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

Targeting hypoxia in the treatment of small cell lung cancer

Small cell lung cancer (SCLC) is an extremely aggressive disease for which minimal therapeutic improvements have been made over the last few decades. Patients still rely on non-targeted, chemotherapeutic drugs complemented by irradiation. Although initial response is very good, the majority of SCLC patients invariably relapse with therapy-resistant tumours. Despite the link between pathologically low oxygen levels and therapy resistant tumours, hypoxia has gained little attention in the development of novel therapies for SCLC. In contrast, the advantages of targeting hypoxic cells in many other cancer types have been studied extensively. This review describes the reasons for targeting hypoxia in SCLC and outlines strategies undertaken to enhance hypoxic tumour cell death, including the use of bioreductive prodrugs, the targeting of HIF-1α and the induction of cell death through acidosis. Therapy directed towards hypoxic tumour regions has the potential to greatly enhance the response of SCLC tumours to current treatment regimens and represents an area of research in need of greater attention. Such research could lead to the much sought after development of targeted drugs against SCLC tumours.

Hypoxia-induced carbonic anhydrase IX as a target for cancer therapy: from biology to clinical use

The tumor microenvironment includes a complicated network of physiological gradients contributing to plasticity of tumor cells and heterogeneity of tumor tissue. Hypoxia is a key component generating intratumoral oxygen gradients, which affect the cellular expression program and lead to therapy resistance and increased metastatic propensity of weakly oxygenated cell subpopulations. One of the adaptive responses of tumor cells to hypoxia involves the increased expression and functional activation of carbonic anhydrase IX (CA IX), a cancer-related cell surface enzyme catalyzing the reversible conversion of carbon dioxide to bicarbonate ion and proton. Via its catalytic activity, CA IX participates in regulation of intracellular and extracellular pH perturbations that result from hypoxia-induced changes in cellular metabolism producing excess of acid. Through the ability to regulate pH, CA IX also facilitates cell migration and invasion. In addition, CA IX has non-catalytic function in cell adhesion and spreading. Thus, CA IX endows tumor cells with survival advantages in hypoxia/acidosis and confers an increased ability to migrate, invade and metastasize. Accordingly, CA IX is expressed in a broad range of tumors, where it is associated with prognosis and therapy outcome. Its expression pattern and functional implications in tumor biology make CA IX a promising therapeutic target, which can be hit either by immunotherapy with monoclonal antibodies or with compounds inhibiting its enzyme activity. The first strategy has already reached the clinical trials, whereas the second one is still in preclinical testing. Both strategies indicate that CA IX can become a clinically useful anticancer target, but urge further efforts toward better selection of patients for immunotherapy and deeper understanding of tumor types, clinical situations and synthetic lethality interactions with other treatment approaches.

Carbonic anhydrase IX-directed immunoliposomes for targeted drug delivery to human lung cancer cells in vitro

Targeted drug delivery to cancer cells by use of antibody-conjugated liposomes (immunoliposomes) has attracted considerable interest in recent years. Despite increasing efforts in developing immunoliposomes as drug carriers, the investigation of useful tumor-associated antigen targets is far from complete. Carbonic anhydrase IX (CA IX) is a cell surface antigen characterized by hypoxia-induced expression in many solid tumors. This study investigated the feasibility of CA IX-directed immunoliposomes for targeted delivery of docetaxel to human lung cancer cells in vitro. Docetaxel-loaded immunoliposomes targeting CA IX were developed with an encapsulation efficiency of 84.4±3.9% and an average particle size of 143.9±11.1 nm. Using fluorescence-based flow cytometry, the in vitro binding activity of the immunoliposomes was found to be significantly higher (by 1.65-fold) than that of the nontargeted liposomes in CA IX-positive lung cancer cells, whereas no such difference was observed between the two groups when CA IX was not expressed. Furthermore, immunoliposomal docetaxel exhibited the strongest growth inhibitory effect against CA IX-positive lung cancer cells when compared with nontargeted liposomal docetaxel or free docetaxel solution. These data suggested that CA IX-directed immunoliposomes could serve as a promising drug delivery system for targeted killing of lung cancer cells.

