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Cytogenetic evidence of gene amplification as a mechanism for tumor cell invasion
S J Bevacqua1, C W Greeff, M J Hendrix
1Department of Molecular and Cellular Biology, University of Arizona, College of Medicine, Tucson 85724.
Abstract:
In order to study the process by which human melanoma cells achieve invasion of basement membranes, a modification of the Membrane Invasion Culture System was developed to allow the in vitro collection of human melanoma cell populations that had invaded acellular human amniotic membranes. A significant increase in the number of double-minute chromosomes (DMs) was observed in metaphase nuclei of A375P human melanoma cells which had passed through two amniotic membranes (A375P-2) over that of control cells. Eighteen percent of the first monolayer of A375P-2 cells contained 1-89 DMs/cell, whereas 3-8.3% of the control A375P cells contained 1-10 DMs/cell. There was a rapid loss of DMs in A375P-2 cells as a function of passage number. After 25 days in tissue culture, the incidence of DMs had essentially dropped below the control range. These data indicate that an unstable gene amplification event may be part of the process by which melanoma cells execute invasion through basement membranes.
Insights
Human melanoma cells invading basement membranes showed increased double-minute chromosomes (DMs). This gene amplification was unstable, rapidly decreasing after invasion, suggesting a role in melanoma cell metastasis.
Area of Science:
- Oncology
- Cell Biology
- Genetics
Background:
- Melanoma cell invasion of basement membranes is a critical step in metastasis.
- Understanding the genetic mechanisms underlying melanoma invasion is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the in vitro process of human melanoma cell invasion through basement membranes.
- To identify potential genetic alterations associated with melanoma cell invasiveness.
Main Methods:
- A modified Membrane Invasion Culture System was used to collect human melanoma cells that invaded acellular human amniotic membranes.
- Metaphase nuclei of invaded (A375P-2) and control (A375P) melanoma cells were analyzed for chromosome abnormalities, specifically double-minute chromosomes (DMs).
Main Results:
- A significant increase in DMs was observed in A375P-2 cells compared to control A375P cells.
- Eighteen percent of A375P-2 cells contained 1-89 DMs/cell, versus 3-8.3% in control cells.
- DMs were rapidly lost in A375P-2 cells over time in tissue culture, dropping below control levels within 25 days.
Conclusions:
- The data suggest that unstable gene amplification, indicated by DMs, may be involved in the process of melanoma cell invasion through basement membranes.
- This transient genetic instability could play a role in the metastatic capabilities of melanoma cells.