Overexpression of carbonic anhydrase IX (CAIX) is an independent unfavorable prognostic marker in endometrioid ovarian cancer

A Case of Duodenal Adenocarcinoma Effectively Highlighted by Linked Color Imaging and Confirmed by Histopathology

While the differential diagnosis of duodenal adenocarcinoma versus adenoma remains the key to determining treatment strategies in patients with suspected duodenal adenocarcinoma, the role of linked color imaging (LCI) in their differential diagnosis remains insufficiently documented. In this case, esophagogastroduodenoscopy (EGD) was performed on a 67-year-old man for anemia, which revealed a 20-mm-sized, whitish, partially reddish, pedunculated lesion located in the duodenal bulb on white light imaging. Using LCI, the lesion was highlighted as a whitish, pedunculated lesion with its central and inferior areas depicted as orangish and reddish, respectively. Endoscopic mucosal resection was performed on the suspicion of an adenocarcinoma for biopsy and endoscopic diagnosis. Histological examination revealed the lesion to be an adenocarcinoma contained in an adenoma: papillary, type 0-Ip, measuring 20x20 mm, pTis (M), involving no lymphovascular invasion. This case appears to underpin the usefulness of LCI in the differential diagnosis of duodenal adenocarcinoma.

Formation of morpholine-acetamide derivatives as potent anti-tumor drug candidates: Pharmacological evaluation and molecular docking studies

Heterocyclic amines and acetamide derivatives are known for their chemotherapeutic potential. Hence, in the present study, morpholine was taken as a principal product and novel morpholine derivatives were designed, formulated, characterized, and screened for the mechanism of inhibition of carbonic anhydrase and their anticancer potential. In addition, in vitro inhibition of hypoxia-inducible factor-1 (HIF-1) protein was also investigated. Results revealed that compounds 1c, 1d, and 1h possessed significant inhibitory activities against carbonic anhydrase with IC50 of 8.80, 11.13, and 8.12 μM, respectively. Interestingly, the carbonic anhydrase inhibitory activity of compound 1h was comparable with that of standard acetazolamide (IC50 7.51 μM). The compounds 1h and 1i significantly inhibited the proliferation of ovarian cancer cell line ID8 with IC50 of 9.40, and 11.2 μM, respectively while the standard cisplatin exhibited an IC50 8.50 μM. In addition, compounds 1c, 1b, 1h and 1i also exhibited significant inhibitory effects on HIF-1α. In conclusion, we report first time the biological potential of morpholine based compounds against ovarian cancer and HIF-1α that may serve as lead molecules for drug discovery.

Leveraging hypoxia in triple-negative breast cancer as a promising treatment strategy

Current treatment strategies for triple-negative breast cancer (TNBC) are based upon conventional chemotherapy, immunotherapy, or a combination of both. The treatment regimen for chemotherapy is often a combination of two or more drugs, either dose dense or low dose for synergy. Anthracyclines, alkylating agents, antimicrotubule agents, and antimetabolites for early-stage TNBC; and antimetabolites, non-taxane microtubule inhibitors, and cross-linker platinums for late-stage TNBC are usually administered in the clinical setting. Newer options for patients with advanced TNBC, such as poly (ADP-ribose) polymerase (PARP) inhibitors and immune checkpoint inhibitors, have recently emerged for cases where surgery is not a viable option and the disease has metastasized. This review outlines the current trends in hypoxia-inspired treatment strategies for TNBC with a focus on clinical trials.

Expression Dynamics of CA IX Epitope in Cancer Cells under Intermittent Hypoxia Correlates with Extracellular pH Drop and Cell Killing by Ureido-Sulfonamide CA IX Inhibitors

Carbonic anhydrase IX (CA IX) is a membrane-bound CA isozyme over-expressed in many hypoxic tumor cells, where it ensures pH homeostasis and has been implicated in tumor survival, metastasis and resistance to chemotherapy and radiotherapy. Given the functional importance of CA IX in tumor biochemistry, we investigated the expression dynamics of CA IX in normoxia, hypoxia and intermittent hypoxia, which are typical conditions experienced by tumor cells in aggressive carcinomas. We correlated the CA IX epitope expression dynamics with extracellular pH acidification and with viability of CA IX-expressing cancer cells upon treatment with CA IX inhibitors (CAIs) in colon HT-29, breast MDA-MB-231 and ovarian SKOV-3 tumor cell models. We observed that the CA IX epitope expressed under hypoxia by these cancer cells is retained in a significant amount upon reoxygenation, probably to preserve their proliferation ability. The extracellular pH drop correlated well with the level of CA IX expression, with the intermittent hypoxic cells showing a similar pH drop to fully hypoxic ones. All cancer cells showed higher sensitivity to CA IX inhibitors (CAIs) under hypoxia as compared to normoxia. The tumor cell sensitivity to CAIs under hypoxia and intermittent hypoxia were similar and higher than in normoxia and appeared to be correlated with the lipophilicity of the CAI.

Design and synthesis of new adamantyl derivatives as promising antiproliferative agents

A series of adamantyl carboxamide derivatives containing sulfonate or sulfonamide moiety were designed as multitargeted inhibitors of ectonucleotide pyrophosphatases/phosphodiesterases (NPPs) and carbonic anhydrases (CAs). The target compounds were investigated for their antiproliferative activity against NCI-60 cancer cell lines panel. Three main series composed of 3- and 4-aminophenol, 4-aminoaniline, and 5-hydroxyindole scaffolds were designed based on a lead compound (A). Compounds 1e (benzenesulfonyl) and 1i (4-fluorobenzenesulfonyl) of 4-aminophenol backbone exhibited the most promising antiproliferative activity. Both compounds exhibited a broad-spectrum and potent inhibition against all the nine tested cancer subtypes. Both compounds showed nanomolar IC50 values over several cancer cell lines that belong to leukemia and colon cancer such as K-562, RPMI-8226, SR, COLO 205, HCT-116, HCT-15, HT29, KM12, and SW-620 cell lines. Compounds 1e and 1i induced apoptosis in K-562 leukemia cells in a dose-dependent manner. Compound 1i showed the highest cytotoxic activity with IC50 value of 200 nM against HT29 cell line. In addition, compounds 1e and 1i were tested against normal breast cells (HME1) and normal skin fibroblast cells (F180) and the results revealed that the compounds are safe toward normal cells compared to cancers cells. Enzymatic assays against NPP1-3 and carbonic anhydrases II, IX, and XII were performed to investigate the possible molecular target(s) of compounds 1e and 1i. Furthermore, a molecular docking study was performed to predict the binding modes of compounds 1e and 1i in the active site of the most sensitive enzymes subtypes.

Proton export upregulates aerobic glycolysis

INTRODUCTION

Aggressive cancers commonly ferment glucose to lactic acid at high rates, even in the presence of oxygen. This is known as aerobic glycolysis, or the "Warburg Effect." It is widely assumed that this is a consequence of the upregulation of glycolytic enzymes. Oncogenic drivers can increase the expression of most proteins in the glycolytic pathway, including the terminal step of exporting H+ equivalents from the cytoplasm. Proton exporters maintain an alkaline cytoplasmic pH, which can enhance all glycolytic enzyme activities, even in the absence of oncogene-related expression changes. Based on this observation, we hypothesized that increased uptake and fermentative metabolism of glucose could be driven by the expulsion of H+ equivalents from the cell.

