Disappearance of Serum Methylated p16 Indicates Longer Survival in Patients with Gastric Cancer

Utilizing circulating tumour DNA as a prognostic predictor of gastric cancer: a meta-analysis

Background: Circulating tumour DNA (ctDNA) has demonstrated robust diagnostic accuracy in several digestive cancers. However, the prognostic role of ctCDNA in gastric cancer (GC) is still controversial. This systematic review and meta-analysis aimed to evaluate the prognostic value of ctDNA in GC.Methods: PubMed, Web of Science and Cochrane databases were searched to identify studies reporting the use of ctDNA to predict GC outcome and all relevant studies published until November 2022 were enrolled for our analysis. Data were extracted by two authors independently and statistic analysis was conducted by R program with 'meta' and 'metafor' packages.Results: A total of 34 qualified articles with 5091 subjects were incorporated into our meta-analysis. The corresponding Hazard ratio (HR) of overall survival (OS), disease-free survival (DFS) and progression-free survival (PFS) were 2.74 (95% CI:2.24-3.35), 3.13 (95% CI:2.08-4.72) and 3.04 (95% CI:2.46-3.76), respectively, in GC patients.Conclusion: Blood-based ctDNA assay would be a potential novel biomarker for GC evaluation and prediction.Simple Summary: This is the integrated meta-analysis on the association of circulating tumour DNA (ctDNA) and prognosis of gastric cancer (GC) with an increasing number of studies exploring the prognostic value of GC in the last few years, which depicted that the detection of ctDNA could be a promising predictor in GC patients.

DNA hypomethylation promotes invasion and metastasis of gastric cancer cells by regulating the binding of SP1 to the CDCA3 promoter

BACKGROUND

Cell division cycle associated protein-3 (CDCA3) has been reported frequently upregulated in various cancers. It has been progressively realized that changed DNA methylations occur in diverse carcinomas. However, the concrete involvement of CDCA3 and DNA methylation in gastric cancer (GC) still needs to be further elucidated.

METHODS

In this study, quantitative reverse-transcription polymerase chain reaction (PCR) was utilized to determine the relative expressions of CDCA3 in GC and normal tissue samples. The methylation condition of CDCA3 was determined by bisulfite-sequencing PCR (BSP) and methylation-specific PCR (MSP). A chromatin immunoprecipitation (ChIP) assay and luciferase activity assay was used for the interaction between transcription factors and promoters and binding site determination, respectively. The effects of knockdown or overexpression of specificity protein 1 (SP1) or CDCA3 on GC cells in vitro were further assessed via wound healing assay, colony formation assay, and matrigel invasion assay.

RESULTS

In comparison to paired normal tissues, CDCA3 expressions were significantly increased in the GC tissues. The CDCA3 expression was regulated by DNA methylation, with the CpG island hypomethylation responsible for CDCA3 upregulation of GC. ChIP assays verified that the activity of SP1 binding to the CDCA3 promoter was dramatically increased. When the CDCA3 expression was downregulated in MKN45 cells by knockdown SP1, the proliferation ability, healing ability, and invasive ability were significantly suppressed.

CONCLUSION

The process by which SP1 bound to the nearest promoter region was expedited in GC cells, by which DNA was hypomethylated and CDCA3 expression was promoted. The effect on cell proliferation and invasion by CDCA3 was under the regulation of SP1 and also affected by hypomethylation of DNA.

Effect of interventional embolotherapy on FHIT and p16 expression in hepatocellular carcinoma patients

