环状RNA-ITGA1促进三阴性乳腺癌进展和转移

Objective: To investigate the mechanism of circRNA-integrin alpha 1 (circ-ITGA1) on the proliferation and metastasis of triple-negative breast cancer (TNBC) cell lines and its significance. Methods: RNA-seq was used to screen circRNAs which were differentially expressed in high-metastatic TNBC cell lines, and real-time fluorescent quantitative PCR was further used to detect the expression of circ-ITGA1 in breast cancer cell lines. The circular characteristics of circ-ITGA1 were verified. Then TNBC cells were transfected with siRNAs and overexpression vectors. MTT method, colony formation and EdU assay were used to detect the effect of circITGA1 on proliferation abilities of TNBC cells. Transwell chamber and scratch-healing assays were used to examine the roles of circ-ITGA1 in migration and invasion of TNBC cells. Finally, the related databases were used to predict potential targets and molecular mechanism. Results: Based on RNA-seq and real-time fluorescent quantitative PCR, the circ-ITGA1 was significantly up-regulated in TNBC cell lines and was positive correlated with malignancy of cells (P＜0.01). The specific junction sequence of circ-ITGA1 was found in TNBC cells and the circular RNA characters such as resistance to RNase R digestion, longer halftime and no poly (A) tail was verified (all P＜0.01). Knockdown of circ-ITGA1 inhibited the proliferation abilities of TNBC cells by MTT method (both P＜0.01), colony formation (both P＜0.01) and EdU assay (both P＜0.01). Moreover, knockdown of circ-ITGA1 could suppress the migration, invasion and wound healing abilities of the TNBC cells (all P ＜0.01). Further overexpression assay proved circ-ITGA1 could promote the proliferation and metastasis of TNBC cells. To explore the potential mechanism of circ-ITGA1, databases were used and miR-624-5p was predicted as the potential target miRNA of circ-ITGA1, which was correlated with better prognosis of TNBC patients (P＜0.05). Then mioncocirc and miRNet databases were used and found LMBR1L could be the target of both circ-ITGA1 and miR-624-5p, which was positively correlated with circ-ITGA1 (r＝0.319, P=0.016) and negatively correlated with miR-624-5p expression (r=－0.313, P＜0.01), and predicted poorer prognosis of TNBC patients (P＜0.05). It was suggested that circ-ITGA1 may perform function by influencing the miR-624-5p/LMBR1L signal axis. Conclusion: The results demonstrates that circ-ITGA1/miR-624-5p/LMBR1L axis could significantly promote the proliferation and metastatic abilities of TNBC cells, providing theoretical basis for further understanding of the molecular mechanism of progression and metastasis of TNBC.