Carbonic anhydrase IX in bladder cancer

CD147 and MCT1-potential partners in bladder cancer aggressiveness and cisplatin resistance

The relapsing and progressive nature of bladder tumors, and the heterogeneity in the response to cisplatin-containing regimens, are the major concerns in the care of urothelial bladder carcinoma (UBC) patients. The metabolic adaptations that alter the tumor microenvironment and thus contribute to chemoresistance have been poorly explored in UBC setting. We found significant associations between the immunoexpressions of the microenvironment-related molecules CD147, monocarboxylate transporters (MCTs) 1 and 4, CD44 and CAIX in tumor tissue sections from 114 UBC patients. The presence of MCT1 and/or MCT4 expressions was significantly associated with unfavorable clinicopathological parameters. The incidence of CD147 positive staining significantly increased with advancing stage, grade and type of lesion, and occurrence of lymphovascular invasion. Similar associations were observed when considering the concurrent expression of CD147 and MCT1. This expression profile lowered significantly the 5-year disease-free and overall survival rates. Moreover, when selecting patients who received platinum-based chemotherapy, the prognosis was significantly worse for those with MCT1 and CD147 positive tumors. CD147 specific silencing by small interfering RNAs (siRNAs) in UBC cells was accompanied by a decrease in MCT1 and MCT4 expressions and, importantly, an increase in chemosensitivity to cisplatin. Our results provide novel insights for the involvement of CD147 and MCTs in bladder cancer progression and resistance to cisplatin-based chemotherapy. We consider that the possible cooperative role of CD147 and MCT1 in determining cisplatin resistance should be further explored as a potential theranostics biomarker.

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.

Impacts of CA9 gene polymorphisms on urothelial cell carcinoma susceptibility and clinicopathologic characteristics in Taiwan

BACKGROUND

Carbonic anhydrase 9 (CA9) is reportedly overexpressed in several types of carcinomas and is generally considered a marker of malignancy. The current study explored the effect of CA9 gene polymorphisms on the susceptibility of developing urothelial cell carcinoma (UCC) and the clinicopathological status.

METHODOLOGY AND PRINCIPAL FINDINGS

A total of 442 participants, including 221 healthy people and 221 patients with UCC, were recruited for this study. Four single-nucleotide polymorphisms (SNPs) of the CA9 gene were assessed by a real-time PCR with the TaqMan assay. After adjusting for other co-variants, the individuals carrying at least one A allele at CA9 rs1048638 had a 2.303-fold risk of developing UCC than did wild-type (CC) carriers. Furthermore, UCC patients who carried at least one A allele at rs1048638 had a higher invasive stage risk (p< 0.05) than did patients carrying the wild-type allele. Moreover, among the UCC patients with smoker, people with at least one A allele of CA9 polymorphisms (rs1048638) had a 4.75-fold (95% CI = 1.204-18.746) increased risk of invasive cancer.

CONCLUSION

The rs1048638 polymorphic genotypes of CA9 might contribute to the prediction of susceptibility to and pathological development of UCC. This is the first study to provide insight into risk factors associated with CA9 variants in carcinogenesis of UCC in Taiwan.

Biomarkers in bladder cancer: translational and clinical implications

Bladder cancer is associated with high recurrence and mortality rates. These tumors show vast heterogeneity reflected by diverse morphologic manifestations and various molecular alterations associated with these disease phenotypes. Biomarkers that prospectively evaluate disease aggressiveness, progression risk, probability of recurrence and overall prognosis would improve patient care. Integration of molecular markers with conventional pathologic staging of bladder cancers may refine clinical decision making for the selection of adjuvant and salvage therapy. In the past decade, numerous bladder cancer biomarkers have been identified, including various tumor suppressor genes, oncogenes, growth factors, growth factor receptors, hormone receptors, proliferation and apoptosis markers, cell adhesion molecules, stromal factors, and oncoproteins. Recognition of two distinct pathways for urothelial carcinogenesis represents a major advance in the understanding and management of this disease. Nomograms for combining results from multiple biomarkers have been proposed to increase the accuracy of clinical predictions. The scope of this review is to summarize the major biomarker findings that may have translational and clinical implications.

