Progression Of Human Gastric Cancer Research Articles

Reduced Levels of miR–28 and miR–200a Act as Predictor Biomarkers of Aggressive Clinicopathological Characteristics in Gastric Cancer Patients

Background: MicroRNAs (miRNAs) play critical roles in different pathological processes including cancer development and progression. To find novel molecular diagnostic and prognostic markers and promising therapeutic tools for gastric cancer (GC), we aimed to investigate the relationship of the expression levels of miR–28–5p or miR–200a–3p with the clinicopathological criteria and to explore their impacts on the progression of human GC. Materials and Methods: Quantitative RT–PCR was performed to analyze miR–28 and miR–200a expression in 60 GC and 60 non–GC tissue samples. Result: Our results revealed that the expressions of miR–200a and miR–28 were significantly downregulated in GC in comparison with non–GC tissues. Tumors with low miR–28 expression had larger tumor size, more advanced histological grade, and a higher incidence of lymph node and distal metastasis than the tumors with high miR–28 expressions. Furthermore, receiver operating characteristic (ROC) analyses demonstrate that the expression of miR–28 is a predictive biomarker allows predicting the histological grade, tumor size, and occurrence of nodal and distal metastases. We also found a significant inverse association between miR–200a expression and the rate of lymph node metastasis (p = 0.010, r = –0.334). Conclusion: Our findings suggest that the miR–28 and miR–200a have tumor–suppressor functions and may be considered as potential biomarkers for gastric cancer diagnosis and prognosis.[GMJ.2019;8:e1329]

The POU2F1/miR-4490/USP22 Axis Regulates Cell Proliferation and Metastasis in Gastric Cancer

Background: Gastric cancer (GC) remains the fourth most common cancer and the miRNAs can function as tumor suppressors or oncogenes.The biological role of miR-4490 has not yet been reported in the context of cancer. Methods: To explore the function of miR-4490, we performed colony formation assays, EdU incorporation assays, qRT-PCR, Western blotting, In situ hybridization (ISH), immunohistochemistry (IHC), flow-cytometry assays, ChIP and dual-luciferase reporter assays. The growth, migration, and invasive capacity of GC cells were evaluated. Findings: microRNA-4490 (miR-4490) was significantly downregulated in GC tumor samples and cell lines compared with that in normal controls and that its expression level was negatively correlated with the aggressiveness of GC. Ectopic miR-4490 expression not only reduced cell-cycle transition and proliferation but also significantly inhibited GC cell migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro. Mechanistically, we confirmed that miR-4490 directly targeted USP22, which mediates the inhibition of proliferation and EMT-induced metastasis in vitro and in vivo. Moreover, we determined through luciferase and ChIP assays that the transcription factor POU2F1 directly bound to potential POU2F1 binding sites in the miR-4490 promoters and modulated their transcription. Spearman's correlation analysis showed a positive correlation between USP22 and POU2F1 and negative correlations between miR-4490 and USP22 as well as between miR-4490 and POU2F1 expression in GC tissues. Interpretation: Our findings suggest that POU2F1/miR-4490/USP22 axis plays an important role in the development and progression of human GC. Funding: National Natural Science Funds of China (Nos.81672875 and 81772964). Declaration of Interest: The authors declare that they have no competing interests. Ethical Approval: This study was reviewed and approved by the Medical Ethics Committee of Nanfang Hosital (NFEC-2017-062), Southern Medical University, Guangzhou, China. All animal studies were approved by the Institutional Animal Care and Use Committee of Committee of Nanfang Hosital.

Deregulation of CSMD1 targeted by microRNA-10b drives gastric cancer progression through the NF-κB pathway.

