title: Milk-specific RNase as a marker of differentiation of rat mammary tumors.
abstract: Various rat mammary tumors were analyzed for the presence of a milk-specific Ca2+-stimulated RNase (Ca2+-RNase). When crude extracts of some differentiated tumors--adenocarcinomas of MT/W9, MT/W9a, R3230AC, DMBA-1, DMBA-8, and DMBA-14 and 3MN squamous cell carcinoma--were assayed for RNase activity under various ionic conditions, it was always highest in the presence of Ca2+/EDTA than under any other ionic condition. The opposite was true in invasive MT/W449a and 13762 adenocarcinomas, poorly differentiated SMT/2A carcinomas, MAMF2/TC fibrosarcoma, and MT/A fibroadenoma. Sephacryl S-200 chromatography separation of tumor extracts confirmed the presence of Ca2+-RNase in those differentiated tumors and absence of the enzyme from other tumors. Expressing the activity as a ratio of Ca2+/EDTA to either Mg2+/EDTA or EDTA alone to more clearly represent the relative level of Ca2+-RNase activity further illustrates the distinct differences between tumor classes. Thus Ca2+-RNase is a sensitive marker for use in the characterization of rat tumors with respect to differentiated mammary functions.
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology; D000232:Adenofibroma / Q000201:enzymology / Q000473:pathology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002277:Carcinoma / Q000201:enzymology / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000473:pathology; D002454:Cell Differentiation; D005260:Female; D005354:Fibrosarcoma / Q000201:enzymology / Q000473:pathology; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology / Q000473:pathology*; D009363:Neoplasm Proteins / Q000032:analysis*; D009376:Neoplasms, Hormone-Dependent / Q000201:enzymology / Q000473:pathology; D051381:Rats; D012260:Ribonucleases / Q000032:analysis*
chemical_list: D009363:Neoplasm Proteins; D012260:Ribonucleases; D002118:Calcium