title: DHCR24 gene expression is upregulated in melanoma metastases and associated to resistance to oxidative stress-induced apoptosis.
abstract: The DHCR24 gene encoding for the 3beta-hydroxysterol delta24-reductase, an oxidoreductase involved in cholesterol biosynthesis, was isolated by subtractive hybridization as highly expressed in a short-term melanoma cell line derived from a cutaneous metastases (S/M2) compared to that obtained from the autologous primary tumor (S/P). DHCR24 (alias seladin-1, diminuto/dwarf1 homolog) has been reported to act as an antiapoptotic factor in neurons. Gene expression analysis by Northern blot confirmed that DHCR24 was 5-fold upregulated in S/M2 compared to S/P cells. High levels of DHCR24 gene expression were detected in 13/25 melanoma metastases and in 1/7 primary melanomas by real-time PCR, indicating that upregulation of this gene may occur in melanoma progression. In S/M2 cells, high DHCR24 gene expression associated with resistance to apoptosis triggered by oxidative stress induced by exposure to hydrogen peroxide. DHCR24 gene transfer was shown to protect melanoma cells from H2O2-induced cytotoxicity. Although higher cholesterol levels were shown in S/M2 cells compared to S/P cells, DHCR24 gene transfer did not increase cholesterol content. To evaluate whether DHCR24 acts as an antiapoptotic factor in melanoma metastases, the cytotoxic effect of chemotherapeutic agents was tested in DHCR24 transfectants and in the presence of a DHCR24 inhibitor, U18666A. High DHCR24 gene expression in transfectants did not result in a higher resistance to cytotoxic agents; treatment with U18666A was cytotoxic in S/P cells with a lower DHCR24 content and showed additive cytotoxic effect only when associated with H2O2 and not with cysplatin or etoposide, indicating that the DHCR24 protective effect is exerted through an oxidative stress-specific mechanism.
authors.affiliation: Unit of Melanoma Genetics, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy.
authors.forename: Delia
authors.initials: D
authors.lastname: Di Stasi
authors.forename: Viviana
authors.initials: V
authors.lastname: Vallacchi
authors.forename: Valentina
authors.initials: V
authors.lastname: Campi
authors.forename: Tiziana
authors.initials: T
authors.lastname: Ranzani
authors.forename: Maria
authors.initials: M
authors.lastname: Daniotti
authors.forename: Elena
authors.initials: E
authors.lastname: Chiodini
authors.forename: Silvia
authors.initials: S
authors.lastname: Fiorentini
authors.forename: Isabell
authors.initials: I
authors.lastname: Greeve
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prinetti
authors.forename: Licia
authors.initials: L
authors.lastname: Rivoltini
authors.forename: Marco A
authors.initials: MA
authors.lastname: Pierotti
authors.forename: Monica
authors.initials: M
authors.lastname: Rodolfo
mesh_terms: D000736:Androstenes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis; D015152:Blotting, Northern; D002784:Cholesterol / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008545:Melanoma / Q000235:genetics* / Q000556:secondary; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012878:Skin Neoplasms / Q000235:genetics* / Q000473:pathology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D000736:Androstenes; D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D009419:Nerve Tissue Proteins; D016877:Oxidants; D012333:RNA, Messenger; C006261:3-beta-(2-(diethylamino)ethoxy)androst-5-en-17-one; D005047:Etoposide; D002784:Cholesterol; D006861:Hydrogen Peroxide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C437069:3beta-hydroxysterol delta24-reductase; C499055:DHCR24 protein, human; D002945:Cisplatin