Carbonic anhydrase IX, a hypoxia-induced catalytic component of the pH regulating machinery in tumors

Acidic tissue microenvironment contributes to tumor progression via multiple effects including the activation of angiogenic factors and proteases, reduced cell-cell adhesion, increased migration and invasion, etc. In addition, intratumoral acidosis can influence the uptake of anticancer drugs and modulate the response of tumors to conventional therapy. Acidification of the tumor microenvironment often develops due to hypoxia-triggered oncogenic metabolism, which leads to the extensive production of lactate, protons, and carbon dioxide. In order to avoid intracellular accumulation of the acidic metabolic products, which is incompatible with the survival and proliferation, tumor cells activate molecular machinery that regulates pH by driving transmembrane inside-out and outside-in ion fluxes. Carbonic anhydrase IX (CA IX) is a hypoxia-induced catalytic component of the bicarbonate import arm of this machinery. Through its catalytic activity, CA IX directly participates in many acidosis-induced features of tumor phenotype as demonstrated by manipulating its expression and/or by in vitro mutagenesis. CA IX can function as a survival factor protecting tumor cells from hypoxia and acidosis, as a pro-migratory factor facilitating cell movement and invasion, as a signaling molecule transducing extracellular signals to intracellular pathways (including major signaling and metabolic cascades) and converting intracellular signals to extracellular effects on adhesion, proteolysis, and other processes. These functional implications of CA IX in cancer are supported by numerous clinical studies demonstrating the association of CA IX with various clinical correlates and markers of aggressive tumor behavior. Although our understanding of the many faces of CA IX is still incomplete, existing knowledge supports the view that CA IX is a biologically and clinically relevant molecule, exploitable in anticancer strategies aimed at targeting adaptive responses to hypoxia and/or acidosis.

Carbonic anhydrase IX: a promising diagnostic and prognostic biomarker in breast carcinoma

We examined the expression of carbonic anhydrase IX (CA IX) by immunohistochemical staining using monoclonal antibody M75 (Institute of Virology, Slovak Academy of Sciences, Bratislava) in a group of 38 fibroadenomas and 55 carcinomas of the breast. In each case, the intensity of staining, percentage of labeled cells and subcellular localization of CA IX were assessed. CA IX was detected in 11/38 fibroadenomas (28.9%). Weak cytoplasmic positivity was dominant in these positive cases. Immunohistochemical analysis of 55 carcinomas showed CA IX expression in 34 cases (61.8%). Membrane staining alone was observed in 27/55 carcinomas (49.1%), while cytoplasmic positivity was found in 4/55 cases (7.3%). Combined membrane and cytoplasmic immunostaining of CA IX was detected in 3/55 carcinomas (5.4%). The intensity of immunoreactivity varied from weak to strong. Under 50% of reactive cells were found in 9/38 fibroadenomas (23.6%) and in 29/55 carcinomas (52.7%). More than 50% of reactive cells were found in 2/38 fibroadenomas (5.3%) and in 5/55 carcinomas (9.1%). Statistical analysis confirmed significant differences in the subcellular localization, intensity of immunoreactivity and percentage of labeled cells in fibroadenomas and carcinomas (p<0.05). Our results confirmed the hypothesis that expression of CA IX may represent a valuable tumor biomarker as well as a promising diagnostic and prognostic parameter in breast cancer.

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.

A pilot study on potential plasma hypoxia markers in the radiotherapy of non-small cell lung cancer. Osteopontin, carbonic anhydrase IX and vascular endothelial growth factor

BACKGROUND

Hypoxic radioresistance plays a critical role in the radiotherapy of cancer and adversely impacts prognosis and treatment response. This prospective study investigated the interrelationship and the prognostic significance of several hypoxia-related proteins in non-small cell lung cancer (NSCLC) patients treated by radiotherapy ± chemotherapy.

MATERIAL AND METHODS

Pretreatment osteopontin (OPN), vascular endothelial growth factor (VEGF) and carbonic anhydrase IX (CA IX) plasma levels were determined by ELISA in 55 NSCLC (M0) patients receiving 66 Gy curative-intent radiotherapy or chemoradiation. Marker correlation, association with clinicopathological parameters and the prognostic value of a biomarker combination was evaluated.

RESULTS

All biomarkers were linearly correlated and linked to different clinical parameters including lung function, weight loss (OPN), gross tumor volume (VEGF) and T stage (CA IX). High OPN (p = 0.03), VEGF (p = 0.02) and CA IX (p = 0.04) values were significantly associated with poor survival. Double marker combination additively increased the risk of death by a factor of 2 and high plasma levels of the triple combination OPN/VEGF/CA IX yielded a 5.9-fold risk of death (p = 0.009). The combined assessment of OPN/VEGF/CA IX correlated independently with prognosis (p = 0.03) in a multivariate Cox regression model including N stage, T stage and GTV.

CONCLUSION

This pilot study suggests that a co-detection augments the prognostic value of single markers and that the integration of OPN, VEGF and CA IX into a hypoxic biomarker profile for the identification of patients with largely hypoxic and radioresistant tumors should be further evaluated.

