Research ArticlesExpression of Cyclooxygenase-2 in Osteosarcoma of BoneMasi, Laura MD*; Recenti, Raffaella BSc*; Silvestri, Sandra MD*; Pinzani, Pamela BSc†; Pepi, Monica‡; Paglierani, Milena BSc‡; Brandi, Maria Luisa MD*; Franchi, Alessandro MD‡ Author Information Departments of *Internal Medicine †Clinical Physiopathology ‡Human Pathology and Oncology, University of Florence, Florence, Italy Supported by grants from M.I.U.R. (60% and 40%) and from the National Health System Projects (to Maria Luisa Brandi). Reprints: Alessandro Franchi, MD, Department of Human Pathology and Oncology, Viale Morgagni 85, 50134 Firenze, Italy (e-mail: [email protected]). Received for publication December 20, 2003; accepted April 6, 2005 Applied Immunohistochemistry & Molecular Morphology: March 2007 - Volume 15 - Issue 1 - p 70-76 doi: 10.1097/01.pai.0000213131.63417.fa Buy Metrics Abstract Several studies indicate that cyclooxygenase-2 (COX-2) is overexpressed in human malignancies, where it produces high levels of prostaglandins and contributes to tumor growth. In this study we have analyzed the expression of COX-2 in a series of 48 skeletal osteosarcomas of different subtypes by immunohistochemistry. In addition, we examined the effects of the specific COX-2 inhibitor Celecoxib on the growth of the human osteosarcoma cell line SaOS-2. Immunoreactivity for COX-2 was observed in 39 out of 48 tumors (81.2%), 30 (76.9%) of which showed a moderate or diffuse immunostaining. Considering the group of 42 primary osteosarcomas, COX-2 immunoreactivity was significantly higher in high grade osteosarcomas, where moderate or diffuse expression was detected in 23 out of 32 cases (71.8%), than in low grade osteosarcomas, where moderate or diffuse expression was detected in 2 out of 10 cases (20%) (P=0.008, Fisher exact test). In addition, low COX-2 expression was always associated with a good response to chemotherapy (5 out of 5 cases), whereas moderate or diffuse COX-2 expression was associated with a good response in 11 out of 20 cases (55%) (P=0.12, Fisher exact test). In SaOS-2 osteosarcoma cells, which express COX-2, treatment with Celecoxib determined inhibition of cell proliferation and induction of apoptosis. These results indicate that COX-2 is expressed at high levels in high grade osteosarcomas and support the use of COX-2 inhibitors to improve both the tumor response to chemotherapy and the outcome of osteosarcoma patients. © 2007 Lippincott Williams & Wilkins, Inc.