The findings of mutations and the development of targeted therapies have improved lung cancer management. Still, the prognosis remains poor, and we need to know more about the genetic and epigenetic alterations in lung cancer. MicroRNAs are involved in crucial biological processes like carcinogenesis by regulating gene expression at the post‐transcriptional level. In this project, we have studied the microRNA expression of lung adenocarcinomas and corresponding normal lung tissue and correlated the expression with clinical data and EGFR‐ and KRAS‐mutational status. Agilent microarrays have been used, examining microRNA expression in 154 surgically resected lung adenocarcinomas and 20 corresponding normal lung tissue samples. Findings were confirmed by RT‐qPCR in the same cohort and in an independent cohort of 103 lung cancer patients. EGFR and KRAS mutation analyses were also performed. 129 microRNAs were significantly differentially expressed in lung adenocarcinomas compared with normal lung tissue, and 17 microRNAs were differentially expressed between EGFR‐mutated and EGFR wildtype tumors. We identified microRNAs associated with time to progression. We have identified several aberrantly expressed microRNAs that discriminate lung adenocarcinomas from normal lung tissue, and hence may be potential biomarkers for early detection. We have found microRNAs that are differentially expressed between EGFR‐mutated and EGFR wildtype lung adenocarcinomas, suggesting that microRNAs can be used as molecular biomarkers in classification. We hypothesize that microRNA expression can be used as biomarkers for clinical course.

Lung cancer, including both non-small cell lung cancer and small cell lung cancer, remains the leading cause of cancer-related mortality worldwide, representing 18% of the total cancer deaths in 2020. Many patients are identified already at an advanced stage with metastatic disease and have a worsening prognosis. Recent advances in the genetic understanding of lung cancer have opened new avenues for personalized treatments and targeted therapies. This review examines the latest discoveries in the genetics of lung cancer, discusses key biomarkers, and analyzes current clinical therapies based on this genetic information. It will conclude with a discussion of future prospects and potential research directions.

Background: MFSD2A (major facilitator superfamily domain containing 2) gene maps on chromosome 1p34 within a linkage disequilibrium block containing genetic elements associated with progression of lung cancer. Results: Here we show that MFSD2A expression is strongly downregulated in non-small cell lung cancer cell lines of different histotypes and in primary lung adenocarcinomas. Experimental modulation of MFSD2A in lung cancer cells is associated with alteration of mRNA levels of genes involved in cell cycle control and interaction with the extracellular matrix. Exogenous expression of MFSD2A in lung cancer cells induced a G1 block, impaired adhesion and migration in vitro, and significantly reduced tumor colony number in vitro (4- to 27-fold, P < 0.0001) and tumor volume in vivo (~3-fold, P < 0.0001). siRNA knockdown studies in normal human bronchial epithelial cells confirmed the role of MFSD2A in G1 regulation. Conclusion: Together these data suggest that MFSD2A is a novel lung cancer tumor suppressor gene that regulates cell cycle progression and matrix attachment.

Isopentenyladenosine (i⁶A) is a product of isopentenyltransferases and, in mammals, occurs either bound to tRNA or as a free nucleoside. Sporadic reports have suggested an anticancer effect of i⁶A, mostly on leukemia cells. The present analysis of 9 human epithelial cancer cell lines derived from different types of malignant tissue revealed complete suppression of clonogenic activity in 8 of the lines after exposure to i⁶A at a concentration of 10 μM. Mechanistic studies showed that i⁶A tumor suppressor activity is associated with inhibition of cell proliferation, a block in DNA synthesis and morphological changes. These results point to i⁶A and to its possible derivatives as a new potential class of wide-spectrum anticancer agents.

Alterations in the gene expression of organs in contact with the environment may signal exposure to toxins. To identify genes in lung tissue whose expression levels are altered by cigarette smoking, we compared the transcriptomes of lung tissue between 118 ever smokers and 58 never smokers. In all cases, the tissue studied was non-involved lung tissue obtained at lobectomy from patients with lung adenocarcinoma. Of the 17,097 genes analyzed, 357 were differentially expressed between ever smokers and never smokers (FDR < 0.05), including 290 genes that were up-regulated and 67 down-regulated in ever smokers. For 85 genes, the absolute value of the fold change was ≥2. The gene with the smallest FDR was MYO1A (FDR = 6.9 × 10⁻⁴) while the gene with the largest difference between groups was FGG (fold change = 31.60). Overall, 100 of the genes identified in this study (38.6%) had previously been found to associate with smoking in at least one of four previously reported datasets of non-involved lung tissue. Seven genes (KMO, CD1A, SPINK5, TREM2, CYBB, DNASE2B, FGG) were differentially expressed between ever and never smokers in all five datasets, with concordant higher expression in ever smokers. Smoking-induced up-regulation of six of these genes was also observed in a transcription dataset from lung tissue of non-cancer patients. Among the three most significant gene networks, two are involved in immunity and inflammation and one in cell death. Overall, this study shows that the lung parenchyma transcriptome of smokers has altered gene expression and that these alterations are reproducible in different series of smokers across countries. Moreover, this study identified a seven-gene panel that reflects lung tissue exposure to cigarette smoke.