The programmed cell death of an immature thymocyte cell line transgenic for an alpha beta TCR and the c-myc proto-oncogene.

Marianna Murdjeva,Yujiro Tanaka,Dimitris Kioussis,Trisha Norton

doi:10.1155/1995/93271

Marianna Murdjeva, Yujiro Tanaka + Show 2 more

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https://doi.org/10.1155/1995/93271

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Abstract

The c-myc proto-oncogene linked to the mouse Thy-1 gene transcriptional unit predisposes mice to development of thymic tumors consisting predominantly of immature CD4+ CD8+ cells. In an attempt to immortalize immature T cells expressing a known T-cell antigen receptor (TCR), Thy-1/c-myc transgenic mice were bred to αβ TCR transgenic mice (F5), and CD4+ CD8+ cell lines were established from thymic tumors in double-transgenic mice. These cells expressed high-level heat-stable antigen (HSA) and were able to undergo programmed cell death upon induction with steroids and CD3 cross-linking, but not with cognate peptide. In addition, one line had rearranged and transcribed endogenous TCR c and genes, in spite of the fact that transgenic α and β genes were also expressed. Furthermore, we show that Thy-1/myc transgenic mice deficient in recombination activating gene-1 (RAG-1) do not develop tumors, in contrast to RAG-1-/- mice, which are also transgenic for both Thy-1/myc and the F5 TCR. This indicates that in order for thymocytes to be transformed by the Thy-myc transgene, they need to proceed to the double-positive stage.

Highlights

Overexpression of the c-myc proto-oncogene in humans has been implicated in the development of T- and B-cell leukemia, in which chromosomal translocations bring the c-myc in close proximity to either T-cell antigen receptor (TCR)- or immunoglobulin-gene regulatory elements
It has previously been shown that different Thy-1/ c-myc (TM) mouse lines give rise to thymic tumors of various phenotypes with respect to CD4, CD8, and heat-stable antigen (HSA) expression (Spanopoulou et al, 1989; Y.T. unpublished observation)
In order to determine the phenotype of cells expanded in the thymic tumor, thymic tumor cells were stained for CD4, CD8, and CD3, V11(transgenic TCR), or HSA; lymphnode cells were stained with CD4 and CD8

Summary

INTRODUCTION

Overexpression of the c-myc proto-oncogene in humans has been implicated in the development of T- and B-cell leukemia, in which chromosomal translocations bring the c-myc in close proximity to either TCR- or immunoglobulin-gene regulatory elements (for reviews, see Dalla-Favera et al, 1982; Casares et al, 1993; Gauwerky and Croce, 1993; Stephenson et al, 1993). Gene rearrangements in the thymic tumors revealed that thymocytes were of oligoclonal origin, suggesting that oncogenic transformation occurred at the CD4 CD8 stage in a stochastic manner. Those data supported the hypothesis that tumorigenesis is a multistep process and cooperation of c-myc with other genetic mutation(s) is required for neoplastic transformation, as had been shown by others (Adams and Cory, 1992). We show that these double-positive (DP) cell lines are functionally immature and undergo programmed cell death upon induction with steroids and crosslinking of CD3 by antibodies These cell lines were refractory to treatment with antigenic peptides, suggesting either that the levels of the transgenic TCR are insufficient to mediate antigenspecific signals or that the TCP is uncoupled from CD3-1inked downstream signal-transduction machineries. TM/RAG-1 -/- mice do not develop thymic tumors, indicating that for transformation to take place, thymocytes have to enter the double-positive (CD4 / 8 /) stage of development

RESULTS

DISCUSSION

MATERIALS AND METHODS