Single nucleotide polymorphism at codon 133 of the RASSF1 gene is preferentially associated with human lung adenocarcinoma risk

Association of RASSF1A Ala133Ser polymorphism with cancer risk: a updated meta-analysis involving 7362 subjects

It has been demonstrated in many studies that the polymorphism of Ras association domain family 1 isoform A (RASSF1A) is related to tumor risk; however, this conclusion remains a controversy. In this study, we systemically retrieved relevant studies in electronic databases such as PUBMED, and EMBASE, and calculated odds ratios (ORs) as well as relevant 95% confidence intervals (CIs). Besides, meta-package in STATA version 12.0 was used. This meta-analysis finally included altogether 12 studies with 16 case-control articles. According to our data, the polymorphism of RASSF1A Ala133Ser was associated with tumor risk (Ser vs. Ala: OR = 1.68,95% CI = 1.20-2.36; Ala/Ser vs. Ala/Ala:OR = 1.63,95% CI = 1.16-2.27; Ser/Ser vs. Ala/Ala:OR = 3.06,95% CI = 1.91-4.89; Recessive model:OR = 2.67, 95% CI = 1.66-4.32; Dominant model: OR =1.72, 95% CI =1.20-2.45). Further, subgroup analyses stratified based on race and cancer type indicated this polymorphism is related to lung cancer(LC) and hepatocellular carcinoma(HCC) susceptibility in Asians.In conclusion, we found that RASSF1A Ala133Ser polymorphism increased LC and HCC risk in Asians, which requires large-scale, delicately-designed researches for verification.

Investigation of the relationship between CTLA4 and the tumor suppressor RASSF1A and the possible mediating role of STAT4 in a cohort of Egyptian patients infected with hepatitis C virus with and without hepatocellular carcinoma

The Ras association domain family 1 isoform A (RASSF1A), cytotoxic T lymphocyte antigen 4 (CTLA-4), and signal transducer and activator of transcription 4 (STAT4) genes play a role in regulating the cell cycle, apoptosis, and the autoimmune response against cancer. We investigated the genotype frequency and the possible association of the rs2073498 (RASSF1A), rs5742909 (CTLA-4) and rs7574865 (STAT4) genetic variants with hepatitis C virus (HCV)-G4-mediated hepatocellular carcinoma (HCC) progression in Egyptian patients. Fifty patients with HCV infection, 50 patients with HCV-mediated HCC, and 50 age- and sex-matched healthy controls were recruited. The investigated variants were genotyped based on polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The Ser133 mutant G4 variant of the rs2073498 SNP in RASSF1A exhibited a positive correlation with HCC incidence risk (OR = 0.571, 95% CI = 0.175-1.865, P < 0.001). The rs7574865 variant in STAT4 (G/T) occurred frequently in both HCV groups, with a significant incidence risk (OR = 1.583, 95% CI = 1.123-2.232, P = 0.005). The rs5742909 change in CTLA4 (C/T) did not show a significant difference between HCV-mediated HCC cases and the control group (OR = 4.5, 95% CI = 1.326-15.277, P > 0.001). Activation of the immune checkpoint gene CTLA4 or polymorphism in the encoded CTLA4 protein causes phosphorylation of kinases needed for RAS gene activation. This in turn downregulates the tumor suppressor RASSF1, inhibiting apoptosis and leading to HCC development, indicating a negative impact of CTLA4 gene polymorphism on HCV-mediated HCC cases. A major determinant of disease progression could be immune system genetic variants, together with the presence of costimulatory factors. The rs2073498 and rs7574865 variations in the RASSF1A and STAT4 genes, respectively, could be genetic susceptibility factors for Egyptian patients with HCV-mediated HCC.

RASSF1-AS1, an antisense lncRNA of RASSF1A, inhibits the translation of RASSF1A to exacerbate cardiac fibrosis in mice

