Cisplatin-resistant Gastric Cancer Research Articles

LncRNA HLA Complex Group 11 Knockdown Alleviates Cisplatin Resistance in Gastric Cancer by Targeting the miR-144-3p/UBE2D1 Axis [Retraction

[This retracts the article DOI: 10.2147/CMAR.S329846.].

Ethoxysanguinarine directly targets CIP2A to inhibit proliferation and induce autophagy of SGC7901/DDP cells

This study aims to investigate the effect of ethoxysanguinarine(Eth) on cisplatin(DDP)-resistant human gastric cancer cells and decipher the underlying mechanism. The human gastric cancer cell line SGC7901 and the DDP-resistant cell line SGC7901/DDP were used as the cell models. Western blot was employed to determine the expression levels of multidrug resistance-related proteins, and methyl thiazolyl tetrazolium(MTT) assay to detect the proliferation of SGC7901 and SGC7901/DDP cells exposed to DDP. After treatment with different concentrations of Eth, the proliferation of SGC7901 and SGC7901/DDP cells was detected by MTT assay, trypan blue exclusion assay, colony formation assay, and high-content imaging and analysis system. The apoptosis of SGC7901/DDP cells was detected by flow cytometry with Annexin V-FITC/PI staining. GFP-LC3 transfection was carried out to detect the effect of Eth on the autophagy of SGC7901/DDP cells. The expression levels of the multidrug resistance-related protein P-glycoprotein(P-gp), the apoptosis-related proteins [caspase-9, caspase-3, and poly(ADP-ribose) polymerase(PARP)], the autophagy-related protein light chain 3-Ⅱ(LC3-Ⅱ), the key effectors [mammalian target of rapamycin(mTOR), 70 kDa ribosomal protein S6 kinase(P70 S6 K), and 4 E binding protein 1(4 E-BP1)] of the mammalian target of rapamycin complex 1(mTORC1) signaling pathway, cancerous inhibitor of protein phosphatase 2A(CIP2A), and protein kinase B(Akt) were measured by Western blot. The mRNA level of CIP2A in the SGC7901/DDP cells exposed to Eth for 24 h was analyzed by RT-qPCR. After SGC7901/DDP cells were transfected with CIP2A expression vector pcDNA3.1-HA-CIP2A and treated with different concentrations of Eth, MTT assay was used to determine the prolife-ration of SGC7901/DDP cells and Western blot to detect the expression levels of related proteins. The interaction sites of Eth and CIP2A were predicted by molecular docking. The affinity between Eth and CIP2A was determined by drug affinity responsive target stability(DARTS) assay. The pharmacokinetic properties and drug-like activity of Eth were predicted by SwissADME. The results indicated that SGC7901/DDP cells were more sensitive to Eth than SGC7901 cells. Eth significantly inhibited proliferation and colony formation and changed the morphology, roundness, and area of SGC7901/DDP cells. Eth treatment caused the nucleus shrinking and significantly increased the apoptosis rate of the cells. Furthermore, Eth down-regulated the expression of caspase-9 and caspase-3 precursors and promoted the cleavage of PARP, which suggested that Eth induced the apoptosis of SGC7901/DDP cells. The GFP-LC3 in Eth-treated cells showed speckled aggregation. The up-regulated expression of LC3-Ⅱ by Eth indicated that Eth activated the autophagy of SGC7901/DDP cells. Eth down-regulated the expression of P-gp, the phosphorylation of mTOR, P70 S6K, and 4E-BP1, the expression of CIP2A, and the phosphorylation of Akt. Additionally, it increased the activity of PP2A, and had no significant effect on the expression of CIP2A in SGC7901/DDP cells. CIP2A overexpression antagonized the inhibition of cell proliferation and the activation of autophagy by Eth. Molecular docking suggested that Eth bound to CIP2A. The results of DARTS assay further proved the above binding effect. Eth has potential drug-like activity. The above results demonstrated that Eth inhibited the proliferation, induced the apoptosis, and activated the autophagy of SGC7901/DDP cells by targeting CIP2A and then down-regulating PP2A/mTORC1 signaling pathway. This study provided a new target for the treatment of cisplatin-resistant gastric cancer.

Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer.

