Project description:Mitochondrial stress triggers both metabolic and transcriptomic reprogramming but its effects on tumor development remains unclear. It is also unknown whether the genetic status has any influence on the capacity of mitochondrial stress to control tumor development. To explore these issues, we generated a mouse model lacking the lipid transfer protein Stard7 in intestinal epithelial cells (IECs) and assessed tumor development in both Wnt-dependent tumor initiation and in inflammation-driven tumor development. The loss of Stard7 in both models of intestinal tumors impaired mitochondrial Complex I activity, led to a severe metabolic and lipidomic reprogramming and potentiated mTORC1 activation. As a result, levels of enzymes involved in serine biosynthesis were enhanced in Stard7-deficient IECs showing or not constitutive Wnt signaling. Strikingly, despite similar molecular signatures upon Stard7 deficiency in intestinal crypts showing or not constitutive Wnt signaling, Stard7 contributed to tumor development in AOM/DSS-treated mice but inhibits Wnt-driven cancer initiation in the intestine. Apc+/min mice lacking Stard7 in IECs developed more tumors in the distal colon as well as a specific microbiota signature. Collectively, our results suggest that the Apc genetic status critically controls the effects of mitochondrial stress on intestinal tumor development.
Project description:Mitochondrial stress triggers both metabolic and transcriptomic reprogramming but its effects on tumor development remains unclear. It is also unknown whether the genetic status has any influence on the capacity of mitochondrial stress to control tumor development. To explore these issues, we generated a mouse model lacking the lipid transfer protein Stard7 in intestinal epithelial cells (IECs) and assessed tumor development in both Wnt-dependent tumor initiation and in inflammation-driven tumor development. The loss of Stard7 in both models of intestinal tumors impaired mitochondrial Complex I activity, led to a severe metabolic and lipidomic reprogramming and potentiated mTORC1 activation. As a result, levels of enzymes involved in serine biosynthesis were enhanced in Stard7-deficient IECs showing or not constitutive Wnt signaling. Strikingly, despite similar molecular signatures upon Stard7 deficiency in intestinal crypts showing or not constitutive Wnt signaling, Stard7 contributed to tumor development in AOM/DSS-treated mice but inhibits Wnt-driven cancer initiation in the intestine. Apc+/Minmice lacking Stard7 in IECs developed more tumors in the distal colon. Collectively, our results suggest that the Apc genetic status critically controls the effects of mitochondrial stress on intestinal tumor development.
Project description:Loss of the APC tumor suppressor in the intestinal epithelium initiates the majority of human colorectal adenocarcinomas. Constitutive β-catenin activation is thought to underlie tumorigenesis induced by loss of APC, however β-catenin activation alone does not recapitulate all APC-loss phenotypes, suggesting that additional pathways are required. We demonstrate that aberrant activation of the Msi1 RNA binding protein occurs upon APC loss and that constitutive Msi1 activation alone is sufficient to phenocopy APC loss in the intestinal epithelium. Msi1 elicits these effects through binding of mRNAs encoding pleiotropic tumor suppressors resulting in promiscuous activation of quiescent intestinal stem cells, proliferative expansion of the stem cell compartment, crypt fission, and blocked differentiation. Further, we find these phenotypes to be largely dependent on mTORC1 activity, and demonstrate that loss of Msi activity is sufficient to abrogate tumorigenesis in mouse and human systems. Our findings implicate Msi1 as a central coordinator of APC loss-induced intestinal stem cell transformation and adenocarcinoma progression. 2 wild-type, 2 transgenic samples
Project description:Amoung their pleiotropic functions, a role was recently assigned for b-arrestin scaffold proteins in tumor growth, angiogenesis and invasion. In order to elucidate the roles of b-arrestins in tumour developement in intestinal epithelium initiated by Apc mutation, we determined the effects of b-arrestin gene deletion on intestinal polypolis using ApcD14/+ mice, a relevant mouse model of human intestinal tumorigenesis.Here we show that unlike b-arrestin1, absence of b-arrestin2 dramatically decreased the number of spontaneously developping intestinal tumors in ApcD14/+ mice.The size of residual tumors was similarto that of controls, suggesting that their growth is b-arrestin2-independent. This result demonstrated a role for b-arrestin2 in the early development of a tumor subset. Gene expression profils analysis of ApcD14/+:Arrb2+/+ and ApcD14/+:Arrb2-/- tumors showed two distinct clusters among ApcD14/+:Arrb2+/+ tumors and one of them was statistically more correlated to ApcD14/+:Arrb2-/- tumors than to the other ApcD14/+:Arrb2+/+ cluster, eventhough a number of genes saw their expression affected in ApcD14/+:Arrb2-/- tumors only. Altogether, our data unravel an unexpected early diversity among intestinal tumors and a crucial role for b-arrestin2 in early tumor development in Apc-mutated mice. 10 tumors from 2 different ApcD14 mice
