Systematic Analysis of the Relationship Between Elevated Zinc and Epilepsy

Previous studies have indicated a potential relationship between zinc and epilepsy. The aim of this study is to investigate the causal relationship between zinc, zinc-dependent carbonic anhydrase, and gray matter volume in brain regions enriched with zinc and epilepsy, as well as explore the possible mechanisms by which zinc contributes to epilepsy. First, this study assessed the risk causality between zinc, carbonic anhydrase, and gray matter volume alterations in zinc-enriched brain regions and various subtypes of epilepsy based on Two-sample Mendelian randomization analysis. And then, this study conducted GO/KEGG analysis based on colocalization analysis, MAGMA analysis, lasso regression, random forest model, and XGBoost model. The results of Mendelian randomization analyses showed a causal relationship between zinc, carbonic anhydrase-4, and generalized epilepsy (p = 0.044 , p = 0.010). Additionally, carbonic anhydrase-1 and gray matter volume of the caudate nucleus were found to be associated with epilepsy and focal epilepsy (p = 0.014, p = 0.003 and p = 0.022, p = 0.009). A colocalization relationship was found between epilepsy and focal epilepsy (PP.H4.abf = 97.7e - 2). Meanwhile, the MAGMA analysis indicated that SNPs associated with epilepsy and focal epilepsy were functionally localized to zinc-finger-protein-related genes (p < 1.0e - 5). The genes associated with focal epilepsy were found to have a molecular function of zinc ion binding (FDR = 2.3e - 6). After the onset of epilepsy, the function of the gene whose expression changed in the rats with focal epilepsy was enriched in the biological process of vascular response (FDR = 4.0e - 5). These results revealed mechanism of the increased risk of epilepsy caused by elevated zinc may be related to the increase of zinc ion-dependent carbonic anhydrase or the increase of the volume of zinc-rich caudate gray matter.

Spatial transcriptomic analysis of tumour with high and low CAIX expression in TNBC tissue samples using GeoMx™ RNA assay

PURPOSE

Prognostic significance and gene signatures associated with carbonic anhydrase IX (CAIX) was investigated in triple negative breast cancer (TNBC) patients.

METHODS

Immunohistochemistry (IHC) for CAIX was performed in tissue microarrays (TMAs) of 136 TNBC patients. In a subset of 52 patients Digital Spatial Profiler (DSP) was performed in tumour (pan-cytokeratin+) and stroma (pan-cytokeratin-). Differentially expressed genes (DEGs) with P<0.05 and and log2 fold change (FC)>(±0.25 and ±0.3, for tumour and stromal compartment, respectively) were identified. Four genes were validated at the protein level.

RESULT

Cytoplasmic CAIX expression was independently associated with poor recurrence free survival in TNBC patients [hazard ratio (HR)=6.59, 95% confidence interval (CI): 1.47-29.58, P=0.014]. DEG analysis identified 4 up-regulated genes (CD68, HIF1A, pan-melanocyte, and VSIR) in the tumour region and 9 down-regulated genes in the stromal region (CD86, CD3E, MS4A1, BCL2, CCL5, NKG7, PTPRC, CD27, and FAS) when low versus high CAIX expression was explored. Employing IHC, high CD68 and HIF-1α was associated with poorer prognosis and high BCL2 and CD3 was associated with good prognosis.

CONCLUSIONS

DSP technology identified DEGs in TNBC. Selected genes validated by IHC showed involvement of CD3 and BCL2 expression within stroma and HIF-1α, and CD68 expression within tumour. However, further functional analysis is warranted.

Association between Carbonic Anhydrase VI (CA VI) gene copy number and dental caries experience

The current study examined the association between the carbonic anhydrase VI (CA VI) copy number variations (CNVs) and dental caries experience in adults. In total, 202 of 35-72 years old subjects participating in the Lithuanian National Oral Health Survey (LNOHS) agreed to provide saliva samples, thus their data were included in the current study. Information about sociodemographic, environmental, and behavioural determinants was acquired via the self-administered World Health Organisation (WHO) questionnaire. Fluoride levels in the drinking water were recorded based on information provided by water suppliers. Dental caries experience was recorded by one calibrated examiner using the WHO criteria for recording caries on smooth (including proximal, buccal, and oral) or occlusal surfaces. Caries experience was measured as the total number of decayed (D3), missing (M), filled (F) surfaces (D3MFS). DNA was extracted from saliva samples to examine CA VI CNVs using the QX200 droplet digital PCR system. Negative binomial regression and Poisson regression analyses were employed for data analyses. Based on multivariable regression analyses, higher copy number of CA VI were associated with higher caries experience on smooth surfaces (IRR 1.04, 95% CI 1.005 – 1.08) and occlusal surfaces (IRR 1.02, 95% CI 1.003 – 1.04). Positive associations between higher copy number of CA VI and higher caries experience on smooth and occlusal surfaces were found, suggesting that the CA VI coding gene may be associated with caries development. Future studies are needed to validate our results and to examine the underlying mechanisms of such associations.

Effect of amino acids and amines on the activity of the recombinant ι-carbonic anhydrase from the Gram-negative bacterium Burkholderia territorii

We here report a study on the activation of the ι-class bacterial CA from Burkholderia territorii (BteCAι). This protein was recently characterised as a zinc-dependent enzyme that shows a significant catalytic activity (kcat 3.0 × 105 s-1) for the physiological reaction of CO2 hydration to bicarbonate and protons. Some amino acids and amines, among which some proteinogenic derivatives as well as histamine, dopamine and serotonin, showed efficient activating properties towards BteCAι, with activation constants in the range 3.9-13.3 µM. L-Phe, L-Asn, L-Glu, and some pyridyl-alkylamines, showed a weaker activating effect towards BteCAι, with KA values ranging between 18.4 µM and 45.6 µM. Nowadays, no information is available on active site architecture, metal ion coordination and catalytic mechanism of members of the ι-group of CAs, and this study represents another contribution towards a better understanding of this still uncharacterised class of enzymes.

Carbonic anhydrase 13 suppresses bone metastasis in breast cancer

Metastatic progression is the leading cause of mortality in breast cancer. However, molecular mechanisms that govern this process remain unclear. In this study, we found that carbonic anhydrase 13 (CA13) plays a potential role in suppressing bone metastasis. iRFP713-labeled iCSCL-10A (iRFP-iCSCL-10A) breast cancer cells, which exhibit the hallmarks of cancer stem cells, exerted the ability of bone metastasis in hind legs after 5-week injections, whereas no metastasis was observed in control iRFP713-labeled MCF-10A (iRFP-MCF10A) cells. Transcriptome analysis indicated that the expression of several genes, including metabolism-related CA13, was reduced in bone metastatic iRFP-iCSCL-10A cells. In vitro and in vivo analyses demonstrated that overexpression of CA13 in iRFP-iCSCL-10A cells suppressed migration, invasion, and bone metastasis, together with the reduction of VEGF-A and M-CSF expression. Furthermore, we found that breast cancer patients with a low CA13 expression had significantly shorter overall survival and disease-free survival rates compared to those with higher CA13 expression. These findings suggest that CA13 may act as a novel prognostic biomarker and would be a therapeutic candidate for the prevention of bone metastasis in breast cancer.

