川陳皮素合併celecoxib 抑制腸癌細胞生長之機制探討

Abstract

川陳皮素為分離自柑橘類果皮之多甲氧基黃酮類化合物，可抑制癌細胞COX-2 表現與導致細胞週期停滯。celecoxib 為非類固醇止痛消炎藥 (non-steroidal anti-inflammatory drug, NSAID)，為美國食品藥物管理局認可做為輔助性治療家族性大腸息肉症 (familial adenomatous polyposis, FAP) 之藥物。celecoxib 具有導致腸胃道不適與增加心血管毒性之副作用。本實驗希望藉由川陳皮素與celecoxib 共同處理以減緩藥物副作用。實驗設計以HT-29 與COLO-205 人類大腸癌細胞株為模式，分析不同濃度celecoxib、川陳皮素與共同處理對細胞生長抑制之影響，propidium iodide 及annexin V/PI 染色法分析細胞週期與細胞凋亡，西方墨點法與免疫螢光染色法分析組蛋白H2AX 之磷酸化程度。結果顯示，添加川陳皮素於較低濃度celecoxib 對細胞生長抑制具有相加 (additive effect) 或加乘效果 (synergistic effect)，且於75 μM celecoxib 與50 μM 川陳皮素的組合有較佳加乘效果。celecoxib 與川陳皮素的共同處理可以增加DNA 損傷反應γH2AX 的表現，同時可抑制細胞增生與促進細胞凋亡。以上結果證實，celecoxib 與川陳皮素的共同處理具有提升大腸癌治療效果且可避免高劑量celecoxib 處理所導致毒性之潛力。

Nobiletin, a polymethoxyflavones isolated from citrus peels, could inhibit the COX-2 expression in various cancer cells and lead to cell cycle arrest. A non-steroidal anti-inflammatory drug (NSAID), celecoxib has been approved by the US Food and Drug Administration for the adjunctive therapy in patients with familial adenomatous polyposis (FAP) or colon cancer. However, celecoxib treatment causes undesired side effects, including gastrointestinal and cardiovascular toxicities. Thus, it would be beneficial if combination treatment to provide enhanced therapeutic response and reduce the side effects of medication. HT-29 and COLO-205 human colon cancer cells exposed to various doses of celecoxib, nobiletin and co-treated with both agents were analyzed for cell proliferation, cell cycle analysis by propidium iodide staining, apoptosis analysis by annexin V/PI staining and γH2AX expression by immunofluorescence and western blotting analysis. Our results show that adding nobiletin to subtoxic celecoxib could synergistically or additively inhibit cell proliferation. Particularly, 75 μM celecoxib together with 50 μM nobiletin indicated the synergistic effect. Combining celecoxib with nobiletin significantly increases DNA damage signal, γH2AX levels and concurrently inhibits cell proliferations and promotes cell death by apoptosis. These results suggest that celecoxib-nobiletin co-treatment may provide enhanced therapeutic response in colon cancer cells, while avoiding the toxicity associated with high-dose celecoxib treatment.