Hypoxia-inducible Carbonic Anhydrase Research Articles

Exploring the Role of Hypoxia-Inducible Carbonic Anhydrase IX (CAIX) in Circulating Tumor Cells (CTCs) of Breast Cancer

Circulating tumor cells (CTCs) in the peripheral blood are believed to be the source of metastasis and can be used as a liquid biopsy to monitor cancer progression and therapeutic response. However, it has been challenging to accurately detect CTCs because of their low frequency and the heterogeneity of the population. In this study, we have developed an in vitro model of CTCs by using non-adherent suspension culture. We used this model to study a group of breast cancer cell lines with distinct molecular subtypes (TNBC, HER2+, and ER+/PR+). We found that, when these breast cancer cell lines lost their attachment to the extracellular matrix, they accumulated a subtype of cancer stem cells (CSC) that expressed the surface markers of stem cells (e.g., CD44+CD24-). These stem-like CTCs also showed high expressions of hypoxia-inducible gene products, particularly the hypoxia-inducible carbonic anhydrase IX (CAIX). Inhibition of CAIX activity was found to reduce CAIX expression and stem cell phenotypes in the targeted CTCs. Further studies are needed, using CTC samples from breast cancer patients, to determine the role of CAIX in CTC survival, CSC transition, and metastasis. CAIX may be a useful surface marker for the detection of CSCs in the blood, and a potential target for treating metastatic breast cancers.

Abstract 1040: Blocking hypoxia-induced carbonic anhydrases 9 enhances sensibility to cisplatin of head and neck squamous carcinoma

Abstract The head and neck squamous carcinomas (HNSSCs) are the sixth most common cancer worldwide. Given the heterogeneous nature of HNSCC, this carcinoma results in higher resistance to chemoradiotherapy. Recent evidence highlight the importance of the hypoxic microenvironment in contributing to cisplatin resistance. Therefore, the aim of this study was to investigate the role played by hypoxia-induced protein carbonic anhydrase 9 (CA9) in supporting HNSCC cisplatin resistance. Furthermore, we purpose to investigate the ability of CA9 inhibitor, SLC-0111, a small molecule already used in Phase I clinical trial, to sensitize HNSSC cells to chemotherapy in vitro and in vivo. We analyzed the expression of CA9 in a public data set of 103 HNSCC samples and 22 oral cavity normal tissues and in two HNSSC cell lines (FaDu; SCC-011). HNSCC cells grown in 2D and 3D models under hypoxic conditions (1% O2) showed increased levels of CA9 and greater resistance to cisplatin than cells grown under normoxic conditions. The addition of CA9 inhibitor SLC-0111 to cisplatin sensitized cells to the chemotherapeutic agent and caused a reduction of colony number, spheroid formation, tumor cell, and spheroid migration and invasiveness. Furthermore, the combination therapy hampered activation of STAT3, AKT, ERK, and EMT program whereas it induced apoptosis. Notably, the combined treatment caused inhibition of tumor growth and induction of apoptosis in HNSCC subcutaneous xenografts, as assessed by high-frequency ultrasonography and fluorescent molecular tomography (FMT) with NIR-Annexin V, respectively, at a higher extent than single agents. In addition, FMT with NIR-Prosense revealed a stronger reduction of lymph nodes metastases when mice bearing orthotopic xenografts were treated with cisplatin plus SLC-0111 with respect to a single treatment. Our findings taken together demonstrate the crucial role played by CA9 in promoting cisplatin resistance in HNSCC and the efficacy of SLC-0111 to sensitize tumor cells and xenografts to chemotherapy. Citation Format: Annachiara Sarnella, Ylenia Ferrara, Luigi Auletta, Sandra Albanese, Vincenzo Alterio, Jean-Yves Winum, Claudiu T Supuran, Laura Cerchia, Giuseppina De Simone, Antonella Zannetti. Blocking hypoxia-induced carbonic anhydrases 9 enhances sensibility to cisplatin of head and neck squamous carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1040.

Hypoxia-induced carbonic anhydrase mediated dorsal horn neuron activation and induction of neuropathic pain.

