Circular RNA La‐related RNA‐binding protein 4 correlates with reduced tumor stage, as well as better prognosis, and promotes chemosensitivity to doxorubicin in breast cancer

OBJECTIVE: We aimed to evaluate the correlation of circular RNA La‐related RNA‐binding protein 4 (circ‐LARP4) with tumor characteristics and prognosis, and its effect on chemosensitivity in breast cancer. METHODS: Circ‐LARP4 from tumor and adjacent tissues of 283 female breast cancer patients underwent resection was detected by reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR). Tumor features, disease‐free survival (DFS), and overall survival (OS) were recorded. In vitro, circ‐LARP4 in human normal mammary epithelial cells (HMEC) and breast cancer cell lines was detected by RT‐qPCR. MCF‐7 and MDA‐MB‐231 cells were transfected with circ‐LARP4 overexpression plasmid (as OE‐Circ group) and control overexpression plasmid (as OE‐Control group). Relative cell viability under different concentrations of doxorubicin was measured. RESULTS: Circ‐LARP4 was decreased in tumor tissues than adjacent tissues (P < .001). Tumor circ‐LARP4 negatively correlated with tumor size (P = .001), T stage (P = .009), N stage (P = .006), and TNM stage (P < .001), whereas positively correlated with DFS (P = .004) and OS (P < .001). In vitro, circ‐LARP4 was decreased MCF‐7, BT474, MDA‐MB‐231, and MDA‐MB‐468 cell lines than HMEC (all P < .001). Relatively cell viability of MCF‐7 cells (at 20 nmol/L [P < .05], 40 nmol/L [P < .01], 80 nmol/L [P < .05] of doxorubicin) and MDA‐MB‐231 cells (at 120 nmol/L [P < .05], 240 nmol/L [P < .05] of doxorubicin) was decreased in OE‐Circ group than OE‐Control group. IC(50) value of doxorubicin was decreased in OE‐Circ group than OE‐Control group in MCF‐7 and MDA‐MB‐231 cell lines (both P < .01). CONCLUSION: Circ‐LARP4 was a potential prognostic biomarker, which might improve the management of breast cancer.