Chromatin Remodeling by Rosuvastatin Normalizes TSC2-/meth Cell Phenotype through the Expression of Tuberin

Abstract

Tuberous sclerosis complex (TSC) is a multi-systemic syndrome caused by mutations in TSC1 or TSC2 gene. In TSC2-null cells, Rheb, a member of the Ras family of GTPases, is constitutively activated. Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase and block the synthesis of isoprenoid lipids with inhibition of Rheb farnesylation and RhoA geranylgeranylation. The effects of rosuvastatin on the function of human TSC22/2 and TSC2 -/meth a-actin smooth muscle (ASM) cells have been investigated. The TSC2 2/2 and TSC2 -/meth ASM cells, previously isolated in our laboratory from the renal angiomyolipoma of two TSC patients, do not express tuberin and bear loss of heterozigosity caused by a double hit on TSC2 and methylation of TSC2 promoter, respectively. Exposure to rosuvastatin affected TSC2 -/meth ASM cell growth and promoted tuberin expression by acting as a demethylating agent. This occurred without changes in interleukin release. Rosuvastatin also reduced RhoA activation in TSC2 -/meth