A potentiated cooperation of carbonic anhydrase IX and histone deacetylase inhibitors against cancer

Combination treatment with histone deacetylase and carbonic anhydrase 9 inhibitors shows therapeutic potential in experimental diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) remains a significant therapeutic challenge due to the lack of effective and safe treatment options. This study explores the potential of combining histone deacetylase (HDAC) and carbonic anhydrase 9 (CA9) inhibitors in treating DIPG. Analysis of RNA sequencing data and tumor tissue from patient samples for the expression of the carbonic anhydrase family and hypoxia signaling pathway activity revealed clinical relevance for targeting CA9 in DIPG. A synergy screen was conducted using CA9 inhibitor SLC-0111 and HDAC inhibitors panobinostat, vorinostat, entinostat, and pyroxamide. The combination of SLC-0111 and pyroxamide demonstrated the highest synergy and was selected for further analysis. Combining SLC-0111 and pyroxamide effectively inhibited DIPG cell proliferation, reduced cell migration and invasion potential, and enhanced histone acetylation, leading to decreased cell population in S Phase. Additionally, the combination therapy induced a greater reduction in intracellular pH than either agent alone. Data from this study suggest that the combination of SLC-0111 and pyroxamide holds promise for treating experimental DIPG, and further investigation of this combination therapy in preclinical models is warranted to evaluate its potential as a viable treatment for DIPG.

Drug interactions of carbonic anhydrase inhibitors and activators

INTRODUCTION

Carbonic anhydrases (CAs, EC 4.2.1.1) have been established drug targets for decades, with their inhibitors and activators possessing relevant pharmacological activity and applications in various fields. At least 11 sulfonamides/sulfamates are clinically used as diuretics, antiglaucoma, antiepileptic, or antiobesity agents and one derivative, SLC-0111, is in clinical trials as antitumor/antimetastatic agent. The activators were less investigated with no clinically used agent.

AREAS COVERED

Drug interactions between CA inhibitors/activators and various other agents are reviewed in publications from the period March 2020 - January 2024.

EXPERT OPINION

Drug interactions involving these agents revealed several interesting findings. Acetazolamide plus loop diuretics is highy effective in acute decompensated heart failure, whereas ocular diseases such as X-linked retinoschisis and macular edema were treated by acetazolamide plus bevacizumab or topical NSAIDs. Potent anti-infective effects of acetazolamide and other CAIs, alone or in combination with other agents were demonstrated for the management of Neisseria gonorrhoea, vancomycin resistant enterococci, Acanthamoeba castellanii, Trichinella spiralis, and Cryptococcus neoformans infections. Topiramate, in combination with phentermine is incresingly used for the management of obesity, whereas zonisamide plus levodopa is highly effective for Parkinson's disease. Acetazolamide, methazolamide, ethoxzolamide, and SLC-0111 showed synergistic antitumor/antimetastatic action in combination with many other antitumor drugs.

SLC-0111, an inhibitor of carbonic anhydrase IX, attenuates hepatoblastoma cell viability and migration

Background

In response to hypoxia, tumor cells undergo transcriptional reprogramming including upregulation of carbonic anhydrase (CA) IX, a metalloenzyme that maintains acid-base balance. CAIX overexpression has been shown to correlate with poor prognosis in various cancers, but the role of this CA isoform in hepatoblastoma (HB) has not been examined.

Methods

We surveyed the expression of CAIX in HB specimens and assessed the impact of SLC-0111, a CAIX inhibitor, on cultured HB cells in normoxic and hypoxic conditions.

Results

CAIX immunoreactivity was detected in 15 out of 21 archival pathology HB specimens. The CAIX-positive cells clustered in the middle of viable tumor tissue or next to necrotic areas. Tissue expression of CAIX mRNA was associated with metastasis and poor clinical outcome of HB. Hypoxia induced a striking upregulation of CAIX mRNA and protein in three HB cell models: the immortalized human HB cell line HUH6 and patient xenograft-derived lines HB-295 and HB-303. Administration of SLC-0111 abrogated the hypoxia-induced upregulation of CAIX and decreased HB cell viability, both in monolayer and spheroid cultures. In addition, SLC-0111 reduced HB cell motility in a wound healing assay. Transcriptomic changes triggered by SLC-0111 administration differed under normoxic vs. hypoxic conditions, although SLC-0111 elicited upregulation of several tumor suppressor genes under both conditions.

