CpG island methylator phenotype in plasma is associated with hepatocellular carcinoma prognosis

AIM： To evaluate the clinical significance of CpG island methylator phenotype （CIMP） in plasma and its association with hepatocellular carcinoma （HCC） progress. METHODS： CIMP status of 108 HCC patients was analyzed using a methylation marker panel in tumor tissues and plasma with methylation-specific polymerase chain reaction. Fifteen samples of non-neoplastic liver tissues and 60 of plasma from healthy persons were examined simultaneously. Examined genes included APC, WIF-1, RUNX-3, DI C-1, SFRP-1, DKK and E-cad.26/108, 24.07% in plasma; WIF-1, 53/108, 49.07% in tissue and 35/108, 32.41% in plasma; RUNX-3, 52/108, 48.14% in tissue and 42/108, 38.89% in plasma; DIC-1, 38/108, 35.18% in tissue and 23/108, 21.30% in plasma; SFRP-1, 40/108, 37.04% in tissue and 31/108, 28.7% in plasma; DKK, 39/108, 36.1% in tis- sue and 25/108, 23.14% in plasma; and E-cad, 37/108, 34.3% in tissue and 18/108, 16.67% in plasma. CIMP＋ （≥3 methylated genes） was detected in 68 （60.2%） tumor tissue samples and 62 （57.4%） plasma samples. CIMP was not detected in non-neoplastic liver tissues or plasma of healthy persons. CIMP status in tumor tissues differed significantly in gender, hepatitis B surface antigen, alpha-fetoprotein, and tumor-node- metastasis stage （P 〈 0.05）. Similar results were obtained with plasma samples （P 〈 0.05）. There was no difference in CIMP status in age, presence of hepatitis C virus antibody, cirrhosis, number of nodes, number of tumors, tumor size, or Edmondson-Steiner stage. A one-year follow-up found that the metastatic rate and recurrence rate in the CIMP＋ group were significantly higher than in the CIMP- group as assessed with plasma samples （P 〈 0.05）. CONCLUSION： Plasma DNA can be a reliable sample source for CIMP analysis. CIMP in plasma may serve as a molecular marker of late-stage and poor-prognosis HCC.

CpG island methylator phenotype and Helicobacter pylori infection associated with gastric cancer

AIM： To investigate the association between the CpG island methylator phenotype （CIMP） and serum Helico- bacter pylori （H. pylori） levels for clinical prediction of gastric cancer （GC） progression. METHODS： We analyzed the serum ClMP status of 75 patients with GC using a methylation marker panel and a methylation-specific polymerase chain reaction. Serum samples from 40 healthy persons were examined at the same time. The genes examined were APC, WIF-1, RUNX-3, DLC-1, SFRP-1, DKK and E-cad. H. pylori infec- tion in serum was assayed with an anti-H, pylori immu- noglobulin G antibody test and a rapid urease test. RESULTS： The frequencies of high-level methylation in GC tissues for the seven genes were： 48% for APC, 57.33% for WIF-1, 56% for RUNX-3, 50.67% for DLC-1, 52% for SFRP-1, 54.67% for DKK, and 48% for E-cad.The frequencies in GC serum were 30.67% for APC, 34.67% for WIF-1, 37.33% for RUNX-3, 29.33% for DLC-1, 33.33% for SFRP-1, 32% for DKK, and 26.67% for E-cad. CIMP＋ （defined as ≥ 3 methylated genes） was associated with 47 （62.67%） GC tissue samples and 44 （58.67%） GC serum samples. CIMP＋ was not associated with non-neoplastic mucosal tissues or the serum of healthy persons. Of the 75 GC cases, 51 （68%） were H. pylori＋, and 24 （32%） were H. pylori-. Of the 51 H. pylori＋ cases, 36 were CIMP＋ and 15 were CIMP-. In contrast, for the 24 H. pylori- cases, 11 were CIMP＋, and 13 were CIMP-. The difference was signifi- cant between the H. pylori＋ and H. pylori- groups χ2 = 4.27, P 〈 0.05）. Of the 51 H. pylori＋ GC patients, 34 were CIMP＋ and 17 were CIMP-, while among the 24 H. pylori- GC cases, 10 were CIMP＋ and 14 were CIMP-. The difference was significant between the H. pylori＋ and H. pylori- groups （χ2 = 4.21, P 〈 0.05）. A 2-year follow-up showed significant difference in the rates of metastasis and recurrence between H. pylori＋/CIMP＋ cases and the H. pylori＋/CIMP- cases or CIMP- cases associated with H. pylori assayed in serum （P 〈 0.05）. However, there were no significant differences in sur- vival rates between the two groups. CONCLUSION： H. pylori＋/CIMP＋ cases are associ- ated with higher rates of metastasis and recurrence thanH, pylori＋/CIMP- cases. Serum may be useful for examining CIMP status.

