Chfr expression is downregulated by CpG island hypermethylation in esophageal cancer

Multi-omic analysis of Esophageal Adenocarcinoma uncovers candidate therapeutic targets and cancer-selective post-transcriptional regulation

BACKGROUND

Efforts to address the poor prognosis associated with esophageal adenocarcinoma (EAC) have been hampered by a lack of biomarkers to identify early disease and therapeutic targets. Despite extensive efforts to understand the somatic mutations associated with EAC over the past decade, a gap remains in understanding how the atlas of genomic aberrations in this cancer impacts the proteome and which somatic variants are of importance for the disease phenotype.

METHODS

We performed a quantitative proteomic analysis of 23 EACs and matched adjacent normal esophageal and gastric tissues. We explored the correlation of transcript and protein abundance using tissue-matched RNA-seq and proteomic data from 7 patients and further integrated these data with a cohort of EAC RNA-seq data (n=264 patients), EAC whole-genome sequencing (n=454 patients) and external published datasets.

CENTRAL FINDINGS

We quantified protein expression from 5879 genes in EAC and patient-matched normal tissues. Several biomarker candidates with EAC-selective expression were identified including the transmembrane protein GPA33. We further verified the EAC-enriched expression of GPA33 in an external cohort of 115 patients and confirm this as an attractive diagnostic and therapeutic target. To further extend the insights gained from our proteomic data, an integrated analysis of protein and RNA expression in EAC and normal tissues revealed several genes with poorly correlated Protein and RNA abundance, suggesting post-transcriptional regulation of protein expression. These outlier genes including SLC25A30, TAOK2, and AGMAT, only rarely demonstrated somatic mutation suggesting post-transcriptional drivers for this EAC-specific phenotype. AGMAT was demonstrated to be over-expressed at the protein level in EAC compared to adjacent normal tissues with an EAC-selective, post-transcriptional mechanism of regulation of protein abundance proposed.

CONCLUSIONS

By quantitative proteomic analysis we have identified GPA33 as an EAC-selective biomarker. Integrated analysis of proteome, transcriptome, and genome in EAC has revealed several genes with tumor-selective, post-transcriptional regulation of protein expression which may be an exploitable vulnerability.

The prognostic value of 11th Japanese classification and 8th AJCC staging systems in Chinese patients with esophageal squamous cell carcinoma

BACKGROUND

Two staging systems, the 8th staging system by the American Joint Committee on Cancer (AJCC) and the 11th Japanese classification by Japan Esophageal Society (JES), are currently applied in the clinic for predicting the prognosis of patients with esophageal squamous cell carcinoma (ESCC). The differences between the two staging systems have been widely researched. However, little studies focus on the differences in specific staging between the two systems. Therefore, we aimed to compare the performance of different staging in predicting overall survival (OS) of Chinese patients with ESCC.

METHODS

This retrospective study included 268 patients who underwent radical esophagectomy and mediastinal lymph node dissection for ESCC between January 2008 and December 2013. Patients were staged by the 8th AJCC and 11th JES staging systems. OS was estimated using the Kaplan-Meier method and compared between N stages and between stage groupings using the log-rank test. Cox proportional hazards regression analysis was performed to identify factors independently related to outcome. Further, we compared the concordance indexes (C-indexes) of the two staging systems.

RESULTS

The mean age was 61.25 ± 7.056 years, median follow-up was 44.82 months, and 5-year OS rate was 47%. The OS was well predicted by the 8th AJCC N staging (P < 0.001) and the 11th JES N staging (P < 0.001), with a c-index of 0.638 (95% CI: 0.592-0.683) for AJCC N staging and 0.627 (95% CI: 0.583-0.670) for JES N staging (P = 0.13). In addition, the OS was also well predicted by stage groupings of the 8th AJCC (P < 0.001) and the 11th JES systems (P < 0.001), with a c-index of 0.658 (95% CI: 0.616-0.699) for 8th AJCC stage grouping and 0.629 (95% CI: 0.589-0.668) for the11th JES stage grouping (P = 0.211).

CONCLUSIONS

The prognostic effect of 11th JES staging system is comparable with that of AJCC 8th staging system for patients with ESCC. Therefore, both systems are applicable to clinical practice.

CHFR promotes metastasis of human gastric carcinoma by activating AKT and ERK via NRF2- ROS axis

Tumor suppressor gene CHFR (The Checkpoint with Forkhead-associated and Ring finger domains) is a mitotic checkpoint and frequently hypermethylated in gastric cancer. Our previous study found CHFR played a certain extent pro-tumor function in gastric cancer. However, little is known about the underlying mechanism. In this study, we tried to further elucidate the role and mechanism for CHFR in gastric cancer (GC) by constructing CHFR stably expressed cell lines. As expected, the ectopic expression of CHFR slowed the cell proliferation in both two SGC-7901 and AGS cells, while significantly promoted the potential of cell migration and invasion. For the first time, our data indicated that stable expression of CHFR in SGC-7901 and AGS restrained cellular reactive oxygen species (ROS) generation and promoted the activation of AKT and ERK, two regulators of redox hemostasis. Furthermore, H₂O₂ treatment effectively elevated ROS level and reversed CHFR-induced cell invasion in stable SGC-7901 and AGS cells with the decreased phosphorylation of AKT and ERK. We also confirmed that CHFR exerted its function by promoting NRF2 expression. The most important is, the ectopic expression of CHFR significantly inhibited SGC-7901 cell-derived xenografts and obviously promoted lung metastasis of GC cell with NRF2, p-AKT and p-ERK increased. Taken together, our findings suggested that CHFR might take part in gastric cancer progression especially cancer metastasis by activating AKT and ERK via NRF2- ROS axis.

