The value of serum RASSF10 hypermethylation as a diagnostic and prognostic tool for gastric cancer

DNA Methylation: An Important Biomarker and Therapeutic Target for Gastric Cancer

Gastric cancer (GC) is a very common malignancy with a poor prognosis, and its occurrence and development are closely related to epigenetic modifications. Methylation of DNA before or during gastric cancer is an interesting research topic. This article reviews the studies on DNA methylation related to the cause, diagnosis, treatment, and prognosis of gastric cancer and aims to find cancer biomarkers to solve major human health problems.

Molecular basis for RASSF10/NPM/RNF2 feedback cascade-mediated regulation of gastric cancer cell proliferation

Ras-association domain family (RASSF) proteins are encoded by numerous tumor suppressor genes that frequently become silenced in human cancers. RASSF10 is downregulated by promoter hypermethylation in cancers and has been shown to inhibit cell proliferation; however, the molecular mechanism(s) remains poorly understood. Here, we demonstrate for the first time that RASSF10 inhibits Cdk1/cyclin-B kinase complex formation to maintain stable levels of cyclin-B for inducing mitotic arrest during cell cycle. Using LC-MS/MS, live cell imaging, and biochemical approaches, we identify Nucleophosmin (NPM) as a novel functional target of RASSF10 and revealed that RASSF10 expression promoted the nuclear accumulation of GADD45a and knockdown of either NPM or GADD45a, resulting in impairment of RASSF10-mediated G2/M phase arrest. Furthermore, we demonstrate that RASSF10 is a substrate for the E3 ligase ring finger protein 2 (RNF2) and show that an NPM-dependent downregulation of RNF2 expression is critical to maintain stable RASSF10 levels in cells for efficient mitotic arrest. Interestingly, the Kaplan–Meier plot analysis shows a positive correlation of RASSF10 and NPM expression with greater gastric cancer patient survival and the reverse with expression of RNF2, suggesting that they may have a role in cancer progression. Finally, our findings provide insights into the mode of action of the RASSF10/NPM/RNF2 signaling cascade on controlling cell proliferation and may represent a novel therapeutic avenue for the prevention of gastric cancer metastasis.

The Tumor Suppressor Role of the Ras Association Domain Family 10

The Ras association domain family 10(RASSF10), a tumor suppressor gene, is located on human chromosome 11p15.2, which is one of the members homologous to other N-terminal RASSF families obtained through structural prediction. RASSF10 plays an important role in inhibiting proliferation, invasion, and migration, inducing apoptosis, making cancer cells sensitive to docetaxel, and capturing G2/M phase. Some studies have found that RASSF10 may inhibit the occurrence and development of tumors by regulating Wnt/β-catenin, P53, and MMP2. Methylation of tumor suppressor gene promoter is a key factor in the development and progression of many tumors. Various methylation detection methods confirmed that the methylation and downregulation of RASSF10 often occur in various tumors, such as gastric cancer, lung cancer, colon cancer, breast cancer, and leukemia. The status of RASSF10 methylation is positively correlated with tumor size, tumor type, and TNM stage. RASSF10 methylation can be used as a prognostic factor for overall survival and disease-free survival, and is also a sign of tumor diagnosis and sensitivity to docetaxel chemotherapy. In this review, we mainly elucidate the acknowledged structure and progress in the verified functions of RASSF10 and the probably relevant signaling pathways.

Cell-free DNA as a liquid biopsy for early detection of gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors with poor prognosis worldwide, mainly due to the lack of suitable modalities for population-based screening and early detection of this disease. Therefore, novel and less invasive tests with improved clinical utility are urgently required. The remarkable advances in genomics and proteomics, along with emerging new technologies for highly sensitive detection of genetic alterations, have shown the potential to map the genomic makeup of a tumor in liquid biopsies, in order to assist with early detection and clinical management. The present review summarize the current status in the identification and development of cell-free DNA (cfDNA)-based biomarkers in GC, and also discusses their potential utility and the technical challenges in developing practical cfDNA-based liquid biopsy for early detection of GC.

