Chemosensitivity Of Gastric Cancer Research Articles

PAK6 promotes homologous-recombination to enhance chemoresistance to oxaliplatin through ATR/CHK1 signaling in gastric cancer

Chemoresistance remains the primary challenge of clinical treatment of gastric cancer (GC), making the biomarkers of chemoresistance crucial for treatment decision. Our previous study has reported that p21-actived kinase 6 (PAK6) is a prognostic factor for selecting which patients with GC are resistant to 5-fluorouracil/oxaliplatin chemotherapy. However, the mechanistic role of PAK6 in chemosensitivity remains unknown. The present study identified PAK6 as an important modulator of the DNA damage response (DDR) and chemosensitivity in GC. Analysis of specimens from patients revealed significant associations between the expression of PAK6 and poorer stages, deeper invasion, more lymph node metastases, higher recurrence rates, and resistance to oxaliplatin. Cells exhibited chemosensitivity to oxaliplatin after knockdown of PAK6, but showed more resistant to oxaliplatin when overexpressing PAK6. Functionally, PAK6 mediates cancer chemoresistance by enhancing homologous recombination (HR) to facilitate the DNA double-strand break repair. Mechanistically, PAK6 moves into nucleus to promote the activation of ATR, thereby further activating downstream repair protein CHK1 and recruiting RAD51 from cytoplasm to the DNA damaged site to repair the broken DNA in GC. Activation of ATR is the necessary step for PAK6 mediated HR repair to protect GC cells from oxaliplatin-induced apoptosis, and ATR inhibitor (AZD6738) could block the PAK6-mediated HR repair, thereby reversing the resistance to oxaliplatin and even promoting the sensitivity to oxaliplatin regardless of high expression of PAK6. In conclusion, these findings indicate a novel regulatory mechanism of PAK6 in modulating the DDR and chemoresistance in GC and provide a reversal suggestion in clinical decision.

Chemosensitivity of gastric cancer: analysis of key pathogenic transcription factors.

We aimed to screen the key pathogenic transcription factors of gastric cancer and analyzed the correlation between the expression of transcription factors and chemotherapy drugs in gastric cancer. Gastric cancer RNA sequencing data sets, single nucleotide polymorphism data sets, and corresponding clinical data sets were downloaded from The Cancer Genome Atlas, which is public data. The expression of transcription factors in gastric cancer and normal tissues was analyzed with R software. Pathway enrichment analysis of differentially expressed transcription factors was performed using the Kyoto Encyclopedia of Genes and Genomes database. Univariate Cox analysis was used to explore the correlation between the differential expression of transcription factors and prognosis. The interaction network among differentially expressed transcription factors was constructed using String database. Spearman test was used to explore the correlation between transcription factor mutation and gene expression. The Genomics of Drug Sensitivity in Cancer database was used to examine the relationship between the expression of transcription factors and chemotherapeutic drug sensitivity. A total of 17 differentially expressed transcription factors were screened. The results indicated that CENPA, E2F1, EMX1, HOXA9, FOXM1, and MYBL2 were prognostic risk factors for gastric cancer patients (P<0.05), while RXRG and SOX4 were prognostic protective factors for gastric cancer patients (P<0.05). FDXM1 interacted with E2F7, MYBL2, E2F1, NCAPG, and SOX9. FOXM1 gene mutation was positively correlated with the expression level (P<0.05). Based on the median value of FOXM1, the patients were divided into high expression group and low expression group of FOXM1. There was no significant difference in IC50 of 5-fluorouracil between the FOXM1 high expression group and the FOXM1 low expression group (P>0.05). The IC50 of paclitaxel in the FOXM1 high expression group was higher than that in the FOXM1 low expression group (P<0.001). The expression of IC50 of cisplatin in the FOXM1 high expression group was higher than that in the FOXM1 low expression group (P<0.05). FOXM1 was a highly expressed transcription factor in gastric cancer. High FOXM1 expression was associated with the resistance of gastric cancer patients to paclitaxel and cisplatin. Therefore, FOXM1 is a potential therapeutic target for gastric cancer.

