Carbonic anhydrase IX reduces E-cadherin-mediated adhesion of MDCK cells via interaction with beta-catenin

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.

The relationship between carbonic anhydrase IX (CAIX) and patient survival in breast cancer: systematic review and meta-analysis

PURPOSE

Hypoxia is a characteristic of many solid tumours and an adverse prognostic factor for cancer therapy. Hypoxia results in upregulation of carbonic anhydrase IX (CAIX) expression, a pH-regulating enzyme. Many human tissue studies have examined the prognostic value of CAIX expression in breast cancer but have yielded inconsistent results. Therefore, a systematic review and meta-analysis was undertaken to assess the prognostic value of CAIX expression for breast cancer patients.

METHODS

The electronic databases were systematically searched to identify relevant papers. The clinical outcomes included disease-free survival (DFS), recurrence-free survival (RFS) and overall survival (OS) in breast cancer patients. Review Manager version 5.4 was employed to analysis data from 23 eligible studies (containing 8390 patients).

RESULTS

High CAIX expression was associated with poorer RFS [HR = 1.42, 95% CI (1.32-1.51), p < 0.00001], DFS [HR = 1.64, 95% CI (1.34-2.00), p < 0.00001], and OS [HR = 1.48, 95% CI (1.22-1.80), p < 0.0001]. Heterogeneity was observed across the studies. There was an effect of the CAIX antibody employed, scoring methods, and tumour localisation on CAIX expression.

CONCLUSION

CAIX overexpression was significantly associated with poorer RFS, DFS, and OS in breast cancer patients. However, further work in high quantity tissue cohorts is required to define the optimal methodological approach.

Differential CMS-Related Expression of Cell Surface Carbonic Anhydrases IX and XII in Colorectal Cancer Models-Implications for Therapy

Tumor-associated carbonic anhydrases IX (CAIX) and XII (CAXII) have long been in the spotlight as potential new targets for anti-cancer therapy. Recently, CAIX/CAXII specific inhibitor SLC-0111 has passed clinical phase I study and showed differential response among patients with colorectal cancer (CRC). CRC can be classified into four different consensus molecular subgroups (CMS) showing unique expression patterns and molecular traits. We questioned whether there is a CMS-related CAIX/CAXII expression pattern in CRC predicting response. As such, we analyzed transcriptomic data of tumor samples for CA9/CA12 expression using Cancertool. Protein expression pattern was examined in preclinical models comprising cell lines, spheroids and xenograft tumors representing the CMS groups. Impact of CAIX/CAXII knockdown and SLC-0111 treatment was investigated in 2D and 3D cell culture. The transcriptomic data revealed a characteristic CMS-related CA9/CA12 expression pattern with pronounced co-expression of both CAs as a typical feature of CMS3 tumors. Protein expression in spheroid- and xenograft tumor tissue clearly differed, ranging from close to none (CMS1) to strong CAIX/CAXII co-expression in CMS3 models (HT29, LS174T). Accordingly, response to SLC-0111 analyzed in the spheroid model ranged from no (CMS1) to clear (CMS3), with moderate in CMS2 and mixed in CMS4. Furthermore, SLC-0111 positively affected impact of single and combined chemotherapeutic treatment of CMS3 spheroids. In addition, combined CAIX/CAXII knockdown and more effective treatment with SLC-0111 reduced clonogenic survival of CMS3 modelling single cells. In conclusion, the preclinical data support the clinical approach of targeted CAIX/CAXII inhibition by showing linkage of expression with response and suggest that patients with CMS3-classified tumors would most benefit from such treatment.

Carbonic anhydrase IX-related tumoral hypoxia predicts worse prognosis in breast cancer: A systematic review and meta-analysis

Background

Tumoral hypoxia is associated with aggressiveness in many cancers including breast cancer. However, measuring hypoxia is complicated. Carbonic anhydrase IX (CAIX) is a reliable endogenous marker of hypoxia under the control of the master regulator hypoxia-inducible factor-1α (HIF-1α). The expression of CAIX is associated with poor prognosis in many solid malignancies; however, its role in breast cancer remains controversial.

Methods

The present study performed a meta-analysis to evaluate the correlation between CAIX expression and disease-free survival (DFS) and overall survival (OS) in breast cancer.

Results

A total of 2,120 publications from EMBASE, PubMed, Cochrane, and Scopus were screened. Of these 2,120 publications, 272 full texts were reviewed, and 27 articles were included in the meta-analysis. High CAIX was significantly associated with poor DFS (HR = 1.70, 95% CI = 1.39–2.07, p &lt; 0.00001) and OS (HR = 2.02, 95% CI 1.40–2.91, p = 0.0002) in patients with breast cancer. When stratified by subtype, the high CAIX group was clearly associated with shorter DFS (HR = 2.09, 95% CI =1.11–3.92, p = 0.02) and OS (HR = 2.50, 95% CI =1.53–4.07, p = 0.0002) in TNBC and shorter DFS in ER+ breast cancer (HR = 1.81 95% CI =1.38–2.36, p &lt; 0.0001).

Conclusion

High CAIX expression is a negative prognostic marker of breast cancer regardless of the subtypes.

Carbonic Anhydrase IX in Tumor Tissue and Plasma of Breast Cancer Patients: Reliable Biomarker of Hypoxia and Prognosis

Carbonic anhydrase IX (CA IX) is recognized as an excellent marker of hypoxia and an adverse prognostic factor in solid tumors, including breast cancer (BC). Clinical studies confirm that soluble CA IX (sCA IX), shed into body fluids, predicts the response to some therapeutics. However, CA IX is not included in clinical practice guidelines, possibly due to a lack of validated diagnostic tools. Here, we present two novel diagnostic tools-a monoclonal antibody for CA IX detection by immunohistochemistry and an ELISA kit for the detection of sCA IX in the plasma-validated on a cohort of 100 patients with early BC. We confirm that tissue CA IX positivity (24%) correlates with tumor grading, necrosis, negative hormone receptor status, and the TNBC molecular subtype. We show that antibody IV/18 can specifically detect all subcellular forms of CA IX. Our ELISA test provides 70% sensitivity and 90% specificity. Although we showed that this test could detect exosomes in addition to shed CA IX ectodomain, we could not demonstrate a clear association of sCA IX with prognosis. Our results indicate that the amount of sCA IX depends on subcellular CA IX localization, but more strictly on the molecular composition of individual molecular subtypes of BC, particularly on metalloproteinases inhibitor expression.

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.

Carbonic anhydrase XII as biomarker and therapeutic target in ovarian carcinomas

Targeting the tumor-associated carbonic anhydrase XII (CA XII) is considered a promising strategy to improve cancer treatment. As such progress is highly demanded for ovarian carcinomas, the present study aimed to provide deeper information about their CA XII expression profile. A large collection of tissue specimens was stained immunohistochemically with a specific anti-CA XII antibody to evaluate the expression in neoplastic and non-neoplastic epithelial ovarian cells. In addition, flow cytometry was used to measure CA XII expression on tumor cells from malignant ascites fluid. Binding of the antibody revealed a significant CA XII expression in most ovarian carcinoma tissue samples and ascites-derived ovarian carcinoma cells. Moreover, CA XII was expressed at higher levels in ovarian carcinomas as compared to borderline ovarian tumors and non-neoplastic ovarian epithelia. Within the carcinoma tissues, high expression of CA XII was associated with higher tumor grading and a trend towards shorter overall survival. Our results indicate that CA XII plays a crucial role for the malignancy of ovarian carcinoma cells and emphasize the potential of CA XII as a diagnostic marker and therapeutic target in the management of ovarian carcinomas.

