Positive Feedback Regulation Between Akt Phosphorylation And Fatty Acid Synthase Expression In Osteosarcoma

Objective：To investigate the possible association between the phosphorylation of Akt andFASN expression in human osteosarcoma cell line U2-OS in vitro. As well as thepotential effects of the expression level of p-Akt and FASN on the malignantphenotype of osteosarcoma cell line U2-OS in vitro.Methods：Immunohistochemical staining was conducted on24OS specimens frompatients with pulmonary metastasis. The recombinant plasmid targeting FASN genewas constructed. An inhibitor of PI3K/Akt named LY294002was used in regulationof the expression level of p-Akt. Human U2-OS OS cells were treated withFASN-specific RNAi plasmid or LY294002, and normal U2-OS cells acting asnegative control group. The mRNA levels of Akt and FASN were measured byreal-time PCR. Western blot analysis was also performed to detect the proteinexperession of t-Akt, p-Akt and FASN. MTT assay was performed to examine cellproliferation; Transwell assay and Migration assay was used to evaluate the invasionand migration ability of U2-OS cells, respectively.Results：Immunohistochemical staining showed a significant positive correlation betweenphosphorylated Akt (p-Akt) and the expression of FASN (R=0.469, P=0.04). Theresults of RT-PCR and western blot demonstrated that the PI3K/Akt signalingpathway modulates FASN expression; the inhibition of FASN resulted in thedownregulation of p-Akt in the U2-OS cells. Furthermore, the proliferation assay, theinvasion assay and the migration assay showed us that the effects induced by theinhibition of the activity of p-Akt or FASN on the malignant phenotype of U2-OScells.Conclusion：The findings of our study suggest the existence of a positive feedback regulationbetween Akt phosphorylation and FASN expression and that this loop may play an important role in the malignant phenotype of OS cells.