腎細胞癌化学療法のin vitroでの実験的研究 2.細胞回転からみたインターフェロンと制癌剤との併用効果

Abstract

ヒト腎細胞癌由来のNC-65細胞に対し, IFN-α単独, IFN-αとvincristine (VCR)あるいはadriamycin (ADM)との併用における増殖抑制効果と, flow cytometry (FCM)をもちい細胞回転におよぼす効果についても検討した.1) NC-65細胞は, IFN-αにより濃度依存性に増殖抑制されるものの, 比較的感受性の低い部類に属する.2) IFN-α単独では6時間から12時間にかけ, G1期からS期への移行阻害が高濃度領域で起こることが示された.IFN接触後24時間から36時間にかけてS期細胞の増加が顕著となり, S期が延長したものと考えられた.3) IFN-αとVCRとの併用により軽度の増殖抑制効果の増強がみられたがADMとの併用ではみられなかった.IFN-αを先行投与し24時間後に制癌剤を接触させると, VCRとの併用では高濃度で同時接触に比し増殖は抑制されたが, ADMとの時間差接触では効果は増強されなかった.4) IFN-αと制癌剤との併用による細胞周期の変化をみると, IFN接触後短時間での細胞回転の阻害はS期前半から中期にみられ, 低濃度ではG2-M期の増加がFCM上顕著に示された.その後のS期の増加はIFN単独に比し, より顕著に長時間みられた.IFNを先行接触させた場合, このような変化が更に顕著にみられた.5) IFN-αによりS期に高率に集積した細胞集団に対し, ADMの細胞周期特異性の効果は認められなかったが, VCRとの併用では同時さらにIFN先行接触により効果は増強され, 有効な併用薬剤と考えられた

To establish a useful combination therapy of interferon (IFN) with antitumor agents, I investigated the antiproliferative effect and change of DNA histograms in vitro after the IFN exposure either alone or in combination with antitumor agents, simultaneously or sequentially, on NC-65 cells derived human renal cell carcinoma. The IFN used was recombinant interferon alpha-2a (IFN-alpha) and the antitumor agents selected were vincristine (VCR) and adriamycin (ADM). IFN-alpha suppressed the proliferation clearly in a dose dependent manner but not so apparently even after the 96-hour exposure. Six to 12 hours after the exposure of IFN-alpha, accumulation of the cells in the G1 phase was observed at the higher concentration, and then increase of S phase cells up to 72 hours, suggesting a G1-S block at a short period and then prolongation of S-phase. VCR combined with IFN-alpha suppressed NC-65 cell proliferation additively, whereas ADM combined with IFN-alpha suppressed it rather less than additively. The sequential exposure of IFN followed by VCR induced the enhancement at a higher concentration but that followed by ADM did not, suggesting that IFN-induced cell modification made the cells more sensitive to VCR. Dose dependent accumulation in the G1-S boundary phase was observed after the combined exposure of IFN-alpha and antitumor agents, especially by sequential exposure, and then accumulation in S and G2-M were observed. The delay of cell progression in the S phase was likely significant when IFN-alpha was used with antitumor agents, such as VCR and ADM.