Paraptosis-Inducing Nanomedicine Overcomes Cancer Drug Resistance for a Potent Cancer Therapy

Targeted delivery of FAK siRNA by engineered exosomes to reverse cetuximab resistance via activating paraptosis in colon cancer

BACKGROUND

Cetuximab is extensively used in the treatment of metastatic colorectal cancer (mCRC). However, resistance poses a significant challenge to successful therapy. Recently, paraptosis, a non-classical programmed cell death, has garnered increased attention for its potential application value in antitumor treatments. We aimed to identify the essential pathways and signaling molecules involved in paraptosis inhibition and select them as therapeutic targets in cetuximab resistance. Additionally, engineered exosome technology is used as a drug delivery system with both targeted and effector properties.

RESULTS

By comparing the differential expression of paraptosis-related genes between drug-resistant colon cancer cells and sensitive cells, it was observed that the paraptosis level induced by cetuximab was significantly downregulated in drug-resistant cells. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified the focal adhesion kinase (FAK) signaling pathway as a key pathway involved in the suppression of paraptosis. The biological function of FAK in cetuximab-resistant cells was investigated through cell morphology observation, CCK-8 assay, colony formation assay, RT-qPCR, Western Blot, and loss-of-function experiments. The results showed that the FAK signaling pathway was significantly upregulated in cetuximab-resistant colon cancer cells, and siRNA interference targeting FAK could notably inhibit cell proliferation while upregulating the paraptosis level. Based on this, engineered colon cancer cells targeted and FAK siRNA loaded exosomes (CT-Exo-siFAK1) were constructed. In vitro experiments, CT-Exo-siFAK1 could effectively activate paraptosis and inhibit the proliferation of drug-resistant colon cancer cells. In vivo experiments also confirmed that CT-Exo-siFAK1 significantly suppressed tumor growth and metastasis while upregulating the paraptosis level.

CONCLUSION

This study suggests that FAK signaling pathway-mediated inhibition of paraptosis levels is crucial in the sensitivity of cetuximab targeted therapy in colon cancer, and the use of engineered exosomes to deliver FAK siRNA may be an effective strategy to reverse cetuximab resistance.

Copper in colorectal cancer: From copper-related mechanisms to clinical cancer therapies

Copper, a trace element and vital cofactor, plays a crucial role in the maintenance of biological functions. Recent evidence has established significant correlations between copper levels, cancer development and metastasis. The strong redox-active properties of copper offer both benefits and disadvantages to cancer cells. The intestinal tract, which is primarily responsible for copper uptake and regulation, may suffer from an imbalance in copper homeostasis. Colorectal cancer (CRC) is the most prevalent primary cancer of the intestinal tract and is an aggressive malignant disease with limited therapeutic options. Current research is primarily focused on the relationship between copper and CRC. Innovative concepts, such as cuproplasia and cuproptosis, are being explored to understand copper-related cellular proliferation and death. Cuproplasia is the regulation of cell proliferation that is mediated by both enzymatic and nonenzymatic copper-modulated activities. Whereas, cuproptosis refers to cell death induced by excess copper via promoting the abnormal oligomerisation of lipoylated proteins within the tricarboxylic acid cycle, as well as by diminishing the levels of iron-sulphur cluster proteins. A comprehensive understanding of copper-related cellular proliferation and death mechanisms offers new avenues for CRC treatment. In this review, we summarise the evolving molecular mechanisms, ranging from abnormal intracellular copper concentrations to the copper-related proteins that are being discovered, and discuss the role of copper in the pathogenesis, progression and potential therapies for CRC. Understanding the relationship between copper and CRC will help provide a comprehensive theoretical foundation for innovative treatment strategies in CRC management.

α-Hederin induces paraptosis by targeting GPCRs to activate Ca2+/MAPK signaling pathway in colorectal cancer

BACKGROUND

Non-apoptotic cell death is presently emerging as a potential direction to overcome the apoptosis resistance of cancer cells. In the current study, a natural plant agent α-hederin (α-hed) induces caspase-independent paraptotic modes of cell death.

PURPOSE

The present study is aimed to investigate the role of α-hed induces paraptosis and the associated mechanism of it.

METHODS

The cell proliferation was detected by CCK-8. The cytoplasm organelles were observed under electron microscope. Calcium (Ca2+) level was detected by flow cytometry. Swiss Target Prediction tool analyzed the potential molecule targets of α-hed. Molecular docking methods were used to evaluate binding abilities of α-hed with targets. The expressions of genes and proteins were analyzed by RT-qPCR, western blotting, immunofluorescence, and immunohistochemistry. Xenograft models in nude mice were established to evaluate the anticancer effects in vivo.

RESULTS

α-hed exerted significant cytotoxicity against a panel of CRC cell lines by inhibiting proliferation. Besides, it induced cytoplasmic vacuolation in all CRC cells. Electron microscopy images showed the aberrant dilation of endoplasmic reticulum and mitochondria. Both mRNA and protein expressions of Alg-2 interacting proteinX (Alix), the marker of paraptosis, were inhibited by α-hed. Besides, both Swiss prediction and molecular docking showed that the structure of α-hed could tightly target to GPCRs. GPCRs were reported to activate the phospholipase C (PLC)-β3/ inositol 1,4,5-trisphosphate receptor (IP3R)/ Ca2+/ protein kinase C alpha (PKCα) pathway, and we then found all proteins and mRNA expressions of PLCβ3, IP3R, and PKCα were increased by α-hed. After blocking the GPCR signaling, α-hed could not elevate Ca2+ level and showed less CRC cell cytotoxicity. MAPK cascade is the symbol of paraptosis, and we then demonstrated that α-hed activated MAPK cascade by elevating Ca2+ flux. Since non-apoptotic cell death is presently emerging as a potential direction to overcome chemo-drug resistance, we then found α-hed also induced paraptosis in 5-fluorouracil-resistant (5-FU-R) CRC cells, and it reduced the growth of 5-FU-R CRC xenografts.

