lysophosphatidylinositol and phosphatidylinositol-4-phosphate

The effects of diabetes and insulin administration on certain aspects of phosphoinositide metabolism in R3230AC mammary tumors were studied in vivo. Three weeks after diabetes was induced by streptozotocin, [3H]myoinositol incorporation into PI, PIP and PIP2 was increased in R3230AC tumors, whereas the formation of [3H]IP, [3H]IP2 and [3H]IP3 was decreased. Administration of protamine zinc insulin (3IU, twice daily, for 3 days) to diabetic rats decreased [3H]myoinositol incorporation into phosphoinositides and inositol phosphates in these mammary tumors. The R3230AC tumor from insulin-treated diabetic hosts had lower levels of unmetabolized [3H]-myoinositol compared to tumors from diabetic animals. Enzymatically-dissociated tumor cells from insulin-treated animals displayed decreased myoinositol transport in vitro. These findings suggest that the insulin-induced decrease in the turnover of inositol lipids in vivo in R3230AC mammary tumors could have resulted from the decreased level of [3H]myoinositol in these cells.

Topics: Adenocarcinoma; Animals; Biological Transport, Active; Diabetes Mellitus, Experimental; Female; Inositol; Insulin; Lysophospholipids; Mammary Neoplasms, Experimental; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol Phosphates; Phosphatidylinositols; Rats; Rats, Inbred F344