Effects of interventional embolotherapy on the expression of fragile histidine triad (FHIT) and p16 in hepatocellular carcinoma (HCC) patients were investigated. Patients with primary HCC who were definitely diagnosed and treated in the Department of Gastroenterology in Qingdao Central Hospital from March 2014 to March 2016 were selected, and they underwent interventional embolotherapy. HCC and cancer-adjacent tissues of the patients were harvested for immunohistochemical staining. The correlation between the expression levels of FHIT and p16 was analyzed at the gene and protein level. Clinical data were collected, and whether they were correlated with the expression of FHIT and p16 was investigated. The expression levels of FHIT and p16 in primary HCC tissues were remarkably lower than that in cancer-adjacent tissues (P<0.05). In HCC tissues, FHIT expression was obviously positively correlated with p16 expression (Spearman's correlation coefficient, r=0.308; P=0.025). FHIT was related to HCC tumor-node-metastasis (TNM) staging, the differentiation degree in Edmondson-Steiner grading, lymph node metastasis and portal vein thrombosis (P<0.05 in all comparisons), whereas, p16 was associated with tumor size and the differentiation degree in Edmondson-Steiner grading (P<0.05 in all comparisons). The expression of FHIT and p16 genes and proteins in HCC tissues were obviously lower than those in cancer-adjacent tissues (P<0.05 in all comparisons). FHIT and p16 genes, as tumor suppressor genes, inhibit the proliferation of HCC, and there is a positive correlation between them. The proteins of the FHIT and p16 can be used as new indicators for clinical detection, thus providing a new method for clinical diagnosis.

Epigenomic biomarkers for prognostication and diagnosis of gastrointestinal cancers

Altered epigenetic regulation is central to many human diseases, including cancer. Over the past two decade, major advances have been made in our understanding of the role of epigenetic alterations in carcinogenesis, particularly for DNA methylation, histone modifications and non-coding RNAs. Aberrant hypermethylation of DNA at CpG islands is a well-established phenomenon that mediates transcriptional silencing of tumor suppressor genes, and it is an early event integral to gastrointestinal cancer development. As such, detection of aberrant DNA methylation is being developed as biomarkers for prognostic and diagnostic purposes in gastrointestinal cancers. Diverse tissue types are suitable for the analyses of methylated DNA, such as tumor tissues, blood, plasma, and stool, and some of these markers are already utilized in the clinical setting. Recent advances in the genome-wide epigenomic approaches are enabling the comprehensive mapping of the cancer methylome, thus providing new avenues for mining novel biomarkers for disease prognosis and diagnosis. Here, we review the current knowledge on DNA methylation biomarkers for the prognostication and non-invasive diagnosis of gastrointestinal cancers and highlight their clinical application.

Clinical significance of expression of proliferating cell nuclear antigen and E-cadherin in gastric carcinoma

AIM

to investigate the expression of proliferating cell nuclear antigen (PCNA) and E-cadherin in gastric carcinoma and to analyze their clinical significance.

METHODS

A total of 146 patients were selected for this study, including 38 patients with intestinal metaplasia, 42 with dysplasia, and 66 with primary gastric cancer. In addition, 40 patients with normal gastric tissues were selected as controls. The expression of PCNA and E-cadherin was detected by immunohistochemistry. Differences in PCNA and the E-cadherin labeling indexes among normal gastric mucosa, intestinal metaplasia, dysplasia, and gastric carcinoma were compared. Subjects with normal gastric tissues were assigned to a normal group, while gastric cancer patients were assigned to a gastric cancer group. The difference in PCNA and E-cadherin expression between these two groups was compared. The relationship between expression of PCNA and E-cadherin and clinicopathological features was also explored in gastric cancer patients. Furthermore, prognosis-related factors, as well as the expression of PCNA and E-cadherin, were analyzed in patients with gastric cancer to determine the 3-year survival of these patients.

RESULTS

The difference in PCNA and the E-cadherin labeling indexes among normal gastric mucosa, intestinal metaplasia, dysplasia, and gastric carcinoma was statistically significant (P < 0.05). During the transition of normal gastric mucosa to gastric cancer, the PCNA labeling index gradually increased, while the E-cadherin labeling index gradually decreased (P < 0.05). The PCNA labeling index was significantly higher and the E-cadherin labeling index was significantly lower in gastric cancer than in dysplasia (P < 0.05). The expression of PCNA was significantly higher in the gastric cancer group than in the normal group, but E-cadherin was weaker (P < 0.05). There was a negative correlation between the expression of PCNA and E-cadherin in gastric carcinoma (r = -0.741, P = 0.000). PCNA expression differed significantly between gastric cancer patients with and without lymph node metastasis and between patients at different T stages. E-cadherin expression also differed significantly between gastric cancer patients with and without lymph node metastasis (P < 0.05). High T stage and positive PCNA expression were risk factors for the prognosis of patients with gastric cancer (RR > 1), while the positive expression of E-cadherin was a protective factor (RR < 1). The sensitivity, specificity, and accuracy of PCNA positivity in predicting the 3-year survival of patients with gastric cancer were 93.33%, 38.89%, and 0.64, respectively; while these values for E-cadherin negativity were 80.0%, 41.67%, and 0.59, respectively. When PCNA positivity and E-cadherin negativity were combined, the sensitivity, specificity, and accuracy were 66.67%, 66.67%, and 0.67, respectively.

