Metal Exposure Promotes Colorectal Tumorigenesis via the Aberrant N6-Methyladenosine Modification of ATP13A3.

Element contamination, including that from heavy metals, is associated with gastrointestinal tumorigenesis, but the effects and mechanisms of crucial element exposure associated with colorectal cancer remain unclear. We profiled 56 elements by ICP-MS and used logistic regression, LASSO, BKMR, and GAM to identify colorectal cancer-relevant elements. A series of biochemical experiments were performed to demonstrate the cytotoxicity and the mechanisms of malignant transformation after metal exposure. Using an elementomics approach, we first found that the metal thallium (Tl) was positively correlated with many toxic metals and was associated with a significantly increased risk of colorectal cancer. Acute exposure to Tl induced cytotoxicity and cell death by accelerating the generation of reactive oxygen species and DNA damage. Chronic exposure to Tl led to the inhibition of cell death and thereby induced the malignant transformation of normal colon cells and xenograft tumor formation in nude mice. Furthermore, we describe the first identification of a significant metal quantitative trait locus for the novel colorectal cancer susceptibility locus rs1511625 near ATP13A3. Mechanistically, Tl increased the level of aberrant N6-methyladenosine (m6A) modification of ATP13A3 via the METLL3/METTL14/ALKBH5-ATP13A3 axis to promote colorectal tumorigenesis. This study provides a basis for the development of public health strategies for reducing metal exposure among populations at high risk for colorectal cancer.

Genetic variants reduced POPs-related colorectal cancer risk via altering miRNA binding affinity and m6A modification.

Exposure to persistent organic pollutants (POPs) may contribute to colorectal cancer risk, but the underlying mechanisms of crucial POPs exposure remain unclear. Hence, we systematically investigated the associations among POPs exposure, genetics and epigenetics and their effects on colorectal cancer. A case-control study was conducted in the Chinese population for detecting POPs levels. We measured the concentrations of 24 POPs in the plasma using gas chromatography-tandem mass spectrometry (GC-MS/MS) and evaluated the clinical significance of POPs by calculating the area under the receiver operating characteristic curve (AUC). To assess the associations between candidate genetic variants and colorectal cancer risk, unconditional logistic regression was used. Compared with healthy control individuals, individuals with colorectal cancer exhibited higher concentrations of the majority of POPs. Exposure to PCB153 was positively associated with colorectal cancer risk, and PCB153 demonstrated superior accuracy (AUC=0.72) for predicting colorectal cancer compared to other analytes. On PCB153-related genes, the rs67734009 C allele was significantly associated with reduced colorectal cancer risk and lower plasma levels of PCB153. Moreover, rs67734009 exhibited an expression quantitative trait locus (eQTL) effect on ESR1, of which the expression level was negatively related to PCB153 concentration. Mechanistically, the risk allele of rs67734009 increased ESR1 expression via miR-3492 binding and m6A modification. Collectively, this study sheds light on potential genetic and epigenetic mechanisms linking PCB153 exposure and colorectal cancer risk, thereby providing insight into the accurate protection against POPs exposure.

Benzo[a]pyrene exposure affects colorectal cancer susceptibility by regulating ERß-mediated LINC02977 transcription.

Environmental pollutants known as polycyclic aromatic hydrocarbons (PAHs) are produced through the incomplete combustion of organic material. While PAHs have been investigated as genotoxicants, they can also operate through nongenotoxic pathways in estrogen-dependent malignancies, such as breast, cervical and ovarian cancer. However, whether PAHs induce colorectal cancer (CRC) risk through estrogenic effects is still illusive. Here, we systematically investigated the abnormal expression and activation of estrogen receptor beta (ERß) regulated by PAHs in CRC as well as the underlying mechanisms of ERß-mediated CRC risk. Based on the 300 plasma samples from CRC patients and healthy controls detected by GC-MS/MS, we found that the plasma concentrations of benzo[a]pyrene (BaP) were significantly higher in CRC cases than in healthy controls, with significant estrogenic effects. Moreover, histone deacetylase 2 (HDAC2)-induced deacetylation of the promoter decreases ERß expression, which is associated with poor overall survival and advanced tumor stage. The study also revealed that BaP and estradiol (E2) had different carcinogenic effects, with BaP promoting cell proliferation and inhibiting apoptosis, while E2 had the opposite effects. Additionally, this study mapped ERß genomic binding regions by performing ChIP-seq and ATAC-seq and identified genetic variants of rs1411680 and its high linkage disequilibrium SNP rs6477937, which were significantly associated with CRC risk through meta-analysis of two independent Chinese population genome-wide association studies comprising 2,248 cases and 3,173 controls and then validation in a large-scale European population. By integrating data from functional genomics, we validated the regulatory effect of rs6477937 as an ERß binding-disrupting SNP that mediated allele-specific expression of LINC02977 in a long-range chromosomal interaction manner, which was found to be highly expressed in CRC tissues. Overall, this study suggests that the different active effects on ERß by PAHs and endogenous E2 may play a crucial role in the development and progression of CRC and highlights the potential of targeting ERß and its downstream targets for CRC prevention and treatment.

