It is becoming increasingly apparent that the tumor microenvironment plays a critical role in human breast cancer onset and progression. Therefore, we isolated cancer-associated fibroblasts (CAFs) from human breast cancer lesions and studied their properties, as compared with normal mammary fibroblasts (NFs) isolated from the same patient. Here, we demonstrate that 8 out of 11 CAFs show dramatic downregulation of caveolin-1 (Cav-1) protein expression; Cav-1 is a well-established marker that is normally decreased during the oncogenic transformation of fibroblasts. Next, we performed gene expression profiling studies (DNA microarray) and established a CAF gene expression signature. Interestingly, the expression signature associated with CAFs encompasses a large number of genes that are regulated via the RB-pathway. The CAF gene signature is also predictive of poor clinical outcome in breast cancer patients that were treated with tamoxifen mono-therapy, indicating that CAFs may be useful for predicting the response to hormonal therapy. Finally, we show that replacement of Cav-1 expression in CAFs (using a cell-permeable peptide approach) is sufficient to revert their hyper-proliferative phenotype and prevent RB hyper-phosphorylation. Taken together, these studies highlight the critical role of Cav-1 downregulation in maintaining the abnormal phenotype of human breast cancer-associated fibroblasts.

Abstract-Caveolins (Cav), the principal structural proteins of the caveolar domains, have been implicated in the pathogenesis of ischemic injury. Indeed, changes in caveolin expression and localization have been reported in renal and myocardial ischemia. Genetic ablation of the Cav-1 gene in mice was further shown to increase the extent of ischemic injury in a model of hindlimb ischemia. However, the role of Cav-1 in the pathogenesis of cerebral ischemia remains unknown. Immunoblot and immunofluorescence analyses of rat brains subjected to middle cerebral artery occlusion revealed marked increases in endothelial Cav-1 and Cav-2 protein levels.

Background-Congestive heart failure (CHF) is a disease that is characterized by progressive left ventricular (LV) dysfunction and dilatation. Oxidative stress is thought to contribute to the progression of CHF, and antioxidants have been shown to have beneficial effects when started early after myocardial infarction (MI). In this study, we tested whether the powerful antioxidant probucol would attenuate progression of CHF once it was established after MI in the rat. Methods and Results-Ligation of a coronary artery was used to create an MI in rats (nϭ266). Survivors were then randomized 20 days after MI to either probucol 61 mg · kg Ϫ1 · d Ϫ1 or vehicle and followed up for a total of 100 days after MI. Studies of cardiac hemodynamics, LV remodeling, cardiac apoptosis and morphology, systemic neurohumoral activation, oxidative stress, and renal function were then evaluated. Probucol improved LV function (LV maximum rate of pressure rise from 3103 to 4250 mm Hg/s, PϽ0.05, and LV end-diastolic pressure decrease from 28 to 24 mm Hg, PϽ0.05), reduced pulmonary weights, prevented right ventricular systolic hypertension, and preserved renal function compared with vehicle. Probucol also prevented LV dilatation, prevented wall thinning (1.70 versus 1.42 mm, PϽ0.05), reduced cardiac fibrosis and cardiac apoptosis, attenuated increased myocardial cell cross-sectional area, and increased scar thickness. Conclusions-In

Nestin -cardiomyocytes were identified in the ischemically damaged human/rodent heart, albeit the cellular source, and signaling events implicated in the appearance of the intermediate filament protein remained undefined. Expression of the enhanced green fluorescent protein (EGFP) driven by the second intron of the nestin gene identified a subpopulation of EGFP/nestin cells that differentiated to a vascular phenotype in the peri-infarct/infarct region of post-MI mice albeit the transgene was not detected in nestin -cardiomyocytes. α-MHC-driven expression of the reporter mCherry was detected in troponin-T - and nestin -cardiomyocytes in the peri-infarct/infarct region of post-MI mice. However, the cell cycle re-entry of nestin/mCherry -cardiomyocytes was not observed. Nestin staining was identified in a paucity of neonatal rat ventricular cardiomyocytes (NNVM). Exposure to phorbol 12,13-dibutyrate (PDBu) induced NNVM hypertrophy but did not promote nestin expression or Brdu incorporation. PDBu treatment of NNVMs phosphorylated p38 MAPK and HSP27 and HSP27 phosphorylation was abrogated by the p38 MAPK inhibitor SB203580. PDBu/SB203580 co-treatment significantly increased the percentage of NNVMs that expressed nestin and incorporated Brdu. In the heart of embryonic 10.5 day mice, nestin immunoreactivity was observed in cycling troponin-T -cardiomyocytes. Nestin was also detected in embryonic rat ventricular cardiomyocytes and depletion of the intermediate filament protein attenuated cell cycle re-entry. Thus, nestin expressed by pre-existing cardiomyocytes following ischemic damage recapitulated in part an embryonic trait and may provide the requisite phenotype to initiate cell cycle re-entry. However, the overt activation of the p38 MAPK pathway post-MI may in part limit the appearance and inhibit the cell cycle re-entry of nestin -cardiomyocytes. J. Cell. Physiol. 232: 1717-1727, 2017. © 2016 Wiley Periodicals, Inc.

Both the nonselective ET(A/B) antagonist BSF420627 and the selective ET(A) antagonist LU135252 are effective in this model of PH. Similar direct comparative studies in other models of PH and with various dosage regimens are warranted to define the optimal pharmacological approach of PH when ET receptor antagonists are used.

Neointima formation is a process characterized by smooth muscle cell (SMC) proliferation and extracellular matrix deposition in the vascular intimal layer. Here, we critically evaluate the role of caveolin-1 (Cav-1) in the pathogenesis of neointima formation. Cav-1 and caveolae organelles are particularly abundant in SMCs, where they are thought to function in membrane trafficking and signal transduction events. To directly evaluate the role of Cav-1 in the pathogenesis of neointimal lesions, we used Cav-1-deficient (Cav-1 -/-) mice as a model system. The right common carotid artery of wild-type and Cav-1 -/- mice was ligated just proximal to its bifurcation. Specimens were then harvested 4-weeks postligation and processed for morphometric and immunohistochemical analyses. The carotids of Cav-1 -/- mice showed significantly more intimal hyperplasia with subtotal luminal obstruction, as compared to wild-type mice. These neointimal lesions consisted mainly of SMCs. Mechanistically, neointimal lesions derived from Cav-1 -/- mice exhibited higher levels of phospho-p42/44 MAP kinase and cyclin D1 immunostaining, consistent with the idea that Cav-1 functions as a negative regulator of signal transduction. A significant increase in phospho-Rb (Ser780) immunostaining was also observed, in line with the upregulation of cyclin D1. In conclusion, using a carotid artery blood-flow cessation model, we show that genetic ablation of Cav-1 in mice stimulates SMC proliferation (neointimal hyperplasia), with concomitant activation of the p42/44 MAP kinase cascade and upregulation of cyclin D1. Importantly, our current study is the first to investigate the role of Cav-1 in SMC proliferation in the vascular system using Cav-1 -/- mice.

After large myocardial infarct there is important pulmonary structural remodeling in which myofibroblasts (pericytes) proliferation may play an important role. This initially protective mechanism against high filling pressures could eventually contribute to the development of pulmonary hypertension and right ventricular hypertrophy. Future studies are needed to determine if angiotensin-II directly modulates pulmonary remodeling after myocardial infarct.

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