ING4 Expression Landscape and Association With Clinicopathologic Characteristics in Breast Cancer

Breast cancer (BC) development and progression is complex and still not fully understood. The expression or dysregulation of a variety of transcription factors has been suggested as contributing to disease severity and a poor prognosis. Therefore, the present study was designed to systematically outline ING4 expression and characteristics in clinical samples and cell lines of BC. A METABRIC (Molecular Taxonomy of Breast Cancer International Consortium) dataset was obtained from a cBioPortal public domain. ING4 gene expression, putative copy number alterations, and pertinent tumor information were retrieved. ING4 gene expression was identified for 1904 BC patients. ING4 mRNA expression data in BC cell lines were obtained from the Cancer Cell Line Encyclopedia. Analyses were conducted for associations between ING4 expression and age at diagnosis, tumor clinicopathologic characteristics, and molecular subtypes. The prognostic value of ING4 in BC patients was evaluated using Kaplan-Meier survival analysis. The ING4 mRNA expression log intensity mean was 6.95, and 1005 (52.8%) of patients were determined to have high ING4 mRNA expression (mRNA log intensity > 6.95). Although ING4 gene expression correlated significantly and negatively with the Nottingham Prognostic Index and the number of positive lymph nodes (P < .05) and positively with overall survival time (P < .001). However, these correlations were weak in magnitude (r ∼ 0.1). The expression of ING4 was significantly associated with tumor grade, hormone receptor expression, human epidermal growth factor receptor 2, and molecular subtype. ING4 copy number alteration was also significantly associated with several clinicopathologic and prognostic factors. Kaplan-Meier survival analysis demonstrated greater overall survival for BC patients with high ING4 expression (P = .0046). Stratification of the data by menopausal status and tumor characteristics revealed a significant effect of ING4 expression on survival among premenopausal patients and women with a nonluminal subtype. Furthermore, the expression of ING4 in BC cell lines was significantly greater in luminal A and basal-like cells compared with human epidermal growth factor receptor 2-positive cells, which was also observed in the clinical samples. The present study showed that ING4 gene expression is modulated in BC. High ING4 gene expression was associated with favorable prognostic parameters and positive clinical outcomes in our series of BC patients.