The significance of aberrant CHFR methylation for clinical response to microtubule inhibitors in gastric cancer

Methylation of CpG Sites as Biomarkers Predictive of Drug-Specific Patient Survival in Cancer

Background:

Though the development of targeted cancer drugs continues to accelerate, doctors still lack reliable methods for predicting patient response to standard-of-care therapies for most cancers. DNA methylation has been implicated in tumor drug response and is a promising source of predictive biomarkers of drug efficacy, yet the relationship between drug efficacy and DNA methylation remains largely unexplored.

Method:

In this analysis, we performed log-rank survival analyses on patients grouped by cancer and drug exposure to find CpG sites where binary methylation status is associated with differential survival in patients treated with a specific drug but not in patients with the same cancer who were not exposed to that drug. We also clustered these drug-specific CpG sites based on co-methylation among patients to identify broader methylation patterns that may be related to drug efficacy, which we investigated for transcription factor binding site enrichment using gene set enrichment analysis.

Results:

We identified CpG sites that were drug-specific predictors of survival in 38 cancer-drug patient groups across 15 cancers and 20 drugs. These included 11 CpG sites with similar drug-specific survival effects in multiple cancers. We also identified 76 clusters of CpG sites with stronger associations with patient drug response, many of which contained CpG sites in gene promoters containing transcription factor binding sites.

Conclusion:

These findings are promising biomarkers of drug response for a variety of drugs and contribute to our understanding of drug-methylation interactions in cancer. Investigation and validation of these results could lead to the development of targeted co-therapies aimed at manipulating methylation in order to improve efficacy of commonly used therapies and could improve patient survival and quality of life by furthering the effort toward drug response prediction.

Deciphering CHFR Role in Pancreatic Ductal Adenocarcinoma

Checkpoint with forkhead-associated and ring finger domains (CHFR) has been proposed as a predictive and prognosis biomarker for different tumor types, but its role in pancreatic ductal adenocarcinoma (PDAC) remains unknown. The aim of this study was two-pronged: to review the role of CHFR in PDAC and evaluating CHFR as a potential predictive biomarker in this disease. For this purpose, we first explored the CHFR messenger (m)RNA expression and promoter methylation through the TCGA database. Secondly, the CHFR expression and promoter methylation were prospectively evaluated in a cohort of patients diagnosed with borderline (n = 19) or resectable (n = 16) PDAC by immunohistochemistry (IHC), methylation specific-PCR (MSP), and pyrosequencing. The results from the TCGA database showed significant differences in terms of progression-free survival (PFS) and overall survival (OS) based on the CHFR mRNA expression, which was likely independent from the promoter methylation. Importantly, our results showed that in primarily resected patients and also the entire cohort, a higher CHFR expression as indicated by the higher IHC staining intensity might identify patients with longer disease-free survival (DFS) and OS, respectively. Similarly, in the same cohorts, patients with lower methylation levels by pyrosequencing showed significantly longer OS than patients without this pattern. Both, the CHFR expression intensity and its promoter methylation were established as independent prognostic factors for PFS and OS in the entire cohort. In contrast, no significant differences were found between different methylation patterns for CHFR and the response to taxane-based neoadjuvant treatment. These results suggest the potential role of the higher expression of CHFR and the methylation pattern of its promoter as potential prognostic biomarkers in PDAC, thus warranting further comprehensive studies to extend and confirm our preliminary findings.

Roles of E3 ubiquitin ligases in gastric cancer carcinogenesis and their effects on cisplatin resistance

Although gastric cancer (GC) is one of the most common cancers with high incidence and mortality rates, its pathogenesis is still not elucidated. GC carcinogenesis is complicated and involved in the activation of oncoproteins and inactivation of tumor suppressors. The ubiquitin-proteasome system (UPS) is crucial for protein degradation and regulation of physiological and pathological processes. E3 ubiquitin ligases are pivotal enzymes in UPS, containing various subfamily proteins. Previous studies report that some E3 ligases, including SKP2, CUL1, and MDM2, act as oncoproteins in GC carcinogenesis. On the other hand, FBXW7, FBXL5, FBXO31, RNF43, and RNF180 exert as tumor suppressors in GC carcinogenesis. Moreover, E3 ligases modulate cell growth, cell apoptosis, and cell cycle; thus, it is complicated to confer cisplatin resistance/sensitivity in GC cells. The intrinsic and acquired cisplatin resistance limits its clinical application against GC. In this review, we explore oncogenic and tumor suppressive roles of E3 ligases in GC carcinogenesis and focus on the effects of E3 ligases on cisplatin resistance in GC cells, which will provide novel therapeutic targets for GC therapy, especially for cisplatin-resistant patients.

Five gene signatures were identified in the prediction of overall survival in resectable pancreatic cancer

Background

Although genes have been previously detected in pancreatic cancer (PC), aberrant genes that play roles in resectable pancreatic cancer should be further assessed.

Methods

Messenger RNA samples and clinicopathological data corrected with PC were downloaded from The Cancer Genome Atlas (TCGA). Resectable PC patients were randomly divided into a primary set and a validation set. Univariable Cox regression analysis, lasso-penalized Cox regression analysis, and multivariable Cox analysis were implemented to distinguish survival-related genes (SRGs). A risk score based on the SRGs was calculated by univariable Cox regression analysis. A genomic-clinical nomogram was established by integrating the risk score and clinicopathological data to predict overall survival (OS) in resectable PC.

Results

Five survival-related genes (AADAC, DEF8, HIST1H1C, MET, and CHFR) were significantly correlated with OS in resectable PC. The resectable PC patients, based on risk score, were sorted into a high-risk group that showed considerably unfavorable OS (p < 0.001) than the low-risk group, in both the primary set and the validation set. The concordance index (C-index) was calculated to evaluate the predictive performance of the nomogram were respectively in the primary set [0.696 (0.608–0.784)] and the validation set [0.682 (0.606–0.758)]. Additionally, gene set enrichment Analysis discovered several meaningful enriched pathways.

Conclusion

Our study identified five prognostic gene biomarkers for OS prediction and which facilitate postoperative molecular target therapy for the resectable PC, especially the nomic-clinical nomogram which may be used as an effective model for the postoperative OS evaluation and also an optimal therapeutic tool for the resectable PC.

CHFR Promoter Hypermethylation Is Associated with Gastric Cancer and Plays a Protective Role in Gastric Cancer Process

Background: Chromosomally unstable tumors account for 50% of gastric cancer. CHFR plays a role in controlling chromosomal instability and its inactivation will eventually lead to tumorigenesis. In addition to genetic deletion, DNA methylation could silence the expression of many cancer-related genes including CHFR. Its methylation was found to be associated with the initiation and progression of gastric cancer.

