Insulin gene enhancer protein 1 mediates glycolysis and tumorigenesis of gastric cancer through regulating glucose transporter 4.

BACKGROUND: Insulin gene enhancer protein 1, (ISL1), a LIM-homeodomain transcription factor, is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes. However, the role of ISL1 in stimulating glycolysis to promote tumorigenesis in gastric cancer (GC) is unclear. In this study, we aimed to characterize the expression pattern of ISL1 in GC patients and explore its molecular biological mechanism in glycolysis and tumorigenesis. METHODS: We analyzed the expression and clinical significance of ISL1 in GC using immunohistochemistry and real-time polymerase chain reaction (PCR). Flow cytometry and IncuCyte assays were used to measure cell proliferation after ISL1 knockdown. RNA-sequencing was performed to identify differentially expressed genes, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Set Enrichment Analysis (GSEA) to reveal key signaling pathways likely regulated by ISL1 in GC. Alteration of the glycolytic ability of GC cells with ISL1 knockdown was validated by measuring the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) and by detecting glucose consumption and lactate production. The expression of glucose transporter 4 (GLUT4) and ISL1 was assessed by Western blotting, immunohistochemistry, and immunofluorescent microscopy. The luciferase reporter activity and chromatin immunoprecipitation assays were performed to determine the transcriptional regulation of ISL1 on GLUT4. RESULTS: High levels of ISL1 and GLUT4 expression was associated with short survival of GC patients. ISL1 knockdown inhibited cell proliferation both in vitro and in vivo. KEGG analysis and GSEA for RNA-sequencing data indicated impairment of the glycolysis pathway in GC cells with ISL1 knockdown, which was validated by reduced glucose uptake and lactate production, decreased ECAR, and increased OCR. Mechanistic investigation indicated that ISL1 transcriptionally regulated GLUT4 through binding to its promoter. CONCLUSION: ISL1 facilitates glycolysis and tumorigenesis in GC via the transcriptional regulation of GLUT4.

Immobilization of FLAG-Tagged Recombinant Adeno-Associated Virus 2 onto Tissue Engineering Scaffolds for the Improvement of Transgene Delivery in Cell Transplants.

The technology of virus-based genetic modification in tissue engineering has provided the opportunity to produce more flexible and versatile biomaterials for transplantation. Localizing the transgene expression with increased efficiency is critical for tissue engineering as well as a challenge for virus-based gene delivery. In this study, we tagged the VP2 protein of type 2 adeno-associated virus (AAV) with a 3×FLAG plasmid at the N-terminus and packaged a FLAG-tagged recombinant AAV2 chimeric mutant. The mutant AAVs were immobilized onto the tissue engineering scaffolds with crosslinked anti-FLAG antibodies by N-succinimidyl-3-(2-pyridyldithiol) propionate (SPDP). Cultured cells were seeded to scaffolds to form 3D transplants, and then tested for viral transduction both in vitro and in vivo. The results showed that our FLAG-tagged AAV2 exerted similar transduction efficiency compared with the wild type AAV2 when infected cultured cells. Following immobilization onto the scaffolds of PLGA or gelatin sponge with anti-FLAG antibodies, the viral mediated transgene expression was significantly improved and more localized. Our data demonstrated that the mutation of AAV capsid targeted for antibody-based immobilization could be a practical approach for more efficient and precise transgene delivery. It was also suggested that the immobilization of AAV might have attractive potentials in applications of tissue engineering involving the targeted gene manipulation in 3D tissue cultures.

Probing the hepatic progenitor cell in human hepatocellular carcinoma.

