Abstract
Leukemic cells are able to receive and send several signals within bone marrow niche that play an important role in their survival. One of the important crosstalk is the interaction between the bone marrow microenvironment proteins (vitronectin, fibronectin, fibrinogen, and ostepontin) and thyrointegrin αVβ3 on leukemic cells, generating ligand-specific outside-in signals that are relevant to a variety of cell functions, including gene transcription, cell division, cell attachment, and motility
Our previous experiment using in vivo AML animal models with primary AML cells and cell lines have shown significant reduction of leukemic cell burden 74% and >95% (P<0.0001), respectively, after daily subcutaneous treatment with thyrointegrin αvβ3 antagonist fb-PMT (Ki 0.23 nM) at 3 and 10 mg/kg, for 3-4 weeks. In this study we focused on evaluations of the molecular effects of fb-PMT in leukemic cells. Acute myeloid leukemia cell lines (K562-Luc and KG1a cells) were cultured in 50 cm² cell culture flasks with 10 mL phenol red free RPMI media containing 10% fetal bovine albumin. The leukemic cells were treated (at 50% confluence) with 30 µM fb-PMT for 48 hours. Total RNA was immediately isolated from harvested cells using Triazole and used for microarray analysis. Overall, there were 370 significantly down-regulated gene expression records and 273 significantly up-regulated gene expression records, expression of which were changed at least 1.5-fold in fb-PMT-treated human leukemic cells. Significant examples of the fb-PMT-induced gene expression signatures (GES) of pathway's interference include SNAI, MYC, HIF1A, TWIST1, and TFAP2C (P<0.05). Notably, inference of potential contribution to the fb-PMT anticancer activity of the interference with these pathways seems highly congruent with their known biological functions such as cell cycle control (MYC), survival and maintenance of stem cells (HIF1A, TFAP2C), and essential features of the malignant phenotype (TWIST1, SNAI) (Figure 1).
Consistently, examples of the fb-PMT-induced GES of transcriptional pathway's activation include RB1, IRF9, MAML1, RAP1A, and GATA4 pathways (P<0.05), known biological functions of which appear highly consistent with the hypothesis that activation of these pathways might contribute to fb-PMT anticancer activity. Finally, we found that fb-PMT interfered with estrogen signaling in human AML cells. The fb-PMT was associated with decreased phosphorylation and nuclear enrichment of Erα (Figure 1).
Collectively, our in vivo study and genomic data have shown the key role thyrointegrin αvβ3 in leukemogenesis. The thyrointegrin αvβ3 antagonist fb-PMT demonstrated potent anticancer actions on human AML through the molecular interference mechanism with multiple signaling pathways supporting growth and survival of leukemic cells
No relevant conflicts of interest to declare.
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