Progression Of Gastric Carcinoma Research Articles

Inhibiting the role of Skp2 suppresses cell proliferation and tumorigenesis of human gastric cancer cells via the upregulation of p27kip1.

Gastric cancer is a malignant disease of the digestive system with high rates of incidence and mortality. S‑phase kinase‑associated protein 2 (Skp2) is a novel oncogene, which has been identified to be important in tumor progression and metastasis. In order to clarify the role of Skp2 in human gastric cancer, the present study detected the expression of Skp2 in human gastric cancer tissues, and investigated the molecular mechanism of Skp2 in the progression of gastric carcinoma. The results of the initial bioinformatics analysis showed that Skp2 was significantly upregulated in 31specimens of primary gastric cancer from a UK patient cohort, and in 10 gastric cancer lines of a side population, compared with normal gastric tissues (P<0.01). Specimens from 47patients with gastric cancer and 19 normal gastric tissue specimens were obtained and analyzed using western blot analysis. The positive rate of expression of Skp2 was 87.2%, indicating that the expression of Skp2 was observed in 41specimens of the detected gastric cancer samples, whereas the positive rate of the expression of Skp2 was 5.6% in the normal gastric samples (P<0.01). In the human gastric cancer cell lines, the defective regulation of Skp2 or presence of an Skp2 inhibitor inhibited the proliferation of BGC‑823 and MKN‑45 cells. In addition, the Skp2 inhibitor suppressed the proliferation of gastric cancer cells in a time‑ and dose‑dependent manner. Furthermore, transfection with Skp2 short hairpin (sh)RNA or treatment with SKPinhibitorC1 for 48 and 72h led to the accumulation of p27kip1 in Hela cells. Tumorigenicity experiments involving nude mice showed that interference of the expression of Skp2 inhibited the growth of the human gastric tumor cells in the nude mice, and the tumor weights and volumes in the Skp2 shRNA group were significantly lower, compared with those in the negative control shRNA group (P<0.01) and untreated group (P<0.01). Taken together, these data suggested that Skp2 acted as an oncogene in human gastric cancer, and that Skp2‑mediated p27kip1 degradation contributed to the progression of gastric cancer. Abrogating the effects of Skp2 may effectively inhibit the growth of gastric cancer cells, which may be useful as a novel target in the clinical treatment of gastric cancer.

Prognostic implications of phosphatidylinositol 3-kinase/AKT signaling pathway activation in gastric carcinomas.

IntroductionActivation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway plays a critical role in carcinogenesis and resistance to anticancer drugs. In this study, gastric carcinomas (GC) were investigated and statistical analyses were performed concerning the correlation between the clinicopathological features and activation of the PI3K/AKT pathway.Material and methodsImmunohistochemistry for p-AKT, p-mTOR and PTEN was performed in 239 GC and 200 non-neoplastic gastric tissues. The clinicopathological parameters were recorded from the medical charts. Statistical significance was defined by a p-value < 0.05.ResultsHigh p-AKT expression was observed in 10% of the normal gastric tissue and in 90% of GC, and it was significantly associated with tumor size (p < 0.001), T3/T4 tumors (p < 0.001), and presence of metastases (p = 0.02). Similarly, p-mTOR positivity was found in GC cells, but not in the normal gastric mucosa, and was correlated with perineural invasion (p = 0.02) and T3/T4 tumors (p = 0.03). On the other hand, PTEN expression was weak and focal in the tumor cells, while in the normal gastric tissue this staining was strong and diffuse. Importantly, the expression of p-mTOR and PTEN was associated with overall survival.ConclusionsThe results of the present study, characterized by the loss of PTEN expression and higher expression of p-AKT and p-mTOR in the majority of tumor cells, apparently are implicated in the carcinogenesis and progression of GC. The identification of p-mTOR and PTEN expression as prognostic factors corroborates the identification and use of potential target drugs that could be more efficient for the treatment of these patients.

