Circ72688 Drives Breast Cancer Invasion and Metastasis via the miR-654-5p/ORAI2 Axis

Background: Circular RNAs (circRNAs) play a crucial role in the progression of malignant tumors such as breast cancer. Methods: A circRNA microarray was used to detect key circRNAs in breast cancer. Expression of Circ72688 was verified by quantitative reverse transcription PCR (qRT-PCR) and fluorescence in situ hybridization (FISH) assay. Transwell assay and in vivo assay were conducted to prove the function of Circ72688. Exploring the downstream mechanism, dual-luciferase reporter assay, western blotting, and tissue microarray were performed. Results: We sequenced and identified a circRNA, hsa-circ-0072688, also known as Circ72688. Our research found that Circ72688 enhanced tumor metastasis both in vivo and in vitro. Mechanistically, Circ72688 acted as a molecular sponge for hsa-miR-654-5p, thereby affecting the transcription of ORAI2. The expression levels of Circ72688 and ORAI2 were significantly higher in breast cancer tissues compared to adjacent normal tissues, and a notable positive correlation could be seen between them. Conclusions: In summary, our study demonstrated the critical role of Circ72688 in breast cancer invasion and metastasis, and how Circ72688 partially regulated ORAI2 through hsa-miR-654-5p. Targeting Circ72688 might be a potential therapeutic strategy for breast cancer.