Characterization of a Steroid Receptor Coactivator Small Molecule Stimulator that Overstimulates Cancer Cells and Leads to Cell Stress and Death

Steroid receptor coactivators in Treg and Th17 cell biology and function

Steroid receptor coactivators (SRCs) are master regulators of transcription that play key roles in human physiology and pathology. SRCs are particularly important for the regulation of the immune system with major roles in lymphocyte fate determination and function, macrophage activity, regulation of nuclear factor κB (NF-κB) transcriptional activity and other immune system biology. The three members of the p160 SRC family comprise a network of immune-regulatory proteins that can function independently or act in synergy with each other, and compensate for - or moderate - the activity of other SRCs. Recent evidence indicates that the SRCs are key participants in governing numerous aspects of CD4+ T cell biology. Here we review findings that establish the SRCs as essential regulators of regulatory T cells (Tregs) and T helper 17 (Th17) cells, with a focus on their crucial roles in Treg immunity in cancer and Treg-Th17 cell phenotypic plasticity.

Targeting paraptosis in cancer: opportunities and challenges

Cell death can be classified into two primary categories: accidental cell death and regulated cell death (RCD). Within RCD, there are distinct apoptotic and non-apoptotic cell death pathways. Among the various forms of non-apoptotic RCD, paraptosis stands out as a unique mechanism characterized by distinct morphological changes within cells. These alterations encompass cytoplasmic vacuolization, organelle swelling, notably in the endoplasmic reticulum and mitochondria, and the absence of typical apoptotic features, such as cell shrinkage and DNA fragmentation. Biochemically, paraptosis distinguishes itself by its independence from caspases, which are conventionally associated with apoptotic death. This intriguing cell death pathway can be initiated by various cellular stressors, including oxidative stress, protein misfolding, and specific chemical compounds. Dysregulated paraptosis plays a pivotal role in several critical cancer-related processes, such as autophagic degradation, drug resistance, and angiogenesis. This review provides a comprehensive overview of recent advancements in our understanding of the mechanisms and regulation of paraptosis. Additionally, it delves into the potential of paraptosis-related compounds for targeted cancer treatment, with the aim of enhancing treatment efficacy while minimizing harm to healthy cells.

The Molecular Circadian Clock Is a Target of Anti-cancer Translation Inhibitors

Circadian-paced biological processes are key to physiology and required for metabolic, immunologic, and cardiovascular homeostasis. Core circadian clock components are transcription factors whose half-life is precisely regulated, thereby controlling the intrinsic cellular circadian clock. Genetic disruption of molecular clock components generally leads to marked pathological events phenotypically affecting behavior and multiple aspects of physiology. Using a transcriptional signature similarity approach, we identified anti-cancer protein synthesis inhibitors as potent modulators of the cardiomyocyte molecular clock. Eukaryotic protein translation inhibitors, ranging from translation initiation (rocaglates, 4-EGI1, etc.) to ribosomal elongation inhibitors (homoharringtonine, puromycin, etc.), were found to potently ablate protein abundance of REV-ERBα, a repressive nuclear receptor and component of the molecular clock. These inhibitory effects were observed both in vitro and in vivo and could be extended to PER2, another component of the molecular clock. Taken together, our observations suggest that the activity spectrum of protein synthesis inhibitors, whose clinical use is contemplated not only in cancers but also in viral infections, must be extended to circadian rhythm disruption, with potential beneficial or iatrogenic effects upon acute or prolonged administration.

New molecular targets in canine hemangiosarcoma-Comparative review and future of the precision medicine

Human angiosarcoma and canine hemangiosarcoma reveal similarities not only in their aggressive clinical behaviour, but especially in molecular landscape and genetic alterations involved in tumorigenesis and metastasis formation. Currently, no satisfying treatment that allows for achieving long overall survival or even prolonged time to progression does not exist. Due to the progress that has been made in targeted therapies and precision medicine the basis for a new treatment design is to uncover mutations and their functions as possible targets to provide tailored drugs for individual cases. Whole exome or genome sequencing studies and immunohistochemistry brought in the last few years important discoveries and identified the most common mutations with probably crucial role in this tumour development. Also, despite a lack of mutation in some of the culprit genes, the cancerogenesis cause may be buried in main cellular pathways connected with proteins encoded by those genes and involving, for example, pathological angiogenesis. The aim of this review is to highlight the most promising molecular targets for precision oncology treatment from the veterinary perspective aided by the principles of comparative science. Some of the drugs are only undergoing laboratory in vitro studies and others entered the clinic in the management of other cancer types in humans, but those used in dogs with promising responses have been mentioned as priorities.

AIB1/SRC-3/NCOA3 function in estrogen receptor alpha positive breast cancer

The estrogen receptor alpha (ERα) is a steroid receptor that is pivotal in the initiation and progression of most breast cancers. ERα regulates gene transcription through recruitment of essential coregulators, including the steroid receptor coactivator AIB1 (Amplified in Breast Cancer 1). AIB1 itself is an oncogene that is overexpressed in a subset of breast cancers and is known to play a role in tumor progression and resistance to endocrine therapy through multiple mechanisms. Here we review the normal and pathological functions of AIB1 in regard to its ERα-dependent and ERα-independent actions, as well as its genomic conservation and protein evolution. We also outline the efforts to target AIB1 in the treatment of breast cancer.

MCB-613 exploits a collateral sensitivity in drug resistant EGFR-mutant non-small cell lung cancer through covalent inhibition of KEAP1

Targeted therapies have revolutionized cancer chemotherapy. Unfortunately, most patients develop multifocal resistance to these drugs within a matter of months. Here, we used a high-throughput phenotypic small molecule screen to identify MCB-613 as a compound that selectively targets EGFR-mutant, EGFR inhibitor-resistant non-small cell lung cancer (NSCLC) cells harboring diverse resistance mechanisms. Subsequent proteomic and functional genomic screens involving MCB-613 identified its target in this context to be KEAP1, revealing that this gene is selectively essential in the setting of EGFR inhibitor resistance. In-depth molecular characterization demonstrated that (1) MCB-613 binds KEAP1 covalently; (2) a single molecule of MCB-613 is capable of bridging two KEAP1 monomers together; and, (3) this modification interferes with the degradation of canonical KEAP1 substrates such as NRF2. Surprisingly, NRF2 knockout sensitizes cells to MCB-613, suggesting that the drug functions through modulation of an alternative KEAP1 substrate. Together, these findings advance MCB-613 as a new tool for exploiting the selective essentiality of KEAP1 in drug-resistant, EGFR-mutant NSCLC cells.

Mechanism of andrographis paniculata on lung cancer by network pharmacology and molecular docking

BACKGROUND

Traditional Chinese medicine (TCM) has been widely recognized and accepted worldwide to provide favorable therapeutic effects for cancer patients. As Andrographis paniculata has an anti-tumor effect, it might inhibit lung cancer.

OBJECTIVE

The drug targets and related pathways involved in the action of Andrographis paniculata against lung cancer were predicted using network pharmacology, and its mechanism was further explored at the molecular level.

METHODS

This work selected the effective components and targets of Andrographis paniculata against the Traditional Chinese Medicine System Pharmacology (TCMSP) database. Targets related to lung cancer were searched for in the GEO database (accession number GSE136043). The volcanic and thermal maps of differential expression genes were produced using the software R. Then, the target genes were analyzed by GO and KEGG analysis using the software R. This also utilized the AutoDock tool to study the molecular docking of the active component structures downloaded from the PubChem database and the key target structures downloaded from the PDB database, and the docking results were visualized using the software PyMol.

RESULTS

The results of molecular docking show that wogonin, Mono-O-methylwightin, Deoxycamptothecine, andrographidine F_qt, Quercetin tetramethyl (3',4',5,7) ether, 14-deoxyandrographolide, andrographolide-19-β-D-glucoside_qt and 14-deoxy-11-oxo-andrographolide were potential active components, while AKT1, MAPK14, RELA and NCOA1 were key targets.

