Identification and Characterization of Cadmium-Related Genes in Liver Carcinoma

Aloe vera gel relieves cadmium triggered hepatic injury via antioxidative, anti-inflammatory, and anti-apoptotic routes

Aloe vera (AV) gel extracted from fresh AV leaves was chosen in this study to evaluate its antioxidant, anti-inflammatory, and antiapoptotic activities against cadmium (Cd) -induced liver injury. Forty Wistar male adult rats were equally divided into four groups. Group I (standard control) ingested with 2.5 ml/kg b.w. of physiological saline. Group II (Cd-intoxicated) received 3 mg/kg b.w./day of CdCl2 dissolved in saline. Group III (AV) received 200 mg/kg b.w./day of AV gel dissolved in saline. Group IV (Cd+AV) ingested with 200 mg/kg b.w./day of AV gel solution along with 3 mg/kg b.w. CdCl2. All groups were ingested orally by gavage for 3 consecutive weeks. Paraoxonase-1 (PON-1) and HSP70 were measured in serum. The deposited Cd level, nitric oxide content, lipid peroxidation, collagen-1 (COL-1), and metalloproteinase-9 (MMP-9) levels were all determined in liver tissue homogenates. Gene expression of NF-κB and IL-6, Bax, and Bcl2, as well as immunohistochemistry analysis of activated caspase-3, was performed. Results showed that ingestion of AV gel greatly relieved all oxidative stress due to Cd exposure, modulated the NF-κB, IL-6, Bax, and Bcl2 expression levels, and improved the apoptotic state. In conclusion, AV gel confirmed its potential ameliorating effect against liver injury induced due to Cd exposure.

Toxicity Tolerance in the Carcinogenesis of Environmental Cadmium

Cadmium (Cd) is an environmental toxicant of worldwide public health significance. Diet is the main non-workplace Cd exposure source other than passive and active smoking. The intestinal absorption of Cd involves transporters for essential metals, notably iron and zinc. These transporters determine the Cd body burden because only a minuscule amount of Cd can be excreted each day. The International Agency for Research on Cancer listed Cd as a human lung carcinogen, but the current evidence suggests that the effects of Cd on cancer risk extend beyond the lung. A two-year bioassay demonstrated that Cd caused neoplasms in multiple tissues of mice. Also, several non-tumorigenic human cells transformed to malignant cells when they were exposed to a sublethal dose of Cd for a prolonged time. Cd does not directly damage DNA, but it influences gene expression through interactions with essential metals and various proteins. The present review highlights the epidemiological studies that connect an enhanced risk of various neoplastic diseases to chronic exposure to environmental Cd. Special emphasis is given to the impact of body iron stores on the absorption of Cd, and its implications for breast cancer prevention in highly susceptible groups of women. Resistance to cell death and other cancer phenotypes acquired during Cd-induced cancer cell transformation, under in vitro conditions, are briefly discussed. The potential role for the ZnT1 efflux transporter in the cellular acquisition of tolerance to Cd cytotoxicity is highlighted.

Toxic mechanisms of cadmium and exposure as a risk factor for oral and gastrointestinal carcinomas

Incidence and mortality rates of gastrointestinal (GI) and oral cancers are among the highest in the world, compared to other cancers. GI cancers include esophageal, gastric, colon, rectal, liver, and pancreatic cancers, with colorectal cancer being the most common. Oral cancer, which is included in the head and neck cancers category, is one of the most important causes of death in India. Cadmium (Cd) is a toxic element affecting humans and the environment, which has both natural and anthropogenic sources. Generally, water, soil, air, and food supplies are reported as some sources of Cd. It accumulates in organs, particularly in the kidneys and liver. Exposure to cadmium is associated with different types of health risks such as kidney dysfunction, cardiovascular disease, reproductive dysfunction, diabetes, cerebral infarction, and neurotoxic effects (Parkinson's disease (PD) and Alzheimer's disease (AD)). Exposure to Cd is also associated with various cancers, including lung, kidney, liver, stomach, hematopoietic system, gynecologic and breast cancer. In the present study, we have provided and summarized the association of Cd exposure with oral and GI cancers.

