Next, the percentage of the positive stained cells was calculated. Statistical analysis Results are expressed as mean standard error of the mean. Analysis of variance was used to show an overall difference between groups, the Student t test for pairwise comparison of normal distributed parameters, selleck kinase inhibitor and the Mann Whitney U test for para meters without normal distribution. Significance was defined as p 0. 05. Graphical presentations were per formed using GraphPad Prism version 4. 02 for Windows. Results Effects of belinostat in vitro Antiproliferative effect of belinostat on pancreatic cancer cells Belinostat caused a significant dose dependent decrease in cell proliferation in all cell lines tested. The ED50 concentrations for belinostat were 100nM for T3M4, 200nM for AsPC 1 and 600 nM for Panc 1.

Apoptosis induction in pancreatic cancer cells by belinostat treatment As shown in Figure 2, treatment with belinostat induced dose dependent apoptosis in all cell lines tested. The dif ferences compared to control were significant at concen trations of 500 nM or more in all cell lines tested. Belinostat increases gemcitabine mediated apoptosis in pancreatic tumour cells When concomitant use of both drugs was tested in T3M4, AsPC 1 and Panc 1 cells, the combined treatment sig nificantly enhanced the proapoptotic activity compared to gemcitabine treatment alone in Panc 1 and T3M4 cells. Inhibition of histone deacetylation after belinostat treatment In Western Blot analysis with an anti ac histone H4 antibody, treatment with belinostat significantly increased acetylation of histone 4 in all cell lines tested.

Belinostat induces expression of p21Cip1 Waf1 In addition, belinostat was effective in increasing the level of p21Cip1 Waf1, which is related to HDACi induced growth arrest in pancreatic carcinoma cells. Figure 3B demonstrates the increased expression of p21Cip1 Waf1 after belinostat treatment in Panc 1 cells. Inhibition of in vivo tumour growth by belinostat Tumours in the belinostat treatment group showed sig nificantly reduced growth in both subcutaneous and intrapancreatic tumours compared with the control group, in in vivo experiments. The combination of belinostat and gemcitabine therapy showed no additional growth inhibition. Routine hematoxylin eosin histological examination showed no morphological differences between the tumours in the treatment and control groups.

However, analysis of their proliferation rates using an anti Ki 67 antibody, showed a significantly lower num ber of proliferating cells per unit area in the belinostat group compared with the control group. Discussion PDAC remains a therapeutic challenge with Cilengitide a poor overall prognosis. Only surgery with adjuvant chemotherapy can achieve a long term perspective in patients with localized tumours.