RASSF10 is an epigenetically silenced tumor suppressor in gastric cancer

The Tumor Suppressor Role of the Ras Association Domain Family 10

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

Emerging strategies for sensitization of therapy resistant tumors toward cancer therapeutics by targeting the Bcl-2 family, TGF-β, Wnt/β-Catenin, RASSF and miRNA regulated signaling pathways

Conventional chemotherapy relies on the cytotoxicity of chemo-drugs to inflict destructive effects on tumor cells. However, as most tumor cells develop resistance to chemo-drugs, small doses of chemo-drugs are unlikely to provide significant clinical benefits in cancer treatment while high doses of chemo-drugs have been shown to impact normal human cells negatively due to the non-specific nature and cytotoxicity associated with chemo-drugs. To overcome this challenge, sensitizations of tumor cells with bioactive molecules that specifically target the pro-survival and pro-apoptosis signaling pathways of the tumor cells are likely to increase the therapeutic impacts and improve the clinical outcomes by reducing the dependency and adverse effects associated with using high doses of chemo-drugs in cancer treatment. This review focuses on emerging strategies to enhance the sensitization of tumor cells toward cancer therapies based on our understanding of tumor cell biology and underlying signaling pathways.

Apatinib Inhibits the Invasion and Metastasis of Liver Cancer Cells by Downregulating MMP-Related Proteins via Regulation of the NF-κB Signaling Pathway

Objective

We aimed to investigate whether apatinib has an inhibitory effect on the invasion and metastasis of liver cancer in vitro.

Methods

The anti-invasion and antimetastasis effects of apatinib in HepG2, Hep3B,Huh7 and SMMC-7721 liver cancer cell lines were tested by the wound-healing and transwell invasion assays. Real-time PCR and Western blot were used to detect the influence of apatinib on the gene expression of MMPs, TIMPs, and constituents of the NF-κB signaling pathway in Hep3B and HepG2 liver cell lines.

Results

Apatinib has a significant inhibitory effect on the metastasis and invasion of liver cancer cells. The expression levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, MMP-10, MMP-11, and MMP-16 were downregulated, while the expression levels of TIMP-3 and TIMP-4 were upregulated by apatinib treatment at both the mRNA and protein levels. The phosphorylation of IκBα and NF-κB p65 was significantly reduced compared with that in the control group.

Conclusions

Apatinib inhibits the invasion and metastasis of human liver cancer cells by downregulating the expression of MMP-related genes. This may be achieved by inhibiting the activation of the NF-κB signaling pathway.

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

Background

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

Methods

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

Results

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

Conclusions

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

Decreased expression of RASSF10 correlates with poor prognosis in patients with colorectal cancer

Ras association domain protein 10 (RASSF10) was reported to act as a prognostic indicator in various types of cancer and it was proved to be tumor suppressor gene in colorectal cancer (CRC). The purpose of this study was to evaluate the prognostic significance of RASSF10 in CRC.Quantitative real-time polymerase chain reaction was used to detect the messenger RNA (mRNA) expression while enzyme-linked immunosorbent assay was taken to measure the protein expression of RASSF10 in tumor tissues and adjacent normal tissues from 102 patients with CRC. The relationship between RASSF10 expression level and clinical characteristics of CRC patients was analyzed by chi-squared test. In addition, the association between overall survival of CRC patients and RASSF10 expression was estimated by Kaplan-Meier analysis. Cox regression analysis was used to evaluate the prognostic value of RASSF10.The expression level of RASSF10 in tumor tissues was significantly lower than that in the normal tissues both at mRNA and protein levels. Moreover, the expression level was correlated with lymph-node-metastasis and tumor-node-metastasis stage. Kaplan-Meier analysis suggested that patients with high expression level of RASSF10 had a longer overall survival than those with low level (log-rank test, P < .001). Besides, RASSF10 might be a potential biomarker in the prognosis of CRC according to cox regression analysis.The down regulated of RASSF10 is found in CRC and it may be an ideal prognostic marker.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The coiled-coil domain of oncogene RASSF 7 inhibits hippo signaling and promotes non-small cell lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide, and despite recent improvements in treatment patient prognosis remains dismal. In this study, we examined the role of N-terminal Ras-association domain family 7 (RASSF7) in human non-small cell lung cancer (NSCLC). We found that RASSF7 was overexpressed NSCLC tissues, which correlated with advanced TNM stage, positive lymph node metastasis, and poor prognosis. This RASSF7 overexpression promoted lung cancer cell proliferation, migration, and invasion. We also found that RASSF7 interacted with mammalian Ste20-like kinase 1(MST1) through its C-terminal coiled-coil domain to inhibit MST1 phosphorylation as well as the phosphorylation of large tumor suppressor kinase 1(LATS1) and yes-associated protein (YAP), while promoting the nuclear translocation of YAP. In addition, RASSF7 overexpression inhibited the Hippo signaling pathway both in vitro and vivo and promoted the expression of proteins associated with proliferation and invasion, such as connective tissue growth factor. These results suggest that targeting RASSF7 could be exploited for therapeutic benefit in the treatment of NSCLC.

