摘要:甲狀腺未分化癌的腫瘤細胞增殖迅速且易轉移,因為此類細胞失去凋亡調控機制,病人多因癌細胞迅速增生轉移,而於短期內死亡。過去的臨床報告顯示,合併手術、放射線治療及化學藥物治療,這是一種治療成功率極低且致命的癌症。我們有關甲狀腺未分化癌的研究,開始於1999年。我們使用腫瘤壞死因子(tumor necrosis factor)處理甲狀腺未分化癌的細胞株(ARO cell line),藉由電子顯微鏡觀察到,腫瘤壞死因子可以誘導甲狀腺未分化癌細胞產生型態學上的分化現象。2001年,我們進一步使用降膽固醇藥物史達汀 (statins, lovastatin)來處理甲狀腺未分化癌的細胞,較低濃度的史達汀可以誘導癌細胞產生分化現象,但在較高濃度下,史達汀可以誘導癌細胞產生細胞凋亡。其分子機轉都在於史達汀改變了細胞膜上的G-蛋白,包括Ras 及 Rho,之後的實驗也發現,史達汀確實可以藉由抑制細胞膜G-蛋白質,降低甲狀腺未分化癌細胞的侵襲性,研究結果刊登於國外重要期刊 (J Clin Endo & Metab、Endocrinology及Endocrine Related Cancer)。有關裸鼠動物實驗模型,我們將ARO細胞株植入裸鼠的皮下組織,並且在腫瘤成長後,以1及5及10毫克/每公斤/每日的餵食劑量治療,雖然使用5及10毫克/每公斤/每日時,史達汀可以明顯的抑制腫瘤生長,並使腫瘤萎縮,但是使用1毫克/每公斤/每日的史達汀時,卻發生腫瘤明顯加速成長的現象,我們稱為『雙元效應』(duality effects),而癌細胞培養的過程中,我們也發現癌細胞所分泌的血管內皮生長因子也會因不同濃度的史達汀,產生『雙元效應』。此外,我們更發現閥蛋白(Flotillin-1)是史達汀處理甲狀腺未分化癌後,細胞分化的重要控制因子。本研究成果已被International Journal of Cancer (IF: 4.734) 接受於2010年刊登,史達汀調控閥蛋白之研究成果,也正在Experimental Cell Research (IF: 3.948) 修訂中 (in revision)。最近,我們以蛋白質體學及西方墨點蛋白質技術,發現史達汀在腫瘤生長過程中所產生的『雙元效應』中,腫瘤加速生長的過程極可能導源於醣類代謝Pentose Phosphate pathway途徑中的轉酮脢 (transketolase)活化效應。因此未來三年中,我們將針對氧化硫胺素/史達汀對轉酮脢/血管內皮生長因子調控甲狀腺未分化癌及甲狀腺腺癌細胞的機制,以蛋白質體學確認不同濃度的氧化硫胺素/史達汀可抑制或活化的蛋白質 (第一年),並設計小型干擾核糖核酸 (small interfering RNA, siRNA) 轉殖於ARO及SW579細胞,阻斷轉酮脢/血管內皮生長因子調控的途徑,觀察史達汀對癌細胞增生或凋亡的影響 (第二年),動物實驗部份,我們將以轉殖阻斷調控轉酮脢/血管內皮生長因子siRNA的ARO及SW579細胞株植入裸鼠,深入研究史達汀在甲狀腺未分化癌出現的『雙元效應』 (第三年),因為就目前全世界使用史達汀治療高血脂症的病患而言,史達汀與其可能加速腫瘤生長的劑量也必須釐清,但是高劑量的史達汀確在動物實驗中的確具有抑制腫瘤生長的效果。在建立基礎的研究成果後,未來我們將進行甲狀腺未分化癌患者的臨床試驗,希望可以利用高劑量的史達汀治療此類病患,延長其生命,並改善其生活品質。
Abstract: Anaplastic thyroid cancer is a fatal malignancy, and it usually progressed rapidly with distant metastasis due to deficiency of apoptotic regulation, and the average period of survival would be less than half year. Since 1999, we initially treated anaplastic thyroid cancer cell line (ARO cells) with TNF-α, the evidences of re-differentiation were firstly observed via scanning electron microscopy. In 2001, we further used statins (lovastatin), a lipid-lowering drug, to treat ARO cells. Apoptosis could be found in ARO cells treated with higher concentrations, however, re-differentiation was noted in cells treated with lower concentrations (25μM). Molecular mechanism revealed that small G-proteins, Ras and Rho, in ARO cellular membrane were the pivotal roles for cellular apoptosis and differentiation via the treatment of lovastatin. These results were published in Journal of Clinical Endocrinology & Metabolism, Endocrinology and Endocrine Related Cancer, respectively.Later, our animal model was carried out, nude mice implanting with ARO cells was established for lovastatin treatment. We set the therapeutic doses in 1, 5, 10 mg/kg/day with control groups. The results revealed that tumor growth was prominent suppressed in nude mice treated with lovastatin, 5 and 10 mg/kg/day in comparison with positive control group. Meanwhile, tumor growth was significantly promoted in mice treated with 1 mg/kg/day as unexpected finding. Lovastatin showed the “duality effects” for tumor progression. We also proved that the duality effects could be found in the supernatant concentrations of vascular endothelial growth factor (VEGF), secreted by ARO cells treated with different doses of lovastatin. Moreover, we found Flotillin 1 as a downstream mediator in lovastatin-induced differentiation of anaplastic thyroid cancer cells. These results were accepted for publication in International Journal of Cancer (IF: 4.734) and revised in Experimental Cell Research (IF: 3.948), respectively. Based on above results and important finding of proteomic changes, either up- or down-regulation, in ARO cells treated with various concentrations of lovastatin, we suppose that statins could be the effective therapy for anaplastic thyroid cancer in higher doses, and its duality effect in tumor progression in lower dose was also needed to be surveyed.Recently, we use proteomic investigation and western blot technique, the duality effects in tumor progression could be due to activation transketolase (TKT), an important and non-oxidative part of Pentose Phosphate pathway (PPP). In the very next three years, we will continue proteomic study to investigate the up- or down-regulation of proteins in anaplastic thyroid cancer cells and follicular thyroid cancer cells (SW579 cell line), including TKT, VEGF, in ARO cells and SW579 cells treated with various concentrations of lovastatin and other statins. Oxythiamine, the inhibitor of TKT, will be further investigated in tumor progression and apoptosis (year 1). We will further design small interfering RNA (siRNA) to transfect into ARO cells/SW579 cells for knocking down the expression of TKT & VEGF, and observe the cellular apoptosis and proliferation after treatment of statins (year 2). We further will implant the ARO cells/SW579 transfected with siRNA, blocking TKT & VEGF, to nude mice for investigating the duality effects in tumor progression related with TKT and VEGF (year 3). In addition, high dose statins did work in suppression of tumor growth in prior nude mice model. We hope to carry out clinical trials with high dose stains for the patients of anaplastic thyroid cancer after clarifying above questions to improve their life quality and even longer survival.