Gene Expression Omnibus Database Analysis Research Articles

GRK2 mediated degradation of SAV1 initiates hyperplasia of fibroblast-like synoviocytes in rheumatoid arthritis

Hyperplasia and migration of fibroblast-like synoviocytes (FLSs) are the key drivers in the pathogenesis of rheumatoid arthritis (RA) and joint destruction. Abundant Yes-associated protein (YAP), which is a powerful transcription co-activator for proliferative genes, was observed in the nucleus of inflammatory FLSs with unknown upstream mechanisms. Using Gene Expression Omnibus database analysis, it was found that Salvador homolog-1 (SAV1), the pivotal negative regulator of the Hippo-YAP pathway, was slightly downregulated in RA synovium. However, SAV1 protein expression is extremely reduced. Subsequently, it was revealed that SAV1 is phosphorylated, ubiquitinated, and degraded by interacting with an important serine-threonine kinase, G protein-coupled receptor (GPCR) kinase 2 (GRK2), which was predominately upregulated by GPCR activation induced by ligands such as prostaglandin E2 (PGE2) in RA. This process further contributes to the decreased phosphorylation, nuclear translocation, and transcriptional potency of YAP, and leads to aberrant FLSs proliferation. Genetic depletion of GRK2 or inhibition of GRK2 by paroxetine rescued SAV1 expression and restored YAP phosphorylation and finally inhibited RA FLSs proliferation and migration. Similarly, paroxetine treatment effectively reduced the abnormal proliferation of FLSs in a rat model of collagen-induced arthritis which was accompanied by a significant improvement in clinical manifestations. Collectively, these results elucidate the significance of GRK2 regulation of Hippo-YAP signaling in FLSs proliferation and migration and the potential application of GRK2 inhibition in the treatment of FLSs-driven joint destruction in RA.

ARHGAP44-mediated regulation of the p53/C-myc/Cyclin D1 pathway in modulating the malignant biological behavior of osteosarcoma cells

ObjectiveOsteosarcoma is a rare primary malignant tumor of the bone characterized by poor survival rates, owing to its unclear pathogenesis. Rho GTPase-activating protein 44 (ARHGAP44), which belongs to the Rho GTPase-activating protein family, has promising applications in the targeted therapy of tumors. Therefore, this study aimed to investigate the biological function of ARHGAP44 in osteosarcoma and its possible application as a therapeutic target.MethodsThe expression level of ARHGAP44 in osteosarcoma and its relationship with tumor prognosis were detected using Gene Expression Omnibus database analysis and immunohistochemical staining of clinical specimens. The cell model of ARHGAP44 knockdown was constructed, and the effects of this gene on the malignant biological behavior of osteosarcoma cells were investigated using CCK-8, clone formation, transwell invasion, wound healing, and flow cytometry assays. Western blotting was performed to detect the expression of ARHGAP44, p53, C-myc, and Cyclin D1 in osteosarcoma.ResultsBiogenic analysis showed that ARHGAP44 was highly expressed in osteosarcoma. This result was associated with poor tumor prognosis and negatively correlated with the expression of the tumor suppressor gene p53. Immunohistochemistry and western blotting revealed significantly upregulated expression of ARHGAP44 in osteosarcoma tissues. Additionally, Kaplan–Meier analysis of clinical specimens suggested that ARHGAP44 was negatively correlated with tumor prognosis. CCK-8, clone formation, transwell invasion, wound healing, and flow cytometry assays showed that downregulation of ARHGAP44 expression significantly reduced the malignant biological behavior of osteosarcoma cells. Furthermore, western blotting showed that the expression level of p53 in osteosarcoma cells was significantly increased after the downregulation of ARHGAP44 expression, whereas the expression of C-myc and Cyclin D1 was significantly decreased compared with that in the control group.ConclusionARHGAP44 was highly expressed in osteosarcoma and was negatively correlated with its prognosis. The downregulation of ARHGAP44 expression reduced the malignant biological behavior of osteosarcoma cells. These findings suggest that the downregulation of ARHGAP44 expression inhibits the malignant progression of osteosarcoma by regulating the p53/C-myc/Cyclin D1 pathway, demonstrating the potential of ARHGAP44 as a therapeutic target for osteosarcoma.

SILENCING M 6 A READER YTHDC1 REDUCES INFLAMMATORY RESPONSE IN SEPSIS-INDUCED CARDIOMYOPATHY BY INHIBITING SERPINA3N EXPRESSION.

