Comprehensive Two- and Three-Dimensional RNAi Screening Identifies PI3K Inhibition as a Complement to MEK Inhibitor AS703026 for Combination Treatment of Triple-Negative Breast Cancer

Abstract

Triple-negative breast cancer (TNBC) is a major cause of death among breast cancer patients that results from intrinsic and acquired resistance to systemic chemotherapies. To identify novel targets for effective treatment of TNBC through combination strategies with MEK inhibitor (AS703026), we used a novel method of combining high-throughput two- and three-dimensional (2D and 3D) RNAi screening. TNBC cells were transfected with a kinome siRNA library comprising siRNA targeting 790 kinases under both 2D and 3D culture conditions with or without AS703026. Molecule activity predictor analysis revealed the PI3K pathway as the major target pathway in our RNAi combination studies in TNBC. We found that PI3K inhibitor SAR245409 (also called XL765) combined with AS703026 synergistically inhibited proliferation compared with either drug alone (P < 0.001). Reduced in vitro colony formation (P < 0.001) and migration and invasion ability were also observed with the combination treatment (P<0.01). Our data suggest that SAR245409 combined with AS703026 may be effective in patients with TNBC. We conclude that a novel powerful high-throughput RNAi assays were able to identify anti-cancer drugs as single or combinational agents. Integrated and multi-system RNAi screening methods can complement difference between in vitro and in vivo culture conditions, and enriches targets that are close to the in vivo condition.

Molecular mechanism of triple‑negative breast cancer‑associated BRCA1 and the identification of signaling pathways

“…It was observed that EGFR was closely associated with the proliferation, invasion and vascular formation of cancer, and it was markedly overexpressed in basal-like TNBC, which was significantly negatively correlated with clinical prognosis (14,15). MAPK signaling pathways regulate tumor proliferation and survival studies have demonstrated that MAPK was abnormally activated in the occurrence and development of TNBC, which may provide TNBC cells with the ability to proliferate and resist apoptosis (16)(17)(18). The PI3K/AKT/mTOR signaling pathway controls the proliferation, metabolism, survival and movement of cancer and has frequent communication with the MAPK signaling pathway (19)(20)(21)(22).…”

High-throughput RNAi screen for essential genes and drug synergistic combinations in colorectal cancer

“…Several recent studies have successfully utilised high-throughput RNAi screening for profiling the essential gene landscape, and the identification of novel drug targets for cancer therapy 11–14 . Further, both chemical and genomic screens for synthetic lethal combinations have successfully identified targetable cancer-specific sensitivities 8 , 15–19 . However, it is important to note that in order to properly address the genomic heterogeneity of cancer, multiple cell lines are required.…”

Clinically relevant inflammatory breast cancer patient-derived xenograft–derived ex vivo model for evaluation of tumor-specific therapies

“…This failure is often due to the fact that primary tumor cells grown on 2-dimensional monolayer cultures do not accurately mimic cells in the tumor microenvironment [ 37 ]. Our group [ 71 ] and others [ 35 , 37 , 72 – 73 ] have identified clinically relevant targets for drug development utilizing 3D cell culture models. However, even 3D cell culture models have limitations as they can still fail to capture the heterogeneity associated with the tumor’s microenvironment.…”