CA12

Gene Summary

Gene:CA12; carbonic anhydrase 12
Aliases: CAXII, CA-XII, T18816, HsT18816
Location:15q22.2
Summary:Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide. They participate in a variety of biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid. This gene product is a type I membrane protein that is highly expressed in normal tissues, such as kidney, colon and pancreas, and has been found to be overexpressed in 10% of clear cell renal carcinomas. Three transcript variants encoding different isoforms have been identified for this gene. [provided by RefSeq, Jun 2014]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:carbonic anhydrase 12
Source:NCBIAccessed: 31 August, 2019

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (9)

Latest Publications: CA12 (cancer-related)

Uda NR, Stenner F, Seibert V, et al.
Humanized Monoclonal Antibody Blocking Carbonic Anhydrase 12 Enzymatic Activity Leads to Reduced Tumor Growth
Anticancer Res. 2019; 39(8):4117-4128 [PubMed] Related Publications
BACKGROUND/AIM: Carbonic anhydrase 12 (CA12) is a membrane-associated enzyme that is highly expressed on many human cancers. It is a poor prognostic marker and hence an attractive target for cancer therapy. This study aimed to develop a humanized CA12-antibody with anti-cancer activity.
MATERIALS AND METHODS: Antibody libraries were constructed and screened by the Retrocyte display®. Antibody binding and blocking properties were determined by ELISA, flow cytometry and enzymatic activity assays. Spheroid viability was determined by Cell-Titer-Fluor assay.
RESULTS: We developed a novel humanized CA12-specific antibody, 4AG4, which recognized CA12 as an antigen and blocked CA12 enzymatic activity. Our humanized CA12-antibody significantly inhibited spheroid growth of lung adenocarcinoma A549-cells in vitro by blocking CA12 enzymatic activity. Similar anti-tumor effects were recapitulated with CA12-gene knockout of A549-cells.
CONCLUSION: Our newly identified humanized CA12-antibody with anti-cancer activity, represents a new tool for the treatment of CA12-positive tumors.

Chen Z, Ai L, Mboge MY, et al.
Differential expression and function of CAIX and CAXII in breast cancer: A comparison between tumorgraft models and cells.
PLoS One. 2018; 13(7):e0199476 [PubMed] Free Access to Full Article Related Publications
Carbonic anhydrase IX (CAIX) and XII (CAXII) are transmembrane proteins that are associated with cancer progression. We have previously described the catalytic properties of CAIX in MDA-MB-231 breast cancer cells, a line of cells that were derived from a patient with triple negative breast cancer. We chose this line because CAIX expression in breast cancer is a marker of hypoxia and a prognosticator for reduced survival. However, CAXII expression is associated with better survival statistics than those patients with low CAXII expression. Yet CAIX and CAXII have similar catalytic activities. Here we compare the potential roles of CAIX and CAXII in the context of TNBC and estrogen receptor (ER)-positive breast cancer. In tumor graft models, we show that CAIX and CAXII exhibit distinct expression patterns and non-overlapping. We find the same pattern across a panel of TNBC and luminal breast cancer cell lines. This affords an opportunity to compare directly CAIX and CAXII function. Our data suggest that CAIX expression is associated with growth potentiation in the tumor graft model and in a TNBC line using knockdown strategies and blocking activity with an impermeant sulfonamide inhibitor, N-3500. CAXII was not associated with growth potentiation. The catalytic activities of both CAIX and CAXII were sensitive to inhibition by N-3500 and activated at low pH. However, pH titration of activity in membrane ghosts revealed significant differences in the catalytic efficiency and pKa values. These features provide evidence that CAIX is a more efficient enzyme than CAXII at low pH and that CAIX shifts the equilibrium between CO2 and bicarbonate in favor of CO2 production by consuming protons. This suggests that in the acidic microenvironment of tumors, CAIX plays a role in stabilizing pH at a value that favors cancer cell survival.

von Neubeck B, Gondi G, Riganti C, et al.
An inhibitory antibody targeting carbonic anhydrase XII abrogates chemoresistance and significantly reduces lung metastases in an orthotopic breast cancer model in vivo.
Int J Cancer. 2018; 143(8):2065-2075 [PubMed] Related Publications
Carbonic anhydrase XII (CAXII) is a membrane-tethered ectoenzyme involved in intracellular pH regulation and overexpressed across various types of human cancer. Because CAXII inhibition shows antitumor activity in vitro, it is thought that the enzyme is mandatory for maximum tumor growth, above all under hypoxic conditions. Recently, it has been shown that CAXII is co-expressed along with the P-glycoprotein (P-GP) on many tumor cells and that both proteins physically interact. Of interest, blocking CAXII activity also decreases P-GP activity in cancer cells both in vitro and in vivo. Previously, we have reported on the development of a monoclonal antibody, termed 6A10, which specifically and efficiently blocks human CAXII activity. Here, we demonstrate that 6A10 also indirectly reduces P-GP activity in CAXII/P-GP double-positive chemoresistant cancer cells, resulting in enhanced chemosensitivity as revealed by enhanced accumulation of anthracyclines and increased cell death in vitro. Even more important, we show that mice carrying human triple-negative breast cancer xenografts co-treated with doxorubicin (DOX) and 6A10 show a significantly reduced number of metastases. Collectively, our data provide evidence that the inhibition of CAXII with 6A10 is an attractive way to reduce chemoresistance of cancer cells and to interfere with the metastatic process in a clinical setting.

