Non-apoptotic cell death-based cancer therapy: Molecular mechanism, pharmacological modulators, and nanomedicine

Recent advancements in nanomaterial-mediated ferroptosis-induced cancer therapy: Importance of molecular dynamics and novel strategies

Ferroptosis is a novel type of controlled cell death resulting from an imbalance between oxidative harm and protective mechanisms, demonstrating significant potential in combating cancer. It differs from other forms of cell death, such as apoptosis and necrosis. Molecular therapeutics have hard time playing the long-acting role of ferroptosis induction due to their limited water solubility, low cell targeting capacity, and quick metabolism in vivo. To this end, small molecule inducers based on biological factors have long been used as strategy to induce cell death. Research into ferroptosis and advancements in nanotechnology have led to the discovery that nanomaterials are superior to biological medications in triggering ferroptosis. Nanomaterials derived from iron can enhance ferroptosis induction by directly releasing large quantities of iron and increasing cell ROS levels. Moreover, utilizing nanomaterials to promote programmed cell death minimizes the probability of unfavorable effects induced by mutations in cancer-associated genes such as RAS and TP53. Taken together, this review summarizes the molecular mechanisms involved in ferroptosis along with the classification of ferroptosis induction. It also emphasized the importance of cell organelles in the control of ferroptosis in cancer therapy. The nanomaterials that trigger ferroptosis are categorized and explained. Iron-based and noniron-based nanomaterials with their characterization at the molecular and cellular levels have been explored, which will be useful for inducing ferroptosis that leads to reduced tumor growth. Within this framework, we offer a synopsis, which traverses the well-established mechanism of ferroptosis and offers practical suggestions for the design and therapeutic use of nanomaterials.

Combination treatment with ferroptosis and autophagy inducers significantly inhibit the proliferation and migration of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC), a malignancy originating from mucosal epithelial cells. Currently, triggering apoptotic cell death with anticancer drugs is the main way to inhibit OSCC cells. However, the capability to trigger apoptosis in tumors is constrained by the intrinsic resistance of tumor cells to apoptosis, hampering its effectiveness. Thus, utilizing alternative modes of non-apoptotic cell death offers new therapeutic possibilities, such as using a drug combination strategy to simultaneously induce ferroptosis and autophagy has the potential to improve OSCC therapy. In this study, we found the ferroptosis inducer RSL3 has certain inhibitory effects on the proliferation and migration of OSCC cells. Interestingly, our studies showed that RSL3 is also associated with autophagy activation. Based on this finding, we tried to combine RSL3 with the autophagy inducer LYN-1604 to improve the therapeutic effect. The results demonstrated that simultaneous regulation of autophagy and ferroptosis significantly reduced the proliferation and migration of OSCC cells. Taken together, we demonstrated the therapeutic potential of RSL3 in OSCC cells and proposed that simultaneous activation of autophagy and ferroptosis have synergistic effects, which would provide valuable clues for further exploration of targeted therapy for OSCC.

Targeting Ferroptosis as a Therapeutic Implication in Lung Cancer Treatment by a Novel Naphthoquinone Inducer: Juglone

Lung cancer has garnered significant global attention as a result of its escalating rates of mortality and morbidity, necessitating focused interventions to mitigate its impact. The primary aim of this work was to investigate the anticancer activity of juglone in A549 cells, specifically focusing on its role in mediating ferroptosis. We conducted an investigation involving a range of cytotoxic and morphological assays, such as cell viability assay, fluorescence microscopic analysis, flow cytometry, and ROS assay. The findings demonstrated that the cytotoxicity of juglone was around 18.5 μM. Furthermore, the chemical was found to promote apoptotic activity as observed through fluorescent microscopic inspection and morphological analysis. In addition, the levels of ROS, MDA, GSH, ferrous iron, and colony formation study demonstrated a significant increase, indicating a correlation with the occurrence of ferroptosis. Hence, juglone exhibits promise as a prospective therapeutic drug in the treatment of lung cancer. Therefore, we put forward that the utilization of ferroptosis as a therapeutic approach for lung cancer may yield significant efficacy and warrants further investigation in subsequent studies.

Excavatolide C/cisplatin combination induces antiproliferation and drives apoptosis and DNA damage in bladder cancer cells

Excavatolide C (EXCC), a marine coral-derived compound, exhibits an antiproliferation effect on bladder cancer cells. The present study evaluated the improvement in the antiproliferation ability of EXCC by co-treatment with cisplatin in bladder cancer cells. EXCC/cisplatin (12.5 and 1 μg/mL) showed higher antiproliferation effects on bladder cancer cells than single treatments (EXCC or cisplatin alone) in the 48 h ATP assay. EXCC/cisplatin also enhanced the increase in subG1, annexin V-mediated apoptosis, and activation of poly (ADP-ribose) polymerase (PARP) and several caspases (caspases 3, 8, and 9) compared to the single treatments. Cellular and mitochondrial oxidative stress was enhanced with EXCC/cisplatin compared to the single treatments according to analyses of reactive oxygen species (ROS), mitochondrial superoxide, and mitochondrial membrane potential; in addition, cellular antioxidants, such as glutathione (GSH), and the mRNA expressions of antioxidant signaling genes (catalase and NFE2-like bZIP transcription factor 2) were downregulated. EXCC/cisplatin treatment produced more DNA damage than the single treatments, as indicated by γH2AX and 8-hydroxy-2'-deoxyguanosine levels. Moreover, several DNA repair genes for homologous recombination (HR) and non-homologous end joining (NHEJ) were downregulated in EXCC/cisplatin compared to others. The addition of the GSH precursor N-acetylcysteine, which has ROS scavenging activity, attenuated all EXCC/cisplatin-induced changes. Notably, EXCC/cisplatin showed lower antiproliferation, apoptosis, ROS induction, GSH depletion, and γH2AX DNA damage in normal cells than in bladder cancer cells. Therefore, the co-treatment of EXCC/cisplatin reduces the proliferation of bladder cancer cells via oxidative stress-mediated mechanisms with normal cell safety.