CONCLUSIONS

Collectively, our findings proved α-hed as a promising candidate for inducing non-apoptotic cell death, paraptosis. It may overcome the resistance of apoptotic-based chemo-resistance in CRC.

Apoptosis and Paraptosis Induced by Disulfiram-Loaded Ca2+/Cu2+ Dual-Ions Nano Trap for Breast Cancer Treatment

Regarded as one of the hallmarks of tumorigenesis and tumor progression, the evasion of apoptotic cell death would also account for treatment resistance or failure during cancer therapy. In this study, a Ca2+/Cu2+ dual-ion "nano trap" to effectively avoid cell apoptosis evasion by synchronously inducing paraptosis together with apoptosis was successfully designed and fabricated for breast cancer treatment. In brief, disulfiram (DSF)-loaded amorphous calcium carbonate nanoparticles (NPs) were fabricated via a gas diffusion method. Further on, the Cu2+-tannic acid metal phenolic network was embedded onto the NPs surface by self-assembling, followed by mDSPE-PEG/lipid capping to form the DSF-loaded Ca2+/Cu2+ dual-ions "nano trap". The as-prepared nanotrap would undergo acid-triggered biodegradation upon being endocytosed by tumor cells within the lysosome for Ca2+, Cu2+, and DSF releasing simultaneously. The released Ca2+ could cause mitochondrial calcium overload and lead to hydrogen peroxide (H2O2) overexpression. Meanwhile, Ca2+/reactive oxygen species-associated mitochondrial dysfunction would lead to paraptosis cell death. Most importantly, cell paraptosis could be further induced and strengthened by the toxic dithiocarbamate (DTC)-copper complexes formed by the Cu2+ combined with the DTC, the metabolic products of DSF. Additionally, the released Cu2+ will be reduced by intracellular glutathione to generate Cu+, which can catalyze the H2O2 to produce a toxic hydroxyl radical by a Cu+-mediated Fenton-like reaction for inducing cell apoptosis. Both in vitro cellular assays and in vivo antitumor evaluations confirmed the cancer therapeutic efficiency by the dual ion nano trap. This study can broaden the cognition scope of dual-ion-mediated paraptosis together with apoptosis via a multifunctional nanoplatform.

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.

Apoferritin-Cu(II) Nanoparticles Induce Oncosis in Multidrug-Resistant Colon Cancer Cells

Multidrug resistance (MDR) limits the application of clinical chemotherapeutic drugs. There is an urgent need to develop non-apoptosis-inducing agents that circumvent drug resistance. Herein, four therapeutic copper complexes encapsulated in natural nanocarrier apoferritin (AFt-Cu1-4) are reported. Although they are isomers, they exhibit significantly different organelle distributions and cell death mechanisms. AFt-Cu1 and AFt-Cu3 accumulate in the cytoplasm and induce autophagy, whereas AFt-Cu2 and AFt-Cu4 can quickly enter the nucleus and trigger oncosis. Excitedly, AFt-Cu2 and AFt-Cu4 show a strong tumor growth inhibition effect in mice models bearing multidrug-resistant colon xenograft via intravenous injection. To the best of the authors' knowledge, this is the first example of metal-based nucleus-targeted oncosis inducers overcoming multidrug resistance in vivo.

Ezetimibe Induces Paraptosis through Niemann-Pick C1-like 1 Inhibition of Mammalian-Target-of-Rapamycin Signaling in Hepatocellular Carcinoma Cells

Currently, hepatocellular carcinoma (HCC) is characterized by its unfavorable prognosis and resistance to conventional chemotherapy and radiotherapy. Drug repositioning, an approach aimed at identifying novel therapeutic applications for existing drugs, presents a cost-effective strategy for developing new anticancer agents. We explored the anticancer properties of Ezetimibe, a widely used oral lipid-lowering drug, in the context of HCC. Our findings demonstrate that Ezetimibe effectively suppresses HCC cell proliferation through paraptosis, an apoptotic-independent cell death pathway. The examination of HCC cells lines treated with Ezetimibe using light microscopy and transmission electron microscopy (TEM) showed cytoplasmic vacuolation in the perinuclear region. Notably, the nuclear membrane remained intact in both Ezetimibe-treated and untreated HCC cell lines. Probe staining assays confirmed that the cytoplasmic vacuoles originated from dilated endoplasmic reticulum (ER) compartments rather than mitochondria. Furthermore, a dose-dependent accumulation of reactive oxygen species (ROS) was observed in Ezetimibe-treated HCC cell lines. Co-treatment with the general antioxidant NAC attenuated vacuolation and improved cell viability in Ezetimibe-treated HCC cells. Moreover, Ezetimibe induced paraptosis through proteasome activity inhibition and initiation of the unfolded protein response (UPR) in HCC cell lines. In our in vivo experiment, Ezetimibe significantly impeded the growth of HCC tumors. Furthermore, when combined with Sorafenib, Ezetimibe exhibited a synergistic antitumor effect on HCC cell lines. Mechanistically, Ezetimibe induced paraptosis by targeting NPC1L1 to inhibit the PI3K/AKT/mTOR signaling pathway. In conclusion, our study highlights the potential of Ezetimibe as an anticancer agent by triggering paraptosis in HCC cells.

