A novel copper(I) complex induces ER-stress-mediated apoptosis and sensitizes B-acute lymphoblastic leukemia cells to chemotherapeutic agents

A novel heteroleptic Cu(II)-phenanthroline-UDCA complex as lipoxygenase inhibitor and ER-stress inducer in cancer cell lines

A new heteroleptic copper(II) compound named C0-UDCA was prepared by reaction of [Cu(phen)₂(OH₂)](ClO₄)₂ (C0) with the bile ursodeoxycholic acid (UDCA). The resulting compound is able to inhibit the lipoxygenase enzyme showing more efficacy than the precursors C0 and UDCA. Molecular docking simulations clarified the interactions with the enzyme as due to allosteric modulation. The new complex shows antitumoral effect on ovarian (SKOV-3) and pancreatic (PANC-1) cancer cells at the Endoplasmic Reticulum (ER) level by activating the Unfolded Protein Response. In particular, the chaperone BiP, the pro-apoptotic protein CHOP and the transcription factor ATF6 are upregulated in the presence of C0-UDCA. The combination of Intact Cell MALDI-MS and statistical analysis have allowed us to discriminate between untreated and treated cells based on their mass spectrometry fingerprints.

Cyclometalated Ru(II)-NHC complexes with phenanthroline ligands induce apoptosis mediated by mitochondria and endoplasmic reticulum stress in cancer cells

The exploration of ruthenium complexes as anticancer drugs has been the focus of intense investigation. In this study, we synthesized and characterized four C,N-cyclometalated ruthenium(II) complexes (Ru1-Ru4) coordinated with pyridine-functionalized N-heterocyclic carbene (NHC) and auxiliary ligands (e.g., acetonitrile, 1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline). X-ray diffraction analysis showed that all of the four cycloruthenated complexes are hexa-coordinated in a typical octahedral geometry. In vitro cytotoxic studies revealed that cyclometalated Ru-NHC complexes Ru3 and Ru4 had stronger anticancer activity than their corresponding Ru-NHC precursor Ru1 and the clinically used cisplatin. For HeLa cells, Ru3 and Ru4 exhibited potent cytotoxicity with the IC₅₀ value of 4.31 ± 0.42 μM and 3.14 ± 0.23 μM, respectively, which was approximately three times lower than that of cisplatin. More interestingly, Ru3 and Ru4 not only effectively inhibited the proliferation of HeLa cells, but also exhibited potential anti-migration activity. In the scratch wound healing assay, Ru3 and Ru4 treatment significantly reduced the wound healing rate of HUVEC cells. Mechanistic studies showed that Ru3 and Ru4 caused a dual action mode of mitochondrial membrane depolarization and endoplasmic reticulum stress and finally induced apoptosis of HeLa cells.

Synthesis, characterization and cytotoxicity of copper (II) complex containing a 2H-benzo[e][1,3]oxazin derivative

A new cis-dihalo copper(II) complex, [Cu^II(HL^bz)(Cl)₂].CH₃CN (1), where HL^bz = (S)-2-(((2-(2-(pyridin-2-yl)-2H-benzo[e][1,3]oxazin-3(4H)-yl)ethyl)amino)methyl)phenol), was isolated by reacting copper(II) chloride dihydrate and the H₂L ligand (H₂L = 2,2'-((2-(pyridin-2-yl)imidazolidine-1,3-diyl)bis(methylene))diphenol) in a MeOH/CH₃CN (1:3 v/v) mixture. The complex formation occurred via the ligand modification during complexation, producing a unique structure containing 2H-benzo[e][1,3]oxazin, as observed from the single crystal X-ray structure determination. The complex was characterized by elemental analysis, potentiometric titration, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. Complex 1 inhibits the growth of myelogenous leukemia cells with an IC₅₀ of 17.3 μmol L^-1.