Fiedler L, Kellner M, Oos R, et al.
Fully Automated Production and Characterization of
ChemMedChem. 2018; 13(12):1230-1237 [PubMed] Related Publications

Ambrosetti D, Dufies M, Dadone B, et al.
The two glycolytic markers GLUT1 and MCT1 correlate with tumor grade and survival in clear-cell renal cell carcinoma.
PLoS One. 2018; 13(2):e0193477 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Clear-cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer. Although ccRCC is characterized by common recurrent genetic abnormalities, including inactivation of the von Hippel-Lindau (vhl) tumor suppressor gene resulting in stabilization of hypoxia-inducible factors (HIFs), the tumor aggressiveness and outcome of ccRCC is variable. New biomarkers are thus required to improve ccRCC diagnosis, prognosis and therapeutic options. This work aims to investigate the expression of HIF and proteins involved in metabolism and pH regulation. Their correlation to histoprognostic parameters and survival was analyzed.
METHODS: ccRCC of 45 patients were analyzed. HIF-1α, HIF-2α, HAF, GLUT1, MCT1, MCT4, CAIX and CAXII expression was assessed by immunohistochemistry in a semi-quantitative and qualitative manner. The GLUT1, MCT1, MCT4, CAIX and CAXII mRNA levels were analyzed in an independent cohort of 43 patients.
RESULTS: A significant correlation was observed between increased GLUT1, MCT1, CAXII protein expression and a high Fuhrman grade in ccRCC patients. Moreover, while HIF-1α, HIF-2α and HAF expression was heterogenous within tumors, we observed and confirmed that HIF-2α co-localized with HAF. We confirmed, in an independent cohort, that GLUT1, MCT1 and CAXII mRNA levels correlated with the Fuhrman grade. Moreover, we demonstrated that the high mRNA level of both MCT1 and GLUT1 correlated with poor prognosis.
CONCLUSIONS: This study demonstrates for the first time a link between the aggressiveness of high- Fuhrman grade ccRCC and metabolic reprogramming. It also confirms the role of HIF-2α and HAF in tumor invasiveness. Finally, these results demonstrate that MCT1 and GLUT1 are strong prognostic markers and promising therapeutic targets.

Boyd NH, Walker K, Fried J, et al.
Addition of carbonic anhydrase 9 inhibitor SLC-0111 to temozolomide treatment delays glioblastoma growth in vivo.
JCI Insight. 2017; 2(24) [PubMed] Free Access to Full Article Related Publications
Tumor microenvironments can promote stem cell maintenance, tumor growth, and therapeutic resistance, findings linked by the tumor-initiating cell hypothesis. Standard of care for glioblastoma (GBM) includes temozolomide chemotherapy, which is not curative, due, in part, to residual therapy-resistant brain tumor-initiating cells (BTICs). Temozolomide efficacy may be increased by targeting carbonic anhydrase 9 (CA9), a hypoxia-responsive gene important for maintaining the altered pH gradient of tumor cells. Using patient-derived GBM xenograft cells, we explored whether CA9 and CA12 inhibitor SLC-0111 could decrease GBM growth in combination with temozolomide or influence percentages of BTICs after chemotherapy. In multiple GBMs, SLC-0111 used concurrently with temozolomide reduced cell growth and induced cell cycle arrest via DNA damage in vitro. In addition, this treatment shifted tumor metabolism to a suppressed bioenergetic state in vivo. SLC-0111 also inhibited the enrichment of BTICs after temozolomide treatment determined via CD133 expression and neurosphere formation capacity. GBM xenografts treated with SLC-0111 in combination with temozolomide regressed significantly, and this effect was greater than that of temozolomide or SLC-0111 alone. We determined that SLC-0111 improves the efficacy of temozolomide to extend survival of GBM-bearing mice and should be explored as a treatment strategy in combination with current standard of care.

Waheed A, Sly WS
Carbonic anhydrase XII functions in health and disease.
Gene. 2017; 623:33-40 [PubMed] Free Access to Full Article Related Publications
Human CAXII was initially identified as a cancer marker in different cancers and tumors. Expression of CAXII is regulated by hypoxia and estrogen receptors. CAXII expression has been also detected in several tissues, whereas in cancer and tumor tissues its expression is several fold higher. In brain tumors, an alternatively spliced form of CAXII is expressed. Higher expression of CAXII in breast cancer is indicative of lower grade disease. CAXII plays a key role in several physiological functions. Mutation in the CAXII gene causes cystic fibrosis-like syndrome and salt wasting disease. CAXII is also seen in nuclear pulposus cells of the vertebrae. Aging dependent stiffness or degeneration of backbone correlates with CAXII expression level. This finding suggests a possible implication of CAXII as a biomarker for chronic back pain and a pharmacological target for possible treatment of chronic back pain.

Dinh TA, Vitucci EC, Wauthier E, et al.
Comprehensive analysis of The Cancer Genome Atlas reveals a unique gene and non-coding RNA signature of fibrolamellar carcinoma.
Sci Rep. 2017; 7:44653 [PubMed] Free Access to Full Article Related Publications
Fibrolamellar carcinoma (FLC) is a unique liver cancer primarily affecting young adults and characterized by a fusion event between DNAJB1 and PRKACA. By analyzing RNA-sequencing data from The Cancer Genome Atlas (TCGA) for >9,100 tumors across ~30 cancer types, we show that the DNAJB1-PRKACA fusion is specific to FLCs. We demonstrate that FLC tumors (n = 6) exhibit distinct messenger RNA (mRNA) and long intergenic non-coding RNA (lincRNA) profiles compared to hepatocellular carcinoma (n = 263) and cholangiocarcinoma (n = 36), the two most common liver cancers. We also identify a set of mRNAs (n = 16) and lincRNAs (n = 4), including LINC00473, that distinguish FLC from ~25 other liver and non-liver cancer types. We confirm this unique FLC signature by analysis of two independent FLC cohorts (n = 20 and 34). Lastly, we validate the overexpression of one specific gene in the FLC signature, carbonic anhydrase XII (CA12), at the protein level by western blot and immunohistochemistry. Both the mRNA and lincRNA signatures support a major role for protein kinase A (PKA) signaling in shaping the FLC gene expression landscape, and present novel candidate FLC oncogenes that merit further investigation.

