Retracted: Upregulation of Serine Proteinase Inhibitor Clade B Member 3 (SERPINB3) Expression by Stromal Cell-Derived Factor (SDF-1)/CXCR4/Nuclear Factor kappa B (NF-κB) Promotes Migration and Invasion of Gastric Cancer Cells.

The Editors of Medical Science Monitor wish to inform you that the above manuscript has been retracted from publication due to concerns with the credibility and originality of the study, the manuscript content, and the Figure images. Reference: Jing Gong, Yongxi Song, Ling Xu, Xiaofang Che, Kezuo Hou, Tianshu Guo, Yu Cheng, Yunpeng Liu, Xiujuan Qu. Upregulation of Serine Proteinase Inhibitor Clade B Member 3 (SERPINB3) Expression by Stromal Cell-Derived Factor (SDF-1)/CXCR4/Nuclear Factor kappa B (NF-kB) Promotes Migration and Invasion of Gastric Cancer Cells. Med Sci Monit, 2020; 26: e927411. DOI: 10.12659/MSM.927411.

Elevated blood and cerebrospinal fluid biomarkers of microglial activation and blood‒brain barrier disruption in anti-NMDA receptor encephalitis.

BACKGROUND: Anti-NMDA receptor (NMDAR) encephalitis is an autoimmune disease characterized by complex neuropsychiatric syndrome and cerebrospinal fluid (CSF) NMDAR antibodies. Triggering receptor expressed on myeloid cells 2 (TREM2) has been reported to be associated with inflammation of the central nervous system (CNS). Matrix metalloproteinase-9 (MMP9) and cluster of differentiation (CD44) were measured to evaluate blood‒brain barrier (BBB) permeability in anti-NMDAR encephalitis. The roles of microglial activation and BBB disruption in anti-NMDAR encephalitis are not well known. FINDINGS: In this work, we detected increased expression levels of CSF sTREM2, CSF and serum CD44, and serum MMP9 in anti-NMDAR encephalitis patients compared with controls. CSF sTREM2 levels were positively related to both CSF CD44 levels (r = 0.702, p < 0.0001) and serum MMP9 levels (r = 0.428, p = 0.021). In addition, CSF sTREM2 levels were related to clinical parameters (modified Rankin Scale scores, r = 0.422, p = 0.023, and Glasgow Coma Scale scores, r = - 0.401, p = 0.031). CONCLUSION: Increased sTREM2 levels in CSF as well as increased CD44 and MMP9 in serum and CSF reflected activation of microglia and disruption of the BBB in anti-NMDAR encephalitis, expanding the understanding of neuroinflammation in this disease. The factors mentioned above may have potential as novel targets for intervention or novel diagnostic biomarkers.

Soluble TREM2 is a potential biomarker for the severity of primary angiitis of the CNS.

Background: Primary angiitis of the central nervous system (PACNS) is a severe inflammatory disease, and soluble triggering receptor expressed on myeloid cells 2 (sTREM2) has been reported to be associated with inflammation of the CNS. However, the role of sTREM2 in PACNS remains unknown. Methods: We obtained serum and cerebrospinal fluid (CSF) samples from 18 patients diagnosed with PACNS, as well as 14 patients diagnosed with other neurological disorders with no evidence of inflammation. sTREM2 concentrations in the samples were detected by enzyme-linked immunosorbent assay. And routine CSF measurements of PACNS patients were analysed, including number of White Blood Cells (WBC), protein, Immunoglobulin G (IgG) index and CSF/serum quotients. Levels of inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-6, IL-8, IL-1ß, and complement C4, also were tested. The modified Rankin scale (mRS), National Institutes of Health Stroke Scale (NIHSS), and activities of daily living (ADL) scores were obtained as indicators of disease severity. In PACNS patients, cerebral lesion volume was evaluated by magnetic resonance imaging. Results: sTREM2 levels in serum and CSF were significantly elevated in PACNS patients and significantly associated with the mRS, NIHSS and ADL scores as well as inflammatory cytokine levels. Additionally, positive correlations were observed between the cerebral lesion volume and the sTREM2 levels in both blood and CSF. Higher sTREM2 levels in either the blood or CSF seemed to predict a good prognosis in PACNS patients. Conclusion: Our results indicate an association between serum and CSF sTREM2 levels and the severity of neurological damage. Thus, sTREM2 represents a potential biomarker for monitoring disease and potentially predicting the prognosis of PACNS patients.

