Calcium ionophore, ionomycin inhibits growth of human bladder cancer cells both in vitro and in vivo with alteration of Bcl-2 and Bax expression levels

Lung Adenocarcinoma Systems Biomarker and Drug Candidates Identified by Machine Learning, Gene Expression Data, and Integrative Bioinformatics Pipeline

Lung adenocarcinoma (LUAD) is a significant planetary health challenge with its high morbidity and mortality rate, not to mention the marked interindividual variability in treatment outcomes and side effects. There is an urgent need for robust systems biomarkers that can help with early cancer diagnosis, prediction of treatment outcomes, and design of precision/personalized medicines for LUAD. The present study aimed at systems biomarkers of LUAD and deployed integrative bioinformatics and machine learning tools to harness gene expression data. Predictive models were developed to stratify patients based on prognostic outcomes. Importantly, we report here several potential key genes, for example, PMEL and BRIP1, and pathways implicated in the progression and prognosis of LUAD that could potentially be targeted for precision/personalized medicine in the future. Our drug repurposing analysis and molecular docking simulations suggested eight drug candidates for LUAD such as heat shock protein 90 inhibitors, cardiac glycosides, an antipsychotic agent (trifluoperazine), and a calcium ionophore (ionomycin). In summary, this study identifies several promising leads on systems biomarkers and drug candidates for LUAD. The findings also attest to the importance of integrative bioinformatics, structural biology and machine learning techniques in biomarker discovery, and precision oncology research and development.

A Self-Reinforcing Nanoplatform for Highly Effective Synergistic Targeted Combinatary Calcium-Overload and Photodynamic Therapy of Cancer

While calcium-overload-mediated therapy (COMT) is a promising but largely untapped therapeutic strategy, combinatory therapy greatly boosts treatment outcomes with integrated merits of different therapies. Herein, a BPQD@CaO₂ -PEG-GPC3Ab nanoplatform is formulated by integrating calcium peroxide (CaO₂ ) and black phosphorus quantum dot (BPQD, photosensitizer) with active-targeting glypican-3 antibody (GPC3Ab), for combinatory photodynamic therapy (PDT) and COMT in response to acidic pH and near-infrared (NIR) light, wherein CaO₂ serves as the reservoir of calcium ions (Ca²⁺ ) and hydrogen peroxide (H₂ O₂ ). Navigated by GPC3Ab to tumor cells at acidic pH, the nanoparticle disassembles to CaO₂ and BPQD; CaO₂ produces COMT Ca²⁺ and H₂ O₂ , while H₂ O₂ makes oxygen (O₂ ) to promote PDT; under NIR irradiation BPQD facilitates not only the conversion of O₂ to singlet oxygen (¹ O₂ ) for PDT, but also moderate hyperthermia to accelerate NP dissociation to CaO₂ and BPQD, and conversions of CaO₂ to Ca²⁺ and H₂ O₂ , and H₂ O₂ to O₂ , to enhance both COMT and PDT. After supplementary ionomycin treatment to induce intracellular Ca²⁺ bursts, the multimodal therapeutics strikingly induce hepatocellular carcinoma apoptosis, likely through the activation of the calpains and caspases 12, 9, and 3, up-regulation of Bax and down-regulation of Bcl-2 proteins. This nanoplatform enables a mutually-amplifying and self-reinforcing synergistic therapy.

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

Ionophores: Potential Use as Anticancer Drugs and Chemosensitizers

Ion homeostasis is extremely important for the survival of both normal as well as neoplastic cells. The altered ion homeostasis found in cancer cells prompted the investigation of several ionophores as potential anticancer agents. Few ionophores, such as Salinomycin, Nigericin and Obatoclax, have demonstrated potent anticancer activities against cancer stem-like cells that are considered highly resistant to chemotherapy and responsible for tumor relapse. The preclinical success of these compounds in in vitro and in vivo models have not been translated into clinical trials. At present, phase I/II clinical trials demonstrated limited benefit of Obatoclax alone or in combination with other anticancer drugs. However, future development in targeted drug delivery may be useful to improve the efficacy of these compounds. Alternatively, these compounds may be used as leading molecules for the development of less toxic derivatives.

