Increased expression of carbonic anhydrase IX in oral submucous fibrosis and oral squamous cell carcinoma

A Critical Interpretive Synthesis of the Role of Arecoline in Oral Carcinogenesis: Is the Local Cholinergic Axis a Missing Link in Disease Pathophysiology?

Arecoline is the primary active carcinogen found in areca nut and has been implicated in the pathogenesis of oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF). For this study, we conducted a stepwise review process by combining iterative scoping reviews with a post hoc search, with the aim of identifying the specific mechanisms by which arecoline initiates and promotes oral carcinogenesis. Our initial search allowed us to define the current trends and patterns in the pathophysiology of arecoline-induced OSF and OSCC, which include the induction of cell proliferation, facilitation of invasion, adhesion, and migration, increased collagen deposition and fibrosis, imbalance in immune and inflammatory mechanisms, and genotoxicity. Key molecular pathways comprise the activation of NOTCH1, MYC, PRDX2, WNT, CYR61, EGFR/Pl3K, DDR1 signaling, and cytokine upregulation. Despite providing a comprehensive overview of potential pathogenic mechanisms of OSF, the involvement of molecules functioning as areca alkaloid receptors, namely, the muscarinic and nicotinic acetylcholine receptors (AChRs), was not elucidated with this approach. Accordingly, our search strategy was refined to reflect these evidence gaps. The results of the second round of reviews with the post hoc search highlighted that arecoline binds preferentially to muscarinic AChRs, which have been implicated in cancer. Consistently, AChRs activate the signaling pathways that partially overlap with those described in the context of arecoline-induced carcinogenesis. In summary, we used a theory-driven interpretive review methodology to inform, extend, and supplement the conventional systematic literature assessment workflow. On the one hand, the results of this critical interpretive synthesis highlighted the prevailing trends and enabled the consolidation of data pertaining to the molecular mechanisms involved in arecoline-induced carcinogenesis, and, on the other, brought up knowledge gaps related to the role of the local cholinergic axis in oral carcinogenesis, thus suggesting areas for further investigation.

A pair of long intergenic non-coding RNA LINC00887 variants act antagonistically to control Carbonic Anhydrase IX transcription upon hypoxia in tongue squamous carcinoma progression

Background

Long noncoding RNAs (lncRNAs) are important regulators in tumor progression. However, their biological functions and underlying mechanisms in hypoxia adaptation remain largely unclear.

Results

Here, we established a correlation between a Chr3q29-derived lncRNA gene and tongue squamous carcinoma (TSCC) by genome-wide analyses. Using RACE, we determined that two novel variants of this lncRNA gene are generated in TSCC, namely LINC00887_TSCC_short (887S) and LINC00887_TSCC_long (887L). RNA-sequencing in 887S or 887L loss-of-function cells identified their common downstream target as Carbonic Anhydrase IX (CA9), a gene known to be upregulated by hypoxia during tumor progression. Mechanistically, our results showed that the hypoxia-augmented 887S and constitutively expressed 887L functioned in opposite directions on tumor progression through the common target CA9. Upon normoxia, 887S and 887L interacted. Upon hypoxia, the two variants were separated. Each RNA recognized and bound to their responsive DNA cis-acting elements on CA9 promoter: 887L activated CA9’s transcription through recruiting HIF1α, while 887S suppressed CA9 through DNMT1-mediated DNA methylation.

Conclusions

We provided hypoxia-permitted functions of two antagonistic lncRNA variants to fine control the hypoxia adaptation through CA9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01112-2.

Construction of Prognostic Risk Prediction Model of Oral Squamous Cell Carcinoma Based on Nine Survival-Associated Metabolic Genes

The aim was to investigate the independent prognostic factors and construct a prognostic risk prediction model to facilitate the formulation of oral squamous cell carcinoma (OSCC) clinical treatment plan. We constructed a prognostic model using univariate COX, Lasso, and multivariate COX regression analysis and conducted statistical analysis. In this study, 195 randomly obtained sample sets were defined as training set, while 390 samples constituted validation set for testing. A prognostic model was constructed using regression analysis based on nine survival-associated metabolic genes, among which PIP5K1B, NAGK, and HADHB significantly down-regulated, while MINPP1, PYGL, AGPAT4, ENTPD1, CA12, and CA9 significantly up-regulated. Statistical analysis used to evaluate the prognostic model showed a significant different between the high and low risk groups and a poor prognosis in the high risk group (P < 0.05) based on the training set. To further clarify, validation sets showed a significant difference between the high-risk group with a worse prognosis and the low-risk group (P < 0.05). Independent prognostic analysis based on the training set and validation set indicated that the risk score was superior as an independent prognostic factor compared to other clinical characteristics. We conducted Gene Set Enrichment Analysis (GSEA) among high-risk and low-risk patients to identify metabolism-related biological pathways. Finally, nomogram incorporating some clinical characteristics and risk score was constructed to predict 1-, 2-, and 3-year survival rates (C-index = 0.7). The proposed nine metabolic gene prognostic model may contribute to a more accurate and individualized prediction for the prognosis of newly diagnosed OSCC patients, and provide advice for clinical treatment and follow-up observations.

