CEACAM6 promotes tumor migration,invasion, and metastasis in gastric cancer

Carcinoembryonic antigen-related cell adhesion molecule 6 （CEACAM6） shows increased expression in a wide variety of human cancers, and its over-expression is associated with enhanced migration, invasion, and in vivo metastasis. Here, we reported that CEACAM6 was up-regulated in gastric cancer （GC） cell lines and tumor tissues. Overexpression of CEACAM6 in MKN-45 and SGC-7901 GC cells promoted migration and invasion in vitro and metastasis in athymic mice, whereas migration and invasion of MKN-28 and SNU-16 GC cells were suppressed by knockdown of CEACAM6. We also observed that steroid receptor coactivator （C-SRC） phosphorylation was increased when CEACAM6 was over-expressed in SGC-7901 cells. Taken together, these results suggested that CEACAM6 functions as an oncoprotein in GC and may be an important metastatic biomarker and therapeutic target.     

胃癌侵袭转移相关基因的研究进展

肿瘤的侵袭转移是恶性肿瘤患者死亡的主要原因。目前对胃癌侵袭转移的分子机制尚未查明。胃癌侵袭转移过程中涉及许多特殊基因,包括促进转移的转移基因和控制转移的转移抑制基因。转移基因有：细胞粘附分子(cAM)基因、基质金属蛋白酶(MMPs)基因、肝素酶(heparanase)基因等;转移抑制基因有：nm23、组织基质金属蛋白酶抑制因子(TIMPs)基因等。本文对胃癌侵袭转移相关基因及其产物的结构、功能及其在侵袭转移过程中作用的研究进展作一综述。     

Overexpression of LI-cadherin in gastric cancer is associated with lymph node metastasis

Gastric cancer remains the second leading cause of cancer deaths worldwide. Patients usually present late with local invasion or metastatic diseases. The present study investigated the expression level of liver-intestine cadherin (LI-cadherin) by RT-PCR and its correlation with clinicopathological data in 71 pairs of tumor and non-cancerous gastric mucosa. Protein expression level of LI-cadherin was determined by Western blotting and immunohistochemistry. The mRNA of LI-cadherin was highly expressed in tumor as compared to non-cancerous mucosa. Lymph node metastasis was significantly associated with the expression of LI-cadherin (p=0.038). On multivariate analysis, T staging and LI-cadherin expression were found to be independent factors associated with lymph node metastasis.     

ARPC4 promotes bladder cancer cell invasion and is associated with lymph node metastasis

The significance of actin-related protein 2/3 complex subunit 4 (ARPC4) expression in bladder cancer, and its potential role in the invasion and migration of bladder cancer cells, has yet to be determined. This study was to identify the correlation between ARPC4 and lymph node metastasis, and to determine the role of ARPC4 in the invasive migration of T24 bladder cancer cells. One hundred and ninety-eight bladder cancer tissues and 40 normal bladder and lymph node tissues were examined. Tissue microarrays were constructed and subjected to immunohistochemical stating for ARPC4. Multiple logistic analysis was used to determine risk factors associated with bladder cancer metastasis. ARPC4 expression in T24 bladder cancer cells was suppressed using small interfering RNA and changes in protein levels were determined by Western blot analysis. The proliferation of bladder cancer cells after knocking down of ARPC4 was determined by cell counting kit-8. The effects of ARPC4 knockdown on T24 cell invasion and migration was determined using transwell and wound healing assays. Immunofluorescence analysis was performed to examine changes in pseudopodia formation and actin cytoskeleton structure. The expression of ARPC4 was elevated in bladder cancer tissues than normal tissues (84.3% vs 27.5%, P < 0.001). The multivariate logistic analysis demonstrated that the level of ARPC4, as a risk factor, was correlated with lymphatic metastasis (P < 0.05). ARPC4 knockdown attenuated proliferation, migration, invasion, and pseudopodia formation in T24 cells. ARPC4 expression, as a risk factor, is associated with lymphatic metastasis and is upregulated in bladder cancer tissues in comparison with normal tissues. Inhibition of ARPC4 expression significantly attenuates the proliferation, migration, and invasion of bladder cancer cell, possibly due to defects in pseudopodia formation.     

