Hypoxia, primarily acting through HIF 1a, elicits a wide spectrum of changes in gene expression that con tribute to the metastatic phenotype of cancer cells. Hypoxia and Hif 1a have been shown to upregulate CXCR4 in carcinomas such as lung cancer, oral squamous Ruxolitinib chemical structure cell carcinoma, breast carcinoma, and renal cell carcinoma. The mechanism of Hif 1a regulation of CXCR4 is through direct binding to the CXCR4 promoter. Our results show that HIF 1a also upregulates Inhibitors,Modulators,Libraries CXCR4 in chondrosarcoma. Interest ingly, during chondrogenic differentiation CXCR4 is downregulated. Although chondrosarcoma share some markers of the cartilage phenotype, as cells become malignant, some repressed genes will be reex pressed. CXCR4 has been shown to be involved with cell migration and invasion in many systems.

The data include in vitro invasion and migration assays as well as xenograft models of metastatic disease in which block ade of CXCR4 with drugs, peptides, or antibodies can Inhibitors,Modulators,Libraries inhibit development and growth of metastases. Inhibitors,Modulators,Libraries Indepen dent of CXCR4, MMP1 has also been shown to be involved with tissue invasion and development of metas tases. MMP1 is also known to be upregulated by hypoxia and HIF 1a in breast and lung cancer cells, and also by CXCR4 in Nk cells and pros tate cancer cells. However, this project is the first to link the combined effects of HIF 1a on CXCR4 and MMP1 expression and the indirect effect of HIF 1a on MMP1 expression acting through CXCR4, which inde pendently increases MMP1 in chondrosarcoma cells. The role of MMP1 in chondrosarcoma invasion and its role as a poor prognostic indicator have been known for some time.

Inhibition of MMP1 with siRNA Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries has been shown to decrease chondrosarcoma cell inva sion. We have shown that one mechanism of increased MMP1 in chondrosarcoma is mediated through CXCR4 signaling, which is amplified by hypoxia, and is mediated by ERK, but not other MAP kinases. siRNA directed against HIF 1a, CXCR4, ERK. CXCR4 blockade with AMD3100. or ERK inhibitor U0126 all efficiently inhibited the increase in invasion of chondrosarcoma cells during hypoxia. A previous study of CXCR4 in chondrosarcoma invasion during normoxia showed that CXCR signaling increased expression of alphavbeta3 integrin, also through ERK, and that alphavbeta3 integrin antibodies could also inhibit chon drosarcoma invasion in vitro. Therefore, CXCR4 affects chondrosarcoma invasion through upregulation of multiple genes including alphavbeta3 integrin and MMP1. In other tumors and chondrosarcoma, CXCR4 signaling upregulates other MMPs Z-VAD-FMK chemical structure such as MMP 2, 8 and 9 and 13.