微型核醣核酸參與台灣大腸直腸癌轉移及預後之相關性研究

研究背景：大腸直腸癌是世界上盛行率很高的癌症之一，在台灣每年會有一萬四千個新增病例，而大腸直腸癌的死亡率也是高居癌症死亡率的第三名。對於日益增多的癌症患者，醫療團隊最希望在治療過程中可以早期預測評估患者的預後是否良好，希望可以對腫瘤的治療更能全盤掌握。而微型核醣核酸(microRNAs；miRNA)的功能可以對轉錄後的基因表現有調控作用，許多的miRNA是位於和腫瘤癌細胞形成相關的基因序列上，所以被視為有可能和癌症的發生形成，甚至是將來的預後、轉移復發有相關性。本研究目的是探討腫瘤組織細胞中miRNA-92a以及miRNA-224的表現與臨床大腸直腸癌患者預後的相關性。研究方法：本研究收集手術後之大腸直腸癌腫瘤組織，以同步定量反轉錄聚合酶連鎖反應偵測miR-92a、miR-224,及下游基因的表現，並同時分析標的miRNAs及基因表現與患者的臨床因子、預後、存活率、基因突變及腫瘤復發情形，同時也記錄分析miR-92a及miR-224與其下游訊息路徑的調控及腫瘤轉移的相關性。研究結果：miR-92a與大腸直腸癌的腫瘤淋巴轉移及病理期別有相關性，並發現PTEN基因表現與miR-92a表現呈現負相關；臨床大腸直腸癌腫瘤組織低miR-92a表現與高PTEN基因表現與臨床大腸直腸癌患者有較好的整體存活率(OS)及無疾病存活率(DFS)；miR-92a也可透過對PTEN/PI3K/AKT Signaling Pathway的影響促進細胞移行。miR-224在大腸直腸癌腫瘤組織中的表現量較低，並且與APC基因的變異有相關，高miR-224表現會抑制大腸直腸癌細胞株的移行能力，且miR-224的異常表現會減少Cdc42及SMAD4的表現，並且會抑制Actin-Filaments的形成。結論：從本研究可以初步證實：腫瘤組織中miR-92a及miR-224表現程度高低和腫瘤細胞的侵襲、移行、轉移的調控有相關性，也會影響大腸直腸癌患者臨床病情的預後。

Background: The metastatic spread of tumor cells is the major risk factor affecting the clinical prognosis of colorectal cancer (CRC) patients. The metastatic phenotype can be modulated by dysregulating the synthesis of different structural and functional proteins of tumor cells. MicroRNAs regulate gene expression at the post-transcriptional level and play important roles in tumor development, progression, and metastasis. The aim of this study was to investigate the role of miR-92a and miR-224 in metastasis of colorectal cancer (CRC). Methods. One hundred fifty-eight CRC patients were enrolled. The expression of miR-92a, PTEN, and E-cadherin was analyzed by real-time PCR. Univariate (Kaplan–Meier) analysis was used to analyze primary outcomes included 5-year overall survival and tumor recurrence. CRC cell model studies were used to analyze the miR-92a involved CRC metastasis. The miR-224 expression level was assessed by a quantitative real-time PCR in 79 CRC and 18, nontumor tissues. The relation between gene mutation , cell migration and expression levels of miR-224 in CRC tissues were analyzed.Results. The expression of miR-92a in tumor tissues was significantly positively correlated with lymph node metastasis in CRC patients (p = 0.012). After adjusting for age, gender, and differentiation, this correlation remained significant (p = 0.01). In addition, there was a negative correlation between levels of miR-92a and the PTEN gene (p <0.0001). No any association of miR-92a and E-cadherin was found (p=0.128). Patients with high miR-92a/low PTEN had poorer overall survival (OS) and disease-free survival (DFS) rates than those with high miR-92a/high PTEN, low miR-92a/high PTEN, and low miR-92a/low PTEN. The association of levels of miR-92a and PTEN with tumor cell migration in CRC was also confirmed in CRC cell models. Expression levels of miR-224 in CRC tissues were significantly lower than those in nontumor tissues. Its expression level was associated with the mutation status of the APC gene. Ectopic expression of miR-224 suppressed the migratory ability of CRC cell line, but cell proliferation was less affected. Increased miR-224 diminished Cdc42 and SMAD4 expressions at both the protein and mRNA levels and inhibited the formation of actin filaments.Conclusion. We suggest that miR-92a is involved in lymph node metastasis of CRC patients through PTEN regulated PI3K/AKT signaling pathway. The role of miR-224 is negatively regulating CRC cell migration. The expression level of miR-92a and miR-224 may be useful predictive biomarkers for CRC progression.