CA9 transcriptional expression determines prognosis and tumour grade in tongue squamous cell carcinoma patients

CA9 is a member of the carbonic anhydrases’ family, that is often expressed in cancer cells under hypoxic condition. However, the role of CA9 in the molecular mechanisms of tongue squamous cell carcinoma (TSCC) pathogenesis remains unclear. CA9 expression was analysed using the TCGA database, and its influence on survival was performed using Kaplan‐Meier, LASSO and COX regression analyses. The correlation between CA9 and immune infiltration was investigated by CIBERSORT and ESTIMATE. Moreover, the relationship between CA9 expression and downstream molecular regulation pathways was analysed by GSEA, GO and WGCNA. CA9 expression correlated with clinical prognosis and tumour grade in TSCC. Moreover, CA9 expression potentially contributes to the regulation of cancer cell differentiation and mediates tumour‐associated genes and signalling pathways, including apoptosis, hypoxia, G2M checkpoint, PI3K/AKR/mTOR signalling and TGF‐beta signalling pathways. However, the follicular helper T cells, regulatory T cells, immune and stromal scores showed no significance between high and low CA9 expression groups. These findings suggested that CA9 plays a critical role of TSCC prognosis and tumour grade. CA9 expression significantly correlated with the regulation of cell differentiation, various oncogenes and cancer‐associated pathways.

Chemistry, metabolism and pharmacology of carcinogenic alkaloids present in areca nut and factors affecting their concentration

Areca Nut (AN), the seed of tropical palm tree Areca catechu, is a widely chewed natural product with estimated 600 million users across the world. Various AN products, thriving in the market, portray 'Areca nut' or 'Supari' as mouth freshener and safe alternative to smokeless tobacco. Unfortunately, AN is identified as a Group 1 human carcinogen by International Agency for Research on Cancer (IARC). Wide variation in the level of alkaloids, broadly ranging from 2 to 10 mg/gm dry weight, is observed in diverse variety of AN sold worldwide. For the first time, various factors influencing the formation of carcinogenic alkaloids in AN at various stages, including during the growth, processing, and storage of the nut, are discussed. Current review illustrates the mechanism of cancer induction by areca alkaloids in humans and also compiles dose-dependent pharmacology and toxicology data of arecoline, the most potent carcinogenic alkaloid in AN. Careful monitoring of the arecoline content in AN can potentially be used as a tool in product surveillance studies to identify the variations in characteristics of various AN sample sold worldwide. The article will help to generate public awareness and sensitize the government bodies to initiate campaigns against AN use and addiction.

Dissecting the Proton Transport Pathway in Oral Squamous Cell Carcinoma: State of the Art and Theranostics Implications

Cancer cells overexpress proton exchangers at the plasma membrane in order acidify the extracellular matrix and maintain the optimal pH for sustaining cancer growth. Among the families of proton exchangers implicated in carcinogenesis, carbonic anhydrases (CAs), monocarboxylate transporters (MCTs), Na⁺/H⁺ exchangers (NHEs), sodium bicarbonate cotransporters (NBCs), and vacuolar ATPases (V-ATPases) are highlighted. Considerable research has been carried out into the utility of the understanding of these machineries in the diagnosis and prognosis of several solid tumors. In addition, as therapeutic targets, the interference of their functions has contributed to the discovery or optimization of cancer therapies. According to recent reports, the study of these mechanisms seems promising in the particular case of oral squamous cell carcinoma (OSCC). In the present review, the latest advances in these fields are summarized, in particular, the usefulness of proton exchangers as potential prognostic biomarkers and therapeutic targets in OSCC.