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.

Understanding metabolic alterations and heterogeneity in cancer progression through validated immunodetection of key molecular components: a case of carbonic anhydrase IX

Cancer metabolic heterogeneity develops in response to both intrinsic factors (mutations leading to activation of oncogenic pathways) and extrinsic factors (physiological and molecular signals from the extracellular milieu). Here we review causes and consequences of metabolic alterations in cancer cells with focus on hypoxia and acidosis, and with particular attention to carbonic anhydrase IX (CA IX). CA IX is a cancer-associated enzyme induced and activated by hypoxia in a broad range of tumor types, where it participates in pH regulation as well as in molecular mechanisms supporting cancer cells’ invasion and metastasis. CA IX catalyzes reversible conversion of carbon dioxide to bicarbonate ion plus proton and cooperates with a spectrum of molecules transporting ions or metabolites across the plasma membrane. Thereby CA IX contributes to extracellular acidosis as well as to buffering intracellular pH, which is essential for cell survival, metabolic performance, and proliferation of cancer cells. Since CA IX expression pattern reflects gradients of oxygen, pH, and other intratumoral factors, we use it as a paradigm to discuss an impact of antibody quality and research material on investigating metabolic reprogramming of tumor tissue. Based on the validation, we propose the most reliable CA IX-specific antibodies and suggest conditions for faithful immunohistochemical analysis of molecules contributing to heterogeneity in cancer progression.

Hypoxia Marker Carbonic Anhydrase IX Is Present in Abdominal Aortic Aneurysm Tissue and Plasma

Abdominal aortic aneurysms (AAA) are a significant cause of premature deaths worldwide. Since there is no specific treatment for reducing AAA progression, it is crucial to understand the pathogenesis leading to aneurysm wall weakening/remodeling and identify new proteins involved in this process which could subsequently serve as novel therapeutic targets. In this study, we analyzed the presence of the hypoxia-related proteins carbonic anhydrase IX (CA IX), hypoxia-inducible factor 1α (HIF-1α), and AKT as the key molecule in the phosphoinositide-3-kinase pathway in the AAA wall. Additionally, we used a blood-based assay to examine soluble CA IX (s-CA IX) levels in the plasma of AAA patients. Using western blotting, we detected CA IX protein in 12 out of 15 AAA tissue samples. Immunohistochemistry staining proved CA IX expression in the media of the aneurysmal wall. Evaluation of phosphorylated (p-AKT) and total AKT showed elevated levels of both forms in AAA compared to normal aorta. Using ELISA, we determined the concentration of s-CA IX >20 pg/mL in 13 out of 15 AAA patients. Results obtained from in silico analysis of CA9 and aneurysm-associated genes suggest a role for CA IX in aneurysmal wall remodeling. Our results prove the presence of hypoxia-related CA IX in AAA tissues and indicate a possible role of CA IX in hypoxia-associated cardiovascular diseases.

Dual roles of AMAP1 in the transcriptional regulation and intracellular trafficking of carbonic anhydrase IX

BACKGROUND

The cell-surface enzyme carbonic anhydrase IX (CAIX/CA9) promotes tumor growth, survival, invasion, and metastasis, mainly via its pH-regulating functions. Owing to its tumor-specific expression, CAIX-targeting antibodies/chemicals are utilized for therapeutic and diagnostic purposes. However, mechanisms of CAIX trafficking, which affects such CAIX-targeting modalities remain unclear. In this study, roles of the AMAP1-PRKD2 pathway, which mediates integrin recycling of invasive cancer cells, in CAIX trafficking were investigated.

METHODS

Using highly invasive MDA-MB-231 breast cancer cells, the physical association and colocalization of endogenous proteins were analyzed by immunoprecipitation and immunofluorescence, protein/mRNA levels were quantified by western blotting/qPCR, and cell-surface transport and intracellular/extracellular pH regulation were measured by biotin-labeling and fluorescent dye-based assays, respectively. The correlation between mRNA levels and patients' prognoses was analyzed using a TCGA breast cancer dataset.

RESULTS

AMAP1 associated with the CAIX protein complex, and they colocalized at the plasma membrane and tubulovesicular structures. AMAP1 knockdown reduced total/surface CAIX, induced its lysosomal accumulation and degradation, and affected intracellular/extracellular pH. PRKD2 knockdown excluded AMAP1 from the CAIX complex and reduced total CAIX in a lysosome-dependent manner. Unexpectedly, AMAP1 knockdown also reduced CAIX mRNA. AMAP1 interacted with PIAS3, which stabilizes HIF-1α, a transcriptional regulator of CA9. AMAP1 knockdown inhibited the PIAS3-HIF-1α interaction and destabilized the HIF-1α protein. High-ASAP1 (AMAP1-encoding gene) together with high-PIAS3 correlated with high-CA9 and an unfavorable prognosis in breast cancer.

CONCLUSION

The AMAP1-PRKD2 pathway regulates CAIX trafficking, and modulates its total/surface expression. The AMAP1-PIAS3 interaction augments CA9 transcription by stabilizing HIF-1α, presumably contributing to an unfavorable prognosis.

Aromatic Sulfonamides including a Sulfonic Acid Tail: New Membrane Impermeant Carbonic Anhydrase Inhibitors for Targeting Selectively the Cancer-Associated Isoforms

We report here a new drug design strategy for producing membrane-impermeant carbonic anhydrase (CA; EC 4.2.1.1) inhibitors selectively targeting the tumor-associated, membrane-bound human CAs IX and XII over off-target cytosolic isoforms. To date, this approach has only been pursued by including permanent positively charged pyridinium type or highly hydrophilic glycosidic moieties into the structure of aromatic sulfonamide CA inhibitors (CAIs). Aliphatic (propyl and butyl) sulfonic acid tails, deprotonated at physiological pH, were thus incorporated onto a benzenesulfonamide scaffold by a common 1,2,3-triazole linker and different types of spacers. Twenty such derivatives were synthesized and tested for their inhibition of target (hCAs IV, IX, and XII) and off-target CAs (hCAs I and II). Most sulfonate CAIs induced a potent inhibition of hCAs II, IX, and XII up to a low nanomolar K_I range (0.9–459.4 nM) with a limited target/off-target CA selectivity of action. According to the drug design schedule, a subset of representative derivatives was assessed for their cell membrane permeability using Caco-2 cells and a developed FIA-MS/MS method. The complete membrane impermeability of the sulfonate tailed CAIs (≥98%) validated these negatively charged moieties as being suitable for achieving, in vivo, the selective targeting of the tumor-associated CAs over off-target ones.

Docking studies and molecular dynamics simulation of triazole benzene sulfonamide derivatives with human carbonic anhydrase IX inhibition activity

Carbonic anhydrase IX has been used as a hypoxia endogenous marker in a range of solid tumors including renal cell, lung, bladder and tumors of the head and neck. α-CA IX isozyme is over-expressive in hypoxic environment which becomes an attractive target for the design of inhibitors' targeting cancer particularly, tumor progression and invasion. In the process of designing new leads for the inhibition of tumor-associated hCA IX, the best triazole benzene sulfonamide derivatives were obtained from the QSAR model published in the research paper as cited. The statistically validated QSAR model was utilized for bioactivity prediction of novel leads. Further the designed molecules having good scores were subjected to molecular docking studies and molecular dynamic simulation studies. Designed compounds 1, 2, 20, 24 and 27 have shown predicted bioactivity of 9.13, 9.65, 10.05, 10.03 and 10.104 logarithmic units respectively using QSAR model 2. The low energy conformations of the above compounds exhibited good Autodock binding energy scores (-8.1, -8.2, -8.1, -8.3 and -9.2 K cal mol-1) and interactions with Gln92, Thr200, Asn66 and His68. Desmond's molecular dynamics simulations studies for 100 ns of compound 27 compared to reference SLC0111 provided useful structural insights of human carbonic anhydrase IX inhibition. Compound 27 with new chemical structure displayed both hydrophobic and hydrophilic stable interactions in the active site. RMSD, RMSF, RoG, H-bond and SASA analysis confirmed the stable binding of compound 27 with 5FL4 structure. In addition, MM-PBSA and MM-GBSA also affirm the docking results. We propose the designed compound 27 (predicted Ki = ∼0.07 nM) as the best theoretical lead which may further be experimentally studied for selective inhibition.

