Europ. J. Cancer Vol. 15, pp. 1151 1158. 0014-2964/79/0901-1151 $02.00/0 © Pergamon Press Ltd. 1979. Printed in Great Britain Structural and Functional Correlations Parathyroid Hormone Responsive Transplantable Osteogenic Sarcomas* in j. c. E. UNDERWOOD,] R. A. MELICK,+ + R. S. LOOMES,t V. M. DANGERFIELD,]. A. CRAWFORD,§ L. COULTON,§ P. M. INGLETON¶ and T. J. MARTIN§ ].Departments of Pathology, §Chemical Pathology and ¶Zoology, University of Sheffield, Sheffield S10 2RX, England +Department of Medicine, University of Melbourne, Royal Melbourne Hospital, PO 3050, Victoria, Australia Abstract--Bone tumours induced in rats by repeated injections of 32p-orthophosphate exhibit morphological characteristics of osteogenic differentiation after successive transplantation; stromal mineralization is a constant feature. Cell membranes isolated from the transplantable tumour possess a parathyroid hormone (PTH) and pro- staglandin (PGE1, PGE2, PGF2~) responsive adenylate cyclase. Basal cyclic AMP (cAMP) concentrations and P T H responsiveness are greatest in the cellular poorly mineralized peripheral zones of the tumour, cAMP and P T H induce a cytoplasmic contraction response in cultured tumour cells and the P T H responsive adenylate cyclase is retained by the cells even after repeated subculture. A direct correlation exists between tumour size and serum alkaline phosphatase activity. INTRODUCTION THERE are few model tumour systems in which well characterized biochemical proper- ties of the neoplastic cells correlate with the structural and functional properties of the neoplastic tissue. We present in this paper our experience with a series of radiation induced osteogenic sarcomas, transplantable in the rat, that exhibit several stable functional and structural differentiated characteristics. Light and electron microscopic appearances, hor- mone responsiveness, alkaline phosphatase sec- retion and cultural properties are described. Some of the results are relevant to the ap- parent ambiguous relationship between cyclic nucleotide concentrations and neoplastic growth [1-3]. We also confirm the value of serum alkaline phosphatase activity as a possible marker for osteogenic neoplasia [4]. MATERIALS AND METHODS Tumour induction and transplantation Sprague-Dawley rats were injected intrape- ritoneally with carrier-free 32P-orthophos- Accepted 23 February 1979. *Supported by the Yorkshire Council of the Cancer Research Campaign. phate according to a schedule ofBensted etal. [5]. An initial injection of 1 # Ci/g body weight was followed, at 2 week intervals, by subsequent injections of 0.6#Ci/g body weight. Bone tumours appeared in roughly half of the animals, usually at the distal end of the femur, within 6-9 months. For transplantation, small pieces of tumour tissue were forced through a 60-mesh stainless steel gauze and injected subcutaneously (s.c.) into the flank. Alternatively, cells were disper- sed by digestion of tumour fragments with hyaluronidase and collagenase [6, 7] and in- jected (106-3 x 106 cells) into the flank. Histological studies Slices of tumour tissue were fixed either in Bouin's fluid or, if undecalcified sections were to be prepared, in neutral 10% formalin. Undecalcified sections were stained to de- monstrate mineralisation by Von Kossa's method. The relative volumetric composition of dif- ferent zones within a tumour was derived from area measurements obtained by point counting tissue sections [8]. A regular 100 point grid lattice was mounted in the focal plane of the microscope eyepiece and the proportion of points coincident with the ima- 1151