Cisplatin Resistance and Redox-Metabolic Vulnerability: A Second Alteration

Drug resistance mechanisms and treatment strategies mediated by Ubiquitin-Specific Proteases (USPs) in cancers: new directions and therapeutic options

Drug resistance represents a significant obstacle in cancer treatment, underscoring the need for the discovery of novel therapeutic targets. Ubiquitin-specific proteases (USPs), a subclass of deubiquitinating enzymes, play a pivotal role in protein deubiquitination. As scientific research advances, USPs have been recognized as key regulators of drug resistance across a spectrum of treatment modalities, including chemotherapy, targeted therapy, immunotherapy, and radiotherapy. This comprehensive review examines the complex relationship between USPs and drug resistance mechanisms, focusing on specific treatment strategies and highlighting the influence of USPs on DNA damage repair, apoptosis, characteristics of cancer stem cells, immune evasion, and other crucial biological functions. Additionally, the review highlights the potential clinical significance of USP inhibitors as a means to counter drug resistance in cancer treatment. By inhibiting particular USP, cancer cells can become more susceptible to a variety of anti-cancer drugs. The integration of USP inhibitors with current anti-cancer therapies offers a promising strategy to circumvent drug resistance. Therefore, this review emphasizes the importance of USPs as viable therapeutic targets and offers insight into fruitful directions for future research and drug development. Targeting USPs presents an effective method to combat drug resistance across various cancer types, leading to enhanced treatment strategies and better patient outcomes.

Moving beyond cisplatin resistance: mechanisms, challenges, and prospects for overcoming recurrence in clinical cancer therapy

Cisplatin, a classical platinum-based chemotherapy agent, has been a frontline treatment for various cancers for decades. However, its effectiveness has been hindered by the development of resistance, leading to cancer relapse. Addressing this challenge is crucial for both clinical practice and research. Hence, the imperative to unravel the intricate mechanisms underpinning cisplatin resistance and to uncover novel strategies to overcome this barrier holds immense significance. Within this review, we summarized the classification of platinum agents, highlighting their roles in therapeutic landscapes. We discussed the diverse mechanisms behind cisplatin resistance, including diminished intracellular cisplatin accumulation, intracellular detoxification, DNA repair, autophagy responses, heat shock proteins, tumor microenvironment, cancer stem cells, epigenetic regulation, ferroptosis resistance, and metabolic reprogramming. Drawing from this comprehensive understanding, we offered a series of prospective solutions to surmount cisplatin resistance and consequently mitigate the specter of disease recurrence within the realm of clinical cancer therapy.

Metallodrugs in the battle against non-small cell lung cancer: unlocking the potential for improved therapeutic outcomes

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer mortality worldwide. Platinum-based chemotherapy is standard-of-care but has limitations including toxicity and resistance. Metal complexes of gold, ruthenium, and other metals have emerged as promising alternatives. This review provides a comprehensive analysis of metallodrugs for NSCLC. Bibliometric analysis reveals growing interest in elucidating mechanisms, developing targeted therapies, and synergistic combinations. Classification of metallodrugs highlights platinum, gold, and ruthenium compounds, as well as emerging metals. Diverse mechanisms include DNA damage, redox modulation, and immunomodulation. Preclinical studies demonstrate cytotoxicity and antitumor effects in vitro and in vivo, providing proof-of-concept. Clinical trials indicate platinums have utility but resistance remains problematic. Non-platinum metallodrugs exhibit favorable safety but modest single agent efficacy to date. Drug delivery approaches like nanoparticles show potential to enhance therapeutic index. Future directions include optimization of metal-based complexes, elucidation of resistance mechanisms, biomarker development, and combination therapies to fully realize the promise of metallodrugs for NSCLC.

