Expression of phosphorylated Akt (pAkt) in gastric carcinoma predicts prognosis and efficacy of chemotherapy

3,3'-Diindolylmethane Augments 5-Fluorouracil-InducedGrowth Suppression in Gastric Cancer Cells through Suppression of the Akt/GSK-3β and WNT/Beta-Catenin

Gastric cancer (GC) is one of the most lethal cancers in South Korea, and it is a cancer of concern worldwide. 5-fluorouracil (5-Fu) is commonly used as the first-line therapy for advanced GC; however, its side effects often limit the dosage range and impair patients' quality of life. Due to the limitations of current chemotherapy, new anticancer therapies are urgently needed. 3,3'-diindolylmethane (DIM) has been reported to have the ability to protect against various types of cancer. Our study aimed to elucidate the anticancer effect of DIM in GC when treated with the chemotherapeutic agent 5-Fu. In our results, combined treatment with DIM and 5-Fu resulted in higher apoptosis and lower cell proliferation than treatment with 5-Fu in SNU484 and SNU638 cell lines. Furthermore, when DIM and 5-Fu were administered together, cell invasion was diminished by mediated E-cadherin, MMP-9, and uPA; p-Akt and p-GSK-3β levels were reduced more significantly than when 5-Fu was administered alone. Moreover, in the Wnt signaling pathway, combined treatment of DIM and 5-Fu diminished β-catenin levels in the nucleus and inhibited cyclin D1and c-Myc protein levels. The Akt inhibitor, wortmannin, further inhibited the levels of β-catenin and c-Myc that were inhibited by DIM and 5-Fu. Furthermore, an animal xenograft model demonstrated that DIM combined with 5-Fu considerably reduced tumor growth without any toxic effects by regulating the Akt/GSK-3β and β-catenin levels. Our findings suggest that DIM significantly potentiates the anticancer effects of 5-Fu by targeting the Akt/GSK-3β and WNT/β-catenin because the combination therapy is more effective than 5-Fu alone, thereby offering an innovative potential therapy for patients with GC.

Increased Expression of POSTN Predicts Poor Prognosis: a Potential Therapeutic Target for Gastric Cancer

BACKGROUND

Periostin (POSTN) is involved in many biological processes and is associated with the occurrence and development of several cancers, while its role in gastric cancer is not clear. We aimed to demonstrate the relationship between POSTN and gastric cancer based on publicly available data from The Cancer Genome Atlas (TCGA) database.

METHODS

POSTN expression data and corresponding clinical information were downloaded from TCGA database. We compared the expression of POSTN in gastric cancer samples and normal samples. POSTN-related differentially expressed genes (DEGs) were identified for further functional enrichment analysis. In addition, the relationships between POSTN expression and clinicopathological features and survival in patients with gastric cancer were also investigated through univariate and multivariate Cox regression analyses. Furthermore, a nomogram was constructed to predict the survival probability of gastric cancer patients.

RESULTS

POSTN expression in gastric cancer was significantly higher than that in normal gastric tissues (p < 0.001). High POSTN expression in gastric cancer was significantly related to poor prognostic features, including greater tumor extent (odds ratio [OR] = 1.638 for T3 and T4 vs. T1 and T2), worse histological type (OR = 0.329 for diffuse type vs. tubular type), and advanced histological grade (OR = 1.646 for grade 3 vs. grades 1 and 2) (all p < 0.05). The 118 identified DEGs were primarily enriched in pathways related to tumorigenesis and tumor progression, including the TGF-β signaling pathway, the WNT signaling pathway, and the signaling by VEGF. POSTN expression was positively correlated with the enrichment of the macrophages (r = 0.599, p < 0.001), helper T2 cells (r = 0.146, p = 0.005), and CD8 + T cells (r = 0.190, p < 0.001), but negatively correlated with the enrichment of Th17 cells (r =  - 0.130, p = 0.012) and NK CD56bright cells. Kaplan-Meier survival analysis showed that high POSTN expression is associated with a short overall survival (hazard ratio [HR] = 1.54; p = 0.011). In the multivariate cox regression analysis, high POSTN expression was confirmed to be an independent predictor of poor overall survival (HR = 1.681; p = 0.017). The constructed nomogram can well predict the 1 and 3 years overall survival probability of patients with GC (0.696 [95% CI, 0.671-0.721]).

CONCLUSION

POSTN plays an important role in the progression and prognosis of gastric cancer, and it may serve as a useful biomarker to predict survival in gastric cancer patients.

LC3B, mTOR, AMPK Are Molecular Targets for Neoadjuvant Chemotherapy in Gastric Cancers

Autophagy plays a dual role in oncogenesis processes. On one hand, autophagy enhances the cell resistance to oncogenic factors, and on the other hand, it participates in the tumor progression. The aim of the study was to find the associations between the effectiveness of the FLOT regimen in resectable gastric cancers (GCs) with the key autophagy-related proteins. Materials and Methods: The study included 34 patients with morphologically verified gastric cancer. All patients had FLOT neoadjunvant chemotherapy (NACT) (fluorouracil, leucovorin, oxaliplatin, and docetaxel) followed by gastrectomy. The studied tissue material was the non-transformed and tumor tissues obtained during diagnostic video gastroscopy in patients before the start of the combined treatment and after surgical treatment, frozen after collection. The LC3B, mTOR, and AMPK expression was determined by real-time PCR. The content of the LC3B protein was determined by Western blotting analysis. Results: The mRNA level and the content of the LC3B protein were associated with the tumor stage and the presence of signet ring cells. The AMPK mRNA level was increased in patients with the T4N0-2M0 stage by 37.7 and 7.33 times, which was consequently compared with patients with the T2N0M0 and T3N0-1M0 stages. The opposite changes in the mTOR and AMPK in the GCs before anti-cancer therapy were noted. The tumor size and regional lymph node affections were associated with a decrease in the mTOR mRNA level. A decrease in the mTOR expression was accompanied by an increase in the AMPK expression in the GCs. The mTOR expression was reduced in patients with a cancer spreading; in contrast, AMPK grew with the tumor size. There was an increase in the LC3B expression, which can probably determine the response to therapy. An increase in LC3B mRNA before the start of treatment and the protein content in cancers after NACT with a decrease in therapy effectiveness was recorded. There was an increase in the protein level in patients with partial regression and stabilization by 3.65 and 5.78 times, respectively, when compared with patients with complete tumor regression was noted. Conclusions: The anticancer effectiveness in GCS is down to the LC3B, mTOR, and AMPK expression. These were found to be entire molecular targets affecting the cancer progression and metastasis as well as the NACT effectiveness.

Molecular target: pan-AKT in gastric cancer

The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signalling pathway is involved in multiple cellular processes, including cell survival, proliferation, differentiation, metabolism and cytoskeletal reorganisation. The downstream effectors of this PI3K pathway are also essential for maintaining physiologic homeostasis, commonly dysregulated in most solid tumours. AKT is the key regulator in PI3K/AKT/mTOR signalling, interacting with multiple intracellular molecules. AKT activation subsequently leads to a number of potential downstream effects, and its aberrant activation results in the pathogenesis of cancer. Accordingly, as an attractive therapeutic target for cancer treatment, several AKT inhibitors are currently under development and in multiple stages of clinical trials for various types of malignancy, including gastric cancer (GC). Therefore, the authors review the significance of AKT and recent studies on AKT inhibitors in GC, focusing on the scientific background with the potential to improve treatment outcomes.

