Cisplatin-resistant Gastric Cancer Research Articles

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.

Study on the Mechanism of Action of STAT3 in the Drug Resistance of Gastric Cancer Cells.

Gastric cancer is the most common digestive tract malignancy in China and has a poor prognosis, with a 5-year overall survival rate of only 35.1%. Because its early symptoms are not obvious and early diagnosis is complicated, there is an urgent need to find biological targets for diagnosis and treatment. This research detected the expression of STAT3 in gastric cancer tissues and adjacent tissues by Western blot and immunohistochemical experiments and conducted corresponding basic experiments to explore the role of STAT3 in inhibiting the proliferation of cisplatin-resistant gastric cancer cells and promoting their apoptosis, including the construction of cisplatin-resistant gastric cancer cell line, the knock-out STAT3 in drug-resistant gastric cancer cells by CRISPR-Cas9, and the comparison of the proliferation and apoptosis of drug-resistant cells and drug-resistant cells STAT3(-). The mechanism provides a possible intervention target for clinically improving the prognosis of patients with cisplatin-resistant gastric cancer.

CircARVCF Contributes to Cisplatin Resistance in Gastric Cancer by Altering miR-1205 and FGFR1.

Background: Chemoresistance is a major barrier to the treatment of human cancers. Circular RNAs (circRNAs) are implicated in drug resistance in cancers, including gastric cancer (GC). In this study, we aimed to explore the functions of circRNA Armadillo Repeat gene deleted in Velo-Cardio-Facial syndrome (circARVCF) in cisplatin (DDP) resistance in GC. Methods: The expression of circARVCF, microRNA-1205 (miR-1205) and fibroblast growth factor receptor 1 (FGFR1) was detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot assay or immunohistochemistry (IHC) assay. Cell Counting Kit-8 (CCK-8) assay and colony formation assay were performed to evaluate DDP resistance and cell colony formation ability. Transwell assay was conducted to assess cell migration and invasion. Flow cytometry analysis was done to analyze cell apoptosis. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were manipulated to analyze the relationships of circARVCF, miR-1205 and FGFR1. Murine xenograft model was constructed to explore DDP resistance in vivo. Results: CircARVCF level was increased in DDP-resistant GC tissues and cells. CircARVCF silencing inhibited DDP resistance, colony formation and metastasis and induced apoptosis in DDP-resistant GC cells. CircARVCF directly interacted with miR-1205 and miR-1205 inhibition reversed circARVCF silencing-mediated effect on DDP resistance in DDP-resistant GC cells. FGFR1 served as the target gene of miR-1205. MiR-1205 overexpression restrained the resistance of DDP-resistant GC cells to DDP, but FGFR1 elevation abated the effect. In addition, circARVCF knockdown repressed DDP resistance in vivo. Conclusion: CircARVCF enhanced DDP resistance in GC by elevating FGFR1 through sponging miR-1205.

Targeting Oncogenic miR-181a-2-3p Inhibits Growth and Suppresses Cisplatin Resistance of Gastric Cancer.

PurposeThis study aimed to explore the value of miR-181a-2-3p in cisplatin (DDP) treatment effectiveness prediction, and to reveal the function underlying the reversal of DDP resistance in patients with gastric cancer (GC).MethodsmiRNA expression dataset of three DDP-resistant GC cell lines and their DDP-sensitive parental cell lines obtained from GEO DataSets and GenBank, and functional miRNAs were annotated by bioinformatics analyses. Serum specimens and tumor samples were collected from 91 GC patients for understanding of the interrelation between chemotherapy response and miRNA expression. RT-qPCR validated these miRNAs at the transcriptional level in both gastric cancer cells and 91 gastric cancer patients. The correlation between the miRNAs expression and clinical parameters of the patients were analyzed. Receiver operating characteristics (ROC) analysis has been utilized to assess the diagnostic performance. The MTT and colony formation assays were performed to assess cell proliferation. Flow cytometry was conducted to detect cell apoptosis. DDP-resistant GC cells and their DDP-sensitive parental cells were transfected with miRNA mimic or inhibitor vector to overexpress or downregulate miRNA expression.ResultsmiR-181a-2-3p as a unique miRNA was found in the common differentially expressed-miRNAs (DE-miRNAs) after miRNA screening and validation from three DDP-resistant and DDP-sensitive gastric cancer cell lines. Clinical data analysis displayed that miR-181a-2-3p expression was apparently increased in larger tumor size (≥5 cm), higher T stage (T4), and chemotherapy resistance. miR-181a-2-3p (AUC=0.926, SE=0.028, 95% CI: 0.872–0.980, p< 0.0001) differentiated chemosensitive GC patients from chemoresistant GC patients. miR-181a-2-3p presented a higher level in gastric cancer, and could serve as a valid biomarker to predict the overall survival of GC patients. Upregulation of miR-181a-2-3p rendered the apoptosis-inducing and anti-proliferative effects of DDP, while downregulating it decreased these effects.ConclusionmiR-181a-2-3p can function as a therapeutic target and a tumor biomarker. Targeting oncogenic miR-181a-2-3p inhibits growth and suppresses cisplatin resistance of gastric cancer.

