Project description:In many organs, adult stem cells are uniquely poised to serve as cancer cells of origin. In the epidermis, hair follicle stem cells (HFSCs) cycle through stages of quiescence (telogen) and proliferation (anagen) to drive hair growth. Within the hair follicle, HFSCs are capable of initiating squamous cell carcinoma, yet it is unclear how the hair cycle contributes to tumorigenesis. The data presented here show that HFSCs are unable to initiate tumors during the quiescent phase of the hair cycle, indicating that the mechanisms that keep HFSCs dormant are dominant to gain of oncogenes (Ras) or loss of tumor suppressors (p53). Instead, prolonged oncogenic stimuli only exert their effects when HFSC quiescence mechanisms are removed by normal HFSC activation. Furthermore, Pten activity is necessary for quiescence based tumor suppression, since Pten deletion alleviates this stem cell specific ability without affecting proliferation per se. Small RNAs were cloned from Trizol-lysed cells sorted from mouse skin and sequenced with the Illumina HiSeq2000.
Project description:In many organs, adult stem cells are uniquely poised to serve as cancer cells of origin. In the epidermis, hair follicle stem cells (HFSCs) cycle through stages of quiescence (telogen) and proliferation (anagen) to drive hair growth. Within the hair follicle, HFSCs are capable of initiating squamous cell carcinoma, yet it is unclear how the hair cycle contributes to tumorigenesis. The data presented here show that HFSCs are unable to initiate tumors during the quiescent phase of the hair cycle, indicating that the mechanisms that keep HFSCs dormant are dominant to gain of oncogenes (Ras) or loss of tumor suppressors (p53). Instead, prolonged oncogenic stimuli only exert their effects when HFSC quiescence mechanisms are removed by normal HFSC activation. Furthermore, Pten activity is necessary for quiescence based tumor suppression, since Pten deletion alleviates this stem cell specific ability without affecting proliferation per se.
Project description:In some organs, adult stem cells are uniquely poised to serve as cancer cells of origin1-4. It is unclear, however, whether tumorigenesis is influenced by the activation state of the adult stem cell. Hair follicle stem cells (HFSCs) act as cancer cells of origin for cutaneous squamous cell carcinoma (SCC) and undergo defined cycles of quiescence and activation. The data presented here show that HFSCs are unable to initiate tumors during the quiescent phase of the hair cycle, indicating that the mechanisms that keep HFSCs dormant are dominant to the gain of oncogenes (Ras) or the loss of tumor suppressors (p53). Furthermore, Pten activity is necessary for quiescence based tumor suppression, as its deletion alleviates tumor suppression without affecting proliferation. These data demonstrate that stem cell quiescence is a form of tumor suppression in HFSCs, and that Pten plays a role in maintaining quiescence in the presence of tumorigenic stimuli. This experiment includes RNA profiling of hair follicle stem cells at various stages of tumorigenesis
Project description:In some organs, adult stem cells are uniquely poised to serve as cancer cells of origin1-4. It is unclear, however, whether tumorigenesis is influenced by the activation state of the adult stem cell. Hair follicle stem cells (HFSCs) act as cancer cells of origin for cutaneous squamous cell carcinoma (SCC) and undergo defined cycles of quiescence and activation. The data presented here show that HFSCs are unable to initiate tumors during the quiescent phase of the hair cycle, indicating that the mechanisms that keep HFSCs dormant are dominant to the gain of oncogenes (Ras) or the loss of tumor suppressors (p53). Furthermore, Pten activity is necessary for quiescence based tumor suppression, as its deletion alleviates tumor suppression without affecting proliferation. These data demonstrate that stem cell quiescence is a form of tumor suppression in HFSCs, and that Pten plays a role in maintaining quiescence in the presence of tumorigenic stimuli. This experiment includes RNA profiling of hair follicle stem cells at various stages of tumorigenesis Briefly: HFSCs were lineage traced with YFP allele, FACS isolated from various genotypes, and then profiled by Affymetrix microarray Cell Isolation and FACS: Whole dorsal and ventral mouse K15-CrePR; LSLYFP, K15-CrePR; KrasG12D; LSLYFP and K15-CrePR; KrasG12D; Ptenff; LSLYFP was extracted, diced and digested with collagenase (20mg/ml) for 2 hours at 37C, then an equal volume of .25% trypsin was added and digestion continued for an additional hour at 37C. Digested tissue was mechanically dispersed via pipette and filtered with a 100uM cell strainer, collected at 300g and washed twice with PBS. The cells were then filtered through a 40uM cell strainer and FACS processed. YFP+ and YFP- cell populations were collected in RNA lysis buffer (Stratagene) and stored at -80C. Gene expression profiling Microarray analyses by GeneSpring software were performed
Project description:Quiescent stem cells are periodically activated to maintain tissue homeostasis or occasionally called into action upon injury. Molecular mechanisms that constitutively maintain stem cell identity or promote stem cell proliferation and differentiation upon activation have been extensively studied. However, it is unclear how quiescent stem cells maintain identity and reinforce quiescence when they transition from quiescence to activation. Here we show mouse hair follicle stem cell compartment induces a transcription factor, Foxc1, when activated. Importantly, deletion of Foxc1 in the activated but not quiescent stem cells compromises stem cell identity, fails to re-establish quiescence and subsequently drives premature stem cell activation.These findings uncover a dynamic, cell-intrinsic mechanism employed by hair follicle stem cells to reinforce stemness in response to activation. Poly(A)-enriched transcriptome RNA-seq on HFSCs isolated in WT and K14Cre cKO mice at anagen and early telogen stage of hair cycle.
