PI3K PROTAC overcomes the lapatinib resistance in PIK3CA-mutant HER2 positive breast cancer.

Although anti-HER2 therapy has made significant strides in reducing metastasis and relapse in HER2-positive breast cancer, resistance to agents like trastuzumab, pertuzumab, and lapatinib frequently develops in patients undergoing treatment. Previous studies suggest that the hyperactivation of the PI3K-AKT signaling pathway by PIK3CA/PTEN gene mutations is implicated in HER2 resistance. In this study, we introduce a novel PI3K-p110α Proteolysis TAargeting Chimera (PROTAC) that effectively inhibits the proliferation of breast cancer cells by degrading PI3K-p110α. When tested in two lapatinib-resistant cell lines, JIMT1 and MDA-MB-453, both of which harbor PIK3CA mutations, the PI3K PROTAC notably reduced cell proliferation and induced G1 phase cell cycle arrest. Importantly, even at very low concentrations, PI3K PROTAC restored sensitivity to lapatinib. Furthermore, the efficacy of PI3K PROTAC surpassed that of Alpelisib, a selective PI3K-p110α kinase inhibitor in clinic. The superior performance of PI3K PROTAC was also confirmed in lapatinib-resistant breast cancer xenograft tumors and patient-derived breast cancer organoids (PDOs). In conclusion, this study reveals that the novel PI3K PROTAC we synthesized could serve as an effective agent to overcome lapatinib resistance.

CDK9 targeting PROTAC L055 inhibits ERα-positive breast cancer.

Breast cancer is one of the most prevalent malignancies affecting women worldwide, underscoring the urgent need for more effective and specific treatments. Proteolysis-targeting chimeras (PROTACs) have emerged as a promising strategy to develop new lead compounds by selectively targeting oncoproteins for degradation. In this study, we designed, synthesized and evaluated a CRBN-based PROTAC, L055, which targets CDK9. Our findings demonstrate that L055 effectively inhibits the proliferation, induces cell cycle arrest, and decreases the survival of ERα-positive breast cancer cells in vitro. L055 specifically binds to CDK9, facilitating its degradation via the CRBN-dependent proteasomal pathway. Additionally, L055 suppressed the growth of organoids and tumors derived from T47D and MCF7 cells in nude mice. Thus, L055 represents a potential novel therapeutic agent for ERα-positive breast cancer and potentially other malignancies.

Integrin ß4 promotes DNA damage-related drug resistance in triple-negative breast cancer via TNFAIP2/IQGAP1/RAC1.

Anti-tumor drug resistance is a challenge for human triple-negative breast cancer (TNBC) treatment. Our previous work demonstrated that TNFAIP2 activates RAC1 to promote TNBC cell proliferation and migration. However, the mechanism by which TNFAIP2 activates RAC1 is unknown. In this study, we found that TNFAIP2 interacts with IQGAP1 and Integrin ß4. Integrin ß4 activates RAC1 through TNFAIP2 and IQGAP1 and confers DNA damage-related drug resistance in TNBC. These results indicate that the Integrin ß4/TNFAIP2/IQGAP1/RAC1 axis provides potential therapeutic targets to overcome DNA damage-related drug resistance in TNBC.

Angiopoietin-1 promotes triple-negative breast cancer cell proliferation by upregulating carboxypeptidase A4.

Angiopoietin-1 (ANG1) is a pro-angiogenic regulator that contributes to the progression of solid tumors by stimulating the proliferation, migration and tube formation of vascular endothelial cells, as well as the renewal and stability of blood vessels. However, the functions and mechanisms of ANG1 in triple-negative breast cancer (TNBC) are unclear. The clinical sample database shows that a higher level of ANG1 in TNBC is associated with poor prognosis compared to non-TNBC. In addition, knockdown of ANG1 inhibits TNBC cell proliferation and induces cell cycle G1 phase arrest and apoptosis. Overexpression of ANG1 promotes tumor growth in nude mice. Mechanistically, ANG1 promotes TNBC by upregulating carboxypeptidase A4 (CPA4) expression. Overall, the ANG1-CPA4 axis can be a therapeutic target for TNBC.

Targeting HECTD3-IKKα axis inhibits inflammation-related metastasis.

