ERK-dependent DICER1 phosphorylation promotes open chromatin state and lineage plasticity to mediate tumor progression

DICER1 controls micro(mi)RNA-mediated epithelial-to-mesenchymal transition (EMT) to regulate tumorigenesis of lung adenocarcinomas (LUADs). We discovered that DICER1 is phosphorylated by ERK and nuclear translocated and phospho-DICER1 contributes to tumorigenesis. Mechanisms through which phospho-DICER1 regulates tumor progression remain undefined. We show that phospho-nuclear DICER1 associates with invasive human LUADs with oncogenic KRAS mutations and promotes late-stage tumor progression in mice with oncogenic Kras mutations. Surprisingly, phosphomimetic DICER1 regulates LUAD progression independent of miRNAs and EMT. Integrating single-cell RNA sequencing, fluorescent in situ RNA hybridization, immunofluorescence, and ATAC-sequencing, in mice, we discovered that phosphomimetic DICER1 generates an open chromatin state in the lung tumor alveolar cells leading to expression of gastrointestinal genes and altered AT2 cell identity. Strikingly, we also observe the gastric gene signature in human LUADs with phospho-DICER1 and KRAS mutations. We propose that phosphorylated nuclear DICER1 regulates chromatin remodeling leading to tumor cell reprogramming which drives lung cancer progression. ### Competing Interest Statement The authors have declared no competing interest.