Chemotherapy Resistance In Gastric Cancer Research Articles

Effects of hypoxia on the growth of gastric cancer and the chemotherapeutic efficacy of 5-fluorouracil.

Hypoxia is an important cause of chemotherapy resistance in gastric cancer. However, little is known about the growth of gastric cancer under purely hypoxia conditions. This study aims to study the effect of hypoxia on the growth patterns of gastric cancer cells and explore the response of gastric cancer cells to the chemotherapeutic drug 5-fluorouracil (5-FU) in a hypoxic environment. Gastric cancer cells MKN45 were cultured under 1% oxygen hypoxia and conventional air conditions. An intervention group with the addition of the chemotherapeutic drug 5-FU was also established. The proliferation and apoptosis of gastric cancer cells under different oxygen conditions and intervention groups were detected using the cell counting kit-8 (CCK-8) method, JC-1 mitochondrial membrane potential assay, and Annexin-V/PI double staining method. Cell cycle changes were detected by flow cytometry, and mitochondrial changes were detected using electron microscopy. In the absence of 5-FU intervention, compared with the normoxia group, the hypoxia group showed higher rates of early and late apoptosis and higher cell death rates as indicated by the JC-1 mitochondrial membrane potential assay, Annexin-V/PI double staining, and CCK-8 results. Flow cytometry results showed that the cell cycle was arrested in the G0/G1 phase without progression. Electron microscopy revealed more severe mitochondrial destruction. However, with 5-FU intervention, the hypoxia group showed lower apoptosis rates, more cell cycle progression, and less mitochondrial destruction compared with the normoxia group. Hypoxic environments promote apoptosis and even death in gastric cancer cells, but hypoxia counteracts the efficacy of the chemotherapeutic drug 5-FU, which may contribute to 5-FU chemotherapy resistance.

Abstract 5872: CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer

Abstract Gastric carcinoma (GC) is the third most prevalent cause of cancer-related mortality worldwide, presenting a formidable challenge with the rise of resistance to chemotherapeutic agents, leading to treatment failures. Cyclin-dependent kinase 1 (CDK1) has garnered attention due to its substantial overexpression in various tumors, including GC, and its association with poor overall survival and relapse-free survival. This study aimed to understand the molecular and functional mechanisms underlying the CDK1-SOX9 axis in GC chemotherapy resistance. Through a comprehensive analysis of data from The Cancer Genome Atlas (TCGA) and our own integrated gene expression study, we found a positive correlation between CDK1 and SOX9 in both human and mouse GC tissues (p<0.001). Additionally, conserved alterations in miRNAs have been identified in the context of gastric carcinogenesis, evident in our local cohort and the TCGA dataset. Our in-depth investigation of premiR-145 has shed light on the existence of several CpG nucleotides. Notably, treatment with a DNMT inhibitor (5-Aza) has triggered the upregulation of miR-145 expression. Furthermore, the ectopic expression of CDK1 has been associated with increased DNMT1 phosphorylation and enhanced enzymatic activity. Conversely, silencing CDK1 reversed this effect, and the inhibition of DNMT1 reduced SOX9 protein expression. Using cisplatin-resistant cell lines revealed a significant increase in CDK1 and SOX9 expression where silencing CDK1 and SOX9 sensitized these cells to chemotherapy. This study provides valuable insights into the intricate mechanisms governing the CDK1-SOX9 axis in GC chemotherapy resistance, providing potential avenues for therapeutic interventions in this challenging malignancy. Citation Format: Marwah M. Al-Mathkour, Shoumin Zhu, Melanie Genoula, Wael El-Rifai. CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5872.

