miR-30d is related to asbestos exposure and inhibits migration and invasion in NCI-H2452 cells

The interaction between miRNAs and hazardous materials

Toxic agents are broadly present in the environment, households, and workplaces. Contamination of food and drinking water with these agents results in entry of these materials to the body. The crosstalk between these agents and microRNAs (miRNAs) affects pathoetiology of several disorders. These agents can influence the redox status, release of inflammatory cytokines and mitochondrial function. Altered expression of miRNA is involved in the dysregulation of several pathophysiological conditions and signaling pathways. These molecules are also implicated in the adaption to environmental stimuli. Thus, the interactions between miRNAs and toxic materials might participate in the hazardous effects of these materials in the body. This review describes the effects of the toxic materials on miRNAs and the consequences of these interactions on the human health.

A nontoxic dose of chrysotile can malignantly transform Met-5A cells, in which microRNA-28 has inhibitory effects

Chrysotile, which is classified as a class I carcinogen by the International Agency for Research on Cancer (IARC), has extensive application in the industry and can lead to lung or other cancers. However, whether chrysotile causes malignant mesothelioma and its molecular mechanism remain debatable. Thus, this study aimed to demonstrate the mesothelioma-inducing potential of chrysotile at the mesothelial cellular level and the function of microRNA-28 in malignantly transformed mesothelial MeT-5A cells. MeT-5A cells malignantly transformed by a nontoxic dose of chrysotile were named Asb-T, and miR-28 expression was downregulated in Asb-T cells. Restoration of miR-28 expression inhibited the proliferation, migration and invasion of Asb-T cells. We verified that IMPDH is a putative target of miR-28. The expression of IMPDH was significantly higher in Asb-T MeT-5A cells than in control cells, whereas the opposite trend was observed with miR-28 overexpression. Additionally, inhibition of IMPDH had similar effects as miR-28 overexpression. After miR-28 was elevated or IMPDH was inhibited, Ras activation was reduced, and its downstream pathways (the Erk and Akt signalling pathways) were inhibited. Surprisingly, the content of miR-28 in the blood of mesothelioma patients was higher than that in control subjects. Overall, nontoxic doses of chrysotile can cause malignant transformation of MeT-5A cells. Moreover, miR-28 inhibits the proliferation, migration and invasion of Asb-T MeT-5A cells, negatively regulates the expression of IMPDH through the Ras signalling pathway and may be an important therapeutic target.

Role of microRNAs in Lung Carcinogenesis Induced by Asbestos

MicroRNAs are a class of small noncoding endogenous RNAs 19–25 nucleotides long, which play an important role in the post-transcriptional regulation of gene expression by targeting mRNA targets with subsequent repression of translation. MicroRNAs are involved in the pathogenesis of numerous diseases, including cancer. Lung cancer is the leading cause of cancer death in the world. Lung cancer is usually associated with tobacco smoking. However, about 25% of lung cancer cases occur in people who have never smoked. According to the International Agency for Research on Cancer, asbestos has been classified as one of the cancerogenic factors for lung cancer. The mechanism of malignant transformation under the influence of asbestos is associated with the genotoxic effect of reactive oxygen species, which initiate the processes of DNA damage in the cell. However, epigenetic mechanisms such as changes in the microRNA expression profile may also be implicated in the pathogenesis of asbestos-induced lung cancer. Numerous studies have shown that microRNAs can serve as a biomarker of the effects of various adverse environmental factors on the human body. This review examines the role of microRNAs, the expression profile of which changes upon exposure to asbestos, in key processes of carcinogenesis, such as proliferation, cell survival, metastasis, neo-angiogenesis, and immune response avoidance.