1. Department of Pediatrics, Xinyi people's Hospital, Xinyi, China.
2. Department of Orthopedics, the Second Affiliated Hospital of Soochow University, Suzhou, China.
3. Department of Orthopedics, The Affiliated Jiangyin Hospital of Medical College of Southeast University, Jiangyin, China.
4. Department of Orthopedics, The Affiliated Suqian Hospital of Xuzhou Medical University, Suqian, China.
5. Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, China.
6. The Fourth School of Clinical Medicine, Nanjing Medical University, Nanjing, China.
7. Department of Radiotherapy and Oncology, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China.
8. Department of Vascular Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
9. North District, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Suzhou, China.
HBO1 (KAT7 or MYST2) is a histone acetyltransferase that acetylates H3 and H4 histones.
Methods: HBO1 expression was tested in human OS tissues and cells. Genetic strategies, including shRNA, CRISPR/Cas9 and overexpression constructs, were applied to exogenously alter HBO1 expression in OS cells. The HBO1 inhibitor WM-3835 was utilized to block HBO1 activation.
Results: HBO1 mRNA and protein expression is significantly elevated in OS tissues and cells. In established (MG63/U2OS lines) and primary human OS cells, shRNA-mediated HBO1 silencing and CRISPR/Cas9-induced HBO1 knockout were able to potently inhibit cell viability, growth, proliferation, as well as cell migration and invasion. Significant increase of apoptosis was detected in HBO1-silenced/knockout OS cells. Conversely, ectopic HBO1 overexpression promoted OS cell proliferation and migration. We identified ZNF384 (zinc finger protein 384) as a potential transcription factor of HBO1. Increased binding between ZNF384 and HBO1 promoter was detected in OS cell and tissues, whereas ZNF384 silencing via shRNA downregulated HBO1 and produced significant anti-OS cell activity. In vivo, intratumoral injection of HBO1 shRNA lentivirus silenced HBO1 and inhibited OS xenograft growth in mice. Furthermore, growth of HBO1-knockout OS xenografts was significantly slower than the control xenografts. WM-3835, a novel and high-specific small molecule HBO1 inhibitor, was able to potently suppressed OS cell proliferation and migration, and led to apoptosis activation. Furthermore, intraperitoneal injection of a single dose of WM-3835 potently inhibited OS xenograft growth in SCID mice.
Conclusion: HBO1 overexpression promotes OS cell growth in vitro and in vivo.
Keywords: osteosarcoma, HBO1, histone acetylation, WM-3835