Changes in tumor hypoxia measured with a double hypoxic marker technique

Purpose: Development of a double hypoxic cell marker assay, using the biore ductive nitroimidazole derivatives CCI-103F and pimonidazole, to study chan ges in tumor hypoxia after treatments that modify tumor oxygenation. Methods and Materials: Both hypoxic markers were visualized by immunohistoc hemical techniques to detect changes in hypoxic fraction induced by carboge n breathing (95% O-2 and 5% CO2) or hydralazine injection. The protocol was tested in a human laryngeal squamous cell carcinoma xenograft line. Quanti tative measurements were derived from consecutive tissue sections that were analyzed by a semiautomatic image analysis system. Qualitative analysis wa s obtained by double staining of the two hypoxic markers on the same tissue section. Results: A significant correlation between the hypoxic fractions for the tw o markers, CCI-103F and pimonidazole, was found in air breathing animals. A fter carbogen breathing, the hypoxic fraction decreased significantly from 0.07 to 0.03, and after hydralazine treatment, the hypoxic fraction increas ed significantly. Reduction of hypoxia after carbogen breathing was most pr onounced close to well-perfused tumor regions. Conclusions: With this method, employing two consecutively injected bioredu ctive markers, changes in tumor hypoxia can be studied. A significant reduc tion in hypoxia after carbogen breathing and a significant increase in hypo xia after hydralazine administration was demonstrated. (C) 2000 Elsevier Sc ience Inc.