RESULTS

To test this hypothesis, we stably transfected lowly glycolytic MCF-7, U2-OS, and glycolytic HEK293 cells to express proton-exporting systems: either PMA1 (plasma membrane ATPase 1, a yeast H+-ATPase) or CA-IX (carbonic anhydrase 9). The expression of either exporter in vitro enhanced aerobic glycolysis as measured by glucose consumption, lactate production, and extracellular acidification rate. This resulted in an increased intracellular pH, and metabolomic analyses indicated that this was associated with an increased flux of all glycolytic enzymes upstream of pyruvate kinase. These cells also demonstrated increased migratory and invasive phenotypes in vitro, and these were recapitulated in vivo by more aggressive behavior, whereby the acid-producing cells formed higher-grade tumors with higher rates of metastases. Neutralizing tumor acidity with oral buffers reduced the metastatic burden.

CONCLUSIONS

Therefore, cancer cells which increase export of H+ equivalents subsequently increase intracellular alkalization, even without oncogenic driver mutations, and this is sufficient to alter cancer metabolism towards an upregulation of aerobic glycolysis, a Warburg phenotype. Overall, we have shown that the traditional understanding of cancer cells favoring glycolysis and the subsequent extracellular acidification is not always linear. Cells which can, independent of metabolism, acidify through proton exporter activity can sufficiently drive their metabolism towards glycolysis providing an important fitness advantage for survival.

Epigenetic mechanisms in metal carcinogenesis

Many metals exhibit genotoxic and/or carcinogenic effects. These toxic metals can be found ubiquitously - in drinking water, food, air, general use products, in everyday and occupational settings. Exposure to such carcinogenic metals can result in serious health disorders, including cancer. Arsenic, cadmium, chromium, nickel, and their compounds have already been recognized as carcinogens by the International Agency for Research on Cancer. This review summarizes a wide range of epigenetic mechanisms contributing to carcinogenesis induced by these metals, primarily including, but not limited to, DNA methylation, miRNA regulation, and histone posttranslational modifications. The mechanisms are described and discussed both from a metal-centric and a mechanism-centric standpoint. The review takes a broad perspective, putting the mechanisms in the context of real-life exposure, and aims to assist in guiding future research, particularly with respect to the assessment and control of exposure to carcinogenic metals and novel therapy development.

The role of metabolic ecosystem in cancer progression — metabolic plasticity and mTOR hyperactivity in tumor tissues

Despite advancements in cancer management, tumor relapse and metastasis are associated with poor outcomes in many cancers. Over the past decade, oncogene-driven carcinogenesis, dysregulated cellular signaling networks, dynamic changes in the tissue microenvironment, epithelial-mesenchymal transitions, protein expression within regulatory pathways, and their part in tumor progression are described in several studies. However, the complexity of metabolic enzyme expression is considerably under evaluated. Alterations in cellular metabolism determine the individual phenotype and behavior of cells, which is a well-recognized hallmark of cancer progression, especially in the adaptation mechanisms underlying therapy resistance. In metabolic symbiosis, cells compete, communicate, and even feed each other, supervised by tumor cells. Metabolic reprogramming forms a unique fingerprint for each tumor tissue, depending on the cellular content and genetic, epigenetic, and microenvironmental alterations of the developing cancer. Based on its sensing and effector functions, the mechanistic target of rapamycin (mTOR) kinase is considered the master regulator of metabolic adaptation. Moreover, mTOR kinase hyperactivity is associated with poor prognosis in various tumor types. In situ metabolic phenotyping in recent studies highlights the importance of metabolic plasticity, mTOR hyperactivity, and their role in tumor progression. In this review, we update recent developments in metabolic phenotyping of the cancer ecosystem, metabolic symbiosis, and plasticity which could provide new research directions in tumor biology. In addition, we suggest pathomorphological and analytical studies relating to metabolic alterations, mTOR activity, and their associations which are necessary to improve understanding of tumor heterogeneity and expand the therapeutic management of cancer.

A Review of the Role of Hypoxia in Radioresistance in Cancer Therapy

Hypoxia involves neoplastic cells. Unlike normal tissue, solid tumors are composed of aberrant vasculature, leading to a hypoxic microenvironment. Hypoxia is also known to be involved in both metastasis initiation and therapy resistance. Radiotherapy is the appropriate treatment in about half of all cancers, but loco-regional control failure and a disease recurrence often occur due to clinical radioresistance. Hypoxia induces radioresistance through a number of molecular pathways, and numerous strategies have been developed to overcome this. Nevertheless, these strategies have resulted in disappointing results, including adverse effects and limited efficacy. Additional clinical studies are needed to achieve a better understanding of the complex hypoxia pathways. This review presents an update on the mechanisms of hypoxia in radioresistance in solid tumors and the potential therapeutic solutions.

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.

PEG Linker Length Strongly Affects Tumor Cell Killing by PEGylated Carbonic Anhydrase Inhibitors in Hypoxic Carcinomas Expressing Carbonic Anhydrase IX

Hypoxic tumors overexpress membrane-bound isozymes of carbonic anhydrase (CA) CA IX and CA XII, which play key roles in tumor pH homeostasis under hypoxia. Selective inhibition of these CA isozymes has the potential to generate pH imbalances that can lead to tumor cell death. Since these isozymes are dimeric, we designed a series of bifunctional PEGylated CA inhibitors (CAIs) through the attachment of our preoptimized CAI warhead 1,3,4-thiadiazole-2-sulfonamide to polyethylene glycol (PEG) backbones with lengths ranging from 1 KDa to 20 KDa via a succinyl linker. A detailed structure−thermal properties and structure–biological activity relationship study was conducted via differential scanning calorimetry (DSC) and via viability testing in 2D and 3D (tumor spheroids) cancer cell models, either CA IX positive (HT-29 colon cancer, MDA-MB 231 breast cancer, and SKOV-3 ovarian cancer) or CA IX negative (NCI-H23 lung cancer). We identified PEGylated CAIs DTP1K 28, DTP2K 23, and DTP3.4K 29, bearing short and medium PEG backbones, as the most efficient conjugates under both normoxic and hypoxic conditions, and in the tumor spheroid models. PEGylated CAIs did not affect the cell viability of CA IX-negative NCI-H23 tumor spheroids, thus confirming a CA IX-mediated cell killing for these potential anticancer agents.

Structural Basis of Nanomolar Inhibition of Tumor-Associated Carbonic Anhydrase IX: X-Ray Crystallographic and Inhibition Study of Lipophilic Inhibitors with Acetazolamide Backbone

This study provides a structure-activity relationship study of a series of lipophilic carbonic anhydrase (CA) inhibitors with an acetazolamide backbone. The inhibitors were tested against the tumor-expressed CA isozyme IX (CA IX), and the cytosolic CA I, CA II, and membrane-bound CA IV. The study identified several low nanomolar potent inhibitors against CA IX, with lipophilicities spanning two log units. Very potent pan-inhibitors with nanomolar potency against CA IX and sub-nanomolar potency against CA II and CA IV, and with potency against CA I one order of magnitude better than the parent acetazolamide 1 were also identified in this study, together with compounds that displayed selectivity against membrane-bound CA IV. A comprehensive X-ray crystallographic study (12 crystal structures), involving both CA II and a soluble CA IX mimetic (CA IX-mimic), revealed the structural basis of this particular inhibition profile and laid the foundation for further developments toward more potent and selective inhibitors for the tumor-expressed CA IX.

High Beclin-1 and ARID1A expression corelates with poor survival and high recurrence in intrahepatic cholangiocarcinoma: a histopathological retrospective study

Background

Although surgical resection provides a cure for patients with intrahepatic cholangiocarcinoma (ICC), the risk of mortality and recurrence remains high. Several biomarkers are reported to be associated with the prognosis of ICC, including Beclin-1, ARID1A, carbonic anhydrase IX (CA9) and isocitrate dehydrogenase 1 (IDH1), but results are inconsistent. Therefore, a histopathological retrospective study was performed to simultaneously investigate the relationship of these four potential biomarkers with clinicopathological parameters and their prognostic values in patients with ICC.