Cruzeiro GAV, Dos Reis MB, Silveira VS, et al.
HIF1A is Overexpressed in Medulloblastoma and its Inhibition Reduces Proliferation and Increases EPAS1 and ATG16L1 Methylation.
Curr Cancer Drug Targets. 2018; 18(3):287-294 [PubMed] Related Publications
BACKGROUND: Genetic and epigenetic modifications are closely related to tumor initiation and progression and can provide guidance for understanding tumor functioning, potentially leading to the discovery of new therapies. Studies have associated hypoxia-related genes to tumor progression and chemo/radioresistance in brain tumors. Information on the expression profile of hypoxiarelated genes in pediatric medulloblastoma, although scarce, may reveal relevant information that could support treatment decisions.
OBJECTIVE: Our study focused on evaluation the of CA9, CA12, HIF1A, EPAS1, SCL2A1 and VEGF genes in 41 pediatric fresh-frozen medulloblastoma sample. Additionally, we analyzed the effect of hypoxia and normoxia in the pediatric medulloblastoma cell-line UW402. Furthermore, we assessed the effects of HIF1A knockdown in cell-proliferation and methylation levels of genes related to hypoxia, apoptosis and autophagy.
METHOD: qPCR was performed to evaluate mRNA levels, and Western blot to confirm HIF1A silencing in both patient samples and cell line. Pyrosequencing was performed to asses the methylation levels after HIF1A knockdown in the UW402 cell line.
RESULTS: A higher HIF1A mRNA level was observed in MB patients when compared to the cerebellum (non-tumor match). In UW402 MB cell-line, chemically induced hypoxic resulted in an increase of mRNA levels of HIF1A, VEGF, SCL2A1 and CA9 genes. Additionally, HIF1A knockdown induced a decrease in the expression of hypoxia related genes and a decrease of 30% in cell proliferation was also observed. Also, a significant increase in the methylation of ATG16L1 promoter and decrease in the methylation of EPAS1 promoter were observed after HIF1A knockdown.
CONCLUSION: HIF1A knockdown in medulloblastoma cells lead to decreased cellular proliferation, suggesting that HIF1A can be a potential therapeutic target to be explored in the medulloblastoma. However, the mechanisms behind HIF1A protein stabilization and function are very complex and more data need to be generated to potentially use HIF1A as a therapeutical target.

Parks SK, Cormerais Y, Durivault J, Pouyssegur J
Genetic disruption of the pHi-regulating proteins Na+/H+ exchanger 1 (SLC9A1) and carbonic anhydrase 9 severely reduces growth of colon cancer cells.
Oncotarget. 2017; 8(6):10225-10237 [PubMed] Free Access to Full Article Related Publications
Hypoxia and extracellular acidosis are pathophysiological hallmarks of aggressive solid tumors. Regulation of intracellular pH (pHi) is essential for the maintenance of tumor cell metabolism and proliferation in this microenvironment and key proteins involved in pHi regulation are of interest for therapeutic development. Carbonic anhydrase 9 (CA9) is one of the most robustly regulated proteins by the hypoxia inducible factor (HIF) and contributes to pHi regulation. Here, we have investigated for the first time, the role of CA9 via complete genomic knockout (ko) and compared its impact on tumor cell physiology with the essential pHi regulator Na+/H+ exchanger 1 (NHE1). Initially, we established NHE1-ko LS174 cells with inducible CA9 knockdown. While increased sensitivity to acidosis for cell survival in 2-dimensions was not observed, clonogenic proliferation and 3-dimensional spheroid growth in particular were greatly reduced. To avoid potential confounding variables with use of tetracycline-inducible CA9 knockdown, we established CA9-ko and NHE1/CA9-dko cells. NHE1-ko abolished recovery from NH4Cl pre-pulse cellular acid loading while both NHE1 and CA9 knockout reduced resting pHi. NHE1-ko significantly reduced tumor cell proliferation both in normoxia and hypoxia while CA9-ko dramatically reduced growth in hypoxic conditions. Tumor xenografts revealed substantial reductions in tumor growth for both NHE1-ko and CA9-ko. A notable induction of CA12 occurred in NHE1/CA9-dko tumors indicating a potential means to compensate for loss of pH regulating proteins to maintain growth. Overall, these genomic knockout results strengthen the pursuit of targeting tumor cell pH regulation as an effective anti-cancer strategy.

Zheng B, Liu J, Gu J, et al.
Classification of Benign and Malignant Thyroid Nodules Using a Combined Clinical Information and Gene Expression Signatures.
PLoS One. 2016; 11(10):e0164570 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: A key challenge in thyroid carcinoma is preoperatively diagnosing malignant thyroid nodules. A novel diagnostic test that measures the expression of a 3-gene signature (DPP4, SCG5 and CA12) has demonstrated promise in thyroid carcinoma assessment. However, more reliable prediction methods combining clinical features with genomic signatures with high accuracy, good stability and low cost are needed.
METHODOLOGY/PRINCIPAL FINDINGS: 25 clinical information were recorded in 771 patients. Feature selection and validation were conducted using random forest. Thyroid samples and clinical data were obtained from 142 patients at two different hospitals, and expression of the 3-gene signature was measured using quantitative PCR. The predictive abilities of three models (based on the selected clinical variables, the gene expression profile, and integrated gene expression and clinical information) were compared. Seven clinical characteristics were selected based on a training set (539 patients) and tested in three test sets, yielding predictive accuracies of 82.3% (n = 232), 81.4% (n = 70), and 81.9% (n = 72). The predictive sensitivity, specificity, and accuracy were 72.3%, 80.5% and 76.8% for the model based on the gene expression signature, 66.2%, 81.8% and 74.6% for the model based on the clinical data, and 83.1%, 84.4% and 83.8% for the combined model in a 10-fold cross-validation (n = 142).
CONCLUSIONS: These findings reveal that the integrated model, which combines clinical data with the 3-gene signature, is superior to models based on gene expression or clinical data alone. The integrated model appears to be a reliable tool for the preoperative diagnosis of thyroid tumors.

