Artesunate acts as fuel to fire in sensitizing HepG2 cells towards TRAIL mediated apoptosis via STAT3 inhibition and DR4 augmentation.

In the present study, we investigated in vitro, the role of artesunate (ATS) with comparable potency to oxaliplatin (OXP) in sensitizing tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) resistant HepG2 cells towards apoptosis. ATS in consistency with OXP was found to reverse TRAIL resistant HepG2 cells towards TRAIL mediated apoptosis by enhancing caspase-3 and cleavage of PARP. Additionally, ATS also suppressed the nuclear translocation of activated signal transducers and activators of transcription 3 (STAT3) thereby sensitizing the HepG2 cells towards only death receptor 4 (DR4) mediated apoptosis. Furthermore, ATS exposure in TRAIL resistant cells resulted in significant increase of both DR4/DR5 expression and STAT3 inhibition thereby arbitrating TRAIL mediated apoptosis in HepG2 cells. The increase in expression was comparable to that of STAT3 silenced cells. From all the above observations, we conclude that ATS up-regulated DR4 expression by targeting STAT3, which in turn sensitized HepG2 cells to TRAIL mediated apoptosis.

Viper venom hyaluronidase and its potential inhibitor analysis: a multipronged computational investigation.

Viper venom hyaluronidase (VV-HYA) inhibitors have long been used as therapeutic agents for arresting the local and systemic effects caused during its envenomation. Henceforth, to understand its structural features and also to identify the best potential inhibitor against it the present computational study was undertaken. Structure-based homology modeling of VV-HYA followed by its docking and free energy-based ranking analysis of ligand, the MD simulations of the lead complex was also performed. The sequence analysis and homology modeling of VV-HYA revealed a distorted (ß/α)8 folding as in the case of hydrolases family of proteins. Molecular docking of the resultant 3D structure of VV-HYA with known inhibitors (compounds 1-25) revealed the importance of molecular recognition of hotspot residues (Tyr 75, Arg 288, and Trp 321) other than that of the active site residues. It also revealed that Trp 321 of VV-HYA is highly important for mediating π-π interactions with ligands. In addition, the molecular docking and comparative free energy binding analysis was investigated for the VV-HYA inhibitors (compounds 1-25). Both molecular docking and relative free energy binding analysis clearly confirmed the identification of sodium chromoglycate (compound 1) as the best potential inhibitor against VV-HYA. Molecular dynamics simulations additionally confirmed the stability of their binding interactions. Further, the information obtained from this work is believed to serve as an impetus for future rational designing of new novel VV-HYA inhibitors with improved activity and selectivity.

Artesunate obliterates experimental hepatocellular carcinoma in rats through suppression of IL-6-JAK-STAT signalling.

Activation of the IL-6 mediated JAK-STAT (Janus associated kinase-signal transducer and activator of transcription) oncogenic signalling plays a major role in hepatocellular carcinoma pathogenesis. The aim of this study is to assess the anti-tumour, anti-proliferative and apoptotic potential of artesunate and its capacity to modulate JAK-STAT pathway in a nitrosodiethylamine mediated experimental hepatocellular carcinoma model. Administration of nitrosodiethylamine (200mg/kg body weight by i.p. Injections) to rats resulted in alterations of liver pathophysiological parameters such as increased relative liver weight, and increased tumour nodule occurrence. It also increased the levels of serum marker enzymes (AST, ALT, ALP, LDH, and γGT) and tumour biomarker (AFP) levels suggestive of its capacity to cause liver tumourigenesis. Additionally, the immunohistochemistry of liver sections pertaining to nitrosodiethylamine administered animals showed increased detection of AgNOR, PCNA, and GST-Pi positive cells suggestive of its capacity to promote liver proliferation associated tumourigenesis. On the contrary, artesunate (25mg/kg bodyweight) supplementation to nitrosodiethylamine administered animals decreased all the above mentioned pathophysiological, biochemical, and immunohistochemistry parameters suggesting its anti-tumour and anti-proliferative potential. Furthermore, immunoblot analysis showed significant up-regulation of IL-6, GP130, JAK-2, STAT-3 (pY705), Bcl-xL, Bcl-2 and simultaneous down-regulation of Caspase-3, PARP and SOCS-3 in nitrosodiethylamine administered animals. Nevertheless, the immunoblot analysis revealed vice-versa on artesunate supplementation to nitrosodiethylamine administered animals, indicating promotion of the feedback loop inhibition mechanism through SOCS3 up-regulation thereby leading to suppression of JAK-STAT signalling. Overall all these findings substantiate that artesunate promotes anti-tumour, anti-proliferation and apoptosis against nitrosodiethylamine mediated hepatocellular carcinoma.

