Upregulation of cugbp2 increases response of pancreatic cancer cells to chemotherapy.

PURPOSE: Altered expression and/or function of ribosomal RNA (rRNA)-binding proteins CUGBP2/CELF2 might influence post-transcriptional regulation of the HO-1- and COX-2-mediated cytoprotective pathways and represents an important therapeutic target. The aim of this study was to assess the effects of CUGBP2-mediated post-transcriptional regulation of COX-2 and HO-1 in pancreatic cancer cells in regard of response to gemcitabine (GEM) treatment. METHODS: Expression of CUGBP2, COX-2, and HO-1 was evaluated using qRT-PCR and Western blot methods. Cell viability after treatment with GEM and/or curcumin and siCUGBP2 was evaluated using MTT and crystal violet tests. RNA immunoprecipitation analysis was used to confirm COX-2 and HO-1 post-transcriptional regulation by CUGBP2 protein. RESULTS: CUGBP2 expression at the messenger RNA (mRNA) level was 2.2-fold lower (p = 0.007), but HO-1 and COX-2 expression was increased 6.9- (p = 0.023) and 2.3- (p = 0.046) fold in pancreatic cancer tissues. The median survival of patients with low CUGBP2 expression from the lowest tercile was 13.8 months. The median survival of patients in terciles of middle and high CUGBP2 expression levels was 21.9 month (p = 0.123). Induction of CUGBP2 expression by curcumin resulted in the downregulation of HO-1 and COX-2 and strongly sensitized tumor cells to GEM treatment. However, CUGBP2 silencing upregulated HO-1 and COX-2 protein expression and had a high effect on cells viability. CONCLUSION: Decreased activity of CUGBP2 could be associated with high chemoresistance and early dissemination of pancreatic cancer through the HO-1- and COX-2-mediated cytoprotective and carcinogenesis pathways. Curcumin significantly increased the effectiveness of GEM treatment in vitro via the CUGBP2-mediated post-transcriptional regulation pathway.

Effects of Cyanidin-3-O-glucoside on Synthetic and Metabolic Activity of Ethanol Stimulated Human Pancreatic Stellate Cells.

Activated pancreatic stellate cells (PSC) play a major role in the development of chronic pancreatitis. Flavonoids (C-3-O-G) theoretically may have potential to suppress activated PSC. The aim of our study was to determine the ability of C-3-O-G to invert synthetic and metabolic activity of alcohol stimulated human pancreatic stellate cells (hPSC). In the present study we demonstrate that treatment with C-3-O-G decreased proliferation rate of ethanol activated hPSC by 51%. Synthesis of extracellular matrix proteins in activated hPSC was markedly inhibited, as shown by reduced levels of collagen I and fibronectin expression. The decrease of secretion of fibronectin by 33% and in collagen I-25% in ethanol activated and C-3-O-G treated hPSC was observed. Moreover, treatment of ethanol activated hPSC with C-3-O-G resulted in the decrease of oxygen consumption rate by 44% and reduced levels of ATP synthesis (i.e. energy production) by 41%. Hence, the effects of C-3-O-G on ethanol activated hPSC may provide new insights for the use of anthocyanins as anti-fibrogenic agents in treatment and/or prevention of pancreatic fibrosis.

HuR mediated post-transcriptional regulation as a new potential adjuvant therapeutic target in chemotherapy for pancreatic cancer.

AIM: To investigate the expression of HuR in pancreatic ductal adenocarcinoma (PDA) and to assess the effects of HuR silencing on the expression of cyclooxygenase-2 (COX-2) and heme oxygenase-1 (HO-1) and the in vitro response to gemcitabine (GEM) treatment in pancreatic cell lines. METHODS: We compared the expression of HuR, COX-2, and HO-1 in PDA and normal pancreatic tissue using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot. In addition, the HuR, COX-2 and HO-1 were analyzed in four types of cancer cell lines (MiaPaca2, Su.86.86, Capan-1, and Capan-2) with and without GEM treatment. Immunocytofluorescence analysis was used to investigate HuR localization in cells. Cell viability and response to GEM after HuR silencing were determined with the 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide test and the crystal violet clonogenic assay, respectively. To measure apoptosis, activation of caspases 3/7 was evaluated using immunofluorescence. RESULTS: In PDA tissue obtained from patients not treated with GEM, HuR mRNA expression was 3.2 times lower (P < 0.05) and COX-2 and HO-1 mRNA expression was 2.3-fold and 7.2-fold higher (P < 0.05), respectively, than normal pancreatic tissue (from organ donor). qRT-PCR analysis showed that HuR, COX-2, and HO-1 mRNA were overexpressed in all cancer cell lines treated with the half maximal inhibitory concentration (IC50) dose of GEM compared with control cells (P < 0.05). Western blot analysis revealed that COX-2 and HO-1 levels were significantly decreased in cancer cells after HuR silencing. Furthermore, HuR silencing increased the response to GEM treatment and decreased cell viability by 11.6%-53.7% compared to control cell lines. Caspases 3 and 7 were activated after HuR silencing and GEM treatment in all pancreatic cancer cell lines. In comparison, treatment with GEM alone did not activate caspases 3 and 7 in the same cell lines. CONCLUSION: HuR mediated post-transcriptional upregulation of COX-2 and HO-1 expression after GEM treatment in pancreatic cancer cells. HuR silencing significantly increased the effectiveness of GEM treatment in vitro.