Abstract 1379 CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer

Abstract 1379 CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer

HIPK3 maintains sensitivity to platinum drugs and prevents disease progression in gastric cancer

In the realm of cancer therapeutics and resistance, kinases play a crucial role, particularly in gastric cancer (GC). Our study focused on platinum-based chemotherapy resistance in GC, revealing a significant reduction in homeodomain-interacting protein kinase 3 (HIPK3) expression in platinum-resistant tumors through meticulous analysis of transcriptome datasets. In vitro and in vivo experiments demonstrated that HIPK3 knockdown enhanced tumor proliferation and metastasis, while upregulation had the opposite effect. We identified the myocyte enhancer factor 2C (MEF2C) as a transcriptional regulator of HIPK3 and uncovered HIPK3's role in downregulating the morphogenesis regulator microtubule-associated protein (MAP7) through ubiquitination. Phosphoproteome profiling revealed HIPK3's inhibitory effects on mTOR and Wnt pathways crucial in cell proliferation and movement. A combined treatment strategy involving oxaliplatin, rapamycin, and IWR1-1-endo effectively overcame platinum resistance induced by reduced HIPK3 expression. Monitoring HIPK3 levels could serve as a GC malignancy and platinum resistance indicator, with our proposed treatment strategy offering novel avenues for reversing resistance in gastric cancer.

The inhibitory effect of quercetin on chemotherapeutic drug resistance of gastric cancer through forkhead box D3 signaling pathway

Most gastric cancer patients have cancer cell metastasis at the time of being diagnosed. Cisplatin chemotherapy can slow down the development of gastric cancer, but the drug resistance will develop after a long time of chemotherapy. Previous studies have found that quercetin improves resistance of chemotherapy drugs. Therefore, this study intends to explore quercetin’s role in gastric cancer. SGC-7901 drug-resistant cell line was cultured and intervened. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay assessed cell proliferation, cell survival rate, IC50 value and sensitivity along with analysis of cell apoptosis, proliferation by colony formation assay and qRT-PCR (real-time reverse transcription-PCR) and Western blot detection of FOXD3 (Forkhead box D3) levels. Gastric cancer xenograft tumor mouse model was established to assess its in vivo role. The drug-resistant cell model of gastric cancer was successfully constructed and quercetin inhibited cell survival to a certain extent and improved its chemosensitivity. The pro-apoptotic effect of quercetin on cisplatin chemotherapy resistance in gastric cancer is related to the increased FOXD3 level. Quercetin can directly regulate the expression of FOXD3, which is an activation effect. The inhibition rate of gastric cancer mice in vivo was the most prominent in the quercetin+drug resistance group. The tumor-bearing site was significantly reduced and the number of surviving mice was the highest, whose tumor volume was consistently lower than that of other groups. Conclusively, quercetin has a strong anti-tumor effect. It can inhibit gastric cancer cell activity and accelerate apoptosis by activating FOXD3 signaling pathway.

RUNX2 Reverses p53-Induced Chemotherapy Resistance in Gastric Cancer.

Gastric cancer is one of the most common malignancies worldwide; however, its overall mortality has not improved significantly over the last decade. Chemoresistance plays a critical role in this issue. This study aimed to clarify the role and mechanism of runt-related transcription factor 2 (RUNX2) in platinum-based chemotherapy resistance. First, a drug-resistant model of gastric cancer cells was established to evaluate the relative expression level of the RUNX2 as a potential biomarker of chemotherapy resistance. Next, exogenous silencing was conducted to study whether RUNX2 could reverse drug resistance and understand the underlying mechanisms. Simultaneously, the correlation between the clinical outcomes of 40 patients after chemotherapy and the RUNX2 expression levels in tumor samples was analyzed. We discovered that RUNX2 was significantly expressed in drug-resistant gastric cancer cells and tissues; it was also reversibly resistant to transformation treatment by exogenous RUNX2 silencing. It is confirmed that RUNX2 negatively regulates the apoptosis pathway of the p53 to reduce the chemotherapeutic effects of gastric cancer. RUNX2 is a possible target for platinum-based chemotherapy resistance.