Neuropathic pain, such as that seen in diabetes mellitus, results in part from central sensitisation in the dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be causative factors in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial-specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn, we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn neurons, depicted by increased expression of hypoxia markers such as hypoxia inducible factor 1α, glucose transporter 3, and carbonic anhydrase 7. Furthermore, inducing hypoxia through intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia-induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.

Evaluation of Betulinic Acid Derivatives as PET Tracers for Hypoxia-Induced Carbonic Anhydrase IX (CA IX) Expression.

Non-invasive visualisation of the expression of hypoxia-related proteins, such as carbonic anhydrase IX (CA IX), by positron emission tomography (PET) could provide important information on the oxygenation status of tumours. Since betulinic acid derivatives bind specifically to CA IX the aim of the study was the development betulinic acid-based 68Ga-labelled PET tracers and to evaluate the hypoxia detecting properties in vitro and in vivo. The binding of betulinic acid (B-DOTA) and betulinyl-3-sulfamate (BS-DOTA) was assessed in two rat tumour cell lines (AT1 prostate and Walker-256 mammary carcinomas). AT1 cells express CA IX in a hypoxia-dependent manner whereas Walker-256 cells, expressing almost no CA IX in wildtype, were transfected with the rat Car9 gene. In vivo measurements were carried out in a small animal PET/CT in AT1 tumours in rats breathing room air, 8% or 100% O2. In AT1 cells hypoxia-induced overexpression of CA IX led to a stronger binding of BS-DOTA but not of B-DOTA. The BS-DOTA binding correlated linearly with the CA IX protein expression and could be blocked by an excess of unlabelled tracer. In the transfected Walker-256 cells no specific binding of either of the tracers was seen. In vivo the intratumoral accumulation of BS-DOTA was increased in animals kept under inspiratory hypoxia and reduced by hyperoxia. Therefore, betulinyl-3-sulfamate could be used as a PET tracer of CA IX expression in tumours and to provide information about the oxygenation status. However, accumulation data indicated that binding not only depends on hypoxia-induce CA IX expression but also on the tumour-line-specific basal expression and on the initial oxygenation status of the tumour.

CBIO-01. INHIBITION OF EXTRACELLULAR CARBONIC ANHYDRASES INHIBITS GLIOBLASTOMA CELL INVASION

Abstract BACKGROUND Malignant gliomas metabolize glucose preferably by glycolysis which is in accordance with the Warburg effect. This induces a high demand of glucose combined with a significant lactic acid load. The hypoxia-inducible carbonic anhydrase (CA) IX has been shown to moderate the extrusion of hydrogen ions into the extracellular space. Since the acidification of the extracellular environment contributes to host tissue invasion due to activation of proteolytic enzymes, we hypothesized that CA IX plays an important role in malignant glioma Recently, specific small molecule inhibitors of this enzyme have been developed and may provide an innovative strategy for anti – invasive treatment. METHODS Two established and 4 primary GBM cell lines (2 with mesenchymal and 2 with proneural transcriptional profile) were exposed to the CAIX inhibitor U104 under normoxic and hypoxic conditions. Cell toxicity was measured by ATP and crystal violet assay. For invasion assessment, a matrigel invasion chamber system with 8 µm pore size polycarbonate filter was used. CAIX expression was analyzed by quantitative RTPCR and Western Blot. RESULTS Hypoxia significantly induced CAIX expression in all cell lines. Invasiveness increased significantly under hypoxic conditions in the mesenchymal cells (p < 0.01). Regardless of oxygenation status, the mesenchymal group displayed significantly higher invasiveness compared to the proneural group (p = 0.006). Looking at all cell lines, invasion is significantly inhibited by U104, both under normoxic and hypoxic conditions (p < 0.01). However, while the mesenchymal group showed the highest susceptibility to CAIX inhibition followed by the proneurally differentiated group, the established cell lines were entirely refractory to CAIX inhibition. CONCLUSION Our data demonstrate that CAIX inhibition can effectively inhibit invasion in malignant glioma cells independent from oxygenation status, however the effects are significantly influenced by cell type specific biological features.

