THE EFFECT OF VINCRISTINE ON MOUSE JEJUNAL CRYPT CELLS OF DIFFERING CELL AGE: DOUBLE LABELLING AUTORADIOGRAPHIC STUDIES USING3H- AND14C-TdR

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Abstract
The mechanism of action of the alkaloid vincristine (VCR) was investigated in vitro in HeLa [human cervical carcinoma] cells in culture and in vivo in jejunal crypt cells of the mouse. The in vitro experiments with HeLa cells show that VCR affects not only mitotic but also interphase cells. The VCR affected cells continue their passage through the cell cycle undisturbed but after reaching mitosis they are arrested in metaphase. This agrees well with the results obtained by Madoc-Jones and Mauro and Madoc-Jones in synchronized cell cultures. Until now there was no investigation of the mechanism of action of VCR in vivo. This is due to the absence of a suitable technique for synchronization in vivo. The present study is based on a method which permits the assessment of VCR sensitivity as a function of cell age without synchronization in the usual sense. The jejunal crypt epithelium of the normal mouse was double labeled with 3H- and 14C-thymidine (TdR) in such a way as to produce a narrow subpopulation of crypt cells with a maximum age difference of 1 h. On autoradiographs these cells can be distinguished by their characteristic labeling from other cells. As this pseudosynchronized subpopulation passes through the cycle the effect of VCR can be studied, i.e., one can analyze the effect in well-defined time intervals of the cycle. The results show that the effect of VCR is the same in vivo as in vitro. The crypt cells which are affected by VCR in interphase continue their passage through the cycle, but on entering mitosis they are arrested in metaphase. VCR has, at the concentration used in the present study, no effect on the duration of the S and G2 phases. The necrotic cells seen after VCR application are formed from arrested metaphases.