Network pharmacology-based identification of the antitumor effects of taraxasterol in gastric cancer

Taraxasterol (TAX), a pentacyclic triterpene, has been reported to exhibit potent antitumor activity. However, the effects and molecular mechanisms of TAX in gastric cancer (GC) remain undocumented. A network pharmacology approach was applied to identify the collective targets of TAX and GC. Nude mice were subcutaneously injected with MKN-28 cells to establish GC subcutaneous xenograft model, which were treated with TAX for 16 days. Tumor volume was then examined every other day. The pathological scoring was assessed by using hematoxylin and eosin (H&E) staining, and the expression levels of Ki-67 and the target genes of TAX were confirmed by immunohistochemistry analysis. Five collective targets of TAX and GC were identified, such as epidermal growth factor receptor (EGFR), matrix metalloproteinase 2 (MMP2), B-Raf proto-oncogene, serine/threonine kinase (BRAF), fibroblast growth factor receptor 2 (FGFR2), and AKT serine/threonine kinase 1 (AKT1). Further investigations showed that, TAX administration repressed xenograft tumor growth and decreased Ki-67 levels, followed by the downregulation of EGFR and AKT1 expression in xenograft tumor tissues as compared with the untreated group. Our findings demonstrated that TAX inhibited the growth of GC by inhibition of EGFR/AKT1 signaling and might provide a novel therapeutic strategy for treatment of GC.

Facing Cell Autophagy in Gastric Cancer - What Do We Know so Far?

Autophagy is a process by which misfolded proteins and damaged organelles in the lysosomes of tumor cells were degraded reusing decomposed substances and avoiding accumulation of large amounts of harmful substances. Here, the role of autophagy in the development of malignant transformation of gastric tumors, and the underlying mechanisms involved in autophagy formation, and the application of targeted autophagy in the treatment of gastric cancer were summarized.

Ceritinib increases sensitivity of AKT inhibitors to gastric cancer

Gastric cancer (GC), known for high morbidity and mortality, is poorly prognosed with traditional chemotherapy and biological agents. Current studies have found that over-activation of AKT is a common molecular characteristic in GC. Although the development of this targeted inhibitor has entered clinical phases, limited success is reported because of its compensatory signaling pathways. Here, we found that GC cell lines with high phosphorylation of AKT show different sensitivity to AKT inhibitors (AKTis), but a reduction of p-GSK3β related sensitivity of AKTis in GC cells. Besides, we revealed that Ceritinib exerted a strongly synergistic antitumor effect with AKT inhibitors both in vitro and in vivo. Obviously, Ceritinib improved the sensitivity of Capivasertib (AZD5363, AKTs) and Afuresertib (GSK2110183, AKTis) in gastric cancer cells, as illustrated by a significant reduction in the GC cell proliferation and enhanced apoptosis. The drug combination showed tumor regression in BALB/c (nu/nu) mouse MKN45 (Gastric cancer), tumor model. Also, the combination strategy indicated significantly low p-AKT levels due to AKTis compensation and reduced the levels of p-GSK3β in both GC cell lines and GC patient-derived cells. These findings may provide a novel combination strategy for gastric cancer treatment.

AKT/mTOR Signal Cascade and Expression of PD-1, PD-L1, and PD-L2 in Gastric Cancer

The peculiarities of gastric cancer development associated with the expression levels of components of the AKT/mTOR signaling cascade and PD, PD-L1, PD-L2 have not yet been identified. We revealed the fundamental changes in the expression AKT/mTOR and PD receptors and their ligands associated with dissemination of gastric cancer. An increase in the mRNA level of all components of this cascade was demonstrated. The expression of mTOR and AKT decreased against the background of enhanced expression of PTEN phosphatase. The increase in the expression of PD-1 receptors and PD-L1 and PD-L2 ligands was most pronounced in patients with distant metastases.

Differential expression of HER2 and downstream proteins in prediction of advanced tumor phenotypes and overall survival of patients with Epstein-Barr virus-positive vs. negative gastric cancers

This study evaluated the associations of HER2 protein, HER2 gene amplification, and positivity for p-AKT, p-ERK, and p-PLCγ proteins with clinicopathological status and overall survival (OS) of patients who had Epstein-Barr virus-associated gastric cancer (EBVaGC; n = 58) or EBV-negative GC (EBVnGC; n = 329). Tissue samples were subjected to immunohistochemistry and fluorescence in situ hybridization (FISH). Results showed that EBVaGC less expressed HER2 and amplified HER2 gene. p-AKT (p =  0.035) and p-ERK (p =  0.001) were inhibited in EBVaGC than in EBVnGC, while p-PLCγ (p =  0.034) was upregulated. Among EBVaGC patients, p-ERK positivity was associated with Lauren classification (p = 0.023), and p-PLCγ positivity was inversely associated with TNM stage (p = 0.041) and lymph node metastasis (p = 0.041). In contrast, among EBVnGC patients, HER2 expression was associated with distant metastasis (p = 0.043) and p-AKT positivity was associated with intestinal subtype (p < 0.004), lymph node metastasis (p = 0.031), distant metastasis (p < 0.001), and elder age (>60y, p < 0.004). Overall analysis showed that EBVaGC patients presented better OS than EBVnGC patients (p = 0.044). Among EBVaGC patients, p-AKT positivity (p = 0.008) was associated with worse OS; as well as, HER2 high expression (p < 0.001), p-AKT positivity (p = 0.010), and p-PLCγ (p <  0.001) were associated with worse OS in EBVnGC patients. Multivariate analysis showed that distant metastasis (95% CI: 1.559 to 4.028, p <  0.001), HER2 high expression (95% CI: 1.058 to 2.454, p =  0.026), and p-PLCγ positivity (95% CI: 1.056 to 2.435, p = 0.027) were independent prognostic predictors of OS in EBVnGC patients. Our results indicated that p-AKT positive patients presented worse OS than p-AKT negative ones in EBVaGC, as well as, HER2, p-AKT, and p-PLCγ are prognostic biomarkers for OS in EBVnGC patients.

Akt in cancer: Mediator and more

Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.

Increased expression of methionine sulfoxide reductases B3 is associated with poor prognosis in gastric cancer

The present study aimed to investigate the expression of methionine sulfoxide reductases B3 (MSRB3) in gastric cancer (GC) and its clinical significance. A total of 90 specimens from patients with GC were collected to evaluate MSRB3 protein expression by immunohistochemical staining. The associations between MSRB3 protein expression, clinicopathological characteristics and prognosis of patients with GC were subsequently investigated. The results demonstrated that MSRB3 protein expression in GC tissues samples was significantly higher compared with that in paired adjacent normal tissues (P=0.017). Among the 90 GC cases, 64 (71.1%) exhibited higher MSRB3 expression. In addition, the diagnostic value of MSRB3 for patients with GC was estimated with a sensitivity of 71.1% and a specificity of 46.7%. However, MSRB3 expression was not associated with clinicopathological characteristics of patients with GC. Kaplan-Meier analysis indicated that patients with high MSRB3 expression had significantly shorter overall survival (OS) times compared with those with low expression (P=0.040). Univariate Cox regression analysis indicated that maximum tumor diameter, depth of invasion, lymph node metastasis, Tumor-Node-Metastasis (TNM) stage and MSRB3 expression were significantly associated with OS time. Multivariate Cox regression analysis indicated that MSRB3 was an independent predicting factor for the OS time of patients with GC (P=0.049). In addition, analysis using The Cancer Genome Atlas (TCGA) database validated these results. Kaplan-Meier analysis revealed that higher MSRB3 mRNA expression was associated with poorer OS time in 442 patients with GC (P=0.004). Univariate analysis of the TCGA data indicated that age, depth of invasion, lymph node metastasis, distant metastasis, TNM stage and MSRB3 expression were significantly associated with OS time; however, sex and histological differentiation were not associated with OS time. Multivariate analysis demonstrated that MSRB3 was an independent prognostic factor in patients with GC (P=0.001). In conclusion, these results demonstrated that MSRB3 expression was upregulated in patients GC, which suggests that MSBR3 may serve as a potential prognostic biomarker.

