A novel histone deacetylase inhibitor exerts promising anti-breast cancer activity via triggering AIFM1-dependent programmed necrosis

Discovery of a novel hybrid coumarin-hydroxamate conjugate targeting the HDAC1-Sp1-FOSL2 signaling axis for breast cancer therapy

BACKGROUND

Breast cancer is one of the most lethal cancers in women. Despite significant advances in the diagnosis and treatment of breast cancer, many patients still succumb to this disease, and thus, novel effective treatments are urgently needed. Natural product coumarin has been broadly investigated since it reveals various biological properties in the medicinal field. Accumulating evidence indicates that histone deacetylase inhibitors (HDACIs) are promising novel anti-breast cancer agents. However, most current HDACIs exhibit only moderate effects against solid tumors and are associated with severe side effects. Thus, to develop more effective HDACIs for breast cancer therapy, hydroxamate of HDACIs was linked to coumarin core, and coumarin-hydroxamate hybrids were designed and synthesized.

METHODS

A substituted coumarin moiety was incorporated into the classic hydroxamate HDACIs by the pharmacophore fusion strategy. ZN444B was identified by using the HDACI screening kit and cell viability assay. Molecular docking was performed to explore the binding mode of ZN444B with HDAC1. Western blot, immunofluorescent staining, cell viability, colony formation and cell migration and flow cytometry assays were used to analyze the anti-breast cancer effects of ZN444B in vitro. Orthotopic studies in mouse models were applied for preclinical evaluation of efficacy and toxicity in vivo. Proteomic analysis, dual-luciferase reporter assay, chromatin immunoprecipitation, co-immunoprecipitation, immunofluorescent staining assays along with immunohistochemical (IHC) analysis were used to elucidate the molecular basis of the actions of ZN444B.

RESULTS

We synthesized and identified a novel coumarin-hydroxamate conjugate, ZN444B which possesses promising anti-breast cancer activity both in vitro and in vivo. A molecular docking model showed that ZN444B binds to HDAC1 with high affinity. Further mechanistic studies revealed that ZN444B specifically decreases FOS-like antigen 2 (FOSL2) mRNA levels by inhibiting the deacetylase activity of HDAC1 on Sp1 at K703 and abrogates the binding ability of Sp1 to the FOSL2 promoter. Furthermore, FOSL2 expression positively correlates with breast cancer progression and metastasis. Silencing FOSL2 expression decreases the sensitivity of breast cancer cells to ZN444B treatment. In addition, ZN444B shows no systemic toxicity in mice.

CONCLUSIONS

Our findings highlight the potential of FOSL2 as a new biomarker and therapeutic target for breast cancer and that targeting the HDAC1-Sp1-FOSL2 signaling axis with ZN444B may be a promising therapeutic strategy for breast cancer.

First total synthesis, antitumor evaluation and target identification of mornaphthoate E: A new tubulin inhibitor template acting on PI3K/Akt signaling pathway

Mornaphthoate E (MPE) is a prenylated naphthoic acid methyl ester isolated from the roots of a famous Chinese medicinal plant Morinda officinalis and shows remarkable cytotoxicity against several human tumor cell lines. In the current project, the first total synthesis of (±)-MPE was achieved in seven steps and 5.6% overall yield. Then the in vitro anti-tumor activity of MPE was first assessed for both enantiomers in two breast cancer cells, with the levoisomer exerting slightly better potency. The in vivo anti-tumor effect was further verified by applying the racemate in an orthotopic autograft mouse model. Notably, MPE exerted promising anti-metastasis activity both in vitro and in vivo and showed no obvious toxicity on mice at the therapeutic dosage. Mechanistic investigations demonstrated that MPE acted as a tubulin polymerization stabilizer and disturbed the dynamic equilibrium of microtubules via regulating PI3K/Akt signaling. In conclusion, our work has provided a new chemical template for the future design and development of next-generation tubulin-targeting chemotherapies.

