Among the genotoxic drug regimens, doxorubicin (DOX) is known for its high-dose side effects in several carcinomas, including cervical cancer. This study reports on testing the combined use of a DOX genotoxic drug and SCR-7 non-homologous end joining (NHEJ) inhibitor for HeLa cells. An in vitro DNA damaging assay of DOX was performed on plasmid and genomic DNA substrate. In vitro cytotoxicity was investigated using trypan blue dye exclusion, DNA metabolizing, and propidium iodide-based flow cytometric assays. DOX (between 20–100 μM) displayed clear DNA binding and interaction, such as the shearing and smearing of plasmid and genomic DNA. DNA metabolizing assay data indicate that HeLa lysate with DOX and SCR-7 treatment exhibited better in vitro plasmid DNA stability compared with DOX treatment alone. SCR-7 augmented the effects of low-dose DOX by demonstrating enhanced cell death from 15% to 50%. The flow cytometric data also supported that the combination of SCR-7 with DOX lead to a 23% increase in propidium iodide-based HeLa staining, thus indicating enhanced death. In summary, the inhibition of NHEJ DNA repair pathway can potentiate low-dose DOX to produce appreciable cytotoxicity in HeLa cells.
Cell Death ; DNA ; DNA Damage ; DNA End-Joining Repair ; DNA Repair ; Doxorubicin* ; Drug Therapy ; Genomic Instability ; HeLa Cells* ; Humans ; In Vitro Techniques ; Plasmids ; Propidium ; Trypan Blue ; Uterine Cervical Neoplasms

There is a lack of evidence regarding the use of betel quid (BQ) and its potential contribution to oral cancer. Limited attention has been directed towards investigating the involvement of BQ-derived organic acids in the modulation of metabolic-epigenomic pathways associated with oral cancer initiation and progression. We employed novel protocol for preparing saliva-amalgamated BQ filtrate (SABFI) that mimics the oral cavity environment. SABFI and saliva control were further purified by an in-house developed vertical tube gel electrophoresis tool. The purified SABFI was then subjected to liquid chromatography-high resolution mass spectrometry analysis to identify the presence of organic acids. Profiling of SABFI showed a pool of prominent organic acids such as citric acid. malic acid, fumaric acid, 2-methylcitric acid, 2-hydroxyglutarate, cis-aconitic acid, succinic acid, 2-hydroxyglutaric acid lactone, tartaric acid and β-ketoglutaric acid. SABFI showed anti-proliferative and early apoptosis effects in oral cancer cells. Molecular docking and molecular dynamics simulations predicted that SABFI-derived organic acids as potential inhibitors of the epigenetic demethylase enzyme, Ten-Eleven Translocation-2 (TET2). By binding to the active site of α-ketoglutarate, a known substrate of TET2, these organic acids are likely to act as competitive inhibitors. This study reports a novel approach to study SABFI-derived organic acids that could mimic the chemical composition of BQ in the oral cavity. These SABFI-derived organic acids projected as inhibitors of TET2 and could be explored for their role oral cancer.