Sildenafil抑制口腔癌細胞錨定非依存性生長之機制

目的: 人類癌細胞能在soft agar中生長爬行以及侵略，顯示其腫瘤的特性。而Sildenafil屬於Phosphodiesterase 5 (PDE5) 抑制劑它可使細胞內cGMP濃度增加及造成Protein kinase G (PKG)上升，之前研究顯示Sildenafil可抑制癌症。所以本研究是想了解Sildenafil對人類口腔癌細胞在soft agar生長的影響，並從其中試著找出可能的機轉。 實驗方法: 選用口腔癌細胞KB 細胞株，使其在soft agar上生長，觀察其所生成的集落。比較Sildenafil 和Tadalafil在不同濃度下，對腫瘤是否有抑制效果，並計算腫瘤的集落數。另外使用西方墨點吸漬法來分析不同藥物不同濃度下對Cyclooxygenase 2 (COX2) pathway的影響。 結果:觀察KB 細胞生長時，發現soft agar中一個癌細胞便可長成一個集落。在Sildenafil 5 µg/ml和10 µg/ml濃度時，KB cell 的集落數和數目明顯下降，且濃度越高集落下降情況越明顯；相較控制組,Tadalafil處理下，KB cell 的集落數和數目都無明顯變化。西方墨點吸漬法發現低濃度下的Sildenafil可抑制COX2 pathway。 結論: Sildenafil可抑制KB 腫瘤細胞在soft agar中的生長。但其抑制的途徑為何，是否和cGMP、 PKG、 ZAK、 CREB1、β-Catenin protein有關，仍須進一步的研究。

Objective: Human cancer cells exhibit growth, migration and invasion in soft agar to represent the tumor characteristics. Sildenafil belongs to the Phosphodiesterase 5 (PDE5) inhibitors, which increases the intracellular cGMP concentration and raise the expression of protein kinase G (PKG). Previous studies have shown that Sildenafil inhibits cancer. Herein, this study aimed to find the effect of Sildenafil on the growth of human oral cancer cells in soft agar, and from which try to find out the potential mechanisms. Methods: The oral cancer cell line, KB cell, was grown on soft agar and the colonies were observed. Sildenafil or Tadalafil was conducted at different concentrations and calculated the number of tumor colonies to compare the inhibitory effect in tumor growth. In addition, the effect of both drugs on cyclooxygenase 2 (Cox2) was analyzed by Western blot. Result: It was found that one oral cancer cell in soft agar could grow into a colony. At the concentration of 5 μg / ml and 10 μg / ml, Sildenafil significantly decreased the number of KB cells in a dose-dependent manner. It also reduced the expression of Cox2 at lower concentration. In contrast, Tadalafil cannot alter the colony formation. Conclusion: Sildenafil inhibits the growth of KB tumor cells in soft agar. However, the relationships between Sildenafil and the regulatory molecules, cGMP, PKG, ZAK, CREB1, or β-Catenin protein still need to be further elucidated.