Sepsis-induced cardiomyopathy (SIC) is one of the most common complications of infection-induced sepsis. An imbalance in inflammatory mediators is the main factor leading to SIC . N 6 -methyladenosine (m 6 A) is closely related to the occurrence and development of sepsis. N 6 -methyladenosine reader YTH domain containing 1 (YTHDC1) is an m 6 A N 6 -methyladenosine recognition protein. However, the role of YTHDC1 in SIC remains unclear. Herein, we demonstrated that YTHDC1-shRNA inhibits inflammation, reduces inflammatory mediators, and improves cardiac function in a LPS-induced SIC mouse model. Based on the Gene Expression Omnibus database analysis, serine protease inhibitor A3N is a differential gene of SIC. Furthermore, RNA immunoprecipitation indicated that serine protease inhibitor A3N (SERPINA3N) mRNA can bind to YTHDC1, which regulates the expression of SERPINA3N. Serine protease inhibitor A3N-siRNA reduced LPS-induced inflammation of cardiac myocytes. In conclusion, the m 6 A reader YTHDC1 regulates SERPINA3N mRNA expression to mediate the levels of inflammation in SIC. Such findings add to the relationship between m 6 A reader YTHDC1 and SIC, providing a new research avenue for the therapeutic mechanism of SIC.

Delta-catenin attenuates medulloblastoma cell invasion by targeting EMT pathway.

Background: Medulloblastoma is the most common pediatric malignant tumor in central nervous system. Although its prognosis has been improved enormously by the combination treatments with surgery, radiotherapy, and chemotherapy, it still could progress via invasion and distant dissemination. We aimed to investigate molecular mechanisms of medulloblastoma invasion in the current work. Methods: The gene expression profile of medulloblastoma were analyzed based on the data deposited in Gene Expression Omnibus (GEO) and filtered according to brain specific proteins in the Uniprot. Delta-catenin was identified and further analyzed about its expression and roles in the prognosis of medulloblastoma patient. The function of delta-catenin on cell invasion and migration were investigated by transwell and wound healing assay. Whether delta-catenin participates in the epithelial-mesenchymal transition (EMT) regulated invasion was also studied. Results: Delta-catenin expression was highly upregulated in tumor tissues compared to normal tissues from medulloblastoma patients in five independent, nonoverlapping cohorts. Furthermore, delta-catenin expression level was upregulated in WNT subgroup, and significantly correlated with better prognosis, and associated with metastasis through GEO database analysis. Functional assays indicated that delta-catenin inhibited medulloblastoma cell invasion and migration through regulating the key factors of EMT pathway, such as E-cadherin and vimentin. Conclusion: Delta-catenin might be a positive predictor for prognosis of medulloblastoma patients, through attenuating medulloblastoma cell invasion by inhibiting EMT pathway.

Soluble TGFBI aggravates the malignancy of cholangiocarcinoma through activation of the ITGB1 dependent PPARγ signalling pathway.

Cholangiocarcinoma is a devastating cancer with a poor prognosis. Previous reports have presented conflicting results on the role of transforming growth factor-β-induced protein (TGFBI) in malignant cancers. Currently, our understanding of the role of TGFBI in cholangiocarcinoma is ambiguous. The aim of the present study was to investigate the role of TGFBI in human cholangiocarcinoma. Iterative patient partitioning (IPP) scoring and consecutive elimination methods were used to select prognostic biomarkers. mRNA and protein expression levels were determined using Gene Expression Omnibus (GEO), Western blot and ELISA analyses. Biological activities of selected biomarkers were examined using both in vitro and in vivo assays. Prognostic values were assessed using Kaplan-Meier and Liptak's z score analyses. TGFBI was selected as a candidate cholangiocarcinoma biomarker. GEO database analysis revealed significantly higher TGFBI mRNA expression levels in cholangiocarcinoma tissues compared to matched normal tissues. TGFBI protein was specifically detected in a soluble form in vitro and in vivo. TGFBI silencing evoked significant anti-cancer effects in vitro. Soluble TGFBI treatment aggravated the malignancy of cholangiocarcinoma cells both in vitro and in vivo through activation of the integrin beta-1 (ITGB1) dependent PPARγ signalling pathway. High TGFBI expression was associated with a poor prognosis in patients with cholangiocarcinoma. Our data suggest that TGFBI may serve as a promising prognostic biomarker and therapeutic target for cholangiocarcinoma.

GINS1 Induced Sorafenib Resistance by Promoting Cancer Stem Properties in Human Hepatocellular Cancer Cells.

