Expression of Nuclear Factor Erythroid 2 Protein in Malignant Cutaneous Tumors

Background Reactive oxygen species (ROS) damages cell molecules, and modifies cell signaling. The nuclear factor E2-related factor (Nrf2) is a critical transcription regulator, which protects cells against oxidative damage. Nrf2 expression is increased in a large number of cancers. However, little information has been reported regarding the expression of Nrf2 in skin cancers. Hence, we explored the expression of Nrf2 protein in skin cancers.

Methods The Nrf2 protein expression in 24 specimens, including 6 malignant melanomas (MM), 6 squamous cell carcinomas (SCC), 6 basal cell carcinomas (BCC), and 6 normal skin tissues, was evaluated by western blotting. Immunohistochemical staining was performed. The expression of Kelch-like ECH-associated protein 1 (Keap1), the key regulator of Nrf2, was also analyzed by western blotting.

Results Small interfering RNA transfection to the melanoma cell line G361 confirmed that an approximately 66 kDa band was the true Nrf2 band. The western blot revealed that the Nrf2 protein was definitely expressed in normal skin tissues, but the Nrf2 expression was decreased in MM, SCC, and BCC. Immunohistochemical examination showed that expression of Nrf2 was decreased in all skin cancer tissues compared to the normal skin tissues. Keap1 was not expressed in all malignant skin tumors and normal skin tissues by western blot.

Conclusions ROS was increased in various types of cancers which proteins were highly expressed or underexpressed. This study demonstrated that the expression of Nrf2 protein was down-regulated in human malignant skin tumors. We suggest that decreased expression of Nrf2 is related to skin cancers.

Keywords

NF-E2-related factor 2 - Reactive oxygen species - Skin neoplasms

This work was supported by the Soonchunhyang University Research Fund.

Publication History

Received: 03 January 2014

Accepted: 12 February 2014

Article published online:
05 May 2022

• References

• 1 Bickers DR, Athar M. Oxidative stress in the pathogenesis of skin disease. J Invest Dermatol 2006; 126: 2565-2575
• 2 Breimer LH. Molecular mechanisms of oxygen radical carcinogenesis and mutagenesis: the role of DNA base damage. Mol Carcinog 1990; 3: 188-197
• 3 Rosen GM, Pou S, Ramos CL. et al. Free radicals and phagocytic cells. FASEB J 1995; 9: 200-209
• 4 Marrot L, Jones C, Perez P. et al. The significance of Nrf2 pathway in (photo)-oxidative stress response in melanocytes and keratinocytes of the human epidermis. Pigment Cell Melanoma Res 2008; 21: 79-88
• 5 Bryan HK, Olayanju A, Goldring CE. et al. The Nrf2 cell defence pathway: Keap1-dependent and -independent mechanisms of regulation. Biochem Pharmacol 2013; 85: 705-717
• 6 Kobayashi M, Itoh K, Suzuki T. et al. Identification of the interactive interface and phylogenic conservation of the Nrf2-Keap1 system. Genes Cells 2002; 7: 807-820
• 7 Arlt A, Bauer I, Schafmayer C. et al. Increased proteasome subunit protein expression and proteasome activity in colon cancer relate to an enhanced activation of nuclear factor E2-related factor 2 (Nrf2). Oncogene 2009; 28: 3983-3996
• 8 Stacy DR, Ely K, Massion PP. et al. Increased expression of nuclear factor E2 p45-related factor 2 (NRF2) in head and neck squamous cell carcinomas. Head Neck 2006; 28: 813-818
• 9 Kim YR, Oh JE, Kim MS. et al. Oncogenic NRF2 mutations in squamous cell carcinomas of oesophagus and skin. J Pathol 2010; 220: 446-451
• 10 Motohashi H, Yamamoto M. Nrf2-Keap1 defines a physiologically important stress response mechanism. Trends Mol Med 2004; 10: 549-557
• 11 Wakabayashi N, Dinkova-Kostova AT, Holtzclaw WD. et al. Protection against electrophile and oxidant stress by induction of the phase 2 response: fate of cysteines of the Keap1 sensor modified by inducers. Proc Natl Acad Sci U S A 2004; 101: 2040-2045
• 12 Singh A, Misra V, Thimmulappa RK. et al. Dysfunctional KEAP1-NRF2 interaction in non-small-cell lung cancer. PLoS Med 2006; 3: e420
• 13 Shibata T, Kokubu A, Gotoh M. et al. Genetic alteration of Keap1 confers constitutive Nrf2 activation and resistance to chemotherapy in gallbladder cancer. Gastroenterology 2008; 135: 1358-1368.e1-4
• 14 Ikeda H, Nishi S, Sakai M. Transcription factor Nrf2/MafK regulates rat placental glutathione S-transferase gene during hepatocarcinogenesis. Biochem J 2004; 380: 515-521
• 15 Wang HB, Zhou CJ, Song SZ. et al. Evaluation of Nrf2 and IGF-1 expression in benign, premalignant and malignant gastric lesions. Pathol Res Pract 2011; 207: 169-173
• 16 Nioi P, Nguyen T. A mutation of Keap1 found in breast cancer impairs its ability to repress Nrf2 activity. Biochem Biophys Res Commun 2007; 362: 816-821
• 17 Jiang T, Chen N, Zhao F. et al. High levels of Nrf2 determine chemoresistance in type II endometrial cancer. Cancer Res 2010; 70: 5486-5496
• 18 Pi J, Diwan BA, Sun Y. et al. Arsenic-induced malignant transformation of human keratinocytes: involvement of Nrf2. Free Radic Biol Med 2008; 45: 651-658
• 19 Kwak MK, Wakabayashi N, Itoh K. et al. Modulation of gene expression by cancer chemopreventive dithiolethiones through the Keap1-Nrf2 pathway. Identification of novel gene clusters for cell survival. J Biol Chem 2003; 278: 8135-8145
• 20 Xu C, Huang MT, Shen G. et al. Inhibition of 7,12-dimethylbenz(a)anthracene-induced skin tumorigenesis in C57 BL/6 mice by sulforaphane is mediated by nuclear factor E2-related factor 2. Cancer Res 2006; 66: 8293-8296
• 21 Dairkee SH, Nicolau M, Sayeed A. et al. Oxidative stress pathways highlighted in tumor cell immortalization: association with breast cancer outcome. Oncogene 2007; 26: 6269-6279
• 22 Reuter S, Gupta SC, Chaturvedi MM. et al. Oxidative stress, inflammation, and cancer: how are they linked?. Free Radic Biol Med 2010; 49: 1603-1616
• 23 Li W, Kong AN. Molecular mechanisms of Nrf2-mediated antioxidant response. Mol Carcinog 2009; 48: 91-104