Ludescher C, Hilbe W, Eisterer W, Preuss E, Huber C, Gotwald M, Hofmann J, Thaler J
Department of Internal Medicine, University of Innsbruck, Austria.
J Natl Cancer Inst. 1993 Nov 3;85(21):1751-8. doi: 10.1093/jnci/85.21.1751.
Chemoresistance in some hematologic malignancies has been associated with overexpression of P-glycoprotein, which is encoded by the MDR1 gene (also known as PGY1). However, inconsistencies in data on frequency and clinical relevance of multidrug resistance in B-cell chronic lymphocytic leukemia (B-CLL) may reflect a need for improved techniques to detect this overexpression.
Our purpose was to measure P-glycoprotein activity in peripheral blood cells of B-CLL patients and to analyze possible clinical correlations (disease duration, prior treatment, Rai disease stage, lymphocyte counts, and disease progression).
P-glycoprotein activity was assayed in peripheral blood cells of 42 consecutive B-CLL patients (22 treated and 20 untreated). We used dual fluorescence in a flow cytometric assay that detects efflux of the fluorescent dye rhodamine 123, which is transported from the cell by the P-glyprotein pump. Leukemia cells were costained with monoclonal antibody Leu12/CD19, and rhodamine 123 efflux was measured. Expression of MDR1 and MDR3 (also known as PGY3) messenger RNA (mRNA) was quantitatively evaluated by polymerase chain reaction (PCR) in 26 cases.
Marked rhodamine 123 efflux was observed in 34 (81%) of the 42 cases and was abolished in the presence of multidrug resistance inhibitors. Rhodamine 123 efflux was not associated with Rai stage, lymphocyte counts, duration of disease, or disease progression. Although rhodamine 123-negative cases were about equally distributed among untreated and previously treated patients, the percentage of cells with rhodamine 123 efflux was significantly lower for untreated patients than for those treated with chemotherapy regimens including at least one multidrug resistance-associated drug. MDR1 mRNA was detected in 25 of 26 cases and MDR3 mRNA in all 26. MDR1 mRNA expression was significantly correlated with rhodamine 123 efflux, whereas MDR3 mRNA expression was not significantly correlated; MDR1 and MDR3 mRNA expression was not significantly associated with Rai stage, prior treatment, or disease progresssion.
These findings suggest that P-glycoprotein overexpression in B-CLL is intrinsic rather than acquired and that P-glycoprotein activity is enhanced after exposure to multidrug resistance-associated drugs. This enhanced activity does not seem to be associated with more aggressive disease. Our results also indicate that an assay of P-glycoprotein function combined with PCR is suitable for clinical multidrug resistance screening.
Additional studies are needed to determine whether functional activity of P-glycoprotein, measured by rhodamine 123 efflux, is directly related to clinical drug resistance.
某些血液系统恶性肿瘤中的化疗耐药与P-糖蛋白的过表达有关，P-糖蛋白由MDR1基因（也称为PGY1）编码。然而，B细胞慢性淋巴细胞白血病（B-CLL）中多药耐药的频率和临床相关性数据不一致，这可能表明需要改进检测这种过表达的技术。
我们的目的是测量B-CLL患者外周血细胞中的P-糖蛋白活性，并分析可能的临床相关性（疾病持续时间、既往治疗、Rai疾病分期、淋巴细胞计数和疾病进展）。
对42例连续的B-CLL患者（22例接受治疗，20例未接受治疗）的外周血细胞进行P-糖蛋白活性检测。我们在流式细胞术检测中使用双荧光，检测荧光染料罗丹明123的流出，该染料由P-糖蛋白泵从细胞中转运出来。白血病细胞用单克隆抗体Leu12/CD19进行共染色，并测量罗丹明123的流出。在26例患者中通过聚合酶链反应（PCR）定量评估MDR1和MDR3（也称为PGY3）信使核糖核酸（mRNA）的表达。
42例患者中有34例（81%）观察到明显的罗丹明123流出，在存在多药耐药抑制剂的情况下流出被消除。罗丹明123流出与Rai分期、淋巴细胞计数、疾病持续时间或疾病进展无关。虽然罗丹明123阴性病例在未治疗和既往治疗患者中分布大致相同，但未治疗患者中具有罗丹明123流出的细胞百分比明显低于接受包括至少一种多药耐药相关药物的化疗方案治疗的患者。26例患者中有25例检测到MDR1 mRNA，所有26例均检测到MDR3 mRNA。MDR1 mRNA表达与罗丹明123流出显著相关，而MDR3 mRNA表达无显著相关性；MDR1和MDR3 mRNA表达与Rai分期、既往治疗或疾病进展无显著相关性。
这些发现表明B-CLL中P-糖蛋白过表达是内在的而非获得性的，并且在暴露于多药耐药相关药物后P-糖蛋白活性增强。这种增强的活性似乎与更具侵袭性的疾病无关。我们的结果还表明，P-糖蛋白功能检测与PCR相结合适用于临床多药耐药筛查。
需要进一步研究以确定通过罗丹明123流出测量的P-糖蛋白功能活性是否与临床耐药直接相关。
