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Keywords:

  • renal cell carcinoma;
  • RASSF1;
  • polymorphism;
  • survival

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

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.

Abbreviations
CCRCC

clear cell RCC

VHL

von Hippel–Lindau

TSG

tumour suppressor gene

RASSF1A

Ras association domain family 1A

SNP

single-nucleotide polymorphism

INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

RCC is a common urological tumour and accounts for 3%–4% of all human malignancies [1]. It has been acknowledged that the prognosis of RCC differs significantly among individuals. The prediction of prognosis and stratification by their risk of progression are important for personalized treatments and follow-up strategies. RCCs are heterogeneous in terms of histology and genetics, as well as clinical behaviour. Clear cell and papillary carcinomas are the two most frequent subtypes of RCC (75%–80% vs 10%–15%, respectively) [2,3].

Deletions of chromosome 3p are frequent in many adult cancers including RCC [4]. Loss of 3p is detected in 45%–90% of sporadic RCCs, predominantly in clear cell RCC (CCRCC) rather than non-clear-cell RCC [5]. von Hippel–Lindau (VHL) is a tumour suppressor gene (TSG) at chromosome 3p25 and genetic alterations of this gene are observed in up to 70% of CCRCCs, whereas GpG island methylation of VHL is found in 19% of CCRCC. Both genetic and epigenetic alterations of VHL can cause inactivation of the gene [6–8]. Another TSG located at 3p is the Ras association domain family 1A (RASSF1A) gene [9]. RASSF1A, which is located at 3p21.3, is functionally involved in cell cycle control, microtubule stabilization, cellular adhesion and motility as well as apoptosis [10]. Depletion of RASSF1A is reported to be associated with accelerated mitotic progression, an increased risk for chromosomal defects [11–13], enhanced cellular motility [14] and increased tumour susceptibility in knockout mice [15]. Indeed, several investigators have reported the usefulness of RASSF1A methylation as a prognostic marker in patients with non-small-cell lung cancer [16,17], breast cancer [18] and CCRCC [19].

While mutations of the RASSF1A gene are rare events, several common polymorphisms have been identified within the region. A recent study showed that a single-nucleotide polymorphism (SNP) at codon 133 (133Ala/Ser, G/T) in RASSF1A is associated with risk of lung adenocarcinoma [20] and breast cancer [21,22]. One polymorphism, 133Ala/Ser (G/T), is located close to a putative ataxia telangiectasia mutant substrate site (131Ser) in the microtubule-binding domain. Gao et al. [22] have shown that ectopic expression of wild-type RASSF1A inhibits the accumulation of cyclin D1 during G1-S phase progression and this effect was impaired in RASSF1A 133Ser cells. Of particular note are two additional SNPs, -710C/T and -392C/T, in the promoter region of RASSF1A. Common haplotypes of the region are reportedly related to RASSF1A promoter activity, and these SNPs are implicated in lung cancer risk [23].

To the best of our knowledge, there have been no reports on associations between RASSF1A polymorphisms and patient outcome in CCRCC. Based on the biological and pathological significance of RASSF1A, it is likely that functional genetic variations in RASSF1A may contribute to the progression and prognosis of CCRCC. To investigate this hypothesis, we investigated the associations of three functional polymorphisms in the RASSF1A gene with clinicopathological parameters and survival in a cohort of Japanese patients with CCRCC. Furthermore, we compared RASSF1A polymorphisms between a healthy Japanese volunteer group and a CCRCC group.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

PATIENTS

We evaluated 224 patients with histopathologically confirmed CCRCC who underwent radical or partial nephrectomy in our institution between October 1992 and July 2006. The patients consisted of 157 men (70.0%) and 67 women (30.0%) with a median age of 65 (range 29–84) years at surgical operation. We analysed 224 age- and sex-matched healthy Japanese volunteers as control subjects. The controls (156 men, 68 women; mean age 66) were volunteers registered at the Graduate School of Medicine, Yamaguchi University.

