Expression and functional significance of CDC25B in human pancreatic ductal adenocarcinoma

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related deaths. Deregulation of cell-cycle control is thought to be a crucial event in malignant transformation, and CDC25 phosphatases are a family of cyclin-dependent kinase activators, which act at different points of the cell cycle, including G1-S and G2-M transition. Here, we investigated the expression and functional significance of CDC25s in PDAC. CDC25B mRNA expression levels in human pancreatic tissue samples were analysed by cDNA array, quantitative PCR and Northern blotting. Immunohistochemistry was carried out to localize and quantify CDC25B expression. Two specific CDC25B inhibitors were utilized to determine the functional relevance of CDC25B. By quantitative RT-PCR, CDC25B mRNA was overexpressed in pancreatic cancer (7.5-fold) in comparison to the normal pancreas. Strong nuclear CDC25B immunoreactivity was present in both pancreatic and metastatic cancer samples, and there was a marked increase of the percentage of positive cells in primary cancer (48.6716.3%) and metastatic tissues (71.773.1%) compared to normal samples (8.371.8%). Two CDC25B inhibitors reduced the growth of pancreatic cancer cell lines, resulting in the accumulation of phosphorylated CDC2 and G2/M arrest. These findings demonstrate an important role of CDC25B in cell-cycle progression, raising the possibility that inhibition of CDC25B may have therapeutic potential in pancreatic cancer.

MicroRNA-148a is down-regulated in human pancreatic ductal adenocarcinomas and regulates cell survival by targeting CDC25B

“…Accordingly, in PDAC it has been shown that there was no correlation between the percentage of CDC25B positive cells and tumor stage/grade implicating dysregulation of CDC25B as an early event in the current multi-step PDAC progression model. 30 Based on these collective observations, we propose a model in which the control of the CDC25B expression is epigenetically pre-regulated in PanINs via miR-148a promoter-methylation and continues to confer proliferative advantage in PDAC via CDC25B. Further this early repression of miR-148a and the resultant increase in CDC25B expression may additionally confer an increased propensity for genomic instability at an early stage in the PDAC progression model, thus facilitating a higher risk to accumulate genetic defects and subsequent enhanced tumor progression.…”

“…29,30 Further CDC25B has been reported to have prognostic relevance in breast, 31 prostate, 32 colorectal 33,34 and gastric cancer, 35 in which the overexpression of CDC25B seemed to correlate with a poor prognosis. However, the mechanism which leads to the dysregulation of the CDC25B within the specific context of tumor proliferation and progression has largely remained elusive.…”

Expression and differential signaling of heregulins in pancreatic cancer cells

“…Optical density was measured at 570 nm using an ELISA plate reader (ThermoLabsystems, OpsysMR, Dreieich, Germany). 67 …”

“…67 Tissue sections were deparaffinized with Roticlear and rehydrated in progressively decreasing concentrations of ethanol. After washing (10 mM Tris-HCL, 0.85% NaCl, 0.1% bovine serum albumin, pH 7.4), slides were incubated with normal goat serum (KPL, Gaithersburg, MD) for 30 min to block nonspecific binding sites.…”

Loss of BNIP3 expression is a late event in pancreatic cancer contributing to chemoresistance and worsened prognosis

“…To assess cell proliferation, the MTT test was used as described previously (Guo et al, 2004). siRNA-transfected cells were trypsinized after 12 h and seeded in triplicate in 96-well plates at densities of 5000 cells/well for SU86.86 and 6000 cells/well for Panc-1 and T3M4.…”