Comparison of cardiac magnetic resonance imaging, functional and haemodynamic variables in pulmonary arterial hypertension: insights from REPAIR.

Background: Measures that can detect large treatment effects are important for monitoring therapeutic effectiveness. The 2022 European Society of Cardiology/European Respiratory Society guidelines highlight the importance of imaging in monitoring disease status and treatment response in pulmonary arterial hypertension (PAH). Are the standardised treatment effect sizes (STES) of cardiac magnetic resonance imaging (cMRI) comparable with functional and haemodynamic variables? Methods: REPAIR (ClinicalTrials.gov: NCT02310672) was a prospective, multicentre, single-arm, open-label, 52-week phase 4 study evaluating the effect of macitentan 10 mg, with or without a phosphodiesterase 5 inhibitor (PDE5i), on right ventricular (RV) remodelling, cardiac function and cardiopulmonary haemodynamics. Both cMRI and functional assessments were performed at screening and at weeks 26 and 52; haemodynamic measurements were conducted at screening and week 26. In this post hoc analysis, STES were estimated using the parametric Cohen's d and non-parametric Cliff's delta tests. Results: At week 26, large STES (Cohen's d) were observed for 10 of the 20 cMRI variables assessed, including the prognostic measures of RV and left ventricular stroke volume and RV ejection fraction and the haemodynamic trial end-point, pulmonary vascular resistance; medium STES were observed for 6-min walk distance (6MWD). The STES were consistent in treatment-naïve patients and those escalating therapy and maintained at week 52. Similar results were obtained using the non-parametric Cliff's delta method. Conclusions: The treatment effect of macitentan, alone or in combination with a PDE5i, was comparable for several cMRI and haemodynamic variables with prognostic value in PAH, and greater than that of 6MWD in patients with PAH, highlighting the emerging relevance of cMRI in PAH.

Initial combination therapy with macitentan and tadalafil in patients with pulmonary arterial hypertension, with and without cardiac comorbidities.

AIMS: According to current guidelines, initial monotherapy should be considered for pulmonary arterial hypertension (PAH) patients with cardiopulmonary comorbidities. This analysis of combined data from the TRITON and REPAIR clinical trials, assesses efficacy and safety of initial double combination therapy in patients without vs. with 1-2 cardiac comorbidities. METHODS AND RESULTS: Data were combined for patients from TRITON (NCT02558231) and REPAIR (NCT02310672) on initial macitentan and tadalafil double combination therapy (overall set, n = 148) and two subgroups defined as patients without cardiac comorbidities (n = 62) and those with 1-2 cardiac comorbidities (n = 78). Patients with ≥3 comorbidities were excluded from these studies. For the overall set, the median (Q1-Q3) duration of combined macitentan and tadalafil exposure was 513.0 (364.0-778.0) days, and was similar between subgroups. Change from baseline to Week 26 for pulmonary vascular resistance was -55% and -50% for patients without and with 1-2 cardiac comorbidities, respectively; marked improvements in other hemodynamic and functional parameters were also observed, although functional parameters improved to a lesser extent in patients with comorbidities. At Week 26, the majority of patients had improved PAH risk status, according to the non-invasive four-strata and REVEAL Lite 2.0 methods. The safety profile of initial macitentan plus tadalafil combination therapy was consistent with the known profiles of the two drugs, and similar between the subgroups. CONCLUSIONS: Initial double combination therapy with macitentan plus tadalafil is efficacious in patients with PAH with 1-2 cardiac comorbidities and those without, with similar safety and tolerability profiles between the two groups.

Safety of Macitentan for the Treatment of Portopulmonary Hypertension: Real-World Evidence from the Combined OPUS/OrPHeUS Studies.

