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. 2024 Jun 14;10(12):e33104.
doi: 10.1016/j.heliyon.2024.e33104. eCollection 2024 Jun 30.

Citrus polymethoxyflavones degrade estrogen receptor-alpha (ERα) and combine with tamoxifen for the treatment of estrogen receptor-positive breast cancer

Affiliations

Citrus polymethoxyflavones degrade estrogen receptor-alpha (ERα) and combine with tamoxifen for the treatment of estrogen receptor-positive breast cancer

Yiyu Wang et al. Heliyon. .

Abstract

Estrogen receptor-positive (ER+) breast cancer seriously endangers the women's physical and mental health worldwide and ER targeting therapy is vital. Here, we found that a citrus polymethoxyflavones (PMFs)-rich hydrolysate (C-H) and its major components (nobiletin and 3-methoxynobiletin) potently degrade ERα protein via the ubiquitin-proteasome pathway, thereby impairing the proliferation of ER+ breast cancer cells. Moreover, our study exhibited that C-H combined with tamoxifen (TAM) inhibited the cell proliferation of ER+ breast cancer in vitro. It was further confirmed that C-H decreased tumor growth of ER+ breast cancer in tumor-bearing 129 mice in vivo and improved the efficacy of tamoxifen. Our study revealed that the citrus PMFs have potential applications as pharmaceutical and healthcare products in breast cancer treatment by targeting ERα protein degradation.

Keywords: Citrus; Estrogen receptor; Polymethoxyflavones; Tamoxifen; Ubiquitination.

