肺癌中LCRMP1透過調控RAD51基因轉錄促進DNA修復能力

Abstract

DNA損傷修復一直是癌症轉移和化療藥物抗藥性相關研究中的熱門議題。由於基因突變頻率和複製數目變化，使得DNA修復機制發生改變是造成癌症惡化過程中很常見的事件。通常，惡性腫瘤會突變DNA修復基因使它們可藉由非同源性末端結合或同源性定向修復路徑，進而抵抗被放射線或化學物質誘導產生的雙股斷裂。近期，有研究指出DNA修復能力跟癌症轉移存在相關性，但是調控癌轉移相關基因是否會參與細胞中DNA的修復仍然未知。先前，我們實驗室研究發現LCRMP1的表現，除了可以有效促進癌細胞侵襲與轉移能力外，其表現量的高低，在臨床上可用於評估肺癌病人的癒後情形。不僅如此，我們也發現LCRMP1蛋白可以進入細胞核，透過轉錄的方式調控SERPINE1表現並促進腫瘤血管新生。此外，利用體外與體內的研究模式，發現LCRMP1蛋白的表現與肺癌細胞對於化療藥物的抗藥性有明顯的正相關性。這些發現開啟一項新的研究，探討是否癌症轉移的調控子可以參與在DNA修復路徑。從目前結果，我們假設在惡性肺癌細胞中，LCRMP1可能會參與在DNA損傷反應的DNA修復。為了進一步確認，我們使用了pimEJ5-GFP 和 pDR-GFP兩種綠色螢光的報導系統進行偵測，發現LCRMP1的表現對同源性定向的DNA損傷修復路徑(homologous directed recombination簡稱HDR)有較顯著之調控。另外，甚至發現LCRMP1會坐落到RAD51啟動子的區域，透過基因轉錄增加RAD51的表現，進而促進肺癌細胞中DNA損傷的修復。

DNA damage repair is critical for cancer metastasis and chemotherapeutic resistance. The frequency of gene mutations and copy number variations demonstrated that alterations of DNA repair mechanisms are common events in carcinogenesis. Usually, malignant tumors exhibit mutational DNA repair genes which enable them to overcome double strand breaks (DSBs) induced by neither irradiation nor chemical compound via non-homologous end joining (NHEJ) or homology directed repair (HDR). Recently, literatures showed that the DNA repair capacity may correlate with cancer malignancy. However, whether the regulators of cancer metastasis are involved in the process of DNA repair remain as a mystery. In the past, we identified that long form collapsin response mediator protein 1 (LCRMP1) plays as a metastatic enhancer and the expression levels could be used to predict the clinical outcome of lung cancer patients. Moreover, we found that LCRMP1 could increase the expressions of SERPINE1 through transcriptional regulation in cell nucleus, and promote tumor angiogenesis. We even found that the expression of LCRMP1 is positively correlated with chemotherapeutic resistant in vitro and in vivo. The finding creates a vast area to investigate whether the regulators of cancer metastasis are also contributed to DNA repair pathways. These results let us hypothesize that LCRMP1 may collaborate with DNA repair and attend DNA damage response in malignant lung cancer. Here, we used pimEJ5-GFP and pDR-GFP reporter system to explore how LCRMP1 participates in DNA repair, and homology directed repair is dominant upregulation. Furthermore, all results suggest LCRMP1 could bind to the promoter region of RAD51 to promote the expressions through transcriptional regulation and increase the DNA repair capacity in lung cancer cells.