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Erschienen in:
01.02.2012 | Original Article
Nrf2 knockdown by shRNA inhibits tumor growth and increases efficacy of chemotherapy in cervical cancer
Erschienen in: Cancer Chemotherapy and Pharmacology | Ausgabe 2/2012
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Purpose
NF-E2-related factor 2 (Nrf2) is a key transcription regulator for cellular response to oxidative stress in normal cells. In cancer cells, development of chemoresistance is associated with the constitutive activation of the Nrf2-mediated antioxidant defense system. Here, we investigated the role of Nrf2 in terms of cervical cancer cell proliferation and drug resistance.
Method
To investigate whether cancer cells activate the Nrf2 system, we examined 40 surgical cervical cancer samples and 12 normal control tissues. Plasmids containing Nrf2-small hairpin RNA (shRNA) or non-targeting vector-control shRNA were transfected into CaSki cells. Using Western blots and RT-PCR assays, the expression levels of Nrf2 mediated-target genes were measured in CaSki cells stably expressing Nrf2-shRNA. To evaluate how the Nrf2 knockdown affected susceptibility to chemotherapeutic drugs, MTT and flow cytometry assays were done in vitro and confirmed by a mouse xenograft model in vivo.
Results
The Nrf2-dependent defensive system was likely fully activated in cervical tumor tissues. Genetic knockdown of endogenous Nrf2 caused a global decrease in expression of Nrf2-regulated genes. This decrease in expression levels enhanced chemotherapeutic drug-induced apoptotic death in CaSki cells with a reduced cellular glutathione level. Additionally, the combination of cisplatin treatment and Nrf2 knockdown significantly suppressed tumor growth in vivo.
Conclusion
Our findings provide evidence that the inhibition of Nrf2 activity by shRNA might be a promising therapeutic strategy to enhance the efficacy of anticancer drugs and thus can be applied further during the course of chemotherapy in the treatment of cervical cancer.