Gallagher Stuart, Kefford Richard F, Rizos Helen
Westmead Institute for Cancer Research, University of Sydney at Westmead Millennium Institute, Westmead Hospital, Westmead, Australia.
Cell Cycle. 2005 Mar;4(3):465-72. doi: 10.4161/cc.4.3.1526. Epub 2005 Mar 7.
Expression of the p14ARF tumour suppressor is induced by hyperproliferative signals produced by RAS, MYC and other oncogenes. p14ARF quenches inappropriate mitogenic signaling by activating the p53 pathway, and the frequent loss of p14ARF in human cancer diminishes the duration and level of the p53 response. Consistent with this role, p14ARF accumulation can induce potent cell cycle arrest, but its role in promoting apoptosis has not been well established. Therefore we investigated the effects of p14ARF on the survival and growth of several human cell types. To avoid the toxicity associated with adenoviral-based vectors, we established inducible expression of p14ARF in p53-intact and p53-deficient human cell lines. As expected, transient and inducible expression of p14ARF induced rapid cell cycle arrest only in tumour cells expressing intact p53. Further, p14ARF expression did not promote apoptosis in primary human fibroblasts, or in any human tumour cell line tested, irrespective of p53 status. Instead, p14ARF expression sensitized cells to apoptosis in the presence of inhibitors of topoisomerase II (adriamycin) and transcription (DRB). Thus, loss of p14ARF would be an important step in the selection of apoptotic resistant tumour cells.
p14ARF肿瘤抑制因子的表达是由RAS、MYC和其他致癌基因产生的过度增殖信号诱导的。p14ARF通过激活p53途径来抑制不适当的有丝分裂信号，而在人类癌症中p14ARF的频繁缺失会缩短p53反应的持续时间并降低其水平。与这一作用一致，p14ARF的积累可诱导有效的细胞周期停滞，但其在促进细胞凋亡中的作用尚未得到充分证实。因此，我们研究了p14ARF对几种人类细胞类型存活和生长的影响。为避免与腺病毒载体相关的毒性，我们在p53完整和p53缺陷的人类细胞系中建立了p14ARF的诱导表达。正如预期的那样，p14ARF的瞬时和诱导表达仅在表达完整p53的肿瘤细胞中诱导快速的细胞周期停滞。此外，无论p53状态如何，p14ARF的表达在原代人成纤维细胞或任何测试的人类肿瘤细胞系中均未促进细胞凋亡。相反，在存在拓扑异构酶II抑制剂（阿霉素）和转录抑制剂（DRB）的情况下，p14ARF的表达使细胞对细胞凋亡敏感。因此，p14ARF的缺失将是选择抗凋亡肿瘤细胞的重要一步。
