Changes in the expression of c-myc, RB and tyrosine-phosphorylated proteins during proliferation of NIH 3T3 cells induced by hyaluronic acid

We have shown that hyaluronic acid stimulates the proliferation of quiescent NIH 3T3 cells. We have shown that treatment of 1 mg/ml hyaluronic acid results in increase of tyrosine phosphorylation of two proteins, MW 124 kDa and 60 kDa as detected by anti-tyrosine antibodies by Western blot analysis. Maximum phosphorylation occurred within 2 h after addition of 1 mg/ml hyaluronic acid. Stimulation of proliferation was also accompanied by increase in c-Myc protein, which was inhibited by amiloride, an inhibitor of Na+/H+ antiporter and EGTA and increase in the steady state level of pRb, the RE gene product. These results suggest that the intracellular signal transduction pathways that mediate the stimulatory effects of hyaluronic acid on cellular proliferation are similar to those of growth factors.