TGFBR1 variants TGFBR1(*)6A and Int7G24A are not associated with an increased familial colorectal cancer risk

Association of a let-7 miRNA binding region of TGFBR1 with hereditary mismatch repair proficient colorectal cancer (MSS HNPCC)

The purpose of this study was to identify novel colorectal cancer (CRC)-causing alleles in unexplained familial CRC cases. In order to do so, coding regions in five candidate genes (MGMT, AXIN2, CTNNB1, TGFBR1 and TGFBR2) were sequenced in 11 unrelated microsatellite-stable hereditary non-polyposis CRC (MSS HNPCC) cases. Selected genetic variants were genotyped in a discovery set of 27 MSS HNPCC cases and 85 controls. One genetic variant, rs67687202, in TGFBR1 emerged as significant (P = 0.002), and it was genotyped in a replication set of 87 additional MSS HNPCC-like cases and 338 controls where it was also significantly associated with MSS HNPCC cases (P = 0.041). In the combined genotype data, rs67687202 was associated with a moderate increase in CRC risk (OR = 1.68; 95% CI = 1.13-2.50; P = 0.010). We tested a highly correlated SNP rs868 in 723 non-familial CRC cases compared with 629 controls, and it was not significantly associated with CRC risk (P = 0.370). rs868 is contained in a let-7 miRNA binding site in the 3'UTR of TGFBR1, which might provide a functional basis for the association in MSS HNPCC. In luciferase assays, the risk-associated allele for rs868 was associated with half the luciferase expression in the presence of miRNA let-7b-5p compared with protective allele, suggesting more binding of let-7b-5p and less TGFBR1 expression. Thus, rs868 potentially is a CRC risk-causing allele. Our results support the concept that rs868 is associated with lower TGFBR1 expression thereby increasing CRC risk.

TGFBR1*6A polymorphism in sporadic and familial colorectal Carcinoma: a case-control study and systematic literature review

BACKGROUND

The role of genetic factors in colorectal cancer pathogenesis is widely accepted. Polymorphisms are actually thought to play a role in the unexplained colorectal cancer (CRC) susceptibility. There is conflicting data regarding the role of the transforming growth factor beta receptor 1 polymorphism 6A (TGFBR1*6A) in the increased incidence of CRC.

PURPOSE

Our aim is to test the association between this polymorphism and sporadic/familial CRC in the Lebanese population paying attention to lead time bias in the control group. This is a case-control study conducted in two Lebanese hospital centers.

MATERIALS AND METHODS

Cases were diagnosed with CRC during the period of 1 year prior to the study. Controls were healthy subjects aged >50 years with a history of normal colonoscopy during the period of 5 years prior to the beginning of the study. A total of 96 cases (57 sporadic/39 familial) and 97 controls were genotyped. The odds ratios for 6A carrier status was statistically significant for sporadic CRC, odds ratio (OR) = 2.314 (95 % confidence interval (CI) 1.030-5.195) but not for familial CRC.

RESULTS

No association was found between 6A carrier status and mean age at diagnosis of CRC. This is the first article in the literature to evaluate the association between 6A polymorphism and total, sporadic, and familial CRC in a single study with reduction of bias in the control group. Results are in conjunction with other studies and meta-analysis.

Association between Int7G24A rs334354 polymorphism and cancer risk: a meta-analysis of case-control studies

Accumulating evidences have suggested the potential association between Int7G24A (rs334354) polymorphism and cancer risk. However, results from epidemiological studies are controversial. We thus conducted this meta-analysis to clarify the association. Relevant studies were identified on electronic databases according to the inclusion criteria. A total of 13 case-control studies containing 4092 cases and 5909 controls were included in our meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the association. The results of the overall population had suggested that Int7G24A polymorphism had an increased risk for cancer, reaching significant levels in the 2 genetic models (allele model, OR = 1.25, 95% CI 1.09-1.42, P = 0.001; dominant model, OR = 1.24, 95% CI 1.06-1.46, P < 0.008). Besides, significant association was found among Asian population (allele model, OR = 1.27, 95% CI 1.11-1.45, P < 0.001; dominant model, OR = 1.28, 95% CI 1.11-1.49, P < 0.001), whereas there was non-significant relationship detected among Caucasian population (allele model, OR = 1.08, 95% CI 0.92-1.26, P = 0.352; dominant model, OR = 1.05, 95% CI 0.87-1.26, P = 0.639). The present meta-analysis had suggested that Int7G24A polymorphism of gene TGFBR1 involved in the transforming growth factor beta (TGF-β) signaling pathway had a significantly increased risk for cancer development.