上皮间质转化在肿瘤侵袭转移中的研究进展

上皮-间质转化（epithelial-mesenchymal transitions,EMT）是上皮细胞向间质细胞转化的现象,不仅参与胚胎发育和正常生理,还参与许多病理过程。同样EMT也参与肿瘤的发生与发展,尤其在促进肿瘤侵袭转移中发挥着重要作用。研究表明,肿瘤细胞借助EMT方式增强肿瘤细胞迁移和运动能力,促进肿瘤的侵袭与转移。在肿瘤侵袭转移历程中,关于EMT发生的分子调控机制研究已取得了良好的进展,但其详细机制仍然不是十分清楚。本文主要介绍生长因子、转录因子、miRNAs、甲基化及其他调控因子在肿瘤EMT中的调控功能,进一步综述EMT在肿瘤侵袭转移中的作用。     

Epigenetic silencing of DACH1 induces the invasion and metastasis of gastric cancer by activating TGF‐β signalling

Gastric cancer (GC) is the fourth most common malignancy in males and the fifth most common malignancy in females worldwide. DACH1 is frequently methylated in hepatic and colorectal cancer. To further understand the regulation and mechanism of DACH1 in GC, eight GC cell lines, eight cases of normal gastric mucosa, 98 cases of primary GC and 50 cases of adjacent non‐tumour tissues were examined. Methylation‐specific PCR, western blot, transwell assay and xenograft mice were used in this study. Loss of DACH1 expression correlated with promoter region methylation in GC cells, and re‐expression was induced by 5‐Aza‐2′‐deoxyazacytidine. DACH1 is methylated in 63.3% (62/98) of primary GC and 38% (19/50) of adjacent non‐tumour tissues, while no methylation was found in normal gastric mucosa. Methylation of DACH1 correlated with reduced expression of DACH1 (P < 0.01), late tumour stage (stage III/IV) (P < 0.01) and lymph node metastasis (P < 0.05). DACH1 expression inhibited epithelial–mesenchymal transition and metastasis by inhibiting transforming growth factor (TGF)‐β signalling and suppressed GC cell proliferation through inducing G2/M phase arrest. The tumour size is smaller in DACH1‐expressed BGC823 cell xenograft mice than in unexpressed group (P < 0.01). Restoration of DACH1 expression also sensitized GC cells to docetaxel. These studies suggest that DACH1 is frequently methylated in human GC and expression of DACH1 was controlled by promoter region methylation. DACH1 suppresses GC proliferation, invasion and metastasis by inhibiting TGF‐β signalling pathways both in vitro and in vivo. Epigenetic silencing DACH1 may induce GC cells' resistance to docetaxel.     

Overexpression of ZEB1 associated with metastasis and invasion in patients with gastric carcinoma

The aim of this study was to investigate the expression of ZEB1 in gastric carcinoma, its correlation with the clinicopathology of gastric carcinoma, and the role of ZEB1 in invasion and metastasis in gastric carcinoma. ZEB1 expression was analyzed by immunohistochemistry and Western blot in 45 gastric carcinoma tissue samples that contained the adjacent gastric mucosa. The correlation between ZEB1 expression, the occurrence and development of gastric cancer, and clinical pathology was investigated. ZEB1 expression in the human gastric carcinoma cell line AGS was downregulated by RNA interference, and changes in ZEB1 expression corresponded with changes in the invasive and metastatic ability of AGS cells. Immunohistochemistry revealed that ZEB1 protein expression in gastric carcinoma tissues was significantly higher than in normal gastric mucosa tissues (p < 0.001). A lower degree of differentiation of gastric cancer (p = 0.009), a higher TNM (tumor, node, and metastasis) stage (p = 0.010), and a larger scope of invasion were correlated with higher expression of ZEB1 (p = 0.041, 0.002). However, the expression of ZEB1 in gastric carcinoma tissue was independent of gender, age, and tumor size (p > 0.05). Western blot results also showed that ZEB1 protein expression was significantly higher in gastric carcinoma tissue than in the adjacent normal gastric mucosa tissue (p = 0.008). A lower degree of differentiation of the gastric carcinoma correlated with a higher TNM stage, and a larger scope of invasion correlated with increased ZEB1 expression (p = 0.023). Transfection of ZEB1 siRNA in AGS cells significantly decreased the expression level of ZEB1 protein (p = 0.035). Furthermore, the number of cells that could pass through the Transwell chamber was significantly lower in the transfected group than in the non-transfected control group (p = 0.039), indicating that the suppression of ZEB1 expression could significantly reduce the invasive and metastatic ability of AGS cells (p = 0.005). Concluding, in gastric carcinoma tissue, overexpression of ZEB1 may be related to the occurrence and development as well as invasion and metastasis of gastric carcinoma.     

