Increased risk for CRC in diabetic patients with the nonrisk allele of SNPs at 8q24

Cumulative evidence of relationships between multiple variants in 8q24 region and cancer incidence

Genome-wide association studies (GWAS) have identified multiple independent cancer susceptibility loci at chromosome 8q24. We aimed to evaluate the associations between variants in the 8q24 region and cancer susceptibility. A comprehensive research synopsis and meta-analysis was performed to evaluate associations between 28 variants in 8q24 and risk of 7 cancers using data from 103 eligible articles totaling 146,932 cancer cases and 219,724 controls. Results: 20 variants were significantly associated with risk of prostate cancer, colorectal cancer, thyroid cancer, breast cancer, bladder cancer, stomach cancer, and glioma, including 1 variant associated with prostate cancer, colorectal cancer, and thyroid cancer. Cumulative epidemiological evidence of an association was graded as strong for DG8S737 -8 allele, rs10090154, rs7000448 in prostate cancer, rs10808556 in colorectal cancer, rs55705857 in gliomas, rs9642880 in bladder cancer, moderate for rs16901979, rs1447295, rs6983267, rs7017300, rs7837688, rs1016343, rs620861, rs10086908 associated in prostate cancer, rs10505477, rs6983267 in colorectal cancer, rs6983267 in thyroid cancer, rs13281615 in breast cancer, and rs1447295 in stomach cancer, weak for rs6983561, rs13254738, rs7008482, rs4242384 in prostate cancer. Data from ENCODE suggested that these variants with strong evidence and other correlated variants might fall within putative functional regions. Our study provides summary evidence that common variants in the 8q24 are associated with risk of multiple cancers in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the mechanisms underlying variants in the 8q24 involved in various human cancers.

Cumulative evidence for relationships between multiple variants in 8q24 and colorectal cancer incidence

Genome-wide association studies (GWAS) have identified multiple independent cancer susceptibility loci at chromosome 8q24.We conducted a comprehensive research synopsis and meta-analysis to evaluate associations between 6 variants in 8q24 and risk of colorectal cancer using data from 31 eligible articles totaling 41,942 cases and 49,968 controls.Of the 6 variants located in 8q24, 3 were significantly associated with risk of colorectal cancer. In particular, both homozygous TT and heterozygous CT genotypes of rs10505477, as well as the GG and TG genotypes of rs6983267, were associated with risk of colorectal cancer.Our study provides summary evidence that common variants in the 8q24 are associated with risk of colorectal cancer in this large-scale research synopsis and meta-analysis. Further studies are needed to explore the exact role of the variants in the 8q24 involved in the etiology of colorectal cancer.

The polymorphisms of miRNA-binding site in MLH3 and ERCC1 were linked to the risk of colorectal cancer in a case-control study

Colorectal cancer (CRC), as a malignant tumor of lower digestive tract, has been found to have an increasing morbidity and mortality in China. It was particularly important to find some earlier biomarkers to predict the risk and prognosis. In this study, several polymorphisms on 3′UTR of three DNA repair genes including MLH3 rs10862, ERCC1 rs3212986, ERCC1 rs735482, ERCC1 rs2336219, and OGG1 rs1052133 were chosen by bioinformatics exploration, and then, a case–control study of 200 CRC cases and controls was performed. Furthermore, a dual‐luciferase assay was also carried out to certify whether the candidate miRNA can regulate its target gene and the selected SNPs have a valid effect on the target miRNA. Finally, both of ERCC1 rs3212986 and MLH3 rs108621 were shown to be associated with the risk of CRC. Comparing with rs3212986 CC genotype, AA was at a higher risk (OR = 3.079, 95% CI: 1.192–7.952). For MLH3 rs108621, comparing with TT genotype, CC and TC were at a higher risk of CRC in male (OR = 5.171, 95% CI: 1.009–26.494; OR = 1.904, 95% CI: 1.049–3.455). Interestingly, an analysis combining both ERCC1 rs3212986 and MLH3 rs108621 also showed an increased risk of CRC. In addition, a dual‐luciferase assay showed that miR‐193a‐3p could regulate MLH3, and the polymorphism rs108621 could alter the miR‐193a‐3p binding to MLH3. Therefore, MLH3 rs108621 may be associated with the risk of CRC due to the effect of miR‐193a‐3p on MLH3, which reminded the possibility as potential susceptibility biomarkers to predict the risk of CRC.

