Yongfei Tan

Prognostic and Predictive Role of JWA and XRCC1 Expressions in Gastric Cancer

Purpose: To investigate the expression pattern and significance of DNA repair genes JWA and X-ray repair cross complement group 1 (XRCC1) in gastric cancer. Experimental Design: Expressions of JWA and XRCC1 were assessed by immunohistochemistry in a training cohort and they went into a second testing cohort and finally to a validating cohort. Prognostic and predictive role of JWA and XRCC1 expression status in cases treated with surgery alone or combined with adjuvant chemotherapy was evaluated, respectively. Results: JWA and XRCC1 protein levels were significantly downregulated in gastric cancer lesions compared with adjacent noncancerous tissues. Low tumoral JWA or XRCC1 expression significantly correlated with shorter overall survival (OS), as well as with clinicopathologic characteristics in patients without adjuvant treatment. Multivariate regression analysis showed that low JWA and XRCC1 expressions, separately and together, were independent negative markers of OS. Adjuvant fluorouracil-leucovorin-oxaliplatin (FLO) significantly improved OS compared with surgery alone (log-rank test, P = 0.01). However, this effect was evident only in the JWA or XRCC1 low expression group (HR = 0.44; 95% CI: 0.26–0.73; P = 0.002, and HR = 0.44, 95% CI: 0.26–0.75; P = 0.002, respectively); Adjuvant fluorouracil-leucovorin-platinol (FLP) did not improve OS, except in the patients with low JWA and XRCC1 expressions (P = 0.010 for JWA and 0.024 for XRCC1, respectively). Conclusions: JWA and XRCC1 protein expressions in tumor are novel candidate prognostic markers and predictive factors for benefit from adjuvant platinum-based chemotherapy (FLO or FLP) in resectable human gastric carcinoma. Clin Cancer Res; 18(10); 2987–96. ©2012 AACR.

Genetic variant in PSCA predicts survival of diffuse-type gastric cancer in a Chinese population

Recent genome‐wide association study (GWAS) has identified that the prostate stem cell antigen (PSCA) rs2294008 is involving in regulating gastric epithelial‐cell proliferation, influencing the risk of diffuse‐type gastric cancer. We hypothesized that PSCA rs2294008 is also associated with gastric cancer survival. We genotyped PSCA rs2294008 using TaqMan method in 943 patients with surgically resected gastric cancer. Analyses of genotype association with survival outcomes were assessed by the Kaplan‐Meier method, Cox proportional hazards models and the log‐rank test. There was no significant association between rs2294008 and survival of gastric cancer (log‐rank p = 0.085 for CT/TT versus CC). However, in the stratification analysis of histology, we found that rs2294008 CT/TT genotypes were associated with significantly improved survival among diffuse‐type gastric cancer (log‐rank p = 0.025, hazard ratio [HR] = 0.75, 95% confidence interval [CI] = 0.59–0.96), compared to the CC genotype. Moreover, this protective effect was more predominant for diffuse‐type gastric cancer patients with tumor size >5 cm and distant metastasis. If validated in further studies, PSCA rs2294008 could be useful marker of survival assessment and individualized clinical therapy for gastric cancer, particularly among the diffuse‐type gastric cancer.

Overexpression of Cullin1 is associated with poor prognosis of patients with gastric cancer

Cullin1 (Cul1) is a scaffold protein of the ubiquitin E3 ligase Skp1/Cullin1/Rbx1/F-box protein complex, which ubiquitinates a broad range of proteins involved in cell-cycle progression, signal transduction, and transcription. To investigate the role of Cullin1 in the development of gastric cancer, we examined the expression of Cullin1 in primary gastric cancer tissues and analyzed the correlation between Cullin1 expression and clinicopathologic variables and patients survival. We constructed a tissue microarray that includes 792 primary gastric cancer tissues and evaluated the Cullin1 expression by immunohistochemistry in the tumor biopsies. We also studied the role of Cullin1 in gastric cancer cell proliferation and adhesion by performing sulforhodamine B cell proliferation assay and cell attachment assay. The Cullin1 overexpression was significantly correlated with gastric cancer TNM stage (P = .011), depth of invasion (P = .035, comparing T1-T3 versus T4), and lymph node metastasis (P = .036). Furthermore, we showed a strong correlation between high Cullin1 expression and worse overall and 3-year survival rates in gastric cancer patients (P = .042 and P = .026, respectively). Cox regression analysis revealed that Cullin1 expression was an independent prognostic factor to predict 3-year patient outcome in gastric cancer (P = .028). Finally, we found that Cullin1 knockdown inhibits cell growth by up-regulating p27 expression and decreases cell adhesion ability by suppressing the expression of Src family kinases and focal adhesion kinase. Our data indicated that Cullin1 may be an important marker for human gastric cancer lymph node metastasis and prognosis.