Viikilä P, Kivelä AJ, Mustonen H, et al.
Carbonic anhydrase enzymes II, VII, IX and XII in colorectal carcinomas.
World J Gastroenterol. 2016; 22(36):8168-77 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate expression of four alpha-carbonic anhydrases (CAs) in colorectal carcinomas (CRC) and compare the results with patients' survival.
METHODS: Colorectal carcinoma samples from 539 CRC patients and control tissues were arranged as tissue microarrays and analyzed with antibodies against CA II, CA VII, CA IX, and CA XII. Intensity and extent of staining were both scored from 0 to 3 in each sample. These enzyme expression levels were then correlated to patients' survival and clinicopathological parameters, which were tumor differentiation grade and stage, site of tumor, patients' age, and gender. Kaplan-Meier analysis and Cox regression hazard ratio model were used to analyze survival data.
RESULTS: CA II and CA XII staining intensities correlated with patients' survival in that higher expression indicated poorer prognosis. In Cox regression analysis one unit increase in the CA II intensity increased the hazard ratio to 1.19 fold (CI: 1.04-1.37, P = 0.009). A significant correlation was also found when comparing CA XII staining intensity with survival of CRC patients (HR = 1.18, 95%CI: 1.01-1.38, P = 0.036). The extent of CA XII immunostaining did not correlate to the patients' survival (P = 0.242, Kaplan-Meier analysis). A significant interaction between age group and extent of the CA II staining was found. Increased extent of CA II had a significant hazard ratio among patients 65 years and older (1.42, 95%CI: 1.16-1.73, P = 0.0006). No correlations were found between CA VII (intensity P = 0.566, extent P = 0.495, Kaplan-Meier analysis), or CA IX (intensity P = 0.879, extent P = 0.315, Kaplan-Meier analysis) immunostaining results and survival, or the other parameters.
CONCLUSION: The present findings indicate that CA II and CA XII could be useful in predicting survival in CRC.

Lei B, Zhang XY, Zhou JP, et al.
Transcriptome sequencing of HER2-positive breast cancer stem cells identifies potential prognostic marker.
Tumour Biol. 2016; 37(11):14757-14764 [PubMed] Related Publications
In cancer stem cell theory, breast cancer stem cells (BCSCs) are postulated to be the root cause of recurrence and metastasis in breast cancer. Discovery of new biomarkers and development of BCSC-targeted therapy are practical issues that urgently need to be addressed in the clinic. However, few breast cancer stem cell targets are known. Given that there are few BCSCs, performing transcriptome sequencing on them thus far has not been possible. With the emergence of single-cell sequencing technology, we have now undertaken such a study. We prepared single-cell suspensions, which were sorted using flow cytometry from breast tumor tissue and adjacent normal breast tissue from two HER2-positive patients. We obtained BCSCs, breast cancer cells, mammary cells, and CD44

Dang TT, Westcott JM, Maine EA, et al.
ΔNp63α induces the expression of FAT2 and Slug to promote tumor invasion.
Oncotarget. 2016; 7(19):28592-611 [PubMed] Free Access to Full Article Related Publications
Tumor invasion can be induced by changes in gene expression that alter cell phenotype. The transcription factor ΔNp63α promotes basal-like breast cancer (BLBC) migration by inducing the expression of the mesenchymal genes Slug and Axl, which confers cells with a hybrid epithelial/mesenchymal state. However, the extent of the ΔNp63α regulated genes that support invasive behavior is not known. Here, using gene expression analysis, ChIP-seq, and functional testing, we find that ΔNp63α promotes BLBC motility by inducing the expression of the atypical cadherin FAT2, the vesicular binding protein SNCA, the carbonic anhydrase CA12, the lipid binding protein CPNE8 and the kinase NEK1, along with Slug and Axl. Notably, lung squamous cell carcinoma migration also required ΔNp63α dependent FAT2 and Slug expression, demonstrating that ΔNp63α promotes migration in multiple tumor types by inducing mesenchymal and non-mesenchymal genes. ΔNp63α activation of FAT2 and Slug influenced E-cadherin localization to cell-cell contacts, which can restrict spontaneous cell movement. Moreover, live-imaging of spheroids in organotypic culture demonstrated that ΔNp63α, FAT2 and Slug were essential for the extension of cellular protrusions that initiate collective invasion. Importantly, ΔNp63α is co-expressed with FAT2 and Slug in patient tumors and the elevated expression of ΔNp63α, FAT2 and Slug correlated with poor patient outcome. Together, these results reveal how ΔNp63α promotes cell migration by directly inducing the expression of a cohort of genes with distinct cellular functions and suggest that FAT2 is a new regulator of collective invasion that may influence patient outcome.

Vaeteewoottacharn K, Kariya R, Dana P, et al.
Inhibition of carbonic anhydrase potentiates bevacizumab treatment in cholangiocarcinoma.
Tumour Biol. 2016; 37(7):9023-35 [PubMed] Related Publications
Cholangiocarcinoma (CCA) is a unique liver cancer subtype with an increasing incidence globally. The lack of specific symptoms and definite diagnostic markers results in a delayed diagnosis and disease progression. Systemic chemotherapy is commonly selected for advanced CCA even though its advantages remain unknown. Targeted therapy, especially anti-vascular endothelial growth factor (VEGF) therapy, is promising for CCA; however, improvements in the therapeutic regimen are necessary to overcome subsequent resistance. We demonstrated VEGF expression was higher in CCA cell lines than in other liver cancer cells. Secreted VEGFs played roles in the induction of peri- and intra-tumoral vascularization. VEGF neutralization by bevacizumab effectively reduced tumor growth, mainly through the suppression of angiogenesis; however, increases in the expression of hypoxia-inducible factor 1α (HIF1α) and HIF1α-responsive genes (such as VEGF, VEGFR1, VEGFR2, carbonic anhydrase (CA) IX and CAXII) indicated the potential for subsequent therapeutic resistance. Supplementation with a carbonic anhydrase inhibitor, acetazolamide, enhanced the anti-CCA effects of bevacizumab. Anti-angiogenesis and anti-proliferation were observed with the combination treatment. These results suggested a novel treatment strategy to overcome anti-angiogenesis resistance and the importance of "induced essentiality" in the treatment of CCA.