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.

Inhibition of MGMT-mediated autophagy suppression decreases cisplatin chemosensitivity in gastric cancer

Cisplatin (DDP) is the first-line drug for the treatment of gastric cancer (GC). However, DDP resistance is common. Autophagy, which is closely related to chemoresistance, is a process of resolving and recycling proteins and damaged cellular organs. Additionally, O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for alkylating drug resistance. However, the relationship between autophagy and MGMT in response to DDP in GC is still unknown. In the present study, we determined that autophagy induced by DDP decreases chemosensitivity in GC cell lines. DDP may have induced autophagy in GC by inhibiting MGMT to increase autophagy-related gene (ATG) 4B. Inhibition of MGMT-mediated ATG4B suppression resulted in autophagy induction and DDP resistance. In vivo, combined DDP and autophagy inhibitor chloroquine (CQ) enhanced the anti-tumor effect of DDP; additionally, the negative correlation of MGMT and ATG4B was confirmed. High expression of MGMT and low expression of ATG4B were significantly correlated with favorable five-year survival rate (P < 0.05) in 66 clinicopathologically characterized GC cases. Our study demonstrate that DDP inhibits MGMT-mediated autophagy suppression to decrease chemosensitivity in GC, which provides a novel therapeutic strategy to promote DDP chemosensitivity in GC.

Inhibition of protein FAK enhances 5-FU chemosensitivity to gastric carcinoma via p53 signaling pathways

The small molecule drug 5-fluorouracil (5-FU) is widely used in the treatment for gastric cancer (GC), however, it exerts poor efficacy and is associated with acquired and intrinsic resistance. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays a key role in adhesion, migration, and proliferation of gastric carcinoma cells, suggesting that this kinase may be a promising therapeutic target. Differentially expressed FAK in GC tissue was detected by RT-qPCR and TCGA database analysis. To investigate the biological functions of FAK, loss-of-function experiments were performed. CCK-8 assay, colony formation assay, flow cytometry, dual-luciferase reporter assays, and western blot assays were conducted to determine the underlying mechanisms of FAK in 5-FU chemosensitivity in GC. FAK is overexpressed in GC patients, and positively correlated with poor prognosis. The use of shRNA interference to target FAK decreased proliferation and increased apoptosis of GC cells in vitro. Importantly, FAK silencing enhanced the therapeutic efficacy of 5-FU, leading to reduced tumor growth in vivo. We further demonstrated that FAK silencing increased 5-FU-induced caspase-3 activity, and promoted p53 transcriptional activities. Clinical data also has shown that patients with higher levels of FAK had significantly shorter overall survival (OS) and time to first progression (FP) than those with lower levels of FAK. These findings indicate that FAK plays a critical role in 5-FU chemosensitivity in GC, and the use of FAK inhibitors as an adjunct to 5-FU might be an effective strategy for patients who undergo chemotherapy.

MicroRNA-495 Confers Increased Sensitivity to Chemotherapeutic Agents in Gastric Cancer via the Mammalian Target of Rapamycin (mTOR) Signaling Pathway by Interacting with Human Epidermal Growth Factor Receptor 2 (ERBB2).

