The specific ablation of Rb1 gene in stratified epithelia (RbF/F;K14cre) promotes proliferation and altered differentiation but is insufficient to produce spontaneous tumors. The pRb relative, p107, compensates some of the functions of pRb in these tissues, however RbF/F;K14cre;p107-/- mice die postnatally. Acute pRb loss in stratified epithelia, using an inducible mouse model (RbF/F;K14creERTM), shows that p107 exerts specific tumor suppressor functions in its absence. After simultaneous absence of pRb and p107, p53 transcriptional function is impaired and Pten expression is reduced. All mutant mice develop spontaneous squamous tumors carcinomas rapidly. Gene expression analysis of mouse tumors, besides supporting the impaired p53 function and the susceptibility to Akt/mTOR inhibitors, also revealed significant overlap with human squamous carcinomas. Thus, RbF/F;K14creERTM;p107-/- may constitute a new mouse model for these malignancies. Collectively, these data demonstrate the existence of a previously unreported functional connection between pRb, Pten and p53 tumor suppressors, through p107, of a particular relevance in squamous tumor development.
A novel tumor suppressor network in squamous malignancies.
Specimen part
View SamplesA permantly active form of the oncogene Akt was expressed in the keratinocytes of the basal proliferative layer of the epidermis. Stem cells of the hair follicle expressing the cell surface marker CD34 were isolated. RNA form the CD34(+) and CD34(-) keratinocytes was extracted and and hybridized to Mouse Genome 430 2.0 Affymetrix arrays.
Akt signaling leads to stem cell activation and promotes tumor development in epidermis.
Specimen part
View SamplesThe epidermal-specific ablation of Rb gene leads to increased proliferation, aberrant differentiation, and the disengagement of these processes in vivo and in vitro. These differences in phenotype are more severe with the loss of p107, demonstrating the functional compensation between pRb and p107. As p107 and p130 also exert overlapping functions in epidermis, we have generated Rb(F19/F19)K14cre;Rbl2-/- (pRb-;p130-) mice to analyze possible functional redundancies between pRb and p130. The epidermal phenotype was very similar between pRb- and pRb-;p130- mice, suggesting that pRb and p130 activities are not redundant in epidermis. Importantly, we can correlate the proliferation differences with specific changes in gene expression between pRb-, pRb-;p107- and pRb-;p130- primary keratinocytes using microarray analysis, and explain the phenotypes in the context of altered E2F expression and functionality. Our findings support a model in which the distinct retinoblastoma family members, in conjunction with E2F members, play a central role in regulating epidermal homeostasis through specific or overlapping activities.
Gene profiling approaches help to define the specific functions of retinoblastoma family in epidermis.
Specimen part
View SamplesThe 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.
Spontaneous squamous cell carcinoma induced by the somatic inactivation of retinoblastoma and Trp53 tumor suppressors.
Specimen part
View SamplesAberrant activation of the Akt pathway has been implicated in several human pathologies including cancer. However, current knowledge on the involvement of Akt signaling in development is limited. Previous data have suggested that Akt-mediated signaling may be an essential mediator of epidermal homeostasis through cell autonomous and non-cell autonomous mechanisms. Here we report the developmental consequences of deregulated Akt activity in the basal layer of stratified epithelia, mediated by the expression of a constitutively active Akt1
Constitutively active Akt induces ectodermal defects and impaired bone morphogenetic protein signaling.
Age, Specimen part
View SamplesThe epidermal specific ablation of Trp53 gene leads to the spontaneous development of aggressive tumors in mice through a process that is accelerated by the simultaneous ablation of Rb gene. Since alterations of p53-dependent pathway are common hallmarks of aggressive, poor prognostic human cancers, these mouse models can recapitulate the molecular features of some of these human malignancies. To evaluate this possibility, gene expression microarray analysis was performed in mouse samples. The mouse tumors display increased expression of cell cycle and chromosomal instability associated genes. Remarkably, they are also enriched in human embryonic stem cell gene signatures, a characteristic feature of human aggressive tumors. Using cross-species comparison and meta-analytical approaches, we also observed that spontaneous mouse tumors display robust similarities with gene expression profiles of human tumors bearing mutated TP53, or displaying poor prognostic outcome, from multiple body tissues. We have obtained a 20-gene signature whose genes are overexpressed in mouse tumors and can identify human tumors with poor outcome from breast cancer, astrocytoma and multiple myeloma. This signature was consistently overexpressed in additional mouse tumors using microarray analysis. Two of the genes of this signature, AURKA and UBE2C, were validated in human breast and cervical cancer as potential biomarkers of malignancy. Our analyses demonstrate that these mouse models are promising preclinical tools aimed to search for malignancy biomarkers and to test targeted therapies of prospective use in human aggressive tumors and/or with p53 mutation or inactivation.