Genetic Variants Within MTORC1 Genes Predict Gastric Cancer Prognosis in Chinese Populations

Objective: Mammalian target of rapamycin complex 1 (mTORC1) plays an important role in maintaining proper cellular functions in gastric cancer (GC). Previous studies demonstrated genetic variants within mTORC1 genes were associated with GC risk. However, no studies reported the associations between genetic variants within mTORC1 genes and GC prognosis. Herein, we firstly assessed the associations of genetic variants of mTORC1 genes with overall survival (OS) of GC in Chinese populations.

Methods: We genotyped eight single nucleotide polymorphisms (SNPs) in mTORC1 genes (i.e., rs2536 T>C and rs1883965 G>A for mTOR, rs3160 T>C and rs26865 A>G for MLST8, rs3751934 C>A, rs1062935 T>C, rs3751932 T>C and rs12602885 G>A for RPTOR) by the TaqMan method in 197 Chinese GC patients who had surgical resection in Xinhua Hospital. We conducted Kaplan-Meier survival plots and Cox hazards regression analysis to explore the associations of these SNPs with OS.

Results: The single-locus analysis indicated that RPTOR rs1062935 T>C was associated with an increased risk of poor GC prognosis (CC vs. TT/TC: adjusted Hazard ratio (HR) = 1.71, 95% confidence interval (CI) = 1.04-2.82). The combined analysis of all eight SNPs showed that patients with more than three risk genotypes significantly increased risk of death (adjusted HR = 2.44, 95% CI = 1.30-4.58), when compared to those with three or less risk genotypes.

Conclusions: Our findings indicated that genetic variants within mTORC1 genes may predict GC prognosis in Chinese populations. The results need to be validated in future studies with larger sample sizes.

Positive feedback loop of IL-1β/Akt/RARα/Akt signaling mediates oncogenic property of RARα in gastric carcinoma

Abnormal expression and function of retinoic acid receptor α (RARα) have been reported to be associated with various cancers including acute promyelocytic leukemia and hepatocellular carcinoma. However, the role and the mechanism of RARα in gastric carcinoma (GC) were unknown. Here, the expression of RARα was frequently elevated in human GC tissues and cell lines, and its overexpression was closely correlated with tumor size, lymph node metastasis and clinical stages in GC patients. Moreover, RARα overexpression was related with pathological differentiation. Functionally, RARα knockdown inhibited the proliferation and metastasis of GC cells, as well as enhanced drug susceptibility both in vitro and in vivo. Additionally, RARα knockdown suppressed GC progression through regulating the expression of cell proliferation, cell cycle, invasion and drug resistance associated proteins, such as PCNA, CyclinB1, CyclinD2, CyclinE, p21, MMP9 and MDR1. Mechanistically, the above oncogenic properties of RARα in GC were closely associated with Akt signaling activation. Moreover, overexpression of RARα was induced by IL-1β/Akt signaling activation, which suggested a positive feedback loop of IL-1β/Akt/RARα/Akt signaling in GC. Taken together, we demonstrated that RARα was frequently elevated in GC and exerted oncogenic properties. It might be a potential molecular target for GC treatment.

Identification of key miRNAs and genes associated with stomach adenocarcinoma from The Cancer Genome Atlas database

Stomach adenocarcinoma (STAD) is the second leading cause of cancer death and a fuller understanding of its molecular basis is needed to develop new therapeutic targets. miRNA and mRNA data were downloaded from The Cancer Genome Atlas database, and the differentially expressed miRNAs and genes were identified. The target genes of differentially expressed miRNAs were screened by prediction tools. Furthermore, the biological function of these target genes was investigated. Several key miRNAs and their target genes were selected for validation using quantitative real-time polymerase chain reaction (qRT-PCR). The Gene Expression Omnibus (GEO) dataset was used to verify the expression of selected miRNAs and target genes. The diagnostic value of identified miRNAs and genes was accessed by receiver operating characteristic analysis. A total of 1248 differentially expressed genes were identified in STAD. Additionally, nine differentially expressed miRNAs were identified and 160 target genes of these nine miRNAs were identified via target gene detection. Interestingly, they were remarkably enriched in the calcium signaling pathway and bile secretion. qRT-PCR confirmed the expression of several key miRNAs and their target genes. The expression levels of hsa-miR-145-3p, hsa-miR-145-5p, ADAM12,ACAN,HOXC11 and MMP11 in the GEO database were compatible with the bioinformatics results. hsa-miR-139-5p, hsa-miR-145-3p and MMP11 have a potential diagnostic value for STAD. Differential expression of the mature form of miRNAs (hsa-miR-139-5p, hsa-miR-145-3p, hsa-miR-145-5p and hsa-miR-490-3p) and genes including ADAM12,ACAN,HOXC11 and MMP11 and calcium and bile secretion signaling pathways may play important roles in the development of STAD.

Positive prognostic value of HER2-HER3 co-expression and p-mTOR in gastric cancer patients

Background

The HER2-HER3 heterodimer significantly decreases survival in breast cancer patients. However, the prognostic value of HER2-HER3 overexpression remains unknown in gastric cancer (GC).

Methods

The expression levels of HER2, HER3, Akt, p-Akt, mTOR and p-mTOR were examined in specimens from 120 GC patients by immunohistochemistry and quantitative reverse transcription-PCR. The associations of HER proteins, PI3K/Akt/mTOR pathway-related proteins, clinicopathological features of GC, and overall survival (OS) were assessed. To comprehensively evaluate the prognostic values of pathway-related proteins, meta-analyses were conducted with STATA 11.0.

Results

HER2 overexpression was significantly associated with HER3 levels (P = 0.02). HER3 was highly expressed in gastric cancer tissues. High HER2 and HER3 levels were associated with elevated p-Akt and p-mTOR amounts (P < 0.05). Furthermore, HER2-HER3 co-expression was associated with high p-Akt and p-mTOR (P < 0.05) levels. Meanwhile, p-mTOR overexpression was tightly associated with differentiation, depth of invasion, lymph node metastasis, TNM stage and OS (P < 0.05). By meta-analyses, Akt, p-Akt, and mTOR levels were unrelated to clinicopathological characters. HER3 overexpression was associated with depth of invasion (OR = 2.39, 95%CI 1.62–3.54, P < 0.001) and lymph node metastasis (OR = 2.35, 95%CI 1.34–4.11, P = 0.003). Further, p-mTOR overexpression was associated with patient age, tumor location, depth of invasion (OR = 1.63, 95%CI 1.08–2.45, P = 0.02) and TNM stage (OR = 1.73, 95%CI 1.29–2.32, P < 0.001). In addition, HER2-HER3 overexpression corresponded to gradually shortened 5-year OS (P < 0.05), and significant relationships were shown among HER3, p-mTOR overexpression, and 1-, 3-, 5-year OS (P < 0.05).

Conclusions

HER2-HER3 co-expression may potentially enhance mTOR phosphorylation. HER2-HER3 co-expression and p-mTOR are both related to the prognosis of GC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3851-y) contains supplementary material, which is available to authorized users.