BackgroundIn recent years, the incidence of gastric cancer (GC) has been increasing worldwide. Emerging evidence shows that microRNAs (miRs) may be involved in the pathogenesis of GC. Thus, this study explored the mediatory role of miR-495 in GC chemosensitivity, and investigated the mechanism by which it affects the biological behaviors of GC cells via the mTOR signaling pathway.Material/MethodsAfter GC and paracancerous tissue collection, the positive rate of ERBB2 and mTOR was evaluated by immunohistochemistry. Subsequently, the expression of miR-495, ERBB2, and mTOR was determined by RT-qPCR and Western blot analysis. Next, the targeting relationship between miR-495 and ERBB2 was confirmed by dual-luciferase reporter gene assay. In addition, chemosensitivity and proliferation were detected by MTT assay and apoptosis was assessed by flow cytometry.ResultsWe found higher positive rates of ERBB2 and mTOR and decreased expression of miR-495 in GC tissues and showed that ERBB2 is the target gene of miR-495. Furthermore, we determined that overexpression of miR-495 and silencing of ERBB2 enhanced GC cell chemosensitivity and apoptosis, but inhibited GC cell proliferation. We also found that the effect of miR-495 inhibition was lost when ERBB2 was suppressed.ConclusionsThe key findings of our study demonstrate that the miR-495 exerts promotive effects on GC chemosensitivity via inactivation of the mTOR signaling pathway by suppressing ERBB2. The study provides reliable evidence supporting the use of miR-495 as a novel potential target in the chemotherapy of GC.

Cancer-adipose tissue interaction and fluid flow synergistically modulate cell kinetics, HER2 expression, and trastuzumab efficacy in gastric cancer.

Early local tumor invasion in gastric cancer results in likely encounters between cancer cells and submucosal and subserosal adipose tissue, but these interactions remain to be clarified. Microenvironmental mechanical forces, such as fluid flow, are known to modulate normal cell kinetics, but the effects of fluid flow on gastric cancer cells are poorly understood. We analyzed the cell kinetics and chemosensitivity in gastric cancer using a simple in vitro model that simultaneously replicated the cancer-adipocyte interaction and physical microenvironment. Gastric cancer cells (MKN7 and MKN74) were seeded on rat adipose tissue fragment-embedded discs or collagen discs alone. To generate fluid flow, samples were placed on a rotatory shaker in a CO2 incubator. Proliferation, apoptosis, invasion, and motility-related molecules were analyzed by morphometry and immunostaining. Proteins were evaluated by western blot analysis. Chemosensitivity was investigated by trastuzumab treatment. Adipose tissue and fluid flow had a positive synergistic effect on the proliferative potential and invasive capacity of gastric cancer cells, and adipose tissue inhibited apoptosis in these cells. Adipose tissue upregulated ERK1/2 signaling in gastric cancer cells, but downregulated p38 signaling. Notably, adipose tissue and fluid flow promoted membranous and cytoplasmic HER2 expression and modulated chemosensitivity to trastuzumab in gastric cancer cells. We have demonstrated that cancer-adipocyte interaction and physical microenvironment mutually modulate gastric cancer cell kinetics. Further elucidation of the microenvironmental regulation in gastric cancer will be very important for the development of strategies involving molecular targeted therapy.

Bioinformatic Analysis of GLI1 and Related Signaling Pathways in Chemosensitivity of Gastric Cancer.

BackgroundThis study assessed the prognostic value of GLI1 in gastric cancer and analyzed the possible GLI1-related signaling network in chemosensitivity.Material/MethodsBioinformatic data mining was performed by using data in the TCGA-Stomach Cancer (TCGA-STAD) and the Kaplan-Meier plotter. GLI1 co-expressed genes in TCGA-STAD were subjected to KEGG pathway analysis. The genes enriched in the KEGG pathways were further subjected to Protein-Protein Interaction (PPI) analysis.ResultsIn TCGA-STAD, high GLI1 gene/exon expression was associated with significantly worse survival (p=0.016 and 0.0023 respectively). In the Kaplan-Meier plotter, high GLI1 expression was associated with unfavorable overall survival (OS) (HR: 1.68, 95%CI: 1.42–2, p<0.0001) and first progression-free survival (FPS) (HR: 1.72, 95%CI: 1.4–2.11, p<0.0001). In TCGA-STAD, 600 GLI1 co-expressed genes were identified (absolute Pearson’s r ≥0.5). The most significant pathways were pathways in cancer (p=230.0E-12) and the Hedgehog signaling pathway (p=6.9E-9). PI3K-AKT pathway (p=17.0E-9) has the largest proportion of gene enrichment. Some GLI1 co-expressed genes in the PI3K-AKT pathway are central nodes in the PPI network and also play important roles in chemosensitivity of gastric cancer. Nevertheless, the mechanisms underlying their co-expression are still largely unexplored.ConclusionsHigh GLI1 expression is associated with unfavorable OS and FPS in patients with gastric cancer. As a member of the Hedgehog signaling pathway, GLI1 co-expressed genes are also largely enriched in PI3K/AKT pathway in gastric cancer, which is closely related to chemoresistance. The underlying mechanisms are still largely unexplored and need further study.