Transfer of LncRNA CRNDE in TAM-derived exosomes is linked with cisplatin resistance in gastric cancer.

This study explores the role of the long noncoding RNA (LncRNA) CRNDE in cisplatin (CDDP) resistance of gastric cancer (GC) cells. Here, we show that LncRNA CRNDE is upregulated in carcinoma tissues and tumor-associated macrophages (TAMs) of GC patients. In vitro experiments show that CRNDE is enriched in M2-polarized macrophage-derived exosomes (M2-exo) and is transferred from M2 macrophages to GC cells via exosomes. Silencing CRNDE in M2-exo reverses the promotional effect of M2-exo on cell proliferation in CDDP-treated GC cells and homograft tumor growth in CDDP-treated nude mice. Mechanistically, CRNDE facilitates neural precursor cell expressed developmentally downregulated protein 4-1 (NEDD4-1)-mediated phosphatase and tensin homolog (PTEN) ubiquitination. Silencing CRNDE in M2-exo enhances the CDDP sensitivity of GC cells treated with M2-exo, which is reduced by PTEN knockdown. Collectively, these data reveal a vital role for CRNDE in CDDP resistance of GC cells and suggest that the upregulation of CRNDE in GC cells may be attributed to the transfer of TAM-derived exosomes.

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

ObjectiveCisplatin (DDP) treatment is one of the most predominant chemotherapeutic strategies for patients with gastric cancer (GC). LncRNA noncoding RNA HLA complex group 11 (lncRNA HCG11) has been confirmed to promote GC progression. This study attempted to investigate the underlying molecular mechanism of HCG11 in DDP resistance of GC.MethodsqRT-PCR was performed to evaluate the expression of HCG11, microRNA-144-3p (miR-144-3p), and ubiquitin-conjugating enzyme E2 D1 (UBE2D1) in GC. The correlation between HCG11 and clinicopathological features of GC patients was assessed. DDP-resistant GC cells and their parental cells were cultured in different concentrations of DDP. The role of HCG11 for the viability and the half maximal inhibitory concentration (IC50) of DDP in DDP-resistant GC cells was determined by MTT assay. Then, the invasion of DDP-resistant GC cells was measured by transwell assay. Next, a dual-luciferase reporter assay was used to confirm the interactions among HCG11, miR-144-3p, and UBE2D1 in GC.ResultsThe expression of HCG11 and UBE2D1 was elevated in tumor tissues of GC patients, but miR-144-3p was declined. HCG11 expression was elevated in DDP-resistant GC patients and is strongly correlated with DDP sensitivity and World Health Organization grade in GC patients. HCG11 knockdown reduced the viability, IC50 of DDP, and invasion of DDP-resistant GC cells. Additionally, HCG11 targeted miR-144-3p and miR-144-3p further targeted UBE2D1. Feedback experiments indicated that low expression of miR-144-3p or overexpression of UBE2D1 mitigated the inhibitory effect of HCG11 depletion on DDP resistance of GC cells.ConclusionHCG11 knockdown attenuated DDP resistance of GC cells through via miR-144-3p/UBE2D1 axis, affording a novel therapeutic strategy for GC.

EGR1-CCL2 Feedback Loop Maintains Epithelial-Mesenchymal Transition of Cisplatin-Resistant Gastric Cancer Cells and Promotes Tumor Angiogenesis.

