Arachidonate 15-lipoxygenase is required for chronic myeloid leukemia stem cell survival
Yaoyu Chen, … , Tessa L. Holyoake, Shaoguang Li
Yaoyu Chen, … , Tessa L. Holyoake, Shaoguang Li
Published August 8, 2014
Citation Information: J Clin Invest. 2014;124(9):3847-3862. https://doi.org/10.1172/JCI66129.
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Research Article Oncology

Arachidonate 15-lipoxygenase is required for chronic myeloid leukemia stem cell survival

Abstract

Cancer stem cells (CSCs) are responsible for the initiation and maintenance of some types of cancer, suggesting that inhibition of these cells may limit disease progression and relapse. Unfortunately, few CSC-specific genes have been identified. Here, we determined that the gene encoding arachidonate 15-lipoxygenase (Alox15/15-LO) is essential for the survival of leukemia stem cells (LSCs) in a murine model of BCR-ABL–induced chronic myeloid leukemia (CML). In the absence of Alox15, BCR-ABL was unable to induce CML in mice. Furthermore, Alox15 deletion impaired LSC function by affecting cell division and apoptosis, leading to an eventual depletion of LSCs. Moreover, chemical inhibition of 15-LO function impaired LSC function and attenuated CML in mice. The defective CML phenotype in Alox15-deficient animals was rescued by depleting the gene encoding P-selectin, which is upregulated in Alox15-deficient animals. Both deletion and overexpression of P-selectin affected the survival of LSCs. In human CML cell lines and CD34+ cells, knockdown of Alox15 or inhibition of 15-LO dramatically reduced survival. Loss of Alox15 altered expression of PTEN, PI3K/AKT, and the transcription factor ICSBP, which are known mediators of cancer pathogenesis. These results suggest that ALOX15 has potential as a therapeutic target for eradicating LSCs in CML.

Authors

Yaoyu Chen, Cong Peng, Sheela A. Abraham, Yi Shan, Zhiru Guo, Ngoc Desouza, Giulia Cheloni, Dongguang Li, Tessa L. Holyoake, Shaoguang Li

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Figure 9

Inhibition of Alox15 function induces apoptosis of human CML cell lines.

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Inhibition of Alox15 function induces apoptosis of human CML cell lines....
(A) PD146176 inhibited proliferation of K562 cells. K562 cells were treated with DMSO or PD146176 (5, 10, 15, 20, and 50 μM) for 48 or 96 hours, and live cells were counted. Results represent the mean ± SD. (B) PD146176 induced apoptosis of K562 cells. K562 cells were treated with DMSO or PD146176 (20 μM and 50 μM) for 48 hours. Apoptotic cells (annexin V+7AAD+) were analyzed by FACS. Results represent the mean ± SD. (C) Signaling pathways affected by PD146176. K562 cells were treated with PD146176 for 48 hours, and protein lysates were analyzed by Western blotting. PD146176 induced expression of PTEN, ICSBP, and caspase 9 and reduced expression of β-catenin, PI3K, and AKT, but did not significantly alter expression of BCL2 or BAX. (D) Alox15 knockdown caused growth inhibition of leukemia cells. BV-173 cells were transduced with scramble or Alox15-knockdown shRNA (shAlox15), and the transduced cells were selected with puromycin for 48 hours, followed by culturing the cells (2 × 106 cells per well in a 6-well plate) for 48 hours. At the end of the culture, protein lysates were analyzed by Western blotting for Alox15 expression, and viable cells were counted. Results represent the mean ± SD. (E) Alox15 knockdown induced apoptosis of leukemia cells. BV-173 cells were transduced with Alox15-knockdown shRNA (shAlox15), and the transduced cells were selected with puromycin for 48 hours, followed by culturing the cells for 48 hours. At the end of the culture, cellular apoptosis was assessed by FACS analysis of annexin V+7AAD+ cells. *P < 0.05; **P < 0.01.