The carbonic anhydrase IX inhibitor SLC-0111 sensitises cancer cells to conventional chemotherapy

Carbonic anhydrase IX: An atypical target for innovative therapies in cancer

Carbonic anhydrases (CAs), are metallo-enzymes implicated in several pathophysiological processes where tissue pH regulation is required. CA IX is a tumor-associated CA isoform induced by hypoxia and involved in the adaptation of tumor cells to acidosis. Indeed, several tumor-driving pathways can induce CA IX expression, and this in turn has been associated to cancer cells invasion and metastatic features as well as to induction of stem-like features, drug resistance and recurrence. After its functional and structural characterization CA IX targeting approaches have been developed to inhibit its activity in neoplastic tissues, and to date this field has seen an incredible acceleration in terms of therapeutic options and biological readouts. Small molecules inhibitors, hybrid/dual targeting drugs, targeting antibodies and adoptive (CAR-T based) cell therapy have been developed at preclinical level, whereas a sulfonamide CA IX inhibitor and an antibody entered Phase Ib/II clinical trials for the treatment and imaging of different solid tumors. Here recent advances on CA IX biology and pharmacology in cancer, and its therapeutic targeting will be discussed.

Identification and characterization of a new potent inhibitor targeting CtBP1/BARS in melanoma cells

BACKGROUND

The C-terminal-binding protein 1/brefeldin A ADP-ribosylation substrate (CtBP1/BARS) acts both as an oncogenic transcriptional co-repressor and as a fission inducing protein required for membrane trafficking and Golgi complex partitioning during mitosis, hence for mitotic entry. CtBP1/BARS overexpression, in multiple cancers, has pro-tumorigenic functions regulating gene networks associated with "cancer hallmarks" and malignant behavior including: increased cell survival, proliferation, migration/invasion, epithelial-mesenchymal transition (EMT). Structurally, CtBP1/BARS belongs to the hydroxyacid-dehydrogenase family and possesses a NAD(H)-binding Rossmann fold, which, depending on ligands bound, controls the oligomerization of CtBP1/BARS and, in turn, its cellular functions. Here, we proposed to target the CtBP1/BARS Rossmann fold with small molecules as selective inhibitors of mitotic entry and pro-tumoral transcriptional activities.

METHODS

Structured-based screening of drug databases at different development stages was applied to discover novel ligands targeting the Rossmann fold. Among these identified ligands, N-(3,4-dichlorophenyl)-4-{[(4-nitrophenyl)carbamoyl]amino}benzenesulfonamide, called Comp.11, was selected for further analysis. Fluorescence spectroscopy, isothermal calorimetry, computational modelling and site-directed mutagenesis were employed to define the binding of Comp.11 to the Rossmann fold. Effects of Comp.11 on the oligomerization state, protein partners binding and pro-tumoral activities were evaluated by size-exclusion chromatography, pull-down, membrane transport and mitotic entry assays, Flow cytometry, quantitative real-time PCR, motility/invasion, and colony assays in A375MM and B16F10 melanoma cell lines. Effects of Comp.11 on tumor growth in vivo were analyzed in mouse tumor model.

RESULTS

We identify Comp.11 as a new, potent and selective inhibitor of CtBP1/BARS (but not CtBP2). Comp.11 directly binds to the CtBP1/BARS Rossmann fold affecting the oligomerization state of the protein (unlike other known CtBPs inhibitors), which, in turn, hinders interactions with relevant partners, resulting in the inhibition of both CtBP1/BARS cellular functions: i) membrane fission, with block of mitotic entry and cellular secretion; and ii) transcriptional pro-tumoral effects with significantly hampered proliferation, EMT, migration/invasion, and colony-forming capabilities. The combination of these effects impairs melanoma tumor growth in mouse models.  CONCLUSIONS: This study identifies a potent and selective inhibitor of CtBP1/BARS active in cellular and melanoma animal models revealing new opportunities to study the role of CtBP1/BARS in tumor biology and to develop novel melanoma treatments.

Effective Anticancer Potential of a New Sulfonamide as a Carbonic Anhydrase IX Inhibitor Against Aggressive Tumors

This study examines efficiency of a newly synthesized sulfonamide derivative 2-bromo-N-(4-sulfamoylphenyl)propanamide (MMH-1) on the inhibition of Carbonic Anhydrase IX (CA IX), which is overexpressed in many solid tumors including breast cancer. The inhibitory potential of MMH-1 compound against its four major isoforms, including cytosolic isoforms hCA I and II, as well as tumor-associated membrane-bound isoforms hCA IX and XII, was evaluated. To this context, the cytotoxic effect of MMH-1 on cancer and normal cells was tested and found to selectively affect MDA-MB-231 cells. MMH-1 reduced cell proliferation by holding cells in the G0/G1 phase (72 %) and slowed the cells' wound healing capacity. MMH-1 inhibited CA IX under both hypoxic and normoxic conditions and altered the morphology of triple negative breast cancer cells. In MDA-MB-231 cells, inhibition of CA IX was accompanied by a decrease in extracellular pH acidity (7.2), disruption of mitochondrial membrane integrity (80 %), an increase in reactive oxygen levels (25 %), and the triggering of apoptosis (40 %). In addition, the caspase cascade (CASP-3, -8, -9) was activated in MDA-MB-231 cells, triggering both the extrinsic and intrinsic apoptotic pathways. The expression of pro-apoptotic regulatory proteins (Bad, Bax, Bid, Bim, Cyt-c, Fas, FasL, TNF-a, TNF-R1, HTRA, SMAC, Casp-3, -8, P21, P27, and P53) was increased, while the expression of anti-apoptotic proteins, apoptosis inhibitor proteins (IAPs), and heat shock proteins (HSPs) (Bcl-2, Bcl-w, cIAP-2, HSP27, HSP60, HSP70, Survivin, Livin, and XIAP) was decreased. These results propose that the MMH-1 compound could triggers apoptosis in MDA-MB-231 cells via the pH/MMP/ROS pathway through the inhibition of CA IX. This compound is thought to have high potential and promising anticancer properties in the treatment of aggressive tumors.

A comparative study of diaryl urea molecules with and without sulfonamide group on Carbonic anhydrase IX and XII inhibition and its consequence on breast cancer cells

