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Biochem Biophys Res Commun. 1998 Jul 30;248(3):835-40.

Defective retrovirus insertion activates c-Ha-ras protooncogene in an MNU-induced rat mammary carcinoma.

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Cancer Research Laboratory, University of California at Berkeley 94720, USA.


Endogenous retrovirus sequences are present in the genome of a wide variety of animal species. The activation of the proto-oncogenes of the ras family, particularly c-Ha-ras, by either point mutation or overexpression, has been shown to be associated with a vast number, of different cancers. here we report that the insertion of a defective retrovirus in the -1 intron of rat c-Ha-ras is responsible for the activation of the gene by over 10-fold overexpression in an MNU-induced rat mammary cancer. A portion of the 3' end of the retroviral sequence is expressed as a part of the c-Ha-ras transcript in the carcinoma tissue, indicating the direct involvement of this element in the transcription of the c-Ha-ras gene. The c-Ha-ras structural gene transcribed by the promoter of the defective retroviral element can neoplastically transform the NIH 3T3 cell line upon transfection.

[Indexed for MEDLINE]

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