Jianqiang Cai

Risk of Genome-Wide Association Study–Identified Genetic Variants for Colorectal Cancer in a Chinese Population

Background: Recent genome-wide association studies have identified 10 single nucleotide polymorphisms (SNP) associated with colorectal cancer (CRC) in Caucasians. This study evaluated the effects of these newly identified SNPs in a Chinese population. Methods: We assessed the associations of these 10 SNPs with CRC in a case-control study that consisted of 2,124 cases and 2,124 controls. Odds ratios (OR) and 95% confidence intervals were computed by logistic regression, and cumulative effect of risk genotypes were also calculated. Results: We found that only five SNPs (rs6983267, rs4939827, rs10795668, rs3802842, and rs961253) were significantly associated with risk of CRC in our study population in the same direction as reported by previous genome-wide association studies, with the ORs ranging from 1.11 to 2.96. A cumulative effect was observed with the ORs being gradually elevated with increasing number of risk genotypes (Ptrend = 1.32 × 10−21), and patients carrying ≥4 risk genotypes had 3.25-fold increased CRC risk (95% confidence interval, 2.24-4.72) compared with patients carrying no risk genotype. Furthermore, we found that rs10795668 was associated with increased risk only in rectal cancer but not colon cancer, and rs3802842 was also significantly associated with advanced stages of CRC. Conclusions: These results suggest that rs6983267, rs4939827, rs10795668, rs3802842, and rs961253 SNPs are associated with the risk of CRC in the Chinese population individually and jointly. Impact: Our results provide new insights into colorectal tumorigenesis and have potential implications in early detection and target treatment of CRC in non-Western populations. Cancer Epidemiol Biomarkers Prev; 19(7); 1855–61. ©2010 AACR.

Evidence of associations of APOBEC3B gene deletion with susceptibility to persistent HBV infection and hepatocellular carcinoma.

APOBEC3s are a family of cytidine deaminases involved in innate cellular immunity against virus including hepatitis B virus (HBV). A germline deletion across APOBEC3A and APOBEC3B (A3B) genes results in complete removal of the A3B coding region and destroys A3B expression. To determine whether this deletion affects susceptibility to HBV infection and HBV-related hepatocellular carcinoma (HCC), A3B genotypes were analyzed in 1124 individuals with HCC, 510 individuals with persistent HBV infection and 826 healthy controls and the association was estimated by odds ratio (OR) and 95% confidence interval (CI) computed by logistic regression. We also examined the effects of A3B on HBV genome hypermutation and replication in HCC cells. We observed a significantly higher frequency of the A3B deletion allele in persistent HBV carriers (33.3%; P = 0.0015) and HCC patients (37.9%; P = 1.28 × 10(-11)) compared with that in controls (27.5%). An increased risk for persistent HBV infection (OR = 1.35, 95% CI: 1.03-1.77) and HCC development (OR = 1.90, 95% CI: 1.58-2.28) was associated with at least one A3B deletion allele (+/- or -/- genotype) compared with the +/+ genotype. Transfection of A3B in HepG2 cells caused a substantial reduction of HBV RNA levels and G → A hypermutation in the HBV genome. Interestingly, a cytidine deaminase null mutant of A3B (E255A) also inhibited HBV RNA production although it was unable to edit HBV. These results suggest that the deletion of A3B attenuates HBV clearance, which in turn may result in persistent HBV infection and increased risk for developing HCC. Further studies are needed to verify our findings.

Frequent Epigenetic Silencing of the Folate-Metabolising Gene Cystathionine-Beta-Synthase in Gastrointestinal Cancer