MicroRNA-107, an oncogene microRNA that regulates tumour invasion and metastasis by targeting DICER1 in gastric cancer

MicroRNAs are small non-coding RNA molecules that control expression of target genes. Previous studies showed that microRNA-107 (miR-107) is overexpressed in gastric cancer tissues compared with the matched normal tissues. However, it remains largely unclear as to how miR-107 exerts its function and modulates the malignant phenotypes of gastric cancer, because our understanding of miR-107 signalling pathways is limited. In this study, we demonstrate that miR-107 is frequently up-regulated in gastric cancers and its overexpression is significantly associated with gastric cancer metastasis. Furthermore, silencing the expression of miR-107 could inhibit gastric cancer cell migration and invasion in vitro and in vivo. Subsequent investigation characterized DICER1 as a direct target of miR-107. Up-regulation of DICER1 resulted in a dramatic reduction of in vitro migration, invasion, in vivo liver metastasis of nude mice, which is similar to that occurs with the silencing of miR-107, indicating that DICER1 functions as a metastasis suppressor in gastric cancer. Furthermore, the restoration of DICER1 can inhibit miR-107-induced gastric cancer cell invasion and metastasis. In conclusion, our results suggested that miR-107, an oncogene miRNA promoting gastric cancer metastasis through down-regulation of DICER1. Inhibition of miR-107 or restoration of DICER1 may represent a new potential therapeutic target for gastric cancer treatment.     

Exosomal miRNAs as circulating biomarkers for prediction of development of haematogenous metastasis after surgery for stage II/III gastric cancer

Exosomes secreted by living cancer cells can regulate metastasis. Exosomal miRNAs can reflect pathological conditions of the original cancer cells. Therefore, we aim to identify exosomal miRNAs as circulating biomarkers for haematogenous metastasis of gastric cancer. Pre-treatment serum samples of eighty-nine patients with stage II/III gastric cancer were collected. Thirty-four of them developed haematogenous metastasis after surgery and the other fifty-five did not. Extraction of exosomes was validated by western blot, transmission electron microscopy and nanoparticle tracking analysis. MiRNA qPCR array was performed in three matched pairs of samples. Internal control was selected from PCR array and validated in the remaining samples. Expressions of exosomal miRNAs were evaluated in the remaining samples by RT-qPCR, as well as in gastric cancer tissue samples and cell culture medium. Expression levels of exosomal miRNAs were analysed with clinical characteristics. The results indicated thirteen up-regulated and six down-regulated miRNAs were found after normalization. MiR-379-5p and miR-410-3p were significantly up-regulated in metastatic patients (P < .01). Higher expression of exosomal miR-379-5p or miR-410-3p showed shorter progression-free survival of the patients (P < .05). It was also found that miR-379-5p and miR-410-3p were down-regulated in gastric cancer tissue samples, while they were significantly up-regulated in gastric cancer cell culture medium compared with cancer cells. In conclusion, exosomal miRNAs are promising circulating biomarkers for prediction of development of haematogenous metastasis after surgery for stage II/III gastric cancer.     

