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Gastric cancer is one of the most common malignancies worldwide and the third leading cause of cancer-related death. In the present study, we investigated the potential activity of OSI-027, a potent and selective mammalian target of rapamycin complex 1/2 (mTOR1/2) dual inhibitor, alone or in combination with oxaliplatin against gastric cancer cells in vitro. Cell counting kit-8 assays and EdU staining were performed to examine the proliferation of cancer cells. Cell cycle and apoptosis were detected by flow cytometry. Western blot was used to detect the elements of the mTOR pathway and P-gp in gastric cancer cell lines. OSI-027 inhibited the proliferation of MKN-45 and AGS cells by arresting the cell cycle in the G0/G1 phase. At the molecular level, OSI-027 simultaneously blocked mTORC1 and mTORC2 activation, and resulted in the downregulation of phosphor-Akt, phpspho-p70S6k, phosphor-4EBP1, cyclin D1, and cyclin-dependent kinase4 (CDK4). Additionally, OSI-027 also downregulated P-gp, which enhanced oxaliplatin-induced apoptosis and suppressed multidrug resistance. Moreover, OSI-027 exhibited synergistic cytotoxic effects with oxaliplatin in vitro, while a P-gp siRNA knockdown significantly inhibited the synergistic effect. In summary, our results suggest that dual mTORC1/mTORC2 inhibitors (e.g., OSI-027) should be further investigated as a potentially valuable treatment for gastric cancer.

Anoikis is a type of programmed cell death induced by loss of anchorage to the extracellular matrix (ECM). Anoikis resistance (AR) is crucial for the survival of metastatic cancer cells in blood, lymphatic circulation and distant organs. Compared to ordinary cancer cells, anoikis resistant cancer cells undergo various cellular and molecular alterations, probably characterizing the cells with unique features not limited to anoikis resistance. However, the molecular mechanisms connecting anoikis resistance to other metastatic properties are still poorly understood. Here, the biological interaction between anoikis resistance and angiogenesis as well as their involvement into peritoneal metastasis of gastric cancer (GC) were investigated in vitro and in vivo. The prognostic value of key components involved in this interaction was evaluated in the GC cohort. Compared to ordinary GC cells, GCAR cells exhibited stronger metastatic and pro-angiogenic traits corresponding to elevated PDGFB secretion. Mechanistically, transcription factor C/EBPβ facilitated PDGFB transcription by directly binding to and interacting with PDGFB promoter elements, subsequently increasing PDGFB secretion. Secreted PDGFB promoted the survival of detached GC cells through a C/EBPβ-dependent self-feedback loop. Moreover, secreted PDGFB promoted angiogenesis in metastases via activation of the MAPK/ERK signaling pathway in vascular endothelial cells. Both C/EBPβ activation level and PDGFB expression were significantly elevated in GC and correlated with metastatic progression and poor prognosis of patients with GC. Overall, interaction between GCAR cells and vascular endothelial cells promotes angiogenesis and peritoneal metastasis of GC based on C/EBPβ-mediated PDGFB autocrine and paracrine signaling. C/EBPβ-PDGFB-PDGFRβ-MAPK axis promises to be potential prognostic biomarkers and therapeutic targets for peritoneal metastasis of GC.

Background In recent years, the application of functional genetic immuno-oncology screens has showcased the striking ability to identify potential regulators engaged in tumor-immune interactions. Although these screens have yielded substantial data, few studies have attempted to systematically aggregate and analyze them. Methods In this study, a comprehensive data collection of tumor immunity-associated functional screens was performed. Large-scale genomic data sets were exploited to conduct integrative analyses. Results We identified 105 regulator genes that could mediate resistance or sensitivity to immune cell-induced tumor elimination. Further analysis identified MON2 as a novel immune-oncology target with considerable therapeutic potential. In addition, based on the 105 genes, a signature named CTIS (CRISPR screening-based tumor-intrinsic immune score) for predicting response to immune checkpoint blockade (ICB) and several immunomodulatory agents with the potential to augment the efficacy of ICB were also determined. Conclusion Overall, our findings provide insights into immune oncology and open up novel opportunities for improving the efficacy of current immunotherapy agents.

