Advertisement

Cancer Chemotherapy and Pharmacology

, Volume 27, Issue 4, pp 315–319 | Cite as

Mechanism of action of psoralens: isobologram analysis reveals that ultraviolet light potentiation of psoralen action is not additive but synergistic

  • Edward J. Yurkow
  • Jeffrey D. Laskin
Original Articles Psoralens, Isobologram Analysis, Synergism, UV

Summary

The combination of psoralens and ultraviolet light (UVA, 320–400 nm), referred to as PUVA, inhibits proliferation of a variety of cell types. In the present studies, we used S-180 cells to investigate the mechanism underlying the antiproliferative actions of PUVA. We found that inhibition of growth of S-180 cells by PUVA was dependent on the concentration of psoralen as well as the dose of UVA light. Neither the psoralens nor UVA light by themselves inhibited cell growth. Several clinically important psoralen analogs inhibited cell growth. The potent phototoxin 4,5′,8-trimethylpsoralen was the most active psoralen analog tested, followed by 5-methoxypsoralen and 8-methoxypsoralen. The angular furocoumarin, 5-methylangelicin, was the least active inhibitor of growth. Multivariate (isobologram) analysis of the growth-inhibition curves revealed that combinations of psoralens and UVA light were not simply additive but synergistic. Similar results were observed when inhibition of DNA synthesis was used as an endpoint for the biological effects of PUVA. These studies are the first to demonstrate that psoralens and UVA light act synergistically. Our results suggest that the synergism between the psoralens and UVA light may be an important property of PUVA that contributes to its therapeutic efficacy in proliferative diseases.

Keywords

Cell Growth Cancer Research Active Inhibitor Biological Effect Therapeutic Efficacy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