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

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

Plasma osteopontin is a useful diagnostic biomarker for advanced non-small cell lung cancer

Background

Osteopontin (OPN) and carbonic anhydrase IX (CAIX), which are expressed on the surface of tumor cells, are associated with hypoxia during tumor development and progression. However, the roles of these proteins in the plasma of patients with non-small cell lung cancer (NSCLC) are poorly understood. Herein, we hypothesized that plasma OPN and CAIX levels could be used as diagnostic and prognostic tumor markers in patients with NSCLC.

Methods

Fifty-three patients with NSCLC and 50 healthy control subjects were enrolled. We selected controls without malignancy and matched them with NSCLC patient cases according to age and gender. Blood samples were collected at the time of diagnosis; the plasma levels of OPN and CAIX were measured by enzyme-linked immunosorbent assays.

Results

The plasma levels of OPN in the patients with NSCLC were significantly elevated as compared to those in the controls (p=0.016). However, there was no difference in the plasma level of CAIX between the NSCLC patients and controls. NSCLC patients with a distant metastasis had a remarkable increase in plasma OPN compared with patients without metastasis (p=0.026), but no such correlation was found for CAIX. There was no difference in overall survival rates according to the plasma level of OPN between the two groups (by Kaplan-Meier survival analysis).

Conclusion

Plasma OPN levels were elevated in patients with NSCLC as compared with the controls, with greater elevation of OPN levels in the advanced stages of disease. Therefore, plasma OPN may have utility as a diagnostic, but not prognostic, biomarker of advanced NSCLC.

Response of CAIX and CAXII to in vitro re-oxygenation and clinical significance of the combined expression in NSCLC patients

The disorganized neo-vasculature in tumours causes fluctuations in the concentration of oxygen, which contributes to tumour development and metastatic potential. Although hypoxic regulation of the expression of the carbonic anhydrases CAIX and CAXII is well established, the effect of re-oxygenation on these proteins remains to be elucidated. A549 and H1975 human lung cancer cell lines were exposed to hypoxia for 24 h and then re-oxygenated. CAIX or CAXII expression and cell cycle progression at different time-points were monitored. A549-shCA9 cells were analyzed for cell cycle progression in the same conditions. We demonstrate for the first time an association between the stability of CAIX and restoration of the S/G2 phase of hypoxia-arrested cells subjected to re-oxygenation. In exchange, we have found that the loss of CA9 did not cause a decreased progression into S/G2 phase during re-oxygenation, but rather affected the hypoxic growth arrest. We previously demonstrated that CAIX expression is a poor prognostic factor and that CAXII expression is a good prognostic factor in non-small cell lung cancer (NSCLC) patients. We further detail the relevance of the combined expression of these proteins for predicting outcome in a large population of NSCLC patients after long-term follow-up. The high CAIX/low CAXII expression sub-group was associated with a high cumulative incidence of relapse and with poor overall survival of NSCLC patients (P < 0.0001). Our results demonstrate a critical role for re-oxygenation on CAIX and CAXII levels that may select for an aggressive lung cancer phenotype. These findings suggest that CAIX and CAXII play dual roles in tumour progression and emphasize their significant prognostic and potential therapeutic value.

Podoplanin-positive cancer-associated fibroblasts could have prognostic value independent of cancer cell phenotype in stage I lung squamous cell carcinoma: usefulness of combining analysis of both cancer cell phenotype and cancer-associated fibroblast phenotype

BACKGROUND

The prognostic significance of the tumor microenvironment, which is created by both cancer cells and cancer-associated fibroblasts (CAFs), has been increasingly recognized. The purpose of this study was to analyze the prognostic markers of stage I squamous cell carcinoma (SqCC), with special reference to the immunophenotypes of both cancer cells and CAFs.

METHODS

A total of 142 patients with stage I SqCC were included in this study. We examined the expressions of E-cadherin, laminin-5, podoplanin, c-MET, carbonic anhydrase IX (CA-IX), CD10, and CD44 in the cancer cells and those of podoplanin, CA-IX, CD10, and CD44 in the CAFs to evaluate their prognostic value.

RESULTS

Patients with low E-cadherin expression in the cancer cells showed a significantly poorer prognosis than those with high E-cadherin expression in the cancer cells ( P , .001). On the other hand, high podoplanin expression in the CAFs was also associated with a significantly poorer prognosis ( P , .001). A multivariate analysis identified low E-cadherin expression in the cancer cells and high podoplanin expression in the CAFs as significantly independent prognostic factors for overall survival ( P 5 .013 and P 5 .0011, respectively). According to subgroup analyses combining E-cadherin expression in cancer cells and podoplanin expression in CAFs, 5-year overall survival of patients with low E-cadherin expression in the cancer cells and high podoplanin expression in the CAFs was 7.0% and showed a significantly poorer prognosis as compared with other groups ( P , .001).