Diagnostic and prognostic value of the peripheral natural killer cell levels in gastric cancer

Peripheral blood lymphocyte subsets have been reported to be useful as prognostic and/or diagnostic markers for patients with cancer. However, the clinical value of peripheral blood lymphocyte subsets in gastric cancer (GC) has remained elusive. In the present study, peripheral CD3⁺, CD4⁺ and CD8⁺ T lymphocytes, B cells (CD19⁺), regulatory T cells (Tregs; CD4⁺CD25⁺CD127^-) and natural killer (NK) cells (CD3^-CDl6⁺CD56⁺) were detected by flow cytometry in 122 patients with GC, 80 healthy donors (HDs) and 80 patients with gastric ulcer (GU). NK cells (CD56⁺) were detected by immunohistochemical (IHC) analysis in 20 GC and three GU tissue samples. A receiver-operating characteristic (ROC) curve was used to determine the threshold of the peripheral NK cell level and survival analysis was performed to assess its prognostic value in patients with GC. The results indicated that the peripheral NK cell proportion in patients with GC (18.77%) was significantly higher than that in the HD (12.19%) and GU (12.74%) groups. IHC analysis suggested that the NK level in GC tumor samples was correlated with that in paired serum samples. ROC curve analysis indicated that the peripheral NK cell level (15.16%) was able to effectively identify patients with GC, a diagnostic sensitivity of 75.41% and a specificity of 77.45% were determined. Multivariate logistic regression analysis revealed that the peripheral NK cell level was independently associated with the T stage and survival analysis demonstrated that high levels of peripheral NK cells were associated with poor prognosis of patients with GC. In conclusion, the peripheral NK cell level may be a diagnostic and prognostic marker for patients with GC.

Nap1l1 Controls Embryonic Neural Progenitor Cell Proliferation and Differentiation in the Developing Brain

The precise function and role of nucleosome assembly protein 1-like 1 (Nap1l1) in brain development are unclear. Here, we find that Nap1l1 knockdown decreases neural progenitor cell (NPC) proliferation and induces premature neuronal differentiation during cortical development. A similar deficiency in embryonic neurogenesis was observed in Nap1l1 knockout (KO) mice, which were generated using the CRISPR-Cas9 system. RNA sequencing (RNA-seq) analysis indicates that Ras-associated domain family member 10 (RassF10) may be the downstream target of Nap1l1. Furthermore, we found that Nap1l1 regulates RassF10 expression by promoting SETD1A-mediated H3K4 trimethylation at the RassF10 promoter. Nap1l1 KO defects may be rescued by RassF10 overexpression, suggesting that Nap1l1 controls NPC differentiation through RassF10. Our findings reveal an essential role for the Nap1l1 histone chaperone in cortical neurogenesis during early embryonic brain development.

Predictive value of the serum RASSF10 promoter methylation status in gastric cancer

Background

This study aimed to investigate whether the detection of methylation in the promoter of the Ras association domain family 10 gene (RASSF10) in the serum of patients with gastric cancer (GC) by methylation-specific PCR (MSP) can be used as a diagnostic and prognostic indicator of GC.

Methods

We used MSP to examine RASSF10 methylation levels in the serum and/or tumor samples from 100 GC patients, 50 patients with chronic atrophic gastritis (CAG), and 45 healthy controls (HC). We also analyzed clinicopathological and follow-up data.

Results

Our results showed that the rate of serum RASFF10 promoter methylation among patients with GC (49/100) was higher than in those with CAG (1/50) or HC (0/45). Moreover, the RASSF10 methylation status was consistent between serum and tumor tissues. GC patients with serum RASSF10 promoter methylation had significantly shorter overall survival and disease-free survival times than GC patients without serum RASSF10 promoter methylation. Multivariable Cox regression analysis showed that serum RASSF10 promoter methylation and lymph node metastasis both correlated with reduced survival in GC patients.

Conclusions

Detection of the serum RASSF10 methylation status by MSP is feasible as a diagnostic and prognostic indicator of GC.

Epigenetic biomarkers in gastrointestinal cancers: The current state and clinical perspectives

Each year, almost 4.1 million people are diagnosed with gastrointestinal (GI) cancers. Due to late detection of this disease, the mortality is high, causing approximately 3 million cancer-related deaths annually, worldwide. Although the incidence and survival differs according to organ site, earlier detection and improved prognostication have the potential to reduce overall mortality burden from these cancers. Epigenetic changes, including aberrant promoter DNA methylation, are common events in both cancer initiation and progression. Furthermore, such changes may be identified non-invasively with the use of PCR based methods, in bodily fluids of cancer patients. These features make aberrant DNA methylation a promising substrate for the development of disease biomarkers for early detection, prognosis and for predicting response to therapy. In this article, we will provide an update and current clinical perspectives for DNA methylation alterations in patients with colorectal, gastric, pancreatic, liver and esophageal cancers, and discuss their potential role as cancer biomarkers.

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.