Aloperine targets lysosomes to inhibit late autophagy and induces cell death through apoptosis and paraptosis in glioblastoma

Glioblastoma (GBM) is an aggressive intracranial tumour, and current chemotherapy regimens have limited efficacy. Aloperine (ALO), a natural alkaline compound, has shown potential as an antitumor agent. However, the effect of ALO against GBM remains unclear. This study aimed to investigate the function of ALO in treating GBM. U87, A172, and GL261 cell lines were used for in vitro experiments, and GL261 was also used to establish in vivo models. The results showed that ALO inhibited the proliferation of GBM cells by cell cycle arrest and apoptosis. Furthermore, autophagy was found to play a critical role, suggested by observation of autophagosomes under the transmission electron microscopy. It was discovered for the first time that ALO targeted lysosomes directly in glioma cells, tested by fluo-rescence-labelled ALO and organelle-localizing probes. In addition, ALO inhibited late autophagy and induced paraptosis in GBM, verified by classical gene expression changes in qPCR and western blotting. Also, ALO inhibited tumour growth and acted synergistically with temozolomide in intracranial glioma mice models in vivo. Our findings suggest that ALO targets lysosomes to inhibit late autophagy in GBM, inducing cell cycle arrest, paraptosis, and apoptosis. ALO may therefore be a promising therapeutic agent for the treatment of GBM.

Multifaceted Roles of Copper Ions in Anticancer Nanomedicine

The significantly increased copper level in tumor tissues and serum indicates the close association of copper ions with tumor development, making copper ions attractive targets in the development of novel tumor treatment methods. The advanced nanotechnology developed in the past decades provides great potential for tumor therapy, among which Cu-based nanotherapeutic systems have received greater attention. Herein, the multifaceted roles of copper ions in cancer progression are summarized and the recent advances in the copper-based nanostructures or nanomedicines for different kinds of tumor therapies including copper depletion therapy, copper-based cytotoxins, copper-ion-based chemodynamic therapy and its combination with other treatments, and copper-ion-induced ferroptosis and cuproptosis activation are discussed. Furthermore, the perspectives for the further development of copper-ion-based nanomedicines for tumor therapy and clinic translation are presented by the authors.

V. J, Pal S, Nair BG, Kar R, Mishra N. 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.

Transcriptomic Analysis of the Anticancer Effects of Annatto Tocotrienol, Delta-Tocotrienol and Gamma-Tocotrienol on Chondrosarcoma Cells

Previous studies have demonstrated the anticancer activities of tocotrienol on several types of cancer, but its effects on chondrosarcoma have never been investigated. Therefore, this study aims to determine the anticancer properties of annatto tocotrienol (AnTT), γ-tocotrienol (γ-T3) and δ-tocotrienol (δ-T3) on human chondrosarcoma SW1353 cells. Firstly, the MTT assay was performed to determine the half-maximal inhibitory concentration (IC₅₀) of tocotrienol on SW1353 cells after 24 h treatment. The mode of cell death, cell cycle analysis and microscopic observation of tocotrienol-treated SW1353 cells were then conducted according to the respective IC₅₀ values. Subsequently, RNAs were isolated from tocotrienol-treated cells and subjected to RNA sequencing and transcriptomic analysis. Differentially expressed genes were identified and then verified with a quantitative PCR. The current study demonstrated that AnTT, γ-T3 and δ-T3 induced G1 arrest on SW1353 cells in the early phase of treatment (24 h) which progressed to apoptosis upon 48 h of treatment. Furthermore, tocotrienol-treated SW1353 cells also demonstrated large cytoplasmic vacuolation. The subsequent transcriptomic analysis revealed upregulated signalling pathways in endoplasmic reticulum stress, unfolded protein response, autophagy and transcription upon tocotrienol treatment. In addition, several cell proliferation and cancer-related pathways, such as Hippo signalling pathway and Wnt signalling pathway were also significantly downregulated upon treatment. In conclusion, AnTT, γ-T3 and δ-T3 possess promising anticancer properties against chondrosarcoma cells and further study is required to confirm their effectiveness as adjuvant therapy for chondrosarcoma.

Elaiophylin triggers paraptosis and preferentially kills ovarian cancer drug-resistant cells by inducing MAPK hyperactivation

Finely tuned mitogen-activated protein kinase (MAPK) signaling is important for cancer cell survival. Perturbations that push cells out of the MAPK fitness zone result in cell death. Previously, in a screen of the North China Pharmaceutical Group Corporation’s pure compound library of microbial origin, we identified elaiophylin as an autophagy inhibitor. Here, we demonstrated a new role for elaiophylin in inducing excessive endoplasmic reticulum (ER) stress, ER-derived cytoplasmic vacuolization, and consequent paraptosis by hyperactivating the MAPK pathway in multiple cancer cells. Genome-wide CRISPR/Cas9 knockout library screening identified SHP2, an upstream intermediary of the MAPK pathway, as a critical target in elaiophylin-induced paraptosis. The cellular thermal shift assay (CETSA) and surface plasmon resonance (SPR) assay further confirmed the direct binding between the SHP2 and elaiophylin. Inhibition of the SHP2/SOS1/MAPK pathway through SHP2 knockdown or pharmacological inhibitors distinctly attenuated elaiophylin-induced paraptosis and autophagy inhibition. Interestingly, elaiophylin markedly increased the already-elevated MAPK levels and preferentially killed drug-resistant cells with enhanced basal MAPK levels. Elaiophylin overcame drug resistance by triggering paraptosis in multiple tumor-bearing mouse models resistant to platinum, taxane, or PARPi, suggesting that elaiophylin might offer a reasonable therapeutic strategy for refractory ovarian cancer.