Little evidence for association between the TGFBR1*6A variant and colorectal cancer: a family-based association study on non-syndromic family members from Australia and Spain

Background

Genome-wide linkage studies have identified the 9q22 chromosomal region as linked with colorectal cancer (CRC) predisposition. A candidate gene in this region is transforming growth factor β receptor 1 (TGFBR1). Investigation of TGFBR1 has focused on the common genetic variant rs11466445, a short exonic deletion of nine base pairs which results in truncation of a stretch of nine alanine residues to six alanine residues in the gene product. While the six alanine (*6A) allele has been reported to be associated with increased risk of CRC in some population based study groups this association remains the subject of robust debate. To date, reports have been limited to population-based case–control association studies, or case–control studies of CRC families selecting one affected individual per family. No study has yet taken advantage of all the genetic information provided by multiplex CRC families.

Methods

We have tested for an association between rs11466445 and risk of CRC using several family-based statistical tests in a new study group comprising members of non-syndromic high risk CRC families sourced from three familial cancer centres, two in Australia and one in Spain.

Results

We report a finding of a nominally significant result using the pedigree-based association test approach (PBAT; p = 0.028), while other family-based tests were non-significant, but with a p-value <; 0.10 in each instance. These other tests included the Generalised Disequilibrium Test (GDT; p = 0.085), parent of origin GDT Generalised Disequilibrium Test (GDT-PO; p = 0.081) and empirical Family-Based Association Test (FBAT; p = 0.096, additive model). Related-person case–control testing using the “More Powerful” Quasi-Likelihood Score Test did not provide any evidence for association (M_QLS; p = 0.41).

Conclusions

After conservatively taking into account considerations for multiple hypothesis testing, we find little evidence for an association between the TGFBR1*6A allele and CRC risk in these families. The weak support for an increase in risk in CRC predisposed families is in agreement with recent meta-analyses of case–control studies, which estimate only a modest increase in sporadic CRC risk among 6*A allele carriers.

Clinical applications of gene expression in colorectal cancer

BACKGROUND

Despite developments in diagnosis and treatment, 20% of colorectal cancer (CRC) patients present with metastatic disease and 30% of cases recur after curative surgery. Furthermore, the molecular factors involved in prognosis and response to therapy in CRC is poorly understood. The aims of this study were to quantitatively examine the expression of target genes in colorectal cancer and to correlate their expression levels with clinico-pathological variables.

METHODS

A detailed analysis of published CRC microarray data was performed to identify the most prominent genes. The selected genes were validated in fifty-two pairs of fresh colorectal tumour and associated normal tissue specimens by RQ-PCR using TaqMan(®) assays. Statistical analysis and correlation with clinicopathological data was performed using SPSS software.

RESULTS

Expression levels of CXCL12 (P=0.000), CDH17 (P=0.026), MUC2 (P=0.000), L-FABP (P=0.000) and PDCD4 (P=0.000) were down regulated and IL8 (P=0.000) was upregulated in tumours compared to normal colorectal tissues. No significant differences were noted in expression of CEACAM5, CXCR4, CXCR7, TGFB1, TGFBR1 and TGFBR2. Furthermore, we found significant associations of gene expression levels and clinicopathological variables such as tumour size, grade, invasion and lymph node status.

CONCLUSIONS

We identified a comprehensive list of genes with highly differential expression patterns in colorectal cancer that could serve as molecular markers to complement existing histopathological factors in diagnosis, follow up and therapeutic strategies for individualised care of patients.

Int7G24A polymorphism (rs334354) and cancer risk

INTRODUCTION

The transforming growth factor β (TGF-β) signaling system plays an important role in carcinogenesis. Alteration of TGF-β receptors is a potential mechanism in the development and progression of human cancers. Several studies have investigated the association between TGFBR1 gene Int7G24A and cancer risk, but the results are still inconclusive, so a meta-analysis is needed to verify the association.

MATERIAL AND METHODS

We carried out a literature search using the PubMed database (up to January 2012) to identify all papers that investigated the association between the Int7G24A polymorphism (rs334354) and cancer risk. The inclusion criteria were: (1) evaluation of the Int7G24A polymorphism and cancer risk, (2) case-control studies, (3) sufficient published data about genotype frequency. Also the strength of the association between Int7G24A polymorphism and cancer was measured by odds ratio (OR), which was calculated according to the method of Woolf. A χ(2)-based Q statistic test was performed to assess the between-study heterogeneity.

