Augmentation of Transforming Growth Factor-β-induced Epithelial to Mesenchymal Transition by Interleukin-1β: Role of DNA Methylation

Lung cancer is a leading cause of cancer-related deaths worldwide. A better understanding of

mechanisms related to tumor initiation, progression and metastasis might help develop better

prevention and treatment regimens. Epithelial to mesenchymal transition (EMT) is related to

metastasis and the development of therapy resistance. The aim of our study is to determine how inflammatory cytokine Interleukin-1 (IL-1) enhances transforming growth factor beta (TGF-β) induced EMT in A549 lung adenocarcinoma cells, and whether regulation of DNA methylation is involved in this enhancement. Cells in 4 treatment groups (IL-1 alone, TGF-β alone, IL-1 and TGF-β cotreatment and untreated control) were analyzed over a 96-hour period. Total RNA and genomic DNA were isolated at 24, 48, 72 and 96 hours. RT-PCR was used to measure mRNA levels of DNA methylating and DNA demethylating enzymes as well as established markers of EMT progression. Results of RT-PCR showed no significant difference in DNMT1 andDNMT3a mRNA expression between TGF-β alone and TGF-β-IL1 cotreatment. However, IL-1 significantly decreased TET-1 mRNA expression as compared to untreated controls, and inhibited TGF-β induction of TET-1 at 24 and 48 hours. Future experiments will examine changes in global levels of 5mC and 5hmC, as well as DNMT and TET enzyme activity. We hypothesize that decreased TET activity facilitates early steps in EMT transition initiated by TGF-β.