Protopanaxadiol as a Dual-Action Therapeutic Agent: Enhancing Radiotherapy Efficacy and Mitigating DMBA-Induced...

Breast cancer remains a leading cause of cancer-related mortality, with radiotherapy often limited by tumor resistance and systemic toxicity. Protopanaxadiol (PPD), a bioactive ginsenoside metabolite, has emerged as a promising adjunct due to its multifaceted pharmacological properties. This study aimed to evaluate PPD's dual role as a radiosensitizer and cytoprotective agent in breast cancer, integrating in vitro, in vivo, and in silico approaches to elucidate its mechanisms.

In vitro cytotoxicity and cell cycle effects were assessed in MCF-7 cells treated with PPD alone or combined with γ-irradiation (6 Gy) using MTT assay and flow cytometry. A total of 96 female mice were used, including 60 for LD50 determination and 36 for efficacy evaluation. For in vivo studies, female albino mice (n=36) were divided into six groups: (1) normal control, (2) PPD alone (90 mg/kg orally for 8 weeks), (3) DMBA-induced breast cancer (7.5 mg/kg subcutaneously twice weekly for 4 weeks), (4) DMBA+PPD, (5) DMBA+ γ-irradiation (6 Gy/week for 3 weeks), and (6) DMBA+ γ-irradiation+ PPD. Haematological parameters (Hb%, RBCs, WBCs, serum iron), lipid profiles (TC, TG, HDL-C), oxidative stress markers (GSH, SOD, CAT, MDA), and apoptotic proteins (Bax, Bcl-2, caspase-3/9, p53) were analyzed in blood and tissue samples. Gene expression of HIF-1α, PHD2, and NF-κB was evaluated by qRT-PCR. Histopathological examination of breast tissue assessed morphological changes. Molecular docking predicted PPD's binding affinity to target proteins (HIF-1α, NF-κB, PHD2), and ADMET analysis evaluated pharmacokinetic properties.

PPD significantly enhanced the cytotoxic effects of γ-irradiation, reducing the IC50 by 41%, and induced cell cycle arrest at both G0/G1 and G2/M phases. In vivo, PPD restored haematological parameters (increased Hb%, RBCs, and iron; decreased WBCs), improved lipid profiles (reduced total cholesterol and triglycerides; increased HDL-C), and mitigated oxidative stress (elevated GSH, SOD, and CAT; decreased MDA). It rebalanced apoptotic markers (downregulated Bax, caspase-3, caspase-9, and p53; upregulated Bcl- 2) and modulated gene expression (suppressed HIF-1α and NF-κB; enhanced PHD2). Histopathology confirmed reduced malignancy and fibrosis. Molecular docking revealed strong binding to HIF-1α (-9.16 kcal/mol), NF-κB (-8.88 kcal/mol), and PHD2 (-8.23 kcal/mol). ADMET profiling indicated favourable drug-likeness and safety.

These findings demonstrate that PPD exerts multimodal anti-cancer effects by enhancing radiosensitivity, rebalancing oxidative status, and modulating hypoxia and inflammation pathways. Its high docking affinities and pharmacokinetic traits suggest clinical potential. Limitations include the absence of metastatic or long-term survival models.

PPD demonstrates a unique dual capacity to enhance radiotherapy efficacy while protecting against treatment-induced toxicity, mediated through multi-target regulation of hypoxia, inflammation, and apoptosis pathways. These findings position PPD as a promising candidate for adjunctive breast cancer therapy, warranting further clinical exploration.