To investigate the intrinsic relation between carbonic anhydrase inhibition and anticancer activity, we have prepared four sets of diaryl urea molecules and tested for the inhibition of hCA-IX and XII on two breast cancer cell lines. Among 21 compounds, compound J2 (with -SO2NH2 group) and J16 (without -SO2NH2 group) showed the best activity under normoxic and hypoxic conditions. The IC50 values of J16 for MDA-MB-231 and MCF-7 cells, under normoxic condition were 6.3 and 3.7 µM respectively, which are 1.9/3.3 and 15.8 times better than U-4-Nitro and SLC-0111 respectively. Whereas, under the hypoxic condition the corresponding values were 12.4 and 1.1 µM (MDA-MB-231 and MCF-7 cells respectively), which are equal/8 times better than U-4-Nitro. Whereas, J2 showed better IC50 value than U-4-Nitro (6.3 µM) under normoxic condition for both MDA-MB-231 and MCF-7 cells (1.9/2.7 times). Compound J2 inhibits the activity of hCA-IX and XII in nanomolar concentration [Ki values 4.09 and 9.10 nM respectively with selectivity ratio of 1.8 and 0.8 with hCA-II]. The crystal structure and modelling studies demonstrates that the inhibition of CAs arises due to the blocking of the CO2 coordination site of zinc in its catalytic domain. However, J16 was found to be unable to inhibit the activity of hCAs (Ki > 89000 nM). qPCR and western blot analysis showed a significant reduction (1.5 to 20 fold) of the transcription and expression of HIF1A, CA9 and CA12 genes in presence of J2 and J16. Both J2 and J16 found to reduce accumulation of HIF-1α protein by inhibiting the chaperone activity of hHSP70 with IC50 values of 19.4 and 15.3 µM respectively. Perturbation of the hCA-IX and XII activity by binding at active site or by reduced expression or by both leads to the decrease of intracellular pH, which resulted in concomitant increase of reactive oxygen species by 2.6/2.0 (MCF-7) and 2.9/1.8 (MDA-MB-231) fold for J2/J16. Increased cyclin D1 expression in presence of J2 and J16 was presumed to be indirectly responsible for the apoptosis of the cancer cells. Expression of the other apoptosis markers Bcl-2, Bim, caspase 9 and caspase 3 substantiated the apoptosis mechanism. However, decreased transcription/expression of HIF1A/HIF-1α and hCA-IX/XII also implies the inhibition of the extracellular signal-regulated kinase pathway by J2 and J16.

New imidazole-2-ones and their 2-thione analogues as anticancer agents and CAIX inhibitors: Synthesis, in silico ADME and molecular modeling studies

The present study involves the synthesis of a series of new imidazole-2-ones derivatives and their 2-thione analogs using conventional heating and the environmentally friendly benign technique, the microwave technique. Structure of the compounds was well elucidated by considering the data of both elemental and spectral analyses. The obtained data and theoretical values of the synthesized molecules correlated with the proposed molecular structure. Moreover, all the synthesized compounds were evaluated in vitro for antitumor activity against HCT-116 and HeP2 human cancer cell panels and assessed as selective carbonic anhydrase IX isozyme (CA9/CAIX) inhibitors, thereby providing useful preliminary evidence for drug development. In addition, computational techniques were used to investigate the molecular and electronic characteristics of the investigated organic compounds. The 4b compound exhibited the best quantum chemistry features, as the highest occupied molecular orbital, softness, energy gap, and dipole moment, indicating the highest biological activity. This was supported by the experimental findings. Moreover, the in silico evaluation of drug candidates was also investigated. Thereafter, the anticancer activity of the most reactive candidate was studied via molecular docking to determine the types of interactions between this molecule and CAIX. According to the docking experiments, the 4b molecule generates five hydrogen bond interactions with active amino acid residues, Gln 92, Gln 67, and Thr 200.

Ureidobenzenesulfonamides as Selective Carbonic Anhydrase I, IX, and XII Inhibitors

Sulfonamides remain an important class of drugs, especially because of their inhibitory effects on carbonic anhydrases. Herein, we have synthesized several sulfonamides and tested them for their inhibitory activity against carbonic anhydrases hCA I, hCA II, hCA IX, and hCA XII, respectively. Thereby, biphenyl- and benzylphenyl-substituted sulfonamides showed high selectivity against hCA IX and hCA XII; these enzymes are common targets in the treatment of hypoxic cancers, and noteworthy inhibitory activity was observed for several compounds toward hCA I that might be of interest for future applications to treat cerebral edema. Compound 3 (4-[3-(2-benzylphenyl)ureido]benzenesulfonamide) held an exceptionally low Ki value of 1.0 nM for hCA XII.

Recent advances in synthetic strategies and SAR of thiazolidin-4-one containing molecules in cancer therapeutics

Cancer is one of the life-threatening diseases accountable for millions of demises globally. The inadequate effectiveness of the existing chemotherapy and its harmful effects has resulted in the necessity of developing innovative anticancer agents. Thiazolidin-4-one scaffold is among the most important chemical skeletons that illustrate anticancer activity. Thiazolidin-4-one derivatives have been the subject of extensive research and current scientific literature reveals that these compounds have shown significant anticancer activities. This manuscript is an earnest attempt to review novel thiazolidin-4-one derivatives demonstrating considerable potential as anticancer agents along with a brief discussion of medicinal chemistry-related aspects of these compounds and structural activity relationship studies in order to develop possible multi-target enzyme inhibitors. Most recently, various synthetic strategies have been developed by researchers to get various thiazolidin-4-one derivatives. In this review, the authors highlight the various synthetic, green, and nanomaterial-based synthesis routes of thiazolidin-4-ones as well as their role in anticancer activity by inhibition of various enzymes and cell lines. The detailed description of the existing modern standards in the field presented in this article may be interesting and beneficial to the scientists for further exploration of these heterocyclic compounds as possible anticancer agents.

The CAIX inhibitor SLC-0111 exerts anti-cancer activity on gastric cancer cell lines and resensitizes resistant cells to 5-Fluorouracil, taxane-derived, and platinum-based drugs

Gastric cancer (GC) is the fifth most frequent malignancy and the fourth leading cause of worldwide cancer-related death. Despite the usage of multimodal perioperative chemotherapy (pCT), GC progressively gains chemoresistance, thereby, the identification of suitable targets to overcome drug resistance is fundamental. Amongst the potential biomarkers, carbonic anhydrase IX (CAIX) - associated with a poor prognosis of several solid cancers - has gained the most attention. In a cohort of GC patients who received perioperative FLOT (i.e., Leucovorin, 5-Fluouracil, Docetaxel, and Oxaliplatin) or FOLFOX (i.e., Leucovorin, 5-Fluouracil, and Oxaliplatin), non-responder patients showed an increased expression of tumor CAIX compared to responder group. Moreover, GC cell lines induced to be resistant to 5-Fluouracil, Paclitaxel, Cisplatin, or the combination of 5-Fluorouracil, Oxaliplatin, and Docetaxel, overexpressed CAIX compared to the control. Accordingly, CAIX-high-expressing GC cells showed increased therapy resistance compared to low-expressing cells. Notably, SLC0111 significantly improved the therapy response of both wild-type and resistant GC cells. Overall, these data suggest a correlation between CAIX and GC drug resistance highlighting the potential of SLC-0111 in re-sensitizing GC cells to pCT.

CA-IX-Expressing Small Extracellular Vesicles (sEVs) Are Released by Melanoma Cells under Hypoxia and in the Blood of Advanced Melanoma Patients

Cutaneous melanoma is a highly aggressive skin cancer, with poor prognosis. The tumor microenvironment is characterized by areas of hypoxia. Carbonic anhydrase IX (CA-IX) is a marker of tumor hypoxia and its expression is regulated by hypoxia-inducible factor-1 (HIF-1). CA-IX has been found to be highly expressed in invasive melanomas. In this study, we investigated the effects of hypoxia on the release of small extracellular vesicles (sEVs) in two melanoma in vitro models. We demonstrated that melanoma cells release sEVs under both normoxic and hypoxic conditions, but only hypoxia-induced sEVs express CA-IX mRNA and protein. Moreover, we optimized an ELISA assay to provide evidence for CA-IX protein expression on the membranes of the sEVs. These CA-IX-positive sEVs may be exploited as potential biomarkers for liquid biopsy.

