Dong Liang Chen

Overexpression of paxillin induced by miR-137 suppression promotes tumor progression and metastasis in colorectal cancer

The deregulation of paxillin (PXN) has been involved in the progression and metastasis of different malignancies including colorectal cancer (CRC). miR-137 is frequently suppressed in CRC. PXN is predicted to be a direct target of miR-137 in CRC cells. On this basis, we hypothesized that overexpression of PXN induced by suppression of miR-137 may promote tumor progression and metastasis and predicts poor prognosis. We detected the expression of PXN and miR-137 in clinical tumor tissues by immunohistochemical analysis and real-time PCR, positive PXN staining was observed in 198 of the 247 (80.1%) cases, whereas no or weak PXN staining was observed in the adjacent non-cancerous area. Higher level of PXN messenger RNA (mRNA) and lower level of miR-137 was observed in cancer tissues than adjacent non-cancerous tissues. High expression of PXN and low expression of miR-137 was associated with aggressive tumor phenotype and adverse prognosis. Moreover, the expression of PXN was negatively correlated with miR-137 expression. A dual-luciferase reporter gene assay validated that PXN was a direct target of miR-137. The use of miR-137 mimics or inhibitor could decrease or increase PXN mRNA and protein levels in CRC cell lines. Knockdown of PXN or ectopic expression of miR-137 could markedly inhibit cell proliferation, migration and invasion in vitro and repress tumor growth and metastasis in vivo. Taken together, these results demonstrated that overexpression of PXN induced by suppression of miR-137 promotes tumor progression and metastasis and could serve as an independent prognostic indicator in CRC patients.

ABO blood group, hepatitis B viral infection and risk of pancreatic cancer

Little is known about the role of association between ABO blood type and risk of pancreatic cancer develops through effects on hepatitis B viral (HBV) infection. Our study aimed to determine whether joint ABO blood type and HBV infection could increase the risk for pancreatic cancer. A total of 645 patients with pancreatic adenocarcinoma and 711 age‐ and sex‐matched individuals who had nonmalignant diseases treated at the Sun Yat‐sen University Cancer Center in China were retrospectively analyzed. Blood samples were tested for ABO blood type and hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti‐HBs), hepatitis B e antigen (HBeAg), hepatitis B e antibody (anti‐HBe) and hepatitis B core antibody (anti‐HBc). Multivariable unconditional logistic regression analysis was used to estimate adjusted odds ratios [AORs] and 95% confidence interval [CI]. Multivariable analysis with adjustment for risk factors showed that A blood type, HBsAg‐positive/anti‐HBc‐positive, anti‐HBs‐positive/anti‐HBc‐positive were significantly associated with pancreatic cancer. The estimated AORs (95% CI) were as follows: A blood type, 1.425 (1.071–1.894), HBsAg‐positive/anti‐HBc‐positive, 1.610 (1.125–2.304), anti‐HBs‐positive/anti‐HBc‐positive, 1.526 (1.159–2.011). The effect of A blood type significantly modified the risk of pancreatic cancer among subjects with anti‐HBc‐positive (AORs = 1.882, 95% CI, 1.284–2.760). In our study, we reported an association between A blood type, infection with HBV and pancreatic cancer risk. Moreover, we found a synergism between A blood type and HBV infection in the development of pancreatic cancer.

Identification of MicroRNA-214 as a negative regulator of colorectal cancer liver metastasis by way of regulation of fibroblast growth factor receptor 1 expression

The purpose of this study was to identify microRNAs (miRNAs) involved in the pathology of colorectal cancer (CRC) liver metastasis and investigate their underlying mechanisms. A total of 39 miRNAs were identified to be differentially expressed between 16 primary CRC tissues with liver metastases and 16 CRC tissues without liver metastases from 32 patients by Affymetric miRNA microarrays. A panel of eight miRNAs were confirmed to be significantly and differentially expressed between CRC tissues with and without liver metastases through quantitative reverse‐transcription polymerase chain reaction (RT‐PCR) analysis in the 32 patients. In a validated cohort of 99 CRC patients (44 with and 55 without liver metastases), only miR‐214 was validated to be significantly down‐regulated in CRC with liver metastases, which was associated with an unfavorable prognosis. Ectopic expression of miR‐214 suppressed proliferation, migration, and invasion in vitro, tumor growth and liver metastasis in an in vivo xenograft mouse model, whereas miR‐214 knockdown promoted proliferation, migration, and invasion in CRC cell lines. Further studies indicated that fibroblast growth factor receptor 1 (FGFR1) was a potential target of miR‐214. Restoring miR‐214 expression in CRC cells decreased endogenous FGFR1 messenger RNA (mRNA) and protein levels. FGFR1 knockdown mimicked the tumor suppressive effect of miR‐214 on CRC cells, while reintroduction of FGFR1 abolished the tumor suppressive effect of miR‐214 on CRC cells. Moreover, miR‐214 expression levels were inversely correlated with FGFR1 in CRC patients. Conclusion: Down‐regulation of miR‐214 expression was correlated with increased FGFR1 expression levels, which may contribute to increased CRC liver metastasis. miR‐214 may serve as a potential marker to predict survival, and the miR‐214‐FGFR1 axis may be a therapeutic target in CRC patients. (Hepatology 2014;60:598–609)