Nanosilver inhibits the progression of pancreatic cancer by inducing a paraptosis-like mixed type of cell death

Silver has been in clinical use since ancient times and silver nanoparticles (AgNPs) have attracted attention in cancer therapy. We investigated the mechanisms by which AgNPs inhibit pancreatic ductal adenocarcinoma (PDAC). AgNPs were synthesized and 3 human PDAC and 2 nonmalignant primary cell lines were treated with AgNPs. MTT, MAPK, colony, spheroid and scratch assays, Western blotting, TEM, annexin V, 7-AAD, and H2DCFDA staining, FACS analysis, mRNA array and bioinformatics analyses, tumor xenograft transplantation, and immunohistochemistry of the treated cells were performed. We found that minimal AgNPs amounts selectively eradicated PDAC cells within a few hours. AgNPs inhibited cell migration and spheroid and colony formation, damaged mitochondria, and induced paraptosis-like cell death with the presence of cytoplasmic vacuoles, dilation of the ER and mitochondria, ROS formation, MAPK activity, and p62 and LC3b expression, whereas effects on the nucleus, DNA fragmentation, or caspases were not detectable. AgNPs strongly decreased tumor xenograft growth without side effects and reduced the expression of markers for proliferation and DNA repair, but upregulated paraptosis markers. The results highlight nanosilver as complementary agent to improve the therapeutic efficacy in pancreatic cancer.

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

As an emerging cancer therapeutic target, non-apoptotic cell death such as ferroptosis, necroptosis and pyroptosis, etc., has revealed significant potential in cancer treatment for bypassing apoptosis to enhance the undermined therapeutic efficacy triggered by apoptosis resistance. A variety of anticancer drugs, synthesized compounds and natural products have been proven recently to induce non-apoptotic cell death and exhibit excellent anti-tumor effects. Moreover, the convergence of nanotechnology with functional materials and biomedicine science has provided tremendous opportunities to construct non-apoptotic cell death-based nanomedicine for innovative cancer therapy. Nanocarriers are not only employed in targeted delivery of non-apoptotic inducers, but also used as therapeutic components to induce non-apoptotic cell death to achieve efficient tumor treatment. This review first introduces the main characteristics, the mechanism and various pharmacological modulators of different non-apoptotic cell death forms, including ferroptosis, necroptosis, pyroptosis, autophagy, paraptosis, lysosomal-dependent cell death, and oncosis. Second, we comprehensively review the latest progresses of nanomedicine that induces various forms of non-apoptotic cell death and focus on the nanomedicine targeting different pathways and components. Furthermore, the combination therapies of non-apoptotic cell death with photothermal therapy, photodynamic therapy, immunotherapy and other modalities are summarized. Finally, the challenges and future perspectives in this regard are also discussed.

Copper (Ⅱ)/cis-platinum -loaded nanogels as an adjuvant potentiate disulfiram antitumor efficacy

Disulfiram (DSF) is nontoxic and exerts anticancer activity by forming highly toxic chelate via its metabolite diethyldithiocarbamate with transition metal ions. However, there are not enough such ions in the...

Glutathione-responsive copper-disulfiram nanoparticles for enhanced tumor chemotherapy

Disulfiram (DSF), a familiar FDA-approved drug used for alcohol withdrawal, has recently been verified with potent antitumor therapeutic effect by generating Cu(DTC)₂, which is the complex of its metabolite diethyldithiocarbamate (DTC) and copper. However, its poor tumor selectivity and insufficient endogenous Cu²⁺ concentration within tumor site largely hinders the application of DSF-based antitumor therapy. Therefore, a GSH-responsive coordination nanoparticles (Cu-IXZ@DSF) was established as a copper carrier to achieve synchronous but separate delivery of Cu²⁺ and DSF without antitumor ability, further to realize selectively triggered tumor in situ Cu(DTC)₂ generation for antitumor therapy. A widely-used proteasome inhibitor ixazomib (IXZ) was chosen as ligands and Cu²⁺ was used as coordination nodes to form nanosized Cu-IXZ@DSF. The DSF encapsulated in Cu-IXZ@DSF could be reduced to DTC by intracellular GSH, which could contend for Cu²⁺ and realize in situ high toxic Cu(DTC)₂ generation. Meanwhile, the chelation could lead to the disassembly of Cu-IXZ@DSF and release of IXZ to eventually achieve tumor specific "transformation from low toxicity to high toxicity" chemotherapy. The results of in vitro and in vivo experiments demonstrated that the as-prepared nanoplatform Cu-IXZ@DSF showed good biosafety and excellent antitumor effect via endoplasmic reticulum stress (ERS) as well as reactive oxygen species (ROS) generation pathway. Therefore, this nanocarrier provides an inspiring strategy with specific-triggered antitumor Cu(DTC)₂ generation for DSF-based chemotherapy with high therapeutic effect and biosafety and showing great potential of treating cancer.