Nutlin-3 acts as a DNA methyltransferase inhibitor to sensitize esophageal cancer to chemoradiation

Esophageal squamous cell carcinoma (ESCC) is highly resistant to chemoradiation therapy. We aimed to examine whether Nutlin-3, a molecule that suppresses murine double min 2 (MDM2)-mediated p53 and Retinoblastoma (RB) protein degradation leading to downregulation of DNA methyltransferases (DNMTs), can be a novel therapeutic agent for ESCC. We used wild-type and chemoradiation-resistant ESCC cell lines in this study. The expression of DNMTs, p53 and RB, and methylation level of tumor suppressor genes (TSG) were analyzed upon Nutlin-3 treatment. The antitumor efficacy of Nutlin-3 was investigated in ESCC cell lines and xenograft tumor model. TSG protein expression was checked in the excised tumor tissue. Nutlin-3 induced upregulation of p53 and RB and downregulation of DNMTs proteins in the chemoradiation-resistant and aggressive ESCC cells. The methylation level of TSGs was decreased by Nutlin-3. Nutlin-3 inhibits clonogenic growth of ESCC cells and exerts a synergistic cytotoxic-effect when combined with chemotherapeutic agent cisplatin. Moreover, xenograft tumor growth in SCID mice was suppressed by Nutlin-3. The protein expression level of DNMTs was downregulated, and that of TSGs was upregulated by Nutlin-3 treatment in the excised tumor tissue. In conclusion, Nutlin-3 is a potential therapeutic agent that can potentiate the treatment efficacy of chemoradiation-resistant ESCC.

Significance of promoter methylation of multiple tumor suppressor genes in hepatocellular carcinoma

Background

Methylation of the promoter at CpG islands is a mechanism of silencing tumor suppressor genes and therefore enhances cancer progression. The study aimed to examine promoter methylation frequencies of five tumor suppressor genes in hepatocellular carcinoma and their implication on the first-year outcome of surgical resection of the tumor. Fifty specimens of hepatocellular carcinoma and the adjacent non-tumorous liver tissue were collected from the surgically resected hepatic tumor. The status of promoter methylation of tumor suppressor genes RASSF1A, CHFR, MGMT, GSTP1, and hMLH1 was investigated using methylation-specific polymerase chain reaction.

Results

The frequency of promoter methylation of these tumor suppressors genes (TSG) genes in hepatocellular carcinoma was significantly higher than non-tumorous tissue all, P < 0.05, with a methylation rate of 80% in RASSF1A, 70% in CHFR, 46% in GSTP1, 56% in MGMT, and 10% in hMLH1. Methylation of RASSF1A, CHFR, and MGMT promoter genes was significantly associated with decreased first-year postoperative survival and increased recurrence of hepatocellular carcinoma, P < 0.05.

Conclusion

Methylated RASSF1A, CHRF, and MGMT promoters indicated poor prognosis among patients with hepatocellular carcinoma and may serve as potential prognostic indicators in patients with hepatocellular carcinoma.

Development of an Individualized Ubiquitin Prognostic Signature for Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is a common tumor type in genitourinary system and has a poor prognosis. Ubiquitin dependent modification systems have been reported in a variety of malignancies and have influenced tumor genesis and progression. However, the molecular characteristics and prognostic value of ubiquitin in ccRCC have not been systematically reported. In our study, 204 differentially expressed ubiquitin related genes (URGs) were identified from The Cancer Genome Atlas (TCGA) cohort, including 141 up-regulated and 63 down-regulated URGs. A total of seven prognostic related URGs (CDCA3, CHFR, CORO6, RNF175, TRIM72, VAV3, and WDR72) were identified by Cox regression analysis of differential URGs and used to construct a prognostic signature. Kaplan-Meier analysis confirmed that high-risk patients had a worse prognosis (P = 1.11e-16), and the predicted area under the receiver operating characteristic (ROC) curves were 0.735 at 1 year, 0.702 at 3 years, and 0.744 at 5 years, showing good prediction accuracy. Stratified analysis showed that the URGs-based prognostic signature could be used to evaluate tumor progression in ccRCC. Further analysis confirmed that the signature is an independent prognostic factor related to the prognosis of ccRCC patients, which may help to reveal the molecular mechanism of ccRCC and provide potential diagnostic and prognostic markers for ccRCC.

Analysis of the methylation of CpG islands in the CDO1, TAC1 and CHFR genes in pancreatic ductal cancer

No difference in the gene methylation status of tumor-suppression genes between pancreatic cancer tissues and adjacent non-cancer tissues is observed. The present study investigated whether the promoter CpG islands of the cysteine dioxygenase 1 (CDO1), tachykinin precursor 1 (TAC1) and checkpoint with forkhead and ring finger domains (CHFR) genes were methylated in pancreatic cancer and adjacent non-cancerous pancreatic tissue in order to determine if they could be considered as markers for the detection of pancreatic cancer. A total of 38 Formalin-fixed and paraffin-embedded pancreatic adenocarcinoma tissues and their adjacent non-cancerous specimens from patients with pancreatic cancer, as well as 9 non-cancerous pancreatic samples from patients without pancreatic adenocarcinoma were obtained following surgical resection. The hypermethylation of CpG islands was detected using a methylation-specific quantitative PCR. The methylation values were calculated using the ∆Cq method and were expressed as 2^−ΔCq. The 2^−ΔCq value of the CDO1 promoter from pancreatic adenocarcinoma specimens was significantly higher compared with that of adjacent non-cancerous and tumor-free pancreatic tissues (P<0.0001 and P=0.0008, respectively). The 2^−ΔCq value of the TAC1 promoter of pancreatic adenocarcinoma was also significantly higher compared with that of adjacent non-cancerous tissues and tumor-free pancreatic samples (both P<0.0001). However, there was no significant difference in the 2^−ΔCq value of the CHFR promoter among the pancreatic cancer, adjacent non-cancer tissue and tumor-free pancreatic samples. Furthermore, 12 out of the 38 pancreatic adenocarcinoma cases (31.6%) presented some methylation in the CHFR promoter. The results from Kaplan-Meier analysis between CHFR promoter methylation values and the clinicopathological characteristics of patients with pancreatic adenocarcinoma demonstrated that CHFR promoter methylation was significantly associated with lymph node metastasis. The methylation values of CDO1 and TAC1 promoters in cancer tissues were higher compared with adjacent tissues. However, whether hypermethylation of CDO1 and TAC1 promoters may serve as a biomarker in the diagnosis of pancreatic adenocarcinoma remains unclear.

