Carbonic anhydrase IX as a predictive biomarker of response to kidney cancer therapy

Correlation of carbonic anhydrase 9 (CA9) with pathological T-stage and prognosis in patients with oral tongue squamous cell carcinoma

Background

We explored the mechanisms underlying tumorigenesis in oral tongue squamous cell carcinoma (OTSCC) with the goal of uncovering prognostic molecular biomarkers.

Methods

An mRNA sequencing dataset was obtained from The Cancer Genome Atlas (TCGA) database, and differentially expressed genes (DEGs) were selected using R language software packages. Functional enrichment analysis was conducted with DAVID software and protein-protein interaction (PPI) networks were constructed using the STRING database. The relationship between hub genes and overall survival (OS) was evaluated by Kaplan-Meier analysis and Cox proportional hazard regression models. Expression of the candidate gene, carbonic anhydrase 9 (CA9), was verified by real-time RT-PCR, western blotting, and immunohistochemistry.

Results

DEGs (n=581) were obtained from 11 OTSCC samples and corresponding adjacent non-tumor tissues. Gene ontology (GO) analysis revealed that most DEGs were implicated in anterior/posterior pattern specification, embryonic skeletal system morphogenesis, and multicellular organism development, and pathway analysis suggested that DEGs were associated with neuroactive ligand-receptor interaction, calcium signaling pathway and transcriptional misregulation in the cancer. A PPI network consisting of 301 nodes and 2011 edges was constructed and 71 hub genes, with high degrees of connectivity in the network, were identified. Kaplan-Meier analysis of the hub genes indicated that high expression of CA9, LHX1, and KISS1R and low expression of CCKAR were associated with poor OS in OTSCC; however, only CA9 was a significant prognostic factor influencing survival in OTSCC on multivariate analysis. High expression of CA9 was associated with poor pathological T-stage. CA9 tumor specificity was confirmed using the Gene Expression Omnibus (GEO) database and further molecular tests.

Conclusions

We identified key DEGs that may assist in the molecular understanding of OTSCC. CA9 warrants further exploration as potential prognostic biomarker and therapeutic target in OTSCC.

Update on advances in molecular PET in urological oncology

Integrated positron emission tomography/computed tomography (PET/CT) with 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) has emerged as a powerful tool for the combined metabolic and anatomic evaluation of many cancers. In urological oncology, however, the use of (18)F-FDG has been limited by a generally low tumor uptake, and physiological excretion of FDG through the urinary system. (18)F-FDG PET/CT is useful when applied to specific indications in selected patients with urological malignancy. New radiotracers and positron emission tomography/magnetic resonance imaging (PET/MRI) are expected to further improve the performance of PET in uro-oncology.

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

Background

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

Methods

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

Results

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

Conclusions

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

Positron emission tomography in renal cell carcinoma: an imaging biomarker in development

Positron emission tomography (PET) has revolutionized cancer imaging. The current workhorse of molecular imaging, fluorodeoxyglucose (FDG) PET is used in the majority of malignant tumors with a few exceptions. Renal cell carcinoma (RCC) is one of those exceptions because of its variable uptake of FDG, although this variable uptake may actually be an asset in predicting response to some targeted agents, as will be discussed later. Beyond FDG, there is only scattered information in the literature on the use of PET in RCC. The purpose of this review is to summarize the current status of PET usage in RCC and point out its potentials and future directions. We will start with a brief overview of the demographics, molecular pathogenesis, and evolving treatment strategies in RCC because this information is essential for better understanding of uptake of various PET radiotracers in this cancer and their indications. This will be followed by discussing the role of PET in characterization of indeterminate renal masses, in staging and restaging of RCC, and, finally, in predicting and monitoring therapy response. Each of these 3 areas of PET usage will include the relevant radiotracers currently in use or in development.

Predictive factors for response to treatment in patients with advanced renal cell carcinoma

INTRODUCTION

The analysis of predictive factors of response may aid in predicting which patients with advanced renal cell carcinoma (RCC) would be good candidates for systemic treatments.

MATERIALS AND METHODS

The expression of several biomarkers was retrospectively analyzed using immunohistochemistry (IHC), as well as 2 analytical variables in 135 patients with advanced RCC treated with cytokines (CK) and/or new targeted drugs (NTD).

RESULTS

67 patients were treated solely with NTD and 68 with CK (23 also received NTD). Univariate analysis: HIF1α did not correlate significantly with response to these drugs. Overexpression of CAIX was associated with more responses (%) to NTD (64.7 vs. 21.1; p = 0.004) and CK (22.6 vs. 0; p = 0.038). PTEN demonstrated predictive value of response to sunitinib (70.8 vs. 34.1; p = 0.005). p21 was associated with a lower response to sunitinib (35.9 vs. 65.4; p = 0.025). Thrombocytosis was not significantly associated with response to NTD, although it was with CK (0 vs. 20; p = 0.017). Neutrophilia correlated with a lower response to NTD (29.6 vs. 57.5; p = 0.045), although not with CK. Multivariate analysis: Overexpression of CAIX was an independent predictor of significantly higher response to NTD and CK; OR = 8.773 (p < 0.001).

