CXCR4 and its ligand CXCL12 can promote the proliferation, survival, and invasion of cancer cells. They have been shown to play an important role in regulating metastasis of breast cancer to specific organs. High CXCR4 expression was also correlated to poor clinical outcome. Previous study also showed that tumor cells express a high level of CXCR4 and that tumor metastasis target tissues (lung, liver, and bone) express high levels of the ligand CXCL12, allowing tumor cells to directionally migrate to target organs via a CXCL12-CXCR4 chemotactic gradient. However, the exact mechanisms of how CXCR4 and CXCL12 enhance metastasis and/or tumor growth and their full implications on breast cancer progression are unknown. Yet it is likely that chemokine receptor signaling may provide more than just a migrational advantage by also helping the metastasized cells establish and survive in secondary environments. In this study, we investigated CXCR4 and CXCL12 expression in breast cancer and analyzed its association with clinicopathological factors by immunohistochemistry first. Then, we detected the mRNA and protein expression of CXCR4 and CXCL12 in breast cancer cell lines by Western blot and RT-PCR. The MDA-MB-231 has CXCR4 expression and very weak CXCL12 expression. So, we constructed the functional CXCL12 expression in MDA-MB-231 using a gene transfection technique. Further experiments were conducted to evaluate the effect of CXCL12 transfection on the biological behaviors of MDA-MB-231. The cell proliferation of MDA-MB-231–CXCL12 was accessed by MTT assay; the apoptosis was analyzed by an AnnexinV-FITC/propidium iodide double staining of flow cytometry method; and the cell invasive ability was examined by Matrigel invasion assay. Immunohistochemical analysis showed the co-expression of CXCR4 and CXCL12 correlated with lymph node metastasis and TNM stage (p < 0.01). It suggested that the chemokine CXCL12 and its sole ligand CXCR4 play important role in the malignance of breast cancer. To gain a deeper insight into it, we picked CXCR4-expressing cells MDA-MB-231 to be transfected with CXCL12 stably. The decreased cellular proliferation, increased apoptosis, and invasive ability were found in MDA-MB-231 with successful CXCL12 transfection (p < 0.05). Our findings underlined the CXCL12-CXCR4 axis correlated tightly with breast cancer metastasis. CXCL12-CXCR4 axis can increase the invasion and apoptosis of MDA-MB-231 simultaneously. These data strongly support the hypothesis that CXCL12-CXCR4 axis promotes the natural selection of breast cancer cell metastasis. Our findings could have significant implications in terms of breast cancer aggressiveness and the effectiveness of targeting the receptors and downstream signaling pathways for the treatment of breast cancer.

Transmembrane protein 88 (TMEM88) is a transmembrane protein that plays a crucial role in regulating human stem cell differentiation and embryonic development. However, its expression and clinicopathologic significance in human neoplasms is unclear. In this study, the expression and subcellular localizations of TMEM88 were assessed in 214 cases of non-small cell lung cancer (NSCLC). Notably, TMEM88 was highly expressed in the cytosol of $60% NSCLC specimens examined. Higher expression of cytosolic TMEM88 in NSCLC correlated significantly with poor differentiation, high TNM stage, lymph node metastasis, and inferior survival. In NSCLC cells displaying membrane-localized TMEM88, we observed an inhibition of canonical Wnt signaling due to interactions of TMEM88 with the Wnt pathway factor Dishevelled (DVLS). In contrast, NSCLC cells with cytosol-localized TMEM88 lacked effects on Wnt signaling. Cytosolic interactions of TMEM88 and DVLS increased the expression of phosphorylated, active forms of p38, GSK3b (Thr390), and Snail, thereby reducing the expression of the tight junction-associated proteins ZO-1 and occludin, effects associated with enhanced invasive and metastatic cell characters. Importantly, attenuating the expression of cytosolic TMEM88 reduced metastatic prowess in xenograft models. Overall, our findings show how mislocalization of TMEM88 to the cytosol in NSCLC cells ablates its Wnt pathway regulatory properties, thereby promoting invasion and metastasis by activating the p38-GSK3b-Snail signaling pathway. Cancer Res; 75(21); 4527-37. Ó2015 AACR.

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BackgroundDisorders of cell adhesion are critical steps in cancer progression in which varieties of markers including cadherins are involved in.Btbd7 was found to inhibit E-cadherin expression in MDCK cells and play important roles during branching morphogenesis of embryonic salivary glands and lungs. However its function in malignant tumors is largely unknown. The aim of this study is to investigate the clinicopathological significance and possible function of Btbd7 in non-small cell lung cancer.MethodsImmunohistochemistry and Western blotting were used to investigate Btbd7 expression in non-small cell lung cancer and lung tissues. The clinicopathological association and the overall survival was analyzed. In vitro experiments were performed using siRNA to investigate the function of Btbd7 in lung cancer cells.ResultsBtbd7 expression was elevated in non-small cell lung cancer tissues compared to normal lung tissues. Increased Btbd7 expression was significantly associated with lymph node metastasis, reduced E-cadherin expression and patients’ poor clinical outcome. Downregulation of Btbd7 expression in lung cancer cells by siRNA significantly inhibits cancer cell invasion and effectively restores E-cadherin expression in cancer cell membrane.ConclusionsBtbd7 contributes to reduced expression of E-cadherin and may be a promising cancer marker in non-small cell lung cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-704) contains supplementary material, which is available to authorized users.

Our previous studies indicate that abnormal expression of several Wnt signaling molecules including Axin, Dvl and β-catenin are involved in proliferation, invasion and metastasis of lung cancer. Zbed3 was found to inhibit function of Axin-GSK3β complex and thus lead to accumulation of β-catenin in NIH3T3 and HEK293T cells. However its function in malignant tumors is largely unknown. Here we investigate the clinico-pathological significance of Zbed3 expression and its function in non-small cell lung cancer. We use immunohistochemistry and Western blotting to examine Zbed3 expression in non-small cell lung cancer and lung tissues. Transfection of siRNA and plasmid was used to study the function of Zbed3 in lung cancer cells in vitro. We found Zbed3 expression was elevated in cancer tissues compared to normal lung tissues. Increased Zbed3 expression is significantly associated with lymph node metastasis, advanced TNM stages, higher Ki67 status and patients' poor clinical outcome. Higher Zbed3 expression was also found in lung cancer cell lines compared to bronchial epithelial cell line HBE. Downregulation of Zbed3 by siRNA significantly inhibits cancer cell proliferation and invasion in vitro. Downregulation of Zbed3 also significantly inhibits expression of β-catenin, downstream molecules of Wnt signaling and P120ctn-1 in lung cancer cells. These results suggest that Zbed3 may contribute to lung cancer cell invasion through regulating β-catenin and p120ctn-1 and may be a promissing cancer marker in non-small cell lung cancer.