CHFR promotes the migration of human gastric cancer cells by inducing epithelial-to-mesenchymal transition in a HDAC1-dependent manner

Background

Previous studies have illustrated that checkpoint with forkhead-associated and ring finger domains (CHFR) was frequently silenced in several cancer types due to promoter hypermethylation and functions as a tumor suppressor gene. However, the data from the public dataset reveal that CHFR is highly expressed in human gastric cancer specimens, and the biological function of CHFR in gastric cancer is still not well understood.

Materials and methods

The clinical association between CHFR expression and the overall survival of gastric cancer patients as well as cancer metastasis was analyzed according to public datasets. The CHFR expression in clinical specimens and human gastric cancer cell lines was detected by immunohistochemistry and Western blotting, respectively. Gain (overexpression) and loss (silencing) of function experiments were used to elucidate the role of CHFR in gastric cancer. The migration ability of gastric cancer cells was determined by wound healing and transwell assays. Cell cycle distribution was analyzed using fluorescence-activated cell sorting experiment. The expression of the proteins in cancer cells was measured using Western blot analysis.

Results

According to the analysis from Kaplan–Meier plotter dataset, CHFR expression was negatively associated with overall survival of gastric cancer patients. Our data revealed that exogenous expression of CHFR not only arrested cell cycle but also led to dramatically enhanced cell migration, while silencing of CHFR significantly inhibited cell migration in gastric cancer cells. This result is consistent with the data from the Human Cancer Metastasis Dataset, in which CHFR level is found to significantly increase in metastatic gastric cancer. The overexpression of CHFR promoted epithelial–mesenchymal transition (EMT) in both SGC-7901 and AGS cells, while HDAC1 was inhibited. Interestingly, suberoylanilide hydroxamic acid, a HDAC1 antagonist, could effectively increase cell migration in both cell lines via enhancement of EMT.

Conclusion

Our data indicated that CHFR exerted positive effects on cell migration of human gastric cancer by promoting EMT via downregulating HDAC1.

Cell-free plasma hypermethylated CASZ1, CDH13 and ING2 are promising biomarkers of esophageal cancer

Identifying sensitive and specific biomarkers for early detection of cancer is immensely imperative for early diagnosis and treatment and better clinical outcome of cancer patients. This study aimed to construct a specific DNA methylation pattern of cancer suppressor genes and explore the feasibility of applying cell-free DNA based methylation as a biomarker for early diagnosis of esophageal squamous cell carcinoma (ESCC). We recruited early stage ESCC patients from Yangzhong County, China. The Illumina Infinium 450K Methylation BeadChip was used to construct a genome-wide DNA methylation profile. Then, differentiated genes were selected for the validation study using the Sequenom MassARRAY platform. The frequency of methylation was compared between cancer tissues, matched cell-free DNAs and normal controls. The specific methylation profiles were constructed, and the sensitivity and specificity were calculated. Seven CG sites in three genes CASZ1, CDH13 and ING2 were significantly hypermethylated in ESCC as compared with normal controls. A significant correlation was found between the methylation of DNA extracted from cancer tissues and matched plasma cell-free DNA, either for individual CG site or for cumulative methylation analysis. The sensitivity and specificity reached 100% at an appropriate cut-point using these specific methylation biomarkers. This study revealed that aberrant DNA methylation is a promising biomarker for molecular diagnosis of esophageal cancer. Hypermethylation of CASZ1, CDH13 and ING2 detected in plasma cell-free DNA can be applied as a potential noninvasive biomarker for diagnosis of esophageal cancer.

The inhibition of UBC13 expression and blockage of the DNMT1-CHFR-Aurora A pathway contribute to paclitaxel resistance in ovarian cancer

Paclitaxel is widely used as a first-line chemotherapeutic drug for patients with ovarian cancer and other solid cancers, but drug resistance occurs frequently, resulting in ovarian cancer still presenting as the highest lethality among all gynecological tumors. Here, using DIGE quantitative proteomics, we identified UBC13 as down-regulated in paclitaxel-resistant ovarian cancer cells, and it was further revealed by immunohistochemical staining that UBC13 low-expression was associated with poorer prognosis and shorter survival of the patients. Through gene function experiments, we found that paclitaxel exposure induced UBC13 down-regulation, and the enforced change in UBC13 expression altered the sensitivity to paclitaxel. Meanwhile, the reduction of UBC13 increased DNMT1 levels by attenuating its ubiquitination, and the up-regulated DNMT1 enhanced the CHFR promoter DNA methylation levels, leading to a reduction of CHFR expression, and an increased in the levels of Aurora A. Our findings revealed a novel function for UBC13 in regulating paclitaxel sensitivity through a DNMT1-CHFR-Aurora A pathway in ovarian cancer cells. UBC13 could potentially be employed as a therapeutic molecular drug for reversing paclitaxel resistance in ovarian cancer patients.

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.

The diagnostic and prognostic value of CHFR hypermethylation in colorectal cancer, a meta-analysis and literature review

The Checkpoint with Forkhead-associated and Ring finger domains (CHFR) is a mitotic checkpoint and tumor-suppressor gene, its loss contributes tumorigenesis of epithelial cancers including colorectal carcinoma (CRC). The diagnostic and prognostic value of CHFR promoter hypermethylation in CRC remains unclear. This study aimed to conduct a meta-analysis and literature review and investigate clinicopathological significance of CHFR promoter hypermethylation in CRC. The following online database were used: PubMed, EMBASE, and Web of Science up to March 2017. Odds Ratios (OR) and Hazard Ratios (HR) with 95% corresponding confidence intervals (CIs) were calculated. A total of seven relevant articles were available for meta-analysis which included 966 patients. The frequency of CHFR promoter hypermethylation significantly increased in CRC compared to normal colorectal mucosa tissue, pooled OR was 8.35, p < 0.00001. CHFR promoter hypermethylation was not significantly correlated to stage, OR was 1.16, p = 0.63. However, CHFR promoter hypermethylation was more frequently observed in CRC with positive lymph nodes metastasis than CRC with negative lymph nodes metastasis, OR was 0.46, p = 0.03. Additionally CHFR promoter hypermethylation was significantly related to poor overall survival in patients with CRC, HR was 0.62, p = 0.008. Based on these results, tumor CHFR promoter hypermethylation is not only a diagnostic biomarker for CRC, but also a prognostic marker. CHFR promoter hypermethylation is significantly associated with worse overall survival in patients with CRC. Our data suggested that CHFR could be a potential drug target for development of demethylation treatment for patients with CRC.

