Observation of myo-inositol 1,2-(cyclic) phosphate in a Morris hepatoma by 31P NMR.

We have identified an unusual resonance at 16.5 ppm in the 31P NMR spectrum of a Morris (7777) hepatoma grown in the inguinal fossa of a Buffalo rat as myoinositol 1,2-(cyclic) phosphate. This compound has been observed in all of the 32 tumors examined as well as in cultured cells derived from the tumor, but it has not been observed in normal rat tissues. Its level in the aqueous phase of chloroform/methanol/water extracts of the tumor is 70 +/- 40 nmol/g, wet weight (n = 4). The presence of a breakdown product of phosphatidylinositol at such high levels in a fast growing tumor may provide an important clue for understanding the metabolic defect that results in the malignant growth of this tumor.