Carbonic anhydrases II, IX, and XII in Barrett’s esophagus and adenocarcinoma

Elevation of fatty acid desaturase 2 in esophageal adenocarcinoma increases polyunsaturated lipids and may exacerbate bile acid-induced DNA damage

Background

The risk of esophageal adenocarcinoma (EAC) is associated with gastro‐esophageal reflux disease (GERD) and obesity. Lipid metabolism‐targeted therapies decrease the risk of progressing from Barrett's esophagus (BE) to EAC, but the precise lipid metabolic changes and their roles in genotoxicity during EAC development are yet to be established.

Methods

Esophageal biopsies from the normal epithelium (NE), BE, and EAC, were analyzed using concurrent lipidomics and proteomics (n = 30) followed by orthogonal validation on independent samples using RNAseq transcriptomics (n = 22) and immunohistochemistry (IHC, n = 80). The EAC cell line FLO‐1 was treated with FADS2 selective inhibitor SC26196, and/or bile acid cocktail, followed by immunofluorescence staining for γH2AX.

Results

Metabolism‐focused Reactome analysis of the proteomics data revealed enrichment of fatty acid metabolism, ketone body metabolism, and biosynthesis of specialized pro‐resolving mediators in EAC pathogenesis. Lipidomics revealed progressive alterations (NE‐BE‐EAC) in glycerophospholipid synthesis with decreasing triglycerides and increasing phosphatidylcholine and phosphatidylethanolamine, and sphingolipid synthesis with decreasing dihydroceramide and increasing ceramides. Furthermore, a progressive increase in lipids with C20 fatty acids and polyunsaturated lipids with ≥4 double bonds were also observed. Integration with transcriptome data identified candidate enzymes for IHC validation: Δ4‐Desaturase, Sphingolipid 1 (DEGS1) which desaturates dihydroceramide to ceramide, and Δ5 and Δ6‐Desaturases (fatty acid desaturases, FADS1 and FADS2), responsible for polyunsaturation. All three enzymes showed significant increases from BE through dysplasia to EAC, but transcript levels of DEGS1 were decreased suggesting post‐translational regulation. Finally, the FADS2 selective inhibitor SC26196 significantly reduced polyunsaturated lipids with three and four double bonds and reduced bile acid‐induced DNA double‐strand breaks in FLO‐1 cells in vitro.

Conclusions

Integrated multiomics revealed sphingolipid and phospholipid metabolism rewiring during EAC development. FADS2 inhibition and reduction of the high polyunsaturated lipids effectively protected EAC cells from bile acid‐induced DNA damage in vitro, potentially through reduced lipid peroxidation.

Carbonic Anhydrases in Metazoan Model Organisms: Molecules, Mechanisms, and Physiology

During the past three decades, mice, zebrafish, fruit flies, and Caenorhabditis elegans have been the primary model organisms used for the study of various biological phenomena. These models have also been adopted and developed to investigate the physiological roles of carbonic anhydrases (CAs) and carbonic anhydrase-related proteins (CARPs). These proteins belong to eight CA families and are identified by Greek letters: α, β, γ, δ, ζ, η, θ, and ι. Studies using model organisms have focused on two CA families, α-CAs and β-CAs, which are expressed in both prokaryotic and eukaryotic organisms with species-specific distribution patterns and unique functions. This review covers the biological roles of CAs and CARPs in light of investigations performed in model organisms. Functional studies demonstrate that CAs are not only linked to the regulation of pH homeostasis, the classical role of CAs but also contribute to a plethora of previously undescribed functions.

Carbonic Anhydrases II, IX, and XII in Reflux Esophagitis

BACKGROUND

The pathogenesis of gastroesophageal reflux disease (GERD) has not been resolved in detail. Esophageal epithelial cells provide resistance to acidic reflux via several mechanisms, many of which involve buffering acid with bicarbonate and transporting protons. Carbonic anhydrases (CAs) are enzymes that control the acid-base balance by catalyzing the reversible hydration of carbon dioxide to produce bicarbonate and hydrogen ions.