A ferroptosis amplifier based on triple-enhanced lipid peroxides accumulation strategy for effective pancreatic cancer therapy

As an iron dependent regulatory cell death process driven by excessive lipid peroxides (LPO), ferroptosis is recognized as a powerful weapon for pancreatic cancer (PC) therapy. However, the tumor microenvironment (TME) with hypoxia and elevated glutathione (GSH) expression not only inhibits LPO production, but also induces glutathione peroxidase 4 (GPX4) mediated LPO clearance, which greatly compromise the therapeutic outcomes of ferroptosis. To address these issues, herein, a novel triple-enhanced ferroptosis amplifier (denoted as Zal@HM-PTBC) is rationally designed. After intravenous injection, the overexpressed H2O2/GSH in TME induces the collapse of Zal@HM-PTBC and triggers the production of oxygen and reactive oxygen species (ROS), which synergistically amplify the degree of lipid peroxidation (broaden sources). Concurrently, GSH consumption because of the degradation of the hollow manganese dioxide (HM) significantly weakens the activity of GPX4, resulting in a decrease in LPO clearance (reduce expenditure). Moreover, the loading and site-directed release of zalcitabine further promotes autophagy-dependent LPO accumulation (enhance effectiveness). Both in vitro and in vivo results validated that the ferroptosis amplifier demonstrated superior specificity and favorable therapeutic responses. Overall, this triple-enhanced LPO accumulation strategy demonstrates the ability to facilitate the efficacy of ferroptosis, injecting vigorous vitality into the treatment of PC.

A promising future of metal-N-heterocyclic carbene complexes in medicinal chemistry: The emerging bioorganometallic antitumor agents

Metal complexes based on N-heterocyclic carbene (NHC) ligands have emerged as promising broad-spectrum antitumor agents in bioorganometallic medicinal chemistry. In recent decades, studies on cytotoxic metal-NHC complexes have yielded numerous compounds exhibiting superior cytotoxicity compared to cisplatin. Although the molecular mechanisms of these anticancer complexes are not fully understood, some potential targets and modes of action have been identified. However, a comprehensive review of their biological mechanisms is currently absent. In general, apoptosis caused by metal-NHCs is common in tumor cells. They can cause a series of changes after entering cells, such as mitochondrial membrane potential (MMP) variation, reactive oxygen species (ROS) generation, cytochrome c (cyt c) release, endoplasmic reticulum (ER) stress, lysosome damage, and caspase activation, ultimately leading to apoptosis. Therefore, a detailed understanding of the influence of metal-NHCs on cancer cell apoptosis is crucial. In this review, we provide a comprehensive summary of recent advances in metal-NHC complexes that trigger apoptotic cell death via different apoptosis-related targets or signaling pathways, including B-cell lymphoma 2 (Bcl-2 family), p53, cyt c, ER stress, lysosome damage, thioredoxin reductase (TrxR) inhibition, and so forth. We also discuss the challenges, limitations, and future directions of metal-NHC complexes to elucidate their emerging application in medicinal chemistry.

Bioorthogonal/Ultrasound Activated Oncolytic Pyroptosis Amplifies In Situ Tumor Vaccination for Boosting Antitumor Immunity

Personalized in situ tumor vaccination is a promising immunotherapeutic modality. Currently, seeking immunogenic cell death (ICD) to generate in situ tumor vaccines is still mired by insufficient immunogenicity and an entrenched immunosuppressive tumor microenvironment (TME). Herein, a series of tetrazine-functionalized ruthenium(II) sonosensitizers have been designed and screened for establishing a bioorthogonal-activated in situ tumor vaccine via oncolytic pyroptosis induction. Based on nanodelivery-augmented bioorthogonal metabolic glycoengineering, the original tumor is selectively remolded to introduce artificial target bicycle [6.1.0] nonyne (BCN) into cell membrane. Through specific bioorthogonal ligation with intratumoral BCN receptors, sonosensitizers can realize precise membrane-anchoring and synchronous click-activation in desired tumor sites. Upon ultrasound (US) irradiation, the activated sonosensitizers can intensively disrupt the cell membrane with dual type I/II reactive oxygen species (ROS) generation for a high-efficiency sonodynamic therapy (SDT). More importantly, the severe membrane damage can eminently evoke oncolytic pyroptosis to maximize tumor immunogenicity and reverse immunosuppressive TME, ultimately eliciting powerful and durable systemic antitumor immunity. The US-triggered pyroptosis is certified to effectively inhibit the growths of primary and distant tumors, and suppress tumor metastasis and recurrence in "cold" tumor models. This bioorthogonal-driven tumor-specific pyroptosis induction strategy has great potential for the development of robust in situ tumor vaccines.

Doxorubicin loaded octacalcium phosphate particles as controlled release drug delivery systems: Physico-chemical characterization, in vitro drug release and evaluation of cell death pathway

Mastering new and efficient ways to obtain successful drug delivery systems (DDS) with controlled release became a paramount quest in the scientific community. Increase of malignant bone tumors and the necessity to optimize an approach of localized drug delivery require research to be even more intensified. Octacalcium phosphate (OCP), with a number of advantages over current counterparts is extensively used in bone engineering. The aim of the present research was to synthesize bioactive and biocompatible doxorubicin (DOX) containing OCP particles. DOX-OCP was successfully obtained in situ in an exhaustive range of added drug (1-20 wt%, theoretical loading). Based on XRD, above 10 wt% of DOX, OCP formation was inhibited and the obtained product was low crystalline α-TCP. In-vitro drug release was performed in pH 7.4 and 6.0. In both pH environments DOX had a continuous release over six weeks. However, the initial drug burst for pH 7.4, in the first 24 h, ranged from 15.9 ± 1.3 % to 33.5 ± 12 % and for pH 6.0 23.7 ± 1.5 % to 36.2 ± 12 %.The DOX-OCP exhibited an inhibitory effect on viability of osteosarcoma cell lines MG63, U2OS and HOS. In contrast, MC3T3-E1 cells (IC50 > 0.062 µM) displayed increased viability and proliferation from 3rd to 7th day. Testing of the DDS on ferroptotic markers (CHAC1, ACSL4 and PTGS2) showed that OCP-DOX does not induce ferroptotic cell death. Moreover, the evaluation of protein levels of cleaved PARP, by western blotting analysis, corroborated that apoptosis is the main pathway of programmed cell death in osteosarcoma cells induced by DOX-OCP.

Designing a Mitochondria-Targeted Theranostic Cyclometalated Iridium(III) Complex: Overcoming Cisplatin Resistance and Inhibiting Tumor Metastasis through Necroptosis and Immune Response

To develop a potential theranostic metal agent to reverse the resistance of cancer cells to cisplatin and effectively inhibit tumor growth and metastasis, we proposed to design a cyclometalated iridium (Ir) complex based on the properties of the tumor environment (TME). To the end, we designed and synthesized a series of Ir(III) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes by modifying the hydrogen atom(s) of the N-3 position of 2-hydroxy-1-naphthaldehyde thiosemicarbazone compounds and the structure of cyclometalated Ir(III) dimers and then investigated their structure-activity and structure-fluorescence relationships to obtain an Ir(III) complex (Ir5) with remarkable fluorescence and cytotoxicity to cancer cells. Ir5 not only possesses mitochondria-targeted properties but also overcomes cisplatin resistance and effectively inhibits tumor growth and metastasis in vivo. Besides, we confirmed the anticancer mechanisms of Ir5 acting on different components in the TME: directly killing liver cancer cells by inducing necroptosis and activating the necroptosis-related immune response.

