Yongliang Liu1,2, Guiqin Wang1, Jiasi Zhang3, Xue Chen3, Huailong Xu1, Gang Heng1, Jun Chen4, Yongchun Zhao4, Jiatao Li2, Yuanli Ni2, Yingzi Zhang2, Juanjuan Shan5,6, Cheng Qian7,8. 1. Center of Biological Therapy, Southwest Hospital, Army Medical University, Chongqing, China. 2. Center for Precision Medicine of Cancer, Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing, China. 3. Department of Hematology, Southwest Hospital, Army Medical University, Chongqing, China. 4. Chongqing Institute of Precision Medicine and Biotechnology Co., Ltd., Chongqing, China. 5. Center of Biological Therapy, Southwest Hospital, Army Medical University, Chongqing, China. juanjuansh@gmail.com. 6. Center for Precision Medicine of Cancer, Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing, China. juanjuansh@gmail.com. 7. Center of Biological Therapy, Southwest Hospital, Army Medical University, Chongqing, China. cqian8634@gmail.com. 8. Center for Precision Medicine of Cancer, Chongqing Key Laboratory of Translational Research for Cancer Metastasis and Individualized Treatment, Chongqing University Cancer Hospital, Chongqing, China. cqian8634@gmail.com.
Abstract
BACKGROUND: Leukemia stem cells (LSCs) are responsible for the initiation, progression, and relapse of acute myeloid leukemia (AML). Therefore, a therapeutic strategy targeting LSCs is a potential approach to eradicate AML. In this study, we aimed to identify LSC-specific surface markers and uncover the underlying mechanism of AML LSCs. METHODS: Microarray gene expression data were used to investigate candidate AML-LSC-specific markers. CD9 expression in AML cell lines, patients with AML, and normal donors was evaluated by flow cytometry (FC). The biological characteristics of CD9-positive (CD9+) cells were analyzed by in vitro proliferation, chemotherapeutic drug resistance, migration, and in vivo xenotransplantation assays. The molecular mechanism involved in CD9+ cell function was investigated by gene expression profiling. The effects of alpha-2-macroglobulin (A2M) on CD9+ cells were analyzed with regard to proliferation, drug resistance, and migration. RESULTS: CD9, a cell surface protein, was specifically expressed on AML LSCs but barely detected on normal hematopoietic stem cells (HSCs). CD9+ cells exhibit more resistance to chemotherapy drugs and higher migration potential than do CD9-negative (CD9-) cells. More importantly, CD9+ cells possess the ability to reconstitute human AML in immunocompromised mice and promote leukemia growth, suggesting that CD9+ cells define the LSC population. Furthermore, we identified that A2M plays a crucial role in maintaining CD9+ LSC stemness. Knockdown of A2M impairs drug resistance and migration of CD9+ cells. CONCLUSION: Our findings suggest that CD9 is a new biomarker of AML LSCs and is a promising therapeutic target.
BACKGROUND: Leukemia stem cells (LSCs) are responsible for the initiation, progression, and relapse of acute myeloid leukemia (AML). Therefore, a therapeutic strategy targeting LSCs is a potential approach to eradicate AML. In this study, we aimed to identify LSC-specific surface markers and uncover the underlying mechanism of AML LSCs. METHODS: Microarray gene expression data were used to investigate candidate AML-LSC-specific markers. CD9 expression in AML cell lines, patients with AML, and normal donors was evaluated by flow cytometry (FC). The biological characteristics of CD9-positive (CD9+) cells were analyzed by in vitro proliferation, chemotherapeutic drug resistance, migration, and in vivo xenotransplantation assays. The molecular mechanism involved in CD9+ cell function was investigated by gene expression profiling. The effects of alpha-2-macroglobulin (A2M) on CD9+ cells were analyzed with regard to proliferation, drug resistance, and migration. RESULTS: CD9, a cell surface protein, was specifically expressed on AML LSCs but barely detected on normal hematopoietic stem cells (HSCs). CD9+ cells exhibit more resistance to chemotherapy drugs and higher migration potential than do CD9-negative (CD9-) cells. More importantly, CD9+ cells possess the ability to reconstitute human AML in immunocompromised mice and promote leukemia growth, suggesting that CD9+ cells define the LSC population. Furthermore, we identified that A2M plays a crucial role in maintaining CD9+ LSC stemness. Knockdown of A2M impairs drug resistance and migration of CD9+ cells. CONCLUSION: Our findings suggest that CD9 is a new biomarker of AML LSCs and is a promising therapeutic target.
Authors: Jan Krönke; Richard F Schlenk; Kai-Ole Jensen; Florian Tschürtz; Andrea Corbacioglu; Verena I Gaidzik; Peter Paschka; Shiva Onken; Karina Eiwen; Marianne Habdank; Daniela Späth; Michael Lübbert; Mohammed Wattad; Thomas Kindler; Helmut R Salih; Gerhard Held; David Nachbaur; Marie von Lilienfeld-Toal; Ulrich Germing; Detlef Haase; Hans-Günther Mergenthaler; Jürgen Krauter; Arnold Ganser; Gudrun Göhring; Brigitte Schlegelberger; Hartmut Döhner; Konstanze Döhner Journal: J Clin Oncol Date: 2011-05-09 Impact factor: 44.544
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