Cardiac fibrosis is associated with various cardiovascular diseases and can eventually lead to heart failure. Dysregulation of long non-coding RNAs (lncRNAs) are recognized as one of the key mechanisms of cardiac diseases. However, the roles and underlying mechanisms of lncRNAs in cardiac fibrosis have not been explicitly defined. Here, we investigated the role of an antisense (AS) lncRNA from the Ras association domain-containing protein 1 isoform A (RASSF1A) gene locus, named RASSF1-AS1, in the development of cardiac fibrosis. Cardiac fibrosis mouse model was established by isoproterenol injection. We found that RASSF1A protein was downregulated, whereas RASSF1-AS1 was markedly upregulated during cardiac fibrosis. Overexpression and knockdown of mouse primary cardiac fibroblasts showed that RASSF1-AS1 negatively regulated RASSF1A expression at the post-transcriptional level. According to the landscape analysis and sense-AS binding evaluation, RASSF1-AS1 partially overlaps with RASSF1A messenger RNA (mRNA) at the exon2 region. RNA pull-down and luciferase activity assays confirmed that RASSF1-AS1 directly bound to RASSF1A mRNA and suppressed its translation. Furthermore, wild-type RASSF1-AS1 had a promoting effect on nuclear factor-κB activation and cardiac fibrosis, but mutated RASSF1-AS1, in which the binding region was deleted, had no effect. In conclusion, RASSF1-AS1 inhibits the translation of RASSF1A to exacerbate cardiac fibrosis in mice, indicating a potential application of RASSF1-AS1 as a therapy target for cardiac fibrosis.

Polymorphisms of the Ras-Association Domain Family 1 Isoform A (RASSF1A) Gene are Associated with Ovarian Cancer, and with the Prognostic Factors of Grade and Stage, in Women in Southern China

BACKGROUND The aim of this study was to determine whether polymorphisms of the Ras-association domain family 1 isoform A (RASSF1A) gene were associated with ovarian cancer and with tumor grade and stage, which affect the prognosis of ovarian cancer, in women in Southern China. MATERIAL AND METHODS Women from Southern China with histologically confirmed, graded and staged ovarian cancer (n=1,375), and cancer-free controls (n=1,227), provided samples of peripheral blood. DNA was extracted from the blood samples, and five tagging single nucleotide polymorphisms (SNPs) (rs4688728G>T, rs72932987C>T, rs1989839C>T, rs2073497A>C, and rs2236947A>C) were evaluated using an online assay-by-design platform. Polymerase chain reaction (PCR) DNA amplification was performed and computational haplotyping analysis of genetic associations between the five tagging SNPs was performed to identify frequent haplotypes in women with ovarian cancer, and the associations with tumor grade and stage. RESULTS In women in Southern China, the CT genotype of rs1989839 was associated with the patients with ovarian cancer (P=0.001), and was significantly correlated with tumor grade and stage (P=0.008). One of the remaining four SNPs studied, rs2073497A>C showed an association with the prognostic factors of grade and stage, but this association did not reach statistical significance. CONCLUSIONS Polymorphisms of the RASSF1A gene, most significantly the CT genotype of rs1989839, might play a role in the development and prognosis of ovarian cancer in women in Southern China. To our knowledge, this is the first study to demonstrate an association between polymorphisms in the RASSF1A gene in ovarian cancer.

Ras-Association Domain Family 1 Isoform A (RASSF1A) Gene Polymorphism rs1989839 is Associated with Risk and Metastatic Potential of Osteosarcoma in Young Chinese Individuals: A Multi-Center, Case-Control Study

Background

The ras-association domain family 1 isoform A (RASSF1A) gene serves as a bona fide tumor suppressor gene. The polymorphisms in RASSF1A were previously reported to be associated with the risk of solid malignant tumors. We hypothesized herein that RASSF1A gene polymorphisms are involved in the risk and prognosis of osteosarcoma (OS).

Material/Methods

We recruited 279 young OS cases and 286 tumor-free controls from the east Chinese population. Five tagSNPs of RASSF1A gene (rs2236947A/C, rs2073497A/C, rs1989839C/T, rs72932987C/T, and rs4688728G/T) were genotyped. DNA was isolated from blood samples and then underwent PCR analysis for genotyping.

Results

rs1989839C/T is an important predictor of osteosarcoma risk and outcome. The CT genotype of rs1989839 is highly related to elevated risk of osteosarcoma. Furthermore, rs1989839C/T is also associated with the Enneking stage of osteosarcoma and risk of lung metastasis. One of the other 4 SNPs, rs2236947A/C, shows a borderline significance in predicting osteosarcoma risk.

Conclusions

Our study is the first to prove that RASSF1A gene polymorphisms may potentially be predictive for osteosarcoma risk and prognosis.