8-MOP

8-methoxypsoralen

5-MOP

5-methoxypsoralen

TMF

4,5′,8-trimethylpsoralen

5-MA

5-methylangelicin; UVA, ultraviolet light of 320–400 nm wavelength

PUVA

psoralens used in combination with UVA light

DMEM

Dulbecco's Modified Eagle's Medium

PBS

phosphate-buffered saline

HEPES

N-2-hydroxyethylpiperazine-N′-2-ethane-sulfonic acid

IC50

level of PUVA treatment that inhibits measurable cellular parameters by 50%

[3H]-TdR

[methyl-3H]-thymidine

TCA

trichloroacetic acid

HGPRT

hypoxanthine-guanine phosphoribosyltransferase

CHO

Chinese hamster ovary

EDTA

ethylenediaminetetraacetic acid

EGF

epidermal growth factor

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Babudri N, Pani B, Venturini S, Tamaro M, Montibragadin C, Bordin F (1981) Mutation induction and killing of V79 Chinese hamster cells by 8-methoxypsoralen plus near-ultraviolet light: relative effects of monoadducts and cross-links. Mutat Res 91: 391–394Google Scholar
  2. 2.
    Berenbaum MC (1989) What is synergy? Pharmacol Rev 41: 93–140Google Scholar
  3. 3.
    Black ML (1963) Sequential blockage as a theoretical basis for drug synergism. J Med Chem 6: 145–153Google Scholar
  4. 4.
    Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principal of protein-dye binding. Anal Biochem 72: 248–254Google Scholar
  5. 5.
    Elion GB, Singer S, Hitchings GH (1954) Antagonists of nucleic acid derivatives: VIII. Synergism in combinations of biochemically related antimetabolites. J Biol Chem 208: 477–488Google Scholar
  6. 6.
    Grindey GB, Nichol CA (1972) Interaction of drugs inhibiting different steps in the synthesis of DNA. Cancer Res 32: 527–531Google Scholar
  7. 7.
    Grindey GB, Mihich E, Nichol CA (1972) Evaluation of combination chemotherapy in vivo and in culture with 1-β-d-arabinofuranosylcytosine and 1-formylisoquinoline thiosemicarbazone. Cancer Res 32: 522–526Google Scholar
  8. 8.
    Handschumacher RE (1965) Formal discussion: some enzymatic considerations in combination chemotherapy. Cancer Res 25: 1541–1543Google Scholar
  9. 9.
    Joshi PC, Pathak MA (1983) Production of singlet oxygen and superoxide radicals by psoralens and their biological significance. Biochem Biophys Res Commun 111: 638–646Google Scholar
  10. 10.
    Laskin JD, Laskin DL (1988) Role of psoralen receptors in cell growth regulation. In: Gasparro F (ed) Psoralen DNA photobiology, vol II. CRC Press, Boca Raton, Florida, pp 139–148Google Scholar
  11. 11.
    Laskin JD, Evans RM, Solcum HK, Burke D, Hakala MT (1979) Basis for natural variation in sensitivity to 5-fluorouracil in mouse and human cells in culture. Cancer Res 39: 383–390Google Scholar
  12. 12.
    Laskin JD, Lee E, Yurkow EJ, Laskin DL, Gallo MA (1985) A possible mechanism of psoralen phototoxicity not involving direct interaction with DNA. Proc Natl Acad Sci USA 82: 6158–6162Google Scholar
  13. 13.
    Laskin JD, Lee E, Laskin DL, Gallo MA (1986) Psoralens potentiate ultraviolet light-induced inhibition of epidermal growth factor binding. Proc Natl Acad Sci USA 83: 8211–8215Google Scholar
  14. 14.
    Lowe NJ, Cripps DV, Warin AP (1979) Photochemotherapy for mycosis fungoides. Arch Dermatol 115: 50–53Google Scholar
  15. 15.
    Mermelstein FH, Laskin JD (1989) Inhibition of epidermal growth factor receptor kinase activity in A431 human epidermoid cells following psoralen/ultraviolet light treatment. Mol Pharmacol 36: 848–855Google Scholar
  16. 16.
    Morison WL, Parrish JA, Fitzpatrick TB (1987) Oral psoralen photochemotheray of atopic eczema. Br J Dermatol 98: 25–30Google Scholar
  17. 17.
    O'Niell JP, Brimer PA, Machanoff R, Hirsch GP, Hsie AW (1977) A quantitative assay of mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus in Chinese hamster ovary cells (CHO/HGPRT system): development and definition of the system. Mutat Res 45: 91–102Google Scholar
  18. 18.
    Parrish JA, Fitzpatrick TB, Tannenbaum L, Pathak MA (1974) Photochemotherapy of psoriasis with oral methoxsalen and long wave ultraviolet light. N Engl J Med 291: 1207–1222Google Scholar
  19. 19.
    Parrish JA, Fitzpatrick TB, Shea C, Pathak MA (1976) Photochemotherapy of vitiligo. Arch Dermatol 112: 1531–1535Google Scholar
  20. 20.
    Pathak MA, Joshi PC (1984) Production of active oxygen species1O2 and O 2) by psoralens and ultraviolet radiation (320–400 nm). Biochim Biophys Acta 798: 115–126Google Scholar
  21. 21.
    Pathak MA, Kramer DM, Fitzpatrick TB (1974) Photobiology and photochemistry of furocoumarins (psoralens). In: Fitzpatrick TB (ed) Sunlight and man, vol 22. Tokyo: University of Tokyo Press, Tokyo, pp 335–368Google Scholar
  22. 22.
    Rodighiero G, Dall' Acqua F (1982) In vitro photoreactions of selected psoralens and methylangelicins with DNA, RNA, and proteins. In: Greenwald P (ed) Photobiologic, toxicologic, and pharmacologic aspects of psoralens. (National Cancer Institute Monograph 66) U.S. Govemment Printing Office, Washington, D.C., pp 31–40Google Scholar
  23. 23.
    Rodighiero G, Dall' Acqua F, Pathak MA (1985) Photobiological properties of monofunctional furocoumarin derivatives In: Smith KC (ed) Topics in photomedicine. Plenum Press, New York, pp 319–398Google Scholar
  24. 24.
    Roos DS, Schimke RT (1987) Toxicity of folic acid analogs in cultured human cells: a microtiter assay for the analysis of drug competition. Proc Natl Acad Sci USA 84: 4860–4864Google Scholar
  25. 25.
    Rubin RJ, Reynard A, Handschumacher RE (1964) An analysis of the lack of drug synergism during sequential blockade of de novo pyrimidine biosynthesis. Cancer Res 24: 1002–1007Google Scholar
  26. 26.
    Schenley RL, Hsie AW (1981) Interaction of 8-methoxypsoralen and near-UV light causes mutation and cytotoxicity in mammalian cells. Photochem Photobiol 33: 179–185Google Scholar
  27. 27.
    Schlessinger J (1988) The epidermal growth factor receptor as a multifunctional allosteric protein. Biochemistry 27: 3119–3123Google Scholar
  28. 28.
    Steel GG, Peckham MJ (1979) Exploitable mechanisms in combined radiotherapy-chemotherapy: the concept of additivity. Int J Radiat Oncol Biol Phys 5: 85–91Google Scholar
  29. 29.
    Wolff K, Honigsmann H (1971) Safety and therapeutic effectiveness of selected psoralens in psoriasis. In: Greenwald P (ed) Photobiologic, toxicologic, and pharmacologic aspects of psoralens. (National Cancer Institute Monograph 66) U.S. Government Printing Office, Washington, D.C., pp 159–164Google Scholar
  30. 30.
    Yurkow EJ, Laskin JD (1987) Characterization of a photoalkylated psoralen receptor in HeLa cells. J Biol Chem 262: 8439–8442Google Scholar

Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • Edward J. Yurkow
    • 1
  • Jeffrey D. Laskin
    • 1
  1. 1.Department of Environmental and Community MedicineUniversity of Medicine and Dentistry of New Jersey, UMDNJ-Robert Wood Johnson Medical SchoolPiscatawayUSA

Personalised recommendations