CONCLUSION

This study showed the main candidate components, targets, and pathways involved in the action of Andrographis paniculata against lung cancer.

Steroid receptor coactivators - their role in immunity

Steroid Receptor Coactivators (SRCs) are essential regulators of transcription with a wide range of impact on human physiology and pathology. In immunology, SRCs play multiple roles; they are involved in the regulation of nuclear factor-κB (NF-κB), macrophage (MΦ) activity, lymphoid cells proliferation, development and function, to name just a few. The three SRC family members, SRC-1, SRC-2 and SRC-3, can exert their immunological function either in an independent manner or act in synergy with each other. In certain biological contexts, one SRC family member can compensate for lack of activity of another member, while in other cases one SRC can exert a biological function that competes against the function of another family counterpart. In this review we illustrate the diverse biological functionality of the SRCs with regard to their role in immunity. In the light of recent development of SRC small molecule inhibitors and stimulators, we discuss their potential relevance as modulators of the immunological activity of the SRCs for therapeutic purposes.

A steroid receptor coactivator small molecule "stimulator" attenuates post-stroke ischemic brain injury

Introduction: Pathologic remodeling of the brain following ischemic stroke results in neuronal loss, increased inflammation, oxidative stress, astrogliosis, and a progressive decrease in brain function. We recently demonstrated that stimulation of steroid receptor coactivator 3 with the small-molecule stimulator MCB-613 improves cardiac function in a mouse model of myocardial ischemia. Since steroid receptor coactivators are ubiquitously expressed in the brain, we reasoned that an MCB-613 derivative (MCB-10-1), could protect the brain following ischemic injury. To test this, we administered MCB-10-1 to rats following middle cerebral artery occlusion and reperfusion. Methods: Neurologic impairment and tissue damage responses were evaluated on day 1 and day 4 following injury in rats treated with control or 10-1. Results: We show that 10-1 attenuates injury post-stroke. 10-1 decreases infarct size and mitigates neurologic impairment. When given within 30 min post middle cerebral artery occlusion and reperfusion, 10-1 induces lasting protection from tissue damage in the ischemic penumbra concomitant with: (1) promotion of reparative microglia; (2) an increase in astrocyte NRF2 and GLT-1 expression; (3) early microglia activation; and (4) attenuation of astrogliosis. Discussion: Steroid receptor coactivator stimulation with MCB-10-1 is a potential therapeutic strategy for reducing inflammation and oxidative damage that cause neurologic impairment following an acute ischemic stroke.

Approaches towards tissue-selective pharmacology of the mineralocorticoid receptor

Mineralocorticoid receptor antagonists (MRAs) are highly effective therapies for cardiovascular and renal disease. However, the widespread clinical use of currently available MRAs in cardiorenal medicine is hampered by an increased risk of hyperkalemia. The mineralocorticoid receptor (MR) is a nuclear receptor responsible for fluid and electrolyte homeostasis in epithelial tissues, whereas pathophysiological MR activation in nonepithelial tissues leads to undesirable pro-inflammatory and pro-fibrotic effects. Therefore, new strategies that selectively target the deleterious effects of MR but spare its physiological function are needed. In this review, we discuss recent pharmacological developments starting from novel non-steroidal MRAs that are now entering clinical use, such as finerenone or esaxerenone, to concepts arising from the current knowledge of the MR signaling pathway, aiming at receptor-coregulator interaction, epigenetics, or downstream effectors of MR.

Role of estrogen receptor coregulators in endocrine resistant breast cancer

Breast cancer (BC) is the most ubiquitous cancer in women. Approximately 70–80% of BC diagnoses are positive for estrogen receptor (ER) alpha (ERα). The steroid hormone estrogen [17β-estradiol (E2)] plays a vital role both in the initiation and progression of BC. The E2-ERα mediated actions involve genomic signaling and non-genomic signaling. The specificity and magnitude of ERα signaling are mediated by interactions between ERα and several coregulator proteins called coactivators or corepressors. Alterations in the levels of coregulators are common during BC progression and they enhance ligand-dependent and ligand-independent ERα signaling which drives BC growth, progression, and endocrine therapy resistance. Many ERα coregulator proteins function as scaffolding proteins and some have intrinsic or associated enzymatic activities, thus the targeting of coregulators for blocking BC progression is a challenging task. Emerging data from in vitro and in vivo studies suggest that targeting coregulators to inhibit BC progression to therapy resistance is feasible. This review explores the current state of ERα coregulator signaling and the utility of targeting the ERα coregulator axis in treating advanced BC.

Small Molecules Targeting Programmed Cell Death in Breast Cancer Cells

Targeted chemotherapy has become the forefront for cancer treatment in recent years. The selective and specific features allow more effective treatment with reduced side effects. Most targeted therapies, which include small molecules, act on specific molecular targets that are altered in tumour cells, mainly in cancers such as breast, lung, colorectal, lymphoma and leukaemia. With the recent exponential progress in drug development, programmed cell death, which includes apoptosis and autophagy, has become a promising therapeutic target. The research in identifying effective small molecules that target compensatory mechanisms in tumour cells alleviates the emergence of drug resistance. Due to the heterogenous nature of breast cancer, various attempts were made to overcome chemoresistance. Amongst breast cancers, triple negative breast cancer (TNBC) is of particular interest due to its heterogeneous nature in response to chemotherapy. TNBC represents approximately 15% of all breast tumours, however, and still has a poor prognosis. Unlike other breast tumours, signature targets lack for TNBCs, causing high morbidity and mortality. This review highlights several small molecules with promising preclinical data that target autophagy and apoptosis to induce cell death in TNBC cells.

Steroid receptor coactivator-1: The central intermediator linking multiple signals and functions in the brain and spinal cord

The effects of steroid hormones are believed to be mediated by their nuclear receptors (NRs). The p160 coactivator family, including steroid receptor coactivator-1 (SRC-1), 2 and 3, has been shown to physically interact with NRs to enhance their transactivational activities. Among which SRC-1 has been predominantly localized in the central nervous system including brain and spinal cord. It is not only localized in neurons but also detectable in neuroglial cells (mainly localized in the nuclei but also detectable in the extra-nuclear components). Although the expression of SRC-1 is regulated by many steroids, it is also regulated by some non-steroidal factors such as injury, sound and light. Functionally, SRC-1 has been implied in normal function such as development and ageing, learning and memory, central regulation on reproductive behaviors, motor and food intake. Pathologically, SRC-1 may play a role in the regulation of neuropsychiatric disorders (including stress, depression, anxiety, and autism spectrum disorder), metabolite homeostasis and obesity as well as tumorigenesis. Under most conditions, the related mechanisms are far from elucidation; although it may regulate spatial memory through Rictor/mTORC2-actin polymerization related synaptic plasticity. Several inhibitors and stimulator of SRC-1 have shown anti-cancer potentials, but whether these small molecules could be used to modulate ageing and central disorder related neuropathology remain unclear. Therefore, to elucidate when and how SRC-1 is turned on and off under different stimuli is very interesting and great challenge for neuroscientists.

SRC-3, a Steroid Receptor Coactivator: Implication in Cancer

Steroid receptor coactivator-3 (SRC-3), also known as amplified in breast cancer 1 (AIB1), is a member of the SRC family. SRC-3 regulates not only the transcriptional activity of nuclear receptors but also many other transcription factors. Besides the essential role of SRC-3 in physiological functions, it also acts as an oncogene to promote multiple aspects of cancer. This review updates the important progress of SRC-3 in carcinogenesis and summarizes its mode of action, which provides clues for cancer therapy.