Discovery of novel selective phosphodiesterase‑1 inhibitors for the treatment of acute myelogenous leukemia

Acute myelogenous leukemia (AML) is the most common form of acute leukemia in adults. PDE1 (Phosphodiesterase 1) is a subfamily of the PDE super-enzyme families that can hydrolyze the second messengers cAMP and cGMP simultaneously. Previous research has shown that suppressing the gene expression of PDE1 can trigger apoptosis of human leukemia cells. However, no selective PDE1 inhibitors have been used to explore whether PDE1 is a potential target for treating AML. Based on our previously reported PDE9/PDE1 dual inhibitor 11a, a series of novel pyrazolopyrimidinone derivatives were designed in this study. The lead compound 6c showed an IC50 of 7.5 nM against PDE1, excellent selectivity over other PDEs and good metabolic stability. In AML cells, compound 6c significantly inhibited the proliferation and induced apoptosis. Further experiments indicated that the apoptosis induced by 6c was through a mitochondria-dependent pathway by decreasing the ratio of Bcl-2/Bax and increasing the cleavage of caspase-3, 7, 9, and PARP. All these results suggested that PDE1 might be a novel target for AML.

Targeting paraptosis in cancer: opportunities and challenges

Cell death can be classified into two primary categories: accidental cell death and regulated cell death (RCD). Within RCD, there are distinct apoptotic and non-apoptotic cell death pathways. Among the various forms of non-apoptotic RCD, paraptosis stands out as a unique mechanism characterized by distinct morphological changes within cells. These alterations encompass cytoplasmic vacuolization, organelle swelling, notably in the endoplasmic reticulum and mitochondria, and the absence of typical apoptotic features, such as cell shrinkage and DNA fragmentation. Biochemically, paraptosis distinguishes itself by its independence from caspases, which are conventionally associated with apoptotic death. This intriguing cell death pathway can be initiated by various cellular stressors, including oxidative stress, protein misfolding, and specific chemical compounds. Dysregulated paraptosis plays a pivotal role in several critical cancer-related processes, such as autophagic degradation, drug resistance, and angiogenesis. This review provides a comprehensive overview of recent advancements in our understanding of the mechanisms and regulation of paraptosis. Additionally, it delves into the potential of paraptosis-related compounds for targeted cancer treatment, with the aim of enhancing treatment efficacy while minimizing harm to healthy cells.

6-n-Butoxy-10-nitro-12,13-dioxa-11-azatricyclo[7.3.1.02,7]trideca-2,4,6,10-tetraene Improves the X-ray Sensitivity on Inhibiting Proliferation and Promoting Oxidative Stress and Apoptosis of Oral Cancer Cells

This in vitro study examines the anti-oral cancer effects and mechanisms of a combined X-ray/SK2 treatment, i.e., X-ray and 6-n-butoxy-10-nitro-12,13-dioxa-11-azatricyclo[7.3.1.02,7]trideca-2,4,6,10-tetraene (SK2). ATP cell viability and flow cytometry-based cell cycle, apoptosis, oxidative stress, and DNA damage assessments were conducted. The X-ray/SK2 treatment exhibited lower viability in oral cancer (Ca9-22 and CAL 27) cells than in normal (Smulow-Glickman, S-G) cells, i.e., 32.0%, 46.1% vs. 59.0%, which showed more antiproliferative changes than with X-ray or SK2 treatment. Oral cancer cells under X-ray/SK2 treatment showed slight subG1 and G2/M increments and induced high annexin V-monitored apoptosis compared to X-ray or SK2 treatment. The X-ray/SK2 treatment showed higher caspase 3 and 8 levels for oral cancer cells than other treatments. X-ray/SK2 showed a higher caspase 9 level in CAL 27 cells than other treatments, while Ca9-22 cells showed similar levels under X-ray and/or SK2. The X-ray/SK2 treatment showed higher reactive oxygen species (ROS) generation and mitochondrial membrane potential (MMP) depletion than other treatments. Meanwhile, the mitochondrial superoxide (MitoSOX) and glutathione levels in X-ray/SK2 treatment did not exhibit the highest rank compared to others. Moreover, oral cancer cells had higher γH2AX and/or 8-hydroxy-2-deoxyguanosine levels from X-ray/SK2 treatment than others. All these measurements for X-ray/SK2 in oral cancer cells were higher than in normal cells and attenuated by N-acetylcysteine. In conclusion, X-ray/SK2 treatment showed ROS-dependent enhanced antiproliferative, apoptotic, and DNA damage effects in oral cancer cells with a lower cytotoxic influence on normal cells.

Exploring beyond Common Cell Death Pathways in Oral Cancer: A Systematic Review

Oral squamous cell carcinoma (OSCC) is the most common and lethal type of head and neck cancer in the world. Variable response and acquisition of resistance to traditional therapies show that it is essential to develop novel strategies that can provide better outcomes for the patient. Understanding of cellular and molecular mechanisms of cell death control has increased rapidly in recent years. Activation of cell death pathways, such as the emerging forms of non-apoptotic programmed cell death, including ferroptosis, pyroptosis, necroptosis, NETosis, parthanatos, mitoptosis and paraptosis, may represent clinically relevant novel therapeutic opportunities. This systematic review summarizes the recently described forms of cell death in OSCC, highlighting their potential for informing diagnosis, prognosis and treatment. Original studies that explored any of the selected cell deaths in OSCC were included. Electronic search, study selection, data collection and risk of bias assessment tools were realized. The literature search was carried out in four databases, and the extracted data from 79 articles were categorized and grouped by type of cell death. Ferroptosis, pyroptosis, and necroptosis represented the main forms of cell death in the selected studies, with links to cancer immunity and inflammatory responses, progression and prognosis of OSCC. Harnessing the potential of these pathways may be useful in patient-specific prognosis and individualized therapy. We provide perspectives on how these different cell death types can be integrated to develop decision tools for diagnosis, prognosis, and treatment of OSCC.

Ferroptosis resistance in cancer: recent advances and future perspectives

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death and has been implicated in the occurrence and development of various diseases, including heart disease, nervous system diseases and cancer. Ferroptosis induction recently emerged as an attractive strategy for cancer therapy. Ferroptosis has become a potential target for intervention in these diseases or injuries in relevant preclinical models. This review summarizes recent progress on the mechanisms of ferroptosis resistance in cancer, highlights redox status and metabolism's role in it. Combination therapy for ferroptosis has great potential in cancer treatment, especially malignant tumors that are resistant to conventional therapies. This review will lead us to have a comprehensive understanding of the future exploration of ferroptosis and cancer therapy. A deeper understanding of the relationship between ferroptosis resistance and metabolism reprogramming may provide new strategies for tumor treatment and drug development based on ferroptosis.