Methods: We performed a meta-analysis involving methylation analyses of CHFR promoter in gastric cancer. Nineteen studies with 1,249 tumor tissues and 745 normal tissues had been included in current study.

Results: We found that CHFR methylation was significantly higher in gastric cancer (studies numbers = 15, cases/controls = 862/745, odds ratio (OR) = 7.46, 95% confidence index (95% CI) = 4.99-11.14). Methylation array data was also obtained from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas network (TCGA). There were 7 out of 13 CHFR methylation probes target to the same CpG island region (hg19, 131973620-131975130) showed the CHFR methylation was higher in gastric cancers than normal controls. Eight probes showed CHFR promoter hypermethylation was associated with longer overall survival of gastric cancer patients (Hazard Ratio < 1).

Conclusions: The CHFR promoter hypermethylation was associated with gastric cancer and played a protective role in gastric cancer process. Its methylation could be a potential biomarker for the diagnosis and prognosis of gastric cancer.

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.

Epigenetic Mechanisms and Events in Gastric Cancer-Emerging Novel Biomarkers

Gastric cancer is one of the most common malignancy worldwide. The various genetic and epigenetic events have been found to be associated with its carcinogenesis. The epigenetic is a heritable and transient/reversible change in the gene expression that is not accompanied by modification in the DNA sequence. This event is characterized by the alteration in the promoter CpG island of the gene or histone modification. These events are associated with silencing of critical tumor suppressor gene and activation of oncogenes leading to carcinogenesis. The DNA methylation is a chemical change in the DNA sequence that most commonly occurs at cytosine moiety of CpG dinucleotide and histone, primarily on N- terminal tail that ultimately effect the interaction of DNA with chromatin modifying protein.Hypermethylation of tumor suppressor genes and global hypomethylation of oncogenes are widely studied epigenetic modifications. There are large number of publish reports regarding epigenetic events involving gastric cancer. These changes are potentially useful in identifying markers for early diagnosis and management of this lethal malignancy. Also, role of specific miRNAs and long non coding RNAs in regulation of gene expression is gaining interest and is a matter of further investigation. In this review, we aimed to summarize major epigenetic events (DNA methylation) in gastric cancer along with alteration in miRNAs and long non coding RNAs which plays an important role in pathology of this poorly understood malignancy.

CHFR Promoter Hypermethylation and Reduced CHFR mRNA Expression in Ovarian Cancer

Background

Ovarian cancer is one of the most common cancers and can be treated with microtubule-targeting drugs. Checkpoint with forkhead and ring finger domains (CHFR) is a protein implicated in cancer sensitivity to microtubule-targeting drugs. Whereas CHFR downregulation, often with CHFR promoter hypermethylation, has been identified in a large number of tumor types, it has not been in ovarian cancer. We therefore searched for CHFR downregulation in primary ovarian tumors.

Methods

Fresh ovarian cancer tissues from 53 patients (test) and normal ovarian tissues from 21 patients (control) were tested for CHFR promoter hypermethylation and CHFR mRNA levels.

Results

The CHFR promoter was hypermethylated in 20.75% (11/53) of the ovarian cancers and none (0/21) of the normal controls. The normal controls had a mean mRNA level of 1.89 relative fluorescence units (RFU) with a range of 0.04–24.78 RFU. The cancer tissues had a mean mRNA level of 0.77 RFU with a range of 0.00–68.75 RFU. The median value of the cancer group was significantly lower than that of the control group (p=0.0067). Those cancer samples that had hypermethylated CHFR promoters also had low (n=3) or undetectable (n=8) CHFR mRNA levels.

Conclusions

In contrast to previous reports, we found that alterations in CHFR mRNA and CHFR methylation can be frequently found in ovarian cancers. CHFR hypermethylation was strongly associated with the loss of CHFR mRNA expression. CHFR downregulation in ovarian tumors may be clinically relevant as a staging biomarker, as an indicator of sensitivity to microtubule-targeting drugs, and as a future drug target.

Clinicopathological significance of CHFR promoter methylation in gastric cancer: a meta-analysis

The mitotic checkpoint gene (CHFR) (Checkpoint with Forkhead-associated and Ring finger domains is a G2 phase/mitosis checkpoint and tumor-suppressor gene. Recent studies have reported the relationship of CHFR promoter methylation with clinicopathological significance of gastric cancer. However, the results remain unclear due to small size of sample. We pooled 15 studies including 827 gastric cancer patients and conducted a meta-analysis to investigate the clinicopathological significance of CHFR promoter methylation in gastric cancer. Our data revealed that the frequency of CHFR promoter methylation was higher in gastric cancer than in normal gastric tissue, Odd Ratio (OR) was 10.12 with 95% CI 5.17–19.79, p < 0.00001. Additionally, the rate of CHFR promoter methylation was significantly increased in high grade of gastric cancer compared to low grade, OR was 1.64 with 95% CI 1.00–2.68, p = 0.05. CHFR methylation was significantly associated with the positive lymph node metastasis, OR was 1.56 with 95% CI 1.05–2.32, p = 0.03. We concluded that CHFR could serve as a biomarker for diagnosis of gastric cancer, and a drug target for development of gene therapy in gastric cancer. CHFR promoter methylation is associated with tumor poor differentiation and lymph node metastasis.

Clinicopathological significance of CHFR methylation in non-small cell lung cancer: a systematic review and meta-analysis

Checkpoint with Forkhead-associated and Ring finger domains (CHFR) is a G2/M checkpoint and tumor-suppressor gene. Recent publications showed the correlation of CHFR promoter methylation with clinicopathological significance of non-small cell lung cancer (NSCLC), however, the results remain inconsistent. The aim of this study is to investigate the Clinicopathological significance of CHFR promoter methylation in NSCLC with a meta-analysis. A total of nine studies were included in the meta-analysis that 816 patients were involved. Our data indicated that the frequency of CHFR promoter methylation was higher in NSCLC than in normal lung tissue, Odd Ratios (OR) was 9.92 with 95% corresponding confidence interval (CI) 2.17-45.23, p = 0.003. Further subgroup analysis revealed that CHFR promoter was more frequently methylated in squamous cell carcinoma (SCC) than in adenocarcinoma (ADC), OR was 4.46 with 95% CI 1.65-12.05, p = 0.003, suggesting the mechanism of SCC pathogenesis is different from ADC. Notably, CHFR promoter methylation was correlated with smoking behavior in NSCLC. In conclusion, CHFR could be a biomarker for diagnosis of NSCLC, and a promising drug target for development of gene therapy in SCC. CHFR promoter methylation is potentially associated with poor overall survival, additional studies need to be carried out for confirmation in future.

