Clinical and Pre-Clinical Evidence of Carbonic Anhydrase IX in Pancreatic Cancer and Its High Expression in Pre-Cancerous Lesions
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cancers Review Clinical and Pre-Clinical Evidence of Carbonic Anhydrase IX in Pancreatic Cancer and Its High Expression in Pre-Cancerous Lesions Sabina Strapcova 1, Martina Takacova 1, Lucia Csaderova 1, Paola Martinelli 2,3, Lubomira Lukacikova 1, Viliam Gal 4, Juraj Kopacek 1 and Eliska Svastova 1,* 1 Department of Tumor Biology, Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; [email protected] (S.S.); [email protected] (M.T.); [email protected] (L.C.); [email protected] (L.L.); [email protected] (J.K.) 2 Institute of Cancer Research, Clinic of Internal Medicine I, Medical University of Vienna, 1090 Vienna, Austria; [email protected] 3 Cancer Cell Signaling, Boehringer-Ingelheim RCV Vienna, A-1121 Vienna, Austria 4 Alpha Medical Pathology, Ruzinovska 6, 82606 Bratislava, Slovakia; [email protected] * Correspondence: [email protected] Received: 22 June 2020; Accepted: 16 July 2020; Published: 22 July 2020 Abstract: Hypoxia is a common phenomenon that occurs in most solid tumors. Regardless of tumor origin, the evolution of a hypoxia-adapted phenotype is critical for invasive cancer development. Pancreatic ductal adenocarcinoma is also characterized by hypoxia, desmoplasia, and the presence of necrosis, predicting poor outcome. Carbonic anhydrase IX (CAIX) is one of the most strict hypoxia regulated genes which plays a key role in the adaptation of cancer cells to hypoxia and acidosis. Here, we summarize clinical data showing that CAIX expression is associated with tumor necrosis, vascularization, expression of Frizzled-1, mucins, or proteins involved in glycolysis, and inevitably, poor prognosis of pancreatic cancer patients. We also describe the transcriptional regulation of CAIX in relation to signaling pathways activated in pancreatic cancers. A large part deals with the preclinical evidence supporting the relevance of CAIX in processes leading to the aggressive behavior of pancreatic tumors. Furthermore, we focus on CAIX occurrence in pre-cancerous lesions, and for the first time, we describe CAIX expression within intraductal papillary mucinous neoplasia. Our review concludes with a detailed account of clinical trials implicating that treatment consisting of conventionally used therapies combined with CAIX targeting could result in an improved anti-cancer response in pancreatic cancer patients. Keywords: carbonic anhydrase IX; pancreatic cancer; intraductal papillary mucinous neoplasia; acidic microenvironment; hypoxia; correlation analysis; immunohistochemistry 1. Introduction To date, several members of the carbonic anhydrase (CA) family namely CAI, CAII, CAIV, CAVB, CAVI, CAIX, and CAXII, have been identified in the human pancreas. Within the organ, CAs localize in alpha cells of Langerhans’s islets (cytosolic CAI [1]), beta cells of the pancreas (mitochondrial CAV [2]), acinar cells (secreted CAVI [3], transmembrane CAXII [4]), and pancreatic ducts (cytosolic CAII [1,5], transmembrane CAIX [6,7], transmembrane CAXII [4]). CAXIV has no expression in healthy pancreas, but it has been found in pancreatic tumors [8] (Figure1). As with most carbonic anhydrases, CAIX catalyzes a simple physiological reaction, the reversible hydration of carbon dioxide to bicarbonate ions and protons. Hence, this exofacial CA located at the Cancers 2020, 12, 2005; doi:10.3390/cancers12082005 www.mdpi.com/journal/cancers Cancers 2020, 12, 2005 2 of 39 Cancers 2020, 12, x 2 of 39 cell membrane is a crucial component of the pH-regulating machinery in tumors [9–11]. To prevent the build-up of acidic metabolites inside cancer cells and to maintain a permissive intracellular pH for prevent the build-up of acidic metabolites inside cancer cells and to maintain a permissive intracellular cell proliferation and survival, CAIX closely cooperates with the bicarbonate transporters NBCe1 and pH for cell proliferation and survival, CAIX closely cooperates with the bicarbonate transporters NBCe1 NBCn1, catalyzing HCO3 influx [12,13]. This functional interaction increases the efficiency of ion and NBCn1, catalyzing HCO− 3− influx [12,13]. This functional interaction increases the efficiency of ion transport through a plasma membrane, generation of pH gradient, and neutralization of intracellular transport through a plasma membrane, generation of pH gradient, and neutralization of intracellular space. Together with CAIX, monocarboxylate transporters (MCTs) are also thought to participate in space. Together with CAIX, monocarboxylate transporters (MCTs) are also thought to participate in the the process of extracellular acidification by exporting lactate and ions [14]. process of