Gastric cancer (GC) is one of the most common tumors worldwide, and cisplatin is a standard chemotherapeutic reagent for GC treatment. However, chemoresistance is an inherent challenge which limits its application and effectiveness in clinic. This study aims to investigate the mechanism of metformin-induced cisplatin resistance in GC. Intriguingly, the upregulation of mitophagy markers, mitochondrial fission, autophagy and mitophagosome were observed in SGC-7901/DDP cells compared to those in the SGC-7901 cells. Treatment with metformin significantly increased mitochondrial fission and mitophagy in both AGS and SGC-7901 cells, resulting in decreased ATP production, which unexpectedly protected GC cells against the cytotoxicity of cisplatin. In contrast, application of Chloroquine and 3-methyladenine, two inhibitors of autophagy, significantly alleviated the protective effect of metformin on SGC-7901 and AGS cells against cytotoxicity of cisplatin. Moreover, metformin also stimulated the phosphorylation of AMPK (Thr172) and increased the expression of mitophagy markers including Parkin and PINK1 in the AMPK signaling-dependent manner. Consistently, the cell viability and cell apoptosis assay showed that metformin-induced cisplatin resistance was prevented by knockdown of AMPKα1. Taken together, all data in this study indicate that metformin induced AMPK activation and PINK1/Parkin dependent mitophagy, which may contribute to the progression of cisplatin resistance in GC.

M6A Methyltransferase KIAA1429 Regulates the Cisplatin Sensitivity of Gastric Cancer Cells via Stabilizing FOXM1 mRNA.

Simple SummaryN6-methyladenosine (m6A) is involved in the development of drug resistance in various cancer types. The role of N6-methyladenosine (m6A) methyltransferase, KIAA1429, in the resistance of gastric cancer to cisplatin is largely unknown. In this study, the KIAA1429 expression level as well as m6A content were found to be higher in cisplatin resistant gastric cancer cells, and KIAA1429 regulated the sensitivity of gastric cancer cells to cisplatin treatment. We then identified p65 as the regulator of KIAA1429 expression. Mechanistically, KIAA1429 regulated the sensitivity of gastric cancer cells to cisplatin by stabilizing FOXM1 mRNA via YTHDF1. The findings from this study suggest that KIAA1429 could be a therapeutic target of cisplatin resistance in gastric cancer.Although cisplatin is frequently used to treat gastric cancer, the resistance is the main obstacle for effective treatment. mRNA modification, N6-methyladenosine (m6A), is involved in the tumorigenesis of many types of cancer. As one of the largest m6A methyltransferase complex components, KIAA1429 bridges the catalytic m6A methyltransferase components, such as METTL3. In gastric cancer, KIAA1429 was reported to promote cell proliferation. However, whether KIAA1429 is involved in the resistance of gastric cancer to cisplatin remains unclear. Here, we generated cisplatin resistant gastric cancer cell lines, and compared the m6A content between resistant cells and wild type cells. The m6A content as well as KIAA1429 expression are higher in resistant cells. Interestingly, the expression of KIAA1429 was significantly increased after cisplatin treatment. We then used shRNA to knockdown KIAA1429 and found that resistant cells responded more to cisplatin treatment after KIAA1429 depletion, while overexpression of KIAA1429 decreased the sensitivity. Moreover, we identified a putative p65 binding site on the promoter area of KIAA1429 and ChIP assay confirmed the binding. p65 depletion decreased the expression of KIAA1429. YTHDF1 is the most abundant m6A “reader” that interacts with m6A modified mRNA. Mechanistically, YTHDF1 was recruited to the 3′-untranslated Region (3′-UTR) of transcriptional factor, FOXM1 by KIAA1429 and stabilized FOXM1 mRNA. More importantly, KIAA1429 knockdown increased the sensitivity of resistant cells to cisplatin in vivo. In conclusion, our results demonstrated that KIAA1429 facilitated cisplatin resistance by stabilizing FOXM1 mRNA in gastric cancer cells.

KLF5-mediated aquaporin 3 activated autophagy to facilitate cisplatin resistance of gastric cancer