Conditions for Analysis of Native Protein Structures Using Uniform Field Drift Tube Ion Mobility Mass Spectrometry and Characterization of Stable Calibrants for TWIM-MS

Determination of collisional cross sections (CCS) by travelling wave ion mobility mass spectrometry (TWIM-MS) requires calibration against standards for which the CCS has been measured previously by drift tube ion mobility mass spectrometry (DTIM-MS). The different extents of collisional activation in TWIM-MS and DTIM-MS can give rise to discrepancies in the CCS of calibrants across the two platforms. Furthermore, the conditions required to ionize and transmit large, folded proteins and assemblies may variably affect the structure of the calibrants and analytes. Stable hetero-oligomeric phospholipase A₂ (PDx) and its subunits were characterized as calibrants for TWIM-MS. Conditions for acquisition of native-like TWIM (Synapt G1 HDMS) and DTIM (Agilent 6560 IM-Q-TOF) mass spectra were optimized to ensure the spectra exhibited similar charge state distributions. CCS measurements (DTIM-MS) for ubiquitin, cytochrome c, holo-myoglobin, serum albumin and glutamate dehydrogenase were in good agreement with other recent results determined using this and other DTIM-MS instruments. PDx and its β and γ subunits were stable across a wide range of cone and trap voltages in TWIM-MS and were stable in the presence of organic solvents. The CCS of PDx and its subunits were determined by DTIM-MS and were used as calibrants in determination of CCS of native-like cytochrome c, holo-myoglobin, carbonic anhydrase, serum albumin and haemoglobin in TWIM-MS. The CCS values were in good agreement with those measured by DTIM-MS where available. These experiments demonstrate conditions for analysis of native-like proteins using a commercially available DTIM-MS instrument, characterize robust calibrants for TWIM-MS, and present CCS values determined by DTIM-MS and TWIM-MS for native proteins to add to the current literature database. Graphical Abstract ᅟ.

Cryptophane Nanoscale Assemblies Expand 129Xe NMR Biosensing

Cryptophane-based biosensors are promising agents for the ultrasensitive detection of biomedically relevant targets via 129Xe NMR. Dynamic light scattering revealed that cryptophanes form water-soluble aggregates tens to hundreds of nanometers in size. Acridine orange fluorescence quenching assays allowed quantitation of the aggregation state, with critical concentrations ranging from 200 nM to 600 nM, depending on the cryptophane species in solution. The addition of excess carbonic anhydrase (CA) protein target to a benzenesulfonamide-functionalized cryptophane biosensor (C8B) led to C8B disaggregation and produced the expected 1:1 C8B-CA complex. C8B showed higher affinity at 298 K for the cytoplasmic isozyme CAII than the extracellular CAXII isozyme, which is a biomarker of cancer. Using hyper-CEST NMR, we explored the role of stoichiometry in detecting these two isozymes. Under CA-saturating conditions, we observed that isozyme CAII produces a larger 129Xe NMR chemical shift change (δ = 5.9 ppm, relative to free biosensor) than CAXII (δ = 2.7 ppm), which indicates the strong potential for isozyme-specific detection. However, stoichiometry-dependent chemical shift data indicated that biosensor disaggregation contributes to the observed 129Xe NMR chemical shift change that is normally assigned to biosensor-target binding. Finally, we determined that monomeric cryptophane solutions improve hyper-CEST saturation contrast, which enables ultrasensitive detection of biosensor-protein complexes. These insights into cryptophane-solution behavior support further development of xenon biosensors, but will require reinterpretation of the data previously obtained for many water-soluble cryptophanes.

Comparative study of carbonic anhydrase activity in waters among different geological eco-environments of Yangtze River basin and its ecological significance

This study provides the presence of carbonic anhydrase (CA) activity in waters of the Yangtze River basin, China, as well as the correlation of CA activity with HCO(3)(-) concentration and CO(2) sink flux. Different degrees of CA activity could be detected in almost all of the water samples from different geological eco-environments in all four seasons. The CA activity of water samples from karst areas was significantly higher than from non-karst areas (P<0.01), indicating that the geological type of river basin affected the CA activity of waters. Distinct seasonal changes in CA activity were found, and the variational trend differed among different sampling sites. Generally, CA activity in summer and autumn was higher than in spring (P<0.01) for karst areas. The correlation analysis showed that water CA activity was positively correlated with HCO(3)(-) [corrected] concentration (r=0.672, P<0.01), and that the annual average water CA activity was positively correlated with the CO(2) [corrected] sink flux (r=0.602, P=0.076) in karst areas. This suggests that CA in waters might have a promoting effect on carbon sinks for atmospheric CO(2) in karst river basins. In conditions of similar geological type, higher CA activity was generally detected in water samples taken from areas that exhibited better eco-environments, implying that the CA activity index of waters could be used as an indicator for monitoring ecological environments and protection of river basins. These findings suggest that the role of CA in waters in the karst carbon sink potential of river basins is worthy of further in-depth studies.

Activation Profile Analysis of CruCA4, an α-Carbonic Anhydrase Involved in Skeleton Formation of the Mediterranean Red Coral, Corallium rubrum

CruCA4, a coral α-carbonic anhydrase (CA, EC 4.2.1.1) involved in the biomineralization process of the Mediterranean red coral, Corallium rubrum, was investigated for its activation with a panel of amino acids and amines. Most compounds showed considerable activating properties, with a rather well defined structure-activity relationship. The most effective CruCA4 activators were d-His, 4-H₂N-l-Phe, Histamine, Dopamine, Serotonin, 1-(2-Aminoethyl)-piperazine, and l-Adrenaline, with activation constants in the range of 8-98 nM. Other amines and amino acids, such as d-DOPA, l-Tyr, 2-Pyridyl-methylamine, 2-(2-Aminoethyl) pyridine and 4-(2-Aminoethyl)-morpholine, were submicromolar CruCA4 activators, with K_A ranging between 0.15 and 0.93 µM. Since it has been shown that CA activators may facilitate the initial phases of in-bone mineralization, our study may be relevant for finding modulators of enzyme activity, which can enhance the formation of the red coral skeleton.

High serum carbonic anhydrase IX predicts shorter survival in head and neck cancer

OBJECTIVES

The objective of the study was to investigate prognostic and predictive value of pretreatment soluble carbonic anhydrase IX (CA IX) blood serum concentration in patients with locally advanced head and neck cancer.

BACKGROUND

Increased expression of CA IX in tumor tissues has been associated with treatment resistance and worth prognosis. Soluble form of CA IX, released from tumor cells, is detectable in blood serum and could be a convenient predictive factor of treatment effectiveness that would enable treatment individualization.

METHODS

The prospective study evaluated 48 patients with locally advanced squamous cell carcinomas of head and neck, treated by radiotherapy or chemo-radiotherapy. Pretreatment soluble CA IX serum concentrations were examined using enzyme-linked immunosorbent assay.

RESULTS

Soluble CA IX serum concentration failed to predict radiotherapy effectiveness in the studied patient population (p = 0.26). However, high CA IX serum concentrations have been associated with shorter overall survival (p = 0.035) CONCLUSION: High pretreatment CA IX serum concentration is a negative prognostic factor in locally advanced head and neck cancer patients (Tab. 1, Fig. 2, Ref. 23).