A novel function of novobiocin: disrupting the interaction of HIF 1α and p300/CBP through direct binding to the HIF1α C-terminal activation domain

Hypoxia-inducible factor 1α (HIF1α) is an important cellular survival protein under hypoxic conditions, regulating the cellular response to low oxygen tension via recruitment of a transcriptional co-activator, p300/CBP. p300/CBP induces expression of multiple genes involved in cell survival, proliferation, angiogenesis, and tumor development. Thus, a strategy to inhibit hypoxic responses in tumors may be to target the protein-protein interaction between HIF1α and p300/CBP. Here, we document, for the first time, that the aminocoumarin antibiotic, novobiocin, directly blocks the protein-protein interaction between the HIF1α C-terminal activation domain (CTAD) and the cysteine-histidine rich (CH1) region of p300/CBP. Also, novobiocin down-regulated HIF1α-controlled gene expression, specifically CA9, which is related to tumorigenesis. In a monolayer cell culture, novobiocin inhibited cell proliferation and colony formation in the MCF-7 human breast adenocarcinoma cell line and the A549 human lung cancer cell line. Rescue experiments revealed that the recombinant CTAD fragment of HIF1α partially reversed novobiocin’s inhibitory effects on cell proliferation and colony formation in MCF-7 cells. These findings suggest a novel mechanism of action for novobiocin which has the potential for innovative therapeutic use in tumor treatment.

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.

Centrosome amplification in bladder washing cytology specimens is a useful prognostic biomarker for non-muscle invasive bladder cancer

We investigated whether centrosome amplification (CA) obtained from bladder washing cytology (BWC) specimens may be a useful prognostic biomarker for patients with non-muscle invasive bladder cancer (NMIBC). The study cohort included 78 patients with pathologically confirmed NMIBC. BWC specimens were obtained from all patients during transurethral resection of bladder tumor (TURBT), and CA was evaluated by immunofluorescence staining using a pericentrin polyclonal antibody. A positive case of CA was defined as a specimen in which >5% of cells contained ≥3 centrosomes per cell. CA was detected in 26.9% (21 of 78) of BWC specimens obtained from NMIBC patients. Disease progression was observed in 11.5% (9 of 78) of patients, with a median follow-up of 32 months. In univariate analyses, CA obtained from BWC specimens, initial or recurrent, and washing cytology were significantly associated with progression-free survival (P = 0.009, 0.02, and 0.03, respectively). Multivariate Cox model analyses revealed that CA was the most significant prognostic factor for disease progression (hazard ratio: 2.22, 95% confidence interval: 1.13-4.90, P = 0.022). These data suggest that analysis of CA using bladder washing cytological specimens may provide crucial predictive information regarding disease progression in NMIBC.

Serum adenosine deaminase, catalase and carbonic anhydrase activities in patients with bladder cancer

OBJECTIVES

The relationship between adenosine deaminase and various cancers has been investigated in several studies. However, serum adenosine deaminase activity and carbonic anhydrase and catalase activities in patients with bladder cancer have not previously been reported. Therefore, the aim of this study was to measure serum adenosine deaminase, carbonic anhydrase and catalase activities in patients with bladder cancer.

MATERIALS AND METHODS

Forty patients with bladder cancer and 30 healthy controls were enrolled in the study. Serum adenosine deaminase, carbonic anhydrase and catalase activities were measured spectrophotometrically.

RESULTS

Serum adenosine deaminase, carbonic anhydrase and catalase activities were significantly higher in patients with bladder cancer than controls (all significant, p<0.001).

CONCLUSIONS

These markers might be a potentially important finding as an additional diagnostic biochemical tool for bladder cancer.

A candidate molecular biomarker panel for the detection of bladder cancer

BACKGROUND

Bladder cancer is among the five most common malignancies worldwide, and due to high rates of recurrence, one of the most prevalent. Improvements in noninvasive urine-based assays to detect bladder cancer would benefit both patients and health care systems. In this study, the goal was to identify urothelial cell transcriptomic signatures associated with bladder cancer.

METHODS

Gene expression profiling (Affymetrix U133 Plus 2.0 arrays) was applied to exfoliated urothelia obtained from a cohort of 92 subjects with known bladder disease status. Computational analyses identified candidate biomarkers of bladder cancer and an optimal predictive model was derived. Selected targets from the profiling analyses were monitored in an independent cohort of 81 subjects using quantitative real-time PCR (RT-PCR).

RESULTS

Transcriptome profiling data analysis identified 52 genes associated with bladder cancer (P ≤ 0.001) and gene models that optimally predicted class label were derived. RT-PCR analysis of 48 selected targets in an independent cohort identified a 14-gene diagnostic signature that predicted the presence of bladder cancer with high accuracy.

