Efficacy In Gastric Cancer Research Articles

Translational research on gastric cancer: Ruijin experience

Translational medicine refers to translating basic research achievements into the clinical application for diagnosis and treatment. There are still many issues of gastric cancer to be solved in clinical diagnosis and treatment. We need to focus on clinical questions, by means of basic research and multidisciplinary intersection approach, to further improve the overall efficacy of gastric cancer. Based on Ruijin Hospital's translational research experiences, in this paper, the authors describe the future direction in the field of translational research, such as the etiology and pathogenesis of gastric cancer, tumor markers for early diagnosis, prediction of recurrence and metastasis, classification criteria, evaluation of chemotherapy, tumor heterogeneity, targeted therapy, immunotherapy and research platform establishment. In addition, here we share our perspective of the research on serum biomarkers, specific antibodies and improvement of drug delivery for gastric cancer.

Can PD-L1 expression evaluated by biopsy sample accurately reflect its expression in the whole tumour in gastric cancer?

Programmed death ligand 1 (PD-L1) expression as a predictive biomarker for programmed cell death 1 (PD-1) inhibitor efficacy in gastric cancer (GC) remains controversial. We hypothesised that the conflicting results may be due to the inaccurate assessment of PD-L1 expression using biopsy samples. A total of 191 patients with GC who received radical resection were enrolled. PD-L1 expressions in biopsy and paired resected samples by immunohistochemistry staining were compared according to the number of biopsies. The numbers of PD-L1-positive patients determined by biopsy and resected samples were 89 (46.6%) and 135 (70.1%), respectively. The accordance rate was 64.4% (κ = 0.31). Single biopsy showed a lower accordance rate compared with multiple biopsies. Our study revealed that single biopsy cannot fully reflect PD-L1 expression in the whole tumour in GC. Multiple biopsies are recommended for accurate diagnosis of PD-L1 expression in GC.

Abstract 3981: Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer

Abstract Objectives: Peritoneal metastasis (PM) frequently occurs in patients with gastric cancer and has poor prognosis even with systemic chemotherapy. Intraperitoneal chemotherapy (IPC) using paclitaxel (PTX) combined with systemic chemotherapy has demonstrated a remarkable clinical efficacy for gastric cancer with PM. However, there is no reliable biomarker to reflect the response of peritoneal lesions as well as to predict the outcome of the patients receiving IPC. Although peritoneal fluids are considered to contain many factors derived from disseminated tumor cells in peritoneal cavity, little information is available so far. In this study, we examined exosomal miRNA profiles derived from peritoneal fluids in patients with gastric cancer and explored possible biomarkers useful for IPC of the patients with PM. Methods: Peritoneal fluids were collected from 2 groups; with or without PM. Peritoneal fluids were obtained either laparoscopically, during open surgery or from subcutaneous infusion port connected to an intraperitoneal catheter. Exosomal fractions were isolated using ultracentrifuge method (150,000 xg, 70 min, 4°C) and the presence of exosome was confirmed with nanotracking analysis. Total RNA including small RNA was extracted from exosomal fractions and expression analyses of miRNAs were performed using RT-PCR. Results: At first, we comprehensively analyzed the expression of miRNAs between 11 samples with PM and 14 samples without PM and identified 11 miRNAs which showed particularly different expression pattern between the 2 groups. Among them, 4 miRNAs (miR-21-5p,miR-223-3p, miR-342-3p and miR-92a-3p) were selected and further analysed using 51 samples derived from the peritoneal fluids of gastric cancer. Expression of these 4 miRNAs were significantly up-regulated in samples with PM which was consistent with formeranalysis. Moreover, expression of miR-21-5p was significantly upregulated in in samples fromT4 tumor (invaded serosa or adjacent structure) as compared with those from T1 to T3 tumor. Conclusion: We identified several dysregulated exsosomal miRNAs derived from peritoneal fluids of the patients with PM from gastric cancer, which were supposed to reflect the tumor burden on peritoneum. Exosomal miRNA profiles might be useful biomarkers to determine the presence of PM as well as the response to IPC. Citation Format: Hideyuki Ohzawa, Akira Saito, Yuko Kumagai, Hironori Yamaguchi, Yoshinori Hosoya, Naohiro Sata, Joji Kitayama. Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3981.