Aim: This study aimed to investigate the oncogenic activity of microRNA-10b by targeting CUB and sushi multiple domains protein 1 (CSMD1) in human gastric cancer (GC) and the underlying mechanisms.Methods: The expression of CSMD1 in human GC tissues was evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR), immunoblotting, and immunohistochemical analysis. The expressive abundance of microRNA-10b was detected by stem-loop RT-PCR. Molecular and cellular techniques, including lentiviral vector-mediated knockdown or overexpression, were used to elucidate the effect of microRNA-10b on the expression of CSMD1.Results: CSMD1 was targeted and downregulated by microRNA-10b in human GC tissues and cells, and the down-regulated expression of CSMD1 contributed to poor survival. The knockdown of microRNA-10b expression inhibited cell proliferation in GC cells in vitro and tumor growth in vivo. The inhibition of microRNA-10b expression repressed invasion and migration of HGC27 cells and retarded GC cells metastasis to the liver in Balb/c nude mice. The up-regulated expression of microRNA-10b promoted the proliferation and metastasis of MKN74 cell in vitro. Intratumoral injection of microRNA-10b mimic also promoted the growth and metastasis of tumor xenografts in Balb/c nude mice. Mechanistically, microRNA-10b promoted the invasion and metastasis of human GC cells through inhibiting the expression of CSMD1, leading to the activation of the nuclear factor-κB (NF-κB) pathway that links inflammation to carcinogenesis, subsequently resulting in the upregulation of c-Myc, cyclin D1 (CCND1), and epithelial-mesenchymal transition (EMT) markers.Conclusions: The findings established that microRNA-10b is an oncomiR that drives metastasis. Moreover, a set of critical tumor suppressor mechanisms was defined that microRNA-10b overcame to drive human GC progression.

MiR-5590-3p inhibited tumor growth in gastric cancer by targeting DDX5/AKT/m-TOR pathway

Recent evidence suggests that microRNAs play important roles in the negative post-transcriptional regulators with altered expression levels found in gastric cancer (GC). Therefore, we employed explore the anti-cancer miRNA and the potential mechanisms by which miRNAs modulate GC progression. We have predicted GC miRNA expression data sets in TargetScan. miR-5590-3p is higher in adjacent nonmalignant tissue than in cancer tissue in 42 pairs of GC tissues. Functional assays, CCK-8 and colony formation assay, were used to determine the Anti-cancer role of miR-5590-3p in human GC progression. In addition, Ago2-based RIP and dual-luciferase reporter assay were conducted to study the miR-5590-3p as a direct target of DDX5. Next, Xenograft nude mouse models were used to determine the role of miR-5590-3p in GC tumorigenicity in vivo. Upregulation of miR-5590-3p suppressed GC cell proliferation, whereas downregulation of miR-5590-3p promoted GC proliferation in vitro. Furthermore, we identified DDX5 as a direct target of miR-5590-3p, and that the biological function of miR-5590-3p during GC progression in vitro and in vivo is through the DDX5/AKT/m-TOR pathway and downstream cyclinD1 and CDK2 expression. Finally, we confirmed the effect of miR-5590-3p directly targeting DDX5 on the development of gastric cancer through salvage experiments in vivo and in vitro.

TIPE2 inhibits GC via regulation of cell proliferation, apoptosis and inflammation.

Gastric cancer (GC), a type of gastric mucosal epithelium disease caused by common malignant tumors, has become a major threat to human health and survival. Tumor necrosis factor-α-induced protein-8 like-2 (TIPE2) is a negative immune regulatory factor that is selectively expressed in immune organs, immune cells and various epithelial cells and serves an important role in the maintenance of human physiological immune homeostasis. In our preliminary study, we found that the expression of TIPE2 was downregulated or absent in GC tissues compared with normal gastric mucosa tissues, indicating that TIPE2 may play a significant role in the development of GC. To clarify the role of TIPE2 in the progression of human GC and to elucidate the underlying mechanism, the association between TIPE2 and phosphatidylinositol 3-kinase (PI3K)/AKT, the cell cycle, the caspase-related apoptosis pathway and the NF-κB signaling pathway were investigated through western blot and flow cytometric analysis. It was determined that TIPE2 inhibited GC cell proliferation mainly by reducing the expression of phosphorylated AKT and ERK, which caused subsequent inhibition of the PI3K-AKT and Ras-Raf-MEK-ERK1/2 signaling pathways. Additionally, we investigated the relationship between TIPE2 and GC and discovered that TIPE2 inhibited tumor progression via growth, apoptosis and inflammatory pathways. The results of the present study provided a theoretical basis for the development and application of TIPE2 as an antitumor agent.