Conclusion

Hypoxia induces CAIX expression in HB cells, and the CAIX inhibitor SLC-0111 has in vitro activity against these malignant cells.

Challenging breast cancer through novel sulfonamide-pyridine hybrids: design, synthesis, carbonic anhydrase IX inhibition and induction of apoptosis

Background: Among the important key modulators of the tumor microenvironment and hypoxia is a family of enzymes named carbonic anhydrases. Herein, 11 novel sulfonamide-pyridine hybrids (2-12) were designed, synthesized and biologically evaluated for their potential use in targeting breast cancer. Methods & results: The para chloro derivative 7 reported the highest cytotoxic activity against the three breast cancer cell lines used. In addition, compound 7 was found to induce cell cycle arrest and autophagy as well as delaying wound healing. The IC₅₀ of compound 7 against carbonic anhydrase IX was 253 ± 12 nM using dorzolamide HCl as control. Conclusion: This study encourages us to expand the designed library, where more sulfonamide derivatives would be synthesized and studied for their structure-activity relationships.

Polyoxometalate-based nanocomposites for antitumor and antibacterial applications

Polyoxometalates (POMs), as emerging inorganic metal oxides, have been shown to have significant biological activity and great medicinal value. Nowadays, biologically active POM-based organic-inorganic hybrid materials have become the next generation of antibacterial and anticancer drugs because of their customizable molecular structures related to their highly enhanced antitumor activity and reduced toxicity to healthy cells. In this review, the current developed strategies with POM-based materials for the purpose of antibacterial and anticancer activities from different action principles inducing cell death and hyperpolarization, cell plasma membrane destruction, interference with bacterial respiratory chain and inhibiting bacterial growth are overviewed. Moreover, specific interactions between POM-based materials and biomolecules are highlighted for a better understanding of their antibacterial and anticancer mechanisms. POMs have great promise as next-generation antibacterial and anticancer drugs, and this review will provide a valuable systematic reference for the further development of POM-based nanomaterials.

Suppression of Tumor Growth and Cell Migration by Indole-Based Benzenesulfonamides and Their Synergistic Effects in Combination with Doxorubicin

Pharmacological inhibition of the enzyme activity targeting carbonic anhydrases (CAs) demonstrated antiglaucoma and anticancer effects through pH control. Recently, we reported a series of indole-based benzenesulfonamides as potent CA inhibitors. The present study aimed to evaluate the antitumor effects of these compounds against various cancer cell lines, including breast cancer (MDA-MB-231, MCF-7, and SK-BR-3), lung cancer (A549), and pancreatic cancer (Panc1) cells. Overall, more potent cytotoxicity was observed on MCF-7 and SK-BR-3 cells than on lung or pancreatic cancer cells. Among the 15 compounds tested, A6 and A15 exhibited potent cytotoxic and antimigratory activities against MCF-7 and SK-BR-3 cells in the CoCl₂-induced hypoxic condition. While A6 and A15 markedly reduced the viability of control siRNA-treated cells, these compounds could not significantly reduce the viability of CA IX-knockdown cells, suggesting the role of CA IX in their anticancer activities. To assess whether these compounds exerted synergism with a conventional anticancer drug doxorubicin (DOX), the cytotoxic effects of A6 or A15 combined with DOX were analyzed using Chou−Talalay and Bliss independence methods. Our data revealed that both A6 and A15 significantly enhanced the anticancer activity of DOX. Among the tested pairs, the combination of DOX with A15 showed the strongest synergism on SK-BR-3 cells. Moreover, this combination further attenuated cell migration compared to the respective drug. Collectively, our results demonstrated that A6 and A15 suppressed tumor growth and cell migration of MCF-7 and SK-BR-3 cells through inhibition of CA IX, and the combination of these compounds with DOX exhibited synergistic cytotoxic effects on these breast cancer cells. Therefore, A6 and A15 may serve as potential anticancer agents alone or in combination with DOX against breast cancer.

Expression and prognostic value of carbonic anhydrase IX (CA-IX) in bladder urothelial carcinoma

Objective

To investigate the expression intensity of carbonic anhydrase IX (CA-IX) in bladder urothelial carcinoma and its predictive value for the recurrence after transurethral resection of bladder tumor.

