Transcriptional Landscape of PARs in Epithelial Malignancies

Multi-omics integration analysis of GPCRs in pan-cancer to uncover inter-omics relationships and potential driver genes

G protein-coupled receptors (GPCRs) are the largest drug target family. Unfortunately, applications of GPCRs in cancer therapy are scarce due to very limited knowledge regarding their correlations with cancers. Multi-omics data enables systematic investigations of GPCRs, yet their effective integration remains a challenge due to the complexity of the data. Here, we adopt two types of integration strategies, multi-staged and meta-dimensional approaches, to fully characterize somatic mutations, somatic copy number alterations (SCNAs), DNA methylations, and mRNA expressions of GPCRs in 33 cancers. Results from the multi-staged integration reveal that GPCR mutations cannot well predict expression dysregulation. The correlations between expressions and SCNAs are primarily positive, while correlations of the methylations with expressions and SCNAs are bimodal with negative correlations predominating. Based on these correlations, 32 and 144 potential cancer-related GPCRs driven by aberrant SCNA and methylation are identified, respectively. In addition, the meta-dimensional integration analysis is carried out by using deep learning models, which predict more than one hundred GPCRs as potential oncogenes. When comparing results between the two integration strategies, 165 cancer-related GPCRs are common in both, suggesting that they should be prioritized in future studies. However, 172 GPCRs emerge in only one, indicating that the two integration strategies should be considered concurrently to complement the information missed by the other such that obtain a more comprehensive understanding. Finally, correlation analysis further reveals that GPCRs, in particular for the class A and adhesion receptors, are generally immune-related. In a whole, the work is for the first time to reveal the associations between different omics layers and highlight the necessity of combing the two strategies in identifying cancer-related GPCRs.

PH-Binding Motif in PAR4 Oncogene: From Molecular Mechanism to Drug Design

While the role of G-protein-coupled receptors (GPCR) in cancer is acknowledged, their underlying signaling pathways are understudied. Protease-activated receptors (PAR), a subgroup of GPCRs, form a family of four members (PAR1-4) centrally involved in epithelial malignancies. PAR4 emerges as a potent oncogene, capable of inducing tumor generation. Here, we demonstrate identification of a pleckstrin-homology (PH)-binding motif within PAR4, critical for colon cancer growth. In addition to PH-Akt/PKB association, other PH-containing signal proteins such as Gab1 and Sos1 also associate with PAR4. Point mutations are in the C-tail of PAR4 PH-binding domain; F347 L and D349A, but not E346A, abrogate these associations. Pc(4-4), a lead backbone cyclic peptide, was selected out of a mini-library, directed toward PAR2&4 PH-binding motifs. It effectively attenuates PAR2&4-Akt/PKB associations; PAR4 instigated Matrigel invasion and migration in vitro and tumor development in vivo. EGFR/erbB is among the most prominent cancer targets. AYPGKF peptide ligand activation of PAR4 induces EGF receptor (EGFR) Tyr-phosphorylation, effectively inhibited by Pc(4-4). The presence of PAR2 and PAR4 in biopsies of aggressive breast and colon cancer tissue specimens is demonstrated. We propose that Pc(4-4) may serve as a powerful drug not only toward PAR-expressing tumors but also for treating EGFR/erbB-expressing tumors in cases of resistance to traditional therapies. Overall, our studies are expected to allocate new targets for cancer therapy. Pc(4-4) may become a promising candidate for future therapeutic cancer treatment.

Antiplatelet Therapy Combined with Anastrozole Induces Features of Partial EMT in Breast Cancer Cells and Fails to Mitigate Breast-Cancer Induced Hypercoagulation

Thromboembolic complications are a leading cause of morbidity and mortality in cancer patients. Cancer patients often present with an increased risk for thrombosis including hypercoagulation, so the application of antiplatelet strategies to oncology warrants further investigation. This study investigated the effects of anastrozole and antiplatelet therapy (aspirin/clopidogrel cocktail or atopaxar) treatment on the tumour responses of luminal phenotype breast cancer cells and induced hypercoagulation. Ethical clearance was obtained (M150263). Blood was co-cultured with breast cancer cell lines (MCF7 and T47D) pre-treated with anastrozole and/or antiplatelet drugs for 24 h. Hypercoagulation was indicated by thrombin production and platelet activation (morphological and molecular). Gene expression associated with the epithelial-to-mesenchymal transition (EMT) was assessed in breast cancer cells, and secreted cytokines associated with tumour progression were evaluated. Data were analysed with the PAST3 software. Our findings showed that antiplatelet therapies (aspirin/clopidogrel cocktail and atopaxar) combined with anastrozole failed to prevent hypercoagulation and induced evidence of a partial EMT. Differences in tumour responses that modulate tumour aggression were noted between breast cancer cell lines, and this may be an important consideration in the clinical management of subphenotypes of luminal phenotype breast cancer. Further investigation is needed before this treatment modality (combined hormone and antiplatelet therapy) can be considered for managing tumour associated-thromboembolic disorder.

