Analysis of the VHL Tumor Suppressor Gene in Kidney Cancer

VHL肿瘤抑制基因的体细胞改变是肾细胞癌（RCC）散发性透明细胞亚型中最常见的遗传改变之一。187例行肾切除术的日本透明细胞肾细胞癌患者接受了体细胞VHL基因改变检查，并收集了临床病理和预后数据。在108例（57%）样本中检测到VHL突变。经根治性肾切除术治疗的134例I-III期透明细胞RCC患者的无癌生存率和癌症特异性生存率与VHL改变有较好的预后密切相关(logrank P = 0.024；023年,分别)。在相对晚期肿瘤患者（III期[P = 0.014]和III期[P = 0.014]）中，这些与无癌生存和癌症特异性生存的关联更具统计学意义。[P =.002]或II+III期[P =.002]；[009])或更高级别肿瘤（大于或等于）G3 [P =.013；[032]或【大于或等于】G2 [P =.013和。[18]…更多)或出现症状的患者（P = 0.005和0.012）。在对性别、年龄、分期、分级和症状表现进行调整后，确定VHL改变是一个独立的预后因素。然而，在53例接受姑息性或辅助性肾切除术的IV期肿瘤患者中，VHL改变与癌症特异性生存率无关（logrank P = 0.760）。我们比较了VHL偏向性肾癌786-O细胞与编码VHL的腺病毒载体感染的细胞的基因表达谱，以确定pVHL的靶基因。我们发现cyclin D1是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VHL（+）细胞中Rb蛋白没有磷酸化。即使在缺氧状态下的VHL（+）细胞中，cyclin D1也在高细胞密度下异常表达。此外，抗pvhl介导的蛋白水解的HIF突变体的异位表达导致VHL（+）细胞中cyclin D1的异常表达。综上所述，这些观察结果表明VHL是通过HIF在高细胞密度下下调cyclin D1所必需的。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