Background/Objectives: Cancer is predicted to become the leading cause of premature mortality worldwide within this century. Among the hallmarks of cancer, metabolic reprogramming has received growing attention, and arginine deprivation therapy (ADT) represents a potential treatment strategy for tumors exhibiting arginine auxotrophy. Colorectal cancer cells frequently suppress the expression of argininosuccinate synthetase 1 (ASS1), rendering them dependent on extracellular arginine. However, how CRC cells adapt to and resist ADT remains largely unknown. Methods: We combined ATAC-seq and RNA-seq analyses with multiple functional assays—including CCK-8 viability, apoptosis detection, wound-healing, and transwell migration tests—to investigate the molecular basis of ADT response in cancer cells. Results: ADT markedly inhibited cancer cell proliferation (p < 0.001) and motility (p < 0.05) across three cell lines. Integrative multi-omics analyses revealed substantial chromatin remodeling and transcriptional reprogramming under ADT, with differentially expressed genes enriched in autophagy and cell-growth-related pathways. Among these, the motif CGTTTCCGGT was identified as an arginine deficiency-responsive DNA element in cancer cells, and C11orf54 showed pronounced downregulation accompanied by reduced chromatin accessibility at its genomic locus. Conclusions: These findings suggest that ADT restricts cancer cell proliferation and migration through chromatin remodeling mediated by the motif CGTTTCCGGT and the downregulation of C11orf54, identifying C11orf54 as a potential target for enhancing the efficacy of arginine deprivation therapy in cancer cells.

Background/Objectives: X-linked Alport syndrome (XLAS) arises from pathogenic variants in COL4A5. Truncating variants are generally classified as severe, but whether clinically meaningful heterogeneity exists within this group remains unclear. This study aimed to establish a novel Col4a5 knock-in mouse model based on a clinical variant and to determine whether truncating mutation position influences disease severity. Methods: A de novo COL4A5 frameshift variant, c.2440delG, was identified in a patient with severe early-onset XLAS. A Col4a5-G814fs knock-in mouse was generated by CRISPR/Cas9 on the C57BL/6J inbred mouse strain background and compared with the established Col4a5-G5X nonsense model using survival analysis, serial functional measurements, kidney histopathology, transmission electron microscopy, and RNA sequencing. Results: The Col4a5-G814fs knock-in mouse was successfully generated and showed loss of glomerular α5(IV) collagen chain expression. Compared with G5X mice, G814fs mice exhibited shorter survival (median 141 vs. 161.5 days, p = 0.0004), earlier onset of proteinuria, and more severe kidney functional decline. By 16 weeks, G814fs mice also showed more severe glomerular basement membrane abnormalities and more extensive glomerulosclerosis. RNA sequencing revealed a shared inflammatory gene signature in both models, together with selective upregulation of genes related to the PPAR signaling pathway and fatty acid metabolism in G814fs kidneys. Conclusions: This study reports a novel de novo COL4A5 frameshift variant and establishes the first Col4a5-G814fs knock-in mouse model. Direct comparison with the G5X model shows that distinct truncating COL4A5 mutations can be associated with substantially different disease severity, providing a useful platform for future mechanistic and therapeutic studies in XLAS.