Activation of K(+) channel by 1-EBIO rescues the head and neck squamous cell carcinoma cells from Ca(2+) ionophore-induced cell death

Ion channels in carcinoma and their roles in cell proliferation are drawing attention. Intracellular Ca²⁺ ([Ca²⁺]_i)-dependent signaling affects the fate of cancer cells. Here we investigate the role of Ca²⁺-activated K⁺ channel (SK4) in head and neck squamous cell carcinoma cells (HNSCCs) of different cell lines; SNU-1076, OSC-19 and HN5. Treatment with 1 µM ionomycin induced cell death in all the three cell lines. Whole-cell patch clamp study suggested common expressions of Ca²⁺-activated Cl^- channels (Ano-1) and Ca²⁺-activated nonselective cation channels (CAN). 1-EBIO, an activator of SK4, induced outward K⁺ current (ISK4) in SNU-1076 and OSC-19. In HN5, ISK4 was not observed or negligible. The 1-EBIO-induced current was abolished by TRAM-34, a selective SK4 blocker. Interestingly, the ionomycin-induced cell death was effectively prevented by 1-EBIO in SNU-1076 and OSC-19, and the rescue effect was annihilated by combined TRAM-34. Consistent with the lower level of ISK4, the rescue by 1-EBIO was least effective in HN5. The results newly demonstrate the role of SK4 in the fate of HNSCCs under the Ca²⁺ overloaded condition. Pharmacological modulation of SK4 might provide an intriguing novel tool for the anti-cancer strategy in HNSCC.

Purinergic signalling and cancer

Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.

LEARNING LOCAL DIRECTED ACYCLIC GRAPHS BASED ON MULTIVARIATE TIME SERIES DATA

Multivariate time series (MTS) data such as time course gene expression data in genomics are often collected to study the dynamic nature of the systems. These data provide important information about the causal dependency among a set of random variables. In this paper, we introduce a computationally efficient algorithm to learn directed acyclic graphs (DAGs) based on MTS data, focusing on learning the local structure of a given target variable. Our algorithm is based on learning all parents (P), all children (C) and some descendants (D) (PCD) iteratively, utilizing the time order of the variables to orient the edges. This time series PCD-PCD algorithm (tsPCD-PCD) extends the previous PCD-PCD algorithm to dependent observations and utilizes composite likelihood ratio tests (CLRTs) for testing the conditional independence. We present the asymptotic distribution of the CLRT statistic and show that the tsPCD-PCD is guaranteed to recover the true DAG structure when the faithfulness condition holds and the tests correctly reject the null hypotheses. Simulation studies show that the CLRTs are valid and perform well even when the sample sizes are small. In addition, the tsPCD-PCD algorithm outperforms the PCD-PCD algorithm in recovering the local graph structures. We illustrate the algorithm by analyzing a time course gene expression data related to mouse T-cell activation.

Purinergic signalling in the lower urinary tract

The aim of this review is to describe the conceptual steps contributing to our current knowledge of purinergic signalling and to consider its involvement in the physiology and pathophysiology of the lower urinary tract. The voiding reflex involves ATP released as a cotransmitter with acetylcholine from parasympathetic nerves supplying the bladder and ATP released from urothelial cells during bladder distension to initiate the voiding reflex via P2X3 receptors on suburothelial low threshold sensory nerve fibres. This mechanosensory transduction pathway also participates, via high threshold sensory nerve fibres, in the initiation of pain in bladder and ureter. Treatment of prostate and bladder cancer with ATP is effective against the primary tumours in animal models and human cell lines, via P2X5 and P2X7 receptors, and also improves the systemic symptoms associated with advanced malignancy. Acupuncture is widely used for the treatment of urinary disorders, and a purinergic hypothesis is discussed for the underlying mechanism.

Polyether ionophores: broad-spectrum and promising biologically active molecules for the control of drug-resistant bacteria and parasites

BACKGROUND

As multidrug-resistant (MDR) pathogens continue to emerge, there is a substantial amount of pressure to identify new drug candidates. Carboxyl polyethers, also referred to as polyether antibiotics, are a unique class of compounds with outstanding potency against a variety of critical infectious disease targets including protozoa, bacteria and viruses. The characteristics of these molecules that are of key interest are their selectivity and high potency against several MDR etiological agents.

OBJECTIVE

Although many studies have been published about carboxyl polyether antibiotics, there are no recent reviews of this class of drugs. The purpose of this review is to provide the reader with an overview of the spectrum of activity of polyether antibiotics, their mechanism of action, toxicity and potential as drug candidates to combat drug-resistant infectious diseases.

CONCLUSION

Polyether ionophores show a high degree of promise for the potential control of drug-resistant bacterial and parasitic infections. Despite the long history of use of this class of drugs, very limited medicinal chemistry and drug optimization studies have been reported, thus leaving the door open to these opportunities in the future. Scifinder and PubMed were the main search engines used to locate articles relevant to the topic presented in the present review. Keywords used in our search were specific names of each of the 88 compounds presented in the review as well as more general terms such as polyethers, ionophores, carboxylic polyethers and polyether antibiotics.