Endoscopic Evaluation of Neoadjuvant Chemotherapeutic Efficacy in Gastric Cancer before Gastrectomy Might be as Useful as Histological Assessment after Gastrectomy

Background: Neoadjuvant chemotherapy for advanced gastric cancer is expected to improve prognoses. However, as there is no method to evaluate neoadjuvant chemotherapeutic efficacy before gastrectomy, some patients at high risk for a poor prognosis undergo gastrectomy. The aim of the present study was to investigate whether endoscopy could be useful for assessing the efficacy of neoadjuvant chemotherapy. Methods: In this retrospective study, we analyzed the data of 41 patients who received neoadjuvant chemotherapy followed by gastrectomy at our institution to investigate whether responsiveness to neoadjuvant chemotherapy, as assessed with endoscopy, can serve as a surrogate marker for histological grades 1b or higher in the Japanese Classification of Gastric Carcinoma (JCGC) scheme. Results: There were 32 (78.0%) responders and 9 (22.0%) nonresponders to neoadjuvant chemotherapy, as observed in endoscopic evaluations. Among the endoscopic responders, 24 (75.0%) had cancer of histological grade 1b or higher, and 15 (46.9%) had cancer of grade 2 or higher. Among the endoscopic nonresponders, 1 (11.1%) patient had histological grade 1b cancer. Compared with endoscopic nonresponders, endoscopic responders were more likely to show a histological response (chi-square test: p = 0.0005 for JCGC grade 1b or higher; p = 0.0099 for JCGC grade 2 or higher). Conclusions: Most endoscopic responders showed JCGC histological responses. Evaluation of neoadjuvant chemotherapeutic efficacy by endoscopy in gastric cancer may be useful before gastrectomy. As this was a retrospective study, further investigations are required. The protocol was approved by the ethics review committee at Osaka Medical College (No. 2422) and was registered in the University Hospital Medical Information Network Clinical Trial Registry (UMIN000033088).

Evaluation of cisplatin-hydrogel for improving localized antitumor efficacy in gastric cancer

Gastric cancer, one of the most common disease, has become a major public health problem worldwide. Cisplatin (DDP) has been a widely used drug for the treatment of cancer, also usually applied in gastric cancer in clinic. However, the side effects including toxicity and drug-resistance restricted the usage of DDP in clinic, so we prepared a DDP-complexed hydrogel (DDP-Gel) and investigated its efficacy in gastric cancer. For in vivo studies, MKN45-Luc cells were injected into BLAB/C node mice subcutaneously to establish gastric cancer with orthotopically grown tumors. Mice bearing tumors were treated with normal saline, DDP and DDP-Gel. Body weight and survival condition were observed and recorded. The treatment efficacy in vivo was detected by luciferase imaging and histological evaluation was performed by H&E staining of different organs. Additionally, normal ICR mice were treated with different doses of DDP/DDP-Gel to calculate their LD50 in vivo. The results showed that DDP-Gel prolonged survival time and ameliorated body weight changes of mice bearing tumors. DDP-Gel exhibited higher efficacy to inhibit tumor growth and metastasis, compared to DDP. Besides, LD50 of DDP-Gel was 166.0 mg/kg, 13.2 folds higher than DDP. As a conclusion, DDP-Gel showed a more effective and safer function than DDP in gastric cancer, which indicating that DDP-Gel might be a novel strategy for gastric cancer therapy.

Predicting the Efficacy of 5-Fluorouracil-Based Adjuvant Chemotherapy in Gastric Cancer by Microsatellite Instability: A Meta-Analysis.