Autophagy-Dependent Apoptosis Induced by Apoferritin-Cu(II) Nanoparticles in Multidrug-Resistant Colon Cancer Cells

Chemotherapy continues to be the most commonly applied strategy for cancer. Despite the impressive clinical success obtained with several drugs, increasing numbers of (multi)drug-resistant tumors are reported. To overcome this shortcoming, novel drug candidates and delivery systems are urgently needed. Herein, a therapeutic copper polypyridine complex encapsulated in natural nanocarrier apoferritin is reported. The generated nanoparticles showed higher cytotoxicity toward various (drug-resistant) cancer cell lines than noncancerous cells. The study of the mechanism revealed that the compound triggers cell autophagy-dependent apoptosis. Promisingly, upon injection of the nanodrug conjugate into the bloodstream of a mouse model bearing a multidrug-resistant colon tumor, a strong tumor growth inhibition effect was observed. To date, this is the first study describing the encapsulation of a copper complex in apoferritin that acts by autophagy-dependent apoptosis.

Metal-coordinated nanomedicine for combined tumor therapy by inducing paraptosis and apoptosis

Apoptosis resistance of tumor cells often results in chemoresistance and treatment failure in clinic. In this work, a Cu²⁺-coordinated morusin/doxorubicin biological organizer (designated as COMBO) is designed to combat cellular resistance to apoptosis for combined tumor therapy. By virtue of the coordination and π-π stacking effects, the self-assembled COMBO possesses nanometer particle size, narrow and homogenous graininess distribution as well as a good dispersion stability. Moreover, COMBO could be disassembled by glutathione (GSH) with an effective drug release and fluorescence recovery. Morusin-mediated paraptosis could induce extensive vacuolization through the dilation of endoplasmic reticulum (ER) and mitochondria, leading to non-apoptotic programmed cell death (PCD) regardless of the cellular resistance to apoptosis. Furthermore, the released doxorubicin prefers to locate in cell nucleus to cause cell apoptosis for combined chemotherapy. By the joint action of paraptosis and apoptosis, COMBO exhibits a great superiority over monotherapy in tumor inhibition with a low system toxicity. This study may open a window in the development of self-delivery nanomedicine for overcoming apoptosis resistance in tumor therapy.

Ca2+ overload- and ROS-associated mitochondrial dysfunction contributes to δ-tocotrienol-mediated paraptosis in melanoma cells

Melanoma is an aggressive tumor with still poor therapy outcomes. δ-tocotrienol (δ-TT) is a vitamin E derivative displaying potent anti-cancer properties. Previously, we demonstrated that δ-TT triggers apoptosis in human melanoma cells. Here, we investigated whether it might also activate paraptosis, a non-canonical programmed cell death. In accordance with the main paraptotic features, δ-TT was shown to promote cytoplasmic vacuolization, associated with endoplasmic reticulum/mitochondrial dilation and protein synthesis, as well as MAPK activation in A375 and BLM cell lines. Moreover, treated cells exhibited a significant reduced expression of OXPHOS complex I and a marked decrease in oxygen consumption and mitochondrial membrane potential, culminating in decreased ATP synthesis and AMPK phosphorylation. This mitochondrial dysfunction resulted in ROS overproduction, found to be responsible for paraptosis induction. Additionally, δ-TT caused Ca²⁺ homeostasis disruption, with endoplasmic reticulum-derived ions accumulating in mitochondria and activating the paraptotic signaling. Interestingly, by using both IP3R and VDAC inhibitors, a close cause-effect relationship between mitochondrial Ca²⁺ overload and ROS generation was evidenced. Collectively, these results provide novel insights into δ-TT anti-melanoma activity, highlighting its ability to induce mitochondrial dysfunction-mediated paraptosis. δ-tocotrienol induces paraptotic cell death in human melanoma cells, causing endoplasmic reticulum dilation and mitochondrial swelling. These alterations induce an impairment of mitochondrial function, ROS production and calcium overload.

Perspectives of nano-carrier drug delivery systems to overcome cancer drug resistance in the clinics

Advanced cancer is still considered an incurable disease because of its metastatic spread to distal organs and progressive gain of chemoresistance. Even though considerable treatment progress and more effective therapies have been achieved over the past years, recurrence in the long-term and undesired side effects are still the main drawbacks of current clinical protocols. Moreover, a majority of chemotherapeutic drugs are highly hydrophobic and need to be diluted in organic solvents, which cause high toxicity, in order to reach effective therapeutic dose. These limitations of conventional cancer therapies prompted the use of nanomedicine, the medical application of nanotechnology, to provide more effective and safer cancer treatment. Potential of nanomedicines to overcome resistance, ameliorate solubility, improve pharmacological profile, and reduce adverse effects of chemotherapeutical drugs is thus highly regarded. Their use in the clinical setting has increased over the last decade. Among the various existing nanosystems, nanoparticles have the ability to transform conventional medicine by reducing the adverse effects and providing a controlled release of therapeutic agents. Also, their small size facilitates the intracellular uptake. Here, we provide a closer review of clinical prospects and mechanisms of action of nanomedicines to overcome drug resistance. The significance of specific targeting towards cancer cells is debated as well.

