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A multitherapy resistance factor from melanoma reveals that killing by near UV is different from genotoxic agents
H Z Hill1, G J Hill, K Cieszka
1Department of Radiology, New Jersey Medical School, Newark 07103-2714, USA.
Abstract:
A diffusible multitherapy resistance factor (MTRF) is produced by Cloudman S91 melanoma cells in vitro. The MTRF decreases sensitivity of the target cell line, S91/amel, to gamma-irradiation, UVC (200-280 nm) and mitomycin C (MMC). In the present study, we demonstrate that MTRF also increases the survival of S91/amel after exposure to actinomycin D (AMD) and vinblastine (VBL). The MTRF is thus effective when target cells have been exposed to five genotoxic agents that act by different mechanisms. It does not alter the response to the same five agents of the S91/I3 producer cells, which are presumably saturated with the factor. The factor has no effect on the survival of S91/amel cells that have been exposed to lethal doses of near monochromatic UVB (280-320 nm) or UVA (320-400 nm) or to polychromatic FS20 lamps. The lack of effectiveness of MTRF after cells have been exposed to near (300-400 nm) UV radiation indicates that in this wavelength range, S91 melanoma cells are killed by mechanisms that are different from the lethal effects of the five genotoxic agents (gamma-irradiation, UVC, MMC, AMD and VBL) to which the target cells demonstrate a response.
Insights
A novel multitherapy resistance factor (MTRF) enhances melanoma cell survival against five genotoxic agents, including gamma-irradiation and chemotherapy drugs. However, MTRF does not protect against near-UV radiation, suggesting distinct cell death mechanisms.
Area of Science:
- Cell Biology
- Cancer Research
- Molecular Biology
Background:
- Cloudman S91 melanoma cells produce a diffusible multitherapy resistance factor (MTRF).
- MTRF confers resistance in target S91/amel cells to gamma-irradiation, UVC, and mitomycin C (MMC).
Purpose of the Study:
- To investigate the effect of MTRF on S91/amel cell survival against additional genotoxic agents.
- To determine the range of genotoxic agents to which MTRF confers resistance.
- To explore the mechanisms of cell death induced by different UV wavelengths.
Main Methods:
- Exposure of S91/amel cells to actinomycin D (AMD) and vinblastine (VBL) in the presence of MTRF.
- Assessment of cell survival rates after exposure to various genotoxic agents.
- Comparison of MTRF effectiveness against different UV radiation types (UVC, UVB, UVA) and polychromatic lamps.
Main Results:
- MTRF significantly increased S91/amel cell survival after exposure to AMD and VBL.
- MTRF demonstrated effectiveness against five distinct genotoxic agents acting via different mechanisms.
- MTRF did not enhance survival of S91/amel cells exposed to near-monochromatic UVB, UVA, or polychromatic FS20 lamps.
Conclusions:
- MTRF provides broad-spectrum resistance against multiple genotoxic agents, including chemotherapy drugs.
- The lack of MTRF effectiveness against near-UV radiation suggests distinct cell death pathways are activated by these wavelengths.
- Further research is needed to elucidate the precise mechanisms of MTRF action and its limitations.