Objective. The intrahepatic stem cells, also known as hepatic progenitor cells (HPCs), are able to differentiate into hepatocytes and bile duct epithelia. By exposure of different injuries and different hepatocarcinogenic regimens, the mature hepatocytes can no longer effectively regenerate; stem cells are involved in the pathogenesis of hepatocellular carcinoma. Methods. Immunohistochemistry was performed on 107 paraffin-embedded hepatocellular carcinoma specimens with the marker of hepatocyte and hepatocellular carcinoma (HepPar1), biliary differentiation (CK7,CK19), haemopoietic stem cell (HSC) (c-kit/CD117, CD34, and Thy-1/CD90), HPC specific markers (OV-6), and Ki-67, p53 protein. Results. HPCs can be identified in the tumor nodules, around the edge of tumor nodules, and in the portal tracts of the paracirrhosis nodules being positive in HepPar1, CK7, CK19, and OV-6, but they failed to immunostain with CD117, CD34, and CD90. The HPCs positive in Ki-67 are observed in the tumor and paracirrhosis tissues. In 107 specimens, 40.2% (43/107) HCC tissues expressed p53 protein, lower than that of the HPCs around the tumor nodules (46.7%, 50/107) and much higher than that of the HPCs around the paracirrhosis nodules (8.41%, 9/107). Conclusion. Human hepatocellular carcinogenesis may be based on transformation of HPCs, not HSCs, through the formation of the transitional cells (hepatocyte-like cells and bile ductal cells).

[Photosynthetic functions and chlorophyll fast fluorescence characteristics of five Pinus species].

A comparative study was made on the needle morphological characteristics, photosynthetic rate, and chlorophyll fast fluorescence induction curves of five representative Pinus species P. parvifiora, P. armandii, P. bungeana, P. tabuliformis, and P. densiflora. Significant differences were observed in the needle morphological characteristics among the five species. P. tabuliformis had the longest needle length and highest needle density, whereas P. bungeana had the highest chlorophyll content. P. densiflora and P. parvifiora had the maximum and minimum photosynthetic rate, respectively. There was a positive correlation between the photosynthetic rate and stomatal conductance across the five species. The differences in the chlorophyll fast fluorescence induction curves of the five species were mainly manifested in J-step and I-step. Although the five species had similar values of Fv/Fm, Fv/Fo and Tfm, P. parviflora had significantly higher values of dV/dt(o), dVG/d(o), V and Vi, but lower energy flux ratio psi(o), phiEo and phiRo, compared with the other four species. The low PSII activity and efficiency of P. parviflora might relate to its smallest Sm, Sm/Tfm and N. P. densiflora and P. parvifiora had the maximum and minimum vitality indices PI(ABS/CSo/CSm) and DF, respectively, and there existed significant positive correlations between the PI(CSo) and PI(CSm) and the net photosynthetic rate of the five species, suggesting that PI(CSo) and PI(CSm) could be used to estimate the photosynthetic activity of Pinus trees.

Phospholipase A2 group IIA expression correlates with prolonged survival in gastric cancer.

AIMS: The secreted phospholipase A2 type IIA (PLA2G2A) gene has been identified as a modifier of intestinal adenoma multiplicity in Apc(Min/+) mice. The aim of the present study was to analyse the clinical significance of PLA2G2A expression in human gastric cancer. METHODS AND RESULTS: Using immunohistochemistry, cytoplasmic immunoreactivity of PLA2G2A was observed in 27% (40 of 149) of gastric cancer tissues compared with negative staining in normal mucosa. The PLA2G2A expression rate in well-differentiated carcinoma was elevated significantly compared with that in poorly differentiated carcinoma (46% versus 19%, P = 0.001). Statistical analysis also revealed that PLA2G2A expression correlated negatively with depth of mural invasion, lymph node metastasis and tumour-node-metastasis (TNM) stage (P < 0.05). Patients with positive PLA2G2A expression showed higher 5-year overall survival than those with negative expression (P = 0.0004). In intestinal metaplasia, PLA2G2A was found to be abundant in Paneth cells. The coexistence of PLA2G2A and lysozyme was observed in Paneth cell-rich gastric cancer (P < 0.0001). CONCLUSIONS: PLA2G2A may predict survival and might be a potential biomarker for early detection and individualized therapy.