Methods and significance of the combined detection of HER2 gene amplification and chemosensitivity in gastric cancer.

This study aims to investigate the significance of combined detection of HER2 gene amplification and chemosensitivity in gastric cancer. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and fluorescence reverse-transcription polymerase chain reaction (RT-PCR) were used to analyze the expression of HER2 protein, HER2 gene amplification and the mRNA expression of ERCC1, TUBB3 and TYMS genes in 135 cases of gastric carcinoma. The expression rate of HER2 protein was 39.3% (53/135). Among these positive cases, patients with HER2 protein (3+) accounted for 9.6% (13/135), patients with HER2 protein (2+) accounted for 13.3% (18/135), and patients with HER2 protein (1+) accounted for 16.3% (22/135). The amplification rate of the HER2 gene was 35.8% (19/53). In the detection of the mRNA expression of ERCC1, TUBB3 and TYMS, 45 patients had low and moderate single gene expression, 50 patients had low and moderate double gene expression, 22 patients had low and moderate mRNA expression for ERCC1, TUBB3 and TYMS, and 18 patients had no low and moderate expression. Among the 53 patients with HER2 protein expression and 22 patients with low and moderate mRNA expression of ERCC1, TUBB3 and TYMS, 12 patients received chemotherapy and trastuzumab. Follow-up results revealed that HER2 gene status was positively correlated with the therapeutic effect of the combined treatment in patients with low mRNA expression of ERCC1, TUBB3 and TYMS. Among these patients, five patients with extensive HER2 (3+), HER2 cluster-specific amplification, and low mRNA expression of ERCC1, TUBB3 and TYMS had a total survival of up to 19.1 months. The detection of HER2 in gastric cancer is highly heterogeneity, and the combined detection of HER2 protein expression, HER2 gene amplification and chemosensitivity can provide important reference markers for the benefit of antitumor drugs.

A metabolomic signature for predicting chemosensitivity in gastric cancer.

e15504 Background: Perioperative chemotherapy (QT) with platinum and fluoropyrimidines with or without anthracyclines is recommended option in patients with resectable gastric cancer (GC) at least cT2 or nodal involvement. Another option is surgery followed by QT with radiotherapy (QT/RT) or QT without RT in patients with D2 lymphadenectomy. Unfortunately, a considerable percentage of patients progress during neoadjuvant-QT (neo-QT) and some cases become inoperable cancer. These patients could benefit from curative surgery after diagnosis without neo-QT. Currently, histological/molecular markers have not been established to predict which patients can benefit from neo-QT. As potent analysis method, study of blood metabolites of resectable GC patients to establish a profile to differentiate responder patients (R-P) or not-responder (NR-P) to neoadjuvant-QT is promising. To establish a metabolomic profile or metabolomic signature and correlate with chemosensitivity, defined as pathological and clinical response is our endpoint. Methods: To this end we performend an untargeted metabolomic analysis by LC-HRMS of serum samples from resectable GC patients before neo-QT (n = 20 vs n = 10 healthy controls). Chemosensitive tumors were defined as those with good pathological response (Mandard 1 or 2) and partial response by TAC and chemoresistance tumors, defined as those with poor pathological response (Mandard 5) or/and progression by TAC. Reverse phase and HILIC chromatographic modes were applied to deal with highly polar as well as hydrophobic as required for untargeted metabolomics. For identification of potential biomarkers, we used in combination 2 independent variable selection techniques: principal component analysis and Student t test. Results: 11 patients were R-P and 9 patients were NR-P. We observed differences in metabolic profile between patients with GC &amp; healthy controls and R-P &amp; NR-P to neo-QT. Seven identified metabolites contributed most to the differentiating between R-P and NR-P. Conclusions: There are different metabolomic phenotypes among patients R-P and NR-P to neo-QT. It is necessary to validate a metabolomic signature to allow effective chemosensitivity prediction in patients with resectable GC.

