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Updated: Aug 1, 2025
A Syngeneic Orthotopic Osteosarcoma Sprague Dawley Rat Model with Amputation to Control Metastasis Rate
Published on: May 3, 2021
RING finger gene 180 inhibits osteosarcoma progression through regulating chromobox homolog 4 ubiquitination
Qirui Zhao1, Ning Liu1, Tongtong Xu2
1Department of Orthopedic Joint and Sports Medicine Ward, The First Clinical Hospital affiliated to Harbin Medical University, Harbin, Heilongjiang, China.
Abstract:
Osteosarcoma (OS) is still the most common malignant bone tumor whose etiology remains largely unclear. Here, we aimed to investigate the role of a novel E3 ubiquitin ligase RING finger gene 180 (RNF180) in OS progression. RNF180 was significantly down-regulated in both OS tissues and cell lines. We up-regulated RNF180 using over-expression vector and knocked down RNF180 using specific short hairpin RNAs in OS cell lines. RNF180 over-expression inhibited the viability and proliferation yet promoted apoptosis in OS cells, while RNF180 knockdown showed the opposite effects. RNF180 also suppressed tumor growth and lung metastasis in mouse model, accompanied with elevated E-cadherin level and decreased ki-67 level. Besides, chromobox homolog 4 (CBX4) was predicted as a substrate of RNF180. RNF180 and CBX4 were both localized mainly in nucleus and their interaction was validated. RNF180 aggravated the decline of CBX4 level after cycloheximide treatment. RNF180 also promoted the ubiquitination of CBX4 in OS cells. Furthermore, CBX4 was significantly up-regulated in OS tissues. RNF180 also up-regulated Kruppel like factor 6 (KLF6) yet down-regulated RUNX family transcription factor 2 (Runx2) in OS, which served as downstream targets of CBX4. In addition, RNF180 inhibited migration, invasion and epithelial-mesenchymal transition (EMT) in OS cells, which were partially abolished by CBX4 over-expression. In conclusion, our findings demonstrated that RNF180 inhibits OS development via regulating CBX4 ubiquitination, and RNF180-CBX4 axis is a potential therapeutic target for OS treatment.
Insights
The E3 ubiquitin ligase RING finger gene 180 (RNF180) suppresses osteosarcoma (OS) progression by targeting chromobox homolog 4 (CBX4) for ubiquitination. This RNF180-CBX4 pathway presents a potential therapeutic target for osteosarcoma treatment.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Osteosarcoma (OS) is the most common primary bone malignancy with unclear etiology.
- The role of E3 ubiquitin ligases in OS pathogenesis requires further investigation.
Purpose of the Study:
- To investigate the role of the E3 ubiquitin ligase RING finger gene 180 (RNF180) in osteosarcoma (OS) progression.
- To elucidate the molecular mechanism by which RNF180 influences OS development, focusing on its interaction with chromobox homolog 4 (CBX4).
Main Methods:
- RNF180 expression levels were analyzed in OS tissues and cell lines.
- In vitro and in vivo experiments were conducted using RNF180 overexpression and knockdown models.
- Protein-protein interaction, ubiquitination assays, and Western blotting were employed to study the RNF180-CBX4 axis.
- Tumor growth and metastasis were assessed in a mouse model.
Main Results:
- RNF180 was significantly downregulated in OS tissues and cell lines.
- RNF180 overexpression inhibited OS cell viability, proliferation, tumor growth, and lung metastasis, while promoting apoptosis.
- RNF180 directly interacted with and promoted the ubiquitination of CBX4, leading to its degradation.
- The RNF180-CBX4 axis regulated downstream targets KLF6 and Runx2, affecting epithelial-mesenchymal transition (EMT), migration, and invasion.
Conclusions:
- RNF180 functions as a tumor suppressor in osteosarcoma by inhibiting tumor growth, metastasis, and EMT.
- The RNF180-CBX4 ubiquitination pathway is a critical mechanism in OS development.
- Targeting the RNF180-CBX4 axis offers a promising therapeutic strategy for osteosarcoma.
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