Evaluation of microRNA Markers To Predict Outcome in Low Stage Lung Cancer
EJ Duncavage, B Goodgame, R Govindin, JD Pfeifer. Washington University, Saint Louis, MO
Background: Low stage (I and II) non-small cell lung cancer (LS-NSCLC) currently presents a major treatment dilemma. While the overall 5 year survival rate is around 70%, approximately half of all patients who undergo initial surgical resection will die from their disease. However, as prognostic markers for LS-NSCLC are lacking, many patients receive unnecessary chemotherapy with its side effects. By measuring miRNA expression, which can control hundreds of downstream targets, we aim to discover its relationship to patient outcome.
Design: We selected a set of 5 miRNAs and one control miRNA from previous studies that linked outcome or invasiveness to expression in carcinomas of the lung and other organ systems. Of the 5 experimental miRNAs, increased expression of 3 (hsa-miR-155, hsa-mir-210, and hsa-miR-21) has been associated with a poor outcome/invasiveness. In contrast, decreased expression of 2 selected miRNAs (hsa-let-7a and hsa-mir-221) has been associated with invasiveness. Using a set 44 patients with surgically resected T1 or T2 LS-NSCLC and an average follow-up of 7 years, we measured expression of the selected miRNAs by Real Time RT-PCR. Briefly, comparable areas of viable cellular tumor were punched from paraffin blocks. RNA extracted and quantitated. Approximately 1-10ng of RNA from each sample was reverse transcribed using primers specific to each miRNA. The resulting cDNA was then assayed by Real Time PCR on an ABI 7500 using TaqMan FAM labeled primers. Expression was normalized to rnu-6B.
Results: Triplicate data on a subset of patients was averaged and correlated with outcome using Pearson correlation coefficients. One miRNA, hsa-miR-210, showed a direct relationship with recurrence that approached significance (p=0.056), consistent with previous reports. Expression of hsa-miR-21 showed significant correlation with levels of hsa-miR-155 (p=0.030) and hsa-miR-210 (p=0.0018).
Conclusions: As the role of the more than 800 human miRNAs becomes better understood, it is clear that they play an important part in carcinogenesis. We have shown that increased expression of one miRNA, hsa-miR-210, is correlated with recurrence in LS-NSCLC as it is in carcinomas of other organs. In addition the 3 miRNAs associated with recurrence are correlated with one another. We aim to uncover further relationships as we add additional patients to the study.
Tuesday, March 10, 2009 1:00 PM
Poster Session IV # 223, Tuesday Afternoon