Mo1343 Endoscopic Characteristics and Rapid Progression of Gastric Carcinoma After H. pylori Eradication

Mo1343 Endoscopic Characteristics and Rapid Progression of Gastric Carcinoma After H. pylori Eradication

O-GlcNAcylation is associated with the development and progression of gastric carcinoma

IntroductionO-GlcNAcylation occurs via an O-linked β-N-acetylglucosamine (O-GlcNAc) moiety linked to the side chain hydroxyl of a serine or threonine residue on nucleocytoplasmic proteins. This reaction, which is catalyzed by O-GlcNAc-transferase (OGT), is involved in a variety of human cancers; however, its clinical significance in gastric carcinomas (GC) has been poorly investigated in vivo. Materials and methodsImmunohistochemical staining for O-GlcNAcylation and OGT was performed in 64 primary GCs, 40 gastric adenomas and nonneoplastic tissues adjacent to GCs, including 31 tissues of intestinal metaplasia and 24 normal gastric tissues. Their expressions were also studied in 20 tissues of chronic gastritis according to Helicobacter pylori (H. pylori) infection. ResultsO-GlcNAcylation was expressed in the nucleus and both the nuclear rim and cytoplasm. OGT was strongly expressed in the nucleus and weakly expressed in the cytoplasm. O-GlcNAcylation expression levels were significantly correlated with those of OGT. Their expression levels were progressively increased during the carcinogenesis of GC. O-GlcNAcylation expression was higher in GC with intestinal type, higher pT stage and nodal metastasis, while OGT expression was higher in GC with nodal metastasis. Nuclear O-GlcNAcylation expression was more frequently observed in tumors including GC and adenoma than in nonneoplastic tissues including intestinal metaplasia and normal tissue. Nuclear O-GlcNAcylation expression in GC was closely associated with large size, moderate and poor differentiation, higher pT stage, nodal metastasis and higher clinical stage. In addition, the expression of O-GlcNAcylation and OGT was more elevated in H. pylori-infected chronic gastritis than in chronic gastritis without H. pylori infection. ConclusionsO-GlcNAcylation expression and its nuclear expression were associated with the carcinogenesis and progression of GC.

Epstein-Barr Virus-Associated Gastric Carcinoma and Specific Features of the Accompanying Immune Response.

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) is one of the four subtypes of gastric carcinoma (GC), as defined by the novel classification recently proposed by The Cancer Genome Atlas. EBVaGC has several clinicopathological features such as longer survival and higher frequency of lymphoepithelioma-like carcinoma (LELC) and carcinoma with Crohn's disease-like lymphoid reaction that distinguish it from EBV-negative GC. The intensity and pattern of host cellular immune response in GC have been found to significantly correlate with the prognosis of patients with GC, suggesting that immune reaction and tumor microenvironment have critical roles in the progression of GC, and in particular, EBVaGC. Here, we reviewed the cellular and molecular mechanisms underlying prominent immune reactions in patients with EBVaGC. In EBVaGC, deregulation of the expression of immune response-related genes promotes marked intra- or peritumoral immune cell infiltration. The expression of programmed death receptor-ligand 1 is known to be increased in EBVaGC, and therefore, it has been proposed as a favorable prognostic factor for patients with EBVaGC, albeit some data supporting this claim are controversial. Overall, the underlying mechanisms and clinical significance of the host cellular immune response in patients with EBVaGC have not been thoroughly elucidated. Therefore, further research is necessary to better understand the role of tumor microenvironment in EBVaGC.

MicroRNA-1225-5p inhibits proliferation and metastasis of gastric carcinoma through repressing insulin receptor substrate-1 and activation of β-catenin signaling.

