The p62/Keap1/Nrf2 axis in the control of C-2 induced human gastric cancer cell death switching between autophagy and apoptosis

Abstract Background Compound C-2 is a derivative of natural product Jaspine B and possesses anti-cancer activity against bladder cancer cells. However, little is known about its anti-cancer activity against gastric cancer. In this research, mechanism underlying anti-cancer effect of C-2 in gastric cancer cells was well investigated. Methods Anti-cancer activities of C-2 were determined by MTT, western blotting and flow cytometry. A serial of specific inhibitors, immunoprecipitation, siRNA and immunofluorescence were utilized to explore signaling pathways affected by C-2. Results C-2 induces apoptosis in gastric cancer cells through the internal mitochondrial pathway, and triggers autophagy in gastric cancer cells through JNK/ERK pathway. Phosphorylated JNK/ERK further activates Beclin1 via disturbing Beclin-1/Bcl-xL or Beclin-1/Bcl-2 complexes, leading to autophagy and up-regulated p62. Next, p62 competitively binds keap1 to release Nrf2, thus promoting translocation of Nrf2 from cytoplasm to nucleus and triggering expression of Nrf2 target genes. Pharmacological inhibition or knockdown of key proteins in autophagy attenuates C-2 induced cell apoptosis, indicating that autophagy antagonizes cell apoptosis induced by C-2. Conclusion C-2 possesses anti-tumor activity against gastric cancer cells, while C-2 triggered-autophagy antagonizes cell arrest and apoptosis induced by C-2 by upregulating Nrf2 in nucleus.