Exosomal LncRNA RP5-977B1 as a novel minimally invasive biomarker for diagnosis and prognosis in non-small cell lung cancer.

Background: Lung cancer is the leading cause of cancer-related deaths in the world. Non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer cases. For lack of conveniently sensitive and specific biomarkers, the majority of patients are in the late stage at initial diagnosis. Long non-coding RNAs (LncRNAs), a novel type of non-coding RNA, have recently been recognized as critical factors in tumor initiation and progression, but the role of exosomal LncRNAs has not been thoroughly excavated in NSCLC yet.

Methods: We isolated exosomes from the serum of patients with NSCLC and healthy controls. Exosome RNA deep sequencing was subsequently performed to detect differentially expressed exosomal LncRNAs. qRT-PCR assay was then utilized to validate dysregulated LncRNAs in both testing and multicentric validation cohort. Receiver operating characteristic (ROC) curve was used to detect the diagnostic capability of exosomal biomarkers. Furthermore, Kaplan-Meier analysis was applied to evaluate the prognostic values of these molecules.

Results: On the basis of analysis, we found that novel exosomal LncRNA RP5-977B1 exhibited higher levels in NSCLC than that in the healthy controls. The area under the curve (AUC) value of exosomal RP5-977B1 was 0.8899 and superior to conventional biomarkers CEA and CYFRA21-1 both in testing and multicentric validation cohort. Interestingly, the diagnostic capability of exosomal RP5-977B1 was also validated in early-stage patients with NSCLC. Furthermore, high expression of exosomal RP5-977B1was closely related with worse prognosis in NSCLC (P = 0.036).

Conclusions: Our results suggested that exosomal RP5-977B1 might serve as a novel "liquid biopsy" diagnostic and prognostic biomarker to monitor NSCLC and improve possible therapy.