title: Gelsolin induces promonocytic leukemia differentiation accompanied by upregulation of p21CIP1.
abstract: Tumor suppressor genes have received much attention for their roles in the development of human malignancies. Gelsolin has been found to be down-regulated in several types of human cancers, including leukemias. It is, however, expressed in macrophages, which are the final differentiation derivatives for the monocytic myeloid lineage, implicating this protein in the differentiation process of such cells. In order to investigate the role of gelsolin in leukaemic cell differentiation, stable clones over-expressing ectopic gelsolin, and a control clone were established from U937 leukaemia cells. Unlike the control cells, both gelsolin-overexpressing clones displayed retarded growth, improved monocytic morphology, increased NADPH and NSE activities, and enhanced surface expression of the β-integrin receptor, CD11b, when compared with the parental U937 cells. Interestingly, RT- PCR and western blot analysis also revealed that gelsolin enhanced p21CIP1 mRNA and protein expression in the overexpressing clones. Moreover, transient transfection with siRNA silencing P21CIP1, but not the control siRNA, resulted in a reduction in monocytic differentiation, accompanied by an increase in proliferation. In conclusion, our work demonstrates that gelsolin, by itself, is capable of inducing monocytic differentiation in U937 leukaemia cells, most probably through p21CIP1 activation.
authors.affiliation: Department of Genetics, Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Iran. shirkoohi@tums.ac.ir
authors.forename: Reza
authors.initials: R
authors.lastname: Shirkoohi
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Fujita
authors.forename: Stephanie
authors.initials: S
authors.lastname: Darmanin
authors.forename: Masato
authors.initials: M
authors.lastname: Takimoto
mesh_terms: D039481:CD11b Antigen / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics* / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D018260:Gelsolin / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D009000:Monocytes / Q000378:metabolism* / Q000473:pathology; D009249:NADP / Q000378:metabolism; D010641:Phenotype; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D020298:U937 Cells; D015854:Up-Regulation
chemical_list: D039481:CD11b Antigen; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018260:Gelsolin; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D009249:NADP; D004950:Esterases