Cisplatin resistance in gastric cancer cells is associated with HER2 upregulation-induced epithelial-mesenchymal transition.
ABSTRACT: Cisplatin remains to be primary chemotherapeutic drug for gastric cancer patients, especially for advanced stage ones. However, primary or acquired resistance often occurs with the mechanisms being not well understood, which results in relapse of the cancer and poor survival. Herein, we found that HER2 upregulation was associated with cisplatin resistance. We observed that cisplatin-resistant gastric cancer cells underwent a morphological change similar to epithelial-mesenchymal transition (EMT) which is mediated by HER2 overexpression. When specific monoclonal antibody Herceptin, small molecular targeted drug CP724714, or small interfering RNA against HER2 was applied, the EMT-like phenotypic change was dramatically reversed. More importantly, the IC50 and Resistance Index of resistant gastric cancer cells to cisplatin were also decreased by any of these treatments.We demonstrated that expression and amplification of HER2 positively correlated with expression of EMT-related transcription factor Snail in gastric cancer tissues. Furthermore, for the first time, we found that HER2/Snail double positive gastric cancer patients had poorer survival than single positive or double negative counterparts, which provided experimental evidence for the necessity of HER2/Snail double testing in gastric cancer. In conclusion, this study provides some clues of the association of cisplatin resistance with HER2 upregulation-induced EMT in gastric cancer cells.
Project description:The epithelial to mesenchymal transition (EMT) is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers.Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays.Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects.This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance.
Project description:To investigate the contribution of periostin in nicotine-promoted gastric cancer cell proliferation, survival, invasion, drug resistance, and epithelial-mesenchymal transition (EMT).Gastric cancer cells were treated with nicotine and periostin protein expression was determined by immunoblotting. Periostin mRNA in gastric cancer cells was silenced using small interfering RNA (siRNA) techniques and periostin gene expression was evaluated by quantitative reverse transcription-polymerase chain reaction. Gastric cancer cells transfected with control or periostin siRNA plasmid were compared in terms of cell proliferation using the methylthiazolyldiphenyl-tetrazolium bromide assay. Cell apoptosis was compared using annexin V-fluoresceine isothiocyanate and propidium iodine double staining. Tumor invasion was determined using the Boyden chamber invasion assay, and the EMT marker Snail expression was evaluated by immunoblotting.Nicotine upregulated periostin in gastric cancer cells through a COX-2 dependent pathway, which was blocked by the COX-2-specific inhibitor NS398. Periostin mRNA expression was decreased by ~87.2% by siRNA in gastric cancer cells, and stable periostin-silenced cells were obtained by G418 screening. Periostin-silenced gastric cancer cells exhibited reduced cell proliferation, elevated sensitivity to chemotherapy with 5-fluorouracil, and decreased cell invasion and Snail expression (P < 0.05).Periostin is a nicotine target gene in gastric cancer and plays a role in gastric cancer cell growth, invasion, drug resistance, and EMT facilitated by nicotine.
Project description:Rho GDP dissociation inhibitor 2 (RhoGDI2) expression correlates with tumor growth, metastasis, and chemoresistance in gastric cancer. Here, we show that RhoGDI2 functions in the epithelial-mesenchymal transition (EMT), which is responsible for invasiveness during tumor progression. This tumorigenic activity is associated with repression of E-cadherin by RhoGDI2 via upregulation of Snail. Overexpression of RhoGDI2 induced phenotypic changes consistent with EMT in gastric cancer cells, including abnormal epithelial cell morphology, fibroblast-like properties, and reduced intercellular adhesion. RhoGDI2 overexpression also resulted in decreased expression of the epithelial markers E-cadherin and ?-catenin and increased expression of the mesenchymal markers vimentin and fibronectin. Importantly, RhoGDI2 overexpression also stimulated the expression of Snail, a repressor of E-cadherin and inducer of EMT, but not other family members such as Slug or Twist. RNA interference-mediated knockdown of Snail expression suppressed RhoGDI2-induced EMT and invasion, confirming that the effect was Snail-specific. These results indicate that RhoGDI2 plays a critical role in tumor progression in gastric cancer through induction of EMT. Targeting RhoGDI2 may thus be a useful strategy to inhibit gastric cancer cell invasion and metastasis.
Project description:Chemoresistance is a major barrier to successful cisplatinbased chemotherapy for epithelial ovarian cancer (EOC), and emerging evidences suggest that microRNAs (miRNAs) are involved in the resistance. In this study, it was indicated that miR-363 downregulation was significantly correlated with EOC carcinogenesis and cisplatin resistance. Moreover, miR-363 overexpression could resensitise cisplatin-resistant EOC cells to cisplatin treatment both in vitro and in vivo. In addition, data revealed that EMT inducer Snail was significantly upregulated in cisplatin-resistant EOC cell lines and EOC patients and was a functional target of miR-363 in EOC cells. Furthermore, snail overexpression could significantly attenuate miR-363-suppressed cisplatin resistance of EOC cells, suggesting that miR-363-regulated cisplatin resistance is mediated by snail-induced EMT in EOC cells. Taken together, findings suggest that miR-363 may be a biomarker for predicting responsiveness to cisplatin-based chemotherapy and a potential therapeutic target in EOC. [BMB Reports 2018; 51(9): 456-461].