extracellular acidification by exporting lactate and ions [14]. Figure 1.1. TheThe expression expression profile profile of selectedof selected carbonic carbonic anhydrase anhydrase isoforms isoforms and sonic and hedgehog sonic hedgehog (activated (activatedin pancreatic in cancer)pancreatic in 179 cancer) samples in of179 pancreatic samples adenocarcinomaof pancreatic adenocarcinoma and 171 normal and pancreatic 171 normal tissue pancreaticsamples extracted tissue samples from Xena extracted (using from the Xena cancer (using genome the cancer atlas (TCGA) genome targetatlas (TCGA) GTEx datasets) target GTEx [15] (fordatasets) more [15]. information Expression see Supplementaryof CA9 increases Material). in pancreatic Expression ductal adenocarcinoma of CA9 increases samples in pancreatic along ductal with Sonicadenocarcinoma Hedgehog samples(SHH) level. along Analysis with Sonic of CA9 Hedgehog promoter (SHH) revealed level. Analysispossible ofregulation CA9 promoter through revealed Sonic possibleHedgehog regulation (SHH) pathway through (see Sonic Figure. Hedgehog 2). According (SHH) pathway to the carbonic (see Figure anhydrase 2). According nomenclature, to the carbonic human anhydrase nomenclature, human CA isoenzymes are written in capital Roman letters and numerals, CA isoenzymes are written in capital Roman letters and numerals, while their genes are written in while their genes are written in Italic letters and Arabic numerals. Italic letters and Arabic numerals. The reversed intracellular (pHi) and extracellular pH (pHe) gradient generated by the The reversed intracellular (pHi) and extracellular pH (pHe) gradient generated by the cooperation of CAIX with other proteins enhances cell migration, during which CAIX relocalizes to cooperation of CAIX with other proteins enhances cell migration, during which CAIX relocalizes to lammelipodia [12]. Invadopodial distribution of CAIX promoting the proteolytic activity of matrix lammelipodia [12]. Invadopodial distribution of CAIX promoting the proteolytic activity of matrix metalloproteasis within invasion through the extracellular matrix and quail chorioallantoic membranes, metalloproteasis within invasion through the extracellular matrix and quail chorioallantoic as well as the ability of anti-CAIX antibodies to cease this process, was shown by Debreova et al. membranes, as well as the ability of anti-CAIX antibodies to cease this process, was shown by (2019) [16] (the role in invadopodia was also described in [17]). Furthermore, CAIX de-stabilizes cell-cell Debreova et al. (2019) [16] (the role in invadopodia was also described in [17]). Furthermore, CAIX adhesion through competitive binding with β-catenin, disabling the formation of a complex between de-stabilizes cell-cell adhesion through competitive binding with β-catenin, disabling the formation β-catenin and E-cadherin necessary for adherent junction maintenance. The disruption of this complex of a complex between β-catenin and E-cadherin necessary for adherent junction maintenance. The facilitates tumor cell dissemination and further cancer progression [16,18]. Interestingly, CAIX is also disruption of this complex facilitates tumor cell dissemination and further cancer progression [16,18]. Interestingly, CAIX is also cleaved from the cell membrane by a disintegrin and metalloproteinase 17 (ADAM17). Its ectodomain serves as a potential blood biomarker of some cancer types with developed hypoxia [19,20]. Cancers 2020, 12, 2005 3 of 39 cleaved from the cell membrane by a disintegrin and metalloproteinase 17 (ADAM17). Its ectodomain serves as a potential blood biomarker of some cancer types with developed hypoxia [19,20]. Considering its unique transcriptional regulation and expression, enzymatic activity, as well as appertaining functions [21], CAIX possesses a special position among all human CAs and is a crucial player implicated in cancer pathogenesis due to its catalytic and non-catalytic mechanisms. While enzymatic activity is mediated by the protein’s catalytic CA domain oriented towards the extracellular space, the unique presence of a proteoglycan-like (PG) domain enables non-catalytic functions characteristic of CAIX. The PG domain is negatively charged and easily dissociates from complexes at a slightly acidic pH [22], facilitating the detachment of primary tumor cells, and eventually leading to the formation of metastases. Through its PG domain, CAIX facilitates adhesion to collagen. During initial adhesion and spreading, it colocalizes with paxillin in focal contacts [23]. Moreover, the PG domain displays the capability to bind mucins, abundantly overexpressed in pancreatic tumors. The expression pattern of CAIX clearly differs from the rest of its CA family members: CAIX can be found in only a few normal tissues, but