Sustained expression of miR-26a promotes chromosomal instability and tumorigenesis through regulation of CHFR

MicroRNA 26a (miR-26a) reduces cell viability in several cancers, indicating that miR-26a could be used as a therapeutic option in patients. We demonstrate that miR-26a not only inhibits G1-S cell cycle transition and promotes apoptosis, as previously described, but also regulates multiple cell cycle checkpoints. We show that sustained miR-26a over-expression in both breast cancer (BC) cell lines and mouse embryonic fibroblasts (MEFs) induces oversized cells containing either a single-large nucleus or two nuclei, indicating defects in mitosis and cytokinesis. Additionally, we demonstrate that miR-26a induces aneuploidy and centrosome defects and enhances tumorigenesis. Mechanistically, it acts by targeting G1-S transition genes as well as genes involved in mitosis and cytokinesis such as CHFR, LARP1 and YWHAE. Importantly, we show that only the re-expression of CHFR in miR-26a over-expressing cells partially rescues normal mitosis and impairs the tumorigenesis exerted by miR-26a, indicating that CHFR represents an important miR-26a target in the regulation of such phenotypes. We propose that miR-26a delivery might not be a viable therapeutic strategy due to the potential deleterious oncogenic activity of this miRNA.

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.

Pathologic response during chemo-radiotherapy and variation of serum VEGF levels could predict effects of chemo-radiotherapy in patients with esophageal cancer

BACKGROUND

To investigate the relationship between pathologic tumor response to concurrent chemo- radiotherapy and variation of serum VEGF in patients with esophageal cancer.

MATERIALS AND METHODS

Forty six patients with esophageal cancer who were treated with concurrent chemo-radiotherapy were enrolled. Endoscopic and pathologic examination was conducted before and four weeks afterwards. Serum level of VEGF was documented before, four weeks later and after chemo-radiotherapy. The relationship between pathologic response and the variation of serum level of VEGF and its influence on the prognosis were investigated.

RESULTS

Serum level of VEGF decreased remarkably during and after chemo-radiotherapy in patients whose pathologic response was severe (F=5.393, 4.587, P(0.05). There were no statistical differences of serum VEGF level before, during and after chemo-radiotherapy for patients whose pathologic response was moderate or mild. There were 18 (85.7%), 7 (53.8%) and 6 patients (50.0%) whose serum VEGF level dropped in the severe, moderate and mild group, respectively, with significant differences among these groups (p=0.046). Two year survival rates of patients with severe, moderate and mild pathologic response were 61.9%, 53.8% and 33.3% respectively, and no statistically difference between severe and mild group regarding OS (p=0.245) was tested.

CONCLUSIONS

Tumor pathologic response during chemo-radiotherapy and the changes of serum VEGF lever could predict curative effects of chemo-radiotherapy in patients with esophageal 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.

Insulin-induced cell division is controlled by the adaptor Grb14 in a Chfr-dependent manner

Beyond its key role in the control of energy metabolism, insulin is also an important regulator of cell division and neoplasia. However, the molecular events involved in insulin-driven cell proliferation are not fully elucidated. Here, we show that the ubiquitin ligase Chfr, a checkpoint protein involved in G2/M transition, is a new effector involved in the control of insulin-induced cell proliferation. Chfr is identified as a partner of the molecular adapter Grb14, an inhibitor of insulin signalling. Using mammalian cell lines and the Xenopus oocyte as a model of G2/M transition, we demonstrate that Chfr potentiates the inhibitory effect of Grb14 on insulin-induced cell division. Insulin stimulates Chfr binding to the T220 residue of Grb14. Both Chfr binding site and Grb14 C-ter BPS-SH2 domain, mediating IR binding and inhibition, are required to prevent insulin-induced cell division. Targeted mutagenesis revealed that Chfr ligase activity and phosphorylation of its T39 residue, a target of Akt, are required to potentiate Grb14 inhibitory activity. In the presence of insulin, the binding of Chfr to Grb14 activates its ligase activity, leading to Aurora A and Polo-like kinase degradation and blocking cell division. Collectively, our results show that Chfr and Grb14 collaborate in a negative feedback loop controlling insulin-stimulated cell division.

Methylation of CHFR sensitizes esophageal squamous cell cancer to docetaxel and paclitaxel

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies worldwide. Both genetic and epigenetic changes are involved in esophageal carcinogenesis. CHFR methylation has been found frequently in different cancers and is regarded as a marker of taxane sensitivity. CHFR methylation was found in 0% (0/16) of normal mucosa, 2.9% (1/34) of grade I dysplasia, 0% (0/8) of grade II dysplasia, 12.5% (1/8) of grade III dysplasia and 45% (49/109) of invasive cancer. When treated with docetaxel or paclitaxel, cell viability was lower in CHFR methylated esophageal cancer cells than in unmethylated cells (p<0.05). No difference was found with either cisplatin or VP16 treatment in either group (p>0.05). In CHFR methylated cells, treatment with docetaxel or paclitaxel resulted in almost all cells being suspended in G0/G1 phase of the cell cycle. After 5-AZ treatment, there was an increased fraction of CHFR-methylated cells in S and G2/M phases (p<0.05). In conclusion, CHFR is frequently methylated in ESCC and the expression of CHFR is regulated by promoter region methylation. CHFR methylation is a late stage event in ESCC. Methylation of CHFR sensitized ESCC cells to taxanes. 5-AZ may re-sensitize chemotherapy resistant in refractory tumors by inducing cell cycle phase re-distribution.