Inhibition of Bone Marrow-Mesenchymal Stem Cell-Induced Carbonic Anhydrase IX Potentiates Chemotherapy Efficacy in Triple-Negative Breast Cancer Cells

Conventional chemotherapy represents the main systemic treatment used for triple-negative breast cancer (TNBC) patients, although many of them develop drug resistance. The hypoxic TME is the crucial driver in the onset of insensitivity to chemotherapy. In this research, we elucidated the role played by bone marrow-derived mesenchymal stem cells (BM-MSCs) in reducing cisplatin effects in TNBC. BT-549 and MDA-MB-231 cells, grown under hypoxic conditions in the presence of conditioned medium obtained from BM-MSCs (CM-MSCs), showed a strong cisplatin insensitivity and increased expression levels of carbonic anhydrase IX (CA IX). Therefore, we inhibited CM-MSC-induced CA IX by SLC-0111 to potentiate chemotherapy efficacy in TNBC cells. Our results showed that CM-MSCs under hypoxic conditions caused an increase in the ability of TNBC cells to form vascular structures, migrate and invade Matrigel. Cell treatment with cisplatin plus SLC-0111 was able to block these mechanisms, as well as the signaling pathways underlying them, such as p-AKT, p-ERK, CD44, MMP-2, vimentin, β-catenin, and N-cadherin, more effectively than treatment with single agents. In addition, a significant enhancement of apoptosis assessed by annexin V, caspase-3 expression and activity was also shown. Taken together, our results demonstrated the possibility, through CA IX inhibition, of returning TNBC cells to a more chemosensitive state.

Mitochondrial carbonic anhydrase VA and VB: properties and roles in health and disease

Carbonic anhydrase V (CA V), a mitochondrial enzyme, was first isolated from guinea-pig liver and subsequently identified in mice and humans. Later, studies revealed that the mouse genome contains two mitochondrial CA sequences, named Car5A and Car5B. The CA VA enzyme is most highly expressed in the liver, whereas CA VB shows a broad tissue distribution. Car5A knockout mice demonstrated a predominant role for CA VA in ammonia detoxification, whereas the roles of CA VB in ureagenesis and gluconeogenesis were evident only in the absence of CA VA. Previous studies have suggested that CA VA is mainly involved in the provision of HCO₃ ^- for biosynthetic processes. In children, mutations in the CA5A gene led to reduced CA activity, and the enzyme was sensitive to increased temperature. The metabolic profiles of these children showed a reduced supply of HCO₃ ^- to the enzymes that take part in intermediary metabolism: carbamoylphosphate synthetase, pyruvate carboxylase, propionyl-CoA carboxylase and 3-methylcrotonyl-CoA carboxylase. Although the role of CA VB is still poorly understood, a recent study reported that it plays an essential role in human Sertoli cells, which sustain spermatogenesis. Metabolic disease associated with CA VA appears to be more common than other inborn errors of metabolism and responds well to treatment with N-carbamyl-l-glutamate. Therefore, early identification of hyperammonaemia will allow specific treatment with N-carbamyl-l-glutamate and prevent neurological sequelae. Carbonic anhydrase VA deficiency should therefore be considered a treatable condition in the differential diagnosis of hyperammonaemia in neonates and young children.

Benzenesulfonamides with different rigidity-conferring linkers as carbonic anhydrase inhibitors: an insight into the antiproliferative effect on glioblastoma, pancreatic, and breast cancer cells

Among the chemotypes studied for selective inhibition of tumour-associated carbonic anhydrases (CAs), SLC-0111, a ureido-bearing benzenesulfonamide CA IX inhibitor, displayed promising antiproliferative effects in cancer cells in vitro and in vivo, being in Phase Ib/II clinical development. To explore the structural characteristics required for better discrimination of less conserved regions of the enzyme, we investigate the incorporation of the urea linker into an imidazolidin-2-one cycle, a modification already explored previously for obtaining CA inhibitors. This new library of compounds inhibited potently four different hCAs in the nanomolar range with a different isoform selectivity profile compared to the lead SLC-0111. Several representative CA IX inhibitors were tested for their efficacy to inhibit the proliferation of glioblastoma, pancreatic, and breast cancer cells expressing CA IX, in hypoxic conditions. Unlike previous literature data on SLC-149, a structurally related sulphonamide to compounds investigated here, our data reveal that these derivatives possess promising anti-proliferative effects, comparable to those of SLC-0111.

N-Cycloamino substituent effects on the packing architecture of ortho-sulfanilamide molecular crystals and their in silico carbonic anhydrase II and IX inhibitory activities

In the search for new `sulfa drugs' with therapeutic properties, o-nitrosulfonamides and N-cycloamino-o-sulfanilamides were synthesized and characterized using techniques including ¹H NMR, ¹³C NMR and FT-IR spectroscopy, and single-crystal X-ray diffraction (SC-XRD). The calculated density functional theory (DFT)-optimized geometry of the molecules showed similar conformations to those obtained by SC-XRD. Molecular docking of N-piperidinyl-o-sulfanilamide and N-indolinyl-o-sulfanilamide supports the notion that o-sulfanilamides are able to bind to human carbonic anhydrase II and IX inhibitors (hCA II and IX; PDB entries 4iwz and 5fl4). Hirshfeld surface analyses and DFT studies of three o-nitrosulfonamides {1-[(2-nitrophenyl)sulfonyl]pyrrolidine, C₁₀H₁₂N₂O₄S, 1, 1-[(2-nitrophenyl)sulfonyl]piperidine, C₁₁H₁₄N₂O₄S, 2, and 1-[(2-nitrophenyl)sulfonyl]-2,3-dihydro-1H-indole, C₁₄H₁₂N₂O₄S, 3} and three N-cycloamino-o-sulfanilamides [2-(pyrrolidine-1-sulfonyl)aniline, C₁₀H₁₄N₂O₂S, 4, 2-(piperidine-1-sulfonyl)aniline, C₁₁H₁₆N₂O₂S, 5, and 2-(2,3-dihydro-1H-indole-1-sulfonyl)aniline, C₁₄H₁₄N₂O₂S, 6] suggested that forces such as hydrogen bonding and π-π interactions hold molecules together and further showed that charge transfer could promote bioactivity and the ability to form biological interactions at the piperidinyl and phenyl moieties.

Carbonic anhydrase IX: A tumor acidification switch in heterogeneity and chemokine regulation

The primary physiological process of respiration produces carbon dioxide (CO₂) that reacts with water molecules which subsequently liberates bicarbonate (HCO-₃) and protons. Carbonic anhydrases (CAs) are the primary catalyst involved in this conversion. More than 16 isoforms of human CAs show organ or subcellular specific activity. Dysregulation of each CA is associated with multiple pathologies. Out of these members, the overexpression of membrane-bound carbonic anhydrase IX (CAIX) is associated explicitly with hypoxic tumors or various solid cancers. CAIX helps tumors deal with higher CO₂ by sequestering it with bicarbonate ions and helping cancer cells to grow in a comparatively hypoxic or acidic environment, thus acting as a pH adaptation switch. CAIX-mediated adaptations in cancer cells include angiogenesis, metabolic alterations, tumor heterogeneity, drug resistance, and regulation of cancer-specific chemokines. This review comprehensively collects and describe the cancer-specific expression mechanism and role of CAIX in cancer growth, progression, heterogeneity, and its structural insight to develop future combinatorial targeted cancer therapies.