Inhibition of Carbonic Anhydrase IX Suppresses Breast Cancer Cell Motility at the Single-Cell Level

Protein Carbonic Anhydrase IX (CA IX), which is expressed in various hypoxic solid tumors in order to maintain proper pH, is also related to cancer cell adhesion, invasion, and metastasis processes. Here, we investigated whether CA IX inhibition by a highly CA IX selective agent benzenesulfonamide VD11-4-2 triggers changes in individual cell motility. We seeded breast cancer cells on an extracellular matrix-coated glass-bottomed dish and in a microfluidic device with a gradient flow of epidermal growth factor (EGF), tracked individual cell movement, calculated their migration speeds, and/or followed movement direction. Our results showed that the inhibitor VD11-4-2 decreased the speed of CA IX positive breast cancer cells by 20-26% while not affecting non-cancerous cell migration. The inhibitor suppressed the cell migration velocity increment and hindered cells from reaching their maximum speed. VD11-4-2 also reduced CA IX, expressing cell movement towards the growth factor as a chemoattractant. Such a single cell-based migration assay enabled the comprehensive investigation of the cell motility and revealed that VD11-4-2 shows the ability to suppress breast cancer cell migration at a lower concentration than previously tested CA IX inhibitors.

Carbonic Anhydrase IX and Survivin in Colorectal Adenocarcinoma Cells: Slovakian Population Study

Simple Summary

This retrospective study (Slovakian population study) brings information about immunohistochemical detection of CAIX and survivin in 74 samples of human colorectal adenocarcinoma and comparison their expression with expression in healthy colon tissue. Our results show that all of samples with healthy colon tissue were CAIX and survivin-negative and there is no statistically significant dependence of these proteins and the chosen clinicopathological parameters. These findings demonstrate that detection of these proteins could be useful for tumor diagnostic and prognostic and CAIX and survivin could represent independent negative prognostic markers of colorectal cancer.

Abstract

The aim of this study was to detect carbonic anhydrase IX (CAIX) and survivin in the colorectal adenocarcinoma cells of the Slovakian population. We used an indirect three-step immunohistochemical method with DAB staining for the localization of the proteins and investigation their expression. We compared their expression with expression in healthy colorectal tissue. In 74 tissues of colorectal adenocarcinomas, 42% showed CAIX positivity and 20% showed survivin positivity. Brown membrane immunostaining was visible in CAIX-positive tumors. Survivin-positive tumors had strong brown cytoplasmic immunostaining. Co-expression of both proteins was present in five specimens (7%). The samples of normal colorectal tissue (without carcinoma) were CAIX-negative and survivin-negative. We also applied the Chi-squared test for evaluation statistically significant association between the expression of proteins and selected clinical and histopathological parameters. We did not find any statistically significant correlations between CAIX or survivin expression and sex of patients, the grade of the tumor, nodal status and presence of metastasis (p > 0.05). The fact that all samples of normal colorectal tissue were CAIX- and survivin-negative could lead to the possibility of using these two proteins as potential tumor diagnostic markers. On the basic of the available publications and data, we suggest that CAIX and survivin could be negative independent prognostic markers of colorectal cancer, which could affect response to therapy.

Rigosertib elicits potent anti-tumor responses in colorectal cancer by inhibiting Ras signaling pathway

BACKGROUND

The therapeutic potency of Rigosertib (RGS) in the treatment of the myelodysplastic syndrome has been investigated previously, but little is known about its mechanisms of action.

METHODS

The present study integrates systems and molecular biology approaches to investigate the mechanisms of the anti-tumor effects of RGS, either alone or in combination with 5-FU in cellular and animal models of colorectal cancer (CRC).

RESULTS

The effects of RGS were more pronounced in dedifferentiated CRC cell types, compared to cell types that were epithelial-like. RGS inhibited cell proliferation and cell cycle progression in a cell-type specific manner, and that was dependent on the presence of mutations in KRAS, or its down-stream effectors. RGS increased both early and late apoptosis, by regulating the expression of p53, BAX and MDM2 in tumor model. We also found that RGS induced cell senescence in tumor tissues by increasing ROS generation, and impairing oxidant/anti-oxidant balance. RGS also inhibited angiogenesis and metastatic behavior of CRC cells, by regulating the expression of CD31, E-cadherin, and matrix metalloproteinases-2 and 9.

CONCLUSION

Our findings support the therapeutic potential of this potent RAS signaling inhibitor either alone or in combination with standard regimens for the management of patients with CRC.

Post-translational modifications in tumor-associated carbonic anhydrases

Human carbonic anhydrases IX (hCA IX) and XII (hCA XII) are two proteins associated with tumor formation and development. These enzymes have been largely investigated both from a biochemical and a functional point of view. However, limited data are currently available on the characterization of their post-translational modifications (PTMs) and the functional implication of these structural changes in the tumor environment. In this review, we summarize existing literature data on PTMs of hCA IX and hCA XII, such as disulphide bond formation, phosphorylation, O-/N-linked glycosylation, acetylation and ubiquitination, highlighting, when possible, their specific role in cancer pathological processes.

Gene Families With Stochastic Exclusive Gene Choice Underlie Cell Adhesion in Mammalian Cells

Exclusive stochastic gene choice combines precision with diversity. This regulation enables most T-cells to express exactly one T-cell receptor isoform chosen from a large repertoire, and to react precisely against diverse antigens. Some cells express two receptor isoforms, revealing the stochastic nature of this process. A similar regulation of odorant receptors and protocadherins enable cells to recognize odors and confer individuality to cells in neuronal interaction networks, respectively. We explored whether genes in other families are expressed exclusively by analyzing single-cell RNA-seq data with a simple metric. This metric can detect exclusivity independently of the mean value and the monoallelic nature of gene expression. Chromosomal segments and gene families are more likely to express genes concurrently than exclusively, possibly due to the evolutionary and biophysical aspects of shared regulation. Nonetheless, gene families with exclusive gene choice were detected in multiple cell types, most of them are membrane proteins involved in ion transport and cell adhesion, suggesting the coordination of these two functions. Thus, stochastic exclusive expression extends beyond the prototypical families, permitting precision in gene choice to be combined with the diversity of intercellular interactions.

Carbonic Anhydrase IX Promotes Human Cervical Cancer Cell Motility by Regulating PFKFB4 Expression

Simple Summary

Carbonic anhydrase IX (CAIX) is a hypoxia-induced protein that is highly expressed in numerous human cancers. However, the molecular mechanisms involved in CAIX and human cervical cancer metastasis remain poorly understood. Our study found that CAIX overexpression increases PFKFB4 expression and EMT, promoting cervical cancer cell migration. CAIX could contribute to cervical cancer cell metastasis and its inhibition could be a cervical cancer treatment strategy.