Identification of circular RNA biomarkers for Pien Tze Huang treatment of CCl4‑induced liver fibrosis using RNA‑sequencing

Pien Tze Huang (PZH), a common hepatoprotective Traditional Chinese Medicine that has been found to be an effective treatment for carbon tetrachloride-induced hepatic damage, including liver fibrosis. Circular RNAs (circRNAs) serve a crucial role in regulating gene expression levels via circRNA/micro (mi)RNA/mRNA networks in several human diseases and biological processes. However, whether circRNAs are involved in the underlying mechanism of the therapeutic effects of PZH on liver fibrosis remains unclear. Therefore, the aim of the present study was to investigate these effects using circRNA expression profiles from PZH-treated fibrotic livers in model mice. A case-control study on >59,476 circRNAs from CCl₄-induced (control group, n=6) and PZH-treated (case group, n=6) mice was performed using circRNA sequencing in liver tissues. PZH treatment resulted in the differential expression of 91 circRNAs, including 58 upregulated and 33 downregulated circRNAs. Furthermore, the construction of competing endogenous networks also indicated that differentially expressed circRNAs acted as miRNA sponges. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of miRNA targets demonstrated that PZH-affected circRNAs were mainly involved in biological processes such as ‘positive regulation of fibroblast proliferation’, ‘cellular response to interleukin-1’ and ‘regulation of DNA-templated transcription in response to stress’ and in a number of important pathways, such as ‘TNF signaling pathway’, ‘PI3K-Akt signaling pathway’, ‘IL-17 signaling pathway’ and ‘MAPK signaling pathway’. To further validate the bioinformatics data, reverse transcription–quantitative PCR was performed on seven miRNA targets in a human hepatic stellate LX-2 cell model. The results suggested that seven of the miRNAs exhibited regulatory patterns that were consistent with those of the transcriptome sequencing results. Kaplan-Meier survival analysis demonstrated that the expression levels of dihydrodiol dehydrogenase and solute carrier family 7, member 11 gene were significantly associated with patient survival, 269 patients with liver hepatocellular carcinoma from The Cancer Genome Atlas database. To the best of our knowledge, this was the first study to provide evidence that PZH affects circRNA expression levels, which may serve important roles in PZH-treated fibrotic liver through the regulation of functional gene expression. In conclusion, the present study provided new insights into the mechanism underlying the pathogenesis of liver fibrosis and identified potential novel, efficient, therapeutic targets against liver injury.

Cadmium Exposure in Young Adulthood Is Associated with Risk of Nonalcoholic Fatty Liver Disease in Midlife

BACKGROUND

Studies have suggested that cadmium (Cd) may be involved in the etiology of nonalcoholic fatty liver disease (NAFLD), but available data in human is sparse.

AIMS

We aimed to examine Cd exposure in young adulthood in relation to prevalent NAFLD in midlife among American adults.

METHODS

This study included 2446 participants from the Coronary Artery Risk Development in Young Adults study with toenail Cd measurement at exam year 2 (baseline) and computed tomography quantification of liver fat at exam year 25. Toenail Cd concentrations were considered as a reliable marker of long-term exposure. NAFLD was defined if liver attenuation < 51 Hounsfield units after excluding other possible causes of liver fat. Multivariable-adjusted logistic regression models were used to estimate the odds ratio of NAFLD by Cd exposure.