Wound Healing-related Functions of the p160 Steroid Receptor Coactivator Family

Multicellular organisms have evolved sophisticated mechanisms to recover and maintain original tissue functions following injury. Injury responses require a robust transcriptomic response associated with cellular reprogramming involving complex gene expression programs critical for effective tissue repair following injury. Steroid receptor coactivators (SRCs) are master transcriptional regulators of cell-cell signaling that is integral for embryogenesis, reproduction, normal physiological function, and tissue repair following injury. Effective therapeutic approaches for facilitating improved tissue regeneration and repair will likely involve temporal and combinatorial manipulation of cell-intrinsic and cell-extrinsic factors. Pleiotropic actions of SRCs that are critical for wound healing range from immune regulation and angiogenesis to maintenance of metabolic regulation in diverse organ systems. Recent evidence derived from studies of model organisms during different developmental stages indicates the importance of the interplay of immune cells and stromal cells to wound healing. With SRCs being the master regulators of cell-cell signaling integral to physiologic changes necessary for wound repair, it is becoming clear that therapeutic targeting of SRCs provides a unique opportunity for drug development in wound healing. This review will provide an overview of wound healing-related functions of SRCs with a special focus on cellular and molecular interactions important for limiting tissue damage after injury. Finally, we review recent findings showing stimulation of SRCs following cardiac injury with the SRC small molecule stimulator MCB-613 can promote cardiac protection and inhibit pathologic remodeling after myocardial infarction.

Comparative analysis of the AIB1 interactome in breast cancer reveals MTA2 as a repressive partner which silences E-Cadherin to promote EMT and associates with a pro-metastatic phenotype

Steroid regulated cancer cells use nuclear receptors and associated regulatory proteins to orchestrate transcriptional networks to drive disease progression. In primary breast cancer, the coactivator AIB1 promotes estrogen receptor (ER) transcriptional activity to enhance cell proliferation. The function of the coactivator in ER+ metastasis however is not established. Here we describe AIB1 as a survival factor, regulator of pro-metastatic transcriptional pathways and a promising actionable target. Genomic alterations and functional expression of AIB1 associated with reduced disease-free survival in patients and enhanced metastatic capacity in novel CDX and PDX ex-vivo models of ER+ metastatic disease. Comparative analysis of the AIB1 interactome with complementary RNAseq characterized AIB1 as a transcriptional repressor. Specifically, we report that AIB1 interacts with MTA2 to form a repressive complex, inhibiting CDH1 (encoding E-cadherin) to promote EMT and drive progression. We further report that pharmacological and genetic inhibition of AIB1 demonstrates significant anti-proliferative activity in patient-derived models establishing AIB1 as a viable strategy to target endocrine resistant metastasis. This work defines a novel role for AIB1 in the regulation of EMT through transcriptional repression in advanced cancer cells with a considerable implication for prognosis and therapeutic interventions.

Predicting chemosensitivity using drug perturbed gene dynamics

Background

One of the current directions of precision medicine is the use of computational methods to aid in the diagnosis, prognosis, and treatment of disease based on data driven approaches. For instance, in oncology, there has been a particular focus on development of algorithms and biomarkers that can be used for pre-clinical and clinical applications. In particular large-scale omics-based models to predict drug sensitivity in in vitro cancer cell line panels have been used to explore the utility and aid in the development of these models as clinical tools. Additionally, a number of web-based interfaces have been constructed for researchers to explore the potential of drug perturbed gene expression as biomarkers including the NCI Transcriptional Pharmacodynamic Workbench. In this paper we explore the influence of drug perturbed gene dynamics of the NCI Transcriptional Pharmacodynamics Workbench in computational models to predict in vitro drug sensitivity for 15 drugs on the NCI60 cell line panel.

Results

This work presents three main findings. First, our models show that gene expression profiles that capture changes in gene expression after 24 h of exposure to a high concentration of drug generates the most accurate predictive models compared to the expression profiles under different dosing conditions. Second, signatures of 100 genes are developed for different gene expression profiles; furthermore, when the gene signatures are applied across gene expression profiles model performance is substantially decreased when gene signatures developed using changes in gene expression are applied to non-drugged gene expression. Lastly, we show that the gene interaction networks developed on these signatures show different network topologies and can be used to inform selection of cancer relevant genes.

Conclusion

Our models suggest that perturbed gene signatures are predictive of drug response, but cannot be applied to predict drug response using unperturbed gene expression. Furthermore, additional drug perturbed gene expression measurements in in vitro cell lines could generate more predictive models; but, more importantly be used in conjunction with computational methods to discover important drug disease relationships.

Ouabain and Digoxin Activate the Proteasome and the Degradation of the ERα in Cells Modeling Primary and Metastatic Breast Cancer

Simple Summary

Breast cancer (BC) treatment relies on the detection of the estrogen receptor α (ERα). ERα-expressing BC patients are treated with anti-estrogen drugs (i.e., tamoxifen and fulvestrant). Despite their proven efficacy, these drugs cause serious side effects in a significant fraction of the patients, including both tumor insurgence in secondary organs, and resistant phenotypes, which result in a relapsing disease with scarce treatment options. Thus, new drugs for treatment of primary and metastatic BC (MBC) are needed. Here, we report the characterization of two cardiac glycosides (CGs) (i.e., ouabain and digoxin), approved by the FDA for treatment of heart disease, as novel ‘anti-estrogen’-like drugs. We found that these drugs induce ERα degradation, and prevent the proliferation of cellular models of primary and metastatic BC cells. Remarkably, we discovered that these CGs are activators of the proteasome, and therefore may be repurposed for treatment not only of BC, but also for other proteasome-based diseases.

Abstract

Estrogen receptor α expressing breast cancers (BC) are classically treated with endocrine therapy. Prolonged endocrine therapy often results in a metastatic disease (MBC), for which a standardized effective therapy is still lacking. Thus, new drugs are required for primary and metastatic BC treatment. Here, we report that the Food and Drug Administration (FDA)-approved drugs, ouabain and digoxin, induce ERα degradation and prevent proliferation in cells modeling primary and metastatic BC. Ouabain and digoxin activate the cellular proteasome, instigating ERα degradation, which causes the inhibition of 17β-estradiol signaling, induces the cell cycle blockade in the G2 phase, and triggers apoptosis. Remarkably, these effects are independent of the inhibition of the Na/K pump. The antiproliferative effects of ouabain and digoxin occur also in diverse cancer models (i.e., tumor spheroids and xenografts). Additionally, gene profiling analysis reveals that these drugs downregulate the expression of genes related to endocrine therapy resistance. Therefore, ouabain and digoxin behave as ‘anti-estrogen’-like drugs, and are appealing candidates for the treatment of primary and metastatic BCs.

Novel 3-(3, 5-difluoro-4-hydroxyphenyl)-1-(naphthalen-2-yl) prop-2-en-1-one as a potent inhibitor of MAP-kinase in HeLa cell lines and anti-angiogenic activity is mediated by HIF-1α in EAC animal model

In the present investigation, we synthesized chalcone bearing naphthalene compound d1, and on the basis of ¹H-NMR, ¹³C NMR, and LC-MS data we had specified the structure of the synthesized compound. The resultant compound d1 was assessed for their antiproliferative action against human cancer cell lines (HeLa, HCT116, HT29, MDA-MB-231, MCF-7, and SKBR3). The IC₅₀ range was estimated at 5.58 to 11.13 μM shows that compound d1 had remarkable anticancer activity on HeLa cell lines. Besides, it was discovered that d1 incited the mitochondrial apoptotic pathway by controlling Bax and Bcl-2 transcripts by expanding the Caspase 3 activation. We depicted the in-vivo effects of tumor advancement and the antiangiogenic activity of d1 in the EAC animal model. Tumor growth had inhibited and without symptoms the longevity of EAC containing mice expanded by the treatment of d1. Inhibition of nuclear transcriptional factor HIF-1α in EAC cells and finally it also inhibited phosphorylation of downstream signaling proteins such as ERK_1/2, p38, and JNK in HeLa cells. The present investigation uncovered that d1 indicated noteworthy tumor-repressing abilities much less concentration in in-vitro and in-vivo recommended that compound d1 as the potent anticancer medication.

