title: MART-1- and gp100-expressing and -non-expressing melanoma cells are equally proliferative in tumors and clonogenic in vitro.
abstract: MART-1 and gp100 are prototypical melanoma antigen (Ag), but their clinical use as vaccines or as targets of cytotoxic lymphocytes achieved modest success. Possible explanations could be that as MART-1 and gp100 are melanocyte differentiation Ag, clonogenic Ag-non-expressing cells would be spared by immune effectors, or that clonogenic cells would be intrinsically resistant to cytotoxic lymphocytes. We therefore analyzed the proliferative status of MART-1/gp100-expressing and -non-expressing cells in biopsies, and the clonogenicity and sensitiveness to cytotoxic lymphocytes of the human cutaneous melanoma cell lines MEL-XY1 and MEL-XY3. Analysis of MART-1/gp100 and Ki-67 expression in 22 melanoma tumors revealed that MART-1/gp100-expressing and -non-expressing cells proliferated competitively. MART-1, gp100, tyrosinase, and CD271 expression were studied in MEL-XY1 and MEL-XY3 colonies. At 7 days, colonies displayed positive, negative, and mixed expression patterns. By 14 days, colonies of different sizes developed, showing cells with different clonogenic potential, and Ag were downregulated, suggesting Ag plasticity. Subcloning of MEL-XY1 colonies showed that Ag expression varied with time without interfering with clonogenicity. Finally, clonogenic, MART-1/gp100-expressing cells were lysed by specific CD8 lymphocytes. Thus, MART-1 and gp100 expression and plasticity would not interfere with proliferation or clonogenicity, and clonogenic cells may be lysed by cytotoxic lymphocytes.
authors: Laboratorio de Cancerología, Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires, Argentina.
authors: Mariana
authors: M
authors: Aris
authors: Mariana Rodríguez
authors: MR
authors: Zubieta
authors: Marina
authors: M
authors: Colombo
authors: Juan Martín
authors: JM
authors: Arriaga
authors: Michele
authors: M
authors: Bianchini
authors: Myriam
authors: M
authors: Alperovich
authors: Alicia I
authors: AI
authors: Bravo
authors: María M
authors: MM
authors: Barrio
authors: José
authors: J
authors: Mordoh
mesh_terms: D049109:Cell Proliferation; D019175:DNA Methylation; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D058965:MART-1 Antigen / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D008545:Melanoma / Q000737:chemistry / Q000473:pathology*; D011401:Promoter Regions, Genetic; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D058951:gp100 Melanoma Antigen / Q000032:analysis* / Q000502:physiology
chemical_list: D019394:Ki-67 Antigen; D058965:MART-1 Antigen; D058951:gp100 Melanoma Antigen