Background Resistance to chemotherapeutic drugs limits the control of gastric cancer (GC) development. The study intended to probe into the mechanism of aquaporin 3 (AQP3) on the chemoresistance of GC. Methods Cisplatin (CDDP)-resistant cells were constructed. Parental AGS and HGC-27 cells and their respective CDDP-resistant cells were transfected with AQP3 overexpression plasmid, AQP3 short hairpin RNA (sh-AQP3) and sh-Kruppel-like factor 5 (shKLF5). The expressions of AQP3 and factors related to autophagy (LC3 I, LC3 II, Atg5, Beclin-1, p62)/epithelial-mesenchymal transition (EMT; E-cadherin and snail) were assessed by Western blot and qRT-PCR. Cell counting kit-8 assay was adopted to test cell viability and half maximal inhibitory concentration (IC 50) was determined. Transwell assay was used for the examination of cell migration and invasion. The regulatory relationship of AQP3 and KLF5 was tested by chromatin immunoprecipitation (ChIP) and dual luciferase reporter assays. Results AQP3 was highly-expressed in GC cells and its level was even higher in CDDP-resistant GC cells. AQP3 silencing inhibited viability, autophagy and EMT in CDDP-resistant GC cells, while AQP3 overexpression had the opposite effect. KLF5 positively modulated AQP3 in GC cells resistant to CDDP. KLF5 knockdown reversed AQP3-induced autophagy, viability, migration, invasion and EMT in CDDP-resistant GC cells. Conclusion KLF5-modulated AQP3 activated autophagy to facilitate the resistance of GC to CDDP.

The Global mRNA Expression Profiles of Inhibiting PHGDH Induced Cisplatin Resistance in Gastric Cancer.

Objective Drug resistance is the main hindrance to improve the prognosis of patients with gastric cancer. Amino acid metabolic reprograming is essential to satisfy the different requirements of cancer cells during drug resistance, of which serine deprivation could promote resistance to cisplatin in gastric cancer. As the key enzyme in the de novo biosynthesis of serine, phosphoglycerate dehydrogenase (PHGDH) inhibition could also induce cisplatin resistance in gastric cancer. This study aims to reveal the potential mechanisms of drug resistance induced by PHGDH inhibition via exploring the global mRNA expression profiles. Materials and Methods In this experimental study, the viability and the apoptotic rate of gastric cancer cells were evaluated by using Cell Counting Kit-8 (CCK-8) analysis and flow cytometric determination, respectively. The identification of differentially expressed genes (DEGs) was tested by mRNA-sequencing (mRNA-Seq) analysis. The confirmation of sequencing results was verified using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Results The inhibition of PHGDH significantly increased the viability and decreased the apoptotic rate induced by cisplatin in gastric cancer cells. mRNA-Seq analysis revealed that the combined treatment of NCT503 reduced the number of DEGs induced by cisplatin. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Set Enrichment Analysis (GSEA) showed that unfolded protein response, ECM receptor interaction and cell cycle signaling pathways were modulated by NCT503 treatment. Hub genes were identified by using protein-protein interaction network modeling, of which E1A binding protein p300 (EP300) and heat shock protein family A (Hsp70) member 8 (HSPA8) act as the vital genes in cisplatin resistance induced by the inhibition of PHGDH. ConclusionThese findings suggested that the inhibition of PHGDH promoted cisplatin resistance in gastric cancer through various intercellular mechanisms. And appropriate serine supplementation or the modulation of EP300 and HSPA8 may be of great help in overcoming cisplatin resistance in gastric cancer.

LINC-PINT suppresses cisplatin resistance in gastric cancer by inhibiting autophagy activation via epigenetic silencing of ATG5 by EZH2.

Resistance to cisplatin (DDP) is a major obstacle in the clinical treatment of advanced gastric cancer (GC). Long noncoding RNA (lncRNA) play a significant regulatory role in the development and drug resistance of GC. In this study, we reported that the lncRNA LINC-PINT was downregulated in DDP-resistant GC cells. Functional studies showed that LINC-PINT inhibited proliferation and migration of DDP-resistant GC cells in vitro, and overexpression of LINC-PINT could enhance the sensitivity of DDP-resistant GC cells to DDP. Further investigation revealed that LINC-PINT recruited enhancer of zeste homolog 2 (EZH2) to the promotor of ATG5 to inhibit its transcription, leading to the suppression of autophagy and DDP resensitization. Collectively, our results revealed how the LINC-PINT/EZH2/ATG5 axis regulates autophagy and DDP resistance in GC. These data suggest that LINC-PINT may be a potential therapeutic target in GC.

Circ_0017274 acts on miR-637/CDX2 axis to facilitate cisplatin resistance in gastric cancer.