A steroid receptor coactivator stimulator (MCB-613) attenuates adverse remodeling after myocardial infarction

We are at an exciting era of identification of the cell and molecular processes necessary for tissue remodeling and repair. Unlike current systemic therapeutics, our studies reveal pharmacologic stimulation of SRCs modulates macrophage and fibrotic reparative cell responses to promote more effective repair and lasting beneficial remodeling after myocardial infarction.

Progressive remodeling of the heart, resulting in cardiomyocyte (CM) loss and increased inflammation, fibrosis, and a progressive decrease in cardiac function, are hallmarks of myocardial infarction (MI)-induced heart failure. We show that MCB-613, a potent small molecule stimulator of steroid receptor coactivators (SRCs) attenuates pathological remodeling post-MI. MCB-613 decreases infarct size, apoptosis, hypertrophy, and fibrosis while maintaining significant cardiac function. MCB-613, when given within hours post MI, induces lasting protection from adverse remodeling concomitant with: 1) inhibition of macrophage inflammatory signaling and interleukin 1 (IL-1) signaling, which attenuates the acute inflammatory response, 2) attenuation of fibroblast differentiation, and 3) promotion of Tsc22d3-expressing macrophages—all of which may limit inflammatory damage. SRC stimulation with MCB-613 (and derivatives) is a potential therapeutic approach for inhibiting cardiac dysfunction after MI.

Exploring the multiple roles of guardian of the genome: P53

Background

Cells have evolved balanced mechanisms to protect themselves by initiating a specific response to a variety of stress. TheTP53gene, encoding P53 protein, is one of the many widely studied genes in human cells owing to its multifaceted functions and complex dynamics. The tumour-suppressing activity of P53 plays a principal role in the cellular response to stress. The majority of the human cancer cells exhibit the inactivation of the P53 pathway. In this review, we discuss the recent advancements in P53 research with particular focus on the role of P53 in DNA damage responses, apoptosis, autophagy, and cellular metabolism. We also discussed important P53-reactivation strategies that can play a crucial role in cancer therapy and the role of P53 in various diseases.

Main body

We used electronic databases like PubMed and Google Scholar for literature search. In response to a variety of cellular stress such as genotoxic stress, ischemic stress, oncogenic expression, P53 acts as a sensor, and suppresses tumour development by promoting cell death or permanent inhibition of cell proliferation. It controls several genes that play a role in the arrest of the cell cycle, cellular senescence, DNA repair system, and apoptosis. P53 plays a crucial role in supporting DNA repair by arresting the cell cycle to purchase time for the repair system to restore genome stability. Apoptosis is essential for maintaining tissue homeostasis and tumour suppression. P53 can induce apoptosis in a genetically unstable cell by interacting with many pro-apoptotic and anti-apoptotic factors.

Furthermore, P53 can activate autophagy, which also plays a role in tumour suppression. P53 also regulates many metabolic pathways of glucose, lipid, and amino acid metabolism. Thus under mild metabolic stress, P53 contributes to the cell’s ability to adapt to and survive the stress.

Conclusion

These multiple levels of regulation enable P53 to perform diversified roles in many cell responses. Understanding the complete function of P53 is still a work in progress because of the inherent complexity involved in between P53 and its target proteins. Further research is required to unravel the mystery of this Guardian of the genome “TP53”.

Dienone Compounds: Targets and Pharmacological Responses

The biological responses to dienone compounds with a 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have been studied extensively. Despite their expected general thiol reactivity, these compounds display considerable degrees of tumor cell selectivity. Here we review in vitro and preclinical studies of dienone compounds including b-AP15, VLX1570, RA-9, RA-190, EF24, HO-3867, and MCB-613. A common property of these compounds is their targeting of the ubiquitin–proteasome system (UPS), known to be essential for the viability of tumor cells. Gene expression profiling experiments have shown induction of responses characteristic of UPS inhibition, and experiments using cellular reporter proteins have shown that proteasome inhibition is associated with cell death. Other mechanisms of action such as reactivation of mutant p53, stimulation of steroid receptor coactivators, and induction of protein cross-linking have also been described. Although unsuitable as biological probes due to widespread reactivity, dienone compounds are cytotoxic to apoptosis-resistant tumor cells and show activity in animal tumor models.

SRC-1 Knockout Exerts No Effect on Amyloid β Deposition in APP/PS1 Mice

Steroid receptor coactivator 1 (SRC-1) is the key coactivator because of its transcriptional activity. Previous studies have shown that SRC-1 is abundant in the hippocampus and has been implicated in cognition. SRC-1 is also related to some major risk factors for Alzheimer’s disease (AD), such as a decline in estrogen and aging, however, whether SRC-1 is involved in the pathogenesis of AD remains unclear. In this study, we established SRC-1 knockout in AD mice by cross breeding SRC-1^−/− mutant mice with APP/PS1 transgenic mice, and investigated the expression of some synaptic proteins, the amyloid β (Aβ) deposition, and activation of astrocytes and microglia in the hippocampus of APP/PS1×SRC-1^−/− mice. The results showed that SRC-1 knockout neither affects the Aβ plaque and activation of glia, nor changes the expression of synaptic proteins in AD model mice. The above results suggest that the complete deletion of SRC-1 in the embryo exerts no effect on the pathogenesis of APP/PS1 mice. Nevertheless, this study could not eliminate the possible role of SRC-1 in the development of AD due to the lack of observation of other events in AD such as tau hyperphosphorylation and the limitation of the animal model employed.

Patent highlights February–March 2020

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Long-Term Follow-Up and Treatment of a Female With Complete Estrogen Insensitivity

CONTEXT

We previously reported the first female with a causative ESR1 gene variant, who exhibited absent puberty and high estrogens. At age 15 years, she presented with lower abdominal pain, absent breast development, primary amenorrhea, and multicystic ovaries. The natural history of complete estrogen insensitivity (CEI) in women is unknown.

OBJECTIVE

The purpose of this report is to present the neuroendocrine phenotype of CEI, identify potential ligands, and determine the effect of targeted treatment.

DESIGN

We have characterized gonadotropin pulsatility and followed this patient's endocrine profile and bone density over 8 years. Seventy-five different compounds were tested for transactivation of the variant receptor. A personalized medicine approach was tailored to our patient.

SETTING

Academic medical center.

PATIENT OR OTHER PARTICIPANTS

A 24-year-old adopted white female with CEI.

INTERVENTION(S)

The patient was treated with diethylstilbestrol (DES) for approximately 2.5 years.

MAIN OUTCOME MEASURE(S)

Induction of secondary sexual characteristics.

RESULTS

Luteinizing hormone (LH) pulse studies demonstrated normal pulsatile LH secretion, elevated mean LH, and mildly elevated mean follicle-stimulating hormone (FSH) in the presence of markedly increased estrogens. DES transactivated the variant ESR1 in vitro. However, DES treatment did not induce secondary sexual characteristics in our patient.

CONCLUSIONS

Treatment with DES was not successful in our patient. She remains hypoestrogenic despite the presence of ovarian cysts with a hypoestrogenic vaginal smear, absent breast development, and low bone mineral mass. Findings suggest additional receptor mechanistic actions are required to elicit clinical hormone responses.

Gene co-expression network for analysis of plasma exosomal miRNAs in the elderly as markers of aging and cognitive decline

BACKGROUND

Evidence has shown that microRNA (miRNAs) are involved in molecular pathways responsible for aging and age-related cognitive decline. However, there is a lack of research linked plasma exosome-derived miRNAs changes with cognitive function in older people and aging, which might prove a new insight on the transformation of miRNAs on clinical applications for cognitive decline for older people.