YAP and endothelin-1 signaling: an emerging alliance in cancer

The rational making the G protein-coupled receptors (GPCR) the centerpiece of targeted therapies is fueled by the awareness that GPCR-initiated signaling acts as pivotal driver of the early stages of progression in a broad landscape of human malignancies. The endothelin-1 (ET-1) receptors (ET-1R), known as ET_A receptor (ET_AR) and ET_B receptor (ET_BR) that belong to the GPCR superfamily, affect both cancer initiation and progression in a variety of cancer types. By the cross-talking with multiple signaling pathways mainly through the scaffold protein β-arrestin1 (β-arr1), ET-1R axis cooperates with an array of molecular determinants, including transcription factors and co-factors, strongly affecting tumor cell fate and behavior. In this scenario, recent findings shed light on the interplay between ET-1 and the Hippo pathway. In ET_AR highly expressing tumors ET-1 axis induces the de-phosphorylation and nuclear accumulation of the Hippo pathway downstream effectors, the paralogous transcriptional cofactors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). Recent evidence have discovered that ET-1R/β-arr1 axis instigates a transcriptional interplay involving YAP and mutant p53 proteins, which share a common gene signature and cooperate in a oncogenic signaling network. Mechanistically, YAP and mutp53 are enrolled in nuclear complexes that turn on a highly selective YAP/mutp53-dependent transcriptional response. Notably, ET-1R blockade by the FDA approved dual ET-1 receptor antagonist macitentan interferes with ET-1R/YAP/mutp53 signaling interplay, through the simultaneous suppression of YAP and mutp53 functions, hampering metastasis and therapy resistance. Based on these evidences, we aim to review the recent findings linking the GPCR signaling, as for ET-1R, to YAP/TAZ signaling, underlining the clinical relevance of the blockade of such signaling network in the tumor and microenvironmental contexts. In particular, we debate the clinical implications regarding the use of dual ET-1R antagonists to blunt gain of function activity of mutant p53 proteins and thereby considering them as a potential therapeutic option for mutant p53 cancers. The identification of ET-1R/β-arr1-intertwined and bi-directional signaling pathways as targetable vulnerabilities, may open new therapeutic approaches able to disable the ET-1R-orchestrated YAP/mutp53 signaling network in both tumor and stromal cells and concurrently sensitizes to high-efficacy combined therapeutics.

Tamoxifen induces hypercoagulation and alterations in ERα and ERβ dependent on breast cancer sub-phenotype ex vivo

Tamoxifen shows efficacy in reducing breast cancer-related mortality but clinically, is associated with increased risk for thromboembolic events. We aimed to determine whether breast tumour sub-phenotype could predict propensity for thrombosis. We present two ex vivo Models of Tamoxifen-therapy, Model 1 in which treatment recapitulates accumulation within breast tissue, by treating MCF7 and T47D cells directly prior to exposure to blood constituents; and Model 2 in which we recreate circulating Tamoxifen by treating blood constituents prior to exposure to cancer cells. Blood constituents included whole blood, platelet-rich plasma and platelet-poor plasma. Hypercoagulation was assessed as a function of thrombin activity, expression of CD62P and CD63 activation markers defined as an index of platelet activation, and platelet morphology; while oestrogen receptor expression was assessed using immunocytochemistry with quantitative analysis. We determined, in concert with clinical studies and contrary to selected laboratory investigations, that Tamoxifen induces hypercoagulation, dependent on sub-phenotypes, with the T47D cell line capacity most enhanced. We determined a weak positive correlation between oestrogen receptor expression, and CD62P and CD63; indicating an association between tumour invasion profiles and hypercoagulation, however, other yet unknown factors may play a predictive role in defining hypercoagulation.

