Pre-treatment with angiotensin-(1-7) inhibits tumor growth via autophagy by downregulating PI3K/Akt/mTOR signaling in human nasopharyngeal carcinoma xenografts.

The highest incidence of nasopharyngeal carcinoma (NPC) is in southeast China, including Taiwan. Many side effects have been observed following radiation therapy with chemotherapy; hence, exploring new treatment modalities for NPC is an important future direction. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous heptapeptide hormone and important component of the renin-angiotensin system that acts through both the Mas receptor and AT2 receptor, exhibiting anti-proliferative and anti-angiogenic properties in cancer cells. However, the anti-cancer activity of Ang-(1-7) related to autophagy in NPC remains largely debated. The effects and signaling pathway(s) involved in the Ang-(1-7)/Mas receptor axis in NPC were investigated both in vitro and in vivo. Ang-(1-7) inhibited cell proliferation, migration, and invasion in NPC-TW01 cells. Ang-(1-7) induced autophagy by increasing the levels of the autophagy marker LC3-II and by enhancing p62 degradation via activation of the Beclin-1/Bcl-2 signaling pathway with involvement of the PI3K/Akt/mTOR and p38 pathways in vitro study. In addition, pre-treatment with Ang-(1-7) inhibited tumor growth in NPC xenografts by inducing autophagy, suggesting a correlation between PI3K/Akt/mTOR pathway inhibition and the abovementioned anti-cancer activities. However, no autophagy was observed following Ang-(1-7) post-treatment. Taken together, these data indicate that Ang-(1-7) plays a novel role in autophagy downstream signaling pathways in NPC, supporting its potential as a therapeutic agent for alleviation the incidence of NPC and preventive treatment of recurrent NPC. KEY MESSAGES: Ang-(1-7) inhibits cell proliferation, migration, and invasion by activating autophagy Ang-(1-7)pre-treatment inhibits tumor growth via autophagy by suppressing PI3K/Akt/mTOR pathway. Ang-(1-7) may provide a novel preventative treatment for NPC and recurrent NPC.