RESULTS

There are 10 studies including 2398 cases and 3465 controls in the research. Our results indicate that the TGFBR1 gene Int7G24A polymorphism is associated with cancer risk (A vs. G: OR = 1.35, 95% CI = 1.10-1.66, A/A+G/A vs. G/G: OR = 1.34, 95% CI = 1.05-1.72).

CONCLUSIONS

This meta-analysis suggests that the TGFBR1 gene Int7G24A polymorphism might be associated with an increased risk of cancer.

Association between TGFBR1 polymorphisms and cancer risk: a meta-analysis of 35 case-control studies

Background

Numerous epidemiological studies have evaluated the association between TGFBR1 polymorphisms and the risk of cancer, however, the results remain inconclusive. To derive a more precise estimation of the relation, we conducted a comprehensive meta-analysis of all available case-control studies relating the TGFBR1*6A and IVS7+24G>A polymorphisms of the TGFBR1 gene to the risk of cancer.

Methods

Eligible studies were identified by search of electronic databases. Overall and subgroup analyses were performed. Odds ratio (OR) and 95% confidence interval (CI) were applied to assess the associations between TGFBR1*6A and IVS7+24G>A polymorphisms and cancer risk.

Results

A total of 35 studies were identified, 32 with 19,767 cases and 18,516 controls for TGFBR1*6A polymorphism and 12 with 4,195 cases and 4,383 controls for IVS7+24G>A polymorphism. For TGFBR1*6A, significantly elevated cancer risk was found in all genetic models (dominant OR = 1.11, 95% CI = 1.04∼1.18; recessive: OR = 1.36, 95% CI = 1.11∼1.66; additive: OR = 1.13, 95% CI = 1.05∼1.20). In subgroup analysis based on cancer type, increased cancer risk was found in ovarian and breast cancer. For IVS7+24G>A, significant correlation with overall cancer risk (dominant: OR = 1.39, 95% CI = 1.15∼1.67; recessive: OR = 2.23, 95% CI = 1.26∼3.92; additive: OR = 1.43, 95% CI = 1.14∼1.80) was found, especially in Asian population. In the subgroup analysis stratified by cancer type, significant association was found in breast and colorectal cancer.

Conclusions

Our investigations demonstrate that TGFBR1*6A and IVS7+24G>A polymorphisms of TGFBR1 are associated with the susceptibility of cancer, and further functional research should be performed to explain the inconsistent results in different ethnicities and cancer types.

Debate about TGFBR1 and the susceptibility to colorectal cancer

Recent years have witnessed enormous progress in our understanding of the genetic predisposition to colorectal cancer (CRC). Estimates suggest that all or most genetic susceptibility mechanisms proposed so far, ranging from high-penetrance genes to low-risk alleles, account for about 60% of the population-attributable fraction of CRC predisposition. In this context, there is increasing interest in the gene encoding the transforming growth factor β receptor 1 (TGFBR1); first when over a decade ago a common polymorphism in exon 1 (rs11466445, TGFBR1*6A/9A) was suggested to be a risk allele for CRC, then when linkage studies identified the chromosomal region where the gene is located as susceptibility locus for familial CRC, and more recently when the allele-specific expression (ASE) of the gene was proposed as a risk factor for CRC. Published data on the association of TGFBR1 with CRC, regarding polymorphisms and ASE and including sporadic and familial forms of the disease, are often contradictory. This review gives a general overview of the most relevant studies in order to clarify the role of TGFBR1 in the field of CRC genetic susceptibility.

