Genome‐wide DNA methylation changes in oral submucous fibrosis

Abstract

Objective Oral submucous fibrosis (OSF) is a debilitating potentially malignant condition of the buccal cavity characterized by extensive extracellular matrix deposition resulting in stiffness and trismus. As OSF is a progressive disease, we hypothesized that there would be extensive epigenetic changes in OSF tissues. Materials and Methods Using the Infinium HumanMethylation450 BeadChip Array, we analyzed gross DNA methylation changes in seven OSF tissues compared to five controls. Comparison with transcriptomic data and pathway analyses was conducted to find commonly regulated genes. Results A total of 3,294 differentially methylated regions mapping to 857 genes were identified. Comparison with transcriptome data revealed 38 downregulated‐hypermethylated genes and 55 hypomethylated‐upregulated genes. Using methylation‐specific and qRT‐PCR, aberrant hypomethylation and increased expression of FGF13, RPS6KA3, and ACSL4 genes were confirmed. Pathways involved in insulin signaling, ubiquitin‐mediated proteolysis, nicotine addiction, and RAS/MAPK pathways were dysregulated, among others. Intriguingly, numerous genes located on the X chromosome were dysregulated in OSF tissues as the transcript for XIST gene was downregulated due to hypermethylation of the XIST promoter. Conclusions This study highlights global epigenetic dysregulation of tissues of the oral cavity in OSF patients and hints at possible X chromosomal dysregulation, previously not implicated in the pathogenesis of OSF.

N6‐methyladenosine modification contributes to arecoline‐mediated oral submucosal fibrosis

“…10 Paramita Kundu et al found that the transcript for XIST located on the X chromosome was downregulated due to hypermethylation of the XIST promoter in OSF tissues. 6 Xu et al…”

“…A recent study shows that SMAD2/3 promotes binding of the m6A methyltransferase METTL3–METTL14 complex to a subset of transcripts involved in early cell fate decisions 10 . Paramita Kundu et al found that the transcript for XIST located on the X chromosome was downregulated due to hypermethylation of the XIST promoter in OSF tissues 6 . Xu et al found that methylation of CpG islands in E‐cadherin and COX‐2 occurred frequently in patients with OSF 7 .…”

“…5 Epigenetics modifications, including DNA methylation and histone modification, have been reported as part of the pathogenesis of OSF. [6][7][8][9] However, the role and the mechanism of arecoline-induced activation of TGF-β signaling pathway on N6-methyladenosine (m6A) modification remain unclear in OSF research field. Studies have shown that TGF-β can enhance m6A modification, 10 suggesting that TGFβ-mediated m6A modification may play an important role in arecolineinduced OSF.…”

“…Under arecoline stimulation, the expression of TGF‐β2, SMAD3, FN1, and other TGF‐β signals in epithelial cells is upregulated in epithelial cells, leading to activation of TGF‐β signaling pathway, which in turn leads to the occurrence and development of OSF 5 . Epigenetics modifications, including DNA methylation and histone modification, have been reported as part of the pathogenesis of OSF 6–9 …”

Substance P and Neurokinin 1 Receptor in Chronic Inflammation and Cancer of the Head and Neck: A Review of the Literature

“…Nevertheless, these molecular events could also play oncogenic roles in other oral, potentially malignant disorders, such as proliferative verrucous leukoplakia, where the presence of a band-like lymphocytic chorionic infiltrate constitutes an unspecific histopathologic feature affecting up to 30% of patients [ 49 ]. Furthermore, increased levels of cytokines (e.g., interleukin-6 and tumour necrosis factor alpha) have also been reported in patients with oral lichen planus [ 50 ], oral submucous fibrosis [ 51 ] and oral leukoplakia [ 52 ]. In head and neck cancer, as previously mentioned, inflammation is a well-established hallmark, and numerous oncogenic mechanisms have been documented [ 39 ], e.g., the infiltration of inflammatory cells facilitating tumour development through the regulation of growth factors from mitogenic signalling pathways [ 53 ], the attenuation of the host immune response to tumour cells [ 54 ], or the determination of cytokines and chemokines playing key roles by promoting angiogenesis, proliferation and the immune cell response [ 55 , 56 , 57 ].…”