Figure 4.

Expression of DNA repair and cell cycle regulatory genes. Preconfluent cultures of SCC12F cells (15) were given fresh medium supplemented with either 100 μM pTpT (+) or an equal volume of diluent (DMEM) (−). Cells were collected 24, 48, and 72 hr after additions and processed for total RNA. Ten micrograms of RNA from each sample were gel-electrophoresed, transferred to a nylon filter, and probed as described (21) (A–C). The ethidium bromide-stained gel is shown to demonstrate relative loading of the RNA samples (D). Similar results were obtained using normal human fibroblasts (data not shown). Densitometric analysis showed a 2.5- to 3.5-fold increase at one or more time points for all three transcripts in pTpT-treated cells compared with diluent-treated controls.