LRRC1 (leucine-rich repeat containing 1) is a cytoplasmic protein with emerging roles in cellular regulation and cancer biology. Primary Function: LRRC1 functions as a cell polarity regulator 1 and is a vertebrate paralog of the SCRIB tumor suppressor 2. It is a PPARγ target gene involved in adipocytic differentiation 3. Mechanism: LRRC1 regulates multiple signaling pathways depending on cellular context. In hepatocellular carcinoma (HCC), LRRC1 enhances PDK1 stability through USP7-mediated deubiquitination, activating the AKT/GSK3β/β-catenin/VEGFA pathway to promote tumor angiogenesis 4. In acute myeloid leukemia (AML), LRRC1 interacts with MACF1 to activate β-catenin/c-Myc signaling 5. In breast cancer, LRRC1 depletion increases WNT ligand secretion, promoting stem cell self-renewal via paracrine WNT/β-catenin signaling 2. Disease Relevance: LRRC1 is aberrantly upregulated in HCC (66.1% of specimens) and correlates with poor prognosis 16. It is upregulated in AML bone marrow with reduced overall survival 5. LRRC1 also associates with preeclampsia as a diagnostic biomarker 7. Clinical Significance: LRRC1 represents a potential therapeutic target in cancer and a biomarker for patient stratification, particularly for WNT/β-catenin pathway inhibitor responsiveness 2.