NR2F1-AS1/miR-190a/PHLDB2 Induces the Epithelial-Mesenchymal Transformation Process in Gastric Cancer by Promoting Phosphorylation of AKT3.

The median survival time of patients with advanced gastric cancer (GC) who received radiotherapy and chemotherapy was <1 year. Epithelial-mesenchymal transformation (EMT) gives GC cells the ability to invade, which is an essential biological mechanism in the progression of GC. The long non-coding RNA (lncRNA)-based competitive endogenous RNA (ceRNA) system has been shown to play a key role in the GC-related EMT process. Although the AKT pathway is essential for EMT in GC, the relationship between AKT3 subtypes and EMT in GC is unclear. Here, we evaluated the underlying mechanism of ceRNA involving NR2F1-AS1/miR-190a/PHLDB2 in inducing EMT by promoting the expression and phosphorylation of AKT3. The results of bioinformatics analysis showed that the expression of NR2F1-AS1/miR-190a/PHLDB2 in GC was positively associated with the pathological features, staging, poor prognosis, and EMT process. We performed cell transfection, qRT-PCR, western blot, cell viability assay, TUNEL assay, Transwell assay, cell morphology observation, and double luciferase assay to confirm the regulation of NR2F1-AS1/miR-190a/PHLDB2 and its effect on EMT transformation. Finally, GSEA and GO/KEGG enrichment analysis identified that PI3K/AKT pathway was positively correlated to NR2F1-AS1/miR-190a/PHLDB2 expression. AKT3 knockout cells were co-transfected with PHLDB2-OE, and the findings revealed that AKT3 expression and phosphorylation were essential for the PHLDB2-mediated EMT process. Thus, our results showed that NR2F1-AS1/miR-190a/PHLDB2 promoted the phosphorylation of AKT3 to induce EMT in GC cells. This study provides a comprehensive understanding of the underlying mechanism involved in the EMT process as well as the identification of new EMT markers.

Comparative Analysis and in vitro Experiments of Signatures and Prognostic Value of Immune Checkpoint Genes in Colorectal Cancer.

PURPOSE: Immune checkpoints, as pivotal regulators of immune escape in cancer, can motivate the emergence of immune checkpoint inhibitors (ICIs). The aim of this study is to identify the expression of the immune checkpoint genes (ICGs) in colorectal cancer (CRC) and to relate their individual as well as combined expression to prognosis and therapeutic effectiveness in CRC. METHODS: RNA expression of 47 ICGs and clinical information of CRC patients were collected from two public databases to elucidate the expression levels and prognostic values of these ICGs in CRC. Then, the Shapiro-Wilk normality test was used to determine the normality of variables. Overall survival (OS) rates of each subset were found by Kaplan-Meier method, and the statistical significance was determined by the Log rank test (p < 0.05). RESULTS: The expression of 13 and 9 ICGs was significantly associated with CRC prognosis in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) cohorts. A series of ICGs was found to be significantly associated with TMB, neoantigens and MMR in CRC indicating that the combination of immunotherapy treatment biomarkers and ICGs may achieve accurate prognostic stratification of CRC, and potentially identify CRC cases that might respond to checkpoint inhibitors (CPIs). The subsets of high or low PD1/PD-L1/IDO1 expression stratified by CD48 were accurately associated with prognosis in CRC. In addition, in vitro experiments confirmed that VTCN1(B7-H4)-KD increases anti-PD-L1-mediated NK cell cytotoxicity on CRC tumor cells. CONCLUSION: Although the expression of a single immune-checkpoint molecule does not predict the efficacy of immunotherapy in CRC, our findings infer that subsets defined by ICGs are associated with prognosis and imply the possibility that VTCN1 and CD48 serve as new immunotherapeutic targets.

