RRS1 (regulator of ribosome synthesis 1) is a nuclear protein essential for ribosomal large subunit assembly and 5S ribonucleoprotein particle maturation 1. In eukaryotes, RRS1 functions as a specialized chaperone that guides 5S RNA incorporation into preribosomes through interactions with ribosomal proteins Rpl5 and Rpl11, and coordinates the initial assembly conformations required for large subunit biogenesis 1. RRS1 plays critical roles in multiple cellular processes beyond ribosome assembly. In normal trophoblasts, RRS1 regulates cell proliferation, migration, and invasion; its deficiency impairs trophoblast function and is associated with early pregnancy loss 2. RRS1 also regulates nucleolar assembly and p53 homeostasis through the 5S RNP complex 1. Clinically, RRS1 is significantly overexpressed in breast cancer, hepatocellular carcinoma, and other malignancies, correlating with poor prognosis and lymph node metastasis 34. RRS1 knockdown suppresses cancer cell proliferation and induces apoptosis across multiple cancer types 56. Mechanistically, RRS1 promotes cancer progression through multiple pathways: stabilizing GRP78 to activate PI3K/AKT signaling 7, modulating the AEG-1/AKT/c-Myc axis 4, and regulating the RPL11-c-Myc-SNAIL pathway 8. RRS1 inhibition in vivo reduces tumor growth and metastasis 34, suggesting therapeutic potential.