5-Aza-CdR promotes partial MGMT demethylation and modifies expression of different genes in oral squamous cell carcinoma

Astaxanthin Increases Tumor Suppressor Gene Expression and Affects Cellular Biological Behavior in Oral Dysplastic Keratinocytes by Regulating DNA Methylation

BACKGROUND

The inactivation of tumor suppressor genes (TSGs) caused by abnormal DNA methylation is confirmed to be widely present in oral potential malignant diseases (OPMDs). Carotenoids like lycopene and astaxanthin can regulate DNA methylation and exert anticancer effects. Therapeutic effect of astaxanthin in OPMDs and oral squamous cell carcinoma (OSCC) models is confirmed, but the relationship between the anti-cancer ability of astaxanthin and its DNA methylation regulation ability remains unclear.

METHODS

Whole-genome bisulfite sequencing (WGBS) were used to provide biological information associated with DNA methylation. Methylation specific PCR was used to detect the methylation level of specific sites. Related markers were evaluated by qRT-PCR and western blot. CCK8 assay, cell scratch assay, flow cytometric analysis were performed to investigate the cell viability, migration, cell cycle, and apoptosis after treated with concentrations of astaxanthin.

RESULTS

WGBS revealed that HOXA3 and SOX1 were the TSGs with significant differences in promoter CpG methylation of oral dysplastic keratinocytes (DOK) cells. After treatment with 8 μM astaxanthin, the promoter CpG methylation levels of the TSGs were significantly reduced, resulting in the increase in gene expression. The overall effect of astaxanthin on DOK cells is inhibiting cell viability, reducing cell migration, leading to cell cycle G0/G1 arrest, and promoting apoptosis.

CONCLUSIONS

This study confirmed significant differences in DNA methylation patterns among oral normal, dysplastic, and cancerous cells. Astaxanthin can reduce the promoter CpG methylation level of TSGs by reducing DNA methyltransferase 1 protein expression level, upregulating mRNA and protein expression, and subsequently modulating the biological behavior of DOK.

DNA methylation and its potential roles in common oral diseases

Oral diseases are among the most common diseases worldwide and are associated with systemic illnesses, and the rising occurrence of oral diseases significantly impacts the quality of life for many individuals. It is crucial to detect and treat these conditions early to prevent them from advancing. DNA methylation is a fundamental epigenetic process that contributes to a variety of diseases including various oral diseases. Taking advantage of its reversibility, DNA methylation becomes a viable therapeutic target by regulating various cellular processes. Understanding the potential role of this DNA alteration in oral diseases can provide significant advances and more opportunities for diagnosis and therapy. This article will review the biology of DNA methylation, and then mainly discuss the key findings on DNA methylation in oral cancer, periodontitis, endodontic disease, oral mucosal disease, and clefts of the lip and/or palate in the background of studies on global DNA methylation and gene-specific DNA methylation.

Knockdown of DNMT1 Induces SLCO3A1 to Promote Follicular Growth by Enhancing the Proliferation of Granulosa Cells in Mammals

In female mammals, the proliferation and apoptosis of granulosa cells (GCs) have been shown to determine the fate of follicles. DNA methyltransferases (DNMTs) and SLCO3A1 have been reported to be involved in the survival of GCs and follicular growth. However, the molecular mechanisms enabling DNMTs to regulate the expression of SLCO3A1 to participate in follicular growth are unclear. In this study, we found that the knockdown of DNMT1 enhanced the mRNA and protein levels of SLCO3A1 by regulating the chromatin accessibility probably. Moreover, SLCO3A1 upregulated the mRNA and protein levels of MCL1, PCNA, and STAR to promote the proliferation of GCs and facilitated cell cycle progression by increasing the mRNA and protein levels of CCNE1, CDK2, and CCND1, but it decreased apoptosis by downregulating the mRNA and protein levels of CASP3 and CASP8. Moreover, SLCO3A1 promoted the growth of porcine follicles and development of mice follicles. In conclusion, the knockdown of DNMT1 upregulated the mRNA and protein levels of SLCO3A1, thereby promoting the proliferation of GCs to facilitate the growth and development of ovarian follicles, and these results provide new insights into investigations of female reproductive diseases.

