The Assessment of the Chemotherapeutic Effects of Vinca Alkaloids by Immunofluorescence and Flow Cytometry

The effects of the vinca alkaloids on the rates of DNA synthesis in the human pancreatic carcinoma line, MIA Pa Ca-2 have been studied by a new technique for measuring cell kinetics and DNA synthesis by flow cytometry and immunofluorescence. The method employs a monoclonal antibody that is highly specific for bromodeoxyuridine or iododeoxyuridine. The drugs vincristine and vindesine do not appear to have a direct effect on DNA synthesis rate across S phase, whereas DHAD, a compound that has been found previously to affect DNA synthesis, does appear by this technique to inhibit DNA synthesis at specific segments of S phase. That vincristine does not block cells in S phase by inhibiting DNA synthesis is borne out of the observation that cells blocked in S or G2 + M can still incorporate BrdUrd at a high rate in these phases of the cell cycle.