Synthesis and activity of new aryl- and heteroaryl-substituted pyrazole inhibitors of the transforming growth factor-beta type I receptor kinase domain

Transforming growth factor-β micro-environment mediated immune cell functions in cervical cancer

Propensity to develop cervical cancer (CC) in human papilloma virus (HPV) infected individual could potentially involve the impaired immune functioning. Several stages of HPV surveillance by immune cells in tumor micro-environment (TME) is regulated mainly by transforming growth factor-beta (TGF-β) and is crucial for the establishment of CC. The role of TGF-β in the initiation and progression of CC is very complex and involve different suppressor of mothers against decapentaplegic homolog (SMAD) dependent and SMAD independent signaling mechanism(s). This review summarizes the handling of HPV by immune cells such as T lymphocytes, B lymphocytes, natural killer cells (NK), dendritic cells (DC), monocytes, macrophages, myeloid derived suppressor cells (MDSC) and their regulation by TGF-β. The hijack mechanisms adapted by HPV to evade this surveillance process is discussed. Biomarkers indicating the stages of CC and immune checkpoints that can be targeted for improved outcome are included for immune-based theragnostics. This review also addresses the direct actions of TGF-β on CC cells and tumor/immune cell interactions. Therapies focused on targeting TGF-β using small molecule inhibitors, monoclonal antibodies and TGF-β chimeric antigen receptor (CAR)T cells are collated to understand the current strategies related to TGF-β in the management of CC.

Systematic computational strategies for identifying protein targets and lead discovery

Computational algorithms and tools have retrenched the drug discovery and development timeline. The applicability of computational approaches has gained immense relevance owing to the dramatic surge in the structural information of biomacromolecules and their heteromolecular complexes. Computational methods are now extensively used in identifying new protein targets, druggability assessment, pharmacophore mapping, molecular docking, the virtual screening of lead molecules, bioactivity prediction, molecular dynamics of protein-ligand complexes, affinity prediction, and for designing better ligands. Herein, we provide an overview of salient components of recently reported computational drug-discovery workflows that includes algorithms, tools, and databases for protein target identification and optimized ligand selection.

Advances in the discovery of activin receptor-like kinase 5 (ALK5) inhibitors

Activin receptor‑like kinase-5 (ALK5) is an outstanding member of the transforming growth factor-β (TGF-β) family. (TGF-β) signaling pathway integrates pleiotropic proteins that regulate various cellular processes such as growth, proliferation, and differentiation. Dysregulation within the signaling pathway can cause variety of diseases, such as fibrosis, cardiovascular disease, and especially cancer, rendering ALK5 a potential drug target. Hence, various small molecules have been designed and synthesized as potent ALK5 inhibitors. In this review, we shed light on the current ATP-competitive inhibitors of ALK5 through diverse heterocyclic based scaffolds that are in clinical or pre-clinical phases of development. Moreover, we focused on the binding interactions of the compounds to the ATP binding site and the structure-activity relationship (SAR) of each scaffold, revealing new scopes for designing novel candidates with enhanced selectivity and metabolic profiles.

Drug Repositioning Using Computer-aided Drug Design (CADD)

Drug repositioning is a method of using authorized drugs for other unusually complex diseases. Compared to new drug development, this method is fast, low in cost, and effective. Through the use of outstanding bioinformatics tools, such as computer-aided drug design (CADD), computer strategies play a vital role in the re-transformation of drugs. The use of CADD's special strategy for target-based drug reuse is the most promising method, and its realization rate is high. In this review article, we have particularly focused on understanding the various technologies of CADD and the use of computer-aided drug design for target-based drug reuse, taking COVID-19 and cancer as examples. Finally, it is concluded that CADD technology is accelerating the development of repurposed drugs due to its many advantages, and there are many facts to prove that the new ligand-targeting strategy is a beneficial method and that it will gain momentum with the development of technology.

Heterocycles in Breast Cancer Treatment: The Use of Pyrazole Derivatives

Among the aromatic heterocycle rings, pyrazole -a five-membered ring with two adjacent nitrogen atoms in its structure has been postulated as a potent candidate in the pharmacological context. This moiety is an interesting therapeutic target covering a broad spectrum of biological activities due to its presence in many natural substances. Hence, the potential of the pyrazole derivatives as antitumor agents has been explored in many investigations, showing promising results in some cases. In this sense, breast cancer, which is already the leading cause of cancer mortality in women in some countries, has been the topic selected for this review, which covers a range of different research from the earliest studies published in 2003 to the most recent ones in 2021.

Small Molecule Inhibitors for Hepatocellular Carcinoma: Advances and Challenges

According to data provided by World Health Organization, hepatocellular carcinoma (HCC) is the sixth most common cause of deaths due to cancer worldwide. Tremendous progress has been achieved over the last 10 years developing novel agents for HCC treatment, including small-molecule kinase inhibitors. Several small molecule inhibitors currently form the core of HCC treatment due to their versatility since they would be more easily absorbed and have higher oral bioavailability, thus easier to formulate and administer to patients. In addition, they can be altered structurally to have greater volumes of distribution, allowing them to block extravascular molecular targets and to accumulate in a high concentration in the tumor microenvironment. Moreover, they can be designed to have shortened half-lives to control for immune-related adverse events. Most importantly, they would spare patients, healthcare institutions, and society as a whole from the burden of high drug costs. The present review provides an overview of the pharmaceutical compounds that are licensed for HCC treatment and other emerging compounds that are still investigated in preclinical and clinical trials. These molecules are targeting different molecular targets and pathways that are proven to be involved in the pathogenesis of the disease.

Latent TGFβ-binding proteins 1 and 3 protect the larval zebrafish outflow tract from aneurysmal dilatation

Aortic root aneurysm is a common cause of morbidity and mortality in Loeys-Dietz and Marfan syndromes, where perturbations in transforming growth factor beta (TGFβ) signaling play a causal or contributory role, respectively. Despite the advantages of cross-species disease modeling, animal models of aortic root aneurysm are largely restricted to genetically engineered mice. Here, we report that zebrafish devoid of the genes encoding latent-transforming growth factor beta-binding protein 1 and 3 (ltbp1 and ltbp3, respectively) develop rapid and severe aneurysm of the outflow tract (OFT), the aortic root equivalent. Similar to syndromic aneurysm tissue, the distended OFTs display evidence for paradoxical hyperactivated TGFβ signaling. RNA-sequencing revealed significant overlap between the molecular signatures of disease tissue from mutant zebrafish and a mouse model of Marfan syndrome. Moreover, chemical inhibition of TGFβ signaling in wild-type animals phenocopied mutants but chemical activation did not, demonstrating that TGFβ signaling is protective against aneurysm. Human relevance is supported by recent studies implicating genetic lesions in LTBP3 and, potentially, LTBP1 as heritable causes of aortic root aneurysm. Ultimately, our data demonstrate that zebrafish can now be leveraged to interrogate thoracic aneurysmal disease and identify novel lead compounds through small-molecule suppressor screens. This article has an associated First Person interview with the first author of the paper.

