Background: The metastasis gene osteopontin (OPN) is subject to alternative splicing, which yields threemessages, osteopontin-a, osteopontin-b and osteopontin-c. Osteopontin-c is selectively expressed in invasive, butnot in noninvasive tumors. In the present study, we examined the expression of OPN-c in esophageal squamouscell carcinomas (ESCCs) and assessed its value as a diagnostic biomarker.
Methods: OPN-c expression wasassessed by immunohistochemistry in 63 ESCC samples and correlated with clinicopathologic factors. Expressionwas also examined in peripheral blood mononuclear cells (PBMCs) from 120 ESCC patients and 30 healthysubjects. The role of OPN-c mRNA as a tumor marker was investigated by receiver operating characteristiccurve (ROC) analysis.
Results: Immunohistochemistry showed that OPN-c was expressed in 30 of 63 cancerlesions (48%)and significantly associated with pathological T stage (P=0.038) and overall stage (P=0.023). Realtime PCR showed that OPN-c mRNA was expressed at higher levels in the PBMCs of ESCC patients than inthose of healthy subjects (P<0.0001) with a sensitivity as an ESCC biomarker of 86.7%.
Conclusion: Our findingssuggest that expression of OPN-c is significantly elevated in ESCCs and this upregulation could be a potentialdiagnostic marker.