Phase separation of Nur77 mediates XS561-induced apoptosis by promoting the formation of Nur77/Bcl-2 condensates.

The orphan nuclear receptor Nur77 is a critical regulator of the survival and death of tumor cells. The pro-death effect of Nur77 can be regulated by its interaction with Bcl-2, resulting in conversion of Bcl-2 from a survival to killer. As Bcl-2 is overexpressed in various cancers preventing them from apoptosis and promoting their resistance to chemotherapy, targeting the apoptotic pathway of Nur77/Bcl-2 may lead to new cancer therapeutics. Here, we report our identification of XS561 as a novel Nur77 ligand that induces apoptosis of tumor cells by activating the Nur77/Bcl-2 pathway. In vitro and animal studies revealed an apoptotic effect of XS561 in a range of tumor cell lines including MDA-MB-231 triple-negative breast cancer (TNBC) and MCF-7/LCC2 tamoxifen-resistant breast cancer (TAMR) in a Nur77-dependent manner. Mechanistic studies showed XS561 potently induced the translocation of Nur77 from the nucleus to mitochondria, resulting in mitochondria-related apoptosis. Interestingly, XS561-induced accumulation of Nur77 at mitochondria was associated with XS561 induction of Nur77 phase separation and the formation of Nur77/Bcl-2 condensates. Together, our studies identify XS561 as a new activator of the Nur77/Bcl-2 apoptotic pathway and reveal a role of phase separation in mediating the apoptotic effect of Nur77 at mitochondria.

Mitochondria-Targeted Prodrug Nanoassemblies for Efficient Ferroptosis-Based Therapy via Devastating Ferroptosis Defense Systems.

Ferroptosis is a form of regulated cell death accompanied by lipid reactive oxygen species (ROS) accumulation in an iron-dependent manner. However, the efficiency of tumorous ferroptosis was seriously restricted by intracellular ferroptosis defense systems, the glutathione peroxidase 4 (GPX4) system, and the ubiquinol (CoQH2) system. Inspired by the crucial role of mitochondria in the ferroptosis process, we reported a prodrug nanoassembly capable of unleashing potent mitochondrial lipid peroxidation and ferroptotic cell death. Dihydroorotate dehydrogenase (DHODH) inhibitor (QA) was combined with triphenylphosphonium moiety through a disulfide-containing linker to engineer well-defined nanoassemblies (QSSP) within a single-molecular framework. After being trapped in cancer cells, the acidic condition provoked the structural disassembly of QSSP to liberate free prodrug molecules. The mitochondrial membrane-potential-driven accumulation of the lipophilic cation prodrug was delivered explicitly into the mitochondria. Afterward, the thiol-disulfide exchange would occur accompanied by downregulation of reduced glutathione levels, thus resulting in mitochondria-localized GPX4 inactivation for ferroptosis. Simultaneously, the released QA from the hydrolysis reaction of the adjacent ester bond could further devastate mitochondrial defense and evoke robust ferroptosis via the DHODH-CoQH2 system. This subcellular targeted nanoassembly provides a reference for designing ferroptosis-based strategy for efficient cancer therapy through interfering antiferroptosis systems.

Discovery of 5-(Pyrimidin-2-ylamino)-1H-indole-2-carboxamide Derivatives as Nur77 Modulators with Selective and Potent Activity Against Triple-Negative Breast Cancer.

The orphan nuclear receptor Nur77 has been validated as a potential drug target for treating breast cancer. Therefore, focusing on the SAR study of the lead 8b (KDSPR(Nur77) = 354 nM), we found the active compound ja which exhibited improved Nur77-binding capability (KDSPR(Nur77) = 91 nM) and excellent antiproliferative activities against breast cancer cell lines. Interestingly, ja acted as a potent and selective Nur77 antagonist, displaying good potency against triple-negative breast cancer (TNBC) cell lines but did not inhibit human normal breast cancer cell line MCF-10A (SI > 20). Exceptionally, ja Nur77-dependently caused mitochondria dysfunction and induced the caspase-dependent apoptosis by mediating the TP53 phosphorylation pathway. Moreover, ja significantly suppressed MDA-MB-231 xenograft tumor growth but had no apparent side effects in mice and zebrafish. Overall, ja demonstrated to be the first Nur77 modulator mediating the TP53 phosphorylation pathway that has the potential as a novel anticancer agent for TNBC.