What's in the Gift? Towards a Molecular Dissection of Nuptial Feeding in a Cricket

Nuptial gifts produced by males and transferred to females during copulation are common in insects. Yet, their precise composition and subsequent physiological effects on the female recipient remain unresolved. Male decorated crickets Gryllodes sigillatus transfer a spermatophore to the female during copulation that is composed of an edible gift, the spermatophylax, and the ampulla that contains the ejaculate. After transfer of the spermatophore, the female detaches the spermatophylax and starts to eat it while sperm from the ampulla are evacuated into the female reproductive tract. When the female has finished consuming the spermatophylax, she detaches the ampulla and terminates sperm transfer. Hence, one simple function of the spermatophylax is to ensure complete sperm transfer by distracting the female from prematurely removing the ampulla. However, the majority of orally active components of the spermatophylax itself and their subsequent effects on female behavior have not been identified. Here, we report the first analysis of the proteome of the G. sigillatus spermatophylax and the transcriptome of the male accessory glands that make these proteins. The accessory gland transcriptome was assembled into 17,691 transcripts whilst about 30 proteins were detected within the mature spermatophylax itself. Of these 30 proteins, 18 were encoded by accessory gland encoded messages. Most spermatophylax proteins show no similarity to proteins with known biological functions and are therefore largely novel. A spermatophylax protein shows similarity to protease inhibitors suggesting that it may protect the biologically active components from digestion within the gut of the female recipient. Another protein shares similarity with previously characterized insect polypeptide growth factors suggesting that it may play a role in altering female reproductive physiology concurrent with fertilization. Characterization of the spermatophylax proteome provides the first step in identifying the genes encoding these proteins in males and in understanding their biological functions in the female recipient.

Carbonic Anhydrase Activity Monitored In Vivo by Hyperpolarized 13C-Magnetic Resonance Spectroscopy Demonstrates Its Importance for pH Regulation in Tumors

Carbonic anhydrase buffers tissue pH by catalyzing the rapid interconversion of carbon dioxide (CO2) and bicarbonate (HCO3 (-)). We assessed the functional activity of CAIX in two colorectal tumor models, expressing different levels of the enzyme, by measuring the rate of exchange of hyperpolarized (13)C label between bicarbonate (H(13)CO3(-)) and carbon dioxide ((13)CO2), following injection of hyperpolarized H(13)CO3(-), using (13)C-magnetic resonance spectroscopy ((13)C-MRS) magnetization transfer measurements. (31)P-MRS measurements of the chemical shift of the pH probe, 3-aminopropylphosphonate, and (13)C-MRS measurements of the H(13)CO3(-)/(13)CO2 peak intensity ratio showed that CAIX overexpression lowered extracellular pH in these tumors. However, the (13)C measurements overestimated pH due to incomplete equilibration of the hyperpolarized (13)C label between the H(13)CO3(-) and (13)CO2 pools. Paradoxically, tumors overexpressing CAIX showed lower enzyme activity using magnetization transfer measurements, which can be explained by the more acidic extracellular pH in these tumors and the decreased activity of the enzyme at low pH. This explanation was confirmed by administration of bicarbonate in the drinking water, which elevated tumor extracellular pH and restored enzyme activity to control levels. These results suggest that CAIX expression is increased in hypoxia to compensate for the decrease in its activity produced by a low extracellular pH and supports the hypothesis that a major function of CAIX is to lower the extracellular pH.

In vivo evaluation of battery-operated light-emitting diode-based photodynamic therapy efficacy using tumor volume and biomarker expression as endpoints

In view of the increase in cancer-related mortality rates in low- to middle-income countries (LMIC), there is an urgent need to develop economical therapies that can be utilized at minimal infrastructure institutions. Photodynamic therapy (PDT), a photochemistry-based treatment modality, offers such a possibility provided that low-cost light sources and photosensitizers are available. In this proof-of-principle study, we focus on adapting the PDT light source to a low-resource setting and compare an inexpensive, portable, battery-powered light-emitting diode (LED) light source with a standard, high-cost laser source. The comparison studies were performed in vivo in a xenograft murine model of human squamous cell carcinoma subjected to 5-aminolevulinic acid-induced protoporphyrin IX PDT. We observed virtually identical control of the tumor burden by both the LED source and the standard laser source. Further insights into the biological response were evaluated by biomarker analysis of necrosis, microvessel density, and hypoxia [carbonic anhydrase IX (CAIX) expression] among groups of control, LED-PDT, and laser-PDT treated mice. There is no significant difference in the percent necrotic volume and CAIX expression in tumors that were treated with the two different light sources. These encouraging preliminary results merit further investigations in orthotopic animal models of cancers prevalent in LMICs.

CA9 overexpression is an independent favorable prognostic marker in intrahepatic cholangiocarcinoma

The aim of this study is to evaluate the expression of carbonic anhydrase IX (CA9) and to identify its prognostic significance in intrahepatic cholangiocarcinoma (IHCC). We performed immunohistochemistry (IHC) for CA9 in a total of 85 IHCCs. CA9 overexpression was observed in 38 of 85 (44.7%) IHCCs. CA9 overexpression was related to tumors with intraductal growth than mass forming or periductal infiltrative type. CA9 overexpression was more observed in tumors with well/moderate differentiation than poor differentiation and without lymph node metastasis. No significant correlation was observed in CA9 overexpression with tumor size, pT, stage and lymphovascular invasion. Intrahepatic cholangiocarcinomas with CA9 overexpression showed better overall survival than that without expression (P = 0.001). In multivariate analysis, lymph node metastasis (95% CI: 2.103 (1.167-3.791), P = 0.013) was an independent poor prognostic factor. IHCC with CA9 overexpression showed a 0.5-fold (95% confidence interval, 0.328-0.944) lower risk of death compared with those of no or weak expression. CA9 overexpression was related to histologic differentiation and an independent good prognostic factor.

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.

Prognostic relevance of carbonic anhydrase IX expression is distinct in various subtypes of breast cancer and its silencing suppresses self-renewal capacity of breast cancer cells

PURPOSE

Carbonic anhydrase IX (CAIX) is a hypoxia-inducible enzyme with extracellular catalytic domain that is overexpressed in a variety of cancers including breast cancer and plays a crucial role in maintaining favourable intracellular pH and reducing extracellular pH. The purpose of the current study was to elucidate the prognostic significance of CAIX in the intrinsic subtypes of breast cancer and to characterise CAIX as a drug target in breast cancer.

METHODS

The prognostic significance of CAIX mRNA expression was interrogated in a cohort of 3,455 breast tumours by using an online tool, Kaplan-Meier plotter. The functional effects of stable CAIX depletion by shRNA in three breast cancer cell lines—MDA-MB-231, MCF7 and SKBR-3, representing basal-like, luminal A and HER2+ subtypes, respectively—were studied by proliferation, invasion, clonal spheroid formation and chemosensitivity assays under normoxia and hypoxia. Finally, the effect of pharmacological CA inhibition alone or in the combination with doxorubicin on self-renewal was assessed by spheroid-forming assay.

RESULTS

High CAIX mRNA expression was significantly associated with poor survival in patients with basal-like, luminal B and triple-negative breast cancer, but not luminal A and HER+ subtypes. Silencing of CAIX expression had no significant effect on the cell proliferation or viability upon treatment with doxorubicin in any of the cell lines studied, while it inhibited spheroid formation in hypoxic conditions. Furthermore, pharmacological inhibition of CAs using acetazolamide had a synergistic effect with doxorubicin on decreasing the spheroid-forming efficiency in MDA-MB-231 cells.

CONCLUSIONS

Inhibition of CAIX reduces the self-renewal capacity of breast cancer cells, and the combination of doxorubicin and CAIX inhibition is an attractive therapeutic strategy in basal-like and triple-negative breast cancer, which warrants further investigations.