Purinergic receptor-mediated effects of adenosine 5'-triphosphate in urological malignant diseases

Adenosine 5'-triphosphate (ATP) mediates a variety of biological functions and has been shown to play a physiological role in almost every system in the body. In the genito-urinary system, extracellular ATP has been shown to play a functional role in several different capacities, ranging from nociception in the ureter and bladder, to erectile dysfunction via its action on different 'purinergic receptors'. Discovery of the trophic effects of ATP has led to a surge in interest in this signalling system in various malignancies. To date five P2 receptor subtypes have been implicated in the growth inhibition of cancer cells, namely P2X5, P2X7, P2Y1, P2Y2 and P2Y11. Limited data are available on urological malignancies. ATP induces its anti-neoplastic effect primarily via purinergic receptor-mediated apoptosis via calcium-independent pathways, and this has been confirmed in vitro and in vivo. Studies have highlighted functional roles for the P2X5 and/or P2Y11 receptors in both hormone refractory prostate cancer and high-grade bladder cancer, although the contributory effect of pro-apoptotic P2X7 receptors remains unclear. Clinical trials have shown intravenous ATP successfully attenuates a range of systemic symptoms associated with advanced malignancies. This raises the possibility that selective targeting of specific aberrant pathways may allow for treatment of advanced primary malignancies and their systemic effects.

Influences of lovastatin on membrane ion flow and intracellular signaling in breast cancer cells

Lovastatin, an inhibitor of cellular cholesterol synthesis, has an apparent anti-cancer property, but the detailed mechanisms of its anti-cancer effects remain poorly understood. We investigated the molecular mechanism of Lovastatin anti-tumor function through the study of its effect on membrane ion flow, gap junctional intercellular communication (GJIC), and the pathways of related signals in MCF-7 mammary cancer cells. After treatment for 24–72 h with 4, 8 or 16 μmol/L Lovastatin, cellular proliferation was examined via the MTT assay, and changes in membrane potential and cellular [Ca²⁺]_i were monitored using confocal laser microscopy. In addition, the expression of plasma membrane calcium ATPase isoform 1 (PMCA1) mRNA was analyzed via RT-PCR, the GJIC function was examined using the scrape-loading dye transfer (SLDT) technique, and MAPK phosphorylation levels were tested with the kinase activity assay. The results showed that Lovastatin treatment significantly inhibited the growth of MCF-7 breast cancer cells. It also increased the negative value of the membrane potential, leading to the hyperpolarization of cells. Moreover, Lovastatin treatment continuously enhanced [Ca²⁺]_i, although the levels of PMCA1 mRNA were unchanged. GJIC was also upregulated in MCF-7 cells, with transfer of LY Fluorescence reaching 4 to 5 rows of cells from the scraped line after treatment with 16 μmol/L Lovastatin for 72 h. Finally, downregulation of ERK1 and p38^MAPK phosphorylation were found in Lovastatin-treated MCF-7 cells. It could be deduced that Lovastatin can induce changes in cellular hyperpolarization and intracellular Ca²⁺ distributions, and increase GJIC function. These effects may result in changes in the downstream signal cascade, inhibiting the growth of MCF-7 cells.

Changes in Cytosolic Ca2+ Levels Regulate Bcl-xS and Bcl-xL Expression in Spermatogenic Cells during Apoptotic Death

Bcl-x exists in two isoforms, the anti-apoptotic form Bcl-xL and the proapoptotic form Bcl-xS. The critical balance between the two forms appears to be important for cell survival; however, it is still not clear exactly how the vital balance is maintained. Using an in vitro spermatogenic cell apoptosis model, this study provides a new insight into the possible role of Ca2+ in regulating the Bcl-xS and Bcl-xL expression. 2,5-Hexanedione, a metabolite of the common industrial solvent n-hexane, caused a significant increase in reactive oxygen species followed by an enhancement of intracellular Ca2+ through the T-type Ca2+ channels. Consequent to the above changes, expression of Bcl-xS increased with a concomitant drop in Bcl-xL expression, thus altering the ratio of the two proteins. Impediment of Ca2+ influx by using a T-type Ca2+ channel blocker pimozide resulted in a decrease in Bcl-xS and an increase in Bcl-xL expression. This caused prevention of mitochondrial potential loss, reduction of caspase-3 activity, inhibition of DNA fragmentation, and increase in cell survival. Alternatively, Ca2+ ionophores caused an increase of Bcl-xS encoding isoform over the Bcl-xL-encoding isoform. Therefore, this study proposes a role for Ca2+ in regulation of Bcl-xS and Bcl-xL expression and ultimately cell fate.

