Ras, protein kinase C zeta, and I kappa B kinases 1 and 2 are downstream effecters of CD44 during the activation of NF-kappa B by hyaluronic acid fragments in T-24 carcinoma cells

We have investigated the ability of hyaluronic acid (HA) fragments to activ ate the transcription factor NF-kappa B, HA fragments activated NF-kappa B in the cell lines T-24, HeLa, MCF7, and J774, Further studies in T-24 cells demonstrated that HA fragments also induced I kappa B alpha phosphorylatio n and degradation, kappa B-linked reporter gene expression, and ICAM-1 prom oter activity in an NF kappa B-dependent manner. The effect of HA was size dependent as neither disaccharide nor native HA were active. CD44, the prin cipal cellular receptor for HA, was critical for the response because the a nti-CD44 Ab IM7.8.1 blocked the effect on NF-kappa B, HA fragments activate d the I kappa B kinase complex, and the effect on a kappa B-linked reporter gene was blocked in T-24 cells expressing dominant negative I kappa B kina ses 1 or 2. Activation of protein kinase C (PKC) was required because calph ostin C inhibited NF-kappa B activation and I kappa B alpha phosphorylation , In particular, PKC zeta was required because transfection of cells with d ominant negative PKC zeta blocked the effect of HA fragments on kappa B-lin ked gene expression and HA fragments increased PKC zeta activity. Furthermo re, damnacanthal and manumycin A, two mechanistically distinct inhibitors o f Ras, blocked NF-kappa B activation, Transfection of T-24 cells with domin ant negative Ras (RasN17) blocked HA fragment-induced kappa B-linked report er gene expression, and HA fragments activated Ras activity within 5 min. T aken together, these studies establish a novel signal transduction cascade eminating from CD44 to pas, PKC zeta, and I kappa B kinase 1 and 2, The Jou rnal of Immunology, 2000, 164: 2053-2063.