Methods

A retrospective analysis was made of 194 specimens who underwent transurethral resection of bladder tumors in our hospital from January 2014 to January 2016 and completed follow-up. The expression intensity of CA-IX and the clinical data of the patients were analyzed, and the subjects were divided into positive group and negative group according to the expression intensity of CA-IX. The age, gender, T stage, degree of differentiation, tumor number, tumor diameter, recurrence of each group was analyzed. Logistic univariate and multivariate analysis was used successively to find independent influencing factors for predicting the recurrence of bladder urothelial carcinoma after resection. The Kaplan–Meier survival curve was drawn according to the relationship between CA-IX expression intensity and postoperative recurrence.

Results

The positive expression rates of CA-IX in bladder urothelial carcinomas were 68.1% (132/194). The positive expression of CA-IX had no statistical significance with age, gender and tumor diameter (P > 0.05), while the positive expression of CA-IX had statistical significance with tumor T stage, tumor differentiation, tumor number and recurrence (P < 0.05); Logistic regression analysis showed that clinical T stage, tumor differentiation, tumor number, and CA-IX expression intensities were independent risk factors for predicting recurrence of bladder urothelial carcinoma after resection (P < 0.05); There were 59 cases of recurrence in the positive expression of CA-IX group, with a recurrence rate of 44.69% (59/132), and 17 cases of recurrence in the negative expression group, with a recurrence rate of 27.41% (17/62). The mean recurrence time of CA-IX positive group was 29.93 ± 9.86 (months), and the mean recurrence time of CA-IX negative group was 34.02 ± 12.44 (months). The Kaplan–Meier survival curve showed that the recurrence rate and recurrence time of patients with positive expression of CA-IX in bladder urothelial carcinomas were significantly higher than those of patients with negative expression of CA-IX.

Conclusion

CA-IX is highly expressed in bladder urothelial carcinoma, is a good tumor marker, and can be used as a good indicator for predicting the recurrence of bladder urothelial carcinoma after transurethral resection of bladder tumor.

Targeting carbonic anhydrase IX and XII isoforms with small molecule inhibitors and monoclonal antibodies

Carbonic anhydrases IX and CAXII (CAIX/CAXII) are transmembrane zinc metalloproteins that catalyze a very basic but crucial physiological reaction: the conversion of carbon dioxide into bicarbonate with a release of the proton. CA, especially CAIX and CAXII isoforms gained the attention of many researchers interested in anticancer drug design due to pivotal functions of enzymes in the cancer cell metastasis and response to hypoxia, and their expression restricted to malignant cells. This offers an opportunity to develop new targeted therapies with fewer side effects. Continuous efforts led to the discovery of a series of diverse compounds with the most abundant sulphonamide derivatives. Here we review current knowledge considering small molecule and antibody-based targeting of CAIX/CAXII in cancer.

Histone deacetylase inhibitor 2-hexyl-4-pentynoic acid enhances hydroxyurea therapeutic effect in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) treatment has only limited effect, and it causes a significant number of deaths. Histone deacetylase inhibitors (HDACis) are emerging as promising anti-tumor agents in many types of cancers. We thus hypothesized that 2-hexyl-4-pentynoic acid (HPTA), a novel HDACi, could sensitize TNBC to hydroxyurea (HU, a ribonucleotide reductase inhibitor). In the present study, we investigated the effect of HPTA, alone or in combination with HU on cell survival, DNA double-strand breaks (DSBs), key homologous recombination (HR) repair proteins and cell cycle progression in MDA-MB-468 and MDA-MB-231 human TNBC cell lines. HPTA and HU synergistically inhibited the survival of TNBC cell lines and resulted in the accumulation of DNA double-strand breaks (DSBs). HPTA can sensitize TNBC cells to HU by inhibiting replication protein A2 (RPA2) hyperphosphorylation-mediated HR repair, and lessen cell accumulation in S-phase by inhibiting ATR-CHK1 signaling pathway. Taken together, our data suggested that HPTA enhances HU therapeutic effect by blocking the HR repair and regulating cell cycle progression in TNBC.

Carbonic Anhydrase IX Inhibitors as Candidates for Combination Therapy of Solid Tumors

Combination therapy is becoming imperative for the treatment of many cancers, as it provides a higher chance of avoiding drug resistance and tumor recurrence. Among the resistance-conferring factors, the tumor microenvironment plays a major role, and therefore, represents a viable target for adjuvant therapeutic agents. Thus, hypoxia and extracellular acidosis are known to select for the most aggressive and resilient phenotypes and build poorly responsive regions of the tumor mass. Carbonic anhydrase (CA, EC 4.2.1.1) IX isoform is a surficial zinc metalloenzyme that is proven to play a central role in regulating intra and extracellular pH, as well as modulating invasion and metastasis processes. With its strong association and distribution in various tumor tissues and well-known druggability, this protein holds great promise as a target to pharmacologically interfere with the tumor microenvironment by using drug combination regimens. In the present review, we summarized recent publications revealing the potential of CA IX inhibitors to intensify cancer chemotherapy and overcome drug resistance in preclinical settings.