Ionomycin downregulates beta-catenin/Tcf signaling in colon cancer cell line

Functional activation of beta-catenin/Tcf signaling plays an important role in the early events in colorectal carcinogenesis. We examined the effect of ionomycin against beta-catenin/Tcf signaling in colon cancer cells. Reporter gene assay showed that ionomycin inhibited beta-catenin/Tcf signaling efficiently. In addition, the inhibition of beta-catenin/Tcf signaling by ionomycin in HEK293 cells transiently transfected with a constitutively mutant beta-catenin gene, whose product is not phosphorylated by GSK3beta, indicates that its inhibitory mechanism is related to beta-catenin itself or downstream components. To investigate the precise inhibitory mechanism, we performed immunoprecipitation analysis, western blot and electrophoretic mobility shift assay. As a result, our data reveal that the association of beta-catenin and Tcf-4 is disrupted and the amount of beta-catenin product in the nucleus is decreased by ionomycin in a concentration-dependent manner. Moreover, ionomycin strongly suppressed the binding of the Tcf complexes to its specific DNA-binding sites. The significance of the current work is that ionomycin is a negative regulator of beta-catenin/Tcf signaling in colon cancer cells and its inhibitory mechanism is related to the decreased nuclear beta-catenin products and to the suppressed binding of Tcf complexes to consensus DNA.

Synergistic antitumor effect of ionomycin and cisplatin against renal cell carcinoma in vitro and in vivo

Objectives. To characterize the synergistic antitumor effects of the calcium ionophore, ionomycin, and of cisplatin against human renal cell carcinoma cell line, ACHN, both in vitro and in vivo.Methods. The in vitro growth rate of ACHN after exposure to these compounds was measured, using the MTT assay. The apoptotic features in ACHN were evaluated by DNA ladder analysis and flow cytometric analysis. Bcl-2 and Bax expression levels in ACHN after treatment were examined by Western blot. The synergistic antitumor effects of ionomycin and cisplatin against the growth of established ACHN tumors in athymic nude mice were then tested.Results. The in vitro growth rate of ACHN was suppressed more by ionomycin and cisplatin in combination than by either alone. DNA ladder and fragmentation were more obvious when the cells were incubated with ionomycin and cisplatin together than with either reagent alone. Ionomycin treatment increased the expression level of Bax protein, whereas Bcl-2 expression was not influenced. Although an intraperitoneal injection of cisplatin or an intratumoral injection of ionomycin against subcutaneous ACHN tumors somewhat reduced tumorigenicity in nude mice, the effect was significantly enhanced by a combination of these drugs.Conclusions. The synergistic antitumor effects suggest that ionomycin-based therapy could be a novel therapeutic strategy with which to treat advanced renal cell carcinoma.

Synergistic chemosensitization and inhibition of tumor growth and metastasis by adenovirus-mediated P53 gene transfer in human bladder cancer model

OBJECTIVES

To determine whether an adenovirus-mediated p53 gene (Ad5CMV-p53) transfer enhances cisplatin cytotoxicity in vitro and whether Ad5CMV-p53 and cisplatin synergistically inhibit growth and metastasis in vivo using human bladder cancer KoTCC-1 cells.

METHODS

MTT assays and DNA fragmentation assays were used to examine the effects of treatment with Ad5CMV-p53 and/or cisplatin on growth inhibition and induction of apoptosis, respectively, in KoTCC-1 cells. The efficacies of combined Ad5CMV-p53 and/or cisplatin therapy against growth and metastasis of KoTCC-1 tumors were assessed using subcutaneous and orthotopic tumor cell injection models.

RESULTS

Ad5CMV-p53 substantially enhanced cisplatin chemosensitivity in a dose-dependent manner, reducing the median IC(50) by more than 50%. Characteristic apoptotic DNA laddering was induced by the combination of sublethal doses of Ad5CMV-p53 and cisplatin, but not by either agent alone. Furthermore, combined Ad5CMV-p53 and cisplatin therapy synergistically inhibited growth of subcutaneous KoTCC-1 tumors and the incidence of metastasis after orthotopic injection.

CONCLUSIONS

These findings illustrate that combined treatment with Ad5CMV-p53 and cisplatin could be an attractive strategy for inhibiting progression of bladder cancer through effective induction of apoptosis.