MAL2 expression predicts distant metastasis and short survival in pancreatic cancer

Background: Pancreatic cancer is associated with a devastating prognosis, partially because of its aggressive metastatic ability. Identification of prognostic markers of metastasis would be useful in the clinical management of postoperative patients with pancreatic cancer. Mal, T-cell differentiation protein 2 (MAL2) has been identified as a molecule predictive of metastases; the clinical relevance of MAL2 in pancreatic cancer is unknown.

Methods: Orthotopic human pancreatic cancer xenografts from the pancreatic cancer cell line SUIT-2 were established in nude mice. Only liver metastasis was harvested and cultured. These metastatic cycles were repeated 5 times to establish a highly metastatic cell line, termed metastatic SUIT-2 (MS). We investigated proliferation and motility of MS cells compared with those of the parent SUIT-2. Microarray analysis was performed to investigate differences in gene expression. We also performed immunohistochemical analysis of 89 formalin-fixed, paraffin-embedded human pancreatic cancer tissue samples to investigate the clinical significance of MAL2 expression.

Results: MS cells showed a greater metastatic rate after orthotopic implantation than parental SUIT-2. MS cells had increased motility but decreased proliferation compared with parental SUIT-2. Microarray analyses showed that 26 genes were significantly upregulated (>10-fold) in MS cells compared with parental SUIT-2, particularly MAL2 expression. Immunohistochemical analysis showed that high expression of MAL2 was associated with a lesser survival of postoperative patients (P = .03) and a high rate of distant metastasis (P = .008).

Conclusion: We characterized a newly established pancreatic cancer cell line with highly metastatic potential. MAL2 is a promising predictive marker for distant metastasis and short survival in patients with resected pancreatic cancer.