Long non-coding RNA XIST regulates gastric cancer progression by acting as a molecular sponge of miR-101 to modulate EZH2 expression

BackgroundLong non-coding RNAs (lncRNAs) have emerged as critical regulators of tumor progression. However, the role and molecular mechanism of lncRNA XIST in gastric cancer is still unknown.MethodsReal-time PCR analysis was performed to measure the expression levels of lncRNA XIST in gastric cancer tissues and cell lines, the correlation between lncRNA XIST expression and clinicopathological characteristics and prognosis was analyzed in gastric cancer patients. The biological function of lncRNA XIST on gastric cancer cells were determined both in vitro and in vivo. The regulating relationship between lncRNA XIST and miR-101 was investigated in gastric cancer cells.ResultslncRNA XIST was significantly up-regulated in gastric cancer tissues and cell lines. Overexpression of lncRNA XIST was markedly associated with larger tumor size, lymph node invasion, distant metastasis and TNM stage in gastric cancer patients. Functionally, knockdown of lncRNA XIST exerted tumor-suppressive effects by inhibiting cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo. Furthermore, an inverse relationship between lncRNA XIST and miR-101 was found. Polycomb group protein enhancer of zeste homolog 2 (EZH2), a direct target of miR-101, could mediated the biological effects that lncRNA XIST exerted.ConclusionslncRNA XIST is up-regulated and is associated with aggressive tumor phenotypes and patient survival in gastric cancer, and the newly identified lncRNA XIST/miR-101/EZH2 axis could be a potential biomarkers or therapeutic targets for gastric cancer patients.

Overexpression of the Circadian Clock Gene Bmal1 Increases Sensitivity to Oxaliplatin in Colorectal Cancer

Purpose: The circadian clock gene Bmal1 is involved in cancer cell proliferation and DNA damage sensitivity. The aim of this study was to explore the effect of Bmal1 on oxaliplatin sensitivity and to determine its clinical significance in colorectal cancer. Experimental Design: Three colorectal cancer cell lines, HCT116, THC8307 and HT29, were used. The Bmal1-mediated control of colorectal cancer cell proliferation was tested in vitro and in vivo. MTT and colony formation assays were performed to determine the sensitivity of colorectal cancer cells to oxaliplatin. Flow cytometry was used to examine changes in the cell-cycle distribution and apoptosis rate. Proteins expressed downstream of Bmal1 upon its overexpression were determined by Western blotting. Immunohistochemistry was used to analyze Bmal1 expression in 82 archived colorectal cancer tumors from patients treated with oxaliplatin-based regimens. Results: Bmal1 overexpression inhibited colorectal cancer cell proliferation and increased colorectal cancer sensitivity to oxaliplatin in three colorectal cancer cell lines and HCT116 cells model in vivo. Furthermore, the overall survival of patients with colorectal cancer with high Bmal1 levels in their primary tumors was significantly longer than that of patients with low Bmal1 levels (27 vs. 19 months; P = 0.043). The progression-free survival of patients with high Bmal1 expression was also significantly longer than that of patients with low Bmal1 expression (11 vs. 5 months; P = 0.015). Mechanistically, the effect of Bmal1 was associated with its ability to regulate G2–M arrest by activating the ATM pathway. Conclusion: Bmal1 shows the potential as a novel prognostic biomarker and may represent a new therapeutic target in colorectal cancer. Clin Cancer Res; 20(4); 1042–52. ©2013 AACR.

CDC20 overexpression predicts a poor prognosis for patients with colorectal cancer.

BackgroundThe cell division cycle 20 homolog (CDC20) is an essential cofactor of the anaphase-promoting complex (APC/C). CDC20 overexpression has been detected in many types of human cancers; however, its clinical role in colorectal cancer remains unknown.MethodsWestern blotting and immunohistochemistry were used to compare CDC20 expression in adjacent non-cancerous, cancerous and liver metastatic tissues as well as in colon cancer cell lines and normal colon epithelial cell lines. Additionally, the correlation of CDC20 expression with patient clinical parameters and its diagnostic value were statistically analyzed.ResultsCDC20 was overexpressed in colon cancer cell lines/primary cancer tissues compared with normal colon epithelial cell lines/adjacent noncancerous tissue samples. Interestingly, CDC20 expression was further increased in metastatic liver tissues. CDC20 protein expression was significantly correlated with clinical stage (P = 0.008), N classification (P = 0.020), M classification (P = 0.013) and pathologic differentiation (P = 0.008). Patients with higher CDC20 expression had a shorter overall survival than those with lower CDC20 expression. Univariate and multivariate analyses indicated that CDC20 expression was an independent prognostic factor (P < 0.001).ConclusionCDC20 may serve as a potential prognostic biomarker of human colorectal cancer.