Clinical Significance of p53 Protein Expression, Beta-catenin Expression and HER2 Expression for Epstein-Barr Virus-associated Gastric Cancer

This study assessed the expression of the p53 protein, beta-catenin, and HER2 and their prognostic implications in patients with EBV-associated gastric cancer (EBVaGC). After reviewing 1318 consecutive cases of surgically resected or endoscopic submucosal dissected gastric cancers, 117 patients were identified as EBV-positive using EBV-encoded RNA in-situ hybridization. The immunohistochemistry results were interpreted as follows: strong p53 nuclear expression in at least 50% of tumor nuclei was interpreted as a positive result, strong beta-catenin expression in at least 10% of cytoplasmic nuclei was interpreted as a positive result, and moderate or strong complete or basolateral membrane staining in 10% of tumor cells was interpreted as a positive result for HER2. Immunohistochemical staining for p53 was performed on tumor tissue from 105 patients, among whom 25 (23.8%) tested positive. Meanwhile, beta-catenin expression was positive in 10 patients (17.5%) and HER2 expression was positive in 8 patients (6.8%). The positive expression of p53 was significantly associated with a high T stage (p=0.006). More patients with lymph node metastasis were p53-positive (p=0.013). In the univariate analysis, the p53-positive patients showed significantly decreased disease-free survival (DFS) when compared with the p53-negative patients (p=0.022), although the p53 status was only marginally associated with overall survival (OS) (p=0.080). However, p53 expression showed no prognostic significance on DFS in the multivariate analysis. Moreover, beta-catenin and HER2 showed no association with DFS and OS in the survival analysis. The current study found a significant correlation between p53 expression and tumor progression and lymph node metastases in patients with EBVaGC.

p-Akt as a potential poor prognostic factor for gastric cancer: a systematic review and meta-analysis

To understand the relationship between p-Akt expression and the prognosis of patients with gastric cancer, we searched six databases, Pubmed, EMBASE, Cochrane Library, CNKI, Wanfang and CBM for relevant articles in order to conduct this metaanalysis. The pooled hazard ratios and corresponding 95%CI of overall survival were calculated to evaluate the prognostic value of p-Akt expression in patients with gastric cancer. With 2261 patients combined from 13 available studies, the pooled HR showed a poor prognosis in patients with gastric cancer in the univariate analysis (HR=1.88, 95%CI:1.45-2.43, P<0.00001), and the group "univariate analysis+estimate" (HR=1.41, 95%CI: 1.01-1.97, P=0.04), but not in multivariate analysis (HR=0.66, 95%CI: 0.29-1.52, P=0.33) and estimate (HR=1.13, 95%CI: 0.65-1.95, P=0.67). In conclusion, our results indicated that p-Akt was likely to be an indicator of poor prognosis in patients with gastric cancer.

Molecular mechanisms of chemoresistance in gastric cancer

Gastric cancer is the fourth most common cancer and the second leading cause of cancer deaths worldwide. Chemotherapy is one of the major treatments for gastric cancer, but drug resistance limits the effectiveness of chemotherapy, which results in treatment failure. Resistance to chemotherapy can be present intrinsically before the administration of chemotherapy or it can develop during chemotherapy. The mechanisms of chemotherapy resistance in gastric cancer are complex and multifactorial. A variety of factors have been demonstrated to be involved in chemoresistance, including the reduced intracellular concentrations of drugs, alterations in drug targets, the dysregulation of cell survival and death signaling pathways, and interactions between cancer cells and the tumor microenvironment. This review focuses on the molecular mechanisms of chemoresistance in gastric cancer and on recent studies that have sought to overcome the underlying mechanisms of chemoresistance.

Visualization of sphingolipids and phospholipids in the fundic gland mucosa of human stomach using imaging mass spectrometry

AIM: To analyze the lipid distribution in gastric mucosae.

METHODS: Imaging mass spectrometry (MS) is a useful tool to survey the distribution of biomolecules in surgical specimens. Here we used the imaging MS apparatus named iMScope to identify the dominant molecules present in the human gastric mucosa near the fundic glands. Five gastric specimens were subjected to iMScope analysis. These specimens were also analyzed by immunohistochemistry using MUC5AC, H(+)-K(+)-ATPaseβ Claudin18 antibodies.

RESULTS: Three major molecules with m/z 725.5, 780.5, and 782.5 detected in the gastric mucosa were identified as sphingomyelin (SM) (d18:1/16:0), phosphatidylcholine (PC) (16:0/18:2), and PC (16:0/18:1), respectively, through MS/MS analyses. Using immunohistological staining, SM (d18:1/16:0) signals were mainly co-localized with the foveolar epithelium marker MUC5AC. In contrast, PC (16:0/18:2) signals were observed in the region testing positive for the fundic gland marker H(+)-K(+)-ATPaseβ. PC (16:0/18:1) signals were uniformly distributed throughout the mucosa.

CONCLUSION: Our basic data will contribute to the studies of lipid species in physical and pathological conditions of the human stomach.

Silencing A7-nAChR levels increases the sensitivity of gastric cancer cells to ixabepilone treatment

Gastric cancer is an important health issue worldwide. Currently, improving the therapeutic efficacy of chemotherapy drugs is an important goal of cancer research. Alpha-7 nicotine acetylcholine receptor (A7-nAChR) is the key molecule that mediates gastric cancer progression, metastasis, and therapy responses; however, the role of A7-nAChR in the therapeutic efficacy of ixabepilone remains unclear. A7-nAChR expression was silenced by small interfering RNA (siRNA) technology. The cytotoxicity of ixabepilone was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and ixabepilone-induced apoptosis was analyzed by flow cytometry and annexin V/propidium iodide (PI) apoptotic assay. The expression patterns of anti-apoptotic proteins (AKT, phospho-AKT, Mcl-1, and Bcl-2) and pro-apoptotic proteins (Bad and Bax) were determined by western blot. Our study found that A7-nAChR knockdown (A7-nAChR-KD) AGS cells were more sensitive to ixabepilone administration than scrambled control AGS cells. We found that A7-nAChR knockdown enhanced ixabepilone-induced cell death as evidenced by the increased number of annexin V-positive (apoptotic) cells. After scrambled control and A7-nAChR-KD cells were treated with ixabepilone, we found that pAKT and AKT levels were significantly reduced in both groups of cells. The levels of Bcl-2 and the anti-apoptotic Mcl-1 isoform increased dramatically after ixabepilone treatment in scrambled control cells but not in A7-nAChR-KD cells. Bad and Bax levels did not change between the treatment group and vehicle group in both A7-nAChR-KD and scrambled control cells, whereas cleaved PARP levels dramatically increased in ixabepilone-treated A7-nAChR-KD cells. Our results demonstrated that knockdown of A7-nAChR enhanced the sensitivity of gastric cancer cells to ixabepilone administration. Thus, the A7-nAChR expression level in patients with gastric cancer may be a good indicator of ixabepilone sensitivity.

Prognostic significance of p53 in gastric cancer: a meta- analysis

BACKGROUND

Gastric cancer is one of the frequently seen cancers in the world and it is the second most common reason for death due to cancer. The prognostic role of expression of p53 detected by immunohistochemistry in gastric cancer remains controversial. This meta-analysis aimed to explore any association between overexpression and survival outcomes.

MATERIALS AND METHODS

We systematically searched for studies investigating the relationships between expression of p53 detected by immunohistochemistry and prognosis of gastric cancer patients. Study quality was assessed using the Newcastle-Ottawa Scale. After careful review, survival data were extracted from eligible studies. A meta-analysis was performed to generate combined hazard ratios for overall survival and disease-free survival.

RESULTS

A total of 4.330 patients from 21 studies were included in the analysis. Our results showed tissue p53 overexpression in patients with gastric cancer to be associated with poor prognosis in terms of overall survival (HR, 1.610; 95% CI, 1.394 -5.235; p: <0.001). Pooled hazard ratio for disease free survival showed that p53 positivity or negativity were not statitistically significant (HR, 1.219; 95%CI, 0.782-1.899; p:0.382).

