ABSTRACT
The tumor suppressor p53 protein induces apoptosis in response to various kinds of DNA damage in normal cells, but it is still unclear whether or not apoptosis induced by DNA damage correlates with the p53 status in tumor cells. We determined the status of p53 by functional analysis of separated alleles in yeast in five human colon cancer cell lines, SW-480, SW-620, DLD-1, COLO320 and LS174T and investigated whether p53 is necessary for apoptosis and cell cycle arrest after treatment of the cells with a DNA-damaging agent, etoposide (VP-16), or gamma-irradiation. Of these cell lines, only LS174T expresses a functional p53. Apoptosis was detected in SW-480 and COLO320 cell lines, but not in the other cell lines, including LS174T cell line with a normal p53 function. Furthermore, cell cycle analysis revealed accumulation in the G2M phase preceding induction of apoptosis in SW-480 and COLO320 cells, but not in the other cells. These results suggest that apoptotic induction by DNA damage is not necessarily related to p53 status and that induction of p53-independent apoptosis following DNA damage may correlate with G2M arrest in the cell cycle, at least in the colon cancer cell lines used in this study.
Subject(s)
Apoptosis , Colonic Neoplasms/pathology , DNA Damage , Tumor Suppressor Protein p53/physiology , Cell Survival/drug effects , Cell Survival/radiation effects , DNA Fragmentation , Etoposide/pharmacology , G2 Phase , Gamma Rays , Humans , Mitosis , Tumor Cells, CulturedABSTRACT
Electroporation was applied in vitro and in vivo in the treatment of human colorectal cancer cell lines to study whether it can enhance the effect of bleomycin (BLM), 5-fluorouracil (5-FU) and cis-platinum (CDDP). We used LS174T and Colo320 cells derived from human colon cancer as target cells in this study. When the LS174T cells were used as target cells, the IC50 of BLM decreased to 10(-3) times, while that of 5-FU decreased to only about one fifth with the application of electric current. In the case of the Colo320 cells, the IC50 of BLM and 5-FU were about one hundredth and a half, respectively. The effect of CDDP was not enhanced with electric current. In vivo experiments were also performed using LS174T cells transplanted subcutaneously (s.c.) into nude mice. By treatment with intravenously (i.v.) administered BLM and simultaneous application of the electric current, tumors were markedly decreased in size after three weeks.
Subject(s)
Antineoplastic Agents/toxicity , Antineoplastic Agents/therapeutic use , Colorectal Neoplasms/drug therapy , Electroporation , Animals , Bleomycin/therapeutic use , Bleomycin/toxicity , Cell Division/drug effects , Cisplatin/therapeutic use , Cisplatin/toxicity , Colorectal Neoplasms/pathology , Fluorouracil/therapeutic use , Fluorouracil/toxicity , Humans , Male , Mice , Mice, Nude , Transplantation, Heterologous , Tumor Cells, CulturedABSTRACT
The effects of shock waves in combination with various anti-cancer agents i.e. Bleomycin (BLM), Cisplatin (CDDP) and 5-fluorouracil (5-FU) on tumor cells suspended in media containing these agents were examined. GCIY cells derived from human gastric cancer and LS 174T and SW480 cells derived from human colon cancers were used for in vitro experiments; GCIY and SW480 cells were also transplanted into nude mice for in vivo study. It was only with BLM that enhancement was evident in all three cell lines, with a degree of chemotherapeutic enhancement proportional to the amount of shock wave energy applied. Ladder formation of DNA in GCIY cells was observed only when treated with both BLM and shock waves in combination. When SW480 and GCIY cells transplanted into the backs of nude mice were treated with a combination of intravenously (i.v.) injected BLM and regional exposure to shock waves, a significant enhancement of chemotherapeutic effects was observed in terms of the tumor growth curve.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Lithotripsy , Animals , Cisplatin/therapeutic use , Combined Modality Therapy , Fluorouracil/therapeutic use , Humans , Male , Mice , Mice, Nude , Neoplasm Transplantation , Tumor Cells, CulturedABSTRACT
Cell surface MHC H-2K antigens expressed on various types of B16 melanoma cells of C57BL/6 mouse origin were stained by the avidin-biotinylated enzyme complex (ABC) technique. The low metastatic B16F1 cell line, which demonstrates high levels of H-2K antigen, stained strongly, while the high metastatic B16F10 cell line with no H-2K antigen was not stained. Metastatic colonies which developed in lungs after intravenous (i.v.) injection proved to be negative in both cases. Therefore, in consideration of decreased expression of H-2K antigen in the metastatic process both in vivo and in vitro, antisense oligonucleotides against the class I H-2K gene were transfected into B16F1 cells with H-2K antigens. Subsequent immunohistochemical assessment revealed lack of H-2K antigen expression in the cells, but nevertheless they still could not metastasize to lungs when i.v. injected. This may suggest that any link between the two is not directly causal.