The mechanism of cisplatin resistance in gastric cancer (GC) is still elusive; several recent evidences proposed that chemoresistant tumor cells acquired aggressive behaviors. This study was aimed to investigate the mechanism of epithelial-mesenchymal transition (EMT) and angiogenesis in chemoresistant GC. Bioinformatics analysis and function or mechanism experiments including RT-qPCR, immunofluorescence, Western blot, luciferase reporter assay, Chromatin immunoprecipitation, Chicken chorioallantoic membrane assay and animal experiments were applied to evaluate the role of EGR1-CCL2 feedback loop. Compared with the parental cell line SGC7901, cisplatin resistant SGC7901R cells underwent EMT and showed increased angiogenic capabilities. Mechanistically, SGC7901R cells showed increased levels of EGR1, which could transcriptionally activate the angiogenic factor CCL2 and EMT regulator ZEB2. Reciprocally, CCL2 activated the CCR2-ERK-ELK1-EGR1 pathway, thus forming a positive feed-forward loop. Moreover, CCL2 in culture medium of SGC7901R cells promoted angiogenesis of Human Umbilical Vein Endothelial Cells (HUVECs). EGR1 expression was positively correlated with CCL2 and ZEB2 in clinical GC tissues, and the depletion of ERG1 could also decrease microvessel density and ZEB2 expression in metastatic nodules of nude mice. EGR1-CCL2 feedback loop might exert critical roles on EMT and angiogenesis of chemoresistant GC.

Circular RNA circ_0001017 Sensitizes Cisplatin-Resistant Gastric Cancer Cells to Chemotherapy by the miR-543/PHLPP2 Axis.

Resistance to cisplatin (CDDP) remains a major challenge for the treatment of gastric cancer (GC). Circular RNAs (circRNAs) have been implicated in the development of CDDP resistance of GC. However, the precise actions of circ_0001017 in CDDP resistance of GC remain to be elucidated. The levels of circ_0001017, microRNA (miR)-543 and PH-domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) mRNA were gauged by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was used to analyze the protein levels of Vimentin, N-cadherin, E-cadherin, and PHLPP2. Ribonuclease R (RNase R) assay was applied to evaluate the stability of circ_0001017. Cell viability and proliferation, colony formation ability, cell cycle distribution and apoptosis, and migration and invasion were detected by the Cell Counting Kit-8 (CCK-8), colony formation, flow cytometry, and transwell assays, respectively. Direct relationship between miR-543 and circ_0001017 or PHLPP2 was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Xenograft model assay was used to assess the function of circ_0001017 in vivo. Low expression of circ_0001017 was associated with CDDP resistance of GC. Enforced expression of circ_0001017 impeded growth, metastasis, and enhanced apoptosis of HGC-27/R and AGS/R cells and sensitized them to CDDP in vitro. Circ_0001017 targeted miR-543, and circ_0001017 regulated CDDP-resistant cell behaviors and CDDP sensitivity by suppressing miR-543. PHLPP2 was a direct target of miR-543, and circ_0001017 controlled PHLPP2 expression through miR-543. Moreover, miR-543 knockdown-mediated promotion of PHLPP2 impacted CDDP-resistant cell behaviors and CDDP sensitivity in vitro. Additionally, elevated expression of circ_0001017 hindered growth of HGC-27/R cells and sensitized them to CDDP in vivo. Our findings demonstrated that enforced expression of circ_0001017 suppressed malignant behaviors and enhanced CDDP sensitivity of CDDP-resistant GC cells at least partially by the miR-543/PHLPP2 axis.

