Steady‐state levels of c‐Ha‐ras mRNA were measured in eight sublines of the Dunning R3327 rat prostatic adenocarcinoma. As a control, normal dorsal prostate tissue was studied. Increased expression of c‐Ha‐ras is associated with tumor progression in one lineage of the Dunning R3327 system (H to AT1 to MAT‐Lu and MAT‐Ly‐Lu). Here ras mRNA increases as the tumor advances from androgen dependence and a high degree of differentiation to an anaplastic aneuploid phenotype with high metastatic potential. However, in the other Dunning lineage (H to HI to HI‐F to AT3), expression of c‐Ha‐ras is variable and does not correlate with tumor progression. Immunocytochemistry showed that levels of the c‐Ha‐ras p21 protein paralleled steady‐state mRNA levels in all variants. Transfection assays, using NIH/3T3 cells, suggested that the ras loci were not activated in the R3327 tumors. Levels of c‐Ki‐ras mRNA were also measured in the Dunning tumors; these did not correlate with tumor progression in either lineage. Expression of N‐ras mRNA was not detected in the Dunning tumors.
- p21 protein
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