Evaluation of the combined cytotoxic and apoptotic potential of green-synthesized zinc oxide nanoparticles (from Thymus vulgaris) and tamoxifen on MCF-7 breast cancer cells

Vahid Shouryabi; Mohammadreza Pourmohammad; Homa Mahmoudzadeh; Farahnaz Molavi

doi:10.1007/s10616-026-00919-7

Evaluation of the combined cytotoxic and apoptotic potential of green-synthesized zinc oxide nanoparticles (from Thymus vulgaris) and tamoxifen on MCF-7 breast cancer cells

Cytotechnology. 2026 Aug;78(4):132. doi: 10.1007/s10616-026-00919-7. Epub 2026 Jun 2.

Authors

Vahid Shouryabi¹, Mohammadreza Pourmohammad², Homa Mahmoudzadeh¹, Farahnaz Molavi¹

Affiliations

¹ Department of Biology, Ma.C., Islamic Azad University, Mashhad, Iran.
² Department of Parasitology and Mycology, School of Allied Medical Sciences, Ilam University of Medical Sciences, Ilam, Iran.

PMID: 42245620
PMCID: PMC13230432 (available on 2027-08-01)
DOI: 10.1007/s10616-026-00919-7

Abstract

The integration of green nanotechnology in oncology offers a promising path to enhance the efficacy of conventional drugs like tamoxifen while reducing systemic toxicity. This study aimed to evaluate the combined anticancer potential of biosynthesized zinc oxide nanoparticles (ZnO NPs) using Thymus vulgaris extract and Tamoxifen against MCF-7 breast cancer cells. ZnO NPs were synthesized via a green route and characterized by FESEM, XRD, and FTIR. The cytotoxic effects on MCF-7 (cancerous) and HEK-293 (normal) cells were assessed using the MTT assay. Quantitative synergy analysis was performed using the Combination Index (CI). Cell death mechanisms were investigated through Annexin V/PI flow cytometry and RT-qPCR analysis of apoptotic markers (p53, Caspase-9, and Caspase-3). Characterization confirmed the formation of crystalline ZnO nanosheets capped with T. vulgaris phytochemicals. The MTT assay revealed dose-dependent cytotoxicity, with IC50 values of 50 µM for ZnO NPs and 48 µM for Tamoxifen. Notably, the combined treatment (25 µM ZnO + 0.5vµM Tamoxifen) achieved a comparable 50% inhibitory effect, representing a massive reduction in the required dose of Tamoxifen. The treatment was selective, as HEK-293 normal cells maintained over 85% viability across the tested range. Flow cytometry demonstrated a marked increase in apoptosis in the combination group compared to monotherapies (P < 0.001). Molecular analysis showed a significant up-regulation of p53 and Caspase-9 mRNA. Despite the known CASP3 deficiency in MCF-7 cells, a significant increase in Caspase-3-like transcriptional activity was observed, suggesting the activation of alternative apoptotic pathways. T. vulgaris-mediated ZnO NPs significantly potentiate the apoptotic effect of Tamoxifen in MCF-7 cells. This synergistic combination allows for a 96-fold reduction in the Tamoxifen dose to achieve IC 50, highlighting its potential to minimize chemotherapy-related side effects while maintaining high therapeutic efficacy.

Keywords: Apoptosis; Breast cancer; Tamoxifen; Thymus vulgaris; ZnO nanoparticles.

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