Synthesis and evaluation of (18)F-labeled tertiary benzenesulfonamides for imaging carbonic anhydrase IX expression in tumours with positron emission tomography

Three tertiary benzenesulfonamide inhibitors 4a-c were radiolabeled with (18)F and evaluated for imaging carbonic anhydrase IX (CA IX) expression with positron emission tomography. All three inhibitors exhibit <10 nM affinity for CA IX with no measurable affinity for CA II. Despite good affinity/selectivity to CA IX and excellent stability in plasma, uptake of [(18)F]4a-c in CA IX-expressing HT-29 tumours was low without significant contrast. [(18)F]4a,b were excreted rapidly, while [(18)F]4c exhibited significant in vivo defluorination leading to high bone uptake. Due to minimal uptake in HT-29 tumours compared to normal organs/tissues, (18)F-labeled benzenesulfonamides [(18)F]4a-c are not suitable as CA IX imaging agents.

Expression of cell metabolism-related genes in different molecular subtypes of triple-negative breast cancer

AIMS AND BACKGROUND

We evaluated the difference in and significance of cancer cell metabolism by molecular subtyping of triple-negative breast carcinoma.

METHODS

Tissue microarrays from 122 surgical specimens of triple-negative breast carcinoma patients and immunohistochemical staining for CK5/6, epidermal growth factor receptor, claudin 3, claudin 4, claudin 7, E-cadherin, androgen receptor, and gamma-glutamyltransferase 1 were used to classify triple-negative breast carcinoma as follows: basal-like type, molecular apocrine type, claudin low type, mixed type and null type. In addition, immunohistochemical staining for metabolism-related proteins such as c-myc, insulin-like growth factor (g)-1, hypoxia-inducible factor 1-1α, glucose transporter 1, carbonic anhydrase IX antibody, macrophage migration inhibitory factor, and pyruvate dehydrogenase kinase 1 was used to compare the differences according to molecular subtype and clinicopathological factors.

RESULTS

The basal-like type showed the highest proportion of high glucose transporter 1 expression (P = 0.049) and carbonic anhydrase IX antibody expression (P = 0.008). Hypoxia-inducible factor 1-1α expression was associated with lymph node metastasis (P = 0.001) and central fibrotic zone (P = 0.012), and high glucose transporter 1 expression was related to high histologic grade (P = 0.007), cytokeratin 5/6 positivity (P = 0.002), and central fibrotic zone (P = 0.017). Finally, carbonic anhydrase IX antibody was associated with cytokeratin 5/6 positivity (P = 0.001) and central fibrotic zone (P = 0.048).

CONCLUSIONS

Our study revealed the different characteristics of cancer cell metabolism according to the molecular subtypes of triple-negative breast carcinoma. Among them, basal-like type was the most glycolytic and acid-resistant phenotype.

Clear cell papillary renal cell carcinoma: a clinicopathological study emphasizing ultrastructural features and cytogenetic heterogeneity

Clear cell papillary renal cell carcinoma (CCPRCC) is a recently recognized renal neoplasm, which was initially described in end-stage renal disease (ESRD), but some cases have been reported in otherwise normal kidneys. We report a series of 11 CCPRCC (age range, 33-72 years; male-to-female ratio, 8:3). Follow-up was available for 8 patients. No patients developed local recurrence, distant or lymph-node metastasis, or cancer death. Histologically, all tumors exhibit morphologic features typical of CCPRCC including a mixture of cystic and papillary components, covered by small to medium-sized cuboidal cells with abundant clear cytoplasm. All 11 cases exhibited moderate to strong positivity for CK7, CA9, Vim, and HIF-1α, coupled with negative reactions for CD10, P504S, and RCC. We did not find any VHL gene mutations in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases. Ultrastructurally, the tumor cells composed of numerous glycogens with scanty cell organelles, reminiscent of clear cell renal cell carcinoma (CCRCC). In conclusion, the coexpression of CA9 and HIF-1α in the absence of VHL gene abnormalities in CCPRCC suggests activation of the HIF pathway by mechanisms independent of VHL gene mutation. Losses of chromosomes 3 (monosomies chromosome 3) was detected in 3 cases suggesting that at least some of these lesions have demonstrated abnormalities of chromosomes 3. Ultrastructurally, CCPRCC composed of numerous glycogens with scanty cell organelles, reminiscent of CCRCC suggesting the close pathogenesis relationship of CCPRCC with CCRCC.

Quantification of extracellular carbonic anhydrase activity in two marine diatoms and investigation of its role

Many microalgae induce an extracellular carbonic anhydrase (eCA), associated with the cell surface, at low carbon dioxide (CO2) concentrations. This enzyme is thought to aid inorganic carbon uptake by generating CO2 at the cell surface, but alternative roles have been proposed. We developed a new approach to quantify eCA activity in which a reaction-diffusion model is fit to data on (18)O removal from inorganic carbon. In contrast to previous methods, eCA activity is treated as a surface process, allowing the effects of eCA on cell boundary-layer chemistry to be assessed. Using this approach, we measured eCA activity in two marine diatoms (Thalassiosira pseudonana and Thalassiosira weissflogii), characterized the kinetics of this enzyme, and studied its regulation as a function of culture pH and CO2 concentration. In support of a role for eCA in CO2 supply, eCA activity specifically responded to low CO2 rather than to changes in pH or HCO3(-), and the rates of eCA activity are nearly optimal for maintaining cell surface CO2 concentrations near those in the bulk solution. Although the CO2 gradients abolished by eCA are small (less than 0.5 μm concentration difference between bulk and cell surface), CO2 uptake in these diatoms is a passive process driven by small concentration gradients. Analysis of the effects of short-term and long-term eCA inhibition on photosynthesis and growth indicates that eCA provides a small energetic benefit by reducing the surface-to-bulk CO2 gradient. Alternative roles for eCA in CO2 recovery as HCO3(-) and surface pH regulation were investigated, but eCA was found to have minimal effects on these processes.

Pattern of CAIX expression is prognostic for outcome and predicts response to ARCON in patients with laryngeal cancer treated in a phase III randomized trial

BACKGROUND AND PURPOSE

In a phase III trial in patients with advanced stage laryngeal carcinoma comparing ARCON (accelerated radiotherapy with carbogen breathing and nicotinamide) to accelerated radiotherapy alone (AR) the prognostic and predictive value of CAIX, a hypoxia-associated protein, was investigated.

MATERIAL AND METHODS

261 Paraffin embedded tumor biopsies and 79 fresh frozen biopsies from patients entered in the trial were immunohistochemically stained for CAIX. CAIX-fraction and CAIX expression pattern were related to tumor control and patient survival.

RESULTS

Low CAIX-fraction was prognostic for worse regional control and overall survival in patients treated with AR. Patients with a low CAIX-fraction treated with ARCON had better regional control and metastasis-free survival compared to AR (RC 97% vs 71%, p < 0.01 and MFS 92% vs 69%, p = 0.06). Patients with a perinecrotic CAIX staining pattern had a significantly worse local control, metastasis-free and overall survival compared to patients with a diffuse pattern (65% vs 84%, p = 0.01, 70% vs 96%, p < 0.01 and 42% vs 71%, p < 0.01 respectively), and this could not be improved with ARCON. After multivariate analysis CAIX pattern and N-stage emerged as significant predictors for metastasis-free survival and overall survival.

CONCLUSIONS

ARCON improves regional control and metastasis-free survival only in patients with low CAIX expression. The different patterns of CAIX expression suggest different mechanisms of upregulation and have important prognostic value.

Hypoxia inducible factor-1 alpha and carbonic anhydrase IX overexpression are associated with poor survival in breast cancer patients

PURPOSE

Hypoxia is common in many solid tumors such as breast, head-neck, and soft tissue malignancies. Hypoxia causes overexpression of hypoxia inducible factor-1 alpha (HIF-1α) and carbonic anhydrase IX (CA IX) which are associated with unfavorable prognosis in breast cancer. In our study, we evaluated HIF-1α and CA IX expression in patients with breast cancer.