CONCLUSIONS

The present meta-analysis indicated overexpression of p53 detected by immunohistochemistry to be associated with a poor prognosis in patients with gastric cancer.

Molecular classification of gastric adenocarcinoma: translating new insights from the cancer genome atlas research network

Gastric cancer is a heterogenous cancer, which may be classified into several distinct subtypes based on pathology and epidemiology, each with different initiating pathological processes and each possibly having different tumor biology. A classification of gastric cancer should be important to select patients who can benefit from the targeted therapies or to precisely predict prognosis. The Cancer Genome Atlas (TCGA) study collaborated with previous reports regarding subtyping gastric cancer but also proposed a refined classification based on molecular characteristics. The addition of the new molecular classification strategy to a current classical subtyping may be a promising option, particularly stratification by Epstein-Barr virus (EBV) and microsatellite instability (MSI) statuses. According to TCGA study, EBV gastric cancer patients may benefit the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) antibodies or phosphoinositide 3-kinase (PI3K) inhibitors which are now being developed. The discoveries of predictive biomarkers should improve patient care and individualized medicine in the management since the targeted therapies may have the potential to change the landscape of gastric cancer treatment, moreover leading to both better understanding of the heterogeneity and better outcomes. Patient enrichment by predictive biomarkers for new treatment strategies will be critical to improve clinical outcomes. Additionally, liquid biopsies will be able to enable us to monitor in real-time molecular escape mechanism, resulting in better treatment strategies.

Elevated Rictor expression is associated with tumor progression and poor prognosis in patients with gastric cancer

The rapamycin insensitive companion of mTOR (Rictor) is an essential subunit of mTOR complex 2 (mTORC2), maintains the integrity of the complex and functions as regulator of Akt full activation. Rictor has been implicated to be involved in growth and progression of malignancies, however, little is known about its expression and prognostic role in gastric cancer in particular. Therefore, we investigated the relationship of Rictor expression with clinical outcomes, together with pAktSer473 and pS6, two downstream substrates of mTORC2 and mTORC1, in 396 gastric cancer tissue samples via immunohistochemistry. The results showed that 74.0% and 55.8% of tumors were Rictor and pAktSer473 positive staining, respectively, which correlated well with each other. Patients with positive expressions had poorer overall survival and relapse-free survival compared with those negative staining. Both Rictor and pAktSer473 expression were associated with lymph node metastasis, TNM stage, and WHO grading. Rictor was also correlated with tumor size, depth of invasion, and tumor thrombus, while pAktSer473 was also correlated with distant metastasis. In spite of 67.4% expression rate was presented in gastric cancer tissues, no significant association was observed between pS6Ser235/236, representing mTORC1 activity, and clinicopathological features or prognosis. These results suggest that mTORC2/Rictor/pAkt may play a more important role than mTORC1/pS6 in tumor progression, which could act as a prognostic biomarker or potential therapeutic target in gastric cancer.

Lymphangiogenesis in gastric cancer regulated through Akt/mTOR-VEGF-C/VEGF-D axis

BACKGROUND

Lymphangiogenesis plays a significant role in metastasis and recurrence of gastric cancer. There is no report yet focusing on the modulation of VEGF pathway and lymphangiogenesis of gastric cancer by targeting Akt/mTOR pathway. This study aims to demonstrate the relationship between Akt/mTOR pathway and VEGF-C/-D in gastric cancer.

METHODS

We collected surgically resected gastric adenocarcinoma specimens from 55 consented patients. Immunohistochemistry staining of p-Akt, p-mTOR, VEGF-C, VEGF-D were performed and scored by two independent pathologists. The results were presented as staining intensity and positive staining cell rate. We also measured lymphatic vessel density (LVD) by D2-40 staining. Different dosages of p-Akt inhibitor LY294002 (12.5 μM, 25 μM, 50 μM) and p-mTOR inhibitor Rapamycin (25 nM, 50 nM, 100 nM) were given to gastric cancer cell line SGC-7901 in vitro. The inhibition rate of cell growth was tested by MTT at 24 h, 48 h and 72 h, respectively and protein expressions of Akt, p-Akt, mTOR, p-mTOR, VEGF-C and VEGF-D were examined by Western blot.

RESULTS

The positive staining rates of p-Akt, p-mTOR, VEGF-C and VEGF-D in 55 gastric cancer clinical specimens were 74.54%, 85.45%, 72.73% and 58.18%. p-Akt and p-mTOR were positively correlated with VEGF-C and VEGF-D (p < 0.01). The LVD increased with incremental tendency of staining intensity of p-Akt, p-mTOR, VEGF-C and VEGF-D. LY294002 or Rapamycin significantly suppressed SGC-7901 cell growth and the inhibition rate was dose and time dependent (p < 0.001). In addition, the protein expression of p-Akt and p-mTOR were positively correlated with that of VEGF-C and VEGF-D (p < 0.05).

CONCLUSIONS

The level of LVD in gastric cancer specimens was significant higher than that of normal gastric tissue and was positively correlated with p-Akt, p-mTOR, VEGF-C and VEGF-D. Inhibition of p-Akt and p-mTOR, in vitro, decreased tumor cell VEGF-C and VEGF-D significantly. Therefore, we concluded that lymphangiogenesis of gastric cancer might be related to Akt/mTOR-VEGF-C/VEGF-D axis.

Cbl-b-regulated extracellular signal-regulated kinase signaling is involved in the shikonin-induced apoptosis of lung cancer cells in vitro

Shikonin (SK), a naturally occurring naphthoquinone, exhibits antitumor activity. However, its precise mechanisms of action are unknown. In the present study, the effects of SK on NCI-H460 human lung cancer cells were investigated. It was found that SK reduced cell viability and induced apoptosis in the NCI-H460 cells. Additionally, SK inhibited extracellular signal-regulated kinase (ERK) activity, which indicates that inhibition of the ERK pathway is probably one of the mechanisms by which SK induced NCI-H460 cell apoptosis. The expression of Cbl-b was significantly increased by treatment with SK for 4 h, and gradually increased to a maximal level at 24 h; the time taken for the upregulation of Cbl-b protein was in accordance to that required for the downregulation of phospho (p)-ERK protein. The Cbl inhibitor Ps341 reversed the SK-induced downregulation of p-ERK and apoptosis of NCI-H460 cells. These results indicate that Cbl-b potentiates the apoptotic action of SK by inhibiting the ERK pathway in lung cancer cells.

A GG allele of 3'-side AKT1 SNP is associated with decreased AKT1 activation and better prognosis of gastric cancer

PURPOSE

v-akt Murine thymoma viral oncogene homolog (AKT) pathway is critically involved in cancer cell growth, invasion, and survival. We examined the correlation between the genetic variations in molecules of AKT pathway and clinical outcomes of gastric cancer.

PATIENTS AND METHODS

Six single nucleotide polymorphisms (SNPs) located in the four core genes of AKT pathway, namely the PIK3CA, PTEN, AKT1, and mTOR, were determined in 221 patients with stage T2 and T3 gastric cancer. Additionally, the activation of AKT1 in gastric cancer tissues was examined by immunostaining. The correlation between SNPs, AKT activation, and the progress of gastric cancer was analyzed after an average of 51-month follow-up.

RESULTS

The overall recurrence and survival rate in this study group were 54.8 and 46.6 %, respectively. The recurrence rate was reduced 30.4 %, and the survival rate was increased 33.7 % in patients with GG allele of a 3'-side AKT1 SNP (rs2498804). Significantly, GG allele was associated with lower AKT1 activation in gastric cancer tissues. On the contrary, CC allele of PTEN (rs701848) was associated with the increased risk of recurrence (hazard ratio [HR] 2.06, 95 % CI 1.19-3.58) and patient death (HR 2.01, 95 % CI 1.15-3.53).

