Chemosensitivity Of Gastric Cancer Cells Research Articles

MicroRNA-34a negatively regulates Netrin1 and mediates MEK/ERK pathway to regulate chemosensitivity of gastric cancer cells.

To explore the mechanism of action of MicroRNAs-34a (miR-34a) and Eurite growth guiding factor 1 (Netrin1) in cisplatin resistance in gastric cancer (GC), providing new clues for overcoming tumor resistance and optimizing anti-tumor therapy for GC. The Cancer Genome Atlas (TCGA), Differentially Expressed MicroRNAs (miRNAs) in human cancers (dbDEMC), and Starbase online databases were used to analyze the correlation between miR-34a and Netrin-1 and prognosis in GC, and to predict and verify the targeted binding of miR-34a to Netrin-1. The experimental methods including Cell transfection, real-time polymerase chain reaction (RT-PCR), Cell-Counting-Kit-8 (CCK8) assay, flow cytometry, wound scratch assay, transwell assay, and western blotting were used to investigate the effects of miR-34a and Netrin1 on chemotherapy resistance and biological characteristics in cisplatin-resistant GC cells (HGC27/DDP), and to analyze the molecular mechanism of cisplatin resistance. miR-34a expression was downregulated in gastric cancer clinical samples and cisplatin-resistant cells, while Netrin1 was upregulated, and was related to overall survival (OS). Upregulation of miR-34a can significantly reduce the IC50 value of cisplatin(0.65 vs 1.6 ng/mL) and Multidrug Resistance 1 (MDR-1) protein level, inhibit the proliferation activity, reduce the expression levels of proliferating cell nuclear antigen (PCNA) and ki-67 protein, and induce the increase of apoptosis rate and the enhancement of cycle arrest. Upregulation of miR-34a can also significantly reduce the expression level of Matrix metalloproteinase 9 (MMP9) protein, promote the expression of E-cadherin protein, reduce the wound healing rate and invasion number to inhibit migration and invasion ability in drug-resistant gastric cancer cells. Moreover, overexpression of Netrin1 on the basis of upregulation of miR-34a can weaken the above changes caused by upregulation of miR-34a. In addition, upregulation of miR-34a can significantly inhibit the Mitogen-activated protein kinase kinase (MEK) / Extracellular regulated protein kinases (ERK) pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway, and inhibition of MEK/ERK pathway can effectively counteract the protein expression of Netrin1, and reverse changes in the expression of cisplatin IC50 and MDR-1 proteins caused by co-upregulation of miR-34a/Netrin1 in HGC27/DDP, as well as changes in proliferation, apoptosis, migration and invasion. In addition, upregulation of miR-34a can significantly inhibit the MEK/ERK pathway, while overexpression of Netrin1 can activate the MEK/ERK pathway. If the MEK/ERK pathway was inhibited, it can effectively counteract the protein overexpression of Netrin1, and reverse the changes in the expression of cisplatin IC50 and MDR-1 proteins in HGC27/DDP induced by co-upregulation of miR-34a / Netrin1, as well as changes in proliferation, apoptosis, migration and invasion. miR-34a targets and negatively regulates Netrin1 to mediate the proliferation, apoptosis, apoptosis, migration, and invasion of drug-resistant gastric cancer cells via the MEK/ERK pathway, and change the chemosensitivity in GC cells. miR-34a/Netrin1/MEK/ERK axis may serve as a novel therapeutic target for chemoresistance in GC, it is of great significance for overcoming drug resistance and developing new therapeutic strategies for GC.

ARIH2 regulates the proliferation, DNA damage and chemosensitivity of gastric cancer cells by reducing the stability of p21 via ubiquitination