Radiosensitizing effect of galunisertib, a TGF-ß receptor I inhibitor, on head and neck squamous cell carcinoma in vitro

Background. Resistance to radiation therapy poses a major clinical problem for patients suffering from head and neck squamous cell carcinoma (HNSCC). Transforming growth factor ß (TGF-ß) has emerged as a potential target. This study aimed to investigate the radiosensitizing effect of galunisertib, a small molecule TGF-ß receptor kinase I inhibitor, on HNSCC cells in vitro. Methods. Three HNSCC cell lines were treated with galunisertib alone, or in combination with radiation. Of those three cell lines, one has a known inactivating mutation of the TGF-ß pathway (Cal27), one has a TGF-ß pathway deficiency (FaDu) and one has no known alteration (SCC-25). The effect on metabolic activity was evaluated by a resazurin-based reduction assay. Cell migration was evaluated by wound-healing assay, clonogenic survival by colony formation assay and cell cycle by FACS analysis. Results. Galunisertib reduced metabolic activity in FaDu, increased in SCC-25 and had no effect on CAL27. Migration was significantly reduced by galunisertib in all three cell lines and showed additive effects in combination with radiation in CAL27 and SCC-25. Colony-forming capabilities were reduced in SCC-25 by galunisertib and also showed an additive effect with adjuvant radiation treatment. Cell cycle analysis showed a reduction of cells in G₁ phase in response to galunisertib treatment. Conclusion. Our results indicate a potential antineoplastic effect of galunisertib in HNSCC with intact TGF-ß signaling in combination with radiation.

Present and future challenges in therapeutic designing using computational approaches

Currently, various computational methods are being used for the purpose of therapeutic design. The advent of the Coronavirus disease-2019 (COVID-19) pandemic has created a lot of problems due to which the development of effective treatment options is urgently needed. Computational intelligence is used in the control, prevention, prediction, diagnosis, and treatment of the disease. Several important drug targets have been identified in severe acute respiratory syndrome-Coronavirus-2 using in silico methods. Computer-aided drug design includes a variety of theoretical and computational approaches that are part of modern drug discovery. Advances in machine learning methods and their applications speed up the drug discovery process. Exploration of nucleic acid-based therapeutics is playing an important role in healthcare also. But a lot of challenges have also been seen that complicate the therapeutic design. Therefore, investigation of challenges associated with therapeutic design is important, and the present chapter is aimed to cover various therapeutic design approaches and challenges associated with them. Moreover, the role of computational strategies in the exploration of potential therapeutics against COVID-19 has been investigated.

EP3 Receptor Deficiency Improves Vascular Remodeling and Cognitive Impairment in Cerebral Small Vessel Disease

Aging and hypertension are major risk factors for cerebral small vessel disease (CSVD). Anti-hypertensive therapy has achieved effective; however, incomplete results in treating CSVD, suggesting the need for additional treatments. Targeting abnormal inflammatory responses has become a topic of research interest. Small artery remodeling is the main pathological feature of CSVD. Inhibition of the E-prostanoid 3 (EP3) receptor has been shown to attenuate vascular remodeling in peripheral organs; however, little is known about its role in CSVD. Therefore, we investigated whether the deletion of EP3 attenuates the development of CSVD in an animal model-- stroke-prone renovascular hypertensive rat (RHRsp). We found that the cerebral small arteries of RHRsp exhibited increased EP3 expression. Despite no alleviation of hypertension, the deletion of EP3 still attenuated the cerebral small artery remodeling of RHRsp, as evidenced by reduced overexpression of extracellular matrix (ECM) in the vessel. In vitro experiments indicated that EP3 deletion regulated the expression of ECM by downregulating TGF-β1/Smad signaling. Furthermore, the Morris water maze test and magnetic resonance test demonstrated that EP3 knockout attenuated cognitive impairment of the RHRsp, possibly through increased cerebral blood flow. Together, our results indicate that the deletion of EP3 attenuates vascular remodeling and vascular cognitive impairment induced by hypertension, and blockade of the EP3 receptor may be a promising strategy for the treatment of CSVD.

RNAseq of TGF-β receptor type I kinase-dependent genes in oral fibroblast exposed to milk

Background

Milk is a rich source of natural growth factors that may support oral tissue homeostasis and wound healing. We had shown earlier that blocking TGF-β receptor type I kinase with the inhibitor SB431542 abolished the expression of IL11 and other genes in human gingival fibroblasts exposed to the aqueous fraction of milk. Our aim was to identify the entire signature of TGF-β receptor type I kinase-dependent genes regulated by the aqueous fraction of human milk.

Result

RNAseq revealed 99 genes being strongly regulated by milk requiring activation of the SB431542-dependent TGF-β receptor type I kinase. Among the SB431542-dependent genes is IL11 but also cadherins, claudins, collagens, potassium channels, keratins, solute carrier family proteins, transcription factors, transmembrane proteins, tumor necrosis factor ligand superfamily members, and tetraspanin family members. When focusing on our candidate gene, we could identify D609 to suppress IL11 expression, independent of phospholipase C, sphinosine-1 phosphate synthesis, and Smad-3 phosphorylation and its nuclear translocation. In contrast, genistein and blocking phosphoinositide 3-kinases by wortmannin and LY294002 increased the milk-induced IL11 expression in gingival fibroblasts.

Conclusion

Taken together, our data revealed TGF-β receptor type I kinase signaling to cause major changes of the genetic signature of gingival fibroblasts exposed to aqueous fraction of human milk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01913-5.

Appraisal of the Role of In silico Methods in Pyrazole Based Drug Design

Pyrazole and its derivatives are a pharmacologically and significantly active scaffolds that have innumerable physiological and pharmacological activities. They can be very good targets for the discovery of novel anti-bacterial, anti-cancer, anti-inflammatory, anti-fungal, anti-tubercular, antiviral, antioxidant, antidepressant, anti-convulsant and neuroprotective drugs. This review focuses on the importance of in silico manipulations of pyrazole and its derivatives for medicinal chemistry. The authors have discussed currently available information on the use of computational techniques like molecular docking, structure-based virtual screening (SBVS), molecular dynamics (MD) simulations, quantitative structure activity relationship (QSAR), comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) to drug design using pyrazole moieties. Pyrazole based drug design is mainly dependent on the integration of experimental and computational approaches. The authors feel that more studies need to be done to fully explore the pharmacological potential of the pyrazole moiety and in silico method can be of great help.

