MicroRNA profiling and prediction of recurrence/relapse-free survival in stage I lung cancer

Abstract

About 30% stage I non-small cell lung cancer (NSCLC) patients undergoing resection will recur. Robust prognostic markers are required to better manage therapy options. MicroRNAs (miRNAs) are a class of small non-coding RNAs of 19-25 nt and play important roles in gene regulation in human cancers. The purpose of this study is to identify miRNA expression profiles that would better predict prognosis of stage I NSCLC. MiRNAs extracted from 527 stage I NSCLC patients were profiled on the human miRNA expression profiling v2 panel (Illumina). The expression profiles were analyzed for their association with cancer subtypes, lung cancer brain metastasis and recurrence/relapse free survival (RFS). MiRNA expression patterns between lung adenocarcinoma and squamous cell carcinoma differed significantly with 171 miRNAs, including Let-7 family members and miR-205. Ten miRNAs associated with brain metastasis were identified including miR-145*, which inhibit cell invasion and metastasis. Two miRNA signatures that are highly predictive of RFS were identified. The first contained 34 miRNAs derived from 357 stage I NSCLC patients independent of cancer subtype, whereas the second containing 27 miRNAs was adenocarcinoma specific. Both signatures were validated using formalin-fixed paraffin embedded and/or fresh frozen tissues in independent data set with 170 stage I patients. Our findings have important prognostic or therapeutic implications for the management of stage I lung cancer patients. The identified miRNAs hold great potential as targets for histology-specific treatment or prevention and treatment of recurrent disease.

Fig. 1.

Kaplan–Meier survival curves of RFS for stage I NSCLC. (A) All NSCLC patients; (B) ADC patients; (C) SCC patients. The P-values were calculated by log-rank test.

Fig. 2.

Survival analyses of stage I NSCLC. (A–C) Kaplan–Meier survival curves of RFS using miRNA signatures: (A) signature from all stage I NSCLC patients (Signature I); (B) signature from stage I ADC patients (Signature II); (C) signature from stage I SCC patients (Signature III). (D–F) AUC for estimating 5 years RFS using survival models based on stage information or miRNA expression data respectively: (D) comparison of staging method with risk scores estimated by Signature I in all stage I NSCLC patients; (E) comparison of staging method with risk scores estimated by Signature II in stage I ADC patients; (F) comparison of staging method with risk scores estimated by Signature III in stage I SCC patients. FP, false positive; TP, true positive.

Fig. 3.

Validation of the two signatures in an independent testing set from Mayo Clinic. (A), (B) and (C) are validation of the 34-miRNA signature (Signature I) in 170 stage I patients. (D), (E) and (F) are validation of the 27-miRNA ADC-specific signature (Signature II) in 110 stage I ADC patients. A and D are Kaplan–Meier analyses of RFS using staging method. B and E are Kaplan–Meier analyses of RFS using risk scores estimated by miRNA signature. C and F are ROC analyses for estimating 5 years RFS based on stage information or miRNA signature.