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Conditional Inactivation of Pten with EGFR Overexpression in Schwann Cells Models Sporadic MPNST.

Keng VW, Watson AL, Rahrmann EP, Li H, Tschida BR, Moriarity BS, Choi K, Rizvi TA, Collins MH, Wallace MR, Ratner N, Largaespada DA - Sarcoma (2012)

Bottom Line: The genetic mechanisms involved in the transformation from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis-type-1- (NF1-)associated or sporadic malignant peripheral nerve sheath tumors (MPNSTs) remain unclear.It is hypothesized that many genetic changes are involved in transformation.We tested if these two genes cooperate in the evolution of PNSTs.

View Article: PubMed Central - PubMed

Affiliation: Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA ; Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA ; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA ; Brain Tumor Program, University of Minnesota, Minneapolis, MN 55455, USA ; Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.

ABSTRACT
The genetic mechanisms involved in the transformation from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis-type-1- (NF1-)associated or sporadic malignant peripheral nerve sheath tumors (MPNSTs) remain unclear. It is hypothesized that many genetic changes are involved in transformation. Recently, it has been shown that both phosphatase and tensin homolog (PTEN) and epidermal growth factor receptor (EGFR) play important roles in the initiation of peripheral nerve sheath tumors (PNSTs). In human MPNSTs, PTEN expression is often reduced, while EGFR expression is often induced. We tested if these two genes cooperate in the evolution of PNSTs. Transgenic mice were generated carrying conditional floxed alleles of Pten, and EGFR was expressed under the control of the 2',3'-cyclic nucleotide 3'phosphodiesterase (Cnp) promoter and a desert hedgehog (Dhh) regulatory element driving Cre recombinase transgenic mice (Dhh-Cre). Complete loss of Pten and EGFR overexpression in Schwann cells led to the development of high-grade PNSTs. In vitro experiments using immortalized human Schwann cells demonstrated that loss of PTEN and overexpression of EGFR cooperate to increase cellular proliferation and anchorage-independent colony formation. This mouse model can rapidly recapitulate PNST onset and progression to high-grade PNSTs, as seen in sporadic MPNST patients.

No MeSH data available.


Related in: MedlinePlus

Establishing a novel sporadic peripheral nerve sheath tumor (PNST) progression mouse model. (a) Transgenes used to establish the novel sporadic PNST mouse model. Cnp-EGFR consists of the Cnp regulatory elements driving the EGFR gene expression specifically in Schwann cells and/or their precursor cells. Floxed Pten allele consists of the essential exons 4 and 5 of the Pten gene floxed with loxP sites. Dhh-Cre consists of the Dhh regulatory elements driving Cre recombinase to remove the loxP sites and allow for the inactivation of the floxed Pten alleles specifically in Schwann cells and/or their precursor cells. (b) Breeding strategy for generating experimental and control animals. Transgenic mice each carrying a single transgene was bred to obtain doubly transgenic mice Dhh-Cre; Ptenflox/+ mice (Pten-het). Doubly transgenic mice were then bred with remaining transgene to obtain triple transgenic Dhh-Cre; Ptenflox/+; Cnp-EGFR mice (Pten-het/C-EGFR). Finally, Pten-het mice were bred with Pten-het/C-EGFR mice to obtain the required experimental and control cohorts. Dhh-Cre; Ptenflox/flox; Cnp-EGFR (ΔPten/C-EGFR) and Dhh-Cre; Ptenflox/+; Cnp-EGFR (Pten-het/C-EGFR) experimental cohorts. Dhh-Cre; Ptenflox/flox (ΔPten), Pten-het and Cnp-EGFR (C-EGFR) control cohorts. (c) Kaplan-Meier survival curves of various experimental and control cohorts. Pten dosage augmented the peripheral nervous system phenotype in the context of EGFR overexpression in Schwann cell and/or their precursor cells, resulting in decreased survival. P: log-rank test.
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fig1: Establishing a novel sporadic peripheral nerve sheath tumor (PNST) progression mouse model. (a) Transgenes used to establish the novel sporadic PNST mouse model. Cnp-EGFR consists of the Cnp regulatory elements driving the EGFR gene expression specifically in Schwann cells and/or their precursor cells. Floxed Pten allele consists of the essential exons 4 and 5 of the Pten gene floxed with loxP sites. Dhh-Cre consists of the Dhh regulatory elements driving Cre recombinase to remove the loxP sites and allow for the inactivation of the floxed Pten alleles specifically in Schwann cells and/or their precursor cells. (b) Breeding strategy for generating experimental and control animals. Transgenic mice each carrying a single transgene was bred to obtain doubly transgenic mice Dhh-Cre; Ptenflox/+ mice (Pten-het). Doubly transgenic mice were then bred with remaining transgene to obtain triple transgenic Dhh-Cre; Ptenflox/+; Cnp-EGFR mice (Pten-het/C-EGFR). Finally, Pten-het mice were bred with Pten-het/C-EGFR mice to obtain the required experimental and control cohorts. Dhh-Cre; Ptenflox/flox; Cnp-EGFR (ΔPten/C-EGFR) and Dhh-Cre; Ptenflox/+; Cnp-EGFR (Pten-het/C-EGFR) experimental cohorts. Dhh-Cre; Ptenflox/flox (ΔPten), Pten-het and Cnp-EGFR (C-EGFR) control cohorts. (c) Kaplan-Meier survival curves of various experimental and control cohorts. Pten dosage augmented the peripheral nervous system phenotype in the context of EGFR overexpression in Schwann cell and/or their precursor cells, resulting in decreased survival. P: log-rank test.

