The underlying mechanisms of
ovarian cancer (OvCa) dissemination are still poorly understood, and novel molecular markers for this
cancer type are urgently needed. In search of adhesion molecules with prognostic relevance in OvCa, we compared
tumors with good outcome (alive > 3 years) and those with poor outcome (dead < 2 years) within data from The
Cancer Genome Atlas (TCGA). The
carcinoembryonic antigen-related cell adhesion molecule 1 (
CEACAM1) turned out as the only gene with differential expression in these groups. In order to further investigation on its role in OvCa, we analyzed
CEACAM1 mRNA levels extracted from TCGA microarray data (n = 517) as well as
CEACAM1 protein expression by Western blot analysis in a cohort of 242
tumor samples. Further,
CEACAM1 localization in tumour tissue was evaluated by immunohistochemistry and
CEACAM1 splice variants by RT-PCR in representative tumours. In Kaplan-Meier analysis, high
CEACAM1 mRNA levels significantly correlated with longer survival (p = 0.008). By Western blot analysis in the second cohort, similar associations of high
CEACAM1 protein levels with longer recurrence-free survival (RFS, p = 0.035) and overall survival (OAS, p = 0.004) were observed. In multivariate Cox regression analysis including clinical prognostic parameters,
CEACAM1 mRNA or
protein expression turned out as independent prognostic markers. Stratified survival analysis showed that high
CEACAM1 protein expression was prognostic in node-negative
tumors (p = 0.045 and p = 0.0002 for DFS and OAS) but lost prognostic significance in node-positive
carcinomas. Similarly, high
CEACAM1 mRNA expression did not show prognostic relevance in
tumors with lymphatic invasion (L1) but was associated with longer survival in cases without lymphovascular involvement. Further analysis showed a predominance of 4S and 4L
isoforms and mostly membraneous
CEACAM1 localization in ovarian tumours. Our results suggest that
CEACAM1 might be an independent favorable prognostic marker in OvCa, especially in the subgroup of patients with solely intraperitoneal
metastasis.