Regulation of the DNA damage response by ubiquitin conjugation

In response to DNA damage, cells activate a highly conserved and complex kinase-based signaling network, commonly referred to as the DNA damage response (DDR), to safeguard genomic integrity. The DDR consists of a set of tightly regulated events, including detection of DNA damage, accumulation of DNA repair factors at the site of damage, and finally physical repair of the lesion. Upon overwhelming damage the DDR provokes detrimental cellular actions by involving the apoptotic machinery and inducing a coordinated demise of the damaged cells (DNA damage-induced apoptosis, DDIA). These diverse actions involve transcriptional activation of several genes that govern the DDR. Moreover, recent observations highlighted the role of ubiquitylation in orchestrating the DDR, providing a dynamic cellular regulatory circuit helping to guarantee genomic stability and cellular homeostasis (Popovic et al., 2014). One of the hallmarks of human cancer is genomic instability (Hanahan and Weinberg, 2011). Not surprisingly, deregulation of the DDR can lead to human diseases, including cancer, and can induce resistance to genotoxic anti-cancer therapy (Lord and Ashworth, 2012). Here, we summarize the role of ubiquitin-signaling in the DDR with special emphasis on its role in cancer and highlight the therapeutic value of the ubiquitin-conjugation machinery as a target in anti-cancer treatment strategy.

Esophageal squamous cell carcinoma (ESCC): advance in genomics and molecular genetics

Esophageal cancer is aggressive and has poor prognosis. Esophageal squamous cell carcinoma (ESCC) is histologically the most prevalent type of esophageal cancer and ranked as the sixth leading cause of cancer death worldwide. In recent years, cancer has been widely regarded as genetic disease, as well as epigenetic abnormalities including DNA methylation, histone deacetylation, chromatin remodeling, gene imprinting and noncoding RNA regulation. In this review, we will provide a general overview of genes, proteins and microRNAs that are involved in the development of ESCC, which aims to enhance our understanding of molecular mechanisms implicated in ESCC development and progression.

Epigenetic silencing of checkpoint with fork-head associated and ring finger gene expression in esophageal cancer

Checkpoint with fork-head associated and ring finger (CHFR) is a mitotic checkpoint gene with tumor-suppressor functions. Previous studies have described the hypermethylation of the CpG island in the promoter region as a key mechanism involved in silencing tumor suppressor genes. The epigenetic alterations regulating CHFR expression and the clinical significance of CHFR downregulation remain unclear. A total of 40 patients with esophageal squamous cell carcinoma who underwent primary resection were enrolled in this study. CHFR mRNA expression was quantified, followed by an evaluation of the methylation status using methylation-specific polymerase chain reaction (MSP) techniques in 29 patients. The correlation between CHFR expression and MSP status was then analyzed. In addition, the significance of CHFR expression was determined, with respect to clinicopathological features and overall survival. Aberrant hypermethylation of the CHFR gene was observed in 13 of 29 primary esophageal cancers. The CHFR expression levels of the methylated status samples was significantly lower than that of the unmethylated status samples (P=0.014). CHFR expression levels did not exhibit clinical significance with respect to the patient characteristics or overall survival. Hypermethylation of the CHFR gene is a common event in the development of primary esophageal cancer. CpG island hypermethylation of the promoter region in the CHFR gene is a key mechanism involved in silencing the CHFR gene in patients with esophageal cancer.

Overexpression of Cdc25C predicts response to radiotherapy and survival in esophageal squamous cell carcinoma patients treated with radiotherapy followed by surgery

Biomarker identification is crucial for the selection of patients who might benefit from radiotherapy. To explore potential markers for response and prognosis in patients with locally advanced esophageal carcinoma treated with radiotherapy followed by surgery, we evaluated the expression of cell cycle checkpoint-related proteins Chk2, Cdc25C, and Cyclin D1. A total of 56 patients with locally advanced esophageal squamous cell carcinoma were treated with radiotherapy followed by surgery. Pretreatment tumor biopsy specimens were analyzed for Chk2, Cdc25C, and Cyclin D1 expression by immunohistochemistry. High expression of Chk2, Cyclin D1, and Cdc25C was observed in 44 (78.6%), 15 (26.8%), and 27 (48.2%) patients, respectively. The median survival was 16 months (range, 3–154 months), with a 5-year overall survival rate of 19.6%. Overexpression of Chk2 was associated with smoking (P = 0.021), overexpression of Cdc25C was associated with patient age (P = 0.033) and tumor length (P = 0.001), and overexpression of Cdc25C was associated with pathologic complete response (P = 0.038). Univariate analysis demonstrated that overexpression of Cdc25C and pathologic complete response was associated with better survival. In multivariate analysis, Cdc25C was the most significant independent predictor of better survival (P = 0.014) for patients treated with radiotherapy followed by surgery. Overexpression of Cdc25C was significantly associated with pathologic complete response and better survival of patients with locally advanced esophageal cancer treated with radiotherapy followed by surgery. These results suggest that Cdc25C may be a biomarker of treatment response and good prognosis for esophageal carcinoma patients. Thus, immunohistochemical staining of Cdc25C in a pretreatment specimen may be a useful method of identifying optimal treatment for patients with esophageal carcinoma.

CHFR aberrant methylation involves a subset of human lung adenocarcinoma associated with poor clinical outcomes

Excluding epidermal growth factor receptor (EGFR) mutation, v-Ki-ras2/Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation, and echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) fusion, the genetic alterations involved in lung adenocarcinogenesis, especially those linked to poor clinical outcomes, are still unknown. In this study, we analyzed abnormal checkpoint gene with forkhead-associated domain and ring finger (CHFR) methylation along with the above 3 mutations in 165 lung adenocarcinomas, evaluated the spectrum of each molecular abnormality, and correlated the results with clinical and pathologic variables. Reverse transcription-polymerase chain reaction assay, reverse transcription-polymerase chain reaction followed by direct DNA sequencing, and methylation-specific polymerase chain reaction were performed to detect these 3 mutations and CHFR hypermethylation. The EML4-ALK transcript or CHFR hypermethylation was found in 11 (6.7%) or 16 (10%) adenocarcinomas, respectively, whereas EGFR or KRAS mutation was detected in 48 (29%) or 13 (8%) cases, respectively. EGFR mutations occurred in patients who were negative for both CHFR hypermethylation and KRAS mutation. Among the 4 genetic or epigenetic abnormalities, only CHFR hypermethylation was significantly correlated with poor prognosis and lymphatic vessel invasion (P = .024). Histopathologically, the molecular abnormality that correlated with alveolar-destructive growth was the CHFR hypermethylation rather than the EGFR mutation (P = .03). Our results demonstrate that CHFR hypermethylation maybe one of the molecular abnormalities involved in a subset of lung adenocarcinomas with poor prognoses that might be induced by destructive growth and lymphatic vessel invasion of carcinoma cells. Thus, CHFR abnormality might be pursued as a novel therapeutic target against lung adenocarcinoma without an already-known mutation.