Microsatellite instability and MLH1 promoter hypermethylation in colorectal cancer

Colorectal cancer （CRC） is caused by a series of genetic or epigenetic changes, and in the last decade there has been an increased awareness that there are multiple forms of colorectal cancer that develop through different pathways. Microsatellite instability is involved in the genesis of about 15% of sporadic colorectal cancers and most of hereditary nonpolyposis cancers. Tumors with a high frequency of microsatellite instability tend to be diploid, to possess a mucinous histology, and to have a surrounding lymphoid reaction. They are more prevalent in the proximal colon and have a fast pass from polyp to cancer. Nevertheless, they are associated with longer survival than stage-matched tumors with microsateUite stability. Resistance of colorectal cancers with a high frequency of microsatellite instability to 5-fluorouracilbased chemotherapy is well established. Silencing the MLH1 gene expression by its promoter methylation stops the formation of MLH1 protein, and prevents the normal activation of the DNA repair gene. This is an important cause for genomic instability and cell proliferation to the point of colorectal cancer formation. Better knowledge of this process will have a huge impact on colorectal cancer management, prevention, treatment and prognosis.

Coordinated transcription of ANRIL and P16 genes is silenced by P16 DNA methylation

Objective： To investigate the relationship between the transcription of ANRIL, P15, P14 and P16 at the same locus and the regulation mechanism of ANRIL.Methods： Publicly available database of Cancer Cell Line Encyclopedia（CCLE） was used in bioinformatic analyses. Methylation of Cp G islands was detected by denaturing high performance liquid chromatography（DHPLC）. Gene transcript levels were determined using quantitative real-time polymerase chain reaction（q RTPCR） assays. An engineered P16-specific transcription factor and DNA methyltransferase were used to induce P16-specific DNA demethylation and methylation.Results： The expression level of ANRIL was positively and significantly correlated with that of P16 but not with that of P15 in the CCLE database. This was confirmed in human cell lines and patient colon tissue samples. In addition, ANRIL was significantly upregulated in colon cancer tissues. Transcription of ANRIL and P16 was observed only in cell lines in which the P16 alleles were unmethylated and not in cell lines with fully methylated P16 alleles.Notably, P16-specific methylation significantly decreased transcription of P16 and ANRIL in BGC823 and GES1 cells. In contrast, P16-specific demethylation re-activated transcription of ANRIL and P16 in H1299 cells（P〈0.001）.Alteration of ANRIL expression was not induced by P16 expression changes.Conclusions： ANRIL and P16 are coordinately transcribed in human cells and regulated by the methylation status of the P16 Cp G islands around the transcription start site.

CpG island methylator phenotype in adenocarcinomas from the digestive tract:Methods,conclusions,and controversies

Over the last two decades, cancer-related alterations in DNA methylation that regulate transcription have been reported for a variety of tumors of the gastrointestinal tract. Due to its relevance for translational research, great emphasis has been placed on the analysis and molecular characterization of the CpG island methylator phenotype(CIMP), defined as widespread hypermethylation of CpG islands in clinically distinct subsets of cancer patients. Here, we present an overview of previous work in this field and also explore some open questions using crossplatform data for esophageal, gastric, and colorectal adenocarcinomas from The Cancer Genome Atlas. We provide a data-driven, pan-gastrointestinal stratification of individual samples based on CIMP status and we investigate correlations with oncogenic alterations, including somatic mutations and epigenetic silencing of tumor suppressor genes. Besides known events in CIMP such as BRAF V600 E mutation, CDKN2 A silencing or MLH1 inactivation, we discuss the potential role of emerging actors such as Wnt pathway deregulation through truncating mutations in RNF43 and epigenetic silencing of WIF1. Our results highlight the existence of molecular similarities that are superimposed over a larger backbone of tissue-specific features and can be exploited to reduce heterogeneity of response in clinical trials.

Serrated polyposis syndrome:Molecular,pathological and clinical aspects

Hyperplastic polyps have traditionally been considered not to have malignant potential.New pathological classification of serrated polyps and recent discoveries about the serrated pathway of carcinogenesis have revolutionized the concepts and revitalized the research in this area.Until recently,it has been thought that most colorectal cancers arise from conventional adenomas via the traditional tumor suppressor pathway initiated by a mutation of the APC gene,but it has been found thatthis pathway accounts for only approximately 70%-80% of colorectal cancer(CRC)cases.The majority of the remaining colorectal cancer cases follow an alternative pathway leading to CpG island methylator phenotype carcinoma with BRAF mutation and with or without microsatellite instability.The mechanism of carcinomas arising from this alternative pathway seems to begin with an activating mutation of the BRAF oncogene.Serrated polyposis syndrome is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon.Clinical characteristics,etiology and relationship of serrated polyposis syndrome to CRC have not been clarified yet.Patients with this syndrome show a high risk of CRC and both sporadic and hereditary cases have been described.Clinical criteria have been used for diagnosis and frequent colonoscopy surveillance should be performed in order to prevent colorectal cancer.In this review,we try to gather new insights into the molecular pathogenesis of serrated polyps in order to understand their possible clinical implications and to make an approach to the management of this syndrome.