P13.14 Inhibition of extracellular carbonic anhydrases reduces glioblastoma cell invasion

Abstract BACKGROUND Malignant gliomas metabolize glucose preferably by glycolysis which is in accordance with the Warburg effect. This induces a high demand of glucose combined with a significant lactic acid load. The hypoxia-inducible carbonic anhydrase (CA) IX has been shown to moderate the extrusion of hydrogen ions into the extracellular space. Since the acidification of the extracellular environment contributes to host tissue invasion due to activation of proteolytic enzymes, we hypothesized that CA IX plays an important role in malignant glioma Recently, specific small molecule inhibitors of this enzyme have been developed and may provide an innovative strategy for anti - invasive treatment. MATERIAL AND METHODS Two established and 4 primary GBM cell lines (2 with mesenchymal and 2 with proneural transcriptional profile) were exposed to the CAIX inhibitor U104 under normoxic and hypoxic conditions. Cell toxicity was measured by ATP and crystal violet assay. For invasion assessment, a matrigel invasion chamber system with 8 µm pore size polycarbonate filter was used. CAIX expression was analyzed by quantitative RTPCR and Western Blot. RESULTS Hypoxia significantly induced CAIX expression in all cell lines. Invasiveness increased significantly under hypoxic conditions in the mesenchymal cells (p < 0.01). Regardless of oxygenation status, the mesenchymal group displayed significantly higher invasiveness compared to the proneural group (p = 0.006). Looking at all cell lines, invasion is significantly inhibited by U104, both under normoxic and hypoxic conditions (p < 0.01). However, while the mesenchymal group showed the highest susceptibility to CAIX inhibition followed by the proneurally differentiated group, the established cell lines were entirely refractory to CAIX inhibition. CONCLUSION Our data demonstrate that CAIX inhibition can effectively inhibit invasion in malignant glioma cells independent from oxygenation status, however the effects are significantly influenced by cell type specific biological features.

Contemporary update of SPECT tracers and novelties in radioguided surgery: a perspective based on urology.

Recent technical advances and implementation of novel radiotracers have further increased the potential of radioguided surgery for a broad variety of malignancies. Indeed, the possibilities for future applications of novel radiotracers in diverse oncological strategies has become more promising than ever. This literature review aims to provide a contemporary update on a selected group of radiotracers and evaluates the usability of radioguided surgery and sentinel node procedures, focusing on most promising advances. For example, the impact of targeted radiotracers on prostate specific membrane antigen (PSMA), CD206 receptor-targeted agents (99mTc-tilmanocept), and hybrid tracers adding fluorescence to radioguidance (ICG-99mTc-nanocolloid) as well as targeting hypoxia-induced carbonic anhydrase IX (CAIX) will be covered. Furthermore, future outlooks on the implementation of gold nanoparticles (AuNP's), but also technical advances in improved radiotracer detection by hybrid gamma devices will be discussed.

DDRE-13. INHIBITION OF EXTRACELLULAR CARBONIC ANHYDRASES INHIBITS GLIOBLASTOMA CELL INVASION

OBJECTIVEMalignant gliomas metabolize glucose preferably by glycolysis which is in accordance with the Warburg effect. This induces a high demand of glucose combined with a significant lactic acid load. The hypoxia-inducible carbonic anhydrase (CA) IX has been shown to moderate the extrusion of hydrogen ions into the extracellular space. Since the acidification of the extracellular environment contributes to host tissue invasion due to activation of proteolytic enzymes, we hypothesized that CA IX plays an important role in malignant glioma Recently, specific small molecule inhibitors of this enzyme have been developed and may provide an innovative strategy for anti – invasive treatment.METHODSTwo established and 4 primary GBM cell lines (2 with mesenchymal and 2 with proneural transcriptional profile) were exposed to the CAIX inhibitor U104 under normoxic and hypoxic conditions. Cell toxicity was measured by ATP and crystal violet assay. For invasion assessment, a matrigel invasion chamber system with 8 µm pore size polycarbonate filter was used. CAIX expression was analyzed by quantitative RTPCR and Western Blot.RESULTSHypoxia significantly induced CAIX expression in all cell lines. Invasiveness increased significantly under hypoxic conditions in the mesenchymal cells (p < 0.01). Regardless of oxygenation status, the mesenchymal group displayed significantly higher invasiveness compared to the proneural group (p = 0.006). Looking at all cell lines, invasion is significantly inhibited by U104, both under normoxic and hypoxic conditions (p < 0.01). However, while the mesenchymal group showed the highest susceptibility to CAIX inhibition followed by the proneurally differentiated group, the established cell lines were entirely refractory to CAIX inhibition.CONCLUSIONOur data demonstrate that CAIX inhibition can effectively inhibit invasion in malignant glioma cells independent from oxygenation status, however the effects are significantly influenced by cell type specific biological features.