CHFR is important for the first wave of ubiquitination at DNA damage sites

Protein ubiquitination plays an important role in activating the DNA damage response and maintaining genomic stability. In response to DNA double-strand breaks (DSBs), a ubiquitination cascade occurs at DNA lesions. Here, we show that checkpoint with Forkhead-associated (FHA) and RING finger domain protein (CHFR), an E3 ubiquitin ligase, is recruited to DSBs by poly(ADP-ribose) (PAR). At DSBs, CHFR regulates the first wave of protein ubiquitination. Moreover, CHFR ubiquitinates PAR polymerase 1 (PARP1) and regulates chromatin-associated PARP1 in vivo. Thus, these results demonstrate that CHFR is an important E3 ligase in the early stage of the DNA damage response, which mediates the crosstalk between ubiquitination and poly-ADP-ribosylation.

Promoter hypermethylation of DNA damage response genes in hepatocellular carcinoma

Aberrant methylation of promoter CpG islands is a major inactivation mechanism of tumour-related genes that play a crucial role in the progression of silencing in human cancers, including HCC (hepatocellular carcinoma). We have examined the promoter methylation status of five important DNA damage response genes in fresh-frozen HCC tissues and cell lines, as well as the possible correlation between methylation patterns and clinical features of the carcinoma. Promoter methylation status of RASSF1A (Ras association domain family 1), CHFR (checkpoint with forkhead and ring finger domains), GSTP1 (glutathione-S-transferase-pi gene), MGMT [O(6)-methylguanine-DNA methyltransferase] and hMLH1 (human mutL homologue 1) were examined by the MSP (methylation-specific PCR) in 70 HCC tissues and five HCC cell lines. The mRNA expression levels of these genes were measured by RT-PCR (reverse transcription-PCR). Methylation frequencies of these genes tested in HCC were 54 (78%) for RASSF1A, 30 (43%) for CHFR, 26 (38%) for GSTP1 and 22 (32%) for MGMT. No hypermethylation was detected for hMLH1 in any case of HCC or HCC cell lines. Moreover, promoter hypermethylation of RASSF1A, CHFR and GSTP1 in both HepG2 and SNU398 cells, and hypermethylation of MGMT in Huh7 cells, were detected. Treatment of three cell lines with 5Aza-dC (5-aza-20-deoxycytidine) restored or increased the expression of these genes, implicating aberrant DNA methylation in transcriptional silencing. Hypermethylation of RASSF1A and patient age were significantly associated. CHFR methylation status showed a statistically significant correlation with HCC progression. Methylation of the RASSF1A, CHFR, GSTP1 and MGMT genes seem therefore to play an important role in the pathogenesis of HCC. These epigenetic changes may have prognostic importance for patients with HCC.

Promoter methylation of tumor suppressor genes in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a prevalent and fatal cancer in China and other Asian countries. Epigenetic silencing of key tumor suppressor genes (TSGs) is critical to ESCC initiation and progression. Recently, many novel TSGs silenced by promoter methylation have been identified in ESCC, and these genes further serve as potential tumor markers for high-risk group stratification, early detection, and prognosis prediction. This review summarizes recent discoveries on aberrant promoter methylation of TSGs in ESCC, providing better understanding of the role of disrupted epigenetic regulation in tumorigenesis and insight into diagnostic and prognostic biomarkers for this malignancy.

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.

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.

RNF8-dependent histone ubiquitination during DNA damage response and spermatogenesis

Histone ubiquitination regulates the chromatin structure that is important for many biological processes. Recently, ubiquitination of histones was observed during the DNA damage response (DDR), and this modification is controlled by really interesting new gene (RING) domain E3 ligase, RNF8. Together with the E2 conjugating enzyme UBC13, RNF8 catalyzes ubiquitination of the histones H2A and H2AX during the DDR, thus facilitating downstream recruitment of DDR factors, such as p53 binding protein 1 (53BP1) and breast cancer type 1 susceptibility protein (BRCA1), to the damage site. Accordingly, the RNF8 knockout mice display phenotypes associated with failed DDR, including hypersensitivity to ionizing radiation, V(D)J recombination deficiency, and a predisposition to cancer. In addition to the DDR phenotypes, RNF8 knockout mice fail to generate mature sperm during spermatogenesis, resulting in male sterility. The RNF8 knockout mice also have a drastic reduction in histone ubiquitination in the testes. These findings indicate that the role of histone ubiquitination during chromatin remodeling in two different biological events could be linked by an RNF8-dependent mechanism. Here, we review the molecular mechanism of RNF8-dependent histone ubiquitination both in DDR and spermatogenesis.

DNA methylation in thoracic neoplasms

Thoracic neoplasms, which include lung cancers, esophageal carcinoma, and thymic epithelial tumors, are the leading causes of tumor-related death and a major health concern worldwide. The development of neoplasms is a multistep process involving both genetic and epigenetic alterations. A growing body of research provides evidence that aberrant DNA methylation, including DNA hypermethylation in promoter regions, global DNA hypomethylation and the overexpression of DNA methyltransferases, plays an important role in tumorigenesis. In this review, we summarize published observations of methylation pattern disruptions in thoracic tumors, and discuss how these abnormalities contribute to the development of cancers. We review recent findings showing that suppressing the activity of the DNA methylating enzymes DNMTs can have potent anti-cancer effects, and discuss the possibility of developing novel therapies for thoracic tumors based on DNMT inhibition.