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

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

RASSF10 is an epigenetically inactivated tumor suppressor and independent prognostic factor in hepatocellular carcinoma

Methylation of the Ras-association domain family 10 (RASSF10) promoter region correlates with clinicopathological characteristics and poor prognosis in several human cancers. Here, we examined RASSF10 expression in hepatocellular carcinoma (HCC) and its role in hepatocarcinogenesis. RASSF10 mRNA and protein levels were downregulated in both HCC cell lines and patient tissue samples. In patient tissues, low RASSF10 levels correlated with hepatocirrhosis, poor tumor differentiation, tumor thrombus and Barcelona Clinic Liver Cancer stage, and were indicative of increased tumor recurrence and reduced patient survival. Low RASSF10 expression was associated with promoter hypermethylation, which was in turn associated with polycyclic aromatic hydrocarbon and aflatoxin B1 exposure, but not DNA methyltransferase expression. Overexpression of RASSF10 in HCC cell lines suppressed cell growth and colony formation, and induced apoptosis by up- or down-regulating specific Bcl-2 family proteins. RASSF10 overexpression increased pro-apoptotic Bax and Bad levels, but decreased anti-apoptotic Bcl-2 and Bcl-xl expression. Overexpression also inhibited tumor formation in nude mice and reduced cell migration and invasion by inhibiting the epithelial-mesenchymal transition. RASSF10 knockdown promoted cell growth. Our results show that RASSF10 is frequently hypermethylated and down-regulated in HCC and can potentially serve as a useful biomarker predictive of HCC patient prognosis.

Ras-association domain family 10 acts as a novel tumor suppressor through modulating MMP2 in hepatocarcinoma

Ras-Association Domain Family 10 (RASSF10) is the last identified member of the RASSF family. The functional characteristics of this new gene in human cancers remain largely unclear. Here, we examined RASSF10 for the biological functions and related molecular mechanisms in hepatocellular carcinoma (HCC). We found that RASSF10 is expressed in normal human liver tissue, but is silenced or down-regulated in 62.5% (5/8) of HCC cell lines. The mean expression level of RASSF10 was significantly lower in primary HCCs compared with their adjacent normal tissues (P<0.005, n=52). The promoter methylation contributes to the inactivation of RASSF10 as demonstrated by bisulfite genomic sequencing and demethylation treatment analyses. Transgenic expression of RASSF10 in silenced HCC cell lines suppressed cell viability, colony formation and inhibited tumor growth in nude mice (QGY7703, P<0.01; HepG2, P<0.05). Furthermore, RASSF10 was shown to induce the cell accumulation in G1 phase with the increase of p27, as well as the decrease of cyclinD1 and CDK2/CDK4. Over-expression of RASSF10 also inhibited HCC cells migration (P<0.01) or invasion (P<0.05). Adhesion genes array revealed that Matrix Metalloproteinase 2 (MMP2) was a downstream effector of RASSF10. RASSF10 acting as a tumor suppressor to inhibit HCC invasion partially mediated by Focal Adhesion Kinase or p38 MAPK to decrease the accumulation of MMP2. Our study suggests that RASSF10 acts as a tumor suppressor for HCC.