CONCLUSIONS

The current study indicates that immunophenotypes of CAFs could have a prognostic value independent of those of the cancer cells in SqCC.

Comparison of 18F-fluoroazomycin-arabinofuranoside and 64Cu-diacetyl-bis(N4-methylthiosemicarbazone) in preclinical models of cancer

Hypoxic regions are present in different types of cancer and are a negative prognostic factor for disease progression and response to therapy. (18)F-fluoroazomycin-arabinofuranoside ((18)F-FAZA) and (64)Cu-diacetyl-bis(N4-methylthiosemicarbazone) ((64)Cu-ATSM) have been widely used to visualize hypoxic regions in preclinical and clinical studies. Although both these radioligands have high signal-to-noise ratios, (64)Cu-ATSM may be suitable for use in in vivo imaging and as a radiotherapeutic agent. Despite encouraging results suggesting that it may have a role as a prognostic tracer, (64)Cu-ATSM was recently shown to display cell line-dependent kinetics of oxygen-dependent uptake. We set out to evaluate the kinetics of (64)Cu-ATSM distribution in different cancer models, using (18)F-FAZA as the gold standard.

METHODS

(18)F-FAZA and (64)Cu-ATSM uptake were compared ex vivo using dual-tracer autoradiography and in vivo using PET in different xenograft mouse models (FaDu, EMT-6, and PC-3). (18)F-FAZA uptake was compared with (64)Cu-ATSM uptake in PET studies acquired at early (2 h after injection) and delayed time points (24 h after injection). To evaluate the presence of hypoxia and copper pumps, the tumors from animals submitted to PET were harvested and analyzed by an immunohistochemical technique, using antibodies against carbonic anhydrase IX (CAIX) and copper pumps (Ctr1 and ATP7B).

RESULTS

(64)Cu-ATSM showed a higher tumor-to-muscle ratio than did (18)F-FAZA. In the FaDu mouse model, radioactivity distribution profiles were overlapping irrespective of the hypoxic agent injected or the time of (64)Cu acquisition. Conversely, in the EMT-6 and PC-3 models there was little similarity between the early and delayed (64)Cu-ATSM images, and both the radiotracers showed a heterogeneous distribution. The microscopic analysis revealed that (18)F-FAZA-positive areas were also positive for CAIX immunostaining whereas immunolocalization for copper pumps in the 3 models was not related to radioactivity distribution.

CONCLUSION

The results of this study confirm the cell-dependent distribution and retention kinetics of (64)Cu-ATSM and underline the need for proper validation of animal models and PET acquisition protocols before exploration of any new clinical applications.

Identification of proteomic signatures associated with lung cancer and COPD

Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) commonly coexist in smokers, and the presence of COPD increases the risk of developing LC. The aim of this study was to identify distinct proteomic profiles able to discriminate these two pathological entities. Protein content was assessed in the bronchoalveolar lavage (BAL) of 60 patients classified in four groups: COPD, COPD and LC, LC without COPD, and control with neither COPD nor LC. Proteins were separated into spots by bidimensional polyacrylamide gel electrophoresis (2D-PAGE) and examined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/TOF). A total of 40 proteins were differentially expressed in the LC and/or COPD groups as compared with the control group. Distinct protein profiles were identified and validated for each pathological entity (LC and COPD). The main networks involved were related to inflammatory signalling, free radical scavenging and oxidative stress response, and glycolysis and gluconeogenesis pathways. The most relevant signalling link between LC and COPD was through the NF-κB pathway. In conclusion, the protein profiles identified contribute to elucidate the underlying pathogenic pathways of both diseases, and provide new tools of potential use as biomarkers for the early diagnosis of LC.

BIOLOGICAL SIGNIFICANCE

Sequence coverage. The protein sequence coverage (95%) was estimated for specific proteins by the percentage of matching amino acids from the identified peptides having confidence greater than or equal to 95% divided by the total number of amino acids in the sequence. Ingenuity Pathways Analysis. Mapping of our proteins onto biological pathways and disease networks demonstrated that 22 proteins were linked to inflammatory signalling (p-value: 1.35 10(-08)-1.42 10(-02)), 15 proteins were associated with free radical scavenging and oxidative stress response (p-value: 4.93 10(-11)-1.27 10(-02)), and 9 proteins were related with glycolysis and gluconeogenesis pathways (p-value: 7.39 10(-09)-1.58 10(-02)).