Ferroptosis in the ageing retina: A malevolent fire of diabetic retinopathy

Ageing retina is prone to ferroptosis due to the iron accumulation and impaired efficiency of intracellular antioxidant defense system. Ferroptosis acts as a cell death modality that is characterized by the iron-dependent accumulation of lipid peroxidation. Ferroptosis is distinctively different from other types of regulated cell death (RCD) at the morphological, biochemical, and genetic levels. Diabetic retinopathy (DR) is a common microvascular complication of diabetes. Its prevalence and severity increase progressively with age. Recent reports have shown that ferroptosis is implicated in the pathophysiology of DR. Under hyperglycemia condition, the endothelial cell and retinal pigment epithelium (RPE) cell will undergo ferroptosis, which contributes to the increased vascular permeability and the disrupted blood retinal barrier (BRB). The underlying etiology of DR can be attributed to the impaired BRB integrity and subsequent damages of the neurovascular units. In the absence of timely intervention, the compromised BRB can ultimately cause profound visual impairments. In particular, the ageing retina is vulnerable to ferroptosis, and hyperglycemia will accelerate the progression of this pathological process. In this article, we discuss the contributory role of ferroptosis in DR pathogenesis, and summarize recent therapeutic trials that targeting the ferroptosis. Further study on the ferroptosis mediated damage would enrich our knowledge of DR pathology, and promote the development of clinical treatment for this degenerative retinopathy.

Targeted therapy for non-small-cell lung cancer: New insights into regulated cell death combined with immunotherapy

Non-small-cell lung cancer (NSCLC), which has a high rate of metastatic spread and drug resistance, is the most common subtype of lung cancer. Therefore, NSCLC patients have a very poor prognosis and a very low chance of survival. Human cancers are closely linked to regulated cell death (RCD), such as apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis. Currently, small-molecule compounds targeting various types of RCD have shown potential as anticancer treatments. Moreover, RCD appears to be a specific part of the antitumor immune response; hence, the combination of RCD and immunotherapy might increase the inhibitory effect of therapy on tumor growth. In this review, we summarize small-molecule compounds used for the treatment of NSCLC by focusing on RCD and pharmacological systems. In addition, we describe the current research status of an immunotherapy combined with an RCD-based regimen for NSCLC, providing new ideas for targeting RCD pathways in combination with immunotherapy for patients with NSCLC in the future.

Nanomedicine targeting ferroptosis to overcome anticancer therapeutic resistance

A potential reason for the failure of tumor therapies is treatment resistance. Resistance to chemotherapy, radiotherapy, and immunotherapy continues to be a major obstacle in clinic, resulting in tumor recurrence and metastasis. The major mechanisms of therapy resistance are inhibitions of cell deaths, like apoptosis and necrosis, through drug inactivation and excretion, repair of DNA damage, tumor heterogeneity, or changes in tumor microenvironment, etc. Recent studies have shown that ferroptosis play a major role in therapies resistance by inducing phospholipid peroxidation and iron-dependent cell death. Some ferroptosis inducers in combination with clinical treatment techniques have been used to enhance the effect in tumor therapy. Notably, versatile ferroptosis nanoinducers exhibit an extensive range of functions in reversing therapy resistance, including directly triggering ferroptosis and feedback regulation. Herein, we provide a detailed description of the design, mechanism, and therapeutic application of ferroptosis-mediated synergistic tumor therapeutics. We also discuss the prospect and challenge of nanomedicine in tumor therapy resistance by regulating ferroptosis and combination therapy.

GSH/pH Dual Activatable Cross-linked and Fluorinated PEI for Cancer Gene Therapy Through Endogenous Iron De-Hijacking and in Situ ROS Amplification

Ferroptosis-related cancer therapy is limited by insufficient Fe2+ /Fe3+ redox pair and hydrogen peroxide (H2 O2 ) for producing lethal hydroxyl radicals (·OH). Although exogenous iron or ROS-producing drugs can enhance ferroptosis, exploiting endogenous iron (labile iron pool, LIP) stored in ferritin and promoting ROS generation may be safer. Herein, a metal/drug-free nanomedicine is developed for responsive LIP release and H2 O2 generation on the mitochondria membranes, amplifying hydroxyl radical production to enhance ferroptosis-mediated antitumor effects. A glutathione(GSH)/pH dual activatable fluorinated and cross-linked polyethyleneimine (PEI) with dialdehyde polyethylene glycol layer nanocomplex loaded with MTS-KR-SOD (Mitochondria-targeting-sequence-KillerRed-Superoxide Dismutase) and CRISPR/Cas9-CA IX (Carbonic anhydrase IX (CA IX)) plasmids (FP@MC) are developed for enhanced ferroptosis through endogenous iron de-hijacking and in situ ROS amplification. Two plasmids are constructed to knockdown CA IX and translate KillerRed-SOD recombinant protein specifically on mitochondria membranes, respectively. The CA IX knockdown acidifies the intracellular environment, leading the release of LIP from ferritin as a "flare" to initiate endogenous chemodynamic therapy. Meanwhile, MTS-KR-SOD generates H2 O2 when irradiated by a 590 nm laser to assist chemodynamic therapy, leading to ROS amplification for mitochondria damage and lipid peroxide accumulation. The combined therapeutic effects aggravate cancer ferroptosis and suppress tumor growth, providing a new paradigm for amplifying ROS and iron ions to promote ferroptosis-related cancer therapy.

Cell Death Pathway Regulation by Functional Nanomedicines for Robust Antitumor Immunity

Cancer immunotherapy has become a mainstream cancer treatment over traditional therapeutic modes. Cancer cells can undergo programmed cell death including ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis which are find to have intrinsic relationships with host antitumor immune response. However, direct use of cell death inducers or regulators may bring about severe side effects that can also be rapidly excreted and degraded with low therapeutic efficacy. Nanomaterials are able to carry them for long circulation time, high tumor accumulation and controlled release to achieve satisfactory therapeutic effect. Nowadays, a large number of studies have focused on nanomedicines-based strategies through modulating cell death modalities to potentiate antitumor immunity. Herein, immune cell types and their function are first summarized, and state-of-the-art research progresses in nanomedicines mediated cell death pathways (e.g., ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis) with immune response provocation are highlighted. Subsequently, the conclusion and outlook of potential research focus are discussed.

