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Updated: Aug 13, 2025

Intratibial Osteosarcoma Cell Injection to Generate Orthotopic Osteosarcoma and Lung Metastasis Mouse Models
Published on: October 28, 2021
Nuclear receptor modulators inhibit osteosarcoma cell proliferation and tumour growth by regulating the mTOR
Baoshi Yuan1, Kexin Shi1,2, Juanmin Zha3
1Cambridge-Su Genomic Resource Center, Suzhou medical college of Soochow University, Suzhou, Jiangsu, 215123, China.
Abstract:
Osteosarcoma is the most common primary malignant bone tumour in children and adolescents. Chemoresistance leads to poor responses to conventional therapy in patients with osteosarcoma. The discovery of novel effective therapeutic targets and drugs is still the main focus of osteosarcoma research. Nuclear receptors (NRs) have shown substantial promise as novel therapeutic targets for various cancers. In the present study, we performed a drug screen using 29 chemicals that specifically target 17 NRs in several different human osteosarcoma and osteoblast cell lines. The retinoic acid receptor beta (RARb) antagonist LE135, peroxisome proliferator activated receptor gamma (PPARg) antagonist T0070907, liver X receptor (LXR) agonist T0901317 and Rev-Erba agonist SR9011 significantly inhibited the proliferation of malignant osteosarcoma cells (U2OS, HOS-MNNG and Saos-2 cells) but did not inhibit the growth of normal osteoblasts. The effects of these NR modulators on osteosarcoma cells occurred in a dose-dependent manner and were not observed in NR-knockout osteosarcoma cells. These NR modulators also significantly inhibited osteosarcoma growth in vivo and enhanced the antitumour effect of doxorubicin (DOX). Transcriptomic and immunoblotting results showed that these NR modulators may inhibit the growth of osteosarcoma cells by regulating the PI3K/AKT/mTOR and ERK/mTOR pathways. DDIT4, which blocks mTOR activation, was identified as one of the common downstream target genes of these NRs. DDIT4 knockout significantly attenuated the inhibitory effects of these NR modulators on osteosarcoma cell growth. Together, our results revealed that modulators of RARb, PPARg, LXRs and Rev-Erba inhibit osteosarcoma growth both in vitro and in vivo through the mTOR signaling pathway, suggesting that treatment with these NR modulators is a novel potential therapeutic strategy.
Insights
Novel nuclear receptor modulators targeting RARβ, PPARγ, LXRs, and Rev-Erba show promise in inhibiting osteosarcoma growth. These drugs, including LE135 and T0901317, work through the mTOR pathway, offering a new therapeutic strategy for this bone cancer.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Osteosarcoma is the most common primary bone cancer in children and adolescents.
- Chemoresistance limits the effectiveness of current osteosarcoma treatments.
- Nuclear receptors (NRs) are emerging as potential therapeutic targets in cancer treatment.
Purpose of the Study:
- To identify novel therapeutic targets and drugs for osteosarcoma.
- To investigate the efficacy of nuclear receptor modulators in inhibiting osteosarcoma cell proliferation and tumor growth.
- To elucidate the molecular mechanisms underlying the anti-osteosarcoma effects of NR modulators.
Main Methods:
- Drug screening of 29 chemicals targeting 17 NRs in osteosarcoma and osteoblast cell lines.
- In vitro proliferation assays and in vivo tumor growth studies.
- Transcriptomic analysis, immunoblotting, and gene knockout experiments to investigate signaling pathways.
Main Results:
- Specific NR modulators (LE135, T0070907, T0901317, SR9011) inhibited osteosarcoma cell proliferation but not normal osteoblasts.
- These modulators demonstrated dose-dependent effects and efficacy in vivo, enhancing doxorubicin's anti-tumor activity.
- NR modulators regulate PI3K/AKT/mTOR and ERK/mTOR pathways, with DDIT4 identified as a key downstream target.
Conclusions:
- Modulators of RARβ, PPARγ, LXRs, and Rev-Erba inhibit osteosarcoma growth in vitro and in vivo.
- The mTOR signaling pathway is crucial for the anti-osteosarcoma effects of these NR modulators.
- Targeting NRs represents a promising novel therapeutic strategy for osteosarcoma treatment.
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