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Aim: To investigate the persistence of side population (SP) cells in pancreatic cancer and their role and mechanism in the drug resistance., Methods: The presentation of side population cells in pancreatic cancer cell line PANC-1 and its proportion change when cultured with Gemcitabine, was detected by Hoechst 33342 staining and FACS analysis. The expression of ABCB1 and ABCG2 was detected by real-time PCR in either SP cells or non-SP cells., Results: SP cells do exist in PANC-1, with a median of 3.3% and a range of 2.1-8.7%. After cultured with Gemcitabine for 3 d, the proportion of SP cells increased significantly (3.8% +/- 1.9%, 10.7% +/- 3.7%, t = 4.616, P = 0.001 < 0.05). ABCB1 and ABCG2 expressed at higher concentrations in SP as compared with non-SP cells (ABCB1: 1.15 +/- 0.72, 5.82 +/- 1.16, t = 10.839, P = 0.000 < 0.05; ABCG2: 1.16 +/- 0.75, 5.48 +/- 0.94, t = 11.305, P = 0.000 < 0.05), which may contribute to the efflux of fluorescent staining and drug resistance., Conclusion: SP cells with inherently high resistance to chemotherapeutic agents do exist in pancreatic cancers, which may be candidate cancer stem cells contributing to the relapse of the tumor.

Aim: To observe whether pancreatic and duodenal homeobox factor-1 enhances the differentiation of pancreatic ductal epithelial cells into insulin-producing cells in vitro., Methods: Rat pancreatic tissue was submitted to digestion by collegenase, ductal epithelial cells were separated by density gradient centrifugation and then cultured in RPMI1640 medium with 10% fetal bovine serum. After 3-5 passages, the cells were incubated in a six-well plate for 24 h before transfection of recombination plasmid XlHbox8VP16. Lightcycler quantitative real-time RT-PCR was used to detect the expression of PDX-1 and insulin mRNA in pancreatic epithelial cells. The expression of PDX-1 and insulin protein was analyzed by Western blotting. Insulin secretion was detected by radioimmunoassay. Insulin-producing cells were detected by dithizone-staining., Results: XlHbox8 mRNA was expressed in pancreatic ductal epithelial cells. PDX-1 and insulin mRNA as well as PDX-1 and insulin protein were significantly increased in the transfected group. The production and insulin secretion of insulin-producing cells differentiated from pancreatic ductal epithelial cells were higher than those of the untransfected cells in vitro with a significant difference (1.32 +/- 0.43 vs 3.48 +/- 0.81, P < 0.01 at 5.6 mmol/L; 4.86 +/- 1.15 vs 10.25 +/- 1.32, P < 0.01 at 16.7 mmol/L)., Conclusion: PDX-1 can differentiate rat pancreatic ductal epithelial cells into insulin-producing cells in vitro. In vitro PDX-1 transfection is a valuable strategy for increasing the source of insulin-producing cells.

Aim: To study the correlations of Pancreas duodenal homeobox-1 with pancreatic cancer characteristics, including pathological grading, TNM grading, tumor metastasis and tumor cell proliferation., Methods: Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect PDX-1 mRNA expression in pancreatic cancer tissue and normal pancreatic tissue. The expression of PDX-1 protein was measured by Western blot and immunohistochemistry. Immunohistochemistry was also used to detect proliferative cell nuclear antigen (PCNA). Correlations of PDX-1 with pancreatic cancer characteristics, including pathological grading, TNM grading, tumor metastasis and tumor cell proliferation, were analyzed by using c2 test., Results: Immunohistochemistry showed that 41.1% of pancreatic cancers were positive for PDX-1 expression, but normal pancreatic tissue except islets showed no staining for PDX-1. In consistent with the result of imunohistochemistry, Western blot showed that 37.5% of pancreatic cancers were positive for PDX-1. RT-PCR showed that PDX-1 expression was significantly higher in pancreatic cancer tissues than normal pancreatic tissues (2(-3.56 +/- 0.35) vs 2(-8.76 +/- 0.14), P < 0.01). Lymph node metastasis (P < 0.01), TNM grading (P < 0.05), pathological grading (P < 0.05) and tumor cell proliferation (P < 0.01) were significantly correlated with PDX-1 expression levels., Conclusion: PDX-1 is re-expressed in pancreatic cancer, and PDX-1-positive pancreatic cancer cells show more malignant potential compared to PDX-1-negative cells. Therefore, PDX-1-positive cells may be tumor stem cells and PDX-1 may act as alternate surface marker of pancreatic cancer stem cells.

Aim: To investigate the effect of nutritional support therapy on severe acute pancreatitis (SAP)., Methods: A total of 96 patients with severe acute pancreatitis were divided randomly into control and treatment groups. The former group received total parenteral nutrition (TPN) via central venous infusion, while parenteral nutrition (PN) and enteral nutrition (EN) therapies were applied in different phases for the latter group. The nutrition status, acute phase responses, pancreas lesions, enteric mucosa penetrability and immune functions were monitored., Results: Body weight and prealbumin concentration were increased in treatment group, compared to those in the control group, but albumin concentration did not change significantly. Acute physiology and chronic health evaluation II (APACHE II) scores decreased after 7 d of treatment, whereas the scores of the control group decreased on the 11(th) day. Concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukine-6 (IL-6) and serum C reactive protein (CRP) dropped earlier in the treatment group (on the 4(th) day) than that in the control group (on the 7(th) day). No difference was observed in pancreatic lesions between the control and treatment groups. Concentration of endotoxin and lactulose/manicol (L:M) ratio of urine did not change in treatment group, but those in the control group were elevated markedly. Compared with the treatment group, CD4:CD8 T cells ratio and immunoglobulin G (IgG) concentration in the control group decreased significantly., Conclusion: Compared to TPN, the combined therapy of EN and PN could improve the nutrition status and moderate the acute phase response obviously. Moreover, the integrity of enteric mucosa and immune function were protected more effectively in treatment group than in the control one. On the other hand, EN did not simulate the excretion of pancreas and avoid exaggerating the inflammation of pancreas. Thus, appropriate application of PN and EN appears to be more effective for patients with SAP.