Abstract
Lung cancer, particularly non-small-cell lung cancer (NSCLC), remains a leading cause of cancer-related mortality worldwide. Recent studies have implicated pyrroline-5-carboxylate reductase 1 (PYCR1), a key enzyme in proline biosynthesis, in cancer progression, yet its specific role in lung cancer remains unclear. Here we demonstrate that PYCR1 plays a critical role in NSCLC progression through its functional association with the epidermal growth factor receptor (EGFR) and Toll-like receptor (TLR) signaling pathways. An analysis of patient datasets revealed that PYCR1 is upregulated in NSCLC tissues, with the enrichment of cancer-associated pathways in PYCR1-upregulated patients. Functional studies in PYCR1-knockout (PYCR1-KO) lung cancer cells generated via CRISPR-Cas9 showed reduced cell proliferation, migration, colony formation and tumor spheroid growth both in vitro and in vivo. Mechanistically, PYCR1 stabilizes EGFR by forming a complex with EGFR and USP11, thereby enhancing EGFR deubiquitination and stability. In addition, PYCR1 promotes TLR signaling by interacting with key downstream molecules, including TRAF6, TAK1, ECSIT and TAB2, facilitating their ubiquitination and NF-κB activation. The loss of PYCR1 attenuates EGFR- and TLR-induced signaling cascades, resulting in reduced activation of AKT, TAK1 and NF-κB. Importantly, treatment with PYCR1-IN-1, a selective PYCR1 inhibitor, significantly suppressed EGFR- and TLR-induced tumor spheroid growth in multiple lung cancer cell lines, underscoring PYCR1's potential as a therapeutic target. Collectively, our findings establish PYCR1 as a critical regulator of EGFR and TLR signaling pathways, driving lung cancer progression. Targeting PYCR1 with pharmacological inhibitors such as PYCR1-IN-1 offers a promising strategy for combating EGFR- and TLR-driven NSCLC progression.