Meeting: 2017 AACR Annual Meeting
Title: In vivo pooled shRNA library identifies KPNB1 as a new drug target for epithelial ovarian cancer.
Epithelial ovarian cancer (EOC) is a most lethal cancer in gynecology, of which cure rate is 30%. To seek its new therapeutic targets, we performed in vivo loss of function screen.
Human EOC cell line, SKOV3, was transduced with pooled druggable shRNA library containing 42450 shRNAs targeting 7490 genes. Transduced cells were intraperitoneally injected into 12 female nude mice and monitored for PC tumor formation. Genomic DNA of 12 biggest PC tumors were sequenced to identify shRNAs depleted in these tumors.
Ten potential drug targets were identified, including 2 known oncogenes, ERBB2 and RAF1. Second highest ranked gene, KPNB1, is known as a nuclear transporter. KPNB1 inhibition significantly decreased and overexpression increased in vitro cell proliferation in multiple EOC cell lines. KPNB1 inhibition caused multi-phase cell cycle delay at both of G1/S and G2/M transition via elevation of p21 and p27 and induced apoptosis. KPNB1 inhibition significantly decreased in vivo tumor formation through the same mechanism as in vitro, because more cleaved PARP and less Ki67 positive cells were found in KPNB1 knockdown tumors via immunochemical staining. We found a positive correlation between KPNB1 mRNA levels and poor survival of EOC patients, suggesting the oncogenic role of KPNB1 in human EOC. Comprehensive mass spectrometric study identified that KPNB1 positively regulated several members of anaphase promoting complex/cyclosome. Lastly, we found that ivermectin, a well-known anti-parasitic drug, exerted an anti-proliferative effect on EOC cell lines via KPNB1 inhibition, and its combination with paclitaxel synergistically suppressed cell proliferation in vitro and inhibited tumor formation in vivo.
In vivo pooled shRNA library screen identified KPNB1 as a new drug target for EOC. Ivermectin can be a new therapeutics for EOC especially combined with paclitaxel.