Association between CHFR gene hypermethylation and gastric cancer risk: a meta-analysis

BACKGROUND

The association between the hypermethylation of CHFR gene and gastric cancer risk has been investigated by a number of studies. However, the sample size of the majority of these studies was very small. To get a more a convincing conclusion, here we performed a meta-analysis of the previously published studies to assess the association between CHFR methylation and the risk of gastric cancer.

METHODS

Eligible studies were identified by searching the MEDLINE/PubMed, Embase, and Web of Science databases before May 2016 without any language restriction. The strength of the association was estimated by odds ratio with its 95% confidence interval (CI).

RESULTS

Totally 1,399 samples, including 758 gastric cancer cases and 641 controls, from 13 studies were included in the present meta-analysis. Compared with non-cancer controls, the pooled OR of CHFR methylation in gastric cancer patients was 9.08 (95% CI: 6.40-12.88, P<0.001), suggesting that the methylation of CHFR was significantly associated with increased risk of gastric cancer. Similar results were observed when subgroup analyses were performed stratified by country, ethnicity, and methylation testing methods.

CONCLUSION

Our meta-analysis showed a strong positive correlation between CHFR methylation and risk of gastric cancer, suggesting that CHFR methylation might be a promising biomarker for the diagnosis of gastric cancer.

CHFR promoter methylation indicates poor prognosis in stage II microsatellite stable colorectal cancer

PURPOSE

Data on the prognostic significance of promoter CpG island methylation in colorectal cancer (CRC) are conflicting, possibly due to associations between methylation and other factors affecting survival such as genetic alterations and use of adjuvant therapy. Here, we examine the prognostic impact of promoter methylation in patients with CRC treated with surgery alone in the context of microsatellite instability (MSI), BRAF and KRAS mutations.

EXPERIMENTAL METHODS

One hundred and seventy-three CRCs were analyzed for promoter methylation of 19 tumor suppressor and DNA repair genes, the CpG island methylator phenotype (CIMP), MSI, the exon 15 V600E BRAF mutation and KRAS codon 12 and 13 mutations.

RESULTS

Unsupervised hierarchical clustering based on methylation status of 19 genes revealed three subgroups: cluster 1 [CL1, 57% (98/173) of CRCs], cluster 2 [CL2, 25% (43/173) of CRCs], and cluster 3 [CL3, 18% (32/173) of CRCs]. CL3 had the highest methylation index (0.25, 0.49, and 0.69, respectively, P = <0.01) and was strongly associated with CIMP (P < 0.01). Subgroup analysis for tumor stage, MSI, and BRAF status showed no statistically significant differences in survival between CL1, CL2, and CL3 nor between CIMP and non-CIMP CRCs. Analyzing genes separately revealed that CHFR promoter methylation was associated with a poor prognosis in stage II, microsatellite stability (MSS), BRAF wild-type (WT) CRCs: multivariate Cox proportional HR = 3.89 [95% confidence interval (CI), 1.58-9.60, P < 0.01; n = 66] and HR = 2.11 (95% CI, 0.95-4.69, P = 0.068, n = 136) in a second independent population-based study.

CONCLUSIONS

CHFR promoter CpG island methylation, which is associated with MSI, also occurs frequently in MSS CRCs and is a promising prognostic marker in stage II, MSS, BRAF WT CRCs.

Emerging evidence for CHFR as a cancer biomarker: from tumor biology to precision medicine

Novel insights in the biology of cancer have switched the paradigm of a “one-size-fits-all” cancer treatment to an individualized biology-driven treatment approach. In recent years, a diversity of biomarkers and targeted therapies has been discovered. Although these examples accentuate the promise of personalized cancer treatment, for most cancers and cancer subgroups no biomarkers and effective targeted therapy are available. The great majority of patients still receive unselected standard therapies with no use of their individual molecular characteristics. Better knowledge about the underlying tumor biology will lead the way toward personalized cancer treatment. In this review, we summarize the evidence for a promising cancer biomarker: checkpoint with forkhead and ring finger domains (CHFR). CHFR is a mitotic checkpoint and tumor suppressor gene, which is inactivated in a diverse group of solid malignancies, mostly by promoter CpG island methylation. CHFR inactivation has shown to be an indicator of poor prognosis and sensitivity to taxane-based chemotherapy. Here we summarize the current knowledge of altered CHFR expression in cancer, the impact on tumor biology and implications for personalized cancer treatment.

Epigenetic alterations in gastric cancer (Review)

Gastric cancer is one of the most common types of cancer and the second most common cause of cancer-related mortality worldwide. An increasing number of recent studies have confirmed that gastric cancer is a multistage pathological state that arises from environmental factors; dietary factors in particulary are considered to play an important role in the etiology of gastric cancer. Improper dietary habits are one of the primary concerns as they influence key molecular events associated with the onset of gastric carcinogenesis. In the field of genetics, anticancer research has mainly focused on the various genetic markers and genetic molecular mechanisms responsible for the development of this of this disease. Some of this research has proven to be very fruitful, providing insight into the possible mechamisms repsonsible for this disease and into possible treatment modalities. However, the mortality rate associated with gastric cancer remains relatively high. Thus, epigenetics has become a hot topic for research, whereby genetic markers are bypassed and this research is directed towards reversible epigenetic events, such as methylation and histone modifications that play a crucial role in carcinogenesis. The present review focuses on the epigenetic events which play an important role in the development and progression of this deadly disease, gastric cancer.

Predictive value of CHFR and MLH1 methylation in human gastric cancer

BACKGROUND

Gastric carcinoma (GC) has one of the highest mortality rates of cancer diseases and has a high incidence rate in China. Palliative chemotherapy is the main treatment for advanced gastric cancer. It is necessary to compare the effectiveness and toxicities of different regimens. This study explores the possibility of methylation of DNA damage repair genes serving as a prognostic and chemo-sensitive marker in human gastric cancer.

METHODS

The methylation status of five DNA damage repair genes (CHFR, FANCF, MGMT, MLH1, and RASSF1A) was detected by nested methylation-specific PCR in 102 paraffin-embedded gastric cancer samples. Chi-square or Fisher's exact tests were used to evaluate the association of methylation status and clinic-pathological factors. The Kaplan-Meier method and Cox proportional hazards models were employed to analyze the association of methylation status and chemo-sensitivity.

RESULTS

The results indicate that CHFR, MLH1, RASSF1A, MGMT, and FANCF were methylated in 34.3% (35/102), 21.6% (22/102), 12.7% (13/102), 9.8% (10/102), and 0% (0/102) of samples, respectively. No association was found between methylation of CHFR, MLH1, RASSF1A, MGMT, or FANCF with gender, age, tumor size, tumor differentiation, lymph node metastasis, and TNM stage. In docetaxel-treated gastric cancer patients, resistance to docetaxel was found in CHFR unmethylated patients by Cox proportional hazards model (HR 0.243, 95% CI, 0.069-0.859, p = 0.028), and overall survival is longer in the CHFR methylated group compared with the CHFR unmethylated group (log-rank, p = 0.036). In oxaliplatin-treated gastric cancer patients, resistance to oxaliplatin was found in MLH1 methylated patients (HR 2.988, 95% CI, 1.064-8.394, p = 0.038), and overall survival was longer in the MLH1 unmethylated group compared with the MLH1 methylated group (log-rank, p = 0.046).

