Prolonged sulforaphane treatment does not enhance tumorigenesis in oncogenic K-ras and xenograft mouse models of lung cancer.

Authors:
Ponvijay Kombairaju
Ponvijay Kombairaju
Bloomberg School of Public Health
United States
Jinfang Ma
Jinfang Ma
Photosynthesis Research Center
Rajesh K Thimmulappa
Rajesh K Thimmulappa
Bloomberg School of Public Health
Baltimore | United States
Edward Gabrielson
Edward Gabrielson
Johns Hopkins University School of Medicine
Baltimore | United States
Anju Singh
Anju Singh
Johns Hopkins University
United States
Shyam Biswal
Shyam Biswal
Johns Hopkins Bloomberg School of Public Health
Baltimore | United States

J Carcinog 2012 13;11. Epub 2012 Jul 13.

Department of Environmental Health Sciences, Bloomberg School of Public Health, Baltimore, Maryland.

Background: Sulforaphane (SFN), an activator of nuclear factor erythroid-2 related factor 2 (Nrf2), is a promising chemopreventive agent which is undergoing clinical trial for several diseases. Studies have indicated that there is gain of Nrf2 function in lung cancer and other solid tumors because of mutations in the inhibitor Kelch-like ECH-associated protein 1 (Keap1). More recently, several oncogenes have been shown to activate Nrf2 signaling as the main prosurvival pathway mediating ROS detoxification, senescence evasion, and neoplastic transformation. Thus, it is important to determine if there is any risk of enhanced lung tumorigenesis associated with prolonged administration of SFN using mouse models of cancer.

Materials And Methods: We evaluated the effect of prolonged SFN treatment on oncogenic K-ras (K-ras(LSL-G12D))-driven lung tumorigenesis. One week post mutant-K-ras expression, mice were treated with SFN (0.5 mg, 5 d/wk) for 3 months by means of a nebulizer. Fourteen weeks after mutant K-ras expression (K-ras(LSL-G12D)), mice were sacrificed, and lung sections were screened for neoplastic foci. Expression of Nrf2-dependent genes was measured using real time RT-PCR. We also determined the effect of prolonged SFN treatment on the growth of preclinical xenograft models using human A549 (with mutant K-ras and Keap1 allele) and H1975 [with mutant epidermal growth factor receptor (EGFR) allele] nonsmall cell lung cancer cells.

Results: Systemic SFN administration did not promote the growth of K-ras(LSL-G12D)-induced lung tumors and had no significant effect on the growth of A549 and H1975 established tumor xenografts in nude mice. Interestingly, localized delivery of SFN significantly attenuated the growth of A549 tumors in nude mice, suggesting an Nrf2-independent antitumorigenic activity of SFN.

Conclusions: Our results demonstrate that prolonged SFN treatment does not promote lung tumorigenesis in various mouse models of lung cancer.

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http://dx.doi.org/10.4103/1477-3163.98459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3424666PMC
August 2012
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