PKCα regulates the secretion of PDL1-carrying small extracellular vesicles in a p53-dependent manner

Small extracellular vesicles (sEVs), carrying PD-L1, have been implicated in immune evasion and tumor progression. However, understanding how PD-L1 sEVs are secreted still needs to be improved. We found that the secretion dynamics of PD-L1 sEVs is similar to that of other sEVs. Intracellular calcium and the associated downstream PKC signaling plays pivotal roles in releasing PD-L1 sEVs in non-small cell lung cancer cells (NSCLC). Particularly, we observed that knocking down PKC alpha has profound impacts on PD-L1 sEVs secretion, especially in the resting state and in the activated state, when induced by an intracellular calcium rise. Furthermore, our study revealed that PKC alpha regulates PD-L1 expression and PD-L1 sEVs secretion by influencing STAT1 phosphorylation and nuclear translocation in a p53-dependent manner. Notably, p53 can regulate STAT1 phosphorylation and nuclear localization, but it does not affect PKC alpha expression. This suggests that PKC alpha plays a significant role in regulating PD-L1 expression. Our findings suggest that targeting PKC alpha to modulate PD-L1 dynamics in NSCLC may be a promising therapeutic strategy to enhance the efficacy of immunotherapeutic interventions.