Metastasis is the leading cause of cancer-related death. The interactions between circulating tumor cells and endothelial adhesion molecules in distant organs is a key step during extravasation in hematogenous metastasis. Surgery is a common intervention for most primary solid tumors. However, surgical trauma-related systemic inflammation facilitates distant tumor metastasis by increasing the spread and adhesion of tumor cells to vascular endothelial cells (ECs). Currently, there are no effective interventions to prevent distant metastasis. Here, we show that HECTD3 deficiency in ECs significantly reduces tumor metastasis in multiple mouse models. HECTD3 depletion downregulates expression of adhesion molecules, such as VCAM-1, ICAM-1 and E-selectin, in mouse primary ECs and HUVECs stimulated by inflammatory factors and inhibits adhesion of tumor cells to ECs both in vitro and in vivo. We demonstrate that HECTD3 promotes stabilization, nuclear localization and kinase activity of IKKα by ubiquitinating IKKα with K27- and K63-linked polyubiquitin chains at K296, increasing phosphorylation of histone H3 to promote NF-κB target gene transcription. Knockout of HECTD3 in endothelium significantly inhibits tumor cells lung colonization, while conditional knockin promotes that. IKKα kinase inhibitors prevented LPS-induced pulmonary metastasis. These findings reveal the promotional role of the HECTD3-IKKα axis in tumor hematogenous metastasis and provide a potential strategy for tumor metastasis prevention.

Histone Deacetylase Inhibitors (HDACi) Promote KLF5 Ubiquitination and Degradation in Basal-like Breast Cancer.

Basal-like breast cancer (BLBC) accounts for approximately 15% of all breast cancer cases, and patients with BLBC have a low survival rate. Our previous study demonstrated that the KLF5 transcription factor promotes BLBC cell proliferation and tumor growth. In this study, we demonstrated that the histone deacetylase inhibitors (HDACi), suberoylanilide hydroxamic acid (SAHA), and trichostatin A (TSA), increased KLF5 acetylation at lysine 369 (K369), downregulated KLF5 protein expression levels, and decreased cell viability in BLBC cell lines. HDACi target KLF5 for proteasomal degradation by promoting KLF5 protein ubiquitination. K369 acetylation of KLF5 decreases the binding between KLF5 and its deubiquitinase, BAP1. These findings revealed a novel mechanism by which HDACi suppress BLBC, and a novel crosstalk between KLF5 protein acetylation and ubiquitination.

Mifepristone Derivative FZU-00,003 Suppresses Triple-negative Breast Cancer Cell Growth partially via miR-153-KLF5 axis.

Triple-negative breast cancer (TNBC) is one of the most malignant breast cancers lacking targeted therapeutics currently. We recently reported that mifepristone (MIF), a drug regularly used for abortion, suppresses TNBC cell growth by inhibiting KLF5 expression via inducing miR-153. However, its anticancer efficacy is only modest at high dose. In order to enhance the anticancer activities, a focused compound library containing 17 compounds by altering the sensitive metabolic region of mifepristone has been designed and synthesized. We first tested the cell growth inhibitory effects of these compounds in TNBC cell lines. Among them, FZU-00,003 displayed the most potent efficiency. FZU-00,003 suppresses TNBC cell growth, cell cycle progression and induces apoptosis more effectively than MIF does. Consistently, FZU-00,003 induces miR-153 expression and suppressed KLF5 expression at much lower dosages than MIF does. Furthermore, FZU-00,003 inhibits tumor growth more potently than MIF does. Taken together, the MIF derivative, FZU-00,003 may serve as a better therapeutic compound for TNBC than MIF.

miR-153 inhibits the migration and the tube formation of endothelial cells by blocking the paracrine of angiopoietin 1 in breast cancer cells.

The sprouting of endothelial cells is the first step of tumor angiogenesis. Our previous study suggests that miR-153 suppresses breast tumor angiogenesis partially through targeting hypoxia-induced factor (HIF1α). In this study, we demonstrated that miR-153 also suppresses the migration and the tube formation of endothelial cells through directly targeting angiopoietin 1 (ANG1) in breast cancer cells. There was a negative correlation between miR-153 and ANG1 levels in breast cancer. miR-153 blocked the expression and secretion of ANG1 in breast cancer cells through binding to ANG1 mRNA. Conditioned medium from the breast cancer cell, MCF7, treated with miR-153 had no effect on the proliferation of HUVECs, but significantly inhibited the migration and tube formation of HUVECs, which could be rescued by overexpression of ANG1. In addition, miR-153 also directly inhibited the proliferation and migration of MCF7 through downregulation of ANG1. These findings suggest that miR-153 suppresses the activity of tumor cells and the migration and tube formation of endothelial cells by silencing ANG1.

