Increased gene copy number of the transcription factor E2F1 in malignant melanoma.
Translocations and unique chromosome break points in melanoma will aid in the identification of the genes that are important in the neoplastic process. We have previously shown a unique translocation in malignant melanoma cells der(12)t(12;20). The transcription factor E2F1 maps to 20q11. Increased expression of E2F has been associated with the autonomous growth of melanoma cells, however, the molecular basis has not yet been elucidated. To this end, we investigated E2F1 gene copy number and structure in human melanoma cell lines and metastatic melanoma cases. Fluorescent in situ hybridization (FISH) analysis using a specific E2F1 probe indicated increased E2F1 gene copies in melanoma cell lines compared to normal melanocytes. We also observed increased copies of the E2F1 gene in lymph node metastases of melanoma. In addition, Western blot analysis demonstrated increased E2F1 protein levels in 8 out of 9 melanoma cell lines relative to normal melanocytes. Inhibition of E2F1 expression with RNAi also reduced melanoma cell growth. Our results suggest that the release of E2F activity by elevated E2F1 gene copy numbers may play a functional role in melanoma growth.
Department of Pathology, College of Medicine, Arizona Cancer Center, University of Arizona, Tucson, Arizona 87515, USA. mnelson@azcc.arizona.edu
Mark A
MA
Nelson
Steven H
SH
Reynolds
Uma N M
UN
Rao
Anne-Christine
AC
Goulet
Yongmei
Y
Feng
Anthony
A
Beas
Barbara
B
Honchak
Jim
J
Averill
David T
DT
Lowry
Jamie R
JR
Senft
Amy M
AM
Jefferson
Robert C
RC
Johnson
Linda M
LM
Sargent
D015153:Blotting, Western; D045744:Cell Line, Tumor; D002881:Chromosomes, Human, Pair 12; D050687:E2F1 Transcription Factor / Q000235:genetics* / Q000378:metabolism*; D020022:Genetic Predisposition to Disease; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008207:Lymphatic Metastasis; D008544:Melanocytes / Q000378:metabolism; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D034622:RNA Interference; D014178:Translocation, Genetic
D050687:E2F1 Transcription Factor