Supplementary Material for: The Silencing of N-myc Downstream-Regulated Gene-1 in an Orthotopic Pancreatic Cancer Model Leads to More Aggressive Tumor Growth and Metastases

Background: The understanding of molecular mechanisms leading to poor prognosis in pancreatic cancer may help develop treatment options. N-myc downstream-regulated gene-1 (NDRG1) has been correlated to better prognosis in pancreatic cancer. Therefore, we thought to analyze how the loss of NDRG1 affects progression in an orthotopic xenograft animal model of recurrence. Methods: Capan-1 cells were silenced for NDRG1 (C^sil) or transfected with scrambled shRNA (C^scr) and compared for anchorage-dependent and anchorage-independent growth, invasion and tube formation in vitro. In an orthotopic xenograft model of recurrence tumors were grown in the pancreatic tail. The effect of NDRG1 silencing was evaluated on tumor size and metastasis. Results: The silencing of NDRG1 in Capan-1 cells leads to more aggressive tumor growth and metastasis. We found faster cell growth, double count of invaded cells and 1.8-fold increase in tube formation in vitro. In vivo local tumors were 5.9-fold larger (p = 0.006) and the number of metastases was higher in animals with tumors silenced for NDRG1 primarily (3 vs. 1.1; p = 0.005) and at recurrence (3.3 vs. 0.9; p = 0.015). Conclusion: NDRG1 may be an interesting therapeutic target as its silencing in human pancreatic cancer cells leads to a phenotype with more aggressive tumor growth and metastasis.