From Proteomic Mapping to Invasion-Metastasis-Cascade Systemic Biomarkering and Targeted Drugging of Mutant BRAF-Dependent Human Cutaneous Melanomagenesis

Simple Summary

Despite the recent advances in human malignancy therapy, metastasis and chemoresistance remain the principal causes of cancer-derived deaths. Given the fatal forms of cutaneous metastatic melanoma, we herein employed primary (WM115) and metastatic (WM266-4) melanoma cells, both obtained from the same patient, to identify novel biomarkers and therapeutic agents. Through state-of-the-art technologies including deep proteome landscaping, immunofluorescence phenotyping, and drug toxicity screening, we were able to describe new molecular programs, oncogenic drivers, and drug regimens, controlling the invasion-metastasis cascade during BRAF^V600D-dependent melanomagenesis. It proved that proteomic navigation could foster the development of systemic biomarkering and targeted drugging for successful treatment of advanced disease.

Abstract

Melanoma is classified among the most notoriously aggressive human cancers. Despite the recent progress, due to its propensity for metastasis and resistance to therapy, novel biomarkers and oncogenic molecular drivers need to be promptly identified for metastatic melanoma. Hence, by employing nano liquid chromatography-tandem mass spectrometry deep proteomics technology, advanced bioinformatics algorithms, immunofluorescence, western blotting, wound healing protocols, molecular modeling programs, and MTT assays, we comparatively examined the respective proteomic contents of WM115 primary (n = 3955 proteins) and WM266-4 metastatic (n = 6681 proteins) melanoma cells. It proved that WM115 and WM266-4 cells have engaged hybrid epithelial-to-mesenchymal transition/mesenchymal-to-epithelial transition states, with TGF-β controlling their motility in vitro. They are characterized by different signatures of SOX-dependent neural crest-like stemness and distinct architectures of the cytoskeleton network. Multiple signaling pathways have already been activated from the primary melanoma stage, whereas HIF1α, the major hypoxia-inducible factor, can be exclusively observed in metastatic melanoma cells. Invasion-metastasis cascade-specific sub-routines of activated Caspase-3-triggered apoptosis and LC3B-II-dependent constitutive autophagy were also unveiled. Importantly, WM115 and WM266-4 cells exhibited diverse drug response profiles, with epirubicin holding considerable promise as a beneficial drug for metastatic melanoma clinical management. It is the proteome navigation that enables systemic biomarkering and targeted drugging to open new therapeutic windows for advanced disease.

A Systematic Review of Glioblastoma-Targeted Therapies in Phases II, III, IV Clinical Trials

Glioblastoma (GBM), the most frequent and aggressive glial tumor, is currently treated as first line by the Stupp protocol, which combines, after surgery, radiotherapy and chemotherapy. For recurrent GBM, in absence of standard treatment or available clinical trials, various protocols including cytotoxic drugs and/or bevacizumab are currently applied. Despite these heavy treatments, the mean overall survival of patients is under 18 months. Many clinical studies are underway. Based on clinicaltrials.org and conducted up to 1 April 2020, this review lists, not only main, but all targeted therapies in phases II-IV of 257 clinical trials on adults with newly diagnosed or recurrent GBMs for the last twenty years. It does not involve targeted immunotherapies and therapies targeting tumor cell metabolism, that are well documented in other reviews. Without surprise, the most frequently reported drugs are those targeting (i) EGFR (40 clinical trials), and more generally tyrosine kinase receptors (85 clinical trials) and (ii) VEGF/VEGFR (75 clinical trials of which 53 involving bevacizumab). But many other targets and drugs are of interest. They are all listed and thoroughly described, on an one-on-one basis, in four sections related to targeting (i) GBM stem cells and stem cell pathways, (ii) the growth autonomy and migration, (iii) the cell cycle and the escape to cell death, (iv) and angiogenesis.

The Epithelial-to-Mesenchymal Transition-Like Process Induced by TGF-β1 Enhances Rubella Virus Binding and Infection in A549 Cells via the Smad Pathway

Virus–host cell interactions in rubella virus (RuV) are of great interest in current research in the field, as their mechanism is not yet well understood. By hypothesizing that the epithelial-to-mesenchymal transition (EMT) may play a role in RuV infection, this study aimed to investigate the influence of TGF-β1-induced EMT of human lung epithelial A549 cells on the infectivity of RuV. A549 cells were cultured and treated with TGF-β1 for 1 to 2 days prior to virus infection (with a clinical strain). Viral infectivity was determined by flow cytometry analysis of cells harvested at 24 and 48 h post-infection (hpi) and by titration of supernatants collected at 48 hpi. The results showed that the percentages of the TGF-β1-treated A549 cells that were positive for RuV were at least twofold higher than those of the control, and the viral progeny titers in the supernatants collected at 48 hpi were significantly higher in the treatment group than in the control group. In addition, the virus binding assay showed a strong increase (more than threefold) in the percentages of RuV-positive cells, as determined by flow cytometry analysis and further confirmed by real-time PCR. Such an enhancement effect on RuV infectivity was abolished using LY364947 or SB431542, inhibitors of the TGF-β/Smad signaling pathway. The findings suggest that the TGF-β1-induced EMT-like process enhances RuV binding and infection in A549 cells via the Smad pathway. Further studies are necessary to identify possible proteins that facilitate viral binding and entry into treated cells.

Dual β-Catenin and γ-Catenin Loss in Hepatocytes Impacts Their Polarity through Altered Transforming Growth Factor-β and Hepatocyte Nuclear Factor 4α Signaling

Hepatocytes are highly polarized epithelia. Loss of hepatocyte polarity is associated with various liver diseases, including cholestasis. However, the molecular underpinnings of hepatocyte polarization remain poorly understood. Loss of β-catenin at adherens junctions is compensated by γ-catenin and dual loss of both catenins in double knockouts (DKOs) in mice liver leads to progressive intrahepatic cholestasis. However, the clinical relevance of this observation, and further phenotypic characterization of the phenotype, is important. Herein, simultaneous loss of β-catenin and γ-catenin was identified in a subset of liver samples from patients of progressive familial intrahepatic cholestasis and primary sclerosing cholangitis. Hepatocytes in DKO mice exhibited defects in apical-basolateral localization of polarity proteins, impaired bile canaliculi formation, and loss of microvilli. Loss of polarity in DKO livers manifested as epithelial-mesenchymal transition, increased hepatocyte proliferation, and suppression of hepatocyte differentiation, which was associated with up-regulation of transforming growth factor-β signaling and repression of hepatocyte nuclear factor 4α expression and activity. In conclusion, concomitant loss of the two catenins in the liver may play a pathogenic role in subsets of cholangiopathies. The findings also support a previously unknown role of β-catenin and γ-catenin in the maintenance of hepatocyte polarity. Improved understanding of the regulation of hepatocyte polarization processes by β-catenin and γ-catenin may potentially benefit development of new therapies for cholestasis.

Immune-Checkpoint Inhibitors Combinations in Metastatic NSCLC: New Options on the Horizon?

