bims-rehoca 2021-06-20 papers

bims-rehoca

Biomed News

on Redox homeostasis in cancer

Issue of 2021–06–20
seventeen papers selected by
Vittoria Raimondi, Veneto Institute of Oncology

MGST1, a new soldier of NRF2 in the battle against ferroptotic death.
Duramycin radiosensitization of MCA-RH 7777 hepatoma cells through the elevation of reactive oxygen species.
Self-Activating Therapeutic Nanoparticle: A Targeted Tumor Therapy Using Reactive Oxygen Species Self-Generation and Switch-on Drug Release.
Browsing the oldest antioxidant enzyme: catalase and its multiple regulation in cancer.
Ursolic acid disturbs ROS homeostasis and regulates survival-associated gene expression to induce apoptosis in intestinal cancer cells.
GLS1 depletion inhibited colorectal cancer proliferation and migration via redox/Nrf2/autophagy-dependent pathway.
Helenalin Facilitates Reactive Oxygen Species-Mediated Apoptosis and Cell Cycle Arrest by Targeting Thioredoxin Reductase-1 in Human Prostate Cancer Cells.
VHL regulates the sensitivity of clear cell renal cell carcinoma to SIRT4-mediated metabolic stress via HIF-1α/HO-1 pathway.
The immunomodulatory effects of topiramate on azoxymethane-induced colon carcinogenesis in rats: The role of the inflammatory cascade, vascular endothelial growth factor, AKT/mTOR/MAP kinase signaling and the apoptotic markers.
Combination of chemotherapy and oxidative stress to enhance cancer cell apoptosis.
Stabilization of fatty acid synthesis enzyme acetyl-CoA carboxylase 1 suppresses acute myeloid leukemia development.
The murburn precepts for aerobic respiration and redox homeostasis.
Calvatia Lilacina Extracts Exert Anti-Breast-Cancer Bioactivity through the Apoptosis Induction Dependent on Mitochondrial Reactive Oxygen Species and Caspase Activation.
QTMP, a Novel Thiourea Polymer, Causes DNA Damage to Exert Anticancer Activity and Overcome Multidrug Resistance in Colorectal Cancer Cells.
Photodynamic Therapy of Inorganic Complexes for the Treatment of Cancer.
Radiation Resistance: A Matter of Transcription Factors.
Dual-Targeting Polymeric Nanocarriers to Deliver ROS-Responsive Prodrugs and Combat Multidrug Resistance of Cancer Cells.

Cell Chem Biol. 2021 Jun 17. pii: S2451-9456(21)00258-0. [Epub ahead of print]28(6): 741-742

MGST1, a new soldier of NRF2 in the battle against ferroptotic death.

Matthew Dodson, Annadurai Anandhan, Donna D Zhang.

In this issue of Cell Chemical Biology, Kuang et al. (2021) identify microsomal glutathione-S-transferase 1 (MGST1) as an NRF2 target gene that suppresses ferroptosis in pancreatic cancer cells. Mechanistically, MGST1 binds ALOX5 during ferroptosis induction, inhibiting lipid peroxide production. Thus, MGST1 could represent a viable therapeutic target for treating pancreatic cancer.

DOI: https://doi.org/10.1016/j.chembiol.2021.05.013
J Cancer Res Ther. 2021 Apr-Jun;17(2):17(2): 543-546

Duramycin radiosensitization of MCA-RH 7777 hepatoma cells through the elevation of reactive oxygen species.

Bowen Yang, Xiaoke Huang, Weiguo Li, Samdeep Mouli, Robert J Lewandowski, Andrew Christian Larson.

