Epigenetic Silencing of LMX1A Contributes to Cancer Progression in Lung Cancer Cells

Abstract

Epigenetic modification is considered a major mechanism of the inactivation of tumor suppressor genes that finally contributes to carcinogenesis. LIM homeobox transcription factor 1α (LMX1A) is one of the LIM-homeobox-containing genes that is a critical regulator of growth and differentiation. Recently, LMX1A was shown to be hypermethylated and functioned as a tumor suppressor in cervical cancer, ovarian cancer, and gastric cancer. However, its role in lung cancer has not yet been clarified. In this study, we used public databases, methylation-specific PCR (MSP), reverse transcription PCR (RT-PCR), and bisulfite genomic sequencing to show that LMX1A was downregulated or silenced due to promoter hypermethylation in lung cancers. Treatment of lung cancer cells with the demethylating agent 5-aza-2’-deoxycytidine restored LMX1A expression. In the lung cancer cell lines H23 and H1299, overexpression of LMX1A did not affect cell proliferation but suppressed colony formation and invasion. These suppressive effects were reversed after inhibition of LMX1A expression in an inducible expression system in H23 cells. The quantitative RT-PCR (qRT-PCR) data showed that LMX1A could modulate epithelial mesenchymal transition (EMT) through E-cadherin (CDH1) and fibronectin (FN1). NanoString gene expression analysis revealed that all aberrantly expressed genes were associated with processes related to cancer progression, including angiogenesis, extracellular matrix (ECM) remodeling, EMT, cancer metastasis, and hypoxia-related gene expression. Taken together, these data demonstrated that LMX1A is inactivated through promoter hypermethylation and functions as a tumor suppressor. Furthermore, LMX1A inhibits non-small cell lung cancer (NSCLC) cell invasion partly through modulation of EMT, angiogenesis, and ECM remodeling.

Two cell line models to study multiorganic metastasis and immunotherapy in lung squamous cell carcinoma

“…Fibrillin-1 ( FBN1 ), encoding an extracellular matrix glycoprotein that serves as a structural component of calcium-binding microfibrils, seems to play an important role in tumor-related immune infiltration and has been proposed as a prognostic and predictive biomarker for immune therapy against pancreatic ductal adenocarcinoma (PDAC) ( Luan et al, 2020 ). Finally, colony stimulating factor 2 receptor subunit beta (CSF2RB) has been shown to regulate epithelial-mesenchymal transition (EMT) in human lung cancer cells ( Wu et al, 2020 ; Rudisch et al, 2015 ). Our study also shows mutations in genes that are involved in mechanisms relevant in cell-cell adhesion, microtubule activity or extracellular matrix conformation, thereby indicating the presence of commonly altered functions in LUSC tumorigenesis.…”

DNA-methylation-induced silencing of DIO3OS drives non-small cell lung cancer progression via activating hnRNPK-MYC-CDC25A axis

“…8 Several protein-encoding genes have been identified as targets regulated by DNA methylation, such as ALDH2, LMX1A, and SLC22A18. [9][10][11] The hypermethylation or hypomethylation causes downregulation or overexpression of target genes, which further regulate NSCLC tumorigenesis and progression. 12 Apart from protein-encoding genes, several non-coding RNAs were also identified to be targets of DNA methylation, such as miR-21 and miR-196b.…”

“… 8 Several protein-encoding genes have been identified as targets regulated by DNA methylation, such as ALDH2 , LMX1A , and SLC22A18 . 9 , 10 , 11 The hypermethylation or hypomethylation causes downregulation or overexpression of target genes, which further regulate NSCLC tumorigenesis and progression. 12 …”

Alternatively Expressed Transcripts Analysis of Non-Small Cell Lung Cancer Cells under Different Hypoxic Microenvironment

“…e Oncomine database (https:// www.oncomine.org/) [11] and the Kaplan-Meier Plotter (https://kmplot.com/analysis/) [20] was used to determine the effect of differentially expressed genes (DEGs) under different concentrations of oxygen on the overall survival of NSCLC patients. e survival curve was downloaded from the following data links: TCGA CAARRAY GSE31210, GSE14814, GSE19188, GSE29013, GSE30219, GSE3141, GSE31908, GSE37745, GSE43580, GSE4573, GSE50081, GSE31908, and GSE8894.…”

“…e concept of tumor hypoxia was first presented in 1955, while studying tumor specimens obtained from lung cancer patients [6]. Over the next 60 years, scientists have gradually confirmed that hypoxia is a widespread characteristic in tumors and is closely related to tumor differentiation, angiogenesis, energy metabolism, invasion, and drug resistance [7][8][9][10][11]. Compared with normal cells, cancer cells are more adapted to grow in anoxic environments [12].…”