Cancer Chemotherapy and Pharmacology, 2012, Vol.69(6), pp.1601-1615
Byline: Annett Mueller (1), Erika Bachmann (1), Monika Linnig (1), Katrin Khillimberger (1), Carl Christoph Schimanski (1), Peter R. Galle (1), Markus Moehler (1) Keywords: Inhibition; PI3K; Cancer cell lines; Chemotherapy; Wild type Abstract: Purpose New targeted agents like antibodies or small molecules against tyrosine and lipid kinases clearly expand the standard therapy options in oncology. However, tumour resistance is still a challenge, often induced by mutations in growth-related signalling cascades. Twenty and ten percentage of all patients with colorectal and gastric cancers, respectively, carry phosphatidyl-3-kinase (PI3K) mutations and do not respond to receptor-blocking therapies. Recently, selective kinase inhibitors have been generated, which block the PI3K signalling pathway in tumour cells. So far, their therapeutic role for the treatment of mutated versus wild-type human gastrointestinal cancers has not been clarified in detail. Methods To define the inhibitory and pro-apoptotic effects of the two PI3K inhibitors BEZ235 and BKM120 in three human colon cancer (HT-29, HCT-116 and DLD-1) and three gastric cancer (NCI-n87, AGS and MKN-45), cell lines with different PIK3CA gene mutation status were used. Firstly, viability, apoptosis and caspase assays were performed during incubation with either the inhibitors alone or combined with different cytotoxic agents. Secondly, the molecular consequences for the cell cycle and signalling pathways were analysed by defining the protein levels by FACS and Western blot analysis. Results Both the PI3K inhibitors BEZ235 and BKM120 induced a clear concentration-dependent reduction in cell viability and an increase in apoptotic cell death, with the mutated cells being more sensitive to treatment. However, single-agent BEZ235 caused a G1 arrest in tumour cells, whilst BKM120 induced a G2 shift in a half of the gastrointestinal cancer cell lines. There was a clear downregulation in the protein levels of the PI3K--AKT pathway at the concentrations of 100nM for both agents and for BEZ235 the additional inhibition of the mTOR pathway. Furthermore, BEZ235 caused synergistic induction of apoptosis when combined with irinotecan in colon cancer cell lines. Human gastric cancer cells were less sensitive to both BEZ235 and BKM120. Conclusions BEZ235 and BKM120 induced pro-apoptotic effects in all cell lines and especially with an increased response in the PI3KCA mutated cells. Our data support the clinical development of these PI3K inhibitors for patients with wild-type or mutated colon cancers. Author Affiliation: (1) First Department of Internal Medicine, University Medical Centre of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55101, Mainz, Germany Article History: Registration Date: 13/04/2012 Received Date: 02/11/2011 Accepted Date: 12/04/2012 Online Date: 29/04/2012 Article note: Electronic supplementary material The online version of this article (doi: 10.1007/s00280-012-1869-z) contains supplementary material, which is available to authorized users.
Inhibition ; PI3K ; Cancer cell lines ; Chemotherapy ; Wild type
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