Microsatellite instability (MSI) implies the deletion of mismatch repair genes caused by DNA methylation or gene mutation. MSI is a good predictor for efficacy of 5-fluorouracil (FU)-based chemotherapy in the treatment of colorectal cancer. Some gastric cancer studies have reported that MSI has no apparent impact on prognosis after patients receive 5-FU-based adjuvant chemotherapy. However, other studies suggest that high-frequency MSI (MSI-H) status reduced survival in patients receiving 5-FU-based adjuvant chemotherapy. Thus, the correlation between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer remains controversial. We performed a PubMed, Embase, and Cochrane search to retrieve studies that explore the correlation between MSI status and 5-FU-based adjuvant chemotherapy efficacy in gastric cancer. After extracting 65 potentially eligible studies, four were ultimately included in this meta-analysis using Stata software (ver. 12.0). For each study, we estimated the hazard ratio (HR) value for overall survival (OS), and HR was extracted per the survival curve in the studies. Heterogeneity was estimated using the random-effects model. Overall, 1174 patients after operation were included: 84 patients were classed as MSI-H and 1090 as microsatellite stable (MSS)/low-frequency MSI (MSI-L). For the four studies, the overall estimate of HR for OS between MSI-H and MSS/MSI-L groups was 1.90 (95% confidence interval: 0.91-3.93; p = 0.08). We found no correlation to exist between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer. Although MSI can effectively predict efficacy of 5-FU-based chemotherapy in patients with colorectal cancer, the correlation between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer remains controversial. This meta-analysis suggests that MSI status is unrelated to efficacy of 5-FU-based adjuvant chemotherapy in gastric cancer, and more prospective clinical studies are needed to further investigate predictive value of MSI status in patients with gastric cancer who, after operation, receive 5-FU-based adjuvant chemotherapy.

Stimulation of natural killer cells with rhCD137 ligand enhances tumor-targeting antibody efficacy in gastric cancer.

Although many anticancer agents for gastric cancer have been developed, the prognosis for many patients remains poor. Recently, costimulatory immune molecules that reactivate antitumor immune responses by utilizing the host immune system have attracted attention as new therapeutic strategies. CD137 is a costimulatory molecule that reportedly potentiates the antitumor activity of tumor-targeting monoclonal antibodies (mAbs) by enhancing antibody-dependent cellular cytotoxicity. However, it remains unclear whether CD137 stimulates tumor-regulatory activity in gastric cancer. In this study, we investigated the antitumor effects of CD137 stimulation on gastric cancer cells administered tumor-targeting mAbs. Our results showed that human natural killer (NK) cells were activated by expressing CD137 after encountering trastuzumab-coated gastric cancer cells, and that stimulation of activated NK cells in the presence of trastuzumab and recombinant human CD137 ligand (rhCD137L) enhanced cytotoxicity and release of cytokines (IFN-γ, TNF, granzyme A, or granzyme B) as compared with activated NK cells with trastuzumab alone (p < 0.05). By combination treatment with rhCD137L, similar effects were obtained regarding cancer cell cytotoxicity in the presence of cetuximab (p < 0.01). Moreover, we revealed that CD137 expression was dependent upon the affinity between the Fc portion of the antibodies and FcγRIIIa of NK cells based on results indicating that human IgG1 and IgG3 subclasses enhanced CD137 expression (p < 0.001). These results confirmed that FcγRIIIA polymorphisms (158 V/V) enhanced CD137 expression to a greater degree than 158 F polymorphisms (p = 0.014). Our results suggested that CD137 stimulation could promote the effects of tumor-targeting mAbs in gastric cancer, and that further investigation of antibody binding affinity and in vivo activities might improve therapeutic strategies related to the treatment of gastric cancer patients.

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.

Dual silencing of EGFR and HER2 enhances the sensitivity of gastric cancer cells to gefitinib.

