Phosphoglycerate Kinase 1 Expression Research Articles

Responsiveness of ARNT‐deficient mouse hepatoma (BPRc1) cells transfected with HIF‐1beta to oxidative stress and antioxidants

Our previous study showed that phosphoglycerate kinase 1 (PGK1) may be a potential biomarker for oxidative stress. However, the expression of hypoxia inducible factors (HIFs) known as a major upstream regulator of glycolytic enzymes including PGK1 was little affected by hydrogen peroxide but significantly downregulated by antioxidants. Furthermore, PGK1 level in BPRc1 cells lacking HIF‐1beta remained unchanged regardless of treatment of either hydrogen peroxide or delphinidin, suggesting the importance of heterodimer formation between HIF‐1alpha and HIF‐1beta in the regulation of PGK1 expression. PGK1, therefore, appears to be a reliable protein biomarker for oxidative stress or antioxidant potential, and its expression seems to be mediated by the intracelluar level of HIF‐1alpha. To confirm the role of HIF‐1beta in cellular response to oxidative stress and antioxidant, we constructed HIF‐1beta cDNA cloning vector and expression vector using pcDNA3.1/myc‐His construction. The full‐length cDNA of mHIF‐1beta was cloned from mouse HIF‐1beta by RT‐PCR using primers corresponding to the sequence BC012870. The transfectants generated by transfecting BPRc1 with HIF‐1beta will be used to evaluate whether BPRc1 cells insensitive to oxidative stress and antioxidants restore their responsiveness to intracellular redox status by introduction of HIF‐1beta gene or not.

Phosphoglycerate kinase 1‐overexpressing lung cancer cells reduce cyclooxygenase 2 expression and promote anti‐tumor immunity in vivo

In addition to the known function in the glycolytic pathway, phosphoglycerate kinase 1 (PGK-1) promotes reduction of plasmin disulfide bonds leading to angiostatin formation and inhibition of tumor angiogenesis. In this study, the effects of PGK-1 on anti- tumor immunity against lung cancer were evaluated using the Tet-Off control of PGK-1 expression in the Lewis lung carcinoma (LLC-1). There was no significant difference in cell proliferation between parental LLC-1 and LLC-1 transduced with PGK-1 (PGK-LLC-1). However, expression of PGK-1 was found to limit tumor growth in mice subcutaneously injected with the cell lines and tumor growth was restored after doxycycline treatment. In addition, the cell invasion ability of PGK-LLC-1 became weaker than that of LLC-1. Expressions of COX-2, TGF-beta1 and PGE2 were all found to be down-regulated in PGK-LLC-1. PGK-LLC-1 cells treated with doxycycline recovered their COX-2 protein expression. In the presence of conditioned medium from PGK-LLC-1, the endothelial cell migration was reduced. Moreover, PGK-LLC-1 also stimulated T lymphocytes to express higher levels of Th1 cytokine (IFN-gamma) and lower levels of IL-10 in comparison with parental LLC-1. PGK-LLC-1 cells restored the growth rate in immunodeficient mice when compared with the growth rate in normal mice. In the tissue sections, reduced COX-2 expressions and marked infiltrated CD3 T lymphocytes were observed in the PGK-LLC-1 injected group. These findings indicate that overexpression of PGK-1 in LLC-1 reduces the COX-2 expression, and, in turn, affect PGE2, cell invasion, angiogenesis, and the immune functions, and finally inhibit the tumor progression.

PGK1 a prospect marker for peritoneal dissemination in gastric cancer

22171 Background: In patients with primary gastric cancer peritoneal carcinomatosis is a frequent finding, and it is related with a moderate prognosis. The dissemination of cancer cells into the abdominal cavity in diffuse gastric adenocarcinoma seems to be a major mechanism for peritoneal carcinomatosis. The features that enable diffuse primary gastric tumours to develop peritoneal dissemination have been little investigated and are still incompletely understood. Methods: Therefore the gene expression profile in patients with diffuse primary gastric cancer with and without peritoneal carcinomatosis was compared. Using oligonucleotide microarrays, human specimens from consecutive gastric cancer patients with and without peritoneal carcinomatosis were investigated. Differentially expressed and selected genes of interest were additionally evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). Results: A significant overexpression of phosphoglycerate kinase 1 (PGK1), the chemokine CXCR4 and its ligand CXCL12 was detected in specimens from diffuse gastric cancer patients with peritoneal carcinomatosis. Increased expression of PGK1 is associated with an enhancement in the metastatic rate due to effects on CXCR4 and CXCL12 expression, which play an important role in the metastatic homing of malignant cells. Conclusion: The overexpression of PGK1 and its signalling targets CXCR4 and CXCL12 in peritoneal disseminated diffuse primary gastric carcinomas strongly indicate that this pathway may promote peritoneal dissemination. These genes may pose as prognostic markers and/or be potential therapeutic targets to prevent the migration of gastric carcinoma cells into the peritoneum. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Fortuene Funding of the University of Tuebingen