Daidzein nanosuspension in combination with cisplatin to enhance therapeutic efficacy against A549 non-small lung cancer cells: an in vitro evaluation

Lung cancer is the most common cause of cancer-related mortality, chemo-resistance, and toxicity limit treatment. The focus is on innovative combined phytotherapy to improve treatment outcomes. Our aim was to investigate the potential effects of daidzein nanosuspension (DZ-NS) and its combination with cisplatin (CIS) on A549 non-small lung cancer cells. Cytotoxicity was investigated using MTT and Chou-Talalay methods. Oxidative, apoptotic, and inflammatory markers were analyzed by ELISA and qRT-PCR. The IC50 value for DZ-NS was 25.23 µM for 24 h and was lower than pure DZ (IC50 = 835 µM for pure DZ). DZ-NS (at IC50x2 and IC50 values) showed synergistic cytotoxicity with CIS. The cells treated with DZ-NS had low TOS and OSI levels. However, DZ-NS failed to regulate Cas3 and TGF-β1 activation in A549 cells. MMP-9 gene expression was significantly suppressed in DZ-NS-treated cells, especially in combination therapy. DZ represents a potential combination option for the treatment of lung cancer, and its poor toxicokinetic properties limit its clinical use. To overcome these limitations, the effects of the nanosuspension formulation were tested. DZ-NS showed a cytotoxic effect on A549 cells and optimized the therapeutic effect of CIS. This in vitro synergistic effect was mediated by suppression of MMP-9 and not by oxidative stress or Cas3-activated apoptosis. This study provides the basis for an in vivo and clinical trial of DZ-NS with concurrent chemotherapy.

Mechanisms of PANoptosis and relevant small-molecule compounds for fighting diseases

Pyroptosis, apoptosis, and necroptosis are mainly programmed cell death (PCD) pathways for host defense and homeostasis. PANoptosis is a newly distinct inflammatory PCD pathway that is uniquely regulated by multifaceted PANoptosome complexes and highlights significant crosstalk and coordination among pyroptosis (P), apoptosis (A), and/or necroptosis(N). Although some studies have focused on the possible role of PANpoptosis in diseases, the pathogenesis of PANoptosis is complex and underestimated. Furthermore, the progress of PANoptosis and related agonists or inhibitors in disorders has not yet been thoroughly discussed. In this perspective, we provide perspectives on PANoptosome and PANoptosis in the context of diverse pathological conditions and human diseases. The treatment targeting on PANoptosis is also summarized. In conclusion, PANoptosis is involved in plenty of disorders including but not limited to microbial infections, cancers, acute lung injury/acute respiratory distress syndrome (ALI/ARDS), ischemia-reperfusion, and organic failure. PANoptosis seems to be a double-edged sword in diverse conditions, as PANoptosis induces a negative impact on treatment and prognosis in disorders like COVID-19 and ALI/ARDS, while PANoptosis provides host protection from HSV1 or Francisella novicida infection, and kills cancer cells and suppresses tumor growth in colorectal cancer, adrenocortical carcinoma, and other cancers. Compounds and endogenous molecules focused on PANoptosis are promising therapeutic strategies, which can act on PANoptosomes-associated members to regulate PANoptosis. More researches on PANoptosis are needed to better understand the pathology of human conditions and develop better treatment.

Ferritinophagy: research advance and clinical significance in cancers

Ferritinophagy, a process involving selective autophagy of ferritin facilitated by nuclear receptor coactivator 4 (NCOA4), entails the recognition of ferritin by NCOA4 and subsequent delivery to the autophagosome. Within the autophagosome, ferritin undergoes degradation, leading to the release of iron in the lysosome. It is worth noting that excessive iron levels can trigger cell death. Recent evidence has elucidated the significant roles played by ferritinophagy and ferroptosis in regulation the initiation and progression of cancer. Given the crucial role of ferritinophagy in tumor biology, it may serve as a potential target for future anti-tumor therapeutic interventions. In this study, we have provided the distinctive features of ferritinophagy and its distinctions from ferroptosis. Moreover, we have briefly examined the fundamental regulatory mechanisms of ferritinophagy, encompassing the involvement of the specific receptor NCOA4, the Nrf2/HO-1 signaling and other pathways. Subsequently, we have synthesized the current understanding of the impact of ferritinophagy on cancer progression and its potential therapeutic applications, with a particular emphasis on the utilization of chemotherapy, nanomaterials, and immunotherapy to target the ferritinophagy pathway for anti-tumor purposes.

Targeting ferroptosis in melanoma: cancer therapeutics

Melanoma is an aggressive kind of skin cancer; its rate has risen rapidly over the past few decades. Melanoma reports for only about 1% of skin cancers but leads to a high majority of skin cancer deaths. Thus, new useful therapeutic approaches are currently required, to state effective treatments to consistently enhance the overall survival rate of melanoma patients. Ferroptosis is a recently identified cell death process, which is different from autophagy, apoptosis, necrosis, and pyroptosis in terms of biochemistry, genetics, and morphology which plays an important role in cancer treatment. Ferroptosis happens mostly by accumulating iron and lipid peroxides in the cell. Recently, studies have revealed that ferroptosis has a key role in the tumor's progression. Especially, inducing ferroptosis in cells can inhibit the tumor cells' growth, leading to back warding tumorigenesis. Here, we outline the ferroptosis characteristics from its basic role in melanoma cancer and mention its possible applications in melanoma cancer treatment. Video Abstract.

Nanoparticles cellular uptake, trafficking, activation, toxicity and in vitro evaluation

Nanoparticles (NPs) physicochemical properties, such as size, shape, surface chemistry, charge, etc., play a critical role in biological systems interactions, which include NPs' cellular uptake, trafficking, activation, and toxicity. Although nano-bio interactions are multifaceted and complex, their assessment is essential for future therapeutic and diagnostic use since being carriers that deliver specific molecules (i.e., active pharmaceutical ingredients and imaging agents) in intracellular sites. The journey of NPs begins by reaching the plasma membrane and entering the cell mainly through endocytosis. After vesicles pinch off the cell membrane, the intracellular trafficking is mediated by a network of cellular endosomes which direct NPs to the different cellular components. Otherwise, NPs or their contents are released into the cytoplasm. In both cases, NPs can pass undetected or be recognized by the cell leading to a pro or anti-inflammatory response. Indeed, the cell response mostly depends on cell type and NPs physicochemical properties. The principal mechanism by which NPs activate the cell response is RONS production. Other mechanism includes signaling pathways modulation related to metabolic and enzymatic reactions, cell transduction, and immune modulation. Hence, the underlying mechanisms of cellular and subcellular interactions in vitro should be performed to provide insights into NPs' effect. This information helps us to improve their synthesis and design to maximize the clinical benefits while minimizing side effects. Most in vitro tests to evaluate NPs' effect in cells were developed focusing on cell dysfunctions, cytotoxicity, genotoxicity, immunogenicity, and cell death.