Warburg effect in colorectal cancer: the emerging roles in tumor microenvironment and therapeutic implications

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death worldwide. Countless CRC patients undergo disease progression. As a hallmark of cancer, Warburg effect promotes cancer metastasis and remodels the tumor microenvironment, including promoting angiogenesis, immune suppression, cancer-associated fibroblasts formation and drug resistance. Targeting Warburg metabolism would be a promising method for the treatment of CRC. In this review, we summarize information about the roles of Warburg effect in tumor microenvironment to elucidate the mechanisms governing Warburg effect in CRC and to identify novel targets for therapy.

Lineage plasticity in prostate cancer: Looking beyond intrinsic alterations

Emergence of small cell prostate cancer is linked to the plasticity of tumour cells and avoidance of environmental pressures. This process is thought to be reversable, however to-date evidence of this has been demonstrated in small-cell prostate cancer. To study the plasticity of prostate tumours, we look to clinical cohorts of patients covering the spectra of malignancy subtypes and utilise in vitro and in vivo models of disease progression. Current models have assisted in the understanding of the extremities of this plasticity, elucidating internal mechanisms and adaptations to stressors through transition to altered cell states. By interrogating the tumour microenvironment and earlier time points, we are beginning to form a deeper understanding of the full spectra of tumour plasticity. It could be proffered that this deeper understanding will lead to better patient outcome, with earlier interventions more likely to reverse plasticity and prevent trans-differentiation to the aggressive, small cell phenotype.

Novel 2-substituted thioquinazoline-benzenesulfonamide derivatives as carbonic anhydrase inhibitors with potential anticancer activity

A novel series of 2-thioquinazoline-benzenesulfonamide hybrids were designed as carbonic anhydrase (CA) inhibitors. The design approach relies on molecular hybridization between the benzenesulfonamide scaffold as a Zn²⁺ binding group and 2-substituted thioquinazolines as a tail. Assaying the thioquinazoline-benzenesulfonamide conjugates against four different CA isoforms revealed that compounds 12f and 12p are the most potent derivatives. They exhibit K_i  = 0.09 and 0.05 µM on CA II, 0.32 and 0.47 µM on CA IX, and 0.58 and 0.46 µM on CA XII, respectively. In addition, 12p demonstrated high selectivity for CA II over CA I with selectivity index (SI) = 92, and slightly higher specificity for CA II over CA IX and CA XII with SI = 9.40 and 9.20, respectively. The synthesized compounds were screened for their cytotoxic activity at 10 µM concentration and derivatives 12o, 12n, and 12f turned out to be the most potent ones from the synthesized series; they exhibit mean growth inhibition % values of 89.38%, 58.75%, and 54.71%, respectively, while 12p demonstrated moderate activity against the NCI cancer cell lines, with mean growth inhibition % = 29.62%. The analysis of the MCF-7 cell cycle after treatment with 5.0 µM of 12f displayed that it arrests the cell cycle at the G2/M phase. Molecular docking simulation of the thioquinazoline-benzenesulfonamide hybrids in the CA II active site rationalized the potent activity to the settlement of the sulfonamide moiety at the depth of the CA II active site and its stabilization by performing the important interactions with the Zn²⁺ ion as well as with the key amino acids Thr199 and/or Thr200, while the thioquinazoline moiety with different (un)substituted phenyl tails is stabilized by the formation of various hydrogen bonding and hydrophobic interactions with the surrounding amino acids in the binding site.

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.

Cancer Therapeutic Targeting of Hypoxia Induced Carbonic Anhydrase IX: From Bench to Bedside

Simple Summary

Tumor hypoxia remains a significant problem in the effective treatment of most cancers. Tumor cells within hypoxic niches tend to be largely resistant to most therapeutic modalities, and adaptation of the cells within the hypoxic microenvironment imparts the cells with aggressive, invasive behavior. Thus, a major goal of successful cancer therapy should be the eradication of hypoxic tumor cells. Carbonic Anhydrase IX (CAIX) is an exquisitely hypoxia induced protein, selectively expressed on hypoxic tumor cells, and thus has garnered significant attention as a therapeutic target. In this Commentary, we discuss the current status of targeting CAIX, and future strategies for effective, durable cancer treatment.

Abstract

Carbonic Anhydrase IX (CAIX) is a major metabolic effector of tumor hypoxia and regulates intra- and extracellular pH and acidosis. Significant advances have been made recently in the development of therapeutic targeting of CAIX. These approaches include antibody-based immunotherapy, as well as use of antibodies to deliver toxic and radioactive payloads. In addition, a large number of small molecule inhibitors which inhibit the enzymatic activity of CAIX have been described. In this commentary, we highlight the current status of strategies targeting CAIX in both the pre-clinical and clinical space, and discuss future perspectives that leverage inhibition of CAIX in combination with additional targeted therapies to enable effective, durable approaches for cancer therapy.

In-silico predicting as a tool to develop plant-based biomedicines and nanoparticles: Lycium shawii metabolites

INTRODUCTION AND PURPOSE

In silico approach helps develop biomedicines and is useful for exploring the pharmacology of potential therapeutics using computer-simulated models. In vitro assays were used to determine the anti-microbial and cytotoxic efficacies of silver nanoparticles (AgNPs) synthesized with the shrub Lycium shawii.

METHODS

In silico predicting was performed to assess the L. shawii metabolites identified using QTOF-LCMS for their pharmacological properties. L. shawii mediated AgNPs were synthesized and characterized (FTIR, TEM, SEM, DLS and EDX). The anti-bacterial efficacies of L. shawii extract, AgNPs, and penicillin-conjugated AgNPs (pen-AgNPs) were determined. The cytotoxicity of the AgNPs was measured against colorectal cancer cell line (HCT116), normal breast epithelium (MCF 10 A), and breast cancer cell line (MDA MB 231).

RESULTS AND DISCUSSION

Five molecules (costunolide, catechin, emodin, lyciumaside, and aloe emodin 11-O-rhamnoside) were detected in the L. shawii extract. AgNPs (69 nm) were spherical with crystallographic structure. All three agents prepared showed inhibitory activity against the tested bacteria, the most efficacious being pen-AgNPs. High cytotoxicity of AgNPs (IC₅₀ 62 μg/ml) was observed against HCT116, IC₅₀ was 78 μg/ml for MCF 10 A, and 250 μg/ml for MDA MB 231, of which cells showed apoptotic features under TEM examination. The in silico approach indicated that the carbonic anhydrase IX enzyme was the target molecule mediating anti-cancer and anti-bacterial activities and that emodin was the metabolite in action.

CONCLUSIONS

Combining in vitro studies and in silico molecular target prediction helps find novel therapeutic agents. Among L. shawii metabolites, emodin is suggested for further studies as an agent for drug development against pathogenic bacteria and cancer.