Granulocyte Colony Stimulating Factor Expression in Breast Cancer and Its Association with Carbonic Anhydrase IX and Immune Checkpoints.

Simple SummaryPreclinical studies suggest that interactions between granulocyte colony-stimulating factor (G-CSF) and hypoxia-induced carbonic anhydrase IX regulate the trafficking and function of immune cells in the tumour microenvironment. We investigated the clinical significance of this crosstalk by analyzing the protein expression of G-CSF and macrophage markers by immunohistochemistry on a well-characterized tissue microarray series of invasive breast cancers. We report that high expression of G-CSF on breast carcinoma cells is linked with significantly improved survival in an important group of breast cancers that do not respond to hormonal therapy. These tumours were infiltrated by immune cells expressing biomarkers that can be targeted with immune checkpoint inhibitor drugs. In contrast, carbonic anhydrase IX expression was associated with unfavourable outcomes.Purpose: Granulocyte colony-stimulating factor (G-CSF) and hypoxia modulate the tumour immune microenvironment. In model systems, hypoxia-induced carbonic anhydrase IX (CAIX) has been associated with G-CSF and immune responses, including M2 polarization of macrophages. We investigated whether these associations exist in human breast cancer specimens, their relation to breast cancer subtypes, and clinical outcome. Methods: Using validated protocols and prespecified scoring methodology, G-CSF expression on carcinoma cells and CD163 expression on tumour-associated macrophages were assayed by immunohistochemistry and applied to a tissue microarray series of 2960 primary excision specimens linked to clinicopathologic, biomarker, and outcome data. Results: G-CSFhigh expression showed a significant positive association with ER negativity, HER2 positivity, presence of CD163+ M2 macrophages, and CAIX expression. In univariate analysis, G-CSFhigh phenotype was associated with improved survival in non-luminal cases, although the CAIX+ subset had a significantly adverse prognosis. A significant positive association was observed between immune checkpoint biomarkers on tumour-infiltrating lymphocytes and both G-CSF- and CAIX-expressing carcinoma cells. Immune checkpoint biomarkers correlated significantly with favourable prognosis in G-CSFhigh/non-luminal cases independent of standard clinicopathological features. Conclusions: The prognostic associations linking G-CSF to immune biomarkers and CAIX strongly support their immunomodulatory roles in the tumour microenvironment.

Study of Hypoxia Induced Factor-1Alpha (HIF-1A) and Carbonic Anhydrase 9 (CAIX) in clear cell Renal Cell Carcinoma (ccRCC)

Objective: The aim of this study was to investigate the immunohistochemical expression of hypoxia inducible factor-1α (HIF-1α) and carbonic anhydrase 9 (CAIX) in renal cell carcinoma and the association with clinicopathological parameters.

CA IX Stabilizes Intracellular pH to Maintain Metabolic Reprogramming and Proliferation in Hypoxia.