Ariadne homolog 2 (ARIH2) is a key member of the RING-between-RING (RBR) E3 ligase family, which is characterized by an RBR domain involved in the polyubiquitination process. However, the molecular mechanism and biological function of ARIH2 in the pathogenesis of gastric cancer remain unclear. In this paper, we found that high ARIH2 expression is correlated with poor prognosis in gastric cancer patients and that ARIH2 can significantly promote the proliferation of gastric cancer cells. The effect of ARIH2 knockdown on colony formation and tumorigenesis of gastric cancer cells was also shown both in vivo and in vitro. Further mechanistic investigations revealed that ARIH2 interacts with p21 and induces p21 ubiquitination, and that the K48 residue of ubiquitin and the K161 residue of p21 play key roles in ARIH2-mediated p21 ubiquitination. We identified ARIH2 as an E3 ligase of p21 by an in vitro ubiquitination assay. In addition, ARIH2 knockdown induced DNA damage, and then induced cell apoptosis and regulated the chemosensitivity of gastric cancer cells after combined treatment with 5-fluorouracil. Generally, our results indicated that ARIH2 promotes the proliferation of gastric cancer cells and regulates p21 expression. These data demonstrate the need to further evaluate the potential therapeutic implications of ARIH2 in gastric cancer.

Retraction notice to Downregulation of MicroRNA-147 Inhibits Cell Proliferation and Increases the Chemosensitivity of Gastric Cancer Cells to 5-Fluorouracil by Directly Targeting PTEN [Oncology Research 26(6) (2018) 901-911

Retraction notice to Downregulation of MicroRNA-147 Inhibits Cell Proliferation and Increases the Chemosensitivity of Gastric Cancer Cells to 5-Fluorouracil by Directly Targeting PTEN [Oncology Research 26(6) (2018) 901-911

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.

Revealing the Role of lncRNA CCDC144NL-AS1 and LINC01614 in Gastric Cancer via Integrative Bioinformatics Analysis and Experimental Validation.

Long non-coding RNAs (lncRNAs) are key regulators in the pathophysiology of gastric cancer, and lncRNAs have been regarded as potential biomarkers and therapeutic targets for gastric cancer. The present study performed the WGCNA analysis of the GSE70880 dataset and aimed to identify novel lncRNAs associated with gastric cancer progression. Based on the WGCNA, the lncRNAs and mRNA co-expression network were constructed. A total of four modules were identified and the eigengenes in different modules were involved in various key signaling pathways. Furthermore, the co-expression networks were constructed between the lncRNAs and mRNA; this leads to the identification of 6 modules, which participated in various cellular pathways. The survival analysis showed that high expression of CCDC144NL antisense RNA 1 (CCDC144NL-AS1) and LINC01614 was positively correlated with the poor prognosis of patients with gastric cancer. The in vitro validation results showed that CCDC144NL-AS1 and LINC01614 were both up-regulated in the gastric cancer cells. Silence of CCDC144NL-AS1 and LINC01614 both significantly suppressed the cell proliferation and migration of gastric cancer cells, and also promoted the chemosensitivity of gastric cancer cells to 5-fluorouracil. Collectively, our results suggested that the newly identified two lncRNAs (CCDC144NL-AS1 and LINC01614) may act as oncogenes in gastric cancer.

Erratum

Gastric cancer is the fourth most common malignancy and the third leading cause of cancer-related deaths worldwide. This study aimed to investigate the expression patterns, biological roles, and underlying mechanisms of microRNA-147 (miR-147) in gastric cancer. The present study demonstrated that miR-147 was significantly upregulated in gastric cancer tissues and cell lines. Downregulation of miR-147 decreased cell proliferation and enhanced the chemosensitivity of gastric cancer cells to 5-fluorouracil (5-FU) through the cell apoptosis pathway. In addition, phosphatase and tensin homolog (PTEN) was mechanically identified as the direct target of miR-147 in gastric cancer. PTEN knockdown reversed the effects of miR-147 downregulation on the proliferation, chemosensitivity, and 5-FU-induced apoptosis of gastric cancer cells. Moreover, miR-147 regulated the PI3K/AKT signaling pathway in gastric cancer by targeting PTEN. In conclusion, miR-147 suppressed the proliferation and enhanced the chemosensitivity of gastric cancer cells to 5-FU by promoting cell apoptosis through directly targeting PTEN and regulating the PI3K/AKT signaling pathway. This study provides important insight into the molecular mechanism that underlies the chemoresistance of gastric cancer cells. The results of this study could aid the development of a novel therapeutic strategy for gastric cancer.

Long Noncoding RNA KLF3-AS1 Acts as an Endogenous RNA of miR-223 to Attenuate Gastric Cancer Progression and Chemoresistance.