MDACT: A New Principle of Adjunctive Cancer Treatment Using Combinations of Multiple Repurposed Drugs, with an Example Regimen

In part one of this two-part paper, we present eight principles that we believe must be considered for more effective treatment of the currently incurable cancers. These are addressed by multidrug adjunctive cancer treatment (MDACT), which uses multiple repurposed non-oncology drugs, not primarily to kill malignant cells, but rather to reduce the malignant cells' growth drives. Previous multidrug regimens have used MDACT principles, e.g., the CUSP9v3 glioblastoma treatment. MDACT is an amalgam of (1) the principle that to be effective in stopping a chain of events leading to an undesired outcome, one must break more than one link; (2) the principle of Palmer et al. of achieving fractional cancer cell killing via multiple drugs with independent mechanisms of action; (3) the principle of shaping versus decisive operations, both being required for successful cancer treatment; (4) an idea adapted from Chow et al., of using multiple cytotoxic medicines at low doses; (5) the idea behind CUSP9v3, using many non-oncology CNS-penetrant drugs from general medical practice, repurposed to block tumor survival paths; (6) the concept from chess that every move creates weaknesses and strengths; (7) the principle of mass-by adding force to a given effort, the chances of achieving the goal increase; and (8) the principle of blocking parallel signaling pathways. Part two gives an example MDACT regimen, gMDACT, which uses six repurposed drugs-celecoxib, dapsone, disulfiram, itraconazole, pyrimethamine, and telmisartan-to interfere with growth-driving elements common to cholangiocarcinoma, colon adenocarcinoma, glioblastoma, and non-small-cell lung cancer. gMDACT is another example of-not a replacement for-previous multidrug regimens already in clinical use, such as CUSP9v3. MDACT regimens are designed as adjuvants to be used with cytotoxic drugs.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

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.

Inhibition of carbonic anhydrases IX/XII by SLC-0111 boosts cisplatin effects in hampering head and neck squamous carcinoma cell growth and invasion

Background

Hypoxic tumor microenvironment (TME) contributes to the onset of many aspects of the cancer biology associated to the resistance to conventional therapies. Hypoxia is a common characteristic and negative prognostic factor in the head and neck squamous carcinomas (HNSCC) and is correlated with aggressive and invasive phenotype as well as with failure to chemo- and radio-therapies. The carbonic anhydrase isoenzymes IX and XII (CA IX/XII), regulators of extra and intracellular pH, are overexpressed in TME and are involved in adaptative changes occurring in cancer cells to survive at low O₂. In this study, we aim to investigate in HNSCC cells and murine models the possibility to target CA IX/XII by the specific inhibitor SLC-0111 to potentiate the effects of cisplatin in hampering cell growth, migration and invasion. Furthermore, we analyzed the signal pathways cooperating in acquisition of a more aggressive phenotype including stemness, epithelial-mesenchymal transition and apoptotic markers.

Methods

The effects of cisplatin, CA IX/XII specific inhibitor SLC-0111, and the combinatorial treatment were tested on proliferation, migration, invasion of HNSCC cells grown in 2D and 3D models. Main signal pathways and the expression of stemness, mesenchymal and apoptotic markers were analyzed by western blotting. Molecular imaging using NIR-Annexin V and NIR-Prosense was performed in HNSCC xenografts to detect tumor growth and metastatic spread.

Results

HNSCC cells grown in 2D and 3D models under hypoxic conditions showed increased levels of CA IX/XII and greater resistance to cisplatin than cells grown under normoxic conditions. The addition of CA IX/XII inhibitor SLC-0111 to cisplatin sensitized HNSCC cells to the chemotherapeutic agent and caused a reduction of proliferation, migration and invasiveness. Furthermore, the combination therapy hampered activation of STAT3, AKT, ERK, and EMT program, whereas it induced apoptosis. In HNSCC xenografts the treatment with cisplatin plus SLC-0111 caused an inhibition of tumor growth and an induction of apoptosis as well as a reduction of metastatic spread at a higher extent than single agents.

Conclusion

Our results highlight the ability of SLC-0111 to sensitize HNSCC to cisplatin by hindering hypoxia-induced signaling network that are shared among mechanisms involved in therapy resistance and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02345-x.

Intracellular pH-mediated induction of apoptosis in HeLa cells by a sulfonamide carbonic anhydrase inhibitor

Carbonic anhydrase IX (CAIX) is a hypoxia-associated transmembrane protein that is critical in the survival of cells. Because CAIX has a key role in pH regulation, its therapeutic effects have been heavily studied by different research laboratories. This study aims to investigate how a synthetic CAIX inhibitor triggers apoptosis in a cancer cell line, HeLa. In this regard, we investigated the effects of the compound I, synthesized as a CAIX inhibitor, on the survival of cancer cells. The compound I inhibited the proliferation of the CAIX+ HeLa cells, kept the cells in G0/G1 phase (74.7%) and altered the cells morphologies (AO/EtBr staining) and the nuclear structure (γ-H2AX staining). CAIX inhibition triggered apoptosis in HeLa cells with a rate of 47.4%. According to the expression of mediator genes (CASP-3, -8, -9, BAX, BCL-2, BECLIN, LC3), the both death pathways were activated in HeLa cells with the inhibition of CAIX with the compound I. The compound I was also determined to affect the genes and proteins that have a critical role in the regulation of apoptotic pathways (pro casp-3, cleaved casp-3, -8, -9, cleaved PARP and CAIX). Furthermore, CAIX inhibition caused changes in pH balance, disruption in organelle integrity of mitochondria, and increase intracellular reactive oxygen level of HeLa cells. Taken together, our findings suggest that CAIX inhibition has a potential in cancer treatment, and the compound I, a CAIX inhibitor, could be a promising therapeutic strategy in the treatment of aggressive tumours.

Extracellular Vesicles as Mediators of Therapy Resistance in the Breast Cancer Microenvironment

Resistance to various therapies, including novel immunotherapies, poses a major challenge in the management of breast cancer and is the leading cause of treatment failure. Bidirectional communication between breast cancer cells and the tumour microenvironment is now known to be an important contributor to therapy resistance. Several studies have demonstrated that crosstalk with the tumour microenvironment through extracellular vesicles is an important mechanism employed by cancer cells that leads to drug resistance via changes in protein, lipid and nucleic acid cargoes. Moreover, the cargo content enables extracellular vesicles to be used as effective biomarkers for predicting response to treatments and as potential therapeutic targets. This review summarises the literature to date regarding the role of extracellular vesicles in promoting therapy resistance in breast cancer through communication with the tumour microenvironment.

Zinc enzymes in medicinal chemistry

In humans, more than three hundred diverse enzymes that require zinc as an essential cofactor have been identified. These zinc enzymes have demonstrated different and important physiological functions and some of them have been considered as valuable therapeutic targets for drug discovery. Indeed, many drugs targeting a few zinc enzymes have been marketed to treat a variety of diseases. This review discusses drug discovery and drug development based on a dozen of zinc enzymes, including their biological functions and pathogenic roles, their best in class inhibitors (and clinical trial data when available), coordination and binding modes of representative inhibitors, and their implications for further drug design. The opportunities and challenges in developing zinc enzyme inhibitors for the treatment of human disorders are highlighted, too.

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.

Therapeutic targeting of the hypoxic tumour microenvironment

Hypoxia is prevalent in human tumours and contributes to microenvironments that shape cancer evolution and adversely affect therapeutic outcomes. Historically, two different tumour microenvironment (TME) research communities have been discernible. One has focused on physicochemical gradients of oxygen, pH and nutrients in the tumour interstitium, motivated in part by the barrier that hypoxia poses to effective radiotherapy. The other has focused on cellular interactions involving tumour and non-tumour cells within the TME. Over the past decade, strong links have been established between these two themes, providing new insights into fundamental aspects of tumour biology and presenting new strategies for addressing the effects of hypoxia and other microenvironmental features that arise from the inefficient microvascular system in solid tumours. This Review provides a perspective on advances at the interface between these two aspects of the TME, with a focus on translational therapeutic opportunities relating to the elimination and/or exploitation of tumour hypoxia.