Tafreshi NK, Lloyd MC, Proemsey JB, et al.
Evaluation of CAIX and CAXII Expression in Breast Cancer at Varied O2 Levels: CAIX is the Superior Surrogate Imaging Biomarker of Tumor Hypoxia.
Mol Imaging Biol. 2016; 18(2):219-31 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Hypoxia is commonly observed in regions of primary tumors and metastases, and is associated with resistance to treatment, more aggressive tumor phenotypes and poor prognosis. Reliable and validated imaging biomarkers of hypoxia are needed for pre-clinical studies and clinical use. Expression of cell-surface carbonic anhydrases IX and XII (CAIX and CAXII) in tumor cells has been associated with tumor hypoxia. CAIX and CAXII specific antibodies conjugated to fluorescent dye were evaluated for the non-invasive detection of hypoxia in vivo.
PROCEDURES: Human breast cancer cell lines (MCF10A, DCIS, MCF7, ZR-75.1 and MDA-mb231) were characterized for CAIX and CAXII expression by real-time RT-PCR and immunocytochemistry (ICC) under normoxic and hypoxic conditions. Immunohistochemical (IHC) staining of CAIX, CAXII and the commercially available exogenous hypoxia marker, pimonidazole, was performed using sections of ZR-75.1 and MDA-mb-231 orthotopic breast cancer xenograft tumors from nude mice. In vivo fluorescence imaging of ZR-75.1 tumors in animals housed at varied levels of oxygen was used to quantify the relative uptake of the CAIX and CAXII agents and a commercially available sulfonamide-based agent. Corresponding tumor sections were IHC stained for CAIX, CAXII and pimonidazole.
RESULTS: CAIX mRNA expression was significantly higher (p < 0.05) in hypoxia for all cell lines, which was in agreement with protein expression by ICC. CAXII expression was mixed, with a modest hypoxia-related increase in two cell lines (p < 0.05) and no change in others. Quantified IHC staining of ZR-75.1 and MDA-mb-231 tumor sections showed that CAIX and CAXII expression was elevated in regions with pimonidazole staining, but CAXII levels were lower than CAIX. Tumor uptake of the CAIX targeted agent, and IHC staining of CAIX and pimonidazole in corresponding tumor sections were correlated, and co-registered, and shown to be significantly elevated by level of oxygenation (p < 0.001): hypoxia > normoxia > hyperoxia. However, the CAXII and sulfonamide agents were not significantly correlated with hypoxia.
CONCLUSION: These studies suggest that the fluorescently labeled CAIX-specific agent is a more robust indicator of hypoxia in vivo compared to the CAXII-specific agent or the agent specific to the CA active site.

Liu R, Lv QL, Yu J, et al.
Correlating transcriptional networks with pathological complete response following neoadjuvant chemotherapy for breast cancer.
Breast Cancer Res Treat. 2015; 151(3):607-18 [PubMed] Related Publications
We aimed to investigate the association between gene co-expression modules and responses to neoadjuvant chemotherapy in breast cancer by using a systematic biological approach. The gene expression profiles and clinico-pathological data of 508 (discovery set) and 740 (validation set) patients with breast cancer who received neoadjuvant chemotherapy were analyzed. Weighted gene co-expression network analysis was performed and identified seven co-regulated gene modules. Each module and gene signature were evaluated with logistic regression models for pathological complete response (pCR). The association between modules and pCR in each intrinsic molecular subtype was also investigated. Two transcriptional modules were correlated with tumor grade, estrogen receptor status, progesterone receptor status, and chemotherapy response in breast cancer. One module that constitutes upregulated cell proliferation genes was associated with a high probability for pCR in the whole (odds ratio (OR) = 5.20 and 3.45 in the discovery and validation datasets, respectively), luminal B, and basal-like subtypes. The prognostic potentials of novel genes, such as MELK, and pCR-related genes, such as ESR1 and TOP2A, were identified. The upregulation of another gene co-expression module was associated with weak chemotherapy responses (OR = 0.19 and 0.33 in the discovery and validation datasets, respectively). The novel gene CA12 was identified as a potential prognostic indicator in this module. A systems biology network-based approach may facilitate the discovery of biomarkers for predicting chemotherapy responses in breast cancer and contribute in developing personalized medicines.

Kopecka J, Campia I, Jacobs A, et al.
Carbonic anhydrase XII is a new therapeutic target to overcome chemoresistance in cancer cells.
Oncotarget. 2015; 6(9):6776-93 [PubMed] Free Access to Full Article Related Publications
Multidrug resistance (MDR) in cancer cells is a challenging phenomenon often associated with P-glycoprotein (Pgp) surface expression. Finding new ways to bypass Pgp-mediated MDR still remains a daunting challenge towards the successful treatment of malignant neoplasms such as colorectal cancer.We applied the Cell Surface Capture technology to chemosensitive and chemoresistant human colon cancer to explore the cell surface proteome of Pgp-expressing cells in a discovery-driven fashion. Comparative quantitative analysis of identified cell surface glycoproteins revealed carbonic anhydrase type XII (CAXII) to be up-regulated on the surface of chemoresistant cells, similarly to Pgp. In cellular models showing an acquired MDR phenotype due to the selective pressure of chemotherapy, the progressive increase of the transcription factor hypoxia-inducible factor-1 alpha was paralleled by the simultaneous up-regulation of Pgp and CAXII. CAXII and Pgp physically interacted at the cell surface. CAXII silencing or pharmacological inhibition with acetazolamide decreased the ATPase activity of Pgp by altering the optimal pH at which Pgp operated and promoted chemosensitization to Pgp substrates in MDR cells.We propose CAXII as a new secondary marker of the MDR phenotype that influences Pgp activity directly and can be used as a pharmacological target for MDR research and potential treatment.

Patel P, Brooks C, Seneviratne A, et al.
Investigating microenvironmental regulation of human chordoma cell behaviour.
PLoS One. 2014; 9(12):e115909 [PubMed] Free Access to Full Article Related Publications
The tumour microenvironment is complex and composed of many different constituents, including matricellular proteins such as connective tissue growth factor (CCN2), and is characterized by gradients in oxygen levels. In various cancers, hypoxia and CCN2 promote stem and progenitor cell properties, and regulate the proliferation, migration and phenotype of cancer cells. Our study was aimed at investigating the effects of hypoxia and CCN2 on chordoma cells, using the human U-CH1 cell line. We demonstrate that under basal conditions, U-CH1 cells express multiple CCN family members including CCN1, CCN2, CCN3 and CCN5. Culture of U-CH1 cells in either hypoxia or in the presence of recombinant CCN2 peptide promoted progenitor cell-like characteristics specific to the notochordal tissue of origin. Specifically, hypoxia induced the most robust increase in progenitor-like characteristics in U-CH1 cells, including increased expression of the notochord-associated markers T, CD24, FOXA1, ACAN and CA12, increased cell growth and tumour-sphere formation, and a decrease in the percentage of vacuolated cells present in the heterogeneous population. Interestingly, the effects of recombinant CCN2 peptide on U-CH1 cells were more pronounced under normoxia than hypoxia, promoting increased expression of CCN1, CCN2, CCN3 and CCN5, the notochord-associated markers SOX5, SOX6, T, CD24, and FOXA1 as well as increased tumour-sphere formation. Overall, this study highlights the importance of multiple factors within the tumour microenvironment and how hypoxia and CCN2 may regulate human chordoma cell behaviour.

