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Molecular and functional characteristics of ovarian surface epithelial cells transformed by KrasG12D and loss of Pten in a mouse model in vivo.

Mullany LK, Fan HY, Liu Z, White LD, Marshall A, Gunaratne P, Anderson ML, Creighton CJ, Xin L, Deavers M, Wong KK, Richards JS - Oncogene (2011)

Bottom Line: Ovarian cancer is a complex and deadly disease that remains difficult to detect at an early curable stage.Furthermore, although some oncogenic (Kras, Pten/PI3K and Trp53) pathways that are frequently mutated, deleted or amplified in ovarian cancer are known, how these pathways initiate and drive specific morphological phenotypes and tumor outcomes remain unclear.We propose that elevated TRP53 and miR-34a-c may exert negatively regulatory effects that reduce the proliferative potential of OSE cells leading to the low-grade serous adenocarcinoma phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.

ABSTRACT
Ovarian cancer is a complex and deadly disease that remains difficult to detect at an early curable stage. Furthermore, although some oncogenic (Kras, Pten/PI3K and Trp53) pathways that are frequently mutated, deleted or amplified in ovarian cancer are known, how these pathways initiate and drive specific morphological phenotypes and tumor outcomes remain unclear. We recently generated Pten(fl/fl); Kras(G12D); Amhr2-Cre mice to disrupt the Pten gene and express a stable mutant form of Kras(G12D) in ovarian surface epithelial (OSE) cells. On the basis of histopathologic criteria, the mutant mice developed low-grade ovarian serous papillary adenocarcinomas at an early age and with 100% penetrance. This highly reproducible phenotype provides the first mouse model in which to study this ovarian cancer subtype. OSE cells isolated from ovaries of mutant mice at 5 and 10 weeks of age exhibit temporal changes in the expression of specific Mullerian epithelial marker genes, grow in soft agar and develop ectopic invasive tumors in recipient mice, indicating that the cells are transformed. Gene profiling identified specific mRNAs and microRNAs differentially expressed in purified OSE cells derived from tumors of the mutant mice compared with wild-type OSE cells. Mapping of transcripts or genes between the mouse OSE mutant data sets, the Kras signature from human cancer cell lines and the human ovarian tumor array data sets, documented significant overlap, indicating that KRAS is a key driver of OSE transformation in this context. Two key hallmarks of the mutant OSE cells in these mice are the elevated expression of the tumor-suppressor Trp53 (p53) and its microRNA target, miR-34a-c. We propose that elevated TRP53 and miR-34a-c may exert negatively regulatory effects that reduce the proliferative potential of OSE cells leading to the low-grade serous adenocarcinoma phenotype.

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Mutations in either Pten or Kras alone alter gene expression in purified OSE cells. A.) OSE cells were isolated from Pten;Amhr2-cre, Kras;Amhr2-cre, Pten;Kras;Amhr2-cre (tumor-bearing, T) and WT mice. The transformed cells (T) grow rapidly and eventually form clusters whereas the WT and KRAS OSE cells exhibit slower growth and well-defined boarders. OSE cells from the Pten  cells, like the transformed (T) cells, lack distinct borders but are not transformed. B.) The transformed cells and the Pten  cells exhibit striking similarities in the expression of specific mRNAs, including Trp53 and its target p21 (Cdkna1).
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Figure 6: Mutations in either Pten or Kras alone alter gene expression in purified OSE cells. A.) OSE cells were isolated from Pten;Amhr2-cre, Kras;Amhr2-cre, Pten;Kras;Amhr2-cre (tumor-bearing, T) and WT mice. The transformed cells (T) grow rapidly and eventually form clusters whereas the WT and KRAS OSE cells exhibit slower growth and well-defined boarders. OSE cells from the Pten cells, like the transformed (T) cells, lack distinct borders but are not transformed. B.) The transformed cells and the Pten cells exhibit striking similarities in the expression of specific mRNAs, including Trp53 and its target p21 (Cdkna1).

Mentions: To further characterize the specific effects of disrupting the PI3K pathway or activating the RAS pathway, we isolated and cultured OSE cells obtained from ovaries of Ptenfl/fl;Amhr2-Cre and KrasG12D;Amhr2-Cre mice as well as from the Pten fl/fl;KrasG12D;Amhr2-Cre mice and WT mice at 10 week of age. Cells from each genotype exhibited slightly different morphology (Fig 6A) and only cells from the Pten fl/fl;KrasG12D;Amhr2-Cre mice were transformed. Genes that were highly expressed in the OSE cells from the tumor (T) bearing ovaries of the Pten fl/fl;KrasG12D;Amhr2-Cre mice compared to WT were also elevated in OSE cells from the Ptenfl/fl;Amhr2-Cre mice. These include Podxl, markers of Mullerian epithelium (Wt1and Hoxa9), Trp53 and one of its target genes Cdkn1a (p21) as well as a marker of serous adenocarcinomas, Cldn3. These genes were less dramatically increased in the KrasG12D;Amhr2-Cre mice indicating that disrupting the PI3K pathway alone exerts the more potent response in this context (Fig 6B).