Gastric cancer is a deadly disease, and the low rate of early diagnosis and chemoresistance largely contributed to the poor prognosis of gastric cancer. LncRNAs have been extensively reported for their roles in regulating cancer progression. In this study, we found that KLF3-AS1 was down-regulated in gastric cancer cells. Overexpression of KLF3-AS1 repressed gastric cancer cell proliferation, growth. In addition, KLF3-AS1 overexpression also exerted inhibitory effects on the gastric cancer cell invasion, migration and EMT, but promoted chemosensitivity of gastric cancer cells to cisplatin. The mechanistic studies showed that KLF3-AS1 could act as the “sponge” for miR-223 and to repress miR-223 expression in gastric cancer cells. Overexpression of miR-223 reversed the inhibitory effects of KLF3-AS1 overexpression on gastric cancer cell proliferation, invasion, migration and EMT, and attenuated the enhanced effects of KLF3-AS1 overexpression on gastric cancer cell chemosensitivity to cisplatin. The in vivo studies showed that KLF3-AS1 overexpression suppressed the tumor growth of SGC-7901 in the nude mice. In conclusion, our results for the first time demonstrated that KLF3-AS1 was down-regulated in gastric cancer cells and repressed gastric cancer cell proliferation, invasion, migration and EMT, and enhanced chemosensitivity to cisplatin. Further mechanistic results indicated that KLF3-AS1 exerted its biological function in gastric cancer cells by inhibiting miR-223 expression. Future studies are still required to decipher the detailed molecular mechanisms of KLF3-AS1 in gastric cancer.

Retinoblastoma tumor suppressor gene 1 enhances 5-Fluorouracil chemosensitivity through SDF-1/CXCR4 axis by regulating autophagy in gastric cancer

Due to lack of effective biomarkers for early diagnosis, most patients are diagnosed with advanced gastric cancer and have lower survival rates. 5-Fluorouracil (5-FU) is one of commonly used drugs for chemotherapy of gastric cancer, but drug resistance limits the wide application of agents. Retinoblastoma tumor suppressor gene 1 (RB1) is a key regulator in the progression of various human cancers, including gastric cancer. However, the effects of RB1 on chemosensitivity and the underlying mechanisms in gastric cancer (GC) are not clear. In this study, expressions of RB1 in GC cell lines were evaluated by RT-qPCR and western blot assay. CCK-8 was applied to examine the effect of 5-FU on cell viability. Meanwhile, IC50 values were calculated. The drug-resistance protein MDR1 and autophagy-related proteins were detected by western blot assay. Flow cytometry was used to detect cell cycle. The results showed that RB1 expressions were downregulated in GC cell lines and had significant differences between 5-FU resistance cell lines (SNU-620/5-FU and NUGC-3/5-FU) and non-resistance cell lines (SNU-620 and NUGC-3). Overexpression of RB1 enhanced 5-FU sensitivity of GC cells and caused cell cycle arrest in the S phase. Meanwhile, autophagy-related proteins were downregulated. Mechanistically, SDF-1/CXCR4 participated in the regulation of RB1 on cell autophagy. Autophagy activator, SDF-1 treatment and CXCR4 activation reversed the promoted effects of RB1 on 5-FU sensitivity in GC cells. In conclusion, our data revealed that RB1 was downregulated in GC cell lines. RB1 overexpression enhanced 5-FU chemosensitivity in GC cells by regulating cell autophagy via SDF-1/CXCR4 pathway. RB1 might serve as a promising therapeutic target of GC.

The effects and mechanism of α-mangostin on chemosensitivity of gastric cancer cells.

