Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025100
Sulfasalazine (SAS), a clinically utilized anti-inflammatory drug, has been shown to induce ferroptosis by inhibiting system Xc− activity, thereby causing cellular glutathione depletion. Recently, protein disulfide isomerase (PDI) was shown to be an upstream mediator of the oxidative cell death (oxytosis/ferroptosis) induced by glutamate, erastin, RSL3 and SAS. The present study aims to further characterize the detailed biochemical and cellular mechanisms of SAS-induced ferroptosis in two cell lines, i.e., H9C2 rat cardiomyocytes and BRL-3A rat hepatocytes, with a focus on elucidating the critical role of PDI in mediating SAS-induced toxicity. We find that SAS can induce ferroptosis in H9C2 and BRL-3A cells, which is accompanied by a sequential increase in the buildup of cellular nitric oxide (NO), reactive oxygen species (ROS) and lipid-ROS. SAS activates PDI-mediated dimerization of inducible NO synthase (iNOS) and cellular accumulation of NO, and these effects are followed by ROS and lipid-ROS accumulation. Furthermore, SAS markedly upregulates the iNOS protein levels in these cells. Knockdown of PDI or pharmacological inhibition of PDI catalytic activity effectively suppresses SAS-induced iNOS dimerization, abrogates SAS-induced accumulation of NO, ROS and lipid-ROS, and prevents ferroptosis. On the other hand, PDI activation through the use of TrxR1 inhibitors sensitizes these cells to SAS-induced ferroptosis. These findings provide further experimental support for a pivotal role of PDI in SAS-induced cytotoxicity through the activation of the PDI-NOS-NO axis, which then leads to the accumulation of cellular ROS and lipid-ROS and ultimately the induction of oxidative cell death.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2024096
Autophagy is a cellular mechanism for self-renewal that involves the breakdown of cytoplasmic proteins or organelles within lysosomes. Although preeclampsia (PE) exhibits several characteristics that could imply disrupted autophagy, there is limited evidence supporting the notion that impaired placental autophagy directly causes PE, as indicated by differential expression profiling of whole placental tissue. In this study, we aim to explore the significance of autophagy in maintaining pregnancy and its association with PE. First, the RNA-seq results show that 218 genes are differentially expressed in placentas from preeclamptic pregnancies. Notably, KEGG pathway analysis reveals significant enrichment of genes related to autophagy-related signaling pathways, including the PI3K-Akt signaling pathway, the AMPK signaling pathway, and the mTOR signaling pathway. Additionally, our findings indicate an increase in autophagy in placentas from pregnancies complicated by preeclampsia as well as in trophoblasts subjected to hypoxic conditions. Next, we examine the impact of 3-methyladenine (3-MA), a targeted inhibitor of autophagy, on the progression of PE. The administration of 3-MA profoundly alleviates the severity of PE-like symptoms in rats subjected to reduced uterine perfusion pressure (RUPP). The findings from our study suggest that inhibiting autophagy may serve as a promising approach for adjuvant chemotherapy for PE.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025100
Sulfasalazine (SAS), a clinically utilized anti-inflammatory drug, induces ferroptosis by inhibiting system Xc− and depleting glutathione. This study characterizes the biochemical and cellular mechanisms of SAS-induced ferroptosis in H9C2 rat cardiomyocytes and BRL-3A rat hepatocytes, focusing on protein disulfide isomerase (PDI). SAS induced ferroptosis with sequential increases in cellular nitric oxide (NO), reactive oxygen species (ROS), and lipid-ROS. SAS activated PDI-mediated dimerization of inducible NO synthase (iNOS) and NO accumulation, followed by ROS and lipid-ROS buildup. SAS also upregulated iNOS protein levels. PDI knockdown or pharmacological inhibition suppressed iNOS dimerization, abrogated NO, ROS, and lipid-ROS accumulation, and prevented ferroptosis. Conversely, PDI activation via TrxR1 inhibitors sensitized cells to SAS-induced ferroptosis. These findings support a pivotal role of the PDI-NOS-NO axis in SAS-induced cytotoxicity, leading to oxidative cell death. The study provides mechanistic insights and suggests strategies for sensitizing cancer cells to SAS-induced ferroptosis.