L1cam promotes tumor progression and metastasis and is an independent unfavorable prognostic factor in gastric cancer

BackgroundPrevious reports have demonstrated that L1cam is aberrantly expressed in various tumors. The potential role of L1cam in the progression and metastasis of gastric cancer is still not clear and needs exploring.MethodsExpression of L1cam was evaluated in gastric cancer tissues and cell lines by immunohistochemistry and Western blot. The relationship between L1cam expression and clinicopathological characteristics was analyzed. The effects of L1cam on cell proliferation, migration and invasion were investigated in gastric cancer cell lines both in vitro and in vivo. The impact of L1cam on PI3K/Akt pathway was also evaluated.ResultsL1cam was overexpressed in gastric cancer tissues and cell lines. L1cam expression was correlated with aggressive tumor phenotype and poor overall survival in gastric cancer patients. Ectopic expression of L1cam in gastric cell lines significantly promoted cell proliferation, migration and invasion whereas knockdown of L1cam inhibited cell proliferation, migration and invasion in vitro as well as tumorigenesis and metastasis in vivo. The low level of phosphorylated Akt in HGC27 cells was up-regulated after ectopic expression of L1cam, whereas the high level of phosphorylated Akt in SGC7901 cells was suppressed by knockdown of L1cam. Moreover, the migration and invasion promoted by L1cam overexpression in gastric cancer cells could be abolished by either application of LY294002 (a phosphoinositide-3-kinase inhibitor) or knockdown of endogenous Akt by small interfering RNA.ConclusionsOur study demonstrated that L1cam, overexpressed in gastric cancer and associated with poor prognosis, plays an important role in the progression and metastasis of gastric cancer.

Prognostic relevance of BRD7 expression in colorectal carcinoma

BRD7 is a member of bromodomain‐containing protein and was found to be a cofactor of P53. Down‐regulation of BRD7 has been shown in nasopharyngeal carcinoma cell lines and tissues. However, the clinical role of BRD7 in colorectal cancer remains unknown.

Long noncoding RNA XIST expedites metastasis and modulates epithelial–mesenchymal transition in colorectal cancer

Tumor progression and metastasis is the main cause of death in colorectal cancer (CRC). Long noncoding RNAs (lncRNAs) are critical regulators in various diseases including human cancer. In this study, we found that lncRNA XIST was overexpressed in CRC cell lines and tissues. High expression of lncRNA XIST was associated with adverse overall survival in CRC patients. Knockdown of lncRNA XIST remarkably inhibited CRC cell proliferation, invasion, epithelial–mesenchymal transition (EMT) and CRC stem cell formation in vitro as well as tumor growth and metastasis in vivo. Further study indicated that knockdown of lncRNA XIST markedly increased the expression of microRNA-200b-3p (miR-200b-3p) that has been found to be downregulated in CRC tissues and cell lines, and luciferase activity assay indicated that lncRNA XIST could bind directly with miR-200b-3p. Moreover, knockdown of lncRNA XIST significantly reduced the expression of ZEB1, which was the direct target of miR-200b-3p, and the tumor suppressive effects caused by knockdown of lncRNA XIST could be rescued by re-expression of ZEB1 in CRC cells. Overall, our study demonstrated how lncRNA XIST regulates CRC progression and metastasis by competing for miR-200b-3p to modulate the expression of ZEB1. lncRNA XIST may be used as a biomarker to predict prognosis in CRC patients.

Redox Regulation of Stem-like Cells Though the CD44v-xCT Axis in Colorectal Cancer: Mechanisms and Therapeutic Implications.

Colorectal cancer (CRC) is a common neoplastic disease and a frequent cause of death. Drug resistance is a major challenge to CRC treatment and stem-like side-population (SP) cells may play a key role in this resistance. Although it has been recognized that cancer stem cells may be affected by redox status, the underlying mechanisms for this effect and the roles of celllular redox adaptation and antioxidant capacity in CRC remain elusive. Our study shows that CRC SP cells are highly dependent on cellular GSH to maintain ROS levels below those of non-SP cells. Exposing CRC cells to H2O2 produced a significant decrease in the percentage of SP cells, which was rescued by adding N-acetylcysteine. Mechanistically, CD44v interacts with and stabilizes xCT and thereby promotes the uptake of cysteine for GSH synthesis and stimulates SP cell enrichment. Additionally, miR-1297 levels were inversely correlated with the expression of xCT; thus, reduced miR-1297 contributes to SP cell enrichment in CRC tumors, which results in tumor aggressiveness and poor clinical outcomes. Importantly, redox modification by PEITC significantly reduces CRC SP cells in vitro and impairs tumors growth in vivo. The combination of 5FU and PEITC led to synergistic cytotoxic effects against CRC cells in vitro and in vivo. Taken together, our data suggest that a GSH-mediated reduction in cellular ROS levels is an essential regulator of CRC SP cells mediated by the CD44v-xCT axis, and disrupting the redox status may eliminate the chemotherapy-resistant CRC SP cells with potentially significant benefits for cancer treatment.