Aiping Li

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.

CHIP functions as a novel suppressor of tumour angiogenesis with prognostic significance in human gastric cancer

Objective CHIP (carboxy terminus of Hsc70 interacting protein) is an E3 ubiquitin ligase that can induce ubiquitination and degradation of several tumour related proteins, and acts as a suppressor of tumour metastasis. This study explored the biological function and clinical significance of CHIP in gastric cancer (GC). Methods The prognostic value of CHIP expression was evaluated using tissue microarray and immunohistochemical staining in two independent human GC cohorts. The role of CHIP on tumorigenicity and angiogenesis was determined in vitro and in vivo. Results CHIP expression was significantly decreased in GC lesions compared with paired non-cancerous tissues. Low tumoral CHIP expression significantly correlated with clinicopathological characteristics in patients, as well as with shorter overall survival in both cohorts. Multivariate Cox regression analysis revealed that CHIP expression was an independent prognostic factor for human GC patients. Moreover, CHIP overexpression impeded the formation of anchorage independent colonies in soft agar, suppressed the growth of xenografts in nude mice and inhibited endothelial cell growth and tube formation by suppressing nuclear factor κB (NF-κB) mediated interleukin 8 (IL-8) expression in vitro. In vivo studies also confirmed that CHIP inhibited blood vessel formation and recruitment of CD31 positive cells in matrigel plugs. Also, CHIP interacted with NF-κB/p65 and promoted its ubiquitination and degradation by proteasome, terminating NF-κB activity and inhibiting IL-8-induced angiogenesis, which correlated with subsequent tumour metastasis. Conclusions Decreased CHIP expression in GC resulted in increased angiogenesis and contributed to GC progression and poor prognosis. CHIP expression is a GC candidate clinical prognostic marker and a putative treatment target.

TXNL1-XRCC1 pathway regulates cisplatin-induced cell death and contributes to resistance in human gastric cancer

Cisplatin is a cytotoxic platinum compound that triggers DNA crosslinking induced cell death, and is one of the reference drugs used in the treatment of several types of human cancers including gastric cancer. However, intrinsic or acquired drug resistance to cisplatin is very common, and leading to treatment failure. We have recently shown that reduced expression of base excision repair protein XRCC1 (X-ray repair cross complementing group1) in gastric cancerous tissues correlates with a significant survival benefit from adjuvant first-line platinum-based chemotherapy. In this study, we demonstrated the role of XRCC1 in repair of cisplatin-induced DNA lesions and acquired cisplatin resistance in gastric cancer by using cisplatin-sensitive gastric cancer cell lines BGC823 and the cisplatin-resistant gastric cancer cell lines BGC823/cis-diamminedichloridoplatinum(II) (DDP). Our results indicated that the protein expression of XRCC1 was significantly increased in cisplatin-resistant cells and independently contributed to cisplatin resistance. Irinotecan, another chemotherapeutic agent to induce DNA damaging used to treat patients with advanced gastric cancer that progressed on cisplatin, was found to inhibit the expression of XRCC1 effectively, and leading to an increase in the sensitivity of resistant cells to cisplatin. Our proteomic studies further identified a cofactor of 26S proteasome, the thioredoxin-like protein 1 (TXNL1) that downregulated XRCC1 in BGC823/DDP cells via the ubiquitin-proteasome pathway. In conclusion, the TXNL1-XRCC1 is a novel regulatory pathway that has an independent role in cisplatin resistance, indicating a putative drug target for reversing cisplatin resistance in gastric cancer.

JWA reverses cisplatin resistance via the CK2-XRCC1 pathway in human gastric cancer cells.

Gastric cancer is the third most common malignancy in China, with a median 5-year survival of only 20%. Cisplatin has been used in first-line cancer treatment for several types of cancer including gastric cancer. However, patients are often primary resistant or develop acquired resistance resulting in relapse of the cancer and reduced survival. Recently, we demonstrated that the reduced expression of base excision repair protein XRCC1 and its upstream regulator JWA in gastric cancerous tissues correlated with a significant survival benefit of adjuvant first-line platinum-based chemotherapy as well as XRCC1 playing an important role in the DNA repair of cisplatin-resistant gastric cancer cells. In the present study, we demonstrated the role of JWA in cisplatin-induced DNA lesions and aquired cisplatin resistance in five cell-culture models: gastric epithelial cells GES-1, cisplatin-sensitive gastric cancer cell lines BGC823 and SGC7901, and the cisplatin-resistant gastric cancer cell lines BGC823/DDP and SGC7901/DDP. Our results indicated that JWA is required for DNA repair following cisplatin-induced double-strand breaks (DSBs) via XRCC1 in normal gastric epithelial cells. However, in gastric cancer cells, JWA enhanced cisplatin-induced cell death through regulation of DNA damage-induced apoptosis. The protein expression of JWA was significantly decreased in cisplatin-resistant cells and contributed to cisplatin resistance. Interestingly, as JWA upregulated XRCC1 expression in normal cells, JWA downregulated XRCC1 expression through promoting the degradation of XRCC1 in cisplatin-resistant gastric cancer cells. Furthermore, the negative regulation of JWA to XRCC1 was blocked due to the mutation of 518S/519T/523T residues of XRCC1, and indicating that the CK2 activated 518S/519T/523T phosphorylation is a key point in the regulation of JWA to XRCC1. In conclusion, we report for the first time that JWA regulated cisplatin-induced DNA damage and apoptosis through the CK2—P-XRCC1—XRCC1 pathway, indicating a putative drug target for reversing cisplatin resistance in gastric cancer.

