Loss of dual-specificity phosphatase-2 promotes angiogenesis and metastasis via up-regulation of interleukin-8 in colon cancer.

Dual-specificity phosphatase 2 (DUSP2) is a negative regulator of mitogen-activated protein kinases. Our previous study showed that DUSP2 expression is down-regulated in many human cancers and loss of DUSP2 promotes cancer progression; however, the underlying mechanism remains largely uncharacterized. Herein, we found that loss of DUSP2 induces angiogenesis, while forced expression of DUSP2 inhibits microvessel formation in xenografted mouse tumours. Genome-wide screening of expression profiles, and meta-analysis of clinical data, identified that the level of interleukin-8 (IL-8) correlated negatively with that of DUSP2, suggesting that it may be a downstream target of DUSP2. Molecular characterization revealed that DUSP2 inversely regulates IL-8 expression, mediated by ERK1/2 and C/EBPα-dependent transcriptional regulation. Further study showed that hypoxia-induced IL-8 expression in cancer cells is also mediated via down-regulation of DUSP2. Treatment with the IL-8 receptor inhibitor reparixin or knockdown of IL-8 in cancer cells abolished angiogenesis induced by loss of DUSP2. Functionally, knockdown of DUSP2 enhanced tumour growth and metastasis, which were abolished by treatment with reparixin or knockdown of IL-8 in an orthotopic mouse model. Taken together, our results demonstrate that hypoxia inhibits DUSP2 expression in colon cancer, leading to up-regulation of IL-8, which facilitates angiogenesis and tumour metastasis. Our findings suggest that blocking hypoxia-DUSP2-IL-8 signalling may be a plausible approach for therapeutic intervention in cancer. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Lin SC ，Hsiao KY ，Chang N ，Hou PC ，Tsai SJ ... -  《-》

Inhibition of dual specificity phosphatase-2 by hypoxia promotes interleukin-8-mediated angiogenesis in endometriosis.

How does hypoxia-mediated down-regulation of dual specificity phosphatase-2 (DUSP2) promote endometriotic lesion development? Inhibition of DUSP2 by hypoxia enhances endometriotic lesion growth via promoting interleukin-8 (IL-8)-dependent angiogenesis. Angiogenesis is a prerequisite for the development of endometriosis. DUSP2 is down-regulated in endometriotic stromal cells in a hypoxia inducible factor-1α-dependent manner. Down-regulation of DUSP2 contributes to the pathological process of endometriosis. A laboratory study recruiting 20 patients of reproductive age with endometriosis and normal menstrual cycles, and an autoimplant-induced mouse model of endometriosis using 13 mice in a 28-day treatment. IL-8 mRNA levels were assayed in endometrial stromal cells maintained in normoxic or hypoxic (1% O2) conditions, with or without DUSP2 knockdown. Promoter activity and chromatin immunoprecipitation (ChIP) assays were conducted to characterize the regulation of IL-8 by DUSP2. Conditioned media from cells maintained in normoxic or hypoxic conditions, and cells with/without DUSP2 knockdown were collected to investigate the angiogenic capacity using an in vitro tube formation assay. Reparixin, an IL-8 receptor blocker, was administered to investigate the role of IL-8 in hypoxia-mediated angiogenesis and the development of endometriotic-like lesions in an autotransplanted mouse model. IL-8 mRNA was increased by both hypoxia and DUSP2 knockdown in endometrial stromal cells in an extracellular signal-regulated protein kinase-dependent manner (P < 0.05 versus control). Promoter activity and ChIP assays demonstrated that expression of IL-8 was regulated by CCAAT/enhancer binding protein α (P < 0.05 versus control). Furthermore, conditioned media collected from hypoxia-exposed or DUSP2 knockdown endometrial stromal cells promoted tube formation, which was abolished by co-treatment with reparixin (P < 0.05 versus control). Results from the autotransplanted mouse model demonstrated that number of blood vessels and size of endometriotic-like lesions were markedly reduced in recipient mice treated with reparixin (P < 0.05 versus control). This study was conducted in primary human cell cultures and a mouse model, therefore may not fully reflect the situation in vivo. This is the first study to highlight the potential application of an IL-8 receptor blocker as a therapeutic target to treat endometriosis. This study demonstrates IL-8 as a key angiogenic factor regulated by hypoxia/DUSP2, which suggests an alternative mechanism through which hypoxia may promote angiogenesis. This study was funded by the National Science Council of Taiwan (NSC101-2314-B-006-043-MY2). The author declares that there is no conflict of interest.