The novel CDK9 inhibitor, XPW1, alone and in combination with BRD4 inhibitor JQ1, for the treatment of clear cell renal cell carcinoma.

BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is a highly lethal malignancy with few therapeutic options. Cyclin­dependent kinase 9 (CDK9), a potential therapeutic target of many cancers, has been recently observed to be upregulated in ccRCC patients. Therefore, we aimed to investigate the therapeutic potential of CDK9 in ccRCC and develop a novel CDK9 inhibitor with low toxicity for ccRCC treatment. METHODS: The expression of CDK9 in ccRCC was checked using the online database and tissue microarray analysis. shRNA-mediated CDK9 knockdown and CDK inhibitor were applied to evaluate the effect of CDK9 on ccRCC. Medicinal chemistry methods were used to develop a new CDK9 inhibitor with drugability. RNA-seq and ChIP-seq experiments were conducted to explore the mechanism of action. MTS, western blotting, and colony formation assays were performed to evaluate the anti-ccRCC effects of CDK9 knockdown and inhibition in vitro. The in vivo anti-tumour efficacy was evaluated in a xenograft model. RESULTS: CDK9 is overexpressed and associated with poor survival in ccRCC. Knockdown or inhibition of CDK9 significantly suppressed ccRCC cells. XPW1 was identified as a new potent and selective CDK9 inhibitor with excellent anti-ccRCC activity and low toxicity. In mechanism, XPW1 transcriptionally inhibited DNA repair programmes in ccRCC cells, resulting in an excellent anti-tumour effect. CDK9 and BRD4 were two highly correlated transcriptional regulators in ccRCC patients, and the BRD4 inhibitor JQ1 enhanced XPW1's anti-ccRCC effects in vitro and in vivo. CONCLUSIONS: This work provides valuable insights into the therapeutic potential of CDK9 in ccRCC. The CDK9 inhibitor XPW1 would be a novel therapeutic agent for targeting ccRCC, alone or in rational combinations.

Discovery of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-indole-2-carboxamide derivatives as novel anti-cancer agents targeting Nur77.

Encouraged by our previous findings and in continuation of our ongoing study project in designing and synthesis of novel Nur77-targeting anti-cancer agents, a series of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-indole-2-carboxamide derivatives were designed, synthesized and biologically evaluated as potent Nur77 modulators. Among synthesized compounds, 8b maintained good potency against different liver cancer cell lines and other types of cancer cell lines while exhibiting lower toxicity than the positive compound celastrol. Moreover, 8b displayed excellent Nur77-binding activity, superior to the lead compound 10g and comparable to the reference compound celastrol. The cytotoxic action of 8b towards cancer cells was associated with its induction of Nur77-mitochondrial targeting and Nur77-dependent apoptosis. Notably, 8b has good in vivo safety and anti-hepatocellular carcinoma (HCC) activity. Altogether, this study reveals that 8b is a novel Nur77 modulator with great promise for further research.

MicroRNA-506 ameliorates breast cancer-induced osteolytic bone metastasis via the NFATc-1 signaling pathway.

