Xian-Zi Wen

BRCA1 promoter methylation associated with poor survival in Chinese patients with sporadic breast cancer.

Transcriptional inactivation of breast cancer gene 1 (BRCA1) by DNA methylation is a frequent event in sporadic breast cancers. To investigate whether BRCA1 methylation is associated with survival in Chinese patients with sporadic breast cancer, BRCA1 methylation was determined using methylation specific PCR in 536 sporadic breast cancers. Survival curves for patients with methylated and unmethylated BRCA1 were compared using the log‐rank tests. Twenty‐six percent (139/536) of patients exhibited BRCA1 methylation in their tumors. The degree of BRCA1 methylation was correlated with clinical stages of breast cancer, but was not significant. Patients with BRCA1 methylated tumors had a significantly worse 5‐year disease‐free survival (DFS) and 5‐year disease‐specific survival (DSS) than did patients with unmethylated tumors (DFS: 73.2%vs 82.6%, P = 0.045; DSS 80.5%vs 87%, P = 0.038, two‐sided). In conclusions, BRCA1 methylation is a frequent event in breast cancer and is associated with poor clinical outcome in Chinese women with breast cancer. (Cancer Sci 2009; 100: 1663–1667)

Maternal embryonic leucine zipper kinase serves as a poor prognosis marker and therapeutic target in gastric cancer

Maternal embryonic leucine zipper kinase (MELK) is upregulated in a variety of human tumors, and is considered an attractive molecular target for cancer treatment. We characterized the expression of MELK in gastric cancer (GC) and measured the effects of reducing MELK mRNA levels and protein activity on GC growth. MELK was frequently overexpressed in primary GCs, and higher MELK levels correlated with worse clinical outcomes. Reducing MELK expression or inhibiting kinase activity resulted in growth inhibition, G2/M arrest, apoptosis and suppression of invasive capability of GC cells in vitro and in vivo. MELK knockdown led to alteration of epithelial mesenchymal transition (EMT)-associated proteins. Furthermore, targeting treatment with OTSSP167 in GC patient-derived xenograft (PDX) models had anticancer effects. Thus, MELK promotes cell growth and invasiveness by inhibiting apoptosis and promoting G2/M transition and EMT in GC. These results suggest that MELK may be a promising target for GC treatment.

PP242 suppresses cell proliferation, metastasis, and angiogenesis of gastric cancer through inhibition of the PI3K/AKT/mTOR pathway

Although preclinical work with rapalogs suggests potential in the treatment of gastric cancer, they have been less successful clinically. In this study, we report the impact of the investigational drug PP242, a potent and selective small-molecule active-site TORC1/2 kinase inhibitor, on tumor growth and metastasis. The antiproliferative effect of PP242 was assessed using the Cell Counting Kit-8 assay. The migration and invasion potential were analyzed using wound-healing and transwell assays, respectively. The Matrigel capillary tube formation assay was performed to mimic in-vivo angiogenesis. Immunoblotting and immunofluorescence were used to observe protein levels and distribution of actin fibers. Finally, S2448p-mammalian target of rapamycin (mTOR) expression was detected on gastric cancer tissues using immunohistochemistry. First, PP242 potently inhibited cell proliferation in gastric cancer cell lines and in human endothelial cells in vitro at the IC50 ranged from 50 to 500 nmol/l. Then, an inhibitory effect of PP242 on metastasis was observed in gastric cancer cell AGS, along with the cytoskeletal rearrangements and suppression of the phosphorylation of PI3K downstream factors including AKT, mTOR, and P70S6K. Furthermore, PP242 was found to decrease the tube formation and migration of human umbilical vein endothelial cells. Using immunohistochemistry, we found that S2448p-mTOR staining was observed in 41.8% (82/196) of gastric cancer tissues and correlated with depth of mural invasion, lymph node metastasis, tumor node metastasis stage, and vascular invasion. These results show that PP242 suppresses cell proliferation and angiogenesis of gastric cancer through inhibition of the PI3K/AKT/mTOR pathway, which might be an effective novel therapeutic candidate against gastric cancer in the future.

