Bessadóttir Margrét, Skúladóttir Edda Á, Gowan Sharon, Eccles Suzanne, Ögmundsdóttir Sesselja, Ogmundsdóttir Helga M
Faculty of Medicine, University of Iceland, 101 Reykjavik, Iceland; Faculty of Pharmaceutical Sciences, University of Iceland, 101 Reykjavik, Iceland.
Faculty of Medicine, University of Iceland, 101 Reykjavik, Iceland.
Phytomedicine. 2014 Oct 15;21(12):1717-24. doi: 10.1016/j.phymed.2014.08.006. Epub 2014 Sep 16.
The lichen compound (+)-protolichesterinic acid (+)-PA, isolated from Iceland moss, has anti-proliferative effects on several cancer cell lines. The chemical structure of (+)-PA is similar to a known fatty acid synthase (FASN) inhibitor C75.
To test whether the anti-proliferative activity of (+)-PA is associated with effects on FASN and HER2 (human epidermal growth factor receptor 2) and major signalling pathways. Synergism between (+)-PA and lapatinib, a HER2 active drug, was also evaluated.
Pure compound was isolated by preparative high-performance liquid chromatography (HPLC) and purity of (+)-PA analyzed by analytical HPLC. Cell viability was assessed using Crystal violet staining. FASN and HER2 expression was estimated by immunofluorescence. The Meso Scale Discovery (MSD)(®) assay was used to measure activation of ERK1/2 and AKT. Synergism was estimated by the CalcuSyn software.
Treatment with (+)-PA increased FASN expression in SK-BR-3 cells, which overexpress FASN and HER2, implying a compensatory response to inhibition of FASN activity. HER2 expression was decreased suggesting secondary downregulation. ERK1/2 and AKT signalling pathways were inhibited, probably due to reduced levels of HER2. No effects were observed in T-47D cells. Synergism between (+)-PA and lapatinib was observed in the SK-BR-3 cells.
Results suggest that the primary effect of (+)-PA is inhibition of FASN activity. Synergistic effects with lapatinib were seen only in SK-BR-3 cells, and not T-47D cells, further supporting the notion that (+)-PA acts by inhibiting FASN with secondary effects on HER2 expression and signalling. (+)-PA could therefore be a suitable agent for further testing, alone or in combination treatment against HER2-overexpressing breast cancer.
从冰岛衣中分离出的地衣化合物（+）-原地衣硬脂酸（+）-PA对多种癌细胞系具有抗增殖作用。（+）-PA的化学结构与已知的脂肪酸合酶（FASN）抑制剂C75相似。
测试（+）-PA的抗增殖活性是否与对FASN和HER2（人表皮生长因子受体2）及主要信号通路的影响有关。还评估了（+）-PA与HER2活性药物拉帕替尼之间的协同作用。
通过制备型高效液相色谱（HPLC）分离纯化合物，并用分析型HPLC分析（+）-PA的纯度。使用结晶紫染色评估细胞活力。通过免疫荧光估计FASN和HER2的表达。使用中尺度发现（MSD）（®）测定法测量ERK1/2和AKT的激活。通过CalcuSyn软件估计协同作用。
用（+）-PA处理可增加SK-BR-3细胞中FASN的表达，该细胞过表达FASN和HER2，这意味着对FASN活性抑制的一种补偿反应。HER2表达降低，提示继发性下调。ERK1/2和AKT信号通路受到抑制，可能是由于HER2水平降低。在T-47D细胞中未观察到影响。在SK-BR-3细胞中观察到（+）-PA与拉帕替尼之间的协同作用。
结果表明（+）-PA的主要作用是抑制FASN活性。仅在SK-BR-3细胞中观察到与拉帕替尼的协同作用，而在T-47D细胞中未观察到，这进一步支持了（+）-PA通过抑制FASN起作用并对HER2表达和信号传导产生继发性影响的观点。因此，（+）-PA可能是一种适合进一步测试的药物，可单独或联合用于治疗HER2过表达的乳腺癌。