SOX2 inhibits metastasis in gastric cancer

PurposeTo investigate the potential role of SOX2 in gastric cancer (GC) metastasis.MethodsThe SOX2 expression was detected using immunohistochemistry on a GC tissue microarray. The correlations of SOX2 expression with clinicopathological factors and 5-year survival were evaluated. To test the role of SOX2 in inhibiting GC metastasis, the cell transwell assay was performed. Real-time PCR and Western blot were used to explore the possible mechanism that SOX2 inhibits GC metastasis.ResultsIn the present study, SOX2 expression was downregulated in GC tissues when compared to matching normal tissues. Moreover, patients with high SOX2 expression in cancerous tissues had less lymph node metastasis and better treatment outcome. At the subcellular level, SOX2 inhibited the GC cell migration and invasion by upregulating p21 expression. Moreover, SOX2 was determined to associate with the nuclear p21 expression. GC patients with high SOX2 and nuclear p21 expression had synergistically less lymph node metastasis and the better overall survival.ConclusionOur results suggest that SOX2 is a promising and favorable metastatic biomarker for GC.

The opposite prognostic significance of nuclear and cytoplasmic p21 expression in resectable gastric cancer patients

BackgroundProtein p21Cip1/Waf1 is a cyclin-dependent kinase inhibitor, which plays important roles in cell cycle arrest, senescence, and apoptosis. Interestingly, the nuclear and cytoplasmic p21 executes various functions in the cell. In this study, we investigated the prognostic impact of subcellular p21 expression in gastric cancer (GC).MethodsExpressions of subcellular p21 was assessed by immunohistochemistry using a tissue microarray in a training cohort and it went into a second testing cohort and finally to a validating cohort. Prognostic and predictive role of subcellular p21 expression status was evaluated. We also studied the roles of subcellular p21 in GC cell migration and invasion.ResultsNuclear and cytoplasmic p21 protein levels were significantly reduced and increased in GC lesions compared with adjacent non-cancerous tissues, respectively. Low nuclear p21 or high cytoplasmic p21 expression significantly correlated with shorter overall survival (OS), as well as with clinicopathologic characteristics in patients. Multivariate regression analysis showed that low nuclear and high cytoplasmic p21 expression, separately and together, were independent negative markers of OS. Finally, we found that nuclear p21 inhibits but cytoplasmic p21 promotes cell migration and invasion abilities.ConclusionsThese findings suggest that nuclear and cytoplasmic p21 protein expression in tumor are novel candidate prognostic markers in resectable human gastric carcinoma, and they exert distinct roles in cell migration and invasion.

JWA regulates TRAIL-induced apoptosis via MARCH8-mediated DR4 ubiquitination in cisplatin-resistant gastric cancer cells

Platinum chemotherapeutics are widely used to treat solid malignant tumors, including gastric cancer (GC). Drug resistance to platinum compounds may result in cancer relapse and decreased survival. The identification and development of novel agents to reactivate apoptosis pathways in platinum-resistant cancer cells is therefore necessary. Here we report that cisplatin-resistant human GC cells (BGC823/DDP and SGC7901/DDP) but not their parental cells (BGC823 and SGC7901) exhibit high sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a result of overexpression of death receptor 4 (DR4). Furthermore, we found that JWA, a molecule that promotes cisplatin-induced apoptosis in GC cells, suppressed TRAIL-induced apoptosis via negative regulation of DR4. Mechanistically, JWA promoted the ubiquitination of DR4 at K273 via upregulation of the ubiquitin ligase membrane-associated RING-CH-8 (MARCH8). In human GC tissues, JWA and DR4 protein levels were negatively correlated. Thus TRAIL may serve as an auxiliary treatment for cisplatin-resistant GC, and JWA may be a potential predictive marker of TRAIL sensitivity and may improve personalized therapeutics for treating human GC.