   Objective: The objective of this study is to explore the radiosensitization effects of duramycin against the liver cancer hepatoma cells and relationship to reactive oxygen species (ROS) generation.
Materials and Methods: MCA-RH 7777 cells were treated with various combinations of duramycin concentrations and radiation doses. After the treatment, cell viabilities were determined by a cell proliferation assay; intracellular ROS levels were detected with the flow cytometric method.
Results: MCA-RH 7777 cell viability was found significantly reduced after combining duramycin and radiation exposure (comparing to that of either treatment alone). Increased intracellular ROS levels were observed in cells treated with combinations of duramycin and radiation.
Conclusion: Duramycin increased the intracellular ROS generation and also increased the radiosensitivity of MCA-RH 7777 cells.

Keywords:  Duramycin; radiosensitivity; reactive oxygen species

DOI:  https://doi.org/10.4103/jcrt.JCRT_284_18
ACS Appl Mater Interfaces. 2021 Jun 18.

Self-Activating Therapeutic Nanoparticle: A Targeted Tumor Therapy Using Reactive Oxygen Species Self-Generation and Switch-on Drug Release.

Rae Hyung Kang, Yumi Kim, Ji Hyeon Kim, Na Hee Kim, Hyun Min Ko, Seung-Hyeon Lee, Inseob Shim, Jong Seung Kim, Hyeung-Jin Jang, Dokyoung Kim.

  One of the recent advances in nanotechnology within the medical field is the development of a nanoformulation of anticancer drugs or photosensitizers. Cancer cell-specific drug delivery and upregulation of the endogenous level of reactive oxygen species (ROS) are important in precision anticancer treatment. Within our article, we report a new therapeutic nanoformulation of cancer cell targeting using endogenous ROS self-generation without an external initiator and a switch-on drug release (ROS-induced cascade nanoparticle degradation and anticancer drug generation). We found a substantial cellular ROS generation by treating an isothiocyanate-containing chemical and functionalizing it onto the surface of porous silicon nanoparticles (pSiNPs) that are biodegradable and ROS-responsive nanocarriers. Simultaneously, we loaded an ROS-responsive prodrug (JS-11) that could be converted to the original anticancer drug, SN-38, and conducted further surface functionalization with a cancer-targeting peptide, CGKRK. We demonstrated the feasibility as a cancer-targeting and self-activating therapeutic nanoparticle in a pancreatic cancer xenograft mouse model, and it showed a superior therapeutic efficacy through ROS-induced therapy and drug-induced cell death. The work presented is a new concept of a nanotherapeutic and provides a more feasible clinical translational pathway.

Keywords:  ROS-responsive prodrug; cancer therapy; drug-delivery system; porous silicon nanoparticles; reactive oxygen species

DOI:  https://doi.org/10.1021/acsami.1c07037
Free Radic Biol Med. 2021 Jun 12. pii: S0891-5849(21)00375-0. [Epub ahead of print]

Browsing the oldest antioxidant enzyme: catalase and its multiple regulation in cancer.

Marilisa Galasso, Simona Gambino, Maria Grazia Romanelli, Massimo Donadelli, Maria Teresa Scupoli.

  Aerobic organisms possess numerous antioxidant enzymatic families, including catalases, superoxide dismutases (SODs), peroxiredoxins (PRDXs), and glutathione peroxidases (GPXs), which work cooperatively to protect cells from an excess of reactive oxygen species (ROS) derived from endogenous metabolism or external microenvironment. Catalase, as well as other antioxidant enzymes, plays an important dichotomous role in cancer. Therefore, therapies aimed at either reverting the increased or further escalating catalase levels could be effective, depending on the metabolic landscape and on the redox status of cancer cells. This dichotomous role of catalase in cancers highlights the importance to deepen comprehensively the role and the regulation of this crucial antioxidant enzyme. The present review highlights the role of catalase in cancer and provides a comprehensive description of the molecular mechanisms associated with the multiple levels of catalase regulation.

Keywords:  Cancer; Catalase; Reactive oxygen species; gene expression regulation

DOI:  https://doi.org/10.1016/j.freeradbiomed.2021.06.010
Toxicol Res (Camb). 2021 May;10(3): 369-375

Ursolic acid disturbs ROS homeostasis and regulates survival-associated gene expression to induce apoptosis in intestinal cancer cells.