Spliced X-Box binding protein 1 predicts satisfying responsiveness and survival benefit toward bortezomib-based therapy in multiple myeloma patients

OBJECTIVE

Spliced X-Box binding protein 1 (sXBP1) modulates malignant cell activities and enhances the bortezomib sensitivity in multiple myeloma (MM) cells, while its clinical value in MM patients remains elusive. Hence, the current study aimed to explore this issue, particularly the correlation of sXBP1 with treatment outcomes of bortezomib-based therapy in MM patients.

METHODS

Totally, 97 newly-diagnosed MM patients undergoing bortezomib-based therapy, 20 disease controls (DCs), and 20 health controls (HCs) were enrolled. Bone marrow plasma cell samples were acquired to determine sXBP1 by RT-qPCR.

RESULTS

sXBP1 was lowest in MM patients, followed by DCs, and highest in HCs (P < 0.001). Beyond that, sXBP1 discriminated MM patients from DCs with area under curve (AUC) of 0.728 (95% confidence interval (CI): 0.610-0.847) and HCs with AUC of 0.855 (95% CI: 0.771-0.939). sXBP1 was negatively associated with t (4; 14) (P = 0.047), Revised International Staging System stage (P = 0.008). There was a trend that sXBP1 was negatively correlated with β₂-MG, LDH, and t (14; 16) (without statistical significance). sXBP1 was higher in patients with complete response (CR) compared to those with non-CR (P = 0.017) and higher in patients with objective response rate (ORR) compared to those with non-ORR (P = 0.006). sXBP1 (high vs. low) was linked with longer progression-free survival (PFS) (P = 0.011) and overall survival (P = 0.045) in MM patients. Additionally, sXBP1 (high vs. low) (P = 0.025) independently estimated a longer PFS.

CONCLUSION

sXBP1 forecasts a favorable treatment response and survival benefit toward bortezomib-based therapy in multiple myeloma patients.

Development of Two Diagnostic Prediction Models for Leptomeningeal Metastasis in Patients With Solid Tumors

Objectives

For accurate diagnosis of leptomeningeal metastasis (LM) and to avoid unnecessary examinations or lumber puncture (LP), we develop two diagnostic prediction models for patients with solid tumors.

Study Design, Setting, and Participants

This is a retrospective cohort study launched at the Second Affiliated Hospital of Dalian Medical University. In total, 206 patients who had been admitted between January 2005 and December 2021 with a solid tumor and clinical suspicion of LM were enrolled to develop model A. In total, 152 patients of them who underwent LPs for cytology and biochemistry were enrolled to develop model B.

Model Development

Diagnostic factors included skull metastasis, active brain metastasis, progressed extracranial disease, number of extracranial organs involved, number of symptoms, cerebrospinal fluid (CSF) protein, and CSF glucose. The outcome predictor was defined as the clinical diagnosis of LM. Logistic least absolute shrinkage and selection operator (LASSO) regression was used to identify relevant variables and fit the prediction model. A calibration curve and the concordance index (c-index) were used to evaluate calibration and discrimination ability. The n-fold cross-validation method was used to internally validate the models. The decision curve analysis (DCA) and the interventions avoided analysis (IAA) were used to evaluate the clinical application.

Results

The area under the curve (AUC) values of models A and B were 0.812 (95% CI: 0.751–0.874) and 0.901 (95% CI: 0.852–0.949). Respectively, compared to the first magnetic resonance imaging (MRI) and first LP, models A and B showed a higher AUC (model A vs. first MRI: 0.812 vs. 0.743, p = 0.087; model B vs. first LP: 0.901 vs. 0.800, p = 0.010). The validated c-indexes were 0.810 (95% CI: 0.670–0.952) and 0.899 (95% CI: 0.823–0.977). The calibration curves show a good calibrated ability. The evaluation of clinical application revealed a net clinical benefit and a reduction of unnecessary interventions using the models.

Conclusions

The models can help improve diagnostic accuracy when used alone or in combination with conventional work-up. They also exhibit a net clinical benefit in medical decisions and in avoiding unnecessary interventions for patients with LM. Studies focused on external validation of our models are necessary in the future.

ER Stress and Unfolded Protein Response in Leukemia: Friend, Foe, or Both?

