Doxorubicin induced ROS-dependent HIF1α activation mediates blockage of IGF1R survival signaling by IGFBP3 promotes cardiac apoptosis.

Doxorubicin (Dox) causes the generation of intracellular reactive oxygen species (ROS) and inactivates insulin-like growth factor 1 (IGF1) signaling, leading to cardiomyocyte apoptosis. IGF-binding protein 3 (IGFBP3) is the most abundant circulating IGF1 carrier protein with high affinity, which has been reported to mediate ROS-induced apoptosis. Hypoxia-inducible factor 1α (HIF1A), an upstream protein of IGFBP3 is regulated by prolyl hydroxylase domain (PHD) through hydroxylation. In this study, we investigated the role of IGFBP3, HIF1A, and PHD in Dox-induced cardiac apoptosis.Cells challenged with 1 µM Dox for 24 h increased ROS generation, augmented intracellular and secreted IGFBP3 levels, and reduced IGF1 signaling. Further, we showed that Dox enhanced the extracellular association of IGF1 with IGFBP3. Moreover, echocardiography parameters, especially ejection fraction (EF) and fractional shortening (FS) were significantly reduced in ventricle tissue of Dox challenged rats. Notably, siRNA approach against IGFBP3 or an anti-IGFBP3 antibody rescued Dox-induced cardiac apoptosis, mitochondrial ROS, and the decrease in the IGF1 signaling activity. Furthermore, silencing HIF1A either using siRNA or inhibitor downregulated intracellular IGFBP3, rescued apoptosis, mitochondrial generation, and reduction in IGF1 signaling. Finally, western blot data revealed that ROS scavenger reversed Dox-induced cardiac apoptosis, increased levels of HIF1A and secreted IGFBP3, and decreased IGF1 survival signaling and PHD expression.These findings suggest that Dox-induced ROS generation suppressed PHD, which might stabilize nuclear HIF1A protein, leading to increased IGFBP3 expression and secretion. This in turn results in enhanced extracellular association of the latter with IGF1 and blocks IGF1 pro-survival signaling and may result in inducing cardiac apoptosis.

Diallyl Trisulfide Suppresses High-Glucose-Induced Cardiomyocyte Apoptosis by Targeting Reactive Oxygen Species-Mediated Hypoxia-Inducible Factor-1α/Insulin-like Growth Factor Binding Protein 3 Activation.

It has been reported that 80% of diabetic patients die due to cardiovascular diseases. We previously demonstrated that activated hypoxia-inducible factor-1α (HIF-1 α)/insulin-like growth factor binding protein-3 (IGFBP-3) signaling by reactive oxygen species (ROS)-regulated prolyl hydroxylase domain-containing protein (PHD) is involved in high-glucose (HG)-induced cardiac apoptosis. Diallyl trisulfide (DATS), a garlic component, shows the strongest inhibitory effect on diabetic cardiomyopathy. In this study, we investigated whether HIF-1α/IGFBP-3 signaling governs the antiapoptotic effect by DATS on HG-exposed cardiomyocytes. It was observed that significantly increased levels of cell apoptosis and decreased Akt phosphorylation were reversed by DATS in HG-exposed cardiac cells. H2O2 and PHD small interfering RNA treatments increased HIF-1α and IGFBP-3 protein levels, which were decreased by DATS treatment. Overexpression of HIF-1α and IGFBP-3 increased HG-induced cell apoptosis, which was suppressed by DATS. The coimmunoprecipitation assay results showed that DATS not only increased the IGF-1 level and reduced IGFBP-3 level but also suppressed their extracellular association for cardiac cells exposed to HG. Experiments using neonatal cardiomyocytes and hearts showed similar results. These findings indicate that the effect of ROS-regulated PHD on the activation of HIF-1α/IGFBP-3 signaling governs the antiapoptotic effect by DATS on HG-exposed cardiomyocytes.

Signal transducer and activator of transcription 3 mediates apoptosis inhibition through reducing mitochondrial ROS and activating Bcl-2 in gemcitabine-resistant lung cancer A549 cells.

Lung cancer is a leading cause of cancer-related death worldwide. In this study, we used lung adenocarcinoma cells as a model, as lung adenocarcinoma has the highest mortality rate among all lung cancers. For the past few years, medical treatments or lung cancer have been limited because of chemotherapy resistance. Therefore, understanding the pathogenesis of the development of drug resistance in lung cancer is urgent. Gemcitabine is widely prescribed in the chemotherapeutic treatment of lung cancers. In this study, we developed gemcitabine-resistant lung adenocarcinoma cells (A549-GR) from the A549 cell line. The results showed that apoptotic protein expression and reactive oxygen species (ROS) generation were reduced in A549-GR cells compared to A549 cells. Interestingly, we found that signal transducer and activator of transcription 3 (STAT3) translocated to the nucleus and mitochondria to affect the apoptotic pathway and ROS generation, respectively. Furthermore, treatment with STAT3 small interfering RNA diminished the increase in ROS production, proliferation and antiapoptotic proteins in A549-GR cells. Taken together, the study demonstrated that STAT3 acts as an essential regulator and moderates apoptosis through two major mechanisms to induce gemcitabine resistance in cells; and these findings provide a potential target for the treatment of gemcitabine-resistant lung cancer.

High fat diet aggravates atrial and ventricular remodeling of hypertensive heart disease in aging rats.

BACKGROUND/PURPOSE: Left ventricular hypertrophy is a major cause of heart failure in aging population. This study is to determine whether an excess dietary fat is lipotoxic or lipoprotein to the hypertrophic aging heart. METHODS: At 44-week-old, a normal chow (12% fat) was replaced a high-fat diet (HFD; 45% fat) for randomly selective spontaneously hypertensive rats (SHR + HFD, n = 6) and Wistar-Kyoto rats (WKY + HFD, n = 6, normotensive control). Others (SHR, n = 11; WKY, n = 10) were continuously fed with normal diets. After 27 weeks, electrocardiogram, echocardiography, and femoral arterial catheterization were performed before rats being sacrificed for molecular biology analyses. RESULTS: HFD aggravated cardiac atrial, ventricular dilation and hypertrophy in SHR (LV mass: SHR + HFD 2026.0 ± 424.9 vs SHR 1449 ± 461.1 mg, unpaired t test P < 0.05). HFD caused significant atrial dilatation in both WKY (LA diameter, 5.38 ± 0.36 vs 4.11 ± 0.42 mm, P < 0.001) and SHR (6.13 ± 0.79 vs 4.69 ± 1.00, P < 0.01). Only in SHR, HFD induced significant left ventricular dilatation (LV diameter, 8.87 ± 1.25 vs 7.08 ± 1.00 mm, P < 0.01) and reduced ejection fraction (LVEF, 62.8 ± 11.6 vs 75.1 ± 9.2 mm, P < 0.05). The α-myosin heavy chain was significantly upregulated in atria and ventricles of HFD groups. HFD induced significant upregulation of PPARα, ACADM, and TNFα transcripts in atrial tissues (P < 0.05). CONCLUSION: Hypertensive heart disease in aging rats was aggravated by HFD with worse atrial, ventricular remodeling and associated with left ventricular systolic function impairment.