All patients underwent chest X-rays, CT scans and bone scans, and were staged according to the TNM staging system of the International Union Against Cancer (1997). The characteristics of the 224 patients with CCRCC, all of whom were native Japanese, are shown in Table 1. Tumours were pathologically graded according to the World Health Organization classification. The median range follow-up was 45.5, ranging from 0 to 160.1 months. Written informed consent was obtained from all individuals enrolled in this study, which was approved by the institutional ethics committee of the Graduate School of Medicine, Yamaguchi University. After nephrectomy, patient checkup was performed by chest X-rays and pulmonary-to-abdominal CT scans every 6 months.

Table 1.  Clinicopathological characteristics of 224 patients with clear cell renal cell carcinoma (n)
Age (years)Median (range)65 (29–84)
Gender (%)Male157 (70.0)
Female67 (30.0)
Tumour stage (%)pT1132 (58.9)
pT236 (16.1)
pT354 (24.1)
pT42 (0.9)
Lymph node metastasis (%)Negative210 (93.8)
Positive14 (6.3)
Distant metastasis (%)Negative187 (83.5)
Positive37 (16.5)
Stage grouping (%)I121 (54.0)
II30 (13.4)
III33 (14.7)
IV40 (17.9)
Tumour grade (%)G138 (17.0)
G2150 (67.0)
G330 (13.4)
Unknown6 (2.7)

DNA EXTRACTION AND GENOTYPING

Peripheral blood samples were collected from each patient for DNA extraction and genotyping, and lymphocyte DNA was extracted using the QIAamp DNA Mini Kit (VWR International, Westchester, PA, USA). RASSF1A polymorphisms 133Ala/Ser (G/T, rs2073498), -710C/T (rs1989839) and -392C/T (rs3213621) were genotyped using the TaqMan technique (Applied Biosystems, Foster City, CA, USA), as described previously [24]. Briefly, the primer and fluorescent probe set used to amplify the 133Ala/Ser polymorphism was the TaqMan SNP Genotyping Assay C 815951024 10, for the -710C/T polymorphism was C 11934600 10 and for the -392C/T polymorphism was C 25802803 10. Reactions were carried out in 384-well microtitre plates. The assay volume was 5 µL and contained TaqMan Genotyping Master Mix (Applied Biosystems), assay mix and genomic DNA diluted in dH2O (20–40 ng of genomic DNA). The PCR protocol was 2 min at 50 °C (to degrade dU-containing DNA), 10 min at 95 °C (denaturation) and 40 cycles of 15 s at 95 °C, followed by 1 min at an annealing and extension of 60 °C. Endpoint reading of the fluorescence generated during the PCR amplification was performed using an ABI Prism 7900HT (Applied Biosystems), and genotype assignments were obtained with Sequence Detection System software (Applied Biosystems). Results were plotted on a two-dimensional scatter plot of the wild-type allele vs the polymorphic allele.

Genotypes determined by TaqMan assay were confirmed by direct sequencing of PCR products. Sequencing reactions were performed with the use of a BigDye Terminator Cycle Sequencing Kit (Applied Biosystems); the reaction products were applied to an ABI 3100-Avant Genetic Analyzer (Applied Biosystems).

STATISTICAL ANALYSIS

Hardy–Weinberg equilibrium and haplotype frequency were evaluated using SNPAlyse version 2.2 software (DYNACOM, Tokyo, Japan). Associations between genotypes and haplotypes of RASSF1A and clinicopathological characteristics at the time of CCRCC diagnosis were assessed using the chi-squared test or Fisher's exact test and odds ratio (OR) with 95% CI. The outcome selected for this study was recurrence-free survival, which was defined as the time from the nephrectomy to the date of tumour recurrence or death from CCRCC. The associations between the RASSF1A genotypes and recurrence-free survival were estimated by computing the hazard ratio (HR) and 95% CI from Cox proportional hazard regression models. In addition, recurrence-free survival rates were analysed by plotting Kaplan–Meier curves, and the survival probability distributions were compared using the log-rank test; in all tests (two-sided) P < 0.05 was taken to indicate statistical significance. Data were processed using JMP software (SAS Institute, Cary, NC, USA).