INTRODUCTION: Portopulmonary hypertension (PoPH) carries a worse prognosis than other forms of pulmonary arterial hypertension (PAH). Data regarding use of PAH-specific therapies in patients with PoPH are sparse as they are usually excluded from clinical trials. This analysis describes patient characteristics, treatment patterns, outcomes, and safety profiles in patients with PoPH newly initiating macitentan in the USA using the OPUS/OrPHeUS combined dataset. METHODS: OPUS was a prospective, US, multicenter, observational drug registry (April 2014-June 2020); OrPHeUS was a retrospective, US, multicenter chart review (October 2013-March 2017). Additional information regarding patients' liver disease was retrospectively collected for patients with PoPH in OPUS. RESULTS: The OPUS/OrPHeUS dataset included 206 patients with PoPH (median age 58 years; 52.4% female), with baseline cirrhosis and liver test abnormalities reported in 72.8% and 31.6% of patients respectively. Macitentan was initiated as combination therapy in 74.8% of patients and median (Q1, Q3) exposure to macitentan was 11.9 (3.1, 26.0) months. One-year Kaplan-Meier estimates (95% confidence limit, CL) of patients free from all-cause hospitalization and survival were 48.6% (40.7, 56.0) and 82.2% (75.1, 87.4). Of the 96 patients with PoPH in OPUS, 29.2% were classified as in need of liver transplant due to underlying liver disease during the study; transplant waitlist registration was precluded because of PAH severity for 32.1% and 17.9% were transplanted. Hepatic adverse events (HAE) were experienced by 49.0% of patients; the most common being increased bilirubin (16.0%), ascites (7.3%), and hepatic encephalopathy (5.8%); 1.5% and 21.8% of patients discontinued macitentan as a result of HAE and non-hepatic adverse events. CONCLUSION: There were no unexpected safety findings in patients with PoPH treated with macitentan. These data add to the evidence supporting the safety and tolerability of macitentan in patients with PoPH. A graphical abstract is available with this article. TRIAL REGISTRATION: OPsumit® Users Registry (OPUS): NCT02126943; OPsumit® Historical Users cohort (OrPHeUS): NCT03197688; www. CLINICALTRIALS: gov .

Co-expression of HER2 and HER3 receptor tyrosine kinases enhances invasion of breast cells via stimulation of interleukin-8 autocrine secretion.

INTRODUCTION: The tyrosine kinase receptors HER2 and HER3 play an important role in breast cancer. The HER2/HER3 heterodimer is a critical oncogenic unit associated with reduced relapse-free and decreased overall survival. While signaling cascades downstream of HER2 and HER3 have been studied extensively at the level of post-translational modification, little is known about the effects of HER2/HER3 overexpression and activation on gene expression in breast cancer. We have now defined the genetic landscape induced by activation of the HER2/HER3 unit in mammary cells, and have identified interleukin (IL)8 and CXCR1 as potential therapeutic targets for the treatment of HER2/HER3-overexpressing breast cancers. METHODS: Three-dimensional (3D) cultures, invasion and migration assays were used to determine the effects of HER2 and HER3 co-expression and activation. Gene expression analysis was performed to identify the gene network induced by HER2/HER3 in 3D cultures. Bioinformatic analysis and neutralizing antibodies were used to identify key mediators of HER2/HER3-evoked invasion. RESULTS: Co-expression of the tyrosine kinase receptors HER2 and HER3 induced migration and invasion of MCF10A cells. Microarray analysis of these cells revealed a specific "HER2/HER3 signature" comprising 80 upregulated transcripts, with IL8 being the highest (11-fold upregulation). Notably, examination of public datasets revealed high levels of IL8 transcripts in HER2-enriched as well as basal-like primary breast tumors, two subtypes characterized by a particularly poor prognosis. Moreover, IL8 expression correlated with high tumor grade and ER-negative status. Importantly, treatment with IL8-neutralizing antibodies prevented invasion of MCF10A-HER2/HER3 and BT474 cells in 3D cultures, highlighting the importance of IL8 autocrine signaling upon HER2/HER3 activation. CONCLUSIONS: Our findings demonstrate that HER2 and HER3 co-expression induces IL8 autocrine signaling, leading to the invasion of mammary cells. Agents targeting IL8 or its receptor CXCR1 may be useful for the treatment of HER2/HER3/IL8-positive breast cancers with invasive traits.

Decreased expression of BRCA1 in SK-BR-3 cells is the result of aberrant activation of the GABP Beta promoter by an NRF-1-containing complex.

BACKGROUND: BRCA1 has recently been identified as a potential regulator of mammary stem/progenitor cell differentiation, and this function may explain the high prevalence of breast cancer in BRCA1 mutation carriers, as well as the downregulation of BRCA1 in a large proportion of sporadic breast cancers. That is, loss of BRCA1 function results in blocked differentiation with expansion of the mammary stem/progenitor cells. Because BRCA1 also maintains genomic integrity, its loss could produce a pool of genetically unstable stem/progenitor cells that are prime targets for further transforming events. Thus, elucidating the regulatory mechanisms of BRCA1 expression is important to our understanding of normal and malignant breast differentiation. RESULTS: Loss of BRCA1 expression in the ErbB2-amplified SK-BR-3 cell line was found to be the result of loss of activity of the ets transcription factor GABP, a previously characterized regulator of BRCA1 transcription. The expression of the non-DNA binding GABPß subunit was shown to be deficient, while the DNA binding subunit, GABPα was rendered unstable by the absence of GABPß. Deletion analysis of the GABPß proximal promoter identified a potential NRF-1 binding site as being critical for expression. Supershift analysis, the binding of recombinant protein and chromatin immunoprecipitation confirmed the role of NRF-1 in regulating the expression of GABPß. The siRNA knockdown of NRF-1 resulted in decreased GABPß and BRCA1 expression in MCF-7 cells indicating that they form a transcriptional network. NRF-1 levels and activity did not differ between SK-BR-3 and MCF-7 cells, however the NRF-1 containing complex on the GABPß promoter differed between the two lines and appears to be the result of altered coactivator binding. CONCLUSIONS: Both NRF-1 and GABP have been linked to the regulation of nuclear-encoded mitochondrial proteins, and the results of this study suggest their expression is coordinated by NRF-1's activation of the GABPß promoter. Their linkage to BRCA1, a potential breast stem cell regulator, implies a connection between the induction of mitochondrial metabolism and breast differentiation.