Project description:Cisplatin is the major chemotherapeutic drug in gastric cancer, particularly in treating advanced gastric cancer. Tumour cells often develop resistance to chemotherapeutic drugs, which seriously affects the efficacy of chemotherapy. GPR30 is a novel oestrogen receptor that is involved in the invasion, metastasis and drug resistance of many tumours. Targeting GPR30 has been shown to increase the drug sensitivity of breast cancer cells. However, few studies have investigated the role of GPR30 in gastric cancer. Epithelial-mesenchymal transition (EMT) has been shown to be associated with the development of chemotherapeutic drug resistance. In this study, we demonstrated that GPR30 is involved in cisplatin resistance by promoting EMT in gastric cancer. GPR30 knockdown resulted in increased sensitivity of different gastric cancer (GC) cells to cisplatin and alterations in the epithelial/mesenchymal markers. Furthermore, G15 significantly enhanced the cisplatin sensitivity of GC cells while G1 inhibited this phenomenon. In addition, EMT occurred when AGS and BGC-823 were treated with cisplatin. Down-regulation of GPR30 with G15 inhibited this transformation, while G1 promoted it. Taken together, these results revealed the role of GPR30 in the formation of cisplatin resistance, suggesting that targeting GPR30 signalling may be a potential strategy for improving the efficacy of chemotherapy in gastric cancer.
Project description:Vascular endothelial growth factor receptor (VEGFR) and neuropilins (NRPs), a co-receptor of VEGF, play a key role in the formation and development of blood vessels and in tumour growth and metastasis. However, whether VEGFR1/2 and NRP1 are regulated by the same upstream mechanism is unclear, especially in gastric cancer. We used prediction tools to detect miRNAs that may simultaneously regulate VEGFR1/2 and NRP1, and we finally determined that miR-590 can simultaneously regulate VEGFR1/2 and NRP1 in gastric cancer. We discovered that miR-590 was downregulated in gastric cancer tissues and cell lines, and this was related to the dysregulation of the transcription factor SNAIL. In addition, the overexpression of miR-590 inhibits the migration, invasion, proliferation and D-MVA levels of gastric cancer cells in vivo and in vitro by targeting VEGFR1/2 and NRP1. We also demonstrated that miR-590 may be a useful marker for the prognosis of gastric cancer with Kaplan-Meier survival analysis. Since the epithelial-to-mesenchymal transition (EMT) is an important mechanism of tumour invasion and metastasis and VEGFR1/2 and NRP1 can promote the occurrence of EMT, we speculated that miR-590 can regulate the occurrence of EMT. Immunoblot and immunofluorescence analyses confirmed that the overexpression of miR-590 can inhibit the EMT in gastric cancer cells. Since SNAIL is also a mesenchymal marker, our results revealed a new, positive feedback loop. As a transcription factor, SNAIL inhibits the expression of miR-590, thereby upregulating the expression levels of NRP1 and VEGFR1/2; this leads to the development of EMT in gastric cancer and the upregulation of SNAIL.
Project description:Cathepsin L (CTSL), a lysosomal acid cysteine protease, is known to play important roles in tumor metastasis and chemotherapy resistance. In this study we investigated the molecular mechanisms underlying the regulation of chemoresistance by CTSL in human lung cancer cells.Human lung cancer A549 cells, A549/PTX (paclitaxel-resistant) cells and A549/DDP (cisplatin-resistant) cells were tested. The resistance to cisplatin or paclitaxel was detected using MTT and the colony-formation assays. Actin remodeling was observed with FITC-Phalloidin fluorescent staining or immunofluorescence. A wound-healing assay or Transwell assay was used to assess the migration or invasion ability. The expression of CTSL and epithelial and mesenchymal markers was analyzed with Western blotting and immunofluorescence. The expression of EMT-associated transcription factors was measured with Western blotting or q-PCR. BALB/c nude mice were implanted subcutaneously with A549 cells overexpressing CTSL, and the mice were administered paclitaxel (10, 15 mg/kg, ip) every 3 d for 5 times.Cisplatin or paclitaxel treatment (10-80 ng/mL) induced CTSL expression in A549 cells. CTSL levels were much higher in A549/PTX and A549/DDP cells than in A549 cells. Silencing of CTSL reversed the chemoresistance in A549/DDP and A549/TAX cells, whereas overexpression of CTSL attenuated the sensitivity of A549 cells to cisplatin or paclitaxel. Furthermore, A549/DDP and A549/TAX cells underwent morphological and cytoskeletal changes with increased cell invasion and migration abilities, accompanied by decreased expression of epithelial markers (E-cadherin and cytokeratin-18) and increased expression of mesenchymal markers (N-cadherin and vimentin), as well as upregulation of EMT-associated transcription factors Snail, Slug, ZEB1 and ZEB2. Silencing of CTSL reversed EMT in A549/DDP and A549/TAX cells; In contrast, overexpression of CTSL induced EMT in A549 cells. In xenograft nude mouse model, the mice implanted with A549 cells overexpressing CTSL exhibited significantly reduced sensitivity to paclitaxel treatment, and increased expression of EMT-associated proteins and transcription factors in tumor tissues.Cisplatin and paclitaxel resistance is associated with CTSL upregulation-induced EMT in A549 cells. Thus, CTSL-mediated EMT may be exploited as a target to enhance the efficacy of cisplatin or paclitaxel against lung cancer and other types of malignancies.
