The role of ferroptosis in prostate cancer: a novel therapeutic strategy

Current and Potential Roles of Ferroptosis in Bladder Cancer

Ferroptosis, a type of regulated cell death driven by iron-dependent lipid peroxidation, is mainly initiated by extramitochondrial lipid peroxidation due to the accumulation of iron-dependent reactive oxygen species. Ferroptosis is a prevalent and primitive form of cell death. Numerous cellular metabolic processes regulate ferroptosis, including redox homeostasis, iron regulation, mitochondrial activity, amino acid metabolism, lipid metabolism, and various disease-related signaling pathways. Ferroptosis plays a pivotal role in cancer therapy, particularly in the eradication of aggressive malignancies resistant to conventional treatments. Multiple studies have explored the connection between ferroptosis and bladder cancer, focusing on its incidence and treatment outcomes. Several biomolecules and tumor-associated signaling pathways, such as p53, heat shock protein 1, nuclear receptor coactivator 4, RAS-RAF-MEK, phosphatidylinositol 3-kinase-AKT-mammalian target of rapamycin, and the Hippo-tafazzin signaling system, exert a moderating influence on ferroptosis in bladder cancer. Ferroptosis inducers, including erastin, artemisinin, conjugated polymer nanoparticles, and quinazolinyl-arylurea derivatives, hold promise for enhancing the effectiveness of conventional anticancer medications in bladder cancer treatment. Combining conventional therapeutic drugs and treatment methods related to ferroptosis offers a promising approach for the treatment of bladder cancer. In this review, we analyze the research on ferroptosis to augment the efficacy of bladder cancer treatment.

Heavy metals, oxidative stress, and the role of AhR signaling

The Aryl Hydrocarbon Receptor (AhR) is a ligand-activated transcriptional factor pivotal in responding to environmental stress and maintaining cellular homeostasis. Exposure to specific xenobiotics or industrial compounds in the environment activates AhR and its subsequent signaling, inducing oxidative stress and related toxicity. Past research has also identified and characterized several classes of endogenous ligands, particularly some tryptophan (Trp) metabolic/catabolic products, that act as AhR agonists, influencing a variety of physiological and pathological states, including the modulation of immune responses and cell death. Heavy metals, being non-essential elements in the human body, are generally perceived as toxic and hazardous, originating either naturally or from industrial activities. Emerging evidence indicates that heavy metals significantly influence AhR activation and its downstream signaling. This review consolidates current knowledge on the modulation of the AhR signaling pathway by heavy metals, explores the consequences of co-exposure to AhR ligands and heavy metals, and investigates the interplay between oxidative stress and AhR activation, focusing on the regulation of immune responses and ferroptosis.

Long noncoding RNA CASC11 suppresses sorafenib-triggered ferroptosis via stabilizing SLC7A11 mRNA in hepatocellular carcinoma cells

As a frontline treatment for patients with advanced hepatocellular carcinoma (HCC), sorafenib is an effective drug approved by the Food and Drug Administration (FDA). Ferroptosis, a newly defined programmed cell death process with the hallmark of the accumulation of iron-dependent lipid peroxides, can be induced by sorafenib treatment. Our previous study identified oncogenic roles of long noncoding RNA (lncRNA) Cancer susceptibility candidate 11 (CASC11) in HCC progression. However, the relationship between CASC11 and sorafenib-induced ferroptosis in HCC remains unclear. In the present study, we aim to investigate the role of CASC11 in sorafenib-induced ferroptosis in HCC cell lines and determine the involved molecular mechanisms. Here, we demonstrated that sorafenib decreased CASCL11 expression. Knockdown of CASC11 enhanced sorafenib-induced ferroptosis, while overexpression of CASC11 exerted the opposite effect in HCC cells. Moreover, CASC11 led to the accumulation of intracellular malondialdehyde (MDA), lipid reactive oxygen species (ROS) and Fe2+ while depleting glutathione (GSH), thereby suppressing sorafenib-induced ferroptosis and cell death. Ferrostatin-1 (Ferr-1), a ferroptosis inhibitor, reversed the enhanced anticancer effect of sorafenib caused by the silence of CASC11 in HCC cells. Mechanistically, CASC11 upregulated the expression of solute carrier family 7 member 11 (SLC7A11) which is critical for ferroptosis inhibition. CASC11 associated with and stabilized SLC7A11 mRNA. In summary, our data revealed, for the first time, that CASC11 inhibits the sorafenib-induced ferroptosis in HCC cells via regulating SLC7A11, providing a new basis for clinical therapeutic strategies for patients with HCC.