Exonuclease 1 expression is associated with clinical progression,metastasis, and survival prognosis of prostate cancer

Prostate cancer (PCa) is the most prevalent malignancy and the second leading cause of cancer-related deaths in the male population in western countries, and we explored the association between exonuclease 1 (EXO1) expression and clinical progression, metastasis (Met), and survival prognosis of PCa. EXO1 expression of high/low-metastatic patient-derived xenografts model was investigated and clinical correlation and prognosis outcomes were validated. EXO1 in high-metastatic models was significantly increased compared with low-metastatic lines. In memorial sloan-kettering cancer center (MSKCC) cohort, EXO1 expression positively correlated with PCa Met, and patients with high EXO1 had poor biochemical recurrence-free survival in primary PCa cohort. Validation in The Cancer Genome Atlas primary cohort indicated EXO1 expression was significantly associated with lymph node Met and disease-free survival. The overexpression of EXO1 is significantly associated with PCa poor survival outcome, and is a promising biomarker for PCa, especially for primary PCa. A prospective study is clearly needed to validate these findings.     

Overexpression of long non-coding RNA RP11-363E7.4 inhibits proliferation and invasion in gastric cancer

LncRNA RP11-363E7.4 has been shown to be downregulated in gastric cancer (GC), while the effect of lncRNA RP11-363E7.4 on GC and its potential molecular mechanisms is unclear. The purpose of this study was to explore the functional role and underlying molecular mechanisms of lncRNA RP11-363E7.4 involved in GC progress.To address the question, quantitative real-time PCR assay was performed to confirm lncRNA RP11-363E7.4 expression levels in GC tissues and cell lines. Cell proliferation, apoptosis, migration and invasion were estimated using Cell Counting Kit-8, colony formation, scratch wound healing and Transwell assays. Potential molecular mechanisms were evaluated using western blot assay. The results showed that lncRNA RP11-363E7.4 was significantly downregulated in GC cell lines and 82 paired tissues. The correlation between expression and clinicopathological features indicated that low expression of lncRNA RP11-363E7.4 was associated with T stage (P = .010). Functional experiments showed that overexpression of lncRNA RP11-363E7.4 prevented proliferation, migration, and invasion and induced apoptosis of GC cells. Western blot assay revealed that lncRNA RP11-363E7.4 functioned via the p53, Bax/Bcl-2, β-catenin pathway. In summary, this study revealed that lncRNA RP11-363E7.4 functioned as a tumour suppressor by inhibiting proliferation, migration, and invasion and inducing apoptosis of GC cells. Significance of the study :LncRNA RP11-363E7.4 has been shown to be downregulated in GC, while the effect of lncRNA RP11-363E7.4 on GC and its potential molecular mechanism is unclear. We revealed that lncRNA RP11-363E7.4 functioned as a tumour suppressor by inhibiting proliferation, migration, and invasion and inducing apoptosis of GC cells. LncRNA RP11-363E7.4 might become an attractive diagnostic and prognostic biomarker of GC and a promising target for GC treatment.     

USP28 contributes to the proliferation and metastasis of gastric cancer

USP28, a member of the deubiquitinating enzymes family, plays a vital role in the physiological process of cell proliferation, differentiation and apoptosis, DNA repair, immune response, and stress response. USP28 has been reported to be overexpressed in bladder cancer, colon cancer, breast carcinomas, and so on. Nevertheless, the role of USP28 in gastric cancer has not yet been investigated. In our study, we examined the USP28 expression in 87 paired samples of gastric cancer and normal gastric tissues. We found that USP28 was overexpressed in gastric cancer compared with normal gastric tissues (P < 0.01), and its overexpression was related to the degree of differentiation and metastases. Inhibiting USP28 expression in vitro suppressed the proliferation and invasion of gastric cancer cells by downregulating lysine specific demethylase 1. On the basis of our data, it can be concluded that USP28 may be a novel therapeutic target for gastric cancer.     

