Berberine protects cardiac cells against ferroptosis.

Objectives: Cardiovascular diseases are one of the primary causes of death. Cardiomyocyte loss is a significant feature of cardiac injury. Ferroptosis is iron-dependent cell death, which occurs due to excess iron and reactive oxygen species (ROS) accumulation causing lipid peroxidation, and subsequent cell death. Ferroptosis has been confirmed to mediate ischemia/reperfusion-induced cardiomyopathy and chemotherapy-induced cardiotoxicity. Berberine (BBR) has been proven to protect the heart from cardiomyopathies, including cardiac hypertrophy, heart failure, myocardial infarction, and arrhythmias. It protects cardiomyocytes from apoptosis and autophagy. However, the relation between BBR and ferroptosis is still unknown. This study aimed to confirm if BBR reduces cardiac cell loss via inhibiting ferroptosis. Materials and Methods: We used erastin and Ras-selective lethal small molecule 3 (RSL3) to establish a ferroptosis model in an H9c2 cardiomyoblast cell line and rat neonatal cardiomyocytes to prove that BBR has a protective effect on cardiac cells via inhibiting ferroptosis. Results: In H9c2 cardiomyoblasts, the results showed that BBR reduced erastin and RSL3-induced cell viability loss. Moreover, BBR decreased ROS accumulation and lipid peroxidation in cells induced with ferroptosis. Furthermore, quantitative polymerase chain reaction results showed that Ptgs2 mRNA was reduced in BBR-treated cells. In rat neonatal cardiomyocytes, BBR reduced RSL3-induced loss of cell viability. Conclusion: These results indicated that BBR inhibited ferroptosis via reducing ROS generation and reducing lipid peroxidation in erastin and RSL3-treated cardiac cells.

Progesterone Prevents High-Grade Serous Ovarian Cancer by Inducing Necroptosis of p53-Defective Fallopian Tube Epithelial Cells.

High-grade serous ovarian carcinoma (HGSOC) originates mainly from the fallopian tube (FT) epithelium and always carries early TP53 mutations. We previously reported that tumors initiate in the FT fimbria epithelium because of apoptotic failure and the expansion of cells with DNA double-strand breaks (DSB) caused by bathing of the FT epithelial cells in reactive oxygen species (ROSs) and hemoglobin-rich follicular fluid (FF) after ovulation. Because ovulation is frequent and HGSOC is rare, we hypothesized that luteal-phase progesterone (P4) could eliminate p53-defective FT cells. Here we show that P4, via P4 receptors (PRs), induces necroptosis in Trp53-/- mouse oviduct epithelium and in immortalized human p53-defective fimbrial epithelium through the TNF-α/RIPK1/RIPK3/MLKL pathway. Necroptosis occurs specifically at diestrus, recovers at the proestrus phase of the estrus cycle, and can be augmented with P4 supplementation. These results reveal the mechanism of the well-known ability of progesterone to prevent ovarian cancer.

Inducible nitric oxide synthase mediates MG132 lethality in leukemic cells through mitochondrial depolarization.

Proteasomes are highly expressed in rapidly growing neoplastic cells and essential for controlling the cell cycle process and mitochondrial homeostasis. Pharmacological inhibition of the proteasome shows a significant anticancer effect on hematopoietic malignancies that is usually associated with the generation of reactive oxygen species. In this study, we comprehensively investigated the role of endogenous oxidants in various cellular events of K562 leukemic cells in response to treatment with MG132, a proteasome inhibitor. MG132 at 1.4 µM potently triggered G2/M arrest, mitochondrial depolarization, and apoptosis. By such treatment, the protein level of inducible nitric oxide synthase (iNOS) was doubled and cellular oxidants, including nitric oxide, superoxide, and their derivatives, were increasingly produced. In MG132-treated cells, the increase in iNOS-derived oxidants was responsible for mitochondrial depolarization and caspase-dependent apoptosis, but was insignificant in G2/M arrest. The amount of iNOS was negatively correlated with that of manganese superoxide dismutase (MnSOD). Whereas iNOS activity was inhibited by aminoguanidine, cellular MnSOD levels as well as mitochondrial membrane potentials were upregulated, and consequentially G2/M arrest and apoptosis were thoroughly reversed. It is suggested that cells rich in functional mitochondria possess improved proteasome activity, which antagonizes the cytotoxic and cytostatic effects of MG132. In contrast to iNOS, endothelial NOS-driven cGMP-dependent signaling promoted mitochondrial function and survival of MG132-stressed cells. In conclusion, the functional interplay of proteasomes and mitochondria is crucial for leukemic cell growth, wherein iNOS plays a key role.

Regulatory mechanisms controlling human E-cadherin gene expression.

In cancer cells, loss of E-cadherin gene expression caused dysfunction of the cell-cell junction system, triggering cancer invasion and metastasis. Therefore, E-cadherin is an important tumor-suppressor gene. To understand how E-cadherin gene expression is regulated in cancer cells, we have used E-cadherin-positive and -negative expressing cells to find out the possible up- or down regulating transcription factors in human E-cadherin regulatory sequences. Functional analysis of human E-cadherin regulatory sequences constructs indicated that AML1, Sp1, and p300 may play important roles in promoting E-cadherin expression. In addition, we found there are four HNF3-binding sites in human E-cadherin regulatory sequences. The exogenous HNF3 can enhance the E-cadherin promoter activity in metastatic breast cancer cells and the metastatic breast cancer cells stably transfected with HNF3 showed re-expression of E-cadherin. The HNF3 stable transfectants changed from mesenchymal-like into epithelial morphology. The transwell assays showed the re-expressed E-cadherin reduced cell motility of metastatic breast cancer cells. These results suggested HNF3 may play important roles in the upregulation of the E-cadherin promoter, with the consequent re-expression of E-cadherin, thus reducing the metastatic potential of breast cancer cells. These findings suggested HNF3 plays important roles in the upregulation of the E-cadherin gene and may be able to reduce the motility of metastatic breast cancer cells.