促红细胞生成素增加K562细胞转铁蛋白受体的表达及其对细胞周期的影响

目的探讨重组人促红细胞生成素(recombinant human erythroipoitin,rhEPO)和铁对白血病细胞K562转铁蛋白受体(transferrin receptor, TfR)即CD71抗原表达的影响,及其相同处理因素对K562细胞周期变化的影响.方法体外培养K562细胞并加rhEPO等处理因素,分别在24 h和72 h终止处理,各处理组细胞分别与FITC荧光标记的CD71单抗孵育,或与DNA染料碘化丙啶作用.通过流式细胞分析技术检测CD71抗原的表达和细胞周期,观察各组TfR表达情况和S期细胞百分率.结果 (1)不同浓度的rhEPO培养K562细胞72 h,均可使TfR表达增加,与同期空白对照组相比差异有显著意义(P＜0.05).(2)单独使用rhEPO(5 U/ml)或rhEPO(5 U/ml)+FeCl3(100 μmol/L)培养细胞72 h可使S期细胞百分率上升,且与空白对照组相比差异有显著意义(P＜0.05).结论 rhEPO可通过增加白血病细胞转铁蛋白受体的表达而增加DNA的合成.

Erythropoietin increases transferrin receptor expression and the impact of erythropoietin on K562 leukemic cell cycle

OBJECTIVE: Functionally, erythropoietin (EPO) can promote the proliferation and growth of erythroid progenitor cells, and it is widely used in the treatment of anemia in chronic diseases caused by tumor and inflammation. However, it is unclear whether EPO has any effect on tumor cell iron metabolism and tumor cell proliferation. The purpose of this study was to explore the effects of recombinant human EPO (rhEPO) on the expression of transferrin receptor (TfR, CD(71) antigen) of leukemic cell K562 and its relation to cell cycle. METHODS: In vitro culture of K562 cell was performed with additions of various concentrations of rhEPO and Fe. Treatments were terminated at 24 h and 72 h, respectively. Then each group of cells was incubated with FITC-IgG antibody to CD(71) or PI, a kind of DNA dye. And TfR expression and DNA synthesis status were analyzed by flow-cytometry. RESULTS: (1) The expression of TfR by K562 cells increased significantly when incubated for 72 h with different concentrations of rhEPO. The measurement values of 5 U/ml, 10 U/ml and 20 U/ml groups were 12.2 +/- 1.40, 10.7 +/- 0.99 and 11.1 +/- 0.90, respectively. They were markedly increased when compared with that of control group (6.27 +/- 0.11, P < 0.05). (2) When incubated with rhEPO (5 u/ml) alone or combined with FeCl(3) (100 micro mol/L), the percentages of cells in S phase were 51.1% and 59.6%, respectively. They significantly increased when compared with that of control group (42.9%, P < 0.05). CONCLUSIONS: Iron is very important for the proliferation of both normal cells and leukemic cells. It is essential to the activity of ribonucleotide reductase (RR). The authors hypothesized that rhEPO would increase the expression of TfR and intracellular iron content of leukemic cells, which would enhance the DNA synthesis and cell proliferation. Therefore, the clinical application of rhEPO to promote erythropoiesis of cancer patients should be cautious.