Combination therapy with HSP90 inhibitors and piperlongumine promotes ROS-mediated ER stress in colon cancer cells

Membrane Encapsulated Fe3O4@MnO@cGAMP Nanocatalyst for Cancer Therapy: cGAS-STING Immune Pathway Activation

Reactive oxygen species (ROS) mediated cell damage is one of the most popular and effective ways for cancer therapy. However, overexpressed antioxidant of reduced glutathione (GSH) is always activated in tumor cells, which maintains redox equilibrium. Attempts to deplete GSH and elevate ROS levels can be potent therapeutic strategies. Herein, tumor cell membrane-encapsulated Fe3O4@MnO and 2',3'-cyclic GMP-AMP (cGAMP) are prepared as the nanocatalyst for cancer therapy. The ionized Fe3+/Fe2+ redox couple is utilized to initiate the Fenton reaction. Intracellular GSH level can thus be efficaciously controlled, and peroxide oxidation is catalyzed to produce excessive ROS. Meanwhile, cGAMP is released to trigger the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling axis. This targeted activation enhances the recruitment of macrophages, stimulates the secretion of critical pro-inflammatory cytokines, and consequently bolsters the efficacy of innate immune responses within the tumor microenvironment.

Piperlongumine Inhibits Lung Cancer Growth by Inducing Endoplasmic Reticulum Stress Leading to Suppression of M2 Macrophage Polarization

Lung cancer is the leading cause of cancer-related deaths globally. Prolonged targeted therapy use can lead to drug resistance and target mismatches, necessitating more effective and safer treatment strategies. Recent research has focused on the tumor microenvironment, which includes immune and stromal cells that play roles in tumor proliferation, metastasis, and neovascularization. Tumor-associated macrophages (TAMs) are key immune cells in the tumor microenvironment, promoting tumor invasion, metastasis, and immune escape. Their infiltration density in lung cancer tissue is a poor prognostic factor. Piperlongumine (PL), extracted from Piper longum, possesses antitumor and anti-inflammatory properties, inducing apoptosis and inhibiting invasion and metastasis in lung cancer cells. This study aims to elucidate the correlation between endoplasmic reticulum stress (ERS) in lung cancer cells and M2-type TAM polarization and the role of PL in regulating lung cancer progression. The network pharmacologic analysis revealed that Piperlongumine inhibits lung cancer progression by inducing endoplasmic reticulum stress. In vivo experiments demonstrated that Piperlongumine significantly reduced tumor volume and decreased the proportion of M2-type macrophages. Within the co-culture system, lung cancer cells were shown to promote macrophage M2-type polarization and enhance cancer cell migration. Piperlongumine effectively inhibited these effects by inducing endoplasmic reticulum stress in cancer cells, thereby reducing M2 polarization and cell migration. The addition of endoplasmic reticulum stress inhibitor 4-PBA counteracted Piperlongumine's effects, further underscoring the crucial role of ERS in the treatment mechanism. Piperlongumine suppresses lung cancer growth by inducing endoplasmic reticulum stress, which inhibits macrophage M2-type polarization and reduces cell migration. These findings support Piperlongumine's potential as a therapeutic agent and offer a foundation for targeting endoplasmic reticulum stress to modulate TAM function in lung cancer treatment.

Icaritin Represses Autophagy to Promote Colorectal Cancer Cell Apoptosis and Sensitized Low-Temperature Photothermal Therapy via Targeting HSP90-TXNDC9 Interactions

Colorectal cancer (CRC) ranks among the leading causes of cancer-related dea ths worldwide, and the rising incidence and mortality of CRC underscores the urgent need for better understanding and management strategies. Icaritin (ICA) is the metabolites of icariin, a natural flavonoid glycoside compound derived from the stems and leaves of Epimedium. It has broad spectrum antitumor activity and inhibits the proliferation, migration, and invasion of CRC cells, and causes S phase cell cycle arrest. It exerts its antitumor effects against CRC through repressing autophagy to promote CRC cell apoptosis via interfering the HSP90-TXNDC9 interactions. The safety and efficacy of ICA are also affirmed in a mouse xenograft model. Additionally, to test whether ICA exerts synergistic effects with low-temperature photothermal therapy (LTPTT), a novel nanodrug delivery system, employing SiO2 nanocarriers, is designed aiming to load ICA with photothermal materials polydopamine (PDA), and folic acid (FA). This SiO2/Ica-PDA-FA multifunctional nanocomposite actively targets tumor tissues through the high affinity of FA for cancer cells. Once internalized, the acidic intracellular environment triggers the controlled release of ICA, inhibiting HSP90-TXNDC9 interactions. By LTPTT and ICA drug therapy under near-infrared illumination, a dual synergistic antitumor effect is achieved, holding promise for enhancing therapeutic outcomes in CRC treatment.

