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(a) IC50 values (μM) of 5-FU, doxorubicin (DOX) or SN-38 of the SLC6A6-KD and control cells. IC50, half-maximal inhibitory drug concentration. Each bar represents n = 3; means ± SD. *P<0.05, **P<0.01, ***P<0.001 (Student's t-test). (b) Estimation of both MDR1 and ABCG2 expression in the SLC6A6-KD and control cells using flow cytometry. The percentage of MDR1-positive/ABCG2-positive cells (upper right), MDR1-negative/ABCG2-positive cells (upper left) and MDR1-positive/ABCG2-negative cells (lower right) is indicated in each panel. (c) The accumulation of the fluorescent drugs 5 hours after treatment with 3 μM DOX or 30 μM CPT-11 (the prodrug of SN-38) in the HCT-15 SLC6A6-KD and control cells was measured using flow cytometry. (d) Quantitative RT-PCR of the molecules involved in 5-FU metabolism in the HCT-15 SLC6A6-KD and control cells. Each bar represents n = 3; means ± SD. NS, not significant (Student's t-test). Ct, control; KD, knockdown (using short hairpin RNA).
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The treatment of colorectal cancer (CRC) might be improved by the identification of a signalling pathway that could be targeted with novel therapeutics. The results of this study indicate that the taurine transporter SLC6A6 is highly expressed in CRC cells compared with normal colonocytes. SLC6A6 knockdown (KD) attenuated cell survival and was acco...
Citations
... It is known that A2780 cell line cisplatin resistance correlates with an increased intracellular accumulation of glutathione and taurine that, in turn, protects cells from oxidative stress [41], volume reduction [42], and apoptosis [43]. Furthermore, the TauT transporter, involved in taurine transport across the membrane, promotes survival and multidrug resistance in colorectal cancer cells [44], and its overexpression protects kidney cells against cisplatin-induced cell death [45]. Thus, in an A2780cis cell line, the increased level of intracellular glutathione and taurine could be the main mechanisms involved in cisplatin resistance; on the other hand, HGSOC_T and HGSOC_A cells have a glutathione and taurine content similar to the A2780 sensitive cell line. ...
Cancer cell lines are frequently used in metabolomics, such as in vitro tumor models. In particular, A2780 cells are commonly used as a model for ovarian cancer to evaluate the effects of drug treatment. Here, we compare the NMR metabolomics profiles of A2780 and cisplatin-resistant A2780 cells with those of cells derived from 10 patients with high-grade serous ovarian carcinoma (collected during primary cytoreduction before any chemotherapeutic treatment). Our analysis reveals a substantial similarity among all primary cells but significant differences between them and both A2780 and cisplatin-resistant A2780 cells. Notably, the patient-derived cells are closer to the resistant A2780 cells when considering the exo-metabolome, whereas they are essentially equidistant from A2780 and A2780-resistant cells in terms of the endo-metabolome. This behavior results from dissimilarities in the levels of several metabolites attributable to the differential modulation of underlying biochemical pathways. The patient-derived cells are those with the most pronounced glycolytic phenotype, whereas A2780-resistant cells mainly diverge from the others due to alterations in a few specific metabolites already known as markers of resistance.
... A previous study demonstrated that the cancer stem cell population of prostate cancer cells exhibited significantly elevated expression of RPL13a [36]. Expression of the taurine transporter SLC6A6 is significantly higher in colorectal cancer cells than in normal adjacent cells [37]. The inhibition of SLC6A6 resulted in a reduction in the population of side population (SP) cells and their cancer stem cell (CSC) characteristics, including their ability to initiate tumor formation [38]. ...