This work investigated the effect of α-mangostin (α-M) on gastric cancer (GC) cell chemoresistance and its underlying mechanisms. Different concentrations of α-M and CDDP were applied to treat GC cells (SGC7901) and CDDP-resistant GC cells (SGC7901/CDDP) for 24 or 48 h. CCK-8 assays were used to measure the inhibitory effect of CDDP or α-M on SGC7901 and SGC7901/CDDP cells as well as the half-maximal inhibitory concentrations (IC50) of α-M for SGC7901 and SGC7901/CDDP cells. The optimal concentration and induction time of CDDP or α-M were determined. SGC7901/CDDP cells were treated with CDDP or/and α-M, where some of them were transfected with pcDNA3.1 or pcDNA3.1-EBI3. Cell proliferation and apoptosis were assessed as well as the levels of EBI3, STAT3, p-STAT3, autophagy-related proteins, and apoptosis-related proteins. CDDP inhibited SGC7901 cell proliferation in a dose-dependent manner. The IC50 of α-M for SGC7901 cells was 12.86 μM and that for SGC7901/CDDP cells was 13.69 μM. The optimal concentrations of CDDP and α-M for SGC7901/CDDP cells were 2 and 15 μM, respectively, and the optimal time was 48 h. The SGC7901/CDDP cells in the CDDP+/α-M+ group had elevated inhibition of proliferation and apoptosis rates. Western blot analysis revealed enhanced levels of LC3-II/I and Beclin1, reduced p62 level, decreased Bcl2 level, and increased levels of Bax and cleaved caspase-3/9. The EBI3/STAT3 pathway was implicated in the effect of α-M on SGC7901/CDDP cell development. α-M increases the chemosensitivity of GC cells by facilitating autophagy and inactivating the EBI3/STAT3 pathway.

SPARC enhances 5-FU chemosensitivity in gastric cancer by modulating epithelial-mesenchymal transition and apoptosis

Previous studies have shown that secreted protein acidic and rich in cysteine (SPARC) proteins can inhibit the development of cancer cells in various ways, such as by inhibiting angiogenesis and inhibiting cell proliferation. In fact, SPARC proteins may have an effect on the chemoresistance of gastric cancer cells to 5-Fluorouracil (5-FU), which needs further research in the future. Therefore, the purpose of this study was to explore the relationship between SPARC proteins and the chemosensitivity of gastric cancer cells to 5-FU. In vitro, after SPARC protein levels were regulated by plasmid, siRNA and human recombinant SPARC protein transfection in MGC-803, SGC-7901 and BGC-823 cells, we detected epithelial-mesenchymal transition (EMT), apoptosis markers and cell viability after 5-FU treatment. In vivo, we implanted BGC-823 cells with stable SPARC overexpression into nude mice. Tumour size was measured to assess the effect of SPARC protein on tumour formation and 5-FU chemosensitivity. In SGC-7901 and BGC-823 cells, both endogenous and exogenous upregulation of SPARC protein levels decreased cell viability, destroyed cytoskeletal F-actin, inhibited cell migration, and downregulated a series of transcription factors to inhibit cell EMT; it also upregulated cell apoptosis-related proteins to promote cell apoptosis. However, we obtained opposite results in SPARC knockdown MGC-803 cells. In vivo, compared with the control group, the group engrafted with BGC-823 cells stably overexpressing SPARC had a significant smaller tumour size. After 5-FU treatment, the new tumour gradually decreased in size. Our results show that the SPARC protein could enhance 5-FU chemosensitivity in gastric cancer cell lines by inhibiting EMT and promoting cell apoptosis.

Omeprazole improves chemosensitivity of gastric cancer cells by m6A demethylase FTO-mediated activation of mTORC1 and DDIT3 up-regulation.

The curative effect for patients with advanced gastric cancer is still unsatisfactory. Proton pump inhibitors could be a promising treatment strategy that could sensitize gastric cancer cells to antitumor drugs further; however, the underlying molecular mechanism remains to be further elucidated. In this research, it was found that omeprazole pretreatment could enhance the inhibitory effect of 5-Fu, DDP and TAX on gastric cancer cells. Interestingly, omeprazole pretreatment enhanced the total m6A level of cells due to the decreased FTO. TCGA analysis showed that FTO expression is up-regulated in GC tissues and is negatively correlated with disease-free survival of GC patients. It was also found that FTO inhibition induced by omeprazole enhanced the activation of mTORC1 signal pathway that inhibited the prosurvival autophagy so as to improve the antitumor efficiency of chemotherapeutic drugs on GC cells. Meanwhile, transcript level of DDIT3, which is an apoptosis-related tumor suppressor gene downstream of mTORC1, was regulated by omeprazole-induced FTO silence through an m6A-dependent mechanism. The present study, for the first time, found that m6A modification and its eraser FTO may play a role in the improvement of chemosensitivity mediated by proton pump inhibitor omeprazole.

