Identification of expression of CCND1-related lncRNAs in breast cancer

Cyclin D1 has been shown to participate in the pathogenesis of breast cancer. This cell cycle-related protein has direct or indirect interactions with long non-coding RNAs (lncRNAs). In the present two-step study, we first identified CCND1-related lncRNAs through an in silico approach. Then, we measured expression of CCND1 mRNA and five lncRNAs in paired breast cancer samples and their matched non-cancerous samples obtained from adjacent tissues. HOTTIP expression was significantly higher in breast cancer tissues compared with adjacent tissues (expression ratio (95% CI)= 4.63 (1.56-13.76), P value= 0.0070). Similarly, CBR3-AS1 was up-regulated in cancerous tissues compared with control tissues (expression ration (95% CI)= 3.26 (1.35-7.86), P value= 0.0122). Expression of HOTTIP was higher in estrogen receptor (ER) negative samples compared with ER positive ones (-4.35 ± 1.33 versus -4.63 ± 0.62, P value=0.002). CBR3-AS1 could differentiate between these two sets of samples with AUC±SD, sensitivity, specificity and P values of 0.7 ± 0.05, 0.9, 0.49 and 0.003, respectively. These values were 0.68 ± 0.04, 0.87, 0.34 and 0.04 for HOTTIP. Although we could not find difference in expression of CCND1 between these two sets of samples, we reported up-regulation of two CCND1-related lncRNAs in breast cancer samples. These lncRNAs are putative markers for breast cancer.