Laxminarayan Rawat, Vijayashree Nayak.

  Ursolic acid is a natural compound possessing several therapeutic properties including anticancer potential. In present study, cytotoxic and antimetastatic properties of ursolic acid were investigated in intestinal cancer cell lines INT-407 and HCT-116. The cells growth and number were decreased in a dose- and time-dependent manner in both the cell lines. It also increases reactive oxygen species levels in the cells in order to induce apoptosis. Ursolic acid was found to be a significant inhibitor of cancer cells migration and gene expression of migration markers FN1, CDH2, CTNNB1 and TWIST was also downregulated. Ursolic acid treatment downregulated the gene expression of survival factors BCL-2, SURVIVIN, NFKB and SP1, while upregulated the growth-restricting genes BAX, P21 and P53. These results indicate that ursolic acid has anticancer and antimetastatic properties against intestinal cancer. These properties could be beneficial in cancer treatment and could be used as complementary medicine.

Keywords:  NFKB, SP1; herbal medicine; intestinal cancer; reactive oxygen species; ursolic acid

DOI:  https://doi.org/10.1093/toxres/tfab025
Arch Biochem Biophys. 2021 Jun 11. pii: S0003-9861(21)00213-7. [Epub ahead of print]708 108964

GLS1 depletion inhibited colorectal cancer proliferation and migration via redox/Nrf2/autophagy-dependent pathway.

Hui-Yun Liu, Hong-Sheng Zhang, Min-Yao Liu, Hong-Ming Li, Xin-Yu Wang, Miao Wang.

  Cancer cells can metabolize glutamine to replenish TCA cycle intermediates for cell survival. Glutaminase (GLS1) is over-expressed in multiple cancers, including colorectal cancer (CRC). However, the role of GLS1 in colorectal cancer development has not yet fully elucidated. In this study, we found that GLS1 levels were significantly increased in CRC cells. Knockdown of GLS1 by shRNAs as well as GLS1 inhibitor BPTES decreased DLD1 and SW480 cell proliferation, colony formation and migration. Knockdown of GLS1 as well as BPTES induced reactive oxygen species (ROS) production, down-regulation of GSH/GSSG ratio, an decrease in Nrf2 protein expression and an increase in cytoplasmic Nrf2 protein expression in DLD1 and SW480 cells. Furthermore, Knockdown of GLS1 as well as BPTES inhibited autophagy pathway, antioxidant NAC and Nrf2 activator could reversed inhibition of GLS1-mediated an decrease in autophagic flux in DLD1 and SW480 cells. Depletion of GLS1-induced inhibition of DLD1 and SW480 CRC cell proliferation, colony formation and migration was reversed by autophagy inducer rapamycin. These results suggest that targeting GLS1 might be a new potential therapeutic target for the treatment of CRC.

Keywords:  Autophagy; Colorectal cancer; GLS1; Redox

DOI:  https://doi.org/10.1016/j.abb.2021.108964
Med Sci Monit. 2021 Jun 14. 27 e930083

Helenalin Facilitates Reactive Oxygen Species-Mediated Apoptosis and Cell Cycle Arrest by Targeting Thioredoxin Reductase-1 in Human Prostate Cancer Cells.

Mei Yang, Weihua Zhang, Xiuxiu Yu, Feng Wang, Yeping Li, Yan Zhang, Yu Yang.