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

The RASSF1A genotype and haplotype distributions of 133Ala/Ser, -710C/T and -392C/T among 224 patients with CCRCC are presented in Table 1. Each of the observed genotype frequencies was in accordance with the Hardy–Weinberg equilibrium for autosomal genes. No significant associations were detected between genotypes or haplotypes and patients' age or gender.

We found no significant correlation between three polymorphisms in RASSF1A and CCRCC risk (Table 2). The associations of RASSF1A genotypes and haplotypes with stage and grade are shown in Table 3. The TT genotype of -710C/T was significantly more frequent in patients with pT2, or more advanced stage tumours, than in those with pT1, compared with the CC + CT genotype (OR 2.75; 95% CI 1.35–5.61; P = 0.005). The associations of RASSF1A genotypes and haplotypes with lymph node metastasis, distant metastasis and the stage grouping at initial diagnosis are shown in Table 4. The TT genotype of -710C/T was significantly more frequent in patients with stage groupings II, III and IV than in those with stage grouping I compared with the CC + CT genotype (OR 2.15; 95% CI 1.06–4.36; P = 0.032). There were no significant associations of the 133Ala/Ser or -392C/T genotypes with clinicopathological parameters.

Table 2.  Comparison of genotype frequencies of the RASSF1A polymorphism between patients with clear cell renal cell carcinoma and control subjects
GenotypePatients, n (%)Controls, n (%) P
-710C/T   
 CC64 (28.6)77 (34.4) 
 CT121 (54.0)105 (46.9)0.13
 TT39 (17.4)42 (18.8)0.69
-392C/T   
 CC49 (21.9)60 (26.8) 
 CT118 (52.7)105 (46.9)0.17
 TT57 (25.4)59 (26.3)0.53
133Ala/Ser   
 AlaAla204 (91.1)194 (86.6) 
 AlaSer17 (7.6)29 (12.9)0.066
 SerSer3 (1.3)1 (0.4)0.34
Table 3.  Associations of the RASSF1A genotypes and haplotypes with stage and grade
RASSF1A polymorphismTumour stageOdds ratio (95% CI) P * Tumour gradeOdds ratio (95% CI) P * Lymph node metastasis
pT1 (%)≥pT2 (%)G1 (%)G2 or G3 (%)Negative (%)Positive (%)
  • *

    Chi-squared test or Fisher's exact test.

  • †The bold entries indicate statistical significance.

  • ‡Because of the small number of homozygous variant alleles, the combined results for the heterozygous and homozygous variant alleles are shown.