Epigenetic and genetic silencing of CHFR in esophageal adenocarcinomas

BACKGROUND

The checkpoint with forkhead-associated domain and RING-finger domain (CHFR) is a mitotic checkpoint protein with tumor-suppressor functions. In this study, the authors investigated the epigenetic and genetic mechanisms that regulate CHFR expression in esophageal adenocarcinomas (EACs).

METHODS

Quantitative reverse transcriptase polymerase chain reaction analysis demonstrated downregulation of CHFR transcript in 79% of EACs (44 of 56) compared with 41 normal samples (P < .001). Immunohistochemical analysis of CHFR protein expression showed absence or weak immunostaining for CHFR in 75% of EACs (56 of 75) compared with normal tissue samples. The authors next examined the promoter DNA hypermethylation of CHFR by using quantitative bisulfite pyrosequencing technology. They detected significant CHFR promoter DNA hypermethylation in 31% of tumor samples (18 of 58) compared with normal samples (P < .001). Treatment of OE33 cells with 5-Aza-deoxycytidine led to reduction in the promoter DNA methylation levels with restoration of the CHFR mRNA expression, which confirmed promoter DNA methylation as an epigenetic mechanism regulating CHFR expression. However, they identified several EACs where the CHFR mRNA expression was silenced in the absence of notable methylation. Therefore, the authors examined the relative DNA copy number level of CHFR compared with normal samples.

RESULTS

The results confirmed a decrease or absence of the relative CHFR DNA copy number levels in 59% of tumor samples. Nine tumors that showed loss of CHFR mRNA expression, in absence of promoter DNA hypermethylation, demonstrated a significant loss of relative CHFR DNA copy numbers.

CONCLUSIONS

Taken together, their findings demonstrated that both epigenetic and genetic mechanisms were involved in silencing CHFR expression in EACs.

Pathobiologic implications of methylation and expression status of Runx3 and CHFR genes in gastric cancer

Runx3 and CHFR genes were defined as tumor suppressor genes in gastric cancer (GC) recently. This paper was to investigate the roles of methylation and expression status of Runx3 and CHFR genes in GC patients. Methylation-specific polymerase chain reaction (MSP) and bisulfite DNA sequencing (BSP) were used to detect methylation status of Runx3 and CHFR genes in GC patients. The expression of Runx3 and CHFR in GC patients was analyzed by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical analysis. The expression of the protein and mRNA decreased remarkably in the patients with aberrant promoter methylation of Runx3 and CHFR genes. The methylation status of Runx3 and CHFR were inversely related to the tumor size, tumor invasion depth and tumor differentiation in GC patients. Moreover, the protein expression of Runx3 and CHFR were significantly correlated with tumor invasion depth and tumor differentiation, respectively. Aberrant promoter methylation of Runx3 and CHFR genes may be involved in the carcinogenesis and development of GC and may provide useful clues for the prediction of the malignant behaviors of GC.

Safeguarding entry into mitosis: the antephase checkpoint

Maintenance of genomic stability is needed for cells to survive many rounds of division throughout their lifetime. Key to the proper inheritance of intact genome is the tight temporal and spatial coordination of cell cycle events. Moreover, checkpoints are present that function to monitor the proper execution of cell cycle processes. For instance, the DNA damage and spindle assembly checkpoints ensure genomic integrity by delaying cell cycle progression in the presence of DNA or spindle damage, respectively. A checkpoint that has recently been gaining attention is the antephase checkpoint that acts to prevent cells from entering mitosis in response to a range of stress agents. We review here what is known about the pathway that monitors the status of the cells at the brink of entry into mitosis when cells are exposed to insults that threaten the proper inheritance of chromosomes. We highlight issues which are unresolved in terms of our understanding of the antephase checkpoint and provide some perspectives on what lies ahead in the understanding of how the checkpoint functions.

Deficiencies in Chfr and Mlh1 synergistically enhance tumor susceptibility in mice

Genetic instability, which leads to an accumulation of various genetic abnormalities, has been considered an essential component of the human neoplasic transformation process. However, the molecular basis of genomic instability during tumorigenesis remains incompletely understood. Growing evidence indicates that checkpoint with forkhead and ring finger domains (CHFR), a recently identified mitotic checkpoint protein, plays an important role in maintaining chromosome integrity and functions as a tumor suppressor. In this study, we used high-throughput technology to conduct gene expression profiling of human colon cancers and found that loss of CHFR expression frequently occurred in colon cancers with high microsatellite instability (MSI-H). Downregulation of CHFR expression was closely associated with overexpression of Aurora A, an important mitotic kinase. Mice with deficiencies in both Chfr and Mlh1 (the gene that encodes the DNA mismatch-repair protein Mlh1) displayed dramatically higher incidence of spontaneous tumors relative to mice deficient for only one of these genes. These results suggest that defects in both Chfr and Mlh1 synergistically increase predisposition to tumorigenesis.

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.

Nuclear localization of Chfr is crucial for its checkpoint function

Chfr, a checkpoint with FHA and RING finger domains, plays an important role in cell cycle progression and tumor suppression. Chfr possesses the E3 ubiquitin ligase activity and stimulates the formation of polyubiquitin chains by Ub-conjugating enzymes, and induces the proteasome-dependent degradation of a number of cellular proteins, including Plk1 and Aurora A. While Chfr is a nuclear protein that functions within the cell nucleus, how Chfr is localized in the nucleus has not been clearly demonstrated. Here, we show that nuclear localization of Chfr is mediated by nuclear localization signal (NLS) sequences. To reveal the signal sequences responsible for nuclear localization, a short lysine-rich stretch (KKK) at amino acid residues 257-259 was replaced with alanine, which completely abolished nuclear localization. Moreover, we show that nuclear localization of Chfr is essential for its checkpoint function but not for its stability. Thus, our results suggest that NLS-mediated nuclear localization of Chfr leads to its accumulation within the nucleus, which may be important in the regulation of Chfr activation and Chfr-mediated cellular processes, including cell cycle progression and tumor suppression.