ASAP1 activates the IQGAP1/CDC42 pathway to promote tumor progression and chemotherapy resistance in gastric cancer

Abnormal expression and remodeling of cytoskeletal regulatory proteins are important mechanisms for tumor development and chemotherapy resistance. This study systematically analyzed the relationship between differential expression of cytoskeleton genes and prognosis in gastric cancer (GC). We found the Arf GTP-activating protein ASAP1 plays a key role in cytoskeletal remodeling and prognosis in GC patients. Here we analyzed the expression level of ASAP1 in tissue microarrays carrying 564 GC tissues by immunohistochemistry. The results showed that ASAP1 expression was upregulated in GC cells and can be served as a predictor of poor prognosis. Moreover, ASAP1 promoted the proliferation, migration, and invasion of GC cells both in vitro and in vivo. We also demonstrated that ASAP1 inhibited the ubiquitin-mediated degradation of IQGAP1 and thus enhanced the activity of CDC42. The activated CDC42 upregulated the EGFR-MAPK pathway, thereby promoting the resistance to chemotherapy in GC. Taken together, our results revealed a novel mechanism by which ASAP1 acts in the progression and chemotherapy resistance in GC. This may provide an additional treatment option for patients with GC.

PPIC-labeled CAF subpopulations may lead to neoadjuvant chemotherapy resistance in gastric cancer

PPIC-labeled CAF subpopulations may lead to neoadjuvant chemotherapy resistance in gastric cancer

Special AT-rich sequence binding protein 1 promotes multidrug resistance in gastric cancer by regulation of Ezrin to alter subcellular localization of ATP-binding cassette transporters.

Multidrug resistance is a primary factor in the poor response to chemotherapy and subsequent death in gastric cancer patients. However, the molecular mechanisms involved remain unclear. In this study, the high expression of special AT-rich sequence binding protein 1 (SATB1) in gastric cancer was found to be associated with reduced sensitivity to various chemotherapy drugs. Our results demonstrate that SATB1 can promote chemotherapy resistance in gastric cancer in vitro and in vivo. SATB1 exerts its effect by enhancing the activity of multiple ATP-binding cassette (ABC) transporters (P-glycoprotein, multidrug resistance-associated protein, and breast cancer resistance protein) in gastric cancer cell lines. We also found that SATB1 affects ABC transporters by altering the subcellular localization of the ABC transporter rather than its expression. Subsequently, we confirmed that Ezrin binds to various ABC transporters and affects their subcellular localization. In addition, we found that SATB1 can also bind to the Ezrin promoter and regulate its expression. In the present study, we elucidate the mechanism of SATB1-mediated multidrug resistance in gastric cancer, providing a basis for SATB1 as a potential target for reversal of resistance.

ATXN2-Mediated PI3K/AKT Activation Confers Gastric Cancer Chemoresistance and Attenuates CD8+ T Cell Cytotoxicity.

As one of the primary therapeutic choices, chemotherapy is widely adopted for progressive gastric cancer (GC), but the development of chemoresistance has limited chemotherapy efficacy and partly contributes to poor prognosis. Immunotherapy is increasingly being applied in the clinical treatment of GC and is also benefitting patients. To ascertain whether ATXN2 affects chemotherapy efficacy in GC cells and its role in GC immune escape, we performed high-throughput sequencing to clarify genes differentially expressed between 5-FU-resistant and 5-FU-sensitive GC cells and then conducted qRT–PCR to assess ATXN2 expression in GC tissues. Furthermore, the influence of ATXN2 on resistance was studied in vitro and in vivo, ATXN2 and other protein expression levels were detected using Western blotting and immunohistochemistry (IHC), and the direct association of SP1 and ATXN2 was confirmed through luciferase reporter gene analysis. We found elevated ATXN2 in GC tumors and a negative correlation between ATXN2 levels and the prognosis of GC. Furthermore, by activating the PI3K/AKT pathway, ATXN2 was found to promote chemoresistance in GC, facilitating BCL2L1 expression. In GC cells, ATXN2 further stimulated PD-L1 expression and provided better immunotherapy efficacy. Finally, we demonstrated that SP1 transcriptionally regulated the expression of ATXN2 and prompted GC chemoresistance and immune escape. In conclusion, our study reveals the important roles of the SP1/ATXN2/PI3K-AKT/BCL2L1 signalling pathway in GC chemoresistance and of the SP1/ATXN2/PI3K-AKT/PD-L1 signalling pathway in GC immunotherapy. Our findings provide new theories and experimental references for overcoming chemotherapy resistance in GC and enhancing the efficacy of immunotherapy for GC.