-710C/T          
 CC37 (28.0)27 (29.3)1.00 (reference) 9 (23.7)54 (30.0)1.00 (reference) 61 (29.0)3 (21.4)
 CT80 (60.6)41 (44.6)0.43 (0.21–0.82)0.2725 (65.8)92 (51.1)0.68 (0.31–1.57)0.24110 (52.4)11 (78.6)
 TT15 (11.4)24 (26.1)2.19 (0.97–4.95)0.0564 (10.5)34 (18.9)1.42 (0.40–4.96)0.5839 (18.6)0 (0.0)
 CC + CT117 (88.6)68 (73.9)1.00 (reference) 34 (89.5)146 (81.1)1.00 (reference) 171 (81.4)14 (100.0)
 TT15 (11.4)24 (26.1)2.75 (1.35–5.61) 0.0046 4 (10.5)34 (18.9)1.98 (0.66–5.95)0.2539 (18.6)0 (0.0)
-392C/T          
 CC30 (22.7)19 (20.7)1.00 (reference) 9 (23.7)40 (19.8)1.00 (reference) 47 (22.4)2 (25.0)
 CT74 (56.1)44 (47.8)1.34 (0.62–2.99)0.8623 (60.5)92 (45.3)0.57 (0.16–1.70)0.81109 (51.9)9 (31.3)
 TT28 (21.2)29 (31.5)1.52 (0.69–3.50)0.216 (15.8)48 (34.9)0.64 (0.17–2.04)0.3054 (25.7)3 (43.8)
 CC + CT104 (78.8)63 (68.5)1.00 (reference) 32 (84.2)132 (65.1)1.00 (reference) 156 (74.3)11 (56.3)
 TT28 (21.2)29 (31.5)1.71 (0.93–3.14)0.0836 (15.8)48 (34.9)1.94 (0.76–4.93)0.1454 (25.7)3 (43.8)
133Ala/Ser          
 AlaAla120 (90.9)84 (91.3)1.00 (reference) 37 (97.4)162 (90.0)1.00 (reference) 193 (91.9)11 (78.6)
 AlaSer + SerSer12 (9.1)8 (8.7)0.80 (0.46–1.40)0.921 (2.6)18 (10.0)0.66 (0.30–1.43)0.2117 (8.1)3 (21.4)
-710/-392/133 haplotype          
 TTAla110 (41.7)89 (48.4)1.00 (reference) 33 (43.4)160 (44.2)1.00 (reference) 188 (44.8)11 (39.3)
 CCAla134 (50.8)82 (44.6)0.76 (0.51–1.12)0.1641 (53.9)173 (47.8)0.87 (0.52–1.44)0.59203 (48.3)13 (46.4)
 CTSer14 (5.3)9 (4.9)0.80 (0.33–1.92)0.611 (1.3)21 (5.8)4.33 (0.56–33.3)0.1720 (4.8)3 (10.7)
 CTAla6 (2.3)4 (2.2)0.82 (0.23–3.01)0.771 (1.3)8 (2.2)1.65 (0.20–13.6)0.649 (2.1)1 (3.6)
Table 4.  Associations of the RASSF1A genotypes and haplotypes with lymph node metastasis, distant metastasis and the stage grouping at initial diagnosis
RASSF1A polymorphismDistant metastasisOdds ratio (95% CI) P * Stage groupingOdds ratio (95% CI) P *
Negative (%)Positive (%)I (%)≥II (%)
  • *

    Chi-squared test or Fisher's exact test.

  • †The bold entries indicate statistical significance.

  • ‡Because of the small number of homozygous variant alleles, the combined results for the heterozygous and homozygous variant alleles are shown.

-710C/T        
 CC54 (28.9)10 (27.0)1.00 (reference) 33 (27.3)31 (30.1)1.00 (reference) 
 CT102 (54.5)19 (51.4)0.94 (0.39–2.10)0.9973 (60.3)48 (46.6)0.49 (0.26–0.92)0.25
 TT31 (16.6)8 (21.6)1.39 (0.50–3.90)0.5315 (12.4)24 (23.3)1.70 (0.76–3.83)0.19
 CC + CT156 (83.4)29 (78.4)1.00 (reference) 106 (87.6)79 (76.7)1.00 (reference) 
 TT31 (16.6)8 (21.6)1.39 (0.58–3.32)0.4715 (12.4)24 (23.3)2.15 (1.06–4.36) 0.032
-392C/T        
 CC41 (21.9)8 (14.3)1.00 (reference) 26 (21.5)23 (22.3)1.00 (reference) 
 CT98 (52.4)20 (40.0)1.13 (0.40–3.71)0.9268 (56.2)50 (48.5)1.10 (0.52–2.34)0.59
 TT48 (25.7)9 (45.7)1.99 (0.70–6.55)0.9427 (22.3)30 (29.1)1.23 (0.56–2.70)0.56
 CC + CT139 (74.3)28 (54.3)1.00 (reference) 94 (77.7)73 (70.9)1.00 (reference) 
 TT48 (25.7)9 (45.7)0.93 (0.41–2.11)0.8627 (22.3)30 (29.1)1.43 (0.78–2.62)0.24
133Ala/Ser        
 AlaAla169 (90.4)35 (94.6)1.00 (reference) 110 (90.9)94 (91.3)1.00 (reference) 
 AlaSer + SerSer18 (9.6)2 (5.4)1.07 (0.50–2.30)0.5411 (9.1)9 (8.7)0.74 (0.42–1.31)0.93
-710/-392/133 haplotype        
 TTAla164 (43.9)35 (46.1)1.00 (reference) 103 (42.6)96 (46.2)1.00 (reference) 
 CCAla180 (48.1)37 (48.7)0.96 (0.58–1.60)0.88120 (49.6)97 (46.6)0.87 (0.59–1.28)0.47
 CTSer21 (5.6)2 (2.6)0.45 (0.10–1.99)0.2813 (5.4)10 (4.8)0.83 (0.35–1.97)0.67
 CTAla9 (2.4)2 (2.6)1.04 (0.22–5.03)0.966 (2.5)5 (2.4)0.89 (0.26–3.03)0.86

