PRMT1 and cancer: Mediation of Drug Resistance and Immunosuppression: In triple-negative breast cancer (TNBC), PRMT1 methylates PARP1 (R18), enhancing DNA repair and leading to chemotherapy resistance, and activates the NF-κB pathway to promote the secretion of factors such as IL-1β, maintaining the characteristics of cancer stem cells, reducing CD8+ T cell infiltration, and inducing the expression of inhibitory immune checkpoints like LAG3, thereby creating an immunosuppressive microenvironment [27].