Eicosapentaenoic Acid And Retinoic Acid On Hl-60 Cell Proliferation And Differentiation Of Functions And Mechanisms

Retinoic acid (RA) has been used in the therapy of acute promyelocyte leukemia (APL) since 1980s. It has been proved that APL can achieve complete remission by RA (especially ATRA) monotherapy. However, APL always relapse and show resistance to RA after the brief remission. Therefore, it is necessary to take ways to improve RA therapy. A series of studies have demonstrated eicosapentaenoic acid (EPA), a kind of n-3 polyunsaturated fafty acids, has many important biologic effects including antitumor. In this paper, it was studied that the effects of all-trans RA (ATRA) and EPA on proliferation and differentiation of HL-60 cells and the corresponding mechanisms. First, flow cytometry and MIT were used to assay the proliferation and apoptosis of HL-60 cells, and cell differentiation was evaluated by NBT reduction experiment. Then, high performance liquid chromatography (HPLC) was taken to analyse RA metabolism in I-IL-60 cells, reverse transcription polymerase chain reaction (RT-PCR) to estimate the mRNA expression of CRABPII, RAR a, and RB. Additionally, the protein expression of RB, caspase-3 and bcl-2 was detected by Western blot. The results showed as follows: (1) EPA inhibited proliferation and induced differentiation and apoptosis of HL-60 cells, and synergistically enhanced these effects induced by RA. (2) EPA slowed RA metabolism in HL-60 cells, and decreased CRABPII mRNA expression induced by RA. (3) The expression of RB mRNA and pRB didn't change in HL-60 cells treated with EPA, whereas it was decreased by the treatment with RA, and significantly decreased by the treatment with EPA in combination of RA. Moreover, the dephosphorylation rate of pRB in HL-60 cells was increased by the treatment with EPA or/and RA. (4) EPA or RA decreased the expression of N-ras mRNA and bcl-2 protein, but up-regulated the levels of caspase-3 protein and RAR a mRNA in HL-60 cells. And these effects enhanced in the cells treated with EPA in combination of RA. These results indicated: (l)EPA can inhibit proliferation of HL-60 cells and induce their differentiation and apoptosis, and synergistically promote these effects induced by RA. (2)The synergistic effects of EPA and RA to HL-60 cells may be mainly mediated by EPA slowing RA metabolism, which may be partly due to the down-regulation of CRABPII expression, and by influencing the expression of N-ras and RB, and the phosphorylation of pRB, etc.