title: Effect of tunicamycin, an inhibitor of protein glycosylation, on division of tumour cells in vitro.
abstract: We determined the effect tunicamycin (TM), an inhibitor of protein glycosylation, had on cells in vitro that were derived from solid and ascites variants of a chemically induced rat hepatoma. Using flow microfluorometry (FMF), labelling index (LI), and population-doubling time assays, we monitored the progression of cells through the cell cycle after treatment with TM. Cells in monolayer culture were first incubated in 0.05 or 0.10 micrograms TM/ml medium for 24 h then analysed or given fresh medium without TM and allowed to recover for 6-24 h. Exposing cells to 0.05-0.50 micrograms TM/ml medium did not affect the percentage of viable cells as determined using the Trypan Blue exclusion procedure. However, continuous exposure to 0.05 micrograms TM/ml medium did affect the population-doubling times of both the ascites and solid variants, and the ascites tumour cells were more sensitive than the solid tumour cells. TM reversibly inhibited hepatoma cells from entering S phase of the cell cycle. After exposure to TM for 24 h, the percentage of solid tumour cells in vitro in S phase decreased to 19%, as determined by autoradiography of tritiated-thymidine-labelled cells, and to 21% as determined by FMF; 49% of untreated solid tumour cells were in S phase. The percentage of ascites tumour cells in vitro decreased to 12% after exposure to TM for 24 h; 37% of untreated cells were in S phase. We concluded that TM can inhibit division of rat hepatoma cells in vitro by blocking them in G1 phase of the cell cycle.
mesh_terms: D000818:Animals; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005434:Flow Cytometry; D005944:Glucosamine / Q000031:analogs & derivatives*; D007399:Interphase / Q000187:drug effects; D008114:Liver Neoplasms, Experimental / Q000473:pathology; D051381:Rats; D013997:Time Factors; D014415:Tunicamycin / Q000494:pharmacology*
chemical_list: D014415:Tunicamycin; D005944:Glucosamine