CONCLUSIONS

CHFR is frequently methylated in human gastric cancer, and CHFR methylation may serve as a docetaxel-sensitive marker. MLH1 methylation was related to oxaliplatin resistance in gastric cancer patients.

Methylation-mediated gene silencing as biomarkers of gastric cancer: A review

Despite a decline in the overall incidence of gastric cancer (GC), the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem. The best means of improving the survival of GC patients is to screen for and treat early lesions. However, GC is often diagnosed at an advanced stage and is associated with a poor prognosis. Current diagnostic and therapeutic strategies have not been successful in decreasing the global burden of the disease; therefore, the identification of reliable biomarkers for an early diagnosis, predictive markers of recurrence and survival and markers of drug sensitivity and/or resistance is urgently needed. The initiation and progression of GC depends not only on genetic alterations but also epigenetic changes, such as DNA methylation and histone modification. Aberrant DNA methylation is the most well-defined epigenetic change in human cancers and is associated with inappropriate gene silencing. Therefore, an increasing number of genes methylated at the promoter region have been targeted as possible biomarkers for different purposes, including early detection, classification, the assessment of the tumor prognosis, the development of therapeutic strategies and patient follow-up. This review article summarizes the current understanding and recent evidence regarding DNA methylation markers in GC with a focus on the clinical potential of these markers.

CHFR protein expression predicts outcomes to taxane-based first line therapy in metastatic NSCLC

PURPOSE

Currently, there is no clinically validated test for the prediction of response to tubulin-targeting agents in non-small cell lung cancer (NSCLC). Here, we investigated the significance of nuclear expression of the mitotic checkpoint gene checkpoint with forkhead and ringfinger domains (CHFR) as predictor of response and overall survival with taxane-based first-line chemotherapy in advanced stage NSCLC.

METHODS

We studied a cohort of 41 patients (median age 63 years) with advanced NSCLC treated at the Atlanta VAMC between 1999 and 2010. CHFR expression by immunohistochemistry (score 0-4) was correlated with clinical outcome using chi-square test and Cox proportional models. A cutoff score of "3" was determined by receiver operator characteristics analysis for "low" CHFR expression. Results were validated in an additional 20 patients who received taxane-based chemotherapy at Emory University Hospital and the Atlanta VAMC.

RESULTS

High expression (score = 4) of CHFR is strongly associated with adverse outcomes: the risk for progressive disease after first-line chemotherapy with carboplatin-paclitaxel was 52% in patients with CHFR-high versus only 19% in those with CHFR-low tumors (P = 0.033). Median overall survival was strongly correlated with CHFR expression status (CHFR low: 9.9 months; CHFR high: 6.2 months; P = 0.002). After multivariate adjustment, reduced CHFR expression remained a powerful predictor of improved overall survival (HR = 0.24; 95% CI, 0.1-0.58%; P = 0.002). In the validation set, low CHFR expression was associated with higher likelihood of clinical benefit (P = 0.03) and improved overall survival (P = 0.038).

CONCLUSIONS

CHFR expression is a novel predictive marker of response and overall survival in NSCLC patients treated with taxane-containing chemotherapy.

DNA methylation biomarkers in cancer: progress towards clinical implementation

Altered DNA methylation is ubiquitous in human cancers and specific methylation changes are often correlated with clinical features. DNA methylation biomarkers, which use those specific methylation changes, provide a range of opportunities for early detection, diagnosis, prognosis, therapeutic stratification and post-therapeutic monitoring. Here we review current approaches to developing and applying DNA methylation biomarkers in cancer therapy. We discuss the obstacles that have so far limited the routine use of DNA methylation biomarkers in clinical settings and describe ways in which these obstacles can be overcome. Finally, we summarize the current state of clinical implementation for some of the most widely studied and well-validated DNA methylation biomarkers, including SEPT9, VIM, SHOX2, PITX2 and MGMT.

Assessment of Chemosensitivity-related Aberrant Methylation of Nonsmall Cell Lung Cancer by EBUS-TBNA

BACKGROUND

Multigene aberrant methylation profiling may predict response to chemotherapy in lung cancer. The purpose of this study was to analyze the feasibility of detecting aberrant methylation in biopsy samples obtained by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).

METHODS

Lymph node samples from 30 patients with nonsmall cell lung cancer diagnosed as metastatic carcinoma by EBUS-TBNA were analyzed. Histologic cores obtained by EBUS-TBNA were separately stored at -80°C. DNA was extracted from EBUS-TBNA samples and bisulfate modification was performed. We evaluated the methylation status of a panel of 6 genes (FANCF, Reprimo, TMS1/ASC, activated protein-2α, CHFR, and ATM) using methylation-specific polymerase chain reaction. Twenty-four patients with adenocarcinoma or squamous cell carcinoma metastasis received platinum-based combination chemotherapy. We reviewed their response to chemotherapy in correlation to the methylation status.

RESULTS

Bisulfate modification was successfully performed in all samples using DNA obtained from EBUS-TBNA samples by checking p16 unmethylation expression. Aberrant methylation was detected as follows: 9 cases of FANCF (30.0%), 14 cases of Reprimo (46.7%), 10 cases of TMS1/ASC (33.3%), and 19 cases of activated protein-2α (63.3%). In response to chemotherapy, there were 1 complete response, 6 partial response, 12 stable disease, and 5 progressive disease (PD) cases. The number of methylated genes was significantly smaller in the PD group than in the non-PD groups (P=0.0435).

CONCLUSIONS

Aberrant methylation analysis can be performed in metastatic lymph nodes sampled by EBUS-TBNA. EBUS-TBNA allows for genetic evaluations of tumor cells and may help to guide the most effective treatment strategies in the near future.

Epigenetics and genetics in endometrial cancer: new carcinogenic mechanisms and relationship with clinical practice

Endometrial cancer is the seventh most common cancer worldwide among females. An increased incidence and a younger age of patients are also predicted to occur, and therefore elucidation of the pathological mechanisms is important. However, several aspects of the mechanism of carcinogenesis in the endometrium remain unclear. Associations with genetic mutations of cancer-related genes have been shown, but these do not provide a complete explanation. Therefore, epigenetic mechanisms have been examined. Silencing of genes by DNA hypermethylation, hereditary epimutation of DNA mismatch repair genes and regulation of gene expression by miRNAs may underlie carcinogenesis in endometrial cancer. New therapies include targeting epigenetic changes using histone deacetylase inhibitors. Some cases of endometrial cancer may also be hereditary. Thus, patients with Lynch syndrome which is a hereditary disease, have a higher risk for developing endometrial cancer than the general population. Identification of such disease-related genes may contribute to early detection and prevention of endometrial cancer.

