Cuiju Tang

Overexpression of Yes-associated protein confers doxorubicin resistance in hepatocellullar carcinoma.

Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies worldwide and is highly resistant to chemotherapy. Yes-associated protein (YAP) is the downstream effector of the Hippo signaling pathway, which is frequently overexpressed in many types of cancers. Amplification of the YAP gene and overexpression of YAP in HCC have previously been reported to contribute to hepatocyte malignant transformation and tumor progression. In this study, we aimed to investigate the potential role of YAP in HCC chemoresistance. Overexpression of YAP resulted in resistance against doxorubicin-induced apoptosis in HCC cell lines, whereas suppression of the endogenous YAP expression by RNA interference demonstrated the reverse effect. Western blotting revealed that, following exposure to doxorubicin, YAP-overexpressing cells exhibited decreased cleaved PARP, increased phosphorylation of Akt and ERK1/2, and elevated Bcl-xL expression in comparison to the vector control. Inhibition of YAP expression sensitized HCC cells to doxorubicin, by exhibiting increased cleaved PARP, decreased levels of phosphorylated Akt, phosphorylated ERK1/2 and Bcl-xL expression. In addition, pretreatment with the MEK1/2 inhibitor U0126 but not the PI3-K inhibitor LY294002 significantly enhanced doxorubicin-induced apoptosis and decreased Bcl-xL expression in YAP-overexpressing HCC cells. Our data provide evidence that overexpression of YAP plays an important role in conferring doxorubicin resistance to HCC, which is at least partially mediated by YAP-induced activation of the MAP kinase pathway. Targeting YAP may be a promising adjunct for overcoming doxorubicin resistance in HCC.

Common genetic variation in ETV6 is associated with colorectal cancer susceptibility

Genome-wide association studies (GWASs) have identified multiple susceptibility loci for colorectal cancer, but much of heritability remains unexplained. To identify additional susceptibility loci for colorectal cancer, here we perform a GWAS in 1,023 cases and 1,306 controls and replicate the findings in seven independent samples from China, comprising 5,317 cases and 6,887 controls. We find a variant at 12p13.2 associated with colorectal cancer risk (rs2238126 in ETV6, P=2.67 × 10−10). We replicate this association in an additional 1,046 cases and 1,076 controls of European ancestry (P=0.034). The G allele of rs2238126 confers earlier age at onset of colorectal cancer (P=1.98 × 10−6) and reduces the binding affinity of transcriptional enhancer MAX. The mRNA level of ETV6 is significantly lower in colorectal tumours than in paired normal tissues. Our findings highlight the potential importance of genetic variation in ETV6 conferring susceptibility to colorectal cancer.

Frequent KIT Mutations in Human Gastrointestinal Stromal Tumors

Identifying gene mutations in individual tumors is critical to improve the efficacy of cancer therapy by matching targeted drugs to specific mutations. Gastrointestinal stromal tumors (GIST) are stromal or mesenchymal subepithelial neoplasms affecting the gastrointestinal tract and frequently contain activating gene mutations in either KIT or platelet-derived growth factor A (PDGFRA). Although GIST is highly responsive to several selective tyrosine kinase inhibitors, combined use of inhibitors targeting other mutations is needed to further prolong survival in patients with GIST. In this study, we aim to screen and identify genetic mutations in GIST for targeted therapy using the new Ion Torrent next-generation sequencing platform. Utilizing the Ion Ampliseq Cancer Panel, we sequenced 737 loci from 45 cancer-related genes using DNA extracted from formalin-fixed and paraffin-embedded (FFPE) samples of 121 human gastrointestinal stromal tumors, set up stringent parameters for reliable variant calling by filtering out potential raw base calling errors, and identified frequent mutations in the KIT gene. This study demonstrates the utility of using Ion Torrent sequencing to efficiently identify human cancer mutations. This may provide a molecular basis for clinically developing new drugs targeting these gene mutations for GIST therapy.

Genetic variant in 8q24 is associated with prognosis for gastric cancer in a Chinese population.

Single nucleotide polymorphisms (SNPs) located in long noncoding RNA CASC8 gene may influence the process of splicing and stability of messenger RNA conformation, resulting in the modification of its interacting partners. Genome‐wide association studies have identified the SNP rs10505477 and SNP rs1562430 in CASC8 were associated with risk of the colorectal cancer (CRC) and breast cancer, respectively.

