Cloning, expression and biochemical characterization of recombinant superoxide dismutase from Antarctic psychrophilic bacterium Pseudoalteromonas sp. ANT506.

In this study, a superoxide dismutase gene (PsSOD) from Pseudoalteromonas sp. ANT506 was cloned and over expressed in Escherichia coli. The PsSOD has an open reading frame of 582 bp with a putative product of 193 amino acid residue and an estimated molecular size of 21.4 kDa. His-tagged PsSOD was subsequently purified 12.6-fold by Ni-affinity chromatography and the yield of 22.9%. The characterization of the purified rPsSOD exhibited maximum activity at 30 °C and pH 8.0. The enzyme exhibited 13.9% activity at 0 °C and had high-thermo lability at higher than 50 °C. rPsSOD exhibited well capability to 2.5 M NaCl (62.4%). These results indicated that rPsSOD exhibited special catalytic properties.

The ctDNA-based postoperative molecular residual disease status in different subtypes of early-stage breast cancer.

Background: Breast cancer is a highly heterogeneous disease. Early-stage, non-metastatic breast cancer is considered curable after definitive treatment. Early detection of tumor recurrence and metastasis through sensitive biomarkers is helpful for guiding clinical decision-making and early intervention in second-line treatment, which could improve patient prognosis and survival. Methods: In this real-world study, we retrospectively analyzed 82 patients with stages I to III breast cancer who had been analyzed by molecular residual disease (MRD) assay. A total of 82 tumor tissues and 224 peripheral blood samples were collected and detected by next-generation sequencing (NGS) based on a 1,021-gene panel in this study. Results: MRD positivity was detected in 18 of 82 patients (22.0%). The hormone receptor-/human epidermal growth factor receptor 2+ (HR-/HER2+) subgroup had the highest postoperative MRD detection rate at 30.8% (4/13). The BRCA2 and SLX4 genes were significantly enriched in all patients in the MRD positive group and FGFR1 amplification was significantly enriched in the MRD negative group with HR+/HER2-. The number of single nucleotide variants (SNVs) in tissue samples of MRD-positive patients was higher than that of MRD-negative patients (11.94 vs. 8.50 SNVs/sample). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that there was a similar biological function of the tumor-mutated genes in the 2 MRD status groups. Conclusions: This real-world study confirmed that patient samples of primary tumor tissue with different MRD status and molecular subtypes had differential genetic features, which may be used to predict patients at high risk for recurrence.