Expression and clinical relevance of SPOPL in medulloblastoma

Medulloblastoma (MB) is a type of malignant brain tumor in children. Although knowledge of MB is increasing and the survival rate of patients with MB has improved in previous years, the long-term treatment-associated complications remain unfavorable. Early diagnosis and treatment is critical for patients with MB, but effective molecular markers for MB remain elusive. The Speckle-type POZ protein (SPOP) is a member of the MATH-BTB protein family and is a type of joint molecule for Cullin-3. SPOP inhibits tumor growth. However, the SPOP-like (SPOPL) gene, which is a SPOP paralog gene and shares an overall 85% sequence identity with SPOP, has not been explored in cancer studies at present. The results of the present study demonstrate that the SPOPL expression is decreased in MB cells and tissues compared with normal cells and tissues at the protein and mRNA levels. Immunohistochemical analysis revealed decreased expression of SPOPL in 42/56 (75%) paraffin-embedded archival MB biopsies, and SPOPL expression may be associated with the MB differentiation level (P=0.011). Patients with increased SPOPL expression exhibit improved survival rates compared with those with decreased SPOPL expression, and the SPOPL gene may be a potentially valuable molecular marker of MB.