Tumor hypoxia represents a severe microenvironmental stress that is frequently associated with acidosis. Cancer cells respond to these stresses with changes in gene expression that promote survival at least in part through pH regulation and metabolic reprogramming. Hypoxia-induced carbonic anhydrase IX (CA IX) plays a critical adaptive role in response to hypoxic and acidic environments by catalytically hydrating extracellular CO2 to produce bicarbonate for buffering intracellular pH (pHi). We used proteome-wide profiling to study the cellular response to transient CA IX knockdown in hypoxia and found a decrease in the levels of key glycolytic enzymes and lactate dehydrogenase A (LDHA). Interestingly, the activity of LDH was also decreased as demonstrated by native in-gel activity assay. These changes led to a significant reduction in glycolytic flux and extracellular lactate levels in cancer cells in vitro, contributing to a decrease in proliferation. Interestingly, addition of the alternative LDH substrate alpha-ketobutyrate restored LDHA activity, extracellular acidification, pHi, and cellular proliferation. These results indicate that in the absence of CA IX, reduction of pHi disrupts LDHA activity and hinders the cellular capacity to regenerate NAD+ and secrete protons to the extracellular space. Hypoxia-induced CA IX therefore mediates adaptation to microenvironmental hypoxia and acidosis directly, by enzymatically converting extracellular CO2 to bicarbonate, and indirectly, by maintaining glycolysis-permissive intracellular milieu.

Abstract 233: Tumor-associated carbonic anhydrase IX maintains cellular proliferation by regulating tumor metabolism: a novel link revealed by proteomics

Abstract Tumor hypoxia is a critical microenvironmental stress occurring in virtually all types of solid tumors. Survival of cancer cells is dependent upon their ability to adapt to these limiting conditions. Hypoxia-induced carbonic anhydrase IX (CA IX) plays a crucial adaptive role in response to hypoxic and acidic microenvironments by catalytically hydrating extracellular CO2 to produce bicarbonate ions that maintain intracellular pH (pHi). In order to determine how CAIX function impacts other cellular processes, we used proteomic profiling to identify changes in response to transient CA IX knockdown in hypoxia. We discovered a significant reduction of key glycolytic enzyme levels with a most prominent decrease in lactate dehydrogenase (LDH). Our data shows that in addition to participating in cellular regulation of pHi, CA IX significantly stimulates glycolytic flux, lactate production and rate of proliferation in hypoxia. Because LDH activity contributes to pHi regulation by consuming cytoplasmic protons in the process of NADH regeneration, CA IX knockdown-mediated LDH suppression may further compromise the pHi regulating ability in hypoxia. Interestingly, addition of the alternative LDH substrate alpha-ketobutyrate compensates for reduced lactate production and restores pHi and proliferation in CA IX-deficient cells. These findings suggest that CA IX confers adaptive plasticity and supports proliferation of cancer cells both directly and indirectly - through its effect as a pHi regulator and by maintaining glycolysis-permissive intracellular environment, respectively. Because CA IX expression is limited almost exclusively to tumors, our findings highlight the role as well as provide mechanistic insight for the utility of CA IX as an anti-cancer target and suggests that highly glycolytic tumors might be particularly vulnerable to CA IX-targeted therapy. Citation Format: Martin Benej, Eliska Svastova, Radivojka Banova, Juraj Kopacek, Adriana Gibadulinova, Martin Kery, Simona Arena, Andrea Scaloni, Monica Vitale, Nicola Zambrano, Ioanna Papandreou, Nicholas C. Denko, Silvia Pastorekova. Tumor-associated carbonic anhydrase IX maintains cellular proliferation by regulating tumor metabolism: a novel link revealed by proteomics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 233.

Circulating levels of hydroxylated bradykinin function as an indicator of tissue HIF-1α expression

The critical roles of oxygen homeostasis in metabolism are indisputable and hypoxic responses are correlated with the pathogenesis of gastrointestinal, pulmonary, renal diseases and cancers. Evaluating tissue hypoxia to predict treatment outcome is challenging, however, due to the lack of rapid, accurate and non-invasive methods. Hypoxia enhances prolyl-4-hydroxylase α1 (P4HA1) expression, which can convert bradykinin (BK) to hydroxyprolyl-BK (Hyp-BK), leading us to hypothesize that circulating Hyp-BK/BK ratios may reflect tissue hypoxia and predict treatment outcomes. Direct quantification of Hyp-BK peptides in serum or plasma by conventional MALDI-TOF MS analysis is technically challenging. In our study, a nanopore-based fractionation and enrichment protocol was utilized to allow the simple workflow for circulating Hyp-BK/BK analysis. Hypoxia is linked to poor prognosis due to its role in promoting pancreatic cancer progression and metastasis. Here we show that P4HA1 expression was increased in pancreatic tumors versus adjacent tissue, associated with poor survival, and corresponded with tumor expression of the hypoxia inducible factor 1α (HIF-1α) and carbonic anhydrase 9 (CA9). Hypoxia-induced P4HA1 expression and BK conversion to Hyp-BK were found to be HIF-1α dependent, pre-treatment serum Hyp-BK/BK ratios corresponded with tissue HIF-1α and P4HA1 expression, and high Hyp-BK/BK levels corresponded with poor response to therapy. These results suggest that pre-treatment circulating Hyp-BK/BK ratios may have value as a non-invasive, surrogate indicator of tissue hypoxia and tumor responses to therapy.

