Trefoil factor family peptides in normal and diseased human pancreas.

OBJECTIVES: Trefoil factor family (TFF) peptides promote wound healing in the gut. Recent evidence has suggested that TFF3 may be a pancreatic mitogen, an unusual role for TFF peptides. We sought to clarify human pancreatic TFF and mucin expression and performed in vitro experiments to see how pancreatic cell lines respond to TFF3 in particular. METHODS: Samples of normal and diseased pancreas (chronic pancreatitis, pancreatic intraepithelial neoplasia, neuroendocrine tumors, and pancreatic ductal adenocarcinoma [PDAC]) were studied by immunohistochemistry and in situ hybridization. Pancreatic cell lines were challenged with TFF2 and TFF3 in wound and migration assays. RESULTS: In normal islets, colocalization of insulin or glucagon with TFF3 was common. All TFF messenger RNAs were seen in ductal epithelium. Adenocarcinomas expressed all TFF messenger RNAs. Normal ducts were mucin free; MUC5AC was strongest in pancreatic intraepithelial neoplasia and chronic pancreatitis but was reduced in PDAC. TFF2 induced Panc-1 migration and accelerated wound closure in Capan-2 and COLO-357. Double immunohistochemistry for insulin or TFF3 and Ki67 colabeled only very rare islet cells. TFF3-positive PDAC ducts showed some Ki67 colocalization. CONCLUSIONS: No correlation between TFF3 or insulin and Ki67 was seen without ductal hyperplasia. TFF2 may assist pancreatic tumor cell movement, but TFF3 may not be a pancreatic mitogen.

PHLDA1 expression marks the putative epithelial stem cells and contributes to intestinal tumorigenesis.

Studies employing mouse models have identified crypt base and position +4 cells as strong candidates for intestinal epithelial stem cells. Equivalent cell populations are thought to exist in the human intestine; however robust and specific protein markers are lacking. Here, we show that in the human small and large intestine, PHLDA1 is expressed in discrete crypt base and some position +4 cells. In small adenomas, PHLDA1 was expressed in a subset of undifferentiated and predominantly Ki-67-negative neoplastic cells, suggesting that a basic hierarchy of differentiation is retained in early tumorigenesis. In large adenomas, carcinomas, and metastases PHLDA1 expression became widespread, with increased expression and nuclear localization at invasive margins. siRNA-mediated suppression of PHLDA1 in colon cancer cells inhibited migration and anchorage-independent growth in vitro and tumor growth in vivo. The integrins ITGA2 and ITGA6 were downregulated in response to PHLDA1 suppression, and accordingly cell adhesion to laminin and collagen was significantly reduced. We conclude that PHLDA1 is a putative epithelial stem cell marker in the human small and large intestine and contributes to migration and proliferation in colon cancer cells.

The fibroblast growth factor receptor inhibitor PD173074 blocks small cell lung cancer growth in vitro and in vivo.

Lung cancer is the commonest cancer killer. Small cell lung cancer (SCLC) is initially chemosensitive, but rapidly relapses in a chemoresistant form with an overall survival of <5%. Consequently, novel therapies are urgently required and will likely arise from an improved understanding of the disease biology. Our previous work showed that fibroblast growth factor-2 induces proliferation and chemoresistance in SCLC cells. Here, we show that the selective fibroblast growth factor receptor (FGFR) inhibitor PD173074 blocks H-510 and H-69 SCLC proliferation and clonogenic growth in a dose-dependent fashion and prevents FGF-2-induced chemoresistance. These effects correlate with the inhibition of both FGFR1 and FGFR2 transphosphorylation. We then determined the efficacy of daily oral administration of PD173074 for 28 days in two human SCLC models. In the H-510 xenograft, tumor growth was impaired similar to that seen with single-agent cisplatin administration, increasing median survival compared with control sham-treated animals. Crucially, the effect of cisplatin was significantly potentiated by coadministration of PD173074. More dramatically, in H-69 xenografts, PD173074 induced complete responses lasting >6 months in 50% of mice. These effects were not a consequence of disrupted tumor vasculature but instead correlated with increased apoptosis (caspase 3 and cytokeratin 18 cleavage) in excised tumors. Moreover, in vivo imaging with 3'-deoxy-3'-[(18)F]fluorothymidine-positron emission tomography ([(18)F]FLT-PET) showed decreased intratumoral proliferation in live animals treated with the compound at 7 to 14 days. Our results suggest that clinical trials of FGFR inhibitors should be undertaken in patients with SCLC and that [(18)F]FLT-PET imaging could provide early in vivo evidence of response.