Epigenetic Activation of TUSC3 Sensitizes Glioblastoma to Temozolomide Independent of MGMT Promoter Methylation Status

Temozolomide (TMZ) is an important first-line treatment for glioblastoma (GBM), but there are limitations to TMZ response in terms of durability and dependence on the promoter methylation status of the DNA repair gene O6-methylguanine DNA methyltransferase (MGMT). MGMT-promoter-hypermethylated (MGMT-M) GBMs are more sensitive to TMZ than MGMT-promoter-hypomethylated (MGMT-UM) GBMs. Moreover, TMZ resistance is inevitable even in TMZ-sensitive MGMT-M GBMs. Hence, epigenetic reprogramming strategies are desperately needed in order to enhance TMZ response in both MGMT-M and MGMT-UM GBMs. In this study, we present novel evidence that the epigenetic reactivation of Tumor Suppressor Candidate 3 (TUSC3) can reprogram sensitivity of GBM stem cells (GSCs) to TMZ irrespective of MGMT promoter methylation status. Interrogation of TCGA patient GBM datasets confirmed TUSC3 promoter regulation of TUSC3 expression and also revealed a strong positive correlation between TUSC3 expression and GBM patient survival. Using a combination of loss-of-function, gain-of-function and rescue studies, we demonstrate that TUSC3 reactivation is associated with enhanced TMZ response in both MGMT-M and MGMT-UM GSCs. Further, we provide novel evidence that the demethylating agent 5-Azacitidine (5-Aza) reactivates TUSC3 expression in MGMT-M GSCs, whereas the combination of 5-Aza and MGMT inhibitor Lomeguatrib is necessary for TUSC3 reactivation in MGMT-UM GSCs. Lastly, we propose a pharmacological epigenetic reactivation strategy involving TUSC3 that leads to significantly prolonged survival in MGMT-M and MGMT-UM orthotopic GSCs models. Collectively, our findings provide a framework and rationale to further explore TUSC3-mediated epigenetic reprogramming strategies that could enhance TMZ sensitivity and outcomes in GBM. Mechanistic and translational evidence gained from such studies could contribute towards optimal design of impactful trials for MGMT-UM GBMs that currently do not have good treatment options.

Identifying SM-miRNA associations based on layer attention graph convolutional network and matrix decomposition

The accurate prediction of potential associations between microRNAs (miRNAs) and small molecule (SM) drugs can enhance our knowledge of how SM cures endogenous miRNA-related diseases. Given that traditional methods for predicting SM-miRNA associations are time-consuming and arduous, a number of computational models have been proposed to anticipate the potential SM-miRNA associations. However, several of these strategies failed to eliminate noise from the known SM-miRNA association information or failed to prioritize the most significant known SM-miRNA associations. Therefore, we proposed a model of Graph Convolutional Network with Layer Attention mechanism for SM-MiRNA Association prediction (GCNLASMMA). Firstly, we obtained the new SM-miRNA associations by matrix decomposition. The new SM-miRNA associations, as well as the integrated SM similarity and miRNA similarity were subsequently incorporated into a heterogeneous network. Finally, a graph convolutional network with an attention mechanism was used to compute the reconstructed SM-miRNA association matrix. Furthermore, four types of cross validations and two types of case studies were performed to assess the performance of GCNLASMMA. In cross validation, global Leave-One-Out Cross Validation (LOOCV), miRNA-fixed LOOCV, SM-fixed LOOCV and 5-fold cross-validation achieved excellent performance. Numerous hypothesized associations in case studies were confirmed by experimental literatures. All of these results confirmed that GCNLASMMA is a trustworthy association inference method.