Zheng B, Liu J, Gu J, et al.
A three-gene panel that distinguishes benign from malignant thyroid nodules.
Int J Cancer. 2015; 136(7):1646-54 [PubMed] Related Publications
Reliable preoperative diagnosis of malignant thyroid tumors remains challenging because of the inconclusive cytological examination of fine-needle aspiration biopsies. Although numerous studies have successfully demonstrated the use of high-throughput molecular diagnostics in cancer prediction, the application of microarrays in routine clinical use remains limited. Our aim was, therefore, to identify a small subset of genes to develop a practical and inexpensive diagnostic tool for clinical use. We developed a two-step feature selection method composed of a linear models for microarray data (LIMMA) linear model and an iterative Bayesian model averaging model to identify a suitable gene set signature. Using one public dataset for training, we discovered a three-gene signature dipeptidyl-peptidase 4 (DPP4), secretogranin V (SCG5) and carbonic anhydrase XII (CA12). We then evaluated the robustness of our gene set using three other independent public datasets. The gene signature accuracy was 85.7, 78.8 and 85.7%, respectively. For experimental validation, we collected 70 thyroid samples from surgery and our three-gene signature method achieved an accuracy of 94.3% by quantitative polymerase chain reaction (QPCR) experiment. Furthermore, immunohistochemistry in 29 samples showed proteins expressed by these three genes are also differentially expressed in thyroid samples. Our protocol discovered a robust three-gene signature that can distinguish benign from malignant thyroid tumors, which will have daily clinical application.

Kim HJ, Chung JH, Shin HP, et al.
Polymorphisms of interferon gamma gene and risk of hepatocellular carcinoma in Korean patients with chronic hepatitis B viral infection.
Hepatogastroenterology. 2013 Nov-Dec; 60(128):2080-4 [PubMed] Related Publications
BACKGROUNDS/AIMS: Increasing evidence supports the contribution of the pro-/anti-inflammatory cytokine balance and genetic factors to hepatocellular carcinoma (HCC). Here, we investigated whether genetic interferon gamma polymorphisms were associated with HCC in Korean patients with chronic hepatitis B.
METHODOLOGY: We genotyped a single nucleotide polymorphism (SNP, rs2430561, +874A/T) and a microsatellite (rs3138557, (CA) (n) repeat), located in the first intron of the interferon gamma gene, by direct sequencing and the gene scan method. A population-based case-control study of HCC was conducted and included 170 patients with chronic hepatitis and HCC, and 171 with chronic hepatitis B patients without hepatocellular carcinoma in a Korean population.
RESULTS: Genotype and allele distributions of the interferon gamma gene SNP were associated with HCC. The frequencies of the AA genotype and the A allele were significantly increased in hepatocellular carcinoma subjects (p < 0.05). Combined analysis using the genotype of rs2430561 and the number of microsatellites revealed that the frequencies of AT-CA12, and TT-CA12 increased significantly in hepatocellular carcinoma subjects (p < 0.0001).
CONCLUSIONS: Our results suggest that the interferon gamma gene may be a susceptibility gene and a risk factor for HCC in the Korean population.

Buchholtz ML, Brüning A, Mylonas I, Jückstock J
Epigenetic silencing of the LDOC1 tumor suppressor gene in ovarian cancer cells.
Arch Gynecol Obstet. 2014; 290(1):149-54 [PubMed] Related Publications
PURPOSE: Due to very unspecific symptoms ovarian cancer often is diagnosed only at a late stage of the disease. Thus, morbidity and mortality of the patients are high. Even the established tumor marker CA12-5 shows only low specificity, rising the need for alternative biomarkers capable of detecting early stages of ovarian cancer. We analyzed the expression of the tumor suppressor candidate gene LDOC1 (leucine zipper downregulated in cancer 1) as a potential early biomarker in ovarian cancer cell lines.
METHODS: A total of seven ovarian cancer cell lines were analyzed by RT-PCR (reverse transcriptase polymerase chain reaction) and real-time PCR for expression of LDOC1. Verification of promoter methylation was performed using methylation-specific primers on bisulfite-modified genomic DNA.
RESULTS: Three out of seven ovarian cancer cell lines showed a complete loss of LDOC1 gene expression. LDOC1 silencing was caused neither by gene deletion nor gene rearrangements, but by methylation and subsequent inactivation of the concerned promoter as proofed by methylation specific primers. Similarly, promoter methylation could be inhibited by adding AdC (5-aza-2'-deoxycytidine), an inhibitor of DNA methyltransferases. As a result, a reactivation of the LDOC1 gene was seen.
CONCLUSIONS: The tumor suppressor gene LDOC1 in ovarian cancer cell lines is downregulated by promoter methylation and thus may serve as an early biomarker. Further investigation will show if detection of methylated LDOC1 in peripheral blood has both adequate sensitivity and specificity for a timely non-invasive detection of ovarian cancer.

Takacova M, Bullova P, Simko V, et al.
Expression pattern of carbonic anhydrase IX in Medullary thyroid carcinoma supports a role for RET-mediated activation of the HIF pathway.
Am J Pathol. 2014; 184(4):953-965 [PubMed] Related Publications
Medullary thyroid carcinoma is a relatively rare tumor with poor prognosis and therapy response. Its phenotype is determined by both genetic alterations (activating RET oncoprotein) and physiological stresses, namely hypoxia [activating hypoxia-inducible factor (HIF)]. Here, we investigated the cooperation between these two mechanisms. The idea emerged from the immunohistochemical analysis of carbonic anhydrases (CA) IX and XII expression in thyroid cancer. Although CAXII was present in all types of thyroid carcinomas, CAIX, a direct HIF target implicated in tumor progression, was associated with aggressive medullary and anaplastic carcinomas, and its expression pattern in medullary thyroid carcinomas suggested contribution of both hypoxic and oncogenic signaling. Therefore, we analyzed the CA9 promoter activity in transfected tumor cells expressing RET and/or the HIF-α subunit. We showed that overexpression of both wild-type and mutant RET can increase the CA9 promoter activity induced by HIF-1 (but not HIF-2) in hypoxia. Similar results were obtained with another HIF-1-regulated promoter derived from the lactate dehydrogenase A gene. Moreover, inhibition of the major kinase pathways, which transmit signals from RET and regulate HIF-1, abrogated their cooperative effect on the CA9 promoter. Thus, we brought the first experimental evidence for the crosstalk between RET and HIF-1 that can explain the increased expression of CAIX in medullary thyroid carcinoma and provide a rationale for therapy simultaneously targeting both pathways.