CAIX-targeting radiotracers for hypoxia imaging in head and neck cancer models

Hypoxia-induced carbonic anhydrase IX (CAIX) expression is a prognostic marker in solid tumors. In recent years many radiotracers have been developed, but a fair comparison of these compounds is not possible because of the diversity in tumor models and other experimental parameters. In this study we performed a direct in vivo comparison of three promising CAIX targeting radiotracers in xenografted head and neck cancer models. The biodistribution of [111In]In-DOTA-ZCAIX:2 was directly compared with [111In]In-DTPA-G250-F(ab′)2 and [111In] In-DTPA-G250 in female BALB/C nu/nu mice bearing two HNSCC xenografts with different levels of CAIX expression. In vivo biodistribution was quantified by means of microSPECT/CT scans and ex vivo biodistribution was determined with the use of a γ-counter. Tumors were snap frozen and sections were stained for CAIX expression, vessels, hypoxia (pimonidazole) and tumor blood perfusion. Tracer uptake was significantly higher in SSCNij153 tumors compared to SCCNij185 tumors for [111In]In-DOTA-HE3-ZCAIX:2: 0.32 ± 0.03 versus 0.18 ± 0.01%ID/g,(p = 0.003) 4 h p.i., for [111In]In-DTPA-girentuximab-F(ab′)2: 3.0 ± 0.5%ID/g and 1.2 ± 0.1%ID/g (p = 0.03), 24 h p.i. and for [111In]In-DTPA-girentuximab: 30 ± 2.1%ID/g and 7.0 ± 1.0%ID/g (p = 0.0002) 72 h p.i. SPECT imaging with both [111In]In-DTPA-girentuximab-F(ab′)2 and [111In]In-DTPA-girentuximab showed a clear difference in tracer distribution between the two tumor models. The whole IgG, i.e. [111In]In-DTPA-girentuximab, showed the highest tumor-to-muscle ratio. We showed that different CAIX-targeting radiotracers can discriminate a low CAIX-expressing tumor from a high CAIX-expressing head and neck cancer xenografts model. In these hypoxic head and neck xenograft models [111In]In-DTPA-girentuximab showed the most promising results.

Targeting Hypoxia-Induced Carbonic Anhydrase IX Enhances Immune-Checkpoint Blockade Locally and Systemically.

Treatment strategies involving immune-checkpoint blockade (ICB) have significantly improved survival for a subset of patients across a broad spectrum of advanced solid cancers. Despite this, considerable room for improving response rates remains. The tumor microenvironment (TME) is a hurdle to immune function, as the altered metabolism-related acidic microenvironment of solid tumors decreases immune activity. Here, we determined that expression of the hypoxia-induced, cell-surface pH regulatory enzyme carbonic anhydrase IX (CAIX) is associated with worse overall survival in a cohort of 449 patients with melanoma. We found that targeting CAIX with the small-molecule SLC-0111 reduced glycolytic metabolism of tumor cells and extracellular acidification, resulting in increased immune cell killing. SLC-0111 treatment in combination with immune-checkpoint inhibitors led to the sensitization of tumors to ICB, which led to an enhanced Th1 response, decreased tumor growth, and reduced metastasis. We identified that increased expression of CA9 is associated with a reduced Th1 response in metastatic melanoma and basal-like breast cancer TCGA cohorts. These data suggest that targeting CAIX in the TME in combination with ICB is a potential therapeutic strategy for enhancing response and survival in patients with hypoxic solid malignancies.

