Transcriptional regulation of TNF family receptors and Bcl-2 family by chemotherapeutic agents in murine CT26 cells.
Various chemotherapeutic agents have been shown to sensitize cancer cells to members of the tumor necrosis factor (TNF) family. However, it is unclear whether sensitization by chemotherapeutic agents involves the transcriptional regulation of apoptosis-related genes. In this study, we investigated mRNA regulation of TNF family receptors and Bcl-2 family members after treating the murine colon cancer cell line, CT26, with various apoptosis inducers. We found that treatment with cycloheximide, a protein synthesis inhibitor, remarkably increased CD40 mRNA levels by semi-quantitative RT-PCR. Other protein synthesis inhibitors, such as anisomycin and emetine, also enhanced CD40 mRNA expression, which was significantly blocked by a NF-kappaB antagonist and a p38 MAP kinase antagonist. After treatment with cycloheximide, and further cultivation in fresh medium, CD40 protein levels were found to increase by flow cytometry. Additionally, we found that cycloheximide treatment appeared to downregulate the Bcl-xL mRNA level but not the Bax mRNA level by RNase protection assay. Because the upregulation of CD40 mRNA and the downregulation of Bcl-xL correlated with CT26 cell death, our results suggest that chemotherapeutic agents, including cycloheximide, may exert their synergistic effects on the TNF family treatment of cancer cells by regulating the mRNA levels of apoptosis-related genes.
Choi
Kyoung-Han
KH
Department of Pathology, Tumor Immunity Medical Research Center and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
Choi
Hye Young
HY
Ko
Jae-Kyun
JK
Park
Sung-Shin
SS
Kim
Yong-Nyun
YN
Kim
Chul-Woo
CW
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D019013:CD40 Antigens / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D003513:Cycloheximide / Q000494:pharmacology; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
D019013:CD40 Antigens; D011500:Protein Synthesis Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D000841:Anisomycin; D003513:Cycloheximide; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases