Design and synthesis of novel Flavone-based histone deacetylase inhibitors antagonizing activation of STAT3 in breast cancer

doi:10.1016/j.ejmech.2020.112677

European Journal of Medicinal Chemistry

Volume 206, 15 November 2020, 112677

https://doi.org/10.1016/j.ejmech.2020.112677 Get rights and content

Highlights

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Compound 15a is a class of novel HDAC inhibitors based on the structure of flavones and isoflavones.
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Compound 15a can inhibit HDACs and STAT3 signaling pathway both in vitro and in vivo.
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Remarkably inhibit the growth of breast cancers in vivo, which are resistant to regular HDAC inhibitors.

Abstract

Histone deacetylases (HDACs) inhibitors have demonstrated a great clinical achievement in hematological malignancies. However, the efficacy of HDACs inhibitors in treating solid tumors remains limited due to the complicated tumor microenvironment. In this study, we designed and synthesized a class of novel HDACs inhibitors based on the structure of flavones and isoflavones, followed by biological evaluation. To be specific, a lead compound 15a was discovered with strong anti-proliferative effects on a variety of solid tumor cells, especially for breast cancer cells with resistance to SAHA. Studies demonstrated that 15a could significantly inhibit the activity of HDAC 1, 2, 3 (class I) and 6 (class IIB), leading to a dose-dependent accumulation of acetylated histones and α-Tubulin, cell cycle arrest (G1/S phase) and apoptosis in breast cancer cells. Furthermore, the lead compound 15a could also antagonize the activation of STAT3 induced by HDACs inhibition in some breast cancer cells, which further reduced the level of pro-survive proteins in tumor cells and enhanced anti-tumor activity regulated by STAT3 signaling in vivo. Overall, our findings demonstrated that the novel compound 15a might be a HDACs inhibitor candidate, which could be used as promising chemotherapeutic agent for breast cancer.

Graphical abstract

Introduction

As a family of epigenetic enzymes, histone deacetylases (HDACs) can remove acetyl groups from lysine on histones and non-histone proteins, playing an essential role on controlling the transcription of genes and protein stability, which are involved in cell cycle progression, cell differentiation, cell apoptosis, angiogenesis and immune-regulation [[1], [2], [3], [4], [5]]. Functional dysregulations of HDACs have been regarded as a key trigger of various human cancers, thus representing a promising antitumor drug target [6]. Moreover, part of histone deacetylases (HDACs) inhibitors approved by the US Food and Drug Administration (FDA) have brought great clinical benefits in certain types of hematological malignancies, such as T-cell lymphoma and multiple myeloma [7]. However, the efficacy of HDACs inhibitors (such as SAHA) in treating solid tumors remains limited due to diverse resistance mechanisms [[8], [9], [10], [11]].

Activation of the signal transducer and activator of transcription (STAT) pathway has been linked to SAHA resistance in lymphoma [12]. The latest study also elucidated SAHA could upregulate the expression of leukemia inhibitory factor receptor (LIFR) through epigenetic modification of its promoter, leading to the activation of IL-6-LIFR-JAK-STAT3 pathway. It subsequently reduced the response of some breast cancer cells to chemotherapeutics, including HDACs inhibitors themselves [8]. To figure out the reason, firstly, activation of STAT3 promotes the growth of tumor cells by regulating key target genes involved in modulating cellular proliferation and metabolism, suppressing apoptosis, and responding to hypoxia [13]. Furthermore, immunosuppressive factors mediated by STAT3 activation in the tumor microenvironment (such as IL-6, IL-10, TGF-β, and VEGF) stimulates positive-feedback amplification of STAT3 activation in both tumor cells and tumor-infiltrating immune cells [[14], [15], [16], [17], [18]]. It could result in complex crosstalk between cancer cells and immune cells. This process could increase growth and survival of tumor cell, and diminish anti-tumor immunity. Collectively, upregulation of STAT3 induced by treatment of HDACs inhibitors is observed as an inevitable hindrance for the clinical application of HDACs inhibitors in some solid tumors. Therefore, as a possible solution, combinations between HDACs inhibition and antagonism of the oncogenic signaling pathways upstream of STAT3 might provide a promising and novel approach for chemotherapy of some solid malignancies.

