Project description:gDNA from patient samples with multiple basal cell carcinomas and possible exposure to ionizing radiation was hybridized Vs. GM12878 gDNA to assess CNAs. We aimed to find a possible common aberration pattern related to ionizing radiation or a rare metastasis.
Project description:Basal cell carcinomas (BCCs) have relative genomic stability and relatively benign clinical behavior but whether these two are related causally is unknown. To investigate the effects of introducing genomic instability into murine BCCs, we have compared ionizing radiation-induced tumorigenesis in Ptch1+/- mice vs. that in Ptch1+/- mice carrying mutant Blm alleles. We found that BCCs in Ptch1+/- Blmtm3Brd/tm3Brd mice had a trend towards greater genomic instability as measured by array CGH and that these mice developed significantly more microscopic BCCs than did Ptch1+/- Blm+/tm3Brd or Ptch1+/- Blm+/+ mice. The mutant Blm alleles also markedly enhanced the formation of rhabdomyosarcomas (RMS), another cancer to which Ptch1+/- mice and PTCH1+/- (basal cell nevus syndrome) patients are susceptible. Highly recurrent but different copy number changes were associated with the two tumor types and included losses of chromosomes 4 and 10 in all BCCs and gain of chromosome 10 in 80% of RMSs. Loss of chromosome 11 and 13, including the Trp53 and Ptch1 loci respectively, occurred frequently in BCCs, suggesting tissue-specific selection for genes or pathways that collaborate with Ptch deficiency in tumorigenesis. Despite the quantitative differences, there was no dramatic qualitative difference in the BCC or RMS tumors associated with the mutant Blm genotype. We investigated the effect of Blm deficiency on ionizing radiation-induced basal cell carcinoma and rhabdomyosarcoma tumorigenesis in Ptch1+/- mice. Six BCC and five RMS samples were obtained from separate mice. Liver tissue from each mouse was used as the normal reference.