The unfolded protein response (UPR) is an evolutionarily conserved adaptive signaling pathway triggered by a stress of the endoplasmic reticulum (ER) lumen compartment, which is initiated by the accumulation of unfolded proteins. This response, mediated by three sensors-Inositol Requiring Enzyme 1 (IRE1), Activating Transcription Factor 6 (ATF6), and Protein Kinase RNA-Like Endoplasmic Reticulum Kinase (PERK)—allows restoring protein homeostasis and maintaining cell survival. UPR represents a major cytoprotective signaling network for cancer cells, which frequently experience disturbed proteostasis owing to their rapid proliferation in an usually unfavorable microenvironment. Increased basal UPR also participates in the resistance of tumor cells against chemotherapy. UPR activation also occurs during hematopoiesis, and growing evidence supports the critical cytoprotective role played by ER stress in the emergence and proliferation of leukemic cells. In case of severe or prolonged stress, pro-survival UPR may however evolve into a cell death program called terminal UPR. Interestingly, a large number of studies have revealed that the induction of proapoptotic UPR can also strongly contribute to the sensitization of leukemic cells to chemotherapy. Here, we review the current knowledge on the consequences of the deregulation of UPR signaling in leukemias and their implications for the treatment of these diseases.

Recent Advances of Gold Compounds in Anticancer Immunity

In recent years, gold compounds have gained more and more attentions in the design of new metal anticancer drugs. Numerous researches have reported that gold compounds, in addition to their widely studied cytotoxic antitumor effects, also reverse tumor immune escape and directly facilitate the functions of immune cells, leading to enhanced anticancer effects. This review mainly summarizes our current understandings of antitumor effects of gold drugs and their relationships with various aspects of antitumor immunity, including innate immunity, adaptive immunity, immunogenic cell death, and immune checkpoints, as well as their roles in adverse effects. Some recent examples of anticancer gold compounds are highlighted. The property of gold compounds is expected to combine with anticancer immunotherapy, such as immune checkpoint inhibitors, to develop new anticancer therapeutic strategies.

The Unfolded Protein Response: A Novel Therapeutic Target in Acute Leukemias

The unfolded protein response (UPR) is an evolutionarily conserved adaptive response triggered by the stress of the endoplasmic reticulum (ER) due, among other causes, to altered cell protein homeostasis (proteostasis). UPR is mediated by three main sensors, protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6α (ATF6α), and inositol-requiring enzyme-1α (IRE1α). Given that proteostasis is frequently disregulated in cancer, UPR is emerging as a critical signaling network in controlling the survival, selection, and adaptation of a variety of neoplasias, including breast cancer, prostate cancer, colorectal cancer, and glioblastoma. Indeed, cancer cells can escape from the apoptotic pathways elicited by ER stress by switching UPR into a prosurvival mechanism instead of cell death. Although most of the studies on UPR focused on solid tumors, this intricate network plays a critical role in hematological malignancies, and especially in multiple myeloma (MM), where treatment with proteasome inhibitors induce the accumulation of unfolded proteins that severely perturb proteostasis, thereby leading to ER stress, and, eventually, to apoptosis. However, UPR is emerging as a key player also in acute leukemias, where recent evidence points to the likelihood that targeting UPR-driven prosurvival pathways could represent a novel therapeutic strategy. In this review, we focus on the oncogene-specific regulation of individual UPR signaling arms, and we provide an updated outline of the genetic, biochemical, and preclinical therapeutic findings that support UPR as a relevant, novel target in acute leukemias.

Endoplasmic reticulum stress: an arising target for metal-based anticancer agents

Metal anticancer agents are rapidly emerging as selective, potent therapeutics that exhibit anticancer activity by inducing endoplasmic reticulum stress.

Mixed copper(ii)–phenanthroline complexes induce cell death of ovarian cancer cells by evoking the unfolded protein response

There is an ongoing need for development of new therapeutics that override acquired resistance to cancer therapy. Targeting endoplasmic reticulum by Cu(ii)–phenanthroline complexes may represent such alternative strategy to current cytotoxic drugs.