Luminal A breast cancer, constituting 70 % of breast cancer cases, presents a challenge due to the development of resistance and recurrence caused by breast cancer stem cells (BCSC). Luminal breast tumors are characterized by TP53 expression, a tumor suppressor gene involved in maintaining stem cell attributes in cancer. Although a previous study successfully developed mammospheres (MS) from MCF-7 (with wild-type TP53) and T47D (with mutant TP53) luminal breast cancer cells for BCSC enrichment, their transcriptomic profiles remain unclear. We aimed to elucidate the transcriptomic disparities between MS of MCF-7 and T47D cells using bioinformatics analyses of differentially expressed genes (DEGs), including the KEGG pathway, Gene Ontology (GO), drug-gene association, disease-gene association, Gene Set Enrichment Analysis (GSEA), DNA methylation analysis, correlation analysis of DEGs with immune cell infiltration, and association analysis of genes and small-molecule compounds via the Connectivity Map (CMap). Upregulated DEGs were enriched in metabolism-related KEGG pathways, whereas downregulated DEGs were enriched in the MAPK signaling pathway. Drug-gene association analysis revealed that both upregulated and downregulated DEGs were associated with fostamatinib. The KEGG pathway GSEA results indicated that the DEGs were enriched for oxidative phosphorylation, whereas the downregulated DEGs were negatively enriched for the p53 signaling pathway. Examination of DNA methylation revealed a noticeable disparity in the expression patterns of the PKM2, ERO1L, SLC6A6, EPAS1, APLP2, RPL10L, and NEDD4 genes when comparing cohorts with low- and high-risk breast cancer. Furthermore, a significant positive correlation was identified between SLC6A6 expression and macrophage presence, as well as MSN, and AKR1B1 expression and neutrophil and dentritic cell infiltration. CMap analysis unveiled SA-83851 as a potential candidate to counteract the effects of DEGs, specifically in cells harbouring mutant TP53. Further research, including in vitro and in vivo validations, is warranted to develop drugs targeting BCSCs.
... Indeed, we found that the liver had a higher GAA concentration than the pancreas or lungs in mice (Fig. S3P). Many studies have reported the overexpression of GAA transporters in liver metastatic tumours compared to primary tumours in diverse cancers, including pancreatic cancer [56,[61][62][63]. These findings suggest the potential metabolic dependency of PDAC liver metastasis on GAA utilization. ...
Background:
Pancreatic ductal adenocarcinoma (PDAC) tends to undergo distant metastasis, especially liver metastasis, leading to a poor prognosis. Metabolic remodelling and epigenetic reprogramming are two important hallmarks of malignant tumours and participate in regulating PDAC tumorigenesis and metastasis. However, the interaction between these two processes during PDAC metastasis has not been fully elucidated.
Methods:
We performed metabolomics analysis to identify the critical metabolites associated with PDAC liver metastasis and focused on guanidinoacetic acid (GAA). Intracellular GAA content was significantly increased in liver metastatic PDAC cells compared to primary cancer cells in mouse xenograft tumour models. The effects of GAA supplementation and glycine amidinotransferase (GATM) knockdown on PDAC metastasis were assessed by analysing cell migration, filopodia formation, epithelial-mesenchymal transition (EMT), and in vivo metastasis in different cell and animal models. Next, ChIP‒qPCR, 3C‒qPCR, and CRISPRi/dCas9-KRAB experiments were used to validate the "epigenome-metabolome" mechanism. Finally, the results of in vitro approaches, including RNA-seq, CUT&RUN, RT‒qPCR, and western blot analyses, as well as luciferase reporter gene assay and transwell assay, revealed the GAA-c-Myc-HMGA axis and transcription-activating histone modifications reprogramming.
Results:
A high level of intracellular GAA was associated with PDAC liver metastasis. GAA could promote the migration, EMT, and liver metastasis of pancreatic cancer cells in vitro and in vivo. Next, we explored the role of GATM-mediated de novo GAA synthesis in pancreatic cancer metastasis. High expression of GATM was positively correlated with advanced N stage in PDAC. Knockdown of GATM significantly reduced the intracellular level of GAA, suppressed EMT, and inhibited PDAC liver metastasis, and these effects were attenuated by GAA supplementation. Mechanistically, we identified the active enhancers looped to the Gatm gene locus that promoted GATM expression and PDAC liver metastasis. Furthermore, we found that GAA promoted cell migration and EMT by regulating c-Myc-mediated high mobility group AT-hook protein expression. Moreover, GAA increased the H3K4me3 modification level by upregulating histone methyltransferases, which induced the transcription of metastasis-related genes, including Myc.