Gefitinib exhibits very limited efficacy in gastric cancer (GC). Indeed, the limited clinical results obtained with gefitinib alone justify investigation of additional therapeutic strategies. Here, we demonstrate the importance of EGFR and HER2 in GC malignancy using RNA interference (RNAi). Additionally, we explored the ability of RNAi targeting EGFR and HER2 to enhance the sensitivity of GC cells to gefitinib. Specific small interfering RNAs (siRNAs) significantly inhibited mRNA and protein expression of target genes. EGFR-specific siRNA, EGFR/HER2 siRNAs, and gefitinib inhibited growth and induced apoptosis in GC cell lines in a dose-dependent manner. In contrast, resistance to HER2-siRNA-induced growth inhibition and apoptosis was linked to compensatory activation of EGFR. Moreover, gefitinib dramatically reduced p-EGFR and p-HER2 levels in the cell lines tested, and sensitivity to gefitinib was enhanced through dual silencing of EGFR and HER2 via suppression of AKT and ERK activation. These findings are in agreement with the profound inhibitory effect of gefitinib on activation of both EGFR and HER2. Overall, EGFR/HER2 knockdown by siRNAs further decreased the growth of GC cells treated with gefitinib alone, confirming that single-agent drug targeting does not achieve a maximal biological effect. The combination of gefitinib with EGFR/HER2 siRNAs should be further investigated as a new strategy for the treatment of GC and other EGFR/HER2-dependent cancers.

Blockade of CCR5-mediated myeloid derived suppressor cell accumulation enhances anti-PD1 efficacy in gastric cancer

Purpose: Myeloid derived suppressor cells (MDSC) play an important role in tumor immune evasion and its level significantly increased in patients with gastric cancer. Studies confirmed the associations between MDSC and various cytokines in the peripheral blood. However, little is known about the mechanism drawing MDSC into tumor parenchyma. This study was to analyze the correlation between MDSC subsets and CCR5 level in gastric cancer.Materials and methods: G-MDSC and M-MDSC from the peripheral blood and tumor parenchyma were analyzed by flow cytometry. CCR5 ligand CCL5 was detected by ELISA. CCR5 was detected by real-time PCR, western blot and flow cytometry. Furthermore, the therapeutic effects of CCR5 blockade was assessed by the tumor model.Results: CCR5 ligand, gene and protein expression of CCR5, and surface expression of CCR5 significantly increased in blood and tumor of tumor-bearing mice, suggesting MDSC may be attracted into the parenchyma by CCL5/CCR5. Anti-CCR5 treatment decreased G-MDSC and M-MDSC in the periphery and tumor. In addition, combination treatment enhanced CD4+ and CD8+ T cell infiltration and decreased the tumor burden of tumor-bearing mice.Conclusions: This study elucidated a possible association between MDSC subsets and CCR5, in addition to provide a new potential target to enhance the efficacy of immunotherapy in patients with gastric cancer.

Abstract A042: Genomic predictors of chemotherapy efficacy in gastric cancer in the GC0301/TOP002 phase III trial

Abstract Recent gastric cancer (GC) clinical trials have aimed to establish the efficacy of combination therapy over monotherapy; however, a role for genomic biomarkers in these trials has remained largely unexplored. Here, using the NanoString expression platform, we analyzed 105 gastric tumors from a randomized phase III Japanese clinical trial (GC0301/TOP002) testing efficacy of irinotecan plus S-1 over S-1 chemotherapy. We found that previously established proliferative subtype signatures were associated with older patients (&amp;gt;65 years) and liver metastasis, while mesenchymal subtype signatures were associated with younger patients (≤65 years) and peritoneal metastasis. Genes associated with the tumor microenvironment (CD14, DPYD), oncogenic signaling (Wnt5A, PTRF), and chemokines (CCL5, CXCL12, CCL19) were significantly associated with patient age, Lauren’s histologic classification, tumor status, measurable lesions, and metastasis. We identified Wnt5A downregulation as a candidate predictor of improved progression-free survival (PFS) (&amp;gt;8 weeks) in fluorouracil (S-1) monotherapy-treated patients, but not in irinotecan plus S-1 (IRI-S) combined treatment. Although not achieving statistical significance, we observed a trend for mesenchymal subtype showing a treatment interaction with IRI-S for efficacy. These findings highlight promising genomic markers that could be useful predictors of chemotherapy efficacy for better prognosis and survival outcome in gastric cancer. Citation Format: Kakoli Das, Masataka Taguri, Akira Tsuburaya, Patrick Tan. Genomic predictors of chemotherapy efficacy in gastric cancer in the GC0301/TOP002 phase III trial [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A042.

