A comprehensive analysis of the expression and regulation network of lymphocyte-specific protein tyrosine kinase in breast cancer

BACKGROUND: Lymphocyte-specific protein tyrosine kinase (LCK), an encoded Src family protein tyrosine kinase, performs a pivotal molecular signaling role in the selection and maturation processes during T-cell development. Although aberrant LCK expression is known to have a significant association with carcinogenesis, the underlying role of LCK in breast cancer (BC) is still obscure. METHODS: An analysis of the levels of LCK mRNA expression in BC was performed, and the value of LCK expression for predicting the prognosis of patients with BC was studied using various online data resources, which included Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), and UALCAN. The web-based NetworkAnalyst tool was utilized to investigate the functional network of differentially expressed LCK. LinkedOmics was employed to identify the genes with which LCK has correlations in BC, together with the kinases, microRNAs, and transcription factors (TFs) potentially targeted by LCK in BC. The expression levels of LCK and its significantly correlated genes in BC were investigated with the Human Protein Atlas (HPA). RESULTS: We observed a significant difference in the level of LCK mRNA expression between BC patients and healthy individuals, and a higher LCK expression was associated with poor overall survival (OS). The functional enrichment results revealed that the differential expression of LCK was mainly involved in the regulation of immune response and inflammatory response in BC. The expression of significantly related genes, such as inducible T-cell kinase (ITK), CD5, CD96, CD247, SH2 domain containing 1A (SH2D1A), phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CD), Src-like-adaptor 2 (SLA2), and interleukin 2 receptor (IL2RG), was associated with poor OS in patients with BC. Regulatory network analysis found that LCK regulated immune cells, cancer progression, apoptosis, and cell cycle signal transduction through cancer-related kinases (ITK and MAPK3), miRNAs (miR-345 and miR-524), and TFs (AP1, SRF, and E2F1). CONCLUSIONS: This study presents new perspectives on the differential expression and prognostic value of LCK in BC. Our observations will provide a basis for further study on the oncogenic and regulatory roles of LCK in BC.