Relationships of MMP-9, E-cadherin, and VEGF expression with clinicopathological features and response to chemosensitivity in gastric cancer.

The matrix metalloproteinase-9, E-cadherin, and vascular endothelial growth factor play an important role in behavior of tumor cell growth, invasion, and metastasis. In this study, we investigated the relationships of matrix metalloproteinase-9, E-cadherin, and vascular endothelial growth factor expression with clinicopathological features and results of chemosensitivity tested by collagen gel droplet-embedded culture-drug sensitivity test in gastric cancer. Fresh specimens were used for collagen gel droplet-embedded culture-drug sensitivity test and paired fixed specimens were used for immunohistochemistry. Positive expression of matrix metalloproteinase-9 was associated with poorly differentiated carcinoma (p = 0.032), lymph node metastasis (p = 0.022), and tumor stage (p = 0.023). Negative expression of E-cadherin was associated with poorly differentiated carcinoma (p = 0.007), lymph node metastasis (p = 0.012), and tumor stage (p = 0.007). Positive expression of vascular endothelial growth factor was associated with tumor size (p = 0.040) and stage (p = 0.007). Collagen gel droplet-embedded culture-drug sensitivity test was successfully evaluated in 56 patients. Among them, 29 (51.7%) patients were resistant to TS-1 and 31 (55.3%) patients were resistant to L-OHP. The L-OHP resistance rate in vascular endothelial growth factor positive patients was significantly higher than that in negative patients (p = 0.031). The L-OHP resistance rate in E-cadherin negative patients was significantly higher than that in positive patients (p = 0.014). In conclusion, matrix metalloproteinase-9, E-cadherin, and vascular endothelial growth factor were involved in tumor invasion and metastasis. Positive expression of matrix metalloproteinase-9 and vascular endothelial growth factor and negative expression of E-cadherin were malignant markers for gastric cancer. Positive expression of vascular endothelial growth factor and negative expression of E-cadherin were associated with L-OHP resistance.

Plasma mRNA as liquid biopsy predicts chemo-sensitivity in advanced gastric cancer patients.

Predictive biomarkers based individualized chemotherapy can improve efficacy. However, for those advanced patients, it may be impossible to obtain the tissues from operation. Tissues from biopsy may not be always enough for gene detection. Thus, biomarker from blood could be a non-invasive and useful tool to provide real-time information in the procedure of treatment. To further understand the role of plasma mRNA in chemo-efficiency prediction, several mRNA expression levels were assessed in plasma and paired tumor tissues from 133 locally advanced gastric cancer patients (stage III), and mRNA levels were correlated with chemosensitivity to docetaxel, pemetrexed, platinum, and irinotecan. mRNA expression level in 64 advanced gastric cancer patients (stage IV) was also examined (55 in test group, and 9 in control), and chemotherapy in the test group were given according to the plasma gene detection. As a result, in the 133 patients with locally advanced gastric cancer (Stage III), correlations were observed between the mRNA expression of plasma/tumor BRCA1 levels and docetaxel sensitivity (P<0.001), plasma/tumor TS and pemetrexed sensitivity (P<0.001), plasma/tumor BRCA1 and platinum sensitivity (plasma, P=0.016; tumor, P<0.001), and plasma/tumor TOPO1 and irinotecan sensitivity (plasma, P=0.015; tumor, P=0.011). Among another 64 patients with advanced cancer (Stage IV), the median OS of test group was 15.5m (95% CI=10.1 to 20.9m), the PFS was 9.1m (95% CI=8.0 to 10.2m), which were significant longer than the control (P=0.047 for OS, P=0.038 for PFS). The mortality risk was higher in the control than patients treated according to the plasma gene detection (HR in the control=2.34, 95% CI=0.93 to 5.88, P=0.071). Plasma mRNA as liquid biopsy could be ideal recourse for examination to predict chemo-sensitivity in gastric cancer.

