising lead for the treatment for cancer disorders.