Hepatocellular carcinoma (HCC) is characterized by a high rate of incidence and recurrence, and resistance to chemotherapy may aggravate the poor prognosis of HCC patients. Sorafenib resistance is a conundrum to the treatment of advanced/recurrent HCC. Therefore, studies on the molecular pathogenesis of HCC and the resistance to sorafenib are of great interest. Here, we report that GINS1 was highly expressed in HCC tumors, associated with tumor grades, and predicted poor patient survival using Gene Expression Omnibus (GEO) databases exploration. Cell cycle, cell proliferation assay and in vivo xenograft mouse model indicated that knocking down GINS1 induced in G1/S phase cell cycle arrest and decreased tumor cells proliferation in vitro and in vivo. Spheroid formation assay results showed that GINS1 promoted the stem cell activity of HCC tumor cells. Furthermore, GEO database (GSE17112) analysis showed that HRAS oncogenic gene set was enriched in GINS1 high-expressed cancer cells, and quantitative real-time PCR, and Western blot results proved that GINS1 enhanced HCC progression through regulating HRAS signaling pathway. Moreover, knocking down endogenous GINS1 with shGINS1 increased the sensitivity of HCC cells to sorafenib, and restoring HRAS or stem associated pathway partly recovered the sorafenib resistance. Overall, the collective findings highlight GINS1 functions in hepatocarcinogenesis and sorafenib resistance, and indicate its potential use of GINS1 in drug-resistant HCC.

An 8-gene DNA methylation signature predicts the recurrence risk of cervical cancer.

ObjectiveThis study examined the predictive utility of DNA methylation for cervical cancer recurrence.MethodsDNA methylation and RNA expression data for patients with cervical cancer were downloaded from The Cancer Genome Atlas. Differentially methylated genes (DMGs) and differentially expressed genes were screened and extracted via correlation analysis. A support vector machine (SVM)-based recurrence prediction model was established using the selected DMGs. Cox regression analysis and receiver operating characteristic curve analysis were used for self-evaluation. The Gene Expression Omnibus (GEO) database was applied for external validation. Functional enrichment was determined using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses.ResultsAn eight-gene DNA methylation signature identified patients with a high risk of recurrence (area under the curve = 0.833). The SVM score was an independent risk factor for recurrence (hazard ratio [HR] = 0.418; 95% confidence interval [CI] = 0.26–0.67). The independent GEO database analysis further supported the result.ConclusionAn eight-gene DNA methylation signature predictive of cervical cancer recurrence was identified in this study, and this signature may help identify patients at high risk of recurrence and improve clinical treatment.

LncRNA OIP5-AS1 Promotes the Autophagy-Related Imatinib Resistance in Chronic Myeloid Leukemia Cells by Regulating miR-30e-5p/ATG12 Axis.

Background: Resistance to tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia (CML) remains a problem in clinical treatment, and the mechanism has not been fully clarified. Autophagy can protect cancer cells under chemotherapeutic stimulation. Long noncoding RNAs (lncRNAs) are critical in drug resistance of CML. The role of lncRNAs in autophagy and drug resistance of CML needs to be further explored. Methods: Western blot and immunofluorescence were used to evaluate the autophagy activity in the drug-resistant CML cell line K562/G01 and its parental cell line K562. Then the sensitivity of K562/G01 cells to the first generation TKI imatinib (IM) after autophagy inhibition was determined by CCK-8 assays. The lncRNA OIP5-AS1 related to the drug resistance of CML cells was determined by Gene Expression Omnibus database analysis. Western blot and drug-sensitivity assays were used to detect changes in autophagy and sensitivity to the IM in resistant CML cells after OIP5-AS1 knockdown. The interactions of OIP5-AS1, miR-30e-5p, and ATG12 were explored by RNA immunoprecipitation and dual-luciferase reporter assays. Results: In this study, we found that autophagy was associated with drug resistance in CML cells. Moreover, the upregulation of OIP5-AS1 in K562/G01 cells was related to the enhancement of autophagy. Knockdown of OIP5-AS1 suppressed autophagy and enhanced the sensitivity of K562/G01 cells to IM. Furthermore, OIP5-AS1 regulated ATG12 by competitively binding miR-30e-5p, thereby affecting autophagy-related drug resistance. Conclusion: Our study reveals that OIP5-AS1 promotes the autophagy-related IM resistance in CML cells by regulating miR-30e-5p/ATG12 axis, providing new insights into the drug resistance mechanism of CML.

