2015•Unpublished venueRequires access
Characteristics of therapy-related myeloid neoplasms in breast cancer patients
Che‐Wei Ou, Ming‐Chung Kuo, Tung‐Huei Lin, Yu‐Shu Shih, Po Dunn, Tung‐Liang Lin, Po‐Nan Wang, Jin‐Hou Wu, Chen‐Yu Lai, Der‐Cherng Liang, Lee‐Yung Shih
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Abstract
S186 differentiation. mRNA analysis by qRT-PCR revealed that osteoblast specific genes including osteopontin, TNAP, osteocalcin, and osterix were 5-10 fold up-regulated in AML-MSCs compared to NMSCs before induction. In N-MSCs, the expression of these markers was induced only under osteoblast differentiation conditions. These data indicate that AML-MSCs are primed to differentiate into-osteoblasts. Adipocyte differentiation was assessed by Oil-Red O staining for lipid droplets and revealed a > 95% reduction (p<0.0001) in the number mature adipocytes in AMLMSCs compared to N-MSCs suggesting that AML-MSCs lack the ability to differentiate into adipocytes. To understand the mechanism inducing osteogenic specific differentiation of AML-MSCs, we performed mRNA expression analysis of genes that regulate this process. We found RUNX2, a transcription factor that induces osteogenic but inhibits adipogenic differentiation, was 4-5 fold increased in AML-MSCs compared to N-MSCs. To validate these observations, we co-cultured N-MSCs in the presence or absence of OCI-AML3 cells for 3-5 days and FACS sorted the MSCs for gene expression analysis. We observed a 3-4 fold up-regulation of TNAP protein expression by flow cytometry and 4-6 fold up-regulation of osteoblast specific markers including osteopontin, alkaline phosphatase and osterix in MSCs co-cultured with OCI-AML3 cells. In addition, RUNX2 was up-regulated in MSCs when co-cultured with OCI-AML3 cells. These data suggest that AML cells induce osteogenic differentiation in BM-MSCs by up-regulation of RUNX2. To identify the clinical significance of these observations, we examined the ability of AMLand N-MSCs to protect AML cells from chemotherapy. Co-culture of OCI-AML3 cells with either AMLor N-MSCs and treatment with Cytarabine revealed a 15 4.5% increase in the number of live leukemia cells when cocultured with AML-MSCs compared to N-MSCs. These data indicate that AML-MSCs protect leukemia cells better from chemotherapy than normal MSCs. In conclusion, AML cells induce osteogenic differentiation in MSCs through up-regulation of the RUNX2 transcription factor. Increased chemo-protection of AML cells by AML-MSCs suggests a prominent role of these cells in AML relapse. Targeting RUNX2 and thereby inhibition of osteoblast differentiation of MSCs may provide enhanced treatment options for AML therapy.