Nguyen A, Jing Z, Mahoney P S, Davis R, Sikka S C, Agrawal K C, Abdel-Mageed A B
Department of Urology, SL-42, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Cancer Lett. 2000 Nov 28;160(2):133-40. doi: 10.1016/s0304-3835(00)00534-6.
The antiapoptotic and mitogenic responses of metallothionein (MT) have been well documented in vitro. While MT protein overexpression, frequently encountered in a number of human primary tumors, has been shown to be correlated with disease progression, little information is available on the in vivo isoform expression of MT. In this study we have demonstrated the occurrence of MT proteins and further defined their differential expression profile in human primary renal cell carcinoma (RCC). Pooled normal human kidney RNA and paired biopsy specimens (tumor and control) obtained from 11 patients diagnosed with RCC with tumor grade ranging from 1-3 and a pathological staging of T2-T3 (N0M0) were used for the study. Samples were analyzed for the presence of MT protein using immunohistochemical (IHC) analysis and for MT isoform-specific mRNA expression by reverse transcriptase polymerase chain reaction. Metallothionein protein assumed both cytoplasmic and nuclear staining in cancer cells and was detected in eight of 11 samples (72%) with polyclonal antibodies. The immunoreactivity of MT protein, but not its cellular localization, in RCC specimens suggests a relationship between and advanced disease. While alterations in the basal level of expression of MT-1E, MT-1F and MT-1X genes remained unchanged, significant up-regulation of MT-2A and down-regulation of MT-1A and MT-1G transcripts was observed in RCC tissue specimens when compared with controls. Intriguingly, the paired RCC biopsy specimens had lower MT-1H transcripts than pooled normal human controls. We here provide the first report of the differential expression of MT isoforms in human RCC and that this data further support the role of MT-2A in tumorigenesis.
金属硫蛋白（MT）的抗凋亡和促有丝分裂反应在体外已得到充分证明。虽然在许多人类原发性肿瘤中经常遇到MT蛋白过表达，且已表明其与疾病进展相关，但关于MT在体内的异构体表达的信息却很少。在本研究中，我们已经证明了MT蛋白的存在，并进一步确定了它们在人类原发性肾细胞癌（RCC）中的差异表达谱。使用来自11名被诊断为RCC的患者的混合正常人肾RNA和配对活检标本（肿瘤和对照）进行研究，这些患者的肿瘤分级为1 - 3级，病理分期为T2 - T3（N0M0）。使用免疫组织化学（IHC）分析样本中MT蛋白的存在情况，并通过逆转录聚合酶链反应分析MT异构体特异性mRNA的表达。金属硫蛋白在癌细胞中呈现细胞质和细胞核染色，并在11个样本中的8个（72%）中通过多克隆抗体检测到。RCC标本中MT蛋白的免疫反应性而非其细胞定位表明其与晚期疾病之间存在关联。虽然MT - 1E、MT - 1F和MT - 1X基因的基础表达水平变化未改变，但与对照相比，在RCC组织标本中观察到MT - 2A显著上调，MT - 1A和MT - 1G转录本下调。有趣的是，配对的RCC活检标本的MT - 1H转录本低于混合的正常人对照。我们在此首次报道了MT异构体在人类RCC中的差异表达，并且该数据进一步支持了MT - 2A在肿瘤发生中的作用。
