A pilot study on the expression of microRNAs resident on chromosome 21 in laser microdissected FFPE prostate...

The tremendous research effort of the last decades added a new, epigenetic layer of complexity to the already complex image of prostate cancer pathogenesis. Here we use quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the expression of the microRNAs resident on chromosome 21 (miR-ch21) in laser capture microdissected (LCM) tissues from formalin-fixed paraffin-embedded (FFPE) archived, prostate adenocarcinoma samples. We show a strong, specific down-regulation of miR-ch21 in tumoral epithelia and stromae as compared to normal counterparts, results at odd with the current paradigm on the involvement of these microRNAs in prostate oncogenesis. By comparing this result with the expression of two well-known pluripotency associated microRNA, hsa-miR-372 and miR-373, we suggest that miR-ch21 down-regulation might be the result of specific silencing of miR genes mapped to chromosome 21. Further studies, of larger sample size are needed to confirm our preliminary data.