探討核因子活化B細胞κ輕鏈增強子在貓疫苗注射部位肉瘤之致腫瘤機制

Abstract

貓疫苗注射部位肉瘤（Feline injection site sarcomas, FISSs）為間皮來源之惡性腫瘤，該腫瘤的發生一般被認為與狂犬病疫苗和貓五合一疫苗中的鋁佐劑有關。鋁佐劑具強烈免疫刺激性，易導致疫苗施打部位長期發炎，故FISS發生被認為與長期嚴重慢性炎症相關。長期慢性炎症至今已被證實與許多惡性腫瘤的發生有關，其中，核因子活化B細胞κ輕鏈增強子（nuclear factor-kappa B, NF-κB）訊息傳導路徑的活化於人類慢性炎症導致惡性腫瘤的致病機制中，扮演重要的角色。NF-κB可以透過炎症相關細胞激素刺激而活化，啟動目標調控基因，並轉錄、轉譯出抑制細胞凋亡、促進增生、促進血管新生等分子助長腫瘤生成。有鑑於此，為了瞭解NF-κB在FISS之角色，本研究首先進行福馬林固定和石蠟包埋組織中（FFPE）活化型NF-κB表現情形之免疫染色，結果證實約有32/39（82%）樣本呈現NF-κB表現陽性。接著，為了探討NF-κB表現在貓疫苗注射部位肉瘤之角色，本研究成功建立三個來自不同個體之FISS初代細胞株，並以NF-κB抑制劑Dehydroxymethylepoxyquinomicin （DHMEQ）證實在NF-kB活化路徑受抑制下，FISS初代腫瘤細胞之增殖能力（Cell proliferation）、移行能力（Cell migration）和群落生成能力（Clonogenicity）明顯受到NF-κB抑制劑作用而下降，並能有效促進FISS細胞走向凋亡，且這些試驗皆具有劑量依賴性效應。因此證實NF-κB之活化在FISS致腫瘤機制中扮演關鍵角色，在未來腫瘤治療策略上，抑制NF-κB活化將可能為一新方向。

Feline injection site sarcomas (FISSs) are malignant entities of mesenchymal origin. The disease has been proven to be associated with a vaccine adjuvant, aluminum, which serves as a stimulus, continuously inducing exaggerated inflammatory and immunologic reactions. Chronic inflammation has been implicated in sarcomagenesis. Among various factors, the activation of the nuclear factor-kappa B (NF-κB) signaling pathway has been documented to promote genes associated with tumor progression, and to up-regulate the expression of tumor-promoting cytokines and survival genes in several human solid tumors. To understand the contribution of NF-κB in oncogenesis of FISS, we first detected activated NF-κB in paraffin-embedded specimens and showed that activated form of NF-κB was detected in 82% of FISS cases. To evaluate the role of activated NF-κB on the sarcomagenesis of FISS, three primary cells derived from FISS of three cats exhibiting similar immunohistochemical characteristics were also successfully established. Dose-dependent induction of apoptosis and inhibition of cell proliferation, cell migration, and clonogenicity in FISS primary cells treated with the NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), suggested that NF-κB might play an important role in the sarcomagenesis of FISS. The inhibition of NF-κB may be a new direction for developing therapeutic target for FISS.