Array-based genome-wide RNAi screening to identify shRNAs that enhance p53-related apoptosis in human cancer cells
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Masashi Idogawa1,*, Tomoko Ohashi1,*, Jun Sugisaka1, Yasushi Sasaki1, Hiromu Suzuki2 and Takashi Tokino1
1 Department of Medical Genome Sciences, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan
2 Department of Molecular Biology, Sapporo Medical University School of Medicine, Sapporo, Japan
* These authors contributed equally to this work
Takashi Tokino, email:
Keywords: p53; shRNA library; apoptosis; PRIMA-1
Received: April 30, 2014 Accepted: July 26, 2014 Published: July 27, 2014
p53 transduction is a potentially effective cancer therapy but does not result in a good therapeutic response in all human cancers due to resistance to apoptosis. To discover factors that overcome resistance to p53-induced apoptosis, we attempted to identify RNAi sequences that enhance p53-induced apoptosis. We screened a genome-wide lentiviral shRNA library in liver cancer Huh-7 and pancreatic cancer Panc-1 cells, both of which resist p53-induced apoptosis. After the infection of adenovirus expressing p53 or LacZ as a control, shRNA-treated populations were analyzed by microarray. We identified shRNAs that were significantly decreased in p53-infected cells compared with control cells. Among these shRNAs, shRNA-58335 was markedly decreased in both cancer cell lines tested. shRNA-58335 enhanced p53-related apoptosis in vitro and augmented the inhibitory effect of adenoviral p53 transduction on tumor growth in vivo. Furthermore, the enhanced apoptotic response by shRNA-58335 was also confirmed by treatment with PRIMA-1, which reactivates mutant p53, instead of adenoviral p53 transduction. We found that shRNA-58335 evokes the apoptotic response following p53 transduction or functional restoration of p53 with a small molecule drug in cancer cells resistant to p53-induced apoptosis. The combination of p53 restoration and RNAi-based drugs is expected to be a promising novel cancer therapy.
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