Project description:BRCA1 mutation-carriers are predisposed to develop Basal-like breast cancer (BLBC), and p53 mutations are present in the majority of human BLBC cases, suggesting loss of these two tumor suppressors play key roles in development of BLBC. Recent studies suggest that the majority of human breast cancers, including BLBC, may originate from mammary epithelial cells (MECs) in the luminal lineage. However, how loss of p53 and BRCA1 contributes to development of BLBC from luminal MECs remains largely elusive. We developed a novel genetic targeting and lineage tracing approach based on intraductal injection of Cre-expressing adenovirus under the control of the pan-luminal Keratin 8 (K8) promoter (Ad-K8-Cre). We performed intraductal injection of Ad-K8-Cre to female mice carrying conditional knockout alleles of Brca1 (Brca1L) and Trp53 (Trp53L). The injected females developed mammary tumors similar to human BLBC within 12 months after injection. Here we characterized MECs targeted by Ad-K8-Cre at different time points after the intraductal injection, as well as mammary tumors developed in this model, by single cell expression analysis.
Project description:BRCA1 mutation-carriers are predisposed to develop Basal-like breast cancer (BLBC), and p53 mutations are present in the majority of human BLBC cases, suggesting loss of these two tumor suppressors play key roles in development of BLBC. Recent studies suggest that the majority of human breast cancers, including BLBC, may originate from mammary epithelial cells (MECs) in the luminal lineage. However, how loss of p53 and BRCA1 contributes to development of BLBC from luminal MECs remains largely elusive. We developed a novel genetic targeting and lineage tracing approach based on intraductal injection of Cre-expressing adenovirus under the control of the pan-luminal Keratin 8 (K8) promoter (Ad-K8-Cre). We performed intraductal injection of Ad-K8-Cre to female mice carrying conditional knockout alleles of Brca1 and Trp53. The injected females developed mammary tumors within 12 months after injection. Microarray expression profiling of these tumors showed that they most closely resembled human BLBC.
Project description:BRCA1 mutation-carriers are predisposed to develop Basal-like breast cancer (BLBC), and p53 mutations are present in the majority of human BLBC cases, suggesting loss of these two tumor suppressors play key roles in development of BLBC. Recent studies suggest that the majority of human breast cancers, including BLBC, may originate from mammary epithelial cells (MECs) in the luminal lineage. However, how loss of p53 and BRCA1 contributes to development of BLBC from luminal MECs remains largely elusive. We developed a novel genetic targeting and lineage tracing approach based on intraductal injection of Cre-expressing adenovirus under the control of the pan-luminal Keratin 8 (K8) promoter (Ad-K8-Cre). We performed intraductal injection of Ad-K8-Cre to female mice carrying conditional knockout alleles of Brca1 (Brca1L) and Trp53 (Trp53L). The injected females developed mammary tumors similar to human BLBC within 12 months after injection. Here we characterized MECs targeted by Ad-K8-Cre one month after the intraductal injection.
Project description:Densely ionizing radiation is a major component of the space radiation environment and has potentially greater carcinogenic effect compared to sparsely ionizing radiation that is prevalent in the terrestrial environment. It is unknown to what extent the irradiated microenvironment contributes to the differential carcinogenic potential of densely ionizing radiation. To address this gap, 10-week old BALB/c mice were irradiated with 100 cGy sparsely ionizing g-radiation or 10, 30, or 80 cGy of densely ionizing, 350 MeV/amu Si particles and transplanted 3 days later with syngeneic Trp53 null mammary fragments. Tumor appearance was monitored for 600 days. Tumors arising in Si-particle irradiated mice had a shorter median time to appearance, grew faster and were more likely to metastasize. Most tumors arising in sham-irradiated mice were ER-positive, pseudo-glandular and contained both basal keratin 14 and luminal keratin 8/18 cells (designated K14/18), while most tumors arising in irradiated hosts were K8/18 positive (designated K18) and ER negative. Comparison of K18 vs K14/18 tumor expression profiles showed that genes increased in K18 tumors were associated with ERBB2 and KRAS while decreased genes overlapped with those down regulated in metastasis and by loss of E-cadherin. Consistent with this, K18 tumors grew faster than K14/18 tumors and more mice with K18 tumors developed lung metastases compared to mice with K14/18 tumors. However, K18 tumors arising in Si-particle irradiated mice grew even faster and were more metastatic compared to control mice. A K18 Si-irradiated host profile was enriched in genes involved in mammary stem cells, stroma, and Notch signaling. Thus systemic responses to densely ionizing radiation enriches for a ER-negative, K18-positive tumor, whose biology is more aggressive compared to similar tumors arising in non-irradiated hosts. Key Words: ionizing radiation; breast cancer; heavy ion radiation;initiation; promotion 3 different dose of Si were used. Total RNA was extracted from mammary tumors derived from transplantations of non-irradiated p53null mammary fragments into irradiated hosts. We analyzed a total of 45 Trp53-null tumors: 18 from sham-irradiated hosts, 9 from 10 cGy Si-irradiated hosts, 10 from 30 cGy Si-irradiated hosts, and 8 from irradiated hosts.
Project description:Mammary stem and progenitor cells are essential for mammary gland homeostasis and are also candidates for cells of origin of mammary tumors. Here, we provide evidence that the protein kinase p38a is required for the differentiation of luminal progenitor cells through modulation of the transcription factors Runx1 and Foxa1. Moreover, using a mouse model for breast cancer initiated by luminal cells, we show that p38a downregulation in mammary epithelial cells reduces tumorigenesis, which correlates with reduced numbers of tumor-initiating cells. Our results identify p38a as a key regulator of luminal progenitor cell fate that facilitates mammary tumor formation.
Project description:Brca2(fl/fl)Trp53(fl/fl) mice were crossed with MMTV-cre mice to create mice with both alleles of Brca2 and one allele of Trp53 deleted (refered to as Brca2KO). Mature luminal, luminal progenitor and basal mammary epithelial cell populations were sorted from Brca2KO and wildtype mice. Transcriptional profiling revealed marked perturbation within the luminal Brca2KO compartment