Mentions: Generation of transgenic mice carrying the Dhh gene regulatory element driving Cre recombinase (Dhh-Cre) has been previously described [18] (Figure 1(a)). Transgenic mice carrying the floxed Pten allele with the essential exons 4 and 5 of the Pten gene floxed with loxP sites have been previously described [17] (Figure 1(a)). The transgenic mouse carrying the Cnp gene regulatory element driving EGFR (Cnp-EGFR) has been previously described [13]. Breeding strategy for generating various experimental, and control cohorts is shown in Figure 1(b). Animals were sacrificed when moribund due to paralysis and necropsy performed. All animal work was conducted according to the University of Minnesota's approved animal welfare protocol.


Conditional Inactivation of Pten with EGFR Overexpression in Schwann Cells Models Sporadic MPNST.

Keng VW, Watson AL, Rahrmann EP, Li H, Tschida BR, Moriarity BS, Choi K, Rizvi TA, Collins MH, Wallace MR, Ratner N, Largaespada DA - Sarcoma (2012)

Establishing a novel sporadic peripheral nerve sheath tumor (PNST) progression mouse model. (a) Transgenes used to establish the novel sporadic PNST mouse model. Cnp-EGFR consists of the Cnp regulatory elements driving the EGFR gene expression specifically in Schwann cells and/or their precursor cells. Floxed Pten allele consists of the essential exons 4 and 5 of the Pten gene floxed with loxP sites. Dhh-Cre consists of the Dhh regulatory elements driving Cre recombinase to remove the loxP sites and allow for the inactivation of the floxed Pten alleles specifically in Schwann cells and/or their precursor cells. (b) Breeding strategy for generating experimental and control animals. Transgenic mice each carrying a single transgene was bred to obtain doubly transgenic mice Dhh-Cre; Ptenflox/+ mice (Pten-het). Doubly transgenic mice were then bred with remaining transgene to obtain triple transgenic Dhh-Cre; Ptenflox/+; Cnp-EGFR mice (Pten-het/C-EGFR). Finally, Pten-het mice were bred with Pten-het/C-EGFR mice to obtain the required experimental and control cohorts. Dhh-Cre; Ptenflox/flox; Cnp-EGFR (ΔPten/C-EGFR) and Dhh-Cre; Ptenflox/+; Cnp-EGFR (Pten-het/C-EGFR) experimental cohorts. Dhh-Cre; Ptenflox/flox (ΔPten), Pten-het and Cnp-EGFR (C-EGFR) control cohorts. (c) Kaplan-Meier survival curves of various experimental and control cohorts. Pten dosage augmented the peripheral nervous system phenotype in the context of EGFR overexpression in Schwann cell and/or their precursor cells, resulting in decreased survival. P: log-rank test.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539440&req=5

