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A7111 - Tuberous Sclerosis and Lymphangioleiomyomatosis Are Neurocristopathies
Author Block: U. J. Unachukwu1, T. Shiomi2, J. Sonett3, D. Woode1, V. Anguiano1, M. P. Goldklang4, C. Damoci5, K. Chada6, J. M. D'Armiento1; 1Anesthesiology, Columbia University Medical Center, New York, NY, United States, 2Pathology, International University for Healthe and Welfare, Narita-shi, Japan, 3Anesthesiology, Columbia Presbyterian, New York, NY, United States, 4Anesthesiology, Columbia University Medical Center, Demarest, NJ, United States, 5Small Animal Imaging Shared Resource, Columbia University Medical Center, New York, NY, United States, 6Biochemistry, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, United States.
Introduction/Rationale: Tuberous Sclerosis (TS) and its pulmonary manifestation, lymphangioleiomyomatosis (LAM), are rare disorders characterized by widespread harmatomas and benign neoplasms in multiple organs. These disorders are linked to loss-of-function mutations in Tsc1 or more often Tsc2 tumor suppressor genes, triggering dysregulation of the mechanistic target of rapamycin (mTOR) pathway. Given the variably limited success obtained using mTOR pathway inhibitors for TS and LAM therapy, understanding the source of heterogeneous cells comprising TS and LAM tumors and their method of propagation throughout the body will infom more effective treatment strategies. As LAM presents in multiple organs and expresses markers of early progenitor cells including High Mobility Group A2 (HMGA2), we postulated that LAM and TS are neurocristopathies.
Methods: A Tsc2+/-Mpz(Cre)fl/fl TS reporter mouse model expressing cre recombinase specifically in neural crest and schwann cells under the control of myelin protein zero (MPZ) promoter was generated and aged for 1.5 years along with age-matched control (Tsc2+/+Mpz(Cre)fl/fl, Tsc2+/+Mpz(Cre)+/+) mice to allow for tumor development. IVIS spectral imaging, and small animal ultrasound and magnetic resonance imaging (MRI) were used to detect the occurrence of tumors. Tumors were excised and immunohistochemical sections prepared and stained for the expression of neural crest markers. Neural crest marker expression in Tsc2+/- mouse tumors was confirmed using RT-PCR and Western blots.
Results: Tumors were detected only in Tsc2+/-Mpz(Cre)fl/fl mice compared to age-matched control mouse groups. Additionally, only immunohistochemical slices obtained from renal and hepatic tumors of this TS reporter mouse model exhibited td-Tomato expressing tumor cell masses specifically annotating neural crest ontogeny in tumors of this mouse group. Upon staining for neural crest markers, tumorigenesis in the TS reporter mouse model was observed to be propagated by cranial neural crest cell (CNCC) subpopulations selectively expressing delaminating late-migratory neural crest marker β-1, 3-glucoronyltransferase 1 (CD57) and melanoma-initiating nerve growth factor receptor (NGFR/p75 NTR) but not transcription factor activating protein (Tfap2α). This differential marker expression was observed only in tissue slices obtained from renal tumors and not hepatic tumors indicating tissue specificity in neural crest-derived tumor occurrence initiated by Tsc2 haploinsufficiency. Results were confirmed using RT-PCR and Western blots.
Conclusions: We propose that pathogenic cells in TS and LAM delaminate and migrate from the neural crest during neurocristogenesis forming cranial neural crest sub-populations that give rise to craniofacial mesenchyme and peripheral nervous tissues. Domiciled in these organs, these cells co-opt tumorigenesis upon secondary somatic Tsc2 mutations and/or environmental stimuli.