The role of G2-block abrogation, DNA double-strand break repair and apoptosis in the radiosensitization of melanoma and squamous cell carcinoma cell lines by pentoxifylline.

Purpose: To examine the role of G2-block abrogation, DNA repair inhibition and apoptosis in the enhancement of radiotoxicity by pentoxifylline.

Materials And Methods: The influence of pentoxifylline on radiotoxicity was assessed by colony assay in TP53 wild-type Bell and mutant MeWo melanoma, and in TP53 wild-type 4197 and mutant 4451 squamous cell carcinoma (SCC) cell lines. G2-block abrogation was assessed by flow cytometry.

Influence of apoptosis on the enhancement of radiotoxicity by ouabain.

Background: The Na+, K(+)-ATPase inhibitor ouabain enhances the toxicity of irradiation and we have previously demonstrated that the drug suppresses repair capacity. The influence of ouabain on apoptosis is not known and is examined in this study.

Materials And Methods: Seven human cell lines of defined TP53 status were irradiated with 60Co-gamma irradiation in the presence and absence of 10(-7) M ouabain.

Na+, K+-ATPase inhibitor, ouabain accentuates irradiation damage in human tumour cell lines.

Two normal, two tumour, one transformed fibroblast cell line established from Ataxia telangiectasia (AT) patients and one corrected AT hybrid were characterised with regard to alpha, beta, SF2, and D values. Survival of 60Co gamma-irradiated tumour and transformed cells was markedly reduced when the Na+, K+-ATPase inhibitor ouabain was present 1 hr before and 3 hr post irradiation. Under these conditions, the radiosensitivity in normal cells remained virtually unchanged.

Influence of ouabain on cell inactivation by irradiation.

Background: It has been suggested that irradiation affects the function of the Na(+)-K(+)-ATPase. Here we examine the influence of the inhibitor ouabain on the cytotoxicity of irradiation.

Material And Methods: Cell colony assay, cell survival, 86Rb-uptake, flow cytometry.

Effect of pentoxifylline on radiation damage and tumor growth.

Purpose: Inactivation of tumor cells by photon irradiation can be markedly improved by tumor oxygenation. We have investigated the effect of the vasoactive drug pentoxifylline with respect to cell toxicity, radiation sensitivity, repair and tumor growth.

Methods: V79 and Hela cell survival curves and determination of the tumor volume using rhabdomyosarcoma growth in BALB/c mice.