The accumulation of adenosine in the tumor microenvironment is associated with tumor progression in many cancers. However, whether adenosine is involved in gastric cancer (GC) metastasis and progression, and the underlying molecular mechanism, is largely unclear. In this study, we find that GC tissues and cell lines had higher A2aR levels than nontumor gastric tissues and cell lines. A2aR expression correlated positively with TNMstage, and associated with poor outcomes. Adenosine enhanced the expression of the stemness and epithelial–mesenchymal transition-associated genes by binding to A2aR. A2aR expression on GC cells promoted metastasis in vivo. The PI3K-AKT-mTOR signaling pathway was involved in adenosine-stimulated GC cell migration and invasion. Our results indicate that adenosine promotes GC cell invasion and metastasis by interacting with A2aR to enhance PI3K–AKT–mTOR pathway signaling.

Anoikis is a type of programmed cell death induced by loss of anchorage to the extracellular matrix (ECM). Anoikis resistance (AR) is crucial for the survival of metastatic cancer cells in blood, lymphatic circulation and distant organs. Compared to ordinary cancer cells, anoikis resistant cancer cells undergo various cellular and molecular alterations, probably characterizing the cells with unique features not limited to anoikis resistance. However, the molecular mechanisms connecting anoikis resistance to other metastatic properties are still poorly understood. Here, the biological interaction between anoikis resistance and angiogenesis as well as their involvement into peritoneal metastasis of gastric cancer (GC) were investigated in vitro and in vivo. The prognostic value of key components involved in this interaction was evaluated in the GC cohort. Compared to ordinary GC cells, GC

G protein coupled estrogen receptor (GPER1) is a membrane estrogen receptor, belonging to the seven-transmembrane G protein-coupled receptors family, and has important biological functions in cancer. However, the functional role of GPER1 in gastric cancer (GC) remain incompletely understood. In the present study, we employed gene set enrichment analysis and discovered that GPER1 expression was concomitant with EMT process and was positively correlated with activation of the PI3K/AKT pathway in GC. Knockdown of GPER1 with siRNA suppressed the proliferation, migration, and invasion of AGS and MGC-803 GC cells. Knockdown of GPER1 also downregulated the mesenchymal markers N-cadherin and vimentin, upregulated E-cadherin, an epithelial marker, and suppressed expression of the Snail, Slug and Twist1 transcription factors, indicating that knockdown of GPER1 inhibited EMT. Moreover, 740Y-P, a PI3K activator, reversed the effects of GPER1 knockdown on EMT processes. Overexpression of GPER1 with plasmid can further prove these findings. In summary, these data demonstrate that GPER1 inhibition suppresses the proliferation, migration, and invasion of gastric cancer cells by inhibiting PI3K/AKT-mediated EMT. Our study elucidated the function of GPER1 in gastric cancer, and we identified PI3K/AKT-mediated EMT as a novel mechanism by which GPER1 contributes to proliferation, migration, and invasion of gastric cancer. These data suggest that combining inhibition of GPER1 and PI3K may be a potential therapeutic approach to inhibit gastric cancer metastasis.

// Xing Kang 1, * , Minhuan Li 2, * , Hao Zhu 3, * , Xiaofeng Lu 1 , Ji Miao 1 , Shangce Du 1 , Xuefeng Xia 1 and Wenxian Guan 1 1 Department of General Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, Jiangsu Province, China 2 Department of Laboratory Medicine, Sir Run Run Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu Province, China 3 Department of Gastroenterology, The Afflicted Drum Tower Hospital, Nanjing University Medical School, Nanjing 210008, Jiangsu Province, China * These authors have contributed equally to this work Correspondence to: Xuefeng Xia, email: 18114483312@sina.cn Wenxian Guan, email: 15850502391@163.com Keywords: chemoresistance, doxorubicin, DUSP4, epithelial-mesenchymal transition, gastric cancer Received: August 08, 2017 Accepted: September 03, 2017 Published: October 04, 2017 ABSTRACT 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.

