Predictive value of lncRNA LOC100505851 in breast cancer in the neoadjuvant setting

Background: The expression and function of long noncoding RNA (lncRNA) LOC100505851 in breast cancer are still unknown. We aimed to examine the expression of lncRNA LOC100505851 in breast cancer and adjacent tissues and preliminarily explore its predictive value and function in breast cancer patients receiving neoadjuvant therapy (NAT). Methods: The expression of lncRNA LOC100505851 was tested by qRT-PCR. The correlation between LOC100505851 expression and clinicopathological factors as well as pathological complete response (pCR) was analyzed by chi-squared test and logistic regression, respectively. The online database Kaplan-Meier plotter (KM plotter) was used to compare relapse-free survival (RFS) and overall survival (OS) between groups with different LOC100505851 expression levels. Subcellular localization of LOC100505851 was determined by nuclear and cytoplasmic extraction. A bioinformatics tool was used to predict RNA-binding proteins (RBPs) and interaction among these proteins. Results: LncRNA LOC100505851 was significantly expressed at lower levels in cancer tissues than in adjacent tissues (P<0.001). Its expression was related to human epidermal growth factor receptor 2 (HER2) expression (P=0.003) and molecular subtype based on immunohistochemistry (P=0.001). Patients with high LOC100505851 expression were prone to pCR (OR =3.077, 95% CI: 1.042-9.086, P=0.042) and better RFS (HR =0.68, 95% CI: 0.59-0.79, P<0.001) and OS (HR =0.60, 95% CI: 0.43-0.84, P=0.0026) according to the online database KM plotter. The subcellular localization of LOC100505851 was in the nucleus, and its binding proteins were predicted by bioinformatics tools. Conclusions: LncRNA LOC100505851 was located mainly in the nucleus and was significantly downregulated in breast cancers. Its expression was related to a higher pCR rate and better RFS and OS, indicating its potential value as a novel predictive and prognostic biomarker in breast cancer.