Induction of ferroptosis by photodynamic therapy and enhancement of antitumor effect with ferroptosis inducers

A caged luciferin analogue generating near-infrared bioluminescence for activity-sensing of labile iron

Iron plays a vital role in physiological processes due to its high oxygen affinity and efficient redox capability. However, perturbations in iron homeostasis, particularly in its labile forms that drive oxidative stress, have been implicated in a spectrum of pathologies, including infectious diseases, malignancies, and neurodegenerative disorders. Despite the critical importance of detecting labile Fe2+, conventional fluorescent and bioluminescent probes are constrained by inherent limitations, such as suboptimal sensitivity, elevated background noise, and inadequate tissue penetration depth. To overcome these challenges, we report the development of a novel caged luciferin analogue, O-Akalumine (O-Aka), designed with an Fe2+-specific switchable N-oxide bond to enable turn-on near-infrared (NIR) bioluminescence imaging of labile Fe2+. The bioluminescence emitted by O-Aka in the presence of native firefly luciferase is centered in the NIR spectrum (λmax = 677 nm), substantially improving signal penetration through biological tissues. Exhibiting low intrinsic background noise, high sensitivity, and deep tissue imaging capability, O-Aka effectively visualized exogenous Fe2+ in cellular models and a murine breast cancer model, as well as endogenous Fe2+ in an acute cardiac injury model. These results underscore the utility of O-Aka as a robust bioluminescent probe for elucidating the physiological and pathological roles of Fe2+ and exploring its potential anticancer mechanisms.

Hypericin mediated photodynamic therapy induces ferroptosis via inhibiting the AKT/mTORC1/GPX4 axis in cholangiocarcinoma

Cholangiocarcinoma remains a challenging primary hepatobiliary malignancy with dismal prognosis. Photodynamic therapy (PDT),a less invasive treatment, has been found to inhibit the proliferation and induce ferroptosis, apoptosis and necrosis in other tumor cells in recent years. Regrettably, the role and exact molecule mechanism of PDT is still incompletely clear in cholangiocarcinoma cells. Ferroptosis is a novel regulated cell death(RCD), which is controlled by glutathione peroxidase4(GPX4) with the characteristics of iron dependent and excessive intracellular accumulation of lipid peroxides. This novel form of RCD has attracted great attention as a potential new target in clinical oncology during recent years. In this study, we observed that hypericin mediated PDT(HY-PDT) could significantly inhibit the proliferation of the cholangiocarcinoma cells and suppress migration and the epithelial mesenchymal transition (EMT) as well. Then, we conducted transcriptome sequencing and bioinformatics analysis and observed that HY-PDT was most likely involved in ferroptosis, apoptosis, the EMT process and AKT/mTORC1 signaling pathways in cholangiocarcinoma cells. Next, a series of in vitro and in vivo experiments were performed to confirm that HY-PDT could trigger cholangiocarcinoma cells ferroptosis through inhibiting the expression of GPX4 protein. In terms of molecular mechanism, we found that HY-PDT induced ferroptosis by decreasing GPX4 expression via suppression of the AKT/mTORC1 signaling pathway. In addition, we also found that HY-PDT inhibit cholangiocarcinoma cells migration and the EMT process by inhibiting the AKT/mTORC1 pathway. Our study illustrated a new mechanism of action for HY-PDT and might throw light on the individualized precision therapy for cholangiocarcinoma patients.

Photodynamic Therapy Using IR-783 Liposomes for Advanced Tongue and Breast Cancers in Humans

Photodynamic therapy (PDT) is a minimally invasive treatment that elicits tumor apoptosis using laser light exclusively applied to the tumor site. IR-783, a heptamethine cyanine (HMC) dye, impedes the proliferation of breast cancer cells, even without light. Although studies have investigated the efficacy of IR-783 in cell and animal studies, its efficacy in clinical settings remains unknown. Therefore, we aimed to determine the efficacy of PDT using IR-783 liposomes. An HMC dye, excited by long-wavelength infrared light and with high tissue permeability, was used for PDT after liposomization to enhance tumor tissue accumulation. PDT was performed using IR-783 in two patients with either tongue or breast cancer, one each. IR-783 liposomes inhibited cell proliferation in tongue cancer cells even when not excited by light. Tumor size was markedly reduced in both cases, with no significant adverse events. Furthermore, the patient with tongue cancer exhibited improved respiratory, swallowing, and speech functions, which were attributed not only to the shrinkage of the tumor but also to the improvement in airway narrowing. In conclusion, PDT using IR-783 liposomes effectively reduces tumor size in tongue and breast cancers.

