Elevation of peptidylproline hydroxylase activity and collagen synthesis in spontaneous primary mammary cancers of inbred mice.

Parameters of collagen biosynthesis were determined in mammary cancer tissue. Peptidylproline hydroxylase (PPH) activity was determined in spontaneous primary mammary cancer tissue and normal mammary gland in fat pad. The enzyme was located in the 105,000 X g supernatant of whole-tissue homogenates. Ascorbate, a-ketoglutarate, and ferrous ion were required for enzyme activity of cancerous and control tissues. The activity of PPH of cancer tissue from five high-mammary-cancer strains of inbred mice was 3to 5-fold higher than the level of enzyme activity in normal mammary gland in fat pad of animals of comparable age. As a second parameter of collagen-biosynthetic rate of cancer tissue and specifically the PPH step, the rate of formation of hydroxyproline-14C from uniformly labeled proline-14C was