Regulation of creatine kinase activity in rat osteogenic sarcoma cell clones by parathyroid hormone, prostaglandin E₂, and vitamin D metabolites

We have previously shown that both parathyroid hormone (PTH) and prostaglandin E₂ (PGE₂) stimulate the activity of creatine kinase BB (CKBB) in rat bone cells in culture. Therefore, morphologically distinct rat osteogenic sarcoma cells in culture were tested for stimulation of CKBB activity by hormones that regulate skeletal tissues. PTH stimulated CKBB in the osteoblast-like clone ROS 17/2; 1α,25(OH)₂D₃ inhibited this activity while PGE₂, CT and 24R,25(OH)₂D₃ had no significant effect. PGE₂ stimulated CKBB activity in the fibroblast-like clone ROS 24/1, which was unresponsive to PTH, CT and Vitamin D metabolites. 24R,25(OH)₂D₃ as well as PGE₂ (but not PTH, CT or 1α25(OH)₂D₃) stimulated CKBB in clone ROS 25/1, suggesting that this fibroblast-like clone has some chondroblast-like character. Both PTH and PGE₂ stimulated the brain type isoenzyme of CK (CKBB), although the osteogenic sarcoma cell clones contain a significant proportion of the muscle type of CK (CKMM). Thus, increased CKBB activity can serve as an additional characteristic marker for the action of steroid and polypeptide hormones and for prostaglandins.