Project description:Amoung their pleiotropic functions, a role was recently assigned for b-arrestin scaffold proteins in tumor growth, angiogenesis and invasion. In order to elucidate the roles of b-arrestins in tumour developement in intestinal epithelium initiated by Apc mutation, we determined the effects of b-arrestin gene deletion on intestinal polypolis using ApcD14/+ mice, a relevant mouse model of human intestinal tumorigenesis.Here we show that unlike b-arrestin1, absence of b-arrestin2 dramatically decreased the number of spontaneously developping intestinal tumors in ApcD14/+ mice.The size of residual tumors was similarto that of controls, suggesting that their growth is b-arrestin2-independent. This result demonstrated a role for b-arrestin2 in the early development of a tumor subset. Gene expression profils analysis of ApcD14/+:Arrb2+/+ and ApcD14/+:Arrb2-/- tumors showed two distinct clusters among ApcD14/+:Arrb2+/+ tumors and one of them was statistically more correlated to ApcD14/+:Arrb2-/- tumors than to the other ApcD14/+:Arrb2+/+ cluster, eventhough a number of genes saw their expression affected in ApcD14/+:Arrb2-/- tumors only. Altogether, our data unravel an unexpected early diversity among intestinal tumors and a crucial role for b-arrestin2 in early tumor development in Apc-mutated mice. 16 tumors from ApcD14/+:Arrb2+/+ mice and 13 tumors from ApcD14/+:Arrb2-/- mice
Project description:The first step in the development of human colorectal cancer is the aberrant hyperactivation of the Wnt signaling pathway, predominantly caused by inactivating mutations in the adenomatous polyposis coli (Apc) gene encoding an essential tumor suppressor. The gene encoding transcriptional factor msh homeobox 1 (Msx1) displayed robust upregulation upon Apc inactivation in intestinal epithelium isolated in mice harboring the conditional allele of the Apc gene. To identify the gene signature in the small intestine upon Msx1 depletion, small intestinal epithelium from mice harboring conditional alleles of Apc and Msx1 was isolated and the gene expression profile was compared with control mice harboring the conditional allele of Apc only.
Project description:To analyse roles of HAI-1/Spint1 in intestinal tumorigenesis, we examined the effect of intestine-specific deletion of Spint1 gene on Apc(Min/+) mice. The loss of Hai-1/Spint1 significantly accelerated tumor formation in ApcMin/+ mice and shortened their survival periods. Mouse small intestine tumor tissue or background mucosa lacking macroscopically visible tumors were proceeded to RNA extraction and hybridization on microarrays (Affymetrix Mouse Genome 430 2.0 Array). Non-tumor or tumor intestinal mucosa tissues of Apc (Min/+)/Spint1 (flox/flox) mice and non-tumor or tumor intestinal mucosa tissues of Apc (Min/+)/Spint1 (flox/flox)/Vil-Cre mice were analysed. The experiment was repeated respectively.
Project description:Amoung their pleiotropic functions, a role was recently assigned for b-arrestin scaffold proteins in tumor growth, angiogenesis and invasion. In order to elucidate the roles of b-arrestins in tumour developement in intestinal epithelium initiated by Apc mutation, we determined the effects of b-arrestin gene deletion on intestinal polypolis using ApcD14/+ mice, a relevant mouse model of human intestinal tumorigenesis.Here we show that unlike b-arrestin1, absence of b-arrestin2 dramatically decreased the number of spontaneously developping intestinal tumors in ApcD14/+ mice.The size of residual tumors was similarto that of controls, suggesting that their growth is b-arrestin2-independent. This result demonstrated a role for b-arrestin2 in the early development of a tumor subset. Gene expression profils analysis of ApcD14/+:Arrb2+/+ and ApcD14/+:Arrb2-/- tumors showed two distinct clusters among ApcD14/+:Arrb2+/+ tumors and one of them was statistically more correlated to ApcD14/+:Arrb2-/- tumors than to the other ApcD14/+:Arrb2+/+ cluster, eventhough a number of genes saw their expression affected in ApcD14/+:Arrb2-/- tumors only. Altogether, our data unravel an unexpected early diversity among intestinal tumors and a crucial role for b-arrestin2 in early tumor development in Apc-mutated mice.
Project description:Amoung their pleiotropic functions, a role was recently assigned for b-arrestin scaffold proteins in tumor growth, angiogenesis and invasion. In order to elucidate the roles of b-arrestins in tumour developement in intestinal epithelium initiated by Apc mutation, we determined the effects of b-arrestin gene deletion on intestinal polypolis using ApcD14/+ mice, a relevant mouse model of human intestinal tumorigenesis.Here we show that unlike b-arrestin1, absence of b-arrestin2 dramatically decreased the number of spontaneously developping intestinal tumors in ApcD14/+ mice.The size of residual tumors was similarto that of controls, suggesting that their growth is b-arrestin2-independent. This result demonstrated a role for b-arrestin2 in the early development of a tumor subset. Gene expression profils analysis of ApcD14/+:Arrb2+/+ and ApcD14/+:Arrb2-/- tumors showed two distinct clusters among ApcD14/+:Arrb2+/+ tumors and one of them was statistically more correlated to ApcD14/+:Arrb2-/- tumors than to the other ApcD14/+:Arrb2+/+ cluster, eventhough a number of genes saw their expression affected in ApcD14/+:Arrb2-/- tumors only. Altogether, our data unravel an unexpected early diversity among intestinal tumors and a crucial role for b-arrestin2 in early tumor development in Apc-mutated mice.