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非小細胞肺癌におけるp16遺伝子導入によるアポトーシスの誘導：片岡正文¹, 藤原俊義¹, Francis R. SPITZ², Jack A. ROTH², Richard J. CRISTIANO², 日伝晶夫¹, 田中紀章¹（¹岡山大・医・一外, ²テキサス大・MDアンダーソン癌セ）

Induction of Apoptosis in Non-Small Cell Lung Cancer Cells by p16ink4 with functinal p53: Masafumi KATAOKA¹, Toshiyosi FUJIWARA¹, Francis R SPITZ², Jack A. ROTH², Richard J. CRISTIANO², Akio HIZUTA¹, Noriaki TANAKA¹ (¹1st Dept. of Surg., Okayama Univ. Med. Sch., ²Univ. of Texas M.D. Anderson Cancer Center)

To explore the potential use of p16 in gene therapy for lung cancer, we introduced p16 into lung cancer cells via a recombinant adenovirus (Ad-p16) and analyzed the effects on cell growth. The non-small cell lung cancer cell lines A549, H460, H226b (-p16, +wild type p53 expression) H226br, H322 (-p16, +mutant type p53 expression) and H1299 (-p16, -p53 expression) were utilized in the analysis. Infection of the cells with Ad-p16 resulted the infected cells being arrested in the G0-G1 phase of the cell cycle accompanied by dephosphorylation of Rb protein. More importantly, analysis for apoptosis using Terminal Deoxynucleotidyl Transferase (TdT) either histochemical staining or flow cytometry indicated that a significant amount of apoptosis could be achieved. At 5 days flowing infection, 19% of A549 cells treated with Ad-p16 showed positive staining while only less than 5% of cells infected with Ad-LacZ stained positive. Similar results were obtained in H460 and H226b. However, H1299 cells did not exhibit any significant levels of staining for apoptosis. And, H226br and H322 showed no significant difference in positive staining of TdT between Ad-p16 and Ad-LacZ. As a result, this may indicate that not only is p16 capable of mediating G₀-G₁ arrest, but is also capable of mediating apoptosis in cells that contain functional p53. Further studies should elucidate the mechanism involved, leading to improved methods for the treatment of lung cancer by gene therapy.