Functions of extracellular vesicles including exosomes in the pathogenesis of tuberous sclerosis complex (TSC) have not yet been studied. We report that the extracellular vesicles such as exosomes derived from tuberous sclerosis 1 (Tsc1)-null cells transform phenotypes of neighboring wild-type cells in vivo in such manner that they become functionally similar to Tsc1-null cells. The loss of Tsc1 in the mouse neural tube increases the number of the wild-type neuronal progenitors, which is followed by the precocious and transient acceleration of neuronal differentiation of these cells. The mechanisms regulating these changes involve the exosomal delivery of exosomal shuttle Notch1 and Rheb esRNA and component of γ-secretase complex presenilin 1 from Tsc1-null cells to wild-type cells leading to the activation of Notch and Rheb signaling in the recipient cells. The exosome-mediated mechanisms may also operate in the cells of angiomyolipoma (AML), which develops as a result of mutations in TSC1/TSC2 genes in TSC patients, because we observed the reactivation of mammalian target of rapamycin and Notch pathways, driven by the delivery of Rheb and Notch1 esRNA, in AML cells depleted of Rheb that were treated with the exosomes purified from AML cells with the constitutively high Rheb levels.

Differentiation abnormalities are a hallmark of tuberous sclerosis complex (TSC) manifestations; however, the genesis of these abnormalities remains unclear. Here we report on mechanisms controlling the multi-lineage, early neuronal progenitor and neural stem-like cell characteristics of lymphangioleiomyomatosis (LAM) and angiomyolipoma cells. These mechanisms include the activation of a previously unreported Rheb-Notch-Rheb regulatory loop, in which the cyclic binding of Notch1 to the Notch-responsive elements (NREs) on the Rheb promoter is a key event. This binding induces the transactivation of Rheb. The identified NRE2 and NRE3 on the Rheb promoter are important to Notch-dependent promoter activity. Notch cooperates with Rheb to block cell differentiation via similar mechanisms in mouse models of TSC. Cell-specific loss of Tsc1 within nestin-expressing cells in adult mice leads to the formation of kidney cysts, renal intraepithelial neoplasia, and invasive papillary renal carcinoma.

Androgen Receptor (AR) signaling is a critical driver of hormone-dependent prostate cancer and has also been proposed to have biological activity in female hormone-dependent cancers, including type I endometrial carcinoma (EMC). In this study, we evaluated the preclinical efficacy of a third-generation AR antagonist, enzalutamide, in a genetic mouse model of EMC, Sprr2f-Cre;Pten fl/fl . In this model, ablation of Pten in the uterine epithelium leads to localized and distant malignant disease as observed in human EMC. We hypothesized that administering enzalutamide through the diet would temporarily decrease the incidence of invasive and metastatic carcinoma, while prolonged administration would result in development of resistance and loss of efficacy. Short-term treatment with enzalutamide reduced overall tumor burden through increased apoptosis but failed to prevent progression of invasive and metastatic disease. These results suggest that AR signaling may have biphasic, oncogenic and tumor suppressive roles in EMC that are dependent on disease stage. Enzalutamide treatment increased Progesterone Receptor (PR) expression within both stromal and tumor cell compartments. Prolonged administration of enzalutamide decreased apoptosis, increased tumor burden and resulted in the clonal expansion of tumor cells expressing high levels of p53 protein, suggestive of acquired Trp53 mutations. In conclusion, we show that enzalutamide induces apoptosis in EMC but has limited efficacy overall as a single agent. Induction of PR, a negative regulator of endometrial proliferation, suggests that adding progestin therapy to enzalutamide administration may further decrease tumor burden and result in a prolonged response.