Background Both gastric and colorectal cancers (CRC) are the most frequently occurring malignancies worldwide with the overall survival of these patients remains unsatisfied. Identification of tumor suppressor genes (TSG) silenced by promoter CpG methylation uncovers mechanisms of tumorigenesis and identifies new epigenetic biomarkers for early cancer detection and prognosis assessment. Cystathionine-beta-synthase (CBS) functions in the folate metabolism pathway, which is intricately linked to methylation of genomic DNA. Dysregulation of DNA methylation contributes substantially to cancer development. Methodology/Principal Findings To identify potential TSGs silenced by aberrant promoter methylation in CRC, we analyzed tumor and adjacent tissues from CRC cases using the Illumina Human Methylation45 BeadChip. We identified hypermethylation of the CBS gene in CRC samples, compared to adjacent tissues. Methylation and decreased mRNA expression of CBS were detected in most CRC cell lines by methylation-specific PCR and semiquantitative RT-PCR, as well as in gastric cancer. Treatment with 5-aza-2-deoxycytidine and/or trichostatin A reversed methylation and restored CBS mRNA expression indicating a direct effect. Aberrant methylation was further detected in 31% of primary CRCs (29 of 96) and 55% of gastric tumors (11 of 20). In contrast, methylation was seldom found in normal tissues adjacent to the tumor. CBS methylation was associated with KRAS mutations in primary CRCs (Pu200a=u200a0.04, by χ2-test). However, no association was found between CBS methylation or KRAS mutations with cancer relapse/metastasis in Stage II CRC patients. Conclusion A novel finding from this study is that the folate metabolism enzyme CBS mRNA levels are frequently downregulated through CpG methylation of the CBS gene in gastric cancer and CRC, suggesting that CBS functions as a tumor suppressor gene. These findings warrant further study of CBS as an epigenetic biomarker for molecular diagnosis of gastrointestinal cancers.

Variants Identified by Hepatocellular Carcinoma and Chronic Hepatitis B Virus Infection Susceptibility GWAS Associated with Survival in HBV-Related Hepatocellular Carcinoma

Recent genome-wide association studies (GWAS) have identified several common susceptibility loci associated with the risk of hepatocellular carcinoma (HCC) or chronic hepatitis B infection (CHB). However, the relationship between these genetic variants and survival of patients with hepatitis B virus (HBV)-related HCC is still unknown. In this study, 22 single nucleotide polymorphisms (SNPs) were genotyped among 330 HBV-related HCC patients using the MassARRAY system from Sequenom. Cox proportional hazards regression was used to examine the effects of genotype on survival time under an additive model with age, sex, smoking status and clinical stage as covariates. We identified four SNPs on 6p21 (rs1419881 T>C, rs7453920 G>A,rs3997872 G>A and rs7768538 T>C), and two SNPs on 8p12 (rs2275959 C>T and rs7821974 C>T) significantly associated with survival time of HBV-related HCC patients. Our results suggest that HCC or CHB susceptibility loci might also affect the prognosis of patients with HBV-related HCC.

Genetic Features of Aflatoxin-Associated Hepatocellular Carcinoma

BACKGROUND & AIMSnDietary exposure to aflatoxin is an important risk factor for hepatocellular carcinoma (HCC). However, little is known about the genomic features and mutations of aflatoxin-associated HCCs compared with HCCs not associated with aflatoxin exposure. We investigated the genetic features of aflatoxin-associated HCC that can be used to differentiate them from HCCs not associated with this carcinogen.nnnMETHODSnWe obtained HCC tumor tissues and matched non-tumor liver tissues from 49 patients, collected from 1990 through 2016, at the Qidong Liver Cancer Hospital Institute in China-a high-risk region for aflatoxin exposure (38.2% of food samples test positive for aflatoxin contamination). Somatic variants were identified using GATK Best Practices Pipeline. We validated part of the mutations from whole-genome sequencing and whole-exome sequencing by Sanger sequencing. We also analyzed genomes of 1072 HCCs, obtained from 5 datasets from China, the United States, France, and Japan. Mutations in 49 aflatoxin-associated HCCs and 1072 HCCs from other regions were analyzed using the Wellcome Trust Sanger Institute mutational signatures framework with non-negative matrix factorization. The mutation landscape and mutational signatures from the aflatoxin-associated HCC and HCC samples from general population were compared. We identified genetic features of aflatoxin-associated HCC, and used these to identify aflatoxin-associated HCCs in datasets from other regions. Tumor samples were analyzed by immunohistochemistry to determine microvessel density and levels of CD34 and CD274 (PD-L1).nnnRESULTSnAflatoxin-associated HCCs frequently contained C>A transversions, the sequence motif GCN, and strand bias. In addition to previously reported mutations in TP53, we found frequent mutations in the adhesion G protein-coupled receptor B1 gene (ADGRB1), which were associated with increased capillary density of tumor tissue. Aflatoxin-associated HCC tissues contained high-level potential mutation-associated neoantigens, and many infiltrating lymphocytes and tumors cells that expressed PD-L1, compared to HCCs not associated with aflatoxin. Of the HCCs from China, 9.8% contained the aflatoxin-associated genetic features, whereas 0.4%-3.5% of HCCs from other regions contained these genetic features.nnnCONCLUSIONSnWe identified specific genetic and mutation features of HCCs associated with aflatoxin exposure, including mutations in ADGRB1, compared to HCCs from general populations. We associated these mutations with increased vascularization and expression of PD-L1 in HCC tissues. These findings might be used to identify patients with HCC due to aflatoxin exposure, and select therapies.

