Design, synthesis, DNA binding studies and evaluation of anticancer potential of novel substituted biscarbazole derivatives against human glioma U87 MG cell line.

In this research paper, we report the design and synthesis of novel substituted biscarbazole derivatives which were characterized by 1H and 13C NMR, high resolution mass spectroscopy (HRMS). The SAR study of the compounds is reported based on different substituents and their positions in the biscarbazole scaffold. In vitro cytotoxicity of the compounds was evaluated against human glioma U87 MG cell line by MTT assay for 24 h. The IC50 values of the compounds (30-35, 48-53 and 54-62) were calculated at the concentration range from 1.00 µM to 500 µM. The compound 34 showed the most significant in vitro cytotoxicity (IC50 = 3.9 µM) against human glioma U87 MG cell line and was found to be better than standard drugs used for the treatment of brain tumors such as temozolomide (IC50 = 100 µM) and carmustine (IC50 = 18.2 µM) respectively. To determine the mode of binding of compound 34 with CT-DNA, various biophysical techniques like UV-spectrophotometer, fluorescence, circular dichroism, viscosity, topoisomerase assay and molecular docking analysis, were used. Our results demonstrated groove binding mode of interaction of the compound 34 with CT-DNA with a plausible static bio-molecular quenching rate constant (Kq) 1.7 × 1012 M-1 s-1. The studies of biscarbazole derivatives are anticipated to develop potential novel anticancer agents against brain tumors.

Proteasome mediated degradation of CDC25C and Cyclin B1 in Demethoxycurcumin treated human glioma U87 MG cells to trigger G2/M cell cycle arrest.

Recently, we have reported that Demethoxycurcumin induced Reactive oxygen species via inhibition of Mitochondrial Superoxide Dismutase is an initial event to trigger apoptosis through caspase-8 and 9 activation and to inhibit Akt/NF-κB survival signaling in human glioma U87 MG cells (Kumar et al., 2018). Although cell-cycle disruption had been suggested to be the possible mechanism for DMC inhibitory effect on human glioma U87 MG cells, comprehensive mechanisms of cell-cycle arrest caused by DMC are not fully understood. The present study was designed to elucidate the DMC induced mechanism of cell cycle arrest in human glioma U87 MG cells. In this study, the results illustrated that DMC induced Reactive oxygen species (ROS) leads to reduced expression of CDC25C, Cyclin B1 and CDK1 (Thr161) triggers G2/M cell cycle arrest in U87 MG glioma cells. Moreover, the DMC induced ROS generation activates ubiquitination and proteasome degradation of CDC25C and Cyclin B1 in U87MG glioma cells. In addition, the immunoprecipitation results showed that significant dissociation of CDK1or CDC2-Cyclin B1 complex leads to G2/M cell cycle arrest. To explore the possibility of direct involvement of DMC in the dissociation of CDK1/Cyclin B1 complex, the molecular docking and MD simulation studies were carried. The results showed that DMC nicely fitted into the binding site of CDK1 and Cyclin B1 with minimum binding energy (ΔG) of -9.46 kcal/mol (Ki = 0.11 µM) and - 9.90 kcal/mol (Ki = 0.05 µM) respectively. Therefore, this is the first study demonstrating CDC25C and Cyclin B1 proteins could be used as potential target for anticancer therapy and DMC may be explored as new therapeutic agent in the cure of Glioblastoma (GBM).

Demethoxycurcumin mediated targeting of MnSOD leading to activation of apoptotic pathway and inhibition of Akt/NF-κB survival signalling in human glioma U87 MG cells.

Earlier, we reported that Demethoxycurcumin (DMC) suppressed the growth of human glioma U87 MG cells by downregulation of Bcl-2 expression. In the present work, we investigated the DMC induced reactive oxygen species (ROS) mediated anti-proliferative and apoptotic effects in U87 MG cells. Exposure of U87 MG cells to growth-suppressive concentrations of DMC (0-50 µg/ml) resulted in ROS generation and concomitant increase in apoptosis. The major oxidative species induced by DMC was superoxide anion radical (O2-). DMC-induced anti-proliferation was mediated by Akt/NF-κB signalling inhibition and apoptosis through caspase-8 and 9 activation. In silico molecular docking analysis showed that, the amino acid residues His30, Tyr34, Asn37, Ala63, Asn67, His74, Trp123, and Asp159 in the active site of mitochondrial SOD (MnSOD) interacted with DMC. Furthermore, the complex MnSOD-DMC was found to be more stable as compared to native MnSOD in the MD simulations. In the present study, we have demonstrated for the first time using U87 MG cell line that DMC (a) establishes π-π interactions with Tyr 34 and Trp 161 in the putative active site of MnSOD to inhibit its activity, generating (O2-) to regulate survival and apoptotic proteins leading to antiproliferative and apoptotic events (b) induces antiproliferative effect via inhibition of Akt/NF-κB signalling pathway (c) contributes to the apoptosis via caspase-8 and caspase-9 activation to release the cytochrome c. In exploring the DMC induced cell death events in U 87 MG cell line, we revealed a novel mechanism of DMC-mediated inhibition of MnSOD leading to accumulation of superoxide anions to trigger the inhibition of survival pathways and induction of apoptosis.

Prospective of curcumin, a pleiotropic signalling molecule from Curcuma longa in the treatment of Glioblastoma.

GBM (Glioblastoma) is the most malignant human brain tumor with median survival of one year. The treatment involves surgery, radiotherapy and adjuvant chemotherapy mostly with the alkylation agents such as temozolomide (TMZ). Dietary polyphenol curcumin, isolated from the rhizome of the Curcuma longa (turmeric), has emerged as remarkable anti-cancer agent in the treatment of various peripheral cancers such as blood, lymphomas, multiple myeloma, melanoma as well as skin, lung, prostate, breast, ovarian, bladder, liver, gastrointestinal tract, pancreatic and colorectal epithelial cancers with a pleiotropic mode of action and also showed promise in alleviation of GBM. In this review, the mechanism of anticancer effect of curcumin in GBM has been discussed extensively. The clinical safety and pharmacokinetics of curcumin has been scrutinized to combat the challenges for the treatment of GBM.