Downregulation of glucose-regulated protein 78 enhances the cytotoxic effects of curcumin on human nasopharyngeal carcinoma cells

Curcumin is a conventional Chinese medicine, which exerts a marked effect on various tumor types and suppresses tumor invasion. The present study analyzed the antineoplastic effects of curcumin on human nasopharyngeal carcinoma (NPC) cells and determined the effects of endoplasmic reticulum (ER) stress on curcumin‑induced cytotoxicity. The Cell Counting Kit‑8 assay examined the viability of SUNE1 and SUNE2 NPC cells. The Annexin V/propidium iodide staining technique was used to detect cell apoptosis and flow cytometry was used to examine cell cycle distribution. Western blotting and immunofluorescence were used to detect ER stress‑associated molecules. Furthermore, the toxic effects of curcumin treatment alongside glucose‑regulated protein 78 (GRP78) knockdown using small interfering (si)RNA, and treatment with the pan‑caspase inhibitor Z‑VAD‑FMK and the protein kinase B (AKT) inhibitor MK‑2206 were detected. The results demonstrated that curcumin markedly reduced cell viability, blocked cell cycle progression and induced apoptosis of human NPC cells. In addition, curcumin activated ER stress‑associated proteins to participate in the apoptosis of human NPC cells. siRNA‑induced knockdown of GRP78 may be able to strengthen the toxic effects of curcumin through mediating the AKT signaling pathway. These findings indicated that downregulation of GRP78 promoted the therapeutic effects of curcumin on NPC cells. The present study identified a potential, novel therapeutic method for the treatment of NPC.

Novel copper complexes as potential proteasome inhibitors for cancer treatment (Review)

The use of metal complexes in the pharmaceutical industry has recently increased and as a result, novel metal‑based complexes have initiated an interest as potential anticancer agents. Copper (Cu), which is an essential trace element in all living organisms, is important in maintaining the function of numerous proteins and enzymes. It has recently been demonstrated that Cu complexes may be used as tumor‑specific proteasome inhibitors and apoptosis inducers, by targeting the ubiquitin‑proteasome pathway (UPP). Cu complexes have demonstrated promising results in preclinical studies. The UPP is important in controlling the expression, activity and location of various proteins. Therefore, selective proteasome inhibition and apoptotic induction in cancer cells have been regarded as potential anticancer strategies. The present short review discusses recent progress in the development of Cu complexes, including clioquinol, dithiocarbamates and Schiff bases, as proteasome inhibitors for cancer treatment. A discussion of recent research regarding the understanding of metal inhibitors based on Cu and ligand platforms is presented.

Anticancer metal drugs and immunogenic cell death

Conventional chemotherapeutics, but also innovative precision anticancer compounds, are commonly perceived to target primarily the cancer cell compartment. However, recently it was discovered that some of these compounds can also exert immunomodulatory activities which might be exploited to synergistically enhance their anticancer effects. One specific phenomenon of the interplay between chemotherapy and the anticancer immune response is the so-called "immunogenic cell death" (ICD). ICD was discovered based on a vaccination effect exerted by cancer cells dying from pretreatment with certain chemotherapeutics, termed ICD inducers, in syngeneic transplantation mouse models. Interestingly, only a minority of drugs is able to trigger ICD without a clear-cut relation to chemical structures or their primary modes-of-action. Nevertheless, generation of reactive oxygen species (ROS) and induction of endoplasmic reticulum (ER) stress are clearly linked to ICD. With regard to metal drugs, oxaliplatin but not cisplatin is considered a bona fide ICD inducer. Taken into account that several experimental metal compounds are efficient ROS and ER stress mediators, presence of potent ICD inducers within the plethora of novel metal complexes seems feasible and has occasionally been reported. In the light of recent successes in cancer immunotherapy, here we review existing literature regarding anticancer metal drugs and ICD induction. We recommend a more profound investigation of the immunogenic features of experimental anticancer metal drugs.