MicroRNA-587 Functions as a Tumor Suppressor in Hepatocellular Carcinoma by Targeting Ribosomal Protein SA.

Background Hepatocellular carcinoma (HCC) is one of the most highly aggressive cancer worldwide with an extremely poor prognosis. Evidence has revealed that microRNA-587 (miR-587) is abnormally expressed in a series of cancers. However, its expressions and functions in HCC have not been clearly acknowledged. Methods We detected the expression level of miR-587 both in the Gene Expression Omnibus (GEO) database and 86 paired clinical HCC tissues together with paired adjacent normal tissues by quantitative real-time PCR (qRT-PCR). Afterwards, the transfected HCC cell line SMMC-7721 cells were collected for the cell proliferation assay, cell-cycle arrest, cell migration, and invasion assays to explore the roles of miR-587 in regulating cellular function. In addition, bioinformatics analysis, combined with qRT-PCR and dual-luciferase reporter assays, were performed to confirm whether ribosomal protein SA (RPSA) mRNA was the direct target gene of miR-587. Moreover, the Cancer Genome Atlas (TCGA) and GEO databases as well as 86 paired clinical HCC tissues were used to verify the negative regulation between miR-587 and RPSA. Results In the present study, both the GEO database (GSE36915 and GSE74618) analysis and qRT-PCR analysis of 86 paired clinical tissues showed that miR-587 was significantly downregulated in HCC tissues. The overexpression of miR-587 inhibited proliferation, cell cycle, migration, and invasion in SMMC-7721 cells. In addition, miR-587 directly interacted with the 3′-untranslated region (UTR) of RPSA. Moreover, miR-587 overexpression directly suppressed RPSA expression, and the two genes were inversely expressed in HCC based on the analyses in TCGA and GEO (GSE36376) databases and qPCR analysis of 86 paired clinical tissues. Conclusion Our results demonstrate that miR-587 is downexpressed in HCC and regulates the cellular function by targeting RPSA.

Differential regulation of TGFβ type-I receptor expressions in TGFβ1-induced myofibroblast differentiation.

Fibroblast-to-myofibroblast (FibroMF) differentiation is crucial for embryogenesis and organ fibrosis. Although transforming growth factor-β (TGFβ) is the primary mediator of FibroMF differentiation, the type-I receptor (TGFβRI) responsible for this has not yet been confirmed. In the current study, we investigated the ALK1 and ALK5 expressions in TGFβ1-stimulated NIH 3T3 fibroblasts to compare with the data from the Gene Expression Omnibus (GEO) repository. In our results, whereas TGFβ1 treatment promoted FibroMF differentiation accompanied by increased ALK5 expression and reduced ALK1 expression, TGFβ1-induced FibroMF differentiation and increased α-smooth muscle actin (αSMA) and ALK5 expression were inhibited by co-treatment with ALK5 inhibitor SB431542. GEO database analysis indicated increased ALK5 expression and reduced ALK1 expression in fibrotic compared to normal mouse or human tissues correlating with organ fibrosis progression. Finally, the inhibitors of Akt, mTOR, and β-catenin suppressed TGFβ1-induced ALK5 expression, indicating that the Akt pathway promotes FibroMF differentiation via ALK5 expression and fibrosis.

Liver X Receptor α-Induced Cannabinoid Receptor 2 Inhibits Ubiquitin-Specific Peptidase 4 Through miR-27b, Protecting Hepatocytes From TGF-β.

Liver X receptor‐alpha (LXRα) acts as a double‐edged sword in different biological situations. Given the elusive role of LXRα in hepatocyte viability, this study investigated whether LXRα protects hepatocytes from injurious stimuli and the underlying basis. LXRα activation prevented hepatocyte apoptosis from CCl4 challenges in mice. Consistently, LXRα protected hepatocytes specifically from transforming growth factor‐beta (TGF‐β), whereas LXRα deficiency aggravated TGF‐β‐induced hepatocyte injury. In the Gene Expression Omnibus database analysis for LXR−/− mice, TGF‐β receptors were placed in the core network. Hierarchical clustering and correlation analyses enabled us to find cannabinoid receptor 2 (CB2) as a gene relevant to LXRα. In human fibrotic liver samples, both LXRα and CB2 were lower in patients with septal fibrosis and cirrhosis than those with portal fibrosis. LXRα transcriptionally induced CB2; CB2 then defended hepatocytes from TGF‐β. In a macrophage depletion model, JWH133 (a CB2 agonist) treatment prevented toxicant‐induced liver injury. MicroRNA 27b (miR‐27b) was identified as an inhibitor of ubiquitin‐specific peptidase 4 (USP4), deubiquitylating TGF‐β receptor 1 (TβRI), downstream from CB2. Liver‐specific overexpression of LXRα protected hepatocytes from injurious stimuli and attenuated hepatic inflammation and fibrosis. Conclusion: LXRα exerts a cytoprotective effect against TGF‐β by transcriptionally regulating the CB2 gene in hepatocytes, and CB2 then inhibits USP4‐stabilizing TβRI through miR‐27b. Our data provide targets for the treatment of acute liver injury.

