Aberrant differentiation of Tsc2-deficient teratomas associated with activation of the mTORC1-TFE3 pathway.
The model animal of renal cell carcinoma (RCC), the Eker rat, has a germline mutation in the tuberous sclerosis 2 (Tsc2) gene. Heterozygous mutants develop RCCs by second hit in the wild-type Tsc2 allele, whereas homozygous mutants are embryonic lethal. In the present study, a new cell differentiation model was developed to study the mechanism of Tsc2 mutation-associated pathogenesis by generating Tsc2-deficient embryonic stem cells (ESCs) from Eker rats. Tsc2+/+, Tsc2+/- and Tsc2-/- ESCs were all capable of generating three germ layers: mesoderm, ectoderm, and endoderm. Interestingly, epithelial tumor-like abnormal ductal structures were reproducibly observed in Tsc2-/- teratomas from different ESC lines. Immunohistochemical analysis revealed that mammalian target of rapamycin complex 1 (mTORC1) signaling was activated in abnormal ducts of Tsc2-/- teratomas, on the basis of positive staining for p-S6 and p-4EBP1. In these abnormal ducts, expression levels of epithelial markers (i.e., megalin and cubilin) and the cytoplasmic localization of E-cadherin and β-catenin were similar to those in Eker rat RCCs. Moreover, a transcription factor regulated by mTORC1, named TFE3, was located in the nuclei of abnormal ducts and Eker rat RCCs. As a negative regulator of ESC differentiation, TFE3 may result in tissue-specific differentiation defects related to tumorigenesis in Eker rats and Tsc2-/- teratomas. The present study suggests that ESCs derived from Eker rats constitute a novel experimental tool with which to analyze differentiation defects and cell-type specific pathogenesis associated with Tsc2 deficiency.
Department of Urology, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Haruna
H
Kawano
Department of Molecular Pathogenesis, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Yoshitaka
Y
Ito
Laboratory of Genome Research, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Fumio
F
Kanai
Laboratory of Genome Research, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Eri
E
Nakamura
Laboratory of Genome Research, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Norihiro
N
Tada
Department of Clinical Radiology, Faculty of Health Sciences, Hiroshima International University, Hiroshima 724-0695, Japan.
Setsuo
S
Takai
Department of Urology, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Shigeo
S
Horie
Department of Molecular Pathogenesis, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Toshiyuki
T
Kobayashi
Department of Molecular Pathogenesis, Juntendo University Graduate School of Medicine, Tokyo 113-8431, Japan.
Okio
O
Hino
D000818:Animals; D015820:Cadherins / Q000378:metabolism; D063646:Carcinogenesis / Q000235:genetics; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism; D053595:Embryonic Stem Cells; D055786:Gene Knockout Techniques; D007680:Kidney Neoplasms / Q000235:genetics / Q000473:pathology; D000076222:Mechanistic Target of Rapamycin Complex 1; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D046912:Multiprotein Complexes / Q000378:metabolism*; D009368:Neoplasm Transplantation; D021381:Protein Transport; D051381:Rats; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D013724:Teratoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
D015820:Cadherins; C495268:Ctnnb1 protein, rat; D046912:Multiprotein Complexes; C000617764:TFE3 protein, rat; D014157:Transcription Factors; C000624654:Tsc2 protein, mouse; C000624655:Tsc2 protein, rat; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D051176:beta Catenin; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases