Project description:The erythropoietin (EPO) hormone induces red blood cell production and its recombinant form is the most prescribed drug for the treatment of anemia, including that arising in cancer patients. Based on randomized trials showing that EPO administration to cancer patients result in a decreased survival, we investigated the impact of EPO modulation on tumorigenesis. Using genetically engineered mouse models of breast cancer we found that EPO promoted tumorigenesis by activating JAK/STAT signaling specifically in breast tumor initiating cells (TICs) and promoting their self-renewal. Moreover, we define an active role for endogenous EPO in breast cancer progression and breast TIC self-renewal and demonstrate a potential application of EPO pathway inhibition in breast cancer therapy. reference x sample
Project description:The erythropoietin (EPO) hormone induces red blood cell production and its recombinant form is the most prescribed drug for the treatment of anemia, including that arising in cancer patients. Based on randomized trials showing that EPO administration to cancer patients result in a decreased survival, we investigated the impact of EPO modulation on tumorigenesis. Using genetically engineered mouse models of breast cancer we found that EPO promoted tumorigenesis by activating JAK/STAT signaling specifically in breast tumor initiating cells (TICs) and promoting their self-renewal. Moreover, we define an active role for endogenous EPO in breast cancer progression and breast TIC self-renewal and demonstrate a potential application of EPO pathway inhibition in breast cancer therapy.
Project description:Notch signaling promotes commitment of keratinocytes to differentiation and suppresses tumorigenesis. p63, a p53 family member, has been implicated in establishment of the keratinocyte cell fate and/or maintenance of epithelial self-renewal. Here we show that p63 expression is suppressed by Notch1 activation in both mouse and human keratinocytes through a mechanism independent of cell cycle withdrawal and requiring down-modulation of selected interferon-responsive genes, including IRF7 and/or IRF3. In turn, elevated p63 expression counteracts the ability of Notch1 to restrict growth and promote differentiation. p63 functions as a selective modulator of Notch1-dependent transcription and function, with the Hes-1 gene as one of its direct negative targets. Thus, a complex cross-talk between Notch and p63 is involved in the balance between keratinocyte self-renewal and differentiation. Keywords: Notch1, p63, keratinocyte differentiation, gene expression profiling
Project description:Cell lines geneticially engineered to undergo conditional asymmetric self-renewal were used to identify genes whose expression is asymmetric self-renewal associated (ASRA). Non-random sister chromatid segregation occurs concordantly with asymmetric self-renewal in these cell lines. Asymmetric self-renewal occurs when murine embryo fibroblasts that are otherwise p53-null are induced to express physiological levels of wildtype p53 protein (Asym). To distinguish p53-responsive genes that also require induction of asymmetric self renewal (i.e., ASRA genes) and/or non-random sister chromatid segregation for change, an additional control cell line, which continues to symmetrically self-renew (with random sister chromatid segregation) even when p53 is induced, was also compared (Symp53). This congenic cell line constitutively expresses the type II inosine monophosphate dehydrogenase (IMPDH II; the rate-limiting enzmye for guanine ribonucleotide biosynthesis) and, thereby, prevents p53-induced asymmetric self-renewal and non-random sister chromatid segregation. Three biological replicates of asymmetrically self-renewing cultures (Asym1-3) were compared with cultures that were symmetrically self-renewing - either because they did not express p53 (3 biological replicates, Sym1-3) or they expressed constitutive IMPDH II (i.e., not regulated by p53) as well as p53 (2 biological replicates, Symp53_1 and 2.)
Project description:Loss of GADD45A expression is implicated in poor patient outcomes in acute myeloid leukemia (AML) but its role in leukemia stem cells (LSCs) and disease pathogenesis remains largely unknown. Here we report that GADD45A loss is a critical determinant of high self-renewal potential and knockout of GADD45A supports long-term self-renewal and promotes LSC quiescence, accompanied by the acquisition of an increasingly aggressive phenotype upon serial transplantation in mice. The enhanced LSC characteristics are associated with GADD45A deletion-induced increase in key WNT/self-renewal-related genes. GADD45A knockout promotes engraftment of patient-derived xenograft (PDX) of relapsed AML in mice. Single cell RNA-seq on primary LSCs of AML PDXs and subsequent functional studies show that low expression of GADD45A, an important sensor of oxidative stress, confers ferroptosis resistance through upregulation of genes involved in detoxification of excess iron and reactive oxygen species (ROS), revealing a mechanism of drug resistance in primary AML with unfavorable cytogenetics.
Project description:Epigenetic mechanisms oversee epidermal homeostasis and oncogenesis. The identification of kinases controlling these processes has direct therapeutic implications. We show that ULK3 is a nuclear kinase with elevated expression levels in squamous cell carcinomas (SCCs) arising in multiple body sites, including skin and Head/Neck. ULK3 loss by gene silencing or deletion reduces proliferation and clonogenicity of human keratinocytes and SCC-derived cells and affects transcription impinging on stem cell-related and metabolism programs. Mechanistically, ULK3 directly binds and regulates the activity of two histone arginine methyltransferases, PRMT1 and PRMT5 (PRMT1/5), with ULK3 loss compromising PRMT1/5 chromatin association to specific genes and overall methylation of histone H4, a shared target of these enzymes. These findings are of translational significance, as downmodulating ULK3 by RNA interference or locked antisense nucleic acids (LNAs) blunts the proliferation and tumorigenic potential of SCC cells and promotes differentiation in two orthotopic models of skin cancer.