MiR-542-3p Appended Sorafenib/All-trans Retinoic Acid (ATRA)-Loaded Lipid Nanoparticles to Enhance the Anticancer Efficacy in Gastric Cancers.

In this study, miR-542-3p appended SRF/ATRA-loaded solid lipid nanoparticle was successfully prepared and demonstrated for its therapeutic efficacy against gastric cancers. The particles were nanosized and typically spherical in shape. In vitro release study showed that release of ATRA was significantly slower compared to that of SRF from the NPs. MTT assay showed that miR-542-3p have a strong inhibitory effect on the proliferation of MGC-803 cancer cells in a typical dose dependent manner. Nanocarrier encapsulation of SRF+ATRA induced a significantly higher cytotoxic effect compared to either individual drug or cocktail combinations indicating that the cellular uptake of different formulations was rate limiting factor in the therapeutic efficacy. Importantly, miR-542-3p-based miSRNP exhibited an extremely significant toxic effect compared to any other treated group. Importantly, miSRNP induced a significantly higher early (~55%) and late (~15%) apoptotic effect in gastric cancer cells. In vivo anticancer analysis results clearly suggest that nanoparticle encapsulation of combination of SRF and miRNA (with miRNA) will have greater antitumor efficacy in tumor mice. Overall, unique combination of miRNA coupled with SRF+ATRA in a lipid nanocarrier could be a promising therapeutic approach in gastric cancer treatment.

DUSP4 promotes doxorubicin resistance in gastric cancer through epithelial-mesenchymal transition.

Chemoresistance limits treatment efficacy in gastric cancer and doxorubicin resistance is common in gastric cancer cells. Dual specificity phosphatase 4 (DUSP4) has been associated with tumor progression. This study aimed to investigate the mechanism of DUSP4 regulating doxorubicin resistance in gastric cancer cells. Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2′-deoxyuridine (EdU) incorporation assay were used to measure cell viability and proliferation in gastric cancer cells treated with doxorubicin. The expression of DUSP4, E-cadherin and Vimentin protein was detected by Western blotting. Overexpression of DUSP4 was more resistant to doxorubicin in gastric cancer cells. Knockdown of DUSP4 increased the sensitivity of gastric cancer cells to doxorubicin. Moreover, up-regulation of DUSP4 promoted the Epithelial-Mesenchymal Transition (EMT) in gastric cancer cells, but blocking the EMT using a Twist siRNA increased the sensitivity of gastric cancer cells to doxorubicin and confirmed the EMT was involved in DUSP4-mediated doxorubicin resistance. These findings demonstrated that DUSP4 could enhance doxorubicin resistance by promoting EMT in gastric cancer cells.

Abstract 139: M2698, a novel dual inhibitor of p70S6K and Akt: preclinical efficacy in gastric cancer