Abstract

Carbonic anhydrase IX (CAIX) is a hypoxia-induced protein that is highly expressed in numerous human cancers. However, the molecular mechanisms involved in CAIX and human cervical cancer metastasis remain poorly understood. In this study, CAIX overexpression in SiHa cells increased cell migration and epithelial-to-mesenchymal transition (EMT). Silencing CAIX in the Caski cell line decreased the motility of cells and EMT. Furthermore, the RNA-sequencing analysis identified a target gene, bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB4), which is influenced by CAIX overexpression and knockdown. A positive correlation was found between CAIX expression and PFKFB4 levels in the cervical cancer of the TCGA database. Mechanistically, CAIX overexpression activated the phosphorylation of extracellular signal-regulated kinases (ERKs) to induce EMT and promote cell migration. In clinical results, human cervical cancer patients with CAIX^high/PFKFB4^high expression in the late stage had higher rates of lymph node metastasis and the shortest survival time. Our study found that CAIX overexpression increases PFKFB4 expression and EMT, promoting cervical cancer cell migration. CAIX could contribute to cervical cancer cell metastasis and its inhibition could be a cervical cancer treatment strategy.

Carbonic anhydrase IX: a regulator of pH and participant in carcinogenesis

Carbonic anhydrase IX (CAIX) is a transmembrane metalloenzyme which is upregulated in tumour cells under hypoxic conditions. CAIX expression is induced by the accumulation of hypoxia-inducible factor-1α and has several downstream effects, including acidification of the extracellular pH, loss of cellular adhesion and increased tumour cell migration. CAIX is upregulated in a variety of solid organ tumours and has prognostic implications. High CAIX protein expression is a marker of poor prognosis in breast, lung, ovarian and bladder carcinomas. Conversely, low expression is an indicator of poor prognosis in clear cell renal cell carcinoma (CCRCC). CAIX immunohistochemistry is useful diagnostically to identify metastatic CCRCC, and the recently recognised clear cell papillary renal cell carcinoma. There is much interest in targeting CAIX with monoclonal antibodies and small molecule inhibitors. There are several small molecule inhibitors under development which have shown promising results in clinical trials. In this paper, we provide an overview of the role of CAIX in tumourigenesis and outline its use as a prognostic, diagnostic and therapeutic biomarker.

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.

Carbonic Anhydrase IX in Renal Cell Carcinoma, Implications for Disease Management

Carbonic Anhydrase IX (CAIX) is a well-described enzyme in renal cell carcinoma, with its expression being regulated by the hypoxia-inducible factor 1 alpha, it is known for interfering with hypoxia processes. Renal carcinoma encompasses a broad spectrum of histological entities and is also described as a heterogeneous malignant tumor. Recently, various combinations of checkpoint inhibitors and targeted therapies have been validated to manage this disease. Reliable markers to confirm the diagnosis, estimate the prognosis, predict or monitor the treatment response are required. Molecular imaging developments allow a comprehensive analysis of the tumor, overcoming the spatial heterogeneity issue. CAIX, being highly expressed at the tumor cell surfaces of clear cell renal carcinoma, also represents a potential treatment target. In this manuscript we reviewed the current knowledge from the literature on the pathophysiological interactions between renal cell carcinoma and CAIX, the role of CAIX as a marker for diagnosis, prognosis, treatment monitoring and molecular imaging, and the potential target for therapeutic strategies.

The roles of carbonic anhydrases IX and XII in cancer cell adhesion, migration, invasion and metastasis

The main function of carbonic anhydrases (CAs) in cancer cells is the pH regulation through a conversion of H₂ O and CO₂ to H⁺ and HCO₃ ^- . However, the data of in vitro and in vivo studies have demonstrated that transmembrane isoforms of CA IX and CA XII are involved in various steps of cancer cell migration, invasion and metastasis. According to literature, inhibition of these CAs can affect the expression of multiple proteins. Some scientific groups have reported the possible interactions between CA IX and E-cadherin-catenin system, CA IX and integrins, CA IX, CA XII and ion transporters, which all are highly involved in cell-to-cell adhesion, the formation of membrane protrusions and focal adhesions. Nevertheless, CA IX and CA XII have a high impact on tumour growth and metastases formation. The data discussed in this review are quite recent. It highly support the role of CA IX and CA XII in various cancer metastasis processes through their interactions to other invasion proteins. Nevertheless, all findings show the great potential of these CAs in the context of research and application in clinical use.

CAIX Regulates GBM Motility and TAM Adhesion and Polarization through EGFR/STAT3 under Hypoxic Conditions

Carbonic anhydrases (CAs) are acid-base regulatory proteins that modulate a variety of physiological functions. Recent findings have shown that CAIX is particularly upregulated in glioblastoma multiforme (GBM) and is associated with a poor patient outcome and survival rate. An analysis of the GSE4290 dataset of patients with gliomas showed that CAIX was highly expressed in GBM and was negatively associated with prognosis. The expression of CAIX under hypoxic conditions in GBM significantly increased in protein, mRNA, and transcriptional activity. Importantly, CAIX upregulation also regulated GBM motility, monocyte adhesion to GBM, and the polarization of tumor-associated monocytes/macrophages (TAM). Furthermore, the overexpression of CAIX was observed in intracranial GBM cells. Additionally, epidermal growth factor receptor/signal transducer and activator of transcription 3 regulated CAIX expression under hypoxic conditions by affecting the stability of hypoxia-inducible factor 1α. In contrast, the knockdown of CAIX dramatically abrogated the change in GBM motility and monocyte adhesion to GBM under hypoxic conditions. Our results provide a comprehensive understanding of the mechanisms of CAIX in the GBM microenvironment. Hence, novel therapeutic targets of GBM progression are possibly developed.

Metabolic regulation in HPV associated head and neck squamous cell carcinoma

Cancer cells exhibit distinct energy metabolic pathways due to multiple oncogenic events. In normoxia condition, the anaerobic glycolysis (Warburg effect) is highly observed in head and neck squamous cell carcinoma (HNSCC). HNSCC is associated with smoking, chewing tobacco, consumption of alcohol or Human Papillomavirus (HPV) infection primarily HPV16. In recent years, the correlation of HPV with HNSCC has significantly expanded. Despite the recent advancement in therapeutic approaches, the rate of HPV infected HNSCC has significantly increased in the last few years, specifically, in lower middle-income countries. The oncoproteins of High-risk Human Papillomavirus (HR-HPV), E6 and E7, alter the metabolic phenotype in HNSCC, which is distinct from non-HPV associated HNSCC. These oncoproteins, modulate the cell cycle and metabolic signalling through interacting with tumor suppressor proteins, p53 and pRb. Since, metabolic alteration represents a major hallmark for tumorigenesis, HPV acts as a source of biomarker linked to cancer progression in HNSCC. The dependency of cancer cells to specific nutrients and alteration of various metabolic associated genes may provide a unique opportunity for pharmacological intervention in HPV infected HNSCC. In this review, we have discussed the molecular mechanism (s) and metabolic regulation in HNSCC depending on the HPV status. We have also discussed the possible potential therapeutic approaches for HPV associated HNSCC through targeting metabolic pathways.

