title: A novel oncogenic role of inositol phosphatase SHIP2 in ER-negative breast cancer stem cells: involvement of JNK/vimentin activation.
abstract: Overexpression of SH2-containing-5'-inositol phosphatase-2 (SHIP2) correlates with poor survival in breast cancer. However, its role in breast cancer stem cells (BCSCs) remains unclear. Here, we showed that the percentage of SHIP2(+) cells was positively correlated with that of CD24(-) CD44(+) cells in 60 breast cancer specimens. Among 20 estrogen receptor (ER)-negative samples, 17 had greater SHIP2 expression in CD24(-) CD44(+) subpopulation than the remaining subpopulation. Data mining of microarray analysis of 295 breast tumors showed a significant correlation of higher SHIP2 expression with distant metastasis. Examination of patient-derived mouse xenografts revealed that SHIP2 protein and its tyrosine 1135 phosphorylation were significantly higher in BCSCs, identified as CD24(-) CD44(+) or aldehyde dehydrogenase (ALDH(+)), than non-BCSCs. SHIP2 silencing or inhibitor of SHIP2 phosphatase significantly decreased mammosphere-forming efficiency, ALDH(+) subpopulation in vitro and tumorigenicity of BCSCs in vivo. Overexpression of SHIP2 enhanced the expression of epithelial-mesenchymal transition markers including vimentin (VIM), which was mainly expressed in ER-negative breast cancer cells with higher level in mammospheres than monolayer culture. Ablation of c-Jun N-terminal kinase 1 (JNK1), JNK2, or VIM diminished the increased ALDH(+) population and tumorigenicity, induced by SHIP2 overexpression. BCSCs displayed greater expression of phospho-JNK than non-BCSCs and silencing of JNK suppressed SHIP2-mediated upregulation of VIM. Furthermore, SHIP2 overexpression enhanced Akt activation, but Akt inhibition failed to influence SHIP2-induced phospho-JNK/VIM upregulation. In conclusion, SHIP2 plays a key role in BCSCs of ER-negative breast cancers through activation of Akt and JNK with upregulation of VIM and may serve as a target for therapy directed at BCSCs.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Genomics Research Center, Academia Sinica, Taipei, Taiwan; Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
authors.forename: Chiung-Hui
authors.initials: CH
authors.lastname: Fu
authors.forename: Ruey-Jen
authors.initials: RJ
authors.lastname: Lin
authors.forename: John
authors.initials: J
authors.lastname: Yu
authors.forename: Wen-Wei
authors.initials: WW
authors.lastname: Chang
authors.forename: Guo-Shiou
authors.initials: GS
authors.lastname: Liao
authors.forename: Wen-Ying
authors.initials: WY
authors.lastname: Chang
authors.forename: Ling-Ming
authors.initials: LM
authors.lastname: Tseng
authors.forename: Yi-Fang
authors.initials: YF
authors.lastname: Tsai
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.forename: Alice L
authors.initials: AL
authors.lastname: Yu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D004789:Enzyme Activation / Q000502:physiology; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D064593:Heterografts; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011960:Receptors, Estrogen / Q000096:biosynthesis; D014746:Vimentin / Q000378:metabolism*
chemical_list: D011960:Receptors, Estrogen; D014746:Vimentin; D048670:MAP Kinase Kinase 4; D010744:Phosphoric Monoester Hydrolases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
keywords: Breast cancer stem cells; JNK; SHIP2; Vimentin