STEAP1 blocking peptide

Six-transmembrane epithelial antigen of prostate-1 (STEAP1) is a relatively newly identified gene target from prostate cancer, breast cancer, and gastric cancer. However, functions of STEAP1 in lung adenocarcinoma (LUAD) are still unknown. In the present study, we explored the molecular and cellular mechanisms of STEAP1 in LUAD. Western blot and Q-PCR were conducted to detect the protein and mRNA expressions respectively. The cell proliferation was tested by CCK8 assay. The effects of STEAP1 on the metastasis and epithelial-mesenchymal transition (EMT) of LUAD were evaluated by EdU assay, wound healing assay, and transwell migratory assay. H1650, H358, HCC827, H1299, H23, A549, H1693 were selected as human LUAD cell lines in the study. Results have shown that STEAP1 expression was up-regulated in LUAD cells compared with normal lung epithelial cells. Knockdowning of STEAP1 suppressed the proliferation, migration, and invasion of LUAD epithelial cells. Importantly, after comparing the proliferation, migration, and invasion of LUAD to the corresponding control groups treated in STAT3 inhibitor ADZ1480, we found that STEAP1 regulates EMT via Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway. In conclusion, STEAP1 can serve as a therapeutic target, and it may have important clinical implications for LUAD treatment.

The over-expression of six-transmembrane epithelial antigen of the prostate 1 (STEAP1) underlies the pathogenesis of a large subset of human cancers. Expressed on the cancer cell surface, STEAP1 is an attractive target for antibody-based therapy or immunotherapy. However, its role in modulating the pathophysiology of colorectal cancer (CRC) remains relatively unexplored. In this study, we first demonstrated that the STEAP1 transcript level was significantly higher in CRC tissues than in normal colonic tissues. Of note, STEAP1 expression negatively correlated with overall survival as determined from a publicly accessible gene expression profile data set. A loss-of-function approach in cultured CRC cell lines revealed that STEAP1 silencing suppressed cell growth and increased reactive oxygen species (ROS) production, followed by apoptosis, through an intrinsic pathway. Mechanistically, the inhibition of STEAP1 was associated with decreased expression of antioxidant molecules regulated by the transcription factor, nuclear erythroid 2-related factor (NRF2), in CRC cells. Taken together, we identified high STEAP1 transcript levels leading to reduced ROS production that prevented apoptosis via the NRF2 pathway in CRC cells as a pathological mechanism in CRC. This study highlights the STEAP1-NRF2 axis as a therapeutic target for CRC and its manipulation as a novel strategy to conquer CRC.