Expression of cathepsin L in human tumor cells is under the control of distinct regulatory mechanisms.
Cathepsin L, a cysteine protease, is overexpressed in human tumor cells and plays a major role in melanoma progression. Our aim was herein to identify molecular mechanisms, which contribute to its overexpression. We found that cathepsin L protein expression correlated with mRNA level in tumor cells. Therefore, we focused on mechanisms involved in cathepsin L mRNA regulation. CpG island was localized in the 5' region of cathepsin L gene that encompassed regulatory regions identified as essential for promoter activity. CpG dinucleotides, not methylated in any melanoma cells analysed, were methylated in a B lymphoma cell line, which poorly express cathepsin L. Our data demonstrate that in lymphoma cells, cathepsin L silencing was methylation-dependent. Furthermore, gene amplification was involved in cathepsin L overexpression in one melanoma cell line, while transcriptional mechanisms but not mRNA stability are responsible of cathepsin L overexpression in others melanoma cells. In addition, NF-Y, Sp1, Sp2 and Sp3 transcription factors, essential to basal cathepsin L transcription, are not directly involved in overexpression. Thus, our data provides the first demonstration that cathepsin L expression in tumor cells is under the control of distinct molecular mechanisms.
Jean
D
D
INSERM U.672 (ex U.354), Immunochimie des Régulations Cellulaires et des Interactions Virales, Bâtiment G8, Génopole d'Evry, Evry Cedex, France. jean354@genopole.evry.inserm.fr
Rousselet
N
N
Frade
R
R
D000818:Animals; D001483:Base Sequence; D023081:CCAAT-Binding Factor / Q000235:genetics / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000096:biosynthesis* / Q000235:genetics*; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000096:biosynthesis* / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D008223:Lymphoma; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D051703:Sp Transcription Factors / Q000235:genetics / Q000378:metabolism
D023081:CCAAT-Binding Factor; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D051703:Sp Transcription Factors; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C534278:Ctsl protein, mouse