Sharpless Norman E, Ramsey Matthew R, Balasubramanian Periasamy, Castrillon Diego H, DePinho Ronald A
Department of Medicine, Lineberger Cancer Center, CB# 7295, The University of North Carolina School of Medicine, Chapel Hill, NC 27599-7295, USA.
Oncogene. 2004 Jan 15;23(2):379-85. doi: 10.1038/sj.onc.1207074.
Mounting genetic evidence suggests that each product of the Ink4a/Arf locus, p16(INK4a) and p19(ARF), possesses tumor-suppressor activity (Kamijo et al., 1997; Krimpenfort et al., 2001; Sharpless et al., 2001a). We report the generation and characterization of a p19(ARF)-specific knockout allele (p19(ARF)-/-) and direct comparison with mice and derivative cells deficient for p16(INK4a), both p16(INK4a) and p19(ARF), and p53. Like Ink4a/Arf-/- murine embryo fibroblasts (MEFs), p19(ARF)-/- MEFs were highly susceptible to oncogenic transformation, exhibited enhanced subcloning efficiency at low density, and resisted both RAS- and culture-induced growth arrest. In contrast, the biological profile of p16(INK4a)-/- MEFs in these assays more closely resembled that of wild-type cells. In vivo, however, both p19(ARF)-/- and p16(INK4a)-/- animals were significantly more tumor prone than wild-type animals, but each less so than p53-/- or Ink4a/Arf-/- animals, and with differing tumor spectra. These data confirm the predominant role of p19(ARF) over p16(INK4a) in cell culture-based assays of MEFs, yet also underscore the importance of the analysis of tumor suppressors across many cell types within the organism. The cancer-prone conditions of mice singly deficient for either p16(INK4a) or p19(ARF) agree with data derived from human cancer genetics, and reinforce the view that both gene products play significant and nonredundant roles in suppressing malignant transformation in vivo.
越来越多的遗传学证据表明，Ink4a/Arf基因座的每个产物p16(INK4a)和p19(ARF)都具有肿瘤抑制活性（Kamijo等人，1997年；Krimpenfort等人，2001年；Sharpless等人，2001a）。我们报告了一个p19(ARF)特异性敲除等位基因（p19(ARF)-/-）的产生和特征，并与p16(INK4a)、p16(INK4a)和p19(ARF)以及p53缺陷的小鼠和衍生细胞进行了直接比较。与Ink4a/Arf-/-小鼠胚胎成纤维细胞（MEF）一样，p19(ARF)-/- MEF对致癌转化高度敏感，在低密度下表现出增强的亚克隆效率，并且抵抗RAS诱导和培养诱导的生长停滞。相比之下，在这些实验中p16(INK4a)-/- MEF的生物学特征更类似于野生型细胞。然而，在体内，p19(ARF)-/-和p16(INK4a)-/-动物都比野生型动物更容易发生肿瘤，但比p53-/-或Ink4a/Arf-/-动物的易感性低，并且肿瘤谱不同。这些数据证实了在基于细胞培养的MEF实验中，p19(ARF)比p16(INK4a)起主要作用，但也强调了在生物体中对多种细胞类型的肿瘤抑制因子进行分析的重要性。单独缺乏p16(INK4a)或p19(ARF)的小鼠的癌症易患情况与来自人类癌症遗传学的数据一致，并强化了这两种基因产物在体内抑制恶性转化中发挥重要且非冗余作用的观点。
