School Of Basic And Applied Sciences

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Subject: search.filters.subject.Cell Proliferation

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Now showing 1 - 4 of 4
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    Screening and biological evaluation of myricetin as a multiple target inhibitor insulin, epidermal growth factor, and androgen receptor; In silico and in vitro
    (Springer New York LLC, 2015) Singh, Pushpendra; Bast, Felix
    Myricetin is a naturally omnipresent benzo-?-pyrone flavonoids derivative; has potent anticancer activity. Receptor tyrosine kinases family provides the decisive role in cancer initiation and progression. These receptors have recently caught the attention of the researchers as an attractive target to combat cancer, owing to the evidences endorsed their over-expression on cancer cells. This study is a concerted effort to explore the potent and specific multi-targeted inhibitor against RTKs and AR\ER employing molecular docking approach. IR, IGF1R, EGFR, VEGFR1, VEGFR2, and AR\ER were chosen as a protein and natural compounds as a ligand. Molecular docking procedure followed by using Maestro 9.6 (Schr?dinger Inc). All natural compounds were docked with the X-ray crystal structures of selected proteins by employing grid-based ligand docking with energetics Maestro 9.6. IBS natural compounds docked with each selected protein molecules by using GLIDE high throughput virtual screening. On the basis of Gscore, we selected 20 compounds from IBS (50,000 compounds) along with 68 anticancer compounds from published literature for GLIDE extra precision molecular docking. Calculated docking free energy yielded the excellent dock score for the myricetin when docked with proteins EGFR, IR, and AR\ER. Protein-ligand interactions profile highlighted that the lipophilic, hydrogen bonding and ?-? stacking interactions play a central role in protein-ligand interactions at the active site. The results of MTT assay reveal that the myricetin inhibit the viability and proliferation of cancer cells in a dose-dependent manner. Treatment with the myricetin led to down-regulation of mRNA expression of EGFR, IR, mTOR, and Bcl-2. Although, further in vitro and in vivo experimental studies are required for the experimental validation of our findings. ? 2015 Springer Science+Business Media New York.
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    High-throughput virtual screening, identification and in vitro biological evaluation of novel inhibitors of signal transducer and activator of transcription 3
    (Birkhauser Boston, 2015) Singh, Pushpendra; Bast, Felix
    Signal transducer and activator of transcription (STAT) family, encompassing protein molecules that function as a second messenger and transcription factor, are famously known to regulate a multitude of cellular processes including inflammation, cell proliferation, invasion, angiogenesis, metastasis and immune system homeostasis. STAT3 is one of the six members of a family of transcription factors. STAT3 has proved themselves to be interesting candidates for anticancer therapy as they are over-expressed in most cancer cells. Thus, we studied receptor-based molecular docking of STAT3 against natural compounds and further validations of lead molecules in an array of cancer cells. In the present study, we screened approximately 50,000 natural compounds from the IBS. All natural compounds were docked with the X-ray crystal structure of STAT3 (PDB; 1BG1) retrieved from the protein data bank by using Maestro 9.6 (Schr?dinger Inc). First, we performed high-throughput virtual screening of IBS against the SH2 domain of STAT3. Further, best 20 compounds that possess minimal Gscore along with 85 natural compounds that had been reported in published literature as having anticancer properties were selected, and molecular docking was performed using the XP (extra precision) mode of GLIDE. We analyzed Gscore and protein-ligand interactions of top ranking compounds. It was discovered in this study, compounds CID252682, CID5281670 (Morin), CID5281672 (Myricetin), CID72277 (Epigallocatechol) and CID65064 (Epigallocatechin Gallate, EGCG) yielded the excellent dock score with the STAT3 concluded with the help of docking-free energy. Moreover, IBS STOCK1N-43090, STOCK1N-66505, STOCK1N-54303, STOCK1N-44634, STOCK1N-45027, STOCK1N-73784, STOCK1N-69597, STOCK1N-73062, STOCK1N-81915 and STOCK1N-70844 have better docking-free energy. Further, we chose EGCG and myricetin compounds, and their effect on biological activity such as cell proliferation, oxidative stress, colony formation, mRNA expression of STAT3, and cell number was reported after the 48 h treatments in cancer cell lines. EGCG and myricetin reduce the STAT3 mRNA expression confirmed by RTPCR. Moreover, EGCG and myricetin reduce cell proliferation and ROS generation after 48 h treatments. Interestingly, our result also indicates that the reduction in potential for colony formation enhances anti-metastasis activity of EGCG and myricetin. The information obtained from our study assisted us in drawing a more lucid picture regarding the existence STAT3 natural compounds inhibitor on diverse cancer cells. ? 2015 Springer Science+Business Media.