METHODS

Between June 1996 and June 2008, 111 women with breast cancer were evaluated. Estrogen receptor (ER) and progesterone receptor (PR) status and Her2/ neu expression were evaluated by immunohistochemical methods. Her-2/neu expression was also assessed by FISH method when needed. Two groups were created: ER and PR positive, Her-2/neu negative (group 1, n=56); and ER and PR negative, Her-2/neu positive (group 2, n=55). HIF-1α and CA IX expressions were investigated in both groups and results were compared. In addition, we investigated the association between HIF-1α and CA IX expressions with stage, grade, lymph node metastasis, tumor size, menopause status and survival.

RESULTS

Median patient age in group 1 was 52 years (range 34-77), and in group 2 47 years (range 27-83). HIF-1α expression was detected in 26 (46.4%) of group 1 and in 46 (83.6%) of group 2 patients (p=0.0001). CA IX expression was detected in 25 (46.4%) of group 1 and in 37 (67.3%) of group 2 patients (p7equals;0.0137rpar;. In group 1, median disease free survival (DFS) was 97 months and in group 2 46 months (p=0.0308). In group 1, median overall survival (OS) was 108 months and in group 2 75 months (p=0.0339).

CONCLUSION

HIF-1α and CA IX overexpressions are observed more often in ER and PR negative, Her-2/neu positive breast cancer and are associated with poor survival.

Clock genes show circadian rhythms in salivary glands

Circadian rhythms are endogenous self-sustained oscillations with 24-hour periods that regulate diverse physiological and metabolic processes through complex gene regulation by "clock" transcription factors. The oral cavity is bathed by saliva, and its amount and content are modified within regular daily intervals. The clock mechanisms that control salivary production remain unclear. Our objective was to evaluate the expression and periodicity of clock genes in salivary glands. Real-time quantitative RT-PCR, in situ hybridization, and immunohistochemistry were performed to show circadian mRNA and protein expression and localization of key clock genes (Bmal1, Clock, Per1, and Per2), ion and aqua channel genes (Ae2a, Car2, and Aqp5), and salivary gland markers. Clock gene mRNAs and clock proteins were found differentially expressed in the serous acini and duct cells of all major salivary glands. The expression levels of clock genes and Aqp5 showed regular oscillatory patterns under both light/dark and complete-dark conditions. Bmla1 overexpression resulted in increased Aqp5 expression levels. Analysis of our data suggests that salivary glands have a peripheral clock mechanism that functions both in normal light/dark conditions and in the absence of light. This finding may increase our understanding of the control mechanisms of salivary content and flow.

Immunogold labeling of carbonic anhydrase isozyme (CA-VI) in secretory granules of human parotid glands

Serous granules in the human parotid gland have a well-defined substructure, consisting of a dense spherule suspended in a moderately dense matrix. Immunogold labeling with an antibody against carbonic anhydrase VI revealed that this enzyme is localized within the matrix and is absent from the spherule. This location matches that of a number of other salivary gland proteins. Cell organelles involved in the secretory pathway are devoid of label. Labeling was not observed in any ductular component of the gland.

Effects of atrazine on the gill cells and ionic balance in a neotropical fish, Prochilodus lineatus

The effects of the herbicide atrazine on the gill of the freshwater fish Prochilodus lineatus were evaluated after exposure of fish to 2, 10 and 25 μg L(-1) atrazine during 48 h (acute exposure) and 14 d (subchronic exposure). Ions and osmolality were measured in plasma and gill samples were taken to determine the Na(+)/K(+)-ATPase (NKA) and carbonic anhydrase (CA) activities and for morphological analysis. Plasma osmolality and Na(+) and Cl(-) ions changed depending on atrazine concentration, but atrazine exposure had no effect on the Na(+)/Cl(-) ratio. NKA activity did not change after atrazine exposure, but CA activity decreased in fish exposed to 25 μg L(-1) for 14 d. Gill MRC density decreased after acute exposure but did not change in fish exposed to the subchronic treatment. The MRC density at the epithelial surface increased in fish exposed to 25 μg L(-1), and the MRC fractional area (MRCFA) increased in fish exposed to 10 μg L(-1). The changes in MRCs provide evidence of morphological adjustments to maintain ionic homeostasis in spite of the inhibition of CA activity at the highest atrazine concentration.

Radiosynthesis of three [11C]ureido-substituted benzenesulfonamides as PET probes for carbonic anhydrase IX in tumors

Three ureido-substituted benzenesulfonamides 1a-c have been developed as potent inhibitors for carbonic anhydrase IX, which is overexpressed in hypoxic tumors. In this study, we labeled these unsymmetrical ureas 1a-c using [(11)C]phosgene ([(11)C]COCl(2)) as a labeling agent with the expectation that [(11)C]1a-c could become promising positron tomography probes for imaging carbonic anhydrase IX in tumors. The strategy for radiosynthesis of [(11)C]1a-c was to react hydrochloride of anilines 2a-c with [(11)C]COCl(2) to give isocyanate [(11)C]4a-c, followed by a reaction with 4-aminobenzenesulfonamide (3).

Potential of poly(styrene-co-divinylbenzene) monolithic columns for the LC-MS analysis of protein digests

Two polystyrene-based capillary monolithic columns of different length (50 and 250 mm) were used to evaluate the effects of column length on gradient separation of protein digests. A tryptic digest of a 9-protein mixture was used as a test sample. Peak capacities were determined from selected extracted ion chromatograms, and tandem mass spectrometry data were used for database matching using the MASCOT search engine. Peak capacities and protein identification scores were higher for the long column with all gradients. Peak capacities appear to approach a plateau for longer gradient times; maximum peak capacity was estimated to be 294 for the short column and 370 for the long column. Analyses with similar gradient slope produced a ratio of the peak capacities of 3.36 for the long and the short column, which is slightly higher than the expected value of the square root of the column length ratio. The use of a longer monolith improves peptide separation, as reflected by higher peak capacity, and also increases protein identification, as observed from higher identification scores and a larger number of identified peptides. Attention has also been paid to the peak production rate (PPR, peak capacity per unit time). For short analysis times, the short column produces a higher PPR, while for analysis times longer than 40 min, the PPR of the 250-mm column is higher.

Potential biomarkers of temporomandibular joint disorders

PURPOSE

The purpose of this study was to identify protein markers present in subjects with temporomandibular joint disorders (TMDs) and clicking compared with the levels in controls.

MATERIALS AND METHODS

This was a pilot case-control study, and we report the preliminary results. Samples of joint aspirate collected from patients with TMDs and controls who had undergone surgery for a problem other than TMDs were analyzed using isobaric tags for relative and absolute quantitation (iTRAQ) and biotin-labeled-based protein arrays. The data obtained from these techniques were used to identify the proteins of interest, which were then quantitated using enzyme-linked immunosorbent assay (ELISA). The patient samples studied included joint aspirate collected clinically from the controls and patients and included samples from both the right and the left sides of each patient with a TMD.

RESULTS

The 8 TMJ aspirate samples from 6 subjects included 5 aspirate samples from 4 patients and 3 from 2 controls. The greatest standardized protein concentration of endocrine gland-derived vascular endothelial growth factor/prokineticin-1 (EG-VEGF/PK1) and D6 was found in both joints of the controls compared with the levels from the joints of the patients. With 1 exception, the standardized protein concentration was significantly lower in the patients than in the controls. The lower levels of EG-VEGF/PK1 and D6 in the patients compared with the controls suggest that these cytokines might be possible biomarkers for TMDs.

