Oncogene expression in endocrine pancreatie tumors

The mRNA expression of the (proto) oncogenes Ha-ras, Ki-ras, fos, c-myc, N-myc, and sis was studied in five pancreatic endocrine tumors and two non-neoplastic pancreases by in situ hybridization and Northern blot analysis. Ha-ras, Ki-ras, fos and c-myc, but not N-myc or sis mRNA was detected in all the tumors as well as in the non-neoplastic pancreatic tissues. Compared with non-tumorous pancreatic tissue, Ha-ras and Ki-ras mRNA was overexpressed up to 42-fold in all the tumors; metastasizing tumors showed 2–6 times higher Ha-ras mRNA levels than benign neoplasias. In contrast, c-myc mRNA levels were higher in normal tissue than in tumors and fos mRNA levels did not differ significantly between tumors and normal tissue. The activities of Ki-ras, fos and c-myc mRNA expression did not correlate with any of the histological or biological properties of the tumors, nor with the clinical course of disease. Our results, although based on a limited number of cases, suggest that Ha-ras and Ki-ras mRNA overexpression is associated with the development of pancreatic endocrine tumors. The measurement of Ha-ras mRNA levels may contribute to the assessment of tumor prognosis.