Clinical and Pre-Clinical Evidence of Carbonic Anhydrase IX in Pancreatic Cancer and Its High Expression in Pre-Cancerous Lesions

Hypoxia is a common phenomenon that occurs in most solid tumors. Regardless of tumor origin, the evolution of a hypoxia-adapted phenotype is critical for invasive cancer development. Pancreatic ductal adenocarcinoma is also characterized by hypoxia, desmoplasia, and the presence of necrosis, predicting poor outcome. Carbonic anhydrase IX (CAIX) is one of the most strict hypoxia regulated genes which plays a key role in the adaptation of cancer cells to hypoxia and acidosis. Here, we summarize clinical data showing that CAIX expression is associated with tumor necrosis, vascularization, expression of Frizzled-1, mucins, or proteins involved in glycolysis, and inevitably, poor prognosis of pancreatic cancer patients. We also describe the transcriptional regulation of CAIX in relation to signaling pathways activated in pancreatic cancers. A large part deals with the preclinical evidence supporting the relevance of CAIX in processes leading to the aggressive behavior of pancreatic tumors. Furthermore, we focus on CAIX occurrence in pre-cancerous lesions, and for the first time, we describe CAIX expression within intraductal papillary mucinous neoplasia. Our review concludes with a detailed account of clinical trials implicating that treatment consisting of conventionally used therapies combined with CAIX targeting could result in an improved anti-cancer response in pancreatic cancer patients.

Azidothymidine "Clicked" into 1,2,3-Triazoles: First Report on Carbonic Anhydrase-Telomerase Dual-Hybrid Inhibitors

Cancer cells rely on the enzyme telomerase (EC 2.7.7.49) to promote cellular immortality. Telomerase inhibitors (i.e., azidothymidine) can represent promising antitumor agents, although showing high toxicity when administered alone. Better outcomes were observed within a multipharmacological approach instead. In this context, we exploited the validated antitumor targets carbonic anhydrases (CAs; EC 4.2.1.1) IX and XII to attain the first proof of concept on CA–telomerase dual-hybrid inhibitors. Compounds 1b, 7b, 8b, and 11b showed good in vitro inhibition potency against the CAs IX and XII, with K_I values in the low nanomolar range, and strong antitelomerase activity in PC-3 and HT-29 cells (IC₅₀ values ranging from 5.2 to 9.1 μM). High-resolution X-ray crystallography on selected derivatives in the adduct with hCA II as a model study allowed to determine their binding modes and thus to set the structural determinants necessary for further development of compounds selectively targeting the tumoral cells.

Impairment of carbonic anhydrase IX ectodomain cleavage reinforces tumorigenic and metastatic phenotype of cancer cells

BACKGROUND

Carbonic anhydrase IX (CA IX) is a hypoxia-induced enzyme regulating tumour pH and facilitating cell migration/invasion. It is primarily expressed as a transmembrane cell-surface protein, but its ectodomain can be shed by ADAM17 to extracellular space. This study aims to elucidate the impact of CA IX shedding on cancer cells.

METHODS

We generated a non-shed CA IX mutant by deletion of amino acids 393-402 from the stalk region and studied its phenotypic effects compared to full-length, shedding-competent CA IX using a range of assays based on immunodetection, confocal microscopy, in vitro real-time cell monitoring and in vivo tumour cell inoculation using xenografted NMRI and C57BL/6J female mice.

RESULTS

We demonstrated that the impairment of shedding does not alter the ability of CA IX to bind ADAM17, internalise, form oligomers and regulate pH, but induces cancer-promoting changes in extracellular proteome. Moreover, it affects intrinsic properties of cells expressing the non-shed variant, in terms of their increased ability to migrate, generate primary tumours and form metastatic lesions in lungs.

CONCLUSIONS

Our results show that the ectodomain shedding controls pro-tumorigenic and pro-metastatic roles of the cell-associated CA IX and suggest that this phenomenon should be considered when developing CA IX-targeted therapeutic strategies.

Synthetic Strategies and Computational Inhibition Activity Study for Triazinyl-Substituted Benzenesulfonamide Conjugates with Polar and Hydrophobic Amino Acids as Inhibitors of Carbonic Anhydrases

Various sulfonamide derivatives are intensively studied as anticancer agents owing to their inhibitory activity against human tumor-associated carbonic anhydrase isoforms. In this work, different synthetic procedures for the series of 1,3,5-triazinyl-aminobenzenesulfonamide conjugates with amino acids, possessing polar uncharged, negatively charged, and hydrophobic side chain, were studied and optimized with respect to the yield/purity of the synthesis/product as well as the time of synthetic reaction. These procedures were compared to each other via characteristic HPLC-ESI-DAD/QTOF/MS analytical product profiles, and their benefits as well as limitations were discussed. For new sulfonamide derivatives, incorporating s-triazine with a symmetric pair of polar and some less-polar proteinogenic amino acids, inhibition constants (KIs) against four human carboanhydrases (hCAs), namely cytosolic hCA I, II, transmembrane hCA IV, and the tumor-associated, membrane-bound hCA IX isoforms, were computationally predicted applying various methods of the advanced statistical analysis. Quantitative structure-activity relationship (QSAR) analysis indicated an impressive KI ratio (hCA II/hCA IX) 139.1 and hCA IX inhibition constant very similar to acetazolamide (KI = 29.6 nM) for the sulfonamide derivative disubstituted with Gln. The derivatives disubstituted with Ser, Thr, and Ala showed even lower KIs (8.7, 13.1, and 8.4 nM, respectively).

Sulfonamido carboranes as highly selective inhibitors of cancer-specific carbonic anhydrase IX

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme overexpressed in hypoxic tumors, where it plays an important role in tumor progression. Specific CA IX inhibitors potentially could serve as anti-cancer drugs. We designed a series of sulfonamide inhibitors containing carborane clusters based on prior structural knowledge of carborane binding into the enzyme active site. Two types of carborane clusters, 12-vertex dicarba-closo-dodecaborane and 11-vertex 7,8-dicarba-nido-undecaborate (dicarbollide), were connected to a sulfonamide moiety via aliphatic linkers of varying lengths (1-4 carbon atoms; n = 1-4). In vitro testing of CA inhibitory potencies revealed that the optimal linker length for selective inhibition of CA IX was n = 3. A 1-sulfamidopropyl-1,2-dicarba-closo-dodecaborane (3) emerged as the strongest CA IX inhibitor from this series, with a K_i value of 0.5 nM and roughly 1230-fold selectivity towards CA IX over CA II. X-ray studies of 3 yielded structural insights into their binding modes within the CA IX active site. Compound 3 exhibited moderate cytotoxicity against cancer cell lines and primary cell lines in 2D cultures. Cytotoxicity towards multicellular spheroids was also observed. Moreover, 3 significantly lowered the amount of CA IX on the cell surface both in 2D cultures and spheroids and facilitated penetration of doxorubicin. Although 3 had only a moderate effect on tumor size in mice, we observed favorable ADME properties and pharmacokinetics in mice, and preferential presence in brain over serum.

Pharmacological Inhibition of CA-IX Impairs Tumor Cell Proliferation, Migration and Invasiveness

Carbonic anhydrase IX (CA-IX) plays a pivotal role in regulation of pH in tumor milieu catalyzing carbonic acid formation by hydrating CO₂. An acidification of tumor microenvironment contributes to tumor progression via multiple processes, including reduced cell-cell adhesion, increased migration and matrix invasion. We aimed to assess whether the pharmacological inhibition of CA-IX could impair tumor cell proliferation and invasion. Tumor epithelial cells from breast (MDA-MB-231) and lung (A549) cancer were used to evaluate the cytotoxic effect of sulfonamide CA-IX inhibitors. Two CA-IX enzyme blockers were tested, SLC-0111 (at present in phase Ib clinical trial) and AA-06-05. In these cells, the drugs inhibited cell proliferation, migration and invasion through shifting of the mesenchymal phenotype toward an epithelial one and by impairing matrix metalloprotease-2 (MMP-2) activity. The antitumor activity was elicited via apoptosis pathway activation. An upregulation of p53 was observed, which in turn regulated the activation of caspase-3. Inhibition of proteolytic activity was accompanied by upregulation of the endogenous tissue inhibitor TIMP-2. Collectively, these data confirm the potential use of CA-IX inhibitors, and in particular SLC-0111 and AA-06-05, as agents to be further developed, alone or in combination with other conventional anticancer drugs.

