Project description:For the largest class of human tumors, those of epithelial origin, little is known about their initiating genetic hits or cells of origin. Whether tissue stem cells or more committed progenitors are targets for transformation is also uncertain. Experience in hematopoietic malignancies and sarcomas teaches that recurrent chromosomal translocations represent initiating oncogenic events. To develop a system in which epithelial tumorigenesis can be assessed from the initial event to frank malignancy, we have generated mice that conditionally express the Etv6-NTRK3 (EN) fusion oncoprotein, the product of the t(12;15)(p13;q25) translocation characteristic of one form of human breast cancer. Activation of EN expression in mammary tissues by Whey acidic protein (Wap) promoter-driven Cre leads to fully penetrant, multifocal malignant breast cancer with short latency. We provide genetic evidence that committed, bipotent or CD61+ luminal alveolar progenitors, can be targets of tumorigenesis. Furthermore, EN transforms these otherwise transient progenitors through the AP1 complex. Our model supports the existence of an epithelial cell hierarchy in both normal mammary glands and malignancy. To our knowledge, this is the first murine model of human epithelial cancer based on a recurrent chromosomal translocation. Given increasing relevance of chromosomal translocations in epithelial cancers, such mice serve as a paradigm for the study of their genetic pathogenesis and cellular origins, and generation of novel preclinical models. Experiment Overall Design: Reference X Sample
Project description:Amplification of large chromosomal regions (gene amplification) is a common somatic alteration in human cancer cells and often is associated with advanced disease. A critical event initiating gene amplification is a DNA double strand break (DSB), which is immediately followed by the formation of a large DNA palindrome. Large DNA palindromes are frequent and non-randomly distributed in the genomes of cancer cells and facilitate further increase in copy number. Although the importance of the formation of large DNA palindromes as a very early event in gene amplification is widely recognized, it is not known 1) how a DSB is resolved to form a large DNA palindrome; and 2) whether any local DNA structure determines the location of large DNA palindromes. We show here that intra-strand annealing following a DNA double-strand break leads to the formation of large DNA palindromes and that DNA inverted repeats in the genome determines the efficiency of this event. Furthermore, in human Colo320DM cancer cells, a DNA inverted repeat in the genome marks the border between amplified and non-amplified DNA. Therefore, an early step of gene amplification is a regulated process that is facilitated by DNA inverted repeats in the genome. Experiment Overall Design: Genomic DNA samples from HFF2 and Colo320DM cells were collected and taken through the GAPF procedure. Their GAPF profiles were analyzed using Affymetrix HGU 133A arrays, and the differentially hybridized genes were determined to be significant according to a FDR<0.05
Project description:For the largest class of human tumors, those of epithelial origin, little is known about their initiating genetic hits or cells of origin. Whether tissue stem cells or more committed progenitors are targets for transformation is also uncertain. Experience in hematopoietic malignancies and sarcomas teaches that recurrent chromosomal translocations represent initiating oncogenic events. To develop a system in which epithelial tumorigenesis can be assessed from the initial event to frank malignancy, we have generated mice that conditionally express the Etv6-NTRK3 (EN) fusion oncoprotein, the product of the t(12;15)(p13;q25) translocation characteristic of one form of human breast cancer. Activation of EN expression in mammary tissues by Whey acidic protein (Wap) promoter-driven Cre leads to fully penetrant, multifocal malignant breast cancer with short latency. We provide genetic evidence that committed, bipotent or CD61+ luminal alveolar progenitors, can be targets of tumorigenesis. Furthermore, EN transforms these otherwise transient progenitors through the AP1 complex. Our model supports the existence of an epithelial cell hierarchy in both normal mammary glands and malignancy. To our knowledge, this is the first murine model of human epithelial cancer based on a recurrent chromosomal translocation. Given increasing relevance of chromosomal translocations in epithelial cancers, such mice serve as a paradigm for the study of their genetic pathogenesis and cellular origins, and generation of novel preclinical models. Keywords: Reference X Sample
Project description:Arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) combination safely cures fatal acute promyelocytic leukemia, but the mechanisms underlying their action and synergy remain elusive. ATRA inhibits APL, breast and liver cancers by targeting isomerase Pin1, a master regulator of oncogenic signaling. Here we show that ATO targets Pin1 and cooperates with ATRA to exert potent anticancer activity. ATO inhibits and degrades Pin1, and suppresses its oncogenic function by noncovalent binding to Pin1’s active site. ATRA increases cellular ATO uptake through upregulating aquaporin-9. ATO and ATRA, at clinically safe doses, cooperatively ablate Pin1 to block numerous cancer-driving pathways and inhibit the growth of triple-negative breast cancer cells and tumor-initiating cells in cell and animal models including patient-derived orthotopic xenografts, similar to Pin1 CRISPR knockout, which is substantiated by comprehensive protein and microRNA analyses. Thus, synergistic Pin1 inhibition by ATO and ATRA offers an attractive approach to combating breast and other cancers.