Methods

A total of 113 patients with ICC were enrolled from Cancer Hospital of Chinese Academy of Medical Sciences between January 1999 and June 2015. The expression of Beclin-1, ARID1A, IDH1 and CA9 were determined by immunohistochemical staining. The prognostic values of the four biomarkers were analyzed by Cox regression and the Kaplan-Meier method.

Results

Beclin-1, ARID1A, CA9 and IDH1 were highly expressed in ICC tumor tissues. Higher mortality was positively associated with Beclin-1 expression (HR = 2.39, 95% CI = 1.09–5.24) and higher recurrence was positively associated with ARID1A expression (HR = 1.71, 95% CI = 1.06–2.78). Neither CA9 nor IDH1 expression was significantly associated with mortality or disease recurrence. Kaplan-Meier survival curves showed that ICC patients with higher Beclin-1 and ARID1A expression had a lower survival rate and a worse recurrence rate than patients with low Beclin-1 and ARID1A expression (p < 0.05).

Conclusions

High Beclin-1 and ARIDIA expression are strongly associated with poor prognosis in ICC patients, and thus Beclin-1 and ARID1A should be simultaneously considered as potential prognostic biomarkers for ICC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5429-3) contains supplementary material, which is available to authorized users.

A Flexible Synthesis of 68Ga-Labeled Carbonic Anhydrase IX (CAIX)-Targeted Molecules via CBT/1,2-Aminothiol Click Reaction

We herein describe a flexible synthesis of a small library of ⁶⁸Ga-labeled CAIX-targeted molecules via an orthogonal 2-cyanobenzothiazole (CBT)/1,2-aminothiol click reaction. Three novel CBT-functionalized chelators (1–3) were successfully synthesized and labeled with the positron emitter gallium-68. Cross-ligation between the pre-labeled bifunctional chelators (BFCs) and the 1,2-aminothiol-acetazolamide derivatives (8 and 9) yielded six new ⁶⁸Ga-labeled CAIX ligands with high radiochemical yields. The click reaction conditions were optimized to improve the reaction rate for applications with short half-life radionuclides. Overall, our methodology allows for a simple and efficient radiosynthetic route to produce a variety of ⁶⁸Ga-labeled imaging agents for tumor hypoxia.

Development of a Small Molecule Tubulysin B Conjugate for Treatment of Carbonic Anhydrase IX Receptor Expressing Cancers

Carbonic anhydrase IX (CAIX) is a membrane-spanning zinc metalloenzyme that catalyzes the reversible consumption of CO₂ and water to form H⁺ + HCO₃^-. Many human cancers upregulate CAIX to help control the pH in their hypoxic microenvironments. The consequent overexpression of CAIX on malignant cells and low expression on normal tissues render CAIX a particularly attractive target for small molecule inhibitors, antibody-drug conjugates, and ligand-targeted drugs. In this study, CAIX-targeted fluorescent reporter molecules were initially exploited to investigate CAIX-specific binding to multiple cancer cell lines, where they were shown to display potent and selective binding to CAIX positive cells. A small molecule CAIX-targeted tubulysin B conjugate was then synthesized and examined for its ability to kill CAIX-expressing tumor cells in vitro. Potent therapeutic conjugates were subsequently tested in vivo and demonstrated to eliminate solid human tumor xenografts in murine tumor models without exhibiting overt signs of toxicity. Because most solid tumors contain hypoxic regions where CAIX is overexpressed, development of a method to selectively deliver drugs to these hypoxic regions could aid in the therapy of otherwise difficult to treat tumors.

An update on anticancer drug development and delivery targeting carbonic anhydrase IX

The expression of carbonic anhydrase (CA) IX is up-regulated in many types of solid tumors in humans under hypoxic and acidic microenvironment. Inhibition of CA IX enzymatic activity with selective inhibitors, antibodies or labeled probes has been shown to reverse the acidic environment of solid tumors and reduce the tumor growth establishing the significant role of CA IX in tumorigenesis. Thus, the development of potent antitumor drugs targeting CA IX with minimal toxic effects is important for the target-specific tumor therapy. Recently, several promising antitumor agents against CA IX have been developed to treat certain types of cancers in combination with radiation and chemotherapy. Here we review the inhibition of CA IX by small molecule compounds and monoclonal antibodies. The methods of enzymatic assays, biophysical methods, animal models including zebrafish and Xenopus oocytes, and techniques of diagnostic imaging to detect hypoxic tumors using CA IX-targeted conjugates are discussed with the aim to overview the recent progress related to novel therapeutic agents that target CA IX in hypoxic tumors.

Past, Present, and Future: Development of Theranostic Agents Targeting Carbonic Anhydrase IX

Theranostics is the integration of diagnostic information with pharmaceuticals to increase effectiveness and safety of cancer treatments. Nuclear medicine provides a non-invasive means to visualize drug target expression across primary and metastatic sites, and assess pharmacokinetics and efficacy of companion therapeutic agents. This is significant given the increasing recognition of the importance of clonal heterogeneity in treatment response and resistance. Carbonic anhydrase IX (CA-IX) has been advocated as an attractive diagnostic and therapeutic biomarker for targeting hypoxia in solid malignancies. CA-IX confers cancer cell survival under low oxygen tension, and is associated with increased propensity for metastasis. As such, CA-IX is overexpressed in a broad spectrum of cancers. Different classes of antigen recognition molecules targeting CA-IX including monoclonal antibodies, peptides, small molecule inhibitors, and antibody mimetics have been radiolabeled for imaging and therapeutic applications. cG250, a chimeric monoclonal antibody, has been labeled with an assortment of radionuclides (¹²⁴I, ¹¹¹In, ⁸⁹Zr, ¹³¹I, ⁹⁰Y, and ¹⁷⁷Lu) and is the most extensively investigated CA-IX radiopharmaceutical. In recent years, there have been tremendous advancements made by the research community in developing alternatives to cG250. Although still in preclinical settings, several small molecule inhibitors and antibody mimetics hold great promise in improving the management of aggressive and resistant cancers.

Towards Prognostic Profiling of Non-Small Cell Lung Cancer: New Perspectives on the Relevance of Polo-Like Kinase 1 Expression, the TP53 Mutation Status and Hypoxia

Background: Currently, prognosis of non-small cell lung cancer (NSCLC) patients is based on clinicopathological factors, including TNM stage. However, there are considerable differences in patient outcome within a similar staging group, even when patients received identical treatments. In order to improve prognostic predictions and to guide treatment options, additional parameters influencing outcome are required. Polo-like kinase 1 (Plk1), a master regulator of mitotic cell division and the DNA damage response, is considered as a new potential biomarker in this research area. While several studies reported Plk1 overexpression in a broad range of human malignancies, inconsistent results were published regarding the clinical significance hereof. A prognostic panel, consisting of Plk1 and additional biomarkers that are related to the Plk1 pathway, might further improve prediction of patient prognosis. Methods: In this study, we evaluated for the first time the prognostic value of Plk1 mRNA and protein expression in combination with the TP53 mutation status (next generation sequencing), induction of apoptotic cell death (immunohistochemistry for cleaved caspase 3) and hypoxia (immunohistochemistry for carbonic anhydrase IX (CA IX)) in 98 NSCLC adenocarcinoma patients. Results: Both Plk1 mRNA and protein expression and CA IX protein levels were upregulated in the majority of tumor samples. Plk1 mRNA and protein expression levels were higher in TP53 mutant samples, suggesting that Plk1 overexpression is, at least partially, the result of loss of functional p53 (<0.05). Interestingly, the outcome of patients with both Plk1 mRNA and CA IX protein overexpression, who also harbored a TP53 mutation, was much worse than that of patients with aberrant expression of only one of the three markers (p=0.001). Conclusion: The combined evaluation of Plk1 mRNA expression, CA IX protein expression and TP53 mutations shows promise as a prognostic panel in NSCLC patients. Moreover, these results pave the way for new combination strategies with Plk1 inhibitors.