Hsiao KY ，Chang N ，Lin SC ，Li YH ，Wu MH ... -  《-》

Suppression of dual-specificity phosphatase-2 by hypoxia increases chemoresistance and malignancy in human cancer cells.

Lin SC ，Chien CW ，Lee JC ，Yeh YC ，Hsu KF ，Lai YY ，Lin SC ，Tsai SJ ... -  《-》

Hypoxia-Induced Downregulation of DUSP-2 Phosphatase Drives Colon Cancer Stemness.

Cancer stem-like cells (CSC) evolve to overcome the pressures of reduced oxygen, nutrients or chemically induced cell death, but the mechanisms driving this evolution are incompletely understood. Here, we report that hypoxia-mediated downregulation of the dual specificity phosphatase 2 (DUSP2) is critical for the accumulation of CSC in colorectal cancer. Reduced expression of DUSP2 led to overproduction of COX-2-derived prostaglandin E2, which promoted cancer stemness via the EP2/EP4 signaling pathways. Genetic and pharmacological inhibition of PGE2 biosynthesis or signal transduction ameliorated loss-of-DUSP2-induced tumor growth and cancer stemness. Genome-wide profile analysis revealed that genes regulated by DUSP2 were similar to those controlled by histone deacetylase. Indeed, treatment with novel histone deacetylase inhibitors abolished hypoxia-induced DUSP2 downregulation, COX-2 overexpression, cancer stemness, tumor growth, and drug resistance. Our findings illuminate mechanisms of cancer stemness and suggest new cancer therapy regimens. Cancer Res; 77(16); 4305-16. ©2017 AACR.

Hou PC ，Li YH ，Lin SC ，Lin SC ，Lee JC ，Lin BW ，Liou JP ，Chang JY ，Kuo CC ，Liu YM ，Sun HS ，Tsai SJ ... -  《-》

Hypoxia-inhibited DUSP2 expression promotes IL-6/STAT3 signaling in endometriosis.

How does hypoxia-mediated downregulation of dual-specificity phosphatase-2 (DUSP2) promote the development of endometriotic lesions? The levels of IL-6 and DUSP2 were assessed in eutopic stromal cells with DUSP2 knockdown or hypoxia treatment. Bromodeoxyuridine (BrdU) incorporation was applied for evaluating cell proliferation. The protein levels of DUSP2, cleaved caspase-3, phosphorylated STAT3, and STAT3 were analyzed using immunoblot. The genomewide analysis of cells with DUSP2 overexpression indicated IL-6 regulates multiple pathways related to inflammation, proliferation, and apoptosis. DUSP2 overexpression significantly suppressed IL-6 expression, while DUSP2 knockdown promoted IL-6 expression. The hypoxia-treated eutopic stromal cells expressed higher levels of IL-6, recapitulating the elevated levels of IL-6 in ectopic stromal cells. The treatment with IL-6 elicited the phosphorylation of STAT3, mimicking the elevated levels of phosphorylated STAT3 in the ectopic stromal cells. The IL-6-treated eutopic stromal cells showed more BrdU incorporation and less cleaved caspase-3, which can be reversed by STAT3 inhibitor. Hypoxia-induced IL-6 production in endometriotic lesions is mediated via downregulation of DUSP2, which causes aberrant activation of STAT3 signaling pathway and helps the endometriotic cells survive under the ectopic environment.

Hsiao KY ，Chang N ，Tsai JL ，Lin SC ，Tsai SJ ，Wu MH ... -  《-》