Abstract
We have previously reported the technique of in situ hybridization utilizing sulfonated DNA probes for the detection of amylase mRNA in formalin-fixed paraffin sections of human pancreas and submaxillary gland (22). Using this technique, we detected the mRNAs of Ha-ras and c-myc oncogenes in colonic cancer tissues from 24 patients, as well as in cultured cell lines. HL 60 cells, which are known to have amplified c-myc gene and accelerated transcription rate of this gene (11), and transformed NIH/3T3 cells with T24 Ha-ras were hybridized in situ with the sulfonated DNA probes of v-myc and v-Ha-ras respectively. Specific hybridization of v-myc probe for HL 60 and of v-Ha-ras probe for NIH/3T3 cells were clearly demonstrated at the cytoplasm by immunohistochemistry using a monoclonal antibody raised against sulfonated DNA. Of the colonic cancer tissues, which were freshly prepared and processed in paraffin, 6 were positive for Ha-ras mRNA and 7 were positive for c-myc mRNA. Northern blot analysis of the positive cases confirmed the validity of the results of in situ hybridization.