Pharmacological inhibition of Carbonic Anhydrase IX and XII to enhance targeting of acute myeloid leukaemia cells under hypoxic conditions

Acute myeloid leukaemia (AML) is an aggressive form of blood cancer that carries a dismal prognosis. Several studies suggest that the poor outcome is due to a small fraction of leukaemic cells that elude treatment and survive in specialised, oxygen (O₂)‐deprived niches of the bone marrow. Although several AML drug targets such as FLT3, IDH1/2 and CD33 have been established in recent years, survival rates remain unsatisfactory, which indicates that other, yet unrecognized, mechanisms influence the ability of AML cells to escape cell death and to proliferate in hypoxic environments. Our data illustrates that Carbonic Anhydrases IX and XII (CA IX/XII) are critical for leukaemic cell survival in the O₂‐deprived milieu. CA IX and XII function as transmembrane proteins that mediate intracellular pH under low O₂ conditions. Because maintaining a neutral pH represents a key survival mechanism for tumour cells in O₂‐deprived settings, we sought to elucidate the role of dual CA IX/XII inhibition as a novel strategy to eliminate AML cells under hypoxic conditions. Our findings demonstrate that the dual CA IX/XII inhibitor FC531 may prove to be of value as an adjunct to chemotherapy for the treatment of AML.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

Betulin Sulfonamides as Carbonic Anhydrase Inhibitors and Anticancer Agents in Breast Cancer Cells

Hypoxia-regulated protein carbonic anhydrase IX (CA IX) is up-regulated in different tumor entities and correlated with poor prognosis in breast cancer patients. Due to the radio- and chemotherapy resistance of solid hypoxic tumors, derivatives of betulinic acid (BA), a natural compound with anticancer properties, seem to be promising to benefit these cancer patients. We synthesized new betulin sulfonamides and determined their cytotoxicity in different breast cancer cell lines. Additionally, we investigated their effects on clonogenic survival, cell death, extracellular pH, HIF-1α, CA IX and CA XII protein levels and radiosensitivity. Our study revealed that cytotoxicity increased after treatment with the betulin sulfonamides compared to BA or their precursors, especially in triple-negative breast cancer (TNBC) cells. CA IX activity as well as CA IX and CA XII protein levels were reduced by the betulin sulfonamides. We observed elevated inhibitory efficiency against protumorigenic processes such as proliferation and clonogenic survival and the promotion of cell death and radiosensitivity compared to the precursor derivatives. In particular, TNBC cells showed benefit from the addition of sulfonamides onto BA and revealed that betulin sulfonamides are promising compounds to treat more aggressive breast cancers, or are at the same level against less aggressive breast cancer cells.

Design, synthesis and biochemical evaluation of novel carbonic anhydrase inhibitors triggered by structural knowledge on hCA VII

To tackle the challenge of isoform selectivity, we explored the entrance of the cavity for selected druggable human Carbonic Anhydrases (hCAs). Based on X-ray crystallographic studies on the 4-(4-(2-chlorobenzoyl)piperazine-1-carbonyl)benzenesulfonamide in complex with the brain expressed hCA VII (PDB code: 7NC4), a series of 4-(4(hetero)aroylpiperazine-1-carbonyl)benzene-1-sulfonamides has been developed. To evaluate their capability to fit the hCA VII catalytic cavity, the newer benzenesulfonamides were preliminary investigated by means of docking simulations. Then, this series of thirteen benzenesulfonamides was synthesized and tested against selected druggable hCAs. Among them, the 4-(4-(furan-2-carbonyl)piperazine-1-carbonyl)benzenesulfonamide showed remarkable affinity towards hCA VII (Ki: 4.3 nM) and good selectivity over the physiologically widespread hCA I when compared to Topiramate (TPM).

Identification of non-classical hCA XII inhibitors using combination of computational approaches for drug design and discovery

Human carbonic anhydrase XII (hCA XII) isozyme is of high therapeutic value as a pharmacological target and biomarker for different types of cancer. The hCA XII is one of the crucial effectors that regulates extracellular and intracellular pH and affects cancer cell proliferation, invasion, growth and metastasis. Despite the fact that interaction features of hCAs inhibitors with the catalytic site of the enzyme are well described, lack in the selectivity of the traditional hCA inhibitors based on the sulfonamide group or related motifs is an urgent issue. Moreover, drugs containing sulfanomides can cause sulfa allergies. Thus, identification of novel non-classical inhibitors of hCA XII is of high priority and is currently the subject of a vast field of study. This study was devoted to the identification of novel potential hCA XII inhibitors using comprehensive set of computational approaches for drug design discovery: generation and validation of structure- and ligand-based pharmacophore models, molecular docking, re-scoring of virtual screening results with MMGBSA, molecular dynamics simulations, etc. As the results of the study several compounds with alternative to classical inhibitors chemical scaffolds, in particular one of coumarins derivative, have been identified and are of high interest as potential non-classical hCA XII inhibitors.

Breast cancer fibroblasts and cross-talk

The breast tumor microenvironment is one of the crucial elements supporting breast cancer tumor progression and metastasis. The fibroblasts are the chief cellular component of the stromal microenvironment and are pathologically activated and differentiated into breast cancer-associated fibroblasts (CAFs). The catabolic phenotype of breast CAFs arises due to metabolic reprogramming of these fibroblasts under pseudo-hypoxic conditions. The metabolic intermediates and ATP produced by the breast CAFs are exploited by the neighboring cancer cells for energy generation. The growth factors, cytokines, and chemokines secreted by the CAFs help fuel tumor growth, invasion, and dissemination. Moreover, the interplay between breast CAFs and cancer cells, mediated by the growth factors, ROS, metabolic intermediates, exosomes, and catabolite transporters, aids in building a favorable microenvironment that promotes cancer cell proliferation, tumor progression, and metastasis. Therefore, identifying effective means to target the reprogrammed metabolism of the breast CAFs and the cross-communication between CAFs and cancer cells serve as promising strategies to develop anti-cancer therapeutics. Henceforth, the scope of the present review ranges from discussing the underlying characteristics of breast CAFs, mechanisms of metabolic reprogramming in breast CAFs, and the nature of interactions between breast CAFs and cancer cells to studying the intricacies of reprogrammed metabolism targeted cancer therapy.

The Carbonic Anhydrase Inhibitor E7070 Sensitizes Glioblastoma Cells to Radio- and Chemotherapy and Reduces Tumor Growth

Glioblastomas (GBMs), the most common and lethal primary brain tumor, show inherent infiltrative nature and high molecular heterogeneity that make complete surgical resection unfeasible and unresponsive to conventional adjuvant therapy. Due to their fast growth rate even under hypoxic and acidic conditions, GBM cells can conserve the intracellular pH at physiological range by overexpressing membrane-bound carbonic anhydrases (CAs). The synthetic sulfonamide E7070 is a potent inhibitor of CAs that harbors putative anticancer properties; however, this drug has still not been tested in GBMs. The present study aimed to evaluate the effects of E7070 on CA9 and CA12 enzymes in GBM cells as well as in the tumor cell growth, migration, invasion, and resistance to radiotherapy and chemotherapy. We found that E7070 treatment significantly reduced tumor cell growth and increased radio- and chemotherapy efficacy against GBM cells under hypoxia. Our data suggests that E7070 has therapeutic potential as a radio-chemo-sensitizing in drug-resistant GBMs, representing an attractive strategy to improve the adjuvant therapy. We showed that CA9 and CA12 represent potentially valuable therapeutic targets that should be further investigated as useful diagnostic and prognostic biomarkers for GBM tailored therapy.