CONCLUSIONS

Exfoliated urothelia sampling provides a robust analyte for the evaluation of patients with suspected bladder cancer. The refinement and validation of the multigene urothelial cell signatures identified in this preliminary study may lead to accurate, noninvasive assays for the detection of bladder cancer.

IMPACT

The development of an accurate, noninvasive bladder cancer detection assay would benefit both the patient and health care systems through better detection, monitoring, and control of disease.

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.

Vascular endothelial growth factor, carbonic anhydrase 9, and angiogenin as urinary biomarkers for bladder cancer detection

OBJECTIVE

To investigate whether elevated urinary levels of vascular endothelial growth factor (VEGF), carbonic anhydrase 9 (CA9), and angiogenin are associated with bladder cancer (BCa).

METHODS

This was a case-control study in which voided urine samples from 127 patients (63 control subjects and 64 patients with BCa) were analyzed. The urinary concentrations of VEGF, CA9, angiogenin, and bladder tumor antigen (BTA) were assessed using enzyme-linked immunosorbent assays. We used the area under the curve of receiver operating characteristic curves to determine the ability of VEGF, CA9, and angiogenin to detect BCa in voided urine samples. Data were also compared with the findings from a commercial enzyme-linked immunosorbent assay-based BCa detection assay (BTA-Trak). The sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

The urinary concentrations of VEGF, CA9, angiogenin, and BTA were significantly elevated in those with BCa. VEGF was the most accurate urinary biomarker (area under the curve 0.886, 95% confidence interval 0.8301-0.9418). Furthermore, multivariate regression analysis highlighted VEGF (odds ratio 5.90, 95% confidence interval 2.60-13.40, P < .0001) as an independent variable. The sensitivity and specificity for VEGF (83% sensitivity and 87% specificity) outperformed those for BTA (80% sensitivity and 84% specificity).

CONCLUSION

VEGF could be a valuable addition to voided urine sample analysis for the detection of BCa. Larger, prospective studies are needed to determine the clinical utility of urinary VEGF and angiogenin as biomarkers in the noninvasive evaluation of patients with BCa.

Prospective evaluation of serum tissue inhibitor of metalloproteinase 1 and carbonic anhydrase IX in correlation to circulating tumor cells in patients with metastatic breast cancer

INTRODUCTION

Circulating tumor cells (CTCs) reflect aggressive tumor behavior by hematogenous tumor cell dissemination. The tissue inhibitor of metalloproteinase 1 (TIMP-1) plays a role in tissue invasion and is also involved in angiogenesis, abrogation of apoptosis and in chemoresistance. Carbonic anhydrase IX (CAIX) is a metalloenzyme involved in cell adhesion, growth and survival of tumor cells. The aim of the study was to investigate whether serum concentrations of TIMP-1 and CAIX are associated with the detection of CTC in metastatic breast cancer.

METHODS

Blood was obtained in a prospective multicenter setting from 253 patients with metastatic breast cancer at the time of disease progression. Serum TIMP-1 and CAIX were determined using commercial ELISA-kits (Oncogene Science). CTC were detected with the CellSearch system (Veridex).

RESULTS

Five or more CTCs were detected in 122 patients out of 245 evaluable patients (49.8%). Out of 253 metastatic patients 70 (28%) had serum TIMP-1 levels above 454 ng/mL. Serum CAIX was elevated above 506 ng/mL in 90 (35%) patients. Both serum markers had prognostic significance. Median progression free survival (PFS) was 7.2 months with elevated TIMP-1 vs. 11.4 months with non-elevated levels (p < 0.01). OS was 11.5 vs. 19.1 months (p < 0.01). Median PFS was 7.5 months with elevated CAIX vs. 11.7 months with non-elevated levels (p < 0.01), overall survival (OS) was 13.4 months vs. 19.1 months (p < 0.01). In patients with five or more CTCs, serum levels were above the cut-off for CAIX in 47% vs. 25% in those with less than five CTCs (p = 0.01). For TIMP-1, 37% patients with five or more CTCs had elevated serum levels and 17% of patients with less than five CTCs (p = 0.01). Including TIMP-1, CAIX, CTC and established prognostic factors in the multivariate analysis, the presence of CTCs, the therapy line and elevated CAIX remained independent predictors of OS.