Conclusions:
These findings revealed the critical role of the epigenome-metabolome interaction in regulating PDAC liver metastasis and suggested potential therapeutic strategies targeting GAA metabolism and epigenetic regulatory mechanisms.
... As it was described, severe diseases can be caused by transporters mutation and decreased function. On the other hand, overexpression and increased activity of SLC6A6 or SLC6A8 proteins were described in several types of cancer [48][49][50][51]. ...
... Overexpression of the taurine transporter was noticed in a few types of cancers such as gastric and colorectal cancer [48,49]. The connection between taurine transporter and gastric cancer was evaluated using clinical outcomes and expression datasets, such as Gene Expression Omnibus, The Cancer Genome Atlas, and Human Protein Atlas [48]. ...
... Overexpression of taurine transporter was connected with colorectal cancer (CRC) progression [49]. As noticed before, this type of cancer is one of the most common neoplasms in the world [1]. ...
Cancer cells are characterized by uncontrolled growth, proliferation, and impaired apoptosis. Tumour progression could be related to poor prognosis and due to this fact, researchers have been working on novel therapeutic strategies and antineoplastic agents. It is known that altered expression and function of solute carrier proteins from the SLC6 family could be associated with severe diseases, including cancers. These proteins were noticed to play important physiological roles through transferring nutrient amino acids, osmolytes, neurotransmitters, and ions, and many of them are necessary for survival of the cells. Herein, we present the potential role of taurine (SLC6A6) and creatine (SLC6A8) transporters in cancer development as well as therapeutic potential of their inhibitors. Experimental data indicate that overexpression of analyzed proteins could be connected with colon or breast cancers, which are the most common types of cancers. The pool of known inhibitors of these transporters is limited; however, one ligand of SLC6A8 protein is currently tested in the first phase of clinical trials. Therefore, we also highlight structural aspects useful for ligand development. In this review, we discuss SLC6A6 and SLC6A8 transporters as potential biological targets for anticancer agents.
... CRC data from TCGA were classified according to the CMS subtypes, resulting in the following subtype distribution for the 285 samples: CMS1 (59), CMS2 (144), CMS3 (33) and CMS4 (49). Hierarchical clustering of miRNA expression (Supplementary Figure S1) unveiled three different groups according to miR expression with the following correspondence with CMS subtypes determined by mRNA expression (Supplementary Table S2), this association presented a significant correlation (p < 0.0001) and was performed in those 228 samples with mRNA and miRNA data. ...
... The best scores within non-biologically-validated interactions were obtained between miR-30b which is down-regulated in the miR-HS subtype, and FAP or SLC6A6 genes, which are up-regulated in the high-stroma-subtype. High FAP and SLC6A6 levels are associated with worse prognosis in CRC [32,33]. We could not biologically validate miR-30b and FAP interaction; however, miR-30b has been shown to silence SLC6A6 expression. ...
... We could not biologically validate miR-30b and FAP interaction; however, miR-30b has been shown to silence SLC6A6 expression. Since higher levels of SLC6A6 are associated with maintenance of stem-cells properties and with chemoresistance [33] restoring miR-30b could be a promising strategy for the treatment of CRC patients of the High-stroma/CMS4 subtype. ...