Project description:MicroRNAs (miRNAs) play a critical role in drug resistance and epithelial-mesenchymal transition (EMT). The aims of this study were to explore the potential role of miR-206 in governing cisplatin resistance and EMT in lung cancer cells. We found that both lung adenocarcinoma A549 cisplatin-resistant cells (A549/DDP) and H1299 cisplatin-resistant cells (H1299/DDP) acquired mesenchymal features and were along with low expression of miR-206 and high migration and invasion abilities. Ectopic expression of miR-206 mimics inhibited cisplatin resistance, reversed the EMT phenotype, decreased the migration and invasion in these DDP-resistant cells. In contrast, miR-206 inhibitors increased cisplatin resistance, EMT, cell migration and invasion in non-DDP-resistant cells. Furthermore, we found that MET is the direct target of miR-206 in lung cancer cells. Knockdown of MET exhibited an EMT and DDP resistant inhibitory effect on DDP-resistant cells. Conversely, overexpression of MET in non-DDP- resistant cells produced a promoting effect on cell EMT and DDP resistance. In lung adenocarcinoma tissues, we demonstrated that low expression of miR-206 were also correlated with increased cisplatin resistance and MET expression. In addition, we revealed that miR-206 overexpression reduced cisplatin resistance and EMT in DDP-resistant cells, partly due to inactivation of MET/PI3K/AKT/mTOR signaling pathway, and subsequent downregulation of MDR1, ZEB1 and Snail expression. Finally, we found that miR-206 could also sensitize A549/DDP cells to cisplatin in mice model. Taken together, our study implied that activation of miR-206 or inactivation of its target gene pathway could serve as a novel approach to reverse cisplatin resistance in lung adenocarcinomas cells.
Project description:Atypical teratoid/rhabdoid tumor (ATRT) is a malignant pediatric brain tumor with great recurrence after complete surgery and chemotherapy. Here, we demonstrate that cisplatin treatment selects not only for resistance but also for a more oncogenic phenotype characterized by high self-renewal and invasive capabilities. These phenomena are likely due to STAT3 upregulatoin which occurred simultaneously with higher expression of Snail, an activator of epithelial-mesenchymal transition (EMT), in ATRT-CisR cells. STAT3 knockdown effectively suppressed Snail expression and blocked motility and invasion in ATRT-CisR cells, while overexpressing Snail reversed these effects. Chromatin immunoprecipitation assay indicated that STAT3 directly bound to Snail promoter. Moreover, STAT3 knockdown effectively suppressed cancer stem-like properties, synergistically enhanced the chemotherapeutic effect, and significantly improved survival rate in ATRT-CisR-transplanted immunocompromised mice. Finally, immunohistochemistrical analysis showed that STAT3 and Snail were coexpressed at high levels in recurrent ATRT tissues. Thus, the STAT3/Snail pathway plays an important role in oncogenic resistance, rendering cells not only drug-resistant but also increasingly oncogenic (invasion, EMT and recurrence). Therefore, the STAT3/Snail could be a target for ATRT treatment.
Project description:Substantial evidence suggests that the epithelial-mesenchymal transition (EMT) phenotype is associated with the invasive characteristics of cancer stem cells (CSCs),which possess an EMT phenotype that may predominate in tumor invasion and metastasis. However, the mechanisms for the generation and regulation of these CSCs have not been clearly defined. As hypoxia and EMT-related factors may have important functions in EMT-like CSCs, the aim of this study was to investigate the effects of hypoxia on these cells. CSCs were established from the gastric cancer cell lines MGC-803 and SGC7901, and the relationship between hypoxia and EMT-like CSCs was investigated in gastric cancer. After hypoxia treatment, some gastric CSCs exhibited a marked increase in hypoxia-inducible factor-1? (HIF-1?)expression and increased migration and invasion capabilities compared with the normoxic control. These CSCs were defined by activation of the mesenchymal cell marker Vimentin and by inhibition of the epithelial cell marker E-cadherin. Our analyses also show that HIF-1? was responsible for activating EMT via increased expression of the transcription factor Snail in gastric CSCs. Moreover, inhibition of Snail by shRNA reduced HIF-1?-induced EMT in gastric CSCs. The results demonstrated that hypoxia-induced EMT-like CSCs rely on HIF-1?to activate Snail, which may result in recurrence and metastasis of gastric cancer.