水解磷酸脂於前列腺癌細胞引發過氧化物生成機制之研究

Abstract

前列腺癌是男性最常罹患的癌症之一,其淋巴轉移以及荷爾蒙治療後的癌症復發 是兩個治療前列腺癌的嚴重問題,PC-3 是一種適合用來研究後期前列腺癌細胞行為的癌細胞株。水解磷酸脂 (LPA) 是一種能調控多種細胞行為的傳訊脂質,已知會促進癌細胞的生長、移動以及附著的能力。本實驗室先前於 PC-3 的研究指出, LPA 可以藉由引發過氧化物 (ROS) 生成去提高淋巴管新生因子 (VEGF-C) 的表現。 本研究以流式細胞儀以及 ROS 的染劑進行行其相對量測定,結果顯示 LPA 能在十分鐘內引發 ROS 生成,這個現象經由 NADPH oxidase (Nox) 的酵素系統所調控。利用 RNA 干擾的實驗我們證明了水解磷酸脂受器 1 和 3 (LPA1 及 LPA3) 參與這條 LPA 所調控的分子路徑。由抑制劑與 RNA 干擾的實驗也證明了磷脂酶 C (PLC) 和蛋白質激酶 C (PKC) 同樣參與 LPA 引發的 ROS 生成,而並不是經由環氧化酶 2 與內皮生長因子受器的相關傳訊路徑。於本研究中,我們發現 LPA 可以引發 PC-3 細胞中 ROS 的生成,且有 PLC/PKC/Nox 等酵素參與此路徑。

Prostate cancer is one of the most frequently diagnosed cancers in males, and PC-3 is a cell model popularly used for investigating the behavior of late stage prostate cancer. Lysophosphatidic acid (LPA) is a lysophospholipid that mediates multiple behaviors in cancer cells, such as proliferation, migration and adhesion. We have previously demonstrated that LPA enhances vascular endothelial growth factor (VEGF)-C expression in PC-3 cells by activating the generation of reactive oxygen species (ROS), which is known to be an important mediator in cancer progression. Using flow cytometry, we showed that LPA triggers ROS generation within 10 min and that the generated ROS can be suppressed by pretreatment with the NADPH oxidase (Nox) inhibitor diphenylene iodonium. In addition, transfection with LPA1 and LPA3 siRNA efficiently blocked LPA-induced ROS production, suggesting that both receptors are involved in this pathway. Using specific inhibitors and siRNA, phospholipase C (PLC) and protein kinase C (PKC) were also suggested to participate in LPA-induced ROS generation, but COX-2 and EGFR are not involved in this pathway. Overall, we demonstrated that LPA induces ROS generation in PC-3 prostate cancer cells and this is mediated through the PLC/PKC/Nox pathway.