RASSF1A genotype and haplotype associations with recurrence are shown in Table 5. The TT genotypes of -710C/T were significantly more frequent in patients with recurrence than in those without recurrence compared with the CC + CT genotype (HR 2.51; 95% CI 1.24–5.09; P = 0.012). In addition, the CCAla, CTSer and CTAla haplotypes of -710/-392/133Ala/Ser were significantly less frequent in patients with recurrence than in those without recurrence (HR 0.65; 95% CI 0.43–0.97; P = 0.034).

Table 5.  Associations of the RASSF1A genotypes with recurrence
RASSF1A genotype (n)Recurrence (−)Recurrence (+)Hazard ratio (95% CI) P *
  • *

    Chi-squared test or Fisher's exact test.

  • †The bold entries indicate statistical significance.

  • ‡Due to the small number of homozygous variant alleles, the combined results for the heterozygous and homozygous variant alleles are shown.

-710C/T    
 CC47 (30.9)16 (23.2)1.00 (reference) 
 CT85 (55.9)34 (49.3)1.18 (0.69–2.35)0.65
 TT20 (13.2)19 (27.5)2.79 (1.20–6.51) 0.017
 CC + CT132 (86.8)50 (72.5)1.00 (reference) 
 TT20 (13.2)19 (17.5)2.51 (1.24–5.09) 0.012
-392C/T    
 CC35 (23.0)14 (20.3)1.00 (reference) 
 CT82 (53.9)33 (47.8)1.01 (0.48–2.11)0.99
 TT35 (23.0)22 (31.9)1.57 (0.69–3.56)0.28
 CC + CT117 (77.0)47 (68.1)1.00 (reference) 
 TT35 (23.0)22 (31.9)1.57 (0.83–2.94)0.17
133Ala/Ser    
 AlaAla138 (90.8)64 (92.8)1.00 (reference) 
 AlaSer + SerSer14 (9.2)5 (7.2)0.77 (0.27–2.23)0.62
-710/-392/133 haplotype (%)    
 TTAla124 (41.3)72 (52.2)1.00 (reference) 
 CCAla149 (49.7)61 (44.2)0.71 (0.47–1.07)0.099
 CTSer17 (5.7)5 (3.6)1.01 (0.44–2.33)0.19
 CTAla10 (3.3)0 (0.0) 0.017
 TTAla124 (41.3)72 (52.2)1.00 (reference) 
 CCAla + CTSer + CTAla176 (58.7)66 (47.8)0.65 (0.43–0.97) 0.034

Cox proportional hazards regression analyses for the RASSF1A genotypes influencing recurrence-free survival rates in patients with CCRCC are shown in Table 5. The RASSF1A -710T/T genotype was significantly associated with recurrence-free survival compared with the CC + CT genotype (HR 1.46; 95% CI 1.09–1.93; P = 0.012). Thus, patients with the -710TT genotype had significantly poorer recurrence-free survival rates than those with CC or CT. In addition, Kaplan–Meier survival curves showed that the TT genotype of -710C/T had a significantly shorter recurrence time than that of CC or CT genotypes (P = 0.007; log-rank test; Fig. 1).

image

Figure 1. Kaplan–Meier recurrence-free survival curves for patients with clear cell renal cell carcinoma, grouped by RASSF1A -710C/T genotypes (CC or CT vs TT; P = 0.007; log-rank test).