METHODS

We applied weighted gene co-expression network analysis to investigated miRNAs within plasma exosomes of older people for a better understanding of the relationship of exosome-derived miRNAs with cognitive decline in elderly adults. We identified network modules of co-expressed miRNAs in the elderly exosomal miRNAs dataset. In each module, we selected vital miRNAs and carried out functional enrichment analyses of their experimentally known target genes and their function.

RESULTS

We found that plasma exosomal miRNAs hsa-mir-376a-3p, miR-10a-5p, miR-125-5p, miR-15a-5p have critical regulatory roles in the development of aging and cognitive dysfunction in the elderly and may serve as biomarkers and putative novel therapeutic targets for aging and cognitive decline.

Therapies Targeted to Androgen Receptor Signaling Axis in Prostate Cancer: Progress, Challenges, and Hope

Prostate cancer is the mostly commonly diagnosed non-cutaneous malignancy and the second leading cause of cancer-related death affecting men in the United States. Moreover, it disproportionately affects the men of African origin, who exhibit significantly greater incidence and mortality as compared to the men of European origin. Since androgens play an important role in the growth of normal prostate and prostate tumors, targeting of androgen signaling has remained a mainstay for the treatment of aggressive prostate cancer. Over the years, multiple approaches have been evaluated to effectively target the androgen signaling pathway that include direct targeting of the androgens, androgen receptor (AR), AR co-regulators or other alternate mechanisms that impact the outcome of androgen signaling. Several of these approaches are currently in clinical practice, while some are still pending further development and clinical evaluation. This remarkable progress has resulted from extensive laboratory, pre-clinical and clinical efforts, and mechanistic learnings from the therapeutic success and failures. In this review, we describe the importance of androgen signaling in prostate cancer biology and advances made over the years to effectively target this signaling pathway. We also discuss emerging data on the resistance pathways associated with the failure of various androgen signaling- targeted therapies and potential of this knowledge for translation into future therapies for prostate cancer.

SRC3 expressed in bone marrow mesenchymal stem cells promotes the development of multiple myeloma

SRC3 plays critical roles in various biological processes of diseases, including proliferation, apoptosis, migration, and cell cycle arrest. However, the effect of SRC3 expression in mesenchymal stem cells (MSCs) on multiple myeloma (MM) is not clear yet. In our study, MSCs (MSC-SRC3, MSC-SRC3-/-) and MM cells were co-cultured in a direct or indirect way. The proliferation of MM cells was studied by CCK-8 and colony formation assays. The apoptosis and cell cycle of MM cells were detected by flow cytometry. In addition, the expressions of proteins in MM cells were detected by western blot analysis and the secretions of cytokines were measured by ELISA. Our data showed that the expression of SRC3 in bone marrow mesenchymal stem cells (BM-MSCs) could promote cell proliferation and colony formation of MM cells through accelerating the transformation of the G1/S phase, no matter what kind of culture method was adopted. Meanwhile, SRC3 expressed in BM-MSCs could inhibit the apoptosis of MM cells through the caspase apoptosis pathway and mitochondrial apoptosis pathway. Moreover, SRC3 could enhance the adhesion ability of MM cells through up-regulating the expression of adhesion molecules including CXCL4, ICAM1, VLA4, and syndecan-1. SRC3 also played a regulatory role in the progress of MM through the NF-κB and PI-3K/Akt pathways. SRC3 expressed in MSCs was found to promote the growth and survival of MM cells, while SRC3 silencing in MSCs could inhibit the development of MM. These results would be useful for developing a more effective new strategy for MM treatment.

The transcriptional co-activator NCOA6 promotes estrogen-induced GREB1 transcription by recruiting ERα and enhancing enhancer-promoter interactions

Estrogen and its cognate receptor, ERα, regulate cell proliferation, differentiation, and carcinogenesis in the endometrium by controlling gene transcription. ERα requires co-activators to mediate transcription via mechanisms that are largely uncharacterized. Herein, using growth-regulating estrogen receptor binding 1 (GREB1) as an ERα target gene in Ishikawa cells, we demonstrate that nuclear receptor co-activator 6 (NCOA6) is essential for estradiol (E2)/ERα-activated GREB1 transcription. We found that NCOA6 associates with the GREB1 promoter and enhancer in an E2-independent manner and that NCOA6 knockout reduces chromatin looping, enhancer-promoter interactions, and basal GREB1 expression in the absence of E2. In the presence of E2, ERα bound the GREB1 enhancer and also associated with its promoter, and p300, myeloid/lymphoid or mixed-lineage leukemia protein 4 (MLL4), and RNA polymerase II were recruited to the GREB1 enhancer and promoter. Consequently, the levels of the histone modifications H3K4me1/3, H3K9ac, and H3K27ac were significantly increased; enhancer and promoter regions were transcribed; and GREB1 mRNA was robustly transcribed. NCOA6 knockout reduced ERα recruitment and abolished all of the aforementioned E2-induced events, making GREB1 completely insensitive to E2 induction. We also found that GREB1-deficient Ishikawa cells are much more resistant to chemotherapy and that human endometrial cancers with low GREB1 expression predict poor overall survival. These results indicate that NCOA6 has an essential role in ERα-mediated transcription by increasing enhancer-promoter interactions through chromatin looping and by recruiting RNA polymerase II and the histone-code modifiers p300 and MLL4. Moreover, GREB1 loss may predict chemoresistance of endometrial cancer.

Evolving trends in pancreatic cancer therapeutic development

Despite advances in translational research, the overall 5-year survival for pancreatic cancer remains dismal and with rising incidence pancreatic cancer is predicted to be the second leading cause of cancer death for many developed countries. Surgical intervention followed by cytotoxic chemotherapy are currently the best options for treatment, but disease recurrence is very common. Efforts to develop new therapeutic agents and delivery systems are necessary to achieve better clinical efficacy with less toxicity. Promising prospects are arising with new preclinical and clinical therapeutic strategies using small molecule targeted therapies, RNAi, stromal therapies, and immunotherapies. With a better understanding of the biology to aid target selection and discovery of biomarkers to aid precision medicine, better opportunities will evolve to shape the therapeutic landscape, enhance patient quality of life and increase overall survival.

Depletion of the Transcriptional Coactivator Amplified in Breast Cancer 1 (AIB1) Uncovers Functionally Distinct Subpopulations in Triple-Negative Breast Cancer

The transcriptional coactivator Amplified in Breast Cancer 1 (AIB1) plays a major role in the progression of hormone and HER2-dependent breast cancers but its role in triple negative breast cancer (TNBC) is undefined. Here, we report that established TNBC cell lines, as well as cells from a TNBC patient-derived xenograft (PDX) that survive chemotherapy treatment in vitro express lower levels of AIB1 protein. The surviving cell population has an impaired tube-formation phenotype when cultured onto basement membrane, a property shared with TNBC cells that survive shRNA-mediated depletion of AIB1 (AIB1LOW cells). DNA analysis by exome sequencing revealed that AIB1LOW cells represent a distinct subpopulation. Consistent with their in vitro phenotype AIB1LOW cells implanted orthotopically generated slower growing tumors with less capacity for pulmonary metastases. Gene expression analysis of cultured cells and tumors revealed that AIB1LOW cells display a distinct expression signature of genes in pro-inflammatory pathways, cell adhesion, proteolysis and tissue remodeling. Interestingly, the presence of this AIB1LOW expression signature in breast cancer specimens is associated with shorter disease free survival of chemotherapy treated patients. We concluded that TNBC cell lines contain heterogeneous populations with differential dependence on AIB1 and that the gene expression pattern of AIB1LOW cells may represent a signature indicative of poor response to chemotherapy in TNBC patients.