Potential Coagulation Factor-Driven Pro-Inflammatory Responses in Ovarian Cancer Tissues Associated with Insufficient O₂ and Plasma Supply

Tissue factor (TF) is a cell surface receptor for coagulation factor VII (fVII). The TF-activated fVII (fVIIa) complex is an essential initiator of the extrinsic blood coagulation process. Interactions between cancer cells and immune cells via coagulation factors and adhesion molecules can promote progression of cancer, including epithelial ovarian cancer (EOC). This process is not necessarily advantageous, as tumor tissues generally undergo hypoxia due to aberrant vasculature, followed by reduced access to plasma components such as coagulation factors. However, hypoxia can activate TF expression. Expression of fVII, intercellular adhesion molecule-1 (ICAM-1), and multiple pro-inflammatory cytokines can be synergistically induced in EOC cells in response to hypoxia along with serum deprivation. Thus, pro-inflammatory responses associated with the TF-fVIIa-ICAM-1 interaction are expected within hypoxic tissues. Tumor tissue consists of multiple components such as stromal cells, interstitial fluid, albumin, and other micro-factors such as proton and metal ions. These factors, together with metabolism reprogramming in response to hypoxia and followed by functional modification of TF, may contribute to coagulation factor-driven inflammatory responses in EOC tissues. The aim of this review was to describe potential coagulation factor-driven inflammatory responses in hypoxic EOC tissues. Arguments were extended to clinical issues targeting this characteristic tumor environment.

Evaluation of Nonpeptidic Ligand Conjugates for the Treatment of Hypoxic and Carbonic Anhydrase IX-Expressing Cancers

The majority of tumors contain regions of hypoxia, which cause marked phenotypic changes to resident cells. This altered gene expression often leads to increased resistance to anticancer treatments. Therefore, elimination of these resistant hypoxic cells is crucial to prevent disease recurrence. Herein, we describe the selective delivery of imaging and chemotherapeutic agents to cells expressing carbonic anhydrase IX (CA IX), a highly upregulated hypoxia receptor. These agents were conjugated to a potent divalent CA IX ligand through a hydrophilic PEG linker. These conjugates are shown to bind CA IX-expressing cells in a receptor-dependent manner in vitro with mid-nanomolar affinities and in vivo with good tumor selectivity. In a mouse xenograft tumor model using HT-29 cells, a cytotoxic tubulysin B conjugate completely inhibited tumor growth. Overall, the targeting of a hypoxia marker, such as CA IX, to selectively deliver imaging or chemotherapeutic agents may lead to better treatment options for solid, hypoxic tumors. In addition, the combination of standard chemotherapeutics that are most potent in normoxic dividing cells and drugs specifically designed to eliminate hypoxic nondividing cells may elicit a superior clinical outcome. Mol Cancer Ther; 16(3); 453-60. ©2016 AACR.

Prognostic value of serum carbonic anhydrase IX in testicular germ cell tumor patients

Despite the fact that testicular germ cell tumors (TGCTs) are one of the most chemosensitive solid tumors, a small proportion of patients fail to be cured following cisplatin-based first line chemotherapy. Upregulation of carbonic anhydrase IX (CA IX) in various solid tumors is associated with poor outcome. The current prospective study investigated the prognostic value of serum CA IX level in TGCTs. In total, 83 patients (16 non-metastatic following orchiectomy with no evidence of disease, 57 metastatic chemotherapy-naïve and 10 metastatic relapsed chemotherapy-pretreated) starting adjuvant and/or new line of chemotherapy and 35 healthy controls were enrolled in the study. Serum CA IX values were determined using an enzyme-linked immunosorbent assay, and intratumoral CA IX was analyzed by immunohistochemistry. Metastatic chemotherapy-naïve patients had significantly higher mean CA IX serum levels than healthy controls (490.6 vs. 249.6 pg/ml, P=0.005), while there was no difference in serum CA IX levels in non-metastatic or relapsed TGCT patients compared with healthy controls. There was no significant difference in the mean serum CA IX levels between different groups of patients and between the first and second cycle of chemotherapy, nor association with patients/tumor characteristics. Serum CA IX was not prognostic for progression-free survival [hazard ratio (HR)=0.81, P=0.730] or overall survival (HR=0.64, P=0.480). However, there was a significant association between intratumoral CA IX expression and serum CA IX concentration (rho=0.51, P=0.040). These results suggest that serum CA IX level correlates with tumor CA IX expression in TGCT patients, but fails to exhibit either a prognostic value or an association with patients/tumor characteristics.

Evaluation of Nonpeptidic Ligand Conjugates for SPECT Imaging of Hypoxic and Carbonic Anhydrase IX-Expressing Cancers

As tumors grow, vasculature is often deficient or malformed, resulting in many localized areas of hypoxia. Cells located in these hypoxic regions exhibit an altered gene expression pattern that can significantly alter resistance to conventional anticancer treatments such as ionizing radiation and chemotherapeutic drugs. A priori knowledge of the level of hypoxia within a tumor may better guide clinical care. In an effort to create a hypoxia specific imaging agent, a ligand for the tissue hypoxia marker, carbonic anhydrase IX (CA IX), was synthesized and used as a targeting ligand to deliver an attached (99m)Tc-chelating agent. Binding of the resulting conjugates to hypoxic cancer cells was first characterized in vitro. Whole animal imaging and biodistribution studies then were performed to determine tumor specificity in vivo. Several conjugates were found to bind selectively to CA IX expressing tumors in a receptor-dependent manner. We suggest that such conjugates could prove useful in identifying hypoxic cancers and/or quantitating the level of hypoxia within a tumor.

PEGylated Bis-Sulfonamide Carbonic Anhydrase Inhibitors Can Efficiently Control the Growth of Several Carbonic Anhydrase IX-Expressing Carcinomas

A series of aromatic/heterocyclic bis-sulfonamides were synthesized from three established aminosulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitor pharmacophores, coupled with either ethylene glycol oligomeric or polymeric diamines to yield bis-sulfonamides with short or long (polymeric) linkers. Testing of novel inhibitors and their precursors against a panel of membrane-bound CA isoforms, including tumor-overexpressed CA IX and XII and cytosolic isozymes, identified nanomolar-potent inhibitors against both classes and several compounds with medium isoform selectivity in a detailed structure-activity relationship study. The ability of CA inhibitors to kill tumor cells overexpressing CA IX and XII was tested under normoxic and hypoxic conditions, using 2D and 3D in vitro cellular models. The study identified a nanomolar potent PEGylated bis-sulfonamide CA inhibitor (25) able to significantly reduce the viability of colon HT-29, breast MDA-MB231, and ovarian SKOV-3 cancer cell lines, thus revealing the potential of polymer conjugates in CA inhibition and cancer treatment.