Microenvironment and tumor cell plasticity: an easy way out

Cancer cells undergo genetic changes allowing their adaptation to environmental changes, thereby obtaining an advantage during the long metastatic route, disseminated of several changes in the surrounding environment. In particular, plasticity in cell motility, mainly due to epigenetic regulation of cancer cells by environmental insults, engage adaptive strategies aimed essentially to survive in hostile milieu, thereby escaping adverse sites. This review is focused on tumor microenvironment as a collection of structural and cellular elements promoting plasticity and adaptive programs. We analyze the role of extracellular matrix stiffness, hypoxia, nutrient deprivation, acidity, as well as different cell populations of tumor microenvironment.

Crohn disease-associated Escherichia coli promote gastrointestinal inflammatory disorders by activation of HIF-dependent responses

Crohn disease (CD) ileal lesions are colonized by adherent-invasive E. coli (AIEC) that locally induce inflammation. Hypoxia inducible factor (HIF)-1alpha protein is expressed in acute and chronically inflamed site; however the molecular basis of this expression is not fully understood. The aim of the study was to access whether AIEC induce HIF-1α expression and to study the consequence of HIF-1α expression on the onset of Crohn disease pathogenesis. We show that HIF-1α is maximally expressed in inflamed ileal epithelium of CD-patients. CEACAM6, a protein that acts as a receptor of AIEC, is expressed in this particular condition. Using CEABAC 10 transgenic mice that express CEACAM6, we show that AIEC bacteria, but not non-pathogenic E. coli K12, induce the production of HIF-1alpha protein and the activation of VEGF/VEGFR signaling. Downstream analyses on human intestinal epithelial cells silenced for hif- 1α, highlight the crucial role of this protein in production of pro-angiogenic factors. This study highlights the crucial role of AIEC bacteria as promoter of inflammatory disorders of the gastrointestinal tract and provides clear evidence that HIF-1α protein plays a major role in mediating this effect.

Potential molecular approaches for the early diagnosis of lung cancer (review)

Lung cancer is the leading cause of mortality from cancer among men and women worldwide. More individuals die each year of lung cancer than of colon, breast and prostate cancer combined. Despite new diagnostic techniques, the overall 5-year survival rate remains at approximately 15% and the majority of patients still present with advanced disease. Therefore, lung cancer is the most lethal cancer at present. Diagnosing and treating cancer at its early stages, ideally during the precancerous stages, could increase the 5-year survival rate by 3-4‑fold, with the possibility of cure. To date, no screening method has been shown to decrease the disease-specific mortality rate. This review describes issues related to early lung cancer screening and their rationale, the management of primary cancers detected by screening and the different approaches that have been tested for cancer screening; these include imaging techniques, bronchoscopies and molecular screening, such as analysis of epigenomics using different noninvasive or invasive sources, such as blood, sputum, bronchoscopic samples and exhaled breath.

Operable non-small cell lung cancer: correlation of volumetric helical dynamic contrast-enhanced CT parameters with immunohistochemical markers of tumor hypoxia

PURPOSE

To assess the relationship between helical dynamic contrast material-enhanced (DCE) computed tomographic (CT) parameters and immunohistochemical markers of hypoxia in patients with operable non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

After institutional review board approval was obtained, 20 prospective patients who were suspected of having NSCLC underwent whole-tumor DCE CT with kinetic modeling (Patlak analysis) 24 hours before scheduled surgery. Flow-extraction product (in milliliters per 100 milliliters per minute) and blood volume (in milliliters per 100 milliliters) were derived. After surgery, matched whole-tumor sections were stained for exogenous and endogenous markers of hypoxia (pimonidazole infused intravenously 24 hours before surgery, immediately after DCE CT; glucose transporter protein). Correlation between DCE CT parameters and immunohistochemical markers was assessed by using the Spearman rank correlation. DCE CT parameters and immunohistochemical markers were also compared according to pathologic subtype, grade, stage, and nodal status by using the Mann-Whitney test. P values less than .05 indicated a statistically significant difference.

RESULT

Fourteen patients with confirmed primary NSCLC underwent resection. There were negative correlations between blood volume and pimonidazole staining (r = -0.48, P = .004), and between flow-extraction product and glucose transporter protein expression (r = -0.50, P = .002). Flow-extraction product was significantly higher in adenocarcinomas than in squamous cell tumors (17.73 vs 11.46; P = .043). Glucose transporter protein expression was significantly lower for adenocarcinomas than for squamous tumors (14.07 vs 33.03; P < .001) and in node negative than in node positive tumors (15.63 vs 23.85; P = .005).

CONCLUSION

Blood volume and flow-extraction product derived at DCE CT correlated negatively with pimonidazole and glucose transporter protein expression, indicating the potential of these CT parameters as imaging biomarkers of hypoxia.

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.

