貓注射部位肉瘤：轉錄體剖析及第二型環氧合酶所扮演之角色

Abstract

貓注射部位肉瘤（feline injection-site sarcomas, FISS）是種發生在貓的間質來源惡性腫瘤，其具有高度侵犯性且被認為與注射行為相關，但致病機轉尚未明瞭，目前最廣為接受的假說是，因注射相關創傷和異物性化學物質刺激引發慢性炎症，進而導致FISS的發生。由於慢性炎症能夠提供有利於腫瘤生長的微環境，故在多種腫瘤被認為是誘發腫瘤發生的潛在因子。為了瞭解FISS的腫瘤發生與尋找具有潛力的治療標靶，本研究選擇環氧合酶-2（cycloxygenase-2, COX-2）作為研究目標，並以FISS及正常組織的初代細胞進行COX-2抑制劑（robenacoxib)的體外試驗，評估COX-2抑制劑作為輔助治療藥物的可能性與研究COX-2在FISS腫瘤發生所扮演的角色。此外，本研究也利用次世代基因定序，經由大數據分析FISS與正常組織之基因表現差異，以尋找其他可能的腫瘤生成機制。結果顯示，本研究使用的FISS病例之石蠟包埋組織與初代細胞均可見不等程度的COX-2表現，COX-2抑制劑能夠抑制FISS初代細胞的細胞存活率、移行和細胞群落形成，以及誘發細胞凋亡，並且表現明顯的劑量依賴性，但不同細胞株的敏感性有所差異且不完全與COX-2的表現量相關。本研究顯示COX-2抑制劑可能具有作為FISS輔助治療藥物之潛力。在次世代定序方面，FISS初代細胞不僅在腫瘤途逕如Wnt、Ras以及Rap1的基因表現有顯著變化，炎症反應相關途徑如PI3K-Akt和MAPK亦可見顯著差異，故FISS的腫瘤發生可能與多種炎症反應途徑有關，其扮演的角色仍需要進行更深入的探討。

Feline injection-site sarcomas (FISSs) are highly invasive malignant mesenchymal neoplasm arising from the injection sites in cats. Although the tumorigenesis of FISSs is still uncertain, it is the consensus that FISS is associated with chronic inflammation caused by the irritation of injection-related trauma and foreign chemical substance. Owing to that chronic inflammation can provide a proper microenvironment for tumor development and thus has been known as one of the risk factors of tumorigenesis in many tumors. To investigate the tumorigenesis of FISS and screening potential therapeutic targets of FISS, cyclooxygenase-2 (COX-2), an inflammation enhancing enzyme, is selected as the target of the study and in vitro experiments using FISS- and normal tissue-derived primary cells and robenacoxib, a highly selective COX-2 inhibitor, were performed. In order to screening the potential pathways associated with FISS tumorigenesis, next generation sequencing (NGS) was conducted to compare the differences in gene expression between cells derived from FISS and normal tissue. The results demonstrated that the expression of COX-2 could be detected in formalin-fixed and paraffin embedded FISS tissues and FISS-derived primary cells. The cell viability, migration and colony formation of FISS-derived primary cells could be inhibited and the cell apoptosis could be enhanced by robenacoxib in a dose dependent manner. However, the susceptibility to robenacoxib varied in different lines of FISS primary cells and was not completely correlated with the expression of COX-2. The results of the study suggests that COX-2 inhibitor may have potential as an adjuvant treatment for FISSs. As for the results of NGS, significantly differentially expressed genes associated with not only the pathways in cancer, such as Wnt, Ras and Rap1 signaling pathway, but also pathway associated with inflammation, such as PI3K-Akt and MAPK signaling pathway were revealed. Therefore, the tumorigenesis of FISS might be corelated with multiple inflammatory pathways and their roles on FISS development still need further investigation.