Construction of an immune-related gene signature to predict survival and treatment outcome in gastric cancer.

Immune cells have emerged as key regulators in the occurrence and development of multiple tumor types. However, it is unclear whether immune-related genes (IRGs) and the tumor immune microenvironment can predict prognosis for patients with gastric cancer (GC). The mRNA expression data in GC tissues (n = 368) were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed IRGs in patients with GC were determined using a computational difference algorithm. A prognostic signature was constructed using COX regression and random survival forest (RSF) analyses. In addition, datasets related to "gemcitabine resistance" and "trastuzumab resistance" (GSE58118 and GSE77346) were obtained for GEO database, and DEGs associated with drug-resistance were screened. Then, we analyzed correlations between gene expression and cancer immune infiltrates via Tumor Immune Estimation Resource (TIMER) site. The cBioportal database was used to analyze drug-resistant gene mutation status and survival. One hundred and fifty-five differentially expressed IRGs were screened between GC and normal tissues, and a prognostic signature consisting of four IRGs (NRP1, PPP3R1, IL17RA, and FGF16) was closely related to the overall survival (OS). According to cutoff value of risk score, patients were divided into high-risk and low-risk group. Patients in the high-risk group had shorter OS compared to the low-risk group in both the training (p < 0.0001) and testing sets (p = 0.0021). In addition, we developed a 5-IRGs (LGR6, DKK1, TNFRSF1B, NRP1, and CXCR4) signature which may participate in drug resistance processes in GC. Survival analysis showed that patients with drug-resistant gene mutations had shorter OS (p = 0.0459) and DFS (p < 0.001). We constructed four survival-related IRGs and five IRGs related to drug resistance which may contribute to predict the prognosis of GC.

Upregulation of Serine Proteinase Inhibitor Clade B Member 3 (SERPINB3) Expression by Stromal Cell-Derived Factor (SDF-1)/CXCR4/Nuclear Factor kappa B (NF-κB) Promotes Migration and Invasion of Gastric Cancer Cells.

BACKGROUND Serine proteinase inhibitor clade B member 3 (SERPINB3) is a neutral glycoprotein. Its overexpression is related to the promotion of cell proliferation and activation via the nuclear factor kappa B (NF-kappaB) pathway in several tumors. Whether it can participate in stromal cell-derived factor (SDF-1)/NF-kappaB-induced metastasis of gastric cancer has not been reported. MATERIAL AND METHODS We analyzed the ability of SDF-1 to induce migration and invasion in vitro by knocking down the expression of SERPINB3 with siRNAs in gastric cancer cells. We also explored the effects of a CXCR4 antagonist and NF-kappaB inhibitor on SERPINB3 expression. We verified the effect of SERPINB3 on prognosis in gastric cancer specimens by immunohistochemistry. RESULTS In vitro experiments confirmed that SDF-1 upregulated the expression of SERPINB3 and promoted metastasis in gastric cancer cells. This phenomenon was reversed by knockdown of SERPINB3, a chemokine receptor 4 (CXCR4) antagonist, and an NF-kappaB inhibitor, which downregulated the expression of SERPINB3. In patients with gastric cancer, a significant positive correlation was observed between CXCR4 and SERPINB3 expression (r=0.222, P=0.029). Moreover, double positivity for SERPINB3 and CXCR4 was certified to be an independent prognostic factor (HR=3.332, P<0.001). CXCR4-positive patients who also expressed SERPINB3 were inclined to suffer from lymph node metastasis, confirming that SERPINB3 is a downstream molecule of CXCR4. CONCLUSIONS In vitro and pathological results showed that SDF-1/CXCR4 activated the NF-kappaB pathway and upregulated SERPINB3 to facilitate the migration and invasion of gastric cancer cells.

Positive Cross-Talk Between CXC Chemokine Receptor 4 (CXCR4) and Epidermal Growth Factor Receptor (EGFR) Promotes Gastric Cancer Metastasis via the Nuclear Factor kappa B (NF-kB)-Dependent Pathway.

