Working title: Molecular involvement of p53-MDM2 interactome in gastrointestinal cancers.

The interaction between murine double minute 2 (MDM2) and p53, marked by transcriptional induction and feedback inhibition, orchestrates a functional loop dictating cellular fate. The functional loop comprising p53-MDM2 axis is made up of an interactome consisting of approximately 81 proteins, which are spatio-temporally regulated and involved in DNA repair mechanisms. Biochemical and genetic alterations of the interactome result in dysregulation of the p53-mdm2 axis that leads to gastrointestinal (GI) cancers. A large subset of interactome is well known and it consists of proteins that either stabilize p53 or MDM2 and proteins that target the p53-MDM2 complex for ubiquitin-mediated destruction. Upstream signaling events brought about by growth factors and chemical messengers invoke a wide variety of posttranslational modifications in p53-MDM2 axis. Biochemical changes in the transactivation domain of p53 impact the energy landscape, induce conformational switching, alter interaction potential and could change solubility of p53 to redefine its co-localization, translocation and activity. A diverse set of chemical compounds mimic physiological effectors and simulate biochemical modifications of the p53-MDM2 interactome. p53-MDM2 interactome plays a crucial role in DNA damage and repair process. Genetic aberrations in the interactome, have resulted in cancers of GI tract (pancreas, liver, colorectal, gastric, biliary, and esophageal). We present in this article a review of the overall changes in the p53-MDM2 interactors and the effectors that form an epicenter for the development of next-generation molecules for understanding and targeting GI cancers.

PROTACs in the Management of Prostate Cancer.

Cancer treatments with targeted therapy have gained immense interest due to their low levels of toxicity and high selectivity. Proteolysis-Targeting Chimeras (PROTACs) have drawn special attention in the development of cancer therapeutics owing to their unique mechanism of action, their ability to target undruggable proteins, and their focused target engagement. PROTACs selectively degrade the target protein through the ubiquitin-proteasome system, which describes a different mode of action compared to conventional small-molecule inhibitors or even antibodies. Among different cancer types, prostate cancer (PC) is the most prevalent non-cutaneous cancer in men. Genetic alterations and the overexpression of several genes, such as FOXA1, AR, PTEN, RB1, TP53, etc., suppress the immune response, resulting in drug resistance to conventional drugs in prostate cancer. Since the progression of ARV-110 (PROTAC for PC) into clinical phases, the focus of research has quickly shifted to protein degraders targeting prostate cancer. The present review highlights an overview of PROTACs in prostate cancer and their superiority over conventional inhibitors. We also delve into the underlying pathophysiology of the disease and explain the structural design and linkerology strategies for PROTAC molecules. Additionally, we touch on the various targets for PROTAC in prostate cancer, including the androgen receptor (AR) and other critical oncoproteins, and discuss the future prospects and challenges in this field.

MicroRNAs as a therapeutic target in IgA nephropathy in Indian population.

Immunoglobulin A nephropathy (IgAN) is the most frequent glomerular disease with rapid development to end stage renal disease, requiring renal replacement therapy. Genome-wide studies suggest geographical variations in genetic susceptibility to IgAN and disease progression. Specific 'candidate genes' were indicated to correlate with different functions that are involved in the pathogenesis of renal conditions. MicroRNAs (miRNAs/miRs) have a major role in mRNA degradation or translation repression, thereby regulating the expression of their target proteins. Previously, a small number of miRNAs were reported to have direct associations with IgAN. In the present study, new miRNAs linked to IgAN were identified in the Indian population. The miRNA was isolated from kidney biopsies of patients with IgAN (n=6) and healthy control tissue from patients with renal cell carcinoma (n=6). The sequencing results indicated that the miRNA percentage acquired from controls and patients with IgAN was 5.61 and 4.35%, respectively. From the results, 10 upregulated and 15 downregulated miRNAs were identified. Of the 25 differentially expressed miRNAs (DEMs), miR-181a-5p, miR-28-3p, let-7g-5p, miR-92a-3p and miR-30c-5p were not reported previously. Furthermore, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses suggested that the target genes of the DEMs were mainly enriched in pathways such as cancer, ErbB signalling, proteoglycans in cancer, Hippo signalling and MAPK pathways. The newly identified miRNAs may impact the behaviour of tissues or IgA deposition by regulating signalling pathways, which forms a basis for future studies aimed at improving the diagnosis and care of patients with IgAN in the Indian community.

Novel linezolid-based oxazolidinones as potent anticandidiasis and antitubercular agents.

The quest for new antifungal and antitubercular drugs is a need of the hour because of morbid co-pathogenesis and an increase in immunocompromised patients. One of the ways forward is to explore and repurpose the established pharmacophores for the desired application. Oxazolidinones are well-known antibacterial agents, with few investigations reported to exploit their antifungal properties. Herein, we report the design and synthesis of a series of linezolid-based oxazolidinones as potent anticandidiasis and antitubercular agents. Studies revealed that two of the novel oxazolidinones 2 and 3a exhibited excellent anticandidiasis activity against different Candida fungus strains, superior to standard drugs. Mechanistic and docking studies revealed that oxazolidinones were better inhibitors of the ergosterol biosynthesis pathway than the controls used. In addition, the oxazolidinones 2 and 3a also exhibited prominent inhibitory activity against M. tuberculosis H37Rv with MIC values of 1 and 2 µg/ml, respectively. Computational studies demonstrated the binding of the compounds to the transcriptional regulatory repressor protein, which was reinforced by the molecular dynamics simulations. The pharmacophore modeling experiments validated the molecular docking results in both the target proteins.

