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Introduction Stromal cell-derived factor (SDF)-1 (CXC chemokine ligand-12) is a member of the CXC subfamily of chemokines, which, through its cognate receptor (CXC chemokine receptor [CXCR]4), plays an important role in chemotaxis of cancer cells and in tumour metastasis. We conducted the present study to evaluate the effect of SDF-1 on the invasiveness and migration of breast cancer cells, and we analyzed the expression of SDF-1 and its relation to clinicopathological features and clinical outcomes in human breast cancer.

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Our previous studies indicate that phosphatidylinositol 4-kinase IIα can promote the growth of multi-malignant tumors via HER-2/PI3K and MAPK pathways. However, the molecular mechanisms of this pathway and its potential for clinical application remain unknown. In this study, we found that PI4KIIα could be an ideal combinatorial target for EGFR treatment via regulating EGFR degradation. Results showed that PI4KIIα knockdown reduced EGFR protein level, and the expression of PI4KIIα shows a strong correlation with EGFR in human breast cancer tissues (r = 0.77, P < 0.01). PI4KIIα knockdown greatly prolonged the effects and decreased the effective dosage of AG-1478, a specific inhibitor of EGFR. In addition, it significantly enhanced AG1478-induced inhibition of tumor cell survival and strengthened the effect of the EGFR-targeting anti-cancer drug Iressa in xenograft tumor models. Mechanistically, we found that PI4KIIα suppression increased EGFR ligand-independent degradation. Quantitative proteomic analysis by stable isotope labeling with amino acids in cell culture (SILAC) and LC-MS/MS suggested that HSP90 mediated the effect of PI4KIIα on EGFR. Furthermore, we found that combined inhibition of PI4KIIα and EGFR suppressed both PI3K/AKT and MAPK/ERK pathways, and resulted in downregulation of multiple oncogenes like PRDX2, FASN, MTA2, ultimately leading to suppression of tumor growth. Therefore, we conclude that combined inhibition of PI4KIIα and EGFR exerts a multiple anti-tumor effect. Dual inhibition of EGFR at protein and activity level via combinatorial blocking of PI4KIIα presents a novel strategy to combat EGFR-dependent tumors.Electronic supplementary materialThe online version of this article (doi:10.1007/s13238-014-0055-y) contains supplementary material, which is available to authorized users.

Chemotherapy is an important comprehensive treatment for breast cancer, which targets micro-environment of tumors as well as their characterisitcs. A previous microarray analysis revealed that matrix metalloproteinase (MMP)-1 was highly upregulated in carcinoma-associated fibroblasts (CAFs) prior to and following treatment with Taxotere under co-culture conditions. However, whether the chemotherapeutic effects of Taxotere were influenced by the changes in MMP-1 remained unclear. The purpose of the present study was to investigate the impact and mechanism of CAFs in regulating the efficacy of Taxotere on breast cancer cells. CAFs isolated from primary invasive ductal human breast tumors following surgical resection, were used in co-culture with MDA-MB-231 cells to simulate the tumor micro-environment. Following the addition of Taxotere, changes in MMP-1 gene and protein expression were assessed by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Proliferation, invasion and apoptosis assays revealed that when MMP-1 was upregulated in CAFs, the therapeutic efficacy of Taxotere was reduced in breast cancer cells. Chemosensitivity was significantly increased when MMP-1 expression was inhibited by GM6001. In addition, Collagen IV was upregulated in CAFs following chemotherapy and protected breast cancer cells against chemotherapeutic side effects. Collagen IV expression significantly decreased, as well as MMP-1 expression when GM6001 was added. Proliferation and invasion assays demonstrated that the exogenous addition of Collagen IV weakend the chemotherapeutic effect of Taxotere on breast tumor cells. Overall, the results revealed that in CAFs, MMP-1 synergized with Collagen IV as a key gene in regulating the chemotherapeutic effect of Taxotere on breast tumor cells and served an important role in reducing the efficacy of Taxotere on breast cancer, potentially via the transforming growth factor-β signaling pathway. These fidings provide a theoretical basis for the mechanism of CAFs in reducing the chemotherapeutic effect of Taxotere on breast cancer cells and a novel approach for enhancing the chemosensitivity of tumors.

Recently, emerging evidence has suggested that carcinoma-associated fibroblasts (CAFs) could contribute to chemotherapy resistances in breast cancer treatment. The aim of this study is to compare the gene expression profiling of CAFs before and after chemotherapy and pick up candidate genes that might associate with chemotherapy resistance and could be used as predictors of treatment response. CAFs were cultured from surgically resected primary breast cancers and identified with immunohistochemistry (IHC) and Flow cytometry (FCM). MDA-MB-231 cells were cultured as the breast cancer cell line. Cell adhesion assay, invasion assay, and proliferation assay (MTT) were performed to compare the function of MDA-MB-231 cells co-cultured with CAFs and MDA-MB-231 cells without co-culture, after chemotherapy. Totally 6 pairs of CAFs were prepared for microarray analysis. Each pair of CAFs were obtained from the same patient and classified into two groups. One group was treated with Taxotere (regarded as after chemotherapy) while the other group was not processed with Taxotere (regarded as before chemotherapy). According to our study, the primary-cultured CAFs exhibited characteristic phenotype. After chemotherapy, MDA-MB-231 cells co-cultured with CAFs displayed increasing adhesion, invasiveness and proliferation abilities, compared with MDA-MB-231 cells without CAFs. Moreover, 35 differentially expressed genes (absolute fold change >2) were identified between CAFs after chemotherapy and before chemotherapy, including 17 up-regulated genes and 18 down-regulated genes. CXCL2, MMP1, IL8, RARRES1, FGF1, and CXCR7 were picked up as the candidate markers, of which the differential expression in CAFs before and after chemotherapy was confirmed. The results indicate the changes of gene expression in CAFs induced by Taxotere treatment and propose the candidate markers that possibly associate with chemotherapy resistance in breast cancer.