Currently, a substantial amount of circular RNAs (circRNAs) are closely associated with cancer development and the occurrence of drug resistance, however, circ_0017274 in cisplatin (CDDP) resistance in gastric cancer (GC) has not been addressed. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were utilized for circ_0017274, microRNA-637 (miR-637) and caudal-related homeobox transcription factor 2 (CDX2) contents analysis. Analysis of IC50, proliferation, cell cycle, apoptosis, migration and invasion of GC cells using Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry or transwell assays. Interaction between miR-637 and circ_0017274 or CDX2 was validated under the application of luciferase reporter system, RNA immunoprecipitation (RIP) analysis, and pull-down assay. The effect of circ_0017274 on CDDP sensitivity in vivo was tapped by xenograft models. Circ_0017274 and CDX2 had higher content in CDDP-resistant GC tissues and cells, while miR-637 had lower content. CDDP resistance and development of GC cells were arrested when circ_0017274 level was reduced in vitro. MiR-637 acted as a target of circ_0017274, and miR-637 downregulation abated the phenomenon of elevated sensitivity of sh-circ_0017274 to CDDP. MiR-637 was also demonstrated to interact with CDX2 and to co-regulate CDDP sensitivity in GC cells. The xenograft models also established that circ_0017274 downregulation strengthened CDDP sensitivity and thus curtailed tumour growth in vivo. Circ_0017274 downregulation boosted CDDP sensitivity by acting on miR-637/CDX2 in CDDP-resistant GC cells.

M6 A demethylase fat mass and obesity-associated protein regulates cisplatin resistance of gastric cancer by modulating autophagy activation through ULK1.

Drug resistance is an important factor for treatment failure of gastric cancer. N6‐methyladenosine (m6A) is the predominant mRNA internal modification in eukaryotes. The roles of m6A modification in drug resistance of gastric cancer remains unclear. In the present study, the m6A methylated RNA level was significantly decreased while the expression of m6A demethylase fat mass and obesity‐associated protein (FTO) was obviously elevated in cisplatin‐resistant (SGC‐7901/DDP) gastric cancer cells. Knockdown of FTO reversed cisplatin resistance of SGC‐7901/DDP cells both in vitro and in vivo, which was attributed to the inhibition of Unc‐51‐like kinase 1 (ULK1)‐mediated autophagy. Mechanistically, ULK1 expression was regulated in an FTO‐m6A‐dependent and YTHDF2‐mediated manner. Collectively, our findings indicate that the FTO/ULK1 axis exerts crucial roles in cisplatin resistance of gastric cancer.

Modulation of cisplatin resistance in gastric cancer by LncRNA SNHG15

Background: The role of long non-coding RNA (lncRNA) small nucleolar RNA host gene 15 (SNHG15) in cisplatin-resistance was studied in gastric cancer.
 Methods: The relative SNHG15 expression and its correlation with survival were assayed on the Cancer Genome Atlas data and confirmed with the clinical samples we collected. Cisplatin-resistant MKN45 cell line (MKN45 CR) was established. SNHG15 plasmid and SNHG15 shRNA plasmid were transfected into MKN45 cells and MKN45 CR cells. Colony formation analysis and cell counting kit-8 assay were utilized to determine cell proliferation and viability. The binding between SNHG15 and zeste 2 polycomb repressive complex 2 subunit (EZH2) was testified with RNA immunoprecipitation (RIP). The promoter activity of phosphatase and tensin homolog (PTEN) was evaluated by luciferase reporter assay.
 Results: High SNHG15 expression was correlated with the poor overall survival of gastric cancer patients, and cisplatin treatment can induce time and dose-dependent up-regulation of SNHG15. At the same time, SNHG15 overexpression could promote the cisplatin resistance, while SNHG15 inhibition could diminish the cisplatin resistance. RIP assays confirmed the interaction of SNHG15 with EZH2. More importantly, SNHG15 inhibited PTEN promoter activity by reducing EZH2 recruitment in MKN45 CR cells.
 Conclusion: SNHG15 epigenetically prohibits PTEN expression by recruiting EZH2 in gastric cancer cisplatin-resistant cells.

