The present study was conducted to elucidate the molecular mechanism underlying the transient increase in circulating squamous cell carcinoma antigen (SCC Ag) levels in response to CIS-diamminedichloroplatinum (CDDP) infusion using an in vitro model. The uterine cervical squamous carcinoma CaSki cells were cultured for 72 h after 3 h exposure to 5.0 microg/ml CDDP. The effects of CDDP exposure on the proliferative activity and apoptosis in cultured CaSki cells were determined by bromodeoxyuridine (BrdU) uptake and cell counting and by the TUNEL assay, respectively. SCC Ag levels in cultured CaSki cells and culture media were determined with the use of SCC-RIA kit. The expression of SCC Ag-1 mRNA and SCC Ag-2 mRNA in cultured CaSki cells was assessed using semiquantitative RT-PCR with Southern blot analysis. The number of BrdU-positive CaSki cells significantly decreased 6 h after exposure to CDDP, whereas the apoptosis-positive rate of cultured CaSki cells significantly increased 12 h after the CDDP exposure. The number of cultured CaSki cells significantly decreased 72 h after the CDDP exposure. The total SCC Ag protein levels in both cultured CaSki cells and the culture media after the 3-hour CDDP exposure increased in a time-dependent manner during the subsequent incubation for 48 h. Semiquantitative RT-PCR revealed that the expression levels of both SCC Ag-1 and SCC Ag-2 mRNA increased (1.7- and 2.7-fold, respectively) 12 h after the exposure to CDDP relative to those before the subsequent cultures. Exposure of uterine cervical squamous carcinoma CaSki cells to CDDP resulted in a transient increase in SCC Ag protein and mRNA expression in those cells during the initial 12 h after the exposure, being associated with decreased proliferative activity and increased apoptosis of those cells.
Copyright 2003 S. Karger AG, Basel