Seizing of T cells by human T-cell leukemia/lymphoma virus type 1.
Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) causes neoplastic transformation of human T-cells in a small number of infected individuals several years from infection. Several viral proteins act in concert to increase the responsiveness of T-cells to extracellular stimulation, modulate proapoptotic and antiapoptotic gene signals, enhance T-cell survival, and avoid immune recognition of the infected T-cells. The virus promotes T-cell proliferation by usurping several signaling pathways central to immune T-cell function. Viral proteins modulate the downstream effects of antigen stimulation and receptor-ligand interaction, suggesting that extracellular signals are important for HTLV-1 oncogenesis. Environmental factors such as chronic antigen stimulation are therefore important, as also suggested by epidemiological data. The ability of a given individual to respond to specific antigens is determined genetically. Thus, genetic and environmental factors, together with the virus, contribute to disease development. As in the case of other virus-associated cancers, HTLV-1-induced leukemia/lymphoma can be prevented by avoiding viral infection or by intervention during the asymptomatic phase with approaches able to interrupt the vicious cycle of virus-induced proliferation of a subset of T-cells. This review focuses on current knowledge of the mechanisms regulating HTLV-1 replication and the T-cell pathways that are usurped by viral proteins to induce and maintain clonal proliferation of infected T-cells in vitro. The relevance of these laboratory findings will be related to clonal T-cell proliferation and adult T-cell leukemia/lymphoma development in vivo.
Franchini
Genoveffa
G
National Cancer Institute, Basic Research Laboratory, Bethesda, Maryland 20892, USA.
Nicot
Christophe
C
Johnson
Julie M
JM
D017209:Apoptosis; D002453:Cell Cycle; D004260:DNA Repair; D016356:Gene Products, tax / Q000378:metabolism; D016679:Genome, Viral; D015368:Human T-lymphotropic virus 1 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D008957:Models, Genetic; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D016366:Open Reading Frames; D013601:T-Lymphocytes / Q000821:virology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D016356:Gene Products, tax; D016159:Tumor Suppressor Protein p53