CONCLUSIONS

The genetic variants in the PI3K/PTEN/AKT especially the GG allele in 3' side of AKT1 are closely related to clinical outcomes of gastric cancer.

Alterations in the human epidermal growth factor receptor 2-phosphatidylinositol 3-kinase-v-Akt pathway in gastric cancer

AIM: To investigate human epidermal growth factor receptor 2 (HER2)-phosphatidylinositol 3-kinase (PI3K)-v-Akt murine thymoma viral oncogene homolog signaling pathway.

METHODS: We analyzed 231 formalin-fixed, paraffin-embedded gastric cancer tissue specimens from Japanese patients who had undergone surgical treatment. The patients’ age, sex, tumor location, depth of invasion, pathological type, lymph node metastasis, and pathological stage were determined by a review of the medical records. Expression of HER2 was analyzed by immunohistochemistry (IHC) using the HercepTest^TM kit. Standard criteria for HER2 positivity (0, 1+, 2+, and 3+) were used. Tumors that scored 3+ were considered HER2-positive. Expression of phospho Akt (pAkt) was also analyzed by IHC. Tumors were considered pAkt-positive when the percentage of positive tumor cells was 10% or more. PI3K, catalytic, alpha polypeptide (PIK3CA) mutations in exons 1, 9 and 20 were analyzed by pyrosequencing. Epstein-Barr virus (EBV) infection was analyzed by in situ hybridization targeting EBV-encoded small RNA (EBER) with an EBER-RNA probe. Microsatellite instability (MSI) was analyzed by polymerase chain reaction using the mononucleotide markers BAT25 and BAT26.

RESULTS: HER2 expression levels of 0, 1+, 2+ and 3+ were found in 167 (72%), 32 (14%), 12 (5%) and 20 (8.7%) samples, respectively. HER2 overexpression (IHC 3+) significantly correlated with intestinal histological type (15/20 vs 98 /205, P = 0.05). PIK3CA mutations were present in 20 cases (8.7%) and significantly correlated with MSI (10/20 vs 9/211, P < 0.01). The mutation frequency was high (21%) in T4 cancers and very low (6%) in T2 cancers. Mutations in exons 1, 9 and 20 were detected in 5 (2%), 9 (4%) and 7 (3%) cases, respectively. Two new types of PIK3CA mutation, R88Q and R108H, were found in exon1. All PIK3CA mutations were heterozygous missense single-base substitutions, the most common being H1047R (6/20, 30%) in exon20. Eighteen cancers (8%) were EBV-positive and this positivity significantly correlated with a diffuse histological type (13/18 vs 93/198, P = 0.04). There were 7 cases of lymphoepithelioma-like carcinomas (LELC) and 6 of those cases were EBV-positive (percent/EBV: 6/18, 33%; percent/all LELC: 6/7, 86%). pAkt expression was positive in 119 (53%) cases but showed no correlation with clinicopathological characteristics. pAkt expression was significantly correlated with HER2 overexpression (16/20 vs 103/211, P < 0.01) but not with PIK3CA mutations (12/20 vs 107/211, P = 0.37) or EBV infection (8/18 vs 103/211, P = 0.69). The frequency of pAkt expression was higher in cancers with exon20 mutations (100%) than in those with exon1 (40%) or exon9 (56%) mutations. One case showed both HER2 overexpression and EBV infection and 3 cases showed both PIK3CA mutations and EBV infection. However, no cases showed both PIK3CA mutations and HER2 overexpression. One EBV-positive cancer with PIK3CA mutation (H1047R) was MSI-positive. Three of these 4 cases were positive for pAkt expression. In survival analysis, pAkt expression significantly correlated with a poor prognosis (hazard ratio 1.75; 95%CI: 1.12-2.80, P = 0.02).

CONCLUSION: HER2 expression, PIK3CA mutations and EBV infection in gastric cancer were characterized. pAkt expression significantly correlates with HER2 expression and with a poor prognosis.

Clinicopathological correlations of mTOR and pAkt expression in non-small cell lung cancer

The Akt/mammalian target of rapamycin (mTOR) pathway is up-regulated in many human cancers, and agents targeting the mTOR pathway are in various stages of clinical development and application. Expression of pAkt and mTOR was studied by immunohistochemical analysis of 574 surgically resected non-small cell lung cancer (NSCLC) specimens on a tissue microarray. The results were correlated with clinicopathological features. Expression of mTOR showed a strong correlation with the expression of pAkt (p < 0.001) and was significantly associated with female gender, tumor size of ≤3 cm, adenocarcinoma (ADC), non-smoker status, and lower pathological stage. Expression of pAkt was correlated with older age (≥65), ADC, non-smoker status, and lower T stage. Univariate survival analysis revealed that the mTOR- and pAkt-positive group had a significantly longer cancer-specific survival than the mTOR- and pAkt-negative group (p = 0.038 and 0.024, respectively). Coexpression of pAkt and mTOR correlated with better prognosis than either single- or double-negative pAkt and mTOR groups (p = 0.016). However, multivariate analysis proved that mTOR and pAkt expression are not independent prognostic factors for cancer-specific survival. Expression of pAkt and mTOR expression is more significantly associated with ADC than squamous cell carcinoma. Although pAkt/mTOR expression is not an independent prognostic marker, expression of these proteins is associated with better prognosis.

Genetic Mechanisms and Aberrant Gene Expression during the Development of Gastric Intestinal Metaplasia and Adenocarcinoma

Gastric adenocarcinoma occurs via a sequence of molecular events known as the Correa’s Cascade which often progresses over many years. Gastritis, typically caused by infection with the bacterium H. pylori, is the first step of the cascade that results in gastric cancer; however, not all cases of gastritis progress along this carcinogenic route. Despite recent antibiotic intervention of H. pylori infections, gastric adenocarcinoma remains the second most common cause of cancer deaths worldwide. Intestinal metaplasia is the next step along the carcinogenic sequence after gastritis and is considered to be a precursor lesion for gastric cancer; however, not all patients with intestinal metaplasia develop adenocarcinoma and little is known about the molecular and genetic events that trigger the progression of intestinal metaplasia into adenocarcinoma. This review aims to highlight the progress to date in the genetic events involved in intestinal-type gastric adenocarcinoma and its precursor lesion, intestinal metaplasia. The use of technologies such as whole genome microarray analysis, immunohistochemical analysis and DNA methylation analysis has allowed an insight into some of the events which occur in intestinal metaplasia and may be involved in carcinogenesis. There is still much that is yet to be discovered surrounding the development of this lesion and how, in many cases, it develops into a state of malignancy.

Methyl jasmonate: a plant stress hormone as an anti-cancer drug

Jasmonates act as signal transduction intermediates when plants are subjected to environmental stresses such as UV radiation, osmotic shock and heat. In the past few years several groups have reported that jasmonates exhibit anti-cancer activity in vitro and in vivo and induce growth inhibition in cancer cells, while leaving the non-transformed cells intact. Recently, jasmonates were also discovered to have cytotoxic effects towards metastatic melanoma both in vitro and in vivo. Three mechanisms of action have been proposed to explain this anti-cancer activity. The bio-energetic mechanism - jasmonates induce severe ATP depletion in cancer cells via mitochondrial perturbation. Furthermore, methyl jasmonate (MJ) has the ability to detach hexokinase from the mitochondria. Second, jasmonates induce re-differentiation in human myeloid leukemia cells via mitogen-activated protein kinase (MAPK) activity and were found to act similar to the cytokinin isopentenyladenine (IPA). Third, jasmonates induce apoptosis in lung carcinoma cells via the generation of hydrogen peroxide, and pro-apoptotic proteins of the Bcl-2 family. Combination of MJ with the glycolysis inhibitor 2-deoxy-d-glucose (2DG) and with four conventional chemotherapeutic drugs resulted in super-additive cytotoxic effects on several types of cancer cells. Finally, jasmonates have the ability to induce death in spite of drug-resistance conferred by either p53 mutation or P-glycoprotein (P-gp) over-expression. In summary, the jasmonates are anti-cancer agents that exhibit selective cytotoxicity towards cancer cells, and thus present hope for the development of cancer therapeutics.