Ginsenoside Rg3 Regulates Cisplatin Resistance in Gastric Cancer by Wnt/β-catenin Signaling Pathway

Objective To investigate the inhibitory effect of ginsenoside Rg3 combined with cisplatin (DDP) on DDP-resistant cell line SGC-7901/DDP and their molecular mechanism.Methods SGC-7901/DDP cells were divided into four groups including a control group,a ginsenoside Rg3 (40 μg/ml) treatment group,a DDP (1.40 μg/ml) treatment group,and a drug combination treatment group.The proliferation ability of SGC-7901/DDP cells was detected by MTT,EdU,and colony formation assays.The apoptosis ability of SGC-7901/DDP cell was detected by flow cytometry and Hoechst 33342 staining.The protein levels of apoptosis-related markers were detected by Western blotting.The migration ability of SGC-7901/DDP cells was detected by wound healing and Transwell assays.The expression levels of proteins in epithelial-mesenchymal transformation (EMT) and Wnt/β-catenin signaling pathway were determined by Western blotting and immunofluorescence staining.Results Compared with the ginsenoside Rg3 or the DDP treatment groups,the drug combination treatment group inhibited the proliferation (t=8.062,P=0.001;t=7.090,P=0.002),colony formation (t=8.062,P=0.001;t=6.144,P=0.004),and migration (t=7.424,P=0.002;t=4.317,P=0.013),and promoted the apoptosis (t=5.530,P=0.031;t=6.036,P=0.026) of SGC-7901/DDP cells.Compared with the ginsenoside Rg3 and the DDP treatment groups,the drug combination treatment group down-regulated the expression levels of EMT-associated proteins including vimentin (t=24.450,P<0.001;t=14.750,P<0.001),Snail (t=29.640,P<0.001;t=70.700,P<0.001),Slug (t=89.230,P<0.001;t=87.360,P<0.001),matrix metalloproteinase (MMP) 2 (t=84.540,P<0.001;t=67.120,P<0.001),and MMP9 (t=19.010,P<0.001;t=10.890,P<0.001),as well as those of Wnt/β-catenin signaling pathway related proteins including Wnt (t=35.480,P<0.001;t=14.670,P<0.001),β-catenin (t=155.800,P<0.001;t=118.100,P<0.001),C-myc (t=20.870,P<0.001;t=3.334,P=0.029),and cyclin D1 (t=5.007,P=0.008;t=8.347,P=0.001).Meanwhile,it up-regulated the expression of epithelial cells including E-cadherin (t=36.450,P<0.001;t=33.810,P<0.001) and ZO-1 (t=37.060,P<0.001;t=37.030,P<0.001).Conclusion Ginsenoside Rg3 enhanced the sensitivity of SGC-7901/DDP cells to DDP by inhibiting the activity of Wnt/β-catenin signaling pathway.

PITPNA-AS1/miR-98-5p to Mediate the Cisplatin Resistance of Gastric Cancer.

Gastric cancer (GC) is the most deadly gastrointestinal malignancy with high incidence and mortality. Although, molecular mechanisms which drive gastric cancer progression are extensively investigated, the roles of long noncoding RNA (lncRNA) in gastric cancer growth and drug sensitivity remain unclear. Platinum is a mainstay to treat gastric cancer, and platinum resistance always leads to the local recurrence of gastric cancer. Therefore, it is important to identify biomarkers or therapeutic targets to sensitize gastric cancer to platinum. In this study, we employ noncoding RNA sequencing and found that lncRNA PITPNA-AS1 is overexpressed in gastric cancer tissues and associated with poor survival of gastric cancer patients. Kockdown of PITPNA-AS1 in gastric cancer cells significantly inhibited cell growth and triggered apoptotic cell death in gastric cancer cells. Also, cisplatin treatment could decrease PITPNA-AS1 levels in gastric cancer cells through inhibiting H3K27ac. Besides, PITPNA-AS1 is elevated in cisplatin-resistant gastric cancer cells and tissues, PITPNA-AS1 knockdown could sensitize gastric cancer cells to cisplatin treatment. Furthermore, we identified that PITPNA-AS1 directly interacts and inhibits miR-98-5p. Therefore, PITPNA-AS1 could be served as a potential biomarkers and curative therapeutic targets for gastric cancer progression.

Increase in Cisplatin Resistance by MeCP2 in Human Gastric Cancer through the Activation of the AKT Pathway by Facilitating PDK-1 Transcription.