The impact of tumour pH on cancer progression: strategies for clinical intervention

Dysregulation of cellular pH is frequent in solid tumours and provides potential opportunities for therapeutic intervention. The acidic microenvironment within a tumour can promote migration, invasion and metastasis of cancer cells through a variety of mechanisms. Pathways associated with the control of intracellular pH that are under consideration for intervention include carbonic anhydrase IX, the monocarboxylate transporters (MCT, MCT1 and MCT4), the vacuolar-type H⁺-ATPase proton pump, and the sodium-hydrogen exchanger 1. This review will describe progress in the development of inhibitors to these targets.

Microsecond Simulation of the Proteoglycan-like Region of Carbonic Anhydrase IX and Design of Chemical Inhibitors Targeting pH Homeostasis in Cancer Cells

Carbonic anhydrase IX (CAIX) is a membrane-bound enzyme associated with tumor hypoxia and found to be over expressed in various tumor conditions. Targeting CAIX catalytic activity is proven to be efficient modality in modulating pH homeostasis in cancer cells. Proteoglycan-like (PG) region is unique to CAIX and is proposed to serve as an antenna enhancing the export of protons in conjunction with facilitated efflux of lactate ions via monocarboxylate transporters. Moreover, the PG region is also reported to contribute to the assembly and maturation of focal adhesion links during cellular attachment and dispersion on solid supports. Thus, drug targeting of this region shall efficiently modulate pH homeostasis and cell adhesion in cancer cells. As the PG region is intrinsically disordered, the complete crystal structure is not elucidated. Hence, in this study, we intend to sample the conformational landscape of the PG region at microsecond scale simulation in order to sample the most probable conformations that shall be utilized for structure-based drug design. In addition, the sampled conformations were subjected to high-throughput virtual screening against NCI and Maybridge datasets to identify potential hits based on consensus scoring and validation by molecular dynamics simulation. Further, the identified hits were experimentally validated for efficacy by in vitro and direct enzymatic assays. The results reveal 5-(2-aminoethyl)-1,2,3-benzenetriol to be the most promising hit as it showed significant CAIX inhibition at all levels of in silico and experimental validation.

Carbonic anhydrase IX and acid transport in cancer

Alterations in tumour metabolism and acid/base regulation result in the formation of a hostile environment, which fosters tumour growth and metastasis. Acid/base homoeostasis in cancer cells is governed by the concerted interplay between carbonic anhydrases (CAs) and various transport proteins, which either mediate proton extrusion or the shuttling of acid/base equivalents, such as bicarbonate and lactate, across the cell membrane. Accumulating evidence suggests that some of these transporters interact both directly and functionally with CAIX to form a protein complex coined the 'transport metabolon'. Transport metabolons formed between bicarbonate transporters and CAIX require CA catalytic activity and have a function in cancer cell migration and invasion. Another type of transport metabolon is formed by CAIX and monocarboxylate transporters. In this complex, CAIX functions as a proton antenna for the transporter, which drives the export of lactate and protons from the cell. Since CAIX is almost exclusively expressed in cancer cells, these transport metabolons might serve as promising targets to interfere with tumour pH regulation and energy metabolism. This review provides an overview of the current state of research on the function of CAIX in tumour acid/base transport and discusses how CAIX transport metabolons could be exploited in modern cancer therapy.

Carbonic Anhydrase IX-Mouse versus Human

In contrast to human carbonic anhydrase IX (hCA IX) that has been extensively studied with respect to its molecular and functional properties as well as regulation and expression, the mouse ortholog has been investigated primarily in relation to tissue distribution and characterization of CA IX-deficient mice. Thus, no data describing transcriptional regulation and functional properties of the mouse CA IX (mCA IX) have been published so far, despite its evident potential as a biomarker/target in pre-clinical animal models of tumor hypoxia. Here, we investigated for the first time, the transcriptional regulation of the Car9 gene with a detailed description of its promoter. Moreover, we performed a functional analysis of the mCA IX protein focused on pH regulation, cell-cell adhesion, and migration. Finally, we revealed an absence of a soluble extracellular form of mCA IX and provided the first experimental evidence of mCA IX presence in exosomes. In conclusion, though the protein characteristics of hCA IX and mCA IX are highly similar, and the transcription of both genes is predominantly governed by hypoxia, some attributes of transcriptional regulation are specific for either human or mouse and as such, could result in different tissue expression and data interpretation.

CAIX Regulates Invadopodia Formation through Both a pH-Dependent Mechanism and Interplay with Actin Regulatory Proteins

Tumor metastasis is tightly linked with invasive membrane protrusions, invadopodia, formed by actively invading tumor cells. Hypoxia and pH modulation play a role in the invadopodia formation and in their matrix degradation ability. Tumor-associated carbonic anhydrase IX (CAIX), induced by hypoxia, is essential for pH regulation and migration, predisposing it as an active component of invadopodia. To investigate this assumption, we employed silencing and inhibition of CA9, invadopodia isolation and matrix degradation assay. Quail chorioallantoic membranes with implanted tumor cells, and lung colonization assay in murine model were used to assess efficiency of in vivo invasion and the impact of CAIX targeting antibodies. We showed that CAIX co-distributes to invadopodia with cortactin, MMP14, NBCe1, and phospho-PKA. Suppression or enzymatic inhibition of CAIX leads to impaired invadopodia formation and matrix degradation. Loss of CAIX attenuated phosphorylation of Y421-cortactin and influenced molecular machinery coordinating actin polymerization essential for invadopodia growth. Treatment of tumor cells by CAIX-specific antibodies against carbonic or proteoglycan domains results in reduced invasion and extravasation in vivo. For the first time, we demonstrated in vivo localization of CAIX within invadopodia. Our findings confirm the key role of CAIX in the metastatic process and gives rationale for its targeting during anti-metastatic therapy.

The role of carbonic anhydrase IX in cancer development: links to hypoxia, acidosis, and beyond

Cancer development is a complex process that follows an intricate scenario with a dynamic interplay of selective and adaptive steps and an extensive cast of molecules and signaling pathways. Solid tumor initially grows as an avascular bulk of cells carrying oncogenic mutations until diffusion distances from the nearest functional blood vessels limit delivery of nutrients and oxygen on the one hand and removal of metabolic waste on the other one. These restrictions result in regional hypoxia and acidosis that select for adaptable tumor cells able to promote aberrant angiogenesis, remodel metabolism, acquire invasiveness and metastatic propensity, and gain therapeutic resistance. Tumor cells are thereby endowed with capability to survive and proliferate in hostile microenvironment, communicate with stroma, enter circulation, colonize secondary sites, and generate metastases. While the role of oncogenic mutations initializing and driving these processes is well established, a key contribution of non-genomic, landscaping molecular players is still less appreciated despite they can equally serve as viable targets of anticancer therapies. Carbonic anhydrase IX (CA IX) is one of these players: it is induced by hypoxia, functionally linked to acidosis, implicated in invasiveness, and correlated with therapeutic resistance. Here, we summarize the available experimental evidence supported by accumulating preclinical and clinical data that CA IX can contribute virtually to each step of cancer progression path via its enzyme activity and/or non-catalytic mechanisms. We also propose that targeting tumor cells that express CA IX may provide therapeutic benefits in various settings and combinations with both conventional and newly developed treatments.