The Role of Lipid Metabolism in Gastric Cancer.

Gastric cancer has been one of the most common cancers worldwide with extensive metastasis and high mortality. Chemotherapy has been found as a main treatment for metastatic gastric cancer, whereas drug resistance limits the effectiveness of chemotherapy and leads to treatment failure. Chemotherapy resistance in gastric cancer has a complex and multifactorial mechanism, among which lipid metabolism plays a vital role. Increased synthesis of new lipids or uptake of exogenous lipids can facilitate the rapid growth of cancer cells and tumor formation. Lipids form the structural basis of biofilms while serving as signal molecules and energy sources. It is noteworthy that lipid metabolism is capable of inducing drug resistance in gastric cancer cells by reshaping the tumor micro-environment. In this study, new mechanisms of lipid metabolism in gastric cancer and the metabolic pathways correlated with chemotherapy resistance are reviewed. In particular, we discuss the effects of lipid metabolism on autophagy, biomarkers treatment and drug resistance in gastric cancer from the perspective of lipid metabolism. In brief, new insights can be gained into the development of promising therapies through an in-depth investigation of the mechanism of lipid metabolism reprogramming and resensitization to chemotherapy in gastric cancer cells, and scientific treatment can be provided by applying lipid-key enzyme inhibitors as cancer chemical sensitizers in clinical settings.

Current Advances and Outlook in Gastric Cancer Chemoresistance: A Review.

Surgical resection of the lesion is the standard primary treatment of gastric cancer. Unfortunately, most patients are already in the advanced stage of the disease when they are diagnosed with gastric cancer. Alternative therapies, such as radiation therapy and chemotherapy, can achieve only very limited benefits. The emergence of cancer drug resistance has always been the major obstacle to the cure of tumors. The main goal of modern cancer pharmacology is to determine the underlying mechanism of anticancer drugs. Here, we mainly review the latest research results related to the mechanism of chemotherapy resistance in gastric cancer, the application of natural products in overcoming the chemotherapy resistance of gastric cancer, and the new strategies currently being developed to treat tumors based on immunotherapy and gene therapy. The emergence of cancer drug resistance is the main obstacle in achieving alleviation and final cure for gastric cancer. Mixed therapies are considered to be a possible way to overcome chemoresistance. Natural products are the main resource for discovering new drugs specific for treating chemoresistance, and further research is needed to clarify the mechanism of natural product activity in patients.

Bone Marrow Mesenchymal Stem Cell (BMSC)-Derived Exosomal miR-168-5p Inhibits Proliferation and Chemotherapy Resistance in Gastric Cancer by Downregulation of Cyclin D1 and P Glycoprotein