Ankaferd hemostat (ABS) as a potential mucosal topical agent for the management of COVID-19 syndrome based on its PAR-1 inhibitory effect and oestrogen content

COVID-19 due to the SARS-CoV-2 infection is a multi-systemic immune syndrome affecting mainly the lungs, oropharyngeal region, and other vascular endothelial beds. There are tremendous ongoing efforts for the aim of developing drugs against the COVID-19 syndrome-associated inflammation. However, currently no specific medicine is present for the absolute pharmacological cure of COVID-19 mucositis. The re-purposing/re-positioning of already existing drugs is a very important strategy for the management of ongoing pandemy since the development of a new drug needs decades. Apart from altering angiotensin signaling pathways, novel drug candidates for re-purposing comprise medications shall target COVID-19 pathobiology, including pharmaceutical formulations that antagonize proteinase-activated receptors (PARs), mainly PAR-1. Activation of the PAR-1, mediators and hormones impact on the hemostasis, endothelial activation, alveolar epithelial cells and mucosal inflammatory responses which are the essentials of the COVID-19 pathophysiology. In this context, Ankaferd hemostat (Ankaferd Blood Stopper, ABS) which is an already approved hemostatic agent affecting via vital erythroid aggregation and fibrinogen gamma could be a potential topical remedy for the mucosal management of COVID-19. ABS is a clinically safe and effective topical hemostatic agent of plant origin capable of exerting pleiotropic effects on the endothelial cells, angiogenesis, cell proliferation and vascular dynamics. ABS had been approved as a topically applied hemostatic agent for the management of post-surgical/dental bleedings and healing of infected inflammatory mucosal wounds. The anti-inflammatory and proteinase-activated receptor axis properties of ABS with a considerable amount of oestrogenic hormone presence highlight this unique topical hemostatic drug regarding the clinical re-positioning for COVID-19-associated mucositis. Topical ABS as a biological response modifier may lessen SARS-CoV-2 associated microthrombosis, endothelial dysfunction, oropharyngeal inflammation and mucosal lung damage. Moreover, PAR-1 inhibition ability of ABS might be helpful for reducing the initial virus propagation and mocasal spread of COVID-19.

Friend or foe, the role of EGR-1 in cancer

Early growth response-1 (EGR-1), also termed NEFI-A and Krox-24, as a multi-domain protein is implicated in several vital physiological processes, including development, metabolism, cell growth and proliferation. Previous studies have implied that EGR-1 was producing in response to the tissue injury, immune response and fibrosis. Meanwhile, emerging studies stressed the pronounced correlation of EGR-1 and human cancers. Nevertheless, the intricate mechanisms of cancer-reduce EGR-1 alteration still poorly characterized. In the review, we evaluated the effects of EGR-1 in tumor cell proliferation, apoptosis, migration, invasion and tumor microenvironment, and then, we dwell on the intricate signaling pathways that EGR-1 involved in. The aberrantly expressed of EGR-1 in cancers are expected to provide a new cancer therapy strategy or a new marker for assessing treatment efficacy.

GPCRomics: An Approach to Discover GPCR Drug Targets

G protein-coupled receptors (GPCRs) are targets for ∼35% of approved drugs but only ∼15% of the ∼800 human GPCRs are currently such targets. GPCRomics, the use of unbiased, hypothesis-generating methods [e.g., RNA-sequencing (RNA-seq)], with tissues and cell types to identify and quantify GPCR expression, has led to the discovery of previously unrecognized GPCRs that contribute to functional responses and pathophysiology and that may be therapeutic targets. The combination of GPCR expression data with validation studies (e.g., signaling and functional activities) provides opportunities for the discovery of disease-relevant GPCR targets and therapeutics. Here, we review insights from GPCRomic approaches, gaps in knowledge, and future directions by which GPCRomics can advance GPCR biology and the discovery of new GPCR-targeted drugs.

GPCR-Hippo Signaling in Cancer

The Hippo signaling pathway is involved in tissue size regulation and tumorigenesis. Genetic deletion or aberrant expression of some Hippo pathway genes lead to enhanced cell proliferation, tumorigenesis, and cancer metastasis. Recently, multiple studies have identified a wide range of upstream regulators of the Hippo pathway, including mechanical cues and ligands of G protein-coupled receptors (GPCRs). Through the activation related G proteins and possibly rearrangements of actin cytoskeleton, GPCR signaling can potently modulate the phosphorylation states and activity of YAP and TAZ, two homologous oncogenic transcriptional co-activators, and major effectors of the Hippo pathway. Herein, we summarize the network, regulation, and functions of GPCR-Hippo signaling, and we will also discuss potential anti-cancer therapies targeting GPCR-YAP signaling.