Abstract
BACKGROUND: PIWI proteins belong to the Argonaute family. The human PIWI subfamily genes encode four PIWI (also known as PIWI-like) proteins: PIWIL1, PIWIL2, PIWIL3, and PIWIL4. The dysregulated expression of PIWI proteins appears to be associated with tumorigenesis. OBJECTIVE: To explore the expression of PIWI proteins in primary and metastatic tumors from patients with stage III epithelial ovarian cancer (EOC), evaluate the diagnostic value of PIWI in various tissues, and analyze the characteristics of each PIWI protein associated with metastasis. METHODS: A total of 20 patients with stage III EOC were retrieved for the present study. Various tissues from the primary tumor, adjacent normal tissue, peritoneal metastasis, and lymph node with or without metastasis were examined. PIWI proteins were detected by immunohistochemistry using tissue microarray and analyzed. RESULTS: PIWIL1, PIWIL2, PlWlL3, and PIWIL4 were expressed in EOC. By comparison with the adjacent normal tissues, the expression of four PIWI proteins was significantly enhanced in the primary tumor and metastatic tissues (P< 0.01). CONCLUSION: PIWI proteins are upregulated in EOC and associated with metastasis. These proteins may be useful as diagnostic biomarkers for EOC. The function of PIWI proteins in EOC with tumor metastasis will need to be further explored.