Prognostic value of epithelial-mesenchymal transition related genes: SLUG and QKI in breast cancer patients.

Snail family zinc finger 2 (SLUG) is related to epithelial-mesenchymal transition (EMT). Quaking (QKI) is an RNA binding protein and has been indicated to have a relationship with EMT by recent studies. The prognostic value of SLUG and QKI in breast cancer patients still needs exploration. We conducted Immunohistochemistry (IHC) to evaluate the protein expression of SLUG and QKI and the prognostic value in 108 breast cancer (BC) patients. The Bc-GenExMiner database was used to compare the mRNA levels of two genes in different subgroups of BC patients. Kaplan-Meier plotter were used for survival data of SLUG and QKI gene. We also mined the cBioPortal database for co-expression analysis of QKI and EMT markers. Our results suggested that patients with higher expression of SLUG and QKI showed shorter overall survival time. The mRNA level of SLUG and QKI were higher in ER negative, PR negative, ≤ 51 y, and TNBC patients. SLUG mRNA showed no survival significance, while higher QKI mRNA expression level was correlated with worse clinical outcome in Kaplan-Meier Plotter database. The cBioPortal database showed that QKI was correlated to SLUG as well as other EMT markers like TWIST2, VIM, and ZEB2. QKI was indicated to be a potential prognostic marker for BC patients, and combined expression of SLUG and QKI showed the best prognostic value. Co-expression analysis indicated that QKI was likely to have a correlation with SLUG and EMT. IJCEP