大腸癌為發生率很高的癌症類型，是全世界致死率前三名的癌症，大約有一半的病人最終會產生癌症轉移。腫瘤能對抗傳統化療以及放射療法的原因在於它複雜的異質性。研究發現在腫瘤中有一群非常少量的細胞稱為癌症幹細胞。癌幹細胞具有自我更新、抗藥性以及轉移的能力被認為是使腫瘤產生異質性的主要原因，越來越多研究以殺死癌幹細胞作為一個治療癌症的策略。因此，具有高度幹細胞的標記表現的病人應該會有較差的預後表現。

在此篇研究中我們和林澤教授的實驗室合作（國立清華大學通訊工程研究所），利用他們以系統生物學篩選出來的四個可能的大腸癌幹細胞預後標記 CAND1、COPS5、GRB2以及14-3-3θ。為了探討這四個標記對於預後的影響，我們利用了免疫組織化學染色法（Immunohistochemistry, IHC）對大腸癌的患者組織進行染色，並使用半定量的計算方式對染色結果進行量化，將病人分為正及負的表現群以利於計算腫瘤分期、淋巴轉移以及遠端轉移等預後的情形。我們比較了傳統的8個癌幹細胞標記：EpCAM、CD44、ALCAM、CD133、ABCB1、ABCC1、ABCG2、ALDH1A1以及新的4個大腸癌幹細胞標記。結果顯示，單一表現的傳統癌幹細胞標記對預後不具有顯著性的影響。相反地，四個可能標記中的GRB2以及14-3-3θ高度表現會降低大腸癌病患的存活率。不僅如此，我們發現他們在大腸癌病患中呈正相關的表現。在組合標記進行存活分析的結果中, GRB2和14-3-3θ 的共同表現更降低了大腸癌患者的存活率。綜合以上結果，我們認為GRB2和14-3-3θ是新的大腸癌幹細胞以及預後的標記，不僅比傳統的癌幹細胞更加的準確，他們的共同表現更惡化了大腸癌的預後情形。

A common cancer among males and females, colon cancer (CC) contributes to significant cancer-related deaths. Approximately 50% of CCs metastasize. Tumor undergoing traditional chemotherapy or radiotherapy may not be completely eliminated due to cellular heterogeneity. A small subset of cells, known as cancer stem cells (CSCs), are reported to promote drug-resistance, self-renewal and metastasis in tumor. Therefore, cancer stem cells are linked to poor prognosis.

In this project, we cooperated with Dr. Che Lin (Institute of Communications Engineering, NTHU), who selected 4 potential colon CSC and prognostic markers via system biology method: COPS5, CAND1, GRB2, and 14-3-3θ. They also constructed protein-protein interaction networks (PPINs) that displayed the correlation of the potential markers with the traditional markers. To validate these candidate proteins as CSC/prognostic markers, we used immunohistochemistry (IHC) to compare them with 8 traditional CSC markers, EpCAM, CD44, ALCAM, CD133, ABCB1, ABCC1, ABCG2 and ALDH1A1. We investigated the prognostic status on 8 traditional CSC markers and 4 potential CSC markers. Oue data suggested that traditional CSC markers are not accurate enough to predict patient survival in colon cancer. On the other hand, two of the potential markers, GRB2 and 14-3-3θ, showed a positive correlation with poor survival in patients, and such correlation was found to be even more significant when combining both markers (GRB2+ and 14-3-3θ+). These results suggest that GRB2 and 14-3-3θ are not only novel colon cancer stem cell (CCSC) markers, their positive combinational expression provide more accurate prognostic prediction in colon cancer patients.

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