AIMS

We aimed to determine the immunohistochemical expression patterns of CAII, CAIX, and CAXII in the normal esophageal squamous epithelium and in patients with GERD.

METHODS

We evaluated 82 biopsy samples, including 26 with a histologically normal esophagus, 26 with histologically mild esophagitis, and 30 with severe esophagitis. Expression patterns of CAII, CAIX, and CAXII in the esophageal squamous epithelium were determined by immunohistochemical staining.

RESULTS

Cytoplasmic CAII expression was predominantly detected in the upper luminal part of the squamous epithelium and was significantly (p < 0.01) increased in GERD. Expression of CAIX was essentially membranous. The isozyme was constantly present in the peripapillary cells. In the interpapillary areas, clustered expression was observed to emerge and increase significantly (p < 0.01) in esophagitis. CAXII expression was the most abundant of the isozymes and was mainly membranous. In the normal squamous epithelium, CAXII expression was confined to the basal layer; in severe esophagitis, CAXII expression increased significantly in both basal (p < 0.05) and superficial (p < 0.01) halves of the epithelium.

CONCLUSIONS

We demonstrate upregulated expression of CAII, CAIX, and CAXII in GERD. The increase in expression likely contributes to esophageal epithelial resistance to acidic reflux.

Inhibition of Carbonic Anhydrase 2 Overcomes Temozolomide Resistance in Glioblastoma Cells

About 95% of Glioblastoma (GBM) patients experience tumor relapse as a consequence of resistance to the first-line standard chemotherapy using temozolomide (TMZ). Recent studies reported consistently elevated expression levels of carbonic anhydrase CA2 in recurrent glioblastoma and temozolomide-resistant glioblastoma stem-like cells (GSCs). Here we show that CA2 is preferentially expressed in GSCs and upregulated by TMZ treatment. When expressed in GBM cell lines, CA2 exerts significant metabolic changes reflected by enhanced oxygen consumption and increased extracellular acidification causing higher rates of cell invasion. Notably, GBM cells expressing CA2 respond to combined treatment with TMZ and brinzolamide (BRZ), a non-toxic and potent CA2 inhibitor. Interestingly, brinzolamide was more effective than the pan-CA inhibitor Acetazolamide (ACZ) to sensitize naïve GSCs and TMZ-resistant GSCs to TMZ induced cell death. Mechanistically, we demonstrated that the combined treatment of GBM stem cells with TMZ and BRZ caused autophagy of GBM cell lines and GSCs, reflected by enhanced LC3 cleavage (LC3-II) and p62 reduction. Our findings illustrate the potential of CA2 as a chemo-sensitizing drug target in recurrent GBM and propose a combined treatment of TMZ with CA2 inhibitor to tackle GBM chemoresistance and recurrence.

Carbonic Anhydrases II and IX in Non-ampullary Duodenal Adenomas and Adenocarcinoma

Non-ampullary duodenal adenocarcinoma (DAC) is a rare malignancy. Little information is available concerning the histopathological prognostic factors associated with DAC. Carbonic anhydrases (CAs) are metalloenzymes catalyzing the universal reaction of CO₂ hydration. Isozymes CAII, CAIX, and CAXII are associated with prognosis in various cancers. Our aim was to analyze the immunohistochemical expressions of CAII, CAIX, and CAXII in normal duodenal epithelium, duodenal adenomas, and adenocarcinoma and their associations with clinicopathological variables and survival. Our retrospective study included all 27 DACs treated in Oulu University Hospital during years 2000-2020. For comparison, samples of 42 non-ampullary adenomas were collected. CAII expression was low in duodenal adenomas and adenocarcinoma. CAIX expression in adenomas and adenocarcinoma was comparable with the high expression of normal duodenal crypts. Expression patterns in carcinomas were largely not related to clinicopathological features. However, low expression of CAII associated with poorer differentiation of the tumor (p=0.049) and low expression of CAIX showed a trend for association with nodal spread, although statistical significance was not reached (p=0.091). CAII and CAIX lost their epithelial polarization and staining intensity in adenomas. CAXII expression was not detected in the studied samples. CAs were not associated with survival. The prognostic value of CAII and CAIX downregulation should be further investigated. Both isozymes may serve as biomarkers of epithelial dysplasia in the duodenum.

