Hsa_circ_0029693 (circ-LATS2) promotes cell proliferation and regulates WNT5A via miR-4686 in breast cancer cells.

Abstract Background: Breast cancer (BC) is the most malignant form of tumor in women, which threatens females’ health. Circular RNAs (circRNAs), a class of non-coding RNAs, can act as a disease biomarker and endogenous “sponge” molecules for microRNAs (miRNAs). circRNAs may also influence the expression of their parent gene. LATS2 is a vital suppressor gene in Hippo pathway, which is a signaling cascade composed of a group of conserved kinases. The Hippo pathway plays an important role in almost all cancer types. Methods: Colony formation assays, MTT assays, wound healing assays, xenografts mice experiment, qRT-PCR, western blot assays, immunohistochemical staining assays, dual-luciferase reporter assays and Fluorescence in situ hybridization. Student’s t-test was used to analyse the results.Results: We discovered that circular RNA hsa_circ_0029693 (circ-LATS2), an exonic circRNA, are highly expressed in breast cancer cells. Furthermore, in BC patients’ samples, higher expression of circ-LATS2 was significantly related to higher percentage of Ki-67 expression; however the expression of circ-LATS2 was higher in HER2 negative BC patients compared to HER2 positive ones. We investigated the potential function and mechanism of circ-LATS2 action in BC. The results suggested that circ-LATS2 promoted cell proliferation, growth and migration. Through western blot and immunohistochemical staining assays, we found that circ-LATS2 could influence LATS2 expression. We also discovered that there was an inverse expression relationship between miR-4686 and circ-LATS2, suggesting that circ-LATS2 might act as an endogenous “sponge” for miR-4686. Using dual-luciferase reporter assays, we confirmed that circ-LATS2 can bind miR-4686. Increased miR-4686 expression caused a reduction in the protein levels of WNT5A, which is a putative target of miR-4686. We confirm this using dual-luciferase reporter assays that revealed that miR-4686 targets WNT5A by binding its 3’-untranslated region (3’UTR). Conclusions: Our results showed that circ-LATS2 expression in BC patients’ samples were significantly related to Ki-67 expression. In addition, circ-LATS2 acted as a promoter of proliferation and growth of breast cancer cells. These indicated that circ-LATS2 is a proliferative factor, similar to Ki-67; it also acts as a co-biomarker with Ki-67 in clinical treatment.