Adult T-cell leukemia/lymphoma development in HTLV-1-infected humanized SCID mice.

Area of Science:

• Oncology
• Virology
• Immunology

Background:

• The molecular mechanisms driving adult T-cell leukemia/lymphoma (ATLL) initiation by human T-lymphotropic virus type-1 (HTLV-1) are not fully understood.
• A lack of suitable animal models hinders the study of HTLV-1-induced leukemogenesis.

Purpose of the Study:

• To develop and validate an animal model that accurately recapitulates HTLV-1-induced ATLL.
• To investigate the role of hematopoietic stem cells (HSCs) in HTLV-1 infection and leukemogenesis.

Main Methods:

• Humanized nonobese diabetic severe combined immunodeficiency (HU-NOD/SCID) mice were generated by inoculating NOD/SCID mice with HTLV-1-infected CD34(+) hematopoietic progenitor and stem cells (HP/HSCs).
• Mice were also reconstituted with HP/HSCs transduced with a lentivirus vector expressing the HTLV-1 oncoprotein (Tax1).
• Proviral integrations in purified HP/HSCs from HTLV-1-infected patients were analyzed.

Main Results:

• HTLV-1-HU-NOD/SCID mice exclusively developed CD4(+) T-cell lymphomas resembling ATLL.
• Elevated proliferation of infected human stem cells (CD34(+)CD38(-)) was observed in the bone marrow of mice with malignancies.
• NOD/SCID mice reconstituted with Tax1-transduced HP/HSCs also developed CD4(+) lymphomas.

Conclusions:

• The developed HU-NOD/SCID mouse model accurately recapitulates CD4(+) T-cell lymphoma, similar to ATLL.
• Hematopoietic stem cells (HSCs) serve as a viral reservoir and are cellular targets for transformation in HTLV-1-induced lymphoma.
• This model is a valuable tool for identifying molecular events, progression factors, and therapeutic targets for ATLL.