Cysteine depletion sensitizes prostate cancer cells to agents that enhance DNA damage and to immune checkpoint inhibition

BACKGROUND

Prostate Cancer (PCa) represents one of the most commonly diagnosed neoplasms in men and is associated with significant morbidity and mortality. Therapy resistance and significant side effects of current treatment strategies indicate the need for more effective agents to treat both androgen-dependent and androgen-independent PCa. In earlier studies, we demonstrated that depletion of L-cysteine/cystine with an engineered human enzyme, Cyst(e)inase, increased intracellular ROS levels and inhibited PCa growth in vitro and in vivo. The current study was conducted to further explore the mechanisms and potential combinatorial approaches with Cyst(e)inase for treatment of PCa.

METHODS

DNA single strand breaks and clustered oxidative DNA damage were evaluated by alkaline comet assay and pulsed field gel electrophoresis, respectively. Neutral comet assay and immunofluorescence staining was used to measure DNA double strand breaks. Cell survival and reactive oxygen species level were measured by crystal violet assay and DCFDA staining, respectively. Western blot was used to determine protein expression. FACS analyses were preformed for immune cell phenotyping. Allograft and xenograft tumor models were used for assessing effects on tumor growth.

RESULTS

PCa cells treated with Cyst(e)inase lead to DNA single and double strand breaks resulted from clustered oxidative DNA damage (SSBs and DSBs). Cyst(e)inase in combination with Auranofin, a thioredoxin reductase inhibitor, further increased intracellular ROS and DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo. A combination of Cyst(e)inase with a PARP inhibitor (Olaparib) also increased DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo without additional ROS induction. Knockdown of BRCA2 in PCa cells increased DSBs and enhanced sensitivity to Cyst(e)inase. Finally, Cyst(e)inase treatment altered tumor immune infiltrates and PD-L1 expression and sensitized PCa cells to anti-PD-L1 treatment.

CONCLUSIONS

The current results demonstrate the importance of oxidative DNA damage either alone or in combination for Cyst(e)inase-induced anticancer activity. Furthermore, cysteine/cystine depletion alters the tumor immune landscape favoring enhanced immune checkpoint inhibition targeting PD-L1. Thus, combinatorial approaches with Cyst(e)inase could lead to novel therapeutic strategies for PCa.

The Carotenoid Diatoxanthin Modulates Inflammatory and Angiogenesis Pathways In Vitro in Prostate Cancer Cells

Xanthophylls, a group of carotenoids, have attracted attention as human health benefit compounds thanks to their functionality and bioavailability. The great antioxidant and anti-inflammatory abilities of diatoxanthin (Dt), a photoprotective xanthophyll synthetized by diatoms, were recently documented. This study investigates the capacity of Dt to intercept prostate cancer progression in vitro on different human cell lines, exploring its role against cancer proliferation and angiogenesis. Our results highlighted the chemopreventive role of Dt already at low concentration (44.1 pM) and suggest that the Dt-induced cancer cell death occurred through oxidative stress mechanisms. This hypothesis was supported by variations on the expression of key genes and proteins. Oxidative stress cell deaths (e.g., ferroptosis) are recently described types of cell death that are closely related to the pathophysiological processes of many diseases, such as tumors. Nonetheless, the interest of Dt was further strengthened by its ability to inhibit angiogenesis. The results are discussed considering the actual progress and requirements in cancer therapy, notably for prostate cancer.