Mitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect through reactive oxygen species in osteosarcoma

Shuo Ni,Yin Yuan,Yanbin Kuang,Baoqing Yu

doi:10.1186/s12935-020-01494-3

Abstract

BackgroundIron metabolism disorder is closely associated with several malignant tumors, however the mechanisms underlying iron and the carcinogenesis in osteosarcoma are not yet well understood.MethodsCell proliferation ability of osteosarcoma cell lines was measured by CCK-8, EdU incorporation and colony formation assays. Cell cycle analysis was detected by flow cytometry. The carcinogenesis of osteosarcoma was measured by soft-agar formation, trans-well and Wound healing-scratch assay. Warburg effect was detected by Seahorse respirometry assays. Reactive oxygen species (ROS) level was measured by Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescent probes. Western blotting was used to measure the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Iron level in vitro and vivo was detected by iron assay kit. RNAi stable cell lines was generated using shRNA.ResultsIron promoted proliferation, carcinogenesis and Warburg effect of osteosarcoma cells. Iron-induced reactive oxygen species (ROS) played an important role in these processes. Iron accumulated more in mitochondrion than in cytoplasm, suggesting mitochondrion-mediated iron accumulation was involved in the development of osteosarcoma. Moreover, iron upregulated the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Knock-down of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28) decreased the production of ROS. In addition, iron increased the expression of Warburg key enzymes HK2 and Glut1, and affected AMPK/mTORC1 signaling axis.ConclusionsMitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect of osteosarcoma cells. Meanwhile, iron deprivation might be a novel effective strategy in the treatment of osteosarcoma.

Highlights

Iron metabolism disorder is closely associated with several malignant tumors, the mechanisms underlying iron and the carcinogenesis in osteosarcoma are not yet well understood
Iron chelator DFO decreases tumorigenicity in vivo Based on the epidemiological evidences that cancer patient links with an increased body iron storage 28, so we used Deferoxamine (DFO), a chelator used in clinic which could chelate iron efficiently, to explore whether iron was involved in the tumorigenesis of osteosarcoma in vivo (Fig. 1e)
These results indicated that DFO could inhibit the development of osteosarcoma, which implied that iron maybe was involved in the tumorigenesis of osteosarcoma

Summary

Introduction

Iron metabolism disorder is closely associated with several malignant tumors, the mechanisms underlying iron and the carcinogenesis in osteosarcoma are not yet well understood. Iron metabolism is of central importance to numerous biological processes, including DNA replication, cellcycle progression, electron transport chain and microsomal electron transport proteins, as well as the production of iron-sulfur proteins [1, 2]. Mitochondrion is the main consumer of iron in cells for its function of synthesis or assemble many important proteins such as heme and iron sulfur clusters [5, 6]. Accumulating evidence indicates that mitochondrial iron accumulation is associated with human disease such as pulmonary and cardiovascular disorders [9,10,11]. Little is known about the role of mitochondrion-mediated iron accumulation in the initiation and development of malignant tumors

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