Wnt3a regulates proliferation and migration of HUVEC via canonical and non-canonical Wnt signaling pathways.

Untangling the signaling pathways involved in endothelial cell biology is of central interest for the development of antiangiogenesis based therapies. Here we report that Wnt3a induces the proliferation and migration of HUVECs, but does not affect their survival. Wnt3a-induced proliferation was VEGFR signaling independent, but reduced upon CamKII inhibition. In a search for the downstream mediators of Wnt3a's effects on HUVEC biology, we found that Wnt3a treatment leads to phosphorylation of DVL3 and stabilization of beta-catenin. Moreover, under the same conditions we observed an upregulation in c-MYC, TIE-2 and GJA1 mRNA transcripts. Although treatment of HUVECs with Wnt5a induced DVL3 phosphorylation, we did not observe any of the other effects seen upon Wnt3a stimulation. Taken together, our data indicate that Wnt3a induces canonical and non-canonical Wnt signaling in HUVECs, and stimulates their proliferation and migration.

Characterization of a negative transcriptional element in the BRCA1 promoter.

INTRODUCTION: Decreased transcription of the BRCA1 gene has previously been observed to occur in sporadic breast tumours, making elucidation of the mechanisms regulating the expression of this gene important for our understanding of the etiology of the disease. METHODS: Transcriptional elements involved in the regulation of the BRCA1 promoter were analysed by co-transfection experiments into the human MCF-7 and T-47D breast cancer cell lines. RESULTS: We have identified a repressor element, referred to as the UP site, within the proximal BRCA1 promoter whose inactivation results in increased promoter activity. An E2F recognition element, previously suggested to mediate repression via E2F-6, is adjacent to the UP site and its inactivation also leads to increased BRCA1 expression. These two elements appear to form a composite repressor element whose combined effect is additive. The UP element is composed of two sequences, one of which binds the ubiquitously expressed ets family transcription factor GABP alpha/beta. This site is distinct from a previously identified GABP alpha/beta site, the RIBS element, though the RIBS site appears to be necessary for derepression of the promoter via mutations in the UP site. Knockdown of GABP alpha using an shRNA vector confirms that this protein is important for the function of both the RIBS and UP sites. CONCLUSION: The identification of a repressor element in the BRCA1 promoter brings a new level of complexity to the regulation of BRCA1 expression. The elements characterized here may play a normal role in the integration of a variety of signals, including two different growth related pathways, and it is possible that loss of the ability to derepress the BRCA1 promoter during critical periods may contribute to breast transformation.

Regulation of the BRCA1 promoter in ovarian surface epithelial cells and ovarian carcinoma cells.

As BRCA1 expression is often suppressed in sporadic ovarian carcinoma we characterized the regulation of the 231nt proximal 'L6' fragment of the BRCA1 promoter in two human ovarian surface epithelial cell and two sporadic ovarian carcinoma cell lines. Two individual regulatory elements within L6, the 'RIBS' element and the potential 'CRE' element were each necessary, but alone not sufficient for L6 activation in all four cell lines. The latter element showed some affinity for the CREB transcription factor, but cAMP pathway stimulation failed to promote its activation. This element did, however, interact with, and was activated by, c-Jun and Fra2 which suggests that it can interact with AP1-like transcription factors and that it may act co-operatively with RIBS-binding factors to regulate BRCA1 transcription in ovarian cells.

Memo interacts with c-Src to control Estrogen Receptor alpha sub-cellular localization.

Understanding the complex interaction between growth factor and steroid hormone signaling pathways in breast cancer is key to identifying suitable therapeutic strategies to avoid progression and therapy resistance. The interaction between these two pathways is of paramount importance for the development of endocrine resistance. Nevertheless, the molecular mechanisms behind their crosstalk are still largely obscure. We previously reported that Memo is a small redox-active protein that controls heregulin-mediated migration of breast cancer cells. Here we report that Memo sits at the intersection between heregulin and estrogen signaling, and that Memo controls Estrogen Receptor alpha (ERα) sub-cellular localization, phosphorylation, and function downstream of heregulin and estrogen in breast cancer cells. Memo facilitates ERα and c-Src interaction, ERα Y537 phosphorylation, and has the ability to control ERα extra-nuclear localization. Thus, we identify Memo as an important key mediator between the heregulin and estrogen signaling pathways, which affects both breast cancer cell migration and proliferation.