Bruceine D inhibits Cell Proliferation Through Downregulating LINC01667/MicroRNA-138-5p/Cyclin E1 Axis in Gastric Cancer

Objective: Gastric cancer is one of the most common malignant tumors. Bruceine D (BD) is one of the extracts of Brucea javanica. In recent years, it has been reported that BD has anti-tumor activity in some human cancers through different mechanisms. Here, this study try to explore the effect of BD on gastric cancer and its regulatory mechanism. Methods: Cell proliferation ability was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays, 5-bromo-2-deoxyuridine (BrdU) staining and soft agar colony formation assay, respectively. The tumor xenograft model was used to verify the effect of BD on the tumorigenicity of gastric cancer cells in vivo. Flow cytometry analysis and Western blot assay were performed to detect cell cycle and apoptosis. Gastric cancer cells were analyzed by transcriptome sequencing. The interaction between LINC01667, microRNA-138-5p (miR-138-5p) and Cyclin E1 was verified by dual luciferase experiment and RT-PCR assays. Results: We found that BD significantly inhibited cell proliferation and induced cell cycle arrest at S phase in gastric cancer cells. Transcriptome analysis found that the expression of a long non-coding RNA, LINC01667, were significantly down-regulated after BD treatment. Mechanically, it was discovered that LINC01667 upregulated the expression of Cyclin E1 by sponging miR-138-5p. Furthermore, BD enhanced the chemosensitivity of gastric cancer cells to doxorubicin, a clinically used anti-cancer agent. Conclusion: BD inhibit the growth of gastric cancer cells by downregulating the LINC01667/miR-138-5p/Cyclin E1 axis. In addition, BD enhances the chemosensitivity of gastric cancer cells to doxorubicin. This study indicates that BD may be used as a candidate drug for the treatment of patients with gastric cancer.

Knockdown of PDIA6 Inhibits Cell Proliferation and Enhances the Chemosensitivity in Gastric Cancer Cells.

BackgroundProtein disulfide isomerase A6 (PDIA6), a member of the disulfide isomerase (PDI) family, has been reported to be closely associated with progression of various cancers. However, the specific effects of PDIA6 on gastric cancer (GC) remain unclear. In this study, we investigated the expression pattern and biological functions of PDIA6 in GC.Materials and MethodsThe CCK-8 assay was carried out to examine cell proliferation and cisplatin cytotoxicity. The Western blot analysis was used to measure the protein expression of PDIA6, Wnt3a and β-catenin. The xenograft tumor assay was performed to evaluate the in vivo effect of PDIA6 on GC cell proliferation and chemoresistance.ResultsPDIA6 was significantly elevated in GC tissues and cell lines. Down-regulation of PDIA6 inhibited GC cell proliferation and chemoresistance to cisplatin while up-regulation of PDIA6 promoted the proliferation and chemoresistance of GC cells. Besides, PDIA6 regulated the chemosensitivity of GC cells to cisplatin in vivo. Mechanically, PDIA6 served as a regulator of the Wnt/β-catenin signaling pathway by affecting the protein expression of Wnt3a and β-catenin in GC cells. Additionally, Wnt activator reversed the inhibitory effect of PDIA6 knockdown on cisplatin resistance in GC cells.ConclusionThese findings provided new insight into the potential role of PDIA6 as a promising target for drug resistance in GC chemotherapy.

Esomeprazole affects the proliferation, metastasis, apoptosis and chemosensitivity of gastric cancer cells by regulating lncRNA/circRNA-miRNA-mRNA ceRNA networks.

