KLK3 and prostate cancer: Therefore, the research and development of biomarkers associated with prostate cancer metastasis, including prostate-specific antigen (PSA), androgen receptor splice variant 7 (ARV7), and transforming growth factor-beta (TGFβ), might guide the early treatment decision of tumor metastasis and significantly improve outcomes (Kretschmer and Tilki, 2017; Manca et al., 2017; Bastos and Antonarakis, 2018).