Cells isolated from many types of human cancers express heparin-binding growth factors (HBGFs) that drive tumor growth, metastasis, and angiogenesis. The heparan sulfate proteoglycan glypican-1 (GPC1) is a coreceptor for HBGFs. Here we show that both cancer cell-derived and host-derived GPC1 are crucial for efficient growth, metastasis, and angiogenesis of human and mouse cancer cells. Thus downregulation of GPC1 in the human pancreatic cancer cell line PANC-1, using antisense approaches, resulted in prolonged doubling times and decreased anchorage-independent growth in vitro as well as attenuated tumor growth, angiogenesis, and metastasis when these cells were transplanted into athymic mice. Moreover, athymic mice that lacked GPC1 exhibited decreased tumor angiogenesis and metastasis following intrapancreatic implantation with either PANC-1 or T3M4 human pancreatic cancer cells and fewer pulmonary metastases following intravenous injection of murine B16-F10 melanoma cells. In addition, hepatic endothelial cells isolated from these mice exhibited an attenuated mitogenic response to VEGF-A. These data indicate that cancer cell-and host-derived GPC1 are crucial for full mitogenic, angiogenic, and metastatic potential of cancer cells. Thus targeting GPC1 might provide new avenues for cancer therapy and for the prevention of cancer metastasis.

Pancreatic ductal adenocarcinomas (PDACs) exhibit multiple molecular alterations and overexpress heparin binding growth factors (HBGFs) and glypican-1 (GPC1), a heparan sulfate proteoglycan that promotes efficient signaling by HBGFs. It is not known, however, whether GPC1 plays a role in genetic mouse models of PDAC. Therefore, we generated a GPC1 null mouse that combines pancreas-specific Cre-mediated activation of oncogenic Kras (KrasG12D) with deletion of a conditional INK4A/Arf allele (Pdx1-Cre;LSL-KrasG12D;INK4A/Arflox/lox;GPC1-/- mice). By comparison with Pdx1-Cre;LSL-KrasG12D;INK4A/Arflox/lox mice that were wild-type for GPC1, the Pdx1-Cre;LSL-KrasG12D;INK4A/Arflox/lox;GPC1-/- mice exhibited attenuated pancreatic tumor growth and invasiveness, decreased cancer cell proliferation and mitogen activated protein kinase (MAPK) activation. These mice also exhibited suppressed angiogenesis in conjunction with decreased expression of mRNAs encoding several pro-angiogenic factors and molecules, including vascular endothelial growth factor-A (VEGF-A), SRY-box containing gene (SOX17), chemokine C-X3-C motif ligand 1 (CX3CL1), and integrin β3 (ITGB3). Moreover, pancreatic cancer cells isolated from the tumors of GPC1-/- mice were not as invasive in response to fibroblast growth factor-2 (FGF-2) as cancer cells isolated from wild-type mice, and formed smaller tumors that exhibited an attenuated metastatic potential. Similarly, vascular endothelial growth factor-A (VEGF-A) and FGF-2 did not enhance the migration of hepatic endothelial cells and immortalized murine embryonic fibroblasts isolated from GPC1 null mice. These data demonstrate in an oncogenic Kras-driven genetic mouse model of PDAC that tumor growth, angiogenesis and invasion are enhanced by GPC1, and suggest that suppression of GPC1 may be an important component of therapeutic strategies in PDAC.

Background:Melanoma, the most lethal form of skin cancer, is responsible for over 80% of all skin cancer deaths and is highly metastatic, readily spreading to the lymph nodes or metastasising to other organs. The frequent genetic mutation found in metastatic melanoma, BRAFV600E, results in constitutive activation of the mitogen-activated protein kinase pathway.Methods:In this study, we utilised genetically engineered melanoma cell lines and xenograft mouse models to investigate how BRAFV600E affected cytokine (IL-1β, IL-6, and IL-8) and matrix metalloproteinase-1 (MMP-1) expression in tumour cells and in human dermal fibroblasts.Results:We found that BRAFV600E melanoma cells expressed higher levels of these cytokines and of MMP-1 than wild-type counterparts. Further, conditioned medium from the BRAFV600E melanoma cells promoted the activation of stromal fibroblasts, inducing expression of SDF-1 and its receptor CXCR4. This increase was mitigated when the conditioned medium was taken from melanoma cells treated with the BRAFV600E specific inhibitor, vemurafenib.Conclusions:Our findings highlight the role of BRAFV600E in activating the stroma and suggest a mechanistic link between BRAFV600E and MMP-1 in mediating melanoma progression and in activating adjacent fibroblasts in the tumour microenvironment.