Colorectal cancer consensus molecular subtypes (CMSs) are widely accepted and constitutes the basis for patient stratification to improve clinical practice. We aimed to find whether miRNAs could reproduce molecular subtypes, and to identify miRNA targets associated to the High-stroma/CMS4 subtype. The expression of 939 miRNAs was analyzed in tumors classified in CMS. TALASSO was used to find gene-miRNA interactions. A miR-mRNA regulatory network was constructed using Cytoscape. Candidate gene-miR interactions were validated in 293T cells. Hierarchical-Clustering identified three miRNA tumor subtypes (miR-LS; miR-MI; and miR-HS) which were significantly associated (p < 0.001) to the reported mRNA subtypes. miR-LS correlated with the low-stroma/CMS2; miR-MI with the mucinous-MSI/CMS1 and miR-HS with high-stroma/CMS4. MicroRNA tumor subtypes and association to CMSs were validated with TCGA datasets. TALASSO identified 1462 interactions (p < 0.05) out of 21,615 found between 176 miRs and 788 genes. Based on the regulatory network, 88 miR-mRNA interactions were selected as candidates. This network was functionally validated for the pair miR-30b/SLC6A6. We found that miR-30b overexpression silenced 3′-UTR-SLC6A6-driven luciferase expression in 293T-cells; mutation of the target sequence in the 3′-UTR-SLC6A6 prevented the miR-30b inhibitory effect. In conclusion CRC subtype classification using a miR-signature might facilitate a real-time analysis of the disease course and treatment response.
... SLC6A6 signal pathway has an influence on cell proliferation and cell survival. Further investigation shows that upregulation of this gene in colorectal cancer promotes prosurvival activity of tumour cell but did not affect cell growth rate during the cell cycle (Yasunaga and Matsumura, 2014). However, we found overexpression of SLC6A6 gene in breast cancer, which is correlated to HSP70/Grb biomarker. ...
... These features make PIK3CA a promising therapeutic target in CRC. SLC6A6, a sodium and chloride-dependent taurine transporter, is highly expressed in CRC cells compared to normal colonocytes [36]. Moreover, its knockdown attenuated cell survival and enhanced sensitivity to 5-FU treatment while decreasing the frequency of cells with cancer stem cell (CSC)-like properties [36]. ...
... SLC6A6, a sodium and chloride-dependent taurine transporter, is highly expressed in CRC cells compared to normal colonocytes [36]. Moreover, its knockdown attenuated cell survival and enhanced sensitivity to 5-FU treatment while decreasing the frequency of cells with cancer stem cell (CSC)-like properties [36]. ASAP1 is involved in the regulation of cell motility and has been shown to promote cancer cell invasiveness and metastasis, thereby correlating with poor survival in CRC patients [37,38]. ...
Identifying molecular characteristics that are associated with aggressive cancer phenotypes through gene expression profiling can help predict treatment responses and clinical outcomes. Claudins are deregulated in colorectal cancer (CRC). In CRC, increased claudin-1 expression results in epithelial-to-mesenchymal transition and metastasis, while claudin-7 functions as a tumor suppressor. In this study, we have developed a molecular signature based on claudin-1 and claudin-7 associated with poor patient survival and chemoresistance. This signature was validated using an integrated approach including publicly available datasets and CRC samples from patients who either responded or did not respond to standard-of-care treatment, CRC cell lines, and patient-derived rectal and colon tumoroids. Transcriptomic analysis from a patient dataset initially yielded 23 genes that were differentially expressed along with higher claudin-1 and decreased claudin-7. From this analysis, we selected a claudins-associated molecular signature including PIK3CA, SLC6A6, TMEM43, and ASAP-1 based on their importance in CRC. The upregulation of these genes and their protein products was validated using multiple CRC patient datasets, in vitro chemoresistant cell lines, and patient-derived tumoroid models. Additionally, blocking these genes improved 5-FU sensitivity in chemoresistant CRC cells. Our findings propose a new claudin-based molecular signature that associates with poor prognosis as well as characteristics of treatment-resistant CRC including chemoresistance, metastasis, and relapse.
... for hsa-miR-9-5p and the log fold change of SLC6A6 was 3.2. SLC6A6 is a member of sodium and chloride-ion dependent transporters that plays an important role in CRC development and multidrug resistance (Tran et al., 2014;Yasunaga & Matsumura, 2014). Previous studies F I G U R E 7 The lncRNA-miRNA-mRNA-signaling pathway network constructed by Cytoscape v3.1. ...
