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Enhancement of Cancer Therapeutic Efficacy through Combined Drug Treatment Using a Proteasome Inhibitor and Other Drugs
|Authors: ||Shen, Yung-Chi|
combination therapy;small molecular inhibitors;bisphosphonates;anaplastic thyroid carcinoma;proteasome inhibitors;tumor necrosis factor
|Issue Date: ||2018-08-22T06:31:22Z
|Abstract: ||基因去氧核糖核酸不斷受到內生及外源基因毒素的威脅，為維持基因完整性，細胞已發展出複雜的修復機制。錯誤的修復將導致癌化或細胞凋亡；相對的，化療及放射療等傳統治療破壞癌症細胞去氧核糖核酸，干擾去氧核糖核酸複製及有絲分裂。癌症治療的主要障礙是抗藥性的產生，甚至是目前最有效的小分子標靶藥物，也會在長期治療後產生抗藥性。再則大部分的治療經常破壞正常組織，所以藥物合併治療應可克服這些障礙。 肺癌位居全球癌症死亡的最大死因，超過四分之一的患者會產生骨頭轉移。我們測試雙磷酸鹽與上皮細胞生長因子受體小分子抑制劑gefitinib在非小細胞肺癌細胞株HCC827的敏感度，結果顯示藥物合併使用比個別使用能引致更高的癌細胞凋亡。動物實驗顯示合併藥物使用除能更降低腫瘤增生外，也能降低gefitinib所產生之脂肪脫除的副作用。這些結果表示藥物合併治療除了能更有效的抑制腫瘤增生外，也能降低治療引起的副作用。 近年來的研究顯示蛋白酶體在去氧核糖核酸修復時扮演重要的角色，引致利用蛋白酶體抑制劑來針對癌細胞修復，進而提高傳統治療效果的假設。我們已報導利用轉譯去氧核糖核酸修復分析法以班馬魚萃取蛋白來證實去氧核糖核酸修復。利用相同分析法比較對紫外線所造成去氧核糖核酸損傷的修復能力，結果顯示蛋白酶體抑制劑預處理的未分化甲狀腺癌細胞萃取蛋白相對於未預處理者有明顯降低；實驗也顯示蛋白酶體抑制劑預處理提高放射療對未分化甲狀腺癌的抑制能力。這些數據表示以蛋白酶體抑制劑為基礎的合併藥物治療能對此致命的惡疾有療效。 我們再探索合併蛋白酶體抑制劑及TRAIL在未分化甲狀腺癌細胞的作用，結果顯示合併處理對此類癌細胞的毒殺能力有加乘效果。最深刻的是有內生腫瘤壞死因子分泌的細胞株Thena-Nu對此合併治療十分敏感，低劑量的藥物就可導致大量凋亡。轉殖腫瘤壞死因子於另一株TRAIL不敏感的未分化甲狀腺癌細胞株8505C也相較於空轉殖者對此合併治療更敏感。這些數據表示有腫瘤壞死因子表現的未分化甲狀腺癌細胞株對此合併治療更有療效。進一步探討藥物合併治療在Thena-Nu的機制顯示蛋白酶體抑制劑和TRAIL迅速calpain及caspase，兩者合用時會產生加乘效果，導致抗凋亡蛋白XIAP的去活化，產生正向回饋機制，放大細胞凋亡。 蛋白酶體抑制劑的前處理也提高順鉑對未分化甲狀腺癌細胞株的毒殺能力；合併蛋白酶體抑制劑與Fas刺激抗體造成的細胞凋亡只出現在Thena-Nu，而其他甲狀腺細胞癌則無此反應。整體而言，合併蛋白酶體抑制劑與其他抗癌藥物可引起大於加成的抗癌效果；這些研究結果也顯示腫瘤壞死因子的表現可當成以蛋白酶體抑制劑為基礎之合併治療的生物標記，至少是針對未分化甲狀腺癌。|
Genomic DNA is consistently threatened by both endogenous and exogenous genotoxic agents. To preserve DNA integrity, cells have evolved sophisticated repair systems. Improper to fulfill these tasks may lead to predisposition of malignant transformation or apoptotic cell death. Conversely, in the course of conventional cancer therapy, chemotherapy and radiotherapy introduce DNA damage, thereby interfering with DNA replication and mitosis, leading to cancer cell death. Nevertheless, the major obstacle in cancer therapy is the generation of resistant subpopulation ultimately leading to recurrence. Even with the most effective small molecule targeted drugs, resistance is inevitably generated following long-term treatment. Additionally, damage to normal cell population is frequently observed in the majority of treatment regimens. Thereby, combination therapy should be able to overcome these drawbacks. An over a quarter of patients with non-small cell lung cancer (NSCLC) developed bone metastases. We demonstrated that combined treatment with bisphosphonate zoledronic acid and EGFR small molecule inhibitor gefitinib significantly enhanced apoptosis of HCC827 cells which harbor EGFR sensitive mutation, as compared to either drug alone. Gefitinib-mediated suppression of tumor growth in athymic nude mice was further enhanced by bisphosphonate zoledronic acid. Moreover, zoledronic acid substantially attenuated gefitinib-induced fat depletion in tumor-bearing animals, further supporting that combination therapy may exert better treatment outcome. Recent studies have revealed a crucial role of the ubiquitin-proteasome system in regulating DNA repair, bringing up the idea that DNA repair could be targeted by proteasome inhibitors (PIs) which may enhance the efficacy of conventional therapy. We reported the establishment of a transcription-based DNA repair assay using zebrafish extracts as model system. Utilizing the same model we showed that pretreatment with proteasome inhibitor bortezomib (BZ) in anaplastic thyroid carcinoma (ATC) cell lines substantially reduced subsequent UV irradiation-induced damage repair compared to medium control; augmentation of ionizing radiation-induced cell death was also detected following short-term BZ pretreatment, suggesting that proteasome inhibitor-based combinatorial treatment could be effective on treating this deadly malignancy. We further explored that combined treatment with BZ and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) (BZ/TR) induced synergistic apoptotic cell death in these ATC cells. Most impressively, Thena-Nu, which harbors constitutive TNF- expression, exhibited hypersensitive to this cotreatment at doses far below reports elsewhere. Transfection of TRAIL-resistant 8505C with TNF- expression vector also displayed increased BZ/TR sensitivity than those of empty transfected, suggesting that ATC cells with TNF- expression are more susceptible to this cotreatment. Mechanistic studies demonstrated that BZ and/or TRAIL alone rapidly induced calpain and caspase activation, leading to inactivation of X-linked inhibitor of antiapoptosis protein (XIAP) and generating positive feedback amplification loops. BZ pretreatment also significantly enhanced cisplatin cytotoxicity in certain ATC cells. Sensitization to Fas agonistic antibody CH11-induced cell death was exclusively observed in Thena-Nu. Collectively, these data indicate that proteasome inhibition in combination with other therapeutic agents should exhibit a more than additive antitumor effect and they may also suggest that TNF- expression could be a potential selective biomarker for BZ-based regimens, at least in ATC.
|Appears in Collections:||[生命科學暨生物科技學系] 博碩士論文|
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