Abstract
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.
Highlights
To discover factors that modulate p53 pathways, we attempted to identify RNAi sequences that enhance p53induced apoptosis
These results indicated that specific shRNAs evoked the apoptotic response following p53 transduction or functional restoration of p53 in cancer cells resistant to p53-induced apoptosis, suggesting that the combination of p53 restoration and treatment with specific shRNAs may be an effective cancer therapy
Genome-wide shRNA screening in p53-resistant cancer cells determine the expression levels of each shRNA; as a reference, the shRNA population in each cell line infected with adenovirus expressing LacZ was analyzed
Summary
To discover factors that modulate p53 pathways, we attempted to identify RNAi sequences that enhance p53induced apoptosis. We screened a genomewide lentiviral shRNA library in cancer cells resistant to p53-related apoptosis. We identified specific shRNAs that were significantly decreased in p53-infected cells but not in control cells. These results indicated that specific shRNAs evoked the apoptotic response following p53 transduction or functional restoration of p53 in cancer cells resistant to p53-induced apoptosis, suggesting that the combination of p53 restoration and treatment with specific shRNAs may be an effective cancer therapy
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