Arunasree M. Kalle

Histone deacetylases (HDACs) are pivotal epigenetic regulators that modulate diverse cellular pathways by removing acetyl groups from lysine residues on both histone and non-histone proteins. Histone deacetylase 11 (HDAC11), the sole member of class IV HDACs, exhibits both deacetylation and fatty acid deacylation activities. Accumulating evidence implicates HDAC11 as a key epigenetic regulator of fundamental cellular processes, including metabolism, immune responses, and tissue development. Dysregulation of HDAC11 activity has been associated with inflammatory diseases, metabolic disorders, neurodegenerative conditions, and cancer, highlighting its potential as a therapeutic target. Although several HDAC11-specific inhibitors have been identified, none have progressed to clinical development. In this study, we aimed to discover HDAC11-selective inhibitors by integrating in silico and in vitro validation approaches. Homology modelling of the HDAC11 structure was conducted, followed by model validation, structure-based virtual screening, molecular dynamics (MD) simulations, and binding free energy calculations. We identified and validated three lead compounds and their intermediates using biochemical and cell-based assays. Fluorescence-based and HPLC-based enzymatic assays demonstrated potent inhibition of both the deacetylase and deacylase activities of HDAC11, with Inhibitor 6 and Inhibitor 3 exhibiting the strongest effects among the six compounds tested. Further, a decrease in lipid accumulation, reduced stability of the HDAC11 substrate SHMT2, as determined by immunoblot analysis and decreased cell viability, as assessed by MTT assay, confirmed HDAC11 inhibition in cellular models. The study shows that new HDAC11 inhibitors significantly reduce the viability of breast cancer cells and induce apoptosis; inhibitor 6, in particular, showed high potency, similar to the reference compound SIS-17. Flow cytometry showed that treated MDA-MB-231 cells exhibited cell-cycle arrest and increased apoptosis, a finding further confirmed by Annexin V/PI staining. Molecular analysis showed that BAX increased while BCL2 decreased, indicating that apoptotic pathways were activated in novel compound-treated MDA-MB-231 cells. The results suggest that inhibiting HDAC11 is an effective way to induce cancer cell death and provide a basis for further assessment of these compounds as potential treatments for breast cancer. Collectively, this study identifies novel zinc-chelating HDAC11 inhibitors containing a nitro-sp² group, providing promising candidates for further therapeutic development.

Introduction: Protein Kinase C alpha (PKCα), a key regulator of cellular signaling, is frequently dysregulated in breast cancer. Despite its clinical relevance, there is a dearth of selective and safe PKCα inhibitors. This study aims to identify and characterize novel PKCα inhibitors using computational and experimental methodologies. Methods: A structure-based virtual screening of the Enamine Hinge Binders Library against the PKCα receptor (PDB ID: 3IW4) was performed using the Glide module of Schrödinger Suite. Analysis of docking scores, protein-ligand interactions, binding free energies, and ADMET profiles helped identify lead candidates. The stability of protein-ligand complexes was confirmed using MD simulations. The functional activity of identified candidates was validated using a kinase assay, and cell death was analyzed using an MTT assay on breast cancer cell lines. Results: Compounds Z3077775938 (P1) and Z22177390 (P2) exhibited strong binding and stability within the hinge-binding region of PKCα and showed favorable drug-likeness profiles. Structural analysis revealed P1 and P2 as novel scaffolds. The kinase assay revealed dosedependent inhibition of PKCα’s ATP-binding activity with IC50 values of P1 and P2 as 0.92 nM and 15.27 nM, respectively. Both compounds induced dose-dependent cytotoxicity in breast cancer cells. Discussion: This study identified two novel, structurally diverse PKCα inhibitors. Their low IC50 values and dose-dependent cytotoxicity, as observed in both ER+ and triple-negative breast cancer cell lines, validate their functional efficacy and highlight therapeutic potential for breast cancer treatment Conclusion: Overall, this study identified two PKCα inhibitors that provide a foundation for further optimization as selective therapeutic agents in PKCα-driven malignancies

