Expression of BMP6 is Associated with its Methylation Status in Colorectal Cancer Tissue but Lacks Prognostic Significance

Specific epigenetic age acceleration patterns among four molecular subtypes of gastric cancer and their prognostic value

Aims: To determine the association of the methylation age (Horvath epigenetic clock) of gastric cancer (GC) tissues with molecular subtypes and patient survival. Materials & methods: Multivariate regression models were used to determine the association of methylation age acceleration (AA) with the clinical and molecular characteristics of 333 GC patients. Results: Relative to the chromosomal instability subtype, the epigenetic AA was 49.8 (95% CI: 42.7-56.9) years for Epstein-Barr virus, 16.1 (10.6-21.6) years for microsatellite instability, and 6.05 (0.1-11.1) years for genomic stability subtype. GC patients with accelerated aging of tumor tissues had better outcomes (adjusted hazard ratio: 3.13; p = 0.03). Differentially methylated probes in patients with accelerated and decelerated methylation aging enriched in pathways including BMP signaling, HMGB1 signaling, STAT3 signaling and human embryonic stem cell pluripotency. Conclusions: Our results highlight the prognostic value of epigenetic AA in GC and suggest that epigenetic AA is also an indicator of molecular subtype in GC.

Role of the BMP6 protein in breast cancer and other types of cancer

The BMP6 protein (Bone Morphogenetic Protein 6) is part of the superfamily of transforming growth factor-beta (TGF-β) ligands, participates in iron homeostasis, inhibits invasion by increasing adhesions and cell-cell type interactions and induces angiogenesis directly on vascular endothelial cells. BMP6 is coded by a tumor suppressor gene whose subexpression is related to the development and cancer progression; during neoplastic processes, methylation is the main mechanism by which gene silencing occurs. This work presents a review on the role of BMP6 protein in breast cancer (BC) and other types of cancer. The studies carried out to date suggest the participation of the BMP6 protein in the epithelial-mesenchymal transition (EMT) phenotype, cell growth and proliferation; however, these processes are affected in a variable way in the different types of cancer, the methylated CpG sites in BMP6 gene promoter, as well as the interaction with other proteins could be the cause of such variation.

Prognostic DNA methylation markers for sporadic colorectal cancer: a systematic review

Background

Biomarkers that can predict the prognosis of colorectal cancer (CRC) patients and that can stratify high-risk early stage patients from low-risk early stage patients are urgently needed for better management of CRC. During the last decades, a large variety of prognostic DNA methylation markers has been published in the literature. However, to date, none of these markers are used in clinical practice.

Methods

To obtain an overview of the number of published prognostic methylation markers for CRC, the number of markers that was validated independently, and the current level of evidence (LoE), we conducted a systematic review of PubMed, EMBASE, and MEDLINE. In addition, we scored studies based on the REMARK guidelines that were established in order to attain more transparency and complete reporting of prognostic biomarker studies. Eighty-three studies reporting on 123 methylation markers fulfilled the study entry criteria and were scored according to REMARK.

Results

Sixty-three studies investigated single methylation markers, whereas 20 studies reported combinations of methylation markers. We observed substantial variation regarding the reporting of sample sizes and patient characteristics, statistical analyses, and methodology. The median (range) REMARK score for the studies was 10.7 points (4.5 to 17.5) out of a maximum of 20 possible points. The median REMARK score was lower in studies, which reported a p value below 0.05 versus those, which did not (p = 0.005). A borderline statistically significant association was observed between the reported p value of the survival analysis and the size of the study population (p = 0.051). Only 23 out of 123 markers (17%) were investigated in two or more study series. For 12 markers, and two multimarker panels, consistent results were reported in two or more study series. For four markers, the current LoE is level II, for all other markers, the LoE is lower.

Conclusion

This systematic review reflects that adequate reporting according to REMARK and validation of prognostic methylation markers is absent in the majority of CRC methylation marker studies. However, this systematic review provides a comprehensive overview of published prognostic methylation markers for CRC and highlights the most promising markers that have been published in the last two decades.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0461-8) contains supplementary material, which is available to authorized users.

MGMT-B gene promoter hypermethylation in patients with inflammatory bowel disease - a novel finding

Inflammatory bowel disease (IBD) is a disease strongly associated with colorectal cancer (CRC) as a well-known precancerous condition. Alterations in DNA methylation and mutation in K-ras are believed to play an early etiopathogenic role in CRC and may also an initiating event through deregulation of molecular signaling. Epigenetic silencing of APC and SFRP2 in the WNT signaling pathway may also be involved in IBD-CRC. The role of aberrant DNA methylation in precancerous state of colorectal cancer (CRC) is under intensive investigation worldwide. The aim of this study was to investigate the status of promoter methylation of MGMT-B, APC1A and SFRP2 genes, in inflamed and normal colon tissues of patients with IBD compared with control normal tissues. A total of 52 IBD tissues as well as corresponding normal tissues and 30 samples from healthy participants were obtained. We determined promoter methylation status of MGMT-B, SFRP2 and APC1A genes by chemical treatment with sodium bisulfite and subsequent MSP. The most frequently methylated locus was MGMT-B (71%; 34 of 48), followed by SFRP2 (66.6 %; 32 of 48), and APC1A (43.7%; 21 of 48). Our study demonstrated for the first time that hypermethylation of the MGMT-B and the SFRP2 gene promoter regions might be involved in IBD development. Methylation of MGMT-B and SFRP2 in IBD patients may provide a method for early detection of IBD-associated neoplasia.

The effects of folic acid on global DNA methylation and colonosphere formation in colon cancer cell lines

Folate and its synthetic form, folic acid (FA), are essential vitamins for the regeneration of S-adenosyl methionine molecules, thereby maintaining adequate cellular methylation. The deregulation of DNA methylation is a contributing factor to carcinogenesis, as alterations in genetic methylation may contribute to stem cell reprogramming and dedifferentiation processes that lead to a cancer stem cell (CSC) phenotype. Here, we investigate the potential effects of FA exposure on DNA methylation and colonosphere formation in cultured human colorectal cancer (CRC) cell lines. We show for the first time that HCT116, LS174T, and SW480 cells grown without adequate FA demonstrate significantly impaired colonosphere forming ability with limited changes in CD133, CD166, and EpCAM surface expression. These differences were accompanied by concomitant changes to DNA methyltransferase (DNMT) enzyme expression and DNA methylation levels, which varied depending on cell line. Taken together, these results demonstrate an interaction between FA metabolism and CSC phenotype in vitro and help elucidate a connection between supplemental FA intake and CRC development.