Carbonic Anhydrases: Role in pH Control and Cancer

The pH of the tumor microenvironment drives the metastatic phenotype and chemotherapeutic resistance of tumors. Understanding the mechanisms underlying this pH-dependent phenomenon will lead to improved drug delivery and allow the identification of new therapeutic targets. This includes an understanding of the role pH plays in primary tumor cells, and the regulatory factors that permit cancer cells to thrive. Over the last decade, carbonic anhydrases (CAs) have been shown to be important mediators of tumor cell pH by modulating the bicarbonate and proton concentrations for cell survival and proliferation. This has prompted an effort to inhibit specific CA isoforms, as an anti-cancer therapeutic strategy. Of the 12 active CA isoforms, two, CA IX and XII, have been considered anti-cancer targets. However, other CA isoforms also show similar activity and tissue distribution in cancers and have not been considered as therapeutic targets for cancer treatment. In this review, we consider all the CA isoforms and their possible role in tumors and their potential as targets for cancer therapy.

Single nucleotide polymorphisms and haplotypes of carbonic anhydrase 9 can predict invasive squamous cell carcinoma of uterine cervix

This study aimed to explore the involvement of carbonic anhydrase 9 (CA9) single nucleotide polymorphisms (SNPs) in the development of invasive cancer of uterine cervix for Taiwanese women. Ninety-seven patients with cervical invasive squamous cell carcinoma and 88 with preinvasive squamous cell lesions as well as 324 control women were recruited. Two CA9 SNPs in exons, including rs2071676 (+201, G/A) in exon 1 and rs3829078 (+1081, A/G) in exon 7, rs1048638 (+1584, C/A) in 3'-untranslated region of exon 11, as well as an 18-base pair deletion/insertion (376deltion393) in exon 1 were selected and their genotypic distributions were determined by real-time polymerase chain reaction. Haplotype was then constructed with rs2071676, 376del393, rs3829078 and rs1048638 in order. The results revealed that Taiwanese women with genotypes CA or CA/AA in CA9 SNP rs1048638 displayed a more risk in developing cervical invasive cancer, assigning wild genotype CC as a reference. AA in SNP rs2071676 tended to increase the risk of developing cervical invasive cancer, using GG/GA as a reference. When women had the diplotypes, carrying at least one haplotype A1AA (one mutant allele A in rs2071676, no deletion in 376del393, no mutant allele A in rs3829078 and one mutant allele A in rs1048638), they were significantly susceptible to cervical invasive cancer. In conclusion, CA9 SNP rs1048638 and haplotype A1AA are associated with the susceptibility of cervical invasive squamous cell carcinoma for Taiwanese women.

An update on anticancer drug development and delivery targeting carbonic anhydrase IX

The expression of carbonic anhydrase (CA) IX is up-regulated in many types of solid tumors in humans under hypoxic and acidic microenvironment. Inhibition of CA IX enzymatic activity with selective inhibitors, antibodies or labeled probes has been shown to reverse the acidic environment of solid tumors and reduce the tumor growth establishing the significant role of CA IX in tumorigenesis. Thus, the development of potent antitumor drugs targeting CA IX with minimal toxic effects is important for the target-specific tumor therapy. Recently, several promising antitumor agents against CA IX have been developed to treat certain types of cancers in combination with radiation and chemotherapy. Here we review the inhibition of CA IX by small molecule compounds and monoclonal antibodies. The methods of enzymatic assays, biophysical methods, animal models including zebrafish and Xenopus oocytes, and techniques of diagnostic imaging to detect hypoxic tumors using CA IX-targeted conjugates are discussed with the aim to overview the recent progress related to novel therapeutic agents that target CA IX in hypoxic tumors.

Impact of microRNA-34a and polymorphism of its target gene CA9 on susceptibility to uterine cervical cancer

The purposes of this study were to associate the genetic polymorphisms in carbonic anhydrase (CA) 9 with uterine cervical cancer and identify the clinical implications. Three single-nucleotide polymorphisms (SNPs), rs2071676 (+201, G/A), rs3829078 (+1081, A/G), and rs1048638 (+1584, C/A), and an 18-base-pair deletion/insertion (376del393) in CA9 were examined. We used the Boyden chamber assay to evaluate the influence of CA9 on the migration of cervical cancers. Tissue microarrays were used to evaluate CAIX immunoreactivity and determine its clinical significance. The results revealed that the CA9 SNP rs1048638 is the only significant polymorphism that increases the risk of cervical cancer in Taiwanese women. We discovered that the CA9 SNP rs1048638 influences the expression of CA9 through the interaction between the 3′-untranslated region (UTR) of exon 11, where the SNP is located, and miR-34a, and influences the migration of cervical cancer cells. Moreover, we demonstrated that CAIX immunoreactivity is related to the occurrence of cervical cancer, and elevated CAIX immunoreactivity is associated with a more advanced stage. In conclusion, the finding that the CA9 SNP rs1048638 exerts its action through duplexes of the miR-34a and CA9 3′-UTRs and plays a vital role in cervical cancer in Taiwanese women may be applicable to translational medicine.