Association of rs6983267 at 8q24, HULC rs7763881 polymorphisms and serum lncRNAs CCAT2 and HULC with colorectal cancer in Egyptian patients

The impact of HULC rs7763881 on colorectal cancer (CRC) susceptibility is not yet known. Also, the biological function of the cancer-related rs6983267 remains unclear. We investigated the association of these SNPs with the risk of CRC and adenomatous polyps (AP), their correlation with CCAT2 and HULC expression, and the potential of serum CCAT2 and HULC as biomarkers for CRC. 120 CRC patients, 30 AP patients, and 96 healthy controls were included. Genotyping and serum lncRNAs were assayed by qPCR. Studied SNPs were not associated with AP susceptibility. rs6983267 GG was associated with increased CRC risk, whereas rs7763881 AC was protective. rs7763881 and rs6983267 CT haplotype was protective. Serum CCAT2 and HULC were upregulated in CRC and AP patients versus controls and discriminated these groups by ROC analysis. rs6983267 GG and rs7763881 AA patients demonstrated higher serum CCAT2 and HULC compared with GT/TT and AC, respectively. rs6983267 and serum HULC predicted CRC diagnosis among non-CRC groups (AP + controls) by multivariate analysis. Studied SNPs or serum long noncoding RNAs weren't correlated with nodal or distant metastasis. In conclusion, rs6983267 and rs7763881 are potential genetic markers of CRC predisposition and correlate with serum CCAT2 and HULC, two novel potential non-invasive diagnostic biomarkers for CRC.

A novel mechanism of lncRNA and miRNA interaction: CCAT2 regulates miR-145 expression by suppressing its maturation process in colon cancer cells

Background

Although both long and micro RNAs are emerging as important functional components in colorectal cancer (CRC) progression and metastasis, the mechanism of their interaction remains poorly understood. CCAT2 (Colon cancer-associated transcript-2), a long noncoding RNA (lncRNA), has been reported to be over-expressed in CRC and is found to promote tumor growth. miRNAs, a class of naturally occurring short RNAs negatively control the expression of target genes by cleaving mRNA or through translation repression. Recently, we reported that miR-145 and miR-21 cooperate to regulate colon cancer stem cell (CSC) proliferation and differentiation. Considering that CCAT2 is mainly located in the nucleus and miRNA maturation process begins in the nucleus, we hypothesize that CCAT2 selectively blocks miR-145 maturation process, resulting in decreased mature miR-145 affecting colon CSC proliferation and differentiation.

Methods

The levels of CCAT2 were manipulated by transfection of CCAT2 expression plasmid or knockdown by siRNA or by CRISPR/Cas9. Quantitative RT-PCR was performed to examine the expression of CCAT2 and pri-, pre- and mature miR-145/21. Fluorescence in situ hybridization (FISH) was used to visualize CCAT2 in the cells. In vitro processing of pri-miRNA-145 was performed using T7 RNA polymerase and recombinant human Dicer.

Results

We have observed that modulated expression of CCAT2 regulates the expression of miR-145 in colon cancer HCT-116 and HT-29 cells. Knockout of CCAT2 increases miR-145 and negatively regulates miR-21 in HCT-116 cells, impairs proliferation and differentiation. In contrast, stable up-regulation of CCAT2 decreases mature miR-145 and increases the expression of several CSC markers in colon cancer cells. We have also observed that CCAT2 is enriched in the nucleus and correlates with the expression of pre-miR-145 but not pre-miR-21 in HCT-116 cells. These results indicate CCAT2 selectively blocks miR-145 maturation by inhibiting pre-miR-145 export to cytoplasm. Further, we revealed that CCAT2 blocks cleavage of pre-miR-145 by Dicer in vitro.

Conclusions

Our results identify CCAT2 as a negative regulator of miRNA-145 biogenesis, and expose a novel mechanism of lncRNA-miRNA crosstalk.