CHFR: a key checkpoint component implicated in a wide range of cancers

CHFR (Checkpoint with Forkhead-associated and RING finger domains) has been implicated in a checkpoint regulating entry into mitosis. However, the details underlying its roles and regulation are unclear due to conflicting lines of evidence supporting different notions of its functions. We provide here an overview of how CHFR is thought to contribute towards regulating mitotic entry and present possible explanations for contradictory observations published on the functions and regulation of CHFR. Furthermore, we survey key data showing correlations between promoter hypermethylation or down-regulation of CHFR and cancers, with a view on the likely reasons why different extents of correlations have been reported. Lastly, we explore the possibilities of exploiting CHFR promoter hypermethylation status in diagnostics and therapeutics for cancer patients. With keen interest currently focused on the association between hypermethylation of CHFR and cancers, details of how CHFR functions require further study to reveal how its absence might possibly contribute to tumorigenesis.

Clinical potential of DNA methylation in gastric cancer: a meta-analysis

BACKGROUND

Accumulating evidence indicates aberrant DNA methylation is involved in gastric tumourigenesis, suggesting it may be a useful clinical biomarker for the disease. The aim of this study was to consolidate and summarize published data on the potential of methylation in gastric cancer (GC) risk prediction, prognostication and prediction of treatment response.

METHODS

Relevant studies were identified from PubMed using a systematic search approach. Results were summarized by meta-analysis. Mantel-Haenszel odds ratios were computed for each methylation event assuming the random-effects model.

RESULTS

A review of 589 retrieved publications identified 415 relevant articles, including 143 case-control studies on gene methylation of 142 individual genes in GC clinical samples. A total of 77 genes were significantly differentially methylated between tumour and normal gastric tissue from GC subjects, of which data on 62 was derived from single studies. Methylation of 15, 4 and 7 genes in normal gastric tissue, plasma and serum respectively was significantly different in frequency between GC and non-cancer subjects. A prognostic significance was reported for 18 genes and predictive significance was reported for p16 methylation, although many inconsistent findings were also observed. No bias due to assay, use of fixed tissue or CpG sites analysed was detected, however a slight bias towards publication of positive findings was observed.

CONCLUSIONS

DNA methylation is a promising biomarker for GC risk prediction and prognostication. Further focused validation of candidate methylation markers in independent cohorts is required to develop its clinical potential.

CHFR suppression by hypermethylation sensitizes endometrial cancer cells to paclitaxel

OBJECTIVE

Impairment of a cell cycle checkpoint is often associated with sensitivity to chemotherapeutic drugs. Here, we studied the correlations between the checkpoint with forkhead-associated and ring finger (CHFR) gene expression and responses to paclitaxel in endometrial cancer cells.

METHODS

We cultured 6 endometrial cancer cell lines exposed to paclitaxel, studied the cell cytotoxicity, cell cycle distribution, CHFR expression, and methylation status before and after a demethylation agent (5-aza) treatment. CHFR was silenced by small interfering RNA (siRNA). Then we examined tumor growth and CHFR expression with paclitaxel alone or combined with 5-aza pretreatment in vivo.

RESULTS

We found that HEC-1B, RL-952, and AN3CA cells were sensitive to paclitaxel. Moreover, CHFR was weakly expressed in these cells, whereas paclitaxel-resistant cells (ISH, HEC-1A, and KLE) had high CHFR expression. Then we found that restored expression of CHFR by demethylation decreased the sensitivity to paclitaxel in AN3CA cells. In addition, cells with CHFR demethylation resulted in G2/M phase arrest that induced to paclitaxel resistance. These results were confirmed again in small interfering RNA-transfected HEC-1A cells. Furthermore, in nude mice model, restored expression of CHFR by demethylation inhibited tumor growth and decreased sensitivity to paclitaxel.

CONCLUSION

Our data suggest that CHFR suppression regulated by hypermethylation may sensitize endometrial cancer cells to paclitaxel, and CHFR may be a promising marker to predict the response of endometrial cancer to paclitaxel.

CHFR: A Novel Mitotic Checkpoint Protein and Regulator of Tumorigenesis

Checkpoint with FHA and RING finger domains (CHFR) was first recognized as an early mitotic checkpoint protein that delayed the cell cycle in response to microtubule-targeting drugs. It is an E3 ubiquitin ligase that ubiquitinates target proteins to direct them to the proteasome for degradation or to alter their activity. To date, however, the downstream target proteins critical to CHFR's normal cellular functions largely remain unidentified with the exception of the key mitosis regulators, and oncogenes, PLK1 and Aurora A kinases. Rapidly growing evidence in mice, primary human tumors, and mammalian cell culture models indicate that CHFR may also function as a potent tumor suppressor. Interestingly, studies reported to date suggest that CHFR both controls a novel prophase checkpoint early in mitosis and regulates chromosome segregation later in mitosis to maintain genomic stability. In addition, loss of CHFR sensitizes cancer cells to microtubule poisons, altering chemoresponsiveness to taxanes and making it a potential biomarker for chemotherapeutic response. Importantly, CHFR may be one of the few proteins that are required for regulating the cell cycle and maintaining genomic instability to inhibit tumorigenesis.

Promoter methylation of p16, Runx3, DAPK and CHFR genes is frequent in gastric carcinoma

AIMS AND BACKGROUND

Transcriptional silencing induced by hypermethylation of CpG islands in the promoter regions of genes is believed to be an important mechanism of carcinogenesis in human cancers including gastric cancer. A number of reports on methylation of various genes in gastric cancer have been published, but most of these studies focused on cancer tissues or only a single gene. In this study, we determined the promoter hypermethylation status and mRNA expression of 4 genes: p16, Runx3, DAPK and CHFR.

METHODS

Methylation-specific polymerase chain reaction (MSP) was used to determine the methylation status of p16, Runx3, DAPK and CHFR gene promoters in cancer and adjacent normal gastric mucosa specimens from 70 patients with gastric cancer, as well as normal gastric biopsy samples from 30 people without cancer serving as controls. In addition, the mRNA expression of p16, Runx3, DAPK and CHFR was investigated in 34 gastric cancer patients by RT-PCR. Bisulfite DNA sequence analysis was applied to check the positive samples detected by MSP.