Significance of combined detection ofHER2gene amplification and markers of chemosensitivity in gastric cancer

Significance of combined detection of<i>HER2</i>gene amplification and markers of chemosensitivity in gastric cancer

Role of RNA-interference-induced zinc finger protein 139 suppression in gastric cancer cell sensitivity to chemotherapeutic agents.

Zinc finger proteins (ZNFs) are a class of proteins widely distributed in the human genome, which have been found to play a role in the regulation of gene transcription and the occurrence and development of gastric cancer (GC). ZNF139 was found to be associated with GC in our previous experiments. The present study aimed to analyse the differences in ZNF139 protein expression in SGC7901 GC cells and in situ grafted GC tumors in nude mice prior to and following RNA interference inhibition, and to investigate the mechanisms underlying ZNF139 involvement in the occurrence, development and chemosensitivity of GC. A ZNF139-targeted small interfering (si)RNA plasmid was constructed and transfected into the cancer cells and in situ grafted tumors. The MTT assay was used to investigate the alterations in chemosensitivity prior to and following transfection of siRNA-ZNF139. The two-dimensional difference gel electrophoresis and liquid chromatography-mass spectrometry techniques were used to identify the different protein points prior to and following siRNA-ZNF139 transfection. Western blot analysis was performed to confirm the identified proteins. In the siRNA-ZNF139 group, the growth of the cancer cells and in situ grafted tumors significantly decreased. However, the post-interference chemosensitivity to 5-fluorouracil, cisplatin and mitomycin C significantly increased. In the in vivo and in vitro experiments, the expression of pyridoxal kinase (PDXK) was upregulated, whereas the expression levels of annexin A2 (ANXA2) and fascin were downregulated following transfection. Western blot analysis confirmed the results for PDXK, ANXA2 and fascin by proteomics. Therefore, ZNF139 may participate in the occurrence, development and chemosensitivity of GC by promoting the expression of ANXA2 and fascin, while inhibiting the expression of PDXK.

Gene signature in plasma and tumor to predict irinotecan chemosensitivity in gastric cancer.

e15098 Background: Personalized chemotherapy based on molecular biomarkers can maximize efficiency and reduce adverse effects. We investigated and validated predictive biomarkers for irinotecan and...

MicroRNA-185 regulates chemotherapeutic sensitivity in gastric cancer by targeting apoptosis repressor with caspase recruitment domain.

Gastric cancer remains the second leading cause of cancer deaths worldwide. Resistance to chemotherapy is a significant barrier for effective cancer treatment. Here, we identified miR-185 to be a contributor to chemosensitivity in gastric cancer. We observed low levels of miR-185 in gastric cancer cell lines and clinical tissues, compared with gastric epithelium cell line and noncancerous tissues. Furthermore, enforced expression of miR-185 increased the sensitivity of gastric cancer cells to low-dose chemotherapeutic agents, which alone cannot trigger significant apoptosis. Conversely, knockdown of endogenous miR-185 prevented high-dose chemotherapy-induced apoptosis. In elucidating the molecular mechanism by which miR-185 participated in the regulation of chemosensitivity in gastric cancer, we discovered that apoptosis repressor with caspase recruitment domain (ARC) is a direct target of miR-185. The role of miR-185 was confirmed in gastric tumor xenograft model. The growth of established tumors was suppressed by a combination therapy using enforced miR-185 expression and a low dose of anticancer drugs. Finally, we found that RUNX3 (Runt-related transcription factor) was involved in the activation of miR-185 at the transcriptional level. Taken together, our results reveal that RUNX3, miR-185 and ARC regulate the sensitivity of gastric cancer cells to chemotherapy.