CONCLUSION

In the present pilot study, greater levels of EG-VEGF/PK1 and D6 were found in the controls than in the patients with TMDs. Proteomic analysis of the proteins present in the diseased joints compared with those in the controls might help to identify proteins present when pain or degeneration of the joint occurs. The proteomic information might be useful in the development of future therapies.

Immunoaffinity enrichment and liquid chromatography-selected reaction monitoring mass spectrometry for quantitation of carbonic anhydrase 12 in cultured renal carcinoma cells

Liquid chromatography-selected reaction monitoring (LC-SRM) is a highly specific and sensitive mass spectrometry (MS) technique that is widely being applied to selectively qualify and validate candidate markers within complex biological samples. However, in order for LC-SRM methods to take on these attributes, target-specific optimization of sample processing is required, in order to reduce analyte complexity, prior to LC-SRM. In this study, we have developed a targeted platform consisting of protein immunoaffinity enrichment on magnetic beads and LC-SRM for measuring carbonic anhydrase 12 (CA12) protein in a renal cell carcinoma (RCC) cell line (PRC3), a candidate biomarker for RCC whose expression at the protein level has not been previously reported. Sample processing and LC-SRM assay were optimized for signature peptides selected as surrogate markers of CA12 protein. Using LC-SRM coupled with stable isotope dilution, we achieved limits of quantitation in the low fmol range sufficient for measuring clinically relevant biomarkers with good intra- and interassay accuracy and precision (≤17%). Our results show that using a quantitative immunoaffinity capture approach provides specific, accurate, and robust assays amenable to high-throughput verification of potential biomarkers.

Bidirectional influences of acetazolamide on central nervous system oxygen toxicity of rats

Central nervous system oxygen toxicity, which occurs during diving and hyperbaric oxygen treatment, can lead to very dangerous situations, and it is of great importance to explore its mechanisms. We have speculated that cerebral blood flow plays a pivotal role in its occurrence. Except for acting as an anticonvulsant in clinical applications, acetazolamide is also a vasodilator used in both clinical and laboratory settings. In this study, when acetazolamide from 5 to 500 ug/kg body weight was administered by intracerebroventricular injection, the latency of central nervous system oxygen toxicity detected by electroencephalogram recording in rats subjected to hyperbaric oxygen at 6 atmospheres absolute was prolonged significantly. On the contrary, when the dose of intracerebroventricular injection achieved 5,000 ug/kg body weight, acetazolamide shortened the latency significantly. Intraperitoneal injection of acetazolamide more than 7.5 mg/kg body weight also shortened the latency significantly. Results also showed both intracerebroventricular injection of acetazolamide at a dose of 5,000 ug/kg body weight and intraperitoneal injection at dose of 7.5 mg/kg body weight inhibited the activity of carbonic anhydrase and increased the cerebral blood flow significantly, which helped aggravate oxidation damage and resulted in increased MDA and impaired glutathione peroxidase in brain tissue. But intracerebroventricular injection of acetazolamide at 5 ug/kg body weight had no effect on MDA and glutathione peroxidase, though it inhibited the activity of carbonic anhydrase. These observations indicated acetazolamide covers bidirectional influences on central nervous system oxygen toxicity. Within local brain tissue, especially neurons, it could exert its anticonvulsive effect on the central nervous system at low doses. On the other hand, under high doses, it would display its convulsive-hastening effect through increasing cerebral blood flow to aggravate the oxidation state of brain tissues and exacerbate central nervous system oxygen toxicity when subjected to hyperbaric oxygen. Blood flow of brain plays a pivotal role in central nervous system oxygen toxicity.

Loss of the transit peptide and an increase in gene expression of an ancestral chloroplastic carbonic anhydrase were instrumental in the evolution of the cytosolic C4 carbonic anhydrase in Flaveria

C(4) photosynthesis has evolved multiple times from ancestral C(3) species. Carbonic anhydrase (CA) catalyzes the reversible hydration of CO(2) and is involved in both C(3) and C(4) photosynthesis; however, its roles and the intercellular and intracellular locations of the majority of its activity differ between C(3) and C(4) plants. To understand the molecular changes underlying the evolution of the C(4) pathway, three cDNAs encoding distinct beta-CAs (CA1, CA2, and CA3) were isolated from the leaves of the C(3) plant Flaveria pringlei. The phylogenetic relationship of the F. pringlei proteins with other embryophyte beta-CAs was reconstructed. Gene expression and protein localization patterns showed that CA1 and CA3 demonstrate high expression in leaves and their products localize to the chloroplast, while CA2 expression is low in all organs examined and encodes a cytosolic enzyme. The roles of the F. pringlei enzymes were considered in light of these results, other angiosperm beta-CAs, and Arabidopsis (Arabidopsis thaliana) "omics" data. All three F. pringlei CAs have orthologs in the closely related C(4) plant Flaveria bidentis, and comparisons of ortholog sequences, expression patterns, and intracellular locations of their products indicated that CA1 and CA2 have maintained their ancestral role in C(4) plants, whereas modifications to the C(3) CA3 gene led to the evolution of the CA isoform that catalyzes the first step in the C(4) photosynthetic pathway. These changes included the loss of the chloroplast transit peptide and an increase in gene expression, which resulted in the high levels of CA activity seen in the cytosol of C(4) mesophyll cells.

Carbonic anhydrase IX and response to postmastectomy radiotherapy in high-risk breast cancer: a subgroup analysis of the DBCG82 b and c trials

INTRODUCTION

A significant survival improvement after postmastectomy radiotherapy was identified in the Danish Breast Cancer Cooperative Group (DBCG82) b and c studies and in the British Columbia Randomized Radiation Trial. Recently, potential predictive value regarding response to postmastectomy radiotherapy was reported for carbonic anhydrase (CA) IX in a study (reported in abstract form) that included 160 patients. The purpose of the present study was to examine the importance of CA IX to response to postmastectomy radiotherapy in the larger scaled DBCG82 b and c studies.

METHODS

The DBCG82 b and c studies included 3,083 high-risk Danish breast cancer patients. The women were randomly assigned to postmastectomy radiotherapy plus systemic therapy (cyclophosfamide, methotrexate and fluorouracil in premenopausal women; and tamoxifen in postmenopausal women) or to systemic therapy alone. Cores from invasive tumour-containing paraffin blocks from 1,000 patients (more than seven nodes surgically removed) were transferred to tissue microarrays. Tissue microarray sections were stained immunohistochemically for CA IX (M75). The median follow up for patients remaining alive was 17 years. Clinical end-points were loco-regional recurrence, distant metastases, disease-specific survival and overall survival. Statistical analyses included kappa statistics, chi2 or exact tests, Kaplan-Meier probability plots, Log-rank test and Cox regression analyses.

RESULTS

CA IX was assessable in 945 cores. The percentage of tumours positive for CA IX was 16% (> or = 10% invasive tumour staining). CA IX was not an independent prognostic marker for survival, distant metastases, or locoregional recurrence in the subgroup of 945 patients or within either of the two randomization arms. In subgroup analyses, however, CA IX was an independent prognostic marker for overall survival among postmenopausal women (P = 0.001), women with one to three positive nodes (P = 0.02) and hormone receptor positive women (P = 0.001). Fifteen-year probabilities of overall survival were improved by 9% and 7% after postmastectomy radiotherapy for the subgroups of CA IX negative and CA IX positive patients, respectively.