The therapeutic targeting of the programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) axis marked a milestone in the treatment of non-small cell lung cancer (NSCLC), leading to unprecedented response duration and long-term survival for a relevant subgroup of patients affected by non-oncogene-addicted, metastatic disease. However, the biological heterogeneity as well as the occurrence of innate/acquired resistance are well-known phenomena which significantly affect the therapeutic response to immunotherapy. To date, we are moving towards the second phase of the "immune-revolution", characterized by the advent of new immune-checkpoint inhibitors combinations, aiming to target the main resistance pathways and ultimately increase the number of NSCLC patients who may derive long-term clinical benefit from immunotherapy. In this review, we provide an updated and comprehensive overview of the main PD-1/PD-L1 inhibitors' combination approaches under clinical investigation in non-oncogene addicted, metastatic NSCLC patients, including checkpoints (other than CTLA-4) as well as "immune-metabolism" modulators, DNA repair pathway inhibitors, antiangiogenic agents, cytokines, and a new generation of vaccines, with the final aim of identifying the most promising options on the horizon.

TGFβ-Directed Therapeutics: 2020

The transforming growth factor-beta (TGFβ) pathway is essential during embryo development and in maintaining normal homeostasis. During malignancy, the TGFβ pathway is co-opted by the tumor to increase fibrotic stroma, to promote epithelial to mesenchymal transition increasing metastasis and producing an immune-suppressed microenvironment which protects the tumor from recognition by the immune system. Compelling preclinical data demonstrate the therapeutic potential of blocking TGFβ function in cancer. However, the TGFβ pathway cannot be described as a driver of malignant disease. Two small molecule kinase inhibitors which block the serine-threonine kinase activity of TGFβRI on TGFβRII, a pan-TGFβ neutralizing antibody, a TGFβ trap, a TGFβ antisense agent, an antibody which stabilizes the latent complex of TGFβ and a fusion protein which neutralizes TGFβ and binds PD-L1 are in clinical development. The challenge is how to most effectively incorporate blocking TGFβ activity alone and in combination with other therapeutics to improve treatment outcome.

Recent Advances in the Development of TGF-β Signaling Inhibitors for Anticancer Therapy

TGF-β is a multifunctional cytokine that plays an important role in both physiologic and pathologic processes, including cancer. Importantly, TGF-β has a dual role in tumorigenesis, acting as a tumor suppressor or a tumor promoter, depending on the stage of tumor development. The aberrantly upregulated production of TGF-β has been strongly implicated in tumor progression, angiogenesis, and metastasis, as well as immune evasion. Therefore, hyperactivated TGF-β signaling is considered a potential therapeutic target for cancer therapy. Numerous inhibitors of overactivated TGF-β signaling have been developed, and some of them are currently in clinical trials. This review focuses on the TGF-β signaling that contributes to tumor progression and immune evasion in the tumor microenvironment and presents recent achievements on TGF-β signaling inhibition as a single or combined therapeutic approach in cancer therapy.

Hypoxia-induced TGF-β-RBFOX2-ESRP1 axis regulates human MENA alternative splicing and promotes EMT in breast cancer

Hypoxic microenvironment heralds epithelial-mesenchymal transition (EMT), invasion and metastasis in solid tumors. Deregulation of alternative splicing (AS) of several cancer-associated genes has been instrumental in hypoxia-induced EMT. Our study in breast cancer unveils a previously unreported mechanism underlying hypoxia-mediated AS of hMENA, a crucial cytoskeleton remodeler during EMT. We report that the hypoxia-driven depletion of splicing regulator ESRP1 leads to skipping of hMENA exon 11a producing a pro-metastatic isoform, hMENAΔ11a. The transcriptional repression of ESRP1 is mediated by SLUG, which gets stimulated via hypoxia-driven TGF-β signaling. Interestingly, RBFOX2, an otherwise RNA-binding protein, is also found to transcriptionally repress ESRP1 while interacting with SLUG. Similar to SLUG, RBFOX2 gets upregulated under hypoxia via TGF-β signaling. Notably, we found that the exosomal delivery of TGF-β contributes to the elevation of TGF-β signaling under hypoxia. Moreover, our results show that in addition to hMENA, hypoxia-induced TGF-β signaling contributes to global changes in AS of genes associated with EMT. Overall, our findings reveal a new paradigm of hypoxia-driven AS regulation of hMENA and insinuate important implications in therapeutics targeting EMT.

Epithelial-Mesenchymal Transition Programs and Cancer Stem Cell Phenotypes: Mediators of Breast Cancer Therapy Resistance

Epithelial-mesenchymal transition (EMT) programs play essential functions in normal morphogenesis and organogenesis, including that occurring during mammary gland development and glandular regeneration. Historically, EMT programs were believed to reflect a loss of epithelial gene expression signatures and morphologies that give way to those associated with mesenchymal cells and their enhanced migratory and invasive behaviors. However, accumulating evidence now paints EMT programs as representing a spectrum of phenotypic behaviors that also serve to enhance cell survival, immune tolerance, and perhaps even metastatic dormancy. Equally important, the activation of EMT programs in transformed mammary epithelial cells not only enhances their acquisition of invasive and metastatic behaviors, but also expands their generation of chemoresistant breast cancer stem cells (BCSC). Importantly, the net effect of these events results in the appearance of recurrent metastatic lesions that remain refractory to the armamentarium of chemotherapies and targeted therapeutic agents deployed against advanced stage breast cancers. Here we review the molecular and cellular mechanisms that contribute to the pathophysiology of EMT programs in human breast cancers and how these events impact their "stemness" and acquisition of chemoresistant phenotypes.

Exercise rejuvenates quiescent skeletal muscle stem cells in old mice through restoration of Cyclin D1

Aging impairs tissue repair. This is pronounced in skeletal muscle, whose regeneration by muscle stem cells (MuSCs) is robust in young adult animals but inefficient in older organisms. Despite this functional decline, old MuSCs are amenable to rejuvenation through strategies that improve the systemic milieu, such as heterochronic parabiosis. One such strategy, exercise, has long been appreciated for its benefits on healthspan, but its effects on aged stem cell function in the context of tissue regeneration are incompletely understood. Here we show that exercise in the form of voluntary wheel running accelerates muscle repair in old animals and improves old MuSC function. Through transcriptional profiling and genetic studies, we discovered that the restoration of old MuSC activation ability hinges on restoration of Cyclin D1, whose expression declines with age in MuSCs. Pharmacologic studies revealed that Cyclin D1 maintains MuSC activation capacity by repressing TGFβ signaling. Taken together, these studies demonstrate that voluntary exercise is a practicable intervention for old MuSC rejuvenation. Furthermore, this work highlights the distinct role of Cyclin D1 in stem cell quiescence.

