Emerging role of different DNA methyltransferases in the pathogenesis of cancer

Integrated analysis of the role of PR/SET domain 14 in gastric cancer

BACKGROUND

Gastric cancer is one of the most common tumors worldwide, and most patients are deprived of treatment options when diagnosed at advanced stages. PRDM14 has carcinogenic potential in breast and non-small cell lung cancer. however, its role in gastric cancer has not been elucidated.

METHODS

We aimed to elucidate the expression of PRDM14 using pan-cancer analysis. We monitored the expression of PRDM14 in cells and patients using quantitative polymerase chain reaction, western blotting, and immunohistochemistry. We observed that cell phenotypes and regulatory genes were influenced by PRDM14 by silencing PRDM14. We evaluated and validated the value of the PRDM14-derived prognostic model. Finally, we predicted the relationship between PRDM14 and small-molecule drug responses using the Connectivity Map and The Genomics of Drug Sensitivity in Cancer databases.

RESULTS

PRDM14 was significantly overexpressed in gastric cancer, which identified in cell lines and patients' tissues. Silencing the expression of PRDM14 resulted in apoptosis promotion, cell cycle arrest, and inhibition of the growth and migration of GC cells. Functional analysis revealed that PRDM14 acts in epigenetic regulation and modulates multiple DNA methyltransferases or transcription factors. The PRDM14-derived differentially expressed gene prognostic model was validated to reliably predict the patient prognosis. Nomograms (age, sex, and PRDM14-risk score) were used to quantify the probability of survival. PRDM14 was positively correlated with sensitivity to small-molecule drugs such as TPCA-1, PF-56,227, mirin, and linsitinib.

CONCLUSIONS

Collectively, our findings suggest that PRDM14 is a positive regulator of gastric cancer progression. Therefore, it may be a potential therapeutic target for gastric cancer.

DNMT3A Cooperates with YAP/TAZ to Drive Gallbladder Cancer Metastasis

Gallbladder cancer (GBC) is an extremely lethal malignancy with aggressive behaviors, including liver or distant metastasis; however, the underlying mechanisms driving the metastasis of GBC remain poorly understood. In this study, it is found that DNA methyltransferase DNMT3A is highly expressed in GBC tumor tissues compared to matched adjacent normal tissues. Clinicopathological analysis shows that DNMT3A is positively correlated with liver metastasis and poor overall survival outcomes in patients with GBC. Functional analysis confirms that DNMT3A promotes the metastasis of GBC cells in a manner dependent on its DNA methyltransferase activity. Mechanistically, DNMT3A interacts with and is recruited by YAP/TAZ to recognize and access the CpG island within the CDH1 promoter and generates hypermethylation of the CDH1 promoter, which leads to transcriptional silencing of CDH1 and accelerated epithelial-to-mesenchymal transition. Using tissue microarrays, the association between the expression of DNMT3A, YAP/TAZ, and CDH1 is confirmed, which affects the metastatic ability of GBC. These results reveal a novel mechanism through which DNMT3A recruitment by YAP/TAZ guides DNA methylation to drive GBC metastasis and provide insights into the treatment of GBC metastasis by targeting the functional connection between DNMT3A and YAP/TAZ.

DNA mismatch repair system regulates the expression of PD-L1 through DNMTs in cervical cancer

BACKGROUND

Cervical cancer (CC) is a potential clinical application of PD-1/PD-L1 inhibitor. We aimed to study the mechanism of DNA mismatch repair (MMR) system regulating the expression of PD-L1 in CC through DNA methyltransferase (DNMTs).

METHODS

We collected pathological specimens from 118 cases of CC to analyze the relationship between PD-L1 expression and DNMTs in different MMR states. RNA interference (RNAi) technique was used to simulate the formation of CC cell line with MMR deficiency (dMMR) state, and subcutaneous tumor formation experiment was carried out in nude mice to verify the relationship between PD-L1 expression and DNMTs in MMR state.

RESULTS

The PD-L1 positive rate in 118 cases of CC was 58.47%, while the microsatellite instability (MSI) status accounted for 5.93%. There was a significant difference in the expression of PD-L1 between patients within the dMMR and MMR proficient (pMMR) groups (χ2 = 21.405, P < 0.001). Subcutaneous inoculation after infection of Siha cells led to successful tumorigenesis in nude mice, accompanied by a significant increase in the level of PD-L1 expression in the mouse tumors, while the expression level of MLH1 and MSH2 protein decreased significantly. We also found that PD-L1 expression was closely related to the expression of DNMTs.

CONCLUSION

PD-L1 is universal expressed on the surface of CC cells, dMMR status enhances the expression of PD-L1 on the surface of CC cells, dMMR states of CC are related to the demethylation status of the PD-L1 gene promoter region.

