High expression of UBD correlates with epirubicin resistance and indicates poor prognosis in triple-negative breast cancer

BACKGROUND Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer that is prone to recurrence and metastasis with worse prognosis. Epirubicin-based chemotherapy is of great importance for patients with TNBC, but resistance to epirubicin severely limits the application of this drug and this has emerged as a major problem in the treatment of TNBC. The ubiquitin protein D (UBD) molecule has often been considered a tumor oncogene, and has been shown to promote the recurrence and metastasis of malignant tumor cells. Since the role of UBD in epirubicin resistance and its prognostic value in TNBC have not been reported, the study reported here was designed to identify the epirubicin-resistance molecule and clarify the related biomarker for TNBC prognosis. METHODS UBD plasmid was transfected into MDA-MB-231 cells, and the cells were exposed to epirubicin to observe the ability of UBD in epirubicin resistance. UBD expression was also detected in 78 breast cancer tissues by immunohistochemistry. Statistical methods were used to study the relationship between UBD expression and epirubicin resistance in TNBC treatment. Kaplan-Meier survival analysis was used to determine the correlation between UBD expression and TNBC patients' prognostic parameters. RESULTS UBD expression was found increased in breast cancer tissues. Forced UBD expression was found to have a relationship with TNBC epirubicin resistance in vitro. High expression of UBD was found in TNBC, compared with in non-TNBC, and this played a positive role in epirubicin resistance and indicated the poor prognosis of TNBC treatment. CONCLUSION UBD may play an important role in epirubicin resistance in TNBC. UBD has the potential to be a novel biomarker in TNBC chemoresistance and may be a promising therapeutic target for TNBC patients.