Indazole Derivatives: Promising Anti-tumor Agents.

Currently, cancer continues being a dramatically increasing and serious threat to public health. Although many anti-tumor agents have been developed in recent years, the survival rate of patients is not satisfactory. The poor prognosis of cancer patients is closely related to the occurrence of drug resistance. Therefore, it is urgent to develop new anti-tumor agents to make up for the deficiency. Indazoles is an important class of heterocyclic compounds possessing a variety of biological activities, such as anti-tumor, anti-bacterial, antiinflammatory, anti-depressant and anti-hypertensive. This review focuses on the recent research advances of indazole derivatives in the aspect of anti-tumor. We have searched the recent literatures about indazole derivatives from the online resources and databases, such as pubmed, scifinder and google scholar. In the recent years, many efforts have been taken to develop indazole derivatives as fibroblast growth factor receptor (FGFR) inhibitors, indoleamine-2,3-dioxygenase1 (IDO1) inhibitors, proviral integration site MuLV (Pim) kinase inhibitors, aurora kinases inhibitors, Bcr-Abl inhibitors, hypoxia inducible factor-1 (HIF-1) inhibitors and carbonic anhydrase (CA) inhibitors. Most compounds display good anti-tumor activities. Developing new anti-cancer agents with new scaffolds and high efficiency is a big challenge for researchers. Indazole derivatives are a class of important bioactive compounds. Making structural modifications on active indazole derivatives according to the corresponding structure-activity relationships is of benefit to obtain more potent anti-cancer leads or clinical drugs. This review will be useful for further development of new indazole-based derivatives as anti-cancer agents.

PROGNOSTIC VALUE OF THE EXPRESSION OF ENDOGENOUS HYPOXIA ASSOCIATED PROTEINS HYPOXIA INDUCIBLE FACTOR-1 ALPHA (HIF-1Α) AND CARBONIC ANHYDRASE ISOFORM 9 (CAIX) EXPRESSIONS IN BREAST CARCINOMA.

10Feb 2018 PROGNOSTIC VALUE OF THE EXPRESSION OF ENDOGENOUS HYPOXIA ASSOCIATED PROTEINS HYPOXIA INDUCIBLE FACTOR-1 ALPHA (HIF-1) AND CARBONIC ANHYDRASE ISOFORM 9 (CAIX) EXPRESSIONS IN BREAST CARCINOMA. Ola A. Harb , Ibtesam Elhasadi , Amal M A Adim , Warda M Said , Sharifa A. M. El.Ammari , Basant Sh El Shafaay Fady M. Habib and Loay M. Gertallah. Department of Pathology, Faculty of Medicine, Zagazig University, Zagazig 44519, Egypt. Department of Pathology, Faculty of Medicine, Benghazi University, Benghazi, Libya. Department of Clinical Oncology and nuclear medicine, Faculty of Medicine, Zagazig University, Zagazig 44519, Egypt. Department of General surgery, Faculty of Medicine, Zagazig University, Zagazig 44519, Egypt.

Expressions of HIF-1α and CA9 in breast carcinoma and their relationships with basal-like subtype