Abstract M2698 is a selective, ATP-competitive dual inhibitor of p70S6K and Akt1/3 that is being evaluated in a phase I clinical trial in cancer patients. The dual nature of M2698 may result in improved clinical efficacy by blocking the increased AKT activity in a compensatory feedback loop induced by PI3K/AKT/mTOR (PAM) pathway inhibition. In previous preclinical studies, M2698 was shown to have potent anti-proliferative activity in vitro, and inhibit tumor growth in some xenograft models in vivo. The current study examined the effects of M2698 on cell proliferation in a panel of 13 gastric cancer cell lines, as gastric cancers often harbor mutations in PAM pathway genes that deregulate this signalling pathway. Cells were treated with M2698 at a range of concentrations and proliferation was evaluated at least twice using the WST-8 cell proliferation assay kit (Dojindo Molecular Technologies, Inc. Japan). Two cell lines, HGC-27 and IM95m, were particularly sensitive to M2698 (50% growth inhibition concentration [GI50] 84 and 160 nM, respectively). The GI50 values for all other cell lines were &amp;gt;10-fold higher. Although HGC-27 and IM95m each carry a PIK3CA hotspot point mutation, the presence of an activating PI3K pathway mutation was not the sole determinant of sensitivity, as a third PIK3CA mutant cell line, MKN1, was far less sensitive to M2698 (GI50 9.0 uM). Western blot analysis of pharmacodynamic biomarkers showed that M2698 (1 uM) blocked the PAM pathway in both sensitive and resistant cell lines, inhibiting phospho[p]-S6 and p-PRAS40, despite increased p-Akt. Some biomarkers from the PAM pathway and other signaling pathways appeared to be associated with sensitivity to M2698, but these candidate biomarkers need to be validated in a larger panel of cell lines. Treatment of HGC-27-tumor-bearing mice with M2698 (10, 20, 30 mg/kg/day) for 14 days resulted in significant tumor growth inhibition (80.2-98.6%) at Day 29 compared to treatment with vehicle (p&amp;lt;0.01). In conclusion, we have shown that gastric cancer cell lines have a range of sensitivities to M2698 and the sensitivity cannot be explained solely by genetic mutations in the PAM pathway. M2698 provides potent PAM pathway inhibition in both sensitive and resistant gastric cancer cell lines by blocking both p70S6K and Akt. M2698 significantly inhibits tumor growth in the HGC-27 xenograft model in vivo. Citation Format: Shota Fukuoka, Takashi Kojima, Yoshikatsu Koga, Mayumi Yamauchi, Masahiro Yasunaga, Yasuhiro Matsumura, Toshihiko Doi, Takayuki Yoshino, Toshio Kuronita, Anderson Clark, Brian Elenbaas, Atsuhi Ohtsu. M2698, a novel dual inhibitor of p70S6K and Akt: preclinical efficacy in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 139. doi:10.1158/1538-7445.AM2017-139

Autocrine VEGF signaling promotes cell proliferation through a PLC-dependent pathway and modulates Apatinib treatment efficacy in gastric cancer

BackgroundTumor cells produce vascular endothelial growth factor (VEGF) which interact with the membrane or cytoplasmic VEGF receptors (VEGFRs) to promote cell growth in an angiogenesis-independent fashion. Apatinib, a highly selective VEGFR2 inhibitor, is the only effective drug for patients with terminal gastric cancer (GC) who have no other chemotherapeutic options. However, its treatment efficacy is still controversy and the mechanism behind remains undetermined. In this study, we aimed to investigate the role of autocrine VEGF signaling in the growth of gastric cancer cells and the efficacy of Apatinib treatment.MethodsThe expression of phosphor VEGFR2 in gastric cancer cell lines was determined by real-time PCR, immunofluorescence, and Western blot. The gastric cancer cells were administrated with or without recombination human VEGF (rhVEGF), VEGFR2 neutralizing antibody, U73122, SU1498, and Apatinib. The nude mice were used for xenograft tumor model.Resultswe found that autocrine VEGF induced high VEGFR2-expression, promoted phosphorylation of VEGFR2, and further enhanced internalization of pVEGFR2 in gastric cancer cells. The autocrine VEGF was self-sustained through increasing VEGF mRNA and protein expression. It exerted pro-proliferative effect through a PLC-ERK1/2 dependent pathway. Furthermore, we demonstrated that in VEGFR2 overexpressing gastric cancer cells, Apatinib inhibited cell proliferation in vitro and delayed xenograft tumor growth in vivo. However, these effects were not observed in VEGFR2 low expressing gastric cancer cells.ConclusionThese results suggested that autocrine VEGF signaling promotes gastric cancer cell proliferation and enhances Apatinib treatment outcome in VEGFR2 overexpression gastric cancer cells both in vitro and in vivo. This study would enable better stratification of gastric cancer patients for clinical treatment decision.

AT101 exerts a synergetic efficacy in gastric cancer patients with 5-FU based treatment through promoting apoptosis and autophagy.