The association of polymorphisms on TGFBR1 and colorectal cancer risk: a meta-analysis

Epidemiological studies found inconsistent results on the association of two variants on TGFBR1 (TGFBR1*6A and Int7G24A) with colorectal cancer (CRC) risk. The present study was aimed to evaluate the association of these two variants with CRC susceptibility via the meta-analysis methods. For variant TGFBR1*6A, nine reports including 6,765 CRC patients and 8,496 unrelated controls were identified. The heterozygotes *6A/*9A showed a significant increased risk of CRC with the pooled OR was 1.12 (95% CI = 1.02-1.23), and the pooled OR for the homozygotes *6A/*6A was 1.13 (95% CI = 0.80-1.58) compared to the homozygotes *9A/*9A. However, under the dominant effect model, the TGFBR1*6A carriers showed a significantly increased CRC risk (pooled OR = 1.12, 95% CI = 1.03-1.23, *6A/*6A and *6A/*9A vs. *9A/*9A). For variant Int7G24A, three case-control studies with 1,074 cases and 1,945 controls were found. Although no significant association was found for heterozygosity Int7G24A carriers with CRC risk (pooled OR = 0.97, 95% CI = 0.67-1.42), the homozygosity A/A carriers showed a significant elevated risk of CRC (pooled OR = 1.68, 95% CI = 1.14-2.47) compared to G/G homozygotes. Under the recessive effect model, homozygotes A/A showed a 71% increase of CRC risk compared to the A/G and G/G genotype carriers (pooled OR = 1.71, 95% CI = 1.17-2.51). These data strongly suggested that the two polymorphisms of TGFBR1 may confer low-penetrance susceptibility of CRC risk.

Evidence of linkage to chromosomes 10p15.3-p15.1, 14q24.3-q31.1 and 9q33.3-q34.3 in non-syndromic colorectal cancer families

Up to 25% of colorectal cancer (CRC) may be caused by inherited genetic variants that have yet to be identified. Previous genome-wide linkage studies (GWLSs) have identified a new loci postulated to contain novel CRC risk genes amongst affected families carrying no identifiable mutations in any of the known susceptibility genes for familial CRC syndromes. To undertake a new GWLS, we recruited members from 54 non-syndromic families from Australia and Spain where at least two first-degree relatives were affected by CRC. We used single-nucleotide polymorphism arrays to genotype 98 concordant affected relative pairs that were informative for linkage analyses. We tested for genome-wide significance (GWS) for linkage to CRC using a quantile statistic method, and we found that GWS was achieved at the 5% level. Independently, using the PSEUDO gene-dropping algorithm, we also found that GWS for linkage to CRC was achieved (P=0.02). Merlin non-parametric linkage analysis revealed significant linkage to CRC for chromosomal region 10p15.3-p15.1 and suggestive linkage to CRC for regions on 14q and 9q. The 10p15.3-p15.1 has not been reported to be linked to hereditary CRC in previous linkage studies, but this region does harbour the Kruppel-like factor 6 (KLF6) gene that is known to be altered in common CRC. Further studies aimed at localising the responsible genes, and characterising their function will give insight into the factors responsible for susceptibility in such families, and perhaps shed further light on the mechanisms of CRC development.

Association of polymorphisms in transforming growth factor-β receptors with susceptibility to gastric cardia adenocarcinoma

Both transforming growth factor-β receptor I (TGFBR1) and receptor II (TGFBR2) are serine/threonine kinases and play important roles in TGF-β/Smads signal pathway. The case-control study was performed to evaluate the possible association of Int7G24A and *6A polymorphisms of TGFBR1 and G-875A polymorphism of TGFBR2 with susceptibility to gastric cardia adenocarcinoma (GCA) in a population of North China. Polymerase-chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR methods were used respectively to detect the genotype of Int7G24A, *6A and G-875A in 468 GCA and 584 healthy controls. Immunohistochemistry method was used to determine the protein expression of TGFBR1 and TGFBR2. Family history of upper gastrointestinal cancer (UGIC) significantly increased the risk of developing GCA. There were no differences in the genotype distribution of TGFBR1 *6A polymorphism among cases and controls. However, A allele of Int7G24A significantly elevated the risk of developing GCA (adjusted OR = 1.34, 95% CI 1.03-1.87) and A allele of G-875A significantly decreased the risk of developing GCA (adjusted OR = 0.73, 95% CI 0.49-0.92). When stratified for TNM stage, A allele of Int7G24A and G-875A allele carriers had a 1.41-fold (95% CI 1.05-1.98) increased and a 0.70-fold (95% CI 0.47-0.92) decreased risk of stage III and IV gastric cardia adenocarcinoma. The protein expression of TGFBR1 and TGFBR2 in GCA was not correlated with genotypes of them. In conclusions, TGFBR1 Int7G24A and TGFBR2 G-875A polymorphisms may play important roles in the risk of GCA in North China.

