Flow cytometric studies of human osteosarcoma.

A number of recent studies have emphasized the potential value of flow cytometry as a "marker" to assess the malignity and therefore to help predict the biologic behavior of neoplasms, including bone tumors. Using propidium iodide and a home-built flow cytometer, the authors have studied the DNA distribution in 95 patients with osteosarcoma and determined the percentage of cells in diploidy, S-phase, tetraploidy, and aneuploidy. Using these values and a derived one, mean DNA concentration, it was possible to demonstrate the extent of the abnormalities observed in this group of neoplasms and show their severity as compared with the normal pattern. When the data are compared against disease-free survival and total survival, correlations were noted that, although weak, suggested that some patterns were predictive of increased risk of metastasis and death. The effect of treatment could also be assessed by evaluating the pattern before and after chemotherapy and correlating these with survival. It seems likely that with some improvement in technology, flow cytometry will be of value in the future in assessing the prognosis for osteosarcoma and predicting whether treatment has been effective.

p53 functions as a cell cycle control protein in osteosarcomas.

Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae.