分離腺管を用いた腸上皮化生，非腸上皮化生および胃癌の分子病理学的解析

Molecular Analysis of Gastric Cancer, Intestinal Metaplasia and Non-intestinal Metaplasia with Crypt Isolation Technique

要旨●腸上皮化生の分子異常を明らかにするために，分離腸上皮化生腺管，分離非腸上皮化生腺管，癌分離腺管を用いてDNAメチル化解析を行った．対象は胃癌27例から得られた腸上皮化生腺管と同一粘膜から得られた非腸上皮化生腺管，胃体部大彎から採取された非腸上皮化生腺管と分離胃癌腺管13例を用いた．メチル化解析は2パネル法を用い，HME（high methylation epigenome），IME（intermediate methylation epigenome），LME（low methylation epigenome）に分類した．さらに，分離腺管を採取した粘膜の腸上皮化生粘膜を，粘液形質の観点から完全型（CD10陽性）優位，不完全型（MUC5AC陽性）優位に分類した．腸上皮化生腺管のIMEの頻度は，同一粘膜内の非腸上皮化生腺管のそれより高かった．癌腺管のメチル化はHMEもみられたが，多くはIMEであった．MiR-34b/cのメチル化は腸上皮化生腺管（癌非腸上皮化生腺管）＞同一粘膜内の非腸上皮化生腺管＞胃体部非腸上皮化生腺管の順に高かった．加えて，不完全腸上皮化生優位粘膜のほうが完全腸上皮化生優位型よりIMEの頻度が高かった．メチル化の蓄積が腸上皮化生腺管の発生に重要な役割を担っている可能性が示唆された．

　CpG island hypermethylation is found not only in gastric cancers but also in intestinal metaplasia. However, little is known about the relationship of DNA methylation with intestinal metaplasia. Specimens were examined using a combination of PCR（polymerase chain reaction）-microsatellite assays and PCR-pyrosequencing to detect microsatellite instability and methylation status［HME（high methylation epigenome）, IME（intermediate methylation epigenome）, or low methylation epigenome］. Intestinal metaplasia was also classified into complete and incomplete types according to mucin phenotype. Although the frequency of HME was higher in isolated cancer glands than in isolated intestinal metaplastic glands, IME was common in both intestinal metaplastic glands and cancerous glands. The methylation frequency of MiR-34b/c was higher in intestinal metaplastic and cancerous glands than in non-metaplastic glands. IME was associated with incomplete metaplastic mucosa. Our results suggest that DNA hypermethylation is enhanced with the progression of intestinal metaplasia.