細胞凋亡相關蛋白表現與光動力治療效果關係之研究

Abstract

背景：由我們過去的研究觀察顯示，以局部塗抹5-氨基酮戊酸(ALA)來進行光動力治療(PDT)的效果，治療口腔疣狀增生(OVH)的效果明顯比口腔白斑(OL)的效果好。而Bax和Bcl-2是細胞凋亡相關蛋白，已有報告指出在不同的腫瘤上，其表現與其預後是有相關的。故本研究的目的是分析Bax和Bcl-2蛋白在口腔疣狀增生及口腔白斑表現是否會影響其對光動力治療的效果。 材料與方法：本研究包含了11例口腔疣狀增生及21例口腔白斑症接受5-氨基酮戊酸光動力治療的患者，以其治療前的切片標本來分析。利用免疫組織化學染色法，分析Bax與Bcl-2蛋白在此32例切片標本的表現。Bax與Bcl-2蛋白在細胞質的染色標記指數(LI)，以陽性染色的細胞數目占所有上皮細胞數目的百分比來給予分數，每10%為一等級，記為1~10級分。陽性染色的細胞，染色的強度指數(SI)區分如下：1：無；2：弱；3：中；4：強。標本的染色標記分數(LS)則定義為LI × SI。Bax與Bcl-2標計分數及Bax/Bcl-2 ratio經過計算後，進行統計分析，比較各組別間的差異。 結果：所有11例OVH經過ALA-PDT後都是完全反應(CR)。21例OL，有7例是完全反應(CR)，9例是部份反應(PR)，5例是無反應(NR)。OVH組比OL組治療反應好(P<0.001)，有統計上有義意之相關。而且，OVH組的Bax平均標記分數(P=0.01)和平均Bax/Bcl-2 ratio(P=0.05)都比OL組高，具有統計上有意義之相關。Bax的標記分數在CR組的表現比PR加NR組(P=0.081)高，具有接近統計上有意義之相關；而Bax/Bcl-2 ratio(P=0.048) 在CR組比PR加NR組高，具有統計上有意義之相關。在比較上，雖然OVH組或CR組的Bcl-2標記分數和Bax/Bcl-2 ratio比OL組或PR加NR組高，但不具有統計上有意義之相關。 結論：我們的結果顯示，OVH接受ALA-PDT的臨床治療效果比OL好，具有統計上有意義之相關；與OL比較起來，這也許與OVH的Bax蛋白過度表現和較低的Bcl-2表現有關。此外，若以ALA-PDT治療口腔癌前病變，Bax/Bcl-2 ratio則是一個好的的臨床預後因子。

Background: Our previous studies showed that oral verrucous hyperplasia (OVH) lesions have a significantly better clinical outcome than oral leukoplakia (OL) lesions when treated with topical 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT). Bax and Bcl-2 proteins are involved in the regulation of apoptosis and have been reported to correlate with prognosis in several tumor types. This study assessed whether the expression of Bax or Bcl-2 in OVH and OL lesions had a significant influence on the clinical outcome of OVH and OL lesions treated with ALA-PDT. Materials and methods: In this study, 11 OVH and 21 OL lesions were treated with ALA-PDT after initial biopsies of the lesions. An immunohistochemical staining was performed to study the expression of Bax or Bcl-2 in these 32 biopsy specimens. The cytoplasmic Bax or Bcl-2 labeling indices (LIs) were counted as a ratio of positive cells to total cells counted and graded as 1 to 10 for a gradual increase of every 10% positive cells. The staining intensity (SI) of positive cells was graded as follows: 1, no staining; 2, weak; 3, moderate; and 4, strong. The labeling score (LS) was defined as LI × SI. The Bax and Bcl-2 LSs and Bax/Bcl-2 ratios in OVH and OL lesions were calculated and compared between groups. Result: All 11 OVH lesions showed CR after ALA-PDT. Twenty-one OL lesions treated with ALA-PDT revealed CR in 7, PR in 9 and NR in 5. OVH lesions had a significantly better clinical outcome than OL lesions (P< 0.001). Moreover, OVH lesions had a significantly higher mean cytoplasmic Bax LS (P=0.01) and mean Bax/Bcl-2 ratio (P=0.05) than OL lesions. Those CR cases also had a marginally significantly higher mean cytoplasmic Bax LS (P=0.081) and a significantly higher mean Bax/Bcl-2 ratio (P=0.048) than PR plus NR cases. Although OVH and CR lesions had a lower mean cytoplasmic Bcl-2 LS and mean Bax/Bcl-2 ratio than OL and PR plus NR lesions, respectively; the difference was not significant. Conclusion: We conclude that the significantly better clinical outcome after treatment with ALA-PDT in OVH than in OL lesions may be due to a significantly higher expression of Bax and a relatively lower expression of Bcl-2 in OVH than in OL lesions. The Bax/Bcl-2 ratio is a good maker for prediction of the clinical outcome of oral premalignant lesions treated with topical ALA-PDT.