Induction of ferroptosis by ATF3 elevation alleviates cisplatin resistance in gastric cancer by restraining Nrf2/Keap1/xCT signaling

BackgroundCurrently, resistance against cisplatin (DDP) is a frequent problem for the success of advanced gastric carcinoma (GC) chemotherapy. Here, we sought to investigate the function of activating transcription factor 3 (ATF3) n GC chemoresistance.MethodsExpression of ATF3 was determined in GC cell lines (MNK45, SGC7901, and BGC823) and cisplatin (DDP)-resistant cells (SGC7901/DDP and BGC823/DDP). Biological informatics was performed to analyze ATF3 expression and prognosis in GC patients. Cisplatin resistance was evaluated. Ferroptosis was detected after ATF3 transfection of cells. The underlying molecular mechanism was also investigated.ResultsTranscripts of ATF3 were decreased in GC cells and GC tissues. Kaplan–Meier plotter analysis revealed that ATF3 expression was positively related to the overall survival of GC patients. In particular, lower levels of ATF3 were observed in cisplatin-resistant SGC7901/DDP and BGC823/DDP relative to their parental cells. Notably, ATF3 elevation sensitized cisplatin-resistant cells to cisplatin. Mechanically, compared with parental cells, SGC7901/DDP and BGC823/DDP cells exhibited lower ferroptosis evident by lower ROS, MDA and lipid peroxidation and higher intracellular GSH levels. However, ATF3 elevated ferroptosis in SGC7901/DDP and BGC823/DDP cells. Intriguingly, ATF3 overexpression together with ferroptosis activator erastin or RSL3 treatment further enhanced ferroptosis and cisplatin resistance; however, the ferroptosis suppressor liproxstatin-1 reversed the function of ATF3 in ferroptosis and cisplatin resistance. Additionally, cisplatin-resistant cells exhibited stronger activation of Nrf2/Keap1/xCT signaling relative to parental cells, which was restrained by ATF3 up-regulation. Importantly, restoring Nrf2 signaling overturned ATF3-mediated ferroptosis and cisplatin resistance.ConclusionATF3 may sensitize GC cells to cisplatin by induction of ferroptosis via blocking Nrf2/Keap1/xCT signaling, supporting a promising therapeutic approach for overcoming chemoresistance in GC.

Mortalin/glucose-regulated protein 75 promotes the cisplatin-resistance of gastric cancer via regulating anti-oxidation/apoptosis and metabolic reprogramming

Platinum drug treatment is one of the most predominant chemotherapeutic strategies for patients with gastric cancer (GC). However, the therapeutic effect is less than satisfactory, largely due to the acquired resistance to platinum drugs. Therefore, a better understanding of the underlying mechanisms can greatly improve the therapeutic efficacy of GC. In this study, we aimed to investigate the chemo-resistance related functions/mechanisms and clinical significance of glucose-regulated protein 75 (GRP75) in GC. Here, our data showed that compared with SGC7901 cells, the expression of GRP75 was markedly higher in cisplatin-resistance cells (SGC7901CR). Knockdown of GRP75 abolished the maintenance of mitochondrial membrane potential (MMP) and inhibited the nuclear factor erythroid-2-related factor 2 (NRF2), phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT), hypoxia-inducible factor 1α (HIF-1α), and c-myc, which resulted in blocking the activation of their downstream targets. These processes attenuated the anti-oxidation/apoptosis abilities and altered the metabolic reprogramming in SGC7901CR cells, leading to re-sensitizing these cells to cisplatin. However, overexpression of GRP75 in SGC7901 cells caused the opposite effects. A xenografts model confirmed the abovementioned results. In GC patients receiving platinum chemotherapy and a meta-analysis, a high level of GRP75 was positively associated with aggressive characteristics and poor prognosis including but not limited to gastrointestinal cancers, and was an independent predictor for overall survival. Collectively, our study indicated that GRP75 was involved in the cisplatin-resistance of GC and that GRP75 could be a potential therapeutic target for restoring the drug response in platinum-resistance cells and a useful additive prognostic tool in guiding clinical management of GC patients.

Celastrol Inhibits the Proliferation and Decreases Drug Resistance of Cisplatin- Resistant Gastric Cancer SGC7901/DDP Cells.

