Dithiocarbamates strongly inhibit carbonic anhydrases and show antiglaucoma action in vivo.
ABSTRACT A series of dithiocarbamates were prepared by reaction of primary/secondary amines with carbon disulfide in the presence of bases. These compounds were tested for the inhibition of four human (h) isoforms of the zinc enzyme carbonic anhydrase, CA (EC 18.104.22.168), hCA I, II, IX, and XII, involved in pathologies such as glaucoma (CA II and XII) or cancer (CA IX). Several low nanomolar inhibitors targeting these CAs were detected. The X-ray crystal structure of the hCA II adduct with morpholine dithiocarbamate evidenced the inhibition mechanism of these compounds, which coordinate to the metal ion through a sulfur atom from the dithiocarbamate zinc-binding function. Some dithiocarbamates showed an effective intraocular pressure lowering activity in an animal model of glucoma.
Article: Imaging of CA IX with fluorescent labelled sulfonamides distinguishes hypoxic and (re)-oxygenated cells in a xenograft tumour model.[show abstract] [hide abstract]
ABSTRACT: Carbonic anhydrase (CA) IX is suggested to be an endogenous marker of hypoxia. Fluorescent sulfonamides with a high affinity for CA IX (CAI) have been developed and shown to bind to cells only when CA IX protein was expressed and while cells were hypoxic. The aim of this study was to investigate the in vivo CAI binding properties in a xenograft tumour model using fluorescent imaging. NMRI-nu mice subcutaneously transplanted with HT-29 colorectal tumours were treated with 7% oxygen or with nicotinamide and carbogen and were compared with control animals. CAI accumulation was monitored by non-invasive fluorescent imaging. Specific CAI accumulation could be observed in delineated tumour areas as compared with a non-sulfonamide analogue (P<0.01). Administration of nicotinamide and carbogen, decreasing acute and chronic hypoxia, respectively, prevented CAI accumulation (P<0.05). When treated with 7% oxygen breathing, a 3-fold higher CAI accumulation (P<0.01) was observed. Furthermore, the bound CAI fraction was rapidly reduced upon tumour reoxygenation (P<0.01). Our in vivo imaging results confirm previous in vitro data demonstrating that CAI binding and retention require exposure to hypoxia. Fluorescent labelled sulfonamides provide a powerful tool to visualize hypoxia response. An important step is made towards clinical applicability, indicating the potential of patient selection for CA IX-directed therapies.Radiotherapy and Oncology 08/2009; 92(3):423-8. · 5.58 Impact Factor
Article: Hypoxia activates the capacity of tumor-associated carbonic anhydrase IX to acidify extracellular pH.[show abstract] [hide abstract]
ABSTRACT: Acidic extracellular pH (pHe) is a typical attribute of a tumor microenvironment, which has an impact on cancer development and treatment outcome. It was believed to result from an accumulation of lactic acid excessively produced by glycolysis. However, metabolic profiles of glycolysis-impaired tumors have revealed that CO2 is a significant source of acidity, thereby indicating a contribution of carbonic anhydrase (CA). The tumor-associated CA IX isoform is the best candidate, because its extracellular enzyme domain is highly active, expression is induced by hypoxia and correlates with poor prognosis. This study provides the first evidence for the role of CA IX in the control of pHe. We show that CA IX can acidify the pH of the culture medium in hypoxia but not in normoxia. This acidification can be perturbed by deletion of the enzyme active site and inhibited by CA IX-selective sulfonamides, which bind only to hypoxic cells containing CA IX. Our findings suggest that hypoxia regulates both expression and activity of CA IX in order to enhance the extracellular acidification, which may have important implications for tumor progression.FEBS Letters 12/2004; 577(3):439-45. · 3.54 Impact Factor
Article: Prognostic significance of a novel hypoxia-regulated marker, carbonic anhydrase IX, in invasive breast carcinoma.[show abstract] [hide abstract]
ABSTRACT: To assess the frequency of expression and the prognostic significance of a hypoxia-regulated marker, carbonic anhydrase IX (CA IX), in a cohort of patients with invasive breast cancer. CA IX expression was evaluated by immunohistochemistry with a murine monoclonal antibody, M75, in a series of 103 women treated surgically for invasive breast cancer. The majority of patients were treated with adjuvant hormonal or chemotherapy. The frequency of CA IX expression, its association with recognized prognostic factors, and the relationship with outcome was evaluated by univariate and multivariate statistical analyses. CA IX expression was present in 49 (48%) of 103 cases. The level of CA IX expression was found to be significantly associated with tumor necrosis (P <.001), higher grade (P =.02), and negative estrogen receptor status (P <.001). Furthermore, CA IX expression was associated with a higher relapse rate (P =.004) and a worse overall survival (P =.001). By multivariate analysis, CA IX was also shown to be an independent predictive factor for overall survival (hazard ratio, 2.61; 95% confidence interval, 1.01 to 6.75, P =.05). CA IX expression was associated with worse relapse-free survival and overall survival in an unselected cohort of patients with invasive breast carcinoma. The potential role of CA IX as a marker of hypoxia within breast carcinomas was also indicated by a significant association with necrosis. Further work assessing its prognostic significance in breast cancer is warranted, particularly interactions with radiotherapy and chemotherapy resistance.Journal of Clinical Oncology 08/2001; 19(16):3660-8. · 18.37 Impact Factor