Exercise-induced cardiac mitochondrial reorganization and enhancement in spontaneously hypertensive rats.

The myocardium is a highly oxidative tissue in which mitochondria are essential to supply the energy required to maintain pump function. When pathological hypertrophy develops, energy consumption augments and jeopardizes mitochondrial capacity. We explored the cardiac consequences of chronic swimming training, focusing on the mitochondrial network, in spontaneously hypertensive rats (SHR). Male adult SHR were randomized to sedentary or trained (T: 8-week swimming protocol). Blood pressure and echocardiograms were recorded, and hearts were removed at the end of the training period to perform molecular, imaging, or isolated mitochondria studies. Swimming improved cardiac midventricular shortening and decreased the pathological hypertrophic marker atrial natriuretic peptide. Oxidative stress was reduced, and even more interesting, mitochondrial spatial distribution, dynamics, function, and ATP were significantly improved in the myocardium of T rats. In the signaling pathway triggered by training, we detected an increase in the phosphorylation level of both AKT and glycogen synthase kinase-3 ß, key downstream targets of insulin-like growth factor 1 signaling that are crucially involved in mitochondria biogenesis and integrity. Aerobic exercise training emerges as an effective approach to improve pathological cardiac hypertrophy and bioenergetics in hypertension-induced cardiac hypertrophy.

AhR ligand aminoflavone suppresses α6-integrin-Src-Akt signaling to attenuate tamoxifen resistance in breast cancer cells.

More than 40% of patients with luminal breast cancer treated with endocrine therapy agent tamoxifen demonstrate resistance. Emerging evidence suggests tumor initiating cells (TICs) and aberrant activation of Src and Akt signaling drive tamoxifen resistance and relapse. We previously demonstrated that aryl hydrocarbon receptor ligand aminoflavone (AF) inhibits the expression of TIC gene α6-integrin and disrupts mammospheres derived from tamoxifen-sensitive breast cancer cells. In the current study, we hypothesize that tamoxifen-resistant (TamR) cells exhibit higher levels of α6-integrin than tamoxifen-sensitive cells and that AF inhibits the growth of TamR cells by suppressing α6-integrin-Src-Akt signaling. In support of our hypothesis, TamR cells and associated mammospheres were found to exhibit elevated α6-integrin expression compared with their tamoxifen-sensitive counterparts. Furthermore, tumor sections from patients who relapsed on tamoxifen showed enhanced α6-integrin expression. Gene expression profiling from the TCGA database further revealed that basal-like breast cancer samples, known to be largely unresponsive to tamoxifen, demonstrated higher α6-integrin levels than luminal breast cancer samples. Importantly, AF reduced TamR cell viability and disrupted TamR mammospheres while concomitantly reducing α6-integrin messenger RNA and protein levels. In addition, AF and small interfering RNA against α6-integrin blocked tamoxifen-stimulated proliferation of TamR MCF-7 cells and further sensitized these cells to tamoxifen. Moreover, AF reduced Src and Akt signaling activation in TamR MCF-7 cells. Our findings suggest elevated α6-integrin expression is associated with tamoxifen resistance and AF suppresses α6-integrin-Src-Akt signaling activation to confer activity against TamR breast cancer.

Beneficial Consequences of One-Month Oral Treatment with Cannabis Oil on Cardiac Hypertrophy and the Mitochondrial Pool in Spontaneously Hypertensive Rats.

Introduction: It has been demonstrated the dysregulation of the cardiac endocannabinoid system in cardiovascular diseases. Thus, the modulation of this system through the administration of phytocannabinoids present in medicinal cannabis oil (CO) emerges as a promising therapeutic approach. Furthermore, phytocannabinoids exhibit potent antioxidant properties, making them highly desirable in the treatment of cardiac pathologies, such as hypertension-induced cardiac hypertrophy (CH). Objective: To evaluate the effect of CO treatment on hypertrophy and mitochondrial status in spontaneously hypertensive rat (SHR) hearts. Methods: Three-month-old male SHR were randomly assigned to CO or olive oil (vehicle) oral treatment for 1 month. We evaluated cardiac mass and histology, mitochondrial dynamics, membrane potential, area and density, myocardial reactive oxygen species (ROS) production, superoxide dismutase (SOD), and citrate synthase (CS) activity and expression. Data are presented as mean ± SEM (n) and compared by t-test, or two-way ANOVA and Bonferroni post hoc test were used as appropriate. p < 0.05 was considered statistically significant. Results: CH was reduced by CO treatment, as indicated by the left ventricular weight/tibia length ratio, left ventricular mass index, myocyte cross-sectional area, and left ventricle collagen volume fraction. The ejection fraction was preserved in the CO-treated group despite the persistence of elevated systolic blood pressure and the reduction in CH. Mitochondrial membrane potential was improved and mitochondrial biogenesis, dynamics, area, and density were all increased by treatment. Moreover, the activity and expression of the CS were enhanced by treatment, whereas ROS production was decreased and the antioxidant activity of SOD increased by CO administration. Conclusion: Based on the mentioned results, we propose that 1-month oral treatment with CO is effective to reduce hypertrophy, improve the mitochondrial pool and increase the antioxidant capacity in SHR hearts.