Expression of CA2 and CA9 carbonic anhydrases in ulcerative colitis and ulcerative colitis-associated colorectal cancer

Ulcerative colitis (UC) is characterized by chronic inflammation in the colonic mucosa and submucosa with repeating relapse and remission, but the pathogenesis is unknown. Patients with long-standing UC are at high risk of neoplasm development. The aim of the present study was to identify molecules whose expression is associated with UC and UC-associated colorectal cancer (UCCA). Biopsy specimens from UC and normal colonic mucosae were analyzed using a proteomics approach, in which carbonic anhydrase 2 (CA2) was identified as a molecule downregulated in UC mucosae. Immunohistochemically, CA2 expression was detected in normal and diverticulitis mucosal epithelia, and its expression decreased as UC activity increased. CA2 expression was almost undetectable in UCCA. We also analyzed the expression of another carbonic anhydrase, CA9, and its upstream molecule, hypoxia-inducible factor-1α (HIF-1α), both of which are induced under hypoxic conditions. It was revealed that CA9 expression was relatively low in normal, diverticulitis and UC mucosae, and was upregulated in UCCA. HIF-1α expression was consistently low in all tissue types examined. In conclusion, these results suggest that CA2 and CA9 may be possible indicators of UC activity and UCCA development, respectively.

Identification of novel biomarkers affecting the metastasis of colorectal cancer through bioinformatics analysis and validation through qRT-PCR

Background

Tumor progression and distant metastasis are the main causes of deaths in colorectal cancer (CRC) patients, and the molecular mechanisms in CRC metastasis have not been completely discovered.

Methods

We identified differentially expressed genes (DEGs) and lncRNAs (DELs) of CRC from The Cancer Genome Atlas (TCGA) database. Then we conducted the weighted gene co-expression network analysis (WGCNA) to investigate co-expression modules related with CRC metastasis. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, DEG-DEL co-expression network and survival analyses of significant modules were also conducted. Finally, the expressions of selected biomarkers were validated in cell lines by quantitative real-time PCR (qRT-PCR).

Results

2032 DEGs and 487 DELs were involved the construction of WGCNA network, and greenyellow, turquoise and brown module were identified to have more significant correlation with CRC metastasis. GO and KEGG pathway analysis of these three modules have proven that the functions of DEGs were closely involved in many important processes in cancer pathogenesis. Through the DEG-DEL co-expression network, 12 DEGs and 2 DELs were considered as hub nodes. Besides, survival analysis showed that 30 DEGs were associated with the overall survival of CRC. Then 10 candidate biomarkers were chosen for validation and the expression of CA2, CHP2, SULT1B1, MOGAT2 and C1orf115 were significantly decreased in CRC cell lines when compared to normal human colonic epithelial cells, which were consistent with the results of differential expression analysis. Especially, low expression of SULT1B1, MOGAT2 and C1orf115 were closely correlated with poorer survival of CRC.

Conclusion

This study identified 5 genes as new biomarkers affecting the metastasis of CRC. Besides, SULT1B1, MOGAT2 and C1orf115 might be implicated in the prognosis of CRC patients.