Emerging evidence has linked aberrantly expressed microRNAs (miRNAs) with oncogenesis and malignant development in various human cancers. However, their specific roles and functions in gastric carcinoma (GC) remain largely undefined. In this study we identify and report a novel miRNA, miR-1225-5p, as tumor suppressor in GC development and progression. Microarray analysis revealed that there were fifty-six differentially expressed miRNAs (thirty-two upregulated and twenty-four downregulated) in GC tumor samples compared to their corresponding nontumorous tissues. Downregulation of miR-1225-5p was frequently detected in GC and strongly correlated with more aggressive phenotypes and poor prognosis. Functional assays demonstrated that ectopic overexpression of miR-1225-5p could inhibit cell proliferation, colony formation, migration and invasion in vitro, as well as suppress tumor growth and metastasis in nude mice. Further integrative and functional studies suggested insulin receptor substrate 1 (IRS1) as a downstream effector of miR-1225-5p which acted through β-catenin signaling pathway. These results demonstrate that miR-1225-5p serves to constrain GC growth and metastatic potential via inhibition of IRS1 and β-catenin signaling. Therefore, downregulation of miR-1225-5p is likely to be one of major molecular mechanisms accounting for the development and progression of GC.

The MSHA strain of Pseudomonas aeruginosa (PA-MSHA) inhibits gastric carcinoma progression by inducing M1 macrophage polarization.

Macrophages play crucial roles in promoting tumor development and progression. In the present study, we found that the mannose-sensitive hemagglutination pilus strain of Pseudomonas aeruginosa (PA-MSHA) was efficient in inducing M1 macrophage polarization. PA-MSHA treatment increases expression of M1-related cytokines and promotes activation of murine peritoneal macrophages (MPM). Interestingly, PA-MSHA inhibits cell proliferation and migration and induces the apoptosis of gastric carcinoma cells. These effects of PA-MSHA on M1 polarization were associated with activation of NF-κB expression. Thus, inducing polarization of M1 by PA-MSHA may be one potential strategy for inhibiting gastric carcinoma progression in mice.

Expression and clinical implication of S100A12 in gastric carcinoma.

S100 protein family has been implicated in multiple stages of tumorigenesis and progression in which S100A12 is one of the subtypes. However, the role of S100A12 in gastric carcinoma (GC) has not been elucidated yet. This study was aimed to investigate the expression of S100A12 in GC tissues and evaluate the clinical significance of S100A12 in GC patients. S100A12 protein was detected in 207 GC and 52 paired non-cancerous mucosal tissues by immunohistochemistry, while messenger RNA (mRNA) was investigated by Oncomine database analysis. Moreover, survival analysis was performed and the correlation between S100A12 and ubiquitin-specific protease 10 (USP10) and p53 was determined. As for tumor cells, the expression of S100A12 protein and mRNA in GC was proved to be lower than that in non-cancerous mucosa tissues (p < 0.05). Clinicopathological analysis showed that S100A12 protein was negatively associated with tumor size (p = 0.004), depth of invasion (p = 0.022), tumor node metastasis (TNM) stage (p = 0.018), Lauren classification (p < 0.000), and cell differentiation (p < 0.000). In contrast, a positive correlation was found between S100A12 and USP10 protein (p < 0.000). However, no relationship was detected between S100A12 and p53. Moreover, the survival analysis indicated that S100A12 protein was a favorable factor of prognosis of GC (p < 0.05). Although the expression of S100A12 in the stromal cells was detected higher than that in the tumor cells, no relationship between S100A12 protein in stromal cells and the clinicopathological features described above was found (p > 0.05). Our findings suggested that low expression of S100A12 might be served as a new marker in the tumorigenesis and progression of GC.

Upregulated expression of DIXDC1 in intestinal-type gastric carcinoma: co-localization with β-catenin and correlation with poor prognosis.