Objective To study the expressions of hypoxia inducible factor-1α (HIF-1α) and carbo-nic anhydrase 9 (CA9) in different molecular subtypes of breast carcinoma and their relationships with basal-like subtype. Methods The expressions of HIF-1α and CA9 were detected by immunohistochemistry in five subtypes of breast carcinoma (n=803). The relationships of the expressions of HIF-1α and CA9 with the clinicopathologic parameters of basal-like subtype and with the prognosis of patients were analyzed. Results The positive expression rates of HIF-1α and CA9 protein in breast carcinoma were much higher than those in para-tumor breast tissues (43.96% vs. 3.86%, χ2=354.858, P<0.001; 19.80% vs. 4.61%, χ2=86.495, P<0.001). The positive expression rates of HIF-1α in Luminal A, Luminal B, epidermal growth factor receptor-2 (HER-2) over-expression, basal-like and normal breast-like subtypes were 31.97%, 25.00%, 56.06%, 77.89% and 55.76% respectively, and the positive expression rates of CA9 were 7.48%, 5.56%, 60.61%, 40.00% and 27.88% respectively, with significant differences (χ2=88.628, P<0.001; χ2=147.128, P<0.001). The positive expression rates of HIF-1α and CA9 in estrogen receptor (ER)-negative breast carcinomas (HER-2 over-expression, basal-like and normal breast-like) were significantly higher than those in ER-positive subtypes (Luminal A and Luminal B, all P<0.005). There was a significant positive correlation between HIF-1α and CA9 (C=0.315, P=0.001), and both were correlated with the lymph node metastasis (χ2=4.542, P=0.033; χ2=7.025, P=0.008), pTNM stage (χ2=5.390, P=0.020; χ2=10.179, P=0.001) and poor prognosis (χ2=4.353, P=0.037; χ2=6.056, P=0.014) of basal-like subtype. Conclusion Over-expressions of HIF-1α and CA9 may be related to the ER-negative breast cancer more closely, and both may play important roles in the occurrence and development of basal-like subtype. Over-expressions of HIF-1α and CA9 may suggest the poorer prognosis of patients with basal-like breast carcinoma. Key words: Breast neoplasms; Hypoxia-inducible factor 1, alpha subunit; Carbonic anhydrases; Basal-like subtype

Hypoxia increases the heterogeneity of melanoma cell populations and affects the response to vemurafenib.

A hypoxic microenvironment is one of the predominant reasons for incomplete response to melanoma treatment. Vemurafenib, which targets the mutated BRAF-V600 kinase, improves melanoma patient survival, however, resistance invariably develops. The present study evaluated the effect of hypoxia on three BRAF-V600E mutant melanoma cell lines, M14, A375 and 518A2, treated with vemurafenib. Compared with the other two cell lines, hypoxic vemurafenib-treated A375 cells exhibited an enhanced cell proliferation rate and migratory capacity compared with normoxic vemurafenib-treated A375 cells. Immunoblotting analyses revealed that the expression levels of hypoxia inducible factor (HIF)1α and carbonic anhydrase IX were reduced in vemurafenib‑treated M14 and 518A2 cells, however, not in A375 cells. The expression levels of the mitogen‑activated protein kinase, Janus kinase-signal transducer and activator of transcription, and phosphatidylinositol-4,5-bisphosphate 3‑kinase signaling pathway proteins revealed a cell‑type specific response to vemurafenib and hypoxia. Knockdown experiments of HIF1α performed in hypoxic A375 cells decreased the expression of phosphorylated (p‑)protein kinase B, which was restored following vemurafenib treatment, and increased the expression of p‑extracellular‑signal‑regulated kinases. Therefore, three melanoma cell lines responded to vemurafenib under hypoxia in a cell type‑specific manner, suggesting that a subset of cells provides a treatment-resistant pool, from which disease relapse may originate. These data confirmed that vemurafenib may be successful in treating the proliferating cells, whereas the non‑proliferating subpopulation must be addressed by a combination of vemurafenib with other treatment strategies.

Hypoxia-induced carbonic anhydrase IX facilitates lactate flux in human breast cancer cells by non-catalytic function.

The most aggressive tumour cells, which often reside in hypoxic environments, rely on glycolysis for energy production. Thereby they release vast amounts of lactate and protons via monocarboxylate transporters (MCTs), which exacerbates extracellular acidification and supports the formation of a hostile environment. We have studied the mechanisms of regulated lactate transport in MCF-7 human breast cancer cells. Under hypoxia, expression of MCT1 and MCT4 remained unchanged, while expression of carbonic anhydrase IX (CAIX) was greatly enhanced. Our results show that CAIX augments MCT1 transport activity by a non-catalytic interaction. Mutation studies in Xenopus oocytes indicate that CAIX, via its intramolecular H+-shuttle His200, functions as a “proton-collecting/distributing antenna” to facilitate rapid lactate flux via MCT1. Knockdown of CAIX significantly reduced proliferation of cancer cells, suggesting that rapid efflux of lactate and H+, as enhanced by CAIX, contributes to cancer cell survival under hypoxic conditions.