Honokiol induces paraptosis-like cell death of acute promyelocytic leukemia via mTOR & MAPK signaling pathways activation

Acute promyelocytic leukemia (APL) is a blood system disease caused by the accumulation of a large number of immature blood cells in bone marrow. Although the introduction of all-trans retinoic acid (ATRA) and arsenic has reached a high level of complete remission rate and 5-year disease-free survival rate, the occurrence of various adverse reactions still severely affects the quality of life of patients. As a natural product, honokiol (HNK) has the advantages of low toxicity and high efficiency, and it is a potential drug for the treatment of cancer. Since cancer cells can escape apoptotic cell death through multiple adaptive mechanisms, HNK, a drug that induces cancer cell death in a nonapoptotic way, has attracted much interest. We found that HNK reduced the viability of human APL cell line (NB4 cells) by inducing paraptosis-like cell death. The process was accompanied by excessive reactive oxygen species (ROS), mitochondrial damage, endoplasmic reticulum stress, and increased microtubule-associated protein 1 light chain 3 (LC3) processing. The inactivation of proteasome activity was the main cause of misfolded and unfolded protein accumulation in endoplasmic reticulum, such as LC3II/I and p62. This phenomenon could be alleviated by adding cycloheximide (CHX), a protein synthesis inhibitor. We found that mTOR signaling pathway participated in paraptosis-like cell death induced by HNK in an autophagy-independent process. Moreover, the mitogen-activated protein kinase (MAPK) signaling pathway induced paraptosis of NB4 cells by promoting endoplasmic reticulum stress. In summary, these findings indicate that paraptosis may be a new way to treat APL, and provide novel insights into the potential mechanism of paraptosis-like cell death.

Therapeutic iminoboronate-based polymersomes with a Cu(ii)-mediated Fenton reaction-enhanced ROS-response

Reactive oxygen species (ROS)-responsive prodrug nanoplatforms may not work efficiently due to insufficient ROS concentrations, so therapeutic polymersomes of a metallisable triamine-centered iminoboronate-functionalized amphiphilic starlike prodrug (N₃-(OEG-IBCAPE)₄) are prepared to show a Cu(ii)-mediated Fenton reaction-enhanced ROS response.

Isorhamnetin induces the paraptotic cell death through ROS and the ERK/MAPK pathway in OSCC cells

OBJECTIVE

There were rarely investigations on the effects and molecular mechanisms of oral squamous cell carcinoma (OSCC) cells when treated with isorhamnetin. This article assesses the anti-cancer effect of isorhamnetin.

METHODS AND MATERIALS

Oral squamous cell carcinoma cells were treated with or without isorhamnetin. Cell proliferation, cell cycle arrest, cell migration, cell death, and the related signaling pathways were evaluated.

RESULTS

The results revealed that cell proliferation was inhibited in a dose- and time-dependent manner, which was confirmed by diminished cell viability and revealed by decreased in the number of cell colonies. In addition, the cell cycle arrested in the G2/M phase, and the protein levels of cyclin B1 and CDC2 were suppressed. Moreover, the cell migration was inhibited, and the protein levels of related proteins were modulated. Furthermore, it could be observed that abundant cytoplasmic vacuoles existed which that were derived from mitochondria and the endoplasmic reticulum. It was confirmed that cell death did not result from apoptosis and may have which may be apt to paraptosis. Isorhamnetin was observed to upregulate phosphorylated ERK cascades and increase intracellular reactive oxygen species levels.

CONCLUSIONS

Our study suggested that the anti-cancer effect of isorhamnetin might trigger paraptosis, which may indicate a new therapeutic approach to OSCC.

Recent Advances in Nanostrategies Capable of Overcoming Biological Barriers for Tumor Management

Engineered nanomaterials have been extensively employed as therapeutics for tumor management. Meanwhile, the complex tumor niche along with multiple barriers at the cellular level collectively hinders the action of nanomedicines. Here, the advanced strategies that hold promise for overcoming the numerous biological barriers facing nanomedicines are summarized. Starting from tumor entry, methods that promote tissue penetration of nanomedicine and address the hypoxia issue are also highlighted. Then, emphasis is given to the significance of overcoming both physical barriers, such as membrane-associated efflux pumps, and biological features, such as resistance to apoptosis. The pros and cons for an individual approach are presented. In addition, the associated technical problems are discussed, along with the importance of balancing the therapeutic merits and the additional cost of sophisticated nanomedicine designs.

Iodine‑125 seed radiation induces ROS‑mediated apoptosis, autophagy and paraptosis in human esophageal squamous cell carcinoma cells

