FLOW CYTOMETRIC QUANTITATION OF C-MYC AND P53 PROTEINS IN BOVINE PAPILLOMAVIRUS TYPE 1-TRANSFORMED PRIMARY MOUSE FIBROBLASTS

Bovine papillomavirus type 1 (BPV-1)-transformed mouse fibroblast cell lines were analyzed via flow cytometry (FCM) for expression of p53 an d c-myc proteins along with their DNA content. In comparison to the no ntransformed control cell line, significantly elevated levels of both the p53 and the c-myc protein were present in some but not all of the transformed cell lines. Quantitation of p53 and c-myc proteins in cell lines containing BPV-1 DNA revealed that the tumorigenic cell lines e xpressed higher levels of both the p53 (P = 0.0034; Mann-Whitney U tes t) and the c-myc protein (P = 0.0039; Mann-Whitney U test) as compared to the nontumorigenic cell lines. On average, at least 9,000-10,000 p 53 or c-myc protein molecules per cell were detected in the transforme d tumorigenic cell lines. These results show that quantitative FCM can be reliably used to detect very low levels (3,000 molecules per cell) of specific protein, and FCM is a useful tool to study the virus-indu ced changes in the levels of nuclear proteins within a cell population and in tumorigenesis. (C) 1994 Wiley-Liss, Inc.