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目的:研究环腺苷酸(cyclicadenosinemonophosphate,cAMP)对人白血病多药耐药K562/ADM细胞的诱导分化作用。方法:K562/ADM细胞经0.25～2.0mmol/LcAMP处理后,MTT法检测细胞增殖活性,流式细胞术(flowcytometryFCM)检测细胞周期和P-糖蛋白(PglycoproteinPgp)的表达,免疫细胞化学法检测细胞周期蛋白cyclinD1和转录因子E2F的表达;同时观察细胞形态学变化和血红蛋白合成功能。结果:cAMP呈浓度和时间依赖性地抑制K562/ADM细胞的增殖(P<0.01),细胞形态学上出现红系细胞的形态特征;被诱导的细胞能够合成血红蛋白、cyclinD1和E2F的表达减低。cAMP(0.25mmol/L和1.0mmol/L)诱导24h,多数细胞被阻滞在G1期,S期和G2+M期细胞显著降低;诱导72h后K562/ADM细胞Pgp表达的阳性率无明显变化(99.8%～99.9%),但Pgp的表达量显著增加,平均荧光强度分别增高1.24倍和1.28倍。结论:K562/ADM细胞仍保留了分化成熟的潜能,可被cAMP诱导向正常血细胞分化,但在分化诱导过程中,化学诱导剂可导致耐药细胞发生Pgp的应激性表达增强而可能阻抑后续的化学治疗,或对诱导剂产生耐受性。
Objective: To study the effect of cyclic adenosine monophosphate (cAMP) on the differentiation of multidrug-resistant human leukemia K562/ADM cells. METHODS: After K562/ADM cells were treated with 0.25-2.0 mmol/L cAMP, cell proliferation activity was measured by MTT assay, cell cycle and P-glycoprotein (Pglycoprotein Pgp) expression were detected by flow cytometry (FCM), and cells were detected by immunocytochemistry. The expression of cyclin D1 and E2F was studied. Morphological changes and hemoglobin synthesis were also observed. RESULTS: cAMP inhibited the proliferation of K562/ADM cells in a concentration- and time-dependent manner (P<0.01). The morphological features of erythroid cells appeared in the cell morphology, and the expression of hemoglobin and cyclinD1 and E2F in the induced cells decreased. When cells were induced with cAMP (0.25 mmol/L and 1.0 mmol/L) for 24 h, most cells were arrested in G1 phase, and cells in S phase and G2+M phase were significantly decreased; the positive rate of Pgp expression in K562/ADM cells was not significantly changed after 72 h. (99.8%-99.9%), but the expression level of Pgp increased significantly, and the average fluorescence intensity increased by 1.24-fold and 1.28-fold, respectively. CONCLUSION: K562/ADM cells still retain their potential for differentiation and maturation. They can be induced by cAMP to differentiate into normal blood cells. However, during induction of differentiation, chemical inducers may lead to enhanced expression of Pgp in drug-resistant cells and may suppress Subsequent chemotherapy, or tolerance to inducers.