This study aimed to determine the effect and mechanism of Celastrol inhibiting the proliferation and decreasing the drug resistance of cisplatin-resistant gastric cancer cells. The objective of this study was to explore the effect and mechanism of Celastrol on proliferation and drug resistance of human gastric cancer cisplatin-resistant cells SGC7901/DDP. The thiazole blue (MTT) method was used to detect the sensitivity of human gastric cancer cisplatinresistant cells SGC7901/DPP to cisplatin and Celastrol to determine the Drug Resistance Index (DRI). According to the half Inhibitory Concentration (IC50) value, the action of the concentration of the following experimental drugs was set to reduce the cytotoxicity. Annexin V-FITC/PI double staining method was used to detect the apoptosis of SGC7901/DDP cells induced by Celastrol. Western Blot was used to examine the expression levels of P-glycoprotein (P-gp), Multidrug Resistance Associated Protein 1 (MRP1), Breast Cancer Resistance Associated Protein (Breast Cancer Resistance)-relative protein (BCRP), and mechanistic Target of Rapamycin (mTOR) pathway-related proteins. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect the mRNA expression levels of P-gp, MRP1, and BCRP. (1) Compared with the control group (we set the untreated group as the control group), the proliferation of the SGC7901/DPP cells was significantly inhibited after treating with 0.1-6.4μmol/L Celastrol in a time- and concentration-dependent manner (P<0.05). The Drug Resistance Index (DRI) of the SGC7901/DPP cells to DDP was 5.64. (2) Compared with the control group, Celastrol could significantly inhibit the proliferation and induce the apoptosis of the SGC7901/DPP cells (P<0.05). (3) The mRNA and protein expression levels of P-gp, MRP1, and BCRP in the SGC7901/DPP cells were significantly higher than those in the SGC7901 cells. However, after treating with Celastrol, the expression levels of P-gp, MRP1, and BCRP in the SGC7901/DPP cells were significantly reduced (P<0.05). (4) Compared with the control group, the Celastrol treatment also reduced the expression of the mTOR signaling pathway-related proteins, suggesting that the mTOR signaling pathway may be involved in the process of Celastrol inhibiting the proliferation of the SGC7901/DDP cells and reducing their drug resistance. (5) Significantly, the combination of Celastrol and DDP reduced the expression of P-gp, MRP1, and BCRP in the SGC7901/DPP cells. Celastrol can inhibit the proliferation of the SGC7901/DDP cells, induce their apoptosis, and reduce the expression of drug resistance genes, probably by inhibiting the expression of the proteins related to the mTOR signaling pathway.

Circular RNA circ_ASAP2 regulates drug sensitivity and functional behaviors of cisplatin-resistant gastric cancer cells by the miR-330-3p/NT5E axis.

This study aims to explore the biological actions of circular RNA (circRNA) ArfGAP with SH3 domain, ankyrin repeat and PH domain 2 (circ_ASAP2, circ_0006089) in cisplatin (DDP) resistance of gastric cancer. Circ_ASAP2, ecto-5'-nucleotidase (NT5E) and miR-330-3p were quantified by quantitative real-time PCR or western blot. The measurements of the IC50 value and cell proliferation were done using 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay. Cell colony formation, cell cycle distribution, apoptosis, migration and invasion were evaluated by the colony formation, flow cytometry and transwell assays. Dual-luciferase reporter assay was performed to confirm the targeted relationship between different molecules. The role of circ_ASAP2 in tumor growth was gauged by in vivo animal studies. Circ_ASAP2 and NT5E were overexpressed in DDP-resistant gastric cancer tissues and cells. Knockdown of circ_ASAP2 promoted DDP sensitivity, apoptosis and repressed proliferation, migration and invasion of DDP-resistant gastric cancer cells in vitro and diminished tumor growth in vivo. Moreover, NT5E was a downstream effector of circ_ASAP2 in regulating cell DDP sensitivity and functional behaviors. Mechanistically, circ_ASAP2 directly bound to miR-330-3p to promote NT5E expression. Furthermore, circ_ASAP2 modulated cell DDP sensitivity and functional behaviors by targeting miR-330-3p. Knockdown of circ_ASAP2 promoted DDP sensitivity and suppressed malignant behaviors of DDP-resistant gastric cancer cells through targeting the miR-330-3p/NT5E axis.