Metabolic Dysregulation Controls Endocrine Therapy-Resistant Cancer Recurrence and Metastasis

Cancer recurrence and metastasis involves many biological interactions, such as genetic, transcription, environmental, endocrine signaling, and metabolism. These interactions add a complex understanding of cancer recurrence and metastatic progression, delaying the advancement in therapeutic opportunities. We highlight the recent advances on the molecular complexities of endocrine-related cancers, focusing on breast and prostate cancer, and briefly review how endocrine signaling and metabolic programs can influence transcriptional complexes for metastasis competence. Nuclear receptors and transcriptional coregulators function as molecular nodes for the crosstalk between endocrine signaling and metabolism that alter downstream gene expression important for tumor progression and metastasis. This exciting regulatory axis may provide insights to the development of cancer therapeutics important for these desensitized endocrine-dependent cancers.

Multidimensional profiling of drug-treated cells by Imaging Mass Cytometry

In pharmaceutical research, high‐content screening is an integral part of lead candidate development. Measuring drug response in vitro by examining over 40 parameters, including biomarkers, signaling molecules, cell morphological changes, proliferation indices, and toxicity in a single sample, could significantly enhance discovery of new therapeutics. As a proof of concept, we present here a workflow for multidimensional Imaging Mass Cytometry™ (IMC™) and data processing with open source computational tools. CellProfiler was used to identify single cells through establishing cellular boundaries, followed by histoCAT™ (histology topography cytometry analysis toolbox) for extracting single‐cell quantitative information visualized as t‐SNE plots and heatmaps. Human breast cancer‐derived cell lines SKBR3, HCC1143, and MCF‐7 were screened for expression of cellular markers to generate digital images with a resolution comparable to conventional fluorescence microscopy. Predicted pharmacodynamic effects were measured in MCF‐7 cells dosed with three target‐specific compounds: growth stimulatory EGF, microtubule depolymerization agent nocodazole, and genotoxic chemotherapeutic drug etoposide. We show strong pairwise correlation between nuclear markers pHistone3^S28, Ki‐67, and p4E‐BP1^T37/T46 in classified mitotic cells and anticorrelation with cell surface markers. Our study demonstrates that IMC data expand the number of measured parameters in single cells and brings higher‐dimension analysis to the field of cell‐based screening in early lead compound discovery.

Steroid receptor coactivator-1 modulates the function of Pomc neurons and energy homeostasis

Hypothalamic neurons expressing the anorectic peptide Pro-opiomelanocortin (Pomc) regulate food intake and body weight. Here, we show that Steroid Receptor Coactivator-1 (SRC-1) interacts with a target of leptin receptor activation, phosphorylated STAT3, to potentiate Pomc transcription. Deletion of SRC-1 in Pomc neurons in mice attenuates their depolarization by leptin, decreases Pomc expression and increases food intake leading to high-fat diet-induced obesity. In humans, fifteen rare heterozygous variants in SRC-1 found in severely obese individuals impair leptin-mediated Pomc reporter activity in cells, whilst four variants found in non-obese controls do not. In a knock-in mouse model of a loss of function human variant (SRC-1^L1376P), leptin-induced depolarization of Pomc neurons and Pomc expression are significantly reduced, and food intake and body weight are increased. In summary, we demonstrate that SRC-1 modulates the function of hypothalamic Pomc neurons, and suggest that targeting SRC-1 may represent a useful therapeutic strategy for weight loss.

Nuclear Receptor Coactivator 2 Promotes Human Breast Cancer Cell Growth by Positively Regulating the MAPK/ERK Pathway

As a member of the p160 steroid receptor coactivator (SRC) family, nuclear receptor coactivator 2 (NCOA2) is known to play essential roles in many physiological and pathological processes, including development, endocrine regulation, and tumorigenesis. However, the biological function of NCOA2 in breast cancer is not fully understood. We found that the copy number of the NCOA2 gene was frequently amplified in four breast cancers datasets, varying from 6 to 10%, and the mRNA levels of NCOA2 were also upregulated in 11% of the sequenced cases/patients (TCGA provisional dataset). Next, we confirmed that NCOA2 silencing significantly suppressed cell proliferation in different breast cancer cell lines, by inducing cell cycle arrest and apoptosis. Mechanistically, whole-transcriptome sequencing (RNA-Seq) analysis showed that NCOA2 depletion leads to downregulation of the MAPK/ERK signaling cascade, possibly via downregulating NCOA2's downstream target RASEF. In conclusion, our results suggest NCOA2 as a potential target of therapeutics against breast cancer.

Vitexin compound 1, a novel extraction from a Chinese herb, suppresses melanoma cell growth through DNA damage by increasing ROS levels

BACKGROUND

Vitex negundo L (Verbenaceae) is an aromatic shrub that is abundant in Asian countries. A series of compounds from Vitex negundo have been used in traditional Chinese medicine for the treatment of various diseases. Cutaneous melanoma is one of the most aggressive malignancies. A significant feature of melanoma is its resistance to traditional chemotherapy and radiotherapy; therefore, there is an urgent need to develop novel treatments for melanoma.

METHODS

We first examined the effects of VB1 (vitexin compound 1) on cell viability by CCK-8 (cell counting kit) and Colony Formation Assay; And then, we analyzed the apoptosis and cell cycle by flow cytometry, verified apoptosis by Immunoblotting. The in vivo effect of VB1 was evaluated in xenograft mouse model. Potential mechanisms of VB1's antitumor effects were explored by RNA sequencing and the key differential expression genes were validated by real-time quantitative PCR. Finally, the intracellular reactive oxygen species (ROS) level was detected by flow cytometry, and the DNA damage was revealed by Immunofluorescence and Immunoblotting.

RESULTS

In this study, we show that VB1, which is a compound purified from the seed of the Chinese herb Vitex negundo, blocks melanoma cells growth in vitro and in vivo, arrests the cell cycle in G2/M phase and induces apoptosis in melanoma cell lines, whereas the effects are not significantly observed in normal cells. To study the details of VB1, we analyzed the alteration of gene expression profiles after treatment with VB1 in melanoma cells. The findings showed that VB1 can affect various pathways, including p53, apoptosis and the cell cycle pathway, in a variety of melanoma cell lines. Furthermore, we confirmed that VB1 restored the P53 pathway protein level, and then we demonstrated that VB1 significantly induced the accumulation of ROS, which resulted in DNA damage in melanoma cell lines. Interestingly, our results showed that VB1 also increased the ROS levels in BRAFi (BRAF inhibitor)-resistant melanoma cells, leading to DNA cytotoxicity, which caused G2/M phase arrest and apoptosis.

CONCLUSIONS

Taken together, our findings indicate that vitexin compound 1 might be a promising therapeutic Chinese medicine for melanoma treatment regardless of BRAFi resistance.

Enzalutamide therapy for advanced prostate cancer: efficacy, resistance and beyond

The androgen receptor drives the growth of metastatic castration-resistant prostate cancer. This has led to the development of multiple novel drugs targeting this hormone-regulated transcription factor, such as enzalutamide – a potent androgen receptor antagonist. Despite the plethora of possible treatment options, the absolute survival benefit of each treatment separately is limited to a few months. Therefore, current research efforts are directed to determine the optimal sequence of therapies, discover novel drugs effective in metastatic castration-resistant prostate cancer and define patient subpopulations that ultimately benefit from these treatments. Molecular studies provide evidence on which pathways mediate treatment resistance and may lead to improved treatment for metastatic castration-resistant prostate cancer. This review provides, firstly a concise overview of the clinical development, use and effectiveness of enzalutamide in the treatment of advanced prostate cancer, secondly it describes translational research addressing enzalutamide response vs resistance and lastly highlights novel potential treatment strategies in the enzalutamide-resistant setting.

