To investigate whether hyaluronan (HA)–CD44 promotes head and neck squamous cell carcinoma (HNSCC) cisplatin resistance and whether HA-CD44 promotes phospholipase C (PLC)–mediated Ca2+ signaling to alter cisplatin sensitivity in HNSCC.
Cell line study.
Main Outcome Measures
Tumor cell growth with the chemotherapeutic drug cisplatin was measured in the presence or absence of HA, anti-CD44 antibody plus HA, and other inhibitors of the PLC-mediated Ca2+ signaling pathway. Ca2+ mobilization was measured with fluorescence spectrophotometry using the Ca2+ binding dye Fura/2AM.
In the absence of HA, cisplatin inhibited tumor cell growth. The addition of HA, but not HA plus anti-CD44 antibody, resulted in a 5-fold reduced ability of cisplatin to cause HNSCC cell death, suggesting that HA can promote CD44-dependent cisplatin resistance. Fluorescence spectrophotometry demonstrated that HA can promote CD44-dependent Ca2+ mobilization in HNSCC. On the other hand, the presence of U73122, a PLC inhibitor, and 2-aminoethoxydiphenyl borate, an inositol-1,4,5-triphosphate receptor inhibitor, eliminated HA-mediated Ca2+ mobilization and HA-mediated cisplatin resistance in these cell lines.
Our results indicate that HA-CD44 signaling influences cisplatin sensitivity in HNSCC cell growth. In particular, HA-CD44 promotion of PLC-mediated Ca2+ signaling plays a role in cisplatin resistance in HNSCC cells. Perturbation of this HA-CD44–mediated signaling pathway may be a promising target to overcome cisplatin resistance in HNSCC.