1. Metastatic breast cancer cells overexpress and secrete miR-218 to regulate type I collagen deposition by osteoblasts
- Author
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Liu, Xuxiang, Cao, Minghui, Palomares, Melanie, Wu, Xiwei, Li, Arthur, Yan, Wei, Fong, Miranda Y, Chan, Wing-Chung, and Wang, Shizhen Emily
- Subjects
Biomedical and Clinical Sciences ,Oncology and Carcinogenesis ,Breast Cancer ,Biotechnology ,Genetics ,Cancer ,1.1 Normal biological development and functioning ,2.1 Biological and endogenous factors ,Underpinning research ,Aetiology ,Adult ,Animals ,Bone Marrow Cells ,Bone Neoplasms ,Breast Neoplasms ,Cell Differentiation ,Cell Line ,Tumor ,Circulating MicroRNA ,Collagen Type I ,Collagen Type I ,alpha 1 Chain ,Down-Regulation ,Female ,Humans ,Inhibin-beta Subunits ,Mice ,Mice ,Inbred C57BL ,MicroRNAs ,Middle Aged ,Osteoblasts ,Osteoclasts ,Osteogenesis ,Primary Cell Culture ,Breast cancer ,Bone metastasis ,miRNA ,Cytokines ,Type I collagen ,Oncology & Carcinogenesis ,Oncology and carcinogenesis - Abstract
BackgroundBone is one of the most frequent metastatic sites of advanced breast cancer. Current therapeutic agents aim to inhibit osteoclast-mediated bone resorption but only have palliative effects. During normal bone remodeling, the balance between bone resorption and osteoblast-mediated bone formation is essential for bone homeostasis. One major function of osteoblast during bone formation is to secrete type I procollagen, which will then be processed before being crosslinked and deposited into the bone matrix.MethodsSmall RNA sequencing and quantitative real-time PCR were used to detect miRNA levels in patient blood samples and in the cell lysates as well as extracellular vesicles of parental and bone-tropic MDA-MB-231 breast cancer cells. The effects of cancer cell-derived extracellular vesicles isolated by ultracentrifugation and carrying varying levels of miR-218 were examined in osteoblasts by quantitative real-time PCR, Western blot analysis, and P1NP bone formation marker analysis. Cancer cells overexpressing miR-218 were examined by transcriptome profiling through RNA sequencing to identify intrinsic genes and pathways influenced by miR-218.ResultsWe show that circulating miR-218 is associated with breast cancer bone metastasis. Cancer-secreted miR-218 directly downregulates type I collagen in osteoblasts, whereas intracellular miR-218 in breast cancer cells regulates the expression of inhibin β subunits. Increased cancer secretion of inhibin βA results in elevated Timp3 expression in osteoblasts and the subsequent repression of procollagen processing during osteoblast differentiation.ConclusionsHere we identify a twofold function of cancer-derived miR-218, whose levels in the blood are associated with breast cancer metastasis to the bone, in the regulation of type I collagen deposition by osteoblasts. The adaptation of the bone niche mediated by miR-218 might further tilt the balance towards osteolysis, thereby facilitating other mechanisms to promote bone metastasis.
- Published
- 2018