Received on December 10, 2007
Accepted on July 23, 2008

Cancer Diagnostics

Prognostic Value of Mature MicroRNA-21 and MicroRNA-205 Overexpression in Non–Small Cell Lung Cancer by Quantitative Real-Time RT-PCR

¹ Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Athens, Greece
² "Sotiria" General Hospital for Chest Diseases, Athens, Greece
³ Department of Pathology, Onassis Cardiac Surgery Center, Athens, Greece
⁴ Department of Medical Oncology and Laboratory of Tumor Cell Biology, University Hospital of Heraklion, School of Medicine, University of Crete, Greece

^* To whom correspondence should be addressed. E-mail: lianidou{at}chem.uoa.gr.

BACKGROUND: microRNA (miRNA) expression profiles are being intensively investigated for their involvement in carcinogenesis. We evaluated the prognostic value of mature microRNA-21 (miR-21) and mature microRNA-205 (miR-205) overexpression in non–small cell lung cancer (NSCLC).

PATIENTS AND METHODS: We studied 48 pairs of NSCLC fresh frozen tissue specimens collected at time of surgery and before chemotherapy. Highly specific amplification and quantification of mature miR-21 and mature miR-205 was achieved using looped real time RT-PCR.

RESULTS: miRNA expression, determined by real time RT-PCR, was defined by Ct measurements. We detected overexpression of mature miR-21 in 25 (52.0%) of the 48 NSCLC paired specimens and overexpression of miR-205 in 31 (64.6%). Overexpression was assessed after comparison of miRNA expression in NSCLC tissues and in their corresponding noncancerous tissues with respect to U6 expression. During the follow-up period, 29 of 48 (60.4%) patients relapsed, and 23 of 48 died (47.9%). Mature miR-21 was upregulated in 16 of 29 (55.2%) patients who relapsed and 15 of 23 (65.2%) patients who died. Mature miR-205 was overexpressed in 19 of 29 patients who relapsed (65.5%) and 15 of 23 patients who died (65.2%). Mature miR-21 overexpression correlated with overall survival (OS) of the patients (P = 0.027), whereas overexpression of mature miR-205 did not.

CONCLUSIONS: Our results suggest that overexpression of mature miR-21 is an independent negative prognostic factor for OS in NSCLC patients.