覆盆子萃取物抑制人類鼻咽癌細胞轉移和侵襲之機制探討

鼻咽癌是一種發生在頭頸部的癌症，好發於東亞地區，其中男性發生率比女性高三倍，而造成鼻咽癌病患死亡的主要原因是癌症轉移。在癌症轉移中，腫瘤會釋出基質金屬蛋白酶 (Matrix metalloproteinase, MMP)，分解細胞外基質 (extracellular matrix, ECM)，並藉由血液流動轉移到其他組織，文獻也指出在鼻咽癌的轉移中，MMP-2及MMP-9扮演了重要的角色。有些研究中發現覆盆子 (Rubus idaeus) 在肺癌中有抑制癌症侵襲的能力，然而目前覆盆子萃取物對鼻咽癌的影響尚未釐清。因此在本篇研究中將探討覆盆子萃取物在鼻咽癌中是否能抑制鼻咽癌細胞的轉移和侵襲能力。首先以細胞毒性實驗觀察到覆盆子萃取物在鼻咽癌細胞 (HONE-1, NPC-39 and NPC-BM cell lines) 中並無細胞毒性，接著以Wound healing Assay和Boyden Chamber Assay發現覆盆子萃取物確實能抑制鼻咽癌細胞的爬行和侵襲能力。再利用Gelatin zymography Assay觀察到覆盆子萃取物會抑制鼻咽癌細胞分泌到細胞外的MMP-2；另外，在蛋白表現和mRNA表現方面也觀察到有相同的抑制效果。進而探討其相關的傳遞路徑，觀察到磷酸化ERK蛋白表現量會隨著覆盆子萃取物的濃度上升而被抑制；進一步加入ERK上游蛋白MEK抑制劑 (U0126)，觀察到覆盆子萃取物對鼻咽癌細胞的爬行能力有加成的抑制效果，在細胞外的MMP-2表現也有相同抑制的效果。總結以上結果顯示：在不影響細胞存活率下，覆盆子萃取物透過ERK路徑抑制MMP-2 mRNA、蛋白表現與活性，進而抑制鼻咽癌細胞轉移能力。

Nasopharyngeal carcinoma (NPC) is prevalent in southern China and Southeast Asia. Metastasis involves multiple sequential cascades including degradation of basement membrane and extracellular matrix (ECM) by the matrix metalloproteinases (MMPs). Among these enzymes, MMP-2 and MMP-9 can degrade most components of the ECM and are profoundly involved in the development of NPC invasion and metastasis. Recently reports indicate that crude extracts of Rubus idaeus (RIE) have anticancer ability in the lung cancer cells. However, its effects and mechanism on invasion and metastasis of NPC cancer cells are unclear. The present study aimed to examine the antimetastatic properties of RIE in NPC cell lines. The results of wound healing assays and boyden chamber assays revealed that RIE significantly reduced the migration and invasion of three NPC cells (HONE-1, NPC-39 and NPC-BM cell lines). Gelatin zymography and western blotting analyses showed that RIE significantly inhibited the activity and expression of MMP-2. Western blot analysis also showed that RIE significantly decreased phosphorylated extracellular signal-regulated kinase (Erk) levels. Moreover, blocking of the Erk 1/2 pathway also enhanced the anti-metastatic ability of RIE in NPC cells. In conclusion, RIE inhibited MMP-2 expression and NPC cell metastasis by downregulating Erk1/2 signals pathways and, thus, exerts beneficial effects in chemoprevention.