ABSTRACT: Genomic profiling of human Tert/shp53/Ras mesenchymal cells isolated from several xenografted tumors and their non-transformant epithelial counterparts
Project description:The epithelial-mesenchymal transition (EMT) is an embryonic transdiffrentiation program which consists of the conversion of polarized epithelial cells into a motile mesenchymal phenotype. EMT is aberrantly reactivated during tumor progression, promoting metastatic dissemination. Herein, we demonstrate that EMT permissive conditions also favor tumor initiation by minimizing the number of events required for neoplastic transformation. We further demonstrated that even partial commitment of human mammary epithelial cells into an EMT program is sufficient to confer malignant properties, suggesting that the reactivation of embryonic EMT inducers participate to the primary tumor growth long before the initiation of the invasion-metastasis cascade. Human mammary epithelial cells (HMEC) were sequentially depleted in p53 through RNA interference (shp53), transduced with H-RasG12V and immortalized by hTert. Two different Tert/shp53/Ras cell population emerge that display either an epithelial (Epi) or a mesenchymal (Mes) phenotype. Gene expression profiles of the Tert/shp53 control cells and of tert/shp53/Ras/Epi and Tert/shp53/Ras/Mes were analyzed.
Project description:The epithelial-mesenchymal transition (EMT) is an embryonic transdifferentiation program which consists of the conversion of polarized epithelial cells into a motile mesenchymal phenotype. EMT is aberrantly reactivated during tumor progression, promoting metastatic dissemination. Herein, we demonstrate that EMT-permissive conditions also favor tumor initiation by minimizing the number of events required for neoplastic transformation. We further demonstrated that even the partial commitment of human mammary epithelial cells into an EMT program is sufficient to confer malignant properties, suggesting that the reactivation of embryonic EMT inducers participates to the primary tumor growth long before the initiation of the invasion-metastasis cascade. arrayCGH profiles analysis of Tert/shp53/Ras epithelial HMEC derivatives and 3 different tumors generated after injection of mesenchymal Tert/shp53/Ras/ HMEC derivatives in fad pads of nude mice
Project description:K-Ras mutations occur frequently in epithelial cancers. Using shRNAs to deplete K-Ras in lung and pancreatic cancer cell lines harboring K-Ras mutations, two classes were identified—lines that do or do not require K-Ras to maintain viability. Comparing these two classes of cancer cells revealed a gene expression signature in K-Ras-dependent cells, associated with a well-differentiated epithelial phenotype, which was also seen in primary tumors. Several of these genes encode pharmacologically tractable proteins, such as Syk and Ron kinases and integrin beta6, depletion of which induces epithelial-mesenchymal transformation (EMT) and apoptosis specifically in K-Ras-dependent cells. These findings indicate that epithelial differentiation and tumor cell viability are associated, and that EMT regulators in “K-Ras-addicted” cancers represent candidate therapeutic targets.
Project description:Our study proposes a precise mechanistic classification of clinical neuroblastoma phenotypes that is based on telomere maintenance mechanisms and RAS or p53 pathway mutations. A crucial factor in telomere maintenance is overexpression of TERT. We therefore determined a TERT expression threshold to identify MYCN-WT TERT-WT tumors whose TERT mRNA levels are comparable to those of tumors bearing MYCN or TERT alterations.
Project description:Our study proposes a precise mechanistic classification of clinical neuroblastoma phenotypes that is based on telomere maintenance mechanisms and RAS or p53 pathway mutations. A crucial factor in telomere maintenance is overexpression of TERT. We therefore determined a TERT expression threshold to identify MYCNWT TERTWT tumors whose TERT mRNA levels are comparable to those of tumors bearing MYCN or TERT alterations.