Aldolase A as a prognostic factor and mediator of progression via inducing epithelial-mesenchymal transition in gastric cancer.

Glycolysis is regarded as the hallmark of cancer development and progression, which involves a multistep enzymatic reaction. This study aimed to explore the clinicopathological significance and potential role of glycolytic enzyme aldolase A (ALDOA) in the carcinogenesis and progression of gastric cancer (GC). ALDOA was screened from three paired liver metastasis tissues and primary GC tissues and further explored with clinical samples and in vitro studies. The ALDOA protein level significantly correlated with a larger tumor diameter (P = .004), advanced T stage (P < .001), N stage (P < .001) and lymphovascular invasion (P = .001). Moreover, the expression of ALDOA was an independent prognostic factor for the 5‐year overall survival and disease‐free survival of patients with GC in both univariate and multivariate survival analyses (P < .05). Silencing the expression of ALDOA in GC cell lines significantly impaired cell growth, proliferation and invasion ability (P < .05). Knockdown of the expression of ALDOA reversed the epithelial–mesenchymal transition process. Mechanically, ALDOA could affect the hypoxia‐inducible factor (HIF)‐1α activity as demonstrated by the HIF‐1α response element–luciferase activity in GC cells. Collectively, this study revealed that ALDOA was a potential biomarker of GC prognosis and was important in the carcinogenesis and progression of human GC.

Inhibition of the miR-192/215\u2013Rab11-FIP2 axis suppresses human gastric cancer progression

Less than a century ago, gastric cancer (GC) was the most common cancer throughout the world. Despite advances in surgical, chemotherapeutic, and radiotherapeutic treatment, GC remains the number 3 cancer killer worldwide. This fact highlights the need for better diagnostic biomarkers and more effective therapeutic targets. RAB11-FIP2, a member of the Rab11 family of interacting proteins, exhibits potential tumor suppressor function. However, involvement of RAB11-FIP2 in gastric carcinogenesis is yet to be elucidated. In this study, we demonstrated that RAB11-FIP2 was downregulated in GC tissues and constituted a target of the known onco-miRs, miR-192/215. We also showed that functionally, Rab11-FIP2 regulation by miR-192/215 is involved in GC-related biological activities. Finally, RAB11-FIP2 inhibition by miR-192/215 affected the establishment of cell polarity and tight junction formation in GC cells. In summary, this miR-192/215–Rab11-FIP2 axis appears to represent a new molecular mechanism underlying GC progression, while supplying a promising avenue of further research into diagnosis and therapy of GC.

The gastric mucosal protective effects of astragaloside IV in mnng-induced GPL rats