Predictive clinical outcome of the intratumoral CD66b-positive neutrophil-to-CD8-positive T-cell ratio in patients with resectable nonsmall cell lung cancer

BACKGROUND

The role of the interaction between tumor cells and inflammatory cells in nonsmall cell lung carcinoma (NSCLC) is unclear. In this study, the authors assessed the prognostic impact of intratumoral cluster of differentiation 66b (carcinoembryonic antigen-related cell adhesion molecule 8 [CD66b])-positive neutrophils and of the intratumoral CD66b-positive neutrophil-to-cluster of differentiation 8 (cell surface antigen T8 [CD8])-positive lymphocytes (the CD66b-positive neutrophil-to-CD8-positive lymphocyte ratio [iNTR]) in patients with resectable NSCLC.

METHODS

Expression levels of CD66b and CD8 were evaluated by immunohistochemistry on tissue microarrays consisting of 632 NSCLC specimens from patients who underwent curative surgery. The relation between clinicopathologic variables and patient outcome was assessed.

RESULTS

Intratumoral CD66b-positive neutrophils were elevated in 318 patients (50%). In univariate analysis, an increase in CD66b-positive cells was associated with a high cumulative incidence of relapse (CIR) (median CIR, 51 months for low CD66b-positive cell density; 36 months for high CD66b-positive cell density; P = .002) and trended toward worse overall survival (OS) (median OS, 57 months for low CD66b-positive cell density; 54 months for high CD66b-positive cell density; P = .088). The iNTR was elevated in 190 patients (30%). An increased iNTR was strongly associated with both a high CIR (median CIR: 43 months for an iNTR ≤1; 34 months for an iNTR >1; P < .0001) and poor OS (median OS: 60 months for an iNTR ≤1; 46 months for an iNTR >1; P < .0001). In multivariate analysis, independent prognostic factors for a higher CIR were high iNTR (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.56-0.90; P = .005) and tumor stage >I, (HR, 0.39; 95% CI, 0.30-0.52; P < .0001). Independent prognostic factors for worse OS were a high iNTR (HR, 0.70; 95% CI, 0.54-0.91; P = .007) and tumor stage >I (HR, 0.35; 95% CI, 0.26-0.47; P < .0001).

CONCLUSIONS

The current results indicated that the iNTR is a novel, independent prognostic factor for a high rate of disease recurrence and poor OS in patients with resectable NSCLC.

Expression of a truncated active form of VDAC1 in lung cancer associates with hypoxic cell survival and correlates with progression to chemotherapy resistance

Resistance to chemotherapy-induced apoptosis of tumor cells represents a major hurdle to efficient cancer therapy. Although resistance is a characteristic of tumor cells that evolve in a low oxygen environment (hypoxia), the mechanisms involved remain elusive. We observed that mitochondria of certain hypoxic cells take on an enlarged appearance with reorganized cristae. In these cells, we found that a major mitochondrial protein regulating metabolism and apoptosis, the voltage-dependent anion channel 1 (VDAC1), was linked to chemoresistance when in a truncated (VDAC1-ΔC) but active form. The formation of truncated VDAC1, which had a similar channel activity and voltage dependency as full-length, was hypoxia-inducible factor-1 (HIF-1)-dependent and could be inhibited in the presence of the tetracycline antibiotics doxycycline and minocycline, known inhibitors of metalloproteases. Its formation was also reversible upon cell reoxygenation and associated with cell survival through binding to the antiapoptotic protein hexokinase. Hypoxic cells containing VDAC1-ΔC were less sensitive to staurosporine- and etoposide-induced cell death, and silencing of VDAC1-ΔC or treatment with the tetracycline antibiotics restored sensitivity. Clinically, VDAC1-ΔC was detected in tumor tissues of patients with lung adenocarcinomas and was found more frequently in large and late-stage tumors. Together, our findings show that via induction of VDAC1-ΔC, HIF-1 confers selective protection from apoptosis that allows maintenance of ATP and cell survival in hypoxia. VDAC1-ΔC may also hold promise as a biomarker for tumor progression in chemotherapy-resistant patients.

Prognostic impacts of hypoxic markers in soft tissue sarcoma

Background. We aimed to explore the prognostic impact of the hypoxia-induced factors (HIFαs) 1 and 2, the metabolic HIF-regulated glucose transporter GLUT-1, and carbonic anhydrase IX (CAIX) in non-gastrointestinal stromal tumor soft tissue sarcomas (non-GIST STS). Methods. Duplicate cores with viable tumor tissue from 206 patients with non-GIST STS were obtained and tissue microarrays were constructed. Immunohistochemistry (IHC) was used to evaluate expression of hypoxic markers. Results. In univariate analyses, GLUT-1 (P < 0.001) and HIF-2α (P = 0.032) expression correlated significantly with a poor disease-specific survival (DSS). In the multivariate analysis, however, only high expression of GLUT-1 (HR 1.7, CI 95% 1.1–2.7, P = 0.021) was a significant independent prognostic indicator of poor DSS. Conclusion. GLUT-1 is a significant independent negative prognostic factor in non-GIST STS.