BACKGROUND The purpose of this study was to evaluate the correlation between serum albumin level change (ΔALB) and post-operative complications in patients with normal preoperative serum albumin after gastrectomy of gastric cancer. METHODS A total of 193 patients undergoing curative (R0) gastrectomy from September 2015 to May 2017 were enrolled in this study. The risk factors for predicting post-operative complications were identified by univariate and multivariate analysis. The cut-off value and diagnostic accuracy of ΔALB were measured by receiver operating characteristic curves. ΔALB was defined as: (albumin level before surgery - albumin on post-operative day (POD) 1)/albumin level before surgery × 100%. RESULTS A total of 60 patients (31.0%) had post-operative complications. Our results showed that the cut-off value of ΔALB was 19.0%. Using a cut-off value of 19.0%, multivariate analysis identified that ΔALB was able to predict post-operative complications as an independent factor (odds ratio 13.98, 95% confidence interval 6.048-32.32, P

NADPH oxidase 4 (NOX4) is one of the main sources of reactive oxygen species, and plays a crucial role in the occurrence and development of tumors. However, there is currently little evidence demonstrating that NOX4 expression is associated with gastric cancer. To establish whether NOX4 plays a role in gastric cancer progression and prognosis, we performed immunohistochemistry on gastric cancer tissues and paired adjacent normal tissues from 90 gastric cancer patients to detect and compare NOX4 expression. Next, we analyzed the association between NOX4 expression and clinicopathological characteristics. Survival analysis was performed to explore the association between NOX4 expression and the prognosis of gastric cancer patients. Furtherly, we investigated the effect of NOX4-knockdown using siRNA on gastric cancer progression in vitro and in vivo. Our results revealed that NOX4 expression in gastric cancer tissues is higher than in paired adjacent normal tissues (P = 0.0009). NOX4 expression is significantly correlated with tumor size (P = 0.0321), lymphatic metastasis (P = 0.0125) and vascular invasion (P = 0.0017) and a poor prognosis (P = 0.0000) in gastric cancer patients. NOX4 depletion could significantly inhibit the invasion, proliferation, EMT and MMP7 expression of gastric cancer cells and suppress the progression of gastric cancer in vivo. In conclusion, NOX4 is related to gastric cancer development and predicts a poor prognosis. NOX4 may play an essential role in the progression of gastric cancer, and is a promising target for the prevention and treatment of gastric cancer.

Background. Adenosine, derived from the degradation of ATP via ectonucleotidases CD39 and CD73, is a critical immunosuppressive metabolite in the hypoxic microenvironment of tumor tissue. Adenosine signaling via A2aR can inhibit the antitumor immune response of CD8+T cells. CD39 and CD73 high-expressing Tregs play a critical role in tumor immune evasion of gastric cancer (GC). The present study investigated the underlying mechanism by which Tregs suppress antitumor immune responses in GC.Materials and Methods. Fifty-two GC samples were collected, and the frequency of FoxP3+Tregs and CD8+T cells and density ratios of A2aR+/CD8+T cells, CD39+/FoxP3+Tregs, and CD73+/FoxP3+Tregs in GC were assessed with multiplex immunofluorescence. The expression of FoxP3 and A2aR in GC tissues was also detected by the immunoblotting assay. We next investigated the relationship between density of FoxP3+Tregs, ratio of A2aR+/CD8+T cells, and clinicopathological parameters. At the same time, Tregs and CD8+T cells were isolated from peripheral blood of five GC patients, and the antagonists of CD39 and CD73 were used to assess the ability of Tregs to decompose ATP into adenosine. In addition, we cocultured CD8+T cells and Tregs with antagonists of A2aR and A2bR in order to examine the alterations in immune function of CD8+T cells.Results. The density of both FoxP3+Tregs and A2aR+/CD8+T cells was higher in GC tissue compared to peritumoral normal tissue and significantly correlated with the TNM stage, lymph node metastasis, and distant metastasis of GC. The process of Treg hydrolysis of ATP into adenosine was blocked by the antagonists of CD39 and CD73. In addition, Tregs could induce apoptosis and inhibit proliferation of CD8+T cells, while this effect could be obviously reduced by applying the antagonist of A2aR or A2aR+A2bR. Moreover, IFN-γ, TNF-α, and perforin generated by CD8+T cells could also be inhibited through the adenosine A2aR pathway.Conclusions. The FoxP3+Tregs and A2aR+/CD8+T cells were excessively infiltrated in GC tissue. Tregs from GC can decompose ATP to adenosine and in turn induce apoptosis and inhibit the proliferation of CD8+T cells through the A2aR pathway, further leading to immune escape of GC.