HCP5 contributes to cisplatin resistance in gastric cancer through miR-128/HMGA2 axis

ABSTRACT The long non-coding RNA HLA complex P5 (HCP5) is extensively related to cancer chemoresistance, while its function in gastric cancer (GC) has not been well elucidated yet. Here, the role and mechanism of HCP5 in regulating the chemoresistance of GC to cisplatin (DDP) was investigated. Our results revealed that HCP5 was increased in GC patients and indicated a poor prognosis. HCP5 knockdown weakens DDP resistance and reduced apoptosis of GC cells. miR-128 was decreased in GC patients and sponged by HCP5. HMGA2 was targeted by miR-128 and was increased in GC patients. HCP5 aggravated the resistance of GC cells to DDP in vitro by elevating HMGA2 expression via sponging miR-128. HCP5 silencing inhibited GC cells growth, resistance to DDP, and Ki-67 expression in vivo. In summary, HCP5 contributed to DDP resistance in GC cells through miR-128/HMGA2 axis, providing a promising therapeutic target for GC chemoresistance.

Simultaneously target of normal and stem cells-like gastric cancer cells via cisplatin and anti-CD133 CAR-T combination therapy.

CD133 + cancer stem cells mediate chemoresistance in multiple aggressive cancers, and anti-CD133 chimeric antigen receptor T (CAR-T) cells are designed to selectively target cisplatin-resistant gastric cancer stem cells in this investigation. The relative CD133 expression was detected in gastric cancer patients before and after cisplatin treatment. Anti-CD133 CAR-T cells were incubated with cisplatin-exposed CD133+ BGC-823 cells to evaluate the killing efficacy. At the same time, the canonical T cell activation markers were assayed by fluorescence-activated cell sorting, and the functional cytokine profile was detected with enzyme-linked immunosorbent assays. In addition to the percentage of CD133 positive stem cell-like cells, the volume and weight of subcutaneous tumors in BGC-823, KATO III and MKN-28 xenograft models were measured to evaluate the anti-tumor activity of cisplatin and anti-CD133 CAR-T combination strategy. After cisplatin treatment, both human samples and BGC-823 cells showed up-regulated CD133 expression. Anti-CD133 CAR-T cells exhibited pronounced killing efficiency against cisplatin-exposed CD133+ BGC-823 cells with up-regulated activation markers and cytotoxicity cytokine production. Moreover, cisplatin and anti-CD133 CAR-T combination treatment inhibited tumor progression in three different xenograft models with diminished CD133 positive stem cell-like cell infiltration. These results indicate that cisplatin and anti-CD133 CAR-T combination strategy can simultaneously target normal and stem cell-like gastric cancer cells to improve the treatment outcome.

Low-dose Diosbulbin-B (DB) activates tumor-intrinsic PD-L1/NLRP3 signaling pathway mediated pyroptotic cell death to increase cisplatin-sensitivity in gastric cancer (GC)

BackgroundEmerging evidences suggests that Diosbulbin-B (DB) is effective to improve cisplatin (DDP)-sensitivity in gastric cancer (GC), but its molecular mechanisms were not fully delineated, and this study managed to investigate this issue.MethodsGenes expressions were determined by Real-Time qPCR and Western Blot at transcriptional and translational levels. Cell proliferation and viability were evaluated by cell counting kit-8 (CCK-8) and trypan blue staining assay. Annexin V-FITC/PI double staining assay was used to examine cell apoptosis. The Spheroid formation assay was used to evaluated cell stemness. The xenograft tumor-bearing mice models were established, and the tumors were monitored and the immunohistochemistry (IHC) was employed to examine the expressions and localization of Ki67 protein in mice tumor tissues.ResultsLow-dose DB (12.5 μM) downregulated PD-L1 to activate NLRP3-mediated pyroptosis, and inhibited cancer stem cells (CSCs) properties, to sensitize cisplatin-resistant GC (CR-GC) cells to cisplatin. Mechanistically, the CR-GC cells were obtained, and either low-dose DB or cisplatin alone had little effects on cell viability in CR-GC cells, while low-dose DB significantly induced apoptotic cell death in cisplatin treated CR-GC cells. In addition, low-dose DB triggered cell pyroptosis in CR-GC cells co-treated with cisplatin, which were abrogated by silencing NLRP3. Next, CSCs tended to be enriched in CR-GC cells, instead of their parental cisplatin-sensitive GC (CS-GC) cells, and low-dose DB inhibited spheroid formation and stemness biomarkers (SOX2, OCT4 and Nanog) expressions to eliminate CSCs in CR-GC cells, which were reversed by upregulating programmed death ligand-1 (PD-L1). Furthermore, we proved that PD-L1 negatively regulated NLRP3 in CR-GC cells, and low-dose DB activated NLRP3-mediated pyroptotic cell death in cisplatin treated CR-GC cells by downregulating PD-L1. Also, low-dose DB aggravated the inhibiting effects of cisplatin on tumorigenesis of CR-GC cells in vivo.ConclusionsCollectively, low-dose DB regulated intrinsic PD-L1/NLRP3 pathway to improve cisplatin-sensitivity in CR-GC cells, and this study provided alternative therapy treatments for GC.