Gastric Cancer is one of the most common types of cancer. And the occurrence of gastric carcinoma is an evolutionary histopathological stage. As a result, further research of GPL, which is a borderline of gastric cancer, is indispensable for preventing the formation and development of gastric carcinoma. Several studies have demonstrated a correlation between the expression of autophagy, apoptosis and Gastric cancer (GC). However, the effects of autophagy and apoptosis on human gastric cancer progression, particularly on gastric precancerous lesions (GPL), have not totally been investigated. At present, Astragaloside IV(AS-IV) is a saponin purified from Astragalus membranaceous Bge, a traditional Chinese herb that has been widely used for more than 2000 y in the treatment of cancer, cardiovascular and immune disorders. This study was designed to investigate the mechanism of AS-IV protecting gastric mucosa in N-methyl-N’-nitro-N-nitrosoguanidine (MNNG)-induced GPL rats. The lesions of GIM and GED were significantly ameliorated compared with the model rats, especially crowded tubular glandular and back-to-back tubular structure, which were the dangerous borderline between GPL and GC. Western Blot analysis showed that the ratio of Bcl-2/Bax and the protein expression of Bcl-XL, p53, Beclin1, p62, ATG5 and ATG12 were decreased and the level of Caspase3 was increased in the group of AS-IV compared with the model group; RT-PCR analysis showed that the gene expression Ambra1, Beclin1, ATG5, LC3 and p62 were decreased in the group of AS-IV compared with the model group. This research manifested that the occurrence of gastric cancer was preceded by a prolonged precancerous stage, which could be ameliorated by the AS-IV. Meanwhile, the mild and moderate stage of precancerous lesions is similar with gastric adenocarcinoma in critical biological processes, including inflammation, cell proliferation, differentiation. But this lesion is very different from cancer, because it does not appear obvious invasion and malignant lesions in this pathologic stag. Further, AS-IV could regulate p53 expression to activate the Ambra1/Beclin1 complex in GPL, and it will protect the gastric mucosal injury, prevent and cure gastric mucosal atrophy, intestinal metaplasia and atypical hyperplastic lesions. It provided a potential therapeutic strategy in reversing intestinal metaplasia and dysplasia of gastric precancerous lesions and protecting the gastric mucosa in GPL rats.

MiR-449c inhibits migration and invasion of gastric cancer cells by targeting PFKFB3.

microRNAs (miRNAs) are important regulators in the development and progression of human gastric cancer (GC). However, the expression and biological function of miR-449c in GC remains unknown. In the present study, miR-449c was demonstrated to be downregulated in GC tissues and cell lines compared with normal. Decreased miR-449c levels were associated with poor prognosis in GC patients. Overexpression of miR-449c inhibited migration and invasion in SGC-7901 cells, while inhibition of miR-449c enhanced migration and invasion in MGC-803 cells. Furthermore, 6-phosphofructo-2-kinase (PFKFB3) was identified to be a downstream target of miR-449c in GC cells. miR-449c directly regulated the expression of PFKFB3 in GC cells. Overexpression of PFKFB3 abrogated the inhibitory effect of miR-449c on the migration and invasion of GC cells. In conclusion, the present study suggests that miR-449c may be a novel biomarker and potential therapeutic target in GC.

Cancer as a tissue: The significance of cancer-stromal interactions in the development, morphogenesis and progression of human upper digestive tract cancer.

We review the significance of cancer-stromal interactions (CSIs) in the development, morphogenesis and progression of human gastric and esophageal cancer based on the data obtained from co-culture experiments. Orthotopic fibroblasts in the gastric cancer stroma not only promoted their growth by cancer cells but were also responsible for the mobility, morphogenesis and epithelial-to-mesenchymal transition (EMT) of the cancer cells through CSI. Bone marrow-derived mesenchymal stem cells could be part of the origin of cancer-associated fibroblasts (CAFs) of the gastric cancer providing an advantageous microenvironment for the restoration of cancer stem cells with the induction of the EMT. Tumor-associated macrophages (TAMs) may differentiate from bone marrow-derived monocytes/macrophages within the tumor microenvironment of esophageal cancer and participate in the growth and the progression of esophageal squamous cell carcinomas (ESCCs). Macrophages infiltrated into the intraepithelial neoplastic lesions of the esophagus may function as a biological promoter by promoting the growth and motility of squamous epithelia. Tumor cells build up "cancer as a tissue" by taking advantage of the existing network of growth factors, cytokines and chemokines through the interactions of TAMs, CAFs and cancer cells themselves.

The Effect of Placenta Growth Factor Knockdown on hsa-miR-22-3p, hsa-let-7b-3p, hsa-miR-451b, and hsa-mir-4290 Expressions in MKN-45- derived Gastric Cancer Stem-like Cells

