PA1 cells containing a truncated DNA polymerase ß protein are more sensitive to gamma radiation.

PURPOSE: DNA polymerase ß (Polß) acts in the base excision repair (BER) pathway. Mutations in DNA polymerase ß (Polß) are associated with different cancers. A variant of Polß with a 97 amino acid deletion (PolßΔ), in heterozygous conditions with wild-type Polß, was identified in sporadic ovarian tumor samples. This study aims to evaluate the gamma radiation sensitivity of PolßΔ for possible target therapy in ovarian cancer treatment. MATERIALS AND METHODS: PolßΔ cDNA was cloned in a GFP vector and transfected in PA1 cells. Stable cells (PA1PolßΔ) were treated with 60Co sourced gamma-ray (0-15 Gy) to investigate their radiation sensitivity. The affinity of PolßΔ with DNA evaluated by DNA protein in silico docking experiments. RESULTS: The result showed a statistically significant (p < 0.05) higher sensitivity towards radiation at different doses (0-15 Gy) and time-point (48-72 hours) for PA1PolßΔ cells in comparison with normal PA1 cells. Ten Gy of gamma radiation was found to be the optimal dose. Significantly more PA1PolßΔ cells were killed at this dose than PA1 cells after 48 hours of treatment via an apoptotic pathway. The in silico docking experiments revealed that PolßΔ has more substantial binding potential towards the dsDNA than wild-type Polß, suggesting a possible failure of BER pathway that results in cell death. CONCLUSION: Our study showed that the PA1PolßΔ cells were more susceptible than PA1 cells to gamma radiation. In the future, the potentiality of ionizing radiation to treat this type of cancer will be checked in animal models.

Structure and biological properties of exopolysaccharide isolated from Citrobacter freundii.

This study aimed to investigate the molecular characterization, antioxidant activity in vitro, cytotoxicity study of an exopolysaccharide isolated from Citrobacter freundii. Firstly, the culture conditions were standardized by the Design of experiments (DoE) based approach, and the final yield of thecrude exopolysaccharide was optimized at 2568 ± 169 mg L-1. One large fraction of exopolysaccharide was obtained from the culture filtrate by size exclusion chromatography and molecular characteristics were studied. A new mannose rich exopolysaccharide (Fraction-I) with average molecular weight ~ 1.34 × 105 Da was isolated. The sugar analysis showed the presence of mannose and glucose in a molar ratio of nearly 7:2 respectively. The structure of the repeating unit in the exopolysaccharide was determined through chemical and 1D/2D- NMR experiments as: Finally, the antioxidant activity, and the cytotoxicity of the exopolysaccharide were investigated and the relationship with molecular properties was discussed as well.