Comparison of the Efficacy and Safety of S-1-Based and Capecitabine-Based Regimens in Gastrointestinal Cancer: A Meta-Analysis

Purpose Oral fluoropyrimidine (S-1, capecitabine) has been considered as an important part of various regimens. We aimed to evaluate the efficacy and safety of S-1-based therapy versus capecitabine -based therapy in gastrointestinal cancers. Methods Eligible studies were identified from Pubmed, EMBASE. Additionally, abstracts presented at American Society of Clinical Oncology (ASCO) conferences held between 2000 and 2013 were searched to identify relevant clinical trials. The outcome included overall survival (OS), progression-free survival (PFS), overall response rate (ORR), disease control rate (DCR) and advent events. Results A total of 6 studies (4 RCTs and 2 retrospective analysis studies) containing 790 participants were included in this meta-analysis, including 401 patients in the S-1-based group and 389 patients in the capecitabine-based group. Results of our meta-analysis indicated that S-1-based and capecitabine-based regimens showed very similar efficacy in terms of PFS (HR 0.92, 95% CI 0.78–1.09, P = 0.360), OS (HR 1.01, 95% CI 0.84–1.21, P = 0.949), ORR (HR 1.04, 95% CI 0.87–1.25, P = 0.683) and DCR (HR 1.02, 95% CI 0.94–1.10, P = 0.639). There was also no significant difference in toxicity between regimens other than mild more hand–foot syndrome in capecitabine-based regimens. Conclusion Both the S-1-based and capecitabine-based regimens are equally active and well tolerated, and have the potential of backbone chemotherapy regimen in further studies of gastrointestinal cancers.

Increased risk of developing digestive tract cancer in subjects carrying the PLCE1 rs2274223 A>G polymorphism: evidence from a meta-analysis.

Background To date, the association between phospholipase C epsilon 1 (PLCE1) rs2274223 A>G and risk of digestive tract cancer (DTC) remains inconclusive. To derive a more precise estimation of the association, we conducted a meta-analysis on all eligible case–control studies involving 8281 cases and 10,532 controls. Methods A comprehensive search was conducted to identify all eligible studies of PLCE1 rs2274223 polymorphism and digestive tract cancer risk. The pooled odds ratio (OR) and the 95% confidence interval (95% CI) were calculated using a fixed or random effect model. Heterogeneity, publication bias, and sensitivity analysis were also explored. Results Overall, the PLCE1 rs2274223 A>G polymorphism was associated with risk of DTC in all genetic models (GA vs. AA: OR = 1.21, 95% CI = 1.14–1.29, P<0.001; GG vs. AA: OR = 1.30, 95% CI = 1.06–1.60, P = 0.012; GG/GA vs. AA: OR = 1.20, 95% CI = 1.10–1.32, P<0.001; GG vs. GA/AA: OR = 1.21, 95% CI = 1.01–1.46, P = 0.040). The recessive model did not reach statistically significance when the P values were Bonferroni corrected to 0.0125. In the stratified analysis by cancer type, ethnicity, and source of controls, significantly increased risk was observed for esophagus cancer, Asians in three genetic models (heterozygote comparison, homozygote comparison and dominant model), population-based studies in all genetic models, and for gastric cancer in the heterozygote comparison and dominant model after Bonferroni correction. However, in the subsite of gastric cancer, no significant association was found either in cardia or non-cardia gastric cancer. Conclusion Our study indicated that PLCE1 rs2274223 A>G polymorphism was significantly associated with increased risk of DTC, especially among Asian populations. Due to some minor limitations, our findings should be confirmed in further studies.

A Genetic Polymorphism in TOX3 Is Associated with Survival of Gastric Cancer in a Chinese Population

Purpose Recently, genetic polymorphism (rs3803662C>T) in TOX3 was reported to induce the risk of breast cancer. In this study, we hypothesized that rs3803662 could influence gastric cancer survival outcomes. Methods With multiplex SNaPshot method, we genotyped TOX3 rs3803662 in 880 gastric patients with surgical resection. The association between genotype and survival outcomes was performed by the Kaplan-Meier method, Cox regression analysis models and the log-rank test. Results There was no association in the analyses of rs3803662 and survival of gastric cancer. However, the stratified analysis by histology showed that rs3803662 CT/TT genotype was associated with a significantly better survival for diffuse-type gastric cancer (log-rank p = 0.030, hazard ratio [HR]  = 0.67, 95% confidence interval [CI]  = 0.46–0.96), than the CC genotype. In addition, this favorable effect was especially obvious among gastric cancer patients with tumor size >5 cm, T3 and T4 depth of invasion, lymph node metastasis, no drinking, no distant metastasis, no chemotherapy and gastric cardia cancer. Conclusions TOX3 rs3803662 might play an important role in the prognostic outcome and treatment of gastric cancer, especially perhaps further help in explaining the reduced risk of death associated with diffuse-type gastric cancer.

Association of XRCC1 Gene Polymorphisms with the Survival and Clinicopathological Characteristics of Gastric Cancer.