Regulation of HIFs and PGK1 by Oxidative Stress and Antioxidants in Human Colon Cancer Cells

Our previous study attempted to identify proteins differentially expressed in human colon tumor cells treated with hydrogen peroxide as prooxidant, delphinidin as antioxidant, and both. Phosphoglycerate kinase 1 (PGK1) was the protein only upregulated selectively by hydrogen peroxide and its ROS‐induced induction is efficiently suppressed by delphinidin, one of antioxidants. In this study we attempted to confirm the previous observations using various antioxidants including alpha‐tocopherol, trolox, BHT in both p53‐positive (HCT116) and ‐negative (HT29) colon cancer cells. Treatment with hydrogen peroxide induced PGK1 in both HT29 and HCT116 cells in a dose‐dependent manner. Antioxidants (alpha‐tocopherol, trolox, BHT, delphinidin) consistently decreased the expression of PGK1 and suppressed the increase of PGK1 expression induced by hydrogen peroxide. However, the expression of hypoxia‐inducible factors (HIFs) known as a major upstream regulator of glycolytic enzymes including PGK1 were not affected by hydrogen peroxide but downregulated by antioxidants. The data suggest that intracellular level of PGK1 might be a biomarker for oxidative status and partly regulated by the levels of HIFs.

A Glycolytic Mechanism Regulating an Angiogenic Switch in Prostate Cancer

The generation of an "angiogenic switch" is essential for tumor growth, yet its regulation is poorly understood. In this investigation, we explored the linkage between metastasis and angiogenesis through CXCL12/CXCR4 signaling. We found that CXCR4 regulates the expression and secretion of the glycolytic enzyme phosphoglycerate kinase 1 (PGK1). Overexpression of PGK1 reduced the secretion of vascular endothelial growth factor and interleukin-8 and increased the generation of angiostatin. At metastatic sites, however, high levels of CXCL12 signaling through CXCR4 reduced PGK1 expression, releasing the angiogenic response for metastastic growth. These data suggest that PGK1 is a critical downstream target of the chemokine axis and an important regulator of an "angiogenic switch" that is essential for tumor and metastatic growth.

Proteomic Study Reveals That Proteins Involved in Metabolic and Detoxification Pathways Are Highly Expressed in HER-2/neu-positive Breast Cancer

The receptor tyrosine kinase ErbB2 (HER-2/neu) is overexpressed in up to 30% of breast cancers and is associated with poor prognosis and an increased likelihood of metastasis especially in node-positive tumors. In this proteomic study, to identify the proteins that are associated with the aggressive phenotype of HER-2/neu-positive breast cancer, tumor cells from both HER-2/neu-positive and -negative tumors were procured by laser capture microdissection. Differentially expressed proteins in the two subsets of tumors were identified by two-dimensional electrophoresis and MALDI-TOF/TOF MS/MS. We found differential expression of several key cell cycle modulators, which were linked with increased proliferation of the HER-2/neu-overexpressing cells. Nine proteins involved in glycolysis (triose-phosphate isomerase (TPI), phosphoglycerate kinase 1 (PGK1), and enolase 1 (ENO1)), lipid synthesis (fatty acid synthase (FASN)), stress-mediated chaperonage (heat shock protein 27 (Hsp27)), and antioxidant and detoxification pathways (haptoglobin, aldo-keto reductase (AKR), glyoxalase I (GLO), and prolyl-4-hydrolase beta-isoform (P4HB)) were found to be up-regulated in HER-2/neu-positive breast tumors. HER-2/neu-dependent differential expression of PGK1, FASN, Hsp27, and GLO was further validated in four breast cancer cell lines and 12 breast tumors by immunoblotting and confirmed by partially switching off the HER-2/neu signaling in the high HER-2/neu-expressing SKBr3 cell line with Herceptin treatment. Statistical correlations of these protein expressions with HER-2/neu status were further verified by immunohistochemistry on a tissue microarray comprising 97 breast tumors. Our findings suggest that HER-2/neu signaling may result, directly or indirectly, in enhanced activation of various metabolic, stress-responsive, antioxidative, and detoxification processes within the breast tumor microenvironment. We hypothesize that these identified changes in the cellular proteome are likely to drive cell proliferation and tissue invasion and that the key cell cycle modulators involved, when uncovered by future research, would serve as naturally useful targets for the development of therapeutic strategies to negate the metastatic potential of HER-2/neu-positive breast tumors.