Small cell lung cancer responds to inhibition of Jumonji enzyme in vitro and in vivo

Small-cell lung cancer (SCLC) arises from neuroendocrine cells within the lung. Along with deletion or loss of function Rb and TP53 mutations, which occur in almost all cases, subsets of SCLC are driven by specific transcription factors including ASCL1, NEUROD1, POU2F3, or YAP1. Various MYC family members provide further inter-tumor heterogeneity. Despite this heterogeneity in SCLC, current treatment for SCLC is subtype agnostic. Although most patients are initially responsive to first line etoposide and platin chemotherapy they soon develop resistance with no effective second line therapy. A recent large NCI screen showed that over 60 SCLC cell line models responded to 500+ investigational drugs in a manner highly correlated with etoposide responses, suggesting none of these drugs would provide benefit for SCLC therapy beyond current chemotherapy. By analyzing publicly available data of shRNA and CRISPR screens in addition to our own RNA-seq expression data we identified KDM4A as a potential candidate to target in SCLC. To underscore the potential of KDM4A as an anti-SCLC target, we tested chemotherapy drug and three JmjC KDM inhibitors across a panel of SCLC cell lines representing all the SCLC transcription factor subtypes and found that SCLC responses to JmjC KDM inhibitors do not correlate to their responses to chemotherapy. Furthermore, we found upon treatment with pan-JmjC KDM inhibitor, JIB-04, many genes in the ER stress signaling pathways are upregulated in SCLC lines, suggesting this is the mechanistic path leading to SCLC slower growth or death. Additionally, analysis found that JIB-04 resistant cells activate pro-survival pathways such as mTOR to perhaps overcome the effects of JIB-04 treatment. Furthermore, the loss of KDM4A in SCLC cell line led to slower proliferation and activity in the ER stress signaling pathway.