Anti-gastric cancer effects of celecoxib, a selective COX-2 inhibitor, through inhibition of Akt signaling

BACKGROUND AND AIM

Previously, we showed that treatment with celecoxib significantly reduced the number of viable gastric cancer cells, in a dose- and time-dependent manner. However, the specific anti-cancer effects of celecoxib on gastric cancer cells have not been clarified. The present in vitro study was carried out to investigate the mechanism involved in the anti-gastric cancer effects of celecoxib.

METHODS

3-(4,5-Dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was carried out after treating AGS cells (human gastric cancer cell line, ATCC CRL 1739) with celecoxib or indomethacin, and the effect of prostaglandin E(2) or LY294002 (PI3K inhibitor) was evaluated. Western blot analysis of tAkt (total Akt), pAkt (phosphorylated Akt), pGSK3beta (phosphorylated glycogen synthase kinase-3beta), pFKHR (phosphorylated forkhead transcriptional factor), and caspase-9 was carried out at various concentrations (0, 5, 10, 25, or 50 micromol/L) of celecoxib or indomethacin-treatment for 24 or 48 h in AGS cells.

RESULTS

Celecoxib- or LY294002-induced cell death was found to occur in a dose-dependent manner in AGS cells, and these decreases were slightly recovered by the addition of PGE(2) (25 or 50 micromol/L). The expression of pAkt but not tAkt was lower in the celecoxib treated-AGS cells and the response was dose dependent (P < 0.05). The expression of pGSK3beta and pFKHR was also significantly decreased in the celecoxib treated-AGS cells. Procaspase 9 (47 kDa) was frequently cleaved into 37, 35 and 17 kDa fragments in the celecoxib-treatment group. However, these changes in cell signal transduction were not observed in the indomethacin treated-AGS cells.

CONCLUSION

The anti-cancer effects of celecoxib on gastric cancer cells might be partly mediated by downregulation of Akt, GSK3beta, FKHR, and upregulation of caspase-9, in the mitochondrial apoptotic pathway.

Application of PI3K/Akt and COX-2 signal pathway blockage in treatment of gastric carcinoma

The abnormal alternation of phosphatidylinositol-3-kinase/Protein Kinase B (PI3K/PKB) and cyclooxygenase-2 (COX-2) signal pathways plays an important role in emergence and development of tumors, which also contributes to a series of biological processes and exerts a tremendous influence on treatment and prognosis of tumors. This review investigates PI3K/Akt and COX-2 signal pathways blockage and their mechanism, and provided a original direction for molecular target therapy of diverse tumors including gastric carcinoma.

Genetic variations in the PI3K/PTEN/AKT/mTOR pathway are associated with clinical outcomes in esophageal cancer patients treated with chemoradiotherapy

PURPOSE

The phosphoinositide-3-kinase (PI3K), phosphatase and tensin homolog (PTEN), v-akt murine thymoma viral oncogene homolog (AKT), and mammalian target of rapamycin (mTOR) signaling pathway has been implicated in resistance to several chemotherapeutic agents. In this retrospective study, we determined whether common genetic variations in this pathway are associated with clinical outcomes in esophageal cancer patients with adenocarcinoma or squamous cell carcinoma who have undergone chemoradiotherapy and surgery.

PATIENTS AND METHODS

Sixteen tagging single nucleotide polymorphisms (SNPs) in PIK3CA, PTEN, AKT1, AKT2, and FRAP1 (encoding mTOR) were genotyped in these patients and analyzed for associations with response to therapy, survival, and recurrence.

RESULTS

We observed an increased recurrence risk with genetic variations in AKT1 and AKT2 (hazard ratio [HR], 2.21; 95% CI, 1.06 to 4.60; and HR, 3.30; 95% CI, 1.64 to 6.66, respectively). This effect was magnified with an increasing number of AKT adverse genotypes. In contrast, a predictable protective effect by PTEN genetic variants on recurrence was evident. Survival tree analysis identified higher-order interactions that resulted in variation in recurrence-free survival from 12 to 42 months, depending on the combination of SNPs. Genetic variations in AKT1, AKT2, and FRAP1 were associated with survival. Patients homozygous for either of the FRAP1 SNPs assayed had a more than three-fold increased risk of death. Two genes--AKT2 and FRAP1--were associated with a poor treatment response, while a better response was associated with heterozygosity for AKT1:rs3803304 (odds ratio, 0.50; 95% CI, 0.25 to 0.99).

CONCLUSION

These results suggest that common genetic variations in this pathway modulate clinical outcomes in patients who undergo chemoradiotherapy. With further validation, these results may be used to build a model of individualized therapy for the selection of the optimal chemotherapeutic regimen.

Multiple roles and therapeutic implications of Akt signaling in cancer

The prominence of the PI3K-Akt signaling pathway in several tumors indicates a relationship with tumor grade and proliferation. Critical cellular processes are driven through this pathway. More detailed knowledge of the pathogenesis of tumors would enable us to design targeted drugs to block both membrane tyrosine kinase receptors and the intracellular kinases involved in the transmission of the signal. The newly approved molecular inhibitors sunitinib (an inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and other tyrosine kinase receptors), sorafenib (a serine-threonine kinase inhibitor that acts against B-Raf) and temsirolimus (an mTOR inhibitor) shown clinical activity in advanced kidney cancer. Chronic myeloid leukemia has changed its natural history thanks to imatinib and dasatinib, both of which inhibit the intracellular bcr/abl protein derived from the alteration in the Philadelphia chromosome. Intracellular pathways are still important in cancer development and their blockade directly affects outcome. Cross-talk has been observed but is not well understood. Vertical and horizontal pathway blockade are promising anticancer strategies. Indeed, preclinical and early clinical data suggest that combining superficial and intracellular blocking agents can synergize and leverage single-agent activity. The implication of the Akt signaling pathway in cancer is well established and has led to the development of new anticancer agents that block its activation.

Overexpression of phosphorylated mammalian target of rapamycin predicts lymph node metastasis and prognosis of chinese patients with gastric cancer

PURPOSE

We determined the expression of mammalian target of rapamycin (mTOR) and its activated form, p-mTOR, in Chinese patients with gastric cancer and its clinical effects and underlying mechanisms.

EXPERIMENTAL DESIGN

Tissue microarray blocks containing gastric cancer tissue and matched noncancer gastric tissue specimens obtained from 1,072 patients were constructed. Expression of total mTOR and p-mTOR in these specimens was analyzed using immunohistochemical studies and confirmed by Western blotting.

RESULTS

The overall rates of total mTOR and p-mTOR overexpression were 50.8% (545 of 1,072) and 46.5% (499 of 1,072), respectively. The p-mTOR overexpression was significantly correlated with total mTOR overexpression. Overexpression of total mTOR protein was significantly correlated with tumor differentiation, T1/T2 tumors, and stage I/II/III disease, whereas p-mTOR overexpression was significantly correlated with lymph node metastasis and all stage disease. The Cox proportional hazards model revealed that the overexpression of p-mTOR, but not total mTOR, was an independent prognostic factor for gastric cancer. The overexpression of p-mTOR also predicted the angiogenic phenotype of human gastric cancer and regulated angiogenesis of gastric cancer cells.