Polymorphisms of the DNA repair gene X-ray repair cross-complementing protein 1 (XRCC1) Arg194Trp, Arg280His, and Arg399Gln have been shown to alter the DNA repair activity and to be associated with genetic susceptibility to several types of cancer. We indentified genotypes of 944 surgically resected gastric cancer (GC) patients by the SNaPshot method to investigate the association of these polymorphisms with clinical progression and outcomes of GC in a Chinese population. The XRCC1 codon 280 His carriers (Arg/His+His/His) held a significantly lower risk of distant metastasis in the dominant model (Pearson chi-square test P=0.019). A weak association of these cases with reduced risk of lymph node metastasis was also found (Pearson chi-square test P=0.051). Individuals carrying at least one Trp allele of XRCC1 codon 194 had an increased risk of death compared with those with Arg/Arg homozygotes in diffuse-type GC (adjusted hazard ratio=1.34, 95% confidence interval=1.05-1.71). Our findings demonstrated that the genetic variant Arg280His in XRCC1 may contribute to cancer progression and that XRCC1 Arg194Trp variants may act as a favorable prognostic indicator of resected GC, particularly among the diffuse-type GC. Larger studies are needed to verify our results in different populations.

Survival benefit from S-1 as compared to Fluorouracil in Asian patients with advanced gastrointestinal cancer: a meta-analysis.

Whether S‐1 could replace 5‐Fluorouracil (5‐Fu) or not in the treatment of advanced gastrointestinal (GI) cancer (including advanced gastric cancer [AGS] and metastatic colorectal cancer [mCRC]) in Asian patients has been controversial. This meta‐analysis was performed to compare the activity, efficacy and toxicity of S‐1‐based versus 5‐Fu‐based chemotherapy in those Asian patients. Randomized controlled trials (RCTs) were identified by electronic search of Pubmed. Relevant abstracts were manually searched to identify relevant trials. A total of 2182 patients from eight RCTs were included, and our results demonstrated that S‐1‐based chemotherapy significantly improved overall survival (OS) (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.77–1.00) and overall response rate (ORR) (odds ratio [OR], 1.72; 95% CI, 1.09–2.70), but no significant progression‐free survival (PFS) benefit was found between arms (HR, 0.87; 95% CI, 0.72–1.06). Subgroup analyses revealed that S‐1‐based chemotherapy significantly improved OS and ORR in subgroups of patients with non‐platinum containing regimens (P = 0.041; P = 0.034) and patients with no prior chemotherapy history (P = 0.025; P = 0.016). Statistically significant improvements of PFS and ORR in the S‐1‐based chemotherapy were observed in the subgroup of patients with AGC (P < 0.001; P = 0.005). S‐1‐based chemotherapy was characterized by significantly higher incidences of diarrhea, fatigue and thrombocytopenia, and a lower incidence of nausea. This analysis provided strong evidence for survival benefits of S‐1, and S‐1‐based chemotherapy could be considered to replace 5‐Fu‐based therapy for the treatment of advanced GI cancer in Asian patients.

Addition of vandetanib to chemotherapy in advanced solid cancers: a meta-analysis.

The addition of vandetanib to chemotherapy has been shown to have a marked effect on patients with advanced cancers who had failed previous chemotherapy. We carried out a meta-analysis to determine the efficacy and safety of vandetanib compared with chemotherapy in patients with advanced cancers. For this meta-analysis, we selected randomized clinical trials that compared vandetanib-based therapy (VBT) with the matched chemotherapy or placebo alone in patients with advanced cancers. The outcomes included overall survival (OS), progression-free survival (PFS), the objective response rate, and toxicities. Hazard ratios (HRs) and odds ratios were reported with 95% confidence intervals (CIs). A total of 14 eligible trials were included for the meta-analysis, with 2995 patients in the VBT group and 2479 patients in the control group. A significant improvement was observed in PFS (HR 0.76, 95% CI 0.68–0.86 in all cancers, HR 0.80, 95% CI 0.70–0.90 in lung cancer, HR 0.54, 95% CI 0.40–0.74 in thyroid cancer) and in objective response rate (odds ratio 2.09, 95% CI 1.42–3.07) in the VBT group. However, no significant difference was found in OS (HR 0.96, 95% CI 0.90–1.03). The subgroups of patients with non-small-cell lung cancer who benefited from vandetanib therapy were identified as those with a history of smoking (HR 0.87, 95% CI 0.80–0.95) and an adenocarcinoma histology (HR 0.85, 95% CI 0.77–0.94). In addition, patients who received VBT had an increased incidence of adverse events such as rash, diarrhea, and neutropenia. The addition of vandetanib to chemotherapy significantly improves PFS in patients with locally advanced or metastatic cancers, especially lung and thyroid cancer.