RESULTS

When carcinoma specimens were compared with adjacent normal gastric mucosa samples, a significant increase in promoter methylation of p16, Runx3, DAPK and CHFR was observed, while all 30 histologically normal gastric specimens were methylation free for all 4 genes. The methylation rate of the 4 genes increased from normal stomach tissue to tumor-adjacent gastric mucosa to gastric cancer tissue. Concurrent methylation in 2 or more genes was found in 22.9% of tumor-adjacent normal gastric mucosa and 75.7% of cancer tissues. No correlation was found between hypermethylation and other clinicopathological parameters such as sex, age, and tumor location. However, the frequency of DAPK and CHFR methylation in cancer tissues was significantly associated with the extent of differentiation and lymph node metastasis (P < 0.05) and the frequency of Runx3 methylation was significantly associated with tumor size (P < 0.05). Weak expression and loss of expression of the 4 genes was observed in cancer tissues and was significantly associated with promoter hypermethylation (P < 0.05).

CONCLUSIONS

Promoter hypermethylation of p16, Runx3, DAPK and CHFR is frequent in gastric cancer. DAPK and CHFR promoter hypermethylation may be an important help in evaluating the differentiation grade and lymph node status of gastric cancer. Weak gene expression and loss of gene expression due to promoter hypermethylation may be a cancer-specific event.

Aberrant gene methylation in the peritoneal fluid is a risk factor predicting peritoneal recurrence in gastric cancer

AIM: To investigate whether gene methylation in the peritoneal fluid (PF) predicts peritoneal recurrence in gastric cancer patients.

METHODS: The gene methylation of CHFR (checkpoint with forkhead and ring finger domains), p16, RUNX3 (runt-related transcription factor 3), E-cadherin, hMLH1 (mutL homolog 1), ABCG2 (ATP-binding cassette, sub-family G, member 2) and BNIP3 (BCL2/adenovirus E1B 19 kDa interacting protein 3) were analyzed in 80 specimens of PF by quantitative methylation-specific polymerase chain reaction (PCR). Eighty patients were divided into 3 groups; Group A (n = 35): the depth of cancer invasion was less than the muscularis propria; Group B (n = 31): the depth of cancer invasion was beyond the muscularis propria. Both group A and B were diagnosed as no cancer cells in peritoneal cytology and histology; Group C (n = 14): disseminated nodule was histologically diagnosed or cancer cells were cytologically defined in the peritoneal cavity.

RESULTS: The positive rates of methylation in CHFR, E-cadherin and BNIP3 were significantly different among the 3 groups and increased in order of group A, B and C (0%, 0% and 21% in CHFR, P < 0.05; 20%, 45% and 50% in E-cadherin, P < 0.05; 26%, 35% and 71% in BNIP3, P < 0.05). In addition, the multigene methylation rate among CHFR, E-cadherin and BNIP3 was correlated with group A, B and C (9%, 19% and 57%, P < 0.001). Moreover, the prognosis was analyzed in group B, excluding 3 patients who underwent a non-curative resection. Two of the 5 patients with multigene methylation showed peritoneal recurrence after surgery, while those without or with a single gene methylation did not experience recurrence (P < 0.05).

CONCLUSION: This study suggested that gene methylation in the PF could detect occult neoplastic cells in the peritoneum and might be a risk factor for peritoneal metastasis.

Aberrant gene methylation in the lymph nodes provides a possible marker for diagnosing micrometastasis in gastric cancer

BACKGROUND

This study was designed to determine whether gene methylation is a novel diagnostic marker for micrometastasis to the lymph nodes (LNs) in gastric cancer.

METHODS

The gene methylation of CHFR, p16, RUNX3, E-cadherin, MGMT, hMLH1, and ABCG2 genes were analyzed in 49 primary gastric cancer tissues, corresponding to noncancerous tissues and matched LNs by quantitative methylation-specific PCR (q-MSP).

RESULTS

CHFR, RUNX3, MGMT, and hMLH1 were more frequently methylated in primary cancer compared with the noncancerous mucosa. Further analyses investigated whether the methylation of the four cancer-specific genes was preserved in LN tissues using the 29 control cases, in which LN metastasis had been histologically confirmed. The methylation of both lesions (M/M pattern) in at least one gene, which was judged to be positive for cancer cells in LNs, was observed in 25 of 29 cases (86%). Quantitative RT-PCR (qRT-PCR) of CEA, CK19, and CK20 mRNA was conducted using the same samples. The mRNA expression of at least one of the three genes was observed in 100% of the specimens. The results of the control analysis were used to attempt to predict micrometastasis by q-MSP and qRT-PCR in the 20 test cases without histological LN metastasis. Six cases (30%) showed the M/M pattern in at least one of the four genes. Three of 20 cases (15%) exhibited both the M/M pattern and positive mRNA.

CONCLUSIONS

The methylation analysis revealed the clinical feasibility of detecting occult neoplastic cells in the regional LNs.

Cancer DNA methylation: molecular mechanisms and clinical implications

DNA methylation plays a crucial role in the regulation of gene expression and chromatin organization within normal eukaryotic cells. In cancer, however, global patterns of DNA methylation are altered with global hypomethylation of repeat-rich intergenic regions and hypermethylation of a subset of CpG-dense gene-associated regions (CpG islands). Extensive research has revealed the cellular machinery that catalyzes DNA methylation, as well as several large protein complexes that mediate the transcriptional repression of hypermethylated genes. However, research is only just beginning to uncover the molecular mechanisms underlying the origins of cancer-specific DNA methylation. Herein, we present several recent advances regarding these mechanisms and discuss the relationship between histone modifications (i.e., H3K4me2/3, H4K16Ac, H3K9me2/3, H3K27me3, H4K20me3), chromatin-modifying enzymes (G9a, EZH2, hMOF, SUV4-20H), and aberrant DNA methylation. Additionally, the role played by inflammation, DNA damage, and miRNAs in the etiology of aberrant DNA methylation is considered. Finally, we discuss the clinical implications of aberrant DNA methylation and the utility of methylated biomarkers in cancer diagnosis and management.

Checkpoint with forkhead-associated and ring finger promoter hypermethylation correlates with microsatellite instability in gastric cancer

AIM: To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring finger (CHFR) and microsatellite mutator status in 59 primary gastric cancers.

METHODS: We investigated the promoter methylation of CHFR in 59 cases of gastric cancer using methylation-specific PCR. Five microsatellite loci were analyzed using high-intensity microsatellite analysis reported previously, and p53 gene mutations were investigated by direct sequencing.

RESULTS: Twenty cases (33.9%) showed promoter methylation and no relation was observed with the clinicopathological factors. We found that the promoter methylation of CHFR was frequently accompanied with microsatellite instability (MIN). Seven of 20 (35.0%) cases showed MIN in hypermethylation of the CHFR tumor, while three of 39 (7.7%) cases showed MIN in the non-methylated CHFR tumor (P < 0.01). However, we failed to find any relationship between CHFR methylation and p53 mutation status.

