Transgenic rabbits with lymphocytic leukemia induced by the c-myc oncogene fused with the immunoglobulin heavy chain enhancer.

Abstract

Transgenic rabbits with the rabbit c-myc oncogene fused with the rabbit immunoglobulin heavy chain enhancer region (E,,) DNA were developed by microinjecting pronuclei of single cell zygotes with the gene construct and implanting the microinjected eggs into pseudopregnant females. At age 17-20 days, 3 of 21 offspring born to seven females were found to have peripheral blood leukocyte counts of >100,000 per mm3. Histology analyses showed extensive lymphocytic infiltration in the liver and kidney, indicating that these rabbits had a malignant lymphocytic leukemia. Genomic DNA analyses of thymus and peripheral blood lymphocytes revealed that the leukemic rabbits were transgenic and that both immunoglobulin heavy and K light chain genes were rearranged in the leukemic cells; thus, the leukemic cells are of B-cell lineage. One to four heavy and light chain gene rearrangements were observed, suggesting that the B-cell tumors were oligoclonal. Stable tissue culture cell lines from the bone marrow and peripheral blood of one of the transgenic rabbits have been developed. The development of B-cell leukemias in rabbits with the E,,-myc transgene contrasts with the development of B-cell lymphomas in mice carrying a similar transgene. The lymphomas in mice develop in adults and are monoclonal in origin. The leukemias in rabbits develop in juveniles, less than 3 weeks after birth, and appear oligoclonal in origin. The leukemias seem to develop in rabbit at a specific stage of development, and we suggest that a normal developmental signal may be involved in the oncogenesis.

Development of Keratoacanthomas and Squamous Cell Carcinomas in Transgenic Rabbits with Targeted Expression of EJras. Oncogene in Epidermis

“…The procedure for producing transgenic rabbits was based on the techniques previously described, 31,32 with some modifications in our laboratory. 16 New Zealand White rabbits were purchased from Covance Research Products (Denver, PA).…”

A Single 3′α hs1,2 Enhancer in the Rabbit IgH Locus

“…Further, the activity in rabbit T and epithelial cells was nearly equal to that in rabbit B cells, raising the possibility that hs1,2 is not B cell specific. We think, however, that the hs1,2 enhancer probably is B cell specific, but that because the rabbit B cell lines were obtained from c-myc and c-myc/v-abl transgenic rabbits, in which expression of the oncogenes was controlled by E (27,34), the low level of activity may result from inhibition of hs1,2 by a high level expression of c-myc/v-abl. However, we cannot exclude that the difference in hs1,2 activity in mouse and rabbit cells is due to inherent differences between rabbit and mouse cell lines.…”

“…The rabbit B cell line 55D1, the plasmacytoma cell line 240E (27,34), the murine A20 B cell line (American Type Culture Collection, Manassas, VA), and the rabbit CD4 ϩ T cell line 484.3 (a gift from P. Medveczky, University of South Florida, Tampa, FL) were grown in RPMI 1640 supplemented with 10% FCS. The kidney cell line RK13 was maintained in DMEM with 10% FCS.…”

“…The 900-bp XbaI/PstI fragment containing the putative hs1,2 was amplified by PCR from Fos15B with primers 5Ј-CGGGGATCCTC TAGAAGGA-3Ј and 3Ј-TTTGGATCCAGGACCAGTGCTGAGTGC-5Ј and inserted into the BamHI site of the pGL3 basic vector with and without a promoter in the 5Ј to 3Ј and 3Ј to 5Ј orientations relative to the reporter gene. The 700-bp EcoRI/BamHI fragment containing rabbit E (27) was also inserted into the BamHI/SalI sites of pGL3 with and without a V H promoter.…”

“…Within the rabbit IgH gene cluster, E has been identified as an enhancer region (27,28), but 3Ј␣E has not been described. Because 3Ј␣E is important for IgH gene expression and class switching, and because a 3Ј␣E resides downstream of each of two C␣ genes in the human genome, we investigated whether homologous regions are associated with each of the 13 rabbit C␣ genes.…”