Ras association domain family member 10 suppresses gastric cancer growth by cooperating with GSTP1 to regulate JNK/c-Jun/AP-1 pathway

The Ras association domain family (RASSF) encodes several members with tumor-suppressive potentials. We aimed to investigate the biological function and clinical implication of RASSF10 in gastric cancer (GC). We found that RASSF10 was silenced in six of seven GC cell lines and in primary GC tissues, but was highly expressed in normal gastric tissues. The silence of RASSAF10 was mediated by promoter methylation as evaluated by bisulfite genomic sequencing. RASSF10 expression could be restored by demethylation treatment. A negative correlation between methylation and mRNA expression of RASSF10 was observed in 223 gastric samples of The Cancer Genome Atlas study (P<0.0001). Re-expression of RASSF10 in GC cell lines (AGS and MKN45) significantly suppressed cell viability, colony formation, migration and invasion, reduced cells in S phase, accumulated cells in G2 phase and induced cell apoptosis in vitro, and inhibited tumorigenicity in nude mice. These were confirmed by decreased expression of proliferation markers (proliferating cell nuclear antigen, p-CDC2 and p-CDC25) and increased apoptotic cascades (cleaved caspases-9, -8, -3 and cleaved poly (ADP-ribose) polymerase). Conversely, RASSF10 knockdown in normal gastric cell line yielded an opposing effect. Co-immunoprecipitation combined with mass spectrometry analyses were performed to reveal the downstream effectors of RASSF10. The result revealed that glutathione S-transferase Pi 1 (GSTP1) was a direct cooperator of RASSF10. The tumor-suppressive effect of RASSF10 was partially mediated by cooperating with GSTP1 to deregulate Jun N-terminal kinase (JNK)/c-Jun/AP-1 pathway. Importantly, RASSF10 methylation was detected in 56.6% (98/173) of primary GCs and is an independent risk factor for poor survival of GC patients (P=0.001). In conclusions, RASSF10 functions as a tumor suppressor by cooperating with GSTP1 to deregulate JNK/c-Jun/AP-1 pathway in GC. Promoter methylation of RASSF10 is associated with poor survival of GC patients.

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

The tumor-suppressing role of Ras-association domain family 10 (RASSF10) has been described in several types of cancers. Here, we evaluated the potential use of the hypermethylation status of the RASSF10 promoter in serum as a new diagnostic and prognostic tool in gastric cancer (GC). We used bisulfite sequencing polymerase chain reaction to examine RASSF10 methylation levels in serum and/or tumor samples from 82 GC, 45 chronic atrophic gastritis (CAG), and 50 healthy control patients. In the serum of GC patients, the median level of RASSF10 methylation was higher at 47.84 % than those in the serum of CAG and healthy control patients at 11.89 and 11.35 %, respectively. The median level of RASSF10 methylation in GC tumor tissue was similarly high at 62.70 %. Furthermore, RASSF10 methylation levels were highly correlated between paired serum and tumor samples from GC patients. We performed receiver-operating characteristic curve analyses to verify that serum RASSF10 methylation levels could effectively distinguish GC from control patients. Moreover, multivariate analyses showed that high serum RASSF10 methylation levels in GC patients were associated with large tumors, lymph node metastasis, and high carcinoembryonic antigen (CEA) levels. Survival analyses showed that GC patients with high serum RASSF10 methylation levels had shorter overall and disease-free survival after D2 lymphadenectomy than those with low levels. High serum RASSF10 methylation levels were also an independent predictor of tumor recurrence and GC patient survival. In conclusion, serum RASSF10 promoter methylation levels can serve as a valuable indicator for the diagnosis and prognosis of GC in the clinic.

Aberrant Promoter Methylation of the Tumour Suppressor RASSF10 and Its Growth Inhibitory Function in Breast Cancer

Breast cancer is the most common cancer in women, with 1.7 million new cases each year. As early diagnosis and prognosis are crucial factors in cancer treatment, we investigated potential DNA methylation biomarkers of the tumour suppressor family Ras-association domain family (RASSF). Promoter hypermethylation of tumour suppressors leads to their inactivation and thereby promotes cancer development and progression. In this study we analysed the tumour suppressors RASSF1A and RASSF10. Our study shows that RASSF10 is expressed in normal breast but inactivated by methylation in breast cancer. We observed a significant inactivating promoter methylation of RASSF10 in primary breast tumours. RASSF10 is inactivated in 63% of primary breast cancer samples but only 4% of normal control breast tissue is methylated (p < 0.005). RASSF1A also shows high promoter methylation levels in breast cancer of 56% vs. 8% of normal tissue (p < 0.005). Interestingly more than 80% of breast cancer samples harboured a hypermethylation of RASSF10 and/or RASSF1A promoter. Matching samples exhibited a strong tumour specific promoter methylation of RASSF10 in comparison to the normal control breast tissue. Demethylation treatment of breast cancer cell lines MCF7 and T47D reversed RASSF10 promoter hypermethylation and re-established RASSF10 expression. In addition, we could show the growth inhibitory potential of RASSF10 in breast cancer cell lines MCF7 and T47D upon exogenous expression of RASSF10 by colony formation. We could further show, that RASSF10 induced apoptotic changes in MCF7 and T47D cells, which was verified by a significant increase in the apoptotic sub G1 fraction by 50% using flow cytometry for MCF7 cells. In summary, our study shows the breast tumour specific inactivation of RASSF10 and RASSF1A due to DNA methylation of their CpG island promoters. Furthermore RASSF10 was characterised by the ability to block growth of breast cancer cell lines by apoptosis induction.