Anoikis is a type of programmed cell death induced by detachment from the extracellular matrix. In cancer cells, anoikis resistance is essential for cancer cell survival in blood circulation and distant metastasis. However, the mechanisms behind anoikis resistance of gastric cancer remain largely unknown. Herein, we demonstrate that NADPH oxidase 4 (NOX4) expression and reactive oxygen species (ROS) generation are upregulated in suspension gastric cell cultures compared with adherent cultures. Silencing of NOX4 decreases ROS generation and downregulates EGFR, sensitizing cells to anoikis. NOX4 overexpression upregulates ROS and EGFR levels and promotes anoikis resistance. NOX4 depletion inhibits gastric cancer survival in blood circulation and attenuates distant metastasis. NOX4 expression is correlated with EGFR expression in patients. In conclusion, induction of NOX4 expression by detachment promotes anoikis resistance of gastric cancer through ROS generation and downstream upregulation of EGFR, which is critical for the metastatic progression of gastric cancer.

The nuclear paraspeckle assembly transcript 1 (abbreviated as NEAT1), a nuclear sufficient long noncoding RNA (abbreviated as lncRNA), has aroused a rising concern in recent years. As uncovered by reports, the increase in NEAT1 is related to the deteriorated prognosis of lung cancer, breast cancer, hepatocellular cancer, and colorectal cancer (abbreviated as CRC). Thus far, the mechanism of NEAT1 has not been elucidated by the existing researches. The impact of knockdown of both NEAT1 and its predicted downstream miR‐193a‐3p in CRC cells was examined here to delve into their interactions and mechanisms. Additionally, the target of miR‐193a‐3p, Kirsten rat sarcoma viral oncogene homolog (abbreviated as KRAS), was also predicted by bioinformatics algorithms. Small interfering RNA and antisense oligonucleotides that inhibit NEAT1, as well as overexpression or knockdown of miR‐193a‐3p, were adequately drawn upon to confirm that NEAT1 serves as a miR‐193a‐3p sponge or competing endogenous RNA, to impact miR‐193a‐3p's further functions, including modulating KRAS proteins, both in vitro and in vivo. Generally, lncRNA NEAT1/hsa‐miR‐193a‐3p/KRAS axis was substantiated in CRC cells and could provide novel insight into both diagnostic and therapeutic advancement in CRC.

Background Postoperative complications following gastric cancer resection remain a clinical problem. Early detection of postoperative complications is needed before critical illness develops. The purpose of this study was to evaluate the prognostic value of C-reactive protein/albumin ratio in patients with gastric cancer. Methods A total of 322 patients undergoing curative (R0) gastrectomy between 2015 and 2017 were retrospectively analyzed. Univariate and multivariate analyses were performed to identify clinical factors predicting postoperative complications. The cutoff values and diagnostic accuracy of C-reactive protein/albumin ratio and C-reactive protein were determined by receiver-operating characteristic curves. Results Among all of the patients, 85 (26.4%) developed postoperative complications. The optimal cutoff of C-reactive protein/albumin ratio was set at 3.04 based on the ROC analysis. Multivariate analysis identified C-reactive protein/albumin ratio was an independent risk factors for complications after gastrectomy (OR 3.037; 95% CI 1.248–7.392; P = 0.014). Additionally, C-reactive protein/albumin ratio showed a higher diagnostic accuracy than C-reactive protein on postoperative day 3 (AUC: 0.685 vs 0.660; sensitivity: 0.624 vs 0.471; specificity: 0.722 vs 0.835). Conclusions Elevated C-reactive protein/albumin ratio was an independent predictor for postoperative complications following gastrectomy of gastric cancer, and the diagnostic accuracy was higher than C-reactive protein alone. Overall, postoperative C-reactive protein/albumin ratio may help to identify patients with high probability of postoperative complications.