Down Regulation of Myeloperoxidase (MPO) Gene Induced by Vitamin A or Vitamin D

Abstract

The differentiation-related down regulation of MPO gene was studied in two human myeloid leukemic cell lines. The MPO gene was also strongly expressed in monocytic cell line SKM-1. Exposure of HL-60 or SKM-1 cells to all-trans-retinoic acid (ATRA) resulted in a remarkable decrease of MPO mRNA levels. Tlie MPO mRNA levels in SKM-1 cells decreased faster than those in HL-60 cells after exposure to ATRA. Exposure of HL-60 cells to 1α ,25-dihydroxyvitamin D₃ (1, 25-(OH)₂D₃) resulted in a time-dependent decrease of MPO mRNA levels. While, no decrease of MPO mRNA levels was observed in SKM-1 cells. The increase in c-fms mRNA levels was observed in SKM-1 cells after two days exposure to 1, 25-(OH)₂D₃. The percentage of NBT positive cells in SKM-1 cells was also increasd after 4 days exposure to 1, 25-(OH)₂D₃