CONCLUSION

Combined detection of PCNA and E-cadherin can improve the accuracy of assessing the prognosis of patients with gastric cancer.

Challenges of deciphering gastric cancer heterogeneity

Gastric cancer is in decline in most developed countries; however, it still accounts for a notable fraction of global mortality and morbidity related to cancer. High-throughput methods are rapidly changing our view and understanding of the molecular basis of gastric carcinogenesis. Today, it is widely accepted that the molecular complexity and heterogeneity, both inter- and intra-tumour, of gastric adenocarcinomas present significant obstacles in elucidating specific biomarkers for early detection of the disease. Although genome-wide sequencing and gene expression studies have revealed the intricate nature of the molecular changes that occur in tumour landscapes, the collected data and results are complex and sometimes contradictory. Several aberrant molecules have already been tested in clinical trials, although their diagnostic and prognostic utilities have not been confirmed thus far. The gold standard for the detection of sporadic gastric cancer is still the gastric endoscopy, which is considered invasive. In addition, genome-wide association studies have confirmed that genetic variations are important contributors to increased cancer risk and could participate in the initiation of malignant transformation. This hypothesis could in part explain the late onset of sporadic gastric cancers. The elaborate interplay of polymorphic low penetrance genes and lifestyle and environmental risk factors requires additional research to decipher their relative impacts on tumorigenesis. The purpose of this article is to present details of the molecular heterogeneity of sporadic gastric cancers at the DNA, RNA, and proteome levels and to discuss issues relevant to the translation of basic research data to clinically valuable tools. The focus of this work is the identification of relevant molecular changes that could be detected non-invasively.

Association of DNA Methylation with Acute Mania and Inflammatory Markers

In order to determine whether epigenetic changes specific to the manic mood state can be detected in peripheral blood samples we assayed DNA methylation levels genome-wide in serum samples obtained from 20 patients hospitalized for mania and 20 unaffected controls using the Illumina 450K methylation arrays. We identified a methylation locus in the CYP11A1 gene, which is regulated by corticotropin, that is hypo-methylated in individuals hospitalized for mania compared with unaffected controls. DNA methylation levels at this locus appear to be state related as levels in follow-up samples collected from mania patients six months after hospitalization were similar to those observed in controls. In addition, we found that methylation levels at the CYP11A1 locus were significantly correlated with three inflammatory markers in serum in acute mania cases but not in unaffected controls. We conclude that mania is associated with alterations in levels of DNA methylation and inflammatory markers. Since epigenetic markers are potentially malleable, a better understanding of the role of epigenetics may lead to new methods for the prevention and treatment of mood disorders.

Cancer type-specific epigenetic changes: gastric cancer

Gastric cancer (GC) remains a major cause of mortality despite declining rate in the world. Epigenetic alterations contribute significantly to the development and progression of gastric tumors. Epigenetic refers to the number of modifications of the chromatin structure that affect gene expression without altering the primary sequence of DNA, and these changes lead to transcriptional activation or silencing of the gene. Over the years, the study of epigenetic processes has increased, and novel therapeutic approaches have emerged. This chapter summarizes the main epigenomic mechanisms described recently involved in gastric carcinogenesis, focusing on the roles that aberrant DNA methylation, histone modifications (histone acetylation and methylation), and miRNAs (oncogenic and tumor suppressor function of miRNA) play in the onset and progression of gastric tumors. Clinical implications of these epigenetic alterations in GC are also discussed.