Abraham Ajay, Varatharajan Savitha, Karathedath Sreeja, Philip Chepsy, Lakshmi Kavitha M, Jayavelu Ashok Kumar, Mohanan Ezhilpavai, Janet Nancy Beryl, Srivastava Vivi M, Shaji Ramachandran V, Zhang Wei, Abraham Aby, Viswabandya Auro, George Biju, Chandy Mammen, Srivastava Alok, Mathews Vikram, Balasubramanian Poonkuzhali
Department of Haematology, Christian Medical College, Vellore, India.
Cytogenetics Unit, Christian Medical College, Vellore, India.
Pharmacogenomics. 2015 Jul;16(8):877-90. doi: 10.2217/pgs.15.44. Epub 2015 Jun 17.
Variation in terms of outcome and toxic side effects of treatment exists among acute myeloid leukemia (AML) patients on chemotherapy with cytarabine (Ara-C) and daunorubicin (Dnr). Candidate Ara-C metabolizing gene expression in primary AML cells is proposed to account for this variation.
Ex vivo Ara-C sensitivity was determined in primary AML samples using MTT assay. mRNA expression of candidate Ara-C metabolizing genes were evaluated by RQPCR analysis. Global gene expression profiling was carried out for identifying differentially expressed genes between exvivo Ara-C sensitive and resistant samples.
Wide interindividual variations in ex vivo Ara-C cytotoxicity were observed among samples from patients with AML and were stratified into sensitive, intermediately sensitive and resistant, based on IC50 values obtained by MTT assay. RNA expression of deoxycytidine kinase (DCK), human equilibrative nucleoside transporter-1 (ENT1) and ribonucleotide reductase M1 (RRM1) were significantly higher and cytidine deaminase (CDA) was significantly lower in ex vivo Ara-C sensitive samples. Higher DCK and RRM1 expression in AML patient's blast correlated with better DFS. Ara-C resistance index (RI), a mathematically derived quotient was proposed based on candidate gene expression pattern. Ara-C ex vivo sensitive samples were found to have significantly lower RI compared with resistant as well as samples from patients presenting with relapse. Patients with low RI supposedly highly sensitive to Ara-C were found to have higher incidence of induction death (p = 0.002; RR: 4.35 [95% CI: 1.69-11.22]). Global gene expression profiling undertaken to find out additional contributors of Ara-C resistance identified many apoptosis as well as metabolic pathway genes to be differentially expressed between Ara-C resistant and sensitive samples.
This study highlights the importance of evaluating expression of candidate Ara-C metabolizing genes in predicting ex vivo drug response as well as treatment outcome. RI could be a predictor of ex vivo Ara-C response irrespective of cytogenetic and molecular risk groups and a potential biomarker for AML treatment outcome and toxicity. Original submitted 22 December 2014; Revision submitted 9 April 2015.
接受阿糖胞苷（Ara-C）和柔红霉素（Dnr）化疗的急性髓系白血病（AML）患者在治疗结果和毒副作用方面存在差异。原发性AML细胞中阿糖胞苷代谢相关候选基因的表达被认为是造成这种差异的原因。
使用MTT法在原发性AML样本中测定阿糖胞苷的体外敏感性。通过RQPCR分析评估阿糖胞苷代谢相关候选基因的mRNA表达。进行全基因组表达谱分析以鉴定体外阿糖胞苷敏感和耐药样本之间的差异表达基因。
在AML患者的样本中观察到体外阿糖胞苷细胞毒性存在广泛的个体差异，并根据MTT法获得的IC50值将其分为敏感、中度敏感和耐药。在体外阿糖胞苷敏感样本中，脱氧胞苷激酶（DCK）、人平衡核苷转运体-1（ENT1）和核糖核苷酸还原酶M1（RRM1）的RNA表达显著更高，而胞苷脱氨酶（CDA）显著更低。AML患者原始细胞中较高的DCK和RRM1表达与更好的无病生存期相关。基于候选基因表达模式提出了阿糖胞苷抗性指数（RI），这是一个通过数学推导得出的商值。发现体外阿糖胞苷敏感样本的RI显著低于耐药样本以及复发患者的样本。据推测对阿糖胞苷高度敏感的低RI患者诱导死亡的发生率更高（p = 0.002；RR：4.35 [95% CI：1.69 - 11.22]）。为找出阿糖胞苷抗性的其他影响因素而进行的全基因组表达谱分析确定了许多凋亡以及代谢途径基因在阿糖胞苷耐药和敏感样本之间存在差异表达。
本研究强调了评估阿糖胞苷代谢相关候选基因表达在预测体外药物反应以及治疗结果方面的重要性。RI可能是体外阿糖胞苷反应的预测指标，与细胞遗传学和分子风险组无关，并且是AML治疗结果和毒性的潜在生物标志物。原始提交于2014年12月22日；修订提交于2015年4月9日。
