Prostate cancer induces C/EBPβ expression in surrounding epithelial cells which relates to tumor aggressiveness and patient outcome.

BackgroundImplantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating adaptations in the tumor-bearing organ. Similar changes are seen in prostate cancer patients and they are related to outcome. One gene previously found to be upregulated in the non-malignant part of tumor-bearing prostate lobe in rats was the transcription factor CCAAT/enhancer-binding protein- (C/EBP). MethodsTo explore this further, we examined C/EBP expression by quantitative RT-PCR, immunohistochemistry, and Western blot in normal rat prostate tissue surrounding slow-growing non-metastatic Dunning G, rapidly growing poorly metastatic (AT-1), and rapidly growing highly metastatic (MatLyLu) rat prostate tumors?and also by immunohistochemistry in a tissue microarray (TMA) from prostate cancer patients managed by watchful waiting. ResultsIn rats, C/EBP mRNA expression was upregulated in the surrounding tumor-bearing prostate lobe. In tumors and in the surrounding non-malignant prostate tissue, C/EBP was detected by immunohistochemistry in some epithelial cells and in infiltrating macrophages. The magnitude of glandular epithelial C/EBP expression in the tumor-bearing prostates was associated with tumor size, distance to the tumor, and metastatic capacity. In prostate cancer patients, high expression of C/EBP in glandular epithelial cells in the surrounding tumor-bearing tissue was associated with accumulation of M1 macrophages (iNOS+) and favorable outcome. High expression of C/EBP in tumor epithelial cells was associated with high Gleason score, high tumor cell proliferation, metastases, and poor outcome. ConclusionsThis study suggest that the expression of C/EBP-beta, a transcription factor mediating multiple biological effects, is differentially expressed both in the benign parts of the tumor-bearing prostate and in prostate tumors, and that alterations in this may be related to patient outcome.