Hippo pathway and protection of genome stability in response to DNA damage

The integrity of DNA is constantly challenged by exposure to the damaging effects of chemical and physical agents. Elucidating the cellular mechanisms that maintain genomic integrity via DNA repair and cell growth control is vital because errors in these processes lead to genomic damage and the development of cancer. By gaining a deep molecular understanding of the signaling pathways regulating genome integrity it is hoped to uncover new therapeutics and treatment designs to combat cancer. Components of the Hippo pathway, a tumor-suppressor cascade, have recently been defined to limit cancer transformation in response to DNA damage. In this review, we briefly introduce the Hippo signaling cascade in mammals and discuss in detail how the Hippo pathway has been established as part of the DNA damage response, activated by apical signaling kinases that recognize breaks in DNA. We also highlight the significance of the Hippo pathway activator RASSF1A tumor suppressor, a direct target of ataxia telangiectasia mutated and ataxia telangiectasia and Rad3 related ATR. Furthermore we discuss how Hippo pathway in response DNA lesions can induce cell death via Yes-associated protein (YAP) (the canonical Hippo pathway effector) or promote maintenance of genome integrity in a YAP-independent manner.

RASSF1A, RECK genotypes and haplotypes in Egyptian population with Hepatocellular carcinoma

BACKGROUND AND OBJECTIVES

The development of HCC is multifactorial, resulting from the interaction of environmental factors (possibly hepatitis viruses) and host factors (genetic factors). So identification of risk factors that contribute to HCC and thus early diagnosis and therapy is necessary. This study aimed to investigate the role of tumor suppressor genes RASSF1A Ala133Ser and RECK rs11788747polymorphisms and their haplotypes in HCC.

SUBJECTS AND METHODS

104 cases of HCC and 100 healthy controls were included in a case-control study. RASSF1A and RECK genotypes, allele and haplotypes were detected by PCR-RFLP.

RESULTS

Risk of HCC was significantly associated with carriers of A1a/Ser, Ser/Ser, Ser allele and A1a/Ser +GA haplotypes (OR=20.57, p<0.001, OR=7.26, p=0.05, OR=10.64, p<0.001, OR=12.52, p=0.005) respectively. More over RECK GG, G allele and haplotype A1a/A1a+GG were protective to HCC (OR=0.11, p<0.001, & OR=0.53, p=0.001 & OR=0.16, p=0.002) respectively. Also, it was found that RASSF1A gene polymorphism significantly associated with bad pathological features but no association with RECK gene polymorphism.

CONCLUSIONS

The RASSF1AAla133Ser polymorphism, RECK gene polymorphism and for the first time haplotype of both genes influence molecular carcinogenesis and clinic pathological features of HCC within the Egyptian population.

The Association of Ala133Ser Polymorphism and Methylation in Ras Association Domain Family 1A Gene With Unfavorable Prognosis of Hepatocellular Carcinoma

BACKGROUND

The functional and prognostic significance of Ras association domain family 1A gene (RASSF1A) on hepatocellular carcinoma (HCC) has not been well characterized.

OBJECTIVES

This study aimed to investigate the association between Ala133Ser polymorphism or promoter methylation in RASSF1A and the prognosis of HCC in Nantong City, one of the areas with the highest incidence of cancer in China.

PATIENTS AND METHODS

Using peripheral blood plasma, the incidence rate of RASSF1A Ala133Ser in 235 controls and subjects with 260 HCC was analyzed by the polymerase chain reaction and sequencing. We further investigated the RASSF1A methylation status in HCC and corresponding peri-tumorous normal tissues using the methylation-specific polymerase chain reaction approach.

RESULTS

It was found that the frequency of the RASSF1A Ala133Ser T allele (Ala/Ser and Ser/Ser) genotype in HCC cases was observably higher than that of normal subjects (P < 0.001). In comparison to the Ala/Ala genotype, the T allele genotype improved the susceptibility to HCC. The study also found that RASSF1A methylation improves the risk of HCC. Furthermore, in contrast with the corresponding peri-tumorous normal tissues, we observed that the RASSF1A methylation status was markedly higher in HCC tissues (P < 0.001). The Kaplan-Meier and multivariate analyses suggested that the poor survival of HCC patients was closely connected with hepatocirrhosis, Barcelona Clinic Liver Cancer stage, Edmondson division, RASSF1A methylation and Ala133Ser polymorphism (P < 0.001).

CONCLUSIONS

The polymorphism and promoter methylation of RASSF1A may be a significant factor in HCC, and can be an indicator for poor prognosis in patients with HCC.