RESULTS

Median toenail Cd concentration was 8.2 ppb (inter-quartile range 4.3-18.6 ppb). After 23 years from baseline, 580 participants with prevalent NAFLD (24% prevalence) in midlife were identified. Compared with individuals in the lowest quartile, those in the highest quartile of toenail Cd had a significantly higher odds of NAFLD (OR: 1.43, 95% CI: 1.02, 1.99, P for trend: 0.04) after adjustment for demographics, socioeconomics, major lifestyle factors, and baseline levels of body mass index, lipids, and fasting insulin. The association was not significantly modified by race, sex, BMI, or smoking status at baseline.

CONCLUSIONS

Toenail Cd concentration was associated with a higher odds of prevalent NAFLD23 years later in life in this cohort of US general population.

Lifestyle and Hepatocellular Carcinoma What Is the Evidence and Prevention Recommendations

Simple Summary

The increasing public health burden of Hepatocellular carcinoma (HCC) emphasizes the importance of defining important modifiable risk factors. In the following review, we will discuss the evidence for the relation of major lifestyle risk factors, mostly from large population-based studies. Generally, it is has been shown that healthy lifestyle habits, including minimizing obesity, eating a healthy diet, avoidance of smoking and alcohol, and increasing physical activity, have the potential to prevent HCC. Dietary composition is important beyond obesity. Consumption of n-3 polyunsaturated fatty acids, as well as fish and poultry, vegetables and fiber, are inversely associated with HCC, while red meat, saturated fat, cholesterol and sugar are related to increased risk. Data from multiple studies clearly show a beneficial effect for physical activity in reducing the risk of HCC. Smoking and alcohol can lead to liver fibrosis and liver cancer and jointly lead to an even greater risk.

Abstract

The increasing burden of hepatocellular carcinoma (HCC) emphasizes the unmet need for primary prevention. Lifestyle measures appear to be important modifiable risk factors for HCC regardless of its etiology. Lifestyle patterns, as a whole and each component separately, are related to HCC risk. Dietary composition is important beyond obesity. Consumption of n-3 polyunsaturated fatty acids, as well as fish and poultry, are inversely associated with HCC, while red meat, saturated fat, and cholesterol are related to increased risk. Sugar consumption is associated with HCC risk, while fiber and vegetable intake is protective. Data from multiple studies clearly show a beneficial effect for physical activity in reducing the risk of HCC. However, the duration, mode and intensity of physical activity needed are yet to be determined. There is evidence that smoking can lead to liver fibrosis and liver cancer and has a synergistic effect with alcohol drinking. On the other hand, an excessive amount of alcohol by itself has been associated with increased risk of HCC directly (carcinogenic effect) or indirectly (liver fibrosis and cirrhosis progression. Large-scale intervention studies testing the effect of comprehensive lifestyle interventions on HCC prevention among diverse cohorts of liver disease patients are greatly warranted.

Low-dose cadmium exposure facilitates cell proliferation by promoter hypermethylation of RASSF1A and DAPK1 genes

Cadmium (Cd) at low concentrations has a potential to promote cell proliferation. However, the molecular mechanisms of Cd-induced proliferation are not well understood. Here, we reported that Cd (0-500 nM) significantly promoted the proliferation of HepG2 cells as demonstrated by elevated cell viability, more EdU-positive cells and increased gene expression of KI-67 and COX-2. Meanwhile, the gene expression of DNA methyltransferases was found to be elevated while that of tumor suppressor genes DAPK1 and RASSF1A were decreased under Cd exposure. Correspondingly, the methylation level of promoters in DAPK1 and RASSF1A were increased. Specifically, the CpG sites at -461 (Chr3:50, 374, 481) of RASSF1A promoter, and that at -260 (Chr9:90, 113, 207), -239 (Chr9:90, 113, 228), and -68 (Chr9:90, 113, 399) of DAPK1 promoter, were significantly hypermethylated. Moreover, 5-azacytidine (an inhibitor of DNA methyltransferase) partly impaired Cd-induced promoter hypermethylation of RASSF1A and DAPK1 genes, increased their expressions and slowed down Cd-induced cell proliferation, suggesting that DNA methylation play an essential part in Cd-boosted proliferation. The study showed that Cd caused promoter hypermethylation of RASSF1A and DAPK1, decreasing their expression and leading to higher level of cell proliferation. Furthermore, Cd at low concentrations could influence DNA methylation, which may serve as the proliferative mechanism of Cd.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