Evaluation of a Carbonic Anhydrase IX-Targeted Near-Infrared Dye for Fluorescence-Guided Surgery of Hypoxic Tumors

Proof-of-principle studies in ovarian, lung, and brain cancer patients have shown that fluorescence-guided surgery can enable removal of otherwise undetectable malignant lesions, decrease the number of cancer-positive margins, and permit identification of disease-containing lymph nodes that would have normally evaded resection. Unfortunately, the current arsenal of tumor-targeted fluorescent dyes does not permit identification of all cancers, raising the need to design new tumor-specific fluorescent dyes to illuminate the currently undetectable cancers. In an effort to design a more universal fluorescent cancer imaging agent, we have undertaken to synthesize a fluorophore that could label all hypoxic regions of tumors. We report here the synthesis, in vitro binding, and in vivo imaging of a near-infrared (NIR) fluorescent dye that is targeted to carbonic anhydrase IX (CA IX), i.e., a widely accepted marker of hypoxic tissues. The low molecular weight NIR probe, named Hypoxyfluor, is shown to bind CA IX with high affinity and accumulate rapidly and selectively in CA IX positive tumors. Because nearly all human cancers contain hypoxic regions that express CA IX abundantly, this NIR probe should facilitate surgical resection of a wide variety of solid tumors.

Prognostic Significance of Carbonic Anhydrase IX Expression in Cancer Patients: A Meta-Analysis

Hypoxia is a characteristic of many solid tumors and an adverse prognostic factor for treatment outcome. Hypoxia increases the expression of carbonic anhydrase IX (CAIX), an enzyme that is predominantly found on tumor cells and is involved in maintaining the cellular pH balance. Many clinical studies investigated the prognostic value of CAIX expression, but most have been inconclusive, partly due to small numbers of patients included. The present meta-analysis was therefore performed utilizing the results of all clinical studies to determine the prognostic value of CAIX expression in solid tumors. Renal cell carcinoma was excluded from this meta-analysis due to an alternative mechanism of upregulation. 958 papers were identified from a literature search performed in PubMed and Embase. These papers were independently evaluated by two reviewers and 147 studies were included in the analysis. The meta-analysis revealed strong significant associations between CAIX expression and all endpoints: overall survival [hazard ratio (HR) = 1.76, 95% confidence interval (95%CI) 1.58–1.98], disease-free survival (HR = 1.87, 95%CI 1.62–2.16), locoregional control (HR = 1.54, 95%CI 1.22–1.93), disease-specific survival (HR = 1.78, 95%CI 1.41–2.25), metastasis-free survival (HR = 1.82, 95%CI 1.33–2.50), and progression-free survival (HR = 1.58, 95%CI 1.27–1.96). Subgroup analyses revealed similar associations in the majority of tumor sites and types. In conclusion, these results show that patients having tumors with high CAIX expression have higher risk of locoregional failure, disease progression, and higher risk to develop metastases, independent of tumor type or site. The results of this meta-analysis further support the development of a clinical test to determine patient prognosis based on CAIX expression and may have important implications for the development of new treatment strategies.

Neutralization of Tumor Acidity Improves Antitumor Responses to Immunotherapy

Cancer immunotherapies, such as immune checkpoint blockade or adoptive T-cell transfer, can lead to durable responses in the clinic, but response rates remain low due to undefined suppression mechanisms. Solid tumors are characterized by a highly acidic microenvironment that might blunt the effectiveness of antitumor immunity. In this study, we directly investigated the effects of tumor acidity on the efficacy of immunotherapy. An acidic pH environment blocked T-cell activation and limited glycolysis in vitro. IFNγ release blocked by acidic pH did not occur at the level of steady-state mRNA, implying that the effect of acidity was posttranslational. Acidification did not affect cytoplasmic pH, suggesting that signals transduced by external acidity were likely mediated by specific acid-sensing receptors, four of which are expressed by T cells. Notably, neutralizing tumor acidity with bicarbonate monotherapy impaired the growth of some cancer types in mice where it was associated with increased T-cell infiltration. Furthermore, combining bicarbonate therapy with anti-CTLA-4, anti-PD1, or adoptive T-cell transfer improved antitumor responses in multiple models, including cures in some subjects. Overall, our findings show how raising intratumoral pH through oral buffers therapy can improve responses to immunotherapy, with the potential for immediate clinical translation.

Roles of Carbonic Anhydrase IX in Development of Pancreatic Cancer

The aim of this study was to study the effects of carbonic anhydrase IX (CA IX) towards the invasion and metastasis of pancreatic cancer. The expressions of CA IX in 58 cases of pancreatic cancer and paired paracancerous normal tissues, obtained from 2005 to 2012 in the first Affiliated Hospital of China Medical University, were detected, as well as its expressions in different pancreatic cancer cell lines, aiming to detect the impacts of CA IX silencing towards the invasion and metastasis of pancreatic cancer cells. The CA IX expressions in 58 pancreatic cancer cases were higher than those in the paired paracancerous normal tissues (P < 0.01), and positively correlated with the tumor size and the UICC staging UICC (P < 0.05), the multivariate analysis showed that the high expression of CA IX was the independent risk factor towards the prognosis of pancreatic cancer (P < 0.05). The CA IX was highly expressed in AxPC-1 and Miapaca-2, and the interference effects were significant. CA IX silencing could significantly inhibit the invasion and metastasis of AxPC-1 and Miapaca. We support a pro-tumor role of CA IX in the development and progression of pancreatic cancer.

Carbonic anhydrase IX overexpression regulates the migration and progression in oral squamous cell carcinoma

Carbonic anhydrase IX (CAIX) is reportedly overexpressed in several types of carcinomas and is generally considered a marker of malignancy. The current study investigated the association between membrane expression of CAIX and the clinicopathological characteristics in oral squamous cell carcinoma (OSCC) patients. The study used immunohistochemistry to examine CAIX expression in 271 OSCC specimens by tissue microarray (TMA) and assessed the effect of CAIX overexpression and knockdown on migration of oral cancer cells in vitro. We found that CAIX expression was associated with more advanced clinical stages (p = 0.030) and positive lymph node metastasis (p = 0.026). Importantly, CAIX expression was correlated with a poorer patient prognosis in a univariate survival analysis (p = 0.025). Moreover, CAIX suppression by small interfering RNA (siRNA) significantly reduced cellular migration in OECM-1 oral cancer cell. In conclusion, our study showed that the expression of CAIX in OSCC samples can predict the progression of OSCC and survival of OSCC patients in Taiwan.

Evaluation of a hypoxia regulated gene panel in ovarian cancer

A panel of nine hypoxia regulated genes, selected from a previously published fifty gene panel, was investigated for its ability to predict hypoxic ovarian cancer phenotypes. All nine genes including vascular endothelial growth factor A, glucose transporter 1, phosphoglycerate mutase 1, lactate dehydrogenase A, prolyl 4-hydroxylase, alpha-polypeptide 1, adrenomedullin, N-myc downstream regulated 1, aldolase A, and carbonic anhydrase 9 were upregulated in the HEY and OVCAR-3 human ovarian cell lines cultured in vitro under hypoxic compared to normoxic conditions as measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The gene panel was also elevated in HEY xenograft tumor tissue compared to HEY cells cultured in normoxia. The HEY xenograft tissue demonstrated heterogeneous positive immunohistochemical staining for the exogenous hypoxia biomarker pimonidazole, and the hypoxia regulated protein carbonic anhydrase IX. A quantitative nuclease protection assay (qNPA) was developed which included the nine hypoxia regulated genes. The qNPA assay provided similar results to those obtained using qRT-PCR for cultured cell lines. The qNPA assay was also evaluated using paraffin embedded fixed tissues including a set of five patient matched primary and metastatic serous cancers and four normal ovaries. In this small sample set the average gene expression was higher in primary and metastatic cancer tissue compared to normal ovaries for the majority of genes investigated. This study supports further evaluation by qNPA of this gene panel as an alternative or complimentary method to existing protein biomarkers to identify ovarian cancers with a hypoxic phenotype.