Electronic supplementary material

The online version of this article (10.1186/s12943-017-0725-5) contains supplementary material, which is available to authorized users.

Japanese genome-wide association study identifies a significant colorectal cancer susceptibility locus at chromosome 10p14

Genome‐wide association studies are a powerful tool for searching for disease susceptibility loci. Several studies identifying single nucleotide polymorphisms (SNP) connected intimately to the onset of colorectal cancer (CRC) have been published, but there are few reports of genome‐wide association studies in Japan. To identify genetic variants that modify the risk of CRC oncogenesis, especially in the Japanese population, we performed a multi‐stage genome‐wide association study using a large number of samples: 1846 CRC cases and 2675 controls. We identified 4 SNP (rs7912831, rs4749812, rs7898455 and rs10905453) in chromosome region 10p14 associated with CRC; however, there are no coding or non‐coding genes within this region of fairly extensive linkage disequilibrium (a 500‐kb block) on 10p14. Our study revealed that the 10p14 locus is significantly correlated with susceptibility to CRC in the Japanese population, in accordance with the results of multiple studies in other races.

The rs6983267 SNP and long non-coding RNA CARLo-5 are associated with endometrial carcinoma

The single nucleotide polymorphism (SNP) rs6983267 and cancer-associated region long non-coding RNA (CARLo-5) are associated with various human cancers. This study aimed to investigate the expression of CARLo-5 in endometrial carcinoma (EC) and its relationship with clinicopathological features and patient survival. The association of the rs6983267 SNP with EC risk and its involvement in the regulation of CARLo-5 expression in EC were investigated. The rs6983267 SNP was genotyped by polymerase chain reaction (PCR) and ligase detection reaction in 543 EC patients and 584 controls. The expression of CARLo-5 in 108 EC tissues and 66 normal endometrial tissues (NETs) was determined using quantitative real-time PCR. The genotype and allele distributions of the rs6983267 SNP differed significantly between patients and controls. There was a significant correlation between the rs6983267 genotypes and lymph node metastasis of EC patients (P = 0.026). CARLo-5 expression was significantly higher in EC tissues than in NETs (P < 0.001) and significantly associated with FIGO stage (P = 0.029) and lymph node metastasis (P = 0.030). Patients with high CARLo-5 expression had significantly shorter overall survival than those with low CARLo-5 expression (P = 0.003). The rs6983267 genotype was significantly correlated with CARLo-5 expression (P < 0.05). In conclusion, CARLo-5 was identified as a pro-oncogenic lncRNA that may play an important role in EC progression and represent a prognostic marker for EC. The expression of CARLo-5 was significantly correlated with the rs6983267 genotype associated with increased susceptibility to EC. Environ. Mol. Mutagen. 57:508-515, 2016. © 2016 Wiley Periodicals, Inc.

8q24 Polymorphisms and Diabetes Mellitus Regulate Apolipoprotein A-IV in Colorectal Carcinogenesis

BACKGROUND

Here, we explored the genetic interactions between diabetes and oncogenic single-nucleotide polymorphisms (SNPs) that determine colorectal cancer (CRC) morbidity.

METHODS

8q24 rs6983267 polymorphism analysis and cDNA microarray were performed in 107 CRCs to identify the genes associated with diabetes and the oncogenic SNP. Then clinical significance of the gene was validated in 132 CRCs. Meta-analysis of microarray data and diabetic comorbidity was performed.

RESULTS

Of genes associated with a minor SNP allele at 8q24, diabetes, and MYC overexpression, apolipoprotein A-IV (ApoA-IV) was associated with oncogenesis and poor prognosis in CRC patients. Patients with high ApoA-IV expression showed significantly poorer prognosis by univariate and multivariate analysis. Meta-analysis revealed lipid metabolism was associated with ApoA-IV-related oncogenesis in diabetic patients.

CONCLUSIONS

Changes in lipid metabolism associated with aberrant expression of ApoA-IV were risks for CRC oncogenesis.

