Heparanase Promotes the Spontaneous Metastasis of Myeloma Cells to Bone.

Abstract

Although widespread skeletal dissemination is a critical step in the progression of myeloma, little is known regarding mechanisms that control this process. High levels of the syndecan-1 heparan sulfate proteoglycan are present in the myeloma microenvironment where they bind numerous growth factors (e.g., HGF, FGF-2) that control myeloma growth, angiogenesis and dissemination. Heparanase-1 (HPSE1) is an enzyme that cleaves heparan sulfate chains of proteoglycans and thus may regulate heparan-binding growth factor activity. We have previously demonstrated that human myeloma cells express heparanase and that active enzyme is present in the plasma harvested from the marrow of myeloma patients (Cancer Res. 63: 8749–56). In the present study, experiments were performed to determine the effects of enhanced expression of heparanase on myeloma tumor growth and dissemination in vivo. The human myeloma cell line, CAG, was transfected with human HPSE1 cDNA (CAGHPSE1) or with corresponding vector only (CAGNeo). The transfected cells were injected either directly into the tibia or subcutaneously into the flank of severe combined immune deficient (SCID) mice and tumor growth rate, microvessel density and metastasis to bone were analyzed. We discovered that expression of heparanase: (i) accelerates the initial growth of the primary tumor, (ii) increases whole body tumor burden as compared to controls, and (iii) enhances both the number and size of microvessels within the primary tumor. In addition, enhanced expression of heparanase dramatically upregulates spontaneous metastasis of subcutaneously-injected myeloma cells to bone (95% in mice bearing CAGHPSE1 tumors, n = 21; as compared to 6% in mice bearing CAGNeo tumors, n=16). When tumor was injected directly into the tibia, 100% of the mice bearing CAGHPSE1 tumor cells had metastases within the contralateral femur (n=10) while only 29% of the mice bearing CAGNeo tumor had metastases (n=7). These studies describe a novel experimental animal model for examining the spontaneous metastasis of bone-homing tumors and indicate that heparanase is a critical determinant of myeloma dissemination and growth in vivo. Thus, therapeutic modulation of heparanase expression or function may be of value in the treatment of myeloma and other cancers that metastasize to bone.

Mammalian heparanase: what is the message?

“…More convincing, direct evidence for a role of heparanase-1 in tumour metastasis was provided by the conversion of non-metastatic murine T-lymphoma and melanoma cells into highly metastatic cells, following transfection with human heparanase-1 cDNA [53]. Similar results were obtained upon over-expression of human heparanase-1 in pancreatic cancer [120], myeloma [132] and breast carcinoma [134] cells. Enhancement of metastasis was even more pronounced for a readily secreted and membrane-bound chimeric form of the enzyme [135].…”

“…This observation was confirmed by the finding that increased expressions of heparanase-1 mRNA and protein correlate with increased heparanase activity and the metastatic capacity of rat and human breast cancer cells [53,54]. Since then, this correlation has been observed in a variety of human tumour-derived cell lines and tissues, including those of the bladder [119], pancreas [120], cervix [121], colon [122], ovary [123], endometrium [124], prostate [83], thyroid [125], liver [126], oesophagus [110], stomach [109], oral cavity [127], galbladder [128], nasopharynx [129], brain [130], salivary gland [131] and in multiple myeloma [132] and acute myeloid leukaemia [133]. Consistently, as already mentioned above, elevated levels of heparanase-activity have been detected in sera and urine samples of patients suffering from an aggressive metastatic disease [100][101][102].…”

Matrine inhibits invasiveness and metastasis of human malignant melanoma cell line A375 in vitro

“…Several studies have demonstrated that the expression level of heparanase is correlated with the grade, metastatic activity, and growth rate of malignant tumors. [33][34][35][36][37] In the study by Uno et al, 24 heparanase expression was specifically inhibited in a dose-dependent manner when T.Tn human esophageal cancer cells and A549 human lung cancer cells were infected with Ad-AS/hep. As a result, the invasion ability of transfected cells decreased significantly.…”

Cancer and thrombosis: from molecular mechanisms to clinical presentations

“…This enzyme breaks down the polysaccharide barrier, facilitating cancer-cell invasion through the vascular basement membrane; also angiogenesis and metastases are promoted [93]. In humans elevated heparanase expression by the tumor has been correlated with a more aggressive behavior in breast, colon, ovary, pancreas, non-small lung cancer, acute myeloid leukemia, and myeloma tumors [94][95][96][97][98][99][100][101]. Heparanase also cleaves the growth factor bearing heparan sulfate groups from heparan sulfate proteoglycans in the extracellular matrix and cellular membranes [102][103][104].…”