Independently activated dbl oncogenes exhibit similar yet distinct structural alterations

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The dbl oncogene was first identified in NIH3T3 cells transfected with DNA from a human diffuse B cell lymphoma.
• A related transforming gene, NPDL-dbl, was isolated from a human nodular poorly differentiated lymphoma (NPDL).

Purpose of the Study:

• To characterize the molecular structure and rearrangements of the dbl and NPDL-dbl oncogenes.
• To investigate the potential role of these rearrangements in oncogene activation.

Main Methods:

• Transfection of NIH3T3 cells with tumor DNA.
• Restriction mapping and physical mapping of cloned DNA segments.
• Analysis of oncogene transcripts and translational products.

Main Results:

• The dbl oncogene exhibited a rearrangement at its 5' end involving sequences from another locus.
• NPDL-dbl showed homology to dbl but differed at the 5' and 3' termini, with divergence occurring further upstream.
• Both oncogenes produced truncated transcripts and distinct translational products compared to the normal dbl gene.
• No evidence of the 5' structural rearrangements was found in the original tumor DNA.

Conclusions:

• The identified rearrangements in dbl and NPDL-dbl oncogenes may contribute to their transforming activity.
• If critical for activation, these rearrangements likely occurred during gene transfer or in a minor subpopulation of tumor cells.