Christgen M, Geffers R, Kreipe H, Lehmann U
IPH-926 lobular breast cancer cells are triple-negative but their microarray profile uncovers a luminal subtype.
Cancer Sci. 2013; 104(12):1726-30 [PubMed] Related Publications
Human primary breast cancers and breast cancer cell lines are classified by microarray-defined molecular subtypes, which reflect differentiation characteristics. Estrogen receptor (ER) expression is indicative of the luminal molecular subtype. We have previously established IPH-926, the first well-characterized cell line from infiltrating lobular breast cancer. IPH-926 displays an ER/PR/ErbB2 triple-negative immunophenotype, which is due to a loss of ER expression in its in vivo clonal ancestry. Loss of ER might indicate a fundamental change of cellular differentiation and it is unclear whether a luminal subtype is preserved beyond ER conversion. Using Affymetrix microarray analysis, seven different classifier gene lists (PAM305, DISC256, TN1288, PAM50, UNC1300, LAB704, INT500) and a background population of 50 common mammary carcinoma cell lines, we have now determined the molecular subtype of IPH-926. Strikingly, the IPH-926 expression profile is highly consistent with a luminal subtype. It is nearest to luminal/ER-positive breast cancer cell lines and far apart from basal breast cancer cell lines. Quantitative real-time RT-PCR confirmed enhanced expression of luminal marker genes (AGR2, CLU, CA12, EMP2, CLDN3) and low or absent expression of basal marker genes (KRT5, CD44, CAV1, VIM). Moreover, IPH-926 lacked androgen receptor (AR) expression, a transcription factor previously associated with luminal-like gene expression in a subset of triple-negative or molecular apocrine breast cancers. In conclusion, IPH-926 is triple-negative but belongs to the luminal subtype. Luminal differentiation characteristics can be preserved beyond ER conversion and might not require a compensatory expression of AR.

Pogue-Geile KL, Kim C, Jeong JH, et al.
Predicting degree of benefit from adjuvant trastuzumab in NSABP trial B-31.
J Natl Cancer Inst. 2013; 105(23):1782-8 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-31 suggested the efficacy of adjuvant trastuzumab, even in HER2-negative breast cancer. This finding prompted us to develop a predictive model for degree of benefit from trastuzumab using archived tumor blocks from B-31.
METHODS: Case subjects with tumor blocks were randomly divided into discovery (n = 588) and confirmation cohorts (n = 991). A predictive model was built from the discovery cohort through gene expression profiling of 462 genes with nCounter assay. A predefined cut point for the predictive model was tested in the confirmation cohort. Gene-by-treatment interaction was tested with Cox models, and correlations between variables were assessed with Spearman correlation. Principal component analysis was performed on the final set of selected genes. All statistical tests were two-sided.
RESULTS: Eight predictive genes associated with HER2 (ERBB2, c17orf37, GRB7) or ER (ESR1, NAT1, GATA3, CA12, IGF1R) were selected for model building. Three-dimensional subset treatment effect pattern plot using two principal components of these genes was used to identify a subset with no benefit from trastuzumab, characterized by intermediate-level ERBB2 and high-level ESR1 mRNA expression. In the confirmation set, the predefined cut points for this model classified patients into three subsets with differential benefit from trastuzumab with hazard ratios of 1.58 (95% confidence interval [CI] = 0.67 to 3.69; P = .29; n = 100), 0.60 (95% CI = 0.41 to 0.89; P = .01; n = 449), and 0.28 (95% CI = 0.20 to 0.41; P < .001; n = 442; P(interaction) between the model and trastuzumab < .001).
CONCLUSIONS: We developed a gene expression-based predictive model for degree of benefit from trastuzumab and demonstrated that HER2-negative tumors belong to the moderate benefit group, thus providing justification for testing trastuzumab in HER2-negative patients (NSABP B-47).

Valet F, de Cremoux P, Spyratos F, et al.
Challenging single- and multi-probesets gene expression signatures of pathological complete response to neoadjuvant chemotherapy in breast cancer: experience of the REMAGUS 02 phase II trial.
Breast. 2013; 22(6):1052-9 [PubMed] Related Publications
This study was designed to identify predictive signatures of pathological complete response (pCR) in breast cancer treated by taxane-based regimen, using clinicopathological variables and transcriptomic data (Affymetrix Hgu133 Plus 2.0 devices). The REMAGUS 02 trial (n = 153,training set) and the publicly available M.D. Anderson data set (n = 133, validation set) were used. A re-sampling method was applied. All predictive models were defined using logistic regression and their classification performances were tested through Area Under the Curve (AUC) estimation. A stable set of 42 probesets (31 genes) differentiate pCR or no pCR samples. Single-or 2-probesets signatures, mainly related to ER pathway, were equally predictive of pCR with AUC greater then 0.80. Models including probesets associated with ESR1, MAPT, CA12 or PIGH presented good classification performances. When clinical variables were entered into the model, only CA12 and PIGH, remained informative (p = 0.05 and p = 0.005) showing that a combination of a few genes provided robust and reliable prediction of pCR.