The oncogenic roles of nuclear receptor coactivator 1 in human esophageal carcinoma

Nuclear receptor coactivator 1 (NCOA1) plays crucial roles in the regulation of gene expression mediated by a wide spectrum of steroid receptors such as androgen receptor (AR), estrogen receptor α (ER α), and estrogen receptor β (ER β). Therefore, dysregulations of NCOA1 have been found in a variety of cancer types. However, the clinical relevance and the functional roles of NCOA1 in human esophageal squamous cell carcinoma (ESCC) are less known. We found in this study that elevated levels of NCOA1 protein and/or mRNA as well as amplification of the NCOA1 gene occur in human ESCC. Elevated levels of NCOA1 due to these dysregulations were not only associated with more aggressive clinic-pathologic parameters but also poorer survival. Results from multiple cohorts of ESCC patients strongly suggest that the levels of NCOA1 could serve as an independent predictor of overall survival. In addition, silencing NCOA1 in ESCC cells remarkably decreased proliferation, migration, and invasion. These findings not only indicate that NCOA1 plays important roles in human ESCC but the levels of NCOA1 also could serve as a potential prognostic biomarker of ESCC and targeting NCOA1 could be an efficacious strategy in ESCC treatment.

Steroid Receptor Coactivator-2 Controls the Pentose Phosphate Pathway through RPIA in Human Endometrial Cancer Cells

Steroid receptor coactivator-2 (SRC-2) is a transcriptional coregulator that modulates the activity of many transcription factors. Levels of SRC-2 are elevated in endometrial biopsies from polycystic ovary syndrome patients, a population predisposed to endometrial cancer (EC). Increased expression of SRC-2 is also detected in neoplastic endometrium suggesting a causal link between elevated SRC-2 expression and the emergence of endometrial disorders that can lead to cancer. Here, we reveal that SRC-2 knockdown reduces EC cell proliferation and anchorage-independence. Additionally, SRC-2 is required to maintain cellular glycolytic capacity and oxidative phosphorylation, processes essential for EC cell proliferation. Importantly, SRC-2 is critical for the normal performance of the pentose phosphate pathway (PPP). Perturbation of the PPP due to loss of SRC-2 expression may result from the depletion of ribose-5-P isomerase (RPIA), a key enzyme of the PPP. As with SRC-2, RPIA knockdown reduces EC cell proliferation, which is accompanied by a decrease in glycolytic capacity and oxidative phosphorylation. Glucose metabolite tracking experiments confirmed that knockdown of SRC-2 and RPIA downregulates the metabolic rate of both glycolysis and the PPP, highlighting a novel regulatory cross-talk between glycolysis and the PPP modulated by SRC-2.

Bufalin suppresses endometriosis progression by inducing pyroptosis and apoptosis

The steroid receptor coactivator (SRC)-1 isoform/estrogen receptor (ER)-β axis has an essential role in endometriosis progression. In this context, therefore, bufalin was employed as a 'tool compound' to evaluate inhibitors of SRC in alternative endometriosis treatment. Bufalin effectively suppressed the growth of primary human endometrial stroma cells isolated from endometriosis patients compared to women without endometriosis and immortalized human endometrial epithelial and stromal cells expressing the SRC-1 isoform compared to their parental cells in vitroIn vivo, compared to the vehicle, bufalin treatment significantly suppressed the growth of endometriotic lesions in mice with surgically induced endometriosis because bufalin disrupted the functional axis of SRC-1 isoform/ERβ by increasing SRC-1 isoform protein stability, hyperactivating the transcriptional activity of the SRC-1 isoform and degrading the ERβ protein by proteasome 26S subunit, non-ATPase 2 in endometriotic lesions. Bufalin treatment elevated the apoptosis signaling in epithelial cells of endometriotic lesions. In stromal cells of endometriotic lesions, bufalin treatment increased the levels of pyroptosis markers (caspase 1 and the active form of interleukin 1β) and reduced proliferation. In addition, bufalin treatment increased the expression levels of endoplasmic reticulum-stress (ERS) markers (PKR-like ER kinase, protein disulfide isomerase and binding immunoglobulin) in endometriotic lesions. Collectively, the bufalin-induced disruption of the SRC-1 isoform/ERβ axis might induce apoptosis, pyroptosis and ERS signaling in endometriotic lesions, causing the suppression of endometriosis. Therefore, future generations of SRC-modulators could be employed as an alternative medical approach for endometriosis treatment.

Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive breast cancer

Alterations in both cell metabolism and transcriptional programs are hallmarks of cancer that sustain rapid proliferation and metastasis 1 . However, the mechanisms that control the interaction between metabolic reprogramming and transcriptional regulation remain unclear. Here we show that the metabolic enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) regulates transcriptional reprogramming by activating the oncogenic steroid receptor coactivator-3 (SRC-3). We used a kinome-wide RNA interference-based screening method to identify potential kinases that modulate the intrinsic SRC-3 transcriptional response. PFKFB4, a regulatory enzyme that synthesizes a potent stimulator of glycolysis 2 , is found to be a robust stimulator of SRC-3 that coregulates oestrogen receptor. PFKFB4 phosphorylates SRC-3 at serine 857 and enhances its transcriptional activity, whereas either suppression of PFKFB4 or ectopic expression of a phosphorylation-deficient Ser857Ala mutant SRC-3 abolishes the SRC-3-mediated transcriptional output. Functionally, PFKFB4-driven SRC-3 activation drives glucose flux towards the pentose phosphate pathway and enables purine synthesis by transcriptionally upregulating the expression of the enzyme transketolase. In addition, the two enzymes adenosine monophosphate deaminase-1 (AMPD1) and xanthine dehydrogenase (XDH), which are involved in purine metabolism, were identified as SRC-3 targets that may or may not be directly involved in purine synthesis. Mechanistically, phosphorylation of SRC-3 at Ser857 increases its interaction with the transcription factor ATF4 by stabilizing the recruitment of SRC-3 and ATF4 to target gene promoters. Ablation of SRC-3 or PFKFB4 suppresses breast tumour growth in mice and prevents metastasis to the lung from an orthotopic setting, as does Ser857Ala-mutant SRC-3. PFKFB4 and phosphorylated SRC-3 levels are increased and correlate in oestrogen receptor-positive tumours, whereas, in patients with the basal subtype, PFKFB4 and SRC-3 drive a common protein signature that correlates with the poor survival of patients with breast cancer. These findings suggest that the Warburg pathway enzyme PFKFB4 acts as a molecular fulcrum that couples sugar metabolism to transcriptional activation by stimulating SRC-3 to promote aggressive metastatic tumours.

USP15-dependent lysosomal pathway controls p53-R175H turnover in ovarian cancer cells

Gain-of-function p53 mutants such as p53-R175H form stable aggregates that accumulate in cells and play important roles in cancer progression. Selective degradation of gain-of-function p53 mutants has emerged as a highly attractive therapeutic strategy to target cancer cells harboring specific p53 mutations. We identified a small molecule called MCB-613 to cause rapid ubiquitination, nuclear export, and degradation of p53-R175H through a lysosome-mediated pathway, leading to catastrophic cancer cell death. In contrast to its effect on the p53-R175H mutant, MCB-613 causes slight stabilization of p53-WT and has weaker effects on other p53 gain-of-function mutants. Using state-of-the-art genetic and chemical approaches, we identified the deubiquitinase USP15 as the mediator of MCB-613's effect on p53-R175H, and established USP15 as a selective upstream regulator of p53-R175H in ovarian cancer cells. These results confirm that distinct pathways regulate the turnover of p53-WT and the different p53 mutants and open new opportunities to selectively target them.

Hyperactivation of nuclear receptor coactivators induces PERK-dependent cell death

Nuclear receptor coactivators (NCOAs) function as coactivators for nuclear receptors as well as several other transcription factors and potentiate their transcriptional activity. NCOAs play an important role in biology of hormone-dependent and -independent cancers. MCB-613 is a recently described, small molecule stimulator of NCOAs and anti-neoplastic compound that leads to the death of tumour cells due to increased cellular stress. In the present study we investigated the molecular mechanism of MCB-613-induced cell death. We report that absence of NCOA3 leads to compromised activation of PERK signalling pathway during unfolded protein response (UPR). We found that chemical and genetic inhibition of NCOA3 attenuated the expression of PERK at mRNA and protein level. We show that loss of NCOA3 renders cells hypersensitive to UPR induced cell death. Our results show that MCB-613 induced cell death is attenuated in NCOA3 knockout HeLa cells and MCB-613 leads to enhanced PERK signalling in wild-type HeLa cells. The knockdown of PERK provides resistance to MCB-613 mediated cell death while knockdown of XBP1 and ATF6 have no such effect. Our results suggest that hyperstimulation of NCOA3 by MCB-613 induces cell death by evoking constitutive PERK signalling. Taken together our results point to NCOA3 as an important determinant in regulating cell fate during ER stress, with too little and too much NCOA3 both producing deleterious effects.

