Epigenetic control of microRNA in the development gastric carcinomas in the elderly

胃癌是一种典型的随年龄增长而增多的恶性肿瘤，其致癌机制通常以组织学分化型和未分化型为基础进行研究。然而，胃癌往往在肿瘤内具有组织学多样性，很难解释组织学分类与癌变之间的密切关系。因此，我们检测了微卫星不稳定性(MSI)作为一个标记，发现MSI与年龄、女性发病、乳头状腺癌和实体型低分化腺癌显著相关。与结直肠癌不同，MSI与胃癌的microRNA图谱无关。这可能与多种胃癌有关。然后，我们以老年人常见的胃低分化腺癌为研究对象，发现实体型低分化腺癌与非实体型低分化腺癌的microRNA谱不同。这一结果表明，实体型癌可能以不同于非实体型癌的方式发展。

Gastric cancer is representative malignant neoplasm which increases with aging, and its carcinogenesis has been commonly studied based on the histological classification : differentiated type and undifferentiated type. However, gastric cancer often has histologic diversity within the tumor and it is difficult to explain a close relationship between histological classification and carcinogenesis. Therefore, we examined microsatellite instability (MSI) as a marker and found that MSI was significantly related with older age, occurrence in women, papillary adenocarcinoma and solid-type poorly differentiated adenocarcinoma. Unlike colorectal cancer, MSI was not associated with microRNA profile in gastric cancer. This may be due to variety of gastric cancer. Then, we focused on gastric poorly differentiated adenocarcinoma which often occurred in the elderly and found that microRNA profile in solid-type poorly cancer was different from that in nonsolid-type cancer. This result indicated that solid-type cancer may develop in the different way from nonsolid-type cancer.