HECTD3 mediates TRAF3 polyubiquitination and type I interferon induction during bacterial infection.

Lysine-63-linked (K63-linked) polyubiquitination of TRAF3 coordinates the engagement of pattern-recognition receptors with recruited adaptor proteins and downstream activator TBK1 in pathways that induce type I IFN. Whether autoubiquitination or other E3 ligases mediate K63-linked TRAF3 polyubiquitination remains unclear. We demonstrated that mice deficient in the E3 ligase gene Hectd3 remarkably increased host defense against infection by intracellular bacteria Francisella novicida, Mycobacterium, and Listeria by limiting bacterial dissemination. In the absence of HECTD3, type I IFN response was impaired during bacterial infection both in vivo and in vitro. HECTD3 regulated type I IFN production by mediating K63-linked polyubiquitination of TRAF3 at residue K138. The catalytic domain of HECTD3 regulated TRAF3 K63 polyubiquitination, which enabled TRAF3-TBK1 complex formation. Our study offers insights into mechanisms of TRAF3 modulation and provides potential therapeutic targets against infections by intracellular bacteria and inflammatory diseases.

Hypoxia induces miR-153 through the IRE1α-XBP1 pathway to fine tune the HIF1α/VEGFA axis in breast cancer angiogenesis.

It is well documented that hypoxia activates the hypoxia-inducible factor 1-alpha (HIF1α)/vascular endothelial growth factor A (VEGFA) axis to promote angiogenesis in breast cancer. However, it is unclear how this axis is negatively regulated. In this study, we demonstrated that miR-153 directly inhibits expression of HIF1α by binding to the 3'UTR of HIF1A mRNA, as well as suppresses tube formation of primary human umbilical vein endothelial cells (HUVECs) and breast cancer angiogenesis by decreasing the secretion of VEGFA. Importantly, expression of miR-153 was induced by hypoxia-stimulated ER stress, which activates IRE1α and its downstream transcription factor X-box binding protein 1 (XBP1). X-box binding protein 1 directly binds to the promoter of the miR-153 host gene PTPRN and activates transcription. These results indicate that hypoxia induces miR-153 to fine tune the HIF1α/VEGFA axis in breast cancer angiogenesis and miR-153 could be used for breast cancer anti-angiogenesis therapy.

Levo-Tetrahydroberberrubine Produces Anxiolytic-Like Effects in Mice through the 5-HT1A Receptor.

Tetrahydroprotoberberines (THPBs) are isoquinoline alkaloids isolated from the Chinese herb Corydalis yanhusuo. In the present study, we performed competitive binding assays to examine the binding of l-THBr to neurotransmitter receptors known to be involved in sedation, hypnosis and anxiety. Our results show that l-THBr does not interact with GABAergic receptors but has binding affinities for dopamine and serotonin receptors. In addition, cAMP and [35S]GTPγS assays were used to determine the agonist or antagonist properties of l-THBr at dopamine (D1, D2) or serotonin (5-HT) receptors. Our results show that l-THBr displays D1 and D2 antagonist and 5-HT1A agonist properties. Moreover, l-THBr-treated rodents exhibit anxiolytic-like effects in the light/dark box and elevated plus-maze tests, and the anxiolytic effect of l-THBr can be reduced by WAY-100635, a selective 5-HT1A receptor antagonist. Our results suggest that l-THBr may produce potent anxiolytic-like effects mainly through serotonin receptors.

Mifepristone Suppresses Basal Triple-Negative Breast Cancer Stem Cells by Down-regulating KLF5 Expression.

Triple-negative breast cancer (TNBC) is currently the most malignant subtype of breast cancers without effective targeted therapies. Mifepristone (MIF), a drug regularly used for abortion, has been reported to have anti-tumor activity in multiple hormone-dependent cancers, including luminal type breast cancers. In this study, we showed that MIF suppressed tumor growth of the TNBC cell lines and patient-derived xenografts in NOD-SCID mice. Furthermore, MIF reduced the TNBC cancer stem cell (CSC) population through down-regulating KLF5 expression, a stem cell transcription factor over-expressed in basal type TNBC and promoting cell proliferation, survival and stemness. Interestingly, MIF suppresses the expression of KLF5 through inducing the expression of miR-153. Consistently, miR-153 decreases CSC and miR-153 inhibitor rescued MIF-induced down-regulation of the KLF5 protein level and CSC ratio. Taken together, our findings suggest that MIF inhibits basal TNBC via the miR-153/KLF5 axis and MIF may be used for the treatment of TNBC.