Cisplatin-Resistant Gastric Cancer Cells Promote the Chemoresistance of Cisplatin-Sensitive Cells via the Exosomal RPS3-Mediated PI3K-Akt-Cofilin-1 Signaling Axis.

Cisplatin is an important agent in first-line chemotherapy against gastric cancer (GC). However, consequential drug resistance limits its effectiveness for the treatment of GC. In this study, a cisplatin resistant gastric cancer cell line SGC7901R was determined by LC-MS/MS with increased exosomal levels of RPS3 protein. SGC7901R cell-derived exosomes were readily taken up by cisplatin-sensitive SGC7901S cells, thus triggering off a phenotype of chemoresistance in the receptor cells. Subsequently, it was demonstrated that exosomal RPS3 was essential for inducing chemoresistance of receptor cells as shown by the acquisition of this phenotype in SGC7901S cells with enforced expression of RPS3. Further mechanism study demonstrated that cisplatin-resistant gastric cancer cell-derived exosomal RPS3 enhanced the chemoresistance of cisplatin-sensitive gastric cancer cells through the PI3K-Akt-cofilin-1 signaling pathway. All these findings demonstrated that cisplatin-resistant gastric cancer cells communicate with sensitive cells through the intercellular delivery of exosomal RPS3 and activation of the PI3K-Akt-cofilin-1 signaling pathway. Targeting exosomal RPS3 protein in cisplatin-resistant gastric cancer cells may thus be a promising strategy to overcome cisplatin resistance in gastric cancer.

PD-1/PD-L1 enhanced cisplatin resistance in gastric cancer through PI3K/AKT mediated P-gp expression

BackgroundProgrammed cell death receptor 1 (PD-1) is an immunosuppressive molecule expressed on T cells, and its ligand (PD-L1) which expressed on tumor cells play pivotal roles in regulating host immune responses. However, little is known whether PD-1/PD-L1 axis could directly activates intracellular oncogenic signaling pathways in tumor cells, leading to tumor resistance. MethodsIn the present study, the expression of PD-1 and PD-L1 in the tissues of gastric cancer was detected by western blot and immunofluorescence. The effect of PD-L1-Fc and cisplatin on resistant gastric cancer cells was examined by MTT assay and Flow Cytometry. In addition. The effect of PD-L1-Fc on the expression of P-gp in gastric cancer cells and resistant gastric cancer cells was detected by quantitative real-time reverse-transcription PCR (qRT-PCR) and western blot. The molecular mechanisms of the regulation of cisplatin and PD-L1-Fc treatment were evaluated by western blot. ResultsWe found that the level of PD-1 was significantly increased in human gastric cancer tissues and drug-resistant gastric cancer cells and P-gp was the same result. The PD-L1 could reduce the level of cell damage caused by cisplatin. In addition, we found PD-L1 can also up-regulate the expression of P-gp. Mechanistically, PD-L1 activated the PI3K/AKT signaling pathway in which PI3K/AKT pathway inhibition attenuated the upregulation of P-gp. ConclusionPD-1/PD-L1 enhanced cisplatin resistance in gastric cancer through PI3K/AKT mediated P-gp expression.

Loss of DAB2IP Contributes to Cell Proliferation and Cisplatin Resistance in Gastric Cancer.

