Nano-diamino-tetrac (NDAT) inhibits PD-L1 expression which is essential for proliferation in oral cancer cells

Abstract Programmed death-ligand 1 ( PD-L1) is a critical regulator to defend tumor cells against immune surveillance. Thyroid hormone has been shown to induce PD-L1expression in cancer cells. Its nano-particulated analogue, nano-diamino-tetrac (NDAT; Nanotetrac) is an anticancer/anti-angiogenic agent. In the current study, the inhibitory mechanism by which NDAT inhibited PD-L1mRNA abundance and PD-L1protein content in oral cancer cellswas investigated. NDAT inhibited inducible PD-L1expression and protein accumulation by the inhibition of activated ERK1/2 and PI3K. Knockdown PD-L1also inhibited the proliferation of oral cancer cellswhich suggests that the inhibitory effect of NDAT on PD-L1expression maybe is one of the critical mechanisms for NDAT-induced anti-proliferative effect in oral cancer cells.