Clinical utility of RASSF1A methylation in human malignancies

The high frequency of RASSF1A methylation has been noted in a vast number of patients in a broad spectrum of malignancies, suggesting that RASSF1A inactivation is associated with cancer pathogenesis. However, whether this recurrent incidence of RASSF1A hypermethylation in human malignancies and its association with more aggressive tumour phenotype is a frequent event across different cancer types has not yet been discussed. In this review, we interrogated existing evidence for association of RASSF1A hypermethylation with clinicopathological characteristics that can indicate more invasive lesions.

Safeguarding genome stability: RASSF1A tumor suppressor regulates BRCA2 at stalled forks

While it has been widely established that defective fork restart after exposure to stress results in increased genomic instability, the importance of fork protection during stalling for safeguarding genomic integrity has recently been fully appreciated. BRCA2, Breast tumor suppressor, has dual functionality promoting not only DNA repair but also preventing DNA lesions at stalled forks. In response to replication stress, BRCA2 recruits RAD51 onto nascent DNA at stalled forks, protecting nascent DNA from nucleolitic cleavage. Phosphorylation of the BRCA2 C-terminal RAD51 binding site by CDK2 promotes RAD51 filament disassembly, leading to nucleolitic cleavage of newly synthesized DNA and compromised fork integrity. Recently we uncovered how the core Hippo pathway components RASSF1A, MST2 and LATS1 regulate CDK2 activity towards BRCA2, in response to fork stalling. In complex with LATS1, CDK2 exhibits reduced kinase activity which results in low levels of pBRCA2-S3291 and stable RAD51 filaments protecting nascent DNA from MRE11 cleavage. In the absence of the RASSF1A/MST2/LATS1/CDK2 pathway increased resection of newly synthesized DNA leads to chromosomal instability and malignant transformation. This function of RASSF1A in stalled replication fork protection adds to the role of RASSF1A as a tumor suppressor and builds up evidence for RASSF1A status and its prognostic and predictive value in cancer.

RASSF1A-LATS1 signalling stabilizes replication forks by restricting CDK2-mediated phosphorylation of BRCA2

Genomic instability is a key hallmark of cancer leading to tumour heterogeneity and therapeutic resistance. BRCA2 has a fundamental role in error-free DNA repair but also sustains genome integrity by promoting RAD51 nucleofilament formation at stalled replication forks. CDK2 phosphorylates BRCA2 (pS3291-BRCA2) to limit stabilizing contacts with polymerized RAD51; however, how replication stress modulates CDK2 activity and whether loss of pS3291-BRCA2 regulation results in genomic instability of tumours are not known. Here we demonstrate that the Hippo pathway kinase LATS1 interacts with CDK2 in response to genotoxic stress to constrain pS3291-BRCA2 and support RAD51 nucleofilaments, thereby maintaining genomic fidelity during replication stalling. We also show that LATS1 forms part of an ATR-mediated response to replication stress that requires the tumour suppressor RASSF1A. Importantly, perturbation of the ATR-RASSF1A-LATS1 signalling axis leads to genomic defects associated with loss of BRCA2 function and contributes to genomic instability and 'BRCA-ness' in lung cancers.

Association between RASSF1A Ala133Ser polymorphism and cancer susceptibility: a meta-analysis involving 8,892 subjects

BACKGROUND

Published studies on the association between the Ras Association Domain Family 1 isoform A (RASSF1A) Ala133Ser polymorphism and cancer susceptibility have yielded conflicting results. Thus, a meta- analysis was here performed to assess the possible association.

MATERIALS AND METHODS

All eligible case-control studies published up to November 2013 on the association between RASSF1A Ala133Ser polymorphism and cancer susceptibility were identified by searching PubMed, Web of Science, Science Direct and hand search. Bothfixed- effect and random-effect models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (CIs) by using the Comprehensive Meta-Analysis software version 2.2.

