An enzymic defect in ascites-tumor cells* .\lthough glycogen phosphorylase is found in almost all mammalian tissues, greatly reduced phos- phorylase activities recently have been ascribed to ascites tumors' and a solid tumo@. The following llormonall~-tlependent sequence of reactions been proposed for phosphorylase activation in liver and adrenal cortes3-5. ATP, Jig++ Epincphrine Dephosphophosphoryiase Gll~c;,gon . .._...._._.._..._____. -f (Inactive) .\CTH 4 .\tlenosine-j', j'-cyclic phosphate6 .--------------. ~ Dephosphosphophorylase i kinasc (.\TP?) Phosphorylase (active) This communication demonstrates a complete absence of phosphorylase activity in eight different types of tumors, The cells were found to contain phosphorylase-activating enzymes but lacked specificallv both active and inactive forms of phosphorylase. and therefore, they did not respond physiologicallv to cpinephrine or glwxgon. The followmg ascitcs tumors were used: Hepatoma. Ehrlich carcinoma, lymphocytic leuke- mm. plasma cell, mast cell, Krcbs-2 carcinoma. and sarcoma-37; also the HeLa carcinoma grown in tissue culture. Freshly harvested tumors contained \ery low levels of glycogen, approximating .5 j~molrs glucose equivalents/g protein, as determined analvtically by the method of STADIE, H.IUGA~RD .\SD .\I.ARsH'. Histochemical examination with HIO,-Schiff reagent indicated that the glvcogen was confined cntirclv to normal pol!.morphonuclear leukocytes which comprised I-Z `{,`of the ascitcs-cell populations. .4scites-tumor cells grown ilz yizw and the HeLa carcinoma grown in tissue culture contained no detectable glycogen. In contrast, normal mouse-liver epithe- lial ~11~ grown in tissue culture are known to contain glycogen". The phosphorylase activities of whole, undialyzed tumor and normal mouse-liver homogen- ates were determined bv the method of SUTHERLAND ASD \VOSILAIT'. An active phosphorylase was found in mouse-liver homogenates (1.53 jhmoles phosphate released/mg protein/to min). Phospha- tase activity- was negligible. Grentlv decreased phosphorylase activities were found in hepatoma homogenates (< o. I /tmole phosphate/mg protein/r0 min). Optimal activity was obtained between pH 0-7. .iddition of i'-.\JIP did not result in increased phosphorylase activitv, nor did the use of a wide varier\- of homogenization techniques. Similar results were obtained with the previously hsted tumors. .i histochemical phosphorylase assay9 was applied to the hepatoma, Ehrlich carci- noma and Krebs-2 carcmoma. .\n active phosphorvlase was found in the polymorphonuclear leukoc\tes: none was present in the tumor cells. The phosphorylase reaction was then measured in the keverse direction. from glvcogen to G-I-P, bv following the disappearance of added glycogen * The following abbreviations are used: j'-XJIP, adenylic acid : XTP, adenosine triphosphate; G-i-P, glucose-r-phosphate; G-6-P, glucose-6-phosphate; TC.1, trichloroacetic acid; TRIS, tris (h~drosymethvl) aminomethane; DPP kinase, dephosphophosphorylase kinase. 204 PRELIMINT~RY NOTES VOL. 30 (195s) from the medium. Normal mouse-liver and -muscle homogenates rapidly degraded glycogen; tumor homogenates did not degrade glycogen appreciably. The anaerobic utihzation of G-I-P and G-6-P by tumor homogenates was compared manometrically. G-r-I' was utilized as effectively as G-6-P, indicating phosphoglucomutase activity (zo-30,~tl CO,lmg dry wt. tumor homogenate/h). Addition of 50 ,ug epinephrine. HCljml medium to intact Ehrlich cells and jo /