This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Varga, J. M. Articles by Hearst, J. E. Search for Related Content PubMed PubMed Citation Articles by Varga, J. M. Articles by Hearst, J. E.

Dose-related Effects of Psoralen and Ultraviolet Light on the Cell Cycle of Murine Melanoma Cells¹

Department of Dermatology, Yale University School of Medicine [J. M. V.], New Haven, Connecticut 06510, and Chemistry Department [G. W., J. E. H.] and Biodynamics Laboratory [J. C. B.], Lawrence Berkeley Laboratories, University of California, Berkeley, Berkeley, California 94720

Cloudman (S91) murine melanoma cells were treated with 4'-hydroxymethyltrioxsalen (HMT), a bifunctional psoralen and exposed to long-wavelength (365 nm) ultraviolet light. DNA content of the cells stained with propidium iodide was measured by flow cytometry, and cell cycle phases were delineated from the DNA histograms by using a curve-fitting routine. We found that HMT in combination with long-wavelength (365 nm) ultraviolet irradiation blocked melanoma cells in different phases of the cell cycle, depending on the dose of long-wavelength (365 nm) ultraviolet light and the concentration of HMT. The binding of [³H]HMT to DNA was measured parallel with cell cycle analyses. Treatments with HMT at concentrations corresponding to about 1 HMT bound per 10⁶ base pairs of DNA led to the accumulation of cells with predominantly G₂ DNA content. At higher concentrations (2 to 3 HMT/10⁶ base pairs), the cells were blocked in the S and G₁ phases. In conclusion, we have shown that extremely sparse substitution of HMT to DNA blocks melanoma cells in the G₂ phase or other phases of the cell cycle in a dose-dependent manner.

¹ This Investigation was supported by Grant CA-26081 awarded by the National Cancer Institute and by the Division of Biomedical and Environmental Research, United States Department of Energy, Contract W-7405-ENG-48.

² Recipient of Research Career Development Award 5K04 A1 00154 from USPHS, to whom requests for reprints should be addressed.

Received 6/15/81. Accepted 3/12/82.