title: Human melanomas of fibroblast and epithelial morphology differ widely in their ability to synthesize retinyl esters.
abstract: Reduced retinyl ester synthesis has been associated with several forms of cancer; we therefore proposed studying melanoma development from the perspective of this biochemical pathway. Cultures of human melanoma cells with fibroblastoid morphology showed negligible retinyl ester synthesis; in sharp contrast, those with epithelioid morphology were capable of retinol esterification. Further, isolated proliferating epidermal melanocytes (HFSC/2) esterified retinol, whereas proliferating normal skin fibroblasts (F:CCD-1121.Sk) did not. A primary site cutaneous melanoma and its metastatic match (both of epithelioid morphology) were capable of retinol esterification, while a matched fibroblastoid tumor pair did not synthesize retinyl esters; nevertheless, LRAT (lecithin:retinol acyltransferase) protein was found in microsomal fractions from all four tumors. A mutation screen in the LRAT coding region and adjacent intronic sequences revealed several novel mutations in these melanomas as well as in HFSC/2 and F:CCD-1121.Sk cells: a single nucleotide polymorphism in exon 1(37A-->G), a silent mutation in exon 2a (188 A-->G/186 G-->A), and an insertion in the 5'UTR (9-10insC). CRBP-1 basal expression was present in the HFSC/2, and in both sets of matched tumor pairs; however, steady-state levels in the fibroblastoid melanoma pair were one-third that found in the epithelioid matched tumor pair. Co-culture of human primary site epithelioid melanoma with proliferating normal human skin fibroblasts abrogated retinol esterification within 96 h and increased the expression of the active form of TGFbeta-1 by 2.4-fold. A concomitant 3.2-fold downregulation of CRBP-1 expression took place. This is the first study to (1) demonstrate an association between retinyl ester synthesis and cutaneous melanoma morphological phenotypes; (2) suggest the existence of a soluble, diffusible inhibitor of the retinol esterification pathway; (3) report the ability of the isolated, proliferating human epidermal melanocyte to esterify retinol; and (4) provide evidence of DNA variants in the coding region of LRAT.
authors.affiliation: Laboratory of Cellular Carcinogenesis and Tumor Promotion, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA.
authors.forename: Denise Perry
authors.initials: DP
authors.lastname: Simmons
authors.forename: Fausto
authors.initials: F
authors.lastname: Andreola
authors.forename: Luigi M
authors.initials: LM
authors.lastname: De Luca
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D001685:Biological Factors / Q000378:metabolism; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D004058:Diffusion; D004847:Epithelial Cells / Q000378:metabolism; D004951:Esterification; D004952:Esters / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D005796:Genes; D006801:Humans; D007438:Introns; D008545:Melanoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008861:Microsomes / Q000201:enzymology; D016254:Mutagenesis, Insertional; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D020641:Polymorphism, Single Nucleotide; D012177:Retinol-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D054840:Retinol-Binding Proteins, Cellular; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000502:physiology; D053773:Transforming Growth Factor beta1; D014407:Tumor Cells, Cultured / Q000378:metabolism; D014801:Vitamin A / Q000378:metabolism*
chemical_list: D001685:Biological Factors; D004952:Esters; D009363:Neoplasm Proteins; C518456:RBP1 protein, human; D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014801:Vitamin A; D000217:Acyltransferases; C056942:lecithin-retinol acyltransferase