Project description:The squamous cell carcinomas represent the aggressive type of non melanoma skin cancer, the most frequent malignancy among human population. We have studied here the possible relationship between these two pathways in skin using epidermal-specific mutant mice. Loss of p53, but not pRb, produces spontaneous tumor development, indicating that, contrary to pRb, p53 is the predominant tumor suppressor acting in mouse epidermis. The simultaneous inactivation of pRb and p53 does not aggravate the epidermal phenotype observed in Rb-deficient mice in terms of proliferation and/or differentiation. However, in doubly deficient mice spontaneous skin tumor development is severely accelerated. The tumors are aggressive, undifferentiated and display a hair follicle origin. Detailed analysis indicates that the acceleration is mediated by premature activation of the EGFR/Akt pathway, resulting in increased angiogenesis. The molecular characteristics of this model provide valuable tools to understand epidermal tumor formation, and may ultimately contribute to the development of therapies for the treatment of aggressive squamous cancer. Experiment Overall Design: Pools from RNA whole skin extracts from 3 animals of same genotype were done and analyzed, per duplicate, in mouse microarrays. Comparison was performed between the 4 different genotypes.
Project description:Quiescent stem cells are periodically activated to maintain tissue homeostasis or occasionally called into action upon injury. Molecular mechanisms that constitutively maintain stem cell identity or promote stem cell proliferation and differentiation upon activation have been extensively studied. However, it is unclear how quiescent stem cells maintain identity and reinforce quiescence when they transition from quiescence to activation. Here we show mouse hair follicle stem cell compartment induces a transcription factor, Foxc1, when activated. Importantly, deletion of Foxc1 in the activated but not quiescent stem cells compromises stem cell identity, fails to re-establish quiescence and subsequently drives premature stem cell activation.These findings uncover a dynamic, cell-intrinsic mechanism employed by hair follicle stem cells to reinforce stemness in response to activation.
Project description:Quiescent stem cells are periodically activated to maintain tissue homeostasis or occasionally called into action upon injury. Molecular mechanisms that constitutively maintain stem cell identity or promote stem cell proliferation and differentiation upon activation have been extensively studied. However, it is unclear how quiescent stem cells maintain identity and reinforce quiescence when they transition from quiescence to activation. Here we show mouse hair follicle stem cell compartment induces a transcription factor, Foxc1, when activated. Importantly, deletion of Foxc1 in the activated but not quiescent stem cells compromises stem cell identity, fails to re-establish quiescence and subsequently drives premature stem cell activation.These findings uncover a dynamic, cell-intrinsic mechanism employed by hair follicle stem cells to reinforce stemness in response to activation.
Project description:The squamous cell carcinomas represent the aggressive type of non melanoma skin cancer, the most frequent malignancy among human population. We have studied here the possible relationship between these two pathways in skin using epidermal-specific mutant mice. Loss of p53, but not pRb, produces spontaneous tumor development, indicating that, contrary to pRb, p53 is the predominant tumor suppressor acting in mouse epidermis. The simultaneous inactivation of pRb and p53 does not aggravate the epidermal phenotype observed in Rb-deficient mice in terms of proliferation and/or differentiation. However, in doubly deficient mice spontaneous skin tumor development is severely accelerated. The tumors are aggressive, undifferentiated and display a hair follicle origin. Detailed analysis indicates that the acceleration is mediated by premature activation of the EGFR/Akt pathway, resulting in increased angiogenesis. The molecular characteristics of this model provide valuable tools to understand epidermal tumor formation, and may ultimately contribute to the development of therapies for the treatment of aggressive squamous cancer. Keywords: Squamous cell carcinoma, Epidermis, Tumorigenesis, pRb, p53, Akt, Angiogenesis