Inactivation of the NHEJ Activity of DNA-PKcs Prevents Fanconi Anemia Pre-Leukemic HSC Expansion

Fanconi anemia (FA) is a genetic disorder characterized by bone marrow failure and high risk of cancer particularly leukemia. Here we show that inactivation of the non-homologous end-joining (NHEJ) activity of DNA-PKcs prevented DNA damage-induced expansion of FA pre-leukemic hematopoietic stem cells (HSCs). Furthermore, we performed serial BM transplantation to demonstrate that the DNA damage-induced expanded FA HSC compartment contained pre-leukemic stem cells that required the NHEJ activity of DNA-PKcs to induce leukemia in the secondary recipients. These results suggest that NHEJ may collaborate with FA deficiency to promote DNA damage-induced expansion of pre-leukemic HSCs.

Scriptaid cause histone deacetylase inhibition and cell cycle arrest in HeLa cancer cells: A study on structural and functional aspects.

Scriptaid (SCR), a well-known histone deacetylase inhibitor, cause various cellular effects such as cell growth inhibition and apoptosis. In this study, we have evaluated the anti-cancer effects of Scriptaid in HeLa cells, IMR-32 and HepG2 cells. Scriptaid inhibited the growth of HeLa cells with IC50 of 2µM at 48h in a dose-dependent manner. Flow-cytometric analysis indicated that SCR induced apoptosis. Scriptaid was found to inhibit HDAC-8 effectively than other HDAC inhibitor such as TSA as observed by HDAC-8 assay, Western blotting and modelling study. This observation was further strengthened by an artificial neuronal network (ANN) model.

Novel SAHA analogues inhibit HDACs, induce apoptosis and modulate the expression of microRNAs in hepatocellular carcinoma.

In eukaryotes, transcriptional regulation occurs via chromatin remodeling, mainly through post translational modifications of histones that package DNA into structural units. Histone deacetylases (HDACs) are enzymes that play important role in various biological processes by repressing gene expression. Suberoylanilide hydroxamic acid (SAHA) is a known HDAC inhibitor that showed significant anti cancer activity by relieving gene silencing against hematologic and solid tumors. We have designed and synthesized a series of SAHA analogs C1-C4 and performed biological studies to elucidate its anti-cancer effects. It is observed that SAHA analogs significantly inhibited cell proliferation and induced apoptosis in hepatocellular carcinoma (HCC) cell lines HepG2 and SK-HEP-1. These analogs also showed non-toxic activity towards primary human hepatocytes, which describes its tumor specificity. SAHA analogs exhibited strong HDAC inhibition, which is 2-3 fold higher compared to SAHA. Moreover, these molecules induced hyper acetylation of histone H3 at various positions on the lysine residue. Further, it is observed that SAHA analogs are strong inducers of apoptosis, as they regulated the expression of various proteins involved in both extrinsic and intrinsic pathways. Interestingly, SAHA analogs induced upregulation of tumor suppressor miRNAs by activating its biogenesis pathway. Further, it is confirmed by microRNA (miRNA) prediction tools that these miRNAs are capable of targeting various anti-apoptotic genes. Based on these findings we conclude that SAHA analogs could be strong HDAC inhibitors with promising apoptosis inducing nature in HCC.

Novel Etoposide Analogue Modulates Expression of Angiogenesis Associated microRNAs and Regulates Cell Proliferation by Targeting STAT3 in Breast Cancer.

Tumor microenvironment play role in angiogenesis and carcinogenesis. Etoposide, a known topoisomerase II inhibitor induces DNA damage resulting in cell cycle arrest. We developed a novel Etoposide analogue, Quinazolino-4ß-amidopodophyllotoxin (C-10) that show better efficacy in regulating cell proliferation and angiogenesis. We evaluated its role on expression of microRNAs-15, 16, 17 and 221 and its targets Bcl-2, STAT3 and VEGF that dictate cell proliferation and angiogenesis. Docking studies clearly demonstrated the binding of Etoposide and C-10 to STAT3. We conclude that combination of Etoposide or C-10 with miR-15, 16, 17 and 221 as a new approach to induce apoptosis and control angiogenesis in breast cancer.

Synthesis of imidazothiazole-chalcone derivatives as anticancer and apoptosis inducing agents.

A new class of imidazo[2,1-b]thiazole chalcone derivatives were synthesized and evaluated for their anticancer activity. These chalcone derivatives show promising activity, with log GI(50) values ranging from -7.51 to -4.00. The detailed biological aspects of these derivatives toward the MCF-7 cell line were studied. Interestingly, these chalcone derivatives induced G(0)/G(1)-phase cell-cycle arrest, down-regulation of G(1)-phase cell-cycle regulatory proteins such as cyclin D1 and cyclin E1, and up-regulation of CDK4. Moreover, these compounds elicit the characteristic features of apoptosis such as enhancement in the levels of p53, p21, and p27, suppression of NF-κB, and up-regulation of caspase-9. One of these chalcone derivatives, 3 d, is potentially well suited for detailed biological studies, either alone or in combination with existing therapies.

Synthesis, DNA-binding ability and anticancer activity of benzothiazole/benzoxazole-pyrrolo[2,1-c][1,4]benzodiazepine conjugates.

A series of benzothiazole and benzoxazole linked pyrrolobenzodiazepine conjugates attached through different alkane or alkylamide spacers was prepared. Their anticancer activity, DNA thermal denaturation studies, restriction endonuclease digestion assay and flow cytometric analysis in human melanoma cell line (A375) were investigated. One of the compounds of the series 17d showed significant anticancer activity with promising DNA-binding ability and apoptosis caused G0/G1 phase arrest at sub-micromolar concentrations. To ascertain the binding mode and understand the structural requirement of DNA binding interaction, molecular docking studies using GOLD program and more rigorous 2 ns molecular dynamic simulations using Molecular Mechanics-Poisson-Boltzman Surface Area (MM-PBSA) approach including the explicit solvent were carried out. Further, the compound 17d was evaluated for in vivo efficacy studies in human colon cancer HT29 xenograft mice.