The dual PI3K/mTOR inhibitor NVP-BGT226 induces cell cycle arrest and regulates Survivin gene expression in human pancreatic cancer cell lines

The phosphatidylinositol-3-kinase (PI3K) pathway is one of the most commonly activated signaling pathways in pancreatic cancer and is a target of interest for new therapeutic approaches. NVP-BGT226 is a novel dual class PI3K/mammalian target of rapamycin (mTOR) inhibitor that has entered Phase I/II clinical trials. We analyzed the effect of NVP-BGT226 (10-100 nM) on the pancreatic cell lines Panc-1, BxPc-3, AsPC-1 and MiaPaCa-2 in regard to cell viability, induction of apoptosis, cell cycle, and expression of the antiapoptotic genes Survivin, MCL-1, BCL-2 and BCL-xL. Cell viability decreased within 24-72 h after exposure to about 50% compared to untreated control cells in a concentration- but not time-dependent manner. Cell cycle analysis revealed that NVP-BGT226 induced predominantly G0/G1 cell cycle arrest. Additionally, real-time RT-PCR and Western blot analysis showed a remarkable decrease of Survivin expression. Originally designed as a dual inhibitor, there was only a significant inhibition of p-mTOR. In summary, the dual PI3K/mTOR inhibitor NVP-BGT226 induces G0/G1 arrest and acts, at least, partially via downregulation of Survivin.