Background: Placental growth factor is involved in human gastric cancer initiation and progression through stimulating the proliferation, angiogenesis, invasion and metastasis of cancerous cells. Previous studies indicate that the expression profiles of hsa-miR-22-3p, hsa-let-7b-3p, hsa-miR-451b, and hsa-mir-4290 change in MKN-45- derived gastric cancer stem-like cells. Therefore, this study aims to investigate the effect of PlGF knockdown on hsa-miR-22-3p, hsa-let-7b-3p, hsa-miR-451b, and hsa-mir-4290 expressions in MKN-45-derived gastric cancer stem-like cells.Methods: We used a non-adhesive culture system to derive the cancer stem-like cells from MKN-45 cells. PlGF gene silencing was performed by PlGF-specific siRNA. The transcript of PlGF and miRNAs were measured by real-time RT-PCR. We conducted bioinformatics analyses with the online software programs TargetScan, miRanda, miRWalk, PicTar, and the Database for Annotation, Visualization, and Integrated Discovery tools to predict miRNAs’ targets and their signaling pathways.Results: hsa-let-7b-3p had a 2.28-fold up-regulation, whereas we observed downregulation of hsa-mir-451b (25%), hsa-mir-4290 (34%), and hsa-mir-22-3p (9%). Bioinformatics analysis results indicated that the miRNA target genes TGF-β, MAPK, and Wnt, and hedgehog signaling pathways contributed to cancer initiation and progression by influencing different cellular behaviors.Conclusion: We suggest that PlGF signaling may influence miRNA expression profiles in MKN-45-derived cancer stem-like cells, which can influence the expressions of different genes and signaling pathways. However, more empirical studies should determine the exact effect of PlGF knockdown on the expression of miRNA targets in cancer stem-like cells to locate their actual gene targets.

GSE1 predicts poor survival outcome in gastric cancer patients by SLC7A5 enhancement of tumor growth and metastasis

Gastric cancer remains a malignancy with poor survival outcome. We herein report that GSE1, a proline-rich protein, possesses a role in the progression of human gastric cancer. The expression of GSE1 was observed to be much higher in human gastric cancer tissues compared with normal gastric tissues, and GSE1 expression correlated positively with lymph node metastasis, histological grade, depth of invasion, and clinical stage in gastric cancer patients. Moreover, GSE1 expression was also associated with decreased post-operative relapse-free survival and overall survival in the cohort. The forced expression of GSE1 in gastric cancer cell lines resulted in increased cell proliferation, increased colony formation, enhanced cell migration, and invasion. Furthermore, forced expression of GSE1 also increased tumor size and enhanced lung metastasis in xenograft models. The depletion of endogenous GSE1 with shRNAs decreased the oncogenicity and invasiveness of gastric cancer cells both in vitro and in vivo In addition, GSE1 was determined to be a direct target of miR-200b and miR-200c. Furthermore, GSE1 positively regulated the downstream gene SLC7A5 (also known as LAT-1), which was scanned and verified from mRNA sequencing. GSE1 therefore possesses an oncogenic role in human gastric cancer, and targeted therapeutic approaches to inhibit GSE1 function in gastric cancer warrant further consideration.

Apigetrin inhibits gastric cancer progression through inducing apoptosis and regulating ROS-modulated STAT3/JAK2 pathway

Apigetrin (APG), as a flavonoid, has many cellular bioactivities, including regulation of oxidative stress, and induction of apoptosis. However, the means by which APG suppresses human gastric cancer are still little to be understood. In the present study, the anti-cancer effects of APG on human gastric cancer cells were investigated. The results indicated that APG could suppress the proliferation and induce apoptosis in gastric cancer cells. Its role in apoptosis induction was through reducing Bcl-2, and enhancing Bax, Caspase-9/-3 and poly ADP-ribose polymerase (PARP) cleavage. In addition, APG incubation resulted in the generation of intracellular reactive oxygen species (ROS) in cells. Meanwhile, APG suppressed constitutive and interleukin-6 (IL-6)-stimulated signal transducer and activator of transcription 3 (STAT3), Janus kinase 2 gene (JAK2) and Src activation. However, ROS scavenger, N-acety-l-cysteine (NAC), diminished apoptosis induced by APG. And APG-triggered de-phosphorylation of STAT3/JAK2 was rescued by NAC pre-treatment. In vivo, APG administration significantly inhibited the gastric cancer cell xenograft tumorigenesis through inducing apoptosis and inhibiting STAT3/JAK2 pathways. Taken together, the findings above illustrated that APG might be used as a promising candidate against human gastric cancer progression.

