[Effects of beta-carotene and vitamin C on the expression of c-myc in human leukemic cell].

In order to study the effects of beta-carotene and vitamin C(VC) on the expression of c-myc oncogene in human leukemic cell, myelogenous leukemic cell line HL-60 was cultured in vitro with standard methods. Trypan blue exclusion test and Northern blotting hybridization were used to detect the cell proliferation and the expression of c-myc gene. The results showed that the proliferation of HL-60 cell was inhibited after exposed to VC(5, 10, 100 mumol/L) and the occurrence of proliferation was earlier at lower concentration of VC(5 mumol/L). beta-carotene at 10-100 mumol/L could inhibit the proliferation of HL-60 cell in a dose dependent manner. VC(5 mumol/L) had no influence on the expression of c-myc gene(P > 0.05), but beta-carotene could up-regulate the expression of c-myc(P < 0.05). Our observations suggested that the inhibitory effect of beta-carotene on the proliferation of leukemic cells was caused by inducing apoptosis of HL-60 through up-regulating the expression of c-myc gene; however, the inhibitory effect of vitamin C on cell proliferation was not related to the expression of c-myc gene.