Application of Circular RNA Circ_0071662 in the Diagnosis and Prognosis of Hepatocellular Carcinoma and Its Response to Radiotherapy.

Background: Although the involvement of circular RNA Circ_0071662 in bladder cancer and esophageal cancer has been reported, its role in hepatocellular carcinoma (HCC) is unclear. The presented research aimed to study its role in HCC.

Methods: This study enrolled 60 HCC patients (advanced stage), 60 hepatic angiomyolipoma patients, 60 liver abscess patients, 60 hypertrophic cardiomyopathy patients, 60 focal nodular hyperplasia patients, and 60 healthy controls (HCs). Plasma samples were obtained from all participants prior to treatment. HCC and paired nontumor samples were collected from HCC patients. HCC patients received radiotherapy and plasma samples were also collected after treatment. Gene expression was analyzed by RT-qPCR. The role of Circ_0071662 in the diagnosis of HCC was evaluated by ROC curve analysis.

Results: Compared to HCs, decreased plasma expression levels of Circ_0071662 were only observed in HCC patients, but not in other patient groups. HCC tissues also exhibited decreased expression levels of Circ_0071662 compared to that in nontumor samples. Decreased plasma expression levels of Circ_0071662 separated HCC patients from HCs and other patient groups. After radiotherapy, 28 patients developed radioresistance (RR) and the rest showed no RR. Decreased plasma expression levels of Circ_0071662 were closely associated with patients' poor survival. Compared to pretreatment level, decreased plasma expression levels of Circ_0071662 were only observed in RR group. The expression levels of Circ_0071662 in plasma and tissues were closely associated with patients' tumor metastasis and tumor size.

Conclusion: Circ_0071662 was downregulated in HCC and may serve as a potential biomarker to improve the diagnosis of HCC. Moreover, downregulation of Circ_0071662 is likely correlated to the development of radioresistance.