Discovery and validation of prognostic markers in gastric cancer by genome-wide expression profiling.

AIM: To develop a prognostic gene set that can predict patient overall survival status based on the whole genome expression analysis. METHODS: Using Illumina HumanWG-6 BeadChip followed by semi-supervised analysis, we analyzed the expression of 47,296 transcripts in two batches of gastric cancer patients who underwent surgical resection. Thirty-nine samples in the first batch were used as the training set to discover candidate markers correlated to overall survival, and thirty-three samples in the second batch were used for validation. RESULTS: A panel of ten genes were identified as prognostic marker in the first batch samples and classified patients into a low- and a high-risk group with significantly different survival times (P = 0.000047). This prognostic marker was then verified in an independent validation sample batch (P = 0.0009). By comparing with the traditional Tumor-node-metastasis (TNM) staging system, this ten-gene prognostic marker showed consistent prognosis results. It was the only independent prognostic value by multivariate Cox regression analysis (P = 0.007). Interestingly, six of these ten genes are ribosomal proteins, suggesting a possible association between the deregulation of ribosome related gene expression and the poor prognosis. CONCLUSION: A ten-gene marker correlated with overall prognosis, including 6 ribosomal proteins, was identified and verified, which may complement the predictive value of TNM staging system.

Identification of prognosis-related proteins in advanced gastric cancer by mass spectrometry-based comparative proteomics.

PURPOSE: The objective of this study was to identify differentially expressed proteins of advanced gastric cancer from patients with different prognosis using NanoLC-MS/MS (LTQ) (nanoflow liquid chromatography system interfaced with a linear ion trap LTQ mass spectrometer). METHODS: Eight gastric cancer patients with relatively early TNM stage and survival time >34 months were identified as good survival (group G), while the other eight with late stage and survival time <15 months as poor survival (group P). The total protein of the tissue samples from each group was extracted and pooled together respectively. The resulting two protein mixtures were trypsin-digested and analyzed using NanoLC-MS/MS (LTQ). Database searches were done against NCBI non-redundant database and SWISS-PROT database and the identified proteins were classified through an online Web Gene Ontology Annotation Plot tool. Immunohistochemistry was used to verify candidate prognosis-related proteins. RESULTS: There were 284 and 213 proteins identified for group G and group P respectively. And 117 proteins were detected exclusively in group G and 46 proteins exclusively in group P. These protein markers function in calcium ion signaling pathway, cellular metabolism, cytoskeleton formation, stress reaction, etc. Among those, the down-regulated expression of S100P was verified to claim a poor clinical outcome of gastric cancer patients (P = 0.0375). CONCLUSION: The MS-based proteomics approach is efficient in identifying differentially expressed proteins in relation to prognosis of advanced gastric cancer patients. These differentially expressed proteins could be potential prognosis-related cancer markers and deserve further validation and functional study.

[Nuclear expression of S100A4 is associated with lymph node metastasis in gastric carcinoma].

OBJECTIVE: To investigate the intracellular localization of S100A4 in gastric carcinoma cells and the relationship between S100A4 expression status and lymph node metastasis of gastric carcinoma. METHODS: Western blotting analysis was performed to locate the expression of S100A4 protein in sub-fraction components of frozen tissues. S100A4 protein expression was also determined by immunohistochemical method in 131 samples of gastric cancer and 20 samples of matched metastatic lymph nodes. RESULTS: Thirty-two of 131 (24.4%) gastric carcinoma showed positive S100A4 nuclear expression and 50/131 (38.2%) carcinoma showed positive cytoplasmic expression. In 32 samples with positive S100A4 nuclear expression, 30 (93.8%) carcinomas had positive lymph node metastases. S100A4 nuclear expression level was higher in gastric carcinoma with lymph node metastasis (29.1%) than that without lymph node metastasis (7.1%) (P=0.016). CONCLUSION: Nuclear expression of S100A4 is associated with lymph node metastasis of gastric carcinoma.