Transformation-defective adenovirus 5 E1A mutants exhibit antioncogenic properties in human BLM melanoma cells.
Adenoviral E1 A proteins exhibit a strong tumor-suppressive activity in human tumor cells. However, E1 A is capable of transforming rodent and human cells in cooperation with other oncoproteins, such as activated RAS. Thus, the therapeutic use of wild-type E1A harbors the principal risk of enhancing tumor malignancy. This prompted us to construct E1A 13S cDNA-derived mutants that were unable to transform baby mouse kidney cells in cooperation with E1B and to test their tumor-suppressive activity in BLM human melanoma cells. Anchorage-independent growth in soft agar was reduced for those cell lines expressing the E1AdelCR2 mutant, which lacks the entire conserved region 2 (CR2) sequences, or for cells expressing the E1AcR3Ex2 mutant, which contains CR3 plus exon 2 sequences. In contrast, cell lines expressing the entire E1A wild-type (E1AWT) or only the exon 2 sequences (E1AEx2) grew like the parental BLM cells. Moreover, inoculation of nude mice with BLM cells or cells expressing E1AEx2 revealed large tumors after 2 weeks. In contrast, tumors derived from E1AdelCR2- or E1ACR3Ex2-expressing cells exhibited a substantial delay in tumor growth accompanied by a loss of E1A expression in the outgrown tumors. Cell lines expressing E1AWT showed an intermediate phenotype. Thus, expression of CR3 plus exon 2 sequences is sufficient to enhance both the antioncogenic properties and the therapeutic safety of E1A in our system.
Institute for Molecular Biology (Cancer Research), University of Essen Medical School, Germany.
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A
Dickopp
H
H
Esche
G
G
Swart
S
S
Seeber
H C
HC
Kirch
B
B
Opalka
D000256:Adenoviridae / Q000235:genetics*; D017500:Adenovirus E1A Proteins / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D004273:DNA, Neoplasm / Q000032:analysis; D003673:Defective Viruses; D016147:Genes, Tumor Suppressor; D015316:Genetic Therapy; D006801:Humans; D008546:Melanoma, Experimental / Q000378:metabolism / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D016133:Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
D017500:Adenovirus E1A Proteins; D004273:DNA, Neoplasm