Internal Tandem Duplication in FLT3 Attenuates Proliferation and Regulates Resistance to the FLT3 Inhibitor AC220 by Modulating p21Cdkn1a and Pbx1 in Hematopoietic Cells.
Internal Tandem Duplication in FLT3 Attenuates Proliferation and Regulates Resistance to the FLT3 Inhibitor AC220 by Modulating p21Cdkn1a and Pbx1 in Hematopoietic Cells.
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DOI：
10.1371/journal.pone.0158290
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Fukuda S
中科院分区：
文献类型：
--
作者：
Abe M;Pelus LM;Singh P;Hirade T;Onishi C;Purevsuren J;Taketani T;Yamaguchi S;Fukuda S
fms相关酪氨酸激酶3 （FLT3）基因（FLT3-ITD）的内部串联重复（ITD）突变与急性髓性白血病（AML）患者的不良预后相关。由于耐药的发展，很少有FLT3-ITD抑制剂对FLT3-ITD+ AML有效。在这项研究中，我们发现FLT3-ITD激活了一个涉及p21Cdkn1a （p21）和前b细胞白血病转录因子1 （Pbx1）的新途径，该途径减弱了FLT3-ITD细胞的增殖并参与了耐药性的发展。FLT3-ITD上调小鼠骨髓c-kit+- sca -1+- lin - (KSL)细胞和Ba/F3细胞中p21的表达。在FLT3-ITD+细胞中，p21表达的缺失增强了生长因子不依赖的增殖和对阿糖胞苷的敏感性，因为它同时丰富了S+G2/M期群体，并显著增加了Pbx1的表达，而不是Evi-1的表达。当Pbx1在FLT3-ITD+原代骨髓集落形成细胞和Ba/F3细胞中表达沉默时，p21缺失后的细胞增殖增强被部分消除。当FLT3-ITD选择性抑制剂AC220拮抗FLT3-ITD时，p21表达降低，Pbx1 mRNA表达上调，FLT3-ITD+ Ba/F3存活细胞数量迅速下降；然而，细胞最终对AC220变得难治。在FLT3-ITD+ Ba/F3细胞中过表达p21延迟了AC220耐药细胞的出现，而p21沉默则加速了它们的发育。这些数据表明，FLT3-ITD能够通过p21/Pbx1轴抑制FLT3-ITD+细胞的增殖，拮抗FLT3-ITD的治疗通过破坏p21的表达，促进了FLT3-ITD抑制剂对细胞的后续发展。
Internal tandem duplication (ITD) mutations in the Fms-related tyrosine kinase 3 (FLT3) gene (FLT3-ITD) are associated with poor prognosis in patients with acute myeloid leukemia (AML). Due to the development of drug resistance, few FLT3-ITD inhibitors are effective against FLT3-ITD+ AML. In this study, we show that FLT3-ITD activates a novel pathway involving p21Cdkn1a (p21) and pre-B cell leukemia transcription factor 1 (Pbx1) that attenuates FLT3-ITD cell proliferation and is involved in the development of drug resistance. FLT3-ITD up-regulated p21 expression in both mouse bone marrow c-kit+-Sca-1+-Lin- (KSL) cells and Ba/F3 cells. The loss of p21 expression enhanced growth factor-independent proliferation and sensitivity to cytarabine as a consequence of concomitantly enriching the S+G2/M phase population and significantly increasing the expression of Pbx1, but not Evi-1, in FLT3-ITD+ cells. This enhanced cell proliferation following the loss of p21 was partially abrogated when Pbx1 expression was silenced in FLT3-ITD+ primary bone marrow colony-forming cells and Ba/F3 cells. When FLT3-ITD was antagonized with AC220, a selective inhibitor of FLT3-ITD, p21 expression was decreased coincident with Pbx1 mRNA up-regulation and a rapid decline in the number of viable FLT3-ITD+ Ba/F3 cells; however, the cells eventually became refractory to AC220. Overexpressing p21 in FLT3-ITD+ Ba/F3 cells delayed the emergence of cells that were refractory to AC220, whereas p21 silencing accelerated their development. These data indicate that FLT3-ITD is capable of inhibiting FLT3-ITD+ cell proliferation through the p21/Pbx1 axis and that treatments that antagonize FLT3-ITD contribute to the subsequent development of cells that are refractory to a FLT3-ITD inhibitor by disrupting p21 expression.