BACKGROUND Helenalin is a pseudoguaianolide natural product with anti-cancer activities. This study investigated the underlying mechanism of the anti-prostate cancer effects of helenalin in vitro. MATERIAL AND METHODS CCK-8 assay was performed to detect the optimal concentrations of helenalin in DU145 and PC-3 cells. After exposure to helenalin and/or reactive oxygen species (ROS) inhibitor, ROS production was assessed by DCFH-DA staining. Thioredoxin reductase-1 (TrxR1) expression was detected by RT-qPCR and western blot. Moreover, apoptosis and cell cycle were evaluated by flow cytometry. Following TrxR1 knockdown or overexpression, TrxR1 expression, ROS generation, apoptosis, cell cycle, migration, and invasion were examined in cells co-treated with helenalin. RESULTS Helenalin distinctly repressed the viability of prostate cancer cells in a concentration-dependent manner. We chose 8 μM and 4 μM as the optimal concentrations of helenalin for DU145 and PC-3 cells, respectively. Helenalin treatment markedly triggered ROS production and lowered TrxR1 expression, which was ameliorated by ROS inhibitor. Exposure to helenalin facilitated apoptosis as well as G0/G1 cell cycle arrest, which was reversed by ROS inhibitor. Helenalin relieved the inhibitory effect of TrxR1 on ROS production. Furthermore, helenalin ameliorated the decrease in apoptosis rate and the shortening of G0/G1 phase as well as the increase in migration and invasion induced by TrxR1 overexpression. CONCLUSIONS Our findings revealed that helenalin accelerated ROS-mediated apoptosis and cell cycle arrest via targeting TrxR1 in human prostate cancer cells.

DOI: https://doi.org/10.12659/MSM.930083
Cell Death Dis. 2021 Jun 16. 12(7): 621

VHL regulates the sensitivity of clear cell renal cell carcinoma to SIRT4-mediated metabolic stress via HIF-1α/HO-1 pathway.

Ying Tong, Jinyan Kai, Shuo Wang, Yiwen Yu, Suhong Xie, Hui Zheng, Yanchun Wang, Yixuan Liu, Keyu Zhu, Xiaolin Guan, Lin Guo, Renquan Lu.

Clear cell renal cell carcinomas (ccRCC) reprogram carbon metabolism responses to hypoxia, thereby promoting utilization of glutamine. Recently, sirtuin 4 (SIRT4), a novel molecular has turned out to be related to alternating glutamine metabolism and modulating the tumor microenvironment. However, the role of SIRT4 in ccRCC remains poorly understood. Here, we illustrated that the expression of SIRT4 is markedly reduced in cancerous tissues, and closely associated with malignancy stage, grade, and prognosis. In ccRCC cells, SIRT4 exerted its proapoptotic activity through enhancing intracellular reactive oxygen species (ROS). Heme oxygenase-1 (HO-1) is part of an endogenous defense system against oxidative stress. Nevertheless, overexpression of SIRT4 hindered the upregulation of HO-1 in von Hippel-Lindau (VHL)-proficient cells and repressed its expression in VHL-deficient cells. This discrepancy indicated that competent VHL withstands the inhibitory role of SIRT4 on HIF-1α/HO-1. Functionally, overexpression of HO-1 counteracted the promotional effects of SIRT4 on ROS accumulation and apoptosis. Mechanistically, SIRT4 modulates ROS and HO-1 expression via accommodating p38-MAPK phosphorylation. By contrast, downregulation of p38-MAPK by SB203580 decreased intracellular ROS level and enhanced the expression of HO-1. Collectively, this work revealed a potential role for SIRT4 in the stimulation of ROS and the modulation of apoptosis. SIRT4/HO-1 may act as a potential therapeutic target, especially in VHL-deficient ccRCCs.

DOI: https://doi.org/10.1038/s41419-021-03901-7
Int Immunopharmacol. 2021 Jun 09. pii: S1567-5769(21)00466-5. [Epub ahead of print]98 107830

The immunomodulatory effects of topiramate on azoxymethane-induced colon carcinogenesis in rats: The role of the inflammatory cascade, vascular endothelial growth factor, AKT/mTOR/MAP kinase signaling and the apoptotic markers.

Ahmed M Kabel, Ahmed M Ashour, Dina A Ali, Hany H Arab.

