New target genes for the peroxisome proliferator-activated receptor-γ (PPARγ) antitumour activity: Perspectives from the insulin receptor

The Role of MicroRNAs in the Pathogenesis of Doxorubicin-Induced Vascular Remodeling

Doxorubicin (DOX), a cornerstone chemotherapeutic agent, effectively combats various malignancies but is marred by significant cardiovascular toxicity, including endothelial damage, chronic heart failure, and vascular remodeling. These adverse effects, mediated by oxidative stress, mitochondrial dysfunction, inflammatory pathways, and dysregulated autophagy, underscore the need for precise therapeutic strategies. Emerging research highlights the critical role of microRNAs (miRNAs) in DOX-induced vascular remodeling and cardiotoxicity. miRNAs, such as miR-21, miR-22, miR-25, miR-126, miR-140-5p, miR-330-5p, miR-146, miR-143, miR-375, miR-125b, miR-451, miR-34a-5p, and miR-9, influence signaling pathways like TGF-β/Smad, AMPKa/SIRT, NF-κB, mTOR, VEGF, and PI3K/AKT/Nrf2, impacting vascular homeostasis, angiogenesis, and endothelial-to-mesenchymal transition. Despite existing studies, gaps remain in understanding the full spectrum of miRNAs involved and their downstream effects on vascular remodeling. This review synthesizes the current knowledge on miRNA dysregulation during DOX exposure, focusing on their dual roles in cardiovascular pathology and tumor progression. Strategies to reduce DOX cardiotoxicity include modulating miRNA expression to restore signaling balance, targeting pro-inflammatory and pro-fibrotic pathways, and leveraging miRNA inhibitors or mimics. This review aims to organize and integrate the existing knowledge on the role of miRNAs in vascular remodeling, particularly in the contexts of DOX treatment and the progression of various cardiovascular diseases, including their potential involvement in tumor growth.

Inhibition of miR-128-3p Attenuated Doxorubicin-Triggered Acute Cardiac Injury in Mice by the Regulation of PPAR-γ

Background

The clinical usefulness of doxorubicin (DOX), an anthracycline with antitumor activity, is limited by its cardiotoxicity. Oxidative stress and myocardial apoptosis were closely associated with DOX-induced cardiac dysfunction. It has been reported that microRNA-128-3p (miR-128-3p) was involved into the regulation of redox balance. However, the role of miR-128-3p in DOX-related cardiac injury remains not yet understood. The aim of this study was to investigate the biological effect of miR-128-3p in DOX-induced cardiotoxicity.

Methods

To induce DOX-related acute cardiac injury, mice were subjected to a single injection of DOX. Inhibition of myocardial miR-128-3p was achieved by an adeno-associated virus (AAV9) system carrying a miR-128-3p sponge.

Results

The data in our study indicated that miR-128-3p was upregulated in DOX-treated hearts and cardiomyocytes. Inhibition of miR-128-3p attenuated DOX-related cardiac injury and improved cardiac function in mice. Moreover, miR-128-3p inhibition could suppress myocardial inflammatory response, oxidative damage, and cell apoptotic death in DOX-treated mice. Further analysis showed that miR-128-3p could directly target peroxisome proliferator-activated receptor γ (PPAR-γ) and decrease PPAR-γ expression. Moreover, the protective effects provided by miR-128-3p inhibition were abolished by a PPAR-γ antagonist in vivo and in vitro.

Conclusions

miR-128-3p inhibition attenuated DOX-related acute cardiac injury via the regulation of PPAR-γ in mice.

Insulin resistance and cancer risk: an overview of the pathogenetic mechanisms

Insulin resistance is common in individuals with obesity or type 2 diabetes (T2D), in which circulating insulin levels are frequently increased. Recent epidemiological and clinical evidence points to a link between insulin resistance and cancer. The mechanisms for this association are unknown, but hyperinsulinaemia (a hallmark of insulin resistance) and the increase in bioavailable insulin-like growth factor I (IGF-I) appear to have a role in tumor initiation and progression in insulin-resistant patients. Insulin and IGF-I inhibit the hepatic synthesis of sex-hormone binding globulin (SHBG), whereas both hormones stimulate the ovarian synthesis of sex steroids, whose effects, in breast epithelium and endometrium, can promote cellular proliferation and inhibit apoptosis. Furthermore, an increased risk of cancer among insulin-resistant patients can be due to overproduction of reactive oxygen species (ROS) that can damage DNA contributing to mutagenesis and carcinogenesis. On the other hand, it is possible that the abundance of inflammatory cells in adipose tissue of obese and diabetic patients may promote systemic inflammation which can result in a protumorigenic environment. Here, we summarize recent progress on insulin resistance and cancer, focusing on various implicated mechanisms that have been described recently, and discuss how these mechanisms may contribute to cancer initiation and progression.

Identification of a molecular signature underlying inhibition of mammary carcinoma growth by dietary N-3 fatty acids

An increased ratio of dietary n-3 relative to n-6 fatty acids has been shown to inhibit the development of mammary cancer in animal models. However, the molecular mechanisms by which n-3 fatty acids affect tumor growth remain unknown. Here, we investigated the effects of varying dietary ratios of n-3:n-6 fatty acids on cell signaling in a rat model of chemically induced mammary carcinoma. Cell proliferation was reduced by 60% in carcinomas from the high n-3:n-6 treatment group compared with the low n-3:n-6 treatment group. These changes were associated with decreased cyclin-D1 and phospho-retinoblastoma protein expression and increased levels of cyclin-dependent kinase inhibitors, CIP1 (p21) and KIP1 (p27). In addition, the apoptotic index was increased in carcinomas from the high n-3:n-6 group and was associated with elevated apoptotic protease-activating factor 1 and a higher ratio of Bax/Bcl-2. Interestingly, changes in protein expression were consistent with reduced inflammation and suppressed mTOR activity, and the molecular signature associated with high n-3:n-6 treatment revealed changes in PPARγ activation and suppression of lipid synthesis. Together, our findings indicate that the molecular effects of high dietary n-3 to n-6 ratios are heterogeneous in nature but point to consistent changes in lipid metabolism pathways, which may serve as potential therapeutic targets for cancer prevention and control. This study identifies the pathways modulated by dietary fatty acid ratios in a rat model of breast cancer, with implications for cancer prevention.