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Telomere dysfunction suppresses multiple endocrine neoplasia in mice.

Lee JH, Anver M, Kost-Alimova M, Protopopov A, DePinho RA, Rane SG - Genes Cancer (2014)

Bottom Line: Using this model, here we provide evidence supporting an important role for telomerase in the pathogenesis of MEN.We observed increased aneuploidy in Cdk4 (R/R) fibroblasts along with significantly elevated telomerase activity and telomere length in Cdk4 (R/R) islets and embryonic fibroblasts.Further, mTERC (-/-) Cdk4 (R/R) fibroblasts display reduced transformation potential.

View Article: PubMed Central - PubMed

Affiliation: Diabetes, Endocrinology & Obesity Branch, National Institute of Diabetes & Digestive & Kidney Diseases, Bethesda, MD.

ABSTRACT
Multiple endocrine neoplasia (MEN) syndrome is typified by the occurrence of tumors in two or more hormonal tissues. Whereas the genetics of MEN syndrome is relatively well understood, the tumorigenic mechanisms for these cancers remain relatively obscure. The Cdk4 (R24C) mouse model develops highly penetrant pituitary tumors and endocrine pancreas adenomas, and, as such, this model is appropriate to gain insight into mechanisms underlying MEN. Using this model, here we provide evidence supporting an important role for telomerase in the pathogenesis of MEN. We observed increased aneuploidy in Cdk4 (R/R) fibroblasts along with significantly elevated telomerase activity and telomere length in Cdk4 (R/R) islets and embryonic fibroblasts. To better understand the role of telomerase, we generated Cdk4 (R24C) mice with inactivation of the mTERC locus, which codes for the essential RNA component of the enzyme telomerase (mTERC (-/-) Cdk4 (R/R) mice). Embryonic fibroblasts and islets derived from mTERC (-/-) Cdk4 (R/R) mice exhibit reduced telomere length and proliferative capacity. Further, mTERC (-/-) Cdk4 (R/R) fibroblasts display reduced transformation potential. Importantly, mTERC (-/-) Cdk4 (R/R) mice display significantly reduced spontaneous tumorigenesis. Strikingly, we observed dramatic suppression of pituitary tumors and endocrine pancreas adenomas in mTERC (-/-) Cdk4 (R/R) mice. Telomere dysfunction suppressed tumor initiation and increased latency of tumor development while not affecting the progression of established tumors. In summary, these results are suggestive of an important role for telomerase in tumor development in the Cdk4 (R24C) mouse model, specifically in the genesis of tumors in the pituitary and the endocrine pancreas.

No MeSH data available.


Related in: MedlinePlus

Role of telomerase activity in Cdk4R/R mediated cell proliferation and transformationTelomerase Activity in islets (A) and MEFs (B) from Cdk4+/+ (open boxes) and Cdk4R/R (closed boxes) mice. TRAP assay was performed using 500 ng of protein from islets of 17 month old mice and from MEF cell lysate. (C) Mating scheme to generate mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. Mating of Cdk4R/R mice with G2 mTERC−/− mice produced heterozygous mTERC−/+ Cdk4+/R mice and subsequently generationally aged mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. (D) Average telomere length (in relative fluorescent units) of metaphase from MEF cultures from mTERC+/+ Cdk4R/R (open box), mTERC−/− Cdk4R/R (closed box) and mTERC−/− Cdk4+/+ (hashed box) mice as determined by Q-FISH. (E) Proliferation curves of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs. (F) Colony formation following seeding at 3500 cells of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs per 6 well plate and 14 days of culture. All data presented in experiments shown in each figure panel here represents the mean of at least three independent experiments and along standard error of mean. Statistical analysis was performed by student t-test.
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Figure 2: Role of telomerase activity in Cdk4R/R mediated cell proliferation and transformationTelomerase Activity in islets (A) and MEFs (B) from Cdk4+/+ (open boxes) and Cdk4R/R (closed boxes) mice. TRAP assay was performed using 500 ng of protein from islets of 17 month old mice and from MEF cell lysate. (C) Mating scheme to generate mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. Mating of Cdk4R/R mice with G2 mTERC−/− mice produced heterozygous mTERC−/+ Cdk4+/R mice and subsequently generationally aged mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. (D) Average telomere length (in relative fluorescent units) of metaphase from MEF cultures from mTERC+/+ Cdk4R/R (open box), mTERC−/− Cdk4R/R (closed box) and mTERC−/− Cdk4+/+ (hashed box) mice as determined by Q-FISH. (E) Proliferation curves of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs. (F) Colony formation following seeding at 3500 cells of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs per 6 well plate and 14 days of culture. All data presented in experiments shown in each figure panel here represents the mean of at least three independent experiments and along standard error of mean. Statistical analysis was performed by student t-test.

Mentions: Telomerase activation is correlated with the ability of cells to escape senescence, undergo immortalization and be susceptible to transformation [46]. We examined whether telomerase activity played a role in the Cdk4R/R islet tumorigenesis model. Pancreas were harvested from old (>12 months of age) Cdk4+/+ and Cdk4R/R mice and islets were isolated for analysis of telomerase activity. We observed a significantly elevated telomerase activity in Cdk4R/R islets compared to islets isolated from comparatively old-aged Cdk4+/+ mice (Figure 2A) suggestive of a role for telomerase in islet tumorigenesis.


Telomere dysfunction suppresses multiple endocrine neoplasia in mice.

