The prognostic and predictive values of differential expression of exosomal receptor tyrosine kinases and associated with the PI3K/AKT/mTOR signaling in breast cancer patients undergoing neoadjuvant chemotherapy.

Abstract

Cancer cell-derived exosomes are the mediator of the tumor microenvironment and the molecular content of exosomes presents a promising prognostic or predictive marker in tumor progression and the treatment response of cancer patients. The aim of this study was to identify the expression levels of receptor tyrosine kinases (RTKs) and AKT1 and mTOR before and after neoadjuvant chemotherapy (NACT) in the exosomes of BC patients compared with healthy females. After isolating exosomes in the serum of 25 BC patients and characterization by flow cytometry, the mRNA levels of FGFR2, FGFR3, PDGFRB, AKT1 and mTOR in the exosomes were analyzed by RT-PCR. Our preliminary findings showed that FGFR2, PDGFRB, AKT1 and mTOR levels were significantly upregulated in BC patients before NACT compared with the healthy group (p < 0.05). Furthermore, the mRNA levels PDGFRB and AKT1 were significantly down-regulated after NACT compared with control. PDGFRB expression level could predict pathological non-response and significantly correlated with tumor size after NACT. Therefore, especially FGFR2, PDGFRB and AKT1 could be a therapeutic target as a prognostic marker, whereas PDGFRB may be a promising predictive indicator of therapy response in BC patients. However, the prognostic or predictive role of RTKs and PI3K/AKT/mTOR signaling in the exosomes should be further investigated in a large patient population.