angiotensin-i and Nasopharyngeal-Neoplasms

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.

Topics: Angiotensin I; Animals; Autophagy; Cell Line, Tumor; Down-Regulation; Humans; Male; Mice, Nude; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Peptide Fragments; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

Angiotensin-(1-7) [Ang-(1-7)] is an endogenous, heptapeptide hormone acting through the Mas receptor (MasR), with antiproliferative and antiangiogenic properties. Recent studies have shown that Ang-(1-7) has an antiproliferative action on lung adenocarcinoma cells and prostate cancer cells. In this study, we report that MasR levels were significantly upregulated in nasopharyngeal carcinoma (NPC) specimens and NPC cell lines. Viral vector-mediated expression of Ang-(1-7) dramatically suppressed NPC cell proliferation and migration in vitro. These effects were completely blocked by the specific Ang-(1-7) receptor antagonist A-779, suggesting that they are mediated by the Ang-(1-7) receptor Mas. In this study, Ang-(1-7) not only caused a significant reduction in the growth of human nasopharyngeal xenografts, but also markedly decreased vessel density, suggesting that the heptapeptide inhibits angiogenesis to reduce tumor size. Mechanistic investigations revealed that Ang-(1-7) inhibited the expression of the proangiogenic factors VEGF and PlGF. Taken together, the data suggest that upregulation of MasR could be used as a diagnostic marker of NPC and Ang-(1-7) may be a novel therapeutic agent for nasopharyngeal cancer therapy because it exerts significant antiangiogenic activity.

Topics: Angiogenesis Inhibitors; Angiotensin I; Animals; Carcinoma; Cell Line, Tumor; Cell Movement; Cell Proliferation; Disease Models, Animal; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; MAP Kinase Signaling System; Membrane Proteins; Mice; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neovascularization, Pathologic; Peptide Fragments; Proto-Oncogene Mas; Receptors, Vascular Endothelial Growth Factor; Tumor Burden; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays