- 學位論文
探討希樂葆抑制間質蛋白酶活化及攝護腺癌細胞移動及侵襲之效用
Celebrex-mediated inhibition of matriptase activation, migration and invasion in PC3 prostate cancer cells
摘要
近期研究指出異常活化的間質蛋白酶（matriptase）可促使多種人類癌瘤形成與癌症轉移。希樂葆（Celebrex）原是一種非類固醇類抗發炎藥物（NSAIDs），但被認為具有治療癌症與對抗癌細胞轉移之功效。因此於本篇研究中，吾人除了檢測希樂葆對於間質蛋白酶活化過程之抑制外，同時也探討其對攝護腺癌細胞移動與侵襲能力的影響。吾人發現在給予攝護腺癌細胞（PC3 cells）希樂葆後，可顯著壓抑癌細胞之移動以及侵襲之能力， 同時也抑制了間質蛋白酶的活化。 希樂葆具有抑制攝護腺癌細胞轉移與移動的能力，可能是透過下列兩種方式：其一為亞型環氧化酶（cyclooxygenase 2,COX2）依賴型之機制；其二為非亞型環氧化酶依賴型之機制。在亞型環氧化酶依賴型機制方面，是因為在實驗中觀察到將亞型環氧化酶以基因剔除法（gene knockdown）抑制之後，可引發癌細胞之移動與侵襲能力的衰減；而透過此種方式所造成的衰減可以藉由添加前列腺素E2 (prostaglandin E2)或其訊息傳遞下游之第二訊息者（second messenger），環狀單磷酸腺酐（cAMP）之後，而將此衰減現象回復。以上所論述之結果已明顯指出亞型環氧化酶在攝護腺癌細胞轉移過程中其實占有相當角色。另一方面，吾人也觀察到希樂葆對於Ｂ型蛋白激酶（PKB/Akt）具有抑制的現象。但把亞型環氧化酶剔除後所造成對間質蛋白酶活化之影響不大，此結果顯示應有其他非環氧化酶依賴型機制參與間質蛋白酶活性的調控。因此吾人推論希樂葆可能透過抑制Ｂ型蛋白激酶來壓抑間質蛋白酶活化，此稱為非亞型環氧化酶依賴型機制。綜合以上結果，可以發現希樂葆明顯地表現出對於攝護腺癌細胞移轉以及間質蛋白酶抑制的現象，蛋兩者不存在因果關係。基於以上論點，希樂葆在未來具有潛力發展成為治療癌症與抗癌症轉移方面的藥物。
並列摘要
Recent studies show that abnormal matriptase activation can promote tumor onset and cancer metastasis in human carcinomas, including prostate cancer. Celebrex, one of the NSAIDs, has been proposed to possess anti-metastatic and chemopreventive functions. In this study, we examined the effects of Celebrex on matriptase activation, prostate cancer cell migration and invasion. We found that administration of Celebrex to prostate cancer PC3 cells dramatically suppressed the cell migration and invasion, and concomitantly inhibited matriptase activation. The inhibition of prostate cancer cell migration and invasion by Celebrex was via COX2-dependent and COX2-independent mechanisms. This was because COX2 silence in PC3 cells downregulated prostate cancer cell migration and invasion. Additions of PGE2 and its downstream second messenger cAMP could restore the cancer cell invasion which was suppressed by COX2 knockdown. Thus, the results indicated that COX2 played a role in prostate cancer cell invasion. On the other hand, Celebrex also inhibited Akt activation and the level of activated matriptase. Since we observed that COX2 silencing only had a marginally effect on the level of activated matriptase in PC3 cells, there was a COX2-independent mechanism for Celebrex to inhibit matriptase activation. The data taken together indicated that Celebrex exhibited an inhibitory role in matriptase activation, prostate cancer cell migration and invasion. Celebrex may be a potential candidate as a potent chemopreventive or therapeutic compound for prostate cancer.