CONCLUSION: The coordinated loss of both the mitotic check point function and mismatch repair system suggests the potential to overcome the cell cycle check point, which may lead to an accumulation of mutations. However, the p53 mutation was not related to hypermethylation of the CHFR promoter and MIN, which indicates that an abnormality in p53 occurs as an independent process from the mismatch repair deficiency in carcinogenesis.

Cancer epigenomics: implications of DNA methylation in personalized cancer therapy

Genetic alterations in cancer can provide information for predicting a tumor's sensitivity to chemotherapeutic drugs. But although such information is certainly useful, the relatively low frequency of mutations seen in many cancers limits the utility of pharmacogenomics in large numbers of cancer patients, necessitating consideration of other approaches. Epigenetic changes such as DNA methylation are a hallmark of human cancers. Methylation of genes involved in DNA repair and maintaining genome integrity (e.g. MGMT, hMLH1, WRN, and FANCF), and cell-cycle checkpoint genes (e.g. CHFR and 14-3-3 sigma, CDK10, and p73), all reportedly influence the sensitivity to chemotherapeutic drugs, suggesting that DNA methylation could serve as a molecular marker for predicting the responsiveness of tumors to chemotherapy. However, the comprehensive study of pharmacoepigenomics awaits the advent of genome-wide analysis of DNA methylation using microarrays and next-generation sequencers.

DNA methylation and cancer pathways in gastrointestinal tumors

Cancer is fundamentally a genetic and epigenetic disease that requires the accumulation of genomic alterations that inactivate tumor suppressors and activate proto-oncogenes. In addition to genetic mutation or allelic loss, epigenetic gene silencing associated with DNA methylation is now recognized as an alternative mechanism by which tumor suppressor genes are inactivated. In gastrointestinal cancers, for example, DNA methylation frequently alters the activity in a number of important signaling pathways by silencing expression of genes encoding Wnt antagonists, negative Ras effectors and p53 targets. Indeed, the list of genes aberrantly methylated in cancer is growing, and methylation of a p53 target micoRNA gene has recently been demonstrated. Sites of DNA methylation could be promising markers and targets for risk assessment, early detection and treatment of cancer.

Mechanism and pathobiologic implications of CHFR promoter methylation in gastric carcinoma

AIM: To investigate the aberrant methylation of CHFR promoter in human gastric cancer (GC) and its impact on the expression of CHFR mRNA and protein, as well as its correlation with clinical and histological features of human GC.

METHODS: Methylation-specific polymerase chain reaction (MSPCR) was used to detect the methylation status of CHFR promoter in 20 primary GC samples and paired normal gastric mucosa. The CHFR mRNA and protein expressions were investigated both by RT-PCR and by Western blotting. The CHFR protein expression in 69 GC samples was immunohistochemically examined.

RESULTS: The DNA methylation of the CHFR gene was found in 9 of the 20 GC samples (45%) and the down-regulation of CHFR mRNA and protein was significantly associated with the methylation status of the CHFR gene (P = 0.006). In 20 samples of corresponding non-neoplastic mucosa, no DNA methylation of the CHFR gene was detected. The CHFR gene methylation in poorly differentiated GC samples was significantly higher than that in well-differentiated GC samples (P = 0.014). Moreover, the negative CHFR protein expression rate in paraffin-embedded GC samples was 55.07% (38/69), the positive rate in poorly differentiated GC samples was 36.73% (18/49), which was significantly lower than 65.00% (13/20) in well-differentiated GC samples (χ² = 4.586, P = 0.032).

CONCLUSION: Aberrant methylation of the CHFR gene may be involved in the carcinogenesis and development of GC, and is the predominant cause of down-regulation or loss of CHFR mRNA or protein expression. As aberrant methylation of CHFR promoter is correlated with tumor differentiation, it may help to predict the prognosis of GC and CHFR may become a novel target of gene therapy for GC in the future.

Nasopharyngeal carcinoma--review of the molecular mechanisms of tumorigenesis

Nasopharyngeal carcinoma (NPC) is a head and neck cancer rare throughout most of the world but common in certain geographic areas, such as southern Asia. While environmental factors and genetic susceptibility play important roles in NPC pathogenesis, the Epstein-Barr virus in particular has been implicated in the molecular abnormalities leading to NPC. There is upregulation of cellular proliferation pathways such as the Akt pathway, mitogen-activated protein kinases, and the Wnt pathway. Cell adhesion is compromised due to abnormal E-cadherin and beta-catenin function. Aberrations in cell cycle are due to dysregulation of factors such as p16, cyclin D1, and cyclin E. Anti-apoptotic mechanisms are also upregulated. There are multiple abnormalities unique to NPC that are potential targets for novel treatments.

The anti-proliferative effects of the CHFR depend on the forkhead associated domain, but not E3 ligase activity mediated by ring finger domain

The CHFR protein comprises fork head associated- (FHA) and RING-finger (RF) domain and is frequently downregulated in human colon and gastric cancers up to 50%. The loss of CHFR mRNA expression is a consequence of promoter methylation, suggesting a tumor suppressor role for this gene in gastrointestinal carcinogenesis. In terms of the biological functions of CHFR, it has been shown to activate cell cycle checkpoint when cells are treated with microtubule depolymerizing agents. Furthermore, CHFR was reported to have E3 ligase activity and promote ubiquitination and degradation of oncogenic proteins such as Aurora A and polo-like kinase 1. However, molecular pathways involved in the tumor suppressive function of CHFR are not yet clear since the two established roles of this protein are likely to inhibit cell growth. In this study, we have identified that the FHA domain of CHFR protein is critical for growth suppressive properties, whereas the RF and cysteine rich domains (Cys) are not required for this function. In contrast, the RF and Cys domains are essential for E3 ligase activity of CHFR. By the use of a cell cycle checkpoint assay, we also confirmed that the FHA domain of CHFR plays an important role in initiating a cell cycle arrest at G2/M, indicating a functional link exists between the anti-proliferative effects and checkpoint function of this tumor suppressor protein via this domain. Collectively, our data show that the checkpoint function of the FHA domain of CHFR is a core component of anti-proliferative properties against the gastrointestinal carcinogenesis.