Membrane carbonic anhydrase IX expression and relapse risk in resected stage I-II non-small-cell lung cancer

BACKGROUND

Adjuvant chemotherapy reduces recurrences of non-small-cell lung cancer (NSCLC). To determine which patients need adjuvant chemotherapy, we assessed factors associated with time to relapse (TTR).

METHODS

In 230 resected stage I-II NSCLCs, we correlated immunohistochemistry scores for factors associated with cell growth rate, growth regulation, hypoxia, cell survival, and cell death with TTR.

RESULTS

With a median follow-up of 82 months (1-158) for those alive and relapse free at last follow-up, median time to recurrence was not reached. The 2- and 5-year probabilities of maintaining freedom from recurrence were 80.7% (95% confidence interval, 75.3%, 86.4%) and 74.6% (95% confidence interval, 68.6%, 81.2%), respectively. TTR curves flattened at an apparent cure rate of 70%. In multicovariate Cox models, factors correlating with shorter TTR were membranous carbonic anhydrase IX (mCAIX) staining (any versus none, hazard ratio = 2.083, p = 0.023) and node stage (N1 versus N0, hazard ratio = 2.591, p = 0.002). mCAIX scores correlated positively with tumor size, grade, squamous histology, necrosis, mitoses, Ki67, p53, nuclear DNA methyltransferase 1, and cytoplasmic enhancer-of-split-and-hairy-related protein, and they correlated inversely with papillary histology, epidermal growth factor receptor mutation (trend), copper transporter-1, and cytoplasmic hypoxia-inducible factor-1α, vascular endothelial growth factor, DNA methyltransferase 1, and excision repair cross-complementing rodent repair deficiency, complementation group 1.

CONCLUSION

Nodal stage and mCAIX immunohistochemistry were the strongest independent predictors of shorter TTR in resected NSCLCs. mCAIX correlated with tumor size, markers of tumor proliferation and necrosis, and tumor genetic characteristics, and it paradoxically correlated inversely with the hypoxia markers, hypoxia-inducible factor-1α and vascular endothelial growth factor. Presence of mCAIX could help determine patients with high risk of recurrence who might require adjuvant chemotherapy.

Histopathological determinants of tumor resistance: a special look to the immunohistochemical expression of carbonic anhydrase IX in human cancers

Intrinsic and acquired drug resistance of tumor cells still causes the failure of treatment regimens in advanced human cancers. It may be driven by intrinsic tumor cells features, or may also arise from micro environmental influences. Hypoxia is a microenvironment feature associated with the aggressiveness and metastasizing ability of human solid cancers. Hypoxic cancer cells overexpress Carbonic Anhydrase IX (CA IX). CA IX ensures a favorable tumor intracellular pH, while contributing to stromal acidosis, which facilitates tumor invasion and metastasis. The overexpression of CA IX is considered an epiphenomenon of the presence of hypoxic, aggressive tumor cells. Recently, a relationship between CA IX overexpression and the cancer stem cells (CSCs) population has been hypothesized. CSCs are strictly regulated by tumor hypoxia and drive a major non-mutational mechanism of cancer drug-resistance. We reviewed the current data concerning the role of CA IX overexpression in human malignancies, extending such information to the expression of the stem cells markers CD44 and nestin in solid cancers, to explore their relationship with the biological behavior of tumors. CA IX is heavily expressed in advanced tumors. A positive trend of correlation between CA IX overexpression, tumor stage/grade and poor outcome emerged. Moreover, stromal CA IX expression was associated with adverse events occurrence, maybe signaling the direct action of CA IX in directing the mesenchymal changes that favor tumor invasion; in addition, membranous/cytoplasmic co-overexpression of CA IX and stem cells markers were found in several aggressive tumors. This suggests that CA IX targeting could indirectly deplete CSCs and counteract resistance of solid cancers in the clinical setting.

The potential of liposomes with carbonic anhydrase IX to deliver anticancer ingredients to cancer cells in vivo

Drug delivery nanocarriers, especially targeted drug delivery by liposomes are emerging as a class of therapeutics for cancer. Early research results suggest that liposomal therapeutics enhanced efficacy, while simultaneously reducing side effects, owing to properties such as more targeted localization in tumors and active cellular uptake. Here, we highlight the features of immunoliposomes that distinguish them from previous anticancer therapies, and describe how these features provide the potential for therapeutic effects that are not achievable with other modalities. While a large number of studies has been published, the emphasis here is placed on the carbonic anhydrase IX (CA-IX) and the conjugated liposomes that are likely to open a new chapter on drug delivery system by using immunoliposomes to deliver anticancer ingredients to cancer cells in vivo.

Prognostic value of carbonic anhydrase IX immunohistochemical expression in renal cell carcinoma: a meta-analysis of the literature

Background

Carbonic anhydrase IX (CAIX) protein has been correlated with progression and survival in patients with renal cell carcinoma (RCC). The prognostic value of CAIX in RCC however, remains inconclusive according to published works. This study aimed to analyze CAIX as a biological marker to predict RCC patient prognosis.

Methods

A literature search of the PubMed and Web of Knowledge databases was performed to retrieve original studies from their inception to December of 2013. Fifteen studies, collectively including a total of 2611 patients with renal cell carcinoma, were carefully reviewed. Standard meta-analysis methods were applied to evaluate the prognostic impact of CAIX expression on patient prognosis. The hazard ratio (HR) and its 95% confidence interval (CI) were recorded for the relationship between CAIX expression and survival, and the data were analyzed using Review Manager 5.2 software and Stata software 11.0.

Results

In patients with RCC, low CAIX expression was associated with poor disease-specific survival (HR = 1.89, 95% CI: 1.20–2.98, P = 0.006), unfavorable progression-free survival (HR = 2.62, 95% CI: 1.14–6.05, P = 0.02) and worse overall survival (HR = 2.03, 95% CI: 1.28–3.21, P = 0.002). Furthermore, low CAIX expression was significantly associated with the presence of lymph node metastases (odds ratio (OR) = 0.31, 95% CI = 0.15–0.62, P = 0.0009) and distant metastases (OR = 0.66, 95% CI = 0.46–0.96, P = 0.03) and predicted a higher tumor grade (OR = 0.41, 95% CI = 0.31–0.54, P<0.00001).

Conclusions

Low CAIX expression most likely indicates poor prognosis in RCC patients. Moreover, low CAIX expression was significantly associated with unfavorable clinicopathological factors. To strengthen our findings, further well-designed prospective studies should be conducted to investigate the role of CAIX expression in RCC.

Metabolic differences in estrogen receptor-negative breast cancer based on androgen receptor status

This study investigated the relationship between steroid hormone receptor signaling and cellular metabolism in tumorigenesis by examining the expression of metabolic proteins with respect to androgen receptor (AR) and human epidermal growth factor receptor-2 (HER-2) status in estrogen receptor-negative (ER-) breast cancer. ER- breast cancer cases (n = 334) were selected from a microarray analysis, including those that were AR+ and AR- (n = 127 and 207, respectively) and HER-2+ and HER-2- (n = 140 and 194, respectively). The expression of proteins involved in glycolysis, glutaminolysis, and mitochondrial and intermediary (i.e., serine/glycine) metabolism was determined by immunohistochemistry and correlated with AR and HER-2 status. The expression of several proteins involved in glycolysis, glutaminolysis, and serine/glycine metabolism was higher (p < 0.01) in the AR- than in the AR+ group. In the former, the expression of the glycolytic protein carbonic anhydrase (CA)IX was associated with a shorter disease-free survival period (p = 0.029) and overall survival rate (p = 0.001). In a multivariate Cox analysis, immunoreactivity for CAIX (hazard ratio 15.89, 95 % confidence interval (CI) 1.820-131.6; p = 0.010) was an independent factor in predicting the survival of the AR+ group. In conclusion, differential expression patterns of metabolism-related proteins were noted in ER- breast cancer according to AR status. These findings highlight the link between hormone receptor signaling and metabolic pathways whose dysregulation could underlie breast tumorigenesis.

