The hypothesis to be tested is that reactive oxygen species (ROS) mediate skin tumor malignant progression in part through altered activities of certain transcription factors via Mitogen Activated Protein (MAP) kinase signal transduction pathways. It is proposed that modulation of antioxidant defense systems during skin tumor malignant progression plays a functional role by leading to elevated ROS. We have developed an in vitro model to study molecular mechanisms of tumor progression. Using repeated treatments with ionizing radiation or N-methyI-N'-nitro-N-nitrosoguanidine (MNNG), we malignantly progressed a papilloma cell line, 308 cells. These cells have an activated Harvey-ras gene. We have demonstrated that both radiation and MNNG malignant variants (6R90 and 6M90, respectively) showed elevated ROS levels that contribute to their proliferative capacity in vitro as well as in vivo. We have also found increased Erk-l/2 and p38 MAP kinase activities to be important components of ROS-mediated signaling. The pro-oxidant state also contributed to constitutive elevation ofAP-1, NF-KB and cAMP response element transactivation in the malignant phenotype. We have shown a reduction in several antioxidant defense mechanisms in the malignant variants including a significant reduction in catalase protein and activity. These data are the rationale for a novel mechanistic model in which an activated Harvey-ras oncogene causes through Rac 1 signaling an increase in ROS that is attenuated in benign papilloma cells by catalase activity. This attenuation is lost in malignant progression through a down-regulation in catalase expression. Through ROS mediated signaling there is enhanced activities of Erkl/2 and p38. The increase in these kinase activities in turn contributes to constitutive elevation of certain transcription factor activities, AP-1, NF-kappaB and CRE that are involved in the maintenance of the malignant phenotype.
Specific Aim 1 : to test the hypothesis that the increase in ROS in the malignant variants is due in part to activated Ha-ras signaling downstream through Rac 1 to increase ROS and also due to a decrease in the expression of the catalase gene.
Specific Aim 2 : to test the hypothesis that the decrease in catalase expression is due to alterations in the transcription of the catalase gene.
Specific Aim 3 : to test the hypothesis that activation of Erkl/2 and p38 kinases in malignant variant cells leads to activation of AP-1 and CRE cis elements.
Specific Aim 4 : to test the hypothesis that activation of AP-1, NF-kappaB and CRE play functional roles in the maintenance of the malignant phenotype. An understanding of both gene alterations and signal transduction pathways in the progression of mouse skin carcinomas can lead to new strategies for intervention including chemoprevention and treatment of human squamous carcinomas.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA040584-18A1
Application #
6579697
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Poland, Alan P
Project Start
1985-07-01
Project End
2007-12-31
Budget Start
2003-01-01
Budget End
2003-12-31
Support Year
18
Fiscal Year
2003
Total Cost
$320,423
Indirect Cost
Name
University of Arizona
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Demetriou, Manolis C; Kwei, Kevin A; Powell, Marianne B et al. (2008) Integrin A6 Cleavage in Mouse Skin Tumors. Open Cancer J 2:1-4
Zhang, Jack; Tsaprailis, George; Bowden, G Tim (2008) Nucleolin stabilizes Bcl-X L messenger RNA in response to UVA irradiation. Cancer Res 68:1046-54
Hanke, Neale T; Finch, Joanne S; Bowden, G Timothy (2008) Loss of catalase increases malignant mouse keratinocyte cell growth through activation of the stress activated JNK pathway. Mol Carcinog 47:349-60
Zhang, Jack; Bowden, G Tim (2007) Targeting Bcl-X(L) for prevention and therapy of skin cancer. Mol Carcinog 46:665-70
Finch, Joanne S; Tome, Margaret E; Kwei, Kevin A et al. (2006) Catalase reverses tumorigenicity in a malignant cell line by an epidermal growth factor receptor pathway. Free Radic Biol Med 40:863-75
Kwei, Kevin A; Finch, Joanne S; Ranger-Moore, James et al. (2006) The role of Rac1 in maintaining malignant phenotype of mouse skin tumor cells. Cancer Lett 231:326-38
Kwei, Kevin A; Finch, Joanne S; Thompson, Eric J et al. (2004) Transcriptional repression of catalase in mouse skin tumor progression. Neoplasia 6:440-8
Butts, Brent D; Kwei, Kevin A; Bowden, G Tim et al. (2003) Elevated basal reactive oxygen species and phospho-Akt in murine keratinocytes resistant to ultraviolet B-induced apoptosis. Mol Carcinog 37:149-57
Finch, S; Joseloff, E; Bowden, T (2002) JunB negatively regulates AP-1 activity and cell proliferation of malignant mouse keratinocytes. J Cancer Res Clin Oncol 128:3-10
Thompson, Eric J; MacGowan, Jacalyn; Young, Matthew R et al. (2002) A dominant negative c-jun specifically blocks okadaic acid-induced skin tumor promotion. Cancer Res 62:3044-7

Showing the most recent 10 out of 57 publications