Background: Classification of breast cancer (BC) in the molecular subtypes had the enormous impact on the development of the individualized therapy. Nevertheless, there is a need for additional biomarkers that would help to refine molecular subtypes of BC and propose the therapeutic approach for each patient.
Aim: To study differential expression patterns of AIP, UCKL1, and PKN1 genes in blood sera and tumor tissue of patients with BC of different molecular subtypes.
Materials and methods: The total extracellular RNA was isolated from serum of 26 BC patients. cDNAs was synthesized and quantitative polymerase chain reaction was performed. Also, immunohistochemical studies of UCKL, AIP and PKN1 were performed on deparaffined tissue sections. The study was supplemented by a bioinformatic analysis of the publicly available databases.
Results: AIP and UCKL-1 extracellular mRNA levels were 100-1000-fold increased in blood sera of all BC patients, compared to the healthy donors. The highest levels were detected in the luminal A and HER2 (ERRB2) BC subtypes. The highest levels of PKN1 were detected blood sera of the patients with luminal B and basal subtypes; its expression levels were just 10-100-fold higher in BC samples compared to healthy donors.
Conclusions: The UCKL1, AIP, PKN1 genes are overexpressed at the mRNA level in blood sera of BC patients compared to the sera of healthy individuals. Among three genes under study, only for the AIP gene, the pattern of extracellular mRNA expression in sera paralleled to protein expression in BC tissues of each specified molecular subtype.