Musashi2, A Stem Cell Marker Modulates Human Leukemia Cell Proliferation And Apoptosis Involving The Related Signaling Pathway

Objective Leukemia as a proliferative malignancy derived fromhematopoietic stem cell (HSC), is frequently considered to be caused byleukemia stem cell (LSC). Recent years it’s found that Musashi2(Msi2), apotential LSC marker not only modulated differentiation and developmentof HSC, but also promoted progression of myeloid leukemia and associatedwith poor prognosis in leukemia. Thus, Msi2was regarded as an importantprognostic marker in leukemia. However, the biological functions andunderling mechanisms of Msi2in leukemogenesis was not revealedcompletely. Thus, we would display the role of Msi2in leukemiamalignant transformation in vitro.Methods Adenoviral vectors of RNA interference were constructed toinfect human leukemia K562cells in which Msi2expressed more highly toinvestigate how Msi2silencing modulated leukemia cell proliferation andapoptosis. The effect on leukemia cell growth by Msi2was evaluated byMTT assay. Colony formation ability was detected by methyl cellulose colony formation assay. Leukemia cell cycle was detected by Flowcytometer (FCM). Quantitative PCR and Western blot were used to testmRNA and protein expressions of p21, cyclinD1and cdk2which wereassociated with cell cycle respectively. Leukemia cell apoptosis wasassayed with FCM and Wright-Giemsa Staining. The mRNA and proteinexpressions of Bax and Bcl-2which were related to apoptosis weredetected by Quantitative PCR and Western blot respectively. Expression ofp-ERk and its downstream c-myc, c-fos; p-p38and its downstreamp-MAPKAPK2in MAPK signaling pathway and p-AKT in AKT signalingpathway were examined by Western blot.Results The shRNA adenoviral vectors targeting Msi2wereconstructed successfully to inhibit Msi2expression in human leukemiaK562cells. MTT and colony formation assay demonstrated thatknockdown of Msi2inhibited K562cell proliferation and colony formationability (P＜0.05). Knockdown of Msi2arrested K562cells in G1phase anddecreased cells in S phase (P＜0.05). Downregulation of Msi2induced thep21mRNA and protein expressions but reduced cdk2and cyclinD1expression significantly (P＜0.05). Msi2shRNA promoted K562cellapoptosis by FCM and Wright-Giemsa Stain, activated Bax and decreasedBcl-2expression (P＜0.05). Msi2silencing inhibited activity of p-ERK,c-myc, c-fos and p-p38, p-MAPKAPK2in MAPK signaling pathway otherthan p-AKT. Conclusion Msi2may regulate moleculus related to cell cycle andapoptosis via MAPK signaling pathway to further induce leukemia cellproliferation and reduce cell apoptosis, leading to leukemogenesis. As akey oncogene Msi2may become a potential therapeutic target in leukemia.