Alao John P, Michlikova Sona, Dinér Peter, Grøtli Morten, Sunnerhagen Per
Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-405 30 Göteborg, Sweden.
BMC Cancer. 2014 Nov 20;14:853. doi: 10.1186/1471-2407-14-853.
The RET tyrosine kinase receptor has emerged as a target in thyroid and endocrine resistant breast cancer. We previously reported the synthesis of kinase inhibitors with potent activity against RET. Herein, we have further investigated the effect of the lead compound SPP86 on RET mediated signaling and proliferation. Based on these observations, we hypothesized that SPP86 may be useful for studying the cellular activity of RET.
We compared the effects of SPP86 on RET-induced signaling and proliferation in thyroid cancer cell lines expressing RET-PTC1 (TPC1), or the activating mutations BRAFV600E (8505C) and RASG13R (C643). The effect of SPP86 on RET- induced phosphatidylinositide 3-kinases (PI3K)/Akt and MAPK pathway signaling and cell proliferation in MCF7 breast cancer cells was also investigated.
SPP86 inhibited MAPK signaling and proliferation in RET/PTC1 expressing TPC1 but not 8505C or C643 cells. In TPC1 cells, the inhibition of RET phosphorylation required co-exposure to SPP86 and the focal adhesion kinase (FAK) inhibitor PF573228. In MCF7 cells, SPP86 inhibited RET- induced phosphatidylinositide 3-kinases (PI3K)/Akt and MAPK signaling and estrogen receptorα (ERα) phosphorylation, and inhibited proliferation to a similar degree as tamoxifen. Interestingly, SPP86 and PF573228 inhibited RET/PTC1 and GDNF- RET induced activation of Akt and MAPK signaling to a similar degree.
SPP86 selectively inhibits RET downstream signaling in RET/PTC1 but not BRAFV600E or RASG13R expressing cells, indicating that downstream kinases were not affected. SPP86 also inhibited RET signaling in MCF7 breast cancer cells. Additionally, RET- FAK crosstalk may play a key role in facilitating PTC1/RET and GDNF- RET induced activation of Akt and MAPK signaling in TPC1 and MCF7 cells.
RET酪氨酸激酶受体已成为甲状腺癌和内分泌抵抗性乳腺癌的一个靶点。我们之前报道了具有强效抗RET活性的激酶抑制剂的合成。在此，我们进一步研究了先导化合物SPP86对RET介导的信号传导和增殖的影响。基于这些观察结果，我们推测SPP86可能有助于研究RET的细胞活性。
我们比较了SPP86对表达RET-PTC1（TPC1）、激活突变BRAFV600E（8505C）和RASG13R（C643）的甲状腺癌细胞系中RET诱导的信号传导和增殖的影响。还研究了SPP86对MCF7乳腺癌细胞中RET诱导的磷脂酰肌醇3激酶（PI3K）/Akt和MAPK信号通路信号传导及细胞增殖的影响。
SPP86抑制表达RET/PTC1的TPC1细胞中的MAPK信号传导和增殖，但不抑制8505C或C643细胞。在TPC1细胞中，抑制RET磷酸化需要同时暴露于SPP86和粘着斑激酶（FAK）抑制剂PF573228。在MCF7细胞中，SPP86抑制RET诱导的磷脂酰肌醇3激酶（PI3K）/Akt和MAPK信号传导以及雌激素受体α（ERα）磷酸化，并抑制增殖，其程度与他莫昔芬相似。有趣的是，SPP86和PF573228对RET/PTC1和GDNF-RET诱导的Akt和MAPK信号激活的抑制程度相似。
SPP86选择性抑制表达RET/PTC1的细胞中的RET下游信号传导，但不抑制表达BRAFV600E或RASG13R的细胞，表明下游激酶未受影响。SPP86还抑制MCF7乳腺癌细胞中的RET信号传导。此外，RET-FAK相互作用可能在促进TPC1和MCF7细胞中PTC1/RET和GDNF-RET诱导的Akt和MAPK信号激活中起关键作用。