Hirudin inhibits glioma growth through mTOR-regulated autophagy

Glioma is the most common primary malignant brain tumour, and survival is poor. Hirudin has anticancer pharmacological effects through suppression of glioma cell progression, but the molecular target and mechanism are poorly understood. In this study, we observed that hirudin dose- and time-dependently inhibited glioma invasion, migration and proliferation. Mechanistically, hirudin activated LC3-II but not Caspase-3 to induce the autophagic death of glioma cells by decreasing the phosphorylation of mTOR and its downstream substrates ULK1, P70S6K and 4EBP1. Furthermore, hirudin inhibited glioma growth and induced changes in autophagy in cell-derived xenograft (CDX) nude mice, with a decrease in mTOR activity and activation of LC3-II. Collectively, our results highlight a new anticancer mechanism of hirudin in which hirudin-induced inhibition of glioma progression through autophagy activation is likely achieved by inhibition of the mTOR signalling pathway, thus providing a molecular basis for hirudin as a potential and effective clinical drug for glioma therapy.

Perspectives and mechanisms for targeting mitotic catastrophe in cancer treatment

Mitotic catastrophe is distinct from other cell death modes due to unique nuclear alterations characterized as multi and/or micronucleation. Mitotic catastrophe is a common and virtually unavoidable consequence during cancer therapy. However, a comprehensive understanding of mitotic catastrophe remains lacking. Herein, we summarize the anticancer drugs that induce mitotic catastrophe, including microtubule-targeting agents, spindle assembly checkpoint kinase inhibitors, DNA damage agents and DNA damage response inhibitors. Based on the relationships between mitotic catastrophe and other cell death modes, we thoroughly evaluated the roles played by mitotic catastrophe in cancer treatment as well as its advantages and disadvantages. Some strategies for overcoming its shortcomings while fully utilizing its advantages are summarized and proposed in this review. We also review how mitotic catastrophe regulates cancer immunotherapy. These summarized findings suggest that the induction of mitotic catastrophe can serve as a promising new therapeutic approach for overcoming apoptosis resistance and strengthening cancer immunotherapy.

The amide derivative of anticopalic acid induces non-apoptotic cell death in triple-negative breast cancer cells by inhibiting FAK activation

Anticopalic acid (ACP), a labdane type diterpenoid obtained from Kaempferia elegans rhizomes, together with 21 semi-synthetic derivatives, were evaluated for their cancer cytotoxic activity. Most derivatives displayed higher cytotoxic activity than the parent compound ACP in a panel of nine cancer cell lines. Among the tested compounds, the amide 4p showed the highest cytotoxic activity toward leukemia cell lines, HL-60 and MOLT-3, with IC50 values of 6.81 ± 1.99 and 3.72 ± 0.26 µM, respectively. More interestingly, the amide derivative 4l exhibited cytotoxic activity with an IC50 of 13.73 ± 0.04 µM against the MDA-MB-231 triple-negative breast cancer cell line, which is the most aggressive type of breast cancer. Mechanistic studies revealed that 4l induced cell death in MDA-MB-231 cells through non-apoptotic regulated cell death. In addition, western blot analysis showed that compound 4l decreased the phosphorylation of FAK protein in a concentration-dependent manner. Molecular docking simulations elucidated that compound 4l could potentially inhibit FAK activation by binding to a pocket of FAK kinase domain. The data suggested that compound 4l could be a potential FAK inhibitor for treating triple-negative breast cancer and worth being further investigated.

Biological Activities of Bismuth Compounds: An Overview of the New Findings and the Old Challenges Not Yet Overcome

Bismuth-based drugs have been used primarily to treat ulcers caused by Helicobacter pylori and other gastrointestinal ailments. Combined with antibiotics, these drugs also possess synergistic activity, making them ideal for multiple therapy regimens and overcoming bacterial resistance. Compounds based on bismuth have a low cost, are safe for human use, and some of them are also effective against tumoral cells, leishmaniasis, fungi, and viruses. However, these compounds have limited bioavailability in physiological environments. As a result, there is a growing interest in developing new bismuth compounds and approaches to overcome this challenge. Considering the beneficial properties of bismuth and the importance of discovering new drugs, this review focused on the last decade's updates involving bismuth compounds, especially those with potent activity and low toxicity, desirable characteristics for developing new drugs. In addition, bismuth-based compounds with dual activity were also highlighted, as well as their modes of action and structure-activity relationship, among other relevant discoveries. In this way, we hope this review provides a fertile ground for rationalizing new bismuth-based drugs.

Active Ingredients from Chinese Medicine for Combination Cancer Therapy

Combination therapy against cancer has gained increasing attention because it can help to target multiple pathways to tackle oncologic progression and improve the limited antitumor effect of single-agent therapy. Chinese medicine has been studied extensively in cancer therapy and proven to be efficacious in many cases due to its wide spectrum of anticancer activities. In this review, we aim to summarize the recent progress of active ingredients from Chinese medicine (AIFCM) in combination with various cancer therapeutic modalities, including chemotherapy, gene therapy, radiotherapy, phototherapy and immunotherapy. In addition to highlighting the potential contribution of AIFCM in combination cancer therapy, we also elucidate the underlying mechanisms behind their synergistic effect and improved anticancer efficacy, thereby encouraging the inclusion of these AIFCM as part of effective armamentarium in fighting intractable cancers. Finally, we present the challenges and future perspectives of AIFCM combination therapy as a feasible and promising strategy for the optimization of cancer treatment and better clinical outcomes.

Harnessing the Potential of Non-Apoptotic Cell Death Processes in the Treatment of Drug-Resistant Melanoma

Melanoma is a highly malignant skin cancer that is known for its resistance to treatments. In recent years, there has been significant progress in the study of non-apoptotic cell death, such as pyroptosis, ferroptosis, necroptosis, and cuproptosis. This review provides an overview of the mechanisms and signaling pathways involved in non-apoptotic cell death in melanoma. This article explores the interplay between various forms of cell death, including pyroptosis, necroptosis, ferroptosis, and cuproptosis, as well as apoptosis and autophagy. Importantly, we discuss how these non-apoptotic cell deaths could be targeted as a promising therapeutic strategy for the treatment of drug-resistant melanoma. This review provides a comprehensive overview of non-apoptotic processes and gathers recent experimental evidence that will guide future research and eventually the creation of treatment strategies to combat drug resistance in melanoma.