fig1: Establishing a novel sporadic peripheral nerve sheath tumor (PNST) progression mouse model. (a) Transgenes used to establish the novel sporadic PNST mouse model. Cnp-EGFR consists of the Cnp regulatory elements driving the EGFR gene expression specifically in Schwann cells and/or their precursor cells. Floxed Pten allele consists of the essential exons 4 and 5 of the Pten gene floxed with loxP sites. Dhh-Cre consists of the Dhh regulatory elements driving Cre recombinase to remove the loxP sites and allow for the inactivation of the floxed Pten alleles specifically in Schwann cells and/or their precursor cells. (b) Breeding strategy for generating experimental and control animals. Transgenic mice each carrying a single transgene was bred to obtain doubly transgenic mice Dhh-Cre; Ptenflox/+ mice (Pten-het). Doubly transgenic mice were then bred with remaining transgene to obtain triple transgenic Dhh-Cre; Ptenflox/+; Cnp-EGFR mice (Pten-het/C-EGFR). Finally, Pten-het mice were bred with Pten-het/C-EGFR mice to obtain the required experimental and control cohorts. Dhh-Cre; Ptenflox/flox; Cnp-EGFR (ΔPten/C-EGFR) and Dhh-Cre; Ptenflox/+; Cnp-EGFR (Pten-het/C-EGFR) experimental cohorts. Dhh-Cre; Ptenflox/flox (ΔPten), Pten-het and Cnp-EGFR (C-EGFR) control cohorts. (c) Kaplan-Meier survival curves of various experimental and control cohorts. Pten dosage augmented the peripheral nervous system phenotype in the context of EGFR overexpression in Schwann cell and/or their precursor cells, resulting in decreased survival. P: log-rank test.
Mentions: Generation of transgenic mice carrying the Dhh gene regulatory element driving Cre recombinase (Dhh-Cre) has been previously described [18] (Figure 1(a)). Transgenic mice carrying the floxed Pten allele with the essential exons 4 and 5 of the Pten gene floxed with loxP sites have been previously described [17] (Figure 1(a)). The transgenic mouse carrying the Cnp gene regulatory element driving EGFR (Cnp-EGFR) has been previously described [13]. Breeding strategy for generating various experimental, and control cohorts is shown in Figure 1(b). Animals were sacrificed when moribund due to paralysis and necropsy performed. All animal work was conducted according to the University of Minnesota's approved animal welfare protocol.

Bottom Line: The genetic mechanisms involved in the transformation from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis-type-1- (NF1-)associated or sporadic malignant peripheral nerve sheath tumors (MPNSTs) remain unclear.It is hypothesized that many genetic changes are involved in transformation.We tested if these two genes cooperate in the evolution of PNSTs.

View Article: PubMed Central - PubMed

Affiliation: Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA ; Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA ; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA ; Brain Tumor Program, University of Minnesota, Minneapolis, MN 55455, USA ; Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.

ABSTRACT
The genetic mechanisms involved in the transformation from a benign neurofibroma to a malignant sarcoma in patients with neurofibromatosis-type-1- (NF1-)associated or sporadic malignant peripheral nerve sheath tumors (MPNSTs) remain unclear. It is hypothesized that many genetic changes are involved in transformation. Recently, it has been shown that both phosphatase and tensin homolog (PTEN) and epidermal growth factor receptor (EGFR) play important roles in the initiation of peripheral nerve sheath tumors (PNSTs). In human MPNSTs, PTEN expression is often reduced, while EGFR expression is often induced. We tested if these two genes cooperate in the evolution of PNSTs. Transgenic mice were generated carrying conditional floxed alleles of Pten, and EGFR was expressed under the control of the 2',3'-cyclic nucleotide 3'phosphodiesterase (Cnp) promoter and a desert hedgehog (Dhh) regulatory element driving Cre recombinase transgenic mice (Dhh-Cre). Complete loss of Pten and EGFR overexpression in Schwann cells led to the development of high-grade PNSTs. In vitro experiments using immortalized human Schwann cells demonstrated that loss of PTEN and overexpression of EGFR cooperate to increase cellular proliferation and anchorage-independent colony formation. This mouse model can rapidly recapitulate PNST onset and progression to high-grade PNSTs, as seen in sporadic MPNST patients.

No MeSH data available.


Related in: MedlinePlus