The Relationship between KIT Copy Number Variation, Protein Expression, and Angiogenesis in Sporadic Breast Cancer

KIT is a protooncogene that encodes for the KIT oncoprotein, which is a transmembrane tyrosine kinase growth factor receptor that holds a critical role in a variety of normal physiological and pathological processes including angiogenesis. KIT has been shown to be involved in tumorigenesis, contributing to the development of gastrointestinal carcinoma and leukemia. A link between KIT overexpression and breast cancer development has previously been reported. In the current study, we explored KIT gene expression and exonic copy number variants (CNV) and the relationship with angiogenesis (CD34) and the clinicopathological features of breast cancer. Methods: MLPA technique was used to determine the CNV in 64 breast cancer tumor samples from patients diagnosed with primary sporadic breast cancer. Results were confirmed by quantitative PCR. Expression of KIT and CD34 was determined using immunohistochemistry (IHC). Results: Our results show that 28.1% of the tumor samples from patients with primary sporadic breast cancer had CNV in the KIT gene. Among the breast tumor samples, 54.7% showed positive KIT expression. The expression of the CD34 angiogenesis marker was reported in 43.8% of the tumor samples as low, 42.2% as moderate and 14.1% as high. A significant correlation between increased CNV of KIT exons, a high level of angiogenesis (CD34) and increased tumor grade was observed (p< 0.05). Conclusions: A significant correlation between the KIT CNV and the angiogenesis marker was found. Examining KIT expression and CNV has the potential to function as a biomarker for tyrosine kinase inhibitor drugs in breast cancer.