PTP1B promotes aggressiveness of breast cancer cells by regulating PTEN but not EMT.

Metastasis is a complicated, multistep process and remains the major cause of cancer-related mortality. Exploring the molecular mechanisms underlying tumor metastasis is crucial for development of new strategies for cancer prevention and treatment. In this study, we found that protein tyrosine phosphatase 1B (PTP1B) promoted breast cancer metastasis by regulating phosphatase and tensin homolog (PTEN) but not epithelial-mesenchymal transition (EMT). By detecting PTP1B expression of the specimens from 128 breast cancer cases, we found that the level of PTP1B was higher in breast cancer tissues than the corresponding adjacent normal tissues. Notably, PTP1B was positively associated with lymph node metastasis (LNM) and estrogen receptor (ER) status. In vitro, disturbing PTP1B expression obviously attenuated cell migration and invasion. On the contrary, PTP1B overexpression significantly increased migration and invasion of breast cancer cells. Mechanistically, PTP1B knockdown upregulated PTEN, accompanied with an abatement of AKT phosphorylation and the expression of matrix metalloproteinase 2 (MMP2) and MMP7. Conversely, forced expression of PTP1B reduced PTEN and increased AKT phosphorylation as well as the expression of MMP2 and MMP7. Notably, neither EMT nor stemness of breast cancer cells was regulated by PTP1B. We also found that PTP1B acted as an independent prognostic factor and predicted poor prognosis in ER-positive breast cancer patients. Taken together, our findings provide advantageous evidence for the development of PTP1B as a potential therapeutic target for breast cancer, especially for ER-positive breast cancer patients.

Tumour-associated macrophages secrete pleiotrophin to promote PTPRZ1 signalling in glioblastoma stem cells for tumour growth.

Intense infiltration of tumour-associated macrophages (TAMs) facilitates malignant growth of glioblastoma (GBM), but the underlying mechanisms remain undefined. Herein, we report that TAMs secrete abundant pleiotrophin (PTN) to stimulate glioma stem cells (GSCs) through its receptor PTPRZ1 thus promoting GBM malignant growth through PTN-PTPRZ1 paracrine signalling. PTN expression correlates with infiltration of CD11b+/CD163+ TAMs and poor prognosis of GBM patients. Co-implantation of M2-like macrophages (MLCs) promoted GSC-driven tumour growth, but silencing PTN expression in MLCs mitigated their pro-tumorigenic activity. The PTN receptor PTPRZ1 is preferentially expressed in GSCs and also predicts GBM poor prognosis. Disrupting PTPRZ1 abrogated GSC maintenance and tumorigenic potential. Moreover, blocking the PTN-PTPRZ1 signalling by shRNA or anti-PTPRZ1 antibody potently suppressed GBM tumour growth and prolonged animal survival. Our study uncovered a critical molecular crosstalk between TAMs and GSCs through the PTN-PTPRZ1 paracrine signalling to support GBM malignant growth, indicating that targeting this signalling axis may have therapeutic potential.

miR-663 Suppresses Oncogenic Function of CXCR4 in Glioblastoma.

PURPOSE: To identify the miRNA regulators of C-X-C motif chemokine receptor 4 (CXCR4) and the underlying mechanism as well as the therapeutic and prognostic values in human glioblastoma (GBM). EXPERIMENTAL DESIGN: miRNA profile analyses and bioinformatics predictions were used to identify the mediators of CXCR4, which were confirmed by luciferase reporter assay, Western blot assay and immunohistochemistry. The effects of miR-663 on CXCR4-mediated GBM malignancy were investigated by gain-of-function experiments. Orthotopic xenografts derived from constitutive or induced miR-663-expressing GBM cells were used to determine the antitumor effects of miR-663 and CXCR4-specific antagonist AMD3100. Bivariate correlation analyses were used to examine the correlation of miR-663 and CXCR4 levels in glioma. The prognostic values of miR-663 and CXCR4 were examined in 281 cases of astrocytic glioma from our hospital and 476 cases of GBM from The Cancer Genome Atlas database using the multivariate Cox regression analysis and Kaplan-Meier analysis. RESULTS: miR-663 negatively regulated CXCR4 expression by targeting its coding sequence in GBM and compromised the proliferative and invasive capacities of GBM cells induced by CXCR4 overexpression. Constitutive or induced miR-663 overexpression combined with CXCR4 antagonist AMD3100 suppressed orthotopic GBM growth and prolonged tumor-bearing mice survival. Clinically, miR-663 and CXCR4 were inversely correlated in GBM and composed a valuable biomarker set in predicting the outcomes of GBM patients. CONCLUSIONS: miR-663 negatively regulated CXCR4 to inhibit its oncogenic effect. Combination of miR-663 and CXCR4 can serve as a valuable prognostic biomarker set as well as molecular targets for therapeutic intervention of GBM.