Proteomic analysis of human saliva from lung cancer patients using two-dimensional difference gel electrophoresis and mass spectrometry

Lung cancer is often asymptomatic or causes only nonspecific symptoms in its early stages. Early detection represents one of the most promising approaches to reduce the growing lung cancer burden. Human saliva is an attractive diagnostic fluid because its collection is less invasive than that of tissue or blood. Profiling of proteins in saliva over the course of disease progression could reveal potential biomarkers indicative of oral or systematic diseases, which may be used extensively in future medical diagnostics. There were 72 subjects enrolled in this study for saliva sample collection according to the approved protocol. Two-dimensional difference gel electrophoresis combined with MS was the platform for salivary proteome separation, quantification, and identification from two pooled samples. Candidate proteomic biomarkers were verified and prevalidated by using immunoassay methods. There were 16 candidate protein biomarkers discovered by two-dimensional difference gel electrophoresis and MS. Three proteins were further verified in the discovery sample set, prevalidation sample set, and lung cancer cell lines. The discriminatory power of these candidate biomarkers in lung cancer patients and healthy control subjects can reach 88.5% sensitivity and 92.3% specificity with AUC = 0.90. This preliminary data report demonstrates that proteomic biomarkers are present in human saliva when people develop lung cancer. The discriminatory power of these candidate biomarkers indicate that a simple saliva test might be established for lung cancer clinical screening and detection.

Role of FDG-PET as a biological marker for predicting the hypoxic status of tongue cancer

BACKGROUND

To determine whether 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) could serve as a useful technique predicting tumor hypoxia and prognosis in tongue cancer, we assessed the relationship between FDG uptake and the levels of hypoxia-related markers.

METHODS

Tumor uptake of FDG in 33 patients with T2 tongue cancer was assessed by measuring maximum standardized uptake values (SUVmax). Expression of hypoxia-inducible factor (HIF)-1α, carbonic anhydrase (CA)-9, glucose transporter (GLUT)-1, and erythropoietin receptor (EPOR), was determined by immunohistochemical staining. Correlation between SUVmax and the expression of hypoxia-related markers was assessed and multivariate analysis was performed to determine what parameters affected clinical outcomes.

RESULTS

We observed strong correlations between SUVmax and expression of HIF-1α (p < .05), CA-9 (p < .01), and GLUT-1 (p < .01). SUVmax, HIF-1α expression, and tumor grade were significant independent predictors of disease-free survival (DFS).

CONCLUSION

SUVmax may be a good noninvasive biomarker for prediction of hypoxic status and prognosis of patients with T2 tongue cancer.

Dysregulated pH: a perfect storm for cancer progression

Although cancer is a diverse set of diseases, cancer cells share a number of adaptive hallmarks. Dysregulated pH is emerging as a hallmark of cancer because cancers show a 'reversed' pH gradient with a constitutively increased intracellular pH that is higher than the extracellular pH. This gradient enables cancer progression by promoting proliferation, the evasion of apoptosis, metabolic adaptation, migration and invasion. Several new advances, including an increased understanding of pH sensors, have provided insight into the molecular basis for pH-dependent cell behaviours that are relevant to cancer cell biology. We highlight the central role of pH sensors in cancer cell adaptations and suggest how dysregulated pH could be exploited to develop cancer-specific therapeutics.

Measuring carbonic anhydrase IX as a hypoxia biomarker: differences in concentrations in serum and plasma using a commercial enzyme-linked immunosorbent assay due to influences of metal ions

Background

There is increasing interest in measuring the soluble forms of carbonic anhydrase IX (CA IX) in blood as a marker of hypoxia for prognostic purposes or for predictive use in therapeutic trials in various cancers. Following our initial observations of marked differences in the measured concentrations of CA IX in EDTA plasma versus serum, we sought to investigate these further in order to determine their effects on results in published studies and to ensure accurate measurement in future studies.

Methods

Serum and EDTA plasma samples from healthy controls and patients with renal cancer were used in the validation of two commercially available enzyme-linked immunosorbent assays (ELISAs) for CA IX with examination of recovery, parallelism and specificity and comparison of paired plasma and serum.