Silencing of ENO1 by shRNA Inhibits the Proliferation of Gastric Cancer Cells

α-Enolase is a significant subunit of enolase and acts as a glycolytic enzyme responsible for catalyzing the conversion of 2-phosphoglycerate to phosphoenolpyruvate in the anaerobic glycolysis pathway. The research about their role is known little in tumor invasion and metastasis. This research analyzed the effect of α-enolase in proliferation and progression of human gastric cancer. The constructed PLKO.1-ENO1 shRNA vector was transfected into 293 T cells and used to infect gastric cancer cells, MKN45, by using lentivirus method. Negative controls were generated by infection with viruses containing empty vector PLKO.1-scramble-shRNA by the same protocol and using wild-type MKN45 cells as blank control. The silencing effect was confirmed by reverse transcription polymerase chain reaction and Western blotting at messenger RNA and protein levels, respectively. Cell proliferation and chemosensitivity were tested by methyl-thiazolyl-tetrazolium assay. Cell apoptosis was tested by flow cytometry. The cell line α-enolase short hairpin RNA stabling silence α-enolase was successfully constructed. In the α-enolase short hairpin RNA cell lines, messenger RNA and protein expression of α-enolase were significantly lower than those in negative control and blank control groups. The proliferation and clone formation ability were significantly inhibited, cell apoptosis was increased significantly, and the inhibition rate of chemotherapy drugs was increased (P < .05). Our data provide strong evidence that α-enolase short hairpin RNA interference vector can effectively suppress the proliferation and increase chemosensitivity of MKN45 cells, which may provide a novel gene therapy for gastric cancer.

TIMMDC1 Knockdown Inhibits Growth and Metastasis of Gastric Cancer Cells through Metabolic Inhibition and AKT/GSK3β/β-Catenin Signaling Pathway.

TIMMDC1 (C3orf1), a predicted 4-pass membrane protein, which locates in the mitochondrial inner membrane, has been demonstrated to have association with multiple member of mitochondrial complex I assembly factors and core mitochondrial complex I subunits. The expression level of TIMMDC1 in highly-metastatic tumor cells is higher than that in lowly- metastatic tumor cells. However, the role of TIMMDC1 in human gastric cancer progression is unclear. In this study, human gastric cancer cells SGC-7901 and BGC-823 cells were used, and TIMMDC1 was knockdown with small interfering RNA. The data showed that TIMMDC1 knockdown caused inhibitory effects on the cell proliferation in vitro and tumor progression in vivo. Knockdown of TIMMDC1 significantly and exclusively reduced the activity of mitochondrial complex I but not complex II~ IV, and caused an obvious inhibition in mitochondrial respiration and ATP-linked oxygen consumption. Besides, the glycolysis pathway was also attenuated by TIMMDC1 knockdown, and the ATP content in the group of shTIMMDC1 cells was significantly lower than that in the shCont cells. The expression levels of phosphoylated AKT(Ser473) and GSK-3β (Ser9), as well as the downstream protein β-catenin and c-Myc were also markedly reduced in the group of shTIMMDC1 cells. Taken together, these findings suggest that TIMMDC1 may play an important role in human gastric cancer development, and its underlying mechanism is not only associated with mitochondrial complex I inhibition and reduced mitochondrial respiration, but is also associated with reduced glycolysis activity and the AKT/GSK3β/β-catenin signaling pathways.

KLK6 Promotes Growth, Migration, and Invasion of Gastric Cancer Cells.