Iodine-125 (¹²⁵I) seed brachytherapy has been proven to be a safe and effective treatment for advanced esophageal cancer; however, the mechanisms underlying its actions are not completely understood. In the present study, the anti-cancer mechanisms of ¹²⁵I seed radiation in human esophageal squamous cell carcinoma (ESCC) cells (Eca-109 and KYSE-150) were determined, with a particular focus on the mode of cell death. The results showed that ¹²⁵I seed radiation significantly inhibited cell proliferation, and induced DNA damage and G2/M cell cycle arrest in both ESCC cell lines. ¹²⁵I seed radiation induced cell death through both apoptosis and paraptosis. Eca-109 cells were primarily killed by inducing caspase-dependent apoptosis, with 6 Gy radiation resulting in the largest response. KYSE-150 cells were primarily killed by inducing paraptosis, which is characterized by extensive cytoplasmic vacuolation. ¹²⁵I seed radiation induced autophagic flux in both ESCC cell lines, and autophagy inhibition by 3-methyladenine enhanced radiosensitivity. Furthermore ¹²⁵I seed radiation induced increased production of reactive oxygen species (ROS) in both ESCC cell lines. Treatment with an ROS scavenger significantly attenuated the effects of ¹²⁵I seed radiation on endoplasmic reticulum stress, autophagy, apoptosis, paraptotic vacuoles and reduced cell viability. In vivo experiments showed that ¹²⁵I seed brachytherapy induced ROS generation, initiated cell apoptosis and potential paraptosis, and inhibited cell proliferation and tumor growth. In summary, the results demonstrate that in ESCC cells, ¹²⁵I seed radiation induces cell death through both apoptosis and paraptosis; and at the same time initiates protective autophagy. Additionally, ¹²⁵I seed radiation-induced apoptosis, paraptosis and autophagy was considerably mediated by ROS.

N-Oxide polymer-cupric ion nanogels potentiate disulfiram for cancer therapy

Disulfiram (DSF) exerts potent anticancer activity via the formation of chelates with copper or zinc ions in tumor tissues, but the low abundance of these ions in the tumor cannot sustain its antitumor activity. Herein, we show that a zwitterionic water-soluble N-oxide polymer, poly[2-(N-oxide-N,N-dimethylamino)ethyl methacrylate] (OPDMA), can complex cupric ions and form nanogels (OPDMA/Cu), which efficiently deliver copper ions to tumor tissue to potentiate DSF significantly for effective antitumor therapy.

Thermal-Responsive Carbon Monoxide (CO) Delivery Expedites Metabolic Exhaustion of Cancer Cells toward Reversal of Chemotherapy Resistance

Multidrug resistance (MDR) is the main cause of chemotherapy failure, and the mechanism of MDR is largely associated with drug efflux mediated by the adenosine triphosphate (ATP)-binding cassette transporters. Herein, an NIR-light-triggered CO release system based on mesoporous Prussian blue nanoparticles (PB NPs) was developed to reverse MDR via CO-induced metabolic exhaustion. Pentacarbonyl iron (Fe(CO)₅) as the CO producer was coupled to PB NPs via coordination interaction, and doxorubicin (Dox) was encapsulated into the pores of PB NPs. After layer-by-layer (LBL) coating, the NPs showed desired serum stability to enhance tumor accumulation. Upon tumor-site-specific NIR light (808 nm) irradiation, the nonlethal temperature elevation cleaved the Fe-CO bond to release CO. CO then expedited mitochondrial metabolic exhaustion to block ATP synthesis and inhibit ATP-dependent drug efflux, thus reversing MDR of the Dox-resistant MCF-7/ADR tumors to potentiate the anticancer efficacy of Dox. In the meantime, CO-mediated mitochondrial exhaustion could upregulate the proapoptotic protein, caspase 3, thus inducing cellular apoptosis and enabling a synergistic anticancer effect with chemotherapy. To the best of our knowledge, this is the first time MDR has been overcome using a CO delivery system. This study provides a promising strategy to realize an effective and safe treatment against MDR tumors and reveals new insights in the use of CO for cancer treatment.

Temporally Controlled Photothermal/Photodynamic and Combined Therapy for Overcoming Multidrug Resistance of Cancer by Polydopamine Nanoclustered Micelles

Currently, the simple integration of multiple therapeutic agents within a single nanostructure for combating multidrug resistance (MDR) tumors yet remains a challenge. Herein, we report a photoresponsive nanocluster (NC) system prepared by installing polydopamine (PDA) nanoparticle clusters on the surface of d-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS) (a drug efflux inhibitor) micelles solubilized with IR780 (a photosensitizer) to achieve a combined chemotherapy (CT)/photothermal therapy (PTT)/photodynamic therapy (PDT) for drug-resistant breast cancer. Mediated by the fluorescence resonance energy transfer and radical scavenging properties of PDA, NC shows prominently quenched fluorescence emission (∼78%) and inhibited singlet oxygen generation (∼67%) upon exposure to near-infrared (NIR) light (808 nm, 0.5 W cm^-2), favoring a highly efficient PTT module. Meanwhile, the photothermal heat can also boost the release of doxorubicin hydrochloride whose intracellular accumulation can be greatly enhanced by TPGS. Interestingly, the first NIR irradiation and subsequent incubation (∼24 h) can induce the gradual relocation and disintegration of PDA nanoparticles, thereby leading to activated PDT therapy under the second irradiation. Upon the temporally controlled sequential application of PTT/PDT, the developed NC exhibited a great potential to treat MDR cancer both in vitro and in vivo. These findings suggest that complementary interactions among PTT/PDT/CT modalities can enhance the efficiency of the combined therapy for MDR tumor.

Complexes of lanthanides(iii) with mixed 2,2′-bipyridyl and 5,7-dibromo-8-quinolinoline chelating ligands as a new class of promising anti-cancer agents

MeOMBrQ-Ho induced HeLa cell apoptosis was mediated by inhibition of telomerase activity and dysfunction of mitochondria. Remarkably, MeOMBrQ-Ho obviously inhibited HeLa xenograft tumor growth in vivo.