Phase 1b/2a study of galunisertib, a small molecule inhibitor of transforming growth factor-beta receptor I, in combination with standard temozolomide-based radiochemotherapy in patients with newly diagnosed malignant glioma

Purpose Galunisertib, a TGF-β inhibitor, has demonstrated antitumor effects in preclinical and radiographic responses in some patients with malignant glioma. This Phase 1b/2a trial investigated the clinical benefit of combining galunisertib with temozolomide-based radiochemotherapy (TMZ/RTX) in patients with newly diagnosed malignant glioma (NCT01220271). Methods This is an open-label, 2-arm Phase 1b/2a study (N = 56) of galunisertib (intermittent dosing: 14 days on/14 days off per cycle of 28 days) in combination with TMZ/RTX (n = 40), versus a control arm (TMZ/RTX, n = 16). The primary objective of Phase 1b was to determine the safe and tolerable Phase 2 dose of galunisertib. The primary objective of Phase 2a was to confirm the tolerability and pharmacodynamic profile of galunisertib with TMZ/RTX, and the secondary objectives included determining the efficacy and pharmacokinetic (PK) profile of galunisertib with TMZ/RTX in patients with glioblastoma. This study also characterized the changes in the major T-cell subsets during TMZ/RTX plus galunisertib treatment. Results In the Phase 2a study, efficacy results for patients treated with galunisertib plus TMZ/RTX or TMZ/RTX were: median overall survival (18.2 vs 17.9 months), median progression-free survival (7.6 vs 11.5 months), and disease control rate (80% [32/40] vs 56% [9/16] patients) respectively. PK profile of galunisertib plus TMZ/RTX regimen was consistent with previously published PK data of galunisertib. The overall safety profile across treatment arms was comparable. Conclusion No differences in efficacy, safety or pharmacokinetic variables were observed between the two treatment arms.

Sajedi R. Directed Blocking of TGF-β Receptor I Binding Site Using Tailored Peptide Segments to Inhibit its Signaling Pathway

BACKGROUND

TGF-β isoforms play crucial roles in diverse cellular processes. Therefore, targeting and inhibiting TGF-β signaling pathway provides a potential therapeutic opportunity. TGF-β isoforms bind and bring the receptors (TβRII and TβRI) together to form a signaling complex in an ordered manner.

OBJECTIVES

Herein, an antagonistic variant of TGF-β (AnTβ) has been designed and prepared to inhibit the formation of signaling complex and consequently its signaling pathway. This TGF-β homodimeric variant contains intact TβRII binding sites and blocked TβRI binding sites by substituting three peptide segments. So, AnTβ could only bind to TβRII, but prevent binding and recruitment of TβRI to form a signaling complex.

MATERIALS AND METHODS

A reliable model of AnTβ was built and refined using molecular dynamics (MD) simulation, followed by investigating the interactions of AnTβ with the receptors using in silico docking studies. After expression of disulfide-linked AnTβ in a SHuffle strain and purification of the protein using affinity chromatography, its biological activity was evaluated using Mink lung epithelial cells (Mvl Lu).

RESULTS

No meaningful significant changes in AnTβ structure were observed when compared with the native protein. Based on the docking analysis, AnTβ binds to TβRII similar to TGF-β and its binding to TβRI was diminished considerably which was consistent with our design purpose. Cell-based bioassay indicated that AnTβ could modulate TGF-β-induced cell growth inhibition.

CONCLUSIONS

Our analysis suggests that the antagonistic potency of AnTβ can be used as an anti-TGFβ signaling factor in the future perspectives.

Betaglycan (TβRIII) is a Key Factor in TGF-β2 Signaling in Prepubertal Rat Sertoli Cells

Transforming growth factor-βs (TGF-βs) signal after binding to the TGF-β receptors TβRI and TβRII. Recently, however, betaglycan (BG) was identified as an important co-receptor, especially for TGF-β2. Both proteins are involved in several testicular functions. Thus, we analyzed the importance of BG for TGF-β1/2 signaling in Sertoli cells with ELISAs, qRT-PCR, siRNA silencing and BrdU assays. TGF-β1 as well as TGF-β2 reduced shedding of membrane-bound BG (mBG), thus reducing the amount of soluble BG (sBG), which is often an antagonist to TGF-β signaling. Treatment of Sertoli cells with GM6001, a matrix metalloproteinases (MMP) inhibitor, also counteracted BG shedding, thus suggesting MMPs to be mainly involved in shedding. Interestingly, TGF-β2 but not TGF-β1 enhanced secretion of tissue inhibitor of metalloproteinases 3 (TIMP3), a potent inhibitor of MMPs. Furthermore, recombinant TIMP3 attenuated BG shedding. Co-stimulation with TIMP3 and TGF-β1 reduced phosphorylation of Smad3, while a combination of TIMP3/TGF-β2 increased it. Silencing of BG as well as TIMP3 reduced TGF-β2-induced phosphorylation of Smad2 and Smad3 significantly, once more highlighting the importance of BG for TGF-β2 signaling. In contrast, this effect was not observed with TIMP3/TGF-β1. Silencing of BG and TIMP3 decreased significantly Sertoli cell proliferation. Taken together, BG shedding serves a major role in TGF-β2 signaling in Sertoli cells.

P-glycoprotein (MDR1/ABCB1) controls brain accumulation and intestinal disposition of the novel TGF-β signaling pathway inhibitor galunisertib

Galunisertib (LY2157299), a promising small-molecule inhibitor of the transforming growth factor-beta (TGF-β) receptor, is currently in mono- and combination therapy trials for various cancers including glioblastoma, hepatocellular carcinoma and breast cancer. Using genetically modified mouse models, we investigated the roles of the multidrug efflux transporters ABCB1 and ABCG2, the OATP1A/1B uptake transporters and the drug-metabolizing CYP3A complex in galunisertib pharmacokinetics. In vitro, galunisertib was vigorously transported by human ABCB1, and moderately by mouse Abcg2. Orally administered galunisertib (20 mg/kg) was very rapidly absorbed. Galunisertib brain-to-plasma ratios were increased by ~24-fold in Abcb1a/1b^-/- and Abcb1a/1b;Abcg2^-/- mice compared to wild-type mice, but not in single Abcg2^-/- mice, whereas galunisertib oral availability was not markedly affected. However, recovery of galunisertib in the small intestinal lumen was strongly reduced in Abcb1a/1b^-/- and Abcb1a/1b;Abcg2^-/- mice. Oral coadministration of the ABCB1/ABCG2 inhibitor elacridar boosted galunisertib brain accumulation in wild-type mice to equal the levels seen in Abcb1a/1b;Abcg2^-/- mice. Oatp1a/1b deficiency did not alter oral galunisertib pharmacokinetics or liver distribution. Cyp3a^-/- mice showed a 1.9-fold higher plasma AUC_{0-1 hr} than wild-type mice, but this difference disappeared over 8 hr. Also, transgenic human CYP3A4 overexpression did not significantly alter oral galunisertib pharmacokinetics. Abcb1 thus markedly restricts galunisertib brain penetration and affects its intestinal disposition, possibly through biliary excretion. Elacridar coadministration could fully inhibit both processes, without causing acute toxicity. Moreover, mouse Cyp3a, but not human CYP3A4, may eliminate galunisertib at high plasma concentrations. These insights may help to guide the further clinical development and application of galunisertib.