Paraptosis: a unique cell death mode for targeting cancer

Programmed cell death (PCD) is the universal process that maintains cellular homeostasis and regulates all living systems' development, health and disease. Out of all, apoptosis is one of the major PCDs that was found to play a crucial role in many disease conditions, including cancer. The cancer cells acquire the ability to escape apoptotic cell death, thereby increasing their resistance towards current therapies. This issue has led to the need to search for alternate forms of programmed cell death mechanisms. Paraptosis is an alternative cell death pathway characterized by vacuolation and damage to the endoplasmic reticulum and mitochondria. Many natural compounds and metallic complexes have been reported to induce paraptosis in cancer cell lines. Since the morphological and biochemical features of paraptosis are much different from apoptosis and other alternate PCDs, it is crucial to understand the different modulators governing it. In this review, we have highlighted the factors that trigger paraptosis and the role of specific modulators in mediating this alternative cell death pathway. Recent findings include the role of paraptosis in inducing anti-tumour T-cell immunity and other immunogenic responses against cancer. A significant role played by paraptosis in cancer has also scaled its importance in knowing its mechanism. The study of paraptosis in xenograft mice, zebrafish model, 3D cultures, and novel paraptosis-based prognostic model for low-grade glioma patients have led to the broad aspect and its potential involvement in the field of cancer therapy. The co-occurrence of different modes of cell death with photodynamic therapy and other combinatorial treatments in the tumour microenvironment are also summarized here. Finally, the growth, challenges, and future perspectives of paraptosis research in cancer are discussed in this review. Understanding this unique PCD pathway would help to develop potential therapy and combat chemo-resistance in various cancer.

Phenothiazine derivatives and their impact on the necroptosis and necrosis processes. A review

The current review focuses on the effect of phenothiazine derivatives, tested in vitro, on necrosis and necroptosis, the latter constitutes one of the kinds of programmed cell death. Necroptosis is a necrotic and inflammatory type of programmed cell death. Phenothiazines are D1 and D2-like family receptor antagonists, which are used in the treatment of schizophrenia. Necroptosis begins from TNF-α, whose synthesis is stimulated by dopamine receptors, thus it can be concluded that phenothiazine derivatives may modulate necroptosis. We identified 19 papers reporting in vitro assays of necroptosis and necrosis in which phenothiazine derivatives, and both normal and cancer cell lines were used. Chlorpromazine, fluphenazine, levomepromazine, perphenazine, promethazine, thioridazine, trifluoperazine, and novel derivatives can modulate necroptosis and necrosis. The type of a drug, concentration and a cell line have an impact on the ultimate effect. Unfortunately, the authors confirmed both processes on the basis of TNF-α and ATP levels as well as the final steps of necrosis/necroptosis related to membrane permeability (PI staining, LDH release, and HMGB1 amount), which makes it impossible to understand the complete mechanism of phenothiazines impact on necroptosis and necrosis. Studies analyzing the effect of phenothiazines on RIPK1, RIPK3, or MLKL has not been performed yet. Only the analysis of the expression of those proteins as well as necrosis and necroptosis inhibitors can help us to comprehend how phenothiazine derivatives act, and how to improve their therapeutic potential.

Immuno-photodynamic Therapy (IPDT): Organic Photosensitizers and Their Application in Cancer Ablation

Photosensitizer-based photodynamic therapy (PDT) has been considered as a promising modality for fighting diverse types of cancers. PDT directly inhibits local tumors by a minimally invasive strategy, but it seems to be incapable of achieving complete eradication and fails to prevent metastasis and recurrence. Recently, increasing events proved that PDT was associated with immunotherapy by triggering immunogenic cell death (ICD). Upon a specific wavelength of light irradiation, the photosensitizers will turn the surrounding oxygen molecules into cytotoxic reactive oxygen species (ROS) for killing the cancer cells. Simultaneously, the dying tumor cells release tumor-associated antigens, which could improve immunogenicity to activate immune cells. However, the progressively enhanced immunity is typically limited by the intrinsic immunosuppressive tumor microenvironment (TME). To overcome this obstacle, immuno-photodynamic therapy (IPDT) has come to be one of the most beneficial strategies, which takes advantage of PDT to stimulate the immune response and unite immunotherapy for inducing immune-OFF tumors to immune-ON ones, to achieve systemic immune response and prevent cancer recurrence. In this Perspective, we provide a review of recent advances in organic photosensitizer-based IPDT. The general process of immune responses triggered by photosensitizers (PSs) and how to enhance the antitumor immune pathway by modifying the chemical structure or conjugating with a targeting component was discussed. In addition, future perspectives and challenges associated with IPDT strategies are also discussed. We hope this Perspective could inspire more innovative ideas and provide executable strategies for future developments in the war against cancer.

Iron nitroprusside as a chemodynamic agent and inducer of ferroptosis for ovarian cancer therapy

ChemoDynamic Therapy (CDT) is a powerful therapeutic modality using Fenton/Fenton-like reactions to produce oxidative stress for cancer treatment. However, the insufficient amount of catalyst ions and ROS scavenging activity of glutathione peroxidase (GPX4) limit the application of this approach. Therefore, a tailored strategy to regulate the Fenton reaction more efficiently (utilizing dual metal cations) and inhibit the GPX4 activity, is in great demand. Herein, a CDT system is based on dual (Fe²⁺ metals) iron pentacyanonitrosylferrate or iron nitroprusside (FeNP) having efficient ability to catalyze the reaction of endogenous H₂O₂ to form highly toxic ˙OH species in cells. Additionally, FeNP is involved in ferroptosis via GPX4 inhibition. In particular, FeNP was structurally characterized, and it is noted that a minimum dose of FeNP is required to kill cancer cells while a comparable dose shows negligible toxicity on normal cells. Detailed in vitro studies confirmed that FeNP participates in sustaining apoptosis, as determined using the annexin V marker. Cellular uptake results showed that in a short time period, FeNP enters lysosomes and, due to the acidic lysosomal pH, releases Fe²⁺ ions, which are involved in ROS generation (˙OH species). Western blot analyses confirmed the suppression of GPX4 activity over time. Importantly, FeNP has a therapeutic effect on ovarian cancer organoids derived from High-Grade Serous Ovarian Cancer (HGSOC). Furthermore, FeNP showed biocompatible nature towards normal mouse liver organoids and in vivo. This work presents the effective therapeutic application of FeNP as an efficient Fenton agent along with ferroptosis inducer activity to improve CDT, through disturbing redox homeostasis.

The Role of Silver Nanoparticles in the Diagnosis and Treatment of Cancer: Are There Any Perspectives for the Future?