Clinically, drug cocktails have been widely used in cancer therapy. However, drug combinations are usually accompanied by complicated dose or schedule designs and might also cause safety problem due to the complexity of metabolism. Alternatively, the development of bifunctional with dual antagonist of STAT3 signaling and HDACs activity seems more feasible. To this end, it is considered as a good option by seeking and developing anti-cancer drug molecules from natural origins. The flavones and isoflavones are a class of promising anti-cancer natural products, which could block oncogenic signaling pathways upstream of STAT3 through different mechanisms in various cancer cells [[19], [20], [21], [22], [23], [24], [25]]. Based on the structure of flavones, there have been multiple studies concerning the structural modification and improvement of their anti-tumor activities [[26], [27], [28], [29], [30], [31], [32]]. Herein, based on the structure of flavones, novel HDACs inhibitors which also antagonize STAT3 activation are designed, synthesized and biologically screened. A lead compound has been identified, showing excellent potency in combinational treatment of various types of solid tumors cells, especially for triple-negative breast cancer subset in vivo.

Section snippets

Chemistry

Based on the structure of flavones and designed according to molecular hybrid principle, a series of novel a series of novel STAT3 pathway-HDACs dual inhibitors were prepared according to synergistic effect between the two targets (Scheme 1). HDACs inhibitors (such as vorinostat) generally consisted of a hydrophobic capping group, a hydrophobic linker and a zinc-binding group (hydroxamic acid or benzamide). The general idea was that capping group was flexible, which could, thus, be replaced by

Conclusions

In this study, 28 potential HDACs inhibitors were designed and synthesized based on the structure of flavones and isoflavones. Among them, one lead compound 15a was discovered and biologically evaluated, which could significantly suppress breast cancer subset growth both in vitro and in vivo. Overall, compound 15a selectively inhibited the activity of HDAC1, HDAC2, HDAC3 (class I) and HDAC6 (class IIB) and induced cell cycle arrest and apoptosis of breast cancer cells. Of note, 15a antagonized

Notes

The authors declare no competing financial interest.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by The National Key Research and Development Program of China (No. 2018YFA0507203), the Fundamental Research Funds for the Central Universities, Nankai University (NO. 735-63201235), the National Natural Science Foundation of China (NSFC, No. 81703343 and 81503019), National Science & Technology Major Project “Key New Drug Creation and Manufacturing Program”, China (No. 2019ZX09201001), Key Research and Development Program of Tianjin City (No. 19YFZCSY00160), Key

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Citation Excerpt :
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¹: These authors contributed equally to this work.

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Research paperDesign and synthesis of novel Flavone-based histone deacetylase inhibitors antagonizing activation of STAT3 in breast cancer

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Chemistry

Conclusions

Notes

Declaration of competing interest

Acknowledgments

Canc. Lett.

Canc. Cell

Canc. Lett.

Canc. Lett.

Canc. Lett.

Eur. J. Med. Chem.

Eur. J. Med. Chem.

Eur. J. Med. Chem.

Eur. J. Med. Chem.

Eur. J. Med. Chem.

Physical and functional HAT/HDAC interplay regulates protein acetylation balance

J. Biomed. Biotechnol.

New and emerging HDAC inhibitors for cancer treatment

J. Clin. Invest.

Hdac inhibitors in cancer biology: emerging mechanisms and clinical applications

Immunol. Cell Biol.

Histone deacetylases and their inhibitors in cancer, neurological diseases and immune disorders

Drug Discovery

Epigenetics: novel therapeutics targeting epigenetics

J. Med. Chem.

Targeting histone deacetylases in T-cell lymphoma

Leuk. Lymphoma

Research paper
Design and synthesis of novel Flavone-based histone deacetylase inhibitors antagonizing activation of STAT3 in breast cancer