title: MicroRNA microarray identifies Let-7i as a novel biomarker and therapeutic target in human epithelial ovarian cancer.
abstract: MicroRNAs (miRNA) are approximately 22-nucleotide noncoding RNAs that negatively regulate protein-coding gene expression in a sequence-specific manner via translational inhibition or mRNA degradation. Our recent studies showed that miRNAs exhibit genomic alterations at a high frequency and their expression is remarkably deregulated in ovarian cancer, strongly suggesting that miRNAs are involved in the initiation and progression of this disease. In the present study, we performed miRNA microarray to identify the miRNAs associated with chemotherapy response in ovarian cancer and found that let-7i expression was significantly reduced in chemotherapy-resistant patients (n = 69, P = 0.003). This result was further validated by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.015). Both loss-of-function (by synthetic let-7i inhibitor) and gain-of-function (by retroviral overexpression of let-7i) studies showed that reduced let-7i expression significantly increased the resistance of ovarian and breast cancer cells to the chemotherapy drug, cis-platinum. Finally, using miRNA microarray, we found that decreased let-7i expression was significantly associated with the shorter progression-free survival of patients with late-stage ovarian cancer (n = 72, P = 0.042). This finding was further validated in the same sample set by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.001) and in an independent sample set by in situ hybridization (n = 53, P = 0.049). Taken together, our results strongly suggest that let-7i might be used as a therapeutic target to modulate platinum-based chemotherapy and as a biomarker to predict chemotherapy response and survival in patients with ovarian cancer.
authors.affiliation: Center for Research on Early Detection and Cure of Ovarian Cancer, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Nuo
authors.initials: N
authors.lastname: Yang
authors.forename: Sippy
authors.initials: S
authors.lastname: Kaur
authors.forename: Stefano
authors.initials: S
authors.lastname: Volinia
authors.forename: Joel
authors.initials: J
authors.lastname: Greshock
authors.forename: Heini
authors.initials: H
authors.lastname: Lassus
authors.forename: Kosei
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Shun
authors.initials: S
authors.lastname: Liang
authors.forename: Arto
authors.initials: A
authors.lastname: Leminen
authors.forename: Shan
authors.initials: S
authors.lastname: Deng
authors.forename: Lori
authors.initials: L
authors.lastname: Smith
authors.forename: Cameron N
authors.initials: CN
authors.lastname: Johnstone
authors.forename: Xian-Ming
authors.initials: XM
authors.lastname: Chen
authors.forename: Chang-Gong
authors.initials: CG
authors.lastname: Liu
authors.forename: Qihong
authors.initials: Q
authors.lastname: Huang
authors.forename: Dionyssios
authors.initials: D
authors.lastname: Katsaros
authors.forename: George Adrian
authors.initials: GA
authors.lastname: Calin
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Weber
authors.forename: Ralf
authors.initials: R
authors.lastname: Bützow
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Croce
authors.forename: George
authors.initials: G
authors.lastname: Coukos
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics*; D002945:Cisplatin / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D005260:Female; D018628:Gene Dosage; D006801:Humans; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D035683:MicroRNAs; D012333:RNA, Messenger; C487931:mirnlet7 microRNA, human; D002945:Cisplatin