Skimmianine Modulates Tumor Proliferation and Immune Dynamics in Breast Cancer by Targeting PCNA and TNF-α.

: Breast cancer continues to be a major global health challenge, driving the urgent need for innovative therapeutic strategies. This study evaluates the anticancer and immunomodulatory potential of skimmianine in breast cancer through a comprehensive approach, integrating biochemical, histopathological, immunohistochemical, and bioinformatics analyses. : Thirty-six female Wistar albino rats were divided into three groups: control, 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast cancer, and DMBA + skimmianine ( = 12/group). Breast cancer was induced with a single oral dose of 50 mg/kg DMBA in sesame oil. After 16 weeks, skimmianine (40 mg/kg) was administered intraperitoneally for four weeks. Serum CA15-3 levels were measured via enzyme-linked immunosorbent assay (ELISA). Histopathological assessment was performed using hematoxylin and eosin (H&E) staining, and proliferating cell nuclear antigen (PCNA) and tumor necrosis factor-alpha (TNF-α) were evaluated immunohistochemically. Pathway and hub gene analyses were performed using Cytoscape, functional annotation with Enrichr, and immune analyses via the Tumor and Immune System Interaction Database (TISIDB) and Sangerbox. : The tumor burden in the animals increased after DMBA induction compared to the control groups (0.00 ± 0.00% vs. 89.00 ± 6.60%, respectively, < 0.001), while skimmianine treatment significantly reduced the tumor burden in the animals (49.00 ± 9.40%, vs. DMBA group, = 0.191). Histopathological analysis showed DMBA-induced structural disorganization and malignant clustering, whereas skimmianine preserved ductal structures and mitigated the damage. Compared to the control group, DMBA administration markedly elevated serum CA15-3 levels (0.23 ± 0.06 ng/mL vs. 8.57 ± 1.01 ng/mL, respectively), along with PCNA (13.0 ± 3.0% vs. 25.0 ± 4.0%, respectively) and TNF-α (8.4 ± 1.7% vs. 34.0 ± 5.3%, respectively) expression, indicating active tumor progression. Skimmianine treatment significantly reduced CA15-3 (3.72 ± 0.58 ng/mL), PCNA (20.0 ± 4.1%), and TNF-α (25.0 ± 3.9%) levels ( < 0.001). In silico analyses indicated skimmianine's effects on PCNA influence cell cycle pathways, while TNF-α suppression impacts toll-like receptor (TLR) signaling (adjusted < 0.05). PCNA- and TNF-α-related anticancer effects were especially notable in basal molecular and C2 immune subtypes ( < 0.05). Related hub proteins may regulate immune dynamics by reducing immunosuppression and tumor-promoting inflammation ( < 0.05). : Skimmianine shows promise as a breast cancer therapy by simultaneously targeting tumor growth and immune regulation, with PCNA and TNF-α identified as potential key players.