Mixed-lineage leukemia translocated to 3 (MLLT3) is vital for maintaining the stemness of hematopoietic stem cells. Loss of MLLT3 in megakaryocyte (MK)-erythrocyte progenitor (MEP) cells leads to its differentiation into MKs. Despite its significance in stemness, the regulatory mechanism of MLLT3 during differentiation remains elusive. In this study, we investigate the regulatory role of histone deacetylase 6 (HDAC6) in modulating MLLT3 levels via heat shock protein 90 (Hsp90) activation during myeloid lineage differentiation into MKs, monocytes, and macrophages. We found that HDAC6 activates Hsp90 through deacetylation, enabling Hsp90 to retain MLLT3 in the cytoplasm where protein kinase C (PKC) phosphorylates MLLT3 at serine residues; leading to loss of MLLT3 during MK and macrophage differentiation but not during monocyte differentiation. This research provides valuable insights into the regulatory mechanisms underlying myeloid lineage commitment and opens new avenues for future investigations into stem cell biology and therapeutic applications.

Antimicrobial resistance (AMR) has become a major concern in the treatment of bacterial infections, and bacteriophage therapy has emerged as a promising alternative to antibiotics. Bacteriophages are highly specific to their bacterial hosts; hence, isolating phages indigenous to a specific region offers a significant advantage against various pathogen strains. We have isolated a cocktail of bacteriophages against pathogenic E. coli from sewage water at a primary healthcare centre. Characterisation of the isolated phages demonstrated their stability across a broad pH and temperature range, strong lytic activity, and effective biofilm degradation, with no cross-reactivity with Staphylococcus aureus (S. aureus). Genomic analysis and phylogenetic studies indicated that the largest phage (by genome size) in the cocktail belongs to the genus Vequintavirus (myoviruses, rV5-like phages), and its genome sequence has been deposited in NCBI (Accession ID: PX741096). The phage genome was linear, with headful (PAC) packaging, encoded lysis proteins, and lacked antibiotic-resistant or major lysogeny-associated genes, collectively suggesting a lytic lifestyle. These findings emphasize the therapeutic potential of rV5-like phages and underscore the critical need to establish phage banks in India to improve disease management.

The side effects associated with conventional anti-cancer therapies call for safer and more effective alternatives. Flavonoids are a class of polyphenolic compounds well documented to possess antioxidant, anti-inflammatory, and anticancer properties. This study investigates the bioactivity of three flavonoids, namely Luteolin, Naringenin, and Scutellarin, with a focus on identification and validation of their molecular targets in human breast cancer. Potential targets were screened using the ePharmaLib database, followed by in silico structure-based pharmacophore mapping and molecular docking. Further confirmation was achieved through in vitro biochemical assays and cell-based studies. HDAC4 and HDAC8 assays validated the enzyme inhibitions of flavonoids, particularly Luteolin. In breast cancer cell lines, apoptosis was induced by flavonoids, as viewed by fluorescence microscopy and flow cytometry. Among these, Luteolin exhibited the most potent cytotoxicity. Antioxidant activity assays showed that luteolin and Scutellarin strongly scavenged radicals similar to quercetin. Naringenin and Luteolin significantly enhanced catalase activity. In THP-1-derived macrophages, all three flavonoids significantly suppressed LPS-induced inflammation with reduced expression of pro-inflammatory cytokines at both RNA and protein levels. Collectively, results clearly pinpoint that Luteolin, Naringenin, and Scutellarin may be explored as therapeutic possibilities since they exhibit strong anticancer, antioxidant, and anti-inflammatory properties.