Gastric cancer remains a disease with a high mortality rate despite of multiple therapeutic strategies. So far, it is very important to develop new treatment approaches to improve current therapeutic efficacy in gastric cancer. Apurinic/apyrimidinic endonuclease (APE1) involves in DNA base excision repair (BER) during DNA damage pathway. APE1 was found to be associated with poor overall survival with gastric cancer patients. In the in vitro experiment, we tested APE1 inhibitor-AT101 could potently inhibit gastric cancer cell growth and further induce cancer cell apoptosis and autophagy through p53-dependent pathway. Downregulation of APE1 by AT101 has ability to suppress gastric cancer cell migration and renewal through inhibition of CD133, Nanog and LC3expression. Based on findings that Her-2 positive expression cases has poor prognosis from our dataset and TCGA database, we investigated the role of AT101 in synergetic efficacy with 5-FU treatment in Her-2 overexpression gastric cancer in vivo, indicating that AT101 is able to enhance 5-FU in the shrinkage of xenograft mice tumor and induction of cell apoptosis. In summary, the data obtained from our study showed APE1 is guided as a potential therapeutic target for gastric cancer. AT101 could be regarded as a potent inhibitor to promote chemotherapeutic sensitivity in patients with gastric cancer.

Tu1312 Autocrine VEGF Signaling Promotes Cell Proliferation and Modulates Apatinib Efficacy in Gastric Cancer

Tu1312 Autocrine VEGF Signaling Promotes Cell Proliferation and Modulates Apatinib Efficacy in Gastric Cancer

Intravoxel incoherent motion diffusion-weighted imaging for monitoring chemotherapeutic efficacy in gastric cancer.

To assess intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for monitoring early efficacy of chemotherapy in a human gastric cancer mouse model. IVIM-DWI was performed with 12 b-values (0-800 s/mm(2)) in 25 human gastric cancer-bearing nude mice at baseline (day 0), and then they were randomly divided into control and 1-, 3-, 5- and 7-d treatment groups (n = 5 per group). The control group underwent longitudinal MRI scans at days 1, 3, 5 and 7, and the treatment groups underwent subsequent MRI scans after a specified 5-fluorouracil/calcium folinate treatment. Together with tumor volumes (TV), the apparent diffusion coefficient (ADC) and IVIM parameters [true water molecular diffusion coefficient (D), perfusion fraction (f) and pseudo-related diffusion coefficient (D(*))] were measured. The differences in those parameters from baseline to each measurement (ΔTV%, ΔADC%, ΔD%, Δf% and ΔD(*)%) were calculated. After image acquisition, tumor necrosis, microvessel density (MVD) and cellular apoptosis were evaluated by hematoxylin-eosin (HE), CD31 and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining respectively, to confirm the imaging findings. Mann-Whitney test and Spearman's correlation coefficient analysis were performed. The observed relative volume increase (ΔTV%) in the treatment group were significantly smaller than those in the control group at day 5 (ΔTVtreatment% = 19.63% ± 3.01% and ΔTVcontrol% = 83.60% ± 14.87%, P = 0.008) and day 7 (ΔTVtreatment% = 29.07% ± 10.01% and ΔTVcontrol% = 177.06% ± 63.00%, P = 0.008). The difference in ΔTV% between the treatment and the control groups was not significant at days 1 and 3 after a short duration of treatment. Increases in ADC in the treatment group (ΔADC%treatment, median, 30.10% ± 18.32%, 36.11% ± 21.82%, 45.22% ± 24.36%) were significantly higher compared with the control group (ΔADC%control, median, 4.98% ± 3.39%, 6.26% ± 3.08%, 9.24% ± 6.33%) at days 3, 5 and 7 (P = 0.008, P = 0.016, P = 0.008, respectively). Increases in D in the treatment group (ΔD%treatment, median 17.12% ± 8.20%, 24.16% ± 16.87%, 38.54% ± 19.36%) were higher than those in the control group (ΔD%control, median -0.13% ± 4.23%, 5.89% ± 4.56%, 5.54% ± 4.44%) at days 1, 3, and 5 (P = 0.032, P = 0.008, P = 0.016, respectively). Relative changes in f were significantly lower in the treatment group compared with the control group at days 1, 3, 5 and 7 follow-up (median, -34.13% ± 16.61% vs 1.68% ± 3.40%, P = 0.016; -50.64% ± 6.82% vs 3.01% ± 6.50%, P = 0.008; -49.93% ± 6.05% vs 0.97% ± 4.38%, P = 0.008, and -46.22% ± 7.75% vs 8.14% ± 6.75%, P = 0.008, respectively). D* in the treatment group decreased significantly compared to those in the control group at all time points (median, -32.10% ± 12.22% vs 1.85% ± 5.54%, P = 0.008; -44.14% ± 14.83% vs 2.29% ± 10.38%, P = 0.008; -59.06% ± 19.10% vs 3.86% ± 5.10%, P = 0.008 and -47.20% ± 20.48% vs 7.13% ± 9.88%, P = 0.016, respectively). Furthermore, histopathologic findings showed positive correlations with ADC and D and tumor necrosis (r s = 0.720, P < 0.001; r s = 0.522, P = 0.007, respectively). The cellular apoptosis of the tumor also showed positive correlations with ADC and D (r s = 0.626, P = 0.001; r s = 0.542, P = 0.005, respectively). Perfusion-related parameters (f and D(*)) were positively correlated to MVD (r s = 0.618, P = 0.001; r s = 0.538, P = 0.006, respectively), and negatively correlated to cellular apoptosis of the tumor (r s = -0.550, P = 0.004; r s = -0.692, P < 0.001, respectively). IVIM-DWI is potentially useful for predicting the early efficacy of chemotherapy in a human gastric cancer mouse model.