Efficient generation of mice carrying homozygous double-floxp alleles using the Cas9-Avidin/Biotin-donor DNA system

Efficient generation of mice carrying homozygous double-floxp alleles using the Cas9-Avidin/Biotin-donor DNA system

Phosphatase of regenerating liver-3 (PRL-3) is associated with metastasis and poor prognosis in gastric carcinoma

BackgroundPRL-3 is a member of phosphatases of regenerating liver family, characterized by phosphatase active domain and C-terminal prenylation motif. Overexpression of PRL-3 has been implicated in multiple cancers. Here we examined the clinical significance of PRL-3 in gastric cancer together with its metastatic biological functions utilizing different structural mutants.MethodsPRL-3 expression was analyzed immunohistochemically in 196 gastric cancer patients and 21 cases of liver metastasis. A series of wild type PRL-3 or its mutant plasmids were expressed in BGC823 cells to investigate the relationship between its catalytic activity, cellular localization and metastatic potential in vitro.ResultsPositive staining of PRL-3 was observed in 19.4% (38/196) gastric cancer tissues compared with 76.2% (16/21) in liver metastasis. Statistical analysis revealed that PRL-3 expression correlated with lymph node metastasis and vascular invasion (P < 0.05). Patients with high PRL-3 expression showed poorer 5-year overall survival (P = 0.011). Wild type PRL-3 expressing cells resulted in enhanced migration and invasion ability, which were greatly crippled in form of PRL-3(C104S) or PRL-3(ΔCAAX) mutants accompanied with its alteration in subcellular localization.ConclusionsMetastasis associated protein PRL-3 may serve as a potential prognostic biomarker in human gastric cancer. Both the phosphatase catalytic activity and cellular localization are critical for its function.

Trichostatin A potentiates TRAIL-induced antitumor effects via inhibition of ERK/FOXM1 pathway in gastric cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an ideal apoptosis inducer and believed to have promise in cancer therapy, yet part of cancer cells exhibit resistance to TRAIL-mediated apoptosis. This necessitates the exploration of agents that resensitizes cancer cells to TRAIL. In our study, we found that Trichostatin A (TSA), an histone deacetylase (HDAC) inhibitor, augmented TRAIL-induced apoptosis in gastric cancer cells in a caspase-dependent manner. Besides, upregulation of DR5 and downregulation of anti-apoptotic proteins including XIAP, Mcl-1, Bcl-2 and Survivin also contributed to this synergism. Noticeably, TSA treatment inhibited Forkhead boxM1 (FOXM1), which expression level showed negative correlation with TRAIL sensitivity. Similarly, silencing of FOXM1 by small interfering RNA (siRNA) resensitized cancer cells to TRAIL and strengthened the TRAIL-augmenting effect of TSA. In addition, we demonstrated the depletion of FOXM1 was a consequence of the inactivation of ERK mediated by TSA. Collectively, it was first shown that TSA potentiated TRAIL sensitivity via ERK/FOXM1 pathway in gastric cancer cells. FOXM1 might serve as a biomarker for predicting sensitivity to TRAIL.

Paclitaxel enhances tumoricidal potential of TRAIL via inhibition of MAPK in resistant gastric cancer cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) holds promise for cancer therapy due to its unique capacity to selectively trigger apoptosis in cancer cells. However, TRAIL therapy is greatly hampered by its resistance. A preclinical successful strategy is to identify combination treatments that sensitize resistant cancers to TRAIL. In the present study, we fully assessed TRAIL sensitivity in 9 gastric cancer cell lines. We found combined administration of paclitaxel (PTX) markedly enhanced TRAIL-induced apoptosis in resistant cancer cells both in vitro and in vivo. The sensitization to TRAIL was accompanied by activation of mitochondrial apoptotic pathway, upregulation of TRAIL receptors and downregulation of anti-apoptotic proteins including C-IAP1, C-IAP2, Livin and Mcl-1. Noticeably, we found PTX could suppress the activation of mitogen-activated protein kinases (MAPKs). Inhibition of MAPKs using specific inhibitors (ERK inhibitor U0126, JNK inhibitor SP600125 and P38 inhibitor SB202190) facilitated TRAIL-mediated apoptosis and cytotoxicity. Additionally, SP600125 upregulated TRAL receptors as well as downregulated C-IAP2 and Mcl-1 suggesting the anti-apoptotic role of JNK. Thus, PTX-induced suppression of MAPKs may contribute to restoring TRAIL senstitivity. Collectively, our comprehensive analyses gave new insight into the role of PTX on enhancing TRAIL sensitivity, and provided theoretical references on the development of combination treatment in TRAIL-resistant gastric cancer.