Altered glycolysis results in drug-resistant in clinical tumor therapy

Cancer cells undergo metabolic reprogramming, including increased glucose metabolism, fatty acid synthesis and glutamine metabolic rates. These enhancements to three major metabolic pathways are closely associated with glycolysis, which is considered the central component of cancer cell metabolism. Increasing evidence suggests that dysfunctional glycolysis is commonly associated with drug resistance in cancer treatment, and aberrant glycolysis plays a significant role in drug-resistant cancer cells. Studies on the development of drugs targeting these abnormalities have led to improvements in the efficacy of tumor treatment. The present review discusses the changes in glycolysis targets that cause drug resistance in cancer cells, including hexokinase, pyruvate kinase, pyruvate dehydrogenase complex, glucose transporters, and lactate, as well the underlying molecular mechanisms and corresponding novel therapeutic strategies. In addition, the association between increased oxidative phosphorylation and drug resistance is introduced, which is caused by metabolic plasticity. Given that aberrant glycolysis has been identified as a common metabolic feature of drug-resistant tumor cells, targeting glycolysis may be a novel strategy to develop new drugs to benefit patients with drug-resistance.

Benzyl alcohol inhibits carbonic anhydrases by anchoring to the zinc coordinated water molecule

Up to date alcohols have been scarcely investigated as carbonic anhydrase (CA) inhibitors. To get more insights into the CA inhibition properties of this class of molecules, in this paper, by means of inhibition assays and X-ray crystallographic studies we report a detailed characterization of the CA inhibition properties and the binding mode to human CA II of benzyl alcohol. Results show that, although possessing a very simple scaffold, this molecule acts as a micromolar CA II inhibitor, which anchors to the enzyme active site by means of an H-bond interaction with the zinc bound solvent molecule. Taken together our results clearly indicate primary alcohols as a class of CA inhibitors that deserve to be more investigated.

Inhibition of Carbonic Anhydrase Using SLC-149: Support for a Noncatalytic Function of CAIX in Breast Cancer

Carbonic anhydrase IX (CAIX) is considered a target for therapeutic intervention in solid tumors. In this study, the efficacy of the inhibitor, 4-(3-(2,4-difluorophenyl)-oxoimidazolidin-1-yl)benzenesulfonamide (SLC-149), is evaluated on CAIX and a CAIX-mimic. We show that SLC-149 is a better inhibitor than acetazolamide against CAIX. Binding of SLC-149 thermally stabilizes CAIX-mimic at lower concentrations compared to that of CAII. Structural examinations of SLC-149 bound to CAIX-mimic and CAII explain binding preferences. In cell culture, SLC-149 is a more effective inhibitor of CAIX activity in a triple-negative breast cancer cell line than previously studied sulfonamide inhibitors. SLC-149 is also a better inhibitor of activity in cells expressing CAIX versus CAXII. However, SLC-149 has little effect on cytotoxicity, and high concentrations are required to inhibit cell growth, migration, and invasion. These data support the hypothesis that CAIX activity, shown to be important in regulating extracellular pH, does not underlie its ability to control cell growth.

Synthesis, computational studies and assessment of in vitro inhibitory activity of umbelliferon-based compounds against tumour-associated carbonic anhydrase isoforms IX and XII

Coumarins are widely diffused secondary metabolites possessing a plethora of biological activities. It has been established that coumarins represent a peculiar class of human carbonic anhydrase (hCA) inhibitors having a distinct mechanism of action involving a non-classical binding with amino acid residues paving the entrance of hCA catalytic site. Herein, we report the synthesis of a small series of new coumarin derivatives 7-11, 15, 17 prepared via classical Pechmann condensation starting from resorcinol derivatives and suitable β-ketoesters. The evaluation of inhibitory activity revealed that these compounds possessed nanomolar affinity and high selectivity towards tumour-associated hCA IX and XII over cytosolic hCA I and hCA II isoforms. To investigate the binding mode of these new coumarin-inspired inhibitors, the most active compounds 10 and 17 were docked within hCA XII catalytic cleft.

Hypoxia and its therapeutic possibilities in paediatric cancers

In tumours, hypoxia-a condition in which the demand for oxygen is higher than its availability-is well known to be associated with reduced sensitivity to radiotherapy and chemotherapy, and with immunosuppression. The consequences of hypoxia on tumour biology and patient outcomes have therefore led to the investigation of strategies that can alleviate hypoxia in cancer cells, with the aim of sensitising cells to treatments. An alternative therapeutic approach involves the design of prodrugs that are activated by hypoxic cells. Increasing evidence indicates that hypoxia is not just clinically significant in adult cancers but also in paediatric cancers. We evaluate relevant methods to assess the levels and extent of hypoxia in childhood cancers, including novel imaging strategies such as oxygen-enhanced magnetic resonance imaging (MRI). Preclinical and clinical evidence largely supports the use of hypoxia-targeting drugs in children, and we describe the critical need to identify robust predictive biomarkers for the use of such drugs in future paediatric clinical trials. Ultimately, a more personalised approach to treatment that includes targeting hypoxic tumour cells might improve outcomes in subgroups of paediatric cancer patients.

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.

Design, synthesis and mechanistic study of new benzenesulfonamide derivatives as anticancer and antimicrobial agents via carbonic anhydrase IX inhibition

Changes in gene expression cause uncontrolled cell proliferation and consequently tumor hypoxia. The tumor cells shift their metabolism to anaerobic glycolysis with a significant modification in pH. Therefore, an over expression of carbonic anhydrase IX (CA IX) genes was detected in many solid tumors. Accordingly, selective inhibition of CA IX can be a useful target for discovering novel antiproliferative agents. The present study described the synthesis of new aryl thiazolone–benzenesulfonamides 4a–j as well as their carbonic anhydrase IX inhibitory effect. All the designed derivatives were evaluated for their anti-proliferative activity against triple-negative breast cancer cell line (as MDA-MB-231) and another breast cancer cell line (MCF-7) in addition to normal breast cell line MCF-10A. Compounds 4b–c, 4e, 4g–h showed significant inhibitory effect against both cancer cell lines at concentration ranges from 1.52–6.31 μM, with a high selectivity against breast cancer cell lines ranges from 5.5 to 17.5 times. Moreover, three sulfonamides derivatives 4e, 4g and 4h showed excellent enzyme inhibition against CA IX with IC₅₀ 10.93–25.06 nM and against CA II with IC₅₀ 1.55–3.92 μM that revealed their remarkable selectivity for CA IX over CA II. Additionally, 4e was able to induce apoptosis in MDA-MB-231 with a significant increase in the annexin V-FITC percent by 22 fold as compared with control. Cellular uptake on MDA-MB-231 cell lines were carried out using HPLC method on the three active compounds (4e, 4g and 4h). On the other hand inhibition of one or more CAs present in bacteria was reported to interfere with bacterial growth. So, the new benzenesulfonamides were evaluated against their antibacterial and anti-biofilm activities. Analogues 4e, 4g and 4h exhibited significant inhibition at 50 μg mL⁻¹ concentration with 80.69%, 69.74% and 68.30% against S. aureus compared to the positive control CIP which was 99.2%, while compounds 4g and 4h showed potential anti-biofilm inhibition 79.46% and 77.52% against K. pneumonia. Furthermore, the designed compounds were docked into CA IX (human) protein (PDB ID: 5FL6) and molecular modeling studies revealed favorable binding interactions for the active inhibitors. Finally, the predictive ADMET studies showed that, compounds 4e, 4g and 4h possessed promising pharmacokinetic properties.