Cervical cancer, a leading global cause of female mortality, exhibits diverse molecular aberrations influencing gene expression and signaling pathways. Epigenetic factors, including histone deacetylases (HDACs) such as HDAC8 and HDAC6, along with microRNAs (miRNAs), play pivotal roles in cervical cancer progression. Recent investigations have unveiled miRNAs as potential regulators of HDACs, offering a promising therapeutic avenue. This study employed in-silico miRNA prediction, qRT-PCR co-expression studies, and Dual-Luciferase reporter assays to identify miRNAs governing HDAC8 and HDAC6 in HeLa, cervical cancer cells. Results pinpointed miR-497–3p and miR-324–3p as novel negative regulators of HDAC8 and HDAC6, respectively. Functional assays demonstrated that miR-497–3p overexpression in HeLa cells suppressed HDAC8, leading to increased acetylation of downstream targets p53 and α-tubulin. Similarly, miR-324–3p overexpression inhibited HDAC6 mRNA and protein expression, enhancing acetylation of Hsp90 and α-tubulin. Notably, inhibiting HDAC8 via miRNA overexpression correlated with reduced cell viability, diminished epithelial-to-mesenchymal transition (EMT), and increased microtubule bundle formation in HeLa cells. In conclusion, miR-497–3p and miR-324–3p emerge as novel negative regulators of HDAC8 and HDAC6, respectively, with potential therapeutic implications. Elevated expression of these miRNAs in cervical cancer cells holds promise for inhibiting metastasis, offering a targeted approach for intervention in cervical malignancy.

Aim: To develop novel non-carbohydrate inhibitors of human galectin-1 (GAL-1), we have designed a series of coumarin–benzimidazole hybrids. Methods: We synthesized and characterized the coumarin–be...

Unresponsiveness of the chronic myeloid leukemia (CML) patients to frontline therapy of imatinib results in either dose escalation or change of drug leading to increased toxicity and financial burden. We have previously demonstrated cyclooxygenase-2 (COX-2)-dependent expression of efflux pumps via Wnt-signalling pathway as the underlying mechanism of imatinib resistance in vitro in K562 cells. The present study aimed at evaluating the gene expression of COX-2 and 3 of the efflux pumps, MDR1, MRP1and ABCG2, in lymphocytes of CML patients (n = 50) treated with different doses of imatinib as a means to diagnose resistance development. The results clearly indicated that the dosage of imatinib treatment correlated with expression levels of of efflux pumps and the COX-2-GSK3β- β-catenin-LEF signaling molecules. Although further studies are warrented, the results indicate the predictive therapeutic biomarker value of COX-2 and MDR1 during follow-up visits for early diagosis of resistance development.

Severe Corona Virus Disease is characterized by angiocentric inflammation of lungs and cytokine storm leading to potentially fatal multiple organ failure. Several studies have shown the high levels of pro-inflammatory cytokines, indicative of a poor prognosis in COVID-19. Eicosanoids play an important role in the induction of inflammation and cytokine production, while anti-inflammatory and pro-resolving properties of some eicosanoic acid derivatives enable inflamed tissues to return to homeostasis through the resolution of inflammation by aiding the clearance of cell debris and downregulation of pro-inflammatory stimulants. This review attempts to provide an overall insight on the eicosanoids synthesis and their role in the resolution of inflammation in the context of Corona Virus infection.

The immunological findings from autopsies, biopsies, and various studies in COVID-19 patients show that the major cause of morbidity and mortality in COVID-19 is excess immune response resulting in hyper-inflammation. With the objective to review various mechanisms of excess immune response in adult COVID-19 patients, Pubmed was searched for free full articles not related to therapeutics or co-morbid sub-groups, published in English until 27 October 2020, irrespective of type of article, country, or region. Joanna Briggs Institute’s design-specific checklists were used to assess the risk of bias. Out of 122 records screened for eligibility, 42 articles were included in the final review. The review found that eventually, most mechanisms result in cytokine excess and up-regulation of Nuclear Factor-κB (NF-κB) signaling as a common pathway of excess immune response. Molecules blocking NF-κB or targeting downstream effectors like Tumour Necrosis Factor α (TNFα) are either undergoing clinical trials or lack specificity and cause unwanted side effects. Neutralization of upstream histamine by histamine-conjugated normal human immunoglobulin has been demonstrated to inhibit the nuclear translocation of NF-κB, thereby preventing the release of pro-inflammatory cytokines Interleukin (IL) 1β, TNF-α, and IL-6 and IL-10 in a safer manner. The authors recommend repositioning it in COVID-19.