CpG Island Methylator Phenotype—A Hope for the Future or a Road to Nowhere?

The CpG island methylator phenotype (CIMP) can be regarded as the most notable emanation of epigenetic instability in cancer. Since its discovery in the late 1990s, CIMP has been extensively studied, mainly in colorectal cancers (CRC) and gliomas. Consequently, knowledge on molecular and pathological characteristics of CIMP in CRC and other tumour types has rapidly expanded. Concordant and widespread hypermethylation of multiple CpG islands observed in CIMP in multiple cancers raised hopes for future epigenetically based diagnostics and treatments of solid tumours. However, studies on CIMP in solid tumours were hampered by a lack of generalisability and reproducibility of epigenetic markers. Moreover, CIMP was not a satisfactory marker in predicting clinical outcomes. The idea of targeting epigenetic abnormalities such as CIMP for cancer therapy has not been implemented for solid tumours, either. Twenty-one years after its discovery, we aim to cover both the fundamental and new aspects of CIMP and its future application as a diagnostic marker and target in anticancer therapies.

The CpG island methylator phenotype increases the risk of high-grade squamous intraepithelial lesions and cervical cancer

Background High-risk human papillomavirus (HR-HPV) infection is the main cause of cervical cancer, but additional alterations are necessary for its development. Abnormal DNA methylation has an important role in the origin and dissemination of cervical cancer and other human tumors. In this work, we analyzed the methylation of eight genes (AJAP1, CDH1, CDH13, MAGI2, MGMT, MYOD1, RASSF1A and SOX17) that participate in several biological processes for the maintenance of cell normality. We analyzed DNA methylation by methylation-specific PCR (MSP) and HPV infection using the INNO‑LiPA genotyping kit in 59 samples diagnostic of normal cervical tissue (non-SIL), 107 low-grade squamous intraepithelial lesions (LSILs), 29 high-grade squamous intraepithelial lesions (HSILs) and 51 cervical cancers (CCs). Results We found that all samples of LSIL, HSIL, and CC were HPV-positive, and the genotypes with higher frequencies were 16, 18, 51 and 56. In general, the genes analyzed displayed a significant tendency toward an increase in methylation levels according to increasing cervical lesion severity, except for the CDH13 gene. High CpG island methylator phenotype (CIMP) was associated with a 50.6-fold (95% CI 4.72–2267.3)-increased risk of HSIL and a 122-fold risk of CC (95% CI 10.04–5349.7). Conclusions We found that CIMP high was significantly associated with HSIL and CC risk. These results could indicate that CIMP together with HR-HPV infection and other factors participates in the development of HSIL and CC.

The Methylation of SDC2 and TFPI2 Defined Three Methylator Phenotypes of Colorectal Cancer

BackgroudMethylated SDC2 and TFPI2 are applied frequently for the early detection of colorectal cancer (CRC). However, they often miss some positive samples, which directly affects their sensitivities, and the underlining mechanism is not well known.Methods:CRC samples from TCGA and GEO datasets were divided into three groups, Highmethylation/ High-methylation (HH), High-methylation/Low-methylation (HL), and Lowmethylation/Low-methylation (LL) according to the methylation status of SDC2 and TFPI2 promoters. Variations in age, tumor location, and microsatellite instable were then assessed between the three groups and verified in our custom cohort.ResultsSamples of HL group preferred to derive from left-sided CRCs (P < 0.05). HH samples showed the highest microsatellite instability and mutation load (mean nonsynonymous mutations for HH/HL/LL: 10.55/3.91/7.02, P = 0.0055). Almost all mutations of BRAF, one of the five typical CpG island methylator phenotype (CIMP) related genes, were observed in HH group (HH/HL/LL: 51/0/1, P = 0.018). Besides, older patients were frequently found in HH group. Expression analysis identified 37, 84, and 22 group-specific differentially expressed genes (DEGs) for HH, HL, and LL, respectively. Functional enrichment analysis revealed that HH-specific DEGs were mainly related to transcription regulation, while LL-specific DEGs were enriched in the biological processes of extracellular matrix interaction and cell migration.Conclusions:The three methylation phenotypes identified based on SDC2 and TFPI2 methylation status showed extensive variations in tumor location, patient age, MSI and ECM biology processes, suggesting that these respective sides should be considered when developing new methylation-based biomarkers for CRC detection.

