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Zuo D, Shogren KL, Zang J, Jewison DE, Waletzki BE, Miller AL, Okuno SH, Cai Z, Yaszemski MJ, Maran A. Inhibition of STAT3 blocks protein synthesis and tumor metastasis in osteosarcoma cells. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2018; 37:244. [PMID: 30286779 PMCID: PMC6172747 DOI: 10.1186/s13046-018-0914-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 09/20/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Osteosarcoma is the most common bone cancer. Despite advances, molecular mechanisms associated with osteosarcoma have not been fully understood. Hence, an effective treatment for osteosarcoma has yet to be developed. Even though signal transducer and activator of transcription3 (STAT3) has been implicated, its role in pathogenesis of osteosarcoma is not fully determined. In this study, we investigated the antitumor effect of napabucasin (NP) (BBI608), an inhibitor of STAT3 on osteosarcoma in vitro and in vivo and studied the underlying molecular mechanism. METHODS Cell viability, colony formation, apoptosis, tumor growth and metastasis assays were performed to examine the effect of NP on osteosarcoma in vitro and in vivo. Real-time RT-PCR, western analysis, immunofluorescence and reporter assays were used to monitor the expression and activity of proteins and underlying molecular pathways. Protein synthesis, co-immunoprecipitation and CAP binding assays were carried out to understand NP-mediated mechanism of actions in osteosarcoma cells. RESULTS Our results show that NP treatment decreases cell viability and induces apoptosis in several osteosarcoma cell lines. NP treatment suppresses both expression and phosphorylation of STAT3 in addition to blocking STAT3-mediated transcription and downstream target proteins in osteosarcoma cells. Furthermore, NP inhibits protein synthesis through regulation of the eukaryotic initiation factor 4E (eIF4E) and eIF4E-binding protein 1 (4E-BP1). NP also inhibits the progression of osteosarcoma tumors and metastasis in vivo in an orthotopic tibial model of osteosarcoma. CONCLUSIONS Taken together, our investigation reveals that NP acts through a novel mechanism and inhibits osteosarcoma growth and metastasis, and could be investigated clinically for treating osteosarcoma patients alone or in combination with other drugs.
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Affiliation(s)
- Dongqing Zuo
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.,Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Kristen L Shogren
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA
| | - Jie Zang
- Musculoskeletal Tumor Center, People's Hospital, Peking University, Beijing, 100044, China
| | - Donna E Jewison
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA
| | - Brian E Waletzki
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA
| | | | - Scott H Okuno
- Division of Medical Oncology, Mayo Clinic, Rochester, MN, USA
| | - Zhengdong Cai
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Michael J Yaszemski
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA
| | - Avudaiappan Maran
- Department of Orthopedic Surgery, 2-69 Medical Sciences, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.
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