ObjectiveResistance to chemotherapeutic drugs, such as cisplatin, has been one of the major problems adversely affecting the clinical prognosis of patients with gastric cancer (GC). Disabled Homolog 2-Interacting Protein (DAB2IP) status is one of the major factors involved in sensitivity to chemotherapy in multiple cancer types. In the present study, we aimed to investigate the potential roles of DAB2IP in GC cell proliferation and cisplatin resistance.Materials and MethodsDAB2IP expression was detected in human GC tissues using immunohistochemistry (IHC). The role of DAB2IP in regulating GC cell proliferation and cisplatin resistance was explored by genetic manipulation. Western blot analysis was used to determine the molecular signaling to explain the mechanism of the observed DAB2IP effects in GC.ResultsDAB2IP expression was downregulated in human GC tissues and low DAB2IP expression predicted poor prognosis. Moreover, our data provided evidence that DAB2IP upregulation impaired cell proliferation property and sensitized GC cells to cisplatin while DAB2IP depletion possessed the opposite effects. Mechanistically, we showed that DAB2IP could inhibit the phosphorylation and activation of protein kinase B (AKT) and extracellular signal-regulated kinase (ERK), and the enhanced proliferation ability induced by DAB2IP knockdown was greatly impaired after incubation with AKT or ERK inhibitor.ConclusionDAB2IP modulates GC cell proliferation and sensitivity to cisplatin potentially via regulation of AKT and ERK signaling pathway, indicating that DAB2IP may serve as a potential prognostic biomarker and therapeutic target for treatment of GC.

LncRNA BANCR Attenuates the Killing Capacity of Cisplatin on Gastric Cancer Cell Through the ERK1/2 Pathway.

PurposeChemotherapy-based comprehensive treatments are the most important therapeutic methods for patients with advanced gastric cancer, but chemoresistance often cause treatment failure. Long non-coding RNA (LncRNA) BRAF-activated non-coding RNA (BANCR) has been shown to participate in many biological behaviors of multiple cancers. However, the biological roles of LncRNA BANCR in chemoresistance of gastric cancer remain unclear. Here, we aimed to evaluate the functions of LncRNA BANCR on the therapy of gastric cancer.MethodsIn this study, LncRNA BANCR expression was detected in gastric cancer patient samples and cell lines by quantity polymerase chain reaction (qPCR). Cell proliferation and viability in cisplatin-treated cells were measured using clonogenic survival assay and cell counting kit-8. The levels of ERK1/2 pathway molecules were tested with Western blot. Ly3214996, an inhibitor of ERK signal pathway, was administered to assess the effects of BANCR overexpression on gastric cancer cell with cisplatin-treated resistance. Moreover, the role of BANCR in cisplatin resistance of gastric cancer was validated in xenograft mouse models in vivo.ResultsOur study revealed that LncRNA BANCR expression was also significantly increased in gastric cancer tissues compared with adjacent normal tissues. Furthermore, we found that BANCR overexpression promoted gastric cancer cell resistance to cisplatin in vitro. Ly3214996 treatment abolished the BANCR overexpression-mediated gastric cancer cell cisplatin resistance via regulating the phosphorylation of ERK protein. Knock-down of BANCR significantly delayed tumor growth in xenograft mouse models.ConclusionBANCR promoted cisplatin resistance of gastric cancer cells by activating ERK1/2 pathway. Inhibition of BANCR markedly suppressed the growth of gastric cancer cells in vitro as well as in vivo. These results provided a new strategy for gastric cancer therapy via targeting BANCR.

HDAC3-mediated lncRNA-LOC101928316 contributes to cisplatin resistance in gastric cancer via activating the PI3K-Akt-mTOR pathway.

The present study aimed to explore how histone deacetylases 3 (HDAC3) regulated the resistance to cisplatin by inhibiting the transcription of lncRNA-LOC101928316 (LOC101928316) in gastric cancer (GC). We revealed that HDAC3 expression in cisplatin-resistant cell lines was significantly higher than that of GC parental cell lines. Besides, knockdown of HDAC3 inhibited the cell activity, cell invasion, and migration but promoted the apoptosis of GC cisplatin-resistant cell lines. To our surprise, silencing HDAC3 inhibited the transcription of LOC101928316 by promoting the level of acetylation of H3K4 on the LOC101928316 promoter, thus promoting the LOC101 expression in GC cisplatin-resistant cell lines. Together, the overexpression of HDAC3 mediated LOC101928316 to promote GC resistance to cisplatin by activating the PI3K-Akt-mTOR pathway. Therefore, HDAC3 may serve as a potential target of cisplatin resistance in GC.