Cytokeratin 20 belongs to the epithelial subgroup of the intermediate filament family. Because of its restricted range of expression in humans, it has become an important tool for detecting and identifying metastatic cancer cells by immunohistochemistry and by PCR analysis. Despite its widespread diagnostic use in colorectal cancer and occasional use in pancreatic cancer, little is known about the expression of CK 20 in these tumors in vivo. Therefore, in the present study we characterized CK 20 expression in pancreatic and colorectal cancer by comparison with its expression in the normal pancreas and colon. Tissue samples from 24 patients with pancreatic cancer and from 41 patients with colorectal cancer were examined for CK 20 expression by Northern blot analysis, immunohistochemistry, and in situ hybridization. CK 20 expression was observed in the cancer cells of both cancer types. A subgroup of the pancreatic cancers exhibited a 3.2-fold increase in CK 20 mRNA by comparison with respective normal controls. In contrast, colon cancers underexpressed CK 20 mRNA by comparison with the respective controls. In the normal tissues, CK 20 immunoreactivity was relatively faint and sparse in the pancreatic ductal cells but intense and abundant in the apical portions of the colonic mucosa. CK 20 immunoreactivity was also evident in the ductal cells from the chronic pancreatitis-like lesions adjacent to the cancer cells. Furthermore, distant metastases from pancreas carcinomas exhibited strong CK 20 immunoreactivity. It is concluded that CK 20 is overexpressed in pancreatic cancer and that it can serve as an excellent marker for metastatic pancreatic cancer.

Heparan sulfate proteoglycans (HSPGs) play diverse roles in cell recognition, growth, and adhesion. In vitro studies suggest that cell-surface HSPGs act as coreceptors for heparin-binding mitogenic growth factors. Here we show that the glycosylphosphatidylinositol- (GPI-) anchored HSPG glypican-1 is strongly expressed in human pancreatic cancer, both by the cancer cells and the adjacent fibroblasts, whereas expression of glypican-1 is low in the normal pancreas and in chronic pancreatitis. Treatment of two pancreatic cancer cell lines, which express glypican-1, with the enzyme phosphoinositide-specific phospholipase-C (PI-PLC) abrogated their mitogenic responses to two heparin-binding growth factors that are commonly overexpressed in pancreatic cancer: fibroblast growth factor 2 (FGF2) and heparin-binding EGF-like growth factor (HB-EGF). PI-PLC did not alter the response to the non-heparin-binding growth factors EGF and IGF-1. Stable expression of a form of glypican-1 engineered to possess a transmembrane domain instead of a GPI anchor conferred resistance to the inhibitory effects of PI-PLC on growth factor responsiveness. Furthermore, transfection of a glypican-1 antisense construct attenuated glypican-1 protein levels and the mitogenic response to FGF2 and HB-EGF. We propose that glypican-1 plays an essential role in the responses of pancreatic cancer cells to certain mitogenic stimuli, that it is relatively unique in relation to other HSPGs, and that its expression by pancreatic cancer cells may be of importance in the pathobiology of this disorder.

Purpose

Tumour hypoxia activates hypoxia-inducible factor-1 (HIF-1) and indluences angiogenesis, cell survival and invasion. Prolyl hydroxylase-3 (PHD3) regulates degradation of HIF-1α. The effects of PHD3 in tumour growth are largely unknown.

Experimental design

PHD3 expression was analysed in human pancreatic cancer tissues and cancer cell lines by real-time quantitative PCR and immunohistochemistry. PHD3 overexpression was established by stable transfection and downregulation by short interfering RNA technology. VEGF was quantified by enzyme-linked immunosorbent assay. Matrigel invasion assays were performed to examine tumour cell invasion. Apoptosis was measured by annexin-V staining and caspase-3 assays. The effect of PHD3 on tumour growth in vivo was evaluated in an established orthotopic murine model.

Results

PHD3 was upregulated in well-differentiated human tumours and cell lines, and regulated hypoxic VEGF secretion. PHD3 overexpression mediated tumour cell growth and invasion by induction of apoptosis in a nerve growth factor-dependent manner by the activation of caspase-3 and phosphorylation of focal adhesion kinase HIF-1 independently. In vivo, PHD3 inhibited tumour growth by abrogation of tumour angiogenesis.

Conclusion

Our results indicate essential functions of PHD3 in tumour growth, apoptosis and angiogenesis and through HIF-1-dependent and HIF-1-independent pathways.

Background/aims

Hepatocellular carcinoma (HCC) is a common malignant tumour worldwide, and its differential diagnosis from benign lesions of the liver is often difficult yet of great clinical importance. In the present study, we analysed whether glypican-3 is useful in differentiating between benign and malignant liver diseases and whether it influences the growth behaviour of HCC.

Methods

Northern blot analysis and in situ hybridisation.

Results

Northern blot analysis indicated that expression of glypican-3 mRNA was either low or absent in normal liver, in focal nodular hyperplasia (FNH), and in liver cirrhosis. In contrast, expression of glypican-3 mRNA was markedly increased in 20 of 30 and moderately increased in five of 30 HCC samples. The average increase in glypican-3 mRNA expression in HCC was significant compared with expression in normal liver (21.7-fold increase, p<0.01). In comparison with FNH or liver cirrhosis, glypican-3 mRNA expression in HCC was increased 7.2- (p<0.05) and 10.8-fold (p<0.01), respectively. In addition, pushing HCCs exhibited significantly higher glypican-3 mRNA expression than invading tumours (p<0.05). In situ hybridisation analysis demonstrated weak expression of glypican-3 mRNA in normal hepatocytes and bile ductular cells, and weak to occasionally moderate signals in hepatocytes forming nodules of liver cirrhosis and in regenerated hepatic nodules of FNH. In contrast, glypican-3 in situ hybridisation signals were intense in hepatic cancer cells with even higher levels in pushing HCCs than in invading HCCs.

Conclusions

These findings suggest that glypican-3, in many cases, has the potential to differentiate between benign and malignant liver diseases.