title: PROX1 overexpression inhibits protein kinase C beta II transcription through promoter DNA methylation.
abstract: Prospero-related homeobox 1 (PROX1) is important for embryonic organ formation and differentiation, and changes in PROX1 activity were recently associated with cancer. To address the PROX1 roles in tumorigenesis, we established cells stably overexpressing PROX1 using the human cervical cancer cell line, HeLa. Overexpression of PROX1 reduced cell proliferation and the rate of tumor formation as compared with controls. Comparison of gene expression profiles between PROX1-overexpressing and mock-transfected cells revealed that the expression of protein kinase C βII (PRKCB2) is down-regulated in PROX1-overexpressing cells. A PRKCB inhibitor suppressed cell growth of control cells more than PROX1-expressing cells. Analysis of the 5'-promoter of PRKCB revealed that a region between -110 bp and the first exon contains two Sp1 binding sites and is important for transcriptional regulation of PRKCB. The inhibition of Sp1 transcription factor resulted in down-regulation of PRKCB2 protein levels. Treatment with a demethylating agent, 5-aza-2'-deoxycytidine, restored PRKCB2 mRNA expression in PROX1-expressing cells, suggesting that the 5'-promoter of PRKCB is methylated in these cells. Actually, it was found that a CpG island in this region, in particular a CpG site overlapping with the distal Sp1 site, was hypermethylated and direct Sp1 binding to this region was inhibited in PROX1-overexpressing cells. Thus, the suppressive effect of PROX1 on cell growth and tumor formation might be partially mediated by PRKCB2 via altered methylation of its promoter.
authors: Department of Hematology/Oncology Research, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Japan.
authors: Kazumi
authors: K
authors: Hagiwara
authors: Hiromi
authors: H
authors: Ito
authors: Takashi
authors: T
authors: Murate
authors: Yasuhiko
authors: Y
authors: Miyata
authors: Haruhiko
authors: H
authors: Ohashi
authors: Hirokazu
authors: H
authors: Nagai
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D019175:DNA Methylation; D000077209:Decitabine; D015536:Down-Regulation / Q000187:drug effects; D020869:Gene Expression Profiling; D045325:HCT116 Cells; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D064546:Protein Kinase C beta; D016329:Sp1 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein
chemical_list: D018398:Homeodomain Proteins; D007211:Indoles; D016329:Sp1 Transcription Factor; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D000077209:Decitabine; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D001374:Azacitidine; C504878:enzastaurin