Cancer is a fatal disease with a complex pathophysiology. Lack of specificity and cytotoxicity, as well as the multidrug resistance of traditional cancer chemotherapy, are the most common limitations that often cause treatment failure. Thus, in recent years, significant efforts have concentrated on the development of a modernistic field called nano-oncology, which provides the possibility of using nanoparticles (NPs) with the aim to detect, target, and treat cancer diseases. In comparison with conventional anticancer strategies, NPs provide a targeted approach, preventing undesirable side effects. What is more, nanoparticle-based drug delivery systems have shown good pharmacokinetics and precise targeting, as well as reduced multidrug resistance. It has been documented that, in cancer cells, NPs promote reactive oxygen species (ROS) production, induce cell cycle arrest and apoptosis, activate ER (endoplasmic reticulum) stress, modulate various signaling pathways, etc. Furthermore, their ability to inhibit tumor growth in vivo has also been documented. In this paper, we have reviewed the role of silver NPs (AgNPs) in cancer nanomedicine, discussing numerous mechanisms by which they render anticancer properties under both in vitro and in vivo conditions, as well as their potential in the diagnosis of cancer.

Nanomedicine embraces cancer radio-immunotherapy: mechanism, design, recent advances, and clinical translation

Cancer radio-immunotherapy, integrating external/internal radiation therapy with immuno-oncology treatments, emerges in the current management of cancer. A growing number of pre-clinical studies and clinical trials have recently validated the synergistic antitumor effect of radio-immunotherapy, far beyond the "abscopal effect", but it suffers from a low response rate and toxicity issues. To this end, nanomedicines with an optimized design have been introduced to improve cancer radio-immunotherapy. Specifically, these nanomedicines are elegantly prepared by incorporating tumor antigens, immuno- or radio-regulators, or biomarker-specific imaging agents into the corresponding optimized nanoformulations. Moreover, they contribute to inducing various biological effects, such as generating in situ vaccination, promoting immunogenic cell death, overcoming radiation resistance, reversing immunosuppression, as well as pre-stratifying patients and assessing therapeutic response or therapy-induced toxicity. Overall, this review aims to provide a comprehensive landscape of nanomedicine-assisted radio-immunotherapy. The underlying working principles and the corresponding design strategies for these nanomedicines are elaborated by following the concept of "from bench to clinic". Their state-of-the-art applications, concerns over their clinical translation, along with perspectives are covered.

Targeting Wnt/β-Catenin Signaling Exacerbates Ferroptosis and Increases the Efficacy of Melanoma Immunotherapy via the Regulation of MITF

Melanoma is the most lethal form of skin cancer, resulting from the malignant transformation of epidermal melanocytes. Recent revolutionary progress in targeted therapy and immunotherapy has prominently improved the treatment outcome, but the survival of melanoma patients remains suboptimal. Ferroptosis is greatly involved in cancer pathogenesis and can execute the outcome of immunotherapy. However, the detailed regulatory mechanisms of melanoma cell ferroptosis remain elusive. Herein, we report that Wnt/β-catenin signaling regulates ferroptosis and melanoma immunotherapy efficacy via the regulation of MITF. First of all, we found that Wnt/β-catenin signaling was prominently suppressed in melanoma cell ferroptosis. Then, we proved that targeting β-catenin exacerbated melanoma cell ferroptosis by promoting the generation of lipid peroxidation both in vitro and in vivo. Subsequent mechanistic studies revealed that MITF mediated the effect of Wnt/β-catenin signaling on melanoma cell ferroptosis, and PGC1α and SCD1 were documented as two main effectors downstream of Wnt/β-catenin-MITF pathway. Ultimately, pharmacological inhibition of β-catenin or MITF increased the efficacy of anti-PD-1 immunotherapy in preclinical xenograft tumor model by promoting ferroptosis. Taken together, Wnt/β-catenin signaling deficiency exacerbates ferroptosis in melanoma via the regulation of MITF. Targeting Wnt/β-catenin-MITF pathway could be a promising strategy to potentiate ferroptosis and increase the efficacy of anti-PD-1 immunotherapy.

Dual role of an essential HtrA2/Omi protease in the human malaria parasite: Maintenance of mitochondrial homeostasis and induction of apoptosis-like cell death under cellular stress

Members of the HtrA family of serine proteases are known to play roles in mitochondrial homeostasis as well as in programmed cell death. Mitochondrial homeostasis and metabolism are crucial for the survival and propagation of the malaria parasite within the host. Here we have functionally characterized a Plasmodium falciparum HtrA2 (PfHtrA2) protein, which harbours trypsin-like protease activity that can be inhibited by its specific inhibitor, ucf-101. A transgenic parasite line was generated, using the HA-glmS C-terminal tagging approach, for localization as well as for inducible knock-down of PfHtrA2. The PfHtrA2 was localized in the parasite mitochondrion during the asexual life cycle. Genetic ablation of PfHtrA2 caused significant parasite growth inhibition, decreased replication of mtDNA, increased mitochondrial ROS production, caused mitochondrial fission/fragmentation, and hindered parasite development. However, the ucf-101 treatment did not affect the parasite growth, suggesting the non-protease/chaperone role of PfHtrA2 in the parasite. Under cellular stress conditions, inhibition of PfHtrA2 by ucf-101 reduced activation of the caspase-like protease as well as parasite cell death, suggesting the involvement of protease activity of PfHtrA2 in apoptosis-like cell death in the parasite. Under these cellular stress conditions, the PfHtrA2 gets processed but remains localized in the mitochondrion, suggesting that it acts within the mitochondrion by cleaving intra-mitochondrial substrate(s). This was further supported by trans-expression of PfHtrA2 protease domain in the parasite cytosol, which was unable to induce any cell death in the parasite. Overall, we show the specific roles of PfHtrA2 in maintaining mitochondrial homeostasis as well as in regulating stress-induced cell death.

A Tale of Two Cancers: A Current Concise Overview of Breast and Prostate Cancer

Simple Summary

Breast and prostate cancers are serious public health issues that create considerable burden to both people and healthcare systems worldwide. Cancer is a heterogeneous disease influenced by numerous components, and its diverse intricate pathology challenges disease prevention, diagnosis, treatment, and survival. Although recent statistics suggest improvements in cancer diagnosis and treatment, many challenges remain before cancers are curable. This review presents relevant summarized information related to breast and prostate cancer.

Abstract

Cancer is a global issue, and it is expected to have a major impact on our continuing global health crisis. As populations age, we see an increased incidence in cancer rates, but considerable variation is observed in survival rates across different geographical regions and cancer types. Both breast and prostate cancer are leading causes of morbidity and mortality worldwide. Although cancer statistics indicate improvements in some areas of breast and prostate cancer prevention, diagnosis, and treatment, such statistics clearly convey the need for improvements in our understanding of the disease, risk factors, and interventions to improve life span and quality of life for all patients, and hopefully to effect a cure for people living in developed and developing countries. This concise review compiles the current information on statistics, pathophysiology, risk factors, and treatments associated with breast and prostate cancer.