CONCLUSIONS

Elevated serum levels of the invasion markers TIMP-1 and CAIX in metastatic breast cancer are prognostic markers and are associated with the presence of CTCs. Whether increased secretion of TIMP-1 and/or CAIX might directly contribute to tumor cell dissemination remains to be elucidated in further investigations.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN59722891.

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

Carbonic anhydrase IX (CAIX) is a strictly membranous expressed metalloenzyme involved in cell adhesion, pH homeostasis, and cancer progression. This study was designed to assess the role of CAIX in primary ovarian cancer. Two hundred five well-characterized primary ovarian carcinomas were analyzed on a tissue microarray. CAIX expression was determined by immunohistochemistry using a four-step scoring system. Moderate and strong membranous CAIX expression was found in 37 out of 205 (18%) of all assessable ovarian cancer specimens. High levels of CAIX expression were related to mucinous and endometrioid phenotype of ovarian carcinomas (p < 0.05). There was no association between CAIX overexpression and tumor stage, grading, and mitotic count of ovarian carcinomas (p > 0.05). In univariate Cox regression analysis, advanced tumor stage (p < 0.01), high tumor grade (p = 0.017), high mitotic count (p = 0.025), and high CAIX expression levels (p = 0.031) were correlated to shorter overall patient survival. High pT stage (p = 0.036) and CAIX overexpression were connected to poor clinical outcome in endometrioid ovarian carcinomas. Multivariate Cox regression hazard analysis comprising tumor stage, tumor grade, mitotic count, and CAIX expression revealed pT2/3 stage and CAIX overexpression (scores 2 and 3) as independent prognostic markers in ovarian cancer (p < 0.01, each) as well as in the subgroup of endometrioid carcinomas (p < 0.05, each). In conclusion, CAIX is overexpressed in a substantial proportion of mucinous and endometrioid ovarian carcinomas and connected to poor patient outcome. Our data support the potential therapeutic benefit of newly developed targeting antibodies in advanced ovarian cancer.

Two survivin polymorphisms are cooperatively associated with bladder cancer susceptibility

Abnormal survivin expression has been reported to be involved in many types of cancer. A single-nucleotide polymorphism (SNP), C-31G, located in the promoter region of survivin reportedly may alter the mRNA level, while the significance of the nonsynonymous SNP A9194G in exon 4 has not yet been clarified. Here, the association between the two survivin SNPs and bladder cancer susceptibility and progression was investigated in 235 patients with bladder cancer and 346 healthy controls. Regarding the C-31G SNP, subjects with the CC genotype had a significantly higher risk of bladder cancer compared to those with the GG + CG genotype [odds ratio (OR) = 1.85, p = 0.001]. Regarding the A9194G SNP, the presence of the G allele was associated with a significantly reduced risk with a gene dosage effect (OR = 0.69, p = 0.002). Using the C-A haplotype as a reference, the G-G haplotype was associated with a significantly lower risk (OR = 0.11, p = 0.00006), indicating the cooperative effect of the two SNPs. Immunohistological evaluation of surgical specimens showed that cancer cells of the C-31G CC genotype had significantly higher nuclear survivin expression than those of the C-31G GG + CG genotype. With reverse transcriptase-polymerase chain reaction analysis, a significantly higher survivin mRNA expression level was observed in surgical specimens with an increase in the number of the C-31G C allele (p = 0.016). These results indicate that the two SNPs have a significant and cooperative influence on bladder cancer susceptibility.

Tyrosine kinase ETK/BMX is up-regulated in bladder cancer and predicts poor prognosis in patients with cystectomy

Deregulation of the non-receptor tyrosine kinase ETK/BMX has been reported in several solid tumors. In this report, we demonstrated that ETK expression is progressively increased during bladder cancer progression. We found that down-regulation of ETK in bladder cancer cells attenuated STAT3 and AKT activity whereas exogenous overexpression of ETK had opposite effects, suggesting that deregulation of ETK may attribute to the elevated activity of STAT3 and AKT frequently detected in bladder cancer. The survival, migration and invasion of bladder cancer cells were significantly compromised when ETK expression was knocked down by a specific shRNA. In addition, we showed that ETK localizes to mitochondria in bladder cancer cells through interacting with Bcl-XL and regulating ROS production and drug sensitivity. Therefore, ETK may play an important role in regulating survival, migration and invasion by modulating multiple signaling pathways in bladder cancer cells. Immunohistochemistry analysis on tissue microarrays containing 619 human bladder tissue samples shows that ETK is significantly upregulated during bladder cancer development and progression and ETK expression level predicts the survival rate of patients with cystectomy. Taken together, our results suggest that ETK may potentially serve as a new drug target for bladder cancer treatment as well as a biomarker which could be used to identify patients with higher mortality risk, who may be benefited from therapeutics targeting ETK activity.

