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Background: Genome-wide association studies (GWAS) have identified dozens of loci associated with colon and rectal adenocarcinoma risk. As tissue-specific super-enhancers (SE) play important roles in tumorigenesis, we systematically investigate SEs and inner variants in established GWAS loci to decipher the underlying biological mechanisms. Methods: Through a comprehensive bioinformatics analysis on multi-omics data, we screen potential single-nucleotide polymorphisms (SNP) in cancer-specific SEs, and then subject them to a two-stage case-control study containing 4,929 cases and 7,083 controls from the Chinese population. A series of functional assays, including reporter gene assays, electrophoretic mobility shift assays (EMSA), CRISPR-Cas9 genome editing, chromosome conformation capture (3C) assays, and cell proliferation experiments, are performed to characterize the variant's molecular consequence and target genes. Results: The SNP rs11064124 in 12p13.31 is found significantly associated with the risk of colon and rectal adenocarcinoma with an odds ratio (OR) of 0.87 [95% confidence interval (CI), 0.82-0.92, P = 8.67E-06]. The protective rs11064124-G weakens the binding affinity with vitamin D receptor (VDR) and increases the enhancer's activity and interactions with two target genes' promoters, thus coactivating the transcription of CD9 and PLEKHG6, which are both putative tumor suppressor genes for colon and rectal adenocarcinoma. Conclusions: Our integrative study highlights an SE polymorphism rs11064124 and two susceptibility genes CD9 and PLEKHG6 in 12p13.31 for colon and rectal adenocarcinoma. Impact: These findings suggest a novel insight for genetic pathogenesis of colon and rectal adenocarcinoma, involving transcriptional coactivation of diverse susceptibility genes via the SE element as a gene regulation hub. [ABSTRACT FROM AUTHOR]

Background: Telomere dysfunction triggers cellular senescence and constitutes a driving force for cancer initiation. Genetic variants in genes involved in telomere maintenance may contribute to colorectal cancer susceptibility. Methods: In this study, we firstly captured germline mutations in 192 patients with colorectal cancer by sequencing the coding regions of 13 core components implicated in telomere biology. Five potential functional variants were then genotyped and assessed in a case-control set with 3,761 colorectal cancer cases and 3,839 healthy controls. The promising association was replicated in additional 6,765 cases and 6,906 controls. Functional experiments were used to further clarify the potential function of the significant variant and uncover the underlying mechanism in colorectal cancer development. Results: The two-stage association studies showed that a rare missense variant rs149418249 (c.C1520T and p.P507L) in the 11th exon of TPP1 (also known as ACD, gene ID 65057) was significantly associated with colorectal cancer risk with the ORs being 2.90 [95% confidence interval (CI), 1.04-8.07; P = 0.041], 2.50 (95% CI, 1.04-6.04; P = 0.042), and 2.66 (95% CI, 1.36-5.18; P = 0.004) in discovery, replication, and the combined samples, respectively. Further functional annotation indicated that the TPP1 P507L substitution interrupted TPP1-TIN2 interaction, impaired telomerase processivity, and shortened telomere length, which subsequently facilitated cell proliferation and promoted colorectal cancer development. Conclusions: A rare variant P507L in TPP1 confers increased risk of colorectal cancer through interrupting TPP1-TIN2 interaction, impairing telomerase processivity, and shrinking telomere length. Impact: These findings emphasize the important role of telomere dysfunction in colorectal cancer development, and provide new insights about the prevention of this type of cancer. [ABSTRACT FROM AUTHOR]

The gender disparity observed in the incidence of hepatocellular carcinoma (HCC) suggests an important role of estrogens in HCC pathogenesis. In this study, we conducted a case-control study to investigate whether breast cancer riskassociated single nucleotide polymorphisms (SNPs) located at estrogens loci identified by genome-wide association studies (GWASs) also predispose to HCC in a Chinese population. Three candidate SNPs at 6q25.1 were genotyped in 2025 HCC cases and 2032 healthy controls. Differential expression analyses and expression quantitative trait loci (eQTL) analyses were conducted to further explore the potential function of significant SNPs and genes they reside in. Two of the three candidate SNPs (rs9383951 and rs9485372) were observed to be significantly associated with HCC risk. Under a dominant model, the odds ratios (OR) for rs9383951 and rs9485372 were 1.28 (95% CI: 1.10-1.49, P = 0.002) and 1.34 (95% CI: 1.17-1.53, P = 2.75 × 10-5), respectively. We also found a significant accumulative effect of these two SNPs and there was a gradual increase in OR with a greater number of hazard genotypes. Moreover, the association between rs9383951 and HCC risk was specific in males. Lower ESR1 and TAB2 expressions were investigated in hepatic tumor tissues than adjacent normal tissues. We found a significant association between rs9383951 and ESR1 expression (P = 0.047). Besides, ESR1 expression was significantly correlated with the expression of TAB2. Taken together, our study identified two genetic variants at 6q25.1 newly associated with HCC risk, suggesting ESR1 and estrogen signaling may play a role in mediating susceptibility to HCC in Chinese population. [ABSTRACT FROM AUTHOR]