Loss of CHFR in human mammary epithelial cells causes genomic instability by disrupting the mitotic spindle assembly checkpoint

CHFR is an E3 ubiquitin ligase and an early mitotic checkpoint protein implicated in many cancers and in the maintenance of genomic stability. To analyze the role of CHFR in genomic stability, by siRNA, we decreased its expression in genomically stable MCF10A cells. Lowered CHFR expression quickly led to increased aneuploidy due to many mitotic defects. First, we confirmed that CHFR interacts with the mitotic kinase Aurora A to regulate its expression. Furthermore, we found that decreased CHFR led to disorganized multipolar mitotic spindles. This was supported by the finding that CHFR interacts with alpha-tubulin and can regulate its ubiquitination in response to nocodazole and the amount of acetylated alpha-tubulin, a component of the mitotic spindle. Finally, we found a novel CHFR interacting protein, the spindle checkpoint protein MAD2. Decreased CHFR expression resulted in the mislocalization of both MAD2 and BUBR1 during mitosis and impaired MAD2/CDC20 complex formation. Further evidence of a compromised spindle checkpoint was the presence of misaligned metaphase chromosomes, lagging anaphase chromosomes, and defective cytokinesis in CHFR knockdown cells. Importantly, our results suggest a novel role for CHFR regulating chromosome segregation where decreased expression, as seen in cancer cells, contributes to genomic instability by impairing the spindle assembly checkpoint.

CHFR expression is preferentially impaired in smoking-related squamous cell carcinoma of the lung, and the diminished expression significantly harms outcomes

Loss of tumor suppressors and activation of oncogenes lead to carcinogenesis. Abnormal expression of CHFR, a novel checkpoint gene, or of Aurora kinases, key regulators of mitosis, has been detected in a variety of solid tumors. Recently, CHFR has been revealed to ensure chromosomal stability by controlling the expression level of Aurora-A in vitro. However, the frequency of aberrant expression of these proteins and the association with clinicopathologic parameters remain poorly defined in nonsmall-cell lung cancer (NSCLC). In this study, we investigated the immunohistochemical protein expression of CHFR and Aurora-A in 157 NSCLC cases and evaluated the association between clinicopathologic parameters statistically. The relationship between CHFR protein and mRNA levels and the association between this relationship and promoter methylation of the CHFR gene were also examined in 20 frozen sections of NSCLC. Overexpression of Aurora-A and reduced expression of CHFR were found in 94 cases (59.8%) and 62 cases (39%) of NSCLC, respectively, and those were significantly correlated with tumor differentiation and size. Moreover, diminished CHFR expression was significantly associated with smoking-related squamous cell carcinoma cases and poor prognosis. Multivariate analysis revealed that CHFR expression was an independent prognostic factor. A statistical correlation was evident between CHFR protein and mRNA expression. In conclusion, our results suggest the aberrant expression of Aurora-A and/or of CHFR contributed to the increase in the malignant potential of NSCLC. We also revealed that CHFR expression was predominantly impaired in smoking-related squamous cell carcinoma and might be a useful prognostic marker in NSCLC.

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.

CHFR gene is neither mutated nor hypermethylated in ovarian cancer

BACKGROUND

CHFR is a mitotic checkpoint protein that under mitotic stress (caused also by taxanes) delays progression into mitosis.

METHODS

We looked for CHFR gene (605,209) alterations and its promoter hypermethylation in 48 ovarian carcinomas either sensitive or resistant to taxane treatment. We used single-strand conformation polymorphism analysis, sequencing and methylation-specific polymerase chain reaction.

RESULTS

Neither mutations in the CHFR gene nor hypermethylation of its promoter region were found. A novel single nucleotide polymorphism (Val154Val) was identified in exon 5 of alternatively spliced transcript.

CONCLUSIONS

Our results indicate that CHFR gene status cannot serve as a molecular predictor of ovarian cancer sensitivity to taxanes.

Altered expression of the early mitotic checkpoint protein, CHFR, in breast cancers: implications for tumor suppression

Checkpoint with FHA and Ring Finger (CHFR) is hypothesized to mediate a delay in cell cycle progression early in mitosis in response to microtubule stress, independent of the spindle assembly checkpoint. As a potential regulator of cell cycle progression, CHFR naturally becomes an interesting target for understanding cancer cells. In recent years, there has been increasing evidence supporting the role of CHFR as a tumor suppressor, most of which report loss of expression, occasionally due to promoter hypermethylation, in cancers compared with patient-matched normal tissues. We studied both a panel of breast cancer cell lines as well as primary tissue samples from breast cancer patients to investigate CHFR as a relevant tumor suppressor in breast cancer and to determine whether CHFR expression was associated with clinical and pathologic variables. We report that 41% of cell lines and 36% of patient samples showed low or negative CHFR protein expression or staining. In addition, lack of CHFR detection was associated with increased tumor size and weakly correlated with estrogen receptor-negative tumors from patients. To study the effects of low CHFR expression in vitro, we stably expressed a short hairpin RNA construct targeting CHFR in two lines of immortalized human mammary epithelial cells. Notably, decreased CHFR expression resulted in the acquisition of many phenotypes associated with malignant progression, including accelerated growth rates, higher mitotic index, enhanced invasiveness, increased motility, greater aneuploidy, and amplified colony formation in soft agar, further supporting the role of CHFR as a tumor suppressor in breast cancer.

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.

Methylation in esophageal carcinogenesis

Genetic abnormalities of proto-oncogenes and tumor suppressor genes have been demonstrated to be changes that are frequently involved in esophageal cancer pathogenesis. However, hypermethylation of CpG islands, an epigenetic event, is coming more and more into focus in carcinogenesis of the esophagus. Recent studies have proved that promoter hypermethylation of tumor suppressor genes is frequently observed in esophageal carcinomas and seems to play an important role in the pathogenesis of this tumor type. In this review, we will discuss current research on genes that are hypermethylated in human esophageal cancer and precancerous lesions of the esophagus. We will also discuss the potential use of hypermethylated genes as targets for detection, prognosis and treatment of esophageal cancer.