Inhibiting HSP90 changes the expression pattern of PINK1 and BNIP3 and induces oxidative stress in colon cancer cells

BACKGROUND

Cancer cells can modulate the expression of many proteins that are essential for supporting their uncontrolled proliferation. Heat shock protein 90 (HSP90) is ubiquitously expressed in most cell types and participates in controlling many survival pathways. Cancer cells utilize HSP90 in order to prolong their survival, thus they tend to overexpress it. Based on its importance for cancer cells, we aim to investigate the molecular mechanisms that link HSP90 inhibition in colon cancer cells with oxidative stress and mitochondrial stress-related regulators.

MATERIALS AND METHODS

We used RKO colon cancer cells, blocking HSP90 with the inhibitor AT13387 and HSP90 siRNA. Cell proliferation and apoptosis were measured via CCK8 ELISA and Fluorescent Apoptosis Assays. Western blotting and immunocytochemistry assessed oxidative and mitochondrial stress markers BNIP3, PINK1, GP91/NOX2, and IRE1α in treated cells.

RESULTS

Our findings reveal that inhibiting HSP90 with AT13387 reduces RKO cell viability by suppressing proliferation and enhancing Annexin-V expression, indicative of increased apoptosis. This rise in apoptosis is associated with PINK1 downregulation and BNIP3 upregulation, markers of mitochondrial dysfunction and oxidative stress, respectively. Additionally, AT13387 treatment elevated the protein level of GP91, a marker of oxidative stress, and IRE1α, a marker of ER stress. Similarly, genetic knockdown of HSP90 in RKO cells produced comparable effects, including reduced cell survival and a decreased PINK1/BNIP3 ratio.

CONCLUSION

Targeting HSP90 in colon cancer cells disrupts their survival by decreasing PINK1 and increasing BNIP3, which activates oxidative and endoplasmic reticulum stress, ultimately triggering apoptosis.

Endoplasmic Reticulum Stress Induces ROS Production and Activates NLRP3 Inflammasome Via the PERK-CHOP Signaling Pathway in Dry Eye Disease

Purpose

The purpose of this study was to investigate the potential roles of endoplasmic reticulum (ER) stress in the development of dry eye disease (DED).

Methods

Single-cell RNA sequencing (scRNA-seq) data from the Gene Expression Omnibus (GEO) database, derived from corneal tissues of a dry eye mouse model, was processed using the Seurat R program. The results were validated using a scopolamine-induced dry eye mouse model and a hyperosmotic-induced cell model involving primary human corneal epithelial cells (HCECs) and immortalized human corneal epithelial (HCE-2) cells. The HCE-2 cells were treated with 4-phenylbutyric acid (4-PBA) or tunicamycin (TM) to modulate ER stress. TXNIP and PERK knockdown were performed by siRNA transfection. Immunofluorescence, Western blotting, and real-time PCR were used to assess oxidative stress, ER stress, unfolded protein response (UPR) marker proteins, and TXNIP/NLRP3 axis activation.

Results

The analysis of scRNAseq data shows an increase in the ER stress marker GRP78, and the activation of the PERK-CHOP of UPR in DED mouse. These findings were confirmed both in vivo and in vitro. Additionally, HCE-2 cells treated with 4-PBA or TM showed significant effects on the production of reactive oxygen species (ROS) and the activation of the TXNIP/NLRP3-IL1β signaling pathway. Furthermore, siRNA knockdown of PERK or TXNIP, which alleviated the TXNIP/NLRP3-IL1β signaling axis, showed protective effects on HCECs.

