RESUMO
Car-R and Car-S outbred mouse lines, phenotypically selected for resistance and susceptibility to skin carcinogenesis respectively, show significant linkage disequilibrium (LD) at genetic markers mapping on chromosomal regions where skin cancer modifier loci (Skts3, Skts1, and Psl1 on Chrs 5, 7, and 9 respectively) have been mapped in standard crosses. Analysis of these regions for genetic linkage with skin cancer phenotypes in 245 (Car-R x Car-S)F2 intercross mice, by using single nucleotide polymorphisms (SNPs), revealed significant linkage at a possible allelic form of the Skts1 locus, whose mapping region was shortened to a <5.5-cM interval near the Tyr locus. The Car-derived Skts1 locus was linked with papilloma multiplicity and latency by a recessive inheritance of the susceptibility allele. Putative loci on Chr 5 (Skts3) and 9 (Psl1) showed no significant linkage. These results point to the important role of the Stks1 locus in mouse skin tumorigenesis in independent crosses. The shortened Skts1 mapping region should facilitate the identification of candidate genes.
Assuntos
Desequilíbrio de Ligação , Polimorfismo de Nucleotídeo Único/genética , Neoplasias Cutâneas/genética , Animais , Animais não Endogâmicos , Cruzamentos Genéticos , Modelos Animais de Doenças , Marcadores Genéticos , Predisposição Genética para Doença , Haplótipos/genética , Heterozigoto , Camundongos , Camundongos Endogâmicos , Repetições de MicrossatélitesRESUMO
The parathyroid hormone-related protein (PTHrP) gene (Pthlh) maps in the distal region of mouse chromosome 6 that contains a quantitative trait locus associated with genetic predisposition to skin tumorigenesis. Here, we report a genetic polymorphism located in the osteostatin encoding region of the Pthlh gene and that produces Thr/ Pro PTHrP variants. PthlhThr and PthlhPro alleles were significantly linked with resistance and susceptibility to skin carcinogenesis in phenotypically selected Car-R and Car-S outbred mice. Transfection of human NCI-H520 squamous cell carcinoma cells with the PthlhPro allele resulted in cells growing in clusters, tending to pile up, and growing at a significantly faster rate in nude mice than non-transfected and PthlhThr-transfected cells. These results point to the role of the Pthlh gene as a cancer modifier gene in skin tumorigenesis.
Assuntos
Neoplasias de Células Escamosas/genética , Proteínas/genética , Neoplasias Cutâneas/genética , Animais , Sequência de Bases , Divisão Celular , Suscetibilidade a Doenças , Expressão Gênica , Predisposição Genética para Doença/genética , Humanos , Imunidade Inata/genética , Camundongos , Camundongos Nus , Dados de Sequência Molecular , Proteína Relacionada ao Hormônio Paratireóideo , Fenótipo , Polimorfismo Genético , Proteínas/fisiologia , Transfecção , Células Tumorais CultivadasRESUMO
Car-R (carcinogenesis-resistant) and Car-S (carcinogenesis-susceptible) outbred mice, obtained by phenotypic selection from an initial intercross of eight inbred strains, show a >100-fold difference in their susceptibility to two-stage skin tumorigenesis. We found that the lines carry a high degree of genetic polymorphism. with an average heterozygosity of 0.39. This polymorphism allowed the use of linkage disequilibrium (LD) and haplotype analysis for the mapping of a skin cancer modifier locus on Chr 7, in a short region of 6 cM, around the Tyr gene. Car-S mice inherited the susceptibility allele at this locus from the A/J, BALB/c, SJL/J, and SWR/J strains. Our results demonstrate the feasibility and usefulness of mapping disease genes by LD in phenotypically selected, genetically heterogeneous animals.