Genetic polymorphism and carbonic anhydrase 9 expression can predict nodal metastatic prostate cancer risk in patients with prostate-specific antigen levels ≤10 ng/ml at initial biopsy

OBJECTIVES

Active surveillance is a common management method for low-risk prostate cancer (CaP). However, devising a method to prevent disease progression is crucial. Carbon anhydrase 9 (CA9) plays a vital role in cell adhesion and intercellular communication correlated to tumor metastasis. Our study explored the impact of CA9 genetic polymorphism on the clinicopathological features and prognosis of CaP.

MATERIALS AND METHODS

In total, 579 patients with CaP who underwent robot-assisted radical prostatectomy were enrolled, 270 of whom had an initial prostate-specific antigen (PSA) level ≤10 ng/ml and 309 had initial one >10 ng/ml. Three single-nucleotide polymorphisms of CA9 gene were examined using real-time polymerase chain reaction assay.

RESULTS

After adjusting the confounding factors, participants carrying at least one G allele at CA9 rs3829078 had a 2.241-fold change in PSA compared with the wild-type carrier (AA), leading to an initial PSA level of ≤10 ng/ml. Furthermore, patients with CaP with an initial PSA level ≤10 ng/ml who carried at least one G allele at CA9 rs3829078 had a 4.532-fold and 3.484-fold risk of lymph node metastasis and lymphovascular invasion, respectively. Moreover, The Cancer Genome Atlas database showed that the CA9 mRNA expression significantly increased N1 disease risk and worsened overall survival trends.

CONCLUSION

The rs3829078 polymorphic genotype of CA9 can predict the risk of lymph node metastasis of CaP with an initial PSA level ≤10 ng/ml. This is the first study to report a correlation between CA9 gene polymorphisms/CA9 mRNA expression and early detection of CaP.

Fucoidan inhibits epithelial-to-mesenchymal transition via regulation of the HIF-1α pathway in mammary cancer cells under hypoxia

This study examined the effects of fucoidan on epithelial-to-mesenchymal transition (EMT) in a human triple-negative breast cancer (TNBC) cell line in a hypoxic microenvironment. Transwell and wound-healing assays were performed to analyze the invasion and migration of MDA-MB-231 human mammary cancer cells, respectively. The expression levels of EMT markers and hypoxia-inducible factor-1α (HIF-1α) were detected through western blotting. Under hypoxia, fucoidan treatment inhibited proliferation of breast cancer cells. Fucoidan also suppressed the invasion and migration of MDA-MB-231 cells. Western blotting revealed that fucoidan treatment significantly reduced the protein expression levels of HIF-1α and HIF-1 target genes. Furthermore, the nuclear translocation and activity of HIF-1α were reduced. Fucoidan treatment significantly downregulated the expression levels of mesenchymal markers (N-cadherin and vimentin), but upregulated the expression levels of the epithelial markers zonula occludens-1 and E-cadherin. In addition, overexpression of HIF1-α protected cells from fucoidan-mediated suppression of migration and invasion. These data suggested that fucoidan may inhibit EMT in human TNBC cells via downregulation of the HIF1-α signaling pathway.

Preclinical imaging of epidermal growth factor receptor with ABY-029 in soft-tissue sarcoma for fluorescence-guided surgery and tumor detection

BACKGROUND AND OBJECTIVES

Fluorescence-guided surgery using epidermal growth factor receptor (EGFR) targeting has been performed successfully in clinical trials using a variety of fluorescent agents. We investigate ABY-029 (anti-EGFR Affibody^® molecule labeled with IRDye 800CW) compared with a small-molecule perfusion agent, IRDye 700DX carboxylate, in a panel of soft-tissue sarcomas with varying levels of EGFR expression and vascularization.

METHODS

Five xenograft soft-tissue sarcoma cell lines were implanted into immunosuppressed mice. ABY-029 and IRDye 700DX were each administered at 4.98 μM. Fluorescence from in vivo and ex vivo (fresh and formalin-fixed) fixed tissues were compared. The performance of three fluorescence imaging systems was assessed for ex vivo tissues.

RESULTS

ABY-029 is retained longer within tumor tissue and achieves higher tumor-to-background ratios both in vivo and ex vivo than IRDye 700DX. ABY-029 fluorescence is less susceptible to formalin fixation than IRDye 700DX, but both agents have disproportional signal loss in a variety of tissues. The Pearl Impulse provides the highest contrast-to-noise ratio, but all systems have individual advantages.

CONCLUSIONS

ABY-029 demonstrates promise to assist in wide local excision of soft-tissue sarcomas. Further clinical evaluation of in situ or freshly excised ex vivo tissues using fluorescence imaging systems is warranted.

Novel approaches for designing drugs that interfere with pH regulation

INTRODUCTION

In all living species, pH regulation is a tightly controlled process, with a plethora of proteins involved in its regulation. These include sodium-proton exchangers, carbonic anhydrases, anion exchangers, bicarbonate transporters/cotransporters, H⁺-ATPases, and monocarboxylate transporters. All of them play crucial roles in acid-base balancing, both in eukaryotic as well as in prokaryotic organisms, making them interesting drug targets for the management of pathological events (in)directly involved in pH regulation. Areas covered: Interfering with pH regulation for the treatment of tumors and microbial infections is the main focus of this review, with particular attention paid to inhibitors targeting the above-mentioned proteins. The latest advances in each field id reviewed. Expert opinion: Interfering with the pH regulation of tumor cells is a validated approach to tackle primary tumors and metastases growth. Carbonic anhydrases are the most investigated proteins of those aforementioned, with several inhibitors in clinical development. Recent advances in the characterization of proteins involved in pH homeostasis of various pathogens evidenced their crucial role in the survival and virulence of bacterial, fungal, and protozoan microorganisms. Some encouraging results shed light on the possibility to target such proteins for obtaining new anti-infectives, overcoming the extensive drug resistance problems of clinically used drugs.

Plasmatic carbonic anhydrase IX as a diagnostic marker for clear cell renal cell carcinoma

Carbonic anhydrase (CA, EC 4.2.1.1) IX is regarded as a tumour hypoxia marker and CA inhibitors have been proposed as a new class of antitumor agents, with one such agent in Phase II clinical trials. The expression of some CAs, in particular the isoforms CA IX and CA XII, has been correlated with tumour aggressiveness and progression in several cancers. The aim of this study was to evaluate the possibility that CA IX could represent a marker related to clear cell Renal Cell Carcinoma (ccRCC). Bcl-2 and Bax, and the activity of caspase-3, evaluated in tissue biopsies from patients, were congruent with resistance to apoptosis in ccRCCs with respect to healthy controls, respectively. In the same samples, the CA IX and pro-angiogenic factor VEGF expressions revealed that both these hypoxia responsive proteins were strongly increased in ccRCC with respect to controls. CA IX plasma concentration and CA activity were assessed in healthy volunteers and patients with benign kidney tumours and ccRCCs. CA IX expression levels were found strongly increased only in plasma from ccRCC subjects, whereas, CA activity was found similarly increased both in plasma from ccRCC and benign tumour patients, compared to healthy volunteers. These results show that the plasmatic level of CA IX, but not the CA total activity, can be considered a diagnostic marker of ccRCCs. Furthermore, as many reports exist relating CA IX inhibition to a better outcome to anticancer therapy in ccRCC, plasma levels of CA IX could be also predictive for response to therapy.