Polymorphisms in the transforming growth factor beta 1 pathway in relation to colorectal cancer progression

Transforming growth factor beta1 (TGFB1) acts as a growth inhibitor of normal colonic epithelial cells, however, as a tumor promoter of colorectal cancer (CRC) cells. To explore the association between genetic polymorphisms in the TGFB1 pathway and CRC susceptibility and clinical outcome, we carried out a case-control study on a Swedish population of 308 CRC cases and 585 age- and gender-matched controls. The cases were sampled prospectively and had up to 16 years follow-up, making the study material particularly suitable for survival analysis. On the basis of their reported or predicted functional effect, nine single-nucleotide polymorphisms (TGFB1: Leu10Pro; TGFBR1: 9A/6A and IVS7G+24A; FURIN: C-229T; THBS1: T+42C; LTBP1L: C-256G; LTBP4: T-893G and Thr750Ala; BAMBI: T-779A) were selected for genotyping. We evaluated the associations between genotypes and CRC and Dukes' stage. Survival probabilities were compared between different subgroups. The observed statistically significant associations included a decreased CRC risk for TGFBR1 IVS7G+24A minor allele carriers (odds ratio (OR): 0.72, 95% confidence interval (CI): 0.53-0.97), less aggressive tumors with Dukes' stage A+B for carriers of LTBP4 Thr750Ala and BAMBI T-779A minor alleles (OR: 0.58, 95%CI: 0.36-0.93 and OR: 0.51, 95%CI: 0.29-0.89, respectively) and worse survival for FURIN C-229T heterozygotes (hazard ratio: 1.63, 95%CI: 1.08-2.46). As this is the first study about the influence of the polymorphisms in the TGFB1 pathway on CRC progression, further studies in large independent cohorts are warranted.

The Int7G24A variant of transforming growth factor-beta receptor type I is a risk factor for colorectal cancer in the male Spanish population: a case-control study

BACKGROUND

The Int7G24A variant of transforming growth factor-beta receptor type I (TGFBR1) has been shown to increase the risk for kidney, ovarian, bladder, lung and breast cancers. Its role in colorectal cancer (CRC) has not been established. The aims of this study were to assess the association of TGFBR1*Int7G24A variant with CRC occurrence, patient age, gender, tumour location and stage.

METHODS

We performed a case-control study with 504 cases of sporadic CRC; and 504 non-cancerous age, gender and ethnically matched controls. Genotyping analysis was performed using allelic discrimination assay by real time PCR.

RESULTS

The Int7G24A variant was associated with increased CRC incidence in an additive model of inheritance (P for trend = 0.005). No significant differences were found between Int7G24A genotypes and tumour location or stage. Interestingly, the association of the Int7G24A variant with CRC risk was significant in men (odds ratio 4.10 with 95% confidence intervals 1.41-11.85 for homozygous individuals; P for trend = 0.00023), but not in women. We also observed an increase in susceptibility to CRC for individuals aged less than 70 years.

CONCLUSION

Our data suggest that the Int7G24A variant represents a risk factor for CRC in the male Spanish population.

TGFBR1*6A/9A polymorphism and cancer risk: a meta-analysis of 13,662 cases and 14,147 controls

Published data on the association between TGFBR1*6A/9A polymorphism and cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 32 studies including 13,662 cases and 14,147 controls were involved in this meta-analysis. Overall, significantly elevated cancer risks were associated with TGFBR1*6A in all genetic models (for allelic effect: OR = 1.11; 95% CI = 1.03-1.21; for 6A/6A vs. 9A/9A: OR = 1.30; 95% CI = 1.01-1.69; for 9A/6A vs. 9A/9A: OR = 1.08; 95% CI = 1.01-1.15; for dominant model: OR = 1.08; 95% CI = 1.02-1.15; for recessive model: OR = 1.29; 95% CI = 1.00-1.68). In the subgroup analysis by cancer types, significant associations were found in breast cancer (for allelic effect: OR = 1.16; 95% CI = 1.01-1.34) and ovarian cancer (for allelic effect: OR = 1.24; 95% CI = 1.00-1.54; for 6A/6A vs. 9A/9A: OR = 2.34; 95% CI = 1.03-5.33). However, no significant associations were found in colorectal cancer, bladder cancer, prostate cancer and lung cancer for all genetic models. In summary, this meta-analysis suggests that the TGFBR1*6A/9A polymorphism is associated with cancer susceptibility, increasing the risk of breast and ovarian cancer.