Results

Successful validation of one of the ELISAs was not achieved with particular problems with parallelism and marked differences in measured CA IX concentrations between EDTA plasma and serum. This appeared to be due to a metal ion-dependent epitope on CA IX recognized by the detection antibody in this assay. The other commercially available ELISA examined was successfully validated and showed no difference in CA IX between EDTA plasma and serum.

Conclusions

These results have important consequences for published studies using this assay where the conclusions drawn from the measurements made may be invalid. This study highlights the need for stringent validation of commercially available assays, including examination of various sample types, before use in research studies.

pH control mechanisms of tumor survival and growth

A distinguishing phenotype of solid tumors is the presence of an alkaline cellular feature despite the surrounding acidic microenvironment. This phenotypic characteristic of tumors, originally described by Otto Warburg, arises due to alterations in metabolism of solid tumors. Hypoxic regions of solid tumors develop due to poor vascularization and in turn regulate the expression of numerous genes via the transcription factor HIF-1. Ultimately, the tumor microenvironment directs the development of tumor cells adapted to survive in an acidic surrounding where normal cells perish. The provision of unique pH characteristics in tumor cells provides a defining trait that has led to the pursuit of treatments that target metabolism, hypoxia, and pH-related mechanisms to selectively kill cancer cells. Numerous studies over the past decade involving the cancer-specific carbonic anhydrase IX have re-kindled an interest in pH disruption-based therapies. Although an acidification of the intracellular compartment is established as a means to induce normal cell death, the defining role of acid-base disturbances in tumor physiology and survival remains unclear. The aim of this review is to summarize recent data relating to the specific role of pH regulation in tumor cell survival. We focus on membrane transport and enzyme studies in an attempt to elucidate their respective functions regarding tumor cell pH regulation. These data are discussed in the context of future directions for the field of tumor cell acid-base-related research.

miR-210 is overexpressed in late stages of lung cancer and mediates mitochondrial alterations associated with modulation of HIF-1 activity

Following the identification of a set of hypoxia-regulated microRNAs (miRNAs), recent studies have highlighted the importance of miR-210 and of its transcriptional regulation by the transcription factor hypoxia-inducible factor-1 (HIF-1). We report here that miR-210 is overexpressed at late stages of non-small cell lung cancer. Expression of miR-210 in lung adenocarcinoma A549 cells caused an alteration of cell viability associated with induction of caspase-3/7 activity. miR-210 induced a loss of mitochondrial membrane potential and the apparition of an aberrant mitochondrial phenotype. The expression profiling of cells overexpressing miR-210 revealed a specific signature characterized by enrichment for transcripts related to 'cell death' and 'mitochondrial dysfunction', including several subunits of the electron transport chain (ETC) complexes I and II. The transcript coding for one of these ETC components, SDHD, subunit D of succinate dehydrogenase complex (SDH), was validated as a bona fide miR-210 target. Moreover, SDHD knockdown mimicked miR-210-mediated mitochondrial alterations. Finally, miR-210-dependent targeting of SDHD was able to activate HIF-1, in line with previous studies linking loss-of-function SDH mutations to HIF-1 activation. miR-210 can thus regulate mitochondrial function by targeting key ETC component genes with important consequences on cell metabolism, survival and modulation of HIF-1 activity. These observations help explain contradictory data regarding miR-210 expression and its putative function in solid tumors.

Usefulness of tissue microarrays for assessment of protein expression, gene copy number and mutational status of EGFR in lung adenocarcinoma

Specific inhibitors targeting the epidermal growth factor receptor (EGFR) can increase survival rates in certain lung adenocarcinoma patients with mutations in the EGFR gene. Although such EGFR-targeted therapies have been approved for use, there is no general consensus among surgical pathologists on how the EGFR status should be tested in lung adenocarcinoma tissues and whether the results of immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and mutational analysis by molecular methods correlate. We evaluated the EGFR status in 61 lung adenocarcinomas by IHC (using total and mutant-specific antibodies against EGFR), by FISH analysis on tissue microarrays (TMAs), and by direct sequencing. The results of each method were compared using χ² and κappa statistics. The sensitivity and negative predictive value estimating the presence of abnormal EGFR for each test was calculated. The results show that, with respect to expression patterns and clinicopathological parameters, the total and mutant-specific EGFR detected by immunohistochemistry and FISH analysis on TMAs are valid and are equivalent to conventional methods performed on whole-tissue sections. Abnormal EGFR was detected in 52.4% of patients by IHC, FISH, and sequencing. The best sensitivity (100%) and negative predictive value (100%) was determined by evaluating the EGFR status with all methods. Testing for molecular changes in EGFR using a single test is likely to underestimate the presence of EGFR abnormalities. Taken together, these results demonstrate the high potential of TMAs to test for the major mechanisms of EGFR activation in patients with lung adenocarcinoma.