Alternative splicing (AS) is a widespread process that increases structural transcript variation and proteome diversity. Aberrant splicing patterns are frequently observed in cancer initiation, progress, prognosis and therapy. Increasing evidence has demonstrated that AS events could undergo modulation by genetic variants. The identification of splicing quantitative trait loci (sQTLs), genetic variants that affect AS events, might represent an important step toward fully understanding the contribution of genetic variants in disease development. However, no database has yet been developed to systematically analyze sQTLs across multiple cancer types. Using genotype data from The Cancer Genome Atlas and corresponding AS values calculated by TCGASpliceSeq, we developed a computational pipeline to identify sQTLs from 9 026 tumor samples in 33 cancer types. We totally identified 4 599 598 sQTLs across all cancer types. We further performed survival analyses and identified 17 072 sQTLs associated with patient overall survival times. Furthermore, using genome-wide association study (GWAS) catalog data, we identified 1 180 132 sQTLs overlapping with known GWAS linkage disequilibrium regions. Finally, we constructed a user-friendly database, CancerSplicingQTL (http://www.cancersplicingqtl-hust.com/) for users to conveniently browse, search and download data of interest. This database provides an informative sQTL resource for further characterizing the potential functional roles of SNPs that control transcript isoforms in human cancer.

Protein post-translational modifications (PTMs), including phosphorylation, ubiquitination, methylation, acetylation, glycosylation et al, are very important biological processes. PTM changes in some critical genes, which may be induced by base-pair substitution, are shown to affect the risk of diseases. Recently, large-scale exome-wide association studies found that missense single nucleotide polymorphisms (SNPs) play an important role in the susceptibility for complex diseases or traits. One of the functional mechanisms of missense SNPs is that they may affect PTMs and leads to a protein dysfunction and its downstream signaling pathway disorder. Here, we constructed a database named AWESOME (A Website Exhibits SNP On Modification Event, http://www.awesome-hust.com), which is an interactive web-based analysis tool that systematically evaluates the role of SNPs on nearly all kinds of PTMs based on 20 available tools. We also provided a well-designed scoring system to compare the performance of different PTM prediction tools and help users to get a better interpretation of results. Users can search SNPs, genes or position of interest, filter with specific modifications or prediction methods, to get a comprehensive PTM change induced by SNPs. In summary, our database provides a convenient way to detect PTM-related SNPs, which may potentially be pathogenic factors or therapeutic targets.

Germline coding variants have not been systematically investigated for pancreatic ductal adenocarcinoma (PDAC). Here we report an exome-wide investigation using the Illumina Human Exome Beadchip with 943 PDAC cases and 3908 controls in the Chinese population, followed by two independent replicate samples including 2142 cases and 4697 controls. We identify three low-frequency missense variants associated with the PDAC risk: rs34309238 in PKN1 (OR = 1.77, 95% CI: 1.48–2.12, P = 5.35 × 10−10), rs2242241 in DOK2 (OR = 1.85, 95% CI: 1.50–2.27, P = 4.34 × 10−9), and rs183117027 in APOB (OR = 2.34, 95% CI: 1.72–3.16, P = 4.21 × 10−8). Functional analyses show that the PKN1 rs34309238 variant significantly increases the level of phosphorylated PKN1 and thus enhances PDAC cells' proliferation by phosphorylating and activating the FAK/PI3K/AKT pathway. These findings highlight the significance of coding variants in the development of PDAC and provide more insights into the prevention of this disease.

Genome-wide association studies (GWAS) of colorectal cancer have identified several common susceptible variants in gene regulatory regions. However, low-frequency or rare coding risk variants have not been systematically investigated in patients with colorectal cancer from Chinese populations. In this study, we performed an exome-wide association analysis with 1,062 patients with colorectal cancer and 2,184 controls from a Chinese population. Promising associations were further replicated in two replication sets: replication stage I with 2,478 cases and 3,880 controls, and replication stage II with 3,761 cases and 4,058 controls. We identified two variants significantly associated with colorectal cancer risk: a novel rare missense variant in TCF7L2 [rs138649767, OR = 2.08, 95% confidence interval (CI): 1.69–2.57, P = 5.66 × 10−12] and a previous European GWAS-identified 3′-UTR variant in ATF1 (rs11169571, OR = 1.18, 95% CI: 1.13–1.24, P = 1.65 × 10−12). We found a significant interaction between the TCF7L2 missense variant rs138649767 and a previous GWAS-identified regulatory variant rs6983267 in the MYC enhancer (Pinteraction = 0.0002). Functional analysis of this variant revealed that TCF7L2 with rs138649767-A allele harbored the ability to activate the MYC enhancer with rs6983267-G allele and enhance colorectal cancer cell proliferation. In addition, the ATF1 rs11169571 variant significantly correlated with ATF1 expression by affecting hsa-miR-1283 and hsa-miR-520d-5p binding. Further ChIP-seq and gene coexpression analyses showed that oncogenes NRAS and BRAF were activated by ATF1 in colorectal cancer. These results widen our understanding of the molecular basis of colorectal cancer risk and provide insight into pathways that might be targeted to prevent colorectal cancer. Significance: Exome-wide association analysis identifies a rare missense variant in TCF7L2 and a common regulatory variant in ATF1 as susceptibility factors of colorectal cancer.

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.