In this study the relationship between sisterchromatid exchange (SCE) frequency and cell survival was examined in 3 neoplastic epithelial cell lines originating in salivary glands and maxillary sinus of the human, which were exposed to 4 antineoplastic drugs, cis-diaminedichloroplatinum (cis-DDP), mitomycin C (MMC), 5-fluorouracil (5-Fu) and bleomycin (BLM).
These cells included 2 salivary gland adenocarcinoma cell lines (HSG and HSY) and 1 maxillary sinus squamous carcinoma cell line (OKK). All of the cells were grown in Eagle's minimal essential medium (MEM) supplemented with 10% newborn calf serum and 2mM L-glutamine in the presence of 5% CO2 in an incubator at 37°C. Search for SCE of cells was performed according to the modification of fluorescent plus Giemsa method described by Perry and Wolff.
The respective doubling times for HSG and HSY cells were 21.4±2.5 and 39.1±8.0 hours, while the doubling time for OKK cells was 30.2±6.5 hours. To make permanent cytological preparations of SCE, the cells were cultured in the growth medium containing 1μg/ml bromodeoxyuridine (BUdR) in a 5% CO2 incubator at 37°C for 62 hours during which time 2 rounds of replication occurred.After further cultivation for 1 hour in the presence of 10-5M colcemid, the cells were subjected to SCE analysis.
The mean number of spontaneous SCEs per chromosome of HSG cells (0.18±0.05; mean±SD, n=40, P<0.05), HSY cells (0.19±0.07, n=42, P<0.05) and OKK cells (0.15±0.06, n=31, P<0.05) was significantly increased as compared with that of human peripheral lymphocytes from normal controls subjects (0.10±0.06, n=20). When the cells were cultured for 62 hours in growth medium containing 1μg/ml BUdR and various concentrations of antineoplastic drugs, both cis-DDP and MMC induced high frequencies of SCEs in all of the examined cells.
Although treatment of these cells with 5-Fu resulted in an induction of moderate frequency of SCEs, BLM did not increase frequency of SCEs. Especially, the frequency of cis-DDPinduced SCEs was higher in OKK cells than in HSG and HSY cells, whereas an increase in the frequency of MMC-induced SCEs in HSG and HSY cells as compared with that in OKK cells was observed.
Moreover, the frequecy of SCEs induced by cis-DDP or MMC was intimately associated with reduced cell survival.