CpG Island Methylator Phenotype Modulates the Immune Response of the Tumor Microenvironment and Influences the Prognosis of Pancreatic Cancer Patients

Background. CpG island methylator phenotype (CIMP), featured with concurrent and widespread hypermethylation of a cluster of CpGs, has been reported to play an important role in carcinogenesis. Limited studies have investigated the role of CIMP in pancreatic cancer (PC). The aim of this study was to explore the CIMP in PC patients and its impact on the immune response of the tumor microenvironment and prognosis. Methods. DNA methylation, somatic mutation, mRNA, and corresponding clinical data of PC patients were downloaded from TCGA (184 patients) and the ICGC (264 patients). Univariate and multivariate regression analyses were used to identify prognosis-related CpGs. Consensus clustering analysis was used for identification of the CIMP in PC patients. ESTIMATE and CIBORORT were used for estimation of the tumor microenvironment (TME) in PC patients. Results. In the TCGA PC cohort, 22,450 differential CpGs, including 12,937 hypermethylated CpGs and 9,513 hypomethylated CpGs, were identified between 184 PC patients and 10 normal controls. Univariate and multivariate Cox analysis further screened out 72 OS-related CpGs, and three distinct CIMP groups with distinctly different prognosis and molecular features, including the CIMP-L subgroup, CIMP-M subgroup, and CIMP-H subgroup, were identified based on unsupervised consensus clustering analysis of these CpGs. Patients of the CIMP-H subgroup had poorer OS and RFS, while patients of the CIMP-L subgroup had better OS and RFS. The CIMP status was also an independent prognostic factor for OS and PFS. In molecular features, significantly higher somatic mutation burden and tumor mutational burden were found in patients of the CIMP-H subgroup compared to those of the CIMP-L subgroup. Besides, lower stromal score, immune score, and higher cancer stemness indices and tumor purity were also found in patients of the CIMP-H subgroup compared to those of the CIMP-L subgroup. Correspondingly, significant total T cells, total B cells, CD8 T cells, memory CD4 T cells, and higher regulatory T cells were found in patients of the CIMP-H subgroup. Moreover, significantly lower expression of immune checkpoint genes, such as PD-1, CTLA4, CD86, VTCN1, and LAG-3, was also found in patients of the CIMP-H subgroup compared to those of the CIMP-L subgroup. In the end, we validated the CIMP status in PC patients of the ICGC dataset. Conclusion. The CIMP may modulate the immune response of the tumor microenvironment and influence the prognosis of pancreatic cancer patients, which may help to make an assertion to provide specific and efficient treatment options for patients of different subtypes.

EP.FRI.181 Beyond the adenoma- carcinoma sequence. A review of the morphogenetic basis of colorectal cancer

Introduction Looking beyond the adenoma carcinoma sequence researchers have discovered alternate morpho-genetic routes, and tumour biomarkers in colorectal cancer. This has caused a paradigm shift in the management, resulting in improved diagnosis, prevention, and delivery of tailored treatment aiming at specific molecular pathways. Aims, Methods This review summarises Methods PubMed, Google Scholar, NLM searches based on aims and key words were conducted. Further, academically and clinically relevant searches were made if more information was required. When required, references of articles were also retrieved. Results The two main theories regarding the morphological origins of colorectal cancer are the adenoma carcinoma sequence and the De-novo origins. The underlying genetic models are the (i) chromosomal instability pathway (CIN), (ii) the microsatellite instability pathway (MSI) and (iii) the CpG Island methylator phenotype (CIMP) pathways. Though unique, the pathways communicate with each other. The genetic fingerprinting of colorectal cancers has an impact on their tailored management and consequently a through grounding in the basics are essential for those in gastrointestinal subspecialties. Conclusions Two morphologically distinct pathways and three unique genetic mechanisms have been described. There are significant interactions between them. Behaviours of sporadic and inherited colorectal cancer, their treatment and prognosis depend on our understanding of these mechanisms and the availability of targeted therapies to assist surgical resection.

Immunoprofiles and DNA Methylation of Inflammatory Marker Genes in Ulcerative Colitis-Associated Colorectal Tumorigenesis