Carbonic anhydrase inhibition, antioxidant activity against alveolar epithelial cells and antibacterial effect against Klebsiella pneumoniae enabled by synthesized silica nanoparticles through laser ablation technique

Silica (SiO₂) nanoparticles (NPs) were synthesized by laser ablation method and were characterized by TEM and DLS techniques. Afterwards, their inhibition activity against carbonic anhydrase (CA) isoforms (CA I and CA II) was explored by experimental and theoretical analysis. Also, the protective effect of SiO₂ NPs against H₂O₂-induced oxidative stress in alveolar epithelial cells (A549) were assessed by measurement of MTT, ROS level, CAT and SOD activity and GSH content. Finally, the NPs were screened for their antimicrobial activity using the MICs method against the Klebsiella pneumoniae. The result showed that the synthesized NPs have a size of around 40 nm. The inhibition activity by comparing IC50 values with acetazolamide as a positive control revealed that SiO₂ NPs in comparison with acetazolamide served as potent inhibitors against CA isoforms which was also confirmed by docking studies. The cellular assays indicated that the SiO₂ NPs with a concentration of 20 μg/mL stimulated a significant antioxidant activity against H₂O₂-induced oxidative cell damage through activation of CAT and SOD, an increase in the GSH content and reducing the level of ROS. The synthesize NPs also showed a good inhibition effect against Klebsiella pneumoniae as compared to Sulfamethoxazole as a positive control. In conclusion, this data may provide some useful information on the development of some platforms for pneumonia treatment and management.

Hybrid inhibitors of DNA and HDACs remarkably enhance cytotoxicity in leukaemia cells

Chlorambucil is a nitrogen mustard-based DNA alkylating drug, which is widely used as a front-line treatment of chronic lymphocytic leukaemia (CLL). Despite its widespread application and success for the initial treatment of leukaemia, a majority of patients eventually develop acquired resistance to chlorambucil. In this regard, we have designed and synthesised a novel hybrid molecule, chloram-HDi that simultaneously impairs DNA and HDAC enzymes. Chloram-HDi efficiently inhibits the proliferation of HL-60 and U937 leukaemia cells with GI₅₀ values of 1.24 µM and 1.75 µM, whereas chlorambucil exhibits GI₅₀ values of 21.1 µM and 37.7 µM against HL-60 and U937 leukaemia cells, respectively. The mechanism behind its remarkably enhanced cytotoxicity is that chloram-HDi not only causes a significant DNA damage of leukaemia cells but also downregulates DNA repair protein, Rad52, resulting in the escalation of its DNA-damaging effect. Furthermore, chloram-HDi inhibits HDAC enzymes to induce the acetylation of α-tubulin and histone H3.

Temozolomide-Loaded Solid Lipid Nanoparticles@Hydrogel for Local Treatment of Tumour

Temozolomide (TMZ) is a significant anticancer agent especially for chemotherapy of glioblastoma. In order to reduce the recurrence rate of cancer, in this work an injectable hydrogel composed of TMZ-loaded solid lipid nanoparticles (SLNs) was designed for filling the cavity of a glioblastoma operation. First, TMZ-loaded SLNs (T-SLNs) were prepared by emulsion solvent diffusion and evaporation technology. The optimised formulation showed a particle size of 190.8±15.3nm, a Zeta potential of −20.2±1.7mV, an entrapment efficiency (EE%) of 99.3±0.5%, and drug loading (DL%) of 15.1±2.7%. The optimised formulation was freeze-dried and characterised by scanning electron microscopy (SEM), differential thermogravimetry (DTG), X-ray diffraction (XRD), and stability tests. The freeze-dried T-SLNs were then incorporated into a hydroxypropyl chitosan (HPCS)/diarylaldehyde PEG (PEG-DF) hydrogel bonded with an MRI contrast agent. The hydrogels were evaluated for invitro drug release and cytotoxicity. The results indicated that compared with free TMZ, the T-SLNs@hydrogel prolonged drug release, and both blank SLNs and hydrogel materials did not exhibit cytotoxicity, suggesting the therapeutic efficacy of TMZ was reserved. Thus, comparing with its conventional oral administration, the obtained TMZ-loaded SLNs and the hydrogel could be more potent for local treatment of glioblastoma after an operation.