Identification, characterization and evaluation of novel antifungal cyclic peptides from Neobacillus drentensis.

Marine microbes secrete exopolymeric substances (EPS), which surrounds the biofilm and inhibits the fungal growth. Elucidation of the structure and function of the extracellular exopolymeric substances is of vital relevance therapeutically. The active compound responsible for bioactivity was purified and characterized using TLC, LC/MS/MS, GC/MS and FT-IR. Bioactivity of the characterized cyclic peptides (CLPs) against azole resistant and susceptible Candida strains were examined for growth and biofilm formation using scanning electron microscopy, flow cytometry, confocal microscopy. In the present study we identified bioactive cyclic peptides from marine isolated Neobacillus drentensis that exhibited promising tensio-active properties and antifungal efficacy against azole resistant and susceptible Candida albicans. The cluster is composed of five CLP isoforms which were sequenced and identified as new peptides with compositional and structural variations in the amino acid sequence and fatty acid chain. In vitro cytotoxic activity of CLPs was tested in human fibroblast normal cells. We have observed that the CLPs repressed the Candida albicans growth and multiplication by inhibiting the biofilm formation and disruption of branching filamentous hyphae. CLPs have been found to arrest the C. albicans cell cycle by a block at G1-S transition followed by apoptotic cell death. The current studies suggest these natural marine derived CLPs function as potential anti-biofilm agents against azole C. albicans resistant strains.

In-silico driven design and development of spirobenzimidazo-quinazolines as potential DNA gyrase inhibitors.

DNA gyrase and Topoisomerase IV are promising antibacterial drug targets as they regulate bacterial DNA replication and topology. In a quest for novel DNA topoisomerase inhibitors, a multidisciplinary approach was adopted that involves computational prediction of binding sites and molecular modelling followed by green synthesis and biological evaluation of antibacterial activity of spirobenzimidazo quinazolines derivatives. Using basic quantum chemistry principles, we evaluated spirobenzimidazo quinazolines derivatives with their pharmacokinetic profiles. Based on the results of the aforesaid in-silico studies, we synthesized a series of titled compounds using green synthetic methodology that were validated as potential antimicrobial agents. Quantum chemoinformatics based predicted activity for the synthesized compounds 9b, 9c, and 9j was concomitant with biological evaluation of broadspectrum antibacterial activity. Biological evaluation revealed that inhibition of biofilm formation was due to their potential antibacterial activity. We believe that the novel spirobenzimidazo quinazolines have the potential to be alternatives to aminocoumarins and classical quinazolines upon detailed target specific biological studies.

Identification, synthesis and evaluation of CSF1R inhibitors using fragment based drug design.

Colony-stimulating factor 1 receptor is a type III receptor protein tyrosine kinase belonging to PDGFR family. CSF1R signaling is essential for differentiation, proliferation and survival of macrophages. Aberrant expression of CSF1R appears to be an attractive target in several cancer types. Higher expression of CSF1R ligands correlates to tumor progression. CSF1R inhibitors have been shown to suppress cancers. We have attempted an in silico fragment derived drug discovery approach by screening ˜25,000 in-house compounds as potential CSF1R inhibitors. Using FBDD approach we have identified six diverse fragments that exhibit affinity towards hinge region of CSF1R. Some of the fragments 5-nitroindole and 7-azaindole and their derivatives were synthesized for further evaluation. The in silico and in vitro enzyme activity studies reveal moderate inhibition of CSF1R kinase activity by 5-nitroindole and good inhibition by 7-azaindole fragments. Bio and chemiinformatics studies have shown that 7-azaindole compounds have better membrane permeability and enzyme inhibition properties. Molecular docking studies show that the amino acid residues 664-666 in the hinge region of the cytosolic domain of CSF1R to be the preferred region of binding for nitroindole and azaindole derivatives. Further optimization and biological analysis would identify these fragments as potential and promising leads as CSF1R inhibitors.

Synthesis and Biological Evaluation of 1,2,3-triazole tethered Pyrazoline and Chalcone Derivatives.

A series of pyrazoline derivatives and corresponding chalcone intermediates with substituents same as combretastatin-A4(CA-4) conjugated with triazole nucleus has been synthesized and evaluated for their anticancer potential. Sulphorhodamine B(SRB) assay indicated compound 12c to be the most active compound from the series with GI50 value of 6.7 µm against the human liver carcinoma cell line HepG2. Interestingly, the intermediate 11c exhibited more promising cytotoxicity demonstrating GI50 value of 1.3 µm against the prostate cancer cell line DU145. Compounds 11c and 12c caused accumulation of cells in G2/M phase and inhibited tubulin polymerization. Furthermore, these compounds reduce the mitochondrial membrane potential and activate caspases 3 and 9, thereby indicating their ability to trigger apoptosis.

Synthesis and biological evaluation of novel lipoamino acid derivatives.

Seven novel lipoamino acid conjugates were synthesized from methyl oleate and amino acids. Methyl oleate was grafted to different amino acids using thioglycolic acid as a spacer group. Seven derivatives (3a-g) were prepared and characterized by spectral data (NMR, IR and MS spectral studies). All the derivatives were studied for their antimicrobial, anti-biofilm and anticancer activities. Among all the derivatives, it was found that compound 3b was the most potent antibacterial compound which showed good activity against four Gram positive bacterial strains and also exhibited excellent antifungal activity against a fungal strain. In the anti-biofilm assay, compound 3b showed promising activity with IC50 value of 2.8µM against Bacillus subtilis MTCC 121. All the compounds showed anticancer activities with 3c showing promising anticancer activity (IC50=15.3-22.4µM) against the four cell lines tested.