The binding landscape of a partially-selective isopeptidase inhibitor with potent pro-death activity, based on the bis(arylidene)cyclohexanone scaffold

Diaryldienone derivatives with accessible β-carbons show strong anti-neoplastic properties, related to their ability to make covalent adducts with free thiols by Michael addition, and low toxicity in vivo. Accumulation of poly-ubiquitylated proteins, activation of the unfolded protein response (UPR) and induction of cell death are universal hallmarks of their activities. These compounds have been characterized as inhibitors of isopeptidases, a family of cysteine-proteases, which de-conjugate ubiquitin and ubiquitin-like proteins from their targets. However, it is unclear whether they can also react with additional proteins. In this work, we utilized the biotin-conjugated diaryldienone-derivative named 2c, as a bait to purify novel cellular targets of these small molecules. Proteomic analyses have unveiled that, in addition to isopeptidases, these inhibitors can form stable covalent adducts with different intracellular proteins, thus potentially impacting on multiple functions of the cells, from cytoskeletal organization to metabolism. These widespread activities can explain the ability of diaryldienone derivatives to efficiently trigger different cell death pathways.

PDZ binding kinase (PBK) is a theranostic target for nasopharyngeal carcinoma: driving tumor growth via ROS signaling and correlating with patient survival

Nasopharyngeal carcinoma (NPC) is well known as one of the most common malignancies in southern China and Southeast Asia. However, the mechanisms underlying NPC progression remain poorly understood. Herein, through overlapping the differentially expressed genes from 3 microarray data sets with the human kinome, we identified PBK, a serine-threonine kinase, is highly upregulated and has not been intensively investigated in NPC. PBK was required for malignant phenotypes of NPC, as PBK depletion by RNAi and inhibition by specific inhibitor HI-TOPK-032 obviously reduced cell proliferation and xenograft tumor growth in mice. Moreover, we determined that targeting PBK could accelerate apoptosis by inducing ROS that activates JNK/p38 signaling pathway. In NPC patients, elevated PBK expression in primary tumor positively correlated to clinical severity such as advanced T stage, high death risk and disease progression, and it could serve as an unfavorable independent indicator of overall survival and disease-free survival. Altogether, our results indicate that PBK is a novel significant regulator of NPC progression and a potential therapeutic target for NPC patients.

Coregulator profiling of the glucocorticoid receptor in lymphoid malignancies

Coregulators cooperate with nuclear receptors, such as the glucocorticoid receptor (GR), to enhance or repress transcription. These regulatory proteins are implicated in cancer, yet, their role in lymphoid malignancies, including multiple myeloma (MM) and acute lymphoblastic leukemia (ALL), is largely unknown. Here, we report the use and extension of the microarray assay for real-time nuclear receptor coregulator interactions (MARCoNI) technology to detect coregulator associations with endogenous GR in cell lysates. We use MARCoNI to determine the GR coregulator profile of glucocorticoid-sensitive (MM and ALL) and glucocorticoid-resistant (ALL) cells, and identify common and unique coregulators for different cell line comparisons. Overall, we identify SRC-1/2/3, PGC-1α, RIP140 and DAX-1 as the strongest interacting coregulators of GR in MM and ALL cells and show that the interaction strength does not correlate with GR protein levels. Lastly, as a step towards patient samples, we determine the GR coregulator profile of peripheral blood mononuclear cells. We profile the interactions between GR and coregulators in MM and ALL cells and suggest to further explore the GR coregulator profile in hematological patient samples.

Challenges in Ras therapeutics in pancreatic cancer

Pancreatic cancer is considered among the most aggressive and the least curable of all human malignancies. It is usually characterized by multiple aberrations in tumor suppressor genes and oncogenes, most notably activating mutations in KRAS. This review examines the various attempts that have been made to inhibit Kras and its downstream signaling pathways in pancreatic cancer with an emphasis on challenges related to clinical trials. Attempts include preventing the localization of Ras protein to the plasma membrane, inhibiting downstream oncogenic signaling by targeting Kras effectors such as MEK1/2, Erk1/2 or Akt singly or in combination, and directly inhibiting Kras protein. Most clinical trials have focused on inhibiting downstream effector pathways and clinical benefit has been limited due to compensatory mechanisms and toxicity associated with small therapeutic windows. Additionally, genetic screens have been conducted to identify gene or genes that could provide therapeutic vulnerabilities in mutant KRAS cells and provide a way to target mutant Kras protein only. We also discuss how potentially transforming clinical trials have failed in the past and what new strategies are on-going in clinical trials for pancreas cancer. For long-term success in targeting Kras, future efforts should focus on combinatorial strategies to more effectively block Kras pathways at multiple points, and improve translational application of pre-clinical data to the clinic.

Menthol evokes Ca2+ signals and induces oxidative stress independently of the presence of TRPM8 (menthol) receptor in cancer cells

Menthol is a naturally occurring monoterpene alcohol possessing remarkable biological properties including antipruritic, analgesic, antiseptic, anti-inflammatory and cooling effects. Here, we examined the menthol-evoked Ca²⁺ signals in breast and prostate cancer cell lines. The effect of menthol (50–500 µM) was predicted to be mediated by the transient receptor potential ion channel melastatin subtype 8 (TRPM8). However, the intensity of menthol-evoked Ca²⁺ signals did not correlate with the expression levels of TRPM8 in breast and prostate cancer cells indicating a TRPM8-independent signaling pathway. Menthol-evoked Ca²⁺ signals were analyzed in detail in Du 145 prostate cancer cells, as well as in CRISPR/Cas9 TRPM8-knockout Du 145 cells. Menthol (500 µM) induced Ca²⁺ oscillations in both cell lines, thus independent of TRPM8, which were however dependent on the production of inositol trisphosphate. Results based on pharmacological tools point to an involvement of the purinergic pathway in menthol-evoked Ca²⁺ responses. Finally, menthol (50–500 µM) decreased cell viability and induced oxidative stress independently of the presence of TRPM8 channels, despite that temperature-evoked TRPM8-mediated inward currents were significantly decreased in TRPM8-knockout Du 145 cells compared to wild type Du 145 cells.

Targeting SRC Coactivators Blocks the Tumor-Initiating Capacity of Cancer Stem-like Cells

Tumor-initiating cells (TIC) represent cancer stem-like cell (CSC) subpopulations within tumors that are thought to give rise to recurrent cancer after therapy. Identifying key regulators of TIC/CSC maintenance is essential for the development of therapeutics designed to limit recurrence. The steroid receptor coactivator 3 (SRC-3) is overexpressed in a wide range of cancers, driving tumor initiation, cell proliferation, and metastasis. Here we report that SRC-3 supports the TIC/CSC state and induces an epithelial-to-mesenchymal transition (EMT) by driving expression of the master EMT regulators and stem cell markers. We also show that inhibition of SRC-3 and SRC-1 with SI-2, a second-generation SRC-3/SRC-1 small-molecule inhibitor, targets the CSC/TIC population both in vitro and in vivo Collectively, these results identify SRC coactivators as regulators of stem-like capacity in cancer cells and that these coactivators can serve as potential therapeutic targets to prevent the recurrence of cancer. Cancer Res; 77(16); 4293-304. ©2017 AACR.