However, it is now appreciated that they play a significant function in gene regulation at the post-transcriptional level. This group has previously reported that mi339 expression is downregulated in CaP cell lines generated from metastases in animal models as compared to maternal cell lines PC3 and DU145. This report sought to validate these findings in lymph node metastasis of CaP patients using real time PCR. To do this, miRNA was isolated from cell lines PC3, PC3-N, PC3-125L, DU145 and DU145-MN1 as well as from paraffin-embedded tissue sections of normal prostate, primary tumor and lymph node metastases from the same patient (8 patients in total). miRNA339 expression was determined by real time PCR using commercially available primer sets and normalized to expression of snRNA RNU6B. Differential expression was calculated by relative quantification.
Real time PCR results confirmed their previous microarray findings; a 4-fold downregulation of miRNA339 in metastatic sublines (PC3-N, PC3-125L and DU145-MN1) compared to CaP cell lines PC3 and DU145. In patient lymph nodes with CaP, miR339 was at least two-fold lower in 7 of 8 cases compared to corresponding normal tissue from the same patient. Moreover, all lymph node metastases had at least a 4-fold decrease of miR339 in relation to expression in normal tissue. Comparing miR339 expression in the primary tumor and lymph node metastasis from the same patient, they found a decrease in 6 sample sets and in the remaining 2 cases miR339 was already at very low levels in the primary tumor tissue. This may suggest that miR339 has functional importance in processes suppressing tumor cell invasion, migration and metastasis.
Presented by J. Kamradt, et al. at the 26th Annual European Association of Urology (EAU) Congress - March 18 - 21, 2011 - Austria Centre Vienna, Vienna, Austria