The role of circCNIH4 in the adipocyte's effects on metastasis of breast cancer cells.

Abstract

e13086 Background: Obesity is associated with the risk of breast cancer(BCa) incidence and development. However, biological changes in obesity BCa individuals are still uncertain. Nowadays, circCNIH4, one of novel non-coding RNAs, was found to be a non-invasive biomarker in cancers. Methods: We verified the cancer-promoting role of obesity in BCa patients by comparing BMI indexes of 33 BCa and 44 benign tumor patients. Then we cocultured viscera adipose cells(HPA-v) and BCa cells(MCF-7/H and MDA-MB-231/H) to confirm the function of adipocytes on metastasis of BCa cells through wound healing, transwell assays. In vivo experiments were also performed. We analyzed the expression level of circCNIH4 in MCF-7/H, MDA-MB-231/H and different subtypes of BCa cells by quantitative polymerase chain reaction. Simultaneously, we identified inhibited effects of circCNIH4 on metastasis of BCa cells by wound healing, transwell assays and verified the location of circCNIH4 by FISH. Luciferase Assay was used to detect harbored miRNA. Rescue experiments were then applied. Results: We found the BMI of BCa patients(24.37±2.51) was much higher than benign patients(22.97±2.91). Metastasis of BCa cells were obviously promoted after in vitro and in vivo experiments. Then we found the expression of circCNIH4 in MCF-7/H and MDA-MB-231/H were down-regulated 0.71 and 0.52 than that in MCF-7 and MDA-MB-231. Also, circCNIH4 was positively correlated with less aggressive types of BCa cells. Overexpression of circCNIH4 in MDA-MB-231 could suppress cell invasion and migration, while silencing of it in MCF-7 promoted cell invasion and migration. The FISH assay demonstrated that circCNIH4 mainly located in the cytoplasm and might function as a “sponge” for miRNA. MiR-135b functioned as a tumor promoter gene from data of 93 BCa patients (HR = 2.27; 1.01 − 5.12), and it could be captured by circCNIH4 via luciferase and rescued assays. Conclusions: In this study, we revealed that BMI or viscera adipocytes could deteriorate prognosis of BCa and circCNIH4 could be a novel biomarker for non-invasive BCa. In details, circCNIH4 mainly suppressed the adipocyte's pro-metastasis effects on BCa by capturing miR-135b.