PurposeKallikrein (KLK) proteases are hormone-like signaling molecules with critical functions in different cancers. This study investigated the expression of KLK6 in gastric cancer and its potential role in the growth, migration, and invasion of gastric cancer cells.Materials and MethodsIn this study, we compared protein levels of KLK6, vascular endothelial growth factor (VEGF), and matrix metallopeptidase (MMP) 9 in normal gastric epithelial and gastric cancer cell lines by western blot. Fluorescence-activated cell sorting was employed to sort 2 clones of SGC-7901 cells with distinct KLK6 expression, namely, KLK6-high (KLK6high) and KLK6-low (KLK6low), which were then expanded. Lastly, immunohistochemical analysis was performed to investigate KLK6 expression in gastric cancer patients.ResultsThe expression levels of KLK6, VEGF, and MMP 9, were significantly higher in the gastric cancer cell lines SGC-7901, BGC-823, MKN-28, and MGC-803 than in the normal gastric epithelial cell line GES-1. Compared to KLK6low cells, KLK6high cells showed enhanced viability, colony-forming ability, migration, and invasion potential in vitro. Importantly, immunohistochemical analysis of a human gastric cancer tissue cohort revealed that the staining for KLK6, VEGF, and MMP9 was markedly stronger in the cancerous tissues than in the adjacent normal tissues. KLK6 expression also correlated with that of VEGF and MMP9 expression, as well as several key clinicopathological parameters.ConclusionsTogether, these results suggest an important role for KLK6 in human gastric cancer progression.

FGFR2 Promotes Gastric Cancer Progression by Inhibiting the Expression of Thrombospondin4 via PI3K-Akt-Mtor Pathway

Background/Aims: Fibroblast growth factor receptor 2 (FGFR2) has attracted considerable interest as a therapeutic target in gastric cancer (GC). There is growing evidence to suggest that the bioavailability of the potent pro-tumor function of FGFR2 is associated with thrombospondins (TSPs). As a follow-on from our previous study, here we evaluated the potential clinical significance and mechanism of the relationship between FGFR2 and TSP4 in GC. Methods: Expression levels of FGFR2 and TSP4 were detected by immunohistochemistry in GC tissue microarray slides. SGC7901 and MKN28 cell lines were used to confirm the relationship between FGFR2 and TSP4. In vitro cell viability, colony formation, and invasion and migration assays were performed to evaluate the effect of FGFR2-TSP4 axis on tumor cell activities. The mechanism of TSP4 regulated by FGFG2 was explored via small molecular inhibitors in vitro and a xenograft model. Results: FGFR2 was shown to be markedly overexpressed in GC tissues and was correlated with a high risk of lymph node metastasis, late clinical stage, and poor prognosis. Low TSP4 expression was associated with shorter overall survival (OS) and advanced stage in GC patients. Interestingly, correlation analysis indicated that FGFR2 was negatively associated with TSP4. Indeed, in vitro and in vivo experiments suggested FGFR2 activation could downregulate TSP4 expression, which played an important role in the proliferation, invasion and migration of GC cells. We also found involvement of the PI3K-AKT-mTOR pathway in the FGFR2-TSP4 axis. Conclusion: The FGFR2 signal promotes human GC progression through the downregulation of TSP4 via PI3K-AKT-mTOR pathway. Our findings provide a foundation for further investigating promising therapeutic strategies for GC overexpressing FGFR2.

FAM83D, a microtubule-associated protein, promotes tumor growth and progression of human gastric cancer

FAM83D, a microtubule-associated protein (MAP), is overexpressed in diverse types of human cancer. The expression and critical role of FAM83D in human gastric cancer (GC), however, remains largely unknown. Here, we conducted molecular, cellular and clinical analyses to evaluate the functional link of FAM83D to GC. FAM83D expression was elevated in gastric tumors, and its expression strongly correlated with lymph node metastasis and TNM stage. In addition, over-expression of FAM83D in GC cell lines enhanced cell proliferation, cycle progression, migration, invasion, as well as tumor growth and metastatic dissemination in vivo. Furthermore, FAM83D exhibited a strong cell cycle correlated expression. The knockdown of FAM83D inhibited the regrowth of microtubules in GC cells. FAM83D was co-immunoprecipitated with HMMR, TPX2, and AURKA, a set of drivers of mitosis progression. Taken together, our results demonstrate FAM83D as an important player in the development of human gastric cancer, and as a potential therapeutic target for the treatment of cancer.

