Postoperative circulating tumor DNA can refine risk stratification in resectable lung cancer: results from a multicenter study.

Circulating tumor DNA (ctDNA) has potential as a promising biomarker for molecular residual disease (MRD) detection in lung cancer. As the next-generation sequencing standardized panel for ctDNA detection emerges, its clinical utility needs to be validated. We prospectively recruited 184 resectable lung cancer patients from four medical centers. Serial postoperative ctDNAs were analyzed by a standardized panel. A total of 427 postoperative plasma samples from 177 eligible patients were enrolled. ctDNA positivity after surgery was an independent predictor for disease recurrence and preceded radiological recurrence by a median of 6.6 months (range, 0.7-27.0 months). ctDNA-positive or -negative patients with tumors of any stage had similar disease-free survival (DFS). Patients who received targeted therapy had significantly improved DFS than those not receiving adjuvant therapy or receiving chemotherapy, regardless of baseline/preadjuvant ctDNA status. According to whether the ctDNA variants were detected in its matched tissue, they were classified into tissue derived and non-tissue derived. Patients with detectable postoperative ctDNA with tissue-derived mutations had comparable DFS with those with non-tissue-derived mutations. Collectively, we demonstrated that postoperative ctDNA has the potential to stratify prognosis and optimize tumor stage in resectable lung cancer. ctDNA variants not identified in tissue samples should be considered in MRD test.

Research on Random Drift Model Identification and Error Compensation Method of MEMS Sensor Based on EEMD-GRNN.

Random drift error is one of the important factors of MEMS (micro-electro-mechanical-system) sensor output error. Identifying and compensating sensor output error is an important means to improve sensor accuracy. In order to reduce the impact of white noise on neural network modeling, the ensemble empirical mode decomposition (EEMD) method was used to separate white noise from the original signal. The drift signal after noise removal is modeled by GRNN (general regression neural network). In order to achieve a better modeling effect, cross-validation and parameter optimization algorithms were designed to obtain the optimal GRNN model. The algorithm is used to model and compensate errors for the generated random drift signal. The results show that the mean value of original signal decreases from 0.1130 m/s2 to -1.2646 × 10-7 m/s2, while the variance decreases from 0.0133 m/s2 to 1.0975 × 10-5 m/s2. In addition, the displacement test was carried out by MEMS acceleration sensor. Experimental results show that the displacement measurement accuracy is improved from 95.64% to 98.00% by compensating the output error of MEMS sensor. By comparing the GA-BP (genetic algorithm-back propagation) neural network and the polynomial fitting method, the EEMD-GRNN method proposed in this paper can effectively identify and compensate for complex nonlinear drift signals.

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.

Genomic Landscape and Tumor Mutational Burden Determination of Circulating Tumor DNA in Over 5,000 Chinese Patients with Lung Cancer.

PURPOSE: Having emerged as a noninvasive and clinically applicable approach for molecular determination of lung cancer, a genomic overview of circulating tumor DNA (ctDNA) of large-scale cohort may be helpful in novel biomarker development and therapeutic innovation. EXPERIMENTAL DESIGN: Primary cohort encompasses 5,671 blood samples from 4,892 patients with lung cancer. Pair-wise tissue samples from 579 patients and additional 358 sample pairs were collected to evaluate the correlation between blood and tissue tumor mutational burden (TMB). Parallel sequencing with plasma/tissue and white blood cells was performed using a 1,021-gene panel. RESULTS: Histologic subtyping was the most relevant to ctDNA detectability independent of other demographic characteristics, with small cell lung cancer showing the highest detectability, ctDNA abundance, and blood TMB (bTMB). Mutational landscape demonstrated significant differences, and integrated clonality analysis highlighted distinct driver-pattern and functional pathway interaction among various subtypes. The clonality and concurrent genes of EGFR mutations could predict the therapeutic efficacy of tyrosine kinase inhibitors (TKI), and RB1 mutations in non-small cell lung cancer characterized a subset with high bTMB, elevated ctDNA level, and potential small cell transformation. Most importantly, we developed an adjusted algorithm for bTMB in samples with extremely low ctDNA level and validated its correlation with tissue TMB in an independent cohort. CONCLUSIONS: ctDNA could serve as a promising alternative in genomic profiling for lung cancer. The novel identification of ctDNA clonality and adjusted bTMB might improve therapeutic and prognostic evaluation. This dataset was also a valuable resource for the development of new therapeutic targets and new genomically guided clinical trials.