Evaluation of seven different staging systems for alpha-fetoprotein expression in hepatocellular carcinoma after hepatectomy

Alpha-fetoprotein (AFP) represents the most important biomarker for hepatocellular carcinoma (HCC). The aim of this study was to identify the optimal staging system to predict the survival of AFP-negative and AFP-positive patients. This study analyzed the data of 431 AFP-negative HCC patients who had previously undergone surgery and 471 AFP-positive HCC candidates. Kaplan–Meier (K-M) survival estimates were plotted, and the P values were assessed using log-rank tests. The Akaike information criterion (AIC) was calculated using the results of a Cox’s regression to compare the overall assessment of the seven different staging systems. The AFP-positive group displayed characteristics of poor tumor biological behavior (tumor multiplicity [Pu2009=u20090.032], low grade differentiation [Pu2009=u20090.000] and carcinoma cell embolus [Pu2009=u20090.031]), poor liver function (Child–Pugh B classification [Pu2009=u20090.003], abnormal prothrombin time activity [Pu2009=u20090.037] and moderate/severe cirrhosis [Pu2009=u20090.000]) and increased operative difficulties (transfusion; Pu2009=u20090.001). TNM7th staging showed the lowest AIC value (1,279.528) for the AFP-negative group, while the Barcelona Clinic Liver Cancer (BCLC) staging system revealed the lowest AIC value (1,991.233) for the AFP-positive group. In conclusion, among the seven favorable staging systems, BCLC staging was superior for the AFP-positive group, while the TNM7th was a more appropriate staging model for the AFP-negative group.

Prognostic factors of carcinoma of the ampulla of Vater after surgery

The purpose of this study was to investigate the prognostic factors of carcinoma of the ampulla of Vater (CAV) after surgery. The clinicopathological factors related to the recurrence and prognosis of 162 CAV patients after surgical resection were retrospectively analyzed using univariate and multivariate methods. The in-hospital mortality rate was 4.32xa0% and the 5-year disease-free survival and overall survival of the 162 subjects were 55.1 and 51.7xa0%, respectively. Univariate analysis revealed that an advanced T stage (Pu2009=u20090.002), lymph nodal metastasis (Pu2009=u20090.002), poor differentiation (Pu2009=u20090.006), tumor size (Pu2009=u20090.033), tumor stage (Pu2009=u20090.001), carbohydrate antigen (CA) 199 serum levels (Pu2009=u20090.000), pancreatic invasion (Pu2009=u20090.001), chemotherapy/radiation therapy (Pu2009=u20090.006), and jaundice (Pu2009=u20090.012) were factors that significantly affected the prognosis of CAV. Multivariate analysis showed that the pancreatic invasion (Pu2009=u20090.009), lymph nodal metastasis (Pu2009=u20090.009), and increased CA199 serum level (Pu2009=u20090.001) were independent risk factors of recurrence. The pancreatic invasion, lymph nodal metastasis, and increased CA199 serum level are key prognostic factors of CAV after surgery.

RIPK1 Binds MCU to Mediate Induction of Mitochondrial Ca2+ Uptake and Promotes Colorectal Oncogenesis

The receptor-interacting protein kinase 1 (RIPK1) is an essential signaling molecule in pathways for cell survival, apoptosis, and necroptosis. We report here that RIPK1 is upregulated in human colorectal cancer and promotes cell proliferation when overexpressed in a colon cancer cell line. RIPK1 interacts with mitochondrial Ca2+ uniporter (MCU) to promote proliferation by increasing mitochondrial Ca2+ uptake and energy metabolism. The ubiquitination site of RIPK1 (RIPK1-K377) was critical for this interaction with MCU and function in promoting cell proliferation. These findings identify the RIPK1-MCU pathway as a promising target to treat colorectal cancer.Significance: RIPK1-mediated cell proliferation through MCU is a central mechanism underlying colorectal cancer progression and may prove to be an important therapeutic target for colorectal cancer treatment. Cancer Res; 78(11); 2876-85. ©2018 AACR.

