Fibulin-4 promotes osteosarcoma invasion and metastasis by inducing epithelial to mesenchymal transition via the PI3K/Akt/mTOR pathway.
This study explored the role of fibulin-4 in osteosarcoma progression and the possible signaling pathway involved. Fibulin-4 mRNA and protein expression in normal tissue, benign fibrous dysplasia, osteosarcoma, osteosarcoma cell lines, the normal osteoblastic cell line hFOB, and different invasive subclones were evaluated by immunohistochemistry (IHC) or immunocytochemistry (ICC) and real-time reverse transcriptase-polymerase chain reaction (real-time qRT-PCR). Using in vitro functional assays, we analyzed the invasive and proliferative abilities of different osteosarcoma cell lines and subclones with differing invasive potential. To assess the role of fibulin-4 in the invasion and metastasis of osteosarcoma cells, lentiviral vectors with fibulin-4 small hairpin RNA (shRNA) and pLVX-fibulin-4 were constructed and used to infect the highly invasive and low invasive subclones and osteosarcoma cell lines. The effects of fibulin-4 knockdown and upregulation on the biological behavior of osteosarcoma cells were investigated by functional in vitro and in vivo assays. The results revealed that fibulin-4 expression was upregulated in osteosarcoma, and was positively correlated with low differentiation, lymph node metastasis, and poor prognosis. Fibulin-4 was also found to be over-expressed in highly invasive cell lines and in the highly invasive subclones. Fibulin-4 could promote osteosarcoma cell invasion and metastasis by inducing EMT via the PI3K/AKT/mTOR pathway. Collectively, our findings demonstrate that fibulin-4 is a promoter of osteosarcoma development and progression, and suggest a novel therapeutic target for future studies.
Department of Orthopedics, Qilu Hospital, Shandong University, Jinan, Shandong 250012, P.R. China.
Dong
D
Zhang
Department of Orthopedics, Qilu Hospital, Shandong University, Jinan, Shandong 250012, P.R. China.
Songgang
S
Wang
Department of Maternal and Child Health, School of Public Health, Shandong University, Jinan, Shandong 250012, P.R. China.
Jie
J
Chen
Department of Orthopedics, Xiangcheng No. 2 People's Hospital, Suzhou, Jiangsu 215143, P.R. China.
Haitao
H
Liu
Department of Orthopedics, Xiangcheng No. 2 People's Hospital, Suzhou, Jiangsu 215143, P.R. China.
Jinfa
J
Lu
Department of Orthopedics, Xiangcheng No. 2 People's Hospital, Suzhou, Jiangsu 215143, P.R. China.
Hua
H
Jiang
Department of Orthopedics, Xiangcheng No. 2 People's Hospital, Suzhou, Jiangsu 215143, P.R. China.
Aimin
A
Huang
Department of Orthopedics, Qilu Hospital, Shandong University, Jinan, Shandong 250012, P.R. China.
Yunzhen
Y
Chen
D000818:Animals; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics*; D018572:Disease-Free Survival; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008297:Male; D051379:Mice; D009361:Neoplasm Invasiveness / Q000235:genetics* / Q000473:pathology; D012516:Osteosarcoma / Q000235:genetics* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
D014408:Biomarkers, Tumor; D016326:Extracellular Matrix Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C403672:EFEMP2 protein, human; C546842:MTOR protein, human