High FAK combined with low JWA expression: clinical prognostic and predictive role for adjuvant fluorouracil–leucovorin–oxaliplatin treatment in resectable gastric cancer patients

BackgroundThe multifunctional protein JWA was previously identified as a novel regulator of focal adhesion kinase (FAK/PTK2) in suppressing cancer cell adhesion, invasion and metastasis. JWA is downregulated in gastric cancer (GC) and a prognostic and predictive biomarker for resectable GC. However, the value of FAK combined with JWA for GC patients as a biomarker has not been studied. Here we evaluated the roles of FAK alone and combined with JWA in GC patients treated with surgery alone or combined with adjuvant platinum-based chemotherapy.MethodsTwo tissue microarrays were constructed of specimens from resected GC (nxa0=xa0709 in total) for detection of FAK and JWA expression by immunohistochemistry. Correlations between both proteins and clinicopathological features as well as prognostic and predictive values were evaluated.ResultsCompared with adjacent non-cancerous tissues, FAK protein levels were remarkably up-regulated in GC lesions (Pxa0<xa00.001). High FAK alone or combined with low JWA expression significantly correlated with worse overall survival (OS) (both Pxa0<xa00.001 in two cohorts). Simultaneously, JWA plus FAK expression was a more valuable prognostic biomarker than JWA or FAK alone. Moreover, the patients with high FAK only or combined with low JWA had significant benefit from adjuvant fluorouracil–leucovorin–oxaliplatin (FLO) therapy compared with those with surgery alone (Pxa0=xa00.003); however, the cases with adjuvant fluorouracil–leucovorin–cisplatin (FLP) therapy did not show these effects.ConclusionFAK plus JWA may serve as a more prognostic and predictive biomarker for GC than each separately with a potential clinical application.

JWA loss promotes cell migration and cytoskeletal rearrangement by affecting HER2 expression and identifies a high-risk subgroup of HER2-positive gastric carcinoma patients

Background and Aims JWA, a microtubule-associated protein (MAP) involved in apoptosis, has been identified as a suppressor of metastasis, and it affects cell migration in melanoma and its downregulation in tumor is an idependent negative prognostic factor in resectable gastric cancer. HER2 overexpression has been observed in gastric cancer (GC) cells and implicated in the metastatic phenotype. However, the biological role of JWA in migration and its clinical value in HER2-positive GC remain elusive. Results JWA suppresses EGF-induced cell migration and actin cytoskeletal rearrangement by abrogating HER2 expression and downstream PI3K/AKT signaling in HER2-overexpressing GC cell lines. The modulation of HER2 by JWA is dependent on ERK activation and consequent PEA3 upregulation and activation. Reduced JWA expression is associated with high HER2 expression and with poor survival in patients with AGC, whereas HER2 expression alone is not associated with survival. However, concomitant low JWA and high HER2 expression is associated with unfavorable outcomes. Additionally, when patients were stratified by JWA expression, those with higher HER2 expression in the low JWA expression subgroup exhibited worse survival. Methods The impact of JWA on the EGF-induced migration of HER2-positive GC cells was studied using transwell assays and G-LISA assays. Western blotting, real-time PCR, electrophoretic mobility shift assays and luciferase assays were utilized to investigate the mechanisms by which JWA affects HER2. The association of JWA with HER2 and its clinical value were further analyzed by IHC in 128 pairs of advanced gastric cancer (AGC) and adjacent normal tissue samples. Conclusions This study characterizes a novel mechanism for regulating cell motility in HER2-overexpressing GC cells involving JWA-mediated MEK/ERK/PEA3 signaling activation and HER2 downregulation. Furthermore, JWA may be a useful prognostic indicator for advanced GC and may help stratify HER2-positive patient subgroups to better identify unfavorable outcomes.

Inhibition of PARP1 activity enhances chemotherapeutic efficiency in cisplatin-resistant gastric cancer cells

Cisplatin (DDP) is the first line chemotherapeutic drug for several cancers, including gastric cancer (GC). Unfortunately, the rapid development of drug resistance remains a significant challenge for the clinical application of cisplatin. There is an urgent need to develop new strategies to overcome DDP resistance for cancer treatment. In this study, four types of human GC cells have been divided into naturally sensitive or naturally resistant categories according to their responses to cisplatin. PARP1 activity (poly (ADP-ribose), PAR) was found to be greatly increased in cisplatin-resistant GC cells. PARP1 inhibitors significantly enhanced cisplatin-induced DNA damage and apoptosis in the resistant GC cells via the inhibition of PAR. Mechanistically, PARP1 inhibitors suppress DNA-PKcs stability and reduce the capability of DNA double-strand break (DSB) repair via the NHEJ pathway. This was also verified in BGC823/DDP GC cells with acquired cisplatin resistance. In conclusion, we identified that PARP1 is a useful interceptive target in cisplatin-resistant GC cells. Our data provide a promising therapeutic strategy against cisplatin resistance in GC cells that has potential translational significance.