Defective expression of RFT2 is associated with the development of GC and this may represent a mechanism underlying the decreased plasma riboflavin levels in GC.

The possibility that gamma-hydroxybutyrate (GHB), a metabolite of gamma-aminobutyric acid (GABA), may play a role in the CNS has recently come to attention. We describe here a sensitive and specific mass fragmentographic technique that allows the measurement of picomole amounts of GHB in single rat brain areas. Moreover, we show that GHB can accumulate postmortem, an effect that is blocked by the use of microwave irradiation to kill the animals. To understand further the relationship between GABA and GHB formation, we treated rats with drugs known to interfere with GABA metabolism at different levels and concomitantly measured GABA and GHB in cerebral cortex and cerebellum. Isoniazide, which blocks the formation of GABA, also decreases GHB. Blockers of the catabolism of GABA, such as aminooxyacetic acid and gamma-acetylenic GABA, increase GABA levels and decrease those of GHB. Sodium dipropylacetate increases both GABA and GHB, supporting the hypothesis that this effective antiepileptic drug also blocks in vivo the enzyme that converts succinic semialdehyde to succinic acid.

Dipeptidyl peptidase III (DPP3), a zinc-dependent metallopeptidase, is upregulated in a variety of malignancies. However, little is known about its roles in the pathogenesis of these malignancies. The present study was designed to investigate the roles of DPP3 in the pathogenesis and progression of oesophageal cancer (EC). The expression level of DPP3 in EC tissues and adjacent normal tissues was detected in 93 cases of tissue biopsies collected from patients diagnosed with oesophageal carcinoma by immunohistochemistry. The effect of DPP3 expression on cell proliferation, migration or apoptosis was determined in DPP3-depleted EC cells created by infection with lentivirus containing short hairpin RNA specific to the human DPP3 mRNA sequence, followed by detection at the cellular level using a Celigo cell count assay, flow cytometry, wound-healing assay and Transwell assay as well as chip screening with a Human Apoptosis Antibody Array kit, which enables the quantitative detection of 43 apoptosis-related genes. A xenograft model was applied to detect the tumour growth and invasion of DPP3-depleted cancer cells in nude mice. The results revealed that DPP3 expression was elevated in EC tissues compared with adjacent non-tumour tissues, and high DPP3 expression was significantly associated with poor prognosis. DPP3 depletion resulted in reduced cell proliferation and migration and enhanced cell cycle arrest and apoptosis of EC cells and led to the inhibition of tumour growth and invasion in a xenograft model. In addition, DPP3 depletion was associated with the upregulation of the proapoptotic proteins SMAC and p53 and the downregulation of the antiapoptotic proteins clAP-2, IGFBP-2 and TRAILR-4. Finally, DPP3 may promote cell proliferation, migration and survival of EC cells in vitro and tumour growth and invasion of oesophageal carcinoma in vivo, and thus may serve as a molecular target for tumour therapy.

No abstract

Background: Dipeptidyl peptidase III (DPP3) is a zinc-dependent metallopeptidase and elevated in a variety of malignant tumors, but the underlying mechanism is not well understood so far. Here we investigated the association of esophageal carcinogenesis with the regulation of DPP3 expression by tissue-based quantitative analysis and the depletion of DPP3 expression in esophageal cancer cells and xenograft model. Methods: The expression level of DPP3 in esophageal cancer tissues and adjacent normal tissues was detected in 93 cases of tissue biopsies collected from patients diagnosed with esophageal carcinoma by immunohistochemistry. The effect of DPP3 expression on cell proliferation, migration or apoptosis was determined in DPP3-depleted esophageal cancer cells created by infection with the lentivirus containing the shRNA specific to human DPP3 mRNA sequence followed by cytometric detection using celigo cell count assay, flow cytometry, wound-healing assay and trans-well assay as well as chip screening with a Human Apoptosis Antibody Array kit, which enables the quantitative detection of 43 apoptosis-related genes. A xenograft model was applied to the detection of tumor growth and invasion of DPP3-depleted cancer cells in nude mice.Results: DPP3 expression was elevated in esophageal cancer tissues compared with adjacent non-tumor tissues (normal controls) with statistical significance (P<0.05), and associated with poor prognosis of esophageal carcinoma. The DPP3-depletion resulted in a reduced cell proliferation and migration and enhanced cell-cycle arrest and apoptosis of esophageal cancer cells, and lead to the inhibition of tumor growth and invasion in xenograft model. In addition, DPP3-depletion was associated with the upregulation of pro-apoptotic proteins and the downregulation of anti-apoptotic proteins.Conclusions: These findings suggest that DPP3 may promote cell proliferation, migration and survival of esophageal cancer cells in vitro, and tumor growth and invasion of esophageal carcinoma in vivo and this might serve as a molecular target for tumor therapy.