Yeast Chfr homologs retard cell cycle at G1 and G2/M via Ubc4 and Ubc13/Mms2-dependent ubiquitination

Checkpoint with forkhead-associated and RING (Chfr) is a ubiquitin ligase (E3) that establishes an antephase or prometaphase checkpoint in response to mitotic stress. Though ubiquitination is essential for checkpoint function, the sites, linkages and ubiquitin conjugating enzyme (E2) specificity are controversial. Here we dissect the function of the two Chfr homologs in S. cerevisiae, Chf1 and Chf2, overexpression of which retard cell cycle at both G(1) and G(2). Using a genetic assay, we establish that Ubc4 is required for Chf2-dependent G(1) cell cycle delay and Chf protein turnover. In contrast, Ubc13/Mms2 is required for G(2) delay and does not contribute to Chf protein turnover. By reconstituting cis and trans-ubiquitination activities of Chf proteins in purified systems and characterizing sites modified and linkages formed by tandem mass spectrometry, we discovered that Ubc13/Mms2- dependent modifications are a distinct subset of those catalyzed by Ubc4. Mutagenesis of Lys residues identified in vitro indicates that site-specific Ubc4-dependent Chf protein autoubiquitination is responsible for Chf protein turnover. Thus, combined genetic and biochemical analyses indicate that Chf proteins have dual E2 specificity accounting for different functions in the cell cycle.

Quantitative double-fluorescence immunohistochemistry (qDFIHC), a novel technology to assess protein expression: a pilot study analyzing 5-FU sensitive markers thymidylate synthase, dihydropyrimidine dehydrogenase and orotate phosphoribosyl transferases in gastric cancer tissue specimens

To evaluate the protein expression level in formalin-fixed cancer tissue specimens, the authors devised quantitative double-fluorescence immunohistochemistry (qDFIHC). Using this method, the 17 gastric cancer biopsy specimens, before undergoing S-1 based neoadjuvant chemotherapy, were assessed in order to determine the expression levels of the thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT) and dihydropyrimidine dehydrogenase (DPD) which determines S-1 efficacy. The ratios of OPRT/TS, OPRT/DPD and OPRT/(DPD+TS) which have been proposed to show a good correlation with S-1 efficacy, were calculated and compared with the clinical response. A significant difference was thus observed in OPRT/TS (P=0.0049), OPRT/DPD (P=0.0067) and OPRT/(DPD+TS) (P=0.0013) between the responder and the non-responder groups. Therefore, the ratios assessed by qDFIHC may be a potentially effective predictor of the S-1 efficacy. Furthermore, qDFIHC may also be a useful method for assessing various protein levels in cancer tissues.

Aberrant methylation of p16 predicts candidates for 5-fluorouracil-based adjuvant therapy in gastric cancer patients

BACKGROUND

Aberrant methylation of some cancer-related genes has been reported to correlate with sensitivity to chemotherapeutic agents. The present study was designed to determine whether DNA methylation in six cancer-related genes affects recurrence of gastric cancer in patients who received 5-fluorouracil-based adjuvant chemotherapy.

METHODS

The methylation status of six genes, MGMT, CHFR, hMLH1, p16INK4a, E-cadherin, and Runx3, was analyzed in 56 surgically resected gastric cancer tissue specimens by methylation-specific polymerase chain reaction. Of the 56 patients who underwent surgical resection, 38 received 5-fluorouracil (5-FU)-based adjuvant chemotherapy postoperatively (adjuvant group), whereas the other 18 (32%) did not (surgery group).

RESULTS

There were no significant differences between the two groups with respect to sex, cancer differentiation, depth of tumor invasion, lymph node metastasis, lymphatic invasion, vascular invasion and tumor stage. Among the genes, methylation of p16INK4a showed a significant correlation with longer survival in the 38 patients of the adjuvant group, but not in the 18 patients of the surgery group. A multivariate analysis identified p16INK4a methylation to be an independent factor predicting a longer recurrence-free period under 5-FU-based adjuvant chemotherapy.

CONCLUSIONS

The present study demonstrated for the first time that gastric cancer patients with p16INK4a methylation specifically benefit from 5-FU-based adjuvant chemotherapy.

Advance in the relationship between checkpoint with fork head associated and ring finger gene and carcinomas of digestive tract

CHFR (checkpoint with fork head associated and ring finger), a novel checkpoint gene, was frequently inactivated in human cancers. In response to mitotic stress, it causes a delay in chromosome condensation during prophase. Studies have showed that the direct target of the CHFR pathway was Plk1. In vitro-translated Plk1 is ubiquitinated, in a CHFR-dependent manner, both in Xenopus interphase extracts as well as in a purified system reconstituted with recombinant proteins. In addition, by excluding Cyclin B1 from the nucleus, regulating Aurora-A level and acting with the P38 stress kinases, CHFR blocks entry to mitosis prophase in mammalian cells. Besides, USP7 can remove ubiquitin moiety from the autoubiquitinated CHFR both in vivo and in vitro, which results in the accumulation of CHFR in the cells. Thus, USP7-mediated deubiquitination of CHFR leads to its accumulation, which might be a key regulatory step for CHFR activation. CHFR expression is frequently silenced by aberrant methylation in the carcinomas of digestive tract. In this article, we reviewed the progress of research on the structure of CHFR gene and effect of CHFR protein as well as its relation to the carcinomas of digestive tract.

Protein expression of checkpoint with fork head associated and ring finger and mutant p53 and their clinicopathological significances in gastric cancer

AIM: To investigate the relationship between the expression of checkpoint with fork head associated and ring finger (CHFR) and P53 protein in gastric cancer (GC) and the clinicopathologic characteristics, and to explore the correlated molecular mechanism of CHFR and p53 genes in gastric carcinogenesis.

METHODS: Five paraffin blocks of tissue microarray were constructed using a Tissue Array Machine (Steve Leighton Beecher Instruments, USA), including 151 cases of primary GC (101 cases with matched normal mucosa, intestinal metaplasia or dysplasia). Envision immunohistochemical method was employed to detect the protein expression of CHFR and mutant p53 in GC and precancerous tissues mentioned above.

RESULTS: The positive rate of CHFR protein expression in GC (49.67%, 75/151) was significantly lower than that in normal gastric mucosa (85.25%, 52/61)(P < 0.05). The down-regulation or absence of mitotic checkpoint CHFR protein expression was correlated with the sex of GC patients. The absent rate of CHFR protein expression in the female GC patients was significantly higher than that in the male GC ones (64% vs 43.56%, P < 0.05). The absent rates was also significantly different between GC patients of Borrmann Ⅲ + Ⅳ and Ⅰ + Ⅱ types (57.14% vs 34.78%, P < 0.05). In the present study, though CHFR protein expression showed no significant difference among various histological types of GC, the absent rate of CHFR protein expression was the highest (71.43%) in signet ring cell carcinoma. The absent expression of CHFR protein was not related to the depth of invasion and lymph node metastasis of GC. In addition, no correlation was found between the expression of CHFR and P53 protein expression in GC (P > 0.05).

CONCLUSION: Down-regulation or absence of mitotic checkpoint CHFR protein expression is frequent events in GC and may take a part in gastric carcinogenesis. Abnormal expression of CHFR may be of more importance in the development of female patients and diffuse-type GC.