miR-168-5p is indicated as an upstream effector of the tumor suppressor signal pathway in ovarian cancer and bladder cancer, but the role in gastric cancer (GC) remains unknown. This study aims to reveal the expression and significance of miR-168-5p in GC. RT-qPCR analysis was used to detect the expression of miR-168-5p in GC tissues and plasma, and the relationship of miR-168-5p and CCND1 was evaluated. GC cells were co-cultured with BMSCs or transfected with miR-168-5p mimic. CCK-8 assay and flow cytometry were conducted to assess the effect of miR-168-5p in GC and the interaction between BMSCs and cancer cell progression. Animal experiment was established to explore the in vivo effect of miR-168-5p. miR-168-5p is poorly expressed in gastric cancer cells and the plasma of patients with gastric cancer. BMSC co-culture is similar to miR-168-5p mimic induced miR-168-5p expression increase. miR-168-5p overexpression decreased the proliferative, invasive and migratory capacities of GC cells, and promoted apoptosis. Mechanically, miR-168-5p targeted and decreased the expression of CCND1. Additionally, the low miR-168-5p expression in GC was closely related to poor prognosis and malignant transformation. BMSC exosomes carrying miR-168-5p suppress cell progression in GC when inhibiting the expression of CCND1 and P glycoprotein, which indicates potential diagnostic and prognostic value of miR-168-5p and helps the development of miR-168-5p-based treatment for drug-resistant GC.

TOPBP1 regulates resistance of gastric cancer to oxaliplatin by promoting transcription of PARP1

Gastric cancer (GC) is the third leading cause of cancer-associated mortality worldwide. The platinum derivative oxaliplatin is widely applied in standard GC chemotherapy but recurrence and metastasis are common in advanced GC cases due to intrinsic or induced chemoresistance. Poly(ADP-Ribose) polymerase 1 (PARP1) is an enzyme crucial for repairing DNA damage induced by platinum compounds, which undermines the effectiveness of platinum-based chemotherapy. Data from the current study showed that topoisomerase IIβ binding protein 1 (TOPBP1), an interacting partner of topoisomerase IIβ, is highly expressed in oxaliplatin-resistant GC (OR-GC) cells and promotes PARP1 transcription through direct binding to its proximal promoter region. Furthermore, AKT-mediated phosphorylation of TOPBP1 at Ser1159 was indispensable for inducing PARP1 expression in OR-GC cells. Disruption of the TOPBP1/PARP1 regulatory pathway decreased cell viability and augmented apoptosis of OR-GC cells. The positive correlation between TOPBP1 and PARP1 was confirmed using both the TCGA database and immunohistochemical analysis of GC tissues. In GC patients receiving oxaliplatin treatment, high expression of TOPBP1 or PARP1 was associated with poor prognosis. Our finding that the TOPBP1/PARP1 pathway facilitates acquisition of oxaliplatin resistance uncovers a novel mechanism underlying platinum-based chemotherapy resistance in gastric cancer that may be utilized for developing effective therapeutic strategies.

Upregulation of THBS1 is Related to Immunity and Chemotherapy Resistance in Gastric Cancer.

PurposeThrombospondin 1 (THBS1) is an endogenous inhibitor of angiogenesis, but it also promotes tumor invasion, metastasis, and immune response in the tumor environment. Previous research has found that THBS1 is highly expressed in many tumors and has a negative correlation with tumor prognosis. However, research on the relationship between THBS1 and immune infiltration in GC is less well documented, and the objective of our study was to investigate the role of THBS1 expression in GC.Patients and MethodsThe expression of THBS1 in GC was analyzed by Oncomine, TIMER, TGCA, GEO and IHC staining. Analysis of the signaling pathways associated with THBS1 expression in GC uses GSEA. The relationship between THBS1 expression and immune infiltration was analyzed by the ESTIMATE algorithm, single-cell transcriptome analysis, TIMER2 database and CIBERSORT algorithm. Finally, the relationship between THBS1 expression and drug sensitivity was analyzed by the CellMiner database.ResultsTHBS1 was overexpressed in GC and was associated with poor prognosis, and high THBS1 expression was an independent risk factor. GSEA results showed that high THBS1 expression in GC was associated with tumorigenesis, adhesion, and significant immune enrichment. THBS1 expression was most strongly correlated with tumor-associated macrophages (TAMs), M2 macrophages and cancer-associated fibroblast (CAFs) in GC. THBS1 expression positively correlates with most immune checkpoint members, suggesting that THBS1 may play an important role in the tumor microenvironment. THBS1 overexpression was negatively correlated with some drug sensitivities, such as Oxaliplatin.ConclusionUpregulation of THBS1 was positively correlated with poor prognosis and immunosuppression in GC and negatively correlated with anticancer drug sensitivity, suggesting that THBS1 may serve as a potential target for the treatment of GC.