Molecular and functional characteristics of ovarian surface epithelial cells transformed by KrasG12D and loss of Pten in a mouse model in vivo.

Mullany LK, Fan HY, Liu Z, White LD, Marshall A, Gunaratne P, Anderson ML, Creighton CJ, Xin L, Deavers M, Wong KK, Richards JS - Oncogene (2011)

Mutations in either Pten or Kras alone alter gene expression in purified OSE cells. A.) OSE cells were isolated from Pten;Amhr2-cre, Kras;Amhr2-cre, Pten;Kras;Amhr2-cre (tumor-bearing, T) and WT mice. The transformed cells (T) grow rapidly and eventually form clusters whereas the WT and KRAS OSE cells exhibit slower growth and well-defined boarders. OSE cells from the Pten  cells, like the transformed (T) cells, lack distinct borders but are not transformed. B.) The transformed cells and the Pten  cells exhibit striking similarities in the expression of specific mRNAs, including Trp53 and its target p21 (Cdkna1).
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Related In: Results  -  Collection

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Figure 6: Mutations in either Pten or Kras alone alter gene expression in purified OSE cells. A.) OSE cells were isolated from Pten;Amhr2-cre, Kras;Amhr2-cre, Pten;Kras;Amhr2-cre (tumor-bearing, T) and WT mice. The transformed cells (T) grow rapidly and eventually form clusters whereas the WT and KRAS OSE cells exhibit slower growth and well-defined boarders. OSE cells from the Pten cells, like the transformed (T) cells, lack distinct borders but are not transformed. B.) The transformed cells and the Pten cells exhibit striking similarities in the expression of specific mRNAs, including Trp53 and its target p21 (Cdkna1).
Mentions: To further characterize the specific effects of disrupting the PI3K pathway or activating the RAS pathway, we isolated and cultured OSE cells obtained from ovaries of Ptenfl/fl;Amhr2-Cre and KrasG12D;Amhr2-Cre mice as well as from the Pten fl/fl;KrasG12D;Amhr2-Cre mice and WT mice at 10 week of age. Cells from each genotype exhibited slightly different morphology (Fig 6A) and only cells from the Pten fl/fl;KrasG12D;Amhr2-Cre mice were transformed. Genes that were highly expressed in the OSE cells from the tumor (T) bearing ovaries of the Pten fl/fl;KrasG12D;Amhr2-Cre mice compared to WT were also elevated in OSE cells from the Ptenfl/fl;Amhr2-Cre mice. These include Podxl, markers of Mullerian epithelium (Wt1and Hoxa9), Trp53 and one of its target genes Cdkn1a (p21) as well as a marker of serous adenocarcinomas, Cldn3. These genes were less dramatically increased in the KrasG12D;Amhr2-Cre mice indicating that disrupting the PI3K pathway alone exerts the more potent response in this context (Fig 6B).

Bottom Line: Ovarian cancer is a complex and deadly disease that remains difficult to detect at an early curable stage.Furthermore, although some oncogenic (Kras, Pten/PI3K and Trp53) pathways that are frequently mutated, deleted or amplified in ovarian cancer are known, how these pathways initiate and drive specific morphological phenotypes and tumor outcomes remain unclear.We propose that elevated TRP53 and miR-34a-c may exert negatively regulatory effects that reduce the proliferative potential of OSE cells leading to the low-grade serous adenocarcinoma phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.

ABSTRACT
Ovarian cancer is a complex and deadly disease that remains difficult to detect at an early curable stage. Furthermore, although some oncogenic (Kras, Pten/PI3K and Trp53) pathways that are frequently mutated, deleted or amplified in ovarian cancer are known, how these pathways initiate and drive specific morphological phenotypes and tumor outcomes remain unclear. We recently generated Pten(fl/fl); Kras(G12D); Amhr2-Cre mice to disrupt the Pten gene and express a stable mutant form of Kras(G12D) in ovarian surface epithelial (OSE) cells. On the basis of histopathologic criteria, the mutant mice developed low-grade ovarian serous papillary adenocarcinomas at an early age and with 100% penetrance. This highly reproducible phenotype provides the first mouse model in which to study this ovarian cancer subtype. OSE cells isolated from ovaries of mutant mice at 5 and 10 weeks of age exhibit temporal changes in the expression of specific Mullerian epithelial marker genes, grow in soft agar and develop ectopic invasive tumors in recipient mice, indicating that the cells are transformed. Gene profiling identified specific mRNAs and microRNAs differentially expressed in purified OSE cells derived from tumors of the mutant mice compared with wild-type OSE cells. Mapping of transcripts or genes between the mouse OSE mutant data sets, the Kras signature from human cancer cell lines and the human ovarian tumor array data sets, documented significant overlap, indicating that KRAS is a key driver of OSE transformation in this context. Two key hallmarks of the mutant OSE cells in these mice are the elevated expression of the tumor-suppressor Trp53 (p53) and its microRNA target, miR-34a-c. We propose that elevated TRP53 and miR-34a-c may exert negatively regulatory effects that reduce the proliferative potential of OSE cells leading to the low-grade serous adenocarcinoma phenotype.

Show MeSH
Related in: MedlinePlus