Quantitation of cell kinetic responses using simultaneous flow cytometric measurements of DNA and nuclear protein

A rapid procedure was developed for the simultaneous flow cytometric analysis of nuclear protein using fluorescein isothiocyanate, and DNA using propidium iodide in isolated nuclei. The staining procedure did not involve centrifugation and was easily adapted to the staining of human peripheral blood lymphocytes stimulated with phytohemagglutinin, EL4 murine lymphoid tumor cells in suspension culture, and R3327-G rat prostatic adenocarcinoma solid tumor specimens. Histograms of unstimulated and PHA-stimulated HPBL perturbed by actinomycin D, hydroxyurea, 3H-TdR, colcemid, or hydroxyurea + colcemid showed that 1) resting, noncycling G1 (G1Q) cells are distinguished from late G1 (G1AB) cells, 2) early G2 (G2A) cells are distinguished from late G2 (G2B) cells, and 3) mitotic cells are distinguished from G2 cells. Treatment with hydroxyurea resulted in a build-up of cells having high nuclear protein content and 2C DNA content (G1AB), while incubation with 3H-TdR caused an increase in the number of cells with high nuclear protein content and 4C DNA content (G2B). Colcemid-blocked mitotic cells were identified as having low nuclear protein content (lower than G2A nuclei) and 4C DNA content. The nuclear DNA/protein histograms of untreated and colcemid-treated log-phase EL4 cells provided information concerning G1A, G1B, S, G2A, G2B, and M. The method was also used to quantitate the response of androgen-sensitive rat prostatic R3327-G tumors to androgen deprivation following castration. Sample preparation and staining for correlated nuclear DNA/protein measurements takes approximately the same amount of time as for single parameter nuclear DNA measurements.