Artesunate as an Anti-Cancer Agent Targets Stat-3 and Favorably Suppresses Hepatocellular Carcinoma.

BACKGROUND: Aberrant signal transducer and activator of transcription 3 (STAT-3) molecular signaling elicit hepatocellular carcinoma (HCC) in humans. Therefore, targeting STAT-3 is considered as an attractive option towards suppression of HCC in humans. OBJECTIVE: Our objective is to identify a potential small molecule inhibitor that can specifically target STAT-3 and suppress HCC. METHODS: In this study, we analyze a group of sesquiterpene lactone (STL) candidates that has been recently reported in preclinical trials against cancer by a unified computational and experimental approach. RESULTS: Our virtual analysis of the STL candidates revealed Artesunate (ATS) as the best potential inhibitor of STAT-3 with comparable potency to specific inhibitor S3I-201. We also observed that ATS inhibited IL-6 driven STAT-3-DNA binding activity with comparable potency to S3I-201 in a cell free system. Furthermore ATS was observed to interfere with STAT-3 dimerization and suppression of both constitutive and IL-6 inducible STAT-3 in vitro. Nevertheless, we also observed that ATS modulated STAT-3 dependent targets (procaspase-3, Bcl-xl and survivin) favoring occurrence of apoptosis in vitro. Overall, the putative inhibition of STAT-3 by ATS suggested its capacity to interfere with STAT-3 dimerization by binding to the SH2 domain of STAT-3 monomer. It resulted in suppression of STAT-3 and also favored promotion of in vitro cells towards apoptosis. Consequently, ATS also exhibited selective cytotoxicity of cancer cells over normal cells in vitro. CONCLUSION: All the above observations substantiated by unified computational and in vitro experimental approaches suggested its potential role as a therapeutic anti-cancer agent against HCC.

Virtual analysis of structurally diverse synthetic analogs as inhibitors of snake venom secretory phospholipase A2.

Due to the toxic pathophysiological role of snake venom phospholipase A2 (PLA2 ), its compelling limitations to anti-venom therapy in humans and the need for alternative therapy foster considerable pharmacological interest towards search of PLA2 specific inhibitors. In this study, an integrated approach involving homology modeling, molecular dynamics and molecular docking studies on VRV-PL-V (Vipera russellii venom phospholipase A2 fraction-V) belonging to Group II-B secretory PLA2 from Daboia russelli pulchella is carried out in order to study the structure-based inhibitor design. The accuracy of the model was validated using multiple computational approaches. The molecular docking study of this protein was undertaken using different classes of experimentally proven, structurally diverse synthetic inhibitors of secretory PLA2 whose selection is based on IC50 value that ranges from 25 µM to 100 µM. Estimation of protein-ligand contacts by docking analysis sheds light on the importance of His 47 and Asp 48 within the VRV-PL-V binding pocket as key residue for hydrogen bond interaction with ligands. Our virtual analysis revealed that compounds with different scaffold binds to the same active site region. ADME analysis was also further performed to filter and identify the best potential specific inhibitor against VRV-PL-V. Additionally, the e-pharmacophore was generated for the best potential specific inhibitor against VRV-PL-V and reported here. The present study should therefore play a guiding role in the experimental design of VRV-PL-V inhibitors that may provide better therapeutic molecular models for PLA2 recognition and anti-ophidian activity.

Identification of potential transmembrane protease serine 4 inhibitors as anti-cancer agents by integrated computational approach.

