Dual role of hematopoietic progenitor kinase 1 (HPK1) as a positive regulator of 1α,25-dihydroxyvitamin D-induced differentiation and cell cycle arrest of AML cells and as a mediator of vitamin D resistance
Dual role of hematopoietic progenitor kinase 1 (HPK1) as a positive regulator of 1α,25-dihydroxyvitamin D-induced differentiation and cell cycle arrest of AML cells and as a mediator of vitamin D resistance
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DOI：
10.4161/cc.19765
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发表时间：
2012-04-01
期刊：
影响因子：
4.3
通讯作者：
Studzinski, George P.
中科院分区：
文献类型：
--
作者：
Chen-Deutsch, Xiangwen;Studzinski, George P.
最近旨在通过给予维生素D衍生物改善AML治疗的临床试验显示出不显著的结果，表明患者的AML原始细胞中发生了维生素D耐药性。由于维生素D抵抗的机制尚不清楚，我们研究了40 AF细胞，这是HL 60细胞的一个亚系，可以在1 α，25-二羟基维生素D-3（1，25 D）存在下增殖。我们发现，在40 AF细胞中，上游MAP 4激酶HPK 1的mRNA和蛋白水平显著增加，并且当通过添加鼠尾草酸和p38 MAPK抑制剂SB 202190（DCS鸡尾酒）部分逆转40 AF细胞的1，25 D抗性时，HPK 1蛋白进一步增加。HPK 1基因敲除可降低1，25 D/DCS诱导的HL 60和U937细胞以及1，25 D抗性40 AF细胞的分化，但HPK 1基因敲除对分化相关的G（1）阻滞的影响在抗性细胞中比敏感细胞更明显。为了解释为什么40 AF和固有的维生素D抗性KG-1a细胞可以在维生素D存在下增殖，我们发现40 AF和KG-1a细胞中切割的HPK 1片段（HPK 1-C）水平很高，但是当由DCS诱导分化时，HPK 1-C降低，而全长（FL）-HPK 1增加。因此，用泛半胱天冬酶抑制剂Q-VD-OP h抑制蛋白水解减少了HPK 1裂解并增强了DCS诱导的40 AF细胞分化。结果表明，FL-HPK 1是AML细胞中维生素D诱导分化的正调节因子，但切割的HPK 1片段抑制分化。因此，高HPK 1切割活性有助于维生素D抗性，并且HPK 1在AML细胞分化中具有双重作用。
Recent clinical trials aimed at improved treatment of AML by administration of vitamin D derivatives showed unremarkable results, suggesting development of vitamin D resistance in patients' AML blasts. Since mechanisms of vitamin D resistance are not clear, we studied 40AF cells, a subline of HL60 cells that can proliferate in the presence of 1 alpha,25-dihydroxyvitamin D-3 (1,25D). We found that mRNA and protein levels of HPK1, an upstream MAP4 kinase, are dramatically increased in 40AF cells, and HPK1 protein is further increased when the 1,25D resistance of 40AF cells is partially reversed by the addition of carnosic acid and p38 MAPK inhibitor SB202190 (DCS cocktail). Knockdown of HPK1 reduces 1,25D/DCS-induced differentiation of both 1,25D-sensitive HL60 and U937 cells and 1,25D-resistant 40AF cells, but the effect of HPK1 knockdown on differentiation-associated G(1) arrest is more apparent in the resistant than the sensitive cells. To explain why 40AF and the intrinsically vitamin D-resistant KG-1a cells can proliferate in the presence of vitamin D, we found that the cleaved HPK1 fragment (HPK1-C) level is high in 40AF and KG-1a cells, but when differentiation is induced by DCS, HPK1-C decreases, while full-length (FL)-HPK1 increases. Accordingly, inhibition of proteolysis with the pan-caspase inhibitor Q-VD-OP h reduced HPK1 cleavage and enhanced DCS-induced differentiation of 40AF cells. The results indicate that FL-HPK1 is a positive regulator of vitamin D-induced differentiation in AML cells, but the cleaved HPK1 fragment inhibits differentiation. Thus, high HPK1 cleavage activity contributes to vitamin D resistance, and HPK1 has a dual role in AML cell differentiation.