臨牀消化器内科 Vol.13 No.10(7)


特集名 肝癌 --発癌のメカニズムと予防
題名 サイクリンと肝発癌
発刊年月 1998年 09月
著者 正木 尚彦 国立国際医療センター消化器科
【 要旨 】 G1期の進行に重要なサイクリン依存性キナーゼCdk2の活性を促進的および抑制的に制御するcyclinAおよびp21/WAF1に着目し,肝癌患者における両者の発現動態を検討した.癌部におけるcyclinAmRNAの発現は非癌部に比し有意に高頻度で(41% vs 8%),かつ,著明であった.一方,p21/WAF1mRNAは検討したすべての肝組織に発現していたが,その発現量は肝癌分化度の低下に伴い減弱し,(癌部):(非癌部)発現量比はcyclinAmRNA過剰発現を有する肝癌において有意に低値であった(0.31±0.20vs0.88±0.40;p<0.01).両者の相反的な発現異常が協調的に肝癌増殖能の先進をきたし,脱分化現象と相侯って肝癌を進行させると考えられる.
Theme Hepatocarcinogenesis --Mechanism and Prevention
Title Cyclins in Hepatocarcinogenesis
Author Naohiko Masaki Division of Gastroenterology, International Medical Center of Japan
[ Summary ] The mRNA expressions of cyclin A and p21/WAF1, which reguate cyclin-dependent kinase (Cdk2) activity positively and negatively, respectively, were evaluated in liver tissues obtained from patients with hepatocellular carcinoma (HCC). The expression of cyclin A mRNA was more frequently and strongly seen in cancerous tissues than in surrounding non-tumorous liver tissues. p21/WAF1 mRNA was ubiquitously expressed in liver tissues, however, the extent of its expression was weaker in the less-differentiated HCC. The intensity ratios of p21/WAF1 mRNA expression in cancerous tissues to that in non-tumorous liver tissues were 0.88±0.40 in patients with cyclin A mRNA-negative HCC(n=7), and 0.31±0.20 in those with cyclin A mRNA-positive HCC (n=7 ; p<0.01). It is suggested that reciprocal derangement of cyclin A and p21/WAF1 expressions may cooperatively induce accelerated proliferation of carcinoma cells, which in turn causes progression of HCC in conjunction with development of the dedifferentiation process.
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