A functional polymorphism in MIR196A2 is associated with risk and prognosis of gastric cancer.

Genetic variations in miRNAs have been demonstrated to be capable of altering miRNA expression, consequently affecting many cancer‐related biological processes. The MIR196A2 rs11614913 (T > C) polymorphism has been reported to be associated with various cancers development and progression. In our study, we aim to explore whether this polymorphism is relevant to the genetic susceptibility and prognosis of gastric cancer in a Chinese population. We analyzed the correlations of rs11614913 polymorphism with gastric cancer susceptibility in test and validation sets. The test set comprised 749 cases and 900 controls, while the validation set enrolled 940 cases and 1046 controls. Moreover, we evaluated the association between the polymorphism and gastric cancer prognosis in the validation set with follow‐up information. The variant rs11614913 CC genotype was associated with a significantly reduced risk of gastric cancer in both sets (adjusted odds ratio [OR] = 0.78, 95% confidence interval [CI] = 0.62–0.99 for the test set and 0.64, 0.52–0.80 for the validation set) compared with the CT/TT genotypes. Furthermore, the CC genotype was associated with a significantly increased survival of gastric cancer compared with the CT/TT genotypes (adjusted hazard ratio [HR] = 0.72, 95% CI = 0.55–0.95), and the association was more prominent among patients with non‐cardia gastric cancer than those with cardia gastric cancer (adjusted HR = 0.57, 95% CI = 0.40–0.83 for NCGC and 1.00, 0.65–1.53 for CGC). Our results suggested that the genetic variation of MIR196A2 may play a role in gastric cancer tumorigenesis.

Clinical significance of SOD2 and GSTP1 gene polymorphisms in Chinese patients with gastric cancer

Excessive reactive oxygen species (ROS) accumulation is a common phenomenon in carcinogenesis. However, the rationale behind ROS involvement in gastric cancer is unclear. In this study, the authors investigated the clinical significance of the single nucleotide polymorphisms (SNPs) of 2 ROS metabolic process‐related genes: superoxide dismutase 2 (SOD2) and glutathione S‐transferase π (GSTP1).

JWA suppresses tumor angiogenesis via Sp1-activated matrix metalloproteinase-2 and its prognostic significance in human gastric cancer

JWA, a multifunctional microtubule-binding protein, plays an important role in regulating tumor metastasis via inhibition of matrix metalloproteinase-2 (MMP-2). Recent investigations suggest that MMP-2 is an angiogenesis-associated molecule. In this study, we provide novel evidence that JWA inhibits tumor angiogenesis in gastric cancer (GC). In two independent retrospective GC cohorts, we found that the expression of JWA was downregulated and that of MMP-2 was upregulated in GC tissues compared with the same in normal gastric mucosa. For patients treated with surgery alone, a strong and independent negative prognostic value was shown for low JWA and high MMP-2 expressions separately, which was even stronger when combined (hazard ratio = 7.75, P < 0.001, in the training cohort; hazard ratio = 2.31, P < 0.001, in the validation cohort). Moreover, we found that loss of JWA expression was strongly correlated with increased GC angiogenesis. In vitro, JWA inhibited MMP-2 at both messenger RNA and protein levels by modulating Sp1 activity. Knockdown of endogenous JWA resulted in enhanced human umbilical vein endothelial cell tube formation and MMP-2 expression. Furthermore, JWA was found to inhibit Sp1 activity via an ubiquitin-proteasome-dependent mechanism and to downregulate the expression of the proangiogenic MMP-2. Our findings imply that JWA and MMP-2 may serve as promising prognostic markers in resectable GC, with JWA as a useful biomarker of angiogenesis in GC and a potential therapeutic target by MMP-2 modulation.