   BACKGROUND: Colon cancer is a malignant condition that affects the lower gastrointestinal tract and has unfavorable prognosis. Its mechanisms range from enhanced production of reactive oxygen species, inflammatory changes in the colon microenvironment and affection of the apoptotic pathways. Due to the high incidence of resistance of colon cancer to the traditional chemotherapeutic agents, a need for finding safe/effective agents that can attenuate the malignant changes had emerged.
OBJECTIVE: To investigate the possible immunomodulatory and antitumor effects of topiramate on azoxymethane-induced colon cancer in rats.
METHODOLOGY: Fifty male Wistar rats were randomized into five equal groups as follows: Control; azoxymethane-induced colon cancer; azoxymethane + methyl cellulose; azoxymethane + topiramate small dose; and azoxymethane + topiramate large dose. The body weight gain, serum carcinoembryonic antigen (CEA), tissue antioxidant status, proinflammatory cytokines, vascular endothelial growth factor (VEGF), Nrf2/HO-1 content, p-AKT, mTOR, p38 MAP kinase, caspase 9, nerve growth factor beta and beclin-1 were measured. Also, parts of the colon had undergone histopathological and immunohistochemical evaluation.
KEY FINDINGS: Topiramate improved the body weight gain, decreased serum CEA, augmented the antioxidant defenses in the colonic tissues with significant amelioration of the inflammatory changes, decline in tissue VEGF and p-AKT/mTOR/MAP kinase signaling and increased Nrf2/HO-1 content in a dose-dependent manner when compared to rats treated with azoxymethane alone. In addition, topiramate, in a dose-dependent manner, significantly enhanced apoptosis and improved the histopathological picture in comparison to animals treated with azoxymethane alone.
CONCLUSION: Taking these findings together, topiramate might serve as a new effective adjuvant line of treatment of colon cancer.

Keywords:  Apoptosis; Azoxymethane; Colon cancer; Rats; Topiramate; p38 MAP kinase

DOI:  https://doi.org/10.1016/j.intimp.2021.107830
Chem Sci. 2020 Feb 25. 11(12): 3215-3222

Combination of chemotherapy and oxidative stress to enhance cancer cell apoptosis.

Xinming Li, Yanan Hou, Jintao Zhao, Jin Li, Song Wang, Jianguo Fang.

Cancer cells are vulnerable to reactive oxygen species (ROS) due to their abnormal redox environment. Accordingly, combination of chemotherapy and oxidative stress has gained increasing interest for the treatment of cancer. We report a novel seleno-prodrug of gemcitabine (Gem), Se-Gem, and evaluated its activation and biological effects in cancer cells. Se-Gem was prepared by introducing a 1,2-diselenolane (a five-membered cyclic diselenide) moiety into the parent drug Gem via a carbamate linker. Se-Gem is preferably activated by glutathione (GSH) and displays a remarkably higher potency than Gem (up to a 6-fold increase) to a panel of cancer cell lines. The activation of Se-Gem by GSH releases Gem and a seleno-intermediate nearly quantitatively. Unlike the most ignored side products in prodrug activation, the seleno-intermediate further catalyzes a conversion of GSH and oxygen to GSSG (oxidized GSH) and ROS via redox cycling reactions. Thus Se-Gem may be considered as a suicide agent to deplete GSH and works by a combination of chemotherapy and oxidative stress. This is the first case that employs a cyclic diselenide in prodrug design, and the success of Se-Gem as well as its well-defined action mechanism demonstrates that the 1,2-diselenolane moiety may serve as a general scaffold to advance constructing novel therapeutic molecules with improved potency via a combination of chemotherapy and oxidative stress.

DOI: https://doi.org/10.1039/c9sc05997k
J Clin Invest. 2021 Jun 15. pii: 141529. [Epub ahead of print]131(12):

Stabilization of fatty acid synthesis enzyme acetyl-CoA carboxylase 1 suppresses acute myeloid leukemia development.

Hidenori Ito, Ikuko Nakamae, Jun-Ya Kato, Noriko Yoneda-Kato.