Structure-based design generated novel hydroxamic acid based preferential HDAC6 lead inhibitor with on-target cytotoxic activity against primary choroid plexus carcinoma

Histone deacetylase 6 (HDAC6) is an attractive target for cancer therapeutic intervention. Selective HDAC6 inhibitors is important to minimise the side effects of pan inhibition. Thus, new class of hydroxamic acid-based derivatives were designed on structural basis to perform preferential activity against HDAC6 targeting solid tumours. Interestingly, 1-benzylbenzimidazole-2-thio-N-hydroxybutanamide 10a showed impressive preference with submicromolar potency against HDAC6 (IC₅₀ = 510 nM). 10a showed cytotoxic activity with interesting profile against CCHE-45 at (IC₅₀ = 112.76 µM) when compared to standard inhibitor Tubacin (IC₅₀ = 20 µM). Western blot analysis of acetylated-α-tubulin verified the HDAC6 inhibiting activity of 10a. Moreover, the insignificant difference in acetylated-α-tubulin induced by 10a and Tubacin implied the on-target cytotoxic activity of 10a. Docking of 10a in the binding site of HDAC6 attributed the activity of 10a to π-π stacking with the amino acids of the hydrophobic channel of HDAC6 and capture of zinc metal in bidentate fashion. The therapeutic usefulness besides the on-target activity may define 10a as an interesting safe-lead inhibitor for future development.

Combined Inhibition of TGF-β Signaling and the PD-L1 Immune Checkpoint Is Differentially Effective in Tumor Models

Antibodies blocking the programmed death-ligand 1 (PD-L1) have shown impressive and durable responses in clinical studies. However, this type of immunotherapy is only effective in a subset of patients and not sufficient for rejection of all tumor types. In this study, we explored in two mouse tumor models whether the antitumor effect could be enhanced by the combined blockade of PD-L1 and transforming growth factor-β (TGF-β), a potent immunosuppressive cytokine. The effect of anti-PD-L1 mouse monoclonal (mAb) and a TGF-β type I receptor small molecule kinase inhibitor (LY364947) was evaluated in the highly immunogenic mouse MC38 colon adenocarcinoma and the poorly immunogenic mouse KPC1 pancreatic tumor model. In the MC38 tumor model, LY364947 monotherapy did not show any antitumor effect, whereas treatment with anti-PD-L1 mAb significantly delayed tumor outgrowth. However, combination therapy showed the strongest therapeutic efficacy, resulting in improved long-term survival compared with anti-PD-L1 mAb monotherapy. This improved survival was associated with an increased influx of CD8⁺ T cells in the tumor microenvironment. In the KPC1 tumor model, LY364947 did not enhance the antitumor effect of anti-PD-L1 mAb. Despite this, delayed KPC1 tumor outgrowth was observed in the LY364947-treated group and this treatment led to a significant reduction of CD4⁺ T cells in the tumor microenvironment. Together, our data indicate that an additive anti-tumor response of dual targeting PD-L1 and TGF-β is dependent on the tumor model used, highlighting the importance of selecting appropriate cancer types, using in-depth analysis of the tumor microenvironment, which can benefit from combinatorial immunotherapy regimens.

eToxPred: a machine learning-based approach to estimate the toxicity of drug candidates

BACKGROUND

The efficiency of drug development defined as a number of successfully launched new pharmaceuticals normalized by financial investments has significantly declined. Nonetheless, recent advances in high-throughput experimental techniques and computational modeling promise reductions in the costs and development times required to bring new drugs to market. The prediction of toxicity of drug candidates is one of the important components of modern drug discovery.

RESULTS

In this work, we describe eToxPred, a new approach to reliably estimate the toxicity and synthetic accessibility of small organic compounds. eToxPred employs machine learning algorithms trained on molecular fingerprints to evaluate drug candidates. The performance is assessed against multiple datasets containing known drugs, potentially hazardous chemicals, natural products, and synthetic bioactive compounds. Encouragingly, eToxPred predicts the synthetic accessibility with the mean square error of only 4% and the toxicity with the accuracy of as high as 72%.

CONCLUSIONS

eToxPred can be incorporated into protocols to construct custom libraries for virtual screening in order to filter out those drug candidates that are potentially toxic or would be difficult to synthesize. It is freely available as a stand-alone software at https://github.com/pulimeng/etoxpred .

Development of novel therapeutics for glaucoma filtration surgery based on transforming growth factor-β receptor 1 inhibition

QSAR modeling with computer-aided drug design was used for the in silico development of novel therapeutics for glaucoma filtration surgery.

Medicinal chemistry of vicinal diaryl scaffold: A mini review

The privileged structures have been widely used as a valuable template in new drug discovery. 1,2-Diaryl or vicinal diaryl is a simple scaffold found in many drugs and naturally occurring compounds. From synthetic point of view, the vicinal diaryl derivatives are easily accessible due to their facile and expedient syntheses. These scaffolds have shown numerous interesting pharmacological activities against various diseases with lot of clinical potentials. This review aims to highlight the evidence of vicinal diaryl motif as a privileged scaffold in COX-2 inhibitors and CA-4 analogs.

Biemamides A-E, Inhibitors of the TGF-β Pathway That Block the Epithelial to Mesenchymal Transition

Screening of a marine natural products library for inhibitors of TGF-β revealed five pyrimidinedione derivatives, biemamides A-E (1-5). The structures were determined by 2D NMR and HRMS experiments; absolute configurations were established by advanced Marfey's analysis and ECD calculations. Biemamides A-E specifically inhibited in vitro TGF-β induced epithelial to mesenchymal transition in NMuMG cells. Additionally, using Caenorhabditis elegans, selected biemmamides were found to influence in vivo developmental processes related to body size regulation in a dose-dependent manner.

Pre-neoplastic pancreas cells enter a partially mesenchymal state following transient TGF-β exposure

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease and a major health problem in the United States. While the cytokine TGF-β has been implicated in PDAC development, it can exert both pro-tumorigenic and anti-tumorigenic effects that are highly context dependent and incompletely understood. Using three-dimensional (3D) cultures of KrasG12D-expressing mouse pancreatic epithelial cells we demonstrated that while exposure to exogenous TGF-β induced growth arrest of the KrasG12D cells, its subsequent removal allowed the cells to enter a hyper-proliferative, partially mesenchymal (PM), and progenitor-like state. This state was highly stable and was maintained by autocrine TGF-β signaling. While untreated KrasG12D cells formed cystic lesions in vivo, PM cells formed ductal structures resembling human PanINs, suggesting that they had attained increased oncogenic potential. Supporting this hypothesis, we determined that the PM cells share salient molecular and phenotypic features with the quasi-mesenchymal/squamous subtype of human PDAC, which has the worst prognosis of any of the recently identified subtypes. Transient pulses of TGF-β have been observed during pancreatitis, a major risk factor for PDAC. Our data suggest that transient TGF-β exposure is sufficient to induce the acquisition of stable PDAC-associated phenotypes in pre-neoplastic KrasG12D cells, providing novel molecular insight into the complex role of TGF-β in tumorigenesis.