Serrated pathway in colorectal carcinogenesis

Serrated adenocarcinoma is a recently described subset of colorectal cancer(CRC),which account for about10%of all CRCs and follows an alternative pathway in which serrated polyps replace the traditional adenoma as the precursor lesion to CRC.Serrated polyps form a heterogeneous group of colorectal lesions that includes hyperplastic polyps(HPs),sessile serrated adenoma(SSA),traditional serrated adenoma(TSA)and mixed polyps.HPs are the most common serrated polyp followed by SSA and TSA.This distinct histogenesis is believed to have a major influence in prevention strategies,patient prognosis and therapeutic impact.Genetically,serrated polyps exhibited also a distinct pattern,with KRAS and BRAF having an important contribution to its development.Two other molecular changes that have been implicated in the serrated pathway include microsatellite instability and the CpG island methylator phenotype.In the present review we will address the current knowledge of serrated polyps,clinical pathological features and will update the most recent findings of its molecular pathways.The understanding of their biology and malignancy potential is imperative to implement a surveillance approach in order to prevent colorectal cancer development.

Early-onset colorectal cancer:A separate subset of colorectal cancer

Colorectal cancer(CRC)has a great impact on the world population.With increasing frequency,CRC is described according to the presenting phenotype,based on its molecular characteristics.Classification of CRC tumors according to their genetic and/or epigenetic alterations is not only important for establishing the molecular bases of the disease,but also for predicting patient outcomes and developing more individualized treatments.Early-onset CRC is a heterogeneous disease,with a strong familial component,although the disease is sporadic in an important proportion of cases.Different molecular alterations appear to contribute to the apparent heterogeneity of the early-onset population and subgroups can be distinguished with distinct histopathologic and familial characteristics.Moreover,compared with late-onset CRC,there are characteristicsthat suggest that early-onset CRC may have a different molecular basis.The purpose of this review was to analyze the current state of knowledge about earlyonset CRC with respect to clinicopathologic,familial and molecular features.Together,these features make it increasingly clear that this subset of CRC may be a separate disease,although it has much in common with late-onset CRC.

Multiple primary colorectal cancer: Individual or familial predisposition?

Colorectal carcinoma(CRC) is one of the most frequent cancers. Along the surface of the large bowel, several foci of CRC may appear simultaneously or over the time. The development of at least two different tumours has been defined as multiple primary CRC(MPCRC):When more than one tumour is diagnosed at the same time, it is known as synchronous CRC(SCRC), while when a second neoplasm is diagnosed some time after the resection and/or diagnosis of the first lesion, it is called metachronous CRC(MCRC). Multiple issues can promote the development of MPCRC, ranging from different personal factors, such as environmental exposure, to familial predisposition due to hereditary factors. However, most studies do not distinguish this dichotomy. High- and low-pentrance genetic variants are involved in MPCRC. An increased risk for MPCRC has been described in Lynch syndrome, familial adenomatous polyposis, and serrated polyposis. Non-syndromic familial CRCs should also be considered as risk factors for MPCRC. Environmental factors can promote damage to colon mucosae that enable the concurrence of MPCRC. Epigenetics are thought to play a major role in the carcinogenesis of sporadic MPCRC. The methylation state of the DNA depends on multiple environmental factors(e.g., smoking and eating foods cooked at high temperatures), and this can contribute to increasing the MPCRC rate. Certain clinical features may also suggest individual predisposition for MPCRC. Different etiopathogenic factors are suspected to be involved in SCRC and MCRC, and different familial vs individual factors may be implicated. MCRC seems to follow a familial pattern, whereas individual factors are more important in SCRC. Further studies must be carried out to know the molecular basis of risks for MPCRC in order to modify, if necessary, its clinical management, especially from a preventive point of view.

Molecular phenotypes of colorectal cancer and potential clinical applications

Colorectal cancer(CRC)is a heterogeneous disease,arising from many possible etiological pathways.This heterogeneity can have important implications for CRC prognosis and clinical management.Epidemiological studies of CRC risk and prognosis—as well as clinical trials for the treatment of CRC—must therefore be sensitive to the molecular phenotype of colorectal tumors in patients under study.In this review,we describe four tumor markers that have been widely studied as reflections of CRC heterogeneity:(i)microsatellite instability(MSI)or DNA mismatch repair(MMR)deficiency,(ii)the CpG island methylator phenotype(CIMP),and somatic mutations in(iii)BRAF and(iv)KRAS.These tumor markers have been used to better characterize CRC epidemiology and,increasingly,may be used to guide clinical decision-making.Going beyond these traditional tumor markers,we also briefly review some more novel markers likely to be of clinical significance.Lastly,recognizing that none of these individual tumor markers are isolated attributes but,rather,a reflection of broader tumor phenotypes,we review some of the hypothesized etiological pathways of CRC development and their associated clinical differences.