Diagnostic accuracy of DNA methylation in detection of gastric cancer: a meta-analysis

Emerging studies demonstrate the diagnostic utility of DNA methylation-based blood test for gastric cancer. The aim of the meta-analysis is to evaluate the accuracy of blood DNA methylation markers for detecting patients with gastric cancer. A systematic literature search to November 2016 that evaluated DNA methylation markers utilizing blood specimen to detect gastric cancer were selected to derive pooled sensitivities and specificities. 32 studies including 4,172 patients (gastric cancer (N = 2,098), control (N = 2,074)) met the study criteria. Overall sensitivity of DNA methylation-based blood test for detecting gastric cancer was 57% (95% CI 50–63%); specificity was 97% (95% CI 95–98%). Among patients who received plasma-based testing, sensitivity was 71% (95% CI 59–81%); specificity was 89% (95% CI 78–94%). Among patients who received serum-based testing, sensitivity was 50% (95% CI 43–58%); specificity was 98% (95% CI 96–99%). Using multiple methylated genes had sensitivity of 76% (95% CI 64–84%); specificity of 85% (95% CI 65–95%). DNA methylation test had sensitivity of 55% (95% CI 47–64%) and specificity of 96% (95% CI 92–98%) for detecting TNM stage I+II gastric cancer. In conclusion, blood-based DNA methylation test had high specificity but modest sensitivity for detecting gastric cancer. Evaluating multiple methylated genes or using plasma sample may improve the diagnostic sensitivity.

DNA hypermethylation of tumor suppressor genes RASSF6 and RASSF10 as independent prognostic factors in adult acute lymphoblastic leukemia

BACKGROUND

The Hypermethylation of Ras association domain family (RASSF) often plays a key role in malignant progression of solid tumors; however, their impact on the prognosis and survival of adult ALL patients remain elusive.

METHODS

The frequency of the promoter methylation pattern of RASSF6 and RASSF10 were analyzed in the peripheral blood (PB) samples taken at the time of diagnosis of 45 ALL patients. The methylation-specific PCR (MSP) assay was used to detect the DNA methylation patterns.

RESULTS

RASSF6 was frequently hypermethylated in patients diagnosed with pre-B-ALL (90.9%) and B-ALL (87.5%), followed by T-ALL (66.7%); whereas, RASSF10 methylation was more confined to T-ALL (80%) as compared to B-ALL (25%) and pre-B ALL (9.1%) patients. Moreover, hypermethylation of RASSF6 was significantly associated with a poor prognosis and shorter overall survival (OS) in patients with pre-B-ALL (log-rank test; P=0.041).

CONCLUSION

RASSF6 and RASSF10 were frequently hypermethylated in the samples at the time of diagnosis of adult ALL patients. Our study represents the first report of methylation of RASSF6 at a high frequency in patients with pre-B ALL. Furthermore, hypermethylation of RASSF6 was significantly associated with inferior overall survival in pre-B ALL patients. It may suggest that the frequent epigenetic inactivation of RASSF6 plays an important role in the pathogenesis and progression of pre-B-ALL.

Low expression of RASSF10 is associated with poor survival in patients with colorectal cancer

The RASSF10 has been identified as a tumor suppressor in human colorectal cancer (CRC). However, the expression of RASSF10 in patients with CRC has not been evaluated for its potential use as a biomarker in the diagnosis and prognosis assessment of CRC. We analyzed the expression of RASSF10 mRNA (n=30) and protein (n=205) in CRC and matched noncancerous colon tissue samples to explore the relationships among RASSF10 expression, clinicopathological factors, and prognosis in patients with CRC. Our results showed that the expression of RASSF10 mRNA and protein in CRC-adjacent tissues was higher than that in CRC tissues. Low RASSF10 expression was associated with the T stage (P=.037, odds ratio, 0.664; 95% confidence interval, 0.452-0.975) and the N stage (P<.001, odds ratio, 0.318; 95% confidence interval, 0.184-0.549) of the tumors. In addition, univariate analysis revealed that patients with CRC with lower RASSF10 expression had poorer overall survival (OS; P<.001) and disease-free survival (DFS; P<.001). The 5-year OS and DFS rates were 48.2% and 28.3%, respectively, in patients with low RASSF10 expression and 82.2% and 62.6%, respectively, in patients with high RASSF10 expression. Multivariate Cox regression analysis revealed that the strongest predictors of OS and DFS were RASSF10 expression (P<.001 and P<.001, respectively), T stage (P=.003 and P=.009, respectively), and N stage (P=.005 and P=.026, respectively). These results demonstrate that low expression of RASSF10 in CRC tissues is significantly correlated with poor survival after curative resection and may serve as a useful biomarker predictive of CRC prognosis.