Gene expression profiling in lymph node-positive and lymph node-negative pancreatic cancer

Objectives: The purpose of this study was to screen for genes related to lymph node metastasis by comparing the differences in the expression profile between pancreatic cancer with lymph node metastasis and one without, and to predict the invasiveness and the progression of pancreatic cancer on the basis of these findings. Methods: The total RNA of the tissues was extracted from 10 pancreatic cancer specimens, including those with lymph node metastasis and those with no metastasis. It was studied by means of a DNA microarray (oligo chip) consisting of 37,842 genes. We screened out 1.5-fold or more differential gene expressions in at least 5 pairs of samples. We classified both samples and genes using a 2-way clustering analysis. The screened-out genes were identified using real-time polymerase chain reaction. Results: We identified 194 genes, including 66 overexpressed and 128 underexpressed genes, in pancreatic cancer with lymph node metastasis. Among them, we identified some genes related to lymph node metastasis in patients with pancreatic cancer: oncogenes, tumor suppressor genes, apoptosis and antiapoptosis genes, tumor angiogenesis factors, and cell cycle regulators. Genes promoting the growth of tumor cells were highly expressed in lymph node-positive pancreatic cancer, whereas genes inducing apoptosis were underexpressed. Conclusions: We have identified genes that may play an important role in metastasis and survival in patients with pancreatic cancer. These results provide new insight into the study of human pancreatic cancer metastasis, including lymph node metastasis, and ultimately may lead to improving early diagnosis and discovering innovative therapeutic approaches for cancer.