BackgroundDIXDC1 (Dishevelled-Axin domain containing 1) is a positive regulator of the Wnt pathway. In the field of cancer research, the role of DIXDC1 is unclear. Our previous in vitro study showed that DIXDC1 enhances β-catenin nuclear accumulation in gastric cancer cell lines. The aim of this study was to detect the expression of DIXDC1 in different histological subtypes of gastric carcinoma and to evaluate the correlation between the expression of DIXDC1 and β-catenin localization and clinicopathological parameters, including patients’ survival.MethodsImmunohistochemical staining was performed to characterize the expression of DIXDC1 and β-catenin in archived materials from 259 cases of gastric carcinoma. The χ2 test and the Fisher’s test were used to analyze correlations between DIXDC1 expression, β-catenin localization, and clinicopathological parameters. Univariate analyses were performed using the Kaplan–Meier method, and the survival difference between groups was assessed by the log-rank test. Multivariate analysis was performed using the Cox proportional hazards regression model.ResultsPositive DIXDC1 staining was detected in tumor cells in 123 of 259 (47.5 %) cases. DIXDC1 expression in gastric carcinoma was significantly correlated with the histological intestinal-type (P < 0.001), the depth of tumor invasion (P < 0.001) and the lymph node metastasis (P = 0.006). In the intestinal-type, DIXDC1 was correlated with the nuclear and cytoplasmic β-catenin expression (P = 0.002). Kaplan–Meier analysis indicated that patients with high DIXDC1 expression had poor disease-specific survival (P < 0.001), especially in the intestinal-type. Moreover, multivariate regression analysis showed that positive expression of DIXDC1 was an independent prognostic predictor of intestinal-type gastric carcinoma.ConclusionOur study indicated that DIXDC1 is a significant independent prognostic indicator in intestinal-type gastric carcinoma that plays an important role in carcinogenesis and progression of gastric carcinoma through the Wnt signaling pathway.

Expressional profiles of transcription factors in the progression of Helicobacter pylori-associated gastric carcinoma based on protein/DNA array analysis.

Transcription factors (TFs) are crucial modulators of gene expression during the development and progression of gastric carcinoma. Helicobacter pylori (H. pylori) is one of the most significant risk factors of gastric carcinoma, and it is widely known that chronic inflammation with H. pylori infection triggers gastric carcinogenesis through inflammation-carcinoma chain [gastric carcinogenesis stages: non-atrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia and gastric carcinoma (GC)], but its mechanism regarding changed TFs remains unknown. In this study, we investigated the expressional profiles of 345 transcription factors in gastric mucosa of healthy volunteers and patients at different gastric carcinogenesis stages using protein/DNA array-based approach. The data demonstrated the up-regulated TFs such as GATA-3, AP4, c-Myc and Pbx1 in the gastric mucosa of GC patients compared with the healthy volunteers, while other TFs, particularly CCAAT and CACC, showed the consistently decreasing trend along the gastric carcinogenesis. The increased expressions of AP4, Pbx1 and C/EBPα were further validated by quantitative real-time PCR and Western blot in various H. pylori-infected models such as clinical gastric tissues, gastric epithelial cell lines and Mongolian gerbils. This study provides insights into and potential laws for gene transcriptional regulation by identifying potential TFs targets against the development of H. pylori-associated gastric carcinoma.

The role of cullin proteins in gastric cancer

The cullin proteins are a family of scaffolding proteins that associate with RING proteins and ubiquitin E3 ligases and mediate substrate-receptor bindings. Thus, cullin proteins regulate the specificity of ubiquitin targeting in the regulation of proteins involved in various cellular processes, including proliferation, differentiation, and apoptosis. There are seven cullin proteins that have been identified in eukaryotes: CUL1, CUL2, CUL3, CUL4A, CUL4B, CUL5, and CUL7/p53-associated parkin-like cytoplasmic protein. All of these proteins contain a conserved cullin homology domain that binds to RING box proteins. Cullin-RING ubiquitin ligase complexes are activated upon post-translational modification by neural precursor cell-expressed, developmentally downregulated protein 8. The aberrant expression of several cullin proteins has been implicated in many cancers though the significance in gastric cancer has been less well investigated. This review provides the first systematic discussion of the associations between all members of the cullin protein family and gastric cancer. Functional and regulatory mechanisms of cullin proteins in gastric carcinoma progression are also summarized along with a discussion concerning future research areas. Accumulating evidence suggests a critical role of cullin proteins in tumorigenesis, and a better understanding of the function of these individual cullin proteins and their targets will help identify potential biomarkers and therapeutic targets.