Cadmium causes hepatopathy by changing the status of DNA methylation in the metabolic pathway

Toxicity caused by the heavy metal Cadmium leads to liver diseases; this finding has generated interest among researchers. We detected DNA methylation using Whole Genome Bisulfite Sequencing (WGBS) to study the relationship between Cadmium exposure and liver damage. Forty-eight Sprague-Dawley rats were randomly divided into six groups, and given normal saline or 2.5, 5, 10, 20, and 40 mg/kg body weight per day CdCl₂ by gavage. Twelve weeks later, their liver tissues were collected for pathological examination and DNA extraction. Increased exposure to Cadmium led to a reduction in the amount of weight gain as well as pathological degeneration and necrosis of liver cells of the rats. Using WGBS, we found that DNA methylation changes in the high-dose exposure group were more remarkable, and most of the changes occurred in the gene promoter region. GO enrichment analysis showed that the genes were enriched in the biological process of "response to stimulus." KEGG analysis revealed that metabolic pathways, like MAPK, PI3K-Akt and cAMP, had the largest number of enriched genes. Using Integrative Genomics Viewer (IGV), the demethylation of F2rl3 after Cadmium poisoning was established. This finding may explain why there are changes in liver metabolism after Cadmium poisoning.

Molecular Mechanism of Aflatoxin-Induced Hepatocellular Carcinoma Derived from a Bioinformatics Analysis

Exposure to aflatoxin is considered to be one of the causes of hepatocellular carcinoma (HCC). With the development of bioinformation, we sought to reveal the occurrence and development of aflatoxin-induced HCC through data research. We identified differentially expressed genes (DEGs) of datasets GSE127791 (Aflatoxin-treated pluripotent stem cell derived human hepatocytes vs. controls) and GSE64041 (liver carcinoma with unknown cause vs. non-cancerous tissue) by GEO2R to find the common DEGs. Gene ontology (GO) and KEGG path enrichment analysis were used to annotate the function of DEGs. Hub genes were screened from identified DEGs by protein-protein interaction (PPI) network analysis. The prognostic value of hub genes in cancer databases were evaluated. We obtained 132 common DEGs and 11 hub genes. According to cluster analysis and protein co-expression networks, we screened out the key genes, histidine-rich glycoprotein (HRG) and phosphoenolpyruvate carboxykinase 2 (PCK2). Oncomine database and survival curve analysis showed that the decline in HRG and PCK2 expression in the development of HCC indicated poor prognosis. We speculated that the decreased expression of HRG and PCK2 after aflatoxin exposure to hepatocyte may be related to aflatoxin induced hepatocyte injury and carcinogenesis. In addition, the decreased expression of HRG and PCK2 in the occurrence and development of HCC suggests a poor prognosis of HCC.

Overexpression of SLC7A11: a novel oncogene and an indicator of unfavorable prognosis for liver carcinoma

AIM

SLC7A11 is a gene that encodes a cystine-glutamate antiporter, which has been detected to be overexpressed in various cancers. Thus, we aimed to validate its expression and clinical significance in liver cancer.

METHODS

Bioinformatic analysis was conducted and a tissue microarray was utilized for detecting SLC7A11 expression in liver cancer tissues by immunohistochemistry assay.

RESULTS

High expressions of SLC7A11 have no association with clinical parameters such as age, sex and clinical stages, except for advanced pathological stages. Cox regression analysis revealed that SLC7A11 might be an independent prognostic factor for liver cancer patients.

CONCLUSION

SLC7A11 overexpression might be a novel biomarker and a potential unfavorable prognostic factor as well as a potential therapeutic target for liver carcinoma.