The Role of Epigenetic Modifier Mutations in Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are a group of diseases with a low incidence, high degree of heterogeneity, and a dismal prognosis in most cases. Because of the low incidence of these diseases, there have been few therapeutic novelties developed over time. Nevertheless, this fact is changing presently as epigenetic modifiers have been shown to be recurrently mutated in some types of PTCLs, especially in the cases of PTCLs not otherwise specified (PTCL-NOS), T follicular helper (TFH), and angioimmunoblastic T-cell lymphoma (AITL). These have brought about more insight into PTCL biology, especially in the case of PTCLs arising from TFH lymphocytes. From a biological perspective, it has been observed that ten-eleven translocators (TET2) mutated T lymphocytes tend to polarize to TFH, while Tregs lose their inhibitory properties. IDH2 R172 was shown to have inhibitory effects on TET2, mimicking the effects of TET2 mutations, as well as having effects on histone methylation. DNA methyltransferase 3A (DNMT3A) loss-of-function, although it was shown to have opposite effects to TET2 from an inflammatory perspective, was also shown to increase the number of T lymphocyte progenitors. Aside from bringing about more knowledge of PTCL biology, these mutations were shown to increase the sensitivity of PTCLs to certain epigenetic therapies, like hypomethylating agents (HMAs) and histone deacetylase inhibitors (HDACis). Thus, to answer the question from the title of this review: We found the Achilles heel, but only for one of the Achilles.

Comprehensive Analysis of DNA Methyltransferases Expression in Primary and Relapsed Ovarian Carcinoma

BACKGROUND

Despite recent advances in epithelial ovarian carcinoma (EOC) treatment, its recurrence and mortality rates have not improved significantly. DNA hypermethylation has generally been associated with an ominous prognosis and chemotherapy resistance, but the role of DNA methyltransferases (DNMTs) in EOC remains to be investigated.

METHODS

In the current study, we systematically retrieved gene expression data from patients with EOC and studied the immunohistochemical expression of DNMTs in 108 primary and 26 relapsed tumors.

RESULTS

Our results showed that the DNMT1, DNMT3A, DNMT3B and DNMT3L RNA levels were higher and the DNMT2 level was lower in tumors compared to non-neoplastic tissue, and DNMT3A and DNMT2 expression decreased from Stage-II to Stage-IV carcinomas. The proteomic data also suggested that the DNMT1 and DNMT3A levels were increased in the tumors. Similarly, the DNMT1, DNMT3A and DNMT3L protein levels were overexpressed and DNMT2 expression was reduced in high-grade carcinomas compared to non-neoplastic tissue and low-grade tumors. Moreover, DNMT1 and DNMT3L were increased in relapsed tumors compared to their primaries. The DNMT3A, DNMT1 and DNMT3B mRNA levels were correlated with overall survival.

CONCLUSIONS

Our study demonstrates that DNMT1 and DNMT3L are upregulated in primary high-grade EOC and further increase in relapses, whereas DNMT3A is upregulated only in the earlier stages of cancer progression. DNMT2 downregulation highlights the presumed tumor-suppressor activity of this gene in ovarian carcinoma.

The evaluation of chitosan hydrogel based curcumin effect on DNMT1, DNMT3A, DNMT3B, MEG3, HOTAIR gene expression in glioblastoma cell line

BACKGROUND

Cancer is one of the most important causes of death worldwide. Some types of cancer, including glioblastoma, with a high potential for growth, invasion, and resistance to general treatments, chemotherapy, and radiotherapy, have a high potential for recurrence. Many chemical drugs have been used to treat it, but herbal drugs are more effective with fewer side effects; Therefore, this research aims to investigate the effect of curcumin-chitosan nano-complex on the expression of MEG3, HOTAIR, DNMT1, DNMT3A, DNMT3B genes in the glioblastoma cell line.

METHODS

In this research, glioblastoma cell line, PCR and spectrophotometry techniques, MTT test and transmission, field emission transmission, and fluorescent electron microscopes were used.

RESULTS

The morphological examination of the curcumin-chitosan nano-complex was without clumping, and the fluorescent microscope examination showed the nano-complex enters the cell and affects the genes expression. In its bioavailability studies, it was found that it significantly increases the death of cancer cells in a dose- and time-dependent manner. Gene expression tests showed that this nano-complex increased MEG3 gene expression compared to the control group, which is statistically significant (p < 0.05). It also decreased HOTAIR gene expression compared to the control group, which was not statistically significant (p > 0.05). It decreased the expression of DNMT1, DNMT3A, and DNMT3B genes compared to the control group, which is statistically significant (p < 0.05).

CONCLUSION

By using active plant substances such as curcumin, the active demethylation of brain cells can be directed to the path of inhibiting the growth of brain cancer cells and eliminating them.

The Emerging Role of Epigenetics in Metabolism and Endocrinology

Each cell in a multicellular organism has its own phenotype despite sharing the same genome. Epigenetics is a somatic, heritable pattern of gene expression or cellular phenotype mediated by structural changes in chromatin that occur without altering the DNA sequence. Epigenetic modification is an important factor in determining the level and timing of gene expression in response to endogenous and exogenous stimuli. There is also growing evidence concerning the interaction between epigenetics and metabolism. Accordingly, several enzymes that consume vital metabolites as substrates or cofactors are used during the catalysis of epigenetic modification. Therefore, altered metabolism might lead to diseases and pathogenesis, including endocrine disorders and cancer. In addition, it has been demonstrated that epigenetic modification influences the endocrine system and immune response-related pathways. In this regard, epigenetic modification may impact the levels of hormones that are important in regulating growth, development, reproduction, energy balance, and metabolism. Altering the function of the endocrine system has negative health consequences. Furthermore, endocrine disruptors (EDC) have a significant impact on the endocrine system, causing the abnormal functioning of hormones and their receptors, resulting in various diseases and disorders. Overall, this review focuses on the impact of epigenetics on the endocrine system and its interaction with metabolism.