Increasing evidence indicates that an imbalance in oncogenes is implicated in cancer chemotherapy resistance. Methyl-CpG binding protein 2 (MeCP2), which acts as a major epigenetic regulator of the expression of various genes, is involved in the carcinogenesis and progression of gastric cancer. However, is it not known whether the role of MeCP2 is vital in acquired cisplatin resistance in gastric cancer. This study aimed to determine whether inhibition of MeCP2 expression could sensitize DDP-resistant GC cells to DDP and elucidate the underlying molecular mechanism. qRT-PCR and western blotting were used to evaluate MeCP2 expression in DDP-resistant GC cells. Subsequently, cell viability, colony formation, cell cycle, apoptosis, and tumorigenicity assays were performed to explore the in vitro and in vivo roles of MeCP2. Chromatin immunoprecipitation- qPCR and luciferase reporter assays were used to identify whether 3-phosphoinositide-dependent protein kinase 1 (PDK-1) was a direct target gene of MeCP2. MeCP2 was upregulated in malignant DDP-resistant cells compared to non-DDP-resistant GC cells or normal gastric epithelial cells. MeCP2 knockdown increased the sensitivity of DDP-resistant GC cells to DDP, resulting in reduced cell growth, G0/G1 phase arrest, and increased apoptosis, whereas MeCP2 overexpression attenuated DDP sensitivity of DDP-resistant GC cells. In addition, MeCP2 knockdown enhanced DDP sensitivity in vivo. MeCP2 elevated PDK-1 expression by binding to CpG sites in promoter regions, and inhibition of PDK-1 reversed the inductive effect of MeCP2 overexpression on DDP resistance in GC cells. These findings indicate that silencing of MeCP2 may potentiate DDP-induced cell death, thereby providing a promising therapeutic strategy for GC.

Polyphyllin I Inhibits Cisplatin Resistance of Cervical Cancer Cells by Inducing Mitochondrial Dysfunction and Endoplasmic Reticulum Stress

Resistance of cervical cancer to cisplatin chemotherapy compromises the therapeutic efficacy of the treatment. Polyphyllin I, a bioactive compound extracted from rhizoma of Paris polyphyllin, displays a selective inhibitory effect on a variety of tumor cells. Furthermore, it potentiates the chemosensitivity of cisplatin against cisplatin resistant gastric cancer cells and lung adenocarcinoma. However, its role in modulating chemosensitivity of cisplatin resistant cervical cancer cells remains unexplored. To this end, the repressive effect of polyphyllin I on proliferation, invasion and migration of cisplatin resistant cervical cancer cells compared to the parental cervical cancer cells as well as downregulation of mitochondrial membrane potential of cisplatin resistant cervical cancer cells, as well as upregulation of protein kinase R-like ER kinase/translation initiation factor 2-alpha kinase 3, protein-kinase and site-specific endoribonuclease/inositol-requiring enzyme 1, binding immunoglobulin protein, and C/EBP homologous transcription factor proteins. In conclusion, polyphyllin I stimulate mitochondrial dysfunction and endoplasmic reticulum stress to attenuate cisplatin resistance of cervical cancer.

Construction of a competing endogenous RNA network and identification of potential regulatory axes in gastric cancer chemoresistance

BackgroundEmerging evidence highlights the multifunctional role of noncoding RNAs (ncRNAs) in gastric cancer (GC) chemoresistance. However, the comprehensive expression profile and competing endogenous RNAs (ceRNAs) regulatory network of GC chemoresistance remain unanswered. MethodsThe whole-transcriptome sequencing (RNA sequencing) was performed to comprehensively analyze the differentially expressed (DE) lncRNAs, miRNAs and mRNAs in cisplatin-resistant cells MGC-803/DDP and GC cells MGC-803. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted to investigate the biological functions implicated with the DEncRNAs. Then, the cisplatin-resistant-related ceRNA network and potential regulatory axes were constructed by bioinformatic analysis. ResultsWe successfully generated cisplatin-resistant GC cell line MGC-803/DDP. Differential expression analysis showed that a total of 1936 DElncRNAs, 2194 DEmRNAs and 174 DEmiRNAs were identified. Functional enrichment analysis indicated that those DEncRNAs were mainly involved in neuroactive ligand-receptor interaction, drug metabolism and Hippo signaling pathway. Subsequently, the cisplatin-resistant-related ceRNA network was constructed with the widely accepted vital chemo-resistant-related genes and signaling pathways. In addition, two constructed regulatory axes (include FAM66C/miR-129–5p/7 mRNAs and SFTA1P/miR-206/FN1 or NRP1) were successfully validated by the Genomic Data Commons (GDC) GC data. ConclusionsThe novel ceRNA network and the potential regulatory axes may provide the most comprehensive view of GC chemoresistance to date. Our findings uncovered potential biomarkers for prognostic prediction and novel therapeutic targets for reversing cisplatin resistance in GC.