Targeted Therapies Against Growth Factor Signaling in Breast Cancer

Breast cancer is the most prevalent female malignancy throughout the world. Conventional treatment strategies for breast cancer consist of chemotherapy, radiation, surgery, chemoradiation, hormone therapy, and targeted therapies. Among them, targeted therapies show advantages to reduce cost and toxicity for being possible for individualized treatments based on the intrinsic subtypes of breast cancer. With deeper understanding of key signaling pathways concerning tumor growth and survival, growth factor-controlled signaling pathways are frequently dysregulated in the development and progression of breast cancer. Thus, targeted therapies against growth factor-mediated signaling pathways have been shown to have promising efficacy in both preclinical animal models and human clinical trials. In this chapter, we will briefly introduce inhibitors and monoclonal antibodies that target the main growth factor-modulated scenarios including epidermal growth factor receptor (EGFR), transforming growth factor beta (TGF-β), insulin-like growth factor 1 receptor (IGF1R), and fibroblast growth factor receptor (FGFR) signaling pathways in breast cancer therapy.

Astragaloside Inhibits Hepatic Fibrosis by Modulation of TGF-β1/Smad Signaling Pathway

Activation of HSC is a pivotal step in hepatic fibrosis. In the activation of HSC, the TGF-β1 plays a key role that can promote the occurrence of hepatic fibrosis by combining with Smad proteins. Astragaloside is the main active component extracted from Radix Astragali that has the effect of antioxidation and hepatoprotection. In the present study, we investigated the mechanism of astragalosides inhibiting hepatic fibrosis in vitro and in vivo. In vitro, astragalosides inhibited the activation of HSC and regulated the expression of MMP-2 and TIMP-2 and reduced the formation of collagen fibers. In vivo, administration of astragalosides decreased the serum ALT, AST, and TBiL in rats by reducing oxidative stress. Astragalosides also attenuated hepatic fibrosis by reducing the concentration of hydroxyproline and inhibiting the formation of collagen fibers. The expressions of TGF-β1, TβR-I, p-Smad 2, and p-Smad 3 were downregulated after astragalosides treatments, while Smad 7 was upregulated compared to the control group. The results indicated that the effect of astragaloside on hepatic fibrosis was related to the inhibition of HSC activation and the modulation of the TGF-β1/Smad signaling pathway.

A Novel TGFβ Trap Blocks Chemotherapeutics-Induced TGFβ1 Signaling and Enhances Their Anticancer Activity in Gynecologic Cancers

Purpose: We investigated the mechanisms of how TGFβ pathway is activated by chemotherapeutics and whether a novel TGFβ trap called RER can block chemotherapeutics-induced TGFβ pathway activation and enhance their antitumor activity in gynecologic cancer.Patients and Methods: An unbiased bioinformatic analysis of differentially expressed genes in 31 ovarian cases due to chemotherapy was used to identify altered master regulators. Phosphorylated Smad2 was determined in 30 paired cervical cancer using IHC. Furthermore, the effects of chemotherapeutics on TGFβ signaling and function, and the effects of RER on chemotherapy-induced TGFβ signaling were determined in gynecologic cancer cells.Results: Chemotherapy-induced transcriptome alteration in ovarian cancer was significantly associated with TGFβ signaling activation. Chemotherapy was found to activate TGFβ signaling as indicated by phosphorylated Smad2 in paired cervical tumor samples (pre- and post-chemotherapy). Similar to TGFβ1, chemotherapeutics were found to stimulate Smad2/3 phosphorylation, cell migration, and markers related to epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC). These TGFβ-like effects were due to the stimulation of TGFβ1 expression and secretion, and could all be abrogated by TGFβ inhibitors including a novel TGFβ trap protein called RER both in vitro and in vivo Importantly, combination treatment with RER and cisplatin showed a higher tumor inhibitory activity than either agent alone in a xenograft model of ovarian cancer.Conclusions: Chemotherapeutics can stimulate TGFβ1 production and consequently enhance TGFβ signaling, EMT, and CSC features resulting in reduced chemo-sensitivity. Combination therapy with a TGFβ inhibitor should alleviate this unintended side effect of chemotherapeutics and enhance their therapeutic efficacy. Clin Cancer Res; 24(12); 2780-93. ©2018 AACR.

Drug-Clinical Agent Molecular Hybrid: Synthesis of Diaryl(trifluoromethyl)pyrazoles as Tubulin Targeting Anticancer Agents

Twenty-three combretastatin A-4 (CA-4) analogues were synthesized by judiciously incorporating a functional N-heterocyclic motif present in Celecoxib (a marketed drug) while retaining essential pharmacophoric features of CA-4. Combretastatin-(trifluoromethyl)pyrazole hybrid analogues, i.e., 5-trimethoxyphenyl-3-(trifluoromethyl)pyrazoles with a variety of relevantly substituted aryls and heteroaryls at 1-position were considered as potential tubulin polymerization inhibitors. The cytotoxicity of the compounds was evaluated using MCF-7 cells. Analog 23 (C-23) was found to be the most active among the tested compounds. It showed pronounced cytotoxicity against HeLa, B16F10, and multidrug-resistant mammary tumor cells EMT6/AR1. Interestingly, C-23 displayed significantly lower toxicity toward noncancerous cells, MCF10A and L929, than their cancerous counterparts, MCF-7 and B16F10, respectively. C-23 depolymerized interphase microtubules, disrupted mitotic spindle formation, and arrested MCF-7 cells at mitosis, leading to cell death. C-23 inhibited the assembly of tubulin in vitro. C-23 bound to tubulin at the colchicine binding site and altered the secondary structures of tubulin. The data revealed the importance of (trimethoxyphenyl)(trifluoromethyl)pyrazole as a cis-restricted double bond-alternative bridging motif, and carboxymethyl-substituted phenyl as ring B for activities and interaction with tubulin. The results indicated that the combretastatin-(trifluoromethyl)pyrazole hybrid class of analogues has the potential for further development as anticancer agents.

Spatiotemporal Control of TGF-β Signaling with Light

Cells employ signaling pathways to make decisions in response to changes in their immediate environment. Transforming growth factor beta (TGF-β) is an important growth factor that regulates many cellular functions in development and disease. Although the molecular mechanisms of TGF-β signaling have been well studied, our understanding of this pathway is limited by the lack of tools that allow the control of TGF-β signaling with high spatiotemporal resolution. Here, we developed an optogenetic system (optoTGFBRs) that enables the precise control of TGF-β signaling in time and space. Using the optoTGFBRs system, we show that TGF-β signaling can be selectively and sequentially activated in single cells through the modulation of the pattern of light stimulations. By simultaneously monitoring the subcellular localization of TGF-β receptor and Smad2 proteins, we characterized the dynamics of TGF-β signaling in response to different patterns of blue light stimulations. The spatial and temporal precision of light control will make the optoTGFBRs system as a powerful tool for quantitative analyses of TGF-β signaling at the single cell level.