Role of matrix metalloproteinases and their inhibitors in tumor invasion and metastasis

The role of various matrix metalloproteinases (MMP)—such as gelatinases, stromelysins, matrilysin, collagenase-3, and membrane-bound MMP (MB-MMP)—in tumor invasion and metastasis is discussed. Data suggesting significance for malignant growth of the expression level of these enzymes and also of their activators and inhibitors are presented. It is concluded that at different stages of tumor progression the activity of different MMPs is displayed, which is regulated by various growth factors and oncogenes. Different malignancies are characterized by changes in activities of specific MMPs. Data are presented which show significance of the ratio between the MMP activity and that of tissue inhibitors of metalloproteinases (TIMP) in tumor invasion and metastasis, especially in connection with a dual role of TIMP as both MMP inhibitors and activators.     

Cancer-associated adipocytes promote the invasion and metastasis in breast cancer through LIF/CXCLs positive feedback loop

Cancer-associated adipocytes (CAAs), which are adipocytes transformed by cancer cells, are of great importance in promoting the progression of breast cancer. However, the underlying mechanisms involved in the crosstalk between cancer cells and adipocytes are still unknown. Here we report that CAAs and breast cancer cells communicate with each other by secreting the cytokines leukemia inhibitory factor (LIF) and C-X-C subfamily chemokines (CXCLs), respectively. LIF is a pro-inflammatory cytokine secreted by CAAs, which promotes migration and invasion of breast cancer cells via the Stat3 signaling pathway. The activation of Stat3 induced the secretion of glutamic acid-leucine-arginine (ELR) motif CXCLs (CXCL1, CXCL2, CXCL3 and CXCL8) in tumor cells. Interestingly, CXCLs in turn activated the ERK1/2/NF-κB/Stat3 signaling cascade to promote the expression of LIF in CAAs. In clinical breast cancer pathology samples, the up-regulation of LIF in paracancerous adipose tissue was positively correlated with the activation of Stat3 in breast cancer. Furthermore, we verified that adipocytes enhanced lung metastasis of breast cancer cells, and the combination of EC330 (targeting LIF) and SB225002 (targeting C-X-C motility chemokine receptor 2 (CXCR2)) significantly reduced lung metastasis of breast cancer cells in vivo. Our findings reveal that the interaction of adipocytes with breast cancer cells depends on a positive feedback loop between the cytokines LIF and CXCLs, which promotes breast cancer invasion and metastasis.     

卵巢癌侵袭转移机制的生物信息学研究进展

卵巢癌因其侵袭转移特性,致死率极高,居所有妇科恶性肿瘤之首。近年来随着高通量测序技术及生物信息学方法的快速发展,越来越多调控卵巢癌侵袭转移机制的相关生物大分子被发现。本文对卵巢癌侵袭转移机制的研究背景及现状进行了综述,归纳总结了侵袭转移机制相关调控因素,并对蛋白质组学和单细胞组学的生物信息学分析工具及数据库进行了汇总和介绍,以期为卵巢肿瘤细胞侵袭转移机制的深入研究提供理论依据和科研线索。     

Effect of a synthetic cannabinoid agonist on the proliferation and invasion of gastric cancer cells

Although cannabinoids are associated with antineoplastic activity in a number of cancer cell types, the effect in gastric cancer cells has not been clarified. In the present study, we investigated the effects of a cannabinoid agonist on gastric cancer cell proliferation and invasion. The cannabinoid agonist WIN 55,212‐2 inhibited the proliferation of human gastric cancer cells in a dose‐dependent manner and that this effect was mediated partially by the CB₁ receptor. We also found that WIN 55,212‐2 induced apoptosis and down‐regulation of the phospho‐AKT expression in human gastric cancer cells. Furthermore, WIN 55,212‐2 treatment inhibited the invasion of gastric cancer cells, and down‐regulated the expression of MMP‐2 and VEGF‐A through the cannabinoid receptors. Our results open the possibilities in using cannabinoids as a new gastric cancer therapy. J. Cell. Biochem. 110: 321–332, 2010. © 2010 Wiley‐Liss, Inc.