Suiciding of Hematopoietic and Tumor Clonal Cells by Tritiated Nucleosides In Vitro: Brief Communication

Abstract

Four colony-forming cell (CFC) types were compared to determine their sensitivity in vitro to doses of tritiated nucleic acid precursors; clonal cultures used were monocytic CFC's and lymphocytic CFC's (CFC-L) from mouse explants [(C57BL/6 × DBA/2)F, mice] and P815 mastocytoma and 5178Y lymphoma CFC's from passaged mouse cell lines. Surviving colonies indicated progeny of precursor cells not suiciding from (or not incorporating) a particular tritiated nucleoside. Several general patterns of suiciding were observed. 1) [³H]Adenosine (Ado) and [³H]uridine (Urd) caused the lowest suiciding ratios (³H-treatment/control) in all four clonal cultures. [³H]Guanosine (Guo) and [³H]deoxyguanosine (dGuo) were the least inhibitory suiciding agents on colony formation in both tumor and hematopoietic cultures. 2) CFC-L development was reduced to a greater extent by [³H]Guo, [³H]dGuo, [³H]Urd, [³H]deoxyuridine, and [³H]Ado than were the other three types of CFC's. CFC-L cultures were also the only cell type that consistently was more sensitive to doses of tritiated ribosides than to doses of corresponding deoxysides. 3) When suiciding patterns were compared, a greater correlation of suiciding ratios was observed between the two tumor cell lines than between the two hematopoietic clonal lines. That is, equivalent doses of each tritiated precursor gave rise to similar suiciding ratios for both P815 and 5178Y CFC's. The combination of clonal assays with suiciding techniques described here represented a novel approach to the biochemical analysis of precursor cells.