Antiproliferative and cytotoxic effects of single and combined treatment with tumor necrosis factor alpha and/or alpha interferon on a human renal cell carcinoma xenotransplanted into nu/nu mice: cell kinetic studies.
A human renal cell carcinoma serially transplanted into nude mice was treated with recombinant human tumor necrosis factor alpha (TNF-alpha), recombinant human alpha interferon (IFN-alpha), and a combination of both. All treatments resulted in a significantly reduced tumor growth. The greatest effect was obtained with the combination of TNF-alpha and IFN-alpha. This latter treatment completely eradicated tumors which were smaller than 50 mm3 at the beginning of treatment. Cell kinetic analysis using the bromodeoxyuridine technique and flow cytometry revealed a prolongation of the transition time through S-phase from 7.9 h in the case of control tumors to 10.5 h for tumors treated with IFN-alpha and TNF-alpha. Single treatment with either TNF-alpha or IFN-alpha had only minor effects. The bromodeoxyuridine labeling index was unaffected by IFN-alpha (16.6%; control, 15.2%) but was reduced to 12.1 and 11.7% when tumors were treated with TNF-alpha and IFN-alpha plus TNF-alpha, respectively. The calculated potential doubling times were 2.3 and 2.8 days, respectively, for tumors treated with TNF-alpha or IFN-alpha plus TNF-alpha. When treated with IFN-alpha, the potential doubling time (1.7 days) was similar to that of the control (1.6 days), indicating that the main effect of TNF-alpha was antiproliferative. Conversely, the calculated cell loss factors increased after IFN-alpha and combined treatment but not after TNF-alpha treatment. Combined treatment augmented cytotoxicity, but the cell kinetic characteristics of surviving cells remained similar to those of tumors treated with TNF-alpha alone. Histological analysis showed a distinctly reduced mitotic activity but no coagulative necroses after treatment with TNF-alpha. IFN-alpha and, in particular, IFN-alpha plus TNF-alpha induced cytoplasmic vacuolization, nuclear pyknosis, and cell death, which resulted in tumor regression. These data suggest that, in this particular tumor model, TNF-alpha produces mainly antiproliferative effects, whereas IFN-alpha acts via cytotoxic mechanisms.
Institute of Biophysics and Radiobiology, University of Hamburg, Federal Republic of Germany.
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Baisch
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Otto
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Klöppel
D000818:Animals; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000628:therapy*; D002453:Cell Cycle; D004354:Drug Screening Assays, Antitumor; D004359:Drug Therapy, Combination; D006801:Humans; D007370:Interferon Type I / Q000008:administration & dosage / Q000627:therapeutic use*; D007680:Kidney Neoplasms / Q000473:pathology / Q000628:therapy*; D007700:Kinetics; D051379:Mice; D008819:Mice, Nude; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000627:therapeutic use*
D007370:Interferon Type I; D014409:Tumor Necrosis Factor-alpha