Role of microRNAs in Lung Carcinogenesis Induced by Asbestos

Our plain-English summary of Role of microRNAs in Lung Carcinogenesis Induced by Asbestos, by R. Bersimbaev, O. Bulgakova, A. Aripova, et al (Journal of Personalized Medicine, 2021).

The study

• Authors: R. Bersimbaev, O. Bulgakova, A. Aripova, A. Kussainova, O. Ilderbayev
• Journal: Journal of Personalized Medicine
• Published: 2021;11(2)
• Type of article: Review
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

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.

In plain English

This article is a review, not a new study. The authors summarized published research on microRNAs (small molecules that help control gene activity) in lung cancer and on how asbestos changes microRNA levels. The article does not describe how the reviewed studies were chosen. From those studies, the authors listed 20 microRNAs reported to change with asbestos exposure: 10 higher and 10 lower. Thirteen came from one earlier study of 26 tumors and normal lung tissue control samples. The rest came from studies of lung tissue, serum or blood, including mesothelioma studies. Comparing this list with microRNAs involved in lung cancer, the authors identified miR-222, miR-34b and miR-34c as possible biomarkers of asbestos-induced lung cancer. They noted that three microRNAs described as tumor suppressors (let-7d, let-7e and miR-126) had higher levels in asbestos-exposed people. They also noted that microRNA findings in mesothelioma do not always match those in asbestos-induced lung cancer. The authors concluded that further studies are needed to know whether microRNAs can serve as biomarkers of asbestos lung damage for diagnosing lung cancer.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published studies; no search or selection method is described
• Who was studied: No new subjects. The review drew on published studies of lung tumors, serum and blood from patients (including asbestos-exposed lung cancer and mesothelioma patients) and on laboratory cell-line studies.
• Exposure: Asbestos exposure in general, as reported in the reviewed studies. The main findings do not distinguish fiber types; one reviewed cell study used chrysotile.
• Main results:
  • From the reviewed studies, the authors listed 20 microRNAs whose expression changed with asbestos exposure (Table 3): 10 with overexpression and 10 with down regulation.
  • Thirteen of the listed microRNAs came from one earlier study (Nymark and coauthors). That study analyzed 26 tumors and normal lung tissue control samples and reported eight microRNAs overexpressed and five downregulated in association with asbestos.
  • Comparing microRNAs involved in lung cancer with those changed by asbestos, the authors identified miR-222, miR-34b and miR-34c as possible biomarkers of asbestos-induced lung cancer.
  • Three microRNAs described as tumor suppressors (let-7d, let-7e and miR-126) had increased expression in individuals exposed to asbestos.
  • In a reviewed study, miR-20a and miR-103 were downregulated in the blood of asbestos-exposed malignant mesothelioma patients. Both act as oncomiRs in lung cancer, which the authors took to suggest different mechanisms in asbestos-induced mesothelioma and lung cancer.
• The authors' conclusion: The authors concluded that further studies are needed to answer whether microRNAs can be used as biomarkers of asbestos-caused lung damage for diagnosing lung cancer. They also concluded that microRNA changes reported in mesothelioma do not always correspond to asbestos-induced lung cancer.
• Limitations the authors state:
  • The authors stated that how asbestos fibers affect cells in lung cancer at the molecular level is currently not known.
  • The authors stated that there is no information on whether asbestos exposure changes the level of miR-138, a microRNA involved in DNA repair.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenesis, Lung Cancer, Malignant Transformation, Reactive Oxygen Species (ROS), Biomarker, Metastasis, Angiogenesis.

Related studies

• Extensive temporal transcriptome and microRNA analyses identify molecular mechanisms underlying mitochondrial dysfunction induced by multi-walled carbon nanotubes in human lung cells — P. Nymark, P. Wijshoff, et al. (2015)
• MicroRNA-98 is a prognostic factor for asbestos-induced mesothelioma — K. Kim, Y. Ko, et al. (2020)
• Mechanisms of asbestos-induced carcinogenesis — S. Toyokuni (2009)
• Ferroptosis-dependent extracellular vesicles from macrophage contribute to asbestos-induced mesothelial carcinogenesis through loading ferritin — F. Ito, K. Kato, et al. (2021)
• Iron addiction with ferroptosis-resistance in asbestos-induced mesothelial carcinogenesis: Toward the era of mesothelioma prevention — S. Toyokuni (2019)
• Biopersistent fiber-induced inflammation and carcinogenesis: lessons learned from asbestos toward safety of fibrous nanomaterials — H. Nagai, S. Toyokuni (2010)

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