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Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Zhangshuang Deng reports financial support was provided by 10.13039/501100001809National Natural Science Foundation of China. Jianjia Liang reports financial support was provided by Yichang Applied Basic Research Project. Ye Qin reports financial support was provided by opening foundation of Tumor Microenvironment and Immunotherapy Key Laboratory of Hubei province in China. Zhangshuang deng has patent pending to China Three Gorges University. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
JCCD-EXT degrades ERα proteins via the ubiquitin-proteasome system in MCF7 cells. (A) The decrease of ERα levels in JCCD-EXT-treated MCF7 cells in a dose- and time-dependent manner. (B) The mRNA levels of ESR1 in MCF7 cells treated with JCCD-EXT for 24h. (C) Half-life of ERα in MCF7 cells treated with JCCD-EXT (15 μg/mL) or/and CHX (10 μg/mL) for indicated time. (D) Densitometric analysis of ERα expression in MCF7 cells treated with JCCD-EXT (15 μg/mL) or/and CHX (10 μg/mL) for indicated time. (E, F) The protein levels and quantitative analysis of ERα in MCF7 cells treated with JCCD-EXT (30 μg/mL) for 24 h in the absence or presence of lysosomal inhibitor BafA1 (1 mM). (G, H) The protein levels and quantitative analysis of ERα in MCF7 cells treated with JCCD-EXT (30 μg/mL) for 24 h in the absence or presence of proteasomal inhibitor MG132 (5 μM). (I) The ubiquitination status of ERα in MCF7 cells treated with JCCD-EXT (30 μg/mL) in the absence or presence of proteasomal inhibitor MG132 (5 μM) .
Fig. 2
Fig. 2
3-Methoxynobiletin and nobiletin from JCCD-EXT degrade ERα protein via ubiquitin-proteasome system. (A) The chemical structures of nobiletin and 3-methoxynobiletin from JCCD-EXT. (B, C) The protein levels of ERα in MCF7 cells treated with 3-Methoxynobiletin and nobiletin, respectively. (D) The ubiquitination status of ERα protein in MCF7 cells treated with nobiletin (70 μM) or/and 3-methoxynobiletin (70 μM) in the absence or presence of MG132 (5 μM) for 24h.
Fig. 3
Fig. 3
C–H degrades ERα proteins via ubiquitin-proteasome system. (A) HPLC analysis of C–H. (B) Chemical structures of five major components in C–H. (C) The protein levels of ERα in MCF7 cells treated with components 15 at their IC50 values (1: 0.4 mM, 2: 0.28 mM, 3: 0.07 mM, 4: 0.07 mM, 5: 0.14 mM) for 24h, respectively. (D) Cell viability assays of MCF7, T47D and SSM2 cells treated with C–H for 72 h. The single concentrations were related to the IC50 respectively. (E, F, G) The decrease of ERα levels in MCF7, T47D and SSM2 cells treated with C–H in a dose- and time-dependent manner. (H, I) The protein levels of ERα in MCF7, T47D and SSM2 cells treated with C–H (MCF7: 60 μg/mL, T47D: 50 μg/mL, SSM2: 30 μg/mL) for 24 h in the absence or presence of lysosomal inhibitor BafA1 (1 μM) or proteasomal inhibitor MG132 (5 μM). (J) The ubiquitination status of ERα protein in MCF7 cells treated with C–H (60 μg/mL) for 24 h in the absence or presence of MG132 (5 μM).
Fig. 4
Fig. 4
C–H inhibits ER+ breast cancer growth in vivo. (A) The tumor growth of SSM2 in 129 mice treated with indicated dosage of C–H. (B) The tumor weight of SSM2. (C) The tumors of SSM2 were harvested at the end of experiment and photographs were showed. (D) The body weights of mice in all groups were measured every two days. (E, F) The protein levels of ERα in tumor tissues were determined by Western blot and quantitative analysis was done. *p < 0.05 compared to vehicle group.
Fig. 5
Fig. 5
C–H combined with 4OHT synergistically inhibit the cells proliferation of ER+ breast cancer in vitro. (A, C, E) Fa-CI plots of combined treatment with 4OHT and JCCD-EXT/nobiletin/3-methoxynobiletin in MCF7 cells. (B, D, F) CI values for the synergistic effect of 4OHT and JCCD-EXT/nobiletin/3-methoxynobiletin in MCF-7 cells. (G, I, K) Fa-CI plots of combined treatments with C–H with 4OHT in MCF7, T47D and SSM2 cells. (H, J, L) CI values for the synergistic effect of C–H and 4OHT in MCF7, T47D and SSM2 cells. CI values were analyzed by CompuSyn software. CI value < 1 indicates synergy; CI value > 1 indicates antagonism.
Fig. 6
Fig. 6
C–H combined with tamoxifen inhibit of ER+ breast cancer growth in vivo. (A) The tumor growth of SSM2 syngeneic model treated with C–H or/and TAM. (B) The tumor weight of xenograft tumors at the end of experiment. (C) Photographs of the tumors. (D) The body weights of mice in all groups were measured every two days. *p < 0.05, **p < 0.01, ***p < 0.001.

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References

    1. Sung H., Ferlay J., Siegel R.L., Laversanne M., Soerjomataram I., Jemal A., Bray F. Global Cancer Statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA A Cancer J. Clin. 2021;71:209–249. doi: 10.3322/caac.21660. - DOI - PubMed
    1. Siersbæk R., Kumar S., Carroll J.S. Signaling pathways and steroid receptors modulating estrogen receptor α function in breast cancer. Genes Dev. 2018;32:1141–1154. doi: 10.1101/GAD.316646.118. - DOI - PMC - PubMed
    1. Saha T., Makar S., Swetha R., Gutti G., Singh S.K. Estrogen signaling: an emanating therapeutic target for breast cancer treatment. Eur. J. Med. Chem. 2019;177:116–143. doi: 10.1016/J.EJMECH.2019.05.023. - DOI - PubMed
    1. Group E.B.C.T.C. Relevance of breast cancer hormone receptors and other factors to the efficacy of adjuvant tamoxifen: patient-level meta-analysis of randomised trials. Lancet. 2011;378:771–784. doi: 10.1016/S0140-6736(11)60993-8. - DOI - PMC - PubMed
    1. Hanker A.B., Sudhan D.R., Arteaga C.L. Overcoming endocrine resistance in breast cancer. Cancer Cell. 2020;37:496–513. doi: 10.1016/J.CCELL.2020.03.009. - DOI - PMC - PubMed

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