Lee JH, Anver M, Kost-Alimova M, Protopopov A, DePinho RA, Rane SG - Genes Cancer (2014)

Role of telomerase activity in Cdk4R/R mediated cell proliferation and transformationTelomerase Activity in islets (A) and MEFs (B) from Cdk4+/+ (open boxes) and Cdk4R/R (closed boxes) mice. TRAP assay was performed using 500 ng of protein from islets of 17 month old mice and from MEF cell lysate. (C) Mating scheme to generate mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. Mating of Cdk4R/R mice with G2 mTERC−/− mice produced heterozygous mTERC−/+ Cdk4+/R mice and subsequently generationally aged mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. (D) Average telomere length (in relative fluorescent units) of metaphase from MEF cultures from mTERC+/+ Cdk4R/R (open box), mTERC−/− Cdk4R/R (closed box) and mTERC−/− Cdk4+/+ (hashed box) mice as determined by Q-FISH. (E) Proliferation curves of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs. (F) Colony formation following seeding at 3500 cells of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs per 6 well plate and 14 days of culture. All data presented in experiments shown in each figure panel here represents the mean of at least three independent experiments and along standard error of mean. Statistical analysis was performed by student t-test.
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Figure 2: Role of telomerase activity in Cdk4R/R mediated cell proliferation and transformationTelomerase Activity in islets (A) and MEFs (B) from Cdk4+/+ (open boxes) and Cdk4R/R (closed boxes) mice. TRAP assay was performed using 500 ng of protein from islets of 17 month old mice and from MEF cell lysate. (C) Mating scheme to generate mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. Mating of Cdk4R/R mice with G2 mTERC−/− mice produced heterozygous mTERC−/+ Cdk4+/R mice and subsequently generationally aged mTERC−/− Cdk4R/R and mTERC+/+ Cdk4R/R mice. (D) Average telomere length (in relative fluorescent units) of metaphase from MEF cultures from mTERC+/+ Cdk4R/R (open box), mTERC−/− Cdk4R/R (closed box) and mTERC−/− Cdk4+/+ (hashed box) mice as determined by Q-FISH. (E) Proliferation curves of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs. (F) Colony formation following seeding at 3500 cells of mTERC−/− Cdk4R/R (closed boxes) and mTERC+/+ Cdk4R/R (open boxes) MEFs per 6 well plate and 14 days of culture. All data presented in experiments shown in each figure panel here represents the mean of at least three independent experiments and along standard error of mean. Statistical analysis was performed by student t-test.
Mentions: Telomerase activation is correlated with the ability of cells to escape senescence, undergo immortalization and be susceptible to transformation [46]. We examined whether telomerase activity played a role in the Cdk4R/R islet tumorigenesis model. Pancreas were harvested from old (>12 months of age) Cdk4+/+ and Cdk4R/R mice and islets were isolated for analysis of telomerase activity. We observed a significantly elevated telomerase activity in Cdk4R/R islets compared to islets isolated from comparatively old-aged Cdk4+/+ mice (Figure 2A) suggestive of a role for telomerase in islet tumorigenesis.

Bottom Line: Using this model, here we provide evidence supporting an important role for telomerase in the pathogenesis of MEN.We observed increased aneuploidy in Cdk4 (R/R) fibroblasts along with significantly elevated telomerase activity and telomere length in Cdk4 (R/R) islets and embryonic fibroblasts.Further, mTERC (-/-) Cdk4 (R/R) fibroblasts display reduced transformation potential.

View Article: PubMed Central - PubMed

Affiliation: Diabetes, Endocrinology & Obesity Branch, National Institute of Diabetes & Digestive & Kidney Diseases, Bethesda, MD.

ABSTRACT
Multiple endocrine neoplasia (MEN) syndrome is typified by the occurrence of tumors in two or more hormonal tissues. Whereas the genetics of MEN syndrome is relatively well understood, the tumorigenic mechanisms for these cancers remain relatively obscure. The Cdk4 (R24C) mouse model develops highly penetrant pituitary tumors and endocrine pancreas adenomas, and, as such, this model is appropriate to gain insight into mechanisms underlying MEN. Using this model, here we provide evidence supporting an important role for telomerase in the pathogenesis of MEN. We observed increased aneuploidy in Cdk4 (R/R) fibroblasts along with significantly elevated telomerase activity and telomere length in Cdk4 (R/R) islets and embryonic fibroblasts. To better understand the role of telomerase, we generated Cdk4 (R24C) mice with inactivation of the mTERC locus, which codes for the essential RNA component of the enzyme telomerase (mTERC (-/-) Cdk4 (R/R) mice). Embryonic fibroblasts and islets derived from mTERC (-/-) Cdk4 (R/R) mice exhibit reduced telomere length and proliferative capacity. Further, mTERC (-/-) Cdk4 (R/R) fibroblasts display reduced transformation potential. Importantly, mTERC (-/-) Cdk4 (R/R) mice display significantly reduced spontaneous tumorigenesis. Strikingly, we observed dramatic suppression of pituitary tumors and endocrine pancreas adenomas in mTERC (-/-) Cdk4 (R/R) mice. Telomere dysfunction suppressed tumor initiation and increased latency of tumor development while not affecting the progression of established tumors. In summary, these results are suggestive of an important role for telomerase in tumor development in the Cdk4 (R24C) mouse model, specifically in the genesis of tumors in the pituitary and the endocrine pancreas.

No MeSH data available.


Related in: MedlinePlus