Cell cycle-related signaling pathways modulated by peripheral benzodiazepine receptor ligands in colorectal cancer cells.
Specific ligands of the peripheral benzodiazepine receptor (PBR) have been shown to induce both apoptosis and G1/G0 cell cycle arrest in colorectal cancers. The signaling pathways leading to cell cycle arrest are still unknown. Using cDNA array technology, we identified signaling molecules involved in cell cycle arrest induced by the PBR ligands FGIN-1-27 and PK 11195. Differential gene expression was confirmed by semi-quantitative RT-PCR or Western blot analysis of gene products. The PBR ligand-mediated signaling involved the upregulation of the cyclin-dependent kinase inhibitors p21WAF1/CIP1 and p27Kip1, cdc16, and the cell cycle inhibitors gadd45 and gadd153, the downregulation of the cyclins D1 and B1, as well as the inactivation of ERK1/2. The p21-deficient colorectal cancer cell line HCT116 p21-/- was significantly less sensitive to PBR ligands than the parental HCT116 wild-type cells, demonstrating the functional involvement of p21WAF1/CIP1 in PBR ligand-mediated G1 arrest. This study thus revealed PBR ligand-triggered signaling pathways leading to cell cycle arrest. Moreover, we showed the functional implication and interaction of differentially expressed gene products and provided a model of signaling pathways involved in PBR ligand-induced G1 arrest. These results form the basis for future PBR ligand-mediated therapeutic approaches.
Medical Clinic I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, 12200 Berlin, Germany.
Kerstin
K
Maaser
Andreas P
AP
Sutter
Antje
A
Krahn
Michael
M
Höpfner
Patricia
P
Grabowski
Hans
H
Scherübl
D015153:Blotting, Western; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism*; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D019938:Cyclin D1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D016193:G1 Phase; D005786:Gene Expression Regulation; D006801:Humans; D008024:Ligands; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D011061:Poly A / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011963:Receptors, GABA-A / Q000737:chemistry*; D016192:Resting Phase, Cell Cycle; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D015854:Up-Regulation
C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018076:DNA, Complementary; D008024:Ligands; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D011061:Poly A; D012313:RNA