  Cancer cells reprogram lipid metabolism during their malignant progression, but limited information is currently available on the involvement of alterations in fatty acid synthesis in cancer development. We herein demonstrate that acetyl-CoA carboxylase 1 (ACC1), a rate-limiting enzyme for fatty acid synthesis, plays a critical role in regulating the growth and differentiation of leukemia-initiating cells. The Trib1-COP1 complex is an E3 ubiquitin ligase that targets C/EBPA, a transcription factor regulating myeloid differentiation, for degradation, and its overexpression specifically induces acute myeloid leukemia (AML). We identified ACC1 as a target of the Trib1-COP1 complex and found that an ACC1 mutant resistant to degradation because of the lack of a Trib1-binding site attenuated complex-driven leukemogenesis. Stable ACC1 protein expression suppressed the growth-promoting activity and increased ROS levels with the consumption of NADPH in a primary bone marrow culture, and delayed the onset of AML with increases in mature myeloid cells in mouse models. ACC1 promoted the terminal differentiation of Trib1-COP1-expressing cells and eradicated leukemia-initiating cells in the early phase of leukemic progression. These results indicate that ACC1 is a natural inhibitor of AML development. The upregulated expression of the ACC1 protein has potential as an effective strategy for cancer therapy.

Keywords:  Cancer; Oncology; Tumor suppressors; Ubiquitin-proteosome system

DOI:  https://doi.org/10.1172/JCI141529
Prog Biophys Mol Biol. 2021 Jun 09. pii: S0079-6107(21)00060-2. [Epub ahead of print]

The murburn precepts for aerobic respiration and redox homeostasis.

Kelath Murali Manoj, N M Bazhin.

  Murburn concept is a new perspective to metabolism which posits that certain redox enzymes/proteins mediate catalysis outside their active site, via diffusible reactive oxygen species (DROS, usually deemed as toxic wastes). We have recently questioned the proton-centric chemiosmotic rotary ATP synthesis (CRAS) explanation for mitochondrial oxidative phosphorylation (mOxPhos) and proposed an oxygen-centric murburn model in lieu. Herein, the chemical equations and thermodynamic foundations for this new model of mOxPhos are detailed. Standard transformed Gibbs free energy values of respiratory reactions are calculated to address the spontaneity, control, and efficiency of oxidative phosphorylation. Unlike the deterministic/multi-molecular and 'irreducibly complex' CRAS model, the stochastic/bimolecular and parsimonious murburn reactions afford a more viable precept for the variable and non-integral stoichiometry, higher yield for NADH than FADH2, and origin/evolution of oxygen-centric cellular life. Also, we present tangible DROS-based explanations for the multiple roles of various reaction components, HCN > H2S order of cellular toxicity in aerobes, and explain why oxygen inhibits anaerobes. We highlight the thermodynamic significance of proton deficiency in NADH/mitochondria and link the 'oxygen → DROS → water' metabolic pathway to the macroscopic physiologies of ATP-synthesis, trans-membrane potential, thermogenesis, and homeostasis. We also provide arguments for the extension of the murburn bioenergetics model to life under anoxic and extreme/unique habitats. In the context of mOxPhos, our findings imply that DROS should be seen as an essential requisite for life, and not merely as pathophysiological manifestations.

Keywords:  Aerobic respiration; Bioenergetics; Chemiosmosis; Homeostasis; Murburn concept; Thermodynamics

DOI:  https://doi.org/10.1016/j.pbiomolbio.2021.05.010
Nutr Cancer. 2021 Jun 12. 1-13

Calvatia Lilacina Extracts Exert Anti-Breast-Cancer Bioactivity through the Apoptosis Induction Dependent on Mitochondrial Reactive Oxygen Species and Caspase Activation.

Qinghua Zeng, Ragini Singh, Yong Ye, Shuang Cheng, Chen Fan, Qingmei Zeng.

