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

胃癌是典型的随年龄增长而增加的恶性肿瘤，其癌变机制的研究通常基于组织学分类：分化型和未分化型。然而，胃癌在肿瘤内往往具有组织学多样性，很难解释组织学分型与癌变之间的密切关系。因此，我们将微卫星不稳定性（microsatellite instability， MSI）作为一种标志物进行了研究，发现MSI与年龄、女性发病、乳头状腺癌和固体型低分化腺癌有显著相关。与结直肠癌不同，胃癌的MSI与microRNA谱无关。这可能与胃癌的多样性有关。然后，我们重点研究了常见于老年人的胃低分化腺癌，发现固体型低分化癌的microRNA谱与非固体型癌不同。这一结果表明，固体型癌症可能以不同于非固体型癌症的方式发展。

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.