Project description:K-Ras mutations occur frequently in epithelial cancers. Using shRNAs to deplete K-Ras in lung and pancreatic cancer cell lines harboring K-Ras mutations, two classes were identified—lines that do or do not require K-Ras to maintain viability. Comparing these two classes of cancer cells revealed a gene expression signature in K-Ras-dependent cells, associated with a well-differentiated epithelial phenotype, which was also seen in primary tumors. Several of these genes encode pharmacologically tractable proteins, such as Syk and Ron kinases and integrin beta6, depletion of which induces epithelial-mesenchymal transformation (EMT) and apoptosis specifically in K-Ras-dependent cells. These findings indicate that epithelial differentiation and tumor cell viability are associated, and that EMT regulators in “K-Ras-addicted” cancers represent candidate therapeutic targets. Expression analysis: 40 Samples representing K-Ras mutant cancer cell lines derived from various tissue types were hybridized to the Affymetrix GeneChip Human X3P Array. Copy number analysis: 10 samples representing K-Ras mutant cancer cell lines were hybridized to the Affymetrix Mapping 500K Set Arrays (250K_Nsp_SNP and 250K_Sty2_SNP). Reference data included 63 randomly chosen female samples (supplementary file Sing_etal_CopyNumber_NormalSamples.txt) from the HapMap project Affy 500K SNP data (http://www.hapmap.org/downloads/raw_data/affy500k).
Project description:The newly identified claudin-low subtype of cancer is believed to represent the most primitive breast malignancies, having arisen from transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this hypothesis, we show both in vitro and in vivo that transcription factors inducing epithelial-mesenchymal transition can drive the development of claudin-low tumors from differentiated mammary epithelial cells, by playing a dual role in cell transformation and dedifferentiation. Human mammary epithelial cells (HMEC) were sequentially immortalized by hTert (HMEC-hTert), transduced with Twist1 or Zeb2 or Zeb1 and then with H-RasG12V. The gene expression profiles of the resulting HMEC-hTert-Twist1+Ras, HMEC-hTert-Zeb1+Ras and HMEC-hTert-Zeb2+Ras cell lines were defined. HMEC-hTert-Twist1+Ras and HMEC-hTert-Zeb2+Ras cell lines were additionally cultured in presence of TGFM-CM-^C? and their gene expression profiles were determined. The parental HMEC-hTert, the luminal MCF7 and the basal B MDMB157cell lines were used as controls.
Project description:We induced liver tumors by transforming liver progenitor cells (LPC) with retroviruses expressing oncogenic Ras coupled to tetracycline transactivator together with an inducible shRNA targeting p53. Transformed LPCs were orthotopical transplanted into recipient livers and after tumor onset mice were fed with either Doxycycline containing chow or normal chow. 8 days later tumors were harvested and RNA was extracted. RNA was extracted using Trizol. For microarray experiment, HrasV12 driven liver tumors harboring tet-off shp53 were treated with Doxycycline for 0 day (p53 OFF, as control) or 8 days (p53 ON). Samples were assessed by Affymetrix 430 2.0 mouse microarray.
Project description:Epithelial to Mesenchymal Transition (EMT) has been associated with cancer cell heterogeneity, plasticity and metastasis. It has been the subject of several modeling effort. This logical model of the EMT cellular network aims to assess microenvironmental signals controlling cancer-associated phenotypes amid the EMT continuum. Its outcomes relate to the qualitative degrees of cell adhesions by adherent junctions and focal adhesions, two features affected during EMT. Model attractors recover epithelial, mesenchymal and hybrid phenotypes, and simulations show that hybrid phenotypes may arise through independent molecular paths, involving stringent extrinsic signals.
Of particular interest, model predictions and their experimental validations indicated that: 1) ECM stiffening is a prerequisite for cells overactivating FAK-SRC to upregulate SNAIL1 and acquire a mesenchymal phenotype, and 2) FAK-SRC inhibition of cell-cell contacts through the Receptor Protein Tyrosine Phosphates kappa leads to the acquisition of a full mesenchymal rather than a hybrid phenotype.