ABSTRACT: The mammary epithelia are mainly composed of two distinct lineages, the basal and luminal cells. In our MMTV-Cre; Brca1flox/flox mouse model, we found the Brca1 knockout mainly occurred in the luminal cells, which will lead the mammary tumorigenesis. To investigate the Brca1 deficiency mediated mammary tumorigenesis, we sorted the luminal cells from wild type mice and MMTV-Cre; Brca1flox/flox mice for RNAseq analysis.
Project description:RNA from MMTV-Cre;Sox9flox/flox mouse mammary glands were compared to RNA from MMTV-Cre;Sox9+/flox glands. Results indicate that Sox9 regulates several genes that impact ductal morphogenesis in the mammary gland. The portion of the fourth mammary gland that is proximal to the intra-mammary gland lymph nodes was dissected from four 5-week-old MMTV-Cre;Sox9flox/flox females and four MMTV-Cre;Sox9+/flox females of the same age. Total RNA from each gland was extracted and hybridized to separate Affymetrix Gene 1.0 ST chips.
Project description:RNA from MMTV-Cre;Sox9flox/flox mouse mammary glands were compared to RNA from MMTV-Cre;Sox9+/flox glands. Results indicate that Sox9 regulates several genes that impact ductal morphogenesis in the mammary gland.
Project description:Overexpression and/or amplification of the ErbB-2 oncogene, as well as inactivation of the tumor suppressor PTEN, are two important genetic events in human breast carcinogenesis. To address the biological impact of conditional inactivation of PTEN on ErbB-2-induced mammary tumorigenesis, we generated a novel transgenic mouse model that utilizes the MMTV promoter to directly couple expression of activated ErbB-2 and Cre recombinase to the same mammary epithelial cell (MMTV-NIC). Disruption of PTEN in the mammary epithelium of the MMTV-NIC model system dramatically accelerated the formation of multifocal and highly metastatic mammary tumors, which exhibit homogenous pathology. PTEN-deficient/NIC tumorigenesis was associated with an increase in angiogenesis. Moreover, inactivation of PTEN in the MMTV-NIC mouse model resulted in hyperactivation of the PI3K/Akt signalling pathway. However, like the parental strain, tumors obtained from PTEN-deficient/NIC mice displayed histopathological and molecular features of the luminal-like subtype of breast cancer. Taken together, our findings provide important implications in understanding the molecular determinants of mammary tumorigenesis driven by PTEN deficiency and ErbB-2 activation, and could provide a valuable tool for testing the efficacy of therapeutic strategies that target these critical signalling pathways.
Project description:Overexpression and/or amplification of the ErbB-2 oncogene, as well as inactivation of the tumor suppressor PTEN, are two important genetic events in human breast carcinogenesis. To address the biological impact of conditional inactivation of PTEN on ErbB-2-induced mammary tumorigenesis, we generated a novel transgenic mouse model that utilizes the MMTV promoter to directly couple expression of activated ErbB-2 and Cre recombinase to the same mammary epithelial cell (MMTV-NIC). Disruption of PTEN in the mammary epithelium of the MMTV-NIC model system dramatically accelerated the formation of multifocal and highly metastatic mammary tumors, which exhibit homogenous pathology. PTEN-deficient/NIC tumorigenesis was associated with an increase in angiogenesis. Moreover, inactivation of PTEN in the MMTV-NIC mouse model resulted in hyperactivation of the PI3K/Akt signalling pathway. However, like the parental strain, tumors obtained from PTEN-deficient/NIC mice displayed histopathological and molecular features of the luminal-like subtype of breast cancer. Taken together, our findings provide important implications in understanding the molecular determinants of mammary tumorigenesis driven by PTEN deficiency and ErbB-2 activation, and could provide a valuable tool for testing the efficacy of therapeutic strategies that target these critical signalling pathways. Experiment Overall Design: Common reference design. 9 samples (including 2 normal tissue and 7 tumor tissue samples) replicated twice as dye swaps, generating a total of 18 arrays.
Project description:Gene expression profiles of sorted mammary epithelial cells from animals at 4, 6, and 8 weeks of age. Each individual sample was RNA obtained from an individual mouse. Our mice are mammary epithelium specific knocknout mouse models for gene Cobra1 and/or Brca1. For Cobra1, the first four exons were floxed. For Brca1, the largest exon, exon 11, was floxed. The mammary epithelium specific deletions were driven by cre recombinase under MMTV promoter (MMTV-cre). Animal genotype abbreviations used: wild-type (WT), meaning one of the following three: Cobra1f/f (Cff), Brca1f/f (Bff), and Brca1f/f;Cobra1f/f (Dff). Brca1 knockout (BKO), meaning MMTV-cre;Brca1f/f. Cobra1 knockout (CKO), meaning MMTV-cre;Cobra1f/f. Brca1 and Cobra1 double knockout (DKO), meaning MMTV-cre;Brca1f/f;Cobra1f/f
Project description:RUNX1 encodes a RUNX family transcription factor (TF) and was recently identified as a novel mutated gene in human luminal breast cancers. We found that Runx1 is expressed in all subpopulations of murine mammary epithelial cells (MECs) except the secretory alveolar luminal cells. Conditional knockout of Runx1 in MECs by MMTV-Cre led to a decrease in luminal MECs, largely due to a profound reduction in the estrogen receptor (ER)-positive mature luminal subpopulation, a phenotype that could be rescued by loss of either Trp53 or Rb1. Mechanistically RUNX1 represses Elf5, a master regulatory TF gene for alveolar cells, and activates Foxa1, a key mature luminal TF gene involved in the ER program. Collectively, our data identified a key regulator of the ER+ luminal lineage whose disruption may contribute to development of ER+ luminal breast cancer when under the background of either TP53 or RB1 loss. Thoracic and inguinal mammary glands from 3 MMTV-Cre;Runx1L/L;R26Y and 3 MMTV-Cre;Runx1+/+;R26Y adult virgin females were dissected out, minced and digested to single cell suspension. Runx1L is the floxed conditional knockout allele of Runx1. R26Y is a conditional YFP reporter that would be turned on upon Cre-mediated recombination. FACSaria machine was used to sort out the YFP-marked luminal epithelial cell population of each of these 6 mice. Total RNA was isolated with Qiagen RNeasy kit and subsequently amplified by Nugen V2 and applied to Affymetrix mouse genome 430 2.0 arrays.
Project description:We have identified GATA-3 as a critical regulator of luminal cell differentiation in the mammary gland. Acute loss of GATA-3 in the adult mammary gland leads to an expansion of an undifferentiated luminal epithelium and the formation of a multi-layered epithelium. Here we report microarray analysis of mammary glands that have undergone acute loss of GATA-3 Adult GATA-3flox/flox; WAP-rtTA-Cre and GATA-flox/+; WAP-rtTA-Cre mice were administered doxyxcline for 5 days and their mammary glands harvested. Total RNA was extracted by the Trizol method. Het mammary gland total RNA was labeled with Cy5 while Null mammary gland total RNA was labeled with Cy3. Microarray hybridization was performed on spotted oligonucleotide microarrays with 38,000 features. Lowess print-tip normalization and analysis was performed on the Acuity software package (V 4.0)
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: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 at different time points after the intraductal injection, as well as mammary tumors developed in this model, by single cell expression analysis.