Functional role of the SLC7A11-AS1/xCT axis in the development of gastric cancer cisplatin-resistance by a GSH-dependent mechanism

Resistance to platinum-based chemotherapy is a major obstacle in gastric cancer (GC) treatment. Abundant long noncoding RNAs (lncRNAs) are reported to play important roles in tumorigenesis and drug resistance biology. Herein, we report that the SLC7A11-AS1 and xCT are involved in cisplatin resistance in GC. SLC7A11-AS1 was downregulated and xCT was upregulated in cisplatin-resistant GC tissues and cell lines. GC patients with low expression of SLC7A11-AS1 and high expression of xCT had a poor prognosis and relatively poor response to chemotherapy. Overexpression of SLC7A11-AS1 weakened GC growth, reduced intracellular GSH biosynthesis, enhanced intracellular reactive oxygen species (ROS) and conferred sensitivity to cisplatin to resistant GC cells in vitro and in vivo. Mechanistically, SLC7A11-AS1 directly suppressed xCT expression, while miR-33a-5p remarkably reduced SLC7A11-AS1 and xCT expression by directly targeting the SLC7A11-AS1 and xCT 3′UTRs. In addition, we found that low SLC7A11-AS1 expression activated the p38MAPK-JNK signaling pathway, and increased the expression of cisplatin export gene ATP7A and the GSH biosynthesis gene GCLM in GC.

Ginsenoside Rg3 Alleviates Cisplatin Resistance of Gastric Cancer Cells Through Inhibiting SOX2 and the PI3K/Akt/mTOR Signaling Axis by Up-Regulating miR-429.

Platinum-based cytotoxic chemotherapy is considered the standard treatment for advanced gastric cancer (GC). However, cisplatin chemoresistance often occurs with the mechanisms being not well clarified, which results in the cancer recurrence and poor survival. Ginsenoside Rg3, isolated from the Chinese Herb Panax Ginseng, is recognized as an anti-cancer agent. Herein, we aimed to reveal whether Ginsenoside Rg3 alleviates cisplatin resistance and sensitizes GC cells to cisplatin-induced apoptosis, and draw out the underlying molecular mechanism in cisplatin-resistant GC cells. The lower expression of miR-429 was found in AGSR-CDDP cells; it was also in association with cisplatin-resistance in GC cells and expression of which was restored following Ginsenoside Rg3 treatment. We also demonstrated that miR-429 made a contribution toward chemosensitivity in GC cells partly through SOX2 regulation. SOX2 was found to contribute to developing platinum resistance and was an authentic target for miR-429 in AGSR-CDDP cells. Importantly, enforced expression of SOX2 with a pcDNA3-SOX2 construct lacking the 3′-UTR miRNA binding site diminished the cytotoxic effects of miR-429 in AGSR-CDDP cells. We demonstrated that Ginsenoside Rg3 enhanced chemosensitivity in AGSR-CDDP GC cells, at least in part, through up-regulating miR-429, thereby targeting SOX2 and modulating downstream PI3K/AKT/mTOR signaling. Ginsenoside Rg3 was also found to regulate apoptosis-related genes via miR-429 in cisplatin-resistant GC cells. Ginsenoside Rg3 treatment significantly suppressed the migration rate of AGSR-CDDP GC cells, while following transfection with anti-miR-429, the anti-migratory effects of Ginsenoside Rg3 was partially abolished. This data suggested that Ginsenoside Rg3 may impede the chemoresistance and migration of GC cells mainly mediated through miR-429. We concluded that miR-429-regulated SOX2 expression was one of the main mechanisms by which Ginsenoside Rg3 dramatically promoted its anticancer effects on cisplatin-resistant GC cells. We also underscored a supporting model in which miR-429 adjusted PI3K/AKT/mTOR signaling by regulating SOX2 in cisplatin-resistant GC cells.

Circ_AKT3 knockdown suppresses cisplatin resistance in gastric cancer.

