根據世界衛生組織國際癌症研究機構(International Agency for Research on Cancer, IARC)於2020年發表的全球癌症負擔數據中顯示：乳癌已成為全球最常見的癌症。其中，針對浸潤癌與癌細胞轉移的乳癌，常結合化學治療的方式控制腫瘤大小。然而化學療法藥物缺乏專一性，因此治療過程常伴隨嚴重的副作用。研究顯示：histidine的代謝可以與抗癌藥物Methotrexate (MTX)行協同作用增強其效能，並在降低MTX的劑量下維持良好的療效。故本篇論文展示一種表面具尖刺狀的Fe-L-histidine奈米載體，它由硫酸亞鐵與histidine藉由超音波震盪的方式反應而成。我們藉由SEM、TEM觀測奈米載體的型態，並藉由ICP-MS與元素分析儀分析載體組成，其中histidine成分佔奈米載體的1.5%。同時，利用靜電交互作用的方式裝載MTX於載體，其藥物包覆效率達33%，藥物承載率達25%。體外實驗結果顯示，奈米載體具有爆發性釋放藥物的性質。由於該性質不利於藥物濃度的控制，故後續實驗改採Fe-L-histidine奈米載體添加MTX的方式進行探討。由螢光染色圖觀測細胞吞噬奈米載體的效率：大部分的載體在與細胞共培養24小時後可有效被吞噬。並觀測模擬生理狀況的奈米載體降解情形，結果顯示：奈米載體的外觀在第七天便已有明顯的破壞。接著藉由CellTiter-Glo®檢測試劑與Live and Dead細胞染色實驗，證實100 µg/ml Fe-L-histidine奈米載體添加44 nM MTX的組別相較於奈米載體與MTX的組別，具有較高的細胞毒性。最後，我們進行小鼠乳癌腫瘤治療，結果顯示：100 µg/ml Fe-L-histidine奈米載體添加每公斤小鼠體重5 mg的 MTX組別腫瘤生長趨勢與控制組並無明顯差異，這可能是因為奈米載體降解速度緩慢，所釋放的histidine難以與注射進小鼠體內的MTX行協同作用，以及MTX的治療劑量過低，其協同作用無法顯著抑制腫瘤生長的緣故。綜上述實驗結果，我們會針對載體降解速度以及其histidine與MTX行協同作用的最佳比例進行後續的實驗探討。

Breast cancer is one of the most commonly occurring cancer cases in the world. Patients with invasive breast cancer or reginal metastasis often treat with chemotherapy. However, chemotherapy has severe adverse effects owing to their lack of specificity. Recent studies have demonstrated that a combination of histidine with methotrexate (MTX), a kind of drug used in chemotherapy, can increase the efficacy of MTX by lowering the availability of tetrahydrofolate, and thus enable reduced dosing of this toxicants. In this study, we proposed a spiky Fe-L-histidine nanoparticles (NPs) which can be loaded with MTX via electrostatic interaction. The developed Fe-L-histidine NPs and MTX-loaded Fe-L-histidine NPs was characterized by SEM, TEM, DLS and FT-IR analysis. In vitro degradation and drug release was demonstrated through the simulated physiological conditions. Moreover, the cytotoxicity of the combination of MTX and Fe-L-histidine NPs is tested by CellTiter-Glo® assay using 4T1 cell lines, and the results disclosed that the combination of MTX and Fe-L-histidine NPs had higher cytotoxicity compared to MTX or Fe-L-histidine NPs. Though, there is no significant difference between the control group and the group of 100 µg/ml Fe-L-histidine NPs with 5 mg kg-1 MTX in the study of in situ vaccination. The reason might be the slow release of histidine due to the slow degradation, making it hard to perform the synergistic effect with MTX, and the reduced dosing of MTX might be too low for the therapy, leading to the synergistic effect not strong enough to inhibit the tumor growth. According to the observed results, we will focus on the degradation process of Fe-L-histidine NPs and optimize the ratio of the concentration of MTX and histidine to perform better synergistic effect in our future work.

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