Puffballs are a class of fungi widely distributed worldwide and associated with various bioactivities. This research mainly showed the antitumor bioactivity of extracts from Calvatia lilacina (CL), which is a common variety of puffballs. NMR and high-performance liquid chromatography methods are used to characterize the extracts. Results showed that CL extracts obtained with petroleum ether, ethyl acetate, ethanol, and water elicited obvious inhibitory effects on the proliferation of A549, Caco-2, and MDA-MB-231. Among these extracts, petroleum ether extract demonstrated the highest performance. This extract was then separated into seven sub-fractions (SFs). Three of these SFs (3#, 6#, and 7#) induces a decrease in the viability of MDA-MB-231 cells in which 7# SF exhibited the highest cytotoxicity, where the major component was found to be ergosta-7,22-dien-3-one. Further tests revealed that 7# SF from petroleum ether extract could trigger severe cell death in human breast cancer cells (MDA-MB-231) by activating the apoptotic pathway dependent on mitochondrial reactive oxygen species and caspase activation. All these results in combination indicate that the mechanism of extract-potentiated apoptosis associates closely with ROS-dependent mitochondrial dysfunction events which further induces mitochondria-mediated intrinsic cytochrome C-caspase-related pathway of apoptosis.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1936576.

DOI: https://doi.org/10.1080/01635581.2021.1936576
Front Oncol. 2021 ;11 667689

QTMP, a Novel Thiourea Polymer, Causes DNA Damage to Exert Anticancer Activity and Overcome Multidrug Resistance in Colorectal Cancer Cells.

Zhaoshi Bai, Qing Zhou, Huayun Zhu, Xinyue Ye, Pingping Wu, Lingman Ma.

  Colorectal cancer (CRC) is one of the most common malignancies, and multidrug resistance (MDR) severely restricts the effectiveness of various anticancer drugs. Therefore, the development of novel anticancer drugs for the treatment of CRC patients with MDR is necessary. Quaternized thiourea main-chain polymer (QTMP) is a self-assembled nanoparticle with good water solubility. Notably, QTMP is not a P-glycoprotein (P-gp) substrate, and it exhibits potent cytotoxic activity against CRC cells, including HCT116/DDP and P-gp-mediated multidrug-resistant Caco2 cells. QTMP also exhibits a strong anticancer activity against SW480 cells in vivo. Interestingly, reactive oxygen species (ROS) and reactive nitrogen species (RNS) production were increased in a concentration-dependent manner in QTMP-treated HCT116, SW480 and Caco2 cells. Importantly, QTMP causes DNA damage in these CRC cells via direct insertion into the DNA or regulation of ROS and/or RNS production. QTMP also induces caspase-dependent apoptosis via overproduction of ROS and RNS. Therefore, QTMP is a promising anticancer therapeutic agent for patients with CRC, including those cancer cells with P-gp-mediated MDR. The present study also indicates that the design and synthesis of anticancer drugs based on thiourea polymers is promising and valuable, thereby offering a new strategy to address MDR, and provides reference resources for further investigations of thiourea polymers.

Keywords:  DNA damage; apoptosis; multidrug resistance; nanoparticles; thiourea polymers

DOI:  https://doi.org/10.3389/fonc.2021.667689
Photochem Photobiol. 2021 Jun 14.

Photodynamic Therapy of Inorganic Complexes for the Treatment of Cancer.

Chloe B Smith, Lindsay C Days, Duaa R Alajroush, Khadija Faye, Yara Khodour, Stephen J Beebe, Alvin A Holder.

  Photodynamic therapy (PDT) is a medicinal tool that uses a photosensitiser and a light source to treat several conditions, including cancer. PDT uses reactive oxygen species (ROS) such as cytotoxic singlet oxygen (1 O2 ) to induce cell death in cancer cells. Chemotherapy has historically utilized the cytotoxic effects of many metals, especially transition-metal complexes. However, chemotherapy is a systemic treatment so all cells in a patient's body are exposed to the same cytotoxic effects. Transition metal complexes have also shown high cytotoxicity as PDT agents. PDT is a potential localized method for treating several cancer types by using inorganic complexes as photosensitizing agents. This review covers several in vitro and in vivo studies, as well as clinical trials that reported on the anti-cancer properties of inorganic pharmaceuticals used in PDT against different types of cancer.