Emerging insights into ferroptosis in cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is a malignant tumor that arises within the biliary system, which exhibits a progressively increasing incidence and a poor patient prognosis. A thorough understanding of the molecular pathogenesis that drives the progression of CCA is essential for the development of effective molecular target therapeutic approaches. Ferroptosis is driven by excessive iron accumulation and catalysis, lipid peroxidation and the failure of antioxidant defense systems. Key molecular targets of iron metabolism, lipid metabolism and antioxidant defense systems involve molecules such as transferrin receptor, ACSL4 and GPX4, respectively. Inhibitors of ferroptosis include ferrostatin-1, liproxstatin-1, vitamin E and coenzyme Q10. By contrast, compounds such as erastin, RSL3 and FIN56 have been identified as inducers of ferroptosis. Ferroptosis serves a notable role in the onset and progression of CCA. CCA cells exhibit high sensitivity to ferroptosis and aberrant iron metabolism in these cells increases oxidative stress and iron accumulation. The induction of ferroptosis markedly reduces the ability of CCA cells to proliferate and migrate. Certain ferroptosis agonists, such as RSL3 and erastin, cause lipid peroxide build up and GPX4 inhibition to induce ferroptosis in CCA cells. Current serological markers, such as CA-199, have low specificity and cause difficulties in the diagnosis of CCA. However, novel techniques, such as non-invasive liquid biopsy and assays for oxidative stress markers and double-cortin-like kinase 1, could improve diagnostic accuracy. CCA is primarily treated with surgery and chemotherapy. A close association between the progression of CCA with ferroptosis mechanisms and related regulatory pathways has been demonstrated. Therefore, it could be suggested that multi-targeted therapeutic approaches, such as ferroptosis inducers, iron chelating agents and novel modulators such as YL-939, may improve treatment efficacy. Iron death-related genes, such as GPX4, that are highly expressed in CCA and are associated with a poor prognosis for patients may represent potential prognostic markers for CCA. The present review focused on molecular targets such as p53 and ACSL4, the process of targeted medications in combination with PDT in CCA and the pathways of lipid peroxidation, the Xc-system and GSH-GPX4 in ferroptosis. The present review thus offered novel perspectives to improve the current understanding of CCA.

Berberine ameliorates nonalcoholic fatty liver disease-induced bone loss by inhibiting ferroptosis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) may contribute to osteoporosis. Berberine is a traditional Chinese medicine and was recently shown to be beneficial in NAFLD. However, little is known about its impact on bone loss induced by NAFLD.

AIM

We aimed to explore the role of berberine in bone loss and determine its underlying mechanisms in NAFLD.

METHODS

C57BL/6 mice were fed a high-fat high-fructose high-glucose diet (HFFGD) for 16 weeks to establish a NAFLD mouse model. The mice were administered berberine (300 mg/kg/d) by gavage, and fatty liver levels and bone loss indicators were tested.

RESULTS

Berberine significantly improved HFFGD-induced weight gain, hepatic lipid accumulation and increases in serum liver enzymes, thereby alleviating NAFLD. Berberine increased trabecular number (Tb. N), trabecular thickness (Tb. Th), bone volume to tissue volume ratio (BV/TV), and decreased trabecular separation (Tb. Sp) and restored bone loss in NAFLD. Mechanistically, berberine significantly inhibited ferroptosis and 4-hydroxynonenal (4-HNE), prostaglandin-endoperoxide synthase 2 (PTGS2), and transferrin (TF) levels and increased ferritin heavy chain (FTH) levels in the femurs of HFFGD-fed mice. Moreover, berberine also activated the solute carrier family 7 member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) signaling pathway.

CONCLUSION

Berberine significantly ameliorates bone loss induced by NAFLD by activating the SLC7A11/GSH/GPX4 signaling pathway and inhibiting ferroptosis. Therefore, berberine may serve as a therapeutic agent for NAFLD-induced bone loss.

Ferroptosis in Cancer Therapy: Mechanisms, Small Molecule Inducers, and Novel Approaches

Ferroptosis, a unique form of programmed cell death, is initiated by an excess of iron accumulation and lipid peroxidation-induced damage. There is a growing body of evidence indicating that ferroptosis plays a critical role in the advancement of tumors. The increased metabolic activity and higher iron levels in tumor cells make them particularly vulnerable to ferroptosis. As a result, the targeted induction of ferroptosis is becoming an increasingly promising approach for cancer treatment. This review offers an overview of the regulatory mechanisms of ferroptosis, delves into the mechanism of action of traditional small molecule ferroptosis inducers and their effects on various tumors. In addition, the latest progress in inducing ferroptosis using new means such as proteolysis-targeting chimeras (PROTACs), photodynamic therapy (PDT), sonodynamic therapy (SDT) and nanomaterials is summarized. Finally, this review discusses the challenges and opportunities in the development of ferroptosis-inducing agents, focusing on discovering new targets, improving selectivity, and reducing toxic and side effects.

A review on ferroptosis and photodynamic therapy synergism: Enhancing anticancer treatment

Ferroptosis is an iron-dependent programmed cell death modality, which has showed great potential in anticancer treatment. Photodynamic therapy (PDT) is widely used in clinic as an anticancer therapy. PDT combined with ferroptosis-promoting therapy has been found to be a promising strategy to improve anti-cancer therapy efficacy. Fenton reaction in ferroptosis can provide oxygen for PDT, and PDT can produce reactive oxygen species for Fenton reaction to enhance ferroptosis. In this review, we briefly present the importance of ferroptosis in anticancer treatment, mechanism of ferroptosis, researches on PDT induced ferroptosis, and the mechanism of the synergistic effect of PDT and ferroptosis on cancer killing.