Overexpression of carbonic anhydrase IX induces cell motility by activating matrix metalloproteinase-9 in human oral squamous cell carcinoma cells

Oral cancer is a solid malignant tumor that is prone to occur following hypoxia. There are no clear studies showing a link between hypoxia and oral carcinogenesis. Carbonic anhydrase IX (CAIX), which is a hypoxia-induced transmembrane protein, is highly expressed in various types of human cancer. However, the effects of CAIX on the metastasis of human oral cancer cells and the underlying molecular mechanisms have not been clarified. In this study, we observed that CAIX overexpression increased the migratory and invasive abilities of SCC-9 and SAS cells. In addition, CAIX overexpression increased the mRNA and protein expression of matrix metalloproteinase-9 (MMP-9) and the phosphorylation of focal adhesion kinase (FAK), steroid receptor coactivator (Src), and extracellular signal-regulated kinase 1/2 signaling proteins. CAIX overexpression also increased the binding capacity of nuclear factor-κB (NF-κB), c-Jun, and c-Fos on the MMP-9 gene promoter. In addition, treatment with MMP-9 short hairpin RNA, an MMP inhibitor (GM6001), an FAK mutant, or an MEK inhibitor (U0126) inhibited CAIX-induced cell motility in SCC-9 cells. Moreover, data sets from The Cancer Genome Atlas demonstrated that CAIX expression was significantly associated with advanced progression and poor survival in oral cancer. In conclusion, it can be inferred that CAIX overexpression induces MMP-9 gene expression, which consequently induces the metastasis of oral cancer cells.

Value of pH regulators in the diagnosis, prognosis and treatment of cancer

Altered metabolism, associated with acidification of the extracellular milieu, is one of the major features of cancer. As pH regulation is crucial for the maintenance of all biological functions, cancer cells rely on the activity of lactate exporters and proton transporters to regulate their intracellular pH. The major players in cancer pH regulation are proton pump ATPases, sodium-proton exchangers (NHEs), monocarboxylate transporters (MCTs), carbonic anhydrases (CAs) and anion exchangers (AEs), which have been shown to be upregulated in several human malignancies. Thanks to the activity of the proton pumps and transporters, tumours acidify their microenvironment, becoming more aggressive and resistant to therapy. Thus, targeting tumour pH may contribute to more effective anticancer strategies for controlling tumour progression and therapeutic resistance. In the present study, we review the role of the main pH regulators expressed in human cancer cells, including their diagnostic and prognostic value, as well as their usefulness as therapeutic targets.

Prognostic value of serum carbonic anhydrase IX in testicular germ cell tumor patients

Despite the fact that testicular germ cell tumors (TGCTs) are one of the most chemosensitive solid tumors, a small proportion of patients fail to be cured following cisplatin-based first line chemotherapy. Upregulation of carbonic anhydrase IX (CA IX) in various solid tumors is associated with poor outcome. The current prospective study investigated the prognostic value of serum CA IX level in TGCTs. In total, 83 patients (16 non-metastatic following orchiectomy with no evidence of disease, 57 metastatic chemotherapy-naïve and 10 metastatic relapsed chemotherapy-pretreated) starting adjuvant and/or new line of chemotherapy and 35 healthy controls were enrolled in the study. Serum CA IX values were determined using an enzyme-linked immunosorbent assay, and intratumoral CA IX was analyzed by immunohistochemistry. Metastatic chemotherapy-naïve patients had significantly higher mean CA IX serum levels than healthy controls (490.6 vs. 249.6 pg/ml, P=0.005), while there was no difference in serum CA IX levels in non-metastatic or relapsed TGCT patients compared with healthy controls. There was no significant difference in the mean serum CA IX levels between different groups of patients and between the first and second cycle of chemotherapy, nor association with patients/tumor characteristics. Serum CA IX was not prognostic for progression-free survival [hazard ratio (HR)=0.81, P=0.730] or overall survival (HR=0.64, P=0.480). However, there was a significant association between intratumoral CA IX expression and serum CA IX concentration (rho=0.51, P=0.040). These results suggest that serum CA IX level correlates with tumor CA IX expression in TGCT patients, but fails to exhibit either a prognostic value or an association with patients/tumor characteristics.