Gene expression of LncRNA CASC9, miR-590-3p, and NF-κB p65, and immunohistochemical expression of BAX and BCL-2 in breast cancer tissues.

BACKGROUND: Cancer susceptibility candidate 9 (CASC9) has been implicated in several cancers through interactions with miR-590-3p, a microRNA with context-dependent oncogenic or tumor-suppressive functions. Dysregulation of this regulatory network may influence NF-κB signaling, a major pathway involved in tumor cell survival, proliferation, inflammation, and metastasis. Activation of NF-κB signaling can promote an anti-apoptotic phenotype, including increased BCL-2 activity and suppression of BAX-mediated apoptosis. In our study, we investigated the expression of LncRNA CASC9, miR-590-3p, and NF-κB p65 in Egyptian females with breast cancer (BC) and their associations with clinicopathological features and BAX and BCL-2 immunohistochemical (IHC) expression. PATIENTS AND METHODS: This prospective paired tumor-adjacent tissue study included 71 patients with histopathologically confirmed BC. LncRNA CASC9, miR-590-3p, and NF-κβB p65 gene expressions in BC tissues were measured by quantitative reverse-transcription real-time polymerase chain reaction (RT-qPCR). Additionally, BAX and BCL-2 IHC expression was analyzed in BC tissues. Moreover, serum CA 15-3 was measured by electrochemiluminescence immunoassay (ECLIA). RESULTS: Significantly upregulated LncRNA CASC9 and NF-κB p65, and significantly downregulated miR-590-3p were detected in BC tissues compared to adjacent non-neoplastic tissues. LncRNA CASC9 expression showed significant associations with T-stage (P = 0.021) and extensive intraductal component (EIC) (P = 0.008). NF-κB p65 expression had significant associations with grade (P = 0.02), skin invasion (P = 0.003), T-stage (P = 0.015), N-stage (P = 0.002), EIC (P = 0.006), and stage (P = 0.028). miR-590-3p expression had significant associations with skin invasion (P = 0.004), T-stage (P = 0.037), N-stage (P = 0.03) and EIC (P = 0.006). LncRNA CASC9 expression showed a positive correlation with NF-κB p65 expression (r = 0.333, P = 0.005). miR-590-3p expression showed a negative correlation with NF-κB p65 expression (r=-0.319, P = 0.007), and a positive correlation with event-free survival (EFS) (r = 0.325, P = 0.006). Survival analysis showed that higher LncRNA CASC9 and NF-κB p65 were associated with significantly poorer overall survival (OS) than those with lower expression (log-rank = 5.01, P = 0.025 and log-rank = 9.19, P = 0.001, respectively), while those with higher miR-590-3p had significantly better OS than those with lower expression (log-rank =19.08, P < 0.001). The receiver operating characteristic (ROC) curve analysis revealed that NF-κB p65 and miR-590-3p expressions showed good discriminatory performance for mortality (AUC = 0.765, 95% CI: 0.61-0.92, P = 0.001 and AUC = 0.868, 95% CI: 0.78-0.95, P < 0.001, respectively), with high sensitivity (90.9% and 100%, respectively) and moderate specificity (61.7% and 76.7%, respectively). CONCLUSION: Upregulated LncRNA CASC9 and NF-κB p65, and downregulated miR-590-3p were associated with an unfavorable prognosis in BC, with reduced OS and EFS. Particularly, NF-κB p65 and miR-590-3p showed moderate discriminatory performance for mortality and relapse in our study. BCL-2 IHC expression showed significant associations with T-stage, LVI, advanced stage, and negative BAX IHC expression, and BAX IHC expression showed a significant association with LVI. The multivariable model showed that low miR-590-3p and high NF-κB p65 expression remained independently associated with an increased risk of relapse.