Analisi del pattern di epressione dei miRNA intracellulari ed extracellulari in linee tumorali di prostata esposte a farmaci citotossici

Recently it was discovered that miRNA are stably expressed in dierent body uids (circulating miRNAs) of many animals and may represent an useful di- agnostic and/or predictive tool of diseases. Circulating miRNA have been found stably expressed also in culture medium of tumor cells. We want- ed to determine whether i) prostate metastatic tumor cell lines PC-3 and DU-145 release the same miRNAs found in the plasma/serum of prostate cancer patients; ii) the intracellular expression levels of miRNAs in uence the extracellular ones; iii) the expression pattern of intracellular and ex- tracellular miRNAs is perturbed by chemotherapeutics. We chose a group of miRNA constituted by PCS-miRNAs (Prostate Cancer Secretory miR- NAs) that were overrepresented in the plasma of prostate cancer patients and by NS-miRNAs (Non Secretory miRNAs) that shared a Tumor Sup- pressor function in dierent tumor types. The data obtained showed that PCS-miRNAs but not NS-miRNAs were released by tumor cell lines into the culture medium and that the extracellular and intracellular expression pro- le of miRNAs are positively correlated. To verify whether miRNA release is an inducible mechanism we treated PC-3 and DU-145 cell to proliferation inhibiting concentrations of two dierent chemotherapeutic drugs: a prostate cancer specic drug (Taxotere) and an aspecic drug (Fludarabine). We then evaluated miRNAs expression levels and found that taxotere induced an increase while udarabine induces a variable modulation in the extracellular miRNAs expression levels. To explain these opposite eects we analyzed dif- ferent cellular end-points and found that both chemotherapeutics induce a persistent inhibition of proliferation and cell-cycle but only taxotere induces cell death. As a consequence i) a general increase in extracellular miRNA levels is representative of cell death, thus it may indicate the cytotoxic eca- cy of a treatment; ii) the quantication of miRNA release or retention may be an useful tool to discover possible networks of genetic expression activated by proliferation blockade and to investigate their relevance for cell survival and communication.