Pancreatic cancer patient survival correlates with DNA methylation of pancreas development genes

DNA methylation is an epigenetic mark associated with regulation of transcription and genome structure. These markers have been investigated in a variety of cancer settings for their utility in differentiating normal tissue from tumor tissue. Here, we examine the direct correlation between DNA methylation and patient survival. We find that changes in the DNA methylation of key pancreatic developmental genes are strongly associated with patient survival.

Lactotransferrin expression is downregulated and affects the mitogen-activated protein kinase pathway in gastric cancer

Gastric cancer (GC) is the second leading cause of cancer-associated mortality worldwide. In advanced and metastatic GC, conventional chemotherapy results in limited efficacy and the average survival rate is currently approximately 10 months. Dysregulated activation of numerous genes, including zinc finger, DHHC-type containing 14; caspase-associated recruitment domain-containing protein; and Ras association domain family member 10, have been implicated in GC. The tumor suppressor function of lactotransferrin (LTF) has been reported in a variety of tumors, including GC, nasopharyngeal carcinoma (NPC) and prostate cancer. However, the mechanism of the tumor suppressor function of LTF in GC remains unclear. In the present study, the expression levels of LTF in patient GC tissue samples were investigated using reverse transcription-quantitative polymerase chain reaction, and it was demonstrated that the LTF mRNA expression level in GC tissue samples was reduced by ~20-fold compared with the adjacent non-cancerous tissues (t=4.56, P<0.01). A similar trend in LTF protein expression was observed by western blot analysis. Furthermore, the present study demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway intermediates p38, c-Jun N-terminal kinase (JNK) and c-Jun were highly expressed in GC tissue samples, and indicated that LTF downregulation may be associated with the dysregulation of the MAPK signaling pathway in GC tissues. In addition, the present study indicated that LTF overexpression reduced the expression of p38, JNK2 and c-Jun in the GC cell line, SGC7901. The present study demonstrates that LTF expression is downregulated in GC tissues and that LTF may serve an important role in the dysregulation of the MAPK signaling pathway.

Re-expression of Lactotransferrin, a candidate tumor suppressor inactivated by promoter hypermethylation, impairs the malignance of oral squamous cell carcinoma cells

BACKGROUND

Lactotransferrin (LTF) has been confirmed to act as a tumor suppressor in multiple cancers; however, its roles in oral squamous cell carcinoma (OSCC), one of malignant head and neck carcinomas, has not been explored.

METHODS

Here, the expression of LTF in OSCC tissues and TCA8113 cells was detected with RT-PCR, qPCR, and IHC. And the correlation between LTF expression and OSCC metastasis was assessed. MS-PCR was performed to reveal the methylation status in promoter regions of LTF both in OSCC tissue samples and cells. The influences of 5-Aza-Cdc treatment to the methylation status and expression levels of LTF were also analyzed. At last, the functions of LTF in OSCC progression were demonstrated by MTT analysis, clone formation assay, and cell cycle analysis in TCA8113 cells with forced ectopic expression of LTF.

RESULTS

LTF showed a low or null expression pattern in OSCC tissues and cells, at least partially, due to the hypermethylated status in promoter regions for 5-Aza-Cdc, a methyltransferase inhibitor, could restore the expression of LTF in TCA8113 cells. And the expression level of LTF exhibited a negative correlation with OSCC metastasis.

CONCLUSIONS

Re-expression of LTF inhibited the growth, proliferation, as well as cell cycle progression of TCA8113 cells. In conclusion, hypermethylation contributes much to LTF inactivation in OSCC. And LTF can partially reverse the malignant phenotypes of OSCC cells and may be served as a potential target for diagnosis and therapy of OSCC in future.