Department of Experimental Research, Sun Yat-sen University cancer center, Guangzhou, China.
BMC Cancer. 2010 Sep 1;10:467. doi: 10.1186/1471-2407-10-467.
Overexpression of Bmi-1 has been observed in a variety of cancers, and it has been suggested to be an independent prognostic marker for the patients. The objective of this study was to determine the level of Bmi-1 expression or its autoantibodies in human esophageal squamous cell carcinoma (ESCC) and to correlate it with clinicopathologic data.
We first examined Bmi-1 expression in ESCC cell lines and tumor samples by RT-PCR and Western blot analysis. We then analyzed Bmi-1 protein expression in 171 clinicopathologically characterized ESCC cases by immunohistochemistry. In addition, we detected its autoantibodies in sera of patients with ESCC by ELISA.
We found that Bmi-1 expression was higher in the immortalized cells, cancer cell lines and most cancer tissue than in non-tumorous control tissue at both mRNA and protein level. In addition, Bmi-1 expression was observed in 64.3% (110 of 171) archive ESCC specimen by immunohistochemistry analysis, and the location of Bmi-1 in ESCC was in the nuclei instead of cytoplasm of tumor cells. There was a significant difference of Bmi-1 expression in patients categorized according to stage (P = 0.003) and pN classification (P = 0.047). Multivariate analysis suggested that Bmi-1 expression was an independent prognostic marker for ESCC patients. A prognostic significance of Bmi-1 was also found in the subgroup of T3~T4 and N1 tumor classification. Bmi-1 autoantibodies were detected in sera of 39.0% (62 of 159) ESCC patients. The correlations between anti-Bmi-1 antibodies and tumor stage (P = 0.040), or lymph node status (P < 0.001) were significant.
Our results suggest that Bmi-1 protein is a valuable marker of ESCC progression. The presence of Bmi-1 autoantibodies in sera from patients with ESCC may have clinical utility in esophageal cancer diagnosis.
Bmi-1 的过表达已在多种癌症中被观察到，并且它被认为是患者的独立预后标志物。本研究的目的是确定 Bmi-1 在人食管鳞状细胞癌（ESCC）中的表达水平或其自身抗体，并将其与临床病理数据相关联。
我们首先通过 RT-PCR 和 Western blot 分析检查了 ESCC 细胞系和肿瘤样本中的 Bmi-1 表达。然后，我们通过免疫组织化学分析了 171 例临床病理特征明确的 ESCC 病例中的 Bmi-1 蛋白表达。此外，我们通过 ELISA 检测了患者血清中的 Bmi-1 自身抗体。
我们发现，在永生化细胞、癌细胞系和大多数癌症组织中，Bmi-1 的表达在 mRNA 和蛋白质水平上均高于非肿瘤对照组织。此外，通过免疫组织化学分析，在 64.3%（171 例中的 110 例）存档的 ESCC 标本中观察到 Bmi-1 的表达，并且 Bmi-1 在 ESCC 中的位置位于肿瘤细胞的细胞核而不是细胞质中。根据分期（P = 0.003）和 pN 分类（P = 0.047）对患者进行分类时，Bmi-1 的表达存在显著差异。多变量分析表明，Bmi-1 的表达是 ESCC 患者的独立预后标志物。在 T3~T4 和 N1 肿瘤分类的亚组中也发现了 Bmi-1 的预后意义。在 39.0%（159 例中的 62 例）ESCC 患者的血清中检测到 Bmi-1 自身抗体。抗 Bmi-1 抗体与肿瘤分期（P = 0.040）或淋巴结状态（P < 0.001）之间存在显著相关性。
我们的结果表明，Bmi-1 蛋白是 ESCC 进展的有价值标志物。在 ESCC 患者的血清中存在 Bmi-1 自身抗体可能在食管癌的诊断中有临床应用价值。
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