Osteopontin Expression in Squamous Cell Cancer of the Esophagus

BACKGROUND: The purpose of this study was to better understand the role of osteopontin (OPN) in esophageal squamous cell carcinoma (ESCC) by comparing the OPN mRNA level in ESCC tumor tissue and matched normal tissue and by determining the prognostic significance of the gene expression. METHODS: Initially, by an oligo-nucleotide microarray hybridization technique, OPN expressions were found to consistently elevate at least twofold in three ESCC tissues compared with their adjacent normal ones. Subsequently, the expression of OPN mRNA was detected by real-time QRT-PCR among the 58 fresh surgical ESCC specimens. The clinical information was obtained by chart review. RESULTS: OPN mRNA expression was detectable in 58 of 58 (100%) tumor specimens and 57 of 58 (98.3%) nonmalignant esophageal specimens. OPN expression was higher in tumor tissue than in the matched normal tissue in 54 of 58 (93.1%) individual cases. The overall median mRNA expression level of OPN was approximately 8.8-fold higher in tumor tissues (4.1; range: 0.02-247) compared with matched normal esophageal tissues (0.5; range, 0.0-21.4; p < 0.001). Overexpression of OPN mRNA was significantly associated with clinical stage (p = 0.01). The more severe the clinical stage (from I-II, III, to IV) was the higher frequency of overexpression of OPN mRNA. No significant associations were found between overexpression of OPN mRNA and the patients' survival (p = 0.27). DISCUSSION: Our findings suggest OPN is associated with esophageal tumorigenesis and progression, but not patients' survival.