Soluble guanylate cyclase signalling mediates etoposide resistance in progressing small cell lung cancer

The emergence of acquired resistance to standard platinum-etoposide chemotherapy in small cell lung cancer (SCLC) is a common event. Here, the authors using paired pre-treatment and post-chemotherapy circulating tumour cell patient-derived explant (CDX) models reveal a mechanism of drug resistance in SCLC mediated by Notch and nitric oxide activation of soluble guanylate cyclase signalling. Small cell lung cancer (SCLC) has a 5-year survival rate of <7%. Rapid emergence of acquired resistance to standard platinum-etoposide chemotherapy is common and improved therapies are required for this recalcitrant tumour. We exploit six paired pre-treatment and post-chemotherapy circulating tumour cell patient-derived explant (CDX) models from donors with extensive stage SCLC to investigate changes at disease progression after chemotherapy. Soluble guanylate cyclase (sGC) is recurrently upregulated in post-chemotherapy progression CDX models, which correlates with acquired chemoresistance. Expression and activation of sGC is regulated by Notch and nitric oxide (NO) signalling with downstream activation of protein kinase G. Genetic targeting of sGC or pharmacological inhibition of NO synthase re-sensitizes a chemoresistant CDX progression model in vivo, revealing this pathway as a mediator of chemoresistance and potential vulnerability of relapsed SCLC.

Automated summary

In small cell lung cancer, acquired resistance to standard platinum-etoposide chemotherapy often occurs, with Notch and nitric oxide pathways playing a role in mediating this resistance. Upregulation of soluble guanylate cyclase in residual tumor cells is associated with chemoresistance, highlighting this pathway as a potential target for treating relapsed SCLC.