Gondi G, Mysliwietz J, Hulikova A, et al.
Antitumor efficacy of a monoclonal antibody that inhibits the activity of cancer-associated carbonic anhydrase XII.
Cancer Res. 2013; 73(21):6494-503 [PubMed] Related Publications
Carbonic anhydrase XII (CA XII) is a membrane-tethered cell surface enzyme that is highly expressed on many human tumor cells. Carbonic anhydrase members in this class of exofacial molecules facilitate tumor metabolism by facilitating CO2 venting and intracellular pH regulation. Accordingly, inhibition of exofacial CAs has been proposed as a general therapeutic strategy to target cancer. The recent characterization of 6A10, the first CA XII-specific inhibitory monoclonal antibody, offered an opportunity to evaluate this strategy with regard to CA XII-mediated catalysis. Using functional assays, we showed that 6A10 inhibited exofacial CA activity in CA XII-expressing cancer cells. 6A10 reduced spheroid growth in vitro under culture conditions where CA XII was active (i.e., alkaline pH) and where its catalytic activity was likely rate-limiting (i.e., restricted extracellular HCO3-supply). These in vitro results argued that the antibody exerted its growth-retarding effect by acting on the catalytic process, rather than on antigen binding per se. Notably, when administered in a mouse xenograft model of human cancer, 6A10 exerted a significant delay on tumor outgrowth. These results corroborate the notion that exofacial CA is critical for cancer cell physiology and they establish the immunotherapeutic efficacy of targeting CA XII using an inhibitory antibody.

Kim HJ, Chung JH, Shin HP, et al.
Polymorphisms of interferon gamma gene and risk of hepatocellular carcinoma in korean patients with chronic hepatitis B viral infection.
Hepatogastroenterology. 2013 Jul-Aug; 60(125):1117-20 [PubMed] Related Publications
BACKGROUNDS/AIMS: Increasing evidence supports the contribution of the pro-/anti-inflammatory cytokine balance and genetic factors to hepatocellular carcinoma (HCC). Here, we investigated whether genetic interferon gamma polymorphisms were associated with HCC in Korean patients with chronic hepatitis B.
METHODOLOGY: We genotyped a single nucleotide polymorphism (SNP, rs2430561, +874A/T) and a microsatellite (rs3138557, (CA)n repeat), located in the first intron of the interferon gamma gene, by direct sequencing and the gene scan method. A population-based case-control study of HCC was conducted and included 170 patients with chronic hepatitis and HCC, and 171 with chronic hepatitis B patients without hepatocellular carcinoma in a Korean population.
RESULTS: Genotype and allele distributions of the interferon gamma gene SNP were associated with HCC. The frequencies of the AA genotype and the A allele were significantly increased in hepatocellular carcinoma subjects (p<0.05). Combined analysis using the genotype of rs2430561 and the number of microsatellites revealed that the frequencies of AT-CA12 and TT-CA12 increased significantly in hepatocellular carcinoma subjects (p<0.0001).
CONCLUSIONS: Our results suggest that the interferon gamma gene may be a susceptibility gene and a risk factor for HCC in the Korean population.

Chiche J, Ricci JE, Pouysségur J
Tumor hypoxia and metabolism -- towards novel anticancer approaches.
Ann Endocrinol (Paris). 2013; 74(2):111-4 [PubMed] Related Publications
The transcription factor hypoxia-inducible factor-1 (HIF-1) facilitates the induction of enzymes necessary for regulation of biological processes required for cell survival and the acquisition of an aggressive and invasive phenotype, such as regulation of the intracellular pH (pHi), anaerobic glycolysis, angiogenesis, migration/invasion... In this presentation, we will highlight some of the HIF-1-induced gene products - carbonic anhydrases IX and XII (CAs) and monocarboxylate transporters (MCTs) - which regulate the pHi by controlling export of metabolically-generated acids (carbonic and lactic acids). We reported that targeting these pHi-regulated processes through inhibition of either HIF-1-induced CAIX/CAXII or HIF-1-induced MCT4, MCT1 or Basigin/EMMPRIN/CD147 chaperone of MCTs, severely restricts glycolysis-generated ATP levels and tumor growth. In addition, we demonstrated that the Myc/HIF-1-targeted glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzing a key step producing the NADH cofactor, activates the Akt pathway, thereby upregulating expression of the anti-apoptotic Bcl-xL. As a consequence, high expression of GAPDH contributes to tumor aggressiveness, in particular in the context Myc-driven B lymphomas. We propose that membrane-bound carbonic anhydrases (CAIX, CAXII), monocarboxylate transporters/chaperon Basigin (Myc-induced MCT1 and HIF-induced-MCT4) and GAPDH that are associated with exacerbated tumor metabolism, represent new potential targets for anticancer therapy.

Vermeulen JF, Kornegoor R, van der Wall E, et al.
Differential expression of growth factor receptors and membrane-bound tumor markers for imaging in male and female breast cancer.
PLoS One. 2013; 8(1):e53353 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Male breast cancer accounts for 0.5-1% of all breast cancers and is generally diagnosed at higher stage than female breast cancers and therefore might benefit from earlier detection and targeted therapy. Except for HER2 and EGFR, little is known about expression of growth factor receptors in male breast cancer. We therefore investigated expression profiles of growth factor receptors and membrane-bound tumor markers in male breast cancer and gynecomastia, in comparison with female breast cancer.
METHODS: Tissue microarrays containing 133 male breast cancer and 32 gynecomastia cases were stained by immunohistochemistry for a panel of membrane-bound targets and compared with data on 266 female breast cancers.
RESULTS: Growth factor receptors were variably expressed in 4.5% (MET) up to 38.5% (IGF1-R) of male breast cancers. Compared to female breast cancer, IGF1-R and carbonic anhydrase 12 (CAXII) were more frequently and CD44v6, MET and FGFR2 less frequently expressed in male breast cancer. Expression of EGFR, HER2, CAIX, and GLUT1 was not significantly different between male and female breast cancer. Further, 48.1% of male breast cancers expressed at least one and 18.0% expressed multiple growth factor receptors. Since individual membrane receptors are expressed in only half of male breast cancers, a panel of membrane markers will be required for molecular imaging strategies to reach sensitivity. A potential panel of markers for molecular imaging, consisting of EGFR, IGF1-R, FGFR2, CD44v6, CAXII, GLUT1, and CD44v6 was positive in 77% of male breast cancers, comparable to female breast cancers.
CONCLUSIONS: Expression patterns of growth factor receptors and hypoxia membrane proteins in male breast cancer are different from female breast cancer. For molecular imaging strategies, a putative panel consisting of markers for EGFR, IGF1-R, FGFR2, GLUT1, CAXII, CD44v6 was positive in 77% of cases and might be considered for development of molecular tracers for male breast cancer.

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