CONCLUSIONS

Increased activation of mTOR is frequent in human gastric cancer and overexpression of p-mTOR is an independent prognostic factor, suggesting that mTOR pathway could be a potential target for therapy of this malignancy.

Increased staining for phosphorylated AKT and nuclear factor-kappaB p65 and their relationship with prognosis in epithelial ovarian cancer

AKT plays an important role in malignant behavior of tumors. The purpose of the present study was to determine the expression of phosphorylated AKT (P-AKT) and nuclear factor-kappaB (NF-kappaB) p65 and their association with clinicopathological parameters and prognosis in epithelial ovarian tumor. On immunohistochemistry 115 samples of ovarian tissue that included 68 specimens of epithelial ovarian cancer, 12 of borderline tumor, 24 of epithelial benign tumor and 11 of normal ovary, were evaluated. Sixty-three patients with ovarian cancer were followed up from 7 to 68 months. The positive expression rate of P-AKT and NF-kappaB p65 were higher in epithelial ovarian cancer than in normal ovarian tissue (P<0.01). Elevated P-AKT or NF-kappaB p65 expression was significantly correlated with late clinical stage (P<0.05 and P<0.01) and poor histological differentiation (both P<0.01). P-AKT expression was significantly correlated with NF-kappaB p65 immunostaining (phi=0.272, P<0.05). Elevated expression of P-AKT was negatively correlated with the survival of ovarian cancer patients, but it was not an independent prognostic factor after multivariate analysis. Overexpression of P-AKT and NF-kappaB p65 were involved in the carcinogenesis and metastasis of ovarian cancer. P-AKT might contribute to the malignant transformation through NF-kappaBp65 upregulation.

PI3K/Akt pathway activation attenuates the cytotoxic effect of methyl jasmonate toward sarcoma cells

Methyl jasmonate (MJ) acts both in vitro and in vivo against various cancer cell lines. Activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway results in decreased susceptibility to cytotoxic agents in many types of cancer cells. We found a strong inverse correlation between the basal level of phospho-Akt (pAkt) and the sensitivity to MJ among sarcoma cell lines. Nevertheless, levels of pAkt increased in two sarcoma cell lines, MCA-105 and SaOS-2, after MJ treatment. Treatment of both cell lines with PI3K/Akt pathway inhibitors in combination with MJ resulted in a synergistic cytotoxic effect. Moreover, cells transfected with a constitutively active Akt were less susceptible to MJ-induced cytotoxicity in comparison with cells transfected with an inactive form of Akt. Taken together, these data suggest that the increase in pAkt after treatment with MJ played a protective role. Because it has been shown that the antiapoptotic effects of Akt are dependent on glycolysis, we examined the role of glucose metabolism in activation of Akt and the subsequent resistance of the cell lines to MJ. 2-Deoxy-d-glucose, a glycolysis inhibitor, decreased the levels of pAkt and was able to attenuate the MJ-induced elevation in pAkt. Accordingly, the presence of glucose attenuated MJ-induced cytotoxicity. Moreover, treatment with 2-deoxy-d-glucose in combination with MJ resulted in a synergistic cytotoxic effect. In conclusion, the PI3K/Akt pathway plays a critical role in the resistance of MCA-105 and SaOS-2 sarcoma cell lines toward MJ-induced cytotoxicity.

Activated Akt as an indicator of prognosis in gastric cancer

The immunohistochemical expression of phosphorylated (activated) Akt (pAkt) in 50 advanced gastric carcinomas has been analyzed and the results correlated with age, sex, location in the stomach, histotype, stage, survival, mitotic and apoptotic index, some cell cycle regulators (cyclin D1, cyclin E, p34/cdc2, p27/kip1), and cell proliferation. There was a statistically significant direct correlation between pAkt expression (both cytoplasmatic and nuclear) and depth of infiltration of the tumor, number of infiltrated lymph nodes and p34/cdc2 expression, and between prevalently nuclear pAkt and cyclin D1 and cyclin E. Conversely, there was a significant inverse correlation between nuclear pAkt and apoptotic index and between cytoplasmatic and nuclear pAkt and patient survival. No correlation was found between pAkt and sex, age, tumor location, histotype, mitotic index, and cell proliferation. These findings suggest that pAkt may be considered an indicator of tumor progression and patient survival in gastric cancer.

Helicobacter pylori activate epidermal growth factor receptor- and phosphatidylinositol 3-OH kinase-dependent Akt and glycogen synthase kinase 3beta phosphorylation

The signalling pathways leading to the development of Helicobacter pylori-induced gastric cancer remain poorly understood. We tested the hypothesis that H. pylori infections involve the activation of Akt signalling in human gastric epithelial cancer cells. Immunoblot, immunofluorescence and kinase assays show that H. pylori infection of gastric epithelial cells induced phosphorylation of Akt at Ser 473 and Thr 308. Mutations in the H. pylori virulence factor OipA dramatically reduced phosphorylation of Ser 473, while the cag pathogenicity island mutants predominantly inhibited phosphorylation of Thr 308. As the downstream of Akt activation, H. pylori infection inactivated the inactivation of glycogen synthase kinase 3beta at Ser 9 by its phosphorylation. As the upstream of Akt activation, H. pylori infection activated epidermal growth factor receptor (EGFR) at Tyr 992, phosphatidylinositol 3-OH kinase (PI3K) p85 subunit and PI3K-dependent kinase 1 at Ser 241. Pharmacologic inhibitors of PI3K or mitogen-activated protein kinase kinase (MEK), Akt knock-down and EGFR knock-down showed that H. pylori infection induced the activation of EGFR-->PI3K-->PI3K-dependent kinase 1-->Akt-->extracellular signal-regulated kinase signalling pathways, the inactivation of glycogen synthase kinase 3beta and interleukin-8 production. The combined functions of cag pathogenicity island and OipA were necessary and sufficient for full activation of signalling at each level. We propose activation of these pathways as a novel mechanism for H. pylori-mediated carcinogenesis.

Effect of Genistein on the expression of Akt and phosphorylated Akts in human gastric carcinoma cell line

AIM: To investigate the effects of Genestein on the expression of Akt and its phosphorylated proteins (p-Akts) in human gastric carcinoma cell line SGC-7901.

METHODS: SGC-7901 cells were exposed to 0、5、10、20、40 and 80 μmol/L Genistein for 24 h. The effect of Genistein on cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay, and the apoptosis of SGC-7901 cells was evaluated by Hoechst 33342 staining. The expression of Akt and p-Akts (Ser473 and Thr308) were measured by Western blot.

RESULTS: The inhibitory rate was 6.85% ± 3.71%, 13.19% ± 1.90%, 20.94% ± 1.83%, 29.58% ± 1.19% and 41.75% ± 1.92%, respectively, as SGC-7901 cells were exposed to 5, 10, 20, 40 and 80 μmol/L Genistein for 24 h. Typical morphological changes of apoptosis were induced by Genistein at the concentrations (20-80 μmol/L). Genistein had no marked influences on Akt expression. Both Ser473 and Thr308 were expressed in SGC-7901 cells 24 h after Genistein treatment, and they were decreased with the increasing of Genistein concentrations. The weakest expression appeared as 80 μmol/L Genistein was used.

CONCLUSION: The anti-cancer action of Genistein may be associated with the decreased expression of p-Akt (Ser473) and p-Akt (Thr308).