Alina C. Iuga

Ferroptotic cell death and cancer Cell death can occur through different mechanisms, several of which are being explored as potential targets for cancer treatment. One form of cell death that has attracted recent interest is ferroptosis, which is triggered by high intracellular levels of lipid reactive oxygen species. Pancreatic cancer cells have high levels of reactive oxygen species but manage to avoid ferroptosis by importing extracellular cysteine. Studying mice bearing pancreatic tumors, Badgley et al. found that administration of a drug inhibiting cysteine import induced tumor-selective ferroptosis and inhibited tumor growth. Further work will be required to determine whether this therapeutic strategy will be effective in human pancreatic cancer, a tumor type for which new treatments are urgently needed. Science , this issue p. 85

Abstract In many solid tumors, parasympathetic input is provided by the vagus nerve, which has been shown to modulate tumor growth. However, whether cholinergic signaling directly regulates progression of pancreatic ductal adenocarcinoma (PDAC) has not been defined. Here, we found that subdiaphragmatic vagotomy in LSL-Kras+/G12D;Pdx1-Cre (KC) mice accelerated PDAC development, whereas treatment with the systemic muscarinic agonist bethanechol restored the normal KC phenotype, thereby suppressing the accelerated tumorigenesis caused by vagotomy. In LSL-Kras+/G12D;LSL-Trp53+/R172H;Pdx1-Cre mice with established PDAC, bethanechol significantly extended survival. These effects were mediated in part through CHRM1, which inhibited downstream MAPK/EGFR and PI3K/AKT pathways in PDAC cells. Enhanced cholinergic signaling led to a suppression of the cancer stem cell (CSC) compartment, CD11b+ myeloid cells, TNFα levels, and metastatic growth in the liver. Therefore, these data suggest that cholinergic signaling directly and indirectly suppresses growth of PDAC cells, and therapies that stimulate muscarinic receptors may be useful in the treatment of PDAC. Significance: Subdiaphragmatic vagotomy or Chrm1 knockout accelerates pancreatic tumorigenesis, in part via expansion of the CSC compartment. Systemic administration of a muscarinic agonist suppresses tumorigenesis through MAPK and PI3K/AKT signaling, in early stages of tumor growth and in more advanced, metastatic disease. Therefore, CHRM1 may represent a potentially attractive therapeutic target. Cancer Discov; 8(11); 1458–73. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1333