Keywords:  cancer; photodynamic therapy; photosensitiser; singlet oxygen; transition metal complexes

DOI:  https://doi.org/10.1111/php.13467
Front Oncol. 2021 ;11 662840

Radiation Resistance: A Matter of Transcription Factors.

Chiara Galeaz, Cristina Totis, Alessandra Bisio.

  Currently, radiation therapy is one of the standard therapies for cancer treatment. Since the first applications, the field of radiotherapy has constantly improved, both in imaging technologies and from a dose-painting point of view. Despite this, the mechanisms of resistance are still a great problem to overcome. Therefore, a more detailed understanding of these molecular mechanisms will allow researchers to develop new therapeutic strategies to eradicate cancer effectively. This review focuses on different transcription factors activated in response to radiotherapy and, unfortunately, involved in cancer cells' survival. In particular, ionizing radiations trigger the activation of the immune modulators STAT3 and NF-κB, which contribute to the development of radiation resistance through the up-regulation of anti-apoptotic genes, the promotion of proliferation, the alteration of the cell cycle, and the induction of genes responsible for the Epithelial to Mesenchymal Transition (EMT). Moreover, the ROS-dependent damaging effects of radiation therapy are hampered by the induction of antioxidant enzymes by NF-κB, NRF2, and HIF-1. This protective process results in a reduced effectiveness of the treatment, whose mechanism of action relies mainly on the generation of free oxygen radicals. Furthermore, the previously mentioned transcription factors are also involved in the maintenance of stemness in Cancer Stem Cells (CSCs), a subset of tumor cells that are intrinsically resistant to anti-cancer therapies. Therefore, combining standard treatments with new therapeutic strategies targeted against these transcription factors may be a promising opportunity to avoid resistance and thus tumor relapse.

Keywords:  ROS - reactive oxygen species; cancer stem cells; inflammation; radiation resistance; radiotherapy; transcription factors

DOI:  https://doi.org/10.3389/fonc.2021.662840
Macromol Biosci. 2021 Jun 18. e2100091

Dual-Targeting Polymeric Nanocarriers to Deliver ROS-Responsive Prodrugs and Combat Multidrug Resistance of Cancer Cells.

Longchang Xi, Jingbo Wang, Yuheng Wang, Zhishen Ge.

  Targeting delivery of anticancer drugs that can interact with DNA into mitochondria of cancer cells has been demonstrated to be an effective method to combat drug resistance. In this report, a cancer cell and mitochondria dual-targeting drug delivery system (DT-NP) is presented based on nanoparticles self-assembled from amphiphilic block copolymers with pH-responsive release of cinnamaldehyde (CA), which is used to encapsulate reactive oxygen species (ROS)-activable prodrug, phenylboronic pinacol ester-caged doxorubicin (BDOX). The surfaces of nanoparticles are conjugated by cancer cell-targeting folic acid (FA) and mitochondria-targeting triphenyl phosphonium (TPP) for dual targeting delivery. After incubation of DT-NP with multidrug-resistant breast cancer cells MCF-7/ADR, CA release under acidic conditions in endosomes from DT-NP can effectively induce intracellular oxidative stress improvement, especially in mitochondria. After targeting drug delivery into mitochondria, high level of ROS in mitochondria can in situ activate BDOX to interact with mitochondrial DNA and induce cell apoptosis. DT-NP displays a remarkably higher cancer cell killing effect on MCF-7/ADR as compared with DOX. Accordingly, DT-NP shows great potentials toward multidrug-resistant cancers as dual-targeting drug delivery systems with intracellular oxidative stress improvement and ROS-responsive prodrug activation in mitochondria.

Keywords:  drug delivery; mitochondria targeting; multi-drug resistance; prodrug activation; stimuli-responsive

DOI:  https://doi.org/10.1002/mabi.202100091