Recently, proton pump inhibitors have become a hot research topic in the field of cancer drug research. However, the specific anti-tumor effect and underlying mechanisms of esomeprazole (ESO) in gastric cancer (GC) have remained elusive. In the present study, the toxic effects of ESO on the GC cell line AGS were investigated. MTT assays confirmed that ESO inhibited the proliferation of AGS cells and significantly enhanced their chemosensitivity. Transwell assays were performed to determine the anti-metastatic effects of ESO in AGS cells. Flow cytometry demonstrated that ESO induced cell apoptosis and caused cell cycle arrest in the S and G2/M phases. Furthermore, the differential expression of 948 long non-coding RNAs (lncRNAs), 114 circular RNAs (circRNAs), 1,197 mRNAs and 199 microRNAs (miRNAs) was detected in AGS cells via microarray analysis and RNA-sequencing. The top 10 differently expressed genes were mostly located on chromosomes 10 and 19. In addition, Gene Ontology analysis indicated that the genes were accumulated in functional terms associated with DNA replication, the cell cycle and the apoptotic signaling pathway. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed a variety of significantly dysregulated signaling pathways and targets, including the EGFR tyrosine kinase inhibitor resistance pathway, forkhead box O signaling pathway, p53 signaling pathway and platinum drug resistance pathway. Subsequently, the interactions of microtubule-associated protein 2 (MAP2), homeodomain-interacting protein kinase 2 (HIPK2) and ankyrin 2 (ANK2) were noted in a competing endogenous RNA (ceRNA) network, which may be important targets of ESO, exerting an anti-tumor effect in AGS cells. Collectively, ESO affects the proliferation, metastasis, apoptosis and chemosensitivity of gastric cancer cells by regulating long non-coding RNA/circRNA-miRNA-mRNA ceRNA networks.

Bmi-1-induced miR-27a and miR-155 promote tumor metastasis and chemoresistance by targeting RKIP in gastric cancer

BackgroundWe previously reported an inverse relationship between B cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) and Raf kinase inhibitory protein (RKIP), which is associated with the prognosis of gastric cancer (GC). In this study, we further explored the microRNA (miRNA) regulatory mechanism between Bmi-1 and RKIP.MethodsMicroarray analysis was first carried out to identify miRNA profiles that were differentially expressed in cells overexpressing Bmi-1. Then, miRNAs that could regulate RKIP were identified. Quantitative real-time PCR (qRT-PCR) and Western blotting were performed to measure the expression of Bmi-1, miR-155, miR-27a and RKIP. RKIP was confirmed as a target of miR-27a and miR-155 through luciferase reporter assays, qRT-PCR and Western blotting. The effects of the Bmi-1/miR-27a/RKIP and Bmi-1/miR-155/RKIP axes on tumor growth, proliferation, migration, invasion, colony-formation ability, metastasis and chemoresistance were investigated both in vitro and in vivo.ResultsThe downregulation of RKIP by Bmi-1 occurred at the protein but not mRNA level. This indicates probable posttranscriptional regulation. miRNA expression profiles of cells with ectopic expression of Bmi-1 were analyzed and compared to those of control cells by microarray analysis. A total of 51 upregulated and 72 downregulated miRNAs were identified. Based on publicly available algorithms, miR-27a and miR-155 were predicted, selected and demonstrated to target RKIP. Bmi-1, miR-27a and miR-155 are elevated in human GC and associated with poor prognosis of GC, while RKIP is expressed at lower levels in GC and correlated with good prognosis. Then, in vitro tests shown that in addition to regulating RKIP expression via miR-27a and miR-155, Bmi-1 was also able to regulate the migration, invasion, proliferation, colony-formation ability and chemosensitivity of GC cells through the same pathway. Finally, the in vivo test showed similar results, whereby the knockdown of the Bmi-1 gene led to the inhibition of tumor growth, metastasis and chemoresistance through miR-27a and miR-155.ConclusionsBmi-1 was proven to induce the expression of miR-27a and miR-155 and thus promote tumor metastasis and chemoresistance by targeting RKIP in GC. Overall, miR-27a and miR-155 might be promising targets for the screening, diagnosis, prognosis, treatment and disease monitoring of GC.

H19/miR-152-3p/TCF4 axis increases chemosensitivity of gastric cancer cells through suppression of epithelial-mesenchymal transition.