Transmembrane protease serine 4 is a well known cell surface protease facilitating the extracellular matrix degradation and epithelial mesenchymal transition in hepatocellular carcinoma. Henceforth targeting transmembrane protease serine 4 is strongly believed to provide therapeutic intervention against hepatocellular carcinoma. Owing to lack of crystal structure for human transmembrane protease serine 4, we predicted its three dimensional structure for the first time in this study. Experimentally proven inhibitor-Tyroserleutide (TSL) against hepatocellular carcinoma via transmembrane protease serine 4 was used as a benchmark to identify structurally similar candidates from PubChem database to create the TSL library. Virtual screening of TSL library against modeled transmembrane protease serine 4 revealed the top four potential inhibitors. Further binding free energy (ΔGbind) analysis of the potential inhibitors revealed the best potential lead compound against transmembrane protease serine 4. Drug likeliness nature of the top four potential hits were additionally analyzed in comparison to TSL to confirm on the best potential lead compound with the highest % of human oral absorption. Consequently, e-pharmacophore mapping of the best potential lead compound yielded a six point feature. It was observed to contain four hydrogen bond donor sites (D), one positively ionizable site (P) and one aromatic ring (R). Such e-pharmacophore insight obtained from structural determinants by integrated computational analysis could serve as a framework for further advancement of drug discovery process of new anti-cancer agents with less toxicity and high specificity targeting transmembrane protease serine 4 and hepatocellular carcinoma.

Formylchromone exhibits salubrious effects against nitrosodiethylamine mediated early hepatocellular carcinogenesis in rats.

The salubrious effects of 3-Formylchromone (3-FC) against nitrosodiethylamine (NDEA) mediated early hepatocellular carcinogenesis was investigated in vivo by this study. Male Wistar rats were administered three interspersed intraperitoneal injections of NDEA (200 mg/kg body weight) until sixth week, followed by, thrice a week oral dose of 3-FC (25 mg/kg body weight) from the seventh week to eleventh week. Oral supplementation of Wistar rats with 3-FC prevented the increase in serum marker enzymes (AST, ALT, LDH) and serum pre-neoplastic marker (γ-GT) induced by NDEA. Biochemical observations were found to be further correlated with histological studies, indicating the potential of 3-FC to mediate suppression of hepatic damage/pre-neoplastic lesions. Argyrophilic nucleolar organizer region (AgNOR) staining was done in histology sections to confirm the anti-proliferative potential of 3-FC against NDEA-induced early hepatocellular carcinogenesis. RT-PCR and immunoblot analysis was done to find the modulations in the gene transcript/protein level expression of pre-neoplastic marker (GST-pi), proliferation marker (PCNA), apoptotic mediators (PPARγ, NFκB-p65 and p53). 3-FC was found to favorably modulate the expressions of GST-pi, PCNA, PPARγ, NFκB-p65, p53 clearly confirming the anti-proliferative and apoptotic potential of 3-FC. Further, the apoptotic effect of 3-FC against NDEA-induced early hepatocellular carcinogenesis was confirmed by caspase-3 activity assay and DNA fragmentation analysis. Based on these findings, it is concluded that 3-FC possesses hepatoprotective, anti-pre-neoplastic, anti-proliferative and apoptosis inducing capability against NDEA-induced early hepatocellular carcinogenesis.

Homology modeling, molecular dynamics and atomic level interaction study of snake venom 5' nucleotidase.

5' Nucleotidase (5' NUC) is a ubiquitously distributed enzyme known to be present in snake venoms (SV) that is responsible primarily for causing dysregulation of physiological homeostasis in humans by inducing anticoagulant effects and by inhibiting platelet aggregation. It is also known to act synergistically with other toxins to exert a more pronounced anti-coagulant effect during envenomation. Its structural and functional role is not yet ascertained clearly. The 3D structure of snake venom 5' nucleotidase (SV-5' NUC) is not yet known and was predicted by us for the first time using a comparative homology modeling approach using Demansia vestigiata protein sequence. The accuracy and stability of the predicted SV-5' NUC structure were validated using several computational approaches. Key interactions of SV-5' NUC were studied using experimental studies/molecular docking analysis of the inhibitors vanillin, vanillic acid and maltol. All these inhibitors were found to dock favorably following pharmacologically relevant absorption, distribution, metabolism and excretion (ADME) profiles. Further, atomic level docking interaction studies using inhibitors of the SV-5' NUC active site revealed amino acid residues Y65 and T72 as important for inhibitor-(SV-5' NUC) interactions. Our in silico analysis is in good agreement with experimental inhibition results of SV-5' NUC with vanillin, vanillic acid and maltol. The present study should therefore play a guiding role in the experimental design of new SV-5' NUC inhibitors for snake bite management. We also identified a few pharmacophoric features essential for SV-5' NUC inhibitory activity that can be utilized further for the discovery of putative anti-venom agents of therapeutic value for snake bite management.