Gene expression profiling of mouse p53-deficient epidermal carcinoma defines molecular determinants of human cancer malignancy.
Age, Specimen part
View SamplesThe specific deletion of Rb gene in epidermis leads to altered proliferation and differentiation, but not to the development of spontaneous tumors. Our previous data have demonstrated the existence of a functional compensation of Rb loss by Rbl1 (p107) in as the phenotypic differences with respect to controls are intensified. However, the possible evolution of this aggravated phenotype, in particular in relationship with tumorigenesis, has not been evaluated due to the premature death of the double deficient mice. We have now investigated whether p107 can also act as a tumor suppressor in pRb-deficient epidermis using different experimental approaches. We found spontaneous tumor development in doubly-deficient skin grafts. Moreover, Rb-deficient keratinocytes are susceptible to Ha-ras-induced transformation, and this susceptibility is enhanced by p107 loss. Further functional analyses, including microarray gene expression profiling, indicated that the loss of p107, in the absence of pRb, produces the reduction of p53-dependent pro-apoptotic signals. Overall, our data demonstrate that p107 behaves as a tumor suppressor in epidermis in the absence of pRb and suggest novel tumor-suppressive roles for p107 in the context of functional p53 and activated Ras
p107 acts as a tumor suppressor in pRb-deficient epidermis.
Specimen part
View SamplesObjectives: Phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) is commonly altered in many human tumors, leading to the activation of p110 enzymatic activity that stimulates growth factor-independent cell growth. PIK3CA alterations such as mutation, gene amplification and overexpression are common in head and neck squamous cell carcinoma (HNSCC) and. We aim to explore how these alterations and clinical outcome are associated, as well as the molecular mechanisms involved.
Overexpression of PIK3CA in head and neck squamous cell carcinoma is associated with poor outcome and activation of the YAP pathway.
Specimen part
View SamplesCdk4/6 inhibitors have shown to increase overall survival in hormone-positive breast tumors, but whether other solid tumors could respond to these inhibitors has not yet defined. Here we show that Palbociclib (a Cdk4/6 specific inhibitor in clinic use) treatment exerts antiproliferative effects in vivo using a bladder cancer cell lines.
CDK4/6 Inhibitor as a Novel Therapeutic Approach for Advanced Bladder Cancer Independently of <i>RB1</i> Status.
Specimen part, Cell line
View SamplesWe report that Klebsiella pneumoniae promote Th1 cell induction in colon. To examine the influence of Klebsiella on colonic epithelial cells (ECs) and lamina propria CD11c+ dendritic cells (DCs), we performed RNA seq on them. Germ free mice were orally inoculated with Kp-2H7 or BAA-2552 and total RNA was isolated from colonic ECs and DCs 1 week after inoculation. Furthermore, we examined the involvement of TLRs in induction of Th1 cells using Myd88 KO, Trif KO, Myd88/Trif DKO mice. These deficient germ free mice were orally inoculated with Kp-2H7 and total RNA was isolated from colonic ECs 3 weeks after inoculation. Overall design: The gene expression of colonic ECs and DCs isolated from germ free mice, and GF mice inoculated with Kp-2H7 or BAA-2552, and colonic ECs isolated from GF Myd88 KO, Trif KO or Myd88/Trif DKO mice inoculated with Kp-2H7.
Ectopic colonization of oral bacteria in the intestine drives T<sub>H</sub>1 cell induction and inflammation.
Specimen part, Cell line, Subject
View Samples