Oncogene expression detected by in situ hybridization in human primary lung cancer

By means of in situ hybridization using biotinylated oncogene probes and the immunohistochemical reaction of avidin-biotin complex-alkaline phosphatase with substrate, we investigated expression of c-myc oncogene in the formalin-fixed, paraffin-embedded tissue sections from seven patients with squamous cell carcinoma (six cases) and small cell carcinoma (one case) of primary lung origin. The expression of c-myc oncogene was greatly enhanced in all cases studied, with individual and cell-to-cell variation. In contrast, all of the specimens incubated with deoxyribonuclease after the standard pretreatment with ribonuclease T1 were negative for the expression of c-myc oncogene. The in situ hybridization permits estimation of a heterogeneous amplification of c-myc oncogene that may be related to secondary alterations occurring during the progression of the malignant lung tumors.