The effects of antimony on Alzheimer's disease-like pathological changes in mice brain.

We have previously identified antimony (Sb) as a newly nerve poison which leads to neuronal apoptosis. However, the relationship between Sb exposure and Alzheimer's disease (AD) process lacks direct evidence. HE staining and Nissl staining showed significant nerve damage after Sb exposure. Therefore, we further evaluated Sb-associated AD risk by detecting accumulation of ß-amyloid protein (Aß) and neurofibrillary tangles (NFTs) in the brains of mice exposed to Sb for 4 and 8 weeks, and even 1 year. The results showed that dose of 20 mg/kg induced Aß accumulation, but not tau hyperphosphorylation after exposure for 4 week. Eight weeks later, both 10 and 20 mg/kg dramatically triggered Aß accumulation and increased tau phosphorylation at ser199. At the same time, 20 mg/kg could also increase tau phosphorylation at ser396 and number of NFTs. One years later, we found all of AD hallmarks detected in present study showed positive results in the brains of mice exposed to Sb at 10 and 20 mg/kg. In summary, our data provided direct evidence of Sb-associated AD risk, drawing more attention to Sb-triggered neurotoxicity.

Antimony, a novel nerve poison, triggers neuronal autophagic death via reactive oxygen species-mediated inhibition of the protein kinase B/mammalian target of rapamycin pathway.

Antimony (Sb), a naturally occurring metal present in air and drinking water, has been found in the human brain, and there is evidence of its toxic effects on neurobehavioral perturbations, suggesting that Sb is a potential nerve poison. Here, we provide the first study on the molecular mechanism underlying Sb-associated neurotoxicity. Mice exposed to antimony potassium tartrate hydrate showed significantly increased neuronal apoptosis. In vitro, Sb triggered apoptosis in PC12 cells in a dose-dependent manner. Mechanically, Sb triggered autophagy as indicated by increased expression of microtubule-associated protein 1 light chain 3-II (LC3-II) and accumulation of green fluorescent protein-tagged LC3 dots. Moreover, Sb enhanced autophagic flux and sequestosome 1 (p62) degradation. Subsequent analyses showed that Sb treatment decreased phosphorylation of protein kinase B (Akt) as well as the mammalian target of rapamycin (mTOR), while an Akt activator protected PC12 cells from autophagy. Moreover, the antioxidant N-acetylcysteine attenuated Sb-induced Akt/mTOR inhibition and decreased autophagy and apoptosis, with autophagy inhibition also playing a cytoprotective role. In vivo, mice treated with Sb showed higher expression of LC3-II and p62 in the brain, consistent with the in vitro results. In summary, Sb induced autophagic cell death through reactive oxygen species-mediated inhibition of the Akt/mTOR pathway.

Prenatal exposure to diesel exhaust PM2.5 programmed non-alcoholic fatty liver disease differently in adult male offspring of mice fed normal chow and a high-fat diet.

Air pollution is one of the leading preventable threats to public health. Emerging evidence indicates that exposure to environmental stressors is associated with abnormal foetal development. However, how prenatal exposure to diesel exhaust PM2.5 (DEP) predisposes adult offspring to the development of non-alcoholic fatty liver disease (NAFLD) remains unclear. To examine this, C57BL/6J mice were exposed to DEP or a vehicle before conception and during pregnancy and fed normal chow or a high-fat diet. Then, the hepatic fatty accumulation in the adult male offspring and possible molecular mechanisms were assessed. Our data showed that prenatal exposure to DEP on normal chow led to hepatic steatosis in adult male offspring with normal liver function. However, prenatal DEP exposure relieved the hepatic steatosis and liver function in offspring of mice fed a high-fat diet. Furthermore, prenatal exposure to DEP on normal chow increased lipogenesis and worsened fatty acid oxidation. The counteractive effect of prenatal DEP exposure on high-fat-diet-induced hepatic steatosis was produced through upregulated adenosine 5'-monophosphate-activated protein kinase, and this improved lipogenesis and fatty acid oxidation. Collectively, prenatal exposure to DEP programmed the development of NAFLD differently in the adult male offspring of mice fed normal chow and a high-fat diet, showing the pleotrophic effects of exposure to adverse environmental factors in early life.