New benzenesulfonamide derivatives as anticancer and antimicrobial agents via CA IX inhibition.

Recent advances in the medicinal chemistry of carbonic anhydrase inhibitors

Carbonic anhydrase (CA, EC 4.2.1.1) is an enzyme and a very omnipresent zinc metalloenzyme which catalyzed the reversible hydration and dehydration of carbon dioxide and bicarbonate; a reaction which plays a crucial role in many physiological and pathological processes. Carbonic anhydrase is present in human (h) with sixteen different isoforms ranging from hCA I-hCA XV. All these isoforms are widely distributed in different tissues/organs and are associated with a range of pivotal physiological activities. Due to their involvement in various physiological roles, inhibitors of different human isoforms of carbonic anhydrase have found clinical applications for the treatment of various diseases including glaucoma, retinopathy, hemolytic anemia, epilepsy, obesity, and cancer. However, clinically used inhibitors of CA (acetazolamide, brinzolamide, dorzolamide, etc.) are not selective causing the undesirable side effects. One of the major hurdles in the design and development of carbonic anhydrase inhibitors is the lack of balanced isoform selectivity which thrived to new chemotypes. In this review, we have compiled the recent strategies of various researchers related to the development of carbonic anhydrase inhibitors belonging to different structural classes like pyrimidine, pyrazoline, selenourea, isatin, indole, etc. This review also summarizes the structure-activity relationships, analysis of isoform selectivity including mechanistic and in silico studies to afford ideas and to provide focused direction for the design and development of novel isoform-selective carbonic anhydrase inhibitors with therapeutic implications.

PET imaging and pharmacological therapy targeting carbonic anhydrase-IX high-expressing tumors using US2 platform based on bivalent ureidosulfonamide

Carbonic anhydrase-IX (CA-IX) is attracting much attention as a target molecule for cancer treatment since high expression of CA-IX can lead to a poor prognosis of patients. We previously reported low-molecular-weight ¹¹¹In/⁹⁰Y complexes with a bivalent ureidosulfonamide scaffold ([¹¹¹In/⁹⁰Y]In/Y-US2) as cancer radiotheranostic agents for single photon emission computed tomography and radionuclide-based therapy targeting CA-IX. Here, we applied the US2 platform to positron emission tomography (PET) imaging and pharmacological therapy targeting CA-IX high-expressing tumors by introducing ⁶⁸Ga and ^natIn, respectively. In an in vitro cell binding assay, [⁶⁷Ga]Ga-US2, an alternative complex of [⁶⁸Ga]Ga-US2 with a longer half-life, markedly bound to CA-IX high-expressing (HT-29) cells compared with low-expressing (MDA-MB-231) cells. In a biodistribution study with HT-29 and MDA-MB-231 tumor-bearing mice, [⁶⁷Ga]Ga-US2 showed accumulation in the HT-29 tumor (3.81% injected dose/g at 60 min postinjection) and clearance from the blood pool with time. PET with [⁶⁸Ga]Ga-US2 clearly visualized the HT-29 tumor in model mice at 60 min postinjection. In addition, the administration of [^natIn]In-US2 to HT-29 tumor-bearing mice led to tumor growth delay and prolonged mouse survival, while no critical toxicity was observed. These results indicate that [⁶⁸Ga]Ga-US2 and [^natIn]In-US2 may be useful imaging and therapeutic agents targeting CA-IX, respectively, and that US2 may serve as an effective cancer theranostic platform utilizing CA-IX.

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

The emergence of tumour recurrence and resistance limits the survival rate for most tumour-bearing patients. Only, combination therapies targeting pathways involved in the induction and in the maintenance of cancer growth and progression might potentially result in an enhanced therapeutic efficacy. Herein, we provided a prospective combination treatment that includes suberoylanilide hydroxamic acid (SAHA), a well-known inhibitor of histone deacetylases (HDACs), and SLC-0111, a novel inhibitor of carbonic anhydrase (CA) IX. We proved that HDAC inhibition with SAHA in combination with SLC-0111 affects cell viability and colony forming capability to greater extent than either treatment alone of breast, colorectal and melanoma cancer cells. At the molecular level, this therapeutic regimen resulted in a synergistically increase of histone H4 and p53 acetylation in all tested cell lines. Overall, our findings showed that SAHA and SLC-0111 can be regarded as very attractive combination providing a potential therapeutic strategy against different cancer models.

A Novel Inhibitor of Carbonic Anhydrases Prevents Hypoxia-Induced TNBC Cell Plasticity

Cell plasticity is the ability that cells have to modify their phenotype, adapting to the environment. Cancer progression is under the strict control of the the tumor microenvironment that strongly determines its success by regulating the behavioral changes of tumor cells. The cross-talk between cancer and stromal cells and the interactions with the extracellular matrix, hypoxia and acidosis contribute to trigger a new tumor cell identity and to enhance tumor heterogeneity and metastatic spread. In highly aggressive triple-negative breast cancer, tumor cells show a significant capability to change their phenotype under the pressure of the hypoxic microenvironment. In this study, we investigated whether targeting the hypoxia-induced protein carbonic anhydrase IX (CA IX) could reduce triple-negative breast cancer (TNBC) cell phenotypic switching involved in processes associated with poor prognosis such as vascular mimicry (VM) and cancer stem cells (CSCs). The treatment of two TNBC cell lines (BT-549 and MDA-MB-231) with a specific CA IX siRNA or with a novel inhibitor of carbonic anhydrases (RC44) severely impaired their ability to form a vascular-like network and mammospheres and reduced their metastatic potential. In addition, the RC44 inhibitor was able to hamper the signal pathways involved in triggering VM and CSC formation. These results demonstrate that targeting hypoxia-induced cell plasticity through CA IX inhibition could be a new opportunity to selectively reduce VM and CSCs, thus improving the efficiency of existing therapies in TNBC.

Bad neighbours: hypoxia and genomic instability in prostate cancer

Prostate cancer (PCa) is a clinically heterogeneous disease and has poor patient outcome when tumours progress to castration-resistant and metastatic states. Understanding the mechanistic basis for transition to late stage aggressive disease is vital for both assigning patient risk status in the localised setting and also identifying novel treatment strategies to prevent progression. Subregions of intratumoral hypoxia are found in all solid tumours and are associated with many biologic drivers of tumour progression. Crucially, more recent findings show the co-presence of hypoxia and genomic instability can confer a uniquely adverse prognosis in localised PCa patients. In-depth informatic and functional studies suggests a role for hypoxia in co-operating with oncogenic drivers (e.g. loss of PTEN) and suppressing DNA repair capacity to alter clonal evolution due to an aggressive mutator phenotype. More specifically, hypoxic suppression of homologous recombination represents a “contextual lethal“ vulnerability in hypoxic prostate tumours which could extend the application of existing DNA repair targeting agents such as poly-ADP ribose polymerase inhibitors. Further investigation is now required to assess this relationship on the background of existing genomic alterations relevant to PCa, and also characterise the role of hypoxia in driving early metastatic spread. On this basis, PCa patients with hypoxic tumours can be better stratified into risk categories and treated with appropriate therapies to prevent progression.