Loss of Retrovirus Production in JB/RH Melanoma Cells Transfected with H-2K^band TAP-1 Genes

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• 作者：Li ; Mengfeng ; Xu ; Fan ; Muller ; Jacqueline ; Huang ; Xiaojun ; Hearing ; Vincent J. ; Gorelik ; Elieser
• 刊名：Virology
• 出版年：1999
• 出版时间：January 20, 1999
• 年：1999
• 卷：253
• 期：2
• 页码：230-240
• 全文大小：226 K

文摘

JB/RH1 melanoma cells, as well as other melanomas of C57BL/6 mice (B16 and JB/MS), express a common melanoma-associated antigen (MAA) encoded by an ecotropic melanoma-associated retrovirus (MelARV). JB/RH1 cells do not express the H-2K^bmolecules due to down-regulation of the H-2K^band TAP-1 genes. When JB/RH1 cells were transfected with the H-2K^band cotransfected with the TAP-1 gene, it resulted in the appearance of H-2K^bmolecules and an increase in their immunogenicity, albeit they lost expression of retrovirus-encoded MAA recognized by MM2-9B6 mAb. Loss of MAA was found to result from a complete and stable elimination of ecotropic MelARV production in the H-2K^b/TAP-1-transfected JB/RH1 cells. Northern blot analysis showed no differences in ecotropic retroviral messages in MelARV-producing and -nonproducing melanoma cells, suggesting that loss of MelARV production was not due to down-regulation of MelARV transcription. Southern blot analysis revealed several rearrangements in the proviral DNA of H-2K^b-positive JB/RH1 melanoma cells. Sequence analysis of the ecotropic proviral DNA from these cells showed numerous nucleotide substitutions, some of which resulted in the appearance of a novel intraviralPstI restriction site and the loss of aHindIII restriction site in thepolregion. PCR amplification of the proviral DNAs indicates that an ecotropic provirus found in the H-2K^b-positive cells is novel and does not preexist in the parental H-2K^b-negative melanoma cells. Conversely, the ecotropic provirus of the parental JB/RH1 cells was not amplifable from the H-2K^b-positive cells. Our data indicate that stable loss of retroviral production in the H-2K^b/TAP-1-transfected melanoma cells is probably due to the induction of recombination between a productive ecotropic MelARV and a defective nonecotropic provirus leading to the generation of a defective ecotropic provirus and the loss of MelARV production and expression of the retrovirus-encoded MAA.