The Role of mTORC1 Pathway and Autophagy in Resistance to Platinum-Based Chemotherapeutics

Cisplatin (cis-diamminedichloroplatinum I) is a platinum-based drug, the mainstay of anticancer treatment for numerous solid tumors. Since its approval by the FDA in 1978, the drug has continued to be used for the treatment of half of epithelial cancers. However, resistance to cisplatin represents a major obstacle during anticancer therapy. Here, we review recent findings on how the mTORC1 pathway and autophagy can influence cisplatin sensitivity and resistance and how these data can be applicable for the development of new therapeutic strategies.

Dual inhibition of IDO1/TDO2 enhances anti-tumor immunity in platinum-resistant non-small cell lung cancer

BACKGROUND

The impact of non-small cell lung cancer (NSCLC) metabolism on the immune microenvironment is not well understood within platinum resistance. We have identified crucial metabolic differences between cisplatin-resistant (CR) and cisplatin-sensitive (CS) NSCLC cells with elevated indoleamine 2,3-dioxygenase-1 (IDO1) activity in CR, recognized by increased kynurenine (KYN) production.

METHODS

Co-culture, syngeneic, and humanize mice models were utilized. C57BL/6 mice were inoculated with either Lewis lung carcinoma mouse cells (LLC) or their platinum-resistant counterpart (LLC-CR) cells. Humanized mice were inoculated with either A (human CS cells) or ALC (human CR cells). Mice were treated with either IDO1 inhibitor or TDO2 (tryptophan 2,3-dioxygenase-2) inhibitor at 200 mg/kg P.O. once a day for 15 days; or with a new-in-class, IDO1/TDO2 dual inhibitor AT-0174 at 170 mg/kg P.O. once a day for 15 days with and without anti-PD1 antibody (10 mg/kg, every 3 days). Immune profiles and KYN and tryptophan (TRP) production were evaluated.

RESULTS

CR tumors exhibited a more highly immunosuppressive environment that debilitated robust anti-tumor immune responses. IDO1-mediated KYN production from CR cells suppressed NKG2D on immune effector natural killer (NK) and CD8⁺ T cells and enhanced immunosuppressive populations of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Importantly, while selective IDO1 inhibition attenuated CR tumor growth, it concomitantly upregulated the TDO2 enzyme. To overcome the compensatory induction of TDO2 activity, we employed the IDO1/TDO2 dual inhibitor, AT-0174. Dual inhibition of IDO1/TDO2 in CR mice suppressed tumor growth to a greater degree than IDO1 inhibition alone. Significant enhancement in NKG2D frequency on NK and CD8⁺ T cells and a reduction in Tregs and MDSCs were observed following AT-1074 treatment. PD-L1 (programmed death-ligand-1) expression was increased in CR cells; therefore, we assessed dual inhibition + PD1 (programmed cell death protein-1) blocking and report profound anti-tumor growth and improved immunity in CR tumors which in turn extended overall survival in mice.

CONCLUSION

Our study reports the presence of platinum-resistant lung tumors that utilize both IDO1/TDO2 enzymes for survival, and to escape immune surveillance as a consequence of KYN metabolites. We also report early in vivo data in support of the potential therapeutic efficacy of the dual IDO1/TDO2 inhibitor AT-0174 as a part of immuno-therapeutic treatment that disrupts tumor metabolism and enhances anti-tumor immunity.

The Oligostilbene Gnetin H Is a Novel Glycolysis Inhibitor That Regulates Thioredoxin Interacting Protein Expression and Synergizes with OXPHOS Inhibitor in Cancer Cells