Interaction of margin status and tumour burden determines survival after resection of colorectal liver metastases: A retrospective cohort study

PURPOSEnWe sought to determine the impact of surgical margin status on overall survival (OS) and recurrence pattern stratified by tumor burden.nnnMATERIALS AND METHODSnData were collected from patients undergoing resection for colorectal liver metastases (CRLM). Tumor burden was calculated according to a newly proposed Tumor Burden Score (TBS) system, defined as the distance from the origin on a Cartesian plane that incorporated maximum tumor size and number of liver lesions. Patients were divided into low tumor burden group and high tumor burden group accordingly, and the impact of resection margin on overall survival was examined.nnnRESULTSnA total of 286 patients were available, among which R1 resection was observed in 88 patients. The median TBS for the entire cohort was 3.84. Metastases in the R1 group were characterized by more advanced disease and more complex resections. Compared with a R0 resection, a R1 resection offered an lower 5-year overall survival rate (46.8% vs. 22.1%, pxa0=xa00.001). Multivariate analysis identified R1 resection (pxa0=xa00.03), high TBS (pxa0=xa00.002), lymph nodes metastases (pxa0=xa00.003) and lymphovascular invasion (pxa0=xa00.03) of the primary colorectal tumor as the factors independently associated with worse survival. The survival benefit associated with negative margins was greater in patients with low TBS (55.7% vs. 21.7%, pxa0=xa00.021) than in patients with high TBS (31.8% vs. 24.5%, pxa0=xa00.116). R1 resection was associated with an increased true margin recurrence rate in patients with low TBS (32.3% vs. 13.4%; pxa0=xa00.014) and an increased risk of new intrahepatic metastases in patients with high TBS (43.9% vs. 26.7%; pxa0=xa00.034).nnnCONCLUSIONSnNegative margin is an important determinant of survival. The impact of positive margins is more pronounced in patients with low tumor burden.

Contribution of hepatitis B virus and hepatitis C virus to liver cancer in China north areas: Experience of the Chinese National Cancer Center

INTRODUCTIONnThe aim of this study was to determine the impact of hepatitis B virus (HBV) and/or hepatitis C virus (HCV) on primary liver cancer (PLC) in China north areas.nnnMETHODSnA total of 2172 histologically confirmed PLC patients attending the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences during the period January 1, 2003 to December 31, 2014 were enrolled. Details of hepatitis B surface antigen (HBsAg), antibodies against HBV core antigen (anti-HBc), and antibodies against HCV (anti-HCV) status were recorded. Sequencing of the HBV PreS-S gene and the C/E1 and NS5B fragments of HCV was performed and the genotypes were analyzed for some of the patients with hepatocellular carcinoma (HCC).nnnRESULTSnAmong the 2172 histologically confirmed PLC cases, 1823 (83.9%) had HCC and 238 (11.0%) had intrahepatic cholangiocarcinoma (iCCA). Among HCC cases, HBV infection alone, indicated by HBsAg-neg/pos+anti-HBc-pos, was found in 1567 (86.0%) cases; of these, 18.2% (331/1823) were HBsAg-neg+anti-HBc-pos. Serum HBV-DNA was detectable in 70% of HBsAg-neg+anti-HBc-pos HCC cases. The dominant HBV genotype was HBV-C2 (94.4%). HCV infection alone, indicated by anti-HCV-pos, was found in 2.5% (46/1823) of cases; HCV-1b (72.1%) was the dominant genotype. HBV+HCV co-infection markers were found in 6.7% (122/1823) of cases. Only 88 (4.8%) cases had no HBV and no HCV markers. Among the 238 iCCA cases, 54 (22.7%) were HBsAg-pos+anti-HBc-pos; none was anti-HCV-pos alone.nnnCONCLUSIONSnHBV remains the major contributor to PLC in China north areas Individuals with occult HBV infection should not be ignored in liver cancer screening.