Prognostic significance of overexpression of Traf2- and Nck- interacting kinase (TNIK) in colorectal cancer [152 samples]

Background: The potential of expression profiling using microarray analysis as a tool to predict the prognosis for different types of cancer has been realized. This study aimed to identify a novel biomarker for colorectal cancer (CRC). Methods: The expression profiles of cancer cells in 152 patients with stage I-III CRC were examined using microarray analysis. High expression in CRC cells, especially in patients with distant recurrences, was a prerequisite to select candidate genes. Thus, we identified eleven candidate genes, and selected Traf2- and Nck-interacting kinase (TNIK), which was known to be associated with progression in CRC through Wnt signaling pathways. We analyzed the protein expression of TNIK using immunohistochemistry (IHC) and investigated the relationship between protein expression and patient characteristics in 220 stage I-III CRC patients. Results: Relapse-free survival was significantly worse in the TNIK high expression group than in the TNIK low expression group in stage II (p = 0.028) and stage III (p = 0.006) patients. In multivariate analysis, high TNIK expression was identified as a significant independent risk factor of distant recurrence in stage III patients. Conclusion: This study is the first to demonstrate the prognostic significance of intratumoral TNIK protein expression in clinical tissue samples of CRC, in that high expression of TNIK protein in primary tumors was associated with distant recurrence in stage II and III CRC patients. This TNIK IHC study might contribute to practical decision-making in the treatment of these patients. Gene expression profiles for 152 cancer tissues from colorectal cancer patients were measured by Affymetrix HG-U133 Plus 2.0 arrays. Normalization was performed by robust multi-array average (RMA) method under R 2.12.1 statistical software with affy package from BioConductor. The normalized gene expression levels were presented as log2-transformed values by RMA.

研究背景：学界已证实，利用微阵列分析开展表达谱检测可作为预测多种癌症预后的有效手段。本研究旨在针对结直肠癌（colorectal cancer, CRC）筛选新型生物标志物。
研究方法：本研究通过微阵列分析，对152例I~III期结直肠癌患者的癌细胞表达谱进行检测。以结直肠癌细胞高表达、尤其伴远处复发患者的癌细胞高表达水平作为候选基因的筛选先决条件，最终鉴定出11个候选基因，并选取Traf2与Nck相互作用激酶（Traf2- and Nck-interacting kinase, TNIK）——该分子已知可通过Wnt信号通路参与结直肠癌的疾病进展过程。我们采用免疫组织化学（immunohistochemistry, IHC）方法检测TNIK的蛋白表达水平，并在220例I~III期结直肠癌患者中，分析蛋白表达水平与患者临床特征之间的关联。
研究结果：在II期（p=0.028）及III期（p=0.006）结直肠癌患者中，TNIK高表达组的无复发生存期显著短于TNIK低表达组。多因素回归分析显示，TNIK高表达是III期结直肠癌患者发生远处复发的独立危险因素。
研究结论：本研究首次证实了结直肠癌临床组织样本中瘤内TNIK蛋白表达的预后价值，即原发肿瘤组织中TNIK蛋白高表达与II期及III期结直肠癌患者的远处复发显著相关。本项TNIK免疫组织化学研究可为该类患者的临床治疗决策提供参考依据。本研究中，152例结直肠癌患者的癌组织基因表达谱通过Affymetrix HG-U133 Plus 2.0 基因芯片进行检测；数据标准化采用稳健多阵列平均（robust multi-array average, RMA）方法，基于R 2.12.1 统计软件及BioConductor的affy软件包完成；经RMA标准化处理后的基因表达水平以log2转换值形式呈现。