Groundbreaking Anticancer Activity of Highly Diversified Oxadiazole Scaffolds

Nowadays, an increasing number of heterocyclic-based drugs found application in medicinal chemistry and, in particular, as anticancer agents. In this context, oxadiazoles—five-membered aromatic rings—emerged for their interesting biological properties. Modification of oxadiazole scaffolds represents a valid strategy to increase their anticancer activity, especially on 1,2,4 and 1,3,4 regioisomers. In the last years, an increasing number of oxadiazole derivatives, with remarkable cytotoxicity for several tumor lines, were identified. Structural modifications, that ensure higher cytotoxicity towards malignant cells, represent a solid starting point in the development of novel oxadiazole-based drugs. To increase the specificity of this strategy, outstanding oxadiazole scaffolds have been designed to selectively interact with biological targets, including enzymes, globular proteins, and nucleic acids, showing more promising antitumor effects. In the present work, we aim to provide a comprehensive overview of the anticancer activity of these heterocycles, describing their effect on different targets and highlighting how their structural versatility has been exploited to modulate their biological properties.

Association of Carbonic Anhydrase 9 Polymorphism and the Epithelial Growth Factor Receptor Mutations in Lung Adenocarcinoma Patients

Carbonic anhydrase 9 (CA9) plays a vital role in lung cancer progression. The current study explored the effect of CA9 gene polymorphisms and the epidermal growth factor receptor (EGFR) mutations on the clinicopathological characters of lung adenocarcinoma. In this study, three loci of CA9 single nucleotide polymorphism (SNP) (rs2071676 A>G, rs3829078 A>G, and rs1048638 C>A) were genotyped using the TaqMan allelic discrimination method in 193 EGFR wild type individuals and 281 EGFR mutation subjects. After adjusting for age, gender, and cigarette smoking status in logistic regression, all three CA9 SNPs illustrated a non-significant difference for the distribution between the EGFR wild type group and EGFR mutation group. Nevertheless, a significantly lower rate of CA9 SNP rs2071676 AG (adjusted odds ratio (AOR): 0.40, 95% confidence interval (CI): 0.16-0.95, p = 0.039) and AG+GG (AOR: 0.43, 95% CI: 0.18-0.98, p = 0.046) were found in the male population with L858R EGFR mutation compared to men with EGFR wild type. In addition, the CA9 SNP rs2071676 AG+GG genotype were significantly correlated to the lower tumor stage of lung adenocarcinoma in the whole study population (p = 0.044) and EGFR wild type individuals (p = 0.033). For the male population, the presence of CA9 SNP rs2071676 AG+GG genotype was also correlated to a lower tumor stage (p = 0.037) and fewer lymph node invasion (p = 0.003) in those with EGFR wild type. In conclusion, the existence of CA9 SNP rs2071676 is associated with the rate of EGFR L858R mutation in males. Furthermore, the CA9 SNP rs2071676 is correlated to lower tumor stage and lower risk for developing lymph node metastasis in lung adenocarcinoma, mainly in the EGFR wild type.

Exploring the multiple binding modes of inhibitors to carbonic anhydrases for novel drug discovery

INTRODUCTION

The spacious active site cavity of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) shows a great versatility for a variety of binding modes for modulators of activity, inhibitors, and activators, some of which are clinically used drugs.

AREAS COVERED

There are at least four well-documented CA inhibition mechanisms and the same number of binding modes for CA inhibitors (CAIs), one of which superposes with the binding of activators (CAAs). They include (i) coordination to the catalytic metal ion; (ii) anchoring to the water molecule coordinated to the metal ion; (iii) occlusion of the active site entrance; and (iv) binding outside the active site. A large number of chemical classes of CAIs show these binding modes explored in detail by kinetic, crystallographic, and other techniques. The tail approach was applied to all of them and allowed many classes of highly isoform-selective inhibitors. This is the subject of our review.

EXPERT OPINION

All active site regions of CAs accommodate inhibitors to bind, which is reflected in very different inhibition profiles for such compounds and the possibility to design drugs with effective action and new applications, such as for the management of hypoxic tumors, neuropathic pain, cerebral ischemia, arthritis, and degenerative disorders.