Targeted disruption of Brca1 in restricted compartments of the mouse mammary epithelia.

Tumours arising in BRCA1 mutation carriers have a characteristic phenotype, the molecular and cellular basis of which is unknown. To address the hypothesis that this phenotype reflects a role for BRCA1 in either in the basal or the stem cell compartments of the mammary epithelia, we have targeted its disruption to K14 and K6a expressing cells of the mouse. Unlike MMTV and WAP driven conditional knockout models of Brca1, these two models did not result in any observable changes in the mammary gland.

Patched1 functions as a gatekeeper by promoting cell cycle progression.

Mutations in the Hedgehog receptor, Patched 1 (Ptch1), have been linked to both familial and sporadic forms of basal cell carcinoma (BCC), leading to the hypothesis that loss of Ptch1 function is sufficient for tumor progression. By combining conditional knockout technology with the inducible activity of the Keratin6 promoter, we provide in vivo evidence that loss of Ptch1 function from the basal cell population of mouse skin is sufficient to induce rapid skin tumor formation, reminiscent of human BCC. Elimination of Ptch1 does not promote the nuclear translocation of beta-catenin and does not induce ectopic activation or expression of Notch pathway constituents.