Lysine demethylase2A promotes the progression of ovarian cancer by regulating the PI3K pathway and reversing epithelial‑mesenchymal transition.

Metastasis is the most common cause of death in ovarian cancer patients but remains largely untreated. Epithelial-mesenchymal transition (EMT) is critical for the conversion of early-stage ovarian tumors into metastatic malignancies. Thus, investigating the signaling pathways promoting EMT may identify potential targets for the treatment of metastatic ovarian cancer. Lysine demethylase 2A (KDM2A), also known as FBXL11 and JHDM1A, is a histone H3 lysine 36 (H3K36) demethylase that regulates EMT and the metastasis of ovarian cancer. However, the function and underlying mechanisms of EMT suppression in ovarian cancer have not been thoroughly elucidated to date. In the present study, we used Gene Expression Omnibus (GEO) databases to determine that KDM2A is significantly upregulated in human ovarian cancers. KDM2A expression was assessed by immunohistochemistry of epithelial ovarian cancer (EOC) borderline ovarian tumors and normal ovary tissues. Seven fresh EOC tissues and 3 fresh normal ovary tissues were collected for western blot analysis. Kaplan-Meier survival curves were constructed to identify genes related to EOC prognosis from the TCGA data portal. Stable KDM2A-knockdown cell lines were established to study the biological functions and underlying mechanisms of KDM2A in EMT in vitro. GEO database analysis revealed that KDM2A was highly upregulated in EOC tissues; this analysis was accompanied by immunochemistry and western blot analysis using samples of human tissues. High expression of KDM2A was associated with poor survival in EOC patients. KDM2A knockdown promoted apoptosis and suppressed the proliferation, migration and invasion of tumor cells in vitro. EMT and the PI3K/AKT/mTOR signaling pathway were suppressed in KDM2A-silenced cells. Inactivation of the PI3K/AKT/mTOR signaling pathway in A2780 cells induced EMT inhibition. Our data revealed that KDM2A functions as a tumor oncogene, and the downregulation of KDM2A expression regulates EMT and EOC progression, providing a valuable prognostic marker and potential target for the treatment of EOC patients.

Serine hydroxymethyltransferase 1 promoter hypermethylation increases the risk of essential hypertension.

Serine hydroxymethyltransferase 1 (SHMT1) is an enzyme involved in folic acid metabolism and is known to contribute to the development of hypertension. We evaluated the relationship between SHMT1 promoter methylation and essential hypertension (EH). Quantitative methylation-specific polymerase chain reaction was used to measure the SHMT1 promoter methylation level in 241 EH patients and 288 age- and gender-matched healthy individuals. The diagnostic value of SHMT1 promoter hypermethylation was analyzed using a receiver operating characteristic (ROC) curve. The Gene Expression Omnibus (GEO) database and dual-luciferase reporter assay were used to validate our findings. Compared with the control group, significant differences in SHMT1 promoter methylation were found in both EH and hyperhomocysteinemia groups (P<0.001 and P=0.029, respectively). The area under the curve of the diagnosis of SHMT1 promoter hypermethylation for EH was 0.808, with a sensitivity and specificity of 73.9% and 77.8%, respectively. The risk of SHMT1 promoter hypermethylation was significantly higher in the >65-year group than in the ≤65-year group (odds ratio=3.925; 95% confidence interval=2.141-7.196). In addition, GEO database analysis showed that 5-aza-deoxycytidine increased gene expression in several carotid endothelial cell lines. A dual-luciferase reporter assay revealed that the target sequence in the SHMT1 promoter upregulated gene expression. Our findings indicate that SHMT1 promoter hypermethylation increases the risk of EH and may be a promising biomarker for EH.

MiR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma.