Carbonic anhydrase IX in tumor tissue and sera of patients with primary cervical cancer

Background

Carbonic anhydrase IX (CAIX) is a membranous expressed metalloenzyme involved in pH homeostasis and cell adhesion. The protein is overexpressed in a variety of tumors and potentially associated with negative outcome. This study was designed to investigate the prognostic role of CAIX in serum and tumor tissue of patients with primary cervical cancer.

Methods

Tumor samples of 221 consecutive patients with primary cervical cancer who underwent surgery between 1993 and 2008 were analyzed for CAIX expression by immunohistochemistry. Additionally, preoperative serum CAIX concentrations were determined by ELISA in a subset of patients. Correlation with intratumoral CAIX expression as well as clinicopathological factors and outcome was analyzed.

Results

CAIX expression was observed in 81.9% of the tumor specimens; 62.0% showed a moderate or strong staining intensity. Moderate/strong expression was associated with squamous histology (p = 0.024), advanced tumor stage (p = 0.001), greater invasion depth (p = 0.025), undifferentiated tumor grade (p < 0.001) and high preoperative SCC-Ag values (p = 0.042). Furthermore patients with moderate/strong intratumoral CAIX expression had a higher number of metastatic lymph nodes compared to those with none/weak intratumoral expression levels (p = 0.047) and there was a non-significant association between high intratumoral CAIX expression and shorter survival (p = 0.118). Preoperative serum concentrations of CAIX ranged between 23 and 499 pg/mL and did not correlate with intratumoral expression or other clinicopathological variables.

Conclusion

CAIX is associated with advanced tumor stages and lymph node metastases in cervical cancer, potentially representing a new target in this disease. In contrast to other epithelial cancers we could not observe a correlation between serum CAIX and its intratumoral expression.

High levels of carbonic anhydrase IX in tumour tissue and plasma are biomarkers of poor prognostic in patients with non-small cell lung cancer

Background:

Carbonic anhydrase IX (CAIX) is an enzyme upregulated by hypoxia during tumour development and progression. This study was conducted to assess if the expression of CAIX in tumour tissue and/or plasma can be a prognostic factor in patients with non-small cell lung cancer (NSCLC).

Methods:

Tissue microarrays containing 555 NSCLC tissue samples were generated for quantification of CAIX expression. The plasma level of CAIX was determined by ELISA in 209 of these NSCLC patients and in 58 healthy individuals. The CAIX tissue immunostaining and plasma levels were correlated with clinicopathological factors and patient outcome.

Results:

CAIX tissue overexpression correlated with shorter overall survival (OS) (P=0.05) and disease-specific survival (DSS) of patients (P=0.002). The CAIX plasma level was significantly higher in patients with NSCLC than in healthy individuals (P<0.001). A high level of CAIX in the plasma of patients was associated with shorter OS (P<0.001) and DSS (P<0.001), mostly in early stage I+II NSCLC. Multivariate Cox analyses revealed that high CAIX tissue expression (P=0.002) was a factor of poor prognosis in patients with resectable NSCLC. In addition, a high CAIX plasma level was an independent variable predicting poor OS (P<0.001) in patients with NSCLC.

Conclusion:

High expression of CAIX in tumour tissue is a predictor of worse survival, and a high CAIX plasma level is an independent prognostic biomarker in patients with NSCLC, in particular in early-stage I+II carcinomas.

