Hyaluronan Oligosaccharides Inhibit Tumorigenicity of Osteosarcoma Cell Lines MG-63 and LM-8 in Vitro and in Vivo via Perturbation of Hyaluronan-Rich Pericellular Matrix of the Cells

Abstract

Numerous studies have demonstrated a correlation between hyaluronan expression and the malignant properties of various kinds of cancer , and inhibition of hyaluronan production causes decreased tumor growth. Hyaluronan oligosaccharides have been shown to inhibit several tumor cell types via disrup- tion of receptor-hyaluronan interaction. However, few studies have addressed hyaluronan with respect to osteosarcoma. In this study, we examined the ef- fects of exogenously added hyaluronan oligosaccha- rides on tumorigenicity of murine osteosarcoma cells, LM-8, and human osteoblastic osteosarcoma cells, MG-63. Moreover, the critical size of oligomers needed to inhibit malignant properties was defined. Fluorescent hyaluronan oligosaccharides accumu- lated both on the surface of cells and in the cyto- plasm, and this retention was blocked by pretreat- ment with an anti-CD44 monoclonal antibody. Hyaluronan octasaccharides significantly inhibited cell viability and induced apoptosis as defined by cell proliferation and terminal deoxynucleotidyl trans- ferase dUTP nick-end labeling assays, respectively. Octasaccharides also abrogated functional cell-associ- ated matrices and significantly reduced the retention of endogenous hyaluronan. Further, octasaccharide treatment affected an inhibition of cell motility as well as cell invasiveness. Pretreatment of the cells withanti-CD44antibodyreducedtheantitumoreffect of the octasaccharides. In vivo , intratumoral injection of hyaluronan octasaccharides reduced the hyaluronan accumulation in local tumors, resulting in significant suppression of the formation of distant lung metastasis. Together these data suggest that hyaluronan oligosac- charides have potent antitumor effects functioning in part by the abrogation of hyaluronan-rich cell-associated matrices. Originally published American Journal of Pathology, Vol. 171, No. 1, July 2007