Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Medical Oncology, Hematology and Bone Marrow Transplantation, Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Anticancer Agents Med Chem. 2021;21(1):108-119. doi: 10.2174/1871520620666200817101533.
The intertwining between cancer pathogenesis and aberrant expression of either oncogenes or tumor suppressor proteins ushered the cancer therapeutic approaches into a limitless road of modern therapies. For the nonce and among the plethora of promising anticancer agents, intense interest has focused on pioglitazone, a first in-class of Thiazolidinedione (TZD) drugs that is currently used to treat patients with diabetes.
Intrigued by the overexpression of PPARγ in Acute Promylocytic Leukemia (APL), this study was designed to investigate the effects of pioglitazone in APL-derived NB4 cells.
To assess the anti-leukemic effect of pioglitazone on myeloid leukemia cell lines, we used MTT and trypan blue assays. Given the higher expression level of PPARγ in NB4 cells, we then expanded our experiments on this cell line. To ascertain the molecular mechanism action of pioglitazone in APL-derived NB4 cells, we evaluated the expression levels of a large cohort of target genes responsible for the regulation of apoptosis, autophagy and cell proliferation. Afterward, to examine whether there is a correlation between PPARγ and the PI3K signaling pathway, the amount of Akt phosphorylation was evaluated using western blot analysis.
Our results showed that pioglitazone exerted its cytotoxic effect in wild-type PTEN-expressing NB4 cells, but not in leukemic K562 cells harboring mutant PTEN; suggesting that probably this member of TZD drugs induced its anti-leukemic effects through a PTEN-mediated manner. Moreover, we found that not only pioglitazone reduced the survival rate of NB4 through the induction of p21-mediated G1 arrest, also elevated the intracellular level of Reactive Oxygen Species (ROS) which was coupled with upregulated FOXO3a. Notably, this study proposed for the first time that the stimulation of autophagy as a result of the compensatory activation of PI3K pathway may act as a plausible mechanism through which the anti-leukemic effect of pioglitazone may be attenuated; suggestive of the application of either PI3K or autophagy inhibitors along with pioglitazone in APL.
By suggesting a mechanistic pathway, the results of the present study shed more light on the favorable anti-leukemic effect of pioglitazone and suggest it as a promising drug that should be clinically investigated in APL patients.
癌症发病机制与癌基因或肿瘤抑制蛋白异常表达的交织，使癌症治疗方法进入了现代治疗的无限道路。目前，在众多有前途的抗癌药物中，人们对吡格列酮（一种噻唑烷二酮（TZD）类的首创药物）产生了浓厚的兴趣，该药物目前用于治疗糖尿病患者。
鉴于急性早幼粒细胞白血病（APL）中 PPARγ 的过表达，本研究旨在研究吡格列酮对 APL 衍生的 NB4 细胞的影响。
为了评估吡格列酮对髓系白血病细胞系的抗白血病作用，我们使用 MTT 和台盼蓝测定法。鉴于 NB4 细胞中 PPARγ 的表达水平较高，我们随后在该细胞系上扩展了实验。为了确定吡格列酮在 APL 衍生的 NB4 细胞中的分子机制作用，我们评估了负责调节凋亡、自噬和细胞增殖的大量靶基因的表达水平。之后，为了检查 PPARγ 与 PI3K 信号通路之间是否存在相关性，我们使用 Western blot 分析评估了 Akt 磷酸化的量。
我们的结果表明，吡格列酮在野生型表达 PTEN 的 NB4 细胞中发挥其细胞毒性作用，但在携带突变型 PTEN 的白血病 K562 细胞中不起作用；这表明该 TZD 药物可能通过 PTEN 介导的方式诱导其抗白血病作用。此外，我们发现，吡格列酮不仅通过诱导 p21 介导的 G1 期阻滞降低了 NB4 的存活率，还增加了活性氧（ROS）的细胞内水平，同时上调了 FOXO3a。值得注意的是，本研究首次提出，PI3K 途径的代偿性激活引起的自噬刺激可能是吡格列酮的抗白血病作用减弱的一种可能机制；提示在 APL 中应用 PI3K 或自噬抑制剂与吡格列酮联合应用。
通过提出一种机制途径，本研究结果更深入地了解了吡格列酮的有利抗白血病作用，并表明它是一种有前途的药物，应在 APL 患者中进行临床研究。