Immunological and epigenetic changes are interconnected and contribute to tumorigenesis. We determined the immunoprofiles and promoter methylation of inflammation-related genes for colitis-associated colorectal carcinomas (CA-CRC). The results were compared with Lynch syndrome (LS)-associated colorectal tumors, which are characterized by an active immune environment through inherited mismatch repair defects. CA-CRCs (n = 31) were immunohistochemically evaluated for immune cell scores (ICSs) and PDCD1 and CD274 expression. Seven inflammation-associated genes (CD274, NTSR1, PPARG, PTGS2, PYCARD, SOCS1, and SOCS2), the repair gene MGMT, and eight standard marker genes for the CpG Island Methylator Phenotype (CIMP) were investigated for promoter methylation in CA-CRCs, LS tumors (n = 29), and paired normal mucosae by multiplex ligation-dependent probe amplification. All but one CA-CRCs were microsatellite-stable and all LS tumors were microsatellite-unstable. Most CA-CRCs had a high ICS (55%) and a positive CD274 expression in immune cells (52%). NTSR1 revealed frequent tumor-specific hypermethylation in CA-CRC and LS. When compared to LS mucosae, normal mucosae from patients with CA-CRC showed significantly higher methylation of NTSR1 and most CIMP markers. In conclusion, CA-CRCs share a frequent ICShigh/CD274pos expression pattern with LS tumors. Elevated methylation in normal mucosa may indicate field cancerization as a feature of CA-CRC-associated tumorigenesis.

943 Beyond the Adenoma Carcinoma Sequence

Introduction Looking beyond the adenoma carcinoma sequence researchers have discovered alternate morpho-genetic routes, and tumour biomarkers in colorectal cancer. This has caused a paradigm shift in the management, resulting in improved diagnosis, prevention, and delivery of tailored treatment aiming at specific molecular pathways. Aim This review summarises Method PubMed, Google Scholar, NLM searches based on aims and key words were conducted. Further, academically, and clinically relevant searches were made if more information was required. When required, references of articles were also retrieved. Results The two main theories regarding the morphological origins of colorectal cancer are the adenoma carcinoma sequence and the De-novo origins. The underlying genetic models are the (i) chromosomal instability pathway (CIN), (ii) the microsatellite instability pathway (MSI) and (iii) the CpG Island methylator phenotype (CIMP) pathways. Though unique, the pathways communicate with each other. The genetic fingerprinting of colorectal cancers has an impact on their tailored management and consequently a through grounding in the basics are essential for those in gastrointestinal subspecialties. Conclusions Two morphologically distinct pathways and three unique genetic mechanisms have been described. There are significant interactions between them. Behaviours of sporadic and inherited colorectal cancer, their treatment and prognosis depend on our understanding of these mechanisms and the availability of targeted therapies to assist surgical resection.

Determination & expression of chimeric protein in colorectal cancer: A bioinformatics Approach

Colorectal cancer (CRC) accounts for about 10% of cancer-related mortality in western countries. Increasing ageing population, undesirable modern dietary and high-risk factors like smoking, obesity and low exercise. Chromosomal instability (CIN), CpG island methylator phenotype (CIMP), and microsatellite instability are the three different mechanism that give rise to CRC. It often grow slowly, and customarily doesn’t produce symptoms until reaching a substantial size of several centimeters, which can block the passage of feces and cause cramping, pain, or bleeding which can present as visible bleeding with bowel movements or, rarely, dark “tarry” stools. Most colon tumors develop via a several different processes involving a series of histological, morphological, and genetical changes that accumulate over time to time. New treatments for primary and metastatic colorectal cancer have emerged, like in variety of therapeutic process by preparing chimeric proteins that triggers the cells and stop it from getting severe.

Tetranucleotide and Low Microsatellite Instability Are Inversely Associated with the CpG Island Methylator Phenotype in Colorectal Cancer

MSH3 gene or protein deficiency or loss-of-function in colorectal cancer can cause a DNA mismatch repair defect known as “elevated microsatellite alterations at selected tetranucleotide repeats” (EMAST). A high percentage of MSI-H tumors exhibit EMAST, while MSI-L is also linked with EMAST. However, the distribution of CpG island methylator phenotype (CIMP) within the EMAST spectrum is not known. Five tetranucleotide repeat and five MSI markers were used to classify 100 sporadic colorectal tumours for EMAST, MSI-H and MSI-L according to the number of unstable markers detected. Promoter methylation was determined using methylation-specific PCR for MSH3, MCC, CDKN2A (p16) and five CIMP marker genes. EMAST was found in 55% of sporadic colorectal carcinomas. Carcinomas with only one positive marker (EMAST-1/5, 26%) were associated with advanced tumour stage, increased lymph node metastasis, MSI-L and lack of CIMP-H. EMAST-2/5 (16%) carcinomas displayed some methylation but MSI was rare. Carcinomas with ≥3 positive EMAST markers (13%) were more likely to have a proximal colon location and be MSI-H and CIMP-H. Our study suggests that EMAST/MSI-L is a valuable prognostic and predictive marker for colorectal carcinomas that do not display the high methylation phenotype CIMP-H.