Single-cell profiling of the copy-number heterogeneity in colorectal cancer

Background:With functionally heterogeneous cells,tumors comprise a complex ecosystem to promote tumor adaptability and evolution under strong selective pressure from the given microenvironment.Diversifying tumor cells or intra-tumor heterogeneity is essential for tumor growth,invasion,and immune evasion.However,no reliable method to classify tumor cell subtypes is yet available.In this study,we introduced the single-cell sequencing combined with copy number characteristics to identify the types of tumor cells in microsatellite stable(MSS)colorectal cancer(CRC).Methods:To characterize the somatic copy number alteration(SCNA)of MSS CRC in a single cell profile,we analyzed 26 tissue samples from 19 Korean patients(GSE132465,the Samsung Medical Center[SMC]dataset)and then verified our findings with 15 tissue samples from five Belgian patients(GSE144735,the Katholieke Universiteit Leuven 3[KUL3]dataset).The Cancer Genome Atlas(TCGA)cohort,GSE39582 cohort,and National Cancer Center(NCC)cohort(24 MSS CRC patients were enrolled in this study between March 2017 and October 2017)were used to validate the clinical features of prognostic signatures.Results:We employed single cell RNA-sequencing data to identify three types of tumor cells in MSS CRC by their SCNA characteristics.Among these three types of tumor cells,C1 and C3 had a higher SCNA burden;C1 had significant chromosome 13 and 20 amplification,whereas C3 was the polar opposite of C1,which exhibited deletion in chromosome 13 and 20.The three types of tumor cells exhibited various functions in the tumor microenvironment and harbored different mutations.C1 and C2 were linked to the immune response and hypoxia,respectively,while C3 was critical for cell adhesion activity and tumor angiogenesis.Additionally,one gene(OLFM4)was identified as epithelium-specific biomarker of better prognosis of CRC(TCGA cohort:P=0.0110;GSE39582 cohort:P=0.0098;NCC cohort:P=0.0360).Conclusions:On the basis of copy number characteristics,we illustrated tumor heterogeneity in MSS CRC and identified three types of tumor cells with distinct roles in tumor microenvironment.By understanding heterogeneity in the intricate tumor microenvironment,we gained an insight into the mechanisms of tumor evolution,which may support the development of therapeutic strategies.

Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China

Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls （PCBs） in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatography- tandem mass spectrometry （GC-MS/MS）. The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocyclohexanes （I-ICHs）, hexachlorobenzene （HCB） and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels.

Removal of 17β-estradiol in laccase catalyzed treatment processes

The removal of 17β-estradiol （E2） in laccase catalyzed oxidative coupling processes was systematically studied in this work. We focused on the influence of pH and natural organic matter （NOM） on the performance of the enzymatic treatment processes. It was found that the optimal pH for E2 removal was between 4 and 6. The removal of E2 was slightly inhibited in the presence of NOM. Enzymatic transformation of E2 was second-order in kinetics with first-order to both the concentrations of the enzyme and contaminant. Mass spectrum （MS） analysis suggested that coupling products were formed through radical-radical coupling mechanism. The results of this study demonstrated that laccase catalyzed oxidative coupling process could potentially serve as a treatment strategy to control steroid estrogens.

Transformation of triclosan by a novel cold-adapted laccase from Botrytis sp. FQ

This work investigated the transformation of triclosan （TCS） by the laccase produced by a pathogen isolated from rotten tomato. The pathogen was characterized as Bot^tis sp. FQ, belonging to subphylum Deuteromw＇otina. The laccase exhibited cold-adaptation with relatively high activity at 20℃. The laccase could effectively transform TCS. Approximately 62% TCS could be removed at dose of 1.0 unit·mL^-1 in 120min. The reaction rate appeared to be pseudo-first-order to the concentration of the substrate, suggesting the laccase activity remained stable during the reaction. Transformation products of TCS were analyzed by mass spectrometry and it was revealed that TCS dimers were formed via radical coupling pathways. During this process, laccase catalyzed oxidation of TCS to form a radical intermediate is the rate limiting step. However, this step can be reversed by humic acid. Overall, the laccase showed great potential in the treatment of phenolic contaminants. Since laccase is widely presented in natural environment, this study also revealed an important pathway involved in the transformation of phenolic contaminants in the environment.