The role of PKM2 nuclear translocation in the constant activation of the NF-\u03baB signaling pathway in cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) play critical roles in cancer progression by regulating tumor cell proliferation, angiogenesis, and metastasis. Recent studies demonstrated that CAFs induce inhibitory immune cell infiltration and chemotherapy resistance in gastric cancer by activating the NF-κB signaling pathway to secrete IL6, IL8, and other inflammatory factors. Inhibition of the NF-κB signaling pathway in CAFs might be a potential therapeutic strategy in gastric cancer. However, how the NF-κB pathway is activated in CAFs remains unclear. We showed that mesenchymal stem cells (MSCs) differentiated into CAFs, induced by the exosomes derived from gastric cancer cells. During the process of differentiation from MSCs into CAFs, we showed that nuclear PKM2 expression was continuously upregulated and associated with NF-κB P65 acetylation, contributing to P65 nuclear retention in CAFs and constant transcription of IL-6, IL-8, and other inflammatory factors, thus promoting gastric cancer cell proliferation. We showed that NF-κB P65 acetylation was induced by P300. We showed that nuclear PKM2 was derived from exosomes of gastric cancer cell lines and the positive feedback loop induced by PKM2-P65 combination. It is also proved that P300 inhibitors can inhibit tumor proliferation in an AGS subcutaneous xenograft tumor model. Our study showed that gastric cancer cells influence the continuous activation of the NF-κB signaling pathway in CAFs by secreting gastric cancer exosomes containing PKM2, thus inducing abnormal metabolism and inflammation activation. This study provides a new therapeutic target for CAF normalization or deactivation strategies.

Up-regulation of KLF17 expression increases the sensitivity of gastric cancer to 5-fluorouracil.

It has been reported that the expression of Krüppel-like factor 17 (KLF17) was associated with the occurrence, development, invasion, metastasis and chemotherapy resistance of various tumors. However, the detailed mechanisms by which KLF17 promotes chemotherapy resistance in gastric cancer (GC) have not been fully investigated. In the present study, we collected the GC tissues and non-tumor tissues (matched adjacent normal tissues with corresponding GC tissues) of 60 GC patients, used qRT-PCR, Western blot and immunohistochemistry assay to analyze the relationship between the expression of KLF17 and the clinical pathological data of the patients. The effect of KLF17 on the sensitivity of GC cell lines to 5-fluorouracil (5-FU), and the potential mechanism were detected by MTS assay, Flow cytometry assay, and Western blot. Compared with non-tumor tissues, the expression level of KLF17 in GC tissue was significantly down-regulated, and the expression level of KLF17 in GES-1 cell line and GC cell lines also had a similar trend. Down-regulated expression of KLF17 is related to tumor size, invasion, regional lymph node metastasis, and TNM staging. Furthermore, through upregulating the expression of KLF17, the sensitivity of BGC-823 and SGC-7901 cell lines to 5-FU was obviously increased. Mechanistically, upregulation the expression of KLF17 can inhibit the expressions of P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and B-Cell lymphoma-2 (BCL-2), which have been reported to be associated with drug resistance and cell proliferation. Collectively, these data implied that KLF17 has the biological effect of inhibiting chemotherapy resistance of GC, and it could be a potential strategy for the GC chemotherapy resistance.

The Role of Autophagy in Gastric Cancer Chemoresistance: Friend or Foe?