Statistical optimization for the production of recombinant cold-adapted superoxide dismutase in E. coli using response surface methodology.

Cold-adapted superoxide dismutase (SOD) with higher catalytic activity at lower temperature has great amount of applications in many aspects as an industrial enzyme. The application of recombinant enzyme in gene engineering and microbial fermentation technology is an effective way to obtain high-yield product. In this study, to obtain the recombinant SOD in E. coli (rPsSOD) with the highest activity, the Box-Behnken design was first applied to optimize the important parameters (lactose, tryptone and Tween-80) affecting the activity of rPsSOD. The results showed that the optimal fermentation conditions were Tween-80 (0.047%), tryptone (6.16 g/L), lactose (11.38 g/L). The activity of rPsSOD was 71.86 U/mg (1.54 times) as compared with non-optimized conditions. Such an improved production will facilitate the application of the cold-adapted rPsSOD.

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.

Cloning, expression, purification, and characterization of glutaredoxin from Antarctic sea-ice bacterium Pseudoalteromonas sp. AN178.

Glutaredoxins (Grxs) are small ubiquitous redox enzymes that catalyze glutathione-dependent reactions to reduce protein disulfide. In this study, a full-length Grx gene (PsGrx) with 270 nucleotides was isolated from Antarctic sea-ice bacterium Pseudoalteromonas sp. AN178. It encoded deduced 89 amino acid residues with the molecular weight 9.8 kDa. Sequence analysis of the amino acid sequence revealed the catalytic motif CPYC. Recombinant PsGrx (rPsGrx) stably expressed in E. coli BL21 was purified to apparent homogeneity by Ni-affinity chromatography. rPsGrx exhibited optimal activity at 30°C and pH 8.0 and showed 25.5% of the activity at 0°C. It retained 65.0% of activity after incubation at 40°C for 20 min and still exhibited 37.0% activity in 1.0 M NaCl. These results indicated that rPsGrx was a typical cold active protein with low thermostability.

Molecular cloning, expression and enzymatic characterization of glutathione S-transferase from Antarctic sea-ice bacteria Pseudoalteromonas sp. ANT506.

A glutathione S-transferase (GST) gene from Antarctic sea-ice bacteria Pseudoalteromonas sp. ANT506 (namely PsGST), was cloned and expressed in Escherichia coli. The open reading frame of PsGST comprised 654 bp encoding a protein of 217 amino acids with a calculated molecular size of 24.3 kDa. The rPsGST possesses the conserved amino acid defining the binding sites of glutathione (G-site) and substrate binding pocket (H-site) in GST N_3 family. PsGST was expressed in E. coli and the recombinant PsGST (rPsGST) was purified by Ni-affinity chromatography with a high specific activity of 74.21 U/mg. The purified rPsGST showed maximum activity at 40 °C and exhibited 14.2% activity at 0 °C. It was completely inactivated at 50 °C for 40 min. These results indicated that rPsGST was a typical cold active GST with low thermostability. The enzyme was little affected by H2O2 and Triton X-100, and 50.2% of the remaining activity was detected in the presence of high salt concentrations (2M NaCl). The enzymatic Km values for CDNB and GSH was 0.22 mM and 1.01 mM, respectively. These specific enzyme properties may be related to the survival environment of Antarctic sea ice bacteria.