BackgroundCircular RNAs (circRNAs) are associated with cisplatin resistance in gastric cancer (GC). This study aims to explore the role of circRNA AKT serine/threonine kinase 3 (circ_AKT3) in the resistance of GC to cisplatin.Methods42 sensitive and 23 resistant GC patients were recruited for tissue collection. The cisplatin-resistant GC cells MKN-7/DDP and HGC-27/DDP were used for in vitro study. circ_AKT3, microRNA-206 (miR-206) and protein tyrosine phosphatase non-receptor type 14 (PTPN14) levels were detected via quantitative reverse transcription real-time PCR (qPCR) and Western blot. Cisplatin resistance was assessed by detecting P-glycoprotein (P-gp) level, half maximal inhibitory concentration (IC50) of cisplatin and cell apoptosis. The target relationship between miR-206 and circ_AKT3 or PTPN14 was analyzed via dual-luciferase reporter and RNA pull-down assays. The role of circ_AKT3 in vivo was assessed using xenograft model.Resultscirc_AKT3 level was increased, but miR-206 was declined in cisplatin-resistant GC tissues and cells. circ_AKT3 knockdown or miR-206 overexpression decreased the level of P-gp and IC50 of cisplatin and increased apoptosis of MKN-7/DDP and HGC-27/DDP cells. Additionally, circ_AKT3 targeted miR-206, and regulated cisplatin resistance by interacting with miR-206. PTPN14 was regulated by circ_AKT3 through miR-206 as a bridge. Also, circ_AKT3 knockdown decreased xenograft tumor growth.Conclusioncirc_AKT3 knockdown suppressed cisplatin resistance using miR-206/PTPN14 axis in cisplatin-resistant GC cells.

Linc00852 from cisplatin-resistant gastric cancer cell-derived exosomes regulates COMMD7 to promote cisplatin resistance of recipient cells through microRNA-514a-5p.

Cisplatin (DDP)-based chemotherapy is commonly referred to as advanced gastric cancer (GC). The purpose of this study was to unravel whether Linc00852 from DDP-resistant tumor cell-derived exosomes (Exos) promotes DDP resistance of GC cells. Reverse transcription quantitative polymerase chain reaction was used to detect the expression of Linc00852, miR-514a-5p, COMM domain protein 7 (COMMD7) mRNA, Bax mRNA, and Bcl-2 mRNA. Western blot was used to measure the expression of COMMD7 protein. The IC50 value of DDP is determined by MTT assay. The cell proliferation ability was measured by colony formation test. The apoptosis ability was measured by flow cytometry. The interaction between Linc00852, miR-514a-5p, and COMMD7 was confirmed by luciferase reporter gene assay and RNA pull-down assay. Xenograft tumor model was used to study the effect of Linc00852 on DDP resistance in vivo. Linc00852 was up-regulated in DDP-resistant GC cells and their secreted exosomes. Down-regulating Linc00852 facilitated the sensitivity of DDP-resistant GC cells to DDP. Linc00852 bound to miR-514a-5p and COMMD7 was a target of miR-514a-5p. Linc00852 could regulate COMMD7 expression via targeting miR-514a-5p. Exosomes from DDP-resistant GC cells enhanced the resistance of recipient GC cells to DDP via exosomal delivery of Linc00852. Depletion of Linc00852 repressed the growth and DDP resistance of GC cells in vivo. Linc00852 from DDP-resistant tumor cell-derived Exos regulates COMMD7 to promote drug resistance of GC cells through miR-514a-5p.

LncRNA LIFR-AS1 Regulated Chemoresistance of Gastric Cancer Cells through Regulating MicroRNA-138-5p-PDK1 Axis

Cisplatin represents an important strategy for gastric cancer treatment. However, cisplatin resistance often leads to failure of therapy as well as local reoccurrence. Recently, long non-coding ribonucleic acid was demonstrated to exert important roles in gastric cancer. Expression of long non-coding ribonucleic acid was measured by real time polymerase chain reaction assay in cells from different groups. Cell apoptosis was checked with Hoechst methods and cell counting kit-8 assay was used to determine cell proliferation. Bioinformatics analysis was applied to predict the target of long non-coding ribonucleic acid, which was verified in luciferase assay. We uncovered that long non-coding ribonucleic acid leukemia inhibitory factor receptor antisense RNA1 was significantly correlated to the patient survival of gastric cancer. Knockdown or overexpression of leukemia inhibitory factor receptor antisense RNA1 resulted in delayed or increased cell proliferation in gastric cancer cell lines, respectively. Moreover, in response to cisplatin treatments, cells with leukemia inhibitory factor receptor antisense RNA1 knockdown resulted in more cell apoptosis as well as less colony survival. Leukemia inhibitory factor receptor antisense RNA1 was further confirmed and bound with micro ribonucleic acid-138-5p and then regulates pyruvate dehydrogenase kinase 1 to promote gastric cancer growth. Our findings provided novel mechanism and novel targets for overcoming the cisplatin resistance of gastric cancer.