Reversion of multidrug resistance of human gastric cancer SGC7901/DDP cells by E2F-1 gene silencing

To investigate the effects of E2F-1 gene silencing on multidrug resistance of human gastric cancer SGC7901/DDP cells and its possible mechanisms. Gastric cancer SGC7901/DDP cells were seeded in 6 well plates and divided into three groups: the experimental group, blank control and the negative control groups. For the experimental group, the SGC7901/DDP cells were transfected with recombinant lentivirus vector (Lv-shRNA-E2F-1), while the negative control with an control lentiviral vector (Lv-shRNA-NC) and the blank control with no treatment. The E2F-1 protein level was analyzed by Western blot. MTT assay was used to detect the half maximal inhibitory concentration (IC50) of three chemotherapy drugs including adriamycin, 5-fluorouracil (5-Fu) and cisplatine (DDP) of the three cell groups. Flow cytometry (FCM) was used to detect the pump-out rate of adriamycin and apoptosis rate of the three cell groups. Semi-quantitative RT-PCR and Western blot were also used to detect the protein and mRNA levels of multidrug resistance-associated genes (MDR1, MRP) and apoptosis-related genes (c-Myc, Skp2, cyclinD1). The expression of E2F-1 protein in the experimental group was significantly lower than that in the negative control and blank control groups (0.794 ± 0.033 vs. 1.487 ± 0.082 vs. 1.511 ± 0.084, P < 0.01). The IC50 of the three chemotherapy drugs (adriamycin, 5-Fu and cisplatine) in the experimental group was significantly lower than that of the negative control and blank control groups, respectively (P < 0.01). Compared with the negative control and blank control groups, the pump-out rate of adriamycin of the experimental group was significantly declined [(0.16 ± 0.01)% vs. (0.37 ± 0.01)% vs. (0.35 ± 0.02)%, P < 0.01]. However, the apoptosis rate of the experimental group was significantly higher than that of the negative control and blank control groups [(33.82 ± 1.26)% vs. (17.34 ± 0.81)% vs. (13.16 ± 1.06)%, P < 0.01]. The results of RT-PCR and Western blot assays showed that mRNA and protein expressions of five genes (MDR1, MRP, CyclinD1, c-Myc, Skp2) in the experimental group were significantly lower than that in the negative control and blank control groups, respectively (P < 0.01). E2F-1 gene silencing enhances the chemosensitivity of gastric cancer SGC7901/DDP cells to the chemotherapeutic drugs, directly or indirectly downregulated the expression of MDR1 and MRP, and finally reverses the multidrug resistance of the gastric cancer cells. The mechanism may be associated with the suppression of cyclinD1, c-Myc and Skp2.

Correlation between the methylation of SULF2 and WRN promoter and the irinotecan chemosensitivity in gastric cancer

BackgroundAt present, no study has compared the correlation between SULF2, WRN promoter methylation and clinicopathological parameters of patients with gastric cancer and the sensitivity to irinotecan (CPT-11).MethodsWe collected 102 fresh tumor tissues from pathologically diagnosed gastric carcinoma patients. Methylation specific PCR was used to detect the promoter methylation of SULF2 and WRN. The chemosensitivity of irinotecan to gastric tomor was tested by MTT. Then we compared the chemosensitivity difference of the methylated group with unmethylated group.ResultsThe rates of SULF2, WRN methylation were 28.3% (29/102) and 23.6% (24/102), separately. Patients with SULF2 methylation were more sensitive to CPT-11 than those without SULF2 methylation (P < 0.01). Patients with both SULF2 and WRN methylation were also more sensitive to CPT-11 than others ( P < 0.05).ConclusionSULF2 and WRN promoter methylation detection indicates potential predictive biomarkers to identify and target the most sensitive gastric cancer subpopulation for personalized CPT-11 therapy.