SSTR5‑AS1 functions as a ceRNA to regulate CA2 by sponging miR‑15b‑5p for the development and prognosis of HBV‑related hepatocellular carcinoma

Long non-coding RNAs (lncRNAs) have been implicated in the development and progression of cancer. However, the mechanisms of lncRNAs in hepatitis B virus (HBV) infection-induced hepatocellular carcinoma (HCC) remain unclear. The study aimed to reveal the roles of lncRNAs for HBV-HCC based on the hypothesis of competing endogenous RNA (ceRNA). The lncRNA (GSE27462), miRNA (GSE76903) and mRNA (GSE121248) expression profiles were collected from the Gene Expression Omnibus database. Differentially expressed lncRNAs (DELs), genes (DEGs) and miRNAs (DEMs) were identified using the LIMMA or EdgeR package, respectively. The ceRNA network was constructed based on interaction pairs between miRNAs and mRNAs/lncRNAs. The functions of DEGs in the ceRNA network were predicted using the DAVID database, which was overlapped with the known HCC pathways of Comparative Toxicogenomics Database (CTD) to construct the HCC-related ceRNA network. The prognosis values [overall survival, (OS); recurrence-free survival (RFS)] of genes were validated using the Cancer Genome Atlas (TCGA) data with Cox regression analysis. The present study screened 38 DELs, 127 DEMs and 721 DEGs. A ceRNA network was constructed among 17 DELs, 12 DEMs and 173 DEGs, including the FAM138B-hsa-miR-30c-CCNE2/RRM2 and SSTR5-AS1-hsa-miR-15b-5p-CA2 ceRNA axes. Function enrichment analysis revealed the genes in the ceRNA network that participated in the p53 signaling pathway [cyclin E2 (CCNE2), ribonucleotide reductase M2 subunit (RRM2)] and nitrogen metabolism [carbonic anhydrase 2 (CA2)], which were also included in the pathways of the CTD. Univariate Cox regression analysis revealed that six RNAs (2 DELs: FAM138B, SSTR5-AS1; 2 DEMs: hsa-miR-149, hsa-miR-7; 2 DEGs: CCNE2, RRM2) were significantly associated with OS; while seven RNAs (1 DEL: LINC00284; 3 DEMs: hsa-miR-7, hsa-miR-15b, hsa-miR-30c-2; and 3 DEGs: RRM2, CCNE2, CA2) were significantly associated with RFS. In conclusion, FAM138B-hsa-miR-30c-CCNE2/RRM2 and the SSTR5-AS1-hsa-miR-15b-5p-CA2 ceRNA axes may be important mechanisms for HBV-related HCC.

Comparative Transcriptomic Analysis of Temozolomide Resistant Primary GBM Stem-Like Cells and Recurrent GBM Identifies Up-Regulation of the Carbonic Anhydrase CA2 Gene as Resistance Factor

About 95% of patients with Glioblastoma (GBM) show tumor relapse, leaving them with limited therapeutic options as recurrent tumors are most often resistant to the first line chemotherapy standard Temozolomide (TMZ). To identify molecular pathways involved in TMZ resistance, primary GBM Stem-like Cells (GSCs) were isolated, characterized, and selected for TMZ resistance in vitro. Subsequently, RNA sequencing analysis was performed and revealed a total of 49 differentially expressed genes (|log2-fold change| > 0.5 and adjusted p-value < 0.1) in TMZ resistant stem-like cells compared to their matched DMSO control cells. Among up-regulated genes, we identified carbonic anhydrase 2 (CA2) as a candidate gene correlated with glioma malignancy and patient survival. Notably, we describe consistent up-regulation of CA2 not only in TMZ resistant GSCs on mRNA and protein level, but also in patient-matched clinical samples of first manifest and recurrent tumors. Co-treatment with the carbonic anhydrase inhibitor Acetazolamid (ACZ) sensitized cells to TMZ induced cell death. Cumulatively, our findings illustrate the potential of CA2 as a chemosensitizing target in recurrent GBM and provide a rationale for a therapy associated inhibition of CA2 to overcome TMZ induced chemoresistance.