The expression of Cx43, TGF&amp;beta;/smads signaling pathways and PCNA in the occurrence and development of gastric carcinoma and the relationship among them

Aims and Objectives: To detect the protein expression level of Cx43, smad4 and PCNA in normal and gastric carcinoma tissue by immuno-histochemistry, western blotting and RT-PCR method. We intend to reveal the relationship between their expression in occurrence and development. Simultaneously through analyzing experimental data we have obtained the correlation among them.Materials and Methods: Immuno-histochemistry and western blotting were adopted to detect the expression of Cx43, smad4 and PCNA protein in normal and carcinomatous gastric tissue, expression levels mRNA of Cx43, smad4 and PCNA were detected by RT-PCR in normal and carcinomatous gastric tissue. Experimental data were analyzed by combining clinical pathology data using statistical approach. Results: The expression levels of Cx43, and smad4 in carcinomatous gastric tissue were lower than they were in normal gastric tissue. The expression level of PCNA in carcinomatous gastric tissue was higher than that in normal gastric tissue. The expression levels of Cx43, Smad4 and PCNA in groups of age and gender is not significant. The expression of Cx43, Smad4 and PCNA in different clinicopathologic features of carcinomatous gastric tissue including degrees of pathological differentiation, lymph node metastasis condition, depth of tumor invasion and TNM stages is statistically significant. With the progression of gastric carcinoma, the expression levels of Cx43 and Smad4 were decreased, conversely PCNA showed a high expression level. Based on the analysis Cx43 negatively correlated with PCNA, Cx43 positively correlated with Smad4, Smad4 negatively correlated with PCNA.Conclusions: The protein and mRNA expressions of Cx43, smad4 and PCNA were significant differences between normal gastric tissue and gastric carcinoma, also were concerned with differentiation degree, lymph node metastasis, TNM stages and depth of invasion, while not significant with age and gender. This suggests that they may play an important role in occurrence and development of gastric carcinoma, but also may have some interaction. Asian Journal of Medical Sciences Vol.7(1) 2015 6-13

Abstract 5063: Lysyl oxidase-like 2 (LOXL2) from cancer-associated fibroblasts stimulates the progression of gastric carcinoma

Abstract Purpose: Lysyl oxidase families are involved in a variety of pathological processes, including cancer progression. Lysyl oxidase-like 2 (LOXL2) in the tumor stroma was mainly expressed in fibroblasts, which are a major stromal compartment of gastric cancer. Significance of LOXL2 remains unclear in gastric carcinoma. The aim of this study was to clarify the role of fibroblast-derived LOXL2 in the development of gastric cancer. Methods: Two gastric cancer cell lines, OCUM-12 and NUGC-3, and cancer-associated fibroblasts (CAF) were used in this in vitro study. The effect of fibroblast-derived LOXL2 on the motility of gastric cancer cells was analyzed by wound-healing assay, double-chamber invasion assay, and western blot. The correlation between LOXL2 expression and the clinicopathological features of 548 primary gastric carcinomas was examined by immunohistochemistry. Results: LOXL2 mRNA expression of CAF, was significantly higher than that of normal fibroblasts. CAF significantly stimulated the migration and invasion of OCUM-12 and NUGC-3 cells. This motility-stimulating ability of CAF was inhibited by LOXL2 siRNA. Western blot analysis indicated that phosphorylation of focal adhesion kinase (FAK) in cancer cells was increased by the conditioned medium from CAF, and was not affected by the conditioned medium from LOXL2 siRNA-treated CAF. Immunohistochemical study indicated that LOXL2 expression in stromal cells was significantly associated with tumor invasion depth, lymph node metastasis, lymphatic invasion, venous invasion, and peritoneal dissemination. The overall survival of all patients with LOXL2-positive stromal cells was significantly poorer than those with LOXL2-negative stromal cells. Multivariable logistic regression analysis revealed that LOXL2 expression in stromal cells was an independent predictive parameter for the overall survival of patients with gastric cancer. Conclusion: LOXL2 from CAF may stimulate the motility of gastric cancer cells. LOXL2 expression in stromal cells may be a useful prognostic factor for patients with gastric cancer. Citation Format: Hiroaki Kasashima, Masakazu Yashiro, Kisyu Kitayama, Go Masuda, Haruhito Kinoshita, Katsunobu Sakurai, Takahiro Toyokawa, Naoshi Kubo, Hiroaki Tanaka, Kazuya Muguruma, Masaichi Ohira, Kosei Hirakawa. Lysyl oxidase-like 2 (LOXL2) from cancer-associated fibroblasts stimulates the progression of gastric carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5063. doi:10.1158/1538-7445.AM2015-5063