Copper(i) complexes with phosphine derived from sparfloxacin. Part I - structures, spectroscopic properties and cytotoxicity

In this paper we present new copper(i) iodide or copper(i) thiocyanate complexes with hydroxymethyldiphenylphosphine (PPh2(CH2OH)) or phosphine derivatives of sparfloxacin, a 3(rd) generation fluoroquinolone antibiotic agent (PPh2(CH2-Sf)) and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,2'-biquinoline (bq) auxiliary ligands. The synthesised complexes were fully characterised by NMR and UV-Vis spectroscopy as well as by mass spectrometry. Selected structures were additionally analysed using X-ray and DFT methods. All complexes proved to be stable in solution in the presence of water and atmospheric oxygen for several days. The cytotoxic activity of the complexes was tested against two cancer cell lines (CT26 - mouse colon carcinoma and A549 - human lung adenocarcinoma). Applying two different incubation times, the studies enabled a preliminary estimation of the dependence of the selectivity and the mechanism of action on the type of diimine and phosphine ligands. The results obtained showed that complexes with PPh2(CH2-Sf) are significantly more active than those with PPh2(CH2OH). On the other hand, the relative impact of diimine on cytotoxicity is less pronounced. However, the dmp complexes are characterised by strong inhibitory properties, while the bq ones are rather not. This confirms the interesting and promising biological properties of the investigated group of copper(i) complexes, which undoubtedly are worthy of further biological studies.

Blocking autophagy enhances meloxicam lethality to hepatocellular carcinoma by promotion of endoplasmic reticulum stress

OBJECTIVES

Meloxicam, a selective cyclooxygenase-2 (COX-2) inhibitor, has been demonstrated to exert anti-tumour effects against various malignancies. However, up to now, mechanisms involved in meloxicam anti-hepatocellular carcinoma effects have remained unclear.

MATERIALS AND METHODS

Cell viability and apoptosis were assessed by CCK-8 and flow cytometry. Endoplasmic reticulum (ER) stress and autophagy-associated molecules were analysed by western blotting and immunofluorescence assay. GRP78 and Atg5 knock-down by siRNA or chemical inhibition was used to investigate cytotoxic effects of meloxicam treatment on HCC cells.

RESULTS

We found that meloxicam led to apoptosis and autophagy in HepG2 and Bel-7402 cells via a mechanism that involved ER stress. Up-regulation of GRP78 signalling pathway from meloxicam-induced ER stress was critical for activation of autophagy. Furthermore, autophagy activation attenuated ER stress-related cell death. Blocking autophagy by 3-methyladenine (3-MA) or Atg5 siRNA knock-down enhanced meloxicam lethality for HCC by activation of ER stress-related apoptosis. In addition, GRP78 seemed to lead to autophagic activation via the AMPK-mTOR signalling pathway. Blocking AMPK with a chemical inhibitor inhibited autophagy suggesting that meloxicam-regulated autophagy requires activation of AMPK.

CONCLUSIONS

Our results revealed that both ER stress and autophagy were involved in cell death evoked by meloxicam in HCC cells. This inhibition of autophagy to enhance meloxicam lethality, suggests a novel therapeutic strategy against HCC.

Novel 3-Substituted 7-Phenylpyrrolo[3,2-f]quinolin-9(6H)-ones as Single Entities with Multitarget Antiproliferative Activity

A series of chemically modified 7-phenylpyrrolo[3,2-f]quinolinones was synthesized and evaluated as anticancer agents. Among them, the most cytotoxic (subnanomolar GI50 values) amidic derivative 5f was shown to act as an inhibitor of tubulin polymerization (IC50, 0.99 μM) by binding to the colchicine site with high affinity. Moreover, 5f induced cell cycle arrest in the G2/M phase of the cell cycle in a concentration dependent manner, followed by caspase-dependent apoptotic cell death. Compound 5f also showed lower toxicity in nontumoral cells, suggesting selectivity toward cancer cells. Additional experiments revealed that 5f inhibited the enzymatic activity of multiple kinases, including AURKA, FLT3, GSK3A, MAP3K, MEK, RSK2, RSK4, PLK4, ULK1, and JAK1. Computational studies showed that 5f can be properly accommodated in the colchicine binding site of tubulin as well as in the ATP binding clefts of all examined kinases. Our data indicate that the excellent antiproliferative profile of 5f may be derived from its interactions with multiple cellular targets.

