NPRL2 is an independent prognostic factor of osteosarcoma

NPRL2 is a tumor suppressor gene whose inactivation contributes to tumor development. However, NPRL2 expression in osteosarcoma remains unclear. This study aimed to assess NPRL2 expression in osteosarcoma and analyze its potential as a prognostic factor. NPRL2 expression in 48 cases of osteosarcoma and 40 cases of osteochondroma tumors was examined by immunohistochemistry. NPRL2 expression in 20 osteosarcoma and 20 osteochondroma specimens were detected by Real-time PCR and Western blot analysis. We found that 18 cases (37.5%) of osteosarcoma and 27 cases (67.5%) of osteochondroma showed positive NPRL2 expression. Real-Time PCR and Western blot analysis showed that NRPL2 expression was lower in osteosarcoma than in osteochondroma (p< 0.05). The positive rate of NPRL2 expression was 71.4% (10/14), 25% (4/16) and 16.7% (3/18) in stage I, II and III of osteosarcoma, respectively. The positive rate of NPRL2 was 19% (4/21) and 48.1% (13/27) for low grade and high grade of osteosarcoma, respectively, with significant difference (p< 0.05). Cox multivariate analysis showed that the value of NPRL2 for predicting the overall survival of osteosarcoma patients. Despite the small size of the samples, our results suggest that NPRL2 expression is negatively related with the survival of osteosarcoma patients, indicating its value as a prognosis factor of osteosarcoma.