L-type amino acid transporter 1 (LAT1) expression in lymph node metastasis of gastric carcinoma: Its correlation with size of metastatic lesion and Ki-67 labeling

L-type amino acid transporter 1 (LAT1) is one of the major amino acid transporters. High levels of LAT1 expression have been reported in various tumors, which can act as a novel prognostic marker. Previously, we demonstrated that LAT1 is highly expressed in advanced gastric carcinoma with lymph node metastasis, and proposed that LAT1 is an independent prognostic factor in non-scirrhous gastric carcinoma. The aim of the present study was to investigate the relationship between LAT1 expression and the size of lymph node metastatic lesions in gastric carcinoma. LAT1 and Ki-67 expression was immunohistochemically analyzed in 64 cases of advanced gastric carcinoma with lymph node metastasis. LAT1 expression in the metastatic lymph nodes was correlated with that in the primary lesions. The high LAT1 expression group showed a larger size of metastatic lesion and a higher Ki-67 labeling index than the low LAT1 expression group. LAT1 expression had a weak association with Ki-67 labeling index and tumor diameter of lymph nodes. These results suggest that LAT1 expression is associated with disease progression in gastric carcinoma. We proposed that LAT1 could be a potential therapeutic target for gastric carcinoma cases with large lymph node metastasis.

The expression of Cx43, TGF&amp;beta;/Smads signaling pathway and PCNA in the occurence and development of gastric carcinoma and the relationship among them

Background: To detect the Protein expression level of Cx43, Smad4 and PCNA in normal and gastric carcinoma tissue by immunohistochemistry, western blotting and RT-PCR method.Materials and Methods: Immunohistochemistry and western blotting were adopted to detect the expression and expression level of Cx43, Smad4 and PCNA protein in normal and carcinomatous gastric tissue. Experimental data were analyzed by combining clinical pathology data using statistical tools.Results: The expression levels of Cx43 and Smad4 in carcinomatous gastric tissue were lower than they were in normal gastric tissue. The expression level of PCNA in carcinomatous gastric tissue was higher than that in normal gastric tissue. The expression levels of Cx43, Smad4 and PCNA in groups of age and gender is not significant. The expression of Cx43, Smad4 and PCNA in different clinic pathologic features of carcinomatous gastric tissue which includes degrees of pathological differentiation, lymph node metastasis condition, depth of tumor invasion and TNM stages is statistically significant. With the progression of gastric carcinoma, the expression levels of Cx43 and Smad4 were decreased, conversely PCNA showed a high expression level.Conclusion: The protein and mRNA expressions of Cx43, Smad4 and PCNA were significantly different between normal gastric tissue and gastric carcinoma and also were concerned with degree of differentiation, lymph node metastasis, TNM stages and depth of invasion, though not significant with age and gender. This suggests that they may play an important role in occurrence and development of gastric carcinoma, but also may have some interaction.Journal of Pathology of Nepal (2015) Vol. 5, 696-704

Hyperglycemia Promotes Human Gastric Carcinoma Progression via Aquaporin 3.

