Intrinsic electrical activity drives small-cell lung cancer progression

Elevated or ectopic expression of neuronal receptors and ion channels promotes tumor progression in many cancer types; neuroendocrine (NE) transformation of various adenocarcinomas has also been associated with increased aggressiveness. Whether the defining neuronal feature, namely electrical excitability, exists in cancer cells and whether this impacts cancer progression remains mostly unexplored. Small cell lung cancer (SCLC) is an archetypical example of highly aggressive NE cancers and is comprised of two major distinct subtypes of cancer cells: NE cells and non-NE cells. Here, we show that the NE cells are excitable, like neurons, while non-NE cells cannot fire action potentials, like astrocytes and other non-excitable cells. Action potential firing in NE cells directly promotes SCLC malignancy; however, the high ATP demand of electrical activity also leads to an unusual dependency on oxidative phosphorylation (OXPHOS) in NE cells. This finding contrasts with most cancer cells reported in the literature, which are non-excitable and heavily rely on aerobic glycolysis. Additionally, we find that non-NE cells metabolically support NE cells to supply their high ATP demand, promoting their excitability and malignancy, a process akin to the astrocyte-neuron metabolite shuttle. Lastly, we observe drastic changes in the innervation landscape during SCLC progression, which coincide with increased intratumoral heterogeneity (ITH) and elevated neuronal protein expression in SCLC cells, suggesting an induction of a tumor autonomous vicious cycle driven by cancer cell-intrinsic electrical activity, which confers long-term tumorigenic capability and metastatic potential.