Since aerobic glycolysis was first observed in tumors almost a century ago by Otto Warburg, the field of cancer cell metabolism has sparked the interest of scientists around the world as it might offer new avenues of treatment for malignant cells. Our current study claims the discovery of gnetin H (GH) as a novel glycolysis inhibitor that can decrease metabolic activity and lactic acid synthesis and displays a strong cytostatic effect in melanoma and glioblastoma cells. Compared to most of the other glycolysis inhibitors used in combination with the complex-1 mitochondrial inhibitor phenformin (Phen), GH more potently inhibited cell growth. RNA-Seq with the T98G glioblastoma cell line treated with GH showed more than an 80-fold reduction in thioredoxin interacting protein (TXNIP) expression, indicating that GH has a direct effect on regulating a key gene involved in the homeostasis of cellular glucose. GH in combination with phenformin also substantially enhances the levels of p-AMPK, a marker of metabolic catastrophe. These findings suggest that the concurrent use of the glycolytic inhibitor GH with a complex-1 mitochondrial inhibitor could be used as a powerful tool for inducing metabolic catastrophe in cancer cells and reducing their growth.

Antimicrobial peptides CS-piscidin-induced cell death involves activation of RIPK1/PARP, and modification with myristic acid enhances its stability and tumor-targeting capability

Ovarian cancer (OC) is a highly lethal gynecological malignancy, often diagnosed at advanced stages with limited treatment options. Here, we demonstrate that the antimicrobial peptide CS-piscidin significantly inhibits OC cell proliferation, colony formation, and induces cell death. Mechanistically, CS-piscidin causes cell necrosis by compromising the cell membrane. Furthermore, CS-piscidin can activate Receptor-interacting protein kinase 1 (RIPK1) and induce cell apoptosis by cleavage of PARP. To improve tumor targeting ability, we modified CS-piscidin by adding a short cyclic peptide, cyclo-RGDfk, to the C-terminus (CS-RGD) and a myristate to the N-terminus (Myr-CS-RGD). Our results show that while CS-RGD exhibits stronger anti-cancer activity than CS-piscidin, it also causes increased cytotoxicity. In contrast, Myr-CS-RGD significantly improves drug specificity by reducing CS-RGD toxicity in normal cells while retaining comparable antitumor activity by increasing peptide stability. In a syngeneic mouse tumor model, Myr-CS-RGD demonstrated superior anti-tumor activity compared to CS-piscidin and CS-RGD. Our findings suggest that CS-piscidin can suppress ovarian cancer via multiple cell death forms and that myristoylation modification is a promising strategy to enhance anti-cancer peptide performance.

Glutamine metabolism targeting liposomes for synergistic chemosensitization and starvation therapy in ovarian cancer

Platinum-based chemotherapy is a first-line therapeutic regimen against ovarian cancer (OC); however, the therapeutic potential is always reduced by glutamine metabolism. Herein, a valid strategy of inhibiting glutamine metabolism was proposed to cause tumor starvation and chemosensitization. Specifically, reactive oxygen species-responsive liposomes were developed to co-deliver cisplatin (CDDP) and bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl) ethyl sulfide (BPTES) [C@B LPs]. The C@B LPs induced effective tumor cell starvation and significantly sensitized OC cells to CDDP by reducing glutathione generation to prevent CDDP detoxification, suppressing ATP production to avoid CDDP efflux, hindering nucleotide synthesis to aggravate DNA damage induced by CDDP, and blocking mammalian target of rapamycin (mTOR) signaling to promote cell apoptosis. More importantly, C@B LPs remarkably inhibited tumor growth in vivo and reduced the side effects. Taken together, this study provided a successful strategy of synergistic chemosensitization and starvation therapy escalating the rate of therapeutic success in OCs. STATEMENT OF SIGNIFICANCE: This work proposed a valid strategy of inhibiting glutamine metabolism to cause tumor starvation and chemosensitization. Specifically, ROS-responsive liposomes were developed to co-deliver cisplatin CDDP and BPTES [C@B LPs]. The C@B LPs induced effective tumor cell starvation and significantly sensitized OC cells to cisplatin by reducing glutathione generation to prevent cisplatin detoxification, suppressing ATP production to avoid cisplatin efflux, hindering nucleotide synthesis to aggravate DNA damage induced by cisplatin, and blocking mTOR signaling to promote cell apoptosis. More importantly, C@B LPs remarkably inhibited tumor growth in vivo and reduced the side effects. Taken together, this study provided a successful strategy of synergistic chemosensitization and starvation therapy escalating the rate of therapeutic success in OCs.

