Identification of a ChrXq27.3 MicroRNA Cluster Associated with Early Relapse in Advanced Stage Ovarian Cancer Patients

A major challenge in advanced-stage epithelial ovarian cancer (EOC) is prediction of chemoresistant relapse. Our aim was to identify a microRNA (miRNA) signature associated with early relapse in advanced-stage EOC patients. miRNA expression was assessed by microarray profiling in training (n = 55) and test (n = 30) sets selected on the basis of time to relapse (TTR), followed by internal quantitative reverse transcriptase-PCR validation on a set of 45 consecutive cases unselected for clinical response and external in silico validation on publicly available datasets. Thirty-two differentially expressed miRNAs in early vs. late relapsing patients were identified in the training set. In the test set, 8 of these, belonging to a cluster located on chrXq27.3, were down-modulated in early relapsing patients. Hierarchical clustering of the internal validation set according to chrXq27.3 miRNA expression associated low miRNA expression with shorter TTR (log-rank P=0.00074, HR 2.44). The cluster was an independent prognostic factor in both internal and external validation sets. Forced expression of chrXq27.3-cluster selected miRNAs in human EOC cellular models was associated to reduction of cell proliferation and increased sensitivity to cisplatin. The role of down-modulation of the chrXq27.3 miRNA cluster in early relapse of advanced-stage EOC patients and its association to a reduced sensitivity to chemotherapeutic treatments warrant further investigation.