Effects of hyaluronan on the invasive properties of human breast cancer cells in vitro
Abstract
Hyaluronan (HA) is a high molecular weight glycosaminoglycan present mostly in the extracellular matrix (ECM). HA binds to specific receptors such as CD44. Its production is increased at the tumour–stroma interface, including those in breast cancer tumours. It has been suggested that it facilitates invasion of tumour cells into the ECM by a hydrodynamic effect, or by altering tumour cell behaviour. Using in vitro tests we studied the effect of immobilized (iHA) and soluble (sHA) HA on the invasive properties of four human breast cancer cell lines with different levels of CD44 expression. Our results show that iHA acts as an adhesive, haptotactic, and motility stimulating factor for the CD44 positive Hs578T cells and induces the expression of membrane CD44. sHA also changes the motility properties of the Hs578T and MDA-231 cells and increases their CD44 expression. sHA or iHA have no measurable effect on the adhesion, motility or CD44 expression of the ZR-75–1 and MCF-7 breast cancer cells. Our results establish that in high CD44 expressing breast cancer cells HA modulates tumour cell adhesion and motility and also increases the expression of its own receptor, CD44.
Keywords: hyaluronan, CD44, breast cancer
Introduction
Tumour cell invasion is a three-step process characterized by altered cellular adhesion, cell motility and degradation of the extracellular matrix (ECM). The extracellular environment interacts with tumour cells facilitating, or inhibiting invasion. Hyaluronan (HA) is a glycosaminoglycan present mostly in the extracellular matrix of connective tissues. HA binds to different cellular receptors, such as CD44, generating signals acting on the cytoskeleton (reviewed in Entwistle et al. 1996). CD44 is involved in binding to its HA ligand, followed by its degradation (Culty et al. 1994). Degradation of HA is an important phenomenon, as the intact polymer has different effects than its fragments. Experiments performed both in vitro and in vivo indicate that intact polymer is an important determinant of cell motility (Goebeler et al. 1996; Thomas et al. 1992; Turley 1992; Haddon and Lewis 1991). HA fragments can induce chemokine gene expression (McKee et al. 1996; Horton et al. 1998); production of cytokines (Boyce et al. 1997); up-regulation of immediate early genes such as c-fos and c-jun (Deed et al. 1997); tyrosine kinase activity (Slevin et al. 1998) and activation of the transcriptional regulator, NF kappaB (Noble et al. 1996; McKee et al. 1997). Interestingly, antibodies against CD44, but not against RHAMM or ICAM-1, inhibit HA binding and gene induction in macrophages (McKee et al. 1996). HA fragments of specific length induce angiogenesis (West et al. 1985; West & Kumar 1989a; and West et al. 1989b; Deed et al. 1997).
Tumour cells in breast cancer tumours often express CD44 and the tumour–stroma interface is enriched in HA (Bertrand et al. 1992; de la Torre et al. 1993), but how this might alter tumour cell functions is not well understood. Considering the involvement of CD44 in cell adhesion to HA (Aruffo et al.1990), we hypothesized that HA is an important determinant of breast tumour cells migration. We have previously demonstrated that the Hs578T breast cancer cell line is motile and invasive in in vitro assays and that CD44 is involved in those properties (Herrera-Gayol & Jothy 1999). Therefore, the effect of immobilized (iHA) and soluble HA (sHA) on the invasive properties of four human breast cancer cell lines in vitro was studied, including: adhesion, haptotaxis, motility, CD44 expression and proliferation.
Read More：http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517708/