Modulation of redox homeostasis: A strategy to overcome cancer drug resistance

Cancer treatment is hampered by resistance to conventional therapeutic strategies, including chemotherapy, immunotherapy, and targeted therapy. Redox homeostasis manipulation is one of the most effective innovative treatment techniques for overcoming drug resistance. Reactive oxygen species (ROS), previously considered intracellular byproducts of aerobic metabolism, are now known to regulate multiple signaling pathways as second messengers. Cancer cells cope with elevated amounts of ROS during therapy by upregulating the antioxidant system, enabling tumor therapeutic resistance via a variety of mechanisms. In this review, we aim to shed light on redox modification and signaling pathways that may contribute to therapeutic resistance. We summarized the molecular mechanisms by which redox signaling-regulated drug resistance, including altered drug efflux, action targets and metabolism, enhanced DNA damage repair, maintained stemness, and reshaped tumor microenvironment. A comprehensive understanding of these interrelationships should improve treatment efficacy from a fundamental and clinical research point of view.

Targeting of the intracellular redox balance by metal complexes towards anticancer therapy

The development of cancers is often linked to the alteration of essential redox processes, and therefore, oxidoreductases involved in such mechanisms can be considered as attractive molecular targets for the development of new therapeutic strategies. On the other hand, for more than two decades, transition metals derivatives have been leading the research on drugs as alternatives to platinum-based treatments. The success of such compounds is particularly due to their attractive redox kinetics properties, favorable oxidation states, as well as routes of action different to interactions with DNA, in which redox interactions are crucial. For instance, the activity of oxidoreductases such as PHD2 (prolyl hydroxylase domain-containing protein) which can regulate angiogenesis in tumors, LDH (lactate dehydrogenase) related to glycolysis, and enzymes, such as catalases, SOD (superoxide dismutase), TRX (thioredoxin) or GSH (glutathione) involved in controlling oxidative stress, can be altered by metal effectors. In this review, we wish to discuss recent results on how transition metal complexes have been rationally designed to impact on redox processes, in search for effective and more specific cancer treatments.

Immune Evasion and Drug Resistance Mediated by USP22 in Cancer: Novel Targets and Mechanisms

Regulation of ubiquitination is involved in various processes in cancer occurrence and development, including cell cycle arrest, cell proliferation, apoptosis, invasion, metastasis, and immunity. Ubiquitination plays an important role not only at the transcriptional and post-translational levels but also at the protein level. When ubiquitination is in a pathological state, abnormally activated biological processes will not only induce cancer progression but also induce immune evasion. The main function of deubiquitinases (DUBs) is to remove ubiquitin chains from substrates, changing the biological activity of the substrates. It has great potential to improve the prognosis of cancer by targeting DUB to regulate proteome. Ubiquitin-specific peptidase 22 (USP22) belongs to the ubiquitin-specific protease (USP) family of DUBs and has been reported to be related to various physiological and pathological processes. USP22 is abnormally expressed in various malignant tumors such as prostate cancer, lung cancer, liver cancer, and colorectal cancer, which suggests that USP22 may play an important role in tumors. USP22 may stabilize programmed death ligand 1 (PD-L1) by deubiquitination while also regulating T-cell infiltration into tumors. Regulatory T cells (Tregs) are a unique class of immunosuppressive CD4⁺ T cells that primarily suppress the immune system by expressing the master transcription factor forkhead box protein 3 (FOXP3). USP22 was found to be a positive regulator of stable FOXP3 expression. Treg-specific ablation of USP22 leads to reduced tumor volume in multiple cancer models. This suggests that USP22 may regulate tumor resistance to immunotherapy. In this article, we review and summarize the biological functions of USP22 in multiple signal transduction pathways during tumorigenesis, immune evasion, and drug resistance. Furthermore, we propose a new possibility of combining USP22 with chemotherapeutic, targeted, and immunosuppressive drugs in the treatment of cancer.

