EBV-LMP1 promotes radioresistance by inducing protective autophagy through BNIP3 in nasopharyngeal carcinoma

Studies have indicated that dysfunction of autophagy is involved in the initiation and progression of multiple tumors and their chemoradiotherapy. Epstein-Barr virus (EBV) is a lymphotropic human gamma herpes virus that has been implicated in the pathogenesis of nasopharyngeal carcinoma (NPC). EBV encoded latent membrane protein1 (LMP1) exhibits the properties of a classical oncoprotein. In previous studies, we experimentally demonstrated that LMP1 could increase the radioresistance of NPC. However, how LMP1 contributes to the radioresistance in NPC is still not clear. In the present study, we found that LMP1 could enhance autophagy by upregulating the expression of BCL2/adenovirus E1B 19kDa protein-interacting protein 3 (BNIP3). Knockdown of BNIP3 could increase the apoptosis and decrease the radioresistance mediated by protective autophagy in LMP1-positive NPC cells. The data showed that increased BNIP3 expression is mediated by LMP1 through the ERK/HIF1 alpha signaling axis, and LMP1 promotes the binding of BNIP3 to Beclin1 and competitively reduces the binding of Bcl-2 to Beclin1, thus upregulating autophagy. Furthermore, knockdown of BNIP3 can reduce the radioresistance promoted by protective autophagy in vivo. These data clearly indicated that, through BNIP3, LMP1 induced autophagy, which has a crucial role in the protection of LMP1-positive NPC cells against irradiation. It provides a new basis and potential target for elucidating LMP1-mediated radioresistance.

Automated summary

Studies have shown that LMP1 enhances autophagy by upregulating BNIP3 expression, leading to increased radioresistance in nasopharyngeal carcinoma cells. Through the ERK/HIF1α signaling axis, LMP1 promotes the binding of BNIP3 to Beclin1 and competitively reduces the binding of Bcl-2 to Beclin1, thereby upregulating autophagy. Knockdown of BNIP3 reduces radioresistance mediated by protective autophagy, highlighting its crucial role in LMP1-positive nasopharyngeal carcinoma cells' protection against irradiation.