Warburg effect, lactate dehydrogenase, and radio/chemo-therapy efficacy

The anaerobic metabolism of glucose by cancer cells, even under well-oxygenated conditions, has been documented by Otto Warburg as early as 1927. Micro-environmental hypoxia and intracellular pathways activating the hypoxia-related gene response, shift cancer cell metabolism to anaerobic pathways. In the current review, we focus on a major enzyme involved in anaerobic transformation of pyruvate to lactate, namely lactate dehydrogenase 5 (LDH5). The value of LDH5 as a marker of prognosis of cancer patients, as a predictor of response to radiotherapy (RT) and chemotherapy and, finally, as a major target for cancer treatment and radio-sensitization is reported and discussed. Clinical, translational and experimental data supporting the uniqueness of the LDHA gene and its product LDH5 isoenzyme are summarized and future directions for a metabolic treatment of cancer are highlighted.

Hypoxia increases chemoresistance in human medulloblastoma DAOY cells via hypoxia‑inducible factor 1α‑mediated downregulation of the CYP2B6, CYP3A4 and CYP3A5 enzymes and inhibition of cell proliferation

Medulloblastomas are among the most frequently diagnosed pediatric solid tumors, and drug resistance remains as the principal cause of treatment failure. Hypoxia and the subsequent activation of hypoxia-inducible factor 1α (HIF-1α) are considered key factors in modulating drug antitumor effectiveness, but the underlying mechanisms in medulloblastomas have not yet been clearly understood. The aim of the present study was to determine whether hypoxia induces resistance to cyclophosphamide (CPA) and ifosfamide (IFA) in DAOY medulloblastoma cells, whether the mechanism is dependent on HIF-1α, and whether involves the modulation of the expression of cytochromes P450 (CYP)2B6, 3A4 and 3A5 and the control of cell proliferation. Monolayer cultures of DAOY medulloblastoma cells were exposed for 24 h to moderate (1% O₂) or severe (0.1% O₂) hypoxia, and protein expression was evaluated by immunoblotting. Cytotoxicity was studied with the MTT assay and by Annexin V/PI staining and flow cytometry. Cell proliferation was determined by the trypan-blue exclusion assay and cell cycle by propidium iodide staining and flow cytometry. Hypoxia decreased CPA and IFA cytotoxicity in medulloblastoma cells, which correlated with a reduction in the protein levels of CYP2B6, CYP3A4 and CYP3A5 and inhibition of cell proliferation. These responses were dependent on hypoxia-induced HIF-1α activation, as evidenced by chemical inhibition of its transcriptional activity with 2-methoxyestradiol (2-ME), which enhanced the cytotoxic activity of CPA and IFA and increased apoptosis. Our results indicate that by stimulating HIF-1α activity, hypoxia downregulates the expression of CYP2B6, CYP3A4 and CYP3A5, that in turn leads to decreased conversion of CPA and IFA into their active forms and thus to diminished cytotoxicity. These results support that the combination of HIF-1α inhibitors and canonical antineoplastic agents provides a potential therapeutic alternative against medulloblastoma.

Carbonic anhydrase IX enhances tumor cell proliferation and tumor progression in osteosarcoma

Purpose

We investigated the effect of carbonic anhydrase IX (CA IX) inhibitor under hypoxia and normoxia in SaOS2 human osteosarcoma cell line. We also evaluated the expression of CA IX in 27 patients diagnosed with osteosarcoma.

Materials and methods

CA IX expression in SaOS2 cells cultured under different oxygen tensions was analyzed by Western blotting. To evaluate the effect of CA IX inhibitor, MTS cell viability assay was performed after cells were treated with various concentrations of doxorubicin with or without a CA IX inhibitor. Finally, CA IX expression in patient-derived osteosarcoma samples was evaluated by immunohistochemistry.

Results

Treatment with CA IX inhibitor significantly suppressed cell proliferation and migration under hypoxic conditions. CA IX expression was observed in 81% of 27 patients. The 5-year survival rates in patients with high and low stain scores were 43.8% and 81.8%, respectively.

Conclusion

CA IX inhibitors have the potential to suppress cell proliferation, migration, and chemoresistance.

Aberrant expression of membranous carbonic anhydrase IX (CAIX) is associated with unfavorable disease course in papillary and clear cell renal cell carcinoma

OBJECTIVE

Antibodies against carbonic anhydrase IX (CAIX) are often part of immunohistochemical panels used to assist renal cell cancer (RCC) subtyping. This study was undertaken to determine, whether assessing CAIX expression levels could provide additional prognostic information.

METHODS AND MATERIALS

More than 1,800 RCCs were analyzed in a tissue microarray (TMA) format for CAIX expression. All tumors had been reviewed and newly classified according to the WHO 2016 classification.

RESULTS

Membranous CAIX expression revealed a "black and white" pattern that was strikingly dependent on the RCC subtype. In clear cell RCC, 89.2% of cancers showed strong positivity. The few clear cell RCC with lower CAIX expression levels were more likely to exhibit unfavorable tumor phenotype (p < 0.0001) and poor disease course (p = 0.0036). CAIX was completely absent in 99% of chromophobe RCC and in 100% of oncocytomas. In papillary RCC, 80.2% of cancers showed complete absence of CAIX staining. Papillary RCC with detectable CAIX expression had a less favorable tumor phenotype (p≤0.05) and worse disease outcome (p = 0.0176). These data are consistent with the concept, that "aberrant" CAIX staining - meaning absent or weak staining in a cancer expected to have a high level CAIX expression such as clear cell RCC or detectable CAIX expression in tumors that are typically CAIX negative such as papillary and chromophobe RCC - reflects biologic tumor dedifferentiation.

CONCLUSION

Our data demonstrate that CAIX is a highly useful diagnostic biomarker for RCC providing both diagnostic and prognostic information.

Overexpression of FZD1 and CAIX are Associated with Invasion, Metastasis, and Poor-Prognosis of the Pancreatic Ductal Adenocarcinoma

Approximately 80% of patients with pancreatic ductal adenocarcinoma (PDAC) have metastatic disease with poor prognosis, but clinically available biomarkers have not yet been identified. This study was to investigate the clinical significance of FZD1 and CAIX in PDACs. FZD1 and CAIX protein expression was measured using EnVision immunohistochemistry. Positive FZD1 or CAIX expression was significantly higher in PDAC than that in precursor lesions (p < 0.01). Positive FZD1 or CAIX expression was significantly lower in cases with well-differentiated adenocarcinoma, no-metastasis of the lymph node, no-invasion of regional tissues, and TNM I/II stage disease than in cases with poorly-differentiated adenocarcinoma, metastasis and invasion, and TNM stage III+ IV stage disease (p < 0.05 or p < 0.01). The expression of FZD1 positively correlated with CAIX in PDAC (P = 0.000). Univariate Kaplan-Meier analysis showed that FZD1 and/or CAIX expression (p < 0.001) was significantly associated with shorter overall survival (p < 0.05). Cox multivariate analysis showed that differentiation, tumor mass, lymph node metastasis, invasion, TNM stage, FZD1 and CAIX levels negatively correlated with overall survival. Positive FZD1 and CAIX expressions are poor prognostic factors in PDAC patients. FZD1 and CAIX might be important biological markers for the carcinogenesis, metastasis, invasion, and prognosis of PDAC.