Phosphoglycerate mutase 1 that is essential for glycolysis may act as a novel metabolic target for predicating poor prognosis for patients with gastric cancer.

BACKGROUND: To identify a novel marker for gastric cancer, we examined the usefulness of phosphoglycerate mutase 1 (PGAM1) as a potential diagnostic marker using isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics and evaluated its clinical significance. METHODS: Proteins from a discovery group of four paired gastric cancer tissues and adjacent gastric tissues were labeled with iTRAQ reagents and then identified and quantified using LC-MS/MS. The expression of PGAM1 was further validated in 139 gastric cancer patients using immunohistochemistry. Furthermore, the correlation of PGAM1 expression with clinical parameters was analyzed. Gene set enrichment analysis (GSEA) was performed to identify gene sets that were activated in PGAM1-overexpressing patients with gastric cancer. RESULTS: PGAM1 was significantly overexpressed in most cancers but particularly so in gastric cancer, with a sensitivity of 82.01% (95% confidence interval [CI]: 75.5%-88.5%) and specificity of 79.13% (95% CI: 72.3%-86%). Its expression was significantly associated with histological grade II and III tumors (p = 0.033), lymph node metastasis (p = 0.031), and TNM III-IV staging (p = 0.025). The area under the receiver operating characteristic (ROC) curve for the detection of PGAM1 overexpression in gastric cancer was 0.718 (p < 0.01). Furthermore, GSEA revealed that several important pathways such as glycolysis pathway and immune pathways were significantly enriched in patients with gastric cancer with PGAM1 overexpression. CONCLUSIONS: This study provided a sensitive method for detecting PGAM1, which may serve as a novel indicator for poor prognosis of gastric cancer, as well as a potent drug target for gastric cancer.

Identification and validation of PGLS as a metabolic target for early screening and prognostic monitoring of gastric cancer.

BACKGROUND: Gastric cancer is the third leading cause of cancer-related death in the world. The purpose of the present study is to investigate the expression and prognostic significance of 6-phosphogluconolactonase (PGLS) in gastric cancer. METHODS: The protein extracted from a panel of four pairs of gastric cancer tissues and adjacent tissues, labeled with iTRAQ (8-plex) reagents, and followed by LC-ESI-MS/MS. The expressions of proteins were further validated by immunohistochemistry analysis. The expression levels of mRNA were analyzed and validated in the Oncomine database. The correlations of PGLS with prognostic outcomes were evaluated with Kaplan-Meier plotter database. RESULTS: The present study found that PGLS was significantly up-regulated in gastric cancer by using iTRAQ-based proteomics and immunohistochemistry analysis. The sensitivity of PGLS in gastric cancer was 72.9%. The high expression of PGLS was significantly correlated with TNM staging in gastric cancer (p = 0.02). The overexpression of PGLS predicts worse overall survival (OS) and post-progression survival (PPS) for gastric cancer (OS, HR = 1.48, p = 2.1e-05; PPS, HR = 1.35, p = 0.015). Specifically, the high PGLS expression predicts poor OS, PPS in male gastric cancer patients, in patients with lymph node metastasis and in patients with Her-2 (-). CONCLUSIONS: These findings suggested that PGLS was aberrantly expressed in gastric cancer and predicts poor overall survival, post-progression survival for gastric cancer patients. The present study collectively supported that PGLS is an important target for early determining and follow-up monitoring for gastric cancer.

The effect of genistein on the content and activity of α- and ß-secretase and protein kinase C in Aß-injured hippocampal neurons.

Genistein (Gen), a derivative of soy isoflavone aglycone, has been shown to exert significant protective effect on Aß-induced neurotoxicity and neuroinjury. However, its underlying mechanism remains elusive. The objective was to investigate the inhibitory effect of Gen on Aß-induced neurotoxicity and to elucidate the underlying mechanism. Primary rat hippocampal neurons were pre-treated with Gen for 2 hr followed by incubation with Aß 25-35 for an additional 24 hr. The cell viability was assessed by MTT assay. The content and activity of α-, ß-secretase and protein kinase C (PKC) were measured, and the antagonistic effect of PKC inhibitor Myr was also analysed to clarify the molecular mechanism of Gen inhibition of Aß-induced toxicity to hippocampal neurons. The results showed that pre-treatment with Gen significantly increased the cell viability and presented the best effect at the final concentration of 0.375 µg/mL. Gen increases the activity of α-secretase but down-regulates the ß-secretase activity. It also enhances the expression and activity of PKC. Myr, a PKC inhibitor, partially blocks the activation effect of Gen. Gen exerts protective effect on Aß-induced neurotoxicity via activating the PKC signalling pathway, which further regulates the activities of α- and ß-secretase and thereby inhibits the formation and toxicity of Aß.

Genistein inhibits Aß25₋35 -induced neurotoxicity in PC12 cells via PKC signaling pathway.

Protein kinase C (PKC) signaling pathway is recognized as an important molecular mechanism of Alzheimer's disease (AD) in the regulation of neuronal plasticity and survival. Genistein, the most active molecule of soy isoflavones, exerts neuroprotective roles in AD. However, the detailed mechanism has not been fully understood yet. The present study aimed to investigate whether the neuroprotective effects of genistein against amyloid ß (Aß)-induced toxicity in cultured rat pheochromocytoma (PC12) cells is involved in PKC signaling pathway. PC12 cells were pretreated with genistein for 2 h following incubation with Aß(25-35) for additional 24 h. Cell viability was assessed by MTT. Hoechst33342/PI staining was applied to determine the apoptotic cells. PKC activity, intracellular calcium level and caspase-3 activity were analyzed by assay kits. The results showed that pretreatment with genistein significantly increased cell viability and PKC activity, decreased the levels of intracellular calcium, attenuated Hoechst/PI staining and blocked caspase-3 activity in Aß(25-35)-treated PC12 cells. Pretreatment of Myr, a general PKC inhibitor, significantly attenuated the neuroprotective effect of genistein against Aß(25-35)-treated PC12 cells. The present study indicates that PKC signaling pathway is involved in the neuroprotective action of genistein against Aß(25-35)-induced toxicity in PC12 cells.