Synergistic Role between p53 and JWA: Prognostic and Predictive Biomarkers in Gastric Cancer

Expression of p53 appears to be correlated to prognosis in patients with malignancy, but its role in gastric carcinoma has remained controversial. Recently we reported that JWA, an ADP-ribosylation-like factor 6 interacting protein 5 (ARL6ip5), was both prognostic for overall survival and predictive for platinum-based treatment of gastric cancer. In this study, we aimed to investigate p53 expression as a prognostic and predictive marker in resectable gastric cancer, alone and in combination with JWA. Expression of p53 was examined in three large patient cohorts (total n = 1155) of gastric cancer. High expression of p53 was significantly correlated with unfavorable clinicopathologic parameters and decreased overall patient survival. Furthermore, patients with high p53 expression in tumors acquired remarkable survival benefit from adjuvant first-line platinum-based-chemotherapy. The synergy between p53 and JWA in predicting patient outcome was demonstrated, while no significantly elevated predictive value concerning chemotherapy was observed. Thus, p53 expression is a potent prognostic and predictive factor for resectable gastric cancer with adjuvant platinum-based chemotherapy. A combined effect of p53 with JWA as efficient prognostic indicators was found for the first time.

MDM2 is a useful prognostic biomarker for resectable gastric cancer

Expression of MDM2 protein appears to be increased in malignancy and correlated to prognosis of tumors, but its role in gastric cancer remains controversial. Our recent investigations indicated that JWA was a novel candidate biomarker for gastric cancer. To evaluate the impact of MDM2 protein expression alone, and in combination with JWA, on the prognostic and predictive of patients with resectable gastric cancer, expression of MDM2 and JWA were examined by immunohistochemistry in three large cohorts (total n = 1131) of patient with gastric cancer. We found that MDM2 protein levels were significantly upregulated in gastric cancer (70.4%, 57 of 81) compared with adjacent non‐cancerous tissues. High tumoral MDM2 expression significantly correlated with clinicopathologic characteristics, as well as with shorter overall survival (OS; P < 0.001 for all cohorts) in patients without adjuvant treatment. The effect of adjuvant fluorouracil–leucovorin–oxaliplatin (FLO) in improving OS compared with surgery alone was evident only in the high MDM2 group (hazard ratio = 0.57; 95% confidence interval, 0.37–0.89; P = 0.013). Furthermore, knockdown of MDM2 and overexpression of JWA had a synergistic effect on suppression of gastric cancer cell proliferation and migration. Patients with low MDM2 and high JWA expression had a better outcome of survival compared with the other groups (P < 0.001 for all cohorts). For the first time, our data suggest that MDM2 is a potent prognostic and predictive factor for benefit from adjuvant fluorouracil–leucovorin–oxaliplatin chemotherapy in resectable gastric cancer. The combination of MDM2 expression and JWA could serve as a more effective candidate prognostic biomarker for gastric cancer.

A genetic variation in APE1 is associated with gastric cancer survival in a Chinese population

Altered DNA repair can be associated with aggressive tumor biology and impact on survival of cancer patients. We investigated whether genetic variation of human apurinic/apyrimidinic (AP) endonuclease, a key multifunctional gene involved in the base excision repair pathway, would play a role in gastric cancer survival outcomes. We genotyped APE1 rs1760944 by the TaqMan method in 925 gastric cancer patients. Analyses of association between the polymorphism and survival outcomes were carried out using the Kaplan–Meier method, Cox proportional hazards models, and the log–rank test. Survival analyses for all patients showed that the differences in median survival time between gastric cancer carriers with APE1 rs1760944 TT (55 months) and those with GT/GG (78 months), were statistically significant (P = 0.025, log–rank test). Kaplan–Meier survival estimates revealed that gastric cancer patients carrying the GT/GG genotypes had a higher survival than TT, and this protective effect was also more pronounced among subgroups with tumor size >5 cm (hazard ratio = 0.66, 95% confidence interval = 0.49–0.88), diffuse‐type gastric cancer (0.76, 0.60–0.97), T3 depth of invasion (0.73, 0.57–0.93), lymph node metastasis (0.73, 0.58–0.92), no distant metastasis (0.81, 0.66–0.99), and TNM stage III and IV (0.75, 0.58–0.99 for stage III; 0.50, 0.29–0.88 for stage IV). Our results showed that the genetic variant rs1760944 in APE1 was associated with gastric cancer survival in a Chinese population. Larger studies are needed to verify our findings in different populations. (Cancer Sci 2011; 102: 1293–1297)

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.