Overexpression of carbonic anhydrase IX (CAIX) in vulvar cancer is associated with tumor progression and development of locoregional lymph node metastases

Carbonic anhydrase IX (CAIX) is a strictly membranous expressed metalloenzyme involved in cell adhesion, pH homeostasis, and cancer progression. The protein is specifically overexpressed in a wide variety of malignant tumors. This study was designed to assess the role of CAIX in primary vulvar cancer. One hundred forty-two well-characterized primary vulvar carcinomas were analyzed on a tissue microarray (TMA). Three tissue cores were sampled from each tumor. CAIX expression was determined by immunohistochemistry, using a four-step scoring system. To determine CAIX expression in benign vulvar tissue, we constructed a TMA with 120 samples of normal mucosa and non-neoplastic diseases. CAIX expression was found in 77/135 (57%) of all assessable vulvar cancer specimens and 48 (35.5%) exhibited a moderate or strong expression. CAIX expression in vulvar carcinomas was significantly stronger compared to non-neoplastic vulvar tissue (p < 0.001). High levels of CAIX expression were related to pT stage (p < 0.01), tumor size (p < 0.01), depth of invasion (p < 0.05), as well as inguinal lymph node metastases (p < 0.05). There was also a trend towards shorter recurrence-free patient survival in CAIX-positive compared to CAIX-negative vulvar cancers. CAIX staining results in different tissue cores from the same tumor were homogeneous, raising the possibility of a hypoxia-independent expression. In conclusion, CAIX is overexpressed in the majority of vulvar carcinomas with relationships to advanced tumor stages and development of lymph node metastases. Our data support the potential therapeutic benefit of newly developed targeting antibodies in advanced vulvar cancer.

Unique biological properties of catalytic domain directed human anti-CAIX antibodies discovered through phage-display technology

Carbonic anhydrase IX (CAIX, gene G250/MN-encoded transmembrane protein) is highly expressed in various human epithelial tumors such as renal clear cell carcinoma (RCC), but absent from the corresponding normal tissues. Besides the CA signal transduction activity, CAIX may serve as a biomarker in early stages of oncogenesis and also as a reliable marker of hypoxia, which is associated with tumor resistance to chemotherapy and radiotherapy. Although results from preclinical and clinical studies have shown CAIX as a promising target for detection and therapy for RCC, only a limited number of murine monoclonal antibodies (mAbs) and one humanized mAb are available for clinical testing and development. In this study, paramagnetic proteoliposomes of CAIX (CAIX-PMPLs) were constructed and used for anti-CAIX antibody selection from our 27 billion human single-chain antibody (scFv) phage display libraries. A panel of thirteen human scFvs that specifically recognize CAIX expressed on cell surface was identified, epitope mapped primarily to the CA domain, and affinity-binding constants (KD) determined. These human anti-CAIX mAbs are diverse in their functions including induction of surface CAIX internalization into endosomes and inhibition of the carbonic anhydrase activity, the latter being a unique feature that has not been previously reported for anti-CAIX antibodies. These human anti-CAIX antibodies are important reagents for development of new immunotherapies and diagnostic tools for RCC treatment as well as extending our knowledge on the basic structure-function relationships of the CAIX molecule.

Serum carbonic anhydrase IX during first-line therapy of ovarian cancer

OBJECTIVE

Carbonic anhydrase IX (CAIX) is primarily involved in maintaining the extracellular pH. It is overexpressed in a variety of tumors including ovarian cancer. To evaluate the potential prognostic and predictive role of serum CAIX for therapy response in ovarian cancer, we analyzed longitudinal serum samples.

METHODS

One hundred forty-eight serum samples from 37 patients with primary epithelial ovarian cancer were analyzed. Samples were prospectively collected at 4 time points: (1) before radical surgery, (2) after surgery and before platinum/taxane chemotherapy, (3) during chemotherapy, and (4) after chemotherapy. Serum CAIX was quantified by ELISA and expression in tumor tissue was verified by immunohistochemistry. Correlation with response and clinical outcome as well as the tumor marker CA-125 was analyzed.

RESULTS

Serum concentration of CAIX ranged between 30 and 1687 pg/mL and showed no significant changes during first-line therapy (median level before and after surgery 204 and 198 pg/mL, during and after chemotherapy 175 and 181 pg/mL). There was no association between serum CAIX and progression-free or overall survival. CA-125 decreased significantly after surgery (median serum level before and after surgery 413 and 84 kU/L, p<0.001) and further during and after first-line chemotherapy (median serum levels 21 and 15 kU/L, p<0.001). No intermarker correlation was observed.

CONCLUSIONS

CAIX is upregulated in ovarian cancer and serum CAIX could be a marker to stratify patients for therapy response. However, CAIX serum levels did not change significantly during first-line therapy and were not prognostically relevant. Based on the findings of the current study, CAIX cannot be recommended for therapy monitoring in this context.