CONCLUSIONS

Our findings highlight the usefulness of CAIX in selecting patients with advanced RCC as candidates for systemic treatment. PTEN and p21 may be important in predicting response to sunitinib. Thrombocytosis and neutrophilia correlate well with response to CK and NTD, respectively.

Renal cell carcinoma primary cultures maintain genomic and phenotypic profile of parental tumor tissues

Background

Clear cell renal cell carcinoma (ccRCC) is characterized by recurrent copy number alterations (CNAs) and loss of heterozygosity (LOH), which may have potential diagnostic and prognostic applications. Here, we explored whether ccRCC primary cultures, established from surgical tumor specimens, maintain the DNA profile of parental tumor tissues allowing a more confident CNAs and LOH discrimination with respect to the original tissues.

Methods

We established a collection of 9 phenotypically well-characterized ccRCC primary cell cultures. Using the Affymetrix SNP array technology, we performed the genome-wide copy number (CN) profiling of both cultures and corresponding tumor tissues. Global concordance for each culture/tissue pair was assayed evaluating the correlations between whole-genome CN profiles and SNP allelic calls. CN analysis was performed using the two CNAG v3.0 and Partek software, and comparing results returned by two different algorithms (Hidden Markov Model and Genomic Segmentation).

Results

A very good overlap between the CNAs of each culture and corresponding tissue was observed. The finding, reinforced by high whole-genome CN correlations and SNP call concordances, provided evidence that each culture was derived from its corresponding tissue and maintained the genomic alterations of parental tumor. In addition, primary culture DNA profile remained stable for at least 3 weeks, till to third passage. These cultures showed a greater cell homogeneity and enrichment in tumor component than original tissues, thus enabling a better discrimination of CNAs and LOH. Especially for hemizygous deletions, primary cultures presented more evident CN losses, typically accompanied by LOH; differently, in original tissues the intensity of these deletions was weaken by normal cell contamination and LOH calls were missed.

Conclusions

ccRCC primary cultures are a reliable in vitro model, well-reproducing original tumor genetics and phenotype, potentially useful for future functional approaches aimed to study genes or pathways involved in ccRCC etiopathogenesis and to identify novel clinical markers or therapeutic targets. Moreover, SNP array technology proved to be a powerful tool to better define the cell composition and homogeneity of RCC primary cultures.

Carbonic anhydrase 9 in clear cell renal cell carcinoma: a marker for diagnosis, prognosis and treatment

Carbonic anhydrase 9 (CA9) is a transmembrane member of the carbonic anhydrase family. It catalyses the reversible hydration of carbon dioxide into bicarbonate and a proton, thus enabling tumour cells to maintain a neutral pH despite an acidic microenvironment. CA9 is not expressed in healthy renal tissue but is expressed in most clear cell renal cell carcinomas (CCRCC) through HIF-1α accumulation driven by hypoxia and inactivation of the VHL gene. CA9 expression can be detected in the tumour by immunohistochemistry (IHC), in blood and tissue by ELISA assay and RT-PCR. It has a 100% diagnostic specificity in solid renal tumours, while ELISA assays on aspiration fluids may help in atypical cysts. Blood-based assays, ELISA for CA9 antigen and RT-PCR for CA9 mRNA are promising for the prognosis and follow-up of localised CCRCC. In metastatic disease, high CA9 expression by IHC was reported to be a powerful prognostic marker with better survival and sensitivity to IL-2, but this is still debated. Almost no data are currently available on the association of CA9 expression and outcome to targeted drugs. The prognostic value of CA9 in CCRCC could be explained by the frequent VHL gene inactivation driving an early activation of the HIF pathway. The poorer prognosis associated with low CA9 expressing tumours could be due to the simultaneous overexpression of EGFR contributing to the activation of AkT and mTOR pathways. Targeting CA9 by inhibitors, radioimmunotherapy, monoclonal antibodies or vaccination is promising and offers new avenues for clinical research.

Circulating biomarkers for vascular endothelial growth factor inhibitors in renal cell carcinoma

In recent years, there has been significant progress in the clinical development and application of antiangiogenic therapies in renal cell carcinomas, particularly inhibitors of the vascular endothelial growth factor (VEGF) pathway. Despite this progress, no validated methods are currently available for identifying which patients are most likely to respond to treatment or experience toxic effects, selecting the optimal dose, or determining whether the intended molecular target has been effectively inhibited. However, recent studies have suggested that some of the biomarkers currently under investigation in clear cell renal cell carcinoma for VEGF pathway inhibitors are promising. These biomarkers include circulating proangiogenic factors and receptors; markers of hypoxia and endothelial damage; and cellular populations in peripheral blood, such as circulating endothelial cells. Further preclinical and translational validation studies are still needed to determine their practical utility in the clinical setting.