BACKGROUND Previous studies have established cross-talk between CXC chemokine receptor 4 (CXCR4) and epidermal growth factor receptor (EGFR) in gastric cancer, however, the effect of dual CXCR4/EGFR tumor status on patient survival and mechanisms regulating expression has yet to be investigated. MATERIAL AND METHODS A total of 56 gastric cancer patients were recruited to reveal the relationship between CXCR4 and EGFR expression, and the clinic-pathological features of samples were investigated by immunohistochemical staining. Two gastric cancer cell lines were treated with CXCL12 or EGF, and expression levels of CXCR4 and EGFR were detected by reverse-transcription-polymerase chain reaction and western blotting. Cells were treated with an NF-kappaB pathway inhibitor to investigate its role in the regulation of CXCL12 or EGF-mediated CXCR4 and EGFR expression and migration ability. RESULTS The results show that CXCL12 upregulated CXCR4 and EGFR. Similarly, EGF could induce the expression of CXCR4 and contribute to gastric cancer cell metastasis. In addition, both CXCL12 and EGF could induce the activation of IKKalphaß and P65. Conversely, suppression of the NF-kappaB pathway remarkably decreased the expression of CXCR4/EGFR and migration ability induced by EGF or CXCL12. Furthermore, a significantly positive correlation between CXCR4 and EGFR expression was observed in gastric cancer patient tissues (r=0.372, P=0.005). Samples expressing both receptors had significantly poorer patient prognosis than other patient groups (P=0.002). CONCLUSIONS Our results showed that the CXCL12/CXCR4 and EGF/EGFR axis can regulate the expression of each other through the NF-kappaB pathway to promote metastasis. These data suggested that simultaneous inhibition of EGFR and CXCR4 may be a potential therapeutic strategy in gastric cancer.

PD-L1 Under Regulation of miR-429 Influences the Sensitivity of Gastric Cancer Cells to TRAIL by Binding of EGFR.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has received extensive attention as a cancer therapeutic due to its high propensity for tumor targeting with minimal toxicity to healthy tissue. Gastric cancer (GCa) cells show high levels of TRAIL resistance. Epidermal growth factor receptor (EGFR) antagonizes TRAIL-induced apoptosis, but the mechanisms of these effects remain unclear. Our past research confirmed TRAIL-resistant (BGC823 and SGC7901) and TRAIL-sensitive cells (HGC27 and MKN45). miR-429 associated with TRAIL sensitivity was screened using microRNA arrays. The transfection of mimics and inhibitors confirmed that miR-429 negatively correlated with GCa TRAIL resistance. The target gene of miR-429 was identified as PD-L1, which positively correlated with TRAIL resistance through gene silencing and recovery experiments. Using co-immunoprecipitation (co-IP) and proximity ligation assay, we demonstrated that the pro-survival effects of PD-L1 are mediated through the binding and activation of EGFR. Cell viability experiments demonstrated that PD-L1 is key to the maintenance of cell viability in TRAIL-treated cells. This indicated that PD-L1 binds to and participates in EGFR activation through miR-429 regulation to antagonize TRAIL-induced apoptosis. This provides a new theoretical basis for the combination of the EGFR monoclonal antibodies including cetuximab, PD-L1 inhibitors, and human recombinant TRAIL in gastric cancer therapy and can filter patients who are currently sensitive to TRAIL treatment.

Identification of Key Gene and Pathways for the Prediction of Peritoneal Metastasis of Gastric Cancer by Co-expression Analysis.