RESULTS

A total of 10 studies including 4,572 cancer cases and 4,320 controls were included in the meta-analysis. Overall, significantly increased cancer risk was associated with the variant Ser133 when all studies were pooled (Ser vs Ala: OR=1.51, 95% CI=1.08- 2.12, Pheterogeneity≤0.001; Ser/Ser+Ala/Ser vs Ala/Ala: OR=1.55, 95% CI=1.08-2.22, Pheterogeneity ≤ 0.001). Moreover, in subgroup analyses by cancer types, a significant association between RASSF1A Ala133Ser polymorphism and lung cancer risk was found (Ser vs Ala: OR=2.27, 95% CI=1.29-4.02, Pheterogeneity=0.61; Ser/Ser+Ala/ Ser vs Ala/Ala: OR=2.42, 95% CI=1.33-4.42, Pheterogeneity=0.75). In addition, in subgroup analyses by ethnicity, it was found that the RASSF1A Ala133Ser polymorphism was associated with overall cancer risk in Asians (Ser vs Ala: OR=1.37, 95% CI=1.06-1.77, Pheterogeneity=0.06) and Caucasians (Ser/Ser+Ala/Ser vs Ala/Ala: OR=2.21, 95% CI=1.01-4.82, Pheterogeneity≤0.001).

CONCLUSIONS

This meta-analysis suggests, for the first time, that RASSF1A Ala133Ser polymorphism may contribute to cancer susceptibility, especially for lung cancer. Besides, additional well-designed studies with larger sample size focusing on different ethnicities and cancer types are needed to confirm these findings.

Polymorphism of A133S and promoter hypermethylation in Ras association domain family 1A gene (RASSF1A) is associated with risk of esophageal and gastric cardia cancers in Chinese population from high incidence area in northern China

Background

The role of tumor suppressor gene RASSF1A in the esophageal and gastric cardia carcinogenesis is still inconclusive. In this study, the polymorphism, promoter methylation and gene expression of RASSF1A were characterized in esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA).

Methods

We firstly analyzed the prevalence of RASSF1A A133S in a total of 228 cancer patients with ESCC (n=112) and GCA (n=116) and 235 normal controls by polymerase chain reaction (PCR) and restriction enzyme-digestion assay. Then, the promoter methylation status of the RASSF1A in ESCC (n=143), GCA (n=92) and corresponding adjacent normal tissues were further investigated using methylation-specific PCR (MSP) approach. Finally, the RASSF1A protein expression were determined in ESCC (n=27), GCA (n=24) and the matched adjacent normal tissues by immunohistochemical method.

Results

The frequency of 133Ala/Se and Ser/Ser genotype was significantly higher in GCA patients than in normal controls (19.0% vs. 10.2%, P=0.02). Compared with Ala/Ala genotype, Ala/Se and Ser/Ser genotype significantly increased susceptibility to GCA (OR=2.06, 95% CI=1.09–3.97). However, this polymorphism had no association with ESCC (P=0.69). The promoter methylation of RASSF1A gene was significantly increased the risk to both ESCC (OR=5.90, 95% CI=2.78–12.52) and GCA (OR=7.50, 95% CI= 2.78–20.23). Promoter methylation of RASSF1A gene in ESCC was also associated with age and cancer cell differentiation (for age: OR=3.11, 95% CI=1.10–8.73; for differentiation: OR=0.29, 95% CI=0.12–0.69). RASSF1A positive expression was significantly decreased the risk of GCA (OR=0.16, 95% CI=0.03–0.83). In contrast, there was no statistical significance between RASSF1A positive expression and ESCC. The expression of RASSF1A protein trend to be positively related with older GCA patients (OR=16.20, 95% CI=1.57–167.74).

Conclusions

The present findings suggest that alterations of RASSF1A may play an important role in gastric cardia carcinogenesis in terms of polymorphism, promoter hypermethylation and protein expression. Whereas, RASSF1A hypermethylation may probably also be involved in esophageal squamous cell carcinogenesis.

RASSF1 Polymorphisms in Cancer

Ras association domain family 1A (RASSF1A) is one of the most epigenetically silenced elements in human cancers. Localized on chromosome 3, it has been demonstrated to be a bone fide tumor suppressor influencing cell cycle events, microtubule stability, apoptosis, and autophagy. Although it is epigenetically silenced by promoter-specific methylation in cancers, several somatic nucleotide changes (polymorphisms) have been identified in RASSF1A in tissues from cancer patients. We speculate that both nucleotide changes and epigenetic silencing result in loss of the RASSF1A tumor suppressor function and the appearance of enhanced growth. This paper will summarize what is known about the origin of these polymorphisms and how they have helped us understand the biological role of RASSF1A.