Silencing of XB130 Is Associated with Both the Prognosis and Chemosensitivity of Gastric Cancer

XB130 is a newly characterized adaptor protein that was reported to promote thyroid tumor growth, but its role in the progression of other kinds of cancer such as gastric cancer (GC) remains unknown. Accordingly, we investigated the association between XB130 expression and the prognosis of GC patients. The subjects were 411 patients with GC in stages I to IV. XB130 expression was examined in surgical specimens of GC. Kaplan-Meier analysis and the Cox proportional hazards model were used to assess the prognostic significance of XB130 for survival and recurrence. Moreover, GC cells stably transfected with XB130 short hairpin RNA were established to analyze the effect of XB130 on sensitivity of chemotherapy. The results show that both XB130 mRNA and protein expression were detectable in normal gastric tissues. The overall survival time of stage IV patients and the disease-free period after radical resection of GC in stage I–III patients were significantly shorter when immunohistochemical staining for XB130 was low than when staining was high (both p<0.05). XB130 expression also predicted tumor sensitivity to several chemotherapy agents. Viability of both XB130-silenced SGC7901 cells and wild-type cells was suppressed by 5-fluorouracil (5-FU), cisplatin, and irinotecan in a dose-dependent way, but cisplatin and irinotecan were more sensitive against sXB130-silenced GC cells and 5-FU showed higher sensitivity to wild-type cells. When treated by 5-FU, patients with high expression of XB130 tumors had a higher survival rate than those with low expression tumors. These findings indicate that reduced XB130 protein expression is a prognostic biomarker for shorter survival and a higher recurrence rate in patients with GC, as well as for the response to chemotherapy.

Abstract 1916: Blockade of the fibroblast growth factor receptor (FGFR) system by the novel FGFR inhibitor BGJ398 modulates oncogenic signaling in human gastric cancer cells, endothelial cells and pericytes

Abstract Expression of the FGFR system has been associated with poor prognosis in patients suffering from gastric cancer. Moreover, activation of FGFRs has been demonstrated to mediate tumor angiogenesis through regulation of endothelial cell (EC) and pericyte motility and survival. Therefore, in this study we sought to investigate the effects of targeting FGFR on gastric cancer cells as well as on important components of the tumor microenvironment by the novel FGFR inhibitor BGJ398. For the experiments, human gastric cancer cell lines (TMK-1 and KKLS) as well as ECs and pericytes (vascular smooth muscle cells, VSMCs) were used. The FGFR inhibitor BGJ398 was provided by Novartis Oncology (Basel, Switzerland). Effects of BGJ398 on tumor cell growth and chemoresistance were determined by MTT assays. Impact of BGJ398 on motility of cancer cells was evaluated by modified Boyden chambers. Signaling pathways affected by BGJ398 treatment were assessed by Western blot analyses. To determine effects of FGFR blockade on ECs and pericytes conditioned media from gastric cancer cells was used. Results show that targeting FGFR by BGJ398 impaired growth of gastric cancer cells in a dose-dependent manner in vitro. Furthermore, activation of Akt and Erk in cancer cells was effectively inhibited while expression of c-Myc and HIF-1α was substantially reduced. Additionally, therapy with BGJ398 led to significant inhibition of constitutive migratory and invasive properties of gastric cancer cells (P&amp;lt;0.05). Interestingly, interference with FGFR by BGJ398 increased sensitivity for chemotherapy with oxaliplatin and 5-FU in tumor cells. In ECs as well as pericytes blockade of FGFR by BGJ398 significantly inhibited cell growth and motility even upon stimulation with conditioned media (P&amp;lt;0.05). In conclusion, inhibition of the FGFR system by BGJ398 disrupts oncogenic signaling, impairs tumor cell motility and improves chemosensitivity in gastric cancer. Furthermore, antiangiogenic effects might be mediated via direct effects on ECs and pericytes. Hence, targeting the FGFR system may represent a promising approach to improve current therapy strategies for gastric cancer and warrants further preclinical evaluation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1916. doi:1538-7445.AM2012-1916