Oncogene mobility in a human leukemia line HL-60

Area of Science:

• Human genetics
• Cancer biology
• Molecular cytogenetics

Background:

• HL-60 cells, derived from human promyelocytic leukemia, exhibit c-myc oncogene amplification.
• Reported chromosomal aberrations in HL-60 include double minutes (DMs) and an abnormally banded region (ABR) on chromosome 8.
• A link between these aberrations and c-myc DNA amplification has been hypothesized.

Purpose of the Study:

• To localize amplified c-myc DNA within HL-60 cells using cytologic hybridization.
• To investigate the chromosomal integration sites of amplified c-myc.
• To understand the chromosomal mechanisms underlying c-myc amplification in leukemia.

Main Methods:

• Cytologic hybridization was employed to determine the location of amplified c-myc DNA.
• Analysis was performed on early passage HL-60 cells and later passage clones.
• Karyotyping and chromosome banding techniques were utilized to identify chromosomal abnormalities.

Main Results:

• Amplified c-myc DNA was localized to a marker chromosome, M3q+, in early passage HL-60 cells.
• In later passage clones, c-myc was found at an ABR on an 8q+ chromosome.
• The M3q+ chromosome likely resulted from a translocation t(5p;17q) with c-myc amplification material inserted into 17q.

Conclusions:

• Amplification and chromosomal integration of c-myc can occur at sites distinct from its native locus.
• Different integration sites for amplified c-myc can be observed in different lineages of the same tumor.
• These findings provide insights into the dynamic nature of oncogene amplification in cancer development and progression.