Expression of Axl Receptor Tyrosine Kinase and Its Association With Ki-67 Proliferation Marker, BCL-2 Anti-apoptotic Protein, Hormone Receptor Status, and HER2/Neu Status in Breast Cancer Among Women From Duhok, Iraq

Background Breast cancer (BC) is the most prevalent cancer among women worldwide, contributing to high mortality rates, especially in Iraqi women. Detecting the disease before metastasis may increase survival chances for many patients, but that is not the case for most of them. Thus the search for new prognostic biomarkers or testing the relevance of existing ones could contribute to therapeutic decisions complementing the traditional methods, including TNM (tumor, node, and metastasis) staging, tumor grade, and other clinicopathological features in addition to the use of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu). The Axl receptor is frequently associated with invasion, migration, poor prognosis, and angiogenesis. Furthermore, its association with chemotherapy and targeted therapy resistance makes it an ideal biomarker for therapeutic targeting. Methodology This study involved 50 malignant cases with 25 benign fibroadenoma and non-neoplastic cases represented by inflammatory conditions, collected with their corresponding data from the central lab in Duhok Governorate, Iraq. Expression of Kiel 67 (Ki-67) proliferation marker and B-cell lymphoma 2 (BCL-2) anti-apoptotic protein was measured using immunohistochemistry (IHC) to estimate tumor growth and apoptosis. Gene expression of the Axl receptor was evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results Cases with high Ki-67 accounted for 68% and low Ki-67 cases were 32% across the graded groups and were significantly associated with tumor grade, PR, and HER2. BCL-2-negative cases accounted for 62% and BCL-2-positive cases were 38%. It was revealed that BCL-2 had a strong correlation with age, especially in those under 50 years. As for the Axl gene expression, the average fold change in expression in the high-grade (H.) group was 1.74 times higher than in the control group, while in the low/intermediate (L.) group, it was 3.74 times higher. Additionally, when comparing these results with other variables, no significant associations were observed. Conclusion Axl receptor was not associated with all of the clinicopathological variables, the expression values were high in malignant tumors in comparison with the benign tumors, and it was found that Axl receptor expression was associated with low/intermediate grade, which is considered a favorable prognostic factor. Although Axl receptor expression was previously linked with proliferation and invasiveness in BC, its association with the Ki-67 proliferation marker and BCL-2 anti-apoptotic protein was not observed.