Effect of systemic lupus erythematosus (SLE) treatment drugs on GI-101A breast tumor cell growth

The effect of systemic lupus erythematosus (SLE) treatment drugs on PKC (pr otein kinase C) activity and cell growth was studied using GI-101A breast t umor cells. Both hydroxychloroquine (HCQ) and prednisone treatments signifi cantly increased the PKC activity in GI-101A cells after 60 min. Treatment of cells with a combination of HCQ/prednisone also produced the highest inc rease in PKC activity following 60 min incubation. When the GI-101A cells w ere treated with the same drugs, HCQ (10 ng/ml) prednisone (10 ng/ml) and H CQ/prednisone combination (10 ng/ml of each), for 72 hr the total PKC activ ity in the cells was significantly elevated and consequently the GI-101A ce ll growth was stimulated. As a result of drug induced cell growth stimulati on the total number of cells in the treatment groups increased significantl y compared to the non-treated controls. Interestingly HCQ and prednisone tr eatment induced cell growths were completely blocked by PKC specific inhibi tor chelerythrine (50 mu M). Our results suggest that HCQ and prednisone tr eatment can induce GI-101A cell growth via activating PKC. (C) 2000 Elsevie r Science Inc. All rights reserved.