Peritoneal metastasis is the most common pattern in advanced gastric cancer and can predict poor disease prognosis. Early detection of peritoneal tumor dissemination is restricted by small peritoneal deposits. Therefore, it is critical to identify a novel predictive marker and to explore the potential mechanism associated with this process. In the present study, one module that correlated with peritoneal metastasis was identified. Enrichment analysis indicated that the Focal adhesion and the PI3K-Akt signaling pathway were the most significant pathways. Following network and Molecular Complex Detection (MCODE) analysis, the hub-gene cluster that consisted of 19 genes was selected. Methionine sulfoxide reductase B3 (MSRB3) was identified as a seed gene. Survival analysis indicated that high expression levels of MSRB3 were independent predictors of peritoneal disease-free survival (pDFS) as determined by univariate (HR 8.559, 95% CI; 3.339-21.937; P<.001) and multivariate Cox analysis (HR 3.982, 95% CI; 1.509-10.509; P=.005). Furthermore, patients with high levels of MSRB3 exhibited a significantly lower Overall Survival (OS) (log-rank P = 0.007). The external validation was performed by the (The Cancer Genome Atlas (TCGA)) (log-rank P = 0.037) and Kaplan Meier-plotter (KMplotter) (log-rank P = 0.031) data. In vitro experiments confirmed that MSRB3 was a critical protein in regulating gastric cancer cell proliferation and migration. In conclusion, High expression levels of MSRB3 in GC can predict peritoneal metastasis and recurrence as well as poor prognosis. Furthermore, MSRB3 was involved in the regulation of the proliferation and migration of GC cells.

Role of abnormal microRNA expression in Helicobacter pylori associated gastric cancer.

Epidemiological studies have shown that Helicobacter pylori (HP) infection is a risk factor for gastric cancer (GC). HP infection may induce the release of pro-inflammatory mediators, and abnormally increase the level of reactive oxygen species (ROS), nitric oxide (NO), and cytokines in mucosal epithelial cells of the stomach. However, the specific mechanism underlying the pathogenesis of HP-associated GC is still poorly understood. Recent studies have revealed that abnormal microRNA expression may affect the proliferation, differentiation, and apoptosis of mucosal epithelial cells of the stomach to further influence GC occurrence, development, and metastasis. Herein, we summarize the role of abnormal microRNAs in the regulation of HP-associated GC progression. Abnormal microRNA expression in HP-positive GC may be a biomarker for GC diagnosis, occurrence, and development as well as its targeted treatment and prognosis.

A Clinical Prognostic Score to Predict Survival of Advanced or Metastatic Non-Small Cell Lung Cancer (NSCLC) Patients Receiving First-Line Chemotherapy: A Retrospective Analysis.

BACKGROUND Although several complicated models have been built to evaluate the prognosis of NSCLC patients receiving chemotherapy, simple economic models are still needed to give a preliminary survival assessment of these patients. MATERIAL AND METHODS This study retrospectively assessed the clinical and biological parameters of 223 patients with advanced NSCLC. Univariate and multivariate analyses of overall survival (OS) and progression-free survival (PFS) for the parameters and the prognostic score were assessed. RESULTS Performance status (PS) score=1, smoking history, fibrinogenemia, thrombocytosis, increased lactate dehydrogenase (LDH) level, and anemia were independent predictors of poor prognosis in the univariate analysis of OS and were assessed in multivariate analysis. There was a significant difference in PS=1 (HR=2.134, p<0.0001), increased LDH level (HR=1.508, p=0.014), thrombocytosis (HR=1.547, p=0.012), and smoking history (HR=1.491, p=0.008), based on which the patients were classified into 3 risk groups: low risk (0-1 points), moderate risk (2 points), and high risk (3-5 points). At p values of <0.0001, the median OS was 565, 340, and 273 days and the median progression-free survival was 250, 209, and 135 days, respectively in these 3 risk groups. CONCLUSIONS We established a new prognostic score model using PS, LDH level, PLT count, and smoking history to predict the survival of patients receiving first-line chemotherapy for advanced NSCLC, which might be useful in clinical practice.

ß-elemene increases the sensitivity of gastric cancer cells to TRAIL by promoting the formation of DISC in lipid rafts.

