1. ¹Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
2. ²Department of Oncology, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
3. ³Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA
4. ⁴Division of Tumor Pathology, Kanagawa Cancer Center, Yokohama 241-0815, Japan

Correspondence: M Goggins, Departments of Pathology, Medicine, and Oncology, The Johns Hopkins Medical Institutions, 632 Ross Build., 720 Rutland Ave., Baltimore, MD, 241-0815, Japan. E-mail: mgoggins@jhmi.edu

Received 16 June 2004; Revised 23 July 2004; Accepted 23 July 2004; Published online 13 December 2004.

Abstract

Using microarrays, we have screened for genes reactivated by drugs that modify epigenetic mechanisms in pancreatic cancer cells. One of the genes identified was tissue factor pathway inhibitor 2 (TFPI-2), which encodes for a broad-spectrum serine proteinase inhibitor that negatively regulates the extracellular matrix degradation, an essential step in tumor invasion and metastasis. We therefore investigated the expression and methylation patterns of the TFPI-2 gene in pancreatic adenocarcinoma, and determined its role in tumor growth and invasion. In contrast to its abundant expression in normal pancreas, TFPI-2 mRNA was undetectable in a high fraction of pancreatic cancer cell lines and in primary pancreatic ductal neoplasms (IPMNs). Loss of TFPI-2 expression was associated with aberrant hypermethylation of its promoter CpG island. Treatment with the phorbol ester (PMA), known to stimulate the TFPI-2 promoter activity, augmented the TFPI-2 expression in cell lines with unmethylated or partially methylated TFPI-2, but failed to induce the expression in cell lines that harbored fully methylated TFPI-2. Aberrant methylation of TFPI-2 was also detected in 73% (102/140) of pancreatic cancer xenografts and primary pancreatic adenocarcinomas, was more likely in older patients with pancreatic cancer, and significantly correlated with progression of IPMNs (P=0.0002). Restored expression of the TFPI-2 gene in nonexpressing pancreatic cancer cells resulted in marked suppression in their proliferation, migration, and invasive potential in vitro. We thus conclude that epigenetic inactivation of TFPI-2 is a common mechanism that contributes to the aggressive phenotype of pancreatic ductal adenocarcinoma.