The novel vaccine contained full tumor antigen hopeful to solve the problems of antigen delivery and host immunity enhancement

Herein, we report for the first time of the novel vaccine cell composed with allogenic mature dendritic cells (DCs) and inactive gastric cancer (GC) cells prepared by PEG mediated fusion. Combined with effecter of cytokine induced killing cells (CIKs), the immunotherapeutic and prophylactic potential of the fused vaccine cells (VCs) were evaluated in tumor-bearing, post-surgery and tumor free mice models. The migration and homing process of near infrared region quantum dots (NIR-QDs) labeled VCs were investigated by real-time animal imaging system. Results showed that the VCs and VC+CIKs could trigger the tumor-specific CTLs against GC cell, target the tumor tissue initiatively and enhance the prophylactic effects, suppress the tumor growth remarkably in vivo . The potential mechanism is also investigated. In conclusion, the novel vaccine cells can be used for targeted imaging and enhanced immunotherapeutic efficacy of GC, and hopeful to solve the double problems of antigen delivery and host immunity enhancement at the same time.

Cytokeratin 18 for chemotherapy efficacy in gastric cancer

Cytokeratin 18 (CK18) is the major component of intermediate filaments in epithelial cells and released into the blood in either intact (M65) or caspase-cleaved forms (M30) during apoptotic and necrotic cell death. M30 and M65 are relatively described as novel sandwich ELISA assays that determine different circulating forms of the protein CK18 in either plasma or serum and are proposed to be surrogate endpoints of different forms of cell death. Serum M65 and M30 levels have shown to be elevated in patients with different types of carcinoma. The measurement of M30 or M65 values from epithelial-derived tumors could be a simple, noninvasive way to monitor or predict tumor progression and prognosis. Recently, predictive significance of the increase in the serum M30 and M65 values after chemotherapy in patients advanced nonsmall cell lung cancer (NSCLC) and gastric cancer have been evaluated. It shown that increased serum M65 levels, 48 hours after chemotherapy, could be predicted tumor response in advanced-gastric cancer patients. Although these assays may be useful for evaluating treatment effects and survival in patients with gastric cancer, their importance should be tested after multiple chemotherapy sessions in larger prospective studies with long follow-up time. In this review, prognostic and predictive significance of CK18 for advanced-gastric cancer are summarized in the light of recent advances.