MicroRNA-33a functions as a bone metastasis suppressor in lung cancer by targeting parathyroid hormone related protein

• Published in: Biochimica et biophysica acta Vol. 1830; no. 6; pp. 3756 - 3766
• Main Authors: Kuo, Po-Lin, Liao, Szi-Hui, Hung, Jen-Yu, Huang, Ming-Shyan, Hsu, Ya-Ling
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2013
• Subjects: Bone Neoplasms - genetics; Bone Neoplasms - metabolism; Bone Neoplasms - pathology; Bone Neoplasms - secondary; bone resorption; Bone Resorption - genetics; Bone Resorption - metabolism; Bone Resorption - pathology; bones; Cell Differentiation - genetics; Cell Line, Tumor; Down-Regulation - genetics; enzyme-linked immunosorbent assay; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; interleukin-8; Interleukin-8 - biosynthesis; Interleukin-8 - genetics; luciferase; Lung cancer; lung neoplasms; Lung Neoplasms - genetics; Lung Neoplasms - metabolism; Lung Neoplasms - pathology; macrophage colony-stimulating factor; metastasis; microRNA; MicroRNAs - biosynthesis; MicroRNAs - genetics; mir-33a; morbidity; neoplasm cells; Neoplasm Metastasis; Neoplasm Proteins - biosynthesis; Neoplasm Proteins - genetics; OPG; osteoblasts; Osteoclastogenesis; osteoclasts; Osteoclasts - metabolism; Osteoclasts - pathology; Osteoprotegerin - biosynthesis; Osteoprotegerin - genetics; parathyroid hormone; Parathyroid Hormone-Related Protein - biosynthesis; Parathyroid Hormone-Related Protein - genetics; patients; plasmids; prognosis; PTHrP; quantitative polymerase chain reaction; RANK Ligand - biosynthesis; RANK Ligand - genetics; RNA, Neoplasm - biosynthesis; RNA, Neoplasm - genetics; secretion; Osteoclastogenesis; RANKL; M-CSF; mir-33a; Lung cancer; OPG; Real-time qRT-PCR; PTHrP
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2013.02.022

Bone is a common site of metastasis for lung cancer, and is associated with significant morbidity and a dismal prognosis. MicroRNAs (miRNAs) are increasingly implicated in regulating the progression of malignancies. The efficacy of miR-33a or anti-miR-33a plasmid was assessed by Real-time PCR. Luciferase assays were using One-Glo Luciferase Assay System. Measurement of secreted factors was determined by ELISA kit. We have found that miR-33a, which is downregulated in lung cancer cells, directly targets PTHrP (parathyroid hormone-related protein), a potent stimulator of osteoclastic bone resorption, leading to decreased osteolytic bone metastasis. We also found that miR-33a levels are inversely correlated with PTHrP expression between human normal bronchial cell line and lung cancer cell lines. The reintroduction of miR-33a reduces the stimulatory effect of A549 on the production of osteoclastogenesis activator RANKL (receptor activator of nuclear factor kappa-B ligand) and M-CSF (macrophage colony-stimulating factor) on osteoblasts, while the expression of PTHrP is decreased in A549 cells. miR-33a overexpression also reduces the inhibitory activity of A549 on the production of OPG (osteoprotegerin), an osteoclastogenesis inhibitor. In addition, miR-33a-mediated PTHrP downregulation results in decreased IL-8 secretion in A549, which contributes to decreased lung cancer-mediated osteoclast differentiation and bone resorption. These findings have led us to conclude that miR-33a may be a potent tumor suppressor, which inhibits direct and indirect osteoclastogenesis through repression of PTHrP. miR-33a may even predict a poor prognosis for lung cancer patients. •miR-33a is downregulated in lung cancer cell lines.•miR-33a regulates the expression of PTHrP.•Overexpression of miR-33a decreases the induction of A549 on the production of RANKL and M-CSF in osteoblasts.•Ectopic expression of miR-33a decreases the stimulatory effect of A549 on osteoclastogenesis.•Knockdown of miR-33a triggers the inductive effect of BEAS-2B on the production of RANKL and M-CSF in osteoblasts.