探討具5-fluorouracil抗性之口腔癌細胞株的DNA修補能力

Alterations of DNA repair activities in 5-fluorouracil-resistant oral cancer cell lines

蔡蕙瑜(Huei-Yu Tsai)

指導教授 ： 林常申

高雄醫學大學/醫學院/醫學研究所/碩士(2010年)

https://doi.org/10.6832/KMU.2010.00156

摘要

在臨床上，5-fluorouracil (5-FU)被廣泛應用在治療許多類型的癌症上，其中也包含了口腔癌。然而，5-FU的抗藥性經常導致癌症的復發或是治療的失敗，被視為癌症治療的阻礙。目前對於5-FU抗藥性的分子機轉仍未被清楚了解。因此本篇研究的目的是探討在5-FU抗藥性的口腔癌細胞株，其DNA修復能力是否有所改變。研究策略是利用不同濃度的5-FU長期處理口腔癌細胞株(KB及SAS)，建立抗藥性細胞株KB-F5、KB-F10以及SAS-F1；再針對這些細胞株進行DNA修復能力的分析。結果發現：具有5-FU抗藥性的細胞株，其細胞核苷酸切除修復能力是下降的；KB-F5及KB-F10其同源性重組修復的能力會比parental KB高，在SAS-F1與parental SAS之間則沒有顯著差異。在非同源性接合修復能力方面，KB-F5及KB-F10與parental KB並沒有顯著差異，而在SAS-F1會比parental SAS高。分析基因表現後發現，有抗性的細胞都具有p53蛋白質表現量上升的情形。先前研究指出，若p53的活性喪失，可能會導致5-FU抗藥性的產生。所以我們進一步分析其p53的轉錄活性，發現具抗性的細胞有下降的情形。綜合以上結果得知：具5-FU 抗性的細胞株，其細胞核苷酸切除修復能力會降低，KB-F5及KB-F10的抗藥性原因可能是由於同源性重組修復能力增加，而SAS-F1的抗藥性原因可能是由於非同源性接合修復能力增加。

關鍵字

5-fluorouracil ； DNA修補

並列摘要

5-fluorouracil (5-FU) is widely used for treatment of many types of cancers, including oral cancer. However, 5-FU resistance often leads to treatment failure and recurrence. The exact molecular mechanisms of 5-FU resistance have not been fully elucidated. The purpose of this study is to explore the role of DNA repair in 5-FU-resistant oral cancer cell lines. The 5-FU-resistant KB (KB-F5, KB-F10) and SAS (SAS-F1) cell lines were established after a long-term treatment of 5-FU, and were examined for their DNA repair activities. The results showed that nucleotide excision repair (NER) was repressed in 5-FU-resistant cell lines; homologous recombination repair (HRR) was activated in KB-F5 and KB-F10, but not in SAS-F1 when compared with the parental cells. The repair activity via non-homologous end joining (NHEJ) was higher in SAS-F1 than that in parental SAS cells. No significant difference in NHEJ repair could be found between KB and their 5-FU-resistant clones. The expressions of DNA repair genes were examined by western blots. The results showed that p53 was increased in the resistant cells. Previous studies have indicated that loss of p53 activity may lead to 5-FU drug resistance. Indeed, we found that the p53 transcriptional activity was decreased in the resistant cells. These findings suggested that NER activity was decreased in 5-FU resistant KB and SAS cell lines. However, KB-F5 and KB-F10 might acquire 5-FU resistance by elevating HRR activity, while 5-FU resistance of SAS-F1 might be due to the increased NHEJ repair.

並列關鍵字

5-fluorouracil ； DNA repair

參考文獻

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