Gastric cancer is the third most common cause of cancer-related death worldwide. Drug resistance is the main inevitable and vital factor leading to a low 5-year survival rate for patients with gastric cancer. Autophagy, as a highly conserved homeostatic pathway, is mainly regulated by different proteins and non-coding RNAs (ncRNAs) and plays dual roles in drug resistance of gastric cancer. Thus, targeting key regulatory nodes in the process of autophagy by small molecule inhibitors or activators has become one of the most promising strategies for the treatment of gastric cancer in recent years. In this review, we provide a systematic summary focusing on the relationship between autophagy and chemotherapy resistance in gastric cancer. We comprehensively discuss the roles and molecular mechanisms of multiple proteins and the emerging ncRNAs including miRNAs and lncRNAs in the regulation of autophagy pathways and gastric cancer chemoresistance. We also summarize the regulatory effects of autophagy inhibitor and activators on gastric cancer chemoresistance. Understanding the vital roles of autophagy in gastric cancer chemoresistance will provide novel opportunities to develop promising therapeutic strategies for gastric cancer.

MiR-338-3p attenuates oxaliplatin resistance in gastric cancer cells via targeting thrombospondin-1

IntroductionOxaliplatin resistance (OR) as a poor prognostic factor is closely associated with gastric cancer (GC) recurrence and metastasis. The present study aimed to explore the molecular mechanism underlying oxaliplatin-based chemotherapy resistance of GC.Material and methodsTwo acquired OR strains (BGC-823-OR and MGC-803-OR) were generated by long-term oxaliplatin induction. Cell viability, apoptosis, migration and invasion were evaluated using CCK-8, TUNEL staining and transwell assay, respectively. THBS1 as a direct target of miR-338-3p was validated using the bioinformatics algorithm and luciferase reporter assay. qRT-PCR and western blotting were used to measure gene and protein expression, respectively.ResultsmiR-338-3p was significantly down-regulated, and THBS1 protein level was significantly up-regulated in BGC-823-OR and MGC-803-OR cells compared with parental cell lines. Overexpression of miR-338-3p elevated oxaliplatin sensitivity in BGC-823-OR and MGC-803-OR cells. In addition, we revealed that THBS1 was a direct target of miR-338-3p. Overexpression of miR-338-3p or silence of THBS1 inhibited growth, migration and invasion and promoted apoptosis in BGC-823-OR and MGC-803-OR cells.ConclusionsmiR-338-3p appeared to obtund oxaliplatin-based chemotherapy resistance of GC cells by repression of THBS1. The miR-338-3p/ THBS1 signaling axis might be a prospective therapeutic target to mitigate chemotherapy resistance in GC.

MicroRNA-4290 suppresses PDK1-mediated glycolysis to enhance the sensitivity of gastric cancer cell to cisplatin.

The development of chemotherapy resistance significantly impairs the efficiency of chemotherapy, but the underlying mechanisms of chemotherapy resistance in gastric cancer (GC) are complicated and still need to be further explored. Here, we aimed to reveal the effects of miR-4290/PDK1 (pyruvate dehydrogenase kinase 1) axis on chemotherapy resistance of GC in vitro. The expression patterns of miR-4290 in GC tissues and cell lines were determined by real-time quantitative PCR. Kaplan-Meier was used to assess the relationship between miR-4290 expression levels and patients' overall survival. CCK-8 and flow cytometry technologies were applied to detect cell proliferation and apoptosis. The luciferase gene reporter assay was used to evaluate the interaction between miR-4290 and PDK1. miR-4290 was lowly expressed in GC tissues and cell lines, which was closely associated with the shorter overall survival of GC patients. miR-4290 mimics significantly inhibited cell proliferation and induced cell apoptosis, as well as induced a significant reduction in the expression of PDK1. Moreover, miR-4290 significantly inhibited glycolysis and decreased the IC50 value to cisplatin in SGC7901 cells, whereas these effects were abolished and cell apoptosis was promoted when PDK1 was overexpressed. In conclusion, this study revealed that miR-4290 suppressed PDK1-mediated glycolysis to enhance the sensitivity of GC cells to cisplatin.