Introduction: Prostate cancer (CaP) is one of the most frequent malignancies amongst men throughout the world. CaP cells exhibit aberrant signaling pathways. Signaling biomolecules such as β-Catenin, c-FLIPL, and c-MYC play a very important role in CaP. Lupeol, a pentacyclic triterpene found in fruits, vegetables, other dilatory natural agents, was found possesses strong antioxidant, and anticancer properties. Enzalutamide is the second-generation androgen receptor antagonist having the strong binding affinity and has been permitted by the USFDA against CaP.

Objectives: We determined (a) the mechanism-based efficacy of Lupeol (Lup-20(29)-en-3b-ol) alone or in combination with enzalutamide as a potent c-MYC, cFLIP and β-Catenin inhibitor in both in silico and in vitro studies and (b) amelioration of Enzalutamide induced toxicity by Lupeol in in vivo condition.

Methods: For in silico studies, molecular docking, MD Simulation [RMSD, RMSF, SASA, Rg, number of H-bonds, PCA and Columbic and Lennard-Jones]. For in vitro studies, normal prostate cell (PNT2), 22Rν1, C4-2b and Du145 cells were used. We considered CD133+/CD44+ positive cells are Cancer Stem Cells (CSCs). The cells were treated with either Lupeol (10-50 μM), or enzalutamide (1.0-10 μM), or combination. The treated cells were tested for cell growth, rate of proliferation, Scratch assay, dye exclusion assay, and luciferase-based reporter assay. Animal studies were done on Swiss albino mice. Animals were treated either lupeol/enzalutamide alone or in combination for 48 h. Next, biochemical assays such as GST, GPx, CAT, SOD activities and MDA levels were examined. We also examined the amelioration of genotoxicity by lupeol induced by enzalutamide.

Results: Lupeol is found to dock with -7.1, -6.6, and -7.3 as well as enzalutamide was found to dock with -6.8, -6.0, -7.5 against β-Catenin, c-FLIPL, and c-MYC, respectively. Furthermore, there are good number of hydrogen and hydrophobic interactions between the ligands and proteins. MD simulation data shows further information on interactions between ligands and proteins. This in silico study were verify through in vitro assay performed on CaP cells. Lupeol significantly inhibits the growth of CSCs sparing normal cells and chemosensitize the CSCs for enzalutamide. Lupeol alone or in combination with enzalutamide also significantly inhibit the wound healing of CSCs. Finally, lupeol significantly ameliorates the toxicity caused by FDA approved drug enzalutamide as evident from genotoxicity assay (Chromosome aberration assay & MNT) and Biochemical assays.

Conclusion: We suggest that lupeol alone or as an adjuvant to current therapies could be developed as an agent to chemosensitize the therapy resistant cells as well as to ameliorate the enzalutamide induced toxicity.

Citation Format: Hifzur R. Siddique, Santosh K. Maurya. Lupeol chemosensitize the cancer stem cells for enzalutamide and ameliorate the enzalutamide induced toxicity in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 276.