Hyperglycemia plays an important role in the development of gastric carcinoma (GC). Aquaporin 3 (AQP3) is overexpressed in GC and involved in carcinogenesis and progression of GC. Hyperglycemia promotes AQP3 expression in human peritoneal mesothelial cells. To investigate whether hyperglycemia promotes progression of GC via AQP3. We enrolled 978 patients with GC and evaluated the correlation between preoperative fasting plasma glucose and clinicopathological features. AQP3 was detected by immunohistochemistry in human GC specimens. Western blotting and real-time quantitative polymerase chain reaction evaluated changes in AQP3 expression in human GC MGC803 and SGC7901 cells after co-culture with high glucose. Transwell migration and Cell Counting Kit-8 assays were used to determine migration and proliferation of GC cells. Hyperglycemia (fasting plasma glucose ≥6.1mM) correlated with tumor size, location, and pTNM stage. AQP3 expression in tumor tissue was associated with fasting plasma glucose levels. High glucose concentration upregulated AQP3 expression in a dose- and time-dependent manner. High glucose concentration promoted GC cell migration markedly, and AQP3 knockdown with siRNA could abolish the increase in cell migration. However, high glucose concentration inhibited cell proliferation, and AQP3 knockdown significantly enhanced the inhibitory effect of high glucose. The ERK and PI3K/AKT signaling pathways were involved in high glucose regulation of AQP3 in human GC cells. Hyperglycemia promotes GC progress via AQP3. This improves our understanding of the mechanism of hyperglycemia-induced carcinogenesis and provides a potential therapeutic strategy for GC.

Silencing profilin-1 inhibits gastric cancer progression via integrin β1/focal adhesion kinase pathway modulation.

To investigate the role of profilin-1 (PFN1) in gastric cancer and the underlying mechanisms. Immunohistochemical analysis, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were performed to detect PFN1 expression in clinical gastric carcinoma and adjacent tissues, and the association of PFN1 expression with patient clinicopathological characteristics was analyzed. PFN1 was knocked down to investigate the role of this protein in cell proliferation and metastasis in the SGC-7901 cell line. To explore the underlying mechanisms, the expression of integrin β1 and the activity of focal adhesion kinase (FAK) and the downstream proteins extracellular-regulated kinase (ERK)1/2, P38 mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) were measured through Western blot or qRT-PCR analysis. Fibronectin (FN), a ligand of integrin β1, was used to verify the correlation between alterations in the integrin β1/FAK pathway and changes in tumor cell aggressiveness upon PFN1 perturbation. Immunohistochemical, Western blot and qRT-PCR analyses revealed that PFN1 expression was higher at both the protein and mRNA levels in gastric carcinoma tissues compared with the adjacent tissues. In addition, high PFN1 expression (53/75, 70.4%) was correlated with tumor infiltration, lymph node metastasis and TNM stage in gastric cancer, but not with gender, age, location, tumor size, or histological differentiation. In vitro experiments showed that PFN1 knockdown inhibited the proliferation of SGC-7901 cells through the induction G0/G1 arrest. Silencing PFN1 inhibited cell migration and invasion and down-regulated the expression of matrix metalloproteinase (MMP)-2 and MMP9. Moreover, silencing PFN1 reduced the expression of integrin β1 at the protein level and inhibited the activity of FAK, and the downstream effectors ERK1/2, P38MAPK, PI3K, AKT and mTOR. FN-promoted cell proliferation and metastasis via the integrin β1/FAK pathway was ameliorated by PFN1 silencing. These findings suggest that PFN1 plays a critical role in gastric carcinoma progression, and these effects are likely mediated through the integrin β1/FAK pathway.

Geldanamycin mediates the apoptosis of gastric carcinoma cells through inhibition of EphA2 protein expression.

