Anti-CA9 polyclonal antibody [Biotin]

Hypoxia has been long-time acknowledged as major cancer-promoting microenvironment. In such an energy-restrictive condition, post-transcriptional mechanisms gain importance over the energy-expensive gene transcription machinery. Here we show that the onset of hypoxia-induced cancer stem cell features requires the beta-catenin-dependent post-transcriptional up-regulation of CA9 and SNAI2 gene expression. In response to hypoxia, beta-catenin moves from the plasma membrane to the cytoplasm where it binds and stabilizes SNAI2 and CA9 mRNAs, in cooperation with the mRNA stabilizing protein HuR. We also provide evidence that the post-transcriptional activity of cytoplasmic beta-catenin operates under normoxia in basal-like/triple-negative breast cancer cells, where the beta-catenin knockdown suppresses the stem cell phenotype in vitro and tumor growth in vivo. In such cells, we unravel the generalized involvement of the beta-catenin-driven machinery in the stabilization of EGF-induced mRNAs, including the cancer stem cell regulator IL6. Our study highlights the crucial role of post-transcriptional mechanisms in the maintenance/acquisition of cancer stem cell features and suggests that the hindrance of cytoplasmic beta-catenin function may represent an unprecedented strategy for targeting breast cancer stem/basal-like cells.

Exosomes or microvesicles that are secreted from cells are considered to play important roles in tumor microenvironment. Carbonic anhydrase 9 (CA9), which is induced by hypoxia-inducible factor 1 (HIF1) in response to hypoxia, is overexpressed in many types of cancer including renal cell carcinoma (RCC). We examined the expression level of CA9 in several RCC cell lines and found that the basal level of CA9 was much higher in OSRC-2 cells than in Caki-1, KMRC-1 and 786-O cells. Consistent with the intracellular expression levels, CA9 was abundantly detected in exosomes isolated by ultracentrifugation from OSRC-2 cells. Density gradient centrifugation of OSRC-2 and 786-O exosomes confirmed the co-presence of CA9 with exosomal markers. Upon hypoxia and treatment with CoCl2, a hypoxia mimic agent, the CA9 level in exosomes was increased for all cell lines. In order to examine the effects of CA9 exosomes on angiogenesis, we generated stably transfected HEK293 cells expressing CA9. Immunocytochemical staining demonstrated the uptake of CA9 exosomes by human umbilical vein endothelial cells (HUVEC). In vitro angiogenesis assays using HUVEC revealed that CA9 exosomes promoted migration and tube formation. Lastly, MMP2 expression was increased by treatment with CA9 exosomes in HUVEC. Taken together, our results suggest the possibility that CA9 exosomes released from hypoxic RCC may enhance angiogenesis in microenvironment, thereby contributing to cancer progression. (C) 2017 Elsevier Inc. All rights reserved.