The growth inhibitory effects of curcumin (CUR) were evaluated by MTT assay in U937 and CD34 + KG-1 AML cell lines as well as primary CD34 +/CD38 − bone-marrow derived AML cells isolated by MACS technique. The proportion of LSC markers (CD34, CD38 and CD123) were evaluated by flow cytometry. The expression levels of OPN, AKT, mTOR, PTEN, β-catenin and NF-κB were investigated by qRT-PCR. Short interfering RNA (siRNA) against OPN was used in AML cells incubated with or without CUR.
Proportions of CD34 +/CD38 −/CD123 + and CD34 +/CD38 +/CD123 + LSCs compartment co-expressing an increased level of OPN could be enriched in AML cell lines and in patient's primary cells by CUR treatment. The expression levels of AKT, mTOR, PTEN, and β-catenin and NF-κB1, were also significantly up-regulated concurrently with OPN in the enriched CD34 + AML cells.
The increased in CUR-mediated OPN level is involved in a complex interplay of various signaling pathways resulting in cytoprotection and enrichment of CD34 + LSC compartment in CUR-treated AML cells. AKT/mTOR/PTEN/β-catenin/NF-kB signaling pathways may play roles in modulating OPN-mediated LSC cell survival and enrichment.