Cytotoxic Effects of 5-Azacytidine on Primary Tumour Cells and Cancer Stem Cells from Oral Squamous Cell Carcinoma: An In Vitro FTIRM Analysis

In the present study, the cytotoxic effects of 5-azacytidine on primary Oral Squamous Cell Carcinoma cells (OSCCs) from human biopsies, and on Cancer Stem Cells (CSCs) from the same samples, were investigated by an in vitro Fourier Transform InfraRed Microscospectroscopy (FTIRM) approach coupled with multivariate analysis. OSCC is an aggressive tumoral lesion of the epithelium, accounting for ~90% of all oral cancers. It is usually diagnosed in advanced stages, and this causes a poor prognosis with low success rates of surgical, as well as radiation and chemotherapy treatments. OSCC is frequently characterised by recurrence after chemotherapy and by the development of a refractoriness to some employed drugs, which is probably ascribable to the presence of CSCs niches, responsible for cancer growth, chemoresistance and metastasis. The spectral information from FTIRM was correlated with the outcomes of cytotoxicity tests and image-based cytometry, and specific spectral signatures attributable to 5-azacytidine treatment were identified, allowing us to hypothesise the demethylation of DNA and, hence, an increase in the transcriptional activity, together with a conformational transition of DNA, and a triggering of cell death by an apoptosis mechanism. Moreover, a different mechanism of action between OSSC and CSC cells was highlighted, probably due to possible differences between OSCCs and CSCs response.

APC Promoter Methylation in Gastrointestinal Cancer

The adenomatous polyposis coli (APC) gene, known as tumor suppressor gene, has the two promoters 1A and 1B. Researches on APC have usually focused on its loss-of-function variants causing familial adenomatous polyposis. Hypermethylation, however, which is one of the key epigenetic alterations of the APC CpG sequence, is also associated with carcinogenesis in various cancers. Accumulating studies have successively explored the role of APC hypermethylation in gastrointestinal (GI) tumors, such as in esophageal, colorectal, gastric, pancreatic, and hepatic cancer. In sporadic colorectal cancer, the hypermethylation of CpG island in APC is even considered as one of the primary causative factors. In this review, we systematically summarized the distribution of APC gene methylation in various GI tumors, and attempted to provide an improved general understanding of DNA methylation in GI tumors. In addition, we included a robust overview of demethylating agents available for both basic and clinical researches. Finally, we elaborated our findings and perspectives on the overall situation of APC gene methylation in GI tumors, aiming to explore the potential research directions and clinical values.

5-Aza-CdR Regulates RASSF1A By Inhibiting DNMT1 To Affect Colon Cancer Cell Proliferation, Migration And Apoptosis

Objective

To evaluate 5-Aza-CdR’s inhibited effects on migration, proliferation, and apoptosis in colon cancer cells and its potential mechanisms.

Methods

HCT-116, SW480, and SW620 were divided into HCT116 group, HCT116+5-Aza-CdR group, SW480 group, SW480+5-Aza-CdR group, SW620 group and SW620+5-Aza according to experimental needs. MTT test was chosen to investigate cell proliferation; Transwell test was used to evaluate cell migration; scratch assay was used to investigate cell invasion; flow cytometry was used to investigate apoptosis; immunofluorescence assay was used to investigate the protein level of DNMT1 and RASSF1A in cells; qRT-PCR was used to examine DNMT1, RASSF1A, RAS, Raf1, MEK, Grb2 and ERK transcription levels.

Results

Compared with HCT116 group, 5-Aza-CdR+HCT116 group inhibited cell proliferation, increased apoptosis rate, decreased invasive ability, decreased DNMT1 expression, increased expression of RASSF1A, decreased expression of RAS, Raf1, MEK, Grb2 and ERK. SW480 was compared with 5-Aza-CdR+SW480 group and SW620 group with 5-Aza-CdR+SW620 group. Their change trend of detection index was similar to that in HCT-116 group and HCT116+5-Aza-CdR group.

Conclusion

5-Aza-CdR can obviously inhibit the proliferation, migration and invasion of three colon cancer cell lines. Its mechanism maybe relies on the inhibition of DNMT1 mRNA level and protein level and the enhancement of RASSF1A mRNA level and protein level.