Effects Of Insulin-like Growth Factor ? Promotes Adipogenesis In Hemangioma Stem Cells From Infantile Hemangiomas

Objective: Infantile hemangioma(IH)is the most common infantile tumor characterized by initial proliferation in infancy and spontaneous regression within 5-10 years,often leaving fibrous fat residues.At present,the related research on hemangioma at home and abroad mostly focuses on its treatment plan,and there are few reports on the mechanism of occurrence,development and regression of hemangioma.Related studies have found that hemangioma stem cells(Hem SCs)are the source of hemangiomas.However,the specific mechanism by which Hem SCs differentiate into adipocytes is unclear.Insulin-like growth factor 1(IGF-1)is a polypeptide whose expression in most tissues regulates the quality of adipose tissue by regulating fat formation.In the previous study,it was found that IGF-1 is highly expressed in hemangiomas,which provides a new idea for how infantile hemangioblast stem cells can be converted into adipose tissue.The physiological role and signaling pathway between IGF1 and Hem SCs are also studied.It will provide a new theoretical basis for the follow-up study on how to better use drugs to treat infantile hemangiomas.Method:(1)Samples of strawberry hemangioma from infants and young children who are in the proliferative phase within 1 year old,digested and obtained single cell suspension,and Hem SCs were selected by CD133 immunomagnetic beads for culture and passage.(2)CCK-8 method was used to study the effects of different concentrations of IGF-1 on the proliferation of Hem SCs and the growth curves of IGF-1 treated Hem SCs at different times.(3)Immunohistochemistry was used to determine the expression of IGF-1 and IGF-1 receptors in Hem SCs.(4)IGF-1(100 ng/ml),IGF-1(100 ng/ml)+ IGF-1 receptor inhibitor(OSI-906,1 u M),IGF-1(100 ng/ml)+ PI3K inhibitor(LY294002,10 u M),PI3 K inhibitor(LY294002,10 u M)and blank control group were treated with Hem SCs for fat-induced differentiation,and oil red O staining method was used to determine the number and presence of lipid droplets.(5)Western blotting method for the comparison of IGF-1(100 ng/ml),IGF-1(100 ng/ml)+ IGF-1 receptor inhibitor(OSI-906,1 u M),IGF-1(100 ng/ M))PI3K inhibitor(LY294002,10 u M),PI3 K inhibitor(LY294002,10 u M)and blank control group were used to treat adipose conversion factors(C/EBP-?,C/EBP-?,PPAR-?,adiponectin)in Hem SCs,respectively.And the expression of p-AKT and total AKT.Results:(1)IGF-1 at a concentration of 100-200 ng/ml in vitro significantly promoted the proliferation of Hem SCs,and the growth curve confirmed that cells in the 100 ng/ml IGF-1 treatment group increased significantly on day 3-7 compared with the blank group,all with statistical significance(P <0.05).(2)In immunohistochemistry,IGF-1 and IGF-1R were positively expressed in Hem SCs compared with the blank group.(3)After the fat-induced differentiation of different treatment groups of Hem SCs,the results of oil red O staining showed that the number and size of lipid droplets in the cytoplasm of the IGF-1 treatment group were significantly increased compared with the other groups,and the cytoplasmic lipid droplets of the PI3 K inhibitor group.The number was reduced compared to the blank control group.(4)Western blotting results showed that the expression of fat conversion factor(C/EBP-?,C/EBP-?,PPAR-?,adiponectin)in IGF-1 treatment group was significantly higher than that in other groups,the expression levels of adipose transforming factor(C/EBP-?,C/EBP-?,PPAR-?,adiponectin)in Hem SCs were significantly decreased after treatment with IGF-1 plus OSI-906,IGF-2 plus LY294002 and LY294002 group compared with IGF-1 group.The expression levels of fat conversion factors(C/EBP-?,C/EBP-?,PPAR-?,adiponectin)were significantly decreased in the PI3 K inhibitor group compared with the blank control group.The expression of AKT phosphorylation in the IGF-1 treatment group was significantly higher than that in the other groups.The expression of AKT phosphorylation was significantly reduced in the IGF-1 plus OSI-906,IGF-2 plus LY294002 group compared with IGF-1 group.Conclusions: IGF-1 is able to upregulate PPAR-? by activating the IGF-1R and PI3 K pathways,thereby accelerating lipogenesis and enhancing IH Hem SCs adipogenesis.