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DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

Numerous studies have shown that overexpression of RASSF1 promotes apoptosis and cell cycle arrest and reduces the tumourigenicity of cancer cell lines [25]. Depletion of RASSF1A is reported to be associated with accelerated mitotic progression, an increased risk for chromosomal defects [11–13], enhanced cellular motility [14] and increased tumour susceptibility in knockout mice [15]. Thus, inactivation of RASSF1A may play critical roles in the development and progression of many types of cancer including CCRCC. Loss of RASSF1A expression is largely attributed to promoter hypermethylation [26]. Indeed, several investigators have reported RASSF1A methylation to be a useful prognostic marker in patients with non-small-cell lung cancer [16,17], breast cancer [18] and CCRCC [19].

Somatic mutations of RASSF1A are uncommon in tumour cells; however, several common polymorphisms have been detected in RASSF1A[26]. Recent studies showed that SNPs of the RASSF1A gene are associated with the risk of lung adenocarcinoma [20,23] and breast cancer [21,22]. One polymorphism, 133Ala/Ser (G/T), is located close to a putative ataxia telangiectasia mutant substrate site (131Ser) in the microtubule-binding domain. Gao et al. [22] have shown that ectopic expression of wild-type RASSF1A inhibits the accumulation of cyclin D1 during G1-S phase progression and this effect is impaired in RASSF1A 133Ser cells. Sung et al. [23] reported that the CT haplotype of the RASSF1A promoter (-710 C/T and -392 C/T loci) has a protective effect on the risk of lung cancer and that in non-small-cell lung cancer cell lines the CT haplotype shows significantly increased promoter activity compared with the CC or TT haplotypes [23].

No studies have provided evidence for the association of RASSF1 gene polymorphisms with CCRCC thus far. We carried out a study on the Japanese population to validate our hypothesis; however, we found no significant correlation between three polymorphisms in RASSF1 and CCRCC risk. Interestingly, though, we observed significant correlations of the -710TT genotype with higher tumour stage and higher stage grouping. Additionally, the -710TT genotype and the 133Ala-710T-392T haplotype were significantly associated with poorer recurrence-free survival. These results suggest that the -710TT genotype and the 133Ala-710T-392T haplotype might be associated with decreased RASSF1A expression, which acts to promote tumourigenicity, thereby resulting in a higher tumour stage and poorer survival. Therefore, RASSF1A gene polymorphisms may possibly be associated with altered RASSF1A expression, and might influence tumour progression and survival in CCRCC. However, we did not directly examine RASSF1A expression in cancer cells and their normal neighbours, thus further limiting the generalizability and interpretation of our study.

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

This is the first study to report an association between RASSF1A polymorphisms and clinicopathological parameters and survival in patients with CCRCC. We found significant associations between a RASSF1A genotype or haplotype and progression or prognosis of CCRCC. These results suggest that this RASSF1A genotype and haplotype might be useful as a predictive factor for the clinical course of CCRCC. Furthermore, our finding might provide a better understanding of the mechanism underlying the development and progression of CCRCC. In addition, our results might provide new opportunities to develop therapeutic interventions targeted at reversing RASSF1A silencing or the downstream consequences of RASSF1A inactivation for patients with CCRCC. However, our results were obtained with a limited sample size and therefore limit us to preliminary conclusions. Functional and independent studies with a larger number of patients are needed to confirm our results.

ACKNOWLEDGEMENTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES

This study was supported, in part, by a Grant-in-Aid for Scientific Research (C) (21592047) from the Japan Society for the Promotion of Science.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. ACKNOWLEDGEMENTS
  9. CONFLICT OF INTEREST
  10. REFERENCES