Increased expression of IGF II mRNA-binding protein 1 mRNA is associated with an advanced clinical stage and poor prognosis in patients with ovarian cancer

The purpose of this study was to examine the expression of IGF II mRNA-binding protein (IMP-1, -2, and -3) mRNA in epithelial ovarian tumors, and to identify the association of IMP-1, -2, and -3 expression levels with patient survival. IMP mRNA expression levels were examined by semi-quantitative PCR in 59 epithelial ovarian tumors (8 adenomas, 5 LMP tumors, and 46 adenocarcinomas) and in 7 normal ovaries. Results of semiquantitative PCR were correlated with clinicopathological variables and overall survival. Human normal and tumor tissue cDNAs were included in all of the analyses. The IMP family mRNA expression was detected in almost all cancer tissues examined, including breast, lung, colon, prostatic, and ovarian carcinoma with the exception of pancreatic carcinoma. The mean value of the relative IMP-1 mRNA expression ratio was significantly higher in both ovarian cancer and adenoma samples compared to normal ovarian samples (p<0.05). IMP-2 and IMP-3 expression levels were significantly higher in both ovarian cancer and ovarian LMP tumor samples compared to either ovarian adenomas or to normal ovary samples (p<0.05). A significantly higher IMP-1 mRNA expression level was observed in patients with an advanced clinical stage (p=0.015) and high histological grade (p=0.023). Log-rank testing showed that IMP-1 overexpression (p=0.0398) and an advanced clinical stage (p=0.0050) were significantly correlated with poor patient survival, whereas neither IMP-2 nor IMP-3 overexpression were associated with poor prognoses. In multivariate analysis, IMP-1 overexpression lost its significance, whereas the clinical stage (p=0.0432) remained significantly associated with overall survival. IMP mRNA expression levels might play an important role in ovarian cancer development and progression, and IMP-1 overexpression is a prognostic marker for patients with ovarian cancer.