DNA hypermethylation of sirtuin 1 (SIRT1) caused by betel quid chewing—a possible predictive biomarker for malignant transformation

Abstract

Background: DNA hypermethylation of tumor suppressor genes is observed in precancerous lesions and oral cancer of individuals with the habits of betel quid (BQ) chewing. SIRT1 has been identified as playing a role in the maintenance of epithelial integrity, and its alteration is often related to carcinogenesis. However, the methylation and transcription status of SIRT1 in patients with BQ chewing-related oral cancer has not been investigated. We examined the methylation status of SIRT1 in paraffin-embedded tissue samples of oral squamous cell carcinoma (OSCC) obtained from BQ chewing and non-chewing patients and in tissue samples from healthy control subjects. In addition, we examined whether the hypermethylation of SIRT1 followed by its transcriptional downregulation in the human gingival epithelial cells could be caused by arecoline, a major component of BQ. Furthermore, we investigated the methylation status of SIRT1 in smear samples of macroscopically healthy buccal mucosa from subjects with a habit of BQ chewing. Results: SIRT1 was significantly hypermethylated in tissue samples of OSCC from BQ chewers and non-chewers than in oral mucosa from healthy control subjects. Results also showed that the hypermethylation level of SIRT1 was significantly higher in OSCC of patients with BQ chewing habits than in those of non-chewing habits (p < 0.05). Our in vitro model showed that hypermethylation is followed by downregulation of the transcriptional level of SIRT1 (p < 0.05). The methylation levels of SIRT1 in the smear samples obtained from BQ chewing individuals were significantly higher than those in the samples obtained from individuals that did not chew BQ. The duration of BQ chewing habits was correlated positively to the frequency of SIRT1 hypermethylation (p < 0.05). Conclusions: Our results suggest that DNA hypermethylation of SIRT1 is involved in the occurrence of oral cancer in BQ chewing patients and that hypermethylation in the oral mucosa of BQ chewers could be a predictive marker for the occurrence of malignant transformation. This is the first report that showed DNA hypermethylation in clinically healthy oral epithelium of BQ chewers. Our study shows evidence that DNA hypermethylation may be an early event of oral carcinogenesis prior to observable clinical changes.

Retracted: Arecoline induces epithelial‐mesenchymal transformation and promotes metastasis of oral cancer by SAA1 expression

“…[2][3][4] In Western countries, the major risk factors for oral cancer are cigarette smoking, alcohol consumption, and HPV infection, whereas habitual chewing of areca nuts is considered an important risk factor for oral cancer and oral mucosal diseases in South and Southeast Asian countries. 5,6 Wang H et al reported that zinc finger protein 703 (ZNF703) can regulate the cell cycle and EMT by activating the PI3K/AKT/ GSK-3β signaling pathway in OSCC associated with areca nut. 7 Areca nut extracts can induce the generation of reactive oxygen species (ROS), therefore causing further autophagy and promoting OSCC metastasis.…”

Synergistic Effect of Dietary Betaines on SIRT1-Mediated Apoptosis in Human Oral Squamous Cell Carcinoma Cal 27

“…Under massive levels of DNA damage and loss of tumor suppressors or checkpoints, SIRT1 overexpression promotes cancer formation [15][16][17]. In oral cancer, SIRT1 expression correlated with tumor repression and its downregulation at transcriptional level is linked to malignant transformation, invasion and metastasis [18][19][20][21]. Moreover, in vitro studies on Cal 27 cells and xenograft mouse model support the potential of SIRT1 as tumor suppressor in oral cancer and provide the rationale for the use SIRT1 activators from dietary source in the setting of new prevention strategies [22].…”

A standardized extract of cultured Lentinula edodes mycelia downregulates cortactin in gemcitabine‑resistant pancreatic cancer cells

“…Membranes were incubated with the primary antibody overnight at 4˚C, washed three times with TBS-T, and incubated with horseradish peroxidase-conjugated secondary antibody (dilution 1:10,000; Jackson Immuno-Research Laboratories Inc.) for 1 h at room temperature. Bands of cortactin and actin were visualized by the enhanced chemiluminescence system (Clarity™ Western ECL Substrate; Bio-Rad) and LuminoGraph I (ATTO Corporation, Tokyo, Japan) and recorded using ImageSaver6 software (ATTO Corporation) (17). Cortactin and actin levels were quantified by analyzing each band intensity using CS Analyzer4 software (ATTO Corporation).…”