CONCLUSION

Within this series of 945 high-risk premenopausal and postmenopausal women, positivity for CA IX was not overall an independent prognostic marker for survival; only in subgroup analyses was it found to have prognostic value. The improvement in 15-year survival after postmastectomy radiotherapy was of similar magnitude in the two subgroups of CA IX positive and CA IX negative patients.

[Physiological role of carbonic anhydrase isozymes and their distribution in ruminant gastrointestinal tract]

New data on physical-chemical characteristics, biochemical properties and functional specificity of carbonic anhydrase isozymes of human and animals are reviewed. The recent literature information about the tissue composition and regional distribution of isozymes of carbonic anhydrase in the ruminant gastrointestinal tract is generalized. The participation of carbonic anhydrase isozymes in the regulation of acid-base balance in the organism of ruminants is considered.

Testosterone-stimulated growth of the rat prostate may be driven by tissue hypoxia and hypoxia-inducible factor-1alpha

Testosterone-stimulated growth of the ventral prostate (VP) in castrated rats is preceded by angiogenesis, but the mechanisms coordinating vascular and tissue growth are unknown. Adult rats were castrated and some treated with testosterone. Tissue hypoxia was studied morphologically using the hypoxia marker pimonidazole (Hypoxyprobe), hypoxia-inducible factor-1 (HIF-1) alpha, vascular endothelial growth factor (VEGF), and carbonicanhydrase 9 (CA-9) levels by western blotting and quantitative RT-PCR. In the intact untreated prostate, most glands were unstained by the hypoxia marker but already 1 day after castration most epithelial cells in the VP were stained. Seven days after castration prostate glands were apparently normoxic again, and HIF-1alpha, VEGF, and CA-9 were decreased. Treatment of 7-day castrated rats with testosterone resulted in increased epithelial hypoxyprobe staining and increased HIF-1alpha, VEGF, and CA-9 levels. The transient increase in tissue hypoxia after testosterone treatment is probably caused by a temporary mismatch between oxygen consumption and supply. Treatment of prostate epithelial cells in vitro under normoxic conditions also increased HIF-1alpha, and this could be blocked if epidermal growth factor receptor (EGFR) signaling was blocked with gefitinib. In vivo gefitinib could, however, not block the testosterone induced increase in HIF-1alpha. Testosterone may thus induce HIF-1alpha and its downstream angiogenesis promoting genes by at least two mechanisms, hypoxia and EGFR signaling. Transient epithelial cell hypoxia could by rapidly increasing HIF-1alpha and VEGF be an essential coordinator of testosterone-stimulated vascular and glandular growth.

Gene expression of secretory carbonic anhydrase isozymes in striated ducts of canine salivary glands using laser microdissection system

To clarify whether striated duct cells in canine salivary glands synthesize secretory carbonic anhydrase (CA-VI), as is the case with serous acinar cells, the present study utilized laser microdissection to harvest striated duct cells from canine parotid and submandibular glands, and total RNA extracted from these cells was then amplified by reverse transcription-polymerase chain reaction to assess CA-VI gene expression. The results confirmed the local expression of CA-VI mRNA in striated duct cells. This clarified that, in canine salivary glands, CA-VI is synthesized in not only serous acinar cells, but also striated duct cells.

Hypoxia-inducible expression of the mouse carbonic anhydrase IX demonstrated by new monoclonal antibodies

CA IX is a transmembrane carbonic anhydrase isoenzyme predominantly expressed in human tumors in response to hypoxia and functionally implicated in adaptation of tumor cells to hypoxic stress via control of pH and cell adhesion. Intense investigations of the human CA IX as a hypoxic marker and a therapeutic target have been facilitated by specific monoclonal antibodies. However, no such reagents existed for the mouse CA IX ortholog. We generated five new anti-mouse CA IX monoclonal antibodies AM1-4, AM4-3, AM27-4, AM34-7 and AM35-1 produced using CA IX-deficient mice. The antibodies are suitable for various immunodetection methods including immunoblotting and immunohistochemistry. Using these reagents we show that the mouse CA IX is expressed in three out of nine tested mouse cell lines, namely in L929, MEF and TSA and is regulated by hypoxia and cell density similarly to human CA IX. We also demonstrate that the mouse CA IX exhibits hypoxia-related expression pattern in multicellular spheroids and in tumor xenografts. Our results indicate the use of the mouse model as suitable for further studies of CA IX role in tumor development and for its pre-clinical investigations. The new monoclonal antibodies represent potent tools for accomplishment of these future studies.

Use of stable isotopically enriched proteins and directly coupled high-performance liquid chromatography inductively coupled plasma mass spectrometry for quantitatively monitoring the transfer of metals between proteins

Studies have shown that metallothionein (MT) may play an important role in modulating the activity of certain Zn-regulated enzymes under various oxidoreductive conditions by either donating or removing Zn. To better determine the role of MT in interprotein metal transfer, we describe a procedure that uses stable isotopically enriched (67)Zn(7) metallothionein 2 ((67)Zn(7)-MT-2) to quantitatively determine the stoichiometry of transfer of Zn from the protein to a recipient apo-metalloenzyme, apo-carbonic anhydrase (apo-CA) by directly coupled ion exchange high-performance liquid chromatography inductively coupled plasma mass spectrometry. Quantitatively, the transfer of (67)Zn was consistent with the enzymatic activation of the apo-enzyme as judged by its esterase activity and ability to cleave p-nitrophenyl acetate. Maximum enzyme activation occurred at an MT-2:apo-CA molar ratio of 1, implying the release of a single atom of Zn from MT-2. Preincubation of (67)Zn(7)-MT-2 with an excess of oxidized glutathione (GSSG) increased metal donation fourfold, whereas reduced glutathione (GSH) inhibited donation by approximately 50%. By using multiple recipient and donor proteins having different stable isotopic signatures, the technique has the potential for quantitatively studying the kinetic and thermodynamic aspects of Zn transfer between numerous competing ligands in vitro, an important first step toward understanding the regulatory role of this metal in protein functioning and cellular metabolism in vivo.

Impact of Zn, Cu, and Fe on the activity of carbonic anhydrase of erythrocytes in ducks

The impact of zinc, copper, and iron on the duck erythrocyte carbonic anhydrase (CA) activity and the hemoglobin content in vitro culture were studied. The increase of zinc or iron addition at a low level induced the rise of CA activity, and the CA activity was inhibited by zinc or iron at a high addition level. The duck erythrocyte CA was strongly inhibited by cupric ion. The inhibition constant of duck erythrocyte CA to cupric ion is about 3.5 microM. Carbonic anhydrase compared to hemoglobin is more sensitive to zinc and copper in the environment. These findings suggest that some characteristics of duck erythrocyte CA are different from both CAI and CAII of mammals. The increase of Fe addition below 8 microM in the minimal essential medium brought about the rise of CA activity and resulted in the maximum of CA activity exceeding that induced by Zn. It provided a new evidence for the role of ferrous ion in CA.