Association of RASSF1A genotype and haplotype with the progression of clear cell renal cell carcinoma in Japanese patients

What's known on the subject? and What does the study add? Ras association domain family 1A (RASSF1A) is a tumour suppressor and regulates cell cycle, apoptosis and microtubule stability. This is the first study to identify associations between RASSF1A polymorphisms and clinicopathological parameters and survival in patients with clear cell renal cell carcinoma (CCRCC). RASSF1A genotyping may be useful for predicting the prognosis of the clinical course of CCRCC, and this finding might provide a better understanding of the mechanism underlying the development and progression of CCRCC. However, functional and prospective studies with a larger number of patients are needed to confirm the results.

OBJECTIVE

To compare Ras association domain family 1A (RASSF1A) genotypes or haplotypes with clinicopathological characteristics and survival rates of patients with clear cell renal cell carcinoma (CCRCC).

PATIENTS AND METHODS

The study cohort comprised 224 Japanese patients who underwent radical nephrectomy and had CCRCC confirmed by histopathological analysis. • Three common polymorphisms in the RASSF1A gene, 133Ala/Ser (G/T), -710C/T and -392C/T, were genotyped using TaqMan assays and haplotypes were analysed using appropriate software.

RESULTS

Patients with CCRCC with RASSF1A -710TT genotype exhibited a significantly higher tumour stage and higher stage grouping than those with -710CC or -710CT (P = 0.005 and P = 0.032, respectively). • There was no significant association between 133Ala/Ser or -392C/T genotype and clinicopathological characteristics. • RASSF1A 133Ala-710T-392T haplotype and -710TT genotype were significantly associated with poorer recurrence-free survival rates (P = 0.038 and P = 0.007, respectively).

CONCLUSIONS

This is the first study to identify associations between RASSF1A polymorphisms and clinicopathological parameters and survival in patients with CCRCC. • RASSF1A genotyping may be useful in predicting the prognosis of the clinical course of CCRCC, and this finding might provide a better understanding of the mechanism underlying the development and progression of CCRCC. • Functional and prospective studies with a larger number of patients are needed to confirm the results.

A RASSF1A polymorphism restricts p53/p73 activation and associates with poor survival and accelerated age of onset of soft tissue sarcoma

RASSF1A (Ras association domain containing family 1A), a tumor suppressor gene that is frequently inactivated in human cancers, is phosphorylated by ataxia telangiectasia mutated (ATM) on Ser131 upon DNA damage, leading to activation of a p73-dependent apoptotic response. A single-nucleotide polymorphism located in the region of the key ATM activation site of RASSF1A predicts the conversion of alanine (encoded by the major G allele) to serine (encoded by the minor T allele) at residue 133 of RASSF1A (p.Ala133Ser). Secondary protein structure prediction studies suggest that an alpha helix containing the ATM recognition site is disrupted in the serine isoform of RASSF1A (RASSF1A-p.133Ser). In this study, we observed a reduced ability of ATM to recruit and phosphorylate RASSF1A-p.133Ser upon DNA damage. RASSF1A-p.133Ser failed to activate the MST2/LATS pathway, which is required for YAP/p73-mediated apoptosis, and negatively affected the activation of p53, culminating in a defective cellular response to DNA damage. Consistent with a defective p53 response, we found that male soft tissue sarcoma patients carrying the minor T allele encoding RASSF1A-p.133Ser exhibited poorer tumor-specific survival and earlier age of onset compared with patients homozygous for the major G allele. Our findings propose a model that suggests a certain subset of the population have inherently weaker p73/p53 activation due to inefficient signaling through RASSF1A, which affects both cancer incidence and survival.

RASSF1A Ala133Ser polymorphism is associated with increased susceptibility to hepatocellular carcinoma in a Turkish population

AIM

The tumor suppressor gene Ras association domain family 1 isoform A (RASSF1A) regulates cell cycle regulation, apoptosis and microtubule stability and is inactivated by promoter hypermethylation at a high frequency in hepatocellular carcinoma (HCC). A guanine (G)/thymine (T) common single nucleotide polymorphism (SNP) at first position of codon 133 in RASSF1A gene determines an alanine (Ala) to serine (Ser) (Ala133Ser) amino acidic substitution which may alter cancer risk by influencing the function of RASSF1A protein.

METHODS

To determine the association of the RASSF1A Ala133Ser polymorphism with the risk of HCC development in a Turkish population, a hospital-based case-control study was designed consisting of 236 subjects with HCC and 236 cancer-free control subjects matched for age, gender, smoking and alcohol status. The genotype frequency of the RASSF1A Ala133Ser polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay.

