Hypophosphatemic factor in oncogenic osteomalacia
A Nelson, J Hogan, RS Mason
(collaborators: BG Robinson, Dept of Medicine; R. Baxter, Kolling Institute, RNSH, Ingrid Holm, Boston Childrens Hospital; R Redell, A Chang, Children's Medical Research Institute, Sydney)

Oncogenic osteomalacia is a condition of renal phosphate wasting causing impaired bone mineralization in the presence of a connective tissue tumour. A factor was identified which inhibits renal phosphate uptake, and which is secreted into the culture medium by a cell line derived in this Laboratory from such a tumour. Although the factor was shown to have some properties similar to parathyroid hormone, it was shown not to be either parathyroid hormone or parathyroid hormone-related peptide or a new putative phosphate regulator, stanniocalcin. A tumour cell cDNA library was prepared and strategies to screen this library are being developed. Preliminary experiments to characterise the phosphate-active factor indicate that it is stable to heat and trypsin treatment and has a relatively low molecular weight.