Abstract 1987: Inhibition of collagen receptor discoidin domain receptor-1 (DDR1) reduces gastric cancer cell motility and metastasis

Abstract Accumulating evidences suggest that a unique set of receptor tyrosine kinases, known as discoidin domain receptors (DDRs), play a role in cancer progression by interaction with their surrounding collagen matrix. Although abnormal expression of DDRs is reported in some human cancers, little is known about the expression and function of DDRs in gastric cancer progression. In this study, we investigated expression and the role of DDR1 in the tumor progression of human gastric cancer. The expression and distribution of DDR1 was analyzed by immunohistochemistry in 127 human gastric cancer cases, and the expression level of DDR1 in 7 human gastric cancer cell lines was analyzed by RT-PCR and western blotting. Proliferation, migration, invasion, and tube formation assays were conducted in DDR1 silenced gastric cancer cells. The effect of DDR1 on the tumor growth and metastasis were examined in orthotopically implanted nude mice model and a model of liver metastasis. DDR1 was expressed in human gastric cancer cell lines, and expression of DDR1 in human gastric tumor was associated with poor prognosis. Among 7 gastric cancer cell lines, MKN74 expressed DDR1 at highest level. DDR1-silenced MKN74 cells showed unaltered proliferation activity. In contrast, migration, invasion, and tube formation were significantly reduced. When examined in an orthotopic nude mouse model, DDR1-silenced implanted tumor significantly decreased angiogenesis and lymphangiogensesis, thereby leading to reduction of lymph node metastasis and liver metastasis. We showed that treatment of DDR1 inhibitor also inhibited lymph node metastasis in an orthotopic nude mouse model These results suggest that DDR1 is involved in GC tumor progression and metastasis. DDR1 could be not only an independent prognostic classifier, but also a promising therapeutic target in patients with GC. Citation Format: Ryo Yuge, Yasuhiko Kitadai, Hidehiko Takigawa, Shinji Tanaka, Kazuaki Chayama, Wataru Yasui. Inhibition of collagen receptor discoidin domain receptor-1 (DDR1) reduces gastric cancer cell motility and metastasis [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 1987. doi:10.1158/1538-7445.AM2017-1987

The long noncoding RNA, TINCR, functions as a competing endogenous RNA to regulate PDK1 expression by sponging miR-375 in gastric cancer.

BackgroundAccumulating evidence indicates that the long noncoding RNA, TINCR, plays a critical role in cancer progression and metastasis. However, the overall biological role and mechanisms of TINCR that were involved in human gastric cancer (GC) progression remain largely unknown.MethodsTINCR expression was measured in 56 paired tumor and adjacent nontumor tissue samples by real-time polymerase chain reaction (PCR). Insights of the mechanism of competitive endogenous RNAs (ceRNAs) were gained from bioinformatic analysis, luciferase assays. The effects of TINCR and miR-375 on GC cell apoptosis and proliferation were studied by RNA interference approaches in vitro and in vivo. The correlation of TINCR and PDK1 was identified by real-time PCR and Western blot analysis.ResultsOur results showed that miR-375 level decreased and TINCR level increased in tumor tissues. In addition, TINCR was a target of miR-375 and inhibited its expression in GC cells. Furthermore, the low expression of TINCR increased cell apoptosis and inhibited the proliferation of GC cells, while the downregulation of miR-375 reversed the function. In particular, TINCR could negatively regulate the miR-375 expression and increased the PDK1 expression in GC cells. Finally, tumor growth suppression was retarded with miR-375 downregulated in TINCR knockdown of GC cell xenografts.ConclusionThe long noncoding RNA TINCR functions as a competing endogenous RNA to regulate PDK1 expression by sponging miR-375 in GC. The ceRNA regulatory network of TINCR/miR-375/PDK1 allows us to better understand the pathogenesis of GC and facilitate the development of long noncoding RNA (lncRNA)-directed diagnostics in GC.