Correlation of low expression of hMOF with clinicopathological features of colorectal carcinoma, gastric cancer and renal cell carcinoma

Human MOF (males absent on the first), as a histone acetyltransferase, is responsible for histone H4K16 acetylation in human cells. Recent studies have shown that the abnormal gene expression of hMOF is involved in certain primary cancers. Here, we first report the involvement of hMOF expression in clinically diagnosed primary colorectal carcinoma (CRC) and gastric cancer. Simultaneously, the correlation of hMOF expression and clinicopathological features in CRC, gastric cancer and renal cell carcinoma (RCC) was analyzed. The hMOF mRNA expression was assessed in 44 CRC, 16 gastric cancer and 47 RCC human tissue samples by quantitative PCR (qPCR). Statistical analysis of qPCR data revealed a significant reduction (>2-fold decrease) of hMOF gene expression in CRC, 57% (25/44), 94% (15/16) in gastric cancer and 74% (35/47) in RCC tissues of the patients. In patients with CRC, lymph node metastasis and tumor stage were associated with hMOF expression patterns. However, no significant association between hMOF expression and tumor types emerged (p>0.05). Interestingly, in patients with gastric cancer, although no statistically significant difference was found between adjacent (<2 cm away from the cancer tissue) and normal tissues (>5 cm away from the cancer tissue), >2-fold reduction of hMOF expression in adjacent tissues had already appeared in 35% of patients. In addition, low expression of hMOF was strongly correlated with tumor differentiation (p<0.05) and survival of patients with gastric cancer (p<0.001). While in patients with RCC, downregulation of hMOF was connected to ccRCC and tissues with T1 tumor status. Our results suggest that downregulation of hMOF may be common in cancer tissues, and may represent a novel biomarker for tumor diagnosis.

Carbonic anhydrase IX as an imaging and therapeutic target for tumors and metastases

Carbonic anhydrase IX (CAIX) which is a zinc containing metalloprotein, efficiently catalyzes the reversible hydration of carbon dioxide. It is constitutively up-regulated in several cancer types and has an important role in tumor progression, acidification and metastasis. High expression of CAIX generally correlates with poor prognosis and is related to a decrease in the disease-free interval following successful therapy. Therefore, it is considered as a prognostic indicator in oncology.In this review, we describe CAIX regulation and its role in tumor hypoxia, acidification and metastasis. In addition, the molecular imaging of CAIX and its potential for use in cancer detection, diagnosis, staging, and for use in following therapy response is discussed. Both antibodies and small molecular weight compounds have been used for targeted imaging of CAIX expression. The use of CAIX expression as an attractive and promising candidate marker for systemic anticancer therapy is also discussed.

Carbonic anhydrase IX expression is associated with favorable prognostic factors in small intestinal carcinoma

Tumor hypoxia is associated with more aggressive behavior and resistance to chemotherapy and radiotherapy. Carbonic anhydrase IX (CA9) level increases under hypoxia and is related to poor prognostic factors. The aim of this study was to evaluate the expression of CA9 and to identify its prognostic significance in small intestinal carcinomas (SICs). CA9 expression was observed in 36% (63/175) of SICs. CA9 expression showed significant correlation with well- and moderately differentiated tumors compared with poorly differentiated tumors (p=0.039), tumors with no lymph node metastasis (p=0.005), and lower stage carcinomas (p=0.009). CA9 expression showed an inverse correlation with perineural invasion (p=0.021) and lymphatic invasion (p=0.022). No significant correlation was observed between CA9 expression and gross type, histological type, pathological tumor (pT) classification, vascular invasion, pancreas invasion, and retroperitoneal seeding. SICs with CA9 overexpression showed better overall survival compared with those with no or weak CA9 expression (p=0.048). In the multivariate analysis, poorly differentiated SICs (p<0.001) and SICs with lymph node metastasis (p=0.002) were independent poor prognostic factors. CA9 expression in SICs is more frequently associated with good prognostic markers and better overall survival; however, it is not an independent prognostic factor.

A potential diagnostic marker for ovarian cancer: Involvement of the histone acetyltransferase, human males absent on the first

Human males absent on the first (hMOF), a human ortholog of the Drosophila MOF protein, is responsible for histone H4 lysine 16 (H4K16) acetylation in human cells. The depletion of hMOF leads to a global reduction in histone H4K16 acetylation in human cells, genomic instability, cell cycle defects, reduced transcription of certain genes, defective DNA damage repair and early embryonic lethality. Studies have shown that abnormal hMOF gene expression is involved in a number of primary cancers. The present study examined the involvement of hMOF expression and histone H4K16 acetylation in clinically diagnosed primary ovarian cancer tissues. Clinically diagnosed frozen primary ovarian cancer tissues were used for polymerase chain reaction (PCR), quantitative PCR (qPCR), western blotting and immunohistochemical staining approaches. A PCR analysis of mRNA expression in 47 samples revealed a downregulation of hMOF mRNA in 81% of patients, whereas only 13% of patients demonstrated upregulation. qPCR was used to validate the frequent downregulation of hMOF expression in the primary ovarian cancer tissues. As expected, the analysis of hMOF expression in 57 samples revealed that hMOF mRNA expression was significantly downregulated (>2-fold decrease) in 65% of patients, while a <2-fold reduction of hMOF was observed in 10.5% of patients. Furthermore, the expression of hMOF-regulated human leukocyte antigen (HLA) complex 5, (HCP5), was also found to be downregulated in >87% of patients with a decrease in hMOF. hMOF and its regulated gene, HCP5, are frequently downregulated in human ovarian cancer, suggesting that hMOF may be involved in the pathogenesis of the disease.

Epigenetic change in kidney tumor: downregulation of histone acetyltransferase MYST1 in human renal cell carcinoma

Background

MYST1 (also known as hMOF), a member of the MYST family of histone acetyltransferases (HATs) as an epigenetic mark of active genes, is mainly responsible for histone H4K16 acetylation in the cells. Recent studies have shown that the abnormal gene expression of hMOF is involved in certain primary cancers. Here we examined the involvement of hMOF expression and histone H4K16 acetylation in primary renal cell carcinoma (RCC). Simultaneously, we investigated the correlation between the expression of hMOF and clear cell RCC (ccRCC) biomarker carbohydrase IX (CA9) in RCC.

Materials and methods

The frozen RCC tissues and RCC cell lines as materials, the reverse transcription polymerase chain reaction (RT-PCR), western blotting and immunohistochemical staining approaches were used.

Results

RT-PCR results indicate that hMOF gene expression levels frequently downregulated in 90.5% of patients (19/21) with RCC. The reduction of hMOF protein in both RCC tissues and RCC cell lines is tightly correlated with acetylation of histone H4K16. In addition, overexpression of CA9 was detected in 100% of ccRCC patients (21/21). However, transient transfection of hMOF in ccRCC 786–0 cells did not affect both the gene and protein expression of CA9.

Conclusion

hMOF as an acetyltransferase of H4K16 might be involved in the pathogenesis of kidney cancer, and this epigenetic changes might be a new CA9-independent RCC diagnostic maker.