BackgroundAdriamycin (ADM) is a drug commonly used for treating gastric cancer (GC). However, chemoresistance presents an obstacle to achieving successful outcomes in patients treated with chemotherapy. This study aimed to explore the effect of long non-coding RNA (lncRNA) H19 on chemoresistance in GC and its potential molecular mechanism.MethodsThe expression of H19 was detected in GC tissues and cell lines. The interaction between miR-152 with H19 and transcription factor 4 (TCF4) was validated by luciferase reporter assay. CCK-8 and flow cytometry were employed to measure cell viability and apoptosis, respectively. The levels of epithelial-mesenchymal transition (EMT) markers (E-cadherin, N-cadherin, Slug, Snail, and Twist) were detected by Western blot assay. A mouse model was established by subcutaneously injecting MGC-803 cells stably transfected with sh-H19 to investigate the effect of H19/miR-152-3p/TCF4 axis on ADM in vivo.ResultsIn vitro, we observed that H19 was overexpressed in GC tissues and cell lines. After knockdown of H19, the IC50 of ADM was decreased and cell apoptosis rates increased in both BGC-823ADM and MGC-803ADM cells. Furthermore, H19 shRNA was found to inhibit epithelial-mesenchymal transition (EMT), and induction of EMT counteracted the inhibitory effect of H19 shRNA on chemoresistance of GC cells. miR-152 was a target of H19, and its expression was downregulated in GC tissues and cell lines. Furthermore, the expression of TCF4 was negatively regulated by miR-152 but positively regulated by H19. In vivo, the data indicated that H19 shRNA enhanced the chemosensitivity of GC tumor cells to ADM through sponging miR-152 from TCF4, resulting in the suppression of EMT.ConclusionsThe results of this study elucidated that H19 was overexpressed in GC tissues and cell lines, and knockdown of lncRNA H19 increased the chemosensitivity of GC cells to ADM via sponging miR-152 from TCF4. The H19/miR-152/TCF4 axis may provide a new perspective for treating GC.

CLDN4 silencing promotes proliferation and reduces chemotherapy sensitivity of gastric cancer cells through activation of the PI3K/Akt signalling pathway.

What is the central question of this study? What is the influence of the interaction between the matrix protein CLDN4 and the PI3K/Akt signalling pathway on tumour progression and chemotherapy sensitivity in gastric cancer? What is the main finding and its importance? Silencing of CLDN4 can promote the growth and proliferation of gastric cancer cells by activating the PI3K/Akt signalling pathway, and thus reduce the sensitivity of gastric cancer cells to chemotherapy. Gastric cancer (GC) is one of the most common cancers worldwide and has a high mortality rate, accompanied by metastasis. Claudins (CLDNs) are major tight-junction proteins that mediate cellular polarity and differentiation. In the present study, we investigated the role of claudin 4 (CLDN4) in modulating cell proliferation and chemotherapeutic sensitivity in GC. Immunohistochemistry and RT-qPCR were initially used to detect the expression of CLDN4 in cancer tissues and adjacent normal tissues collected from GC patients. GC cell lines with the highest and the lowest CLDN4 expression were selected for subsequent experiments. The effects of CLDN4 on GC cell chemosensitivity, proliferation, invasion, migration, apoptosis and tumourigenic capacity were evaluated by conducting gain- and loss-of-function studies of CLDN4. Expression of CLDN4 was significantly decreased in GC tissues and cell lines compared to adjacent normal tissues or gastric epithelial cells. Silencing of CLDN4 increased the extent of PI3K and Akt phosphorylation, and also the proliferation, migration, invasion and tumourigenesis of GC cells; at the same time apoptosis and the sensitivity of GC cells to chemotherapy were reduced. In conclusion, CLDN4 may play a pivotal role in attenuating GC cell proliferation and enhancing sensitivity of GC cells to chemotherapy by inactivating the PI3K/Akt signalling pathway.

The Influence of Bcl-3 Expression on Cell Migration and Chemosensitivity of Gastric Cancer Cells via Regulating Hypoxia-Induced Protective Autophagy.

PurposeGastric cancer is a highly metastatic malignant tumor, often characterized by chemoresistance and high mortality. In the present study, we aimed to investigate the role of B-cell lymphoma 3 (Bcl-3) protein on cell migration and chemosensitivity of gastric cancer.Materials and MethodsThe gastric cancer cell lines, AGS and NCI-N87, were used for the in vitro studies and the in vivo studies were performed using BALB/c nude mice. Western blotting, wound healing assay, Cell Counting Kit-8 assay, immunohistochemistry, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay were used to evaluate the role of Bcl-3 in gastric cancer.ResultsWe found that the protein expression of hypoxia (HYP)-inducible factor-1α and Bcl-3 were markedly upregulated under hypoxic conditions in both AGS and NCI-N87 cells in a time-dependent manner. Interestingly, small interfering RNA-mediated knockdown of Bcl-3 expression affected the migration and chemosensitivity of the gastric cancer cells. AGS and NCI-N87 cells transfected with si-RNA-Bcl-3 (si-Bcl-3) showed significantly reduced migratory ability and increased chemosensitivity to oxaliplatin, 5-fluorouracil, and irinotecan. In addition, si-Bcl-3 restored the autophagy induced by HYP. Further, the protective role of si-Bcl-3 on the gastric cancer cells could be reversed by the autophagy inducer, rapamycin. Importantly, the in vivo xenograft tumor experiments showed similar results.ConclusionsOur present study reveals that Bcl-3 knockdown inhibits cell migration and chemoresistance of gastric cancer cells through restoring HYP-induced autophagy.

