Effect of prostaglandin reductase 1 (PTGR1) on gastric carcinoma using lentivirus-mediated system

Gastric carcinoma is a digestive related malignant tumor with poor diagnosis and prognosis for advanced patients. PTGR1 (prostaglandin reductase 1), as a potential cancer biomarker, has not been reported in gastric carcinoma occurrence. To investigate the role of PTGR1 on gastric carcinoma cells, human PTGR1 was efficiently silenced by lentivirus-mediated system in MGC-803 cells confirmed by quantitative real-time PCR (qRT-PCR) and western blot. Then cell proliferation, colony formation and cell cycle were determined after knockdown of PTGR1 by MTT assay, colony assay and flow cytometry, respectively and data suggested that PTGR1 down regulated MGC-803 cells significantly suppressed the proliferation and colony formation ability and induced cell cycle arrest in the G0/G1 phase compared to controls (P < 0.001). Further investigation demonstrated knockdown of PTGR1 influenced cell proliferation and cell cycle via activating p21 and p53 signaling pathway described by Western blot assay. Our findings indicate that PTGR1 may be an oncogene in human gastric carcinoma and identified as a diagnosis and prognosis target for gastric carcinoma.

Intestinal smooth muscle dysfunction develops postnatally in cystic fibrosis mice

OBJECTIVES

Intestinal dysmotility is one of the effects of cystic fibrosis (CF), but when and how this develops is not well understood. The goal of the present study was to use the Cftr knockout mouse to determine when in development circular smooth muscle of the small intestine becomes dysfunctional.

METHODS

Wild-type (WT) and CF mice were used at postnatal day 5 (P5) through adult. Pieces of small intestine were used to measure contractile activity of the circular muscle. Bacterial overgrowth was measured by quantitative polymerase chain reaction (PCR) of the bacterial 16S gene. Intestinal gene expression was determined by quantitative reverse transcription polymerase chain reaction (RT-PCR). Prostaglandin E2 (PGE2) and its metabolites were measured by enzyme immunoassay.

RESULTS

CF circular muscle response to cholinergic stimulation was similar to WT at P5, became somewhat impaired at P7, and was severely impaired by P14. In the CF intestine, bacterial overgrowth occurred by P4 and was maintained into adulthood. Eicosanoid metabolic gene expression in the CF intestine did not differ from WT shortly after birth. The phospholipase A2 genes, Pla2g4c and Pla2g5 exhibited increased expression in CF mice at P24. Prostaglandin degradative genes, Hpgd and Ptgr1, showed lower expression in CF as compared with WT at P16 and P24, respectively. PGE2 levels were significantly greater in CF mice at most ages from P7 through adulthood.

CONCLUSIONS

The results clearly demonstrate that lack of CFTR itself does not cause smooth muscle dysfunction, because the circular muscle from P5 CF mice had normal activity and dysfunction developed between P7 and P14.

Enteric circular muscle dysfunction in the cystic fibrosis mouse small intestine

BACKGROUND Cystic fibrosis (CF) has multiple effects on the gastrointestinal system, including altered motility. The Cftr knockout mouse model of CF has impaired small intestinal transit but the mechanism is unknown. METHODS Behaviour of circular smooth muscle was studied in an organ bath. Expression levels of prostaglandin (PG) degradative genes were measured by quantitative RT-PCR, and PGE(2) levels were measured by enzyme immunoassay. KEY RESULTS Cystic fibrosis circular muscle activity was erratic and had variable frequency of contractions, as compared to WT. The CF tissue was non-responsive to cholinergic stimulation or direct KCl depolarization. PGE(2) and PGF(2alpha) are significantly elevated in the CF mouse small intestine, and we hypothesized these contribute to impaired smooth muscle activity. After inhibition of PG synthesis, the CF circular muscle exhibited greater cholinergic responsiveness, which was reversed by exogenous PGE(2). PGF(2alpha) enhanced activity of CF tissue only after inhibition of PG synthesis. The enteric microbiota was implicated in PGE(2)-mediated dysmotility because broad spectrum antibiotic treated WT mice, which have slowed transit, exhibit impaired circular muscle activity. This was accompanied by decreased expression of PG degradative genes and increased intestinal PGE(2) levels. Furthermore, administration of oral laxative, which eradicates bacterial overgrowth and improves transit in CF mice, increased expression of PG degradative genes, decreased PGE(2) levels, and improved CF muscle activity. CONCLUSIONS & INFERENCES These results suggest that the enteric microbiota modulates PGE(2) levels in a complex manner, which affects enteric smooth muscle activity and contributes to slower small intestinal transit in CF.