FOXM1 is overexpressed in B-acute lymphoblastic leukemia (B-ALL) and its inhibition sensitizes B-ALL cells to chemotherapeutic drugs

The Forkhead box protein M1 (FOXM1) is a transcription factor that plays a central role in the regulation of cell cycle, proliferation, DNA repair, and apoptosis. FOXM1 is overexpressed in many human tumors and its upregulation has been linked to high proliferation rates and poor prognosis. We therefore studied the role of FOXM1 in B-lymphoblastic leukemia (B-ALL) in order to understand whether FOXM1 could be a key target for leukemia therapy. RT-PCR and western blot analysis were carried out in a small cohort of pediatric B-ALL patients to evaluate FOXM1 levels. To assess its biological relevance, its expression was down-modulated by transient RNA interference in B-ALL cell lines (REH and NALM-6). Our results show that FOXM1 expression is higher in both B-ALL patients and cell lines when compared to PBMC or normal B-cells (CD19+) from healthy donors. Furthermore, blocking FOXM1 activity in two B-ALL cell lines, by either knockdown or treatment with the FOXM1 inhibitor thiostrepton, causes significant decrease in their cell proliferation. This decrease in cell proliferation was coupled with both an induction of the G2/M cell cycle arrest and with a reduction in the S phase population. Finally, we noted how thiostrepton synergises with chemotherapeutic agents commonly used in B-ALL therapy, thus increasing their efficiency. Therefore our results suggest that FOXM1 is highly expressed in both patients and B-ALL cell lines, and that targeting FOXM1 could be an attractive strategy for leukemia therapy and for overcoming drug resistance.

Saururus chinensis Baill induces apoptosis through endoplasmic reticulum stress in HepG2 hepatocellular carcinoma cells

In this study, we examined the mechanism underlying the effect of Saururus chinensis Baill (saururaceae) on hepatocellular carcinoma HepG2 cells. HepG2 cells and Chang cells were exposed to various concentrations of S. chinensis Baill extract (SC-E) for 24 h. SC-E affected more significantly HepG2 cells than Chang cells in terms of cell viability and ATP production. Therefore, current study examined detailed mechanism how SC-E affected HepG2 cell survival. We found that SC-E (75 and 150 μg/ml) induced apoptosis via oxidative stress. SC-E also caused CCAAT-enhancer-binding protein homologous protein (CHOP) activation by dissociating the binding immunoglobulin protein (BiP) from inositol-requiring 1α (IRE1α) in the endoplasmic reticulum (ER) and induced Bax, cytochrome c release to cytosol, caspase-3 activation, and poly ADP ribose polymerase (PARP) cleavage, resulting in HepG2 cell apoptosis. Furthermore, SC-E caused ER Ca(2+) leakage into the cytosol; ER dilation and mitochondrial membrane damage were observed in transmission electron microscopy (TEM). Taken together, our results demonstrated that SC-E induced cancer cell apoptosis specifically through ER stress.

Inhibition of 19S proteasome-associated deubiquitinases by metal-containing compounds

Copper and gold complexes have clinical activity in several diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is associated with targeting the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. Here we discuss metal DUB inhibitors in treating cancer and other diseases. (from Editor). Several copper and gold complexes have clinical activity in treating some human diseases including cancer. Recently, we have reported that the anti-cancer activity of copper (II) pyrithione CuPT and gold (I) complex auranofin is tightly associated with their ability to target and inhibit the 19S proteasome-associated deubiquitinases (DUBs), UCHL5 and USP14. In this article we review small molecule inhibitors of DUBs and 19S proteasome-associated DUBs. We then describe and discuss the ubique nature of CuPT and auranofin, which is inhibition of 19S proteasome-associated UCHL5 and USP14. We finally suggest the potential to develop novel, specific metal-based DUB inhibitors for treating cancer and other diseases.