Accumulating evidence has indicated that deregulation of lncRNAs play essential roles in the colorectal cancer (CRC) carcinogenesis. The goal of this study was to analyze the expression of lncRNAs in colorectal cancer and their association with clinico-pathological variables. Bioinformatics analysis of published CRC microarray data was performed to identify the important lncRNAs. The expression levels of candidate genes were assessed in the human colon cancer/normal cell lines, CRC, adenomatous colorectal polyps and their marginal tissues by qRT-PCR. Moreover, methylation status of the TRPM2-AS1 promoter was studied using qMSP assay. Furthermore, we investigated the molecular mechanisms of these lncRNAs in CRC progression using in silico analysis. Microarray analysis revealed that lncRNAs SNHG6, MIR4435-2HG and TRPM2-AS1 were upregulated in CRC. These results were validated in colon cell lines. Moreover, qRT-PCR showed that the expression levels of SNHG6 and TRPM2-AS1 were upregulated in the colorectal tumor tissues compared with their paired tissues. Nonetheless, there was no significant increase in MIR4435-2HG expression in CRC samples. Furthermore, we observed a significant hypomethylation of TRPM2-AS1 promoter and its activation in CRC tissues. By in silico analysis, we found that the lncRNAs upregulation could promote proliferation and drug resistance of colorectal cancer cells via miRNAs sponging and modulation of their targets expression. In conclusion, based on our results upregulation of SNHG6 and TRPM2-AS1, and hypomethylation of TRPM2-AS1 promoter might be considered as potential diagnostic biomarkers for CRC initiation and development.
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... A previous study reported that the deficiency of the OSBPL8 gene in mice resulted in the induction of highdensity lipoproteins [63]. It has been reported that SLC6A6 promotes the survival and multidrug resistance of colorectal cancer [64]. e potential roles of OSBPL8 and SLC6A6 associated with porphyra-334 should be further elucidated. ...
Porphyra-334 is a kind of mycosporine-like amino acid absorbing ultraviolet-A. Here, we characterized porphyra-334 as a potential antiaging agent. An in vitro assay revealed that porphyra-334 dramatically promoted collagen synthesis in fibroblast cells. The effect of porphyra-334 on cell proliferation was dependent on the cell type, and the increase of cell viability by porphyra-334 was the highest in keratinocyte cells among the three tested cell types. An in vivo clinical test with 22 participants demonstrated the possible role of porphyra-334 in the improvement of periorbital wrinkles. RNA-sequencing using human follicle dermal papilla (HFDP) cells upon porphyra-334 treatment identified the upregulation of metallothionein- (MT-) associated genes, confirming the antioxidant role of porphyra-334 with MT. Moreover, the expression of genes involved in nuclear chromosome segregation and the encoding of components of kinetochores was upregulated by porphyra-334 treatment. Furthermore, we found that several genes associated with the hair follicle cycle, the hair follicle structure, the epidermal structure, and stem cells were upregulated by porphyra-334 treatment, suggesting the potential role of porphyra-334 in hair follicle growth and maintenance. In summary, we provided several new pieces of evidence of porphyra-334 as a potential antiaging cosmetic agent and elucidated the expression network in HFDP cells upon porphyra-334.
... The abundance of SLC6A6 was elevated at the surface of intermediate monocytes. SLC6A6 is a known taurine and beta-alanine transporter with proposed roles in regulation of apoptosis 28,29 . Further studies will be required to investigate whether this molecule modulates the survival of intermediate monocytes relative to the other subsets. ...
Monocytes are a critical component of the cellular innate immune system, and can be subdivided into classical, intermediate and non-classical subsets on the basis of surface CD14 and CD16 expression. Classical monocytes play the canonical role of phagocytosis, and account for the majority of circulating cells. Intermediate and non-classical cells are known to exhibit varying levels of phagocytosis and cytokine secretion, and are differentially expanded in certain pathological states. Characterisation of cell surface proteins expressed by each subset is informative not only to improve understanding of phenotype, but may also provide biological insights into function. Here we use highly multiplexed Tandem-Mass-Tag (TMT)-based mass spectrometry with selective cell surface biotinylation to characterise the classical monocyte surface proteome, then interrogate the phenotypic differences between each monocyte subset to identify novel protein markers.