Accumulating evidence has indicated that microRNAs (miRNAs) play an important role in the occurrence and progression of ovarian cancer (OC). However, the function of miRNAs implicated in OC remains unclear. This study investigated the potential role of miR-211 in OC. Gene Expression Omnibus database analysis indicated that miR-211 expression was significantly down-regulated in OC tissues compared with normal specimens. In addition, miR-211 overexpression apparently inhibited proliferation, migration, xenograft growth, and induced apoptosis in HEY-T30 and SKOV3 cells. Moreover, PHF19, a component of the polycomb group of proteins, was found to be a direct target of miR-211 based on the luciferase reporter assay and Western blot analysis. Consistently, survival analysis indicated that high PHF19 expression was associated with shorter survival time in patients with OC. Importantly, silence of PHF19 reduced proliferation, induced cell cycle arrest, promoted apoptosis, suppressed migration, and inhibited xenograft growth in SKOV3 cells. Restoration of PHF19 expression markedly reversed the inhibitory effect of miR-211 on OC. Moreover, our results indicate that the long noncoding RNA MALAT1 could sponge miR-211 as a competing endogenous RNA and potentially up-regulate PHF19 expression, thus facilitating the OC progression. These findings suggest that the MALAT1/miR-211/PHF19 axis may act as a key mediator in OC and provide new insight into the prevention of this disease.-Tao, F., Tian, X., Ruan, S., Shen, M., Zhang, Z. miR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma.

Upregulated plasmacytoma variant translocation 1 promotes cell proliferation, invasion and metastasis in colorectal cancer.

Emerging evidence indicates that the long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) is associated with tumourigenesis in various types of cancer. However, its specific effects on the proliferation, invasion and metastasis of colorectal cancer (CRC) are still poorly understood. The present study aimed to investigate PVT1 expression in CRC and explore its role in CRC pathogenesis. The reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) technique was used to assess PVT1 expression in CRC cell lines. Gene Expression Omnibus (GEO) database analysis and measurement of clinical samples was used to analyse the correlation between PVT1 expression, CRC metastasis and overall survival (OS). In addition, knockdown of PVT1 expression was performed using short interfering RNA (siRNA) and RT-qPCR, western blotting, CCK-8 assays, tumour cell clone-formation and Matrigel invasion assays were used to observe its biological functions in HCT116 cells. The present study demonstrated that the expression of PVT1 in CRC cell lines was higher than that in normal colon mucosal cell lines. Using GEO database analysis and the measurement of clinical samples, it was revealed that CRC patients with high PVT1 expression demonstrated poor OS. Multivariate analysis indicated that high PVT1 expression is an independent risk factor for patients with CRC. In addition, PVT1 knockdown suppressed the proliferation, invasion and metastasis of CRC cells in vitro, which were associated with decreasing vimentin, cyclin D1 and cyclin-dependent kinase 4 expression and enhanced E-cadherin expression. The results of the present study suggest that PVT1 may serve a critical role in CRC progression and metastasis and may serve as a potential prognostic biomarker for CRC.

Effect of SLC7A5 on the proliferation of tumor cells and its relationship with transforming growth factor-β1 signal pathway

To explore the biological effects of amino acid transporter gene SLC7A5 (solute carrier family 7, member 5) on tumor cells and the regulatory mechanism at transcriptional level. Methods: The expression of SLC7A5 was examined in human normal tissues and corresponding tumor tissues by Gene Expression Omnibus (GEO) database. The recombinant plasmid of SLC7A5 gene was constructed, and the effect of the SLC7A5 gene on tumor cell proliferation was investigated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) and flow cytometry. SLC7A5 gene promoter and transcription factor binding sites were predicted through bioinformatics analysis, and the gene promoter recombinant plasmid was constructed. Then the dual luciferase reporter gene assay and reverse transcription polymerase chain reaction (RT-PCR) were used to explore the regulation of transforming growth factor-β1 (TGF-β1) signal on SLC7A5 gene expression. Results: The GEO database analysis showed that the distribution of SLC7A5 was tissue specific, and its expression level was significantly higher in the tumor tissues than that in the corresponding normal tissues. The results of MTT and flow cytometry showed that SLC7A5 could promote cell proliferation. Results from the promoter analysis, reporter gene assay and RT-PCR confirmed that TGF-β1 could up-regulate the activity of SLC7A5 promoter and promote the expression of the SLC7A5 gene. Conclusion: SLC7A5 gene plays a role in promoting tumor development, which is regulated by the TGF-β1 signaling pathway.