Conclusions

This study explores the role of ER stress-induced oxidative stress and NLRP3-IL-1β mediated inflammation in DED, and highlights the therapeutic potential of PERK-CHOP axis and TXNIP in the treatment of DED.

Small molecules for impairing endoplasmic reticulum in cancer

The endoplasmic reticulum plays an important role in maintaining the protein homeostasis of cells as well as regulating Ca2+ storage. An increased load of unfolded proteins in the endoplasmic reticulum due to alterations in the cell's metabolic pathway leads to the activation of the unfolded protein response, also known as ER stress. ER stress plays a major role in maintaining the growth and survival of various cancer cells, but persistent ER stress can also lead to cell death and hence can be a therapeutic pathway in the treatment of cancer. In this review, we focus on different types of small molecules that impair different ER stress sensors, the protein degradation machinery, and chaperone proteins. We also review the metal complexes and other miscellaneous compounds inducing ER stress through multiple mechanisms. Finally, we discuss the challenges in this emerging area of research and the potential direction of research to overcome them towards next-generation ER-targeted cancer therapy.

Apigenin improves testosterone synthesis by regulating endoplasmic reticulum stress

Obesity is a growing epidemic among reproductive-age men, which can cause and exacerbate male infertility by means of associated comorbidities, endocrine abnormalities, and direct effects on the fidelity and throughput of spermatogenesis. A prominent consequence of male obesity is a reduction in testosterone levels. Natural products have shown tremendous potential anti-obesity effects in metabolic diseases. This study aimed to investigate the potential of apigenin (AP) to alleviate testicular dysfunction induced by a high-fat diet (HFD) and to investigate the underlying mechanisms, focusing on endoplasmic reticulum stress (ERS) and testosterone synthesis. A murine model of obesity was established using HFD-fed mice. The effects of AP on obesity, lipid metabolism, testicular dysfunction, and ERS were assessed through various physiological, histological, and molecular techniques. Administration of AP (10 mg/kg) ameliorated HFD-induced obesity and testicular dysfunction in a mouse model, as evidenced by decreased body weight, improved lipid profiles and testicular pathology, and restored protein levels related to testosterone. Furthermore, in vitro studies demonstrated that AP relieved ERS and recovered testosterone synthesis in murine Leydig cells (TM3) treated with free fatty acids (FFAs). It was also observed that AP rescued testosterone synthesis enzymes in TM3 cells, similar to that observed with the inhibitor of the PERK pathway (GSK2606414). In addition, ChIP, qPCR, and gene silencing showed that the C/EBP homologous protein (CHOP) bound directly to the promoter region of steroidogenic STAR and negatively modulated its expression. Collectively, AP has remarkable potential to alleviate HFD-induced obesity and testicular dysfunction. Its protective effects are attributable partly to mitigating ERS and restoring testosterone synthesis in Leydig cells.

RIOK3 sustains colorectal cancer cell survival under glucose deprivation via an HSP90α-dependent pathway

Glucose oxidation via the pentose phosphate pathway serves as the primary cellular mechanism for generating nicotinamide adenine dinucleotide phosphate (NADPH). The central regions of solid tumors typically experience glucose deficiency, emphasizing the need for sustained NADPH production crucial to tumor cell survival. This study highlights the crucial role of RIOK3 in maintaining NADPH production and colorectal cancer (CRC) cell survival during glucose deficiency. Our findings revealed upregulated RIOK3 expression upon glucose deprivation, with RIOK3 knockout significantly reducing cancer cell survival. Mechanistically, RIOK3 interacts with heat shock protein 90α (HSP90α), a chaperone integral to various cellular processes, thereby facilitating HSP90α binding to isocitrate dehydrogenase 1 (IDH1). This interaction further upregulates IDH1 expression, enhancing NADPH production and preserving redox balance. Furthermore, RIOK3 inhibition had no discernible effect on intracellular NADPH levels and cell death rates in HSP90α-knockdown cells. Collectively, our findings suggest that RIOK3 sustains colon cancer cell survival in low-glucose environments through an HSP90α-dependent pathway. This highlights the significance of the RIOK3-HSP90α-IDH1 cascade, providing insights into potential targeted therapeutic strategies for CRC in metabolic stress conditions.