Insights into roles of the miR-1, -133 and -206 family in gastric cancer (Review)

Gastric cancer (GC) remains the third most common cause of cancer deaths worldwide and carries a high rate of metastatic risk contributing to the main cause of treatment failure. An accumulation of data has resulted in a better understanding of the molecular network of GC, however, gaps still exist between the unique bio-resources and clinical application. MicroRNAs are an important part of non-coding RNAs and behave as major regulators of tumour biology, alongside their well-known roles as intrinsic factors of gene expression in cellular processes, via their post-transcriptional regulation of components of signalling pathways in a coordinated manner. Deregulation of the miR-1, -133 and -206 family plays a key role in tumorigenesis, progression, invasion and metastasis. This review aims to provide a summary of recent findings on the miR-1, -133 and -206 family in GC and how this knowledge might be exploited for the development of future miRNA-based therapies for the treatment of GC.

LAPTM4B-35, a Cancer-Related Gene, Is Associated with Poor Prognosis in TNM Stages I-III Gastric Cancer Patients

Background Lysosome-associated transmembrane protein 4β-35 (LAPTM4B-35), a member of the mammalian 4-tetratransmembrane spanning protein superfamily, has been reported to be overexpressed in several cancers. However the expression of LAPTM4B-35 and its role in the progression of gastric cancer (GC) remains unknown. The aim of this study was to investigate LAPTM4B-35 expression in GC, its potential relevance to clinicopathologic parameters and role of LAPTM4B-35 during gastric carcinogenesis. Methods In the present study, paraffin-embedded specimens with GC (n = 240, including 180 paired specimens) and 24 paired fresh frozen tissues were analyzed. qRT-PCR and immunohistochemistry (IHC) were used to analyze the expression of LAPTM4B-35 in GC. The effects of LAPTM4B-35 on GC cell proliferation, migration and invasion were determined by overexpression and knockdown assays. Results IHC showed that LAPTM4B-35 was expressed in 68.3% (123/180) of GC tissues, while in 16.1% (29/180) of their paired adjacent noncancerous gastric tissues (P = 0.000). LAPTM4B-35 mRNA levels in GC tissues were also significantly elevated when compared with their paired adjacent noncancerous tissues (P = 0.017). Overexpression of LAPTM4B-35 was significantly associated with degree of differentiation, depth of invasion, lymphovascular invasion and lymph node metastasis (P<0.05). Kaplan-Meier survival curves revealed that patients with LAPTM4B-35 expression had a significant decrease in overall survival (OS) in stages I-III GC patients (P = 0.006). Multivariate analysis showed high expression of LAPTM4B-35 was an independent prognostic factor for OS in stage I-III GC patients (P = 0.025). Conclusion These findings indicate that LAPTM4B-35 overexpression may be related to GC progression and poor prognosis, and thus may serve as a new prediction marker of prognosis in GC patients.

OSMR and SEPT9: promising biomarkers for detection of colorectal cancer based on blood-based tests

Background: Early screening and monitoring of the stage of colorectal cancer (CRC) is crucial for successful treatment and patient survival. Our purpose was to identify that evaluating methylated oncostatin M receptor (mOSMR) and Septin 9 (mSEPT9) in plasma DNA could be a feasible method for CRC diagnosis. Methods: Plasma samples (40 samples have matched cancer and adjacent non-cancer tissues) were collected from 187 patients with CRC, 25 patients with polyps and 109 healthy controls. qRT-PCR assay was used to analyze SEPT9 and OSMR mRNA levels. DNA bisulfite treatment, the levels of mSEPT9 and mOSMR in CRC tissues and plasma samples were evaluated by using fluorescence-based real-time PCR assay (MethyLight). mSEPT9 and mOSMR levels in plasma were compared before and after curative resection. Serum CEA, CA19-9, CA72-4 and CA242 were also measured and analyzed in parallel. Results: SEPT9 and OSMR mRNA levels were significantly lower in CRC tissues compared with those in their adjacent noncancerous tissues (P=0.006 and 0.002, respectively). mSEPT9 and mOSMR were significantly higher in CRC tissues compared with those in their adjacent non-cancerous tissues (P Conclusions: OSMR methylation (mOSMR) in plasma is useful for diagnosis of CRC as a new biomarker, and the panel of tests to analyze mSEPT9, mOSMR, CEA, CA19-9, CA72-4 and CA242 appears to be feasible and convenient for the diagnosis of CRC.