Identification of New Regulators of Pancreatic Cancer Cell Sensitivity to Oxaliplatin and Cisplatin

The chemoresistance of tumor cells is one of the most urgent challenges in modern oncology and in pancreatic cancer, in which this problem is the most prominent. Therefore, the identification of new chemosensitizing co-targets may be a path toward increasing chemotherapy efficacy. In this work, we performed high-performance in vitro knockout CRISPR/Cas9 screening to find potential regulators of the sensitivity of pancreatic cancer. For this purpose, MIA PaCa-2 cells transduced with two sgRNA libraries (“cell cycle/nuclear proteins genes” and “genome-wide”) were screened by oxaliplatin and cisplatin. In total, 173 candidate genes were identified as potential regulators of pancreatic cancer cell sensitivity to oxaliplatin and/or cisplatin; among these, 25 genes have previously been reported, while 148 genes were identified for the first time as potential platinum drug sensitivity regulators. We found seven candidate genes involved in pancreatic cancer cell sensitivity to both cisplatin and oxaliplatin. Gene ontology enrichment analysis reveals the enrichment of single-stranded DNA binding, damaged DNA binding pathways, and four associated with NADH dehydrogenase activity. Further investigation and validation of the obtained results by in vitro, in vivo, and bioinformatics approaches, as well as literature analysis, will help to identify novel pancreatic cancer platinum sensitivity regulators.

Deferoxamine Counteracts Cisplatin Resistance in A549 Lung Adenocarcinoma Cells by Increasing Vulnerability to Glutamine Deprivation-Induced Cell Death

Glutamine, like glucose, is a major nutrient consumed by cancer cells, yet these cells undergo glutamine starvation in the cores of tumors, forcing them to evolve adaptive metabolic responses. Pharmacologically targeting glutamine metabolism or withdrawal has been exploited for therapeutic purposes, but does not always induce cancer cell death. The mechanism by which cancer cells adapt to resist glutamine starvation in cisplatin-resistant non-small-cell lung cancer (NSCLC) also remains uncertain. Here, we report the potential metabolic vulnerabilities of A549/DDP (drug-resistant human lung adenocarcinoma cell lines) cells, which were more easily killed by the iron chelator deferoxamine (DFO) during glutamine deprivation than their parental cisplatin-sensitive A549 cells. We demonstrate that phenotype resistance to cisplatin is accompanied by adaptive responses during glutamine deprivation partly via higher levels of autophagic activity and apoptosis resistance characteristics. Moreover, this adaptation could be explained by sustained glucose instead of glutamine-dominant complex II-dependent oxidative phosphorylation (OXPHOS). Further investigation revealed that cisplatin-resistant cells sustain OXPHOS partly via iron metabolism reprogramming during glutamine deprivation. This reprogramming might be responsible for mitochondrial iron-sulfur [Fe-S] cluster biogenesis, which has become an “Achilles’ heel,” rendering cancer cells vulnerable to DFO-induced autophagic cell death and apoptosis through c-Jun N-terminal kinase (JNK) signaling. Finally, in vivo studies using xenograft mouse models also confirmed the growth-slowing effect of DFO. In summary, we have elucidated the adaptive responses of cisplatin-resistant NSCLC cells, which balanced stability and plasticity to overcome metabolic reprogramming and permitted them to survive under stress induced by chemotherapy or glutamine starvation. In addition, for the first time, we show that suppressing the growth of cisplatin-resistant NSCLC cells via iron chelator-induced autophagic cell death and apoptosis was possible with DFO treatment. These findings provide a solid basis for targeting mitochondria iron metabolism in cisplatin-resistant NSCLC for therapeutic purposes, and it is plausible to consider that DFO facilitates in the improvement of treatment responses in cisplatin-resistant NSCLC patients.