Detecting Early-Stage Oral Cancer from Clinically Diagnosed Oral Potentially Malignant Disorders by DNA Methylation Profile

DNMT1-targeting remodeling global DNA hypomethylation for enhanced tumor suppression and circumvented toxicity in oral squamous cell carcinoma

BACKGROUND

The faithful maintenance of DNA methylation homeostasis indispensably requires DNA methyltransferase 1 (DNMT1) in cancer progression. We previously identified DNMT1 as a potential candidate target for oral squamous cell carcinoma (OSCC). However, how the DNMT1- associated global DNA methylation is exploited to regulate OSCC remains unclear.

METHODS

The shRNA-specific DNMT1 knockdown was employed to target DNMT1 on oral cancer cells in vitro, as was the use of DNMT1 inhibitors. A xenografted OSCC mouse model was established to determine the effect on tumor suppression. High-throughput microarrays of DNA methylation, bulk and single-cell RNA sequencing analysis, multiplex immunohistochemistry, functional sphere formation and protein immunoblotting were utilized to explore the molecular mechanism involved. Analysis of human samples revealed associations between DNMT1 expression, global DNA methylation and collaborative molecular signaling with oral malignant transformation.

RESULTS

We investigated DNMT1 expression boosted steadily during oral malignant transformation in human samples, and its inhibition considerably minimized the tumorigenicity in vitro and in a xenografted OSCC model. DNMT1 overexpression was accompanied by the accumulation of cancer-specific DNA hypomethylation during oral carcinogenesis; conversely, DNMT1 knockdown caused atypically extensive genome-wide DNA hypomethylation in cancer cells and xenografted tumors. This novel DNMT1-remodeled DNA hypomethylation pattern hampered the dual activation of PI3K-AKT and CDK2-Rb and inactivated GSK3β collaboratively. When treating OSCC mice, targeting DNMT1 achieved greater anticancer efficacy than the PI3K inhibitor, and reduced the toxicity of blood glucose changes caused by the PI3K inhibitor or combination of PI3K and CDK inhibitors as well as adverse insulin feedback.

CONCLUSIONS

Targeting DNMT1 remodels a novel global DNA hypomethylation pattern to facilitate anticancer efficacy and minimize potential toxic effects via balanced signaling synergia. Our study suggests DNMT1 is a crucial gatekeeper regarding OSCC destiny and treatment outcome.

Microneedles: structure, classification, and application in oral cancer theranostics

Oral cancer is a malignant tumor that threatens the health of individuals on a global scale. Currently available clinical treatment methods, including surgery, radiotherapy, and chemotherapy, significantly impact the quality of life of patients with systemic side effects. In the treatment of oral cancer, local and efficient delivery of antineoplastic drugs or other substances (like photosensitizers) to improve the therapy effect is a potential way to optimize oral cancer treatments. As an emerging drug delivery system in recent years, microneedles (MNs) can be used for local drug delivery, offering the advantages of high efficiency, convenience, and noninvasiveness. This review briefly introduces the structures and characteristics of various types of MNs and summarizes MN preparation methods. An overview of the current research application of MNs in different cancer treatments is provided. Overall, MNs, as a means of transporting substances, demonstrate great potential in oral cancer treatments, and their promising future applications and perspectives of MNs are outlined in this review.

Epigenetic regulation of RARB overcomes the radio-resistance of colorectal carcinoma cells via cancer stem cells

Cancer stem cells (CSCs) are able to survive after cancer therapies, leading to cancer progression and recurrence in colorectal carcinoma (CRC). Therapies targeting CSCs are believed to be promising strategies for efficiently eradicating cancers. This study was to investigate that how retinoic acid receptor beta (RARB) affected the biological characteristics of CSCs and radio-resistance in CRC and the epigenetic mechanism. The sensitivity of CSCs isolated from HCT116 cells to radiotherapy was reduced compared with the parental cells. Using database querying, we found that RARB was one of the most significantly downregulated gene in radio-resistant cells in CRC. Also, RARB was poorly expressed in our isolated CSCs, and overexpression of RARB inhibited the properties of CSCs and enhanced radiotherapy sensitivity. Mechanistically, the methylation of RARB was higher in CSCs compared with HCT116 cells, which was significantly reduced after the application of DNA methylation inhibitor 5-azacytidine (5-azaC). DNA methyltransferases (DNMT1) was found to be recruited into the RARB promoter. 5-AzaC treatment inhibited DNMT1 activity and improved radiotherapy sensitivity by promoting RARB expression. Our results imply that inhibition of DNMT1 can display a new mechanism for the epigenetic mediation of RARB in radio-resistant CRC.

The Use of Salivary Levels of Matrix Metalloproteinases as an Adjuvant Method in the Early Diagnosis of Oral Squamous Cell Carcinoma: A Narrative Literature Review

Oral squamous cell carcinoma (OSCC) is an aggressive malignancy with increased mortality, in which the early diagnosis is the most important step in increasing patients' survival rate. Extensive research has evaluated the role of saliva as a source of diagnostic biomarkers, among which matrix metalloproteinases (MMPs) have shown a valuable potential for detecting even early stages of OSCC. The aim of this review was to present recent clinical data regarding the significance of salivary MMPs in the detection of early malignant transformation of the oral mucosa. A narrative review was conducted on articles published in PubMed, Cochrane Library, Web of Science, EBSCO and SciELO databases, using specific terms. Our search revealed that MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-12 and MMP-13 had significantly higher levels in saliva from patients with OSCC compared to controls. However, the strength of evidence is limited, as most information regarding their use as adjuvant diagnostic tools for OSCC comes from studies with a low number of participants, variable methodologies for saliva sampling and diagnostic assays, and insufficient adjustment for all covariates. MMP-1, MMP-3 and MMP-9 were considered the most promising candidates for salivary diagnosis of OSCC, but larger studies are needed in order to validate their clinical application.