J Transl Med. 2013 Oct 1;11:239. doi: 10.1186/1479-5876-11-239.
The incidence and mortality of hepatitis C virus (HCV)-induced hepatocellular carcinoma (HCC) is higher in African Americans (AA) than other racial/ethnic groups in the U.S., but the reasons for this disparity are unknown. There is an urgent need for the discovery of novel molecular signatures for HCV disease progression to understand the underlying biological basis for this cancer rate disparity to improve the clinical outcome.
We performed differential proteomics with isobaric labeling tags for relative and absolute quantitation (iTRAQ) and MS/MS analysis to identify proteins differentially expressed in cirrhotic (CIR) and HCC as compared to normal tissues of Caucasian American (CA) patients. The raw data were analyzed using the ProteinPilot v3.0. Searches were performed against all known sequences populating the Swiss-Prot, Refseq, and TrEMBL databases. Quality control analyses were accomplished using pairwise correlation plots, boxplots, principal component analysis, and unsupervised hierarchical clustering. Supervised analysis was carried out to identify differentially expressed proteins. Candidates were validated in independent cohorts of CA and AA tissues by qRT-PCR or Western blotting.
A total of 238 unique proteins were identified. Of those, around 15% were differentially expressed between normal, CIR & HCC groups. Target validation demonstrates racially distinct alteration in the expression of certain proteins. For example, the mRNA expression levels of transferrin (TF) were 2 and18-fold higher in CIR and HCC in AA as compared to CA. Similarly; the expression of Apolipoprotein A1 (APOA1) was 7-fold higher in HCC of AA. This increase was mirrored in the protein expression levels. Interestingly, the level of hepatocyte nuclear factor4a (HNF4a) protein was down regulated in AA, whereas repression of transcription is seen more in CA compared to AA. These data suggest that racial disparities in HCC could be a consequence of differential dysregulation of HNF4a transcriptional activity.
This study identifies novel molecular signatures in HCV-induced HCC using iTRAQ-based tissue proteomics. The proteins identified will further enhance a molecular explanation to the biochemical mechanism(s) that may play a role in HCC racial disparities.
在美国，非裔美国人（AA）中丙型肝炎病毒（HCV）引起的肝细胞癌（HCC）的发病率和死亡率高于其他种族/族裔群体，但造成这种差异的原因尚不清楚。迫切需要发现新的 HCV 疾病进展的分子特征，以了解这种癌症发病率差异的潜在生物学基础，从而改善临床结果。
我们使用相对和绝对定量的同重同位素标记标签（iTRAQ）和 MS/MS 分析进行差异蛋白质组学研究，以鉴定与白种人（CA）患者的正常组织相比，在肝硬化（CIR）和 HCC 中表达差异的蛋白质。使用 ProteinPilot v3.0 对原始数据进行分析。搜索针对填充 Swiss-Prot、Refseq 和 TrEMBL 数据库的所有已知序列进行。通过成对相关图、箱线图、主成分分析和无监督层次聚类进行质量控制分析。进行有监督分析以识别差异表达的蛋白质。通过 qRT-PCR 或 Western 印迹在 CA 和 AA 组织的独立队列中验证候选物。
共鉴定出 238 个独特的蛋白质。其中，约 15%的蛋白质在正常、CIR 和 HCC 组之间表达差异。靶标验证表明某些蛋白质的表达在种族上存在明显差异。例如，与 CA 相比，在 AA 中 CIR 和 HCC 中转铁蛋白（TF）的 mRNA 表达水平高 2 倍和 18 倍。同样，载脂蛋白 A1（APOA1）在 AA 的 HCC 中表达高 7 倍。这种增加反映在蛋白质表达水平上。有趣的是，HNF4a 蛋白水平在 AA 中下调，而转录抑制在 CA 中比在 AA 中更为明显。这些数据表明，HCC 中的种族差异可能是 HNF4a 转录活性差异失调的结果。
本研究使用 iTRAQ 基于组织蛋白质组学鉴定了 HCV 诱导的 HCC 中的新型分子特征。鉴定出的蛋白质将进一步增强对可能在 HCC 种族差异中起作用的生化机制的分子解释。
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