buparlisib and Stomach-Neoplasms

Dual blockade of phosphoinositide 3-kinase (PI3K) and poly(ADP-ribose) polymerase (PARP) has been revealed to be an effective treatment strategy for breast, ovarian and prostate cancer. However, the efficacy of this combination for the treatment of gastric cancer, and potential predictive therapeutic biomarkers remain unclear. Recent evidence suggests that the deficiency of AT-rich interactive domain containing protein 1A (ARID1A), which is a crucial chromatin remodeling gene, sensitizes tumor cells to PI3K and PARP inhibitors. Herein, we evaluated the therapeutic role of the combined treatment of PI3K inhibitor BKM120 and PARP inhibitor olaparib on gastric cancer cells, and explored ARID1A as a predictive biomarker. The results demonstrated that combined treatment with PI3K and PARP inhibitors effectively inhibited proliferation detected by MTS and clonogenic assay, invasion and migration by Transwell assay, of gastric cancer cells with ARID1A deficiency. Mechanistically, dual blockade of PI3K and PARP in ARID1A-depleted gastric cancer cells significantly increased apoptosis detected by flow cytometry, and induced DNA damage by immunofluorescent staining. Taken together, these data suggest that the combined treatment with PI3K inhibitor BKM120 and PARP inhibitor olaparib may be a promising therapeutic regimen for the treatment of gastric cancer, and ARID1A deficiency could serve as a potential predictive therapeutic biomarker.

Topics: Aminopyridines; Biomarkers, Tumor; Cell Line, Tumor; Chromatin Assembly and Disassembly; DNA Damage; DNA-Binding Proteins; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Morpholines; Nuclear Proteins; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Stomach Neoplasms; Transcription Factors

Aberrations of Phosphoinositide 3-kinase (PI3K)/AKT signaling are frequently observed in many types of cancer, promoting its emergence as a promising target for cancer treatment. PI3K can become activated by various pathways, one of which includes RAS. RAS can not only directly activate the PI3K/AKT pathway via binding to p110 of PI3K, but also regulates mTOR via ERK or RSK independently of the PI3K/AKT pathway. Thus, actively mutated RAS can constitutively activate PI3K signaling. Additionally, in RAS tumorigenic transformation, signal transducer and activator of transcription 3 (STAT3) has been known also to be required. In this study, we examined the efficacy of NVP-BKM120, a pan-class I PI3K inhibitor in human gastric cancer cells and hypothesized that the combined inhibition of PI3K and STAT3 would be synergistic in KRAS mutant gastric cancer cells. NVP-BKM120 demonstrated anti-proliferative activity in 11 human gastric cancer cell lines by decreasing mTOR downstream signaling. But NVP-BKM120 treatment increased p-AKT by subsequent abrogation of feedback inhibition by stabilizing insulin receptor substrate-1. In KRAS mutant gastric cancer cells, either p-ERK or p-STAT3 was also increased upon treatment of NVP-BKM120. The synergistic efficacy study demonstrated that dual PI3K and STAT3 blockade showed a synergism in cells harboring mutated KRAS by inducing apoptosis. The synergistic effect was not seen in KRAS wild-type cells. Together, these findings suggest for the first time that the dual inhibition of PI3K and STAT3 signaling may be an effective therapeutic strategy for KRAS mutant gastric cancer patients.

Topics: Aminopyridines; Cell Growth Processes; Cell Line, Tumor; Drug Synergism; Enzyme Inhibitors; Genes, ras; Humans; Morpholines; Mutation; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction; STAT3 Transcription Factor; Stomach Neoplasms; Tyrphostins