Genome-wide long noncoding RNA and mRNA expression profiles demonstrate associations between exposure to inorganic elements and the risk of developing hepatocellular carcinoma

Integrating transcriptome and metabolomics analyses of hepatocellular carcinoma to discover novel biomarkers and drug targets

BACKGROUND

Hepatocellular carcinoma (HCC) ranks sixth in incidence and third in mortality among all cancers. Chronic infection by hepatitis B and C viruses are the predominant risk factors for HCC, but other factors related to metabolic disorders including diabetes and obesity are also involved.

METHODS

Ten male HCC patients with chronic HBV infection were included in this study. Primary HCC tissues were obtained from all study participants following liver resection. Normal tissues that were simultaneously collected served as the controls and were defined as tissue at least 5 cm from the tumor edge. Tissues were subjected to untargeted metabolomics and transcriptome analyses.

RESULTS

We identified 31 and 41 differentially expressed metabolites (DEMs) in positive and negative ion modes, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 15 DEMs were enriched in ABC transporters, nine in purine metabolism, eight in central carbon metabolism in cancer, and seven in biosynthesis of amino acids. Regarding the transcriptome analysis, 1,224 significantly up-regulated and 887 down-regulated RNAs were found. KEGG pathway analysis revealed that the most significantly enriched pathways were metabolic pathways. Integrated analysis showed seven pathways that were highly activated in HCC tissues including PI3K/Akt, ABC transporters, caffeine metabolism, carbon metabolism, biosynthesis of amino acids, arginine biosynthesis, alanine, aspartate, and glutamate metabolism.

CONCLUSION

Some DEMs could be biomarkers or therapeutic targets for HCC. Moreover, we found that MAGEB2 was significantly elevated in HCC tissues for the first time, and its association with HCC needs to be explored by functional studies.

Long noncoding RNAs in hepatitis B virus replication and oncogenesis

Several diverse long noncoding RNAs (lncRNAs) have been identified to be involved in hepatitis B virus (HBV) replication and oncogenesis, especially those dysregulated in HBV-related hepatocellular carcinoma (HCC). Most of these dysregulated lncRNAs are modulated by the HBV X protein. The regulatory mechanisms of some lncRNAs in HBV replication and oncogenesis have been characterized. Genetic polymorphisms of several lncRNAs affecting HBV replication or oncogenesis have also been studied. The prognosis of HCC remains poor. It is important to identify novel tumor markers for early diagnosis and find more therapeutic targets for effective treatments of HCC. Some dysregulated lncRNAs in HBV-related HCC may become biomarkers for early diagnosis and/or the therapeutic targets of HCC. This mini-review summarizes these findings briefly, focusing on recent developments.

Inorganic elements in occupational settings: A review on the effects on telomere length and biology

The past decades have shown that telomere crisis is highly affected by external factors. Effects of human exposure to xenobiotics on telomere length (TL), particularly in their workplace, have been largely studied. TL has been shown to be an efficient biomarker in occupational risk assessment. This is the first review focusing on studies about the effects on TL from occupational exposures to metals (lead [Pb] and mixtures), and particulate matter (PM) related to inorganic elements. Data from 15 studies were evaluated regarding occupational exposure to metals and PM-associated inorganic elements and impact on TL. Potential complementary analyses and subjects' background (age, length of employment and gender) were also assessed. There was limited information on the correlations between work length and TL dynamics, and that was also true for the correlation between age and TL. Results indicated that TL is affected differently across the types of occupational exposure investigated in this review, and even within the same exposure, a variety of effects can be observed. Fifty-three percent of the studies observed decreased TL in occupational exposure among welding fumes, open-cast coal mine, Pb and PM industries workers. Two studies focused particularly on the levels of metals and association with TL, and both linear and non-linear associations were found. Interestingly, TL modifications were accompanied by increase in DNA damage in 7 out of 8 studies that investigated it, measured either by Cytokinesis-block Micronucleus Assay or Comet assay. Five studies also investigated oxidative stress parameters, and 4 of them found increased levels of oxidative damage along with TL impairment. Oxidative stress is one of the main mechanisms by which telomeres are affected due to their high guanine content. Our review highlights the need of further studies accessing TL in simultaneous occupational exposure to mixtures of xenobiotics.