Analysis of the VHL Tumor Suppressor Gene in Kidney Cancer

VHL肿瘤抑制基因的体细胞改变是在肾细胞癌（RCC）的散发性透明细胞亚型中观察到的最常见的遗传改变之一。共187例接受肾切除术的日本透明细胞肾细胞癌患者进行了体细胞VHL基因改变和临床病理和预后数据的研究。在108例（57%）样本中检测到VHL突变。VHL改变与134例接受根治性肾切除术的I-III期透明细胞肾细胞癌患者的无癌生存率和癌症特异性生存率的预后较好密切相关（logrank P = 0.024和0.023，分别）。这些与无癌生存率和癌症特异性生存率的相关性在相对晚期肿瘤患者中更具有统计学意义（III期[P =.014和.010，或II+III期[P = 0.002和0.009]）或更高级别的肿瘤（[大于或等于]G3 [P = 0.013和0.032]或[大于或等于]G2 [P = 013和018] ...更多信息 ）或出现症状的患者（P = 0.005和0.012）。在调整性别、年龄、分期、分级和症状表现后，VHL改变被确定为一个独立的预后因素。然而，VHL改变与53例接受姑息性或连续性肾切除术的IV期肿瘤患者的癌症特异性生存率无关（logrank P =.760）。我们比较了VHL缺陷型肾癌786-O细胞和用编码VHL的腺病毒载体感染的肾癌786-O细胞的基因表达谱，以鉴定pVHL的靶基因。我们发现细胞周期蛋白D1作为pVHL在高细胞密度下的新靶点。因此，在这些细胞中Rb蛋白的磷酸化水平仍然很高，而在接触抑制下的VHL（+）细胞中没有磷酸化的Rb。即使在低氧状态下的VHL（+）细胞中，在高细胞密度下也观察到细胞周期蛋白D1的异常表达。此外，HIF突变体对pVHL介导的蛋白水解的抗性的异位表达导致VHL（+）细胞中细胞周期蛋白D1的异常表达。两者合计，这些观察结果表明，VHL是所需的下调细胞周期蛋白D1在高细胞密度通过HIF。少

Somatic alteration of the VHL tumor suppressor gene is one of the most common genetic changes observed in the sporadic, clear-cell subtype of renal cell carcinoma (RCC). A total of 187 Japanese patients with clear-cell RCC who underwent nephrectomy were examined for somatic VHL gene alteration and clinicopathologic and prognostic data were also collected. A VHL mutation was detected in 108 (57%) samples. VHL alterations were strongly associated with better prognosis for 134 patients with stage I-III clear-cell RCC treated by radical nephrectomy for cancer-free survival and cancer-specific survival (logrank P =.024 and.023, respectively). These associations with cancer-free survival and cancer-specific survival were more statistically significant among patients with relatively advanced-stage tumors (stage III[P =.014 and.010, respectively] or stage II+III [P =.002 and.009]) or higher-grade tumors (【greater than or equal】G3 [P =.013 and.032] or 【greater than or equal】G2 [P =.013 and.018] … More ) or patients who presented with symptoms (P =.005 and.012). The VHL alteration was determined to be an independent prognostic factor, after adjustment for sex, age, stage, grading, and symptomatic presentation. However, VHL alterations were not associated with cancer-specific survival for the 53 patients with stage IV tumors treated with palliative or adjunctive nephrectomy (logrank P =.760). We compared the gene expression profile between VHL-deflcient renal carcinoma 786-O cells and those infected with an adenovirus vector encoding VHL to identify the target gene of pVHL. We found cyclin D1 as a new target of pVHL at a high cell density. Consequently, the phosporylation level of the Rb protein remained high in these cells whereas there was no phosporylated Rb in VHL (+) cells under the contact inhibition. The abnormal expression of cyclin D1 at a high cell density was observed even in VHL (+) cells under the hypoxic state. Moreover, ectopic expression of a HIF mutant resistant to pVHL-mediated proteolysis causes the abnormal cyclin D1 expression in VHL (+) cells. Taken together, these observations indicate that VHL is required for the down-regulation of cyclin D1 at a high cell density through HIF. Less