Osteopontin expression is an independent factor for poor survival in oral squamous cell carcinoma: a computer-assisted analysis on TMA sections.

ABSTRACT

INTRODUCTION: Osteopontin (OPN) is non-collagenous extracellular matrix protein involved in various physiological and pathological events, including tumor progression. The aim of this study was to analyze the expression of OPN in normal oral mucosa and oral squamous cell carcinoma (OSCC) and to assess its prognostic significance. METHODS: The expression of OPN was immunohistochemicaly analyzed in 86 OSCC and compared with clinicopathological variable such as tumor size, nodal stage, WHO clinical stage, Ki-67 proliferation index, and patients' outcome. OPN mRNA was analyzed using quantitative real-time PCR and compared with protein OPN expression and clinical outcome in 18 OSCC samples. RESULTS: The expression of OPN protein was found in OSCC tumor cells (t-OPN) and various stromal cells (s-OPN). High level of t-OPN expression was associated with higher nodal stage (P = 0.045), higher WHO clinical stage (P = 0.033), and poor clinical outcome (P = 0.022). In multivariate analysis, t-OPN emerged as an adverse independent factor for survival (P = 0.049). Although correlated with t-OPN (P = 0.005), s-OPN was not significantly associated with clinical parameters, including patients' outcome. Also, there was no association between OPN and clinical parameters at the mRNA level. CONCLUSION: OPN is upregulated in tumor and stromal OSCC cells. Tumor cell-derived OPN is involved in tumor progression and can independently predict the clinical outcome. Stromal-derived OPN probably has a different function compared with OPN secreted from tumor cells.