Genetic analyses of mouse skin tumor progression susceptibility using SENCAR inbred derived strains

Susceptibility to tumor development varies among individuals in the human population. This variability can also be found among different strains of mice, particularly in the mouse skin chemical carcinogenesis model. The genetic mechanisms underlying mouse skin tumor susceptibility are not fully understood. The SENCAR stock has been found to be the most sensitive mice for skin carcinogenesis studies; however, little is known about the genes underlying tumor susceptibility, particularly, those involved in tumor progression. Experiments with the SSIN/Sprd mice, an inbred strain derived from the outbred SENCAR stock, suggested that papilloma development, tumor promotion, and their conversion into squamous cell carcinomas (SCCs), progression, are regulated by different genes. In the highly sensitive SSIN/Sprd mice, papillomas rarely progress to SCC. Using crosses between the outbred SENCAR and the SSIN/Sprd mice, we previously determined that papilloma progression in the SENCAR stock could be controlled by at least one autosomal dominant gene. However, the outbred nature of the SENCAR stock precluded us from extending those findings. More recently, another inbred strain was developed from the outbred SENCAR stock, the SENCARB/Pt. These mice have similar tumor promotion sensitivity to the SSIN/Sprd but in contrast, have high papilloma progression susceptibility, similar to the outbred original stock. In the present study, we generated F₁, F₂, and backcross hybrids between the SSIN/Sprd and SENCARB/Pt mice to determine a possible model for tumor progression susceptibility and to map the putative tumor susceptibility genes. Our tumor data suggests that papilloma progression susceptibility in the SENCAR mouse skin model could be genetically determined by one susceptibility gene. Our preliminary linkage analysis failed to identify one strong susceptibility locus to confirm this but provided some evidence for at least one possible susceptibility locus in mouse chromosome 14.