APOPTOSIS AND INTERLEUKIN-7 GENE-EXPRESSION IN CHRONIC B-LYMPHOCYTIC LEUKEMIA-CELLS

Citation
Bw. Long et al., APOPTOSIS AND INTERLEUKIN-7 GENE-EXPRESSION IN CHRONIC B-LYMPHOCYTIC LEUKEMIA-CELLS, Proceedings of the National Academy of Sciences of the United Statesof America, 92(5), 1995, pp. 1416-1420
Citations number
37
Categorie Soggetti
Multidisciplinary Sciences
ISSN journal
00278424
Volume
92
Issue
5
Year of publication
1995
Pages
1416 - 1420
Database
ISI
SICI code
0027-8424(1995)92:5<1416:AAIGIC>2.0.ZU;2-P
Abstract
mRNA for interleukin 7 (IL-7) was readily detected in leukemic cells i mmediately upon their removal from patients with chronic B-lymphocytic leukemia (B-CLL), IL-7 mRNA expression and IL-7 gene transcription we re down regulated, however, when B-CLL cells were placed in culture at 37 degrees C for 4 hr, Down regulation of the IL-7 gene was prevented in cells maintained at 4 degrees C, Continued culture of B-CLL cells at 37 degrees C resulted in programmed cell death, or apoptosis, as ev idenced by DNA fragmentation, The coincident kinetics of IL-7 gene dow n regulation and apoptosis suggested that IL-7 gene expression may be required for maintenance of CLL viability in vivo, Signals for IL-7 ge ne regulation and apoptosis induction were thus examined, Activation o f normal B cells through their immunoglobulin receptors did not result in upregulation of IL-7 gene expression, Reagents required for CLL ce ll purification and culture also did not contribute to IL-7 gene regul ation and apoptosis induction, IL-7 gene expression was retained and a poptosis was prevented, hen-ever, in CLL cells cultured on a monolayer of EA.hy926 human umbilical cord endothelial hybrid cells, Signals sp ecifically presented by EA.hy926 cells supported both CLL cell viabili ty and IL-7 gene expression, whereas culture of CLL cells on A549/8 ca rcinoma cells, the fusion partner used to generate the EA.hy926 cells, did not, Cell-cell contact was required, as culture supernatants did not prevent apoptosis, Specifically, IL-7 mRNA expression was retained and apoptosis was prevented only by contact with the endothelial cell hybrids, Preliminary data indicated that integrins expressed on CLL c ells effected modulation of apoptosis and IL-7 gene regulation, sugges ting that integrins may play significant roles in regulating viability of CLL cells.