Detecting changes in tumor hypoxia with carbonic anhydrase IX and pimonidazole

We have used immunohistochemistry to examine the dynamics of tumor hypoxia.. Expression of CAIX is known to be influenced by tumor hypoxia, and this protein has been shown to be an endogenous hypoxia marker in several models. However, due to its long half-life, it could also be present in oxygenated tissue that had recently been hypoxic. To investigate this issue we have compared CAIX expression to the exogenous hypoxia marker, pimonidazole using HT29 (human colorectal cancer) xenografts. We manipulated tumor hypoxia with carbogen and hydralazine, treatments that respectively increased and decreased tumor oxygenation. (Carbogen was given 75 minutes and hydralazine 30 minutes before sacrifice). In tumors from the control group, CAIX and pimonidazole exhibited similar (though not identical) spatial distribution, and for both markers, the fraction of the section staining positively was similar (13.2% and 12.6% respectively). The mice treated with hydralazine showed a significant increase in pimonidazole accumulation (37.2%, p = 0.03), though the CAIX positive fraction was unchanged (14.2%). In contrast, in the carbogen group pimonidazole staining decreased to 3% (p = 0.01) though CAIX expression was again unaltered. These results suggest that comparison of CAIX and pimonidazole will allow for the detection of reoxygenation.

In vivo effects of oral contraceptives on paraoxonase, catalase and carbonic anhydrase enzyme activities on mouse

Many effects that oestrogens and progestrogens used in oral contraceptive (OC) have on enzyme physiology are of importance on homeostasis. This study was carried out in order to determine the in vivo effect of three oral contraceptives containing ethinyl estradiol in combination with desogestrel and levonorgestrel on the paraoxonase (PON), catalase (CAT) and carbonic anhydrase (CA) activities in mice, which are model organisms for humans. Serum and liver paraoxonase activities were determined spectrophotometrically by using paraoxan as a substrate according to the methods of Gan et al. and Gil et al., respectively. Catalase and carbonic anhydrase activities were determined from erythrocytes used Aebi and Maren methods, respectively. For these studies, a group of ten mice (25+/-2 g) was selected for oral administration for 21 d of each drug (0.15 mg desogestrel+0.03 mg ethinylestradiol (A); 0.15 mg levanogestrel+0.03 mg ethinylestradiol (B) and 0.15 mg desogestrel+0.02 mg ethinylestradiol (C)). A group of ten mice was included in the study for a control group, which were not subject to drug administration. For each drug, a mean of the serum and liver paraoxonase activity and erythrocytes catalase and carbonic anhydrase activities were determined and compared to the control groups. While mouse liver PON activity showed a statistically significant decrease for all three drugs, serum PON activity increased. Erythrocytes catalase activity was significantly decreased by all contraceptives used. On the other hand, these contraceptives did not change the erythrocytes carbonic anhydrase activity.

Sheath-flow cuvette for high-sensitivity laser-induced fluorescence detection in capillary electrophoresis

The sheath-flow cuvette is a key component in a high-sensitivity post-column laser-induced fluorescence detector for capillary electrophoresis. Most designs are based on commercial cuvettes originally manufactured for use in a flow cytometer. In these devices, a quartz flow chamber is held in a stainless-steel fixture that is difficult to machine and subjects the cuvette to a torque when sealed, which frequently leads to damage of the flow chamber. In this report we present a design for a cuvette that may easily be constructed. This design uses compression to hold and seal the quartz flow chamber without applying torque. The system produces detection limits (3sigma) of 115 yoctomoles (70 copies) for FQ-labeled carbonic anhydrase.

MN/CA9: a potential gene marker for detection of malignant cells in effusions

Many cancers cause malignant effusions. The presence of malignant cells in effusions has implications in diagnosis, tumour staging and prognosis. The detection of malignant cells currently presents a challenge for cytopathologists. New adjunctive methods are needed. Although the effusions provide excellent materials for molecular assay, the available molecular markers are extremely limited, which hinders its clinical application. MN/CA9 has proved to be a valuable marker in many cancers such as lung, breast, colon, kidney, etc. The present study was to evaluate MN/CA9 as a new molecular marker for the detection of cancer cells in pleural effusions. Seventy-one pleural effusions including 59 malignant effusions from patients with cancer, and 12 patients with benign diseases as a control, were subjected to RT-PCR for detection of MN/CA9 gene expression. MN/CA9 gene expression was detected in 53/59 (89.8%) pleural effusions from cancer patients (15/16 for breast cancers, 10/11 for lung cancers, 4/4 for ovary cancers, 2/3 for colon-rectal cancers, 5/6 for cancers of unknown site, 7/8 for mesothelioma and 10/11 for other cancers). Furthermore, MN/CA9 was positive in 13/18 (72.2%) of cytologically negative effusions of cancer patients. MN/CA9 was detected in only 1/12 (8.3%) effusions from the control patients (p < 0.01). The sensitivity and specificity of MN/CA9 gene expression were, respectively, 89.8% and 91.7%. Our preliminary results suggest that MN/CA9 could be a potential marker for the detection of malignant cells in effusions. A large-scale study is needed to confirm these results.

An investigation into the prognostic significance of necrosis and hypoxia in high grade and invasive bladder cancer

PURPOSE

We investigated hypoxia and necrosis in high grade and invasive bladder cancer, and related this to prognosis.

MATERIALS AND METHODS

We performed a retrospective observational study of 98 primary cystectomy specimens scored for necrosis, and the hypoxia associated markers carbonic anhydrase IX, hypoxia-inducible factor 1 alpha and 2 alpha, and Bcl2/adenovirus EIB 19 kDa interacting protein 3. Tumor tissue array was used with cores taken from representative and perinecrotic tumor regions. Necrosis was scored on whole sections as absent, less than 5 mm (comedo) or more than 5 mm (gross).

RESULTS

Of the 98 cases analyzed followup data were available on 91. Median followup was 22 months (IQR 8-35). Stage was T0/1 to T4 in 18, 20, 41 and 12 cases, respectively. The prevalence of necrosis in bladder cancer was high and it increased with stage (17%, 30%, 70% and 71% at stages T0/1 to T4, respectively). Necrosis was significantly associated with stage (p = 0.0001) and nodal status (p = 0.016). Hypoxia-inducible factor 1 alpha showed no association with stage, grade or nodal status. Hypoxia-inducible factor 1 alpha and carbonic anhydrase IX showed a significant association with necrosis, whereas hypoxia-inducible factor 2 alpha and Bcl2/adenovirus EIB 19 kDa interacting protein 3 did not. Stage (p <0.0001), necrosis (p <0.0001) and intense hypoxia-inducible factor 1 positivity (p = 0.048) were the only significant prognostic factors on univariate analysis. Stage (HR 3.29, 95% CI 1.80-6.04, p <0.001) and necrosis (HR 1.92, 95% CI 1.05-3.51, p = 0.04) were independent prognostic factors on multivariate analysis, while hypoxia-inducible factor 1 lost significance (HR 1.36, 95% CI 0.98-1.88, p = 0.07). Node status was only reported in 45% of cases.

CONCLUSIONS

Necrosis (the presence and amount) in high grade and invasive bladder cancer is an independent prognostic risk factor.

Differing responses of the two forms of photosystem II carbonic anhydrase to chloride, cations, and pH

The effects of Cl(-), Mn(2+), Ca(2+), and pH on extrinsic and intrinsic photosystem II carbonic anhydrase activity were compared. Under the conditions of our in vitro experiments, extrinsic CA activity, located on the OEC33 protein, was optimum at about 30 mM Cl(-), and strongly inhibited above this concentration. This enzyme is activated by Mn(2+) and stimulated somewhat by Ca(2+). The OEC33 showed dehydration activity that is optimum at pH 6 or below. In contrast, intrinsic CA activity found in the PSII complex after removal of extrinsic proteins was stimulated by Cl(-) up to 0.4 M. Ca(2+) appears to be the required cofactor, which implies that the location of the intrinsic CA activity is in the immediate vicinity of the CaMn(4) complex. Up to now, intrinsic CA has shown only hydration activity that is nearly pH independent.