The aim of the present study was to investigate the role of EphA2 in the carcinogenesis and progression of gastric carcinoma. Moreover, we aimed to determine the effect of geldanamycin (GA), an inhibitor of Hsp90, on the proliferation and apoptosis of human gastric carcinoma cells. Gastric carcinoma tissues, paired adjacent mucosa and paired normal mucosa were obtained from resected surgical specimens of gastric carcinoma, and EphA2 mRNA and protein levels were assessed by RT-PCR, immunohistochemistry and western blot analysis. FCM was used to detect cell cycle distribution and apoptosis. MGC803 cell proliferation and apoptosis were assessed by MTT and FCM, respectively. We found that EphA2 protein was increased in the carcinogenesis of gastric epithelial cells. Proliferation index (PI) was significantly upregulated following an increase in EphA2 expression in gastric carcinoma compared with dysplasia and normal samples, and was notably correlated with grade and lymph node metastasis. Knockdown of EphA2 increased the apoptosis rate and decreased the PI of MGC803 cells, which overexpressed the EphA2 protein. GA inhibited the cell proliferation of MGC803 cells in a dose- and time-dependent manner and induced cell apoptosis. In addition, GA decreased the EphA2 protein expression in MGC803 cells. Overexpression of EphA2 inhibited cell growth, blocked cells in the G0/G1 stage and increased cell apoptosis induced by GA in MGC803 cells. However, knockdown of EphA2 in MGC803 cells increased the apoptosis ratio induced by GA. In conclusion, EphA2 overexpression is an important characteristic in the carcinogenesis of gastric epithelial cells, followed by an increase in apoptosis and cell cycle arrest. Knockdown of EphA2 blocked MGC803 cell proliferation and induced cell apoptosis. In conclusion GA inhibits MGC803 cell proliferation and induces cell apoptosis by upregulating expression of EphA2.

Ubiquitin-specific peptidase 22 overexpression may promote cancer progression and poor prognosis in human gastric carcinoma

Ubiquitin-specific peptidase 22 (USP22) was recently identified as a new tumor cell marker, and previous studies demonstrated its expression in a variety of tumors and its correlation with tumor progression. Because tumor progression plays an important role in cancer, researchers are paying more attention to the correlation between USP22 expression and metastatic potential, resistance to chemotherapy, and patient prognosis. This study showed that USP22 is highly expressed in gastric cancer tissues, and significant differences in USP22 expression (P < 0.01) were identified between different types of gastric cancer (the highest expression was found in poorly differentiated adenocarcinomas). In addition USP22 expression was found to be correlated with the promotion of cancer evolution, tumor invasion, and lymph node metastasis. The C-myc protein was also shown to have synergistic effects with USP22 in gastric cancer tissue. On the basis of the results, USP22 expression may play an important role in gastric carcinoma tissue, particularly in precancerous lesions during the gastric cancer evolution process.

Downregulation of Runx3 is closely related to the decreased Th1-associated factors in patients with gastric carcinoma.

Runt-related transcription factor 3 (Runx3) is a tumor-suppressor gene and plays an important role in immune regulation, whose reduced expression may play an important role in the development and progression of gastric carcinoma. The aim of this study was to investigate the role of Runx3 on the levels of transcription factors in patients with gastric carcinoma and analyze the relationship between the expression of Runx3 and Th1-type cytokines in peripheral blood mononuclear cells (PBMCs). Our results showed that the expression levels of Runx3, T-bet, and IFN-γ in patients with gastric carcinoma were obviously lower than those in control groups, and there was a positive correlation between the expression of Runx3 and T-bet or IFN-γ in patients (p < 0.01). In order to further confirm this result, the Runx3 gene was constructed into pIRES2-eGFP and the recombined plasmid was transfected into SGC-7901 cells with liposome in vitro, the results obtained from the reverse transcription PCR indicated that the mRNA of Runx3, T-bet, or IFN-γ was significantly upregulated individually in Runx3 gene-transfected SGC-7901 cells. It suggested that the Runx3 and Th1-associated factors including T-bet and IFN-γ synchronization declines in gastric carcinoma may contribute to the development of cancer.