RESULTS

Allele and genotype associations of RASSF1A Ala133Ser polymorphism with HCC susceptibility were observed in comparisons between the patient and control samples (P<0.001). Risk of HCC development in this Turkish population was significantly increased in carriers of the Ser133 variant allele of Ala133Ser polymorphism (Ala/Ser and Ser/Ser genotypes) when compared with homozygote Ala/Ala genotype (OR=5.47, 95% CI=3.63-8.25, P=0.001).

CONCLUSION

Because our results suggest for the first time that the Ser133 allele of RASSF1A Ala133Ser polymorphism may be a genetic susceptibility factor for HCC in the Turkish population, further independent studies are required to validate our findings in a larger series, as well as in patients of different ethnic origins.

RASSF1A and the rs2073498 Cancer Associated SNP

RASSF1A is one of the most frequently inactivated tumor suppressors yet identified in human cancer. It is pro-apoptotic and appears to function as a scaffolding protein that interacts with a variety of other tumor suppressors to modulate their function. It can also complex with the Ras oncoprotein and may serve to integrate pro-growth and pro-death signaling pathways. A SNP has been identified that is present in approximately 29% of European populations [rs2073498, A(133)S]. Several studies have now presented evidence that this SNP is associated with an enhanced risk of developing breast cancer. We have used a proteomics based approach to identify multiple differences in the pattern of protein/protein interactions mediated by the wild type compared to the SNP variant protein. We have also identified a significant difference in biological activity between wild type and SNP variant protein. However, we have found only a very modest association of the SNP with breast cancer predisposition.

The association between RASSF1 gene polymorphisms and lung cancer susceptibility among people in Hubei Province of China

The relationship between Ala/Ser polymorphism in 133 codon of exon 3 region of the RASSF1 gene and genetic susceptibility of lung cancer in Hubei province Han population was investigated by a case-control study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was adopted to analyze the polymorphism of codon 133 of exon 3 in the RASSF1 gene of 100 pathologically diagnosed lung cancer patients, and 100 healthy controls. The relationship between different genotypes and the susceptibility of lung cancer was analyzed. Among 200 blood samples from Han people in Hubei Province, including 100 from lung cancer patients and 100 from healthy controls, the frequencies of Ala/Ala, Ala/Ser, Ser/Ser genotype of the RASSF1 in lung cancer patients were 83%, 16%, 1%, and those in healthy controls was 93%, 7%, 0% respectively, with the difference being statistically significant between two groups (P<0.05). The individuals with Ala/Ser genotype had higher risk of suffering from lung cancer, with an OR of 2.341, and 95% CI of 1.009-6.393 respectively. It was concluded that RASSF1Ala133Ser was a susceptible genetic factor of lung cancer. Ala/Ser genotype increased the risk of lung cancer.

Putative association of the single nucleotide polymorphisms in RASSF1A promoter with Korean lung cancer

SUMMARY

The RASSF1 gene, a putative tumor suppressor gene located on human chromosome 3p21, has attracted a great deal of attention because of frequent allelic loss and gene silencing via promoter hypermethylation in a variety of human malignancies. To evaluate the role of RASSF1A gene in lung cancer risk, genotypes of the RASSF1A promoter region (-710 C>T and -392T>C) were determined in 410 lung cancer patients and 410 normal subjects. Furthermore, to examine potential effects of the common haplotypes (C-C, T-T and C-T haplotypes) on RASSF1A transcription, luciferase reporter assays were performed in H2009 and H358 non-small cell lung cancer (NSCLC) cell lines. We found that ht2 C-T haplotype was associated with susceptibility to the risk of lung cancer in dominant (odds ratio (OR): 0.69; 95% CI: 0.46-0.99) model. In particular, we found that C-T haplotype showed a decreased risk of lung cancer in males (codominant OR: 0.59; 95% CI: 0.38-0.93 and dominant OR: 0.58; 95% CI: 0.35-0.96) and in smokers (codominant OR: 0.58; 95% CI: 0.36-0.93 and dominant OR: 0.56; 95% CI: 0.33-0.96). Interestingly, C-T haplotype induced transcriptional activity by 50-60% compared with other haplotypes in NSCLC cell lines. These results suggest that RASSF1A promoter polymorphisms affect RASSF1A expression, further contributing to the genetic susceptibility to lung cancer.