ß-Elemene, an anti-cancer drug extracted from traditional Chinese medicinal herb, showed anti-tumor effects on gastric cancer cells. Our previous studies reported gastric cancer cells are insensitive to TRAIL. However, whether ß-elemene could enhance anti-cancer effects of TRAIL on gastric cancer cells is unknown. In our present study, ß-elemene prevented gastric cancer cell viability in dose-dependent manner, and when combined with TRAIL, obviously inhibited proliferation and promoted apoptosis in gastric cancer cells. Compared to ß-elemene or TRAIL alone, treatment with ß-elemene and TRAIL obviously promoted DR5 clustering as well as translocation of Caspase-8, DR5 and FADD into lipid rafts. This led to cleavage of Caspase-8 and the formation of death-inducing signaling complex (DISC) in lipid rafts. The cholesterol-sequestering agent nystatin partially reversed DR5 clustering and DISC formation, preventing apoptosis triggered by the combination of ß-elemene and TRAIL. Our results suggest that ß-elemene increases the sensitivity of gastric cancer cells to TRAIL partially by promoting the formation of DISC in lipid rafts.

AZ304, a novel dual BRAF inhibitor, exerts anti-tumour effects in colorectal cancer independently of BRAF genetic status.

BACKGROUND: BRAF mutation is associated with poor clinical outcome of patients with malignant tumours, and mediates resistance to chemotherapy and targeted therapy. This study aimed to determine whether V600E mutant and wild type BRAF colorectal cancers exhibit distinct sensitivities to the dual BRAF inhibitor AZ304. METHODS: Kinase activity was assessed by the AlphaScreen assay. Then, MTT assay, EdU assay, colony-formation assay and Western blot were performed to evaluate the anti-tumour effects of AZ304 in vitro. In vivo efficacy was investigated by xenograft analysis and immunohistochemistry. RESULTS: AZ304 exerted potent inhibitory effects on both wild type and V600E mutant forms of the serine/threonine-protein kinase BRAF, with IC50 values of 79 nM and 38 nM, respectively. By suppressing ERK phosphorylation, AZ304 effectively inhibited a panel of human cancer cell lines with different BRAF and RAS genetic statuses. In selected colorectal cancer cell lines, AZ304 significantly inhibited cell growth in vitro and in vivo, regardless of BRAF genetic status. In addition, the EGFR inhibitor Cetuximab enhanced the potency of AZ304 independently of BRAF mutational status. CONCLUSIONS: The BRAF inhibitor AZ304 has broad spectrum antitumour activity, which is significantly enhanced by combination with Cetuximab in colorectal cancers in vitro and in vivo.

miR-200a enhances TRAIL-induced apoptosis in gastric cancer cells by targeting A20.

Tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) triggers apoptosis by inducing the death-inducing signaling complex (DISC) formation. Recently, TNFα-induced protein 3 (TNFAIP3, A20) was reported to prevent TRAIL-induced caspase 8 cleavage in the DISC by mediating ubiquitination of RIP1 in glioblastoma. However, whether A20 regulates caspase 8 cleavage in the DISC when TRAIL induces apoptosis in gastric cancer cells is unknown. In the present study, A20 interacted with RIP1 and DR4 in MGC803 and SGC7901 gastric cancer cells. Treatment with TRAIL promoted the A20-mediated polyubiquitination of RIP1, caspase 8 translocation into the DISC, and the interaction between caspase 8 and ubiquitinated RIP1. Inhibition of A20 expression prevented the polyubiquitination of RIP1 and promoted caspase 8 cleavage. Moreover, our data clarified that A20 is a target of miR-200a. Overexpression of miR-200a inhibited A20 expression and polyubiquitination of RIP1 and then promoted cleavage of caspase 8 and TRAIL-triggered apoptosis. Taken together, our results indicate that miR-200a enhanced TRAIL-triggered apoptosis in gastric cancer cells by targeting A20.

DR5-Cbl-b/c-Cbl-TRAF2 complex inhibits TRAIL-induced apoptosis by promoting TRAF2-mediated polyubiquitination of caspase-8 in gastric cancer cells.

