| 摘要: | 在台灣地區，口腔癌與食道癌分別佔男性十大癌症死因的第四名及第七名，並且與咀嚼檳榔的習慣有密切的關係。約有七八成奇美醫學中心的口腔腫瘤患者在就醫時仍保有咀嚼檳榔的習慣，故可合理的推論這些患者的腫瘤在開始形成之初即持續且長期地受到檳榔的刺激。為模仿這種活體 (in vivo) 的刺激，我們以百分之五十抑制濃度 (50% inhibitory concentration, IC50) 的檳榔嚼塊萃取物 (betel quid extract, BQE) 以及檳榔子中的主要生物鹼成分－檳榔素 ( arecoline )，連續地刺激口腔 ( OECM-1 ) 及食道 ( CE81T/VGH ) 鱗狀細胞上皮癌細胞株後，再分析存活下來的細胞有何行為上的改變。我們的實驗結果發現經 BQE ( 14.4 mg/ml ) 篩選過的OECM-1，與未經篩選的細胞相較之下，均增加了對順鉑 ( cisplatin ) 的抗藥性，其中並以 BQE 篩選過的細胞增加的幅度最大。這兩種篩選過的OECM-1細胞中被磷酸化的S6激酶的表現量有提高的現象，並且其增強的抗藥性具有 PI-3K依賴性。另一方面，經 BQE ( 14.4 mg/ml ) 與檳榔素 ( 150 mg/ml ) 篩選過的CE81T/VGH，和未經篩選的細胞相較之下，在刮傷試驗中的癒合移動速度有明顯地應增快。這些經BQE與檳榔素篩選的 CE81T/VGH 細胞表現了較高量的MMP-1、與磷酸化的 S6K，而其 MMP-28 與磷酸化的ERK表現量則未增加。此增快的移動速度可被 PD98059、LY294002、MMP-1、MMP-2與MMP-8的中和性抗體所抑制，但加入 MMP-28 抗體、正常老鼠血清與正常兔子血清則不影響。這些結果意味著除了促使正常細胞的癌化之外，檳榔也可能在上消化道的腫瘤形成後，更進一步增加某些基質金屬蛋白酶的表現，導致細胞的移動性加快；或者藉由增強PI-3K 傳遞的訊息使細胞的抗藥性增強。
Oral cancer is the fourth leading cause of cancer death among men in Taiwan and is closely associated with betel quid (BQ) chewing habit. Since 70~80% oral tumor patients recorded in Chi-Mei Medical Center have kept this oral habit upon their hospitalization, it is reasonable to speculate that a newly estabilished tumor may encounter a continuous and long-term stimulation by BQ in these patients. To simulate this in vivo stimulation process, an oral squamous cell carcinoma (OSCC) cell line, OECM-1, and an esophageal carcinoma cell line, CE81T/VGH, were subjected to repeated exposure to 50% inhibitory concentration ( IC50 ) of BQ extract ( BQE ) and arecoline ( the major alkaloid in areca nut ), and the change of cellular behavior of the survived cells was analyzed. Our results have demonstrated that BQE (14.4 mg/ml)- and arecoline (150 mg/ml)-selected OECM-1 cells exhibited strong and moderate cisplatin resistance as compared to non-selected cells, respectively. The level of phosphorylated S6 kinase (S6K) was elevated, and the enhanced drug resistance is PI3K-dependent in both BQE- and arecoline-selected OECM-1 cells. On the other hand, BQE ( 14.4 mg/ml )- and arecoline ( 150 mg/ml )-selected CE81T/VGH cells showed the fastest and moderately faster healing speed in Scratching Test as compared to non-selected cells. Levels of MMP-1, phosphorylated S6K were elevated, and levels of MMP-28 and phosphorylated ERK1/2 remained unchanged in BQE- and arecoline- selected CE81T/VGH cells. The enhanced of cell motility is hampered by PD98059, LY294002, and neutralizing antibodies of MMP-1, MMP-2 and MMP-8, but not by MMP-28 antibody, normal mouse serum, and normal rabbit serum. These results suggest that, in addition to the carcinogenic properties, BQ and arecoline may further facilitate cell motility through upregulation of some MMPs; or enhance drug resistance through amplification of PI3K-mediated signals of established tumors along the upper aerodigestive tract. |