Allelic imbalance at an 8q24 oncogenic SNP is involved in activating MYC in human colorectal cancer

BACKGROUND

The rs6983267 at 8q24.21 has been established as a significant cancer-related single nucleotide polymorphism (SNP). The risk allele showed similarity to the binding site of transcription factor TCF4/LEF1 that activates transcription of MYC. However, little is known about the role of this SNP in increasing MYC activity in colorectal cancers (CRCs).

METHODS

The genotypes of rs6983267 in peripheral blood and primary cancers, MYC activity and copy number (CN) alteration were examined in 107 CRCs. Next, we plotted the number of cancers cell lines exhibiting specific G/T genotypes in 746 cancer cell lines of the Sanger Institute database. Then we validated the relationship between the 8q24 SNP status and clinicopathologic parameters in 68 CRCs with loss of heterozygosity (LOH).

RESULTS

The MYC module activity was activated by either transcription in the risk allele (G) or by amplification in the non-risk allele (T). Then, we confirmed that the CN amplification dominantly occurred in the non-risk allele, whereas CN neutral LOH, which indicated uniparental disomy (UPD) was more frequently observed for the risk allele. Finally, we confirmed that risk allele dominant cases, either by amplification or by UPD, indicated a more malignant clinical phenotype than non-risk allele dominant cases.

CONCLUSIONS

The development of CRC requires MYC activation through retention of the risk allele, or amplification of the non-risk allele at the oncogenic SNP in the site of primary tumor.

Common variation rs6983267 at 8q24.1 and risk of colorectal adenoma and cancer: evidence based on 31 studies

Genome-wide association studies have identified 8q24.21-rs6983267 as a new colorectal cancer (CRC) and colorectal adenoma (CRA) susceptibility locus in populations of European descent. Since then, the relationship between 8q24.21-rs6983267 and CRC/CRA has been reported in various ethnic groups; however, these studies have yielded inconsistent results. To investigate this inconsistency and derive a more precise estimation of the relationship, we conducted a meta-analysis of 31 studies, including 51,293 cases and 58,962 controls for CRC, and 8,148 cases and 17,065 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.18 (95% CI, 1.16-1.21; P < 10(-5)) and 1.17 (95% CI, 1.11-1.23; P < 10(-5)) for CRA. Significant results were observed using dominant or recessive genetic model for the polymorphism. In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians and Caucasian populations; while no significant associations were detected among African Americans. After stratifying by sample size and control source, significant associations were also obtained. This meta-analysis suggests that the 8q24.21-rs6983267 polymorphism is associated with CRC/CRA susceptibility, but these associations vary in different ethnic populations.

The rs6983267 SNP is associated with MYC transcription efficiency, which promotes progression and worsens prognosis of colorectal cancer

BACKGROUND

The oncogenic single nucleotide polymorphism rs6983267, located on 8q24.21, may affect copy number aberrations and/or expression profiles in colorectal cancer (CRC). We investigated the role of this single nucleotide polymorphism in the clinical outcome of CRC.

METHODS

Array comparative genomic hybridization (aCGH) and oligomicroarrays were performed on cancer cells from 157 primary CRC tissues. Expression profiles were analyzed by means of extraction expression module (EEM) analyses. Mutations in TP53, KRAS, and BRAF and microsatellite instability were also examined in 107 of the 157 cases.

RESULTS

aCGH analysis revealed two clusters; more frequent genomic copy number alteration (CNA) was observed in the 89 cases in cluster B than in the 18 cases in cluster A. The average CNA was higher in samples containing the major allele (GT/TT) of rs6983267 than in those containing the minor allele (GG). Additionally, MYC expression was the highest in samples containing the GG allele (n = 18), followed by the GT and TT alleles (n = 41 and 48, respectively). EEM analysis revealed dominant up-regulation of MYC in samples containing the minor allele. Moreover, the presence of the minor allele in a MYC-positive, CNA-negative context predicted a poorer prognosis than the presence of the major allele in a MYC-negative, CNA-positive context in CRC.

CONCLUSIONS

The presence of the minor allele of rs6983267 at 8q24.21 worsened the prognosis of CRC through up-regulation of MYC transcription. Furthermore, progression of CRC may require global CNA in the presence of the major allele and with lack of MYC transcription.