Rare flavanone-diarylheptanoid hybrids from Typha angustifolia shows anti breast cancer activity via activating TGF-β1/Smad signaling pathway

Four new flavanone-diarylheptanoid hetero dimers, typhatifolins A-D (1-4), were separated from the pollen of a widely distributed medicinal plant Typha angustifolia. Structures of these rare hybrids were elucidated by detailed interpretation of spectroscopic data, and their absolute configurations were determined on the basis of Mosher's method and ECD analyses. All the four compounds showed moderate to significant cytotoxicities against a panel of tumor cell lines with IC50 values ranging from 0.67 to 12.48 μM. Further in vitro antitumor evaluation for typhatifolin B (TTB, 2) on two breast cancer cells (4T1 and MDA-MB231) revealed that it could remarkably induce cell apoptosis and G0/G1 cycle arrest, as well as block cell migration and invasion. Mechanistically, TTB could exert its antitumor effect via activating the TGF-β1 (transforming growth factor beta 1) signaling pathway as evidenced by RNA-seq analysis and immunoblotting experiments, which was further corroborated by treating cancer cells with a TGF-β signaling inhibitor. Lastly, the in vivo anti breast cancer activity was demonstrated by applying the mixture of typhatifolins A-D to a preclinical animal model.

Natural diterpenoid EKO activates deubiqutinase ATXN3 to preserve vascular endothelial integrity and alleviate diabetic retinopathy through c-fos/focal adhesion axis

Diabetic retinopathy (DR) is one of the most prevalent severe diabetic microvascular complications caused by hyperglycemia. Deciphering the underlying mechanism of vascular injury and finding ways to alleviate hyperglycemia induced microvascular complications is of great necessity. In this study, we identified that a compound ent-9α-hydroxy-15-oxo-16-kauren-19-oic acid (EKO), the diterpenoid isolated and purified from Pteris semipinnata L., exhibited good protective roles against vascular endothelial injury associated with diabetic retinopathy in vitro and in vivo. To further uncover the underlying mechanism, we used unbiased transcriptome sequencing analysis and showed substantial impairment in the focal adhesion pathway upon high glucose and IL-1β stimulation. EKO could effectively improve endothelial focal adhesion pathway by enhancing the expression of two focal adhesion proteins Vinculin and ITGA11. We found that c-fos protein was involved in regulating the expression of Vinculin and ITGA11, a transcription factor component that was downregulated by high glucose and IL-1β stimulation and recovered by EKO. Mechanically, EKO facilitated the binding of deubiquitylation enzyme ATXN3 to c-fos protein and promoted its deubiquitylation, thereby elevating its protein level to enhance the expression of Vinculin and ITGA11. Besides, EKO effectively suppressed ROS production and restored mitochondrial function. In vivo studies, we confirmed EKO could alleviate some of the indicators of diabetic mice. In addition, protein levels of ATXN3 and focal adhesion Vinculin molecule were also verified in vivo. Collectively, our findings addressed the endothelial protective role of natural diterpenoid EKO, with emphasize of mechanism on ATXN3/c-fos/focal adhesion signaling pathway as well as oxygen stress suppression, implicating its therapeutic potential in alleviating vascular endothelium injury and diabetic retinopathy.

The One-Stop Integrated Nanoagent Based on Photothermal Therapy for Deep Infection Healing and Inflammation Inhibition

Chronic wounds caused by bacterial infections are a major challenge in medical fields. The hypoxia condition extremely induces reactive oxygen species (ROS) generation and upregulates the expression of hypoxia-inducible factor, both of which can increase the pro-inflammatory M1 subtype macrophages production while reducing the anti-inflammatory M2 subtype macrophages. Besides, bacteria-formed biofilms can hinder the penetration of therapeutic agents. Encouraged by natural motors automatically executing tasks, hypothesized that supplying sufficient oxygen (O2 ) would simultaneously drive therapeutic agent movement, rescue the hypoxic microenvironment, and disrupt the vicious cycle of inflammation. Here, small organic molecule-based nanoparticles (2TT-mC6B@Cu5.4 O NPs) that possess high photothermal conversion efficiency and enzymatic activities are developed, including superoxide dismutase-, catalase-, and glutathione peroxidase-like activity. 2TT-mC6B@Cu5.4 O NPs exhibit superior ROS-scavenging and O2 production abilities that synergistically relieve inflammation, alleviate hypoxia conditions, and promote their deep penetration in chronic wound tissues. Transcriptome analysis further demonstrates that 2TT-mC6B@Cu5.4O NPs inhibit biological activities inside bacteria. Furthermore, in vivo experiments prove that 2TT-mC6B@Cu5.4 O NPs-based hyperthermia can effectively eliminate bacteria in biofilms to promote wound healing.