Prognostic Relevance of the Expression of CA IX, GLUT-1, and VEGF in Ovarian Epithelial Cancers

Background

Tumor hypoxia is associated with malignant progression and treatment resistance. Hypoxia-related factors, such as carbonic anhydrase IX (CA IX), glucose transporter-1 (GLUT-1), and vascular endothelial growth factor (VEGF) permit tumor cell adaptation to hypoxia. We attempted to elucidate the correlation of these markers with variable clinicopathological factors and overall prognosis.

Methods

Immunohistochemistry for CA IX, GLUT-1, and VEGF was performed on formalin-fixed, paraffin-embedded tissues from 125 cases of ovarian epithelial cancer (OEC).

Results

CA IX expression was significantly associated with an endometrioid and mucinous histology, nuclear grade, tumor necrosis, and mitosis. GLUT-1 expression was associated with tumor necrosis and mitosis. VEGF expression was correlated only with disease recurrence. Expression of each marker was not significant in terms of overall survival in OECs; however, there was a significant correlation between poor overall survival rate and high coexpression of these markers.

Conclusions

The present study suggests that it is questionable whether CA IX, GLUT-1, or VEGF can be used alone as independent prognostic factors in OECs. Using at least two markers helps to predict patient outcomes in total OECs. Moreover, the inhibition of two target gene combinations might prove to be a novel anticancer therapy.

The hypoxic tumor microenvironment regulates invasion of aggressive oral carcinoma cells

Invasion is an important hallmark of cancer involving interactions between the tumor microenvironment and the cancer cells. Hypoxia, low oxygen level, is related to increased invasion and metastasis in many cancers. The aim was to elucidate the effect of hypoxia on invasion of oral squamous cell carcinoma cells (OSCCs), and the applicability of a novel 3-dimentional myoma organotypic invasion model in hypoxia experiments. OSCC cell lines (primary oral carcinoma derived cells UT-SCC-43A, recurrent oral carcinoma cells UT-SCC-43B and aggressive tongue carcinoma cells HSC-3) were studied for their migration and invasion capabilities under normoxia, hypoxia, and in the presence a hypoxia-mimicker cobalt chloride. As expected, the recurrent UT-SCC-43B cells were significantly more aggressive than the primary tumor derived cells. In contrast to tongue carcinoma HSC-3 cells, they only mildly responded to hypoxia in the migration or invasion assays, indicating a cell line specific response of hypoxia on the invasive potential. The modification of the organotypic human tissue-derived matrix via the removal of various yet unidentified soluble factors by rinsing the tissue resulting in stripped matrix substantially changed the invasion pattern of HSC-3 cells and the outcomes of hypoxic treatments. Only in the stripped tissue hypoxia significantly increased invasion, whereas in native intact tissue the induced invasion was not observed. This demonstrates the importance of the soluble factors to the invasion pattern and to the hypoxia response. A metastasis and poor prognosis marker, hypoxia-regulated lysyl oxidase (LOX), was present in the myoma tissue, but could be removed by rinsing. The inhibition of LOX resulted in a decrease in invasion area, but only very mildly in invasion depth. Thus, it may have a role in the modulation of the invasion pattern. Another hypoxia-related poor prognosis marker carbonic anhydrase 9 (CAIX) was induced in HSC-3 cells both by the hypoxic exposure and interestingly in invading HSC-3 cells inside the tissue even in normoxic conditions. In conclusion, this suggests that the intact myoma organotypic model offers optimally hypoxic surroundings, thus being an excellent human tumor microenvironment mimicker.

Recent developments in targeting carbonic anhydrase IX for cancer therapeutics

Carbonic anhydrase IX (CAIX) is a hypoxia-inducible enzyme that is overexpressed by cancer cells from many tumor types, and is a component of the pH regulatory system invoked by these cells to combat the deleterious effects of a high rate of glycolytic metabolism. CAIX functions to help produce and maintain an intracellular pH (pHi) favorable for tumor cell growth and survival, while at the same time participating in the generation of an increasingly acidic extracellular space, facilitating tumor cell invasiveness. Pharmacologic interference of CAIX catalytic activity using monoclonal antibodies or CAIX-specific small molecule inhibitors, consequently disrupting pH regulation by cancer cells, has been shown recently to impair primary tumor growth and metastasis. Many of these agents are in preclinical or clinical development and constitute a novel, targeted strategy for cancer therapy.

Carcinogenic metals and the epigenome: understanding the effect of nickel, arsenic, and chromium

Carcinogenic metals, such as nickel, arsenic, and chromium, are widespread environmental and occupational pollutants. Chronic exposure to these metals has been connected with increased risks of numerous cancers and as well as non-carcinogenic health outcomes, including cardiovascular disease, neurologic deficits, neuro-developmental deficits in childhood, and hypertension. However, currently the specific molecular targets for metal toxicity and carcinogenicity are not fully understood. Here, we propose that the iron- and 2-oxoglutarate-dependent dioxygenase family enzymes, as well as, other histone modifying enzymes are important intracellular targets that mediate the toxicity and carcinogenicity of nickel, and maybe potential targets in chromium and arsenic induced carcinogenesis. Our data demonstrate that all three metals are capable of inducing post-translational histone modifications and affecting the enzymes that modulate them (i.e. the iron- and 2-oxoglutarate-dependent dioxygenase family, including HIF-prolyl hydroxylase PHD2, histone demethylase JHDM2A/JMJD1A, and DNA repair enzymes ABH3 and ABH2, and histone methyltransferases, G9a). Given the effects that these metals can exert on the epigenome, future studies of their involvement in histone modifying enzymes dynamics would deepen our understanding on their respective toxicities and carcinogenicities.

Optimization of a novel peptide ligand targeting human carbonic anhydrase IX

Background

Carbonic anhydrase IX (CA IX) is a hypoxia-regulated transmembrane protein over-expressed in various types of human cancer. Recently, a new peptide with affinity for human carbonic anhydrase IX (CaIX-P1) was identified using the phage display technology. Aim of the present study is to characterize the binding site in the sequence of CaIX-P1, in order to optimize the binding and metabolic properties and use it for targeting purposes.

Methodology/Principal Findings

Various fragments of CaIX-P1 were synthesized on solid support using Fmoc chemistry. Alanine scanning was performed for identification of the amino acids crucial for target binding. Derivatives with increased binding affinity were radiolabeled and in vitro studies were carried out on the CA IX positive human renal cell carcinoma cell line SKRC 52 and the CA IX negative human pancreatic carcinoma cell line BxPC3. Metabolic stability was investigated in cell culture medium and human serum. Organ distribution and planar scintigraphy studies were performed in Balb/c nu/nu mice carrying subcutaneously transplanted SKRC 52 tumors.

The results of our studies clearly identified amino acids that are important for target binding. Among various fragments and derivatives the ligand CaIX-P1-4-10 (NHVPLSPy) was found to possess increased binding potential in SKRC 52 cells, whereas no binding capacity for BxPC3 cells was observed. Binding of radiolabeled CaIX-P1-4-10 on CA IX positive cells could be inhibited by both the unlabeled and the native CaIX-P1 peptide but not by control peptides. Stability experiments indicated the degradation site in the sequence of CaIX-P1-4-10. Biodistribution studies showed a higher in vivo accumulation in the tumor than in most healthy tissues.

Conclusions

Our data reveal modifications in the sequence of the CA IX affine ligand CaIX-P1 that might be favorable for improvement of target affinity and metabolic stability, which are necessary prior to the use of the ligand in clinical approaches.