Wong Matthew H, Xue Aiqun, Baxter Robert C, Pavlakis Nick, Smith Ross C
Cancer Surgery Research Laboratory, Kolling Institute of Medical Research, University of Sydney, Sydney, NSW, Australia; Department of Medical Oncology, Gosford Hospital, Sydney, NSW, Australia.
Cancer Surgery Research Laboratory, Kolling Institute of Medical Research, University of Sydney, Sydney, NSW, Australia.
Neoplasia. 2016 Jul;18(7):425-35. doi: 10.1016/j.neo.2016.06.001.
Extensive cross talk exists between PI3K/Akt/mTOR and mitogen-activated protein kinase (MAPK) pathways, and both are upregulated in pancreatic ductal adenocarcinoma (PDAC). Our previous study suggested that epidermal growth factor receptor inhibitor erlotinib which acts upstream of these pathways acts synergistically with PI3K inhibitors in PDAC. Horizontal combined blockade upstream and downstream of these two pathways is therefore explored.
Erlotinib paired with PI3K inhibitor (BYL719) was tested against erlotinib plus dual PI3K/mTOR inhibitor BEZ-235, and MEK inhibitor (PD98059) plus BEZ235, on five primary PDAC cell lines and on two pairs of parent and erlotinib-resistant (ER) cell lines. A range of in vitro assays including cell proliferation, Western blotting, migration, clonogenic, cell cycle, and apopotic assays was used to test for the efficacy of combined blockade.
Dual downstream blockade of the MAPK and PAM pathways was more effective in attenuating downstream molecular signals. Synergy was demonstrated for erlotinib and BEZ235 and for PD-98059 and BEZ-235. This resulted in a trend of increased growth cell cycle arrest, apoptosis, cell proliferation, and colony and migration suppression. This combination showed more efficacy in cell lines with acquired resistance to erlotinib.
The additional mTOR blockade provided by BEZ235 in combined blockade resulted in increased anticancer effect. The hypersensitivity of ER cell lines to additional mTOR blockade suggested PAM pathway oncogenic dependence via mTOR. Dual downstream combined blockade of MAPK and PAM pathways with MEK and PI3K/mTOR inhibitor appeared most effective and represents an attractive therapeutic strategy against pancreatic cancer and its associated drug resistance.
PI3K/Akt/mTOR和丝裂原活化蛋白激酶（MAPK）通路之间存在广泛的相互作用，且二者在胰腺导管腺癌（PDAC）中均上调。我们之前的研究表明，作用于这些通路上游的表皮生长因子受体抑制剂厄洛替尼在PDAC中与PI3K抑制剂具有协同作用。因此，本研究探索了对这两条通路的上下游进行横向联合阻断。
在五种原发性PDAC细胞系以及两对亲本和厄洛替尼耐药（ER）细胞系中，对厄洛替尼与PI3K抑制剂（BYL719）联合用药、厄洛替尼与双PI3K/mTOR抑制剂BEZ - 235联合用药以及MEK抑制剂（PD98059）与BEZ235联合用药进行了测试。采用一系列体外试验，包括细胞增殖、蛋白质印迹法、迁移、克隆形成、细胞周期和凋亡试验，来检测联合阻断的疗效。
对MAPK和PAM通路的双重下游阻断在减弱下游分子信号方面更有效。厄洛替尼与BEZ235以及PD - 98059与BEZ - 235之间显示出协同作用。这导致了生长细胞周期停滞、凋亡、细胞增殖以及集落和迁移抑制增加的趋势。这种联合用药在对厄洛替尼获得性耐药的细胞系中显示出更高的疗效。
在联合阻断中，BEZ235提供的额外mTOR阻断增强了抗癌效果。ER细胞系对额外mTOR阻断的超敏反应表明PAM通路通过mTOR产生致癌依赖性。用MEK和PI3K/mTOR抑制剂对MAPK和PAM通路进行双重下游联合阻断似乎最为有效，代表了一种针对胰腺癌及其相关耐药性的有吸引力的治疗策略。