Serpin E2 promotes breast cancer metastasis by remodeling the tumor matrix and polarizing tumor associated macrophages.

The extracellular serine protease inhibitor serpinE2 is overexpressed in breast cancer and has been shown to foster metastatic spread. Here, we investigated the hypothesis that serpinE2 creates tumor-promoting conditions in the tumor microenvironment (TME) by affecting extracellular matrix remodeling. Using two different breast cancer models, we show that blocking serpinE2, either by knock-down (KD) in tumor cells or in response to a serpinE2 binding antibody, decreases metastatic dissemination from primary tumors to the lungs. We demonstrate that in response to serpinE2 KD or antibody treatment there are dramatic changes in the TME. Multiphoton intravital imaging revealed deposition of a dense extracellular collagen I matrix encapsulating serpinE2 KD or antibody-treated tumors. This is accompanied by a reduction in the population of tumor-promoting macrophages, as well as a decrease in chemokine ligand 2, which is known to affect macrophage abundance and polarization. In addition, TIMP-1 secretion is increased, which may directly inhibit matrix metalloproteases critical for collagen degradation in the tumor. In summary, our findings suggest that serpinE2 is required in the extracellular milieu of tumors where it acts in multiple ways to regulate tumor matrix deposition, thereby controlling tumor cell dissemination.

Memo is a copper-dependent redox protein with an essential role in migration and metastasis.

Memo is an evolutionarily conserved protein with a critical role in cell motility. We found that Memo was required for migration and invasion of breast cancer cells in vitro and spontaneous lung metastasis from breast cancer cell xenografts in vivo. Biochemical assays revealed that Memo is a copper-dependent redox enzyme that promoted a more oxidized intracellular milieu and stimulated the production of reactive oxygen species (ROS) in cellular structures involved in migration. Memo was also required for the sustained production of the ROS O2- by NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase 1 (NOX1) in breast cancer cells. Memo abundance was increased in >40% of the primary breast tumors tested, was correlated with clinical parameters of aggressive disease, and was an independent prognostic factor of early distant metastasis.

Microenvironmental regulation of BRCA1 gene expression by c-Jun and Fra2 in premalignant human ovarian surface epithelial cells.

Reduced BRCA1 gene expression is common in the sporadic form of ovarian carcinoma. The spread of this highly lethal cancer often begins when tumor cell clusters are shed into the fluid of the abdominopelvic cavity such that they can float freely before seeding distant sites on the peritoneal walls and organs. Thus, the microenvironment that tumor cells find themselves in changes dramatically during these early shedding and floating stages of transperitoneal metastasis. To mimic this microenvironmental change in vitro, we released premalignant human ovarian surface epithelial cells from the substratum and forced them to cluster in suspension. Under these conditions, steady state levels of BRCA1 mRNA and protein fell significantly and the transcriptional activation state of the BRCA1 promoter was suppressed. Analysis of the promoter indicated that the previously identified "CRE" element located within the "positive regulatory region" (PRR) contributed to this suppression. More specifically, we show that the suppression was mediated, at least in part, by a suspension culture-driven decrease in the levels of two members of the AP1 transcription factor complex, c-Jun and Fra2, that bind to the CRE element. Therefore, a microenvironmental change that is manifested during the initial stages of ovarian carcinoma dissemination may, potentially, help suppress BRCA1 expression in sporadic tumors and thus promote their progression.

ErbB receptors and signaling pathways in cancer.

The ErbB receptor tyrosine kinases play important roles in normal physiology and in cancer. Epidermal growth factor receptor (EGFR) and ErbB2 in particular are mutated in many epithelial tumors, and clinical studies suggest that they play roles in cancer development and progression. These receptors have been intensely studied, not only to understand the mechanisms underlying their oncogenic potential, but also to exploit them as therapeutic targets. ErbB receptors activate a multiplicity of intracellular pathways via their ability to interact with numerous signal transducers. Furthermore, there are now many ErbB-targeted inhibitors used in the clinic. In this review we will concentrate on breast tumors with ERBB2 gene amplification/receptor overexpression and non-small cell lung cancer (NSCLC) with activating EGFR mutations. We will discuss data showing the important role that the PI3K/Akt pathway plays, not only in cancer development, but also in response to targeted therapies. Finally, mechanisms contributing to resistance to ErbB-targeted therapeutics will also be discussed.