TGF-β and EGF induced HLA-I downregulation is associated with epithelial-mesenchymal transition (EMT) through upregulation of snail in prostate cancer cells

• HLA-I expression was downregulated during EMT driven by TGF-β and EGF.
• Snail is crucial for TGF-β and EGF-mediated downregulation of HLA-I.
• Downregulation of HLA-I during EMT may depend on the association of Snail and NF-κB.

Human leukocyte antigen class I antigens (HLA-I) is essential in immune response by presenting antigenic peptides to cytotoxic T lymphocytes. Downregulation of HLA-I is observed in primary and metastatic prostate cancers, which facilitates them escape from immune surveillance, thereby promotes prostate cancer progression. In addition, elevated level of growth factors like TGF-β or EGF in microenvironment is related to the prostate cancer deterioration. Thus, we wondered whether TGF-β or EGF was involved in the regulation of HLA-I during the development of prostate cancer cells. In this study, we demonstrated that TGF-β and EGF both downregulated the expression of HLA-I, thereby attenuated the cytotoxic T cell mediated lysis of prostate cancer cells. Next, we revealed that TGF-β and EGF induced downregulation of HLA-I is associated with classical epithelial-mesenchymal transition (EMT) morphological changes and expression profiles. We further illustrated that overexpression of Snail is crucial for HLA-I downregulation and its association with EMT. At last, we discussed that NF-κB/p65 is the plausible target for Snail to induce HLA-I downregulation. Taken together, this is the first evidence to reveal that both TGF-β and EGF can induce HLA-I downregulation which is then proven to be associated with EMT in prostate cancer cells. These discoveries provide a deeper understanding of growth factors induced immune escape and introduce potential therapeutic targets for prostate cancers.