Crosstalk between the Tumor Microenvironment and Immune System in Pancreatic Ductal Adenocarcinoma: Potential Targets for New Therapeutic Approaches

Pancreatic ductal adenocarcinoma is a lethal disease for which radical surgery and chemotherapy represent the only curative options for a small proportion of patients. Recently, FOLFIRINOX and nab-paclitaxel plus gemcitabine have improved the survival of metastatic patients but prognosis remains poor. A pancreatic tumor microenvironment is a dynamic milieu of cellular and acellular elements, and it represents one of the major limitations to chemotherapy efficacy. The continued crosstalk between cancer cells and the surrounding microenvironment causes immunosuppression within pancreatic immune infiltrate increasing tumor aggressiveness. Several potential targets have been identified among tumor microenvironment components, and different therapeutic approaches are under investigation. In this article, we provide a qualitative literature review about the crosstalk between the tumor microenvironment components and immune system in pancreatic cancer. Finally, we discuss potential therapeutic strategies targeting the tumor microenvironment and we show the ongoing trials.

Targeting TGF-β Signaling for Therapeutic Gain

Transforming growth factor βs (TGF-βs) are closely related ligands that have pleiotropic activity on most cell types of the body. They act through common heterotetrameric TGF-β type II and type I transmembrane dual specificity kinase receptor complexes, and the outcome of signaling is context-dependent. In normal tissue, they serve a role in maintaining homeostasis. In many diseased states, particularly fibrosis and cancer, TGF-β ligands are overexpressed and the outcome of signaling is diverted toward disease progression. There has therefore been a concerted effort to develop drugs that block TGF-β signaling for therapeutic benefit. This review will cover the basics of TGF-β signaling and its biological activities relevant to oncology, present a summary of pharmacological TGF-β blockade strategies, and give an update on preclinical and clinical trials for TGF-β blockade in a variety of solid tumor types.

Fluid shear stress-induced TGF-β/ALK5 signaling in renal epithelial cells is modulated by MEK1/2

Renal tubular epithelial cells are exposed to mechanical forces due to fluid flow shear stress within the lumen of the nephron. These cells respond by activation of mechano-sensors located at the plasma membrane or the primary cilium, having crucial roles in maintenance of cellular homeostasis and signaling. In this paper, we applied fluid shear stress to study TGF-β signaling in renal epithelial cells with and without expression of the Pkd1-gene, encoding a mechano-sensor mutated in polycystic kidney disease. TGF-β signaling modulates cell proliferation, differentiation, apoptosis, and fibrotic deposition, cellular programs that are altered in renal cystic epithelia. SMAD2/3-mediated signaling was activated by fluid flow, both in wild-type and Pkd1^−/− cells. This was characterized by phosphorylation and nuclear accumulation of p-SMAD2/3, as well as altered expression of downstream target genes and epithelial-to-mesenchymal transition markers. This response was still present after cilia ablation. An inhibitor of upstream type-I-receptors, ALK4/ALK5/ALK7, as well as TGF-β-neutralizing antibodies effectively blocked SMAD2/3 activity. In contrast, an activin-ligand trap was ineffective, indicating that increased autocrine TGF-β signaling is involved. To study potential involvement of MAPK/ERK signaling, cells were treated with a MEK1/2 inhibitor. Surprisingly, fluid flow-induced expression of most SMAD2/3 targets was further enhanced upon MEK inhibition. We conclude that fluid shear stress induces autocrine TGF-β/ALK5-induced target gene expression in renal epithelial cells, which is partially restrained by MEK1/2-mediated signaling.

Loss of TRIM33 causes resistance to BET bromodomain inhibitors through MYC- and TGF-β-dependent mechanisms

Bromodomain and extraterminal domain protein inhibitors (BETi) hold great promise as a novel class of cancer therapeutics. Because acquired resistance typically limits durable responses to targeted therapies, it is important to understand mechanisms by which tumor cells adapt to BETi. Here, through pooled shRNA screening of colorectal cancer cells, we identified tripartite motif-containing protein 33 (TRIM33) as a factor promoting sensitivity to BETi. We demonstrate that loss of TRIM33 reprograms cancer cells to a more resistant state through at least two mechanisms. TRIM33 silencing attenuates down-regulation of MYC in response to BETi. Moreover, loss of TRIM33 enhances TGF-β receptor expression and signaling, and blocking TGF-β receptor activity potentiates the antiproliferative effect of BETi. These results describe a mechanism for BETi resistance and suggest that combining inhibition of TGF-β signaling with BET bromodomain inhibition may offer new therapeutic benefits.

Myc and Fgf Are Required for Zebrafish Neuromast Hair Cell Regeneration

Unlike mammals, the non-mammalian vertebrate inner ear can regenerate the sensory cells, hair cells, either spontaneously or through induction after hair cell loss, leading to hearing recovery. The mechanisms underlying the regeneration are poorly understood. By microarray analysis on a chick model, we show that chick hair cell regeneration involves the activation of proliferation genes and downregulation of differentiation genes. Both MYC and FGF are activated in chick hair cell regeneration. Using a zebrafish lateral line neuromast hair cell regeneration model, we show that the specific inhibition of Myc or Fgf suppresses hair cell regeneration, demonstrating that both pathways are essential to the process. Rapid upregulation of Myc and delayed Fgf activation during regeneration suggest a role of Myc in proliferation and Fgf in differentiation. The dorsal-ventral pattern of fgfr1a in the neuromasts overlaps with the distribution of hair cell precursors. By laser ablation, we show that the fgfr1a-positive supporting cells are likely the hair cell precursors that directly give rise to new hair cells; whereas the anterior-posterior fgfr1a-negative supporting cells have heightened proliferation capacity, likely to serve as more primitive progenitor cells to replenish lost precursors after hair cell loss. Thus fgfr1a is likely to mark compartmentalized supporting cell subtypes with different capacities in renewal proliferation and hair cell regeneration. Manipulation of c-MYC and FGF pathways could be explored for mammalian hair cell regeneration.

Computational approaches in target identification and drug discovery

In the big data era, voluminous datasets are routinely acquired, stored and analyzed with the aim to inform biomedical discoveries and validate hypotheses. No doubt, data volume and diversity have dramatically increased by the advent of new technologies and open data initiatives. Big data are used across the whole drug discovery pipeline from target identification and mechanism of action to identification of novel leads and drug candidates. Such methods are depicted and discussed, with the aim to provide a general view of computational tools and databases available. We feel that big data leveraging needs to be cost-effective and focus on personalized medicine. For this, we propose the interplay of information technologies and (chemo)informatic tools on the basis of their synergy.