Project description:Amplification of large chromosomal regions (gene amplification) is a common somatic alteration in human cancer cells and often is associated with advanced disease. A critical event initiating gene amplification is a DNA double strand break (DSB), which is immediately followed by the formation of a large DNA palindrome. Large DNA palindromes are frequent and non-randomly distributed in the genomes of cancer cells and facilitate further increase in copy number. Although the importance of the formation of large DNA palindromes as a very early event in gene amplification is widely recognized, it is not known 1) how a DSB is resolved to form a large DNA palindrome; and 2) whether any local DNA structure determines the location of large DNA palindromes. We show here that intra-strand annealing following a DNA double-strand break leads to the formation of large DNA palindromes and that DNA inverted repeats in the genome determines the efficiency of this event. Furthermore, in human Colo320DM cancer cells, a DNA inverted repeat in the genome marks the border between amplified and non-amplified DNA. Therefore, an early step of gene amplification is a regulated process that is facilitated by DNA inverted repeats in the genome. Keywords: cancer vs. normal sample comparison
Project description:Duplication of chromosomal arm 20q occurs in prostate, cervical, colon, gastric, bladder, melanoma, pancreas and breast cancer, suggesting that 20q amplification may play a key causal role in tumorigenesis. According to an alternative view, chromosomal instabilities are mainly a common side effect of cancer progression. To test whether a specific genomic aberration might serve as a cancer initiating event, we established an in vitro system that models the evolutionary process of early stages of prostate tumor formation; normal prostate cells were immortalized and cultured for 650 days till several transformation hallmarks were observed. Gene expression patterns were measured and chromosomal aberrations were monitored by spectral karyotype analysis at different times. Several chromosomal aberrations, in particular duplication of chromosomal arm 20q, occurred early in the process and were fixed in the cell populations, while other aberrations became extinct shortly after their appearance. A wide range of bioinformatic tools, applied to our data and to data from several cancer databases, revealed that spontaneous 20q amplification can promote cancer initiation. Our computational model suggests that deregulation of some key pathways, such as MAPK, p53, cell cycle regulation and Polycomb group factors, in addition to activation of several genes like Myc, AML, B-Catenin and the ETS family transcription factors, are key steps in cancer development driven by 20q amplification. Finally we identified 13 cancer initiating genes, located on 20q13, which were significantly overexpressed in many tumors, with expression levels correlated with tumor grade and outcome; these probably play key roles in inducing malignancy via20q amplification. 33 samples were analysised, 12 were in replicate
Project description:Focal copy-number amplification is an oncogenic event in many cancers. Although several studies showed the complex structure of amplified oncogens and the evolution of amplicons after their formation, the origin of the initial amplicons remains poorly understood. To understand the mechanisms, we generated genome-wide chromosomal translocation maps with/out beta-estradiol in estrogen receptor (ER) positive breast cancer cells when a DNA double strand breark occurs in SHANK2 or RARA. We found that estrogen treatment induces DNA double strand breaks in the estrogen receptor target regions that are repaired by translocations, suggesting the role of estrogen in generating the original translocations initiating amplication.
Project description:MicroRNAs (miRNAs) are small, non-coding, endogenous RNAs involved in many human diseases including breast cancer. miRNA expression profiling of human breast cancers has identified miRNAs related to the clinical diversity of the disease and potentially provides novel diagnostic and prognostic tools for breast cancer therapy. In order to further understand the roles of miRNAs in association with oncogenic drivers and in specifying sub-types of breast cancer, we performed miRNAexpression profiling on mammary tumors from eight well-characterized genetically -engineered Mouse (GEM) models of human breast cancer including MMTV–H-Ras, -Her2/neu, -c-Myc, -PymT, –Wnt1 and C3(1)/SV40 T/t-antigen transgenic mice, BRCA1fl/fl;p53+/-;MMTV-cre and the p53fl/fl ;MMTV-cre transplant model. miRNA expression data for 41 mouse primary mammary tumors and 5 mouse normal mammary glands
Project description:Pancreatic cancer is characterized by nearly universal activating mutations in KRAS. Among other somatic mutations, TP53 is mutated in more than 75% of human pancreatic tumors. Genetically engineered mice have proven instrumental in studies of the contribution of individual genes to carcinogenesis. Oncogenic Kras mutations occur early during pancreatic carcinogenesis and are considered an initiating event. In contrast, mutations in p53 occur later during tumor progression. In our model, we recapitulated the order of mutations of the human disease, with p53 mutation following expression of oncogenic Kras. Further, using an inducible and reversible expression allele for mutant p53, we inactivated its expression at different stages of carcinogenesis. Notably, the function of mutant p53 changes at different stages of carcinogenesis. Our work establishes a requirement for mutant p53 for the formation and maintenance of pancreatic cancer precursor lesions. In tumors, mutant p53 becomes dispensable for growth. However, it maintains the altered metabolism that characterizes pancreatic cancer and mediates its malignant potential. Further, mutant p53 promotes epithelial-mesenchymal transition (EMT) and cancer cell invasion. This work generates new mouse models that mimic human pancreatic cancer and expands our understanding of the role of p53 mutation, common in the majority of human malignancies.