Exploration and validation of a combined Hypoxia and m6A/m5C/m1A regulated gene signature for prognosis prediction of liver cancer.

BACKGROUND: It is widely acknowledged that hypoxia and m6A/m5C/m1A RNA modifications promote the occurrence and development of tumors by regulating the tumor microenvironment. This study aimed to establish a novel liver cancer risk signature based on hypoxia and m6A/m5C/m1A modifications. METHODS: We collected data from The Cancer Genome Atlas (TCGA-LIHC), the National Omics Data Encyclopedia (NODE-HCC), the International Cancer Genome Consortium (ICGC), and the Gene Expression Omnibus (GEO) databases for our study (GSE59729, GSE41666). Using Cox regression and least absolute shrinkage and selection operator (LASSO) method, we developed a risk signature for liver cancer based on differentially expressed genes related to hypoxia and genes regulated by m6A/m5C/m1A modifications. We stratified patients into high- and low-risk groups and assessed differences between these groups in terms of gene mutations, copy number variations, pathway enrichment, stemness scores, immune infiltration, and predictive capabilities of the model for immunotherapy and chemotherapy efficacy. RESULTS: Our analysis revealed a significantly correlated between hypoxia and methylation as well as m6A/m5C/m1A RNA methylation. The three-gene prognosis signature (CEP55, DPH2, SMS) combining hypoxia and m6A/m5C/m1A regulated genes exhibited strong predictive performance in TCGA-LIHC, NODE-HCC, and ICGC-LIHC-JP cohorts. The low-risk group demonstrated a significantly better overall survival compared to the high-risk group (p < 0.0001 in TCGA, p = 0.0043 in NODE, p = 0.0015 in ICGC). The area under the curve (AUC) values for survival at 1, 2, and 3 years are all greater than 0.65 in the three cohorts. Univariate and Multivariate Cox regression analyses of the three datasets indicated that the signature could serve as an independent prognostic predictor (p < 0.001 in the three cohorts). The high-risk group exhibited more genome changes and higher homologous recombination deficiency scores and stemness scores. Analysis of immune infiltration and immune activation confirmed that the signature was associated with various immune microenvironment characteristics. Finally, patients in the high-risk group experienced a more favorable response to immunotherapy, and various common chemotherapy drugs. CONCLUSION: Our prognostic signature which integrates hypoxia and m6A/m5C/m1A-regulated genes, provides valuable insights for clinical prediction and treatment guidance for liver cancer patients.

Resibufogenin inhibited colorectal cancer cell growth and tumorigenesis through triggering ferroptosis and ROS production mediated by GPX4 inactivation.

Resibufogenin (RB) has been used for cancer treatment, but the underlying mechanisms are still unclear. This study aimed to investigate the effects of RB treatment on colorectal cancer (CRC) cells, and to determine the underlying mechanisms. The cell counting kit-8 assay was used to determine cell viability. Cell morphology was observed under light microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay was employed to detect cell apoptosis. Intracellular ferrous iron (Fe2+ ), malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species levels were detected by using commercial iron assay kit, MDA assay kit, GSH assay kit, and 2,7-dichlorodihydrofluorescein diacetate probes, respectively. The protein expressions were determined by Western blot and immunohistochemistry. RB inhibited cell viability in the CRC cell lines (HT29 and SW480) in a dose- and time-dependent manner, and caused cytotoxicity to the normal colonic epithelial cell line (NCM460) at high dose. Similarly, RB induced morphological changes in CRC cells from normal to round shape, and promoted cell death. Of note, RB triggered oxidative stress and ferroptotic cell death in CRC cells, and only ferroptosis inhibitors (deferoxamine and ferrostatin-1), instead of inhibitors for other types of cell death (apoptosis, autophagy, and necroptosis), reversed the inhibitory effects of RB on CRC cell proliferation. Furthermore, glutathione peroxidase 4 (GPX4) was inactivated by RB treatment, and overexpression of GPX4 alleviated RB-induced oxidative cell death in CRC cells. Consistently, the in vivo experiments validated that RB also triggered oxidative stress, and inhibited CRC cells growth and tumorigenicity in mice models. RB can inhibit CRC cells growth and tumorigenesis by triggering ferroptotic cell death in a GPX4 inactivation-dependent manner.

[Quality variation of wheat planted in different regions of Tibet and Beijing].

In order to supply experimental basis for developing high quality and special use wheat for Tibet, multi-varieties experiments in different regions were carried out to study the quality variation of wheat varieties during 1998 to 2001. Field trials of sowing in spring and in autumn were conducted in Linzhi, Rikaze, Lasa and Beijing, and 5 indices including grain protein content, wet gluten content, sedimentation value, falling number and grain hardness were determined. The results showed that the quality characters were significantly different among the varieties, and extremely significant among the sites of same variety. The protein content of grains had a positive correlation to the other 4 indices, and could be a core index in quality characters of wheat. The parameters of quality characters were higher in inland varieties than in Tibet ones, the latter appearing weak or medium gluten, and those of the same varieties were higher in Beijing than in Tibet. When inland varieties were planted in Tibet, the parameters of quality characters would be decreased. The same variety in 3 sites of Tibet had different quality characters. There was a positive correlation between ecological height (latitude x elevation) and growth-development duration of varieties, but a negative correlation between growth-development duration and protein content, and between ecological height and protein content. Medium gluten varieties should be mainly planted in Tibet, and some good inland varieties could be introduced and planted according to the quality regionalization.

[Effects of growing process and climatic conditions on grain quality of spring-sown wheat].

In the period of 1998-2000, 10 wheat varieties were used to study the effects of growth, development process and climatic conditions on the quality of wheat grains through spring sowing experiments in Beijing. The results showed that there were no significant variations on the quality traits among the varieties while there were significant variations among different years. The most significant negative correlation had been shown between the days from sowing to ripening and hardness of the grains and between the days from heading to ripening and the content of wet gluten of the grains. There was a significant negative correlation between day-night temperature difference during the period from heading to ripening and content of NIR protein. The results also showed that there was most significant negative correlation between total radiation, day-night temperature difference and the content of wet gluten of the grains. There was significant positive correlation between total sunlight and the content of wet gluten of the grains. The significant negative correlation was present between sedimentation value and total radiation, total sunlight, average temperature of daytime, day-night temperature difference.