Enhancing the chemotherapy effect of Apatinib on gastric cancer by co-treating with salidroside to reprogram the tumor hypoxia micro-environment and induce cell apoptosis

Hypoxic microenvironment commonly occurred in the solid tumors considerably decreases the chemosensitivity of cancer cells. Salidroside (Sal), the main active ingredient of Rhodiola rosea, was shown to be able of regulating the tumor hypoxia micro-environment and enhancing the chemotherapeutic efficacy of drug-resistant cancer. Therefore, in this study, the Sal was co-loaded with Apatinib (Apa) by the PLGA-based nanoparticles (NPs) to improve the chemosensitivity of gastric cancer cells. Additionally, to improve the drug delivery efficacy, the tumor-homing peptide (iVR1 peptides) was further decorated on the surface of NPs. The tumor targeting ability of the peptides-functionalized nanoparticles (iVR1-NPs-Apa/Sal) was evaluated by in vitro and in vivo experiments. As the obtained results revealed that the iVR1-NPs-Apa/Sal displayed excellent tumor affinity than the unmodified ones (NPs-Apa/Sal), which in turn resulted in more efficient of anti-proliferation of gastric cancer cells and anti-tumor effect in vivo. In addition, compared with the cells or tumor-bearing mice only treaded by monotherapy of Apa, the cells or mice received combinational treatment of Apa and Sal showed obvious lower rate of growth, invasion, and migration or tumor growth and progress. Underlying mechanisms were further investigated and it was revealed that the anti-gastric cancer effect of Apa was signally improved by Sal through down-regulation the proliferation factors and increase the pro-apoptotic genes, as well as reprograming the tumor hypoxia micro-environment. In a word, the study showed that the Sal was able of improving the chemosensitivity of gastric cancer to Apa and the iVR1-NPs-Apa/Sal was capable of realizing highly efficient of tumor-targeting drug delivery.

Activation of LXRβ inhibits proliferation, promotes apoptosis, and increases chemosensitivity of gastric cancer cells by upregulating the expression of ATF4.

Recently, great advances have been achieved in both surgery and chemotherapy for the treatment of gastric cancer, but there is still poor prognosis for this disease. The aim of this study is to investigate the role of liver X receptor β (LXRβ) in chemosensitivity of gastric cancer SGC7901 cells. From 171 patients with gastric cancer, the gastric cancer and paracancerous tissues were selected to measure the expression of LXRβ and ATF4. Gastric cancer cell lines were cultured and screened to figure out the proliferation and apoptosis of gastric cancer SGC7901 cells with the treatment of LXRβ agonist (GW3965), ATF4 short hairpin RNA (shRNA), and chemotherapy drug paclitaxel. The expression of apoptosis-related gene cleaved caspase-3 was detected by Western blot analysis. First, we found that the expressions of LXRβ and ATF4 in gastric cancer tissues and cells were significantly lower than those in their paracancerous tissues and gastric mucosal epithelial cells. In addition, activation of LXRβ and paclitaxel treatment suppressed proliferation of SGC7901 cells, and the expression of ATF4 was upregulated in a concentration-dependent manner. Furthermore, shRNA significantly inhibited the expression of ATF4 and blocked the chemosensitivity of SGC7901 cells to LXRβ activation. Our study demonstrates that the expression of LXRβ was low in gastric cancer. In addition, activation of LXRβ may inhibit the proliferation of gastric cancer cells, promote apoptosis, and increase chemosensitivity by upregulating the expression of ATF4.