Purpose: We analyzed the gene expression of the glycoprotein termed secreted protein, acidic and rich in cysteine (SPARC), also called osteonectin and BM40, in bladder cancer and its relationship with conventional clinical-histopathological manifestations, evaluated its prognostic value for patient outcome and determined the possible mechanism underlying the effect of SPARC on bladder cancer progression.
Materials and methods: Tissue samples from 63 patients with bladder cancer were used for analysis. Gene expression levels of SPARC and matrix metalloproteinase-2 were analyzed using reverse transcription-polymerase chain reaction. Correlations of the expression of SPARC with histopathological findings or patient outcome and with matrix metalloproteinase-2 were evaluated.
Results: Significantly higher expression of SPARC was observed in grades 3 and 2 than in grade 1 tumors (p <0.001 and <0.05, respectively). Stage T2 or greater invasive tumors expressed a significantly higher level of SPARC than stages T1 or less superficial tumors (p <0.0001). Patients in whom the lesions showed high SPARC expression had a significantly worse prognosis than those with low SPARC expression disease (p <0.0001). Even in those with invasive bladder cancer high SPARC expression was associated with significantly worse survival than low expression (p <0.01). Moreover, gene expression of SPARC significantly correlated with matrix metalloproteinase-2 gene expression (p <0.0001), implying that regulation of matrix metalloproteinase-2 expression may be a possible mechanism underlying the effect of SPARC on bladder cancer progression.
Conclusions: A significant correlation was detected of the gene expression level of SPARC with histological grade, pathological stage and bladder cancer prognosis. SPARC may have an important role in bladder cancer progression and provide some additional information in patients with bladder cancer.