CREPT promotes LUAD progression by enhancing the CDK9 and RNAPII assembly to promote ERK-driven gene transcription

<b>Background:</b> Despite advancements in EGFR- and KRAS-targeted therapies for lung adenocarcinoma (LUAD), novel targets are needed for patients unresponsive or resistant to current treatments. This study demonstrates the critical role of CREPT in modulating ERK-downstream gene transcription in LUAD progression. <b>Methods:</b> CREPT expression and function were investigated using human LUAD tissues, EGFR/KRAS mutant LUAD cell lines, and mouse models. Micro-CT was used to monitor tumor progression. Adeno-associated virus (AAV)-mediated CREPT depletion was employed as a therapeutic strategy. RNA sequencing and luciferase reporter assays identified differentially expressed genes (DEGs) and affected signaling pathways. Protein interactions and CDK9 occupancy were assessed using multiplex immunofluorescence, immunoprecipitation, and chromatin immunoprecipitation (ChIP). <b>Results:</b> CREPT overexpression correlated with poor LUAD patient survival and enhanced tumorigenesis in EGFR or KRAS mutant LUAD cells. <i>CREPT</i> deletion impaired LUAD initiation and progression in the CC10-rtTA;TetO-<i>KRAS^G12D</i> mouse model. Mechanistically, CREPT promoted CDK9 assembly with RNA polymerase II (RNAPII) following ERK activation, enhancing transcription of malignancy-related genes downstream of KRAS-ERK-Elk-1 signaling. CREPT depletion and the mutants R106A and S134A disrupting CREPT-RNAPII interaction reduced CDK9 occupancy at Elk-1 downstream gene promoters and their expression. Targeting CREPT in both CC10-rtTA;TetO-<i>KRAS^G12D</i> and xenograft mouse models resulted in tumor growth arrest. Furthermore, in a humanized mouse model, AAV-mediated CREPT silencing inhibited tumor progression and showed synergistic potential with pembrolizumab. <b>Conclusion:</b> Our findings highlight CREPT as a pivotal regulator of LUAD progression and suggest it could be a potential therapeutic target for patients with EGFR or KRAS mutations insensitive or resistant to targeted therapies.