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6th ESACP Congress, Heidelberg, April 7-11, 1999 |
A109
A double staining technique was developed for the simultaneous measurement of
tissue hypoxia and the concentration of non-protein sulphydryls (NPSH), based
on the fluorinated nitroimidazole EF5 and the fluorescent histochemical NPSH
stain mercury orange. Cryostat sections of tumour tissue were examined by
fluorescence image analysis, using a computer controlled microscope stage to
generate large tiled field images of the cut tumour surface. This method was
applied to the human cervical squamous cell carcinoma lines ME180 and SiHa,
grown as xenografts in SCID mice, in order to determine if there is a
systematic relationship between tissue hypoxia and NPSH levels. Hypoxic
regions of the tumours, defined by EF5 labeling, were found to show greater
NPSH concentrations relative to better oxygenated regions. This is probably
due to increases in glutathione, since the ME180 and SiHa xenografts contained
low levels of cysteine and metallothionein; the other major cellular thiols
that can bind to mercury orange. Because the effects of glutathione on
radiation and chemotherapy resistance are likely to be greater under hypoxic
conditions, these results have potentially important implications for the
study of resistance mechanisms in solid tumours.
ELEVATIONS OF NON-PROTEIN SULPHYDRYLS IN HYPOXIC MICROREGIONS OF TUMORS,
MEASURED USING FLUORESCENCE IMAGE CYTOMETRY
Nicklee T, Moreno-Merlo F, Hedley D
Dept of Oncologic Pathology Ontario Cancer Institute/Princess Margaret
Hospital, Toronto, Canada