Jun Itakura

Concomitant over-expression of vascular endothelial growth factor and its receptors in pancreatic cancer.

Vascular endothelial growth factor (VEGF) is a potent angiogenic polypeptide that activates 2 distinct high‐affinity tyrosine kinase receptors, flk‐1/KDR and flt‐1. In the present study, we characterized the expression of VEGF and its receptors flk‐1/KDR and flt‐1 in the normal human pancreas and in human pancreatic cancer tissues and cell lines. VEGF, flk‐1/KDR and flt‐1 mRNA levels were elevated in cancer tissues compared with normal pancreas. By immuno‐histochemistry, VEGF, flk‐1/KDR and flt‐1 immunoreactivity co‐localized in many of the cancer cells within the tumor mass. Three (AsPC‐1, Capan‐1 and MIAPaCa‐2) of 6 pancreatic cancer cell lines expressed flk‐1/KDR mRNA and protein, and 4 cell lines (AsPC‐1, Capan‐1, T3M4 and PANC‐1) expressed flt‐1 mRNA transcripts. Binding studies with 125I‐labeled VEGF165 indicated that only Capan‐1 cells exhibited high levels of specific binding. Furthermore, VEGF enhanced the growth of Capan‐1 cells but was without effect in the other cell lines. VEGF also enhanced mitogen‐activated protein kinase (MAPK) phosphorylation and c‐fos induction in Capan‐1 cells, whereas the MAPK kinase inhibitor PD98059 abolished the growth‐stimulatory effect of VEGF. These data indicate that human pancreatic cancers have the capacity to over‐express VEGF and its receptors and suggest that in some instances VEGF may directly promote pancreatic cancer growth via the MAPK pathway. Int. J. Cancer 85:27–34, 2000.

Increased Cyclin D1 in Human Pancreatic Cancer Is Associated with Decreased Postoperative Survival

Cyclin D1 belongs to a family of protein kinases that have been implicated in cell cycle regulation. In the present study we characterized cyclin D1 expression in 6 cultured human pancreatic cancer cell lines and in normal and cancerous human pancreatic tissues. A 4.4-kb cyclin D1 mRNA transcript was present in all cell lines and in all pancreatic tissues. Cyclin D1 mRNA levels were 2.1-fold higher in the pancreatic cancers than in normal pancreatic tissues (p < 0.0002). Cancer patients with lower cyclin D1 levels (n = 16) had a median survival of 15.5 months whereas patients with higher levels (n = 16) had a median survival of 6.5 months (p < 0.007). These data indicate that cyclin D1 expression may serve as a predictor of postoperative survival in pancreatic cancer patients, and raise the possibility that treatment modalities blocking cyclin D1 activity may have a future role in the therapy of these patients.

Amphiregulin antisense oligonucleotide inhibits the growth of T3M4 human pancreatic cancer cells and sensitizes the cells to EGF receptor-targeted therapy

Human pancreatic cancers overexpress the epidermal growth factor (EGF) receptor (EGFR) and all 5 ligands that bind to this receptor, including amphiregulin. It is not known, however, whether amphiregulin contributes in an autocrine manner to enhance pancreatic cancer cell growth. Therefore, we used an amphiregulin antisense oligonucleotide (AR‐AS) to suppress amphiregulin expression in T3M4 human pancreatic cancer cells. These cells express high levels of EGFR and amphiregulin. AR‐AS abolished amphiregulin immunoreactivity in T3M4 cells, decreased amphiregulin release into the medium and inhibited cell growth in a dose‐dependent manner. Exogenous amphiregulin reversed AR‐AS‐mediated growth inhibition. A random oligonucleotide (AR‐R) did not alter either cell growth or cellular amphiregulin immunoreactivity. AR‐AS also increased cellular EGFR protein levels and enhanced the growth‐inhibitory actions of TP40, a chimeric protein consisting of transforming growth factor‐α coupled to Pseudomonas exotoxin that internalizes into cells via EGFR. These findings indicate that there is an important EGFR/amphiregulin autocrine loop in T3M4 cells and raise the possibility that modalities aimed at abrogating amphiregulin action may prove useful in pancreatic cancer, especially when used in conjunction with EGFR‐targeted therapy. Int. J. Cancer 72:512–517, 1997.