Abstract
Background: Lung adenocarcinoma (LUAD) is a life-threatening disease worldwide with a high mortality rate. The early diagnosis of LUAD is crucial for improving subsequent treatment and prognosis. However, biomarkers for early detection remain a clinical challenge in LUAD. Here, we aimed to develop circular RNAs (circRNAs) in circulating plasma from LUAD patients as valuable diagnostic biomarkers in LUAD. Methods: CircRNA expression was determined by circRNA microarray in three pairs of LUAD tumour tissues and patient-matched normal lung tissues. Hsa_circ_101555 and hsa_circ_008068 were selected as potential biomarkers in LUAD tissues and plasma by RT-PCR, respectively. The diagnostic value was analysed by the area under the curve (AUC) and the receiver operating characteristic (ROC) test. Results: Our results showed that 6261 circRNAs were upregulated and 7238 circRNAs were downregulated in LUAD tumour tissues compared with patient-matched normal lung tissues. Hsa_circ_101555 and hsa_circ_008068 were filtered as biomarkers for early-stage LUAD. Q-PCR results showed that hsa_circ_101555 and hsa_circ_008068 were significantly upregulated in both LUAD cancer tissues and circulating plasma. Hsa_circ_101555 and hsa_circ_008068 were positively associated with tumour differentiation, tumour size and CEA (P<0.05). The ROC analysis showed that hsa_circ_101555 and hsa_circ_008068 had a better diagnostic potential compared to the traditional biomarkers (CEA, SCC, CYFRA21-1) in the detection of early-stage LUAD. Conclusion: The circular RNAs hsa_circ_101555 and hsa_circ_008068 could serve as novel diagnostic biomarkers for early-stage LUAD.