Gene expression profile of genes-related canceration, invasion, or conversion for metastasis in patients with poorly differentiated adenocarcinoma treated by gastric ESD.

78 Background: We encounter some cases of early gastric cancer treated by endoscopic submucosal dissection (ESD) that are out of the indication criteria after pathologic diagnosis. These cases require additional treatments because of a risk of lymph node metastasis in Japanese Classification. So further prediction factors associated with lymph node metastasis is expected. We are focusing on poorly differentiated adenocarcinomas in early gastric cancer that we treated by ESD and used these tissues to characterize their gene expression profiles related to canceration, invasion or conversion for metastasis. Methods: We examined two cases of intramucosal carcinoma and three of submucosal infiltrating carcinoma histologically diagnosed as poorly differentiated adenocarcinoma after ESD. Those samples are separated five adjacent normal tissues (N), five tumor tissues in mucosal layer (M) and three tumor tissues in submucosal layer (SM) in total 13 lesions. Formalin-fixed, paraffin-embedded tissues were dissected by the laser-captured microdissection technique and were analyzed for targeted 158 gene expressions using a quantitative real-time polymerase chain reaction (PCR) using commercial PCR plate (profile PCR array of genes related to cancer stem cells and epithelial mesenchymal transition). Results: Among genes that elevated in the cancer tissues (M or SM) against the normal tissues, five gene expressions (DKK1, TIMP1, THY1, FN1, COL1A2) were tended to much higher in the submucosal layer compared to the mucosal layer (N < M < SM). When we compared tumor gene expressions in depth of M, three gene expressions (FZD7, ZEB 2, CD 44) are higher in the tumors with submucosal invasion compared to within mucosal layer. Conclusions: Poorly differentiated adenocarcinoma of stomach had high expression level in cancer-related genes even if it was intramucosal tumor. Some of these genes tended to increase as its depth of invasion and the presence of invasion of the SM. It suggested that the biopsy specimen could be a prediction factor of invasion from the surface of gastric cancer, but additional specimens and analysis are necessary to prove these findings.