Curcuminoid B63 induces ROS-mediated paraptosis-like cell death by targeting TrxR1 in gastric cells

Gastric cancer is one of the leading causes of cancer-related deaths. Chemotherapy has improved long-term survival of patients with gastric cancer. Unfortunately, cancer readily develops resistance to apoptosis-inducing agents. New mechanisms, inducing caspase-independent paraptosis-like cell death in cancer cells is presently emerging as a potential direction. We previously developed a curcumin analog B63 as an anti-cancer agent in pre-clinical evaluation. In the present study, we evaluated the effect and mechanism of B63 on gastric cancer cells. Our studies show that B63 targets TrxR1 protein and increases cellular reactive oxygen species (ROS) level, which results in halting gastric cancer cells and inducing caspase-independent paraptotic modes of death. The paraptosis induced by B63 was mediated by ROS-mediated ER stress and MAPK activation. Either overexpression of TrxR1 or suppression of ROS normalized B63-induced paraptosis in gastric cancer cells. Furthermore, B63 caused paraptosis in 5-fluorouracil-resistant gastric cancer cells, and B63 treatment reduced the growth of gastric cancer xenografts, which was associated with increased ROS and paraptosis. Collectively, our findings provide a novel strategy for the treatment of gastric cancer by utilizing TrxR1-mediated oxidative stress generation and subsequent cell paraptosis.

Disulfiram Copper Nanoparticles Prepared with a Stabilized Metal Ion Ligand Complex Method for Treating Drug-Resistant Prostate Cancers

Disulfiram (DSF), an alcohol-aversion drug, has been explored for cancer treatment. Copper diethyldithiocarbamate (Cu(DDC)₂) complex formed by DSF and copper ions is a major active ingredient for its anticancer activity. Direct administration of Cu(DDC)₂ is a promising strategy to enhance the anticancer efficacy of DSF. However, efficient drug delivery remains a significant challenge for Cu(DDC)₂ and hinders its clinical use. In this study, we developed a facile stabilized metal ion ligand complex (SMILE) method to prepare Cu(DDC)₂ nanoparticles (NPs). The SMILE method could prepare Cu(DDC)₂ NPs with different types of stabilizers including 1,2-distearoyl- sn-glycerol-3-phosphoethanolamine-poly(ethylene glycol) (PEG) 2000, d-α-tocopherol PEG 1000 succinate, methoxy PEG 5000- b-poly(l-lactide) 5000, and other generally recognized as safe excipients approved by the US Food and Drug Administration. The optimized formulations demonstrated excellent drug-loading efficiency (close to 100%), high drug concentrations (increased drug concentration by over 200-fold compared to the traditional micelle formulation), and an optimal particle size in the sub-100 nm range. Cu(DDC)₂ NPs exhibited outstanding stability in serum for 72 h and can also be stored at room temperature for at least 1 month. The anticancer effects of Cu(DDC)₂ NP formulations were determined by multiple assays including 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, colony-forming assay, calcein-AM/propidium iodide staining, and others. Cu(DDC)₂ NPs showed excellent activity against drug-resistant prostate cancer cells and other cancer cells with a half-maximal inhibitory concentration (IC₅₀) of around 100 nM. Our study also demonstrated that Cu(DDC)₂ NPs induced cell death in drug-resistant prostate cancer cells (DU145-TXR) through paraptosis, which is a nonapoptotic cell death. To our best knowledge, the SMILE method provides, for the first time, a simple yet efficient process for generating Cu(DDC)₂ NPs with high drug concentration, excellent loading efficiency, and desirable physicochemical properties. This method could potentially address drug delivery challenges of DSF/copper-based chemotherapy and facilitate its clinical translation.

Syntheses and biological studies of nitroimidazole conjugated heteroscorpionate ligands and related Cu(I) and Cu(II) complexes

Copper(I) and copper(II) complexes of 5-nitroimidazole conjugated heteroscorpionate ligands have been synthesized. In particular, the new 2,2-bis(pyrazol-1-yl)-N-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl)acetamide ligand (L^HMN) was synthesized by direct coupling of preformed side chain acid with 5-nitroimidazole and its coordination chemistry was investigated towards Cu(I) and Cu(II) acceptors and compared with that of the related 2,2-bis(3,5-dimethyl-1-H-pyrazol-1-yl)-N-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl)acetamide ligand (L^MeMN). The copper(II) complexes {[(L^MeMN)₂Cu]Cl₂} and {[(L^HMN)₂Cu]Cl₂} were prepared by the reaction of CuCl₂·2H₂O with L^HMN or L^MeMN ligands in methanol solution. The water soluble copper(I) complexes {[(L^MeMN)Cu(PTA)₂]}(PF₆) and {[(L^HMN)Cu(PTA)₂]}(PF₆) were prepared by the reaction of Cu(CH₃CN)₄PF₆ and 1,3,5-triaza-7-phosphaadamantane (PTA) with L^HMN or L^MeMN ligands in acetonitrile solution. The new Cu(I) and Cu(II) complexes as well as the corresponding uncoordinated ligands were evaluated for their cytotoxic activity against 2D monolayer cultures of multiple human cancer cell lines and 3D-cultured HCT-15 colon cancer spheroids. Morphological analysis by Transmission Electron Microscopy (TEM) revealed the induction of a massive cytoplasmic vacuolization consistent with a paraptotic-like cancer cell death.

Porphyrin–ferrocene conjugates for photodynamic and chemodynamic therapy

Porphyrin–ferrocene conjugates were designed and synthesized for photodynamic and chemodynamic therapy.