Proto-oncogene expression in avian hematopoietic tissues

Area of Science:

• Molecular Biology
• Oncology
• Virology

Background:

• Previous studies indicated proto-oncogene expression in avian myeloblastosis virus (AMV)-transformed cells.
• The MYB gene is repressed in AMV-transformed cells, while ETS, FPS, MHT (RAF), MYC, and REL are expressed.

Purpose of the Study:

• To investigate whether proto-oncogene expression is altered by v-myb-induced leukemogenesis.
• To analyze proto-oncogene expression in various chicken hematopoietic tissues and chicken embryonic fibroblasts (CEF).

Main Methods:

• Northern blot analysis was used to examine Poly-A+ RNA from hematopoietic cells and CEF.
• Five chicken hematopoietic tissues (yolk sac, spleen, bursa of Fabricius, bone marrow, thymus) were analyzed.

Main Results:

• All five proto-oncogenes (ETS, FPS, MHT (RAF), MYC, REL) were expressed in normal hematopoietic tissues.
• ETS, MHT (RAF), MYC, and REL genes were expressed in CEF, but not FPS.
• Proto-oncogene expression was not altered in AMV-transformed myeloid cells compared to normal cells.

Conclusions:

• Proto-oncogene expression is part of the hematopoietic phenotype and necessary for AMV transformation susceptibility.
• High-level expression of these proto-oncogenes in thymocytes does not lead to transformation, indicating it's not sufficient.
• MYB expression is repressed in leukemic cells, likely independent of v-myb expression.