Ubiquitination of caspase-8 regulates TNF-related apoptosis-inducing ligand (TRAIL) sensitivity in cancer cells, and the preligand assembly complex plays a role in caspase-8 polyubiquitination. However, whether such a complex exists in gastric cancer cells and its role in TRAIL-triggered apoptosis is unclear. In this study, DR5, casitas B-lineage lymphoma-b (Cbl-b)/c-Cbl, and TRAF2 formed a complex in TRAIL-resistant gastric cancer cells, and Cbl-b and c-Cbl were the critical adaptors linking DR5 and TRAF2. Treatment with TRAIL induced caspase-8 translocation into the DR5-Cbl-b/c-Cbl-TRAF2 complex to interact with TRAF2, which then mediated the K48-linked polyubiquitination of caspase-8. The proteasome inhibitor bortezomib markedly enriched the p43/41 products of caspase-8 activated by TRAIL, indicating proteasomal degradation of caspase-8. Moreover, TRAF2 knockdown prevented the polyubiquitination of caspase-8 and thus increased TRAIL sensitivity. In addition, the inhibition of Cbl-b or c-Cbl expression and overexpression of miR-141 targeting Cbl-b and c-Cbl partially reversed TRAIL resistance by inhibiting the interaction between TRAF2 and caspase-8 and the subsequent polyubiquitination of caspase-8. These results indicate that the DR5-Cbl-b/c-Cbl-TRAF2 complex inhibited TRAIL-induced apoptosis by promoting TRAF2-mediated polyubiquitination of caspase-8 in gastric cancer cells.

Formation of the IGF1R/CAV1/SRC tri-complex antagonizes TRAIL-induced apoptosis in gastric cancer cells.

Lipid rafts provide a biological platform for apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We previously reported that insulin-like growth factor 1 receptor (IGF1R) translocation into lipid rafts helped to explain TRAIL resistance. However, it was not clear whether TRAIL resistance was caused by the interaction of IGF1R with caveolin-1 (CAV1) and the non-receptor tyrosine kinase SRC in lipid rafts of gastric cancer cells. Here, we observed high IGF1R expression in TRAIL-resistant gastric cancer cells, and showed that IGF1R combined with both CAV1 and SRC in a native complex. TRAIL was shown to promote the formation of the IGF1R/CAV1/SRC tri-complex and the activation of these three molecules. Knockdown of IGF1R or CAV1 or inhibition of SRC activity reduced the formation of this tri-complex and enhanced TRAIL-induced apoptosis. Furthermore, the overexpression of microRNA-194 reversed TRAIL resistance by reducing IGF1R expression. In summary, TRAIL increased formation of the IGF1R/CAV1/SRC tri-complex and the activation of downstream survival pathways, leading to TRAIL resistance in gastric cancer cells.

E3 Ubiquitin Ligase Cbl-b Prevents Tumor Metastasis by Maintaining the Epithelial Phenotype in Multiple Drug-Resistant Gastric and Breast Cancer Cells.

Multiple drug resistance (MDR) and metastasis are two major factors that contribute to the failure of cancer treatment. However, the relationship between MDR and metastasis has not been characterized. Additionally, the role of the E3 ubiquitin ligase Cbl-b in metastasis of MDR gastric and breast cancer is not well known. In the present study, we found that MDR gastric and breast cancer cells possess a typical mesenchymal phenotype and enhanced cell migration capacity. Additionally, Cbl-b is poorly expressed in MDR gastric and breast cancer cells. In MDR gastric adenocarcinoma tissues, gastric cancer patients with low Cbl-b expression were more likely to have tumor invasion (P=.016) and lymph node metastasis (P=.007). Moreover, overexpression of Cbl-b reduced cell migration in MDR cell cultures both in vitro and in vivo. Cbl-b overexpression also prevented EMT by inducing ubiquitination and degradation of EGFR, leading to inhibition of the EGFR-ERK/Akt-miR-200c-ZEB1 axis. However, further overexpression of EGFR on a background of Cbl-b overexpression restored both the mesenchymal phenotype and cell migration capacity of MDR gastric and breast cancer cells. These results suggest that Cbl-b is an important factor for maintenance of the epithelial phenotype and inhibition of cell migration in MDR gastric and breast cancer cells.