Breast cancer is becoming a common life-threatening disease, especially in women, along with higher incidence and mortality. MicroRNA (miR)-506 was reported to participate in breast cancer progression, while the role of miR-506 in breast cancer-induced osteolytic bone metastasis is unclear. In the present study, we found significant downregulation of miR-506 in breast cancer tissues and cell lines. Overexpression of miR-506 notably reduced the proliferative, migratory and invasive rates of MCF7 and MDA-MB-231 cells, and reduced the production of inflammatory factors IL-6 and TNF-α in MCF7 cells. Moreover, overexpression of miR-506 obviously inhibited tumor growth in an in vivo animal model. In addition, overexpression of miR-560 efficiently attenuated breast cancer-induced osteolysis in vivo, which was characterized by increased bone volume/total volume (BT/TV), trabecular number (Tb. N), and trabecular thickness (Tb. Th), as well as the reduced trabecular separation (Tb. Sp). The nuclear factor of activated T cell cytoplasmic 1 (NFATc1) was identified as a downstream target of miR-506, and overexpression of miR-506 could inhibit breast cancer progression by targeting NFATc1. Furthermore, our results showed that NFATc-1 might participate in the inhibition of miR-506 on breast cancer-induced osteolysis. In conclusion, our findings provide insights into understanding the pathogenesis of breast cancer and breast cancer-induced osteolytic bone metastasis, and miR-506 might serve as a novel biomarker for this disease.

Design, synthesis, and biological evaluation of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-Indole-2-Carbohydrazide derivatives: the methuosis inducer 12A as a Novel and selective anticancer agent.

This study describes the synthesis and vacuole-inducing activity of 5-((4-(pyridin-3-yl)pyrimidin-2-yl)amino)-1H-indole-2-carbohydrazide derivatives, including five potent derivatives 12c, 12 g, 12i, 12n, and 12A that exhibit excellent vacuole-inducing activity. Remarkably, 12A effectively induces methuosis in tested cancer cells but not human normal cells. In addition, 12A exhibits high pan-cytotoxicity against different cancer cell lines but is hardly toxic to normal cells. It is found that the 12A-induced vacuoles are derived from macropinosomes but not autophagosomes. The 12A-induced cytoplasmic vacuoles may originate from the endoplasmic reticulum (ER) and be accompanied by ER stress. The MAPK/JNK signalling pathway is involved in the 12A-induced methuotic cell death. Moreover, 12A exhibits significant inhibition of tumour growth in the MDA-MB-231 xenograft mouse model. The excellent potency and selectivity of 12A prompt us to select it as a good lead compound for further development of methuosis inducers and investigation of the molecular and cellular mechanisms underlying methuosis.

Recent progress in mitochondria-targeting-based nanotechnology for cancer treatment.

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Nanosystems for targeted delivery of cargos to mitochondria for cancer treatment have attracted increasing attention in the past few years. This review will summarize the state of the art of design and construction of nanosystems used for mitochondria-targeted delivery. The use of nanotechnology for cancer treatment through various pathways such as energy metabolism interference, reactive oxygen species (ROS) regulation, mitochondrial protein targeting, mitochondrial DNA (mtDNA) interference, mitophagy inducing, and combination therapy will be discussed. Finally, the major challenges and an outlook in this field will also be provided.

Synthesis and biological evaluation of (3/4-(pyrimidin-2-ylamino)benzoyl)-based hydrazine-1-carboxamide/carbothioamide derivatives as novel RXRα antagonists.

Abnormal alterations in the expression and biological function of retinoid X receptor alpha (RXRα) have a key role in the development of cancer. Potential modulators of RXRα as anticancer agents are explored in growing numbers of studies. A series of (4/3-(pyrimidin-2-ylamino)benzoyl)hydrazine-1-carboxamide/carbothioamide derivatives are synthesised and evaluated for anticancer activity as RXRα antagonists in this study. Among all synthesised compounds, 6A shows strong antagonist activity (half maximal effective concentration (EC50) = 1.68 ± 0.22 µM), potent anti-proliferative activity against human cancer cell lines HepG2 and A549 cells (50% inhibition of cell viability (IC50) values < 10 µM), and low cytotoxic property in normal cells such as LO2 and MRC-5 cells (IC50 values > 100 µM). Further bioassays indicate that 6A inhibits 9-cis-RA-induced activity in a dose-dependent manner, and selectively binds to RXRα-=LΒD with submicromolar affinity (Kd = 1.20 × 10-7 M). 6A induces time-and dose-dependent cleavage of poly ADP-ribose polymerase, and significantly stimulates caspase-3 activity, leading to RXRα-dependent apoptosis. Finally, molecular docking studies predict the binding modes for RXRα-LBD and 6A.