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    Elevated level of acetylation of APE1 in tumor cells modulates DNA damage repair
    (Impact Journals LLC, 2016) Sengupta, S.; Mantha, Anil K.; Song, H.; Roychoudhury, S.; Nath, S.; Ray, S.; Bhakat, K.K.
    Apurinic/apyrimidinic (AP) sites are frequently generated in the genome by spontaneous depurination/depyrimidination or after removal of oxidized/modified bases by DNA glycosylases during the base excision repair (BER) pathway. Unrepaired AP sites are mutagenic and block DNA replication and transcription. The primary enzyme to repair AP sites in mammalian cells is AP endonuclease (APE1), which plays a key role in this repair pathway. Although overexpression of APE1 in diverse cancer types and its association with chemotherapeutic resistance are well documented, alteration of posttranslational modification of APE1 and modulation of its functions during tumorigenesis are largely unknown. Here, we show that both classical histone deacetylase HDAC1 and NAD+-dependent deacetylase SIRT1 regulate acetylation level of APE1 and acetylation of APE1 enhances its AP-endonuclease activity both in vitro and in cells. Modulation of APE1 acetylation level in cells alters AP site repair capacity of the cell extracts in vitro. Primary tumor tissues of diverse cancer types have higher level of acetylated APE1 (AcAPE1) compared to adjacent non-tumor tissue and exhibit enhanced AP site repair capacity. Importantly, in the absence of APE1 acetylation, cells accumulate AP sites in the genome and show increased sensitivity to DNA damaging agents. Together, our study demonstrates that elevation of acetylation level of APE1 in tumor could be a novel mechanism by which cells handle the elevated levels of DNA damages in response to genotoxic stress and maintain sustained proliferation.
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    Human apurinic/apyrimidinic endonuclease (APE1) is acetylated at DNA damage sites in chromatin, and acetylation modulates its DNA repair activity
    (American Society for Microbiology, 2016) Roychoudhury, S.; Nath, S.; Song, H.; Hegde, M.L.; Bellot, L.J.; Mantha, Anil K.; Sengupta, S.; Ray, S.; Natarajan, A.; Bhakat, K.K.
    Apurinic/apyrimidinic (AP) sites, the most frequently formed DNA lesions in the genome, inhibit transcription and block replication. The primary enzyme that repairs AP sites in mammalian cells is the AP endonuclease (APE1), which functions through the base excision repair (BER) pathway. Although the mechanism by which APE1 repairs AP sites in vitro has been extensively investigated, it is largely unknown how APE1 repairs AP sites in cells. Here, we show that APE1 is acetylated (AcAPE1) after binding to the AP sites in chromatin and that AcAPE1 is exclusively present on chromatin throughout the cell cycle. Positive charges of acetylable lysine residues in the N-terminal domain of APE1 are essential for chromatin association. Acetylation-mediated neutralization of the positive charges of the lysine residues in the N-terminal domain of APE1 induces a conformational change; this in turn enhances the AP endonuclease activity of APE1. In the absence of APE1 acetylation, cells accumulated AP sites in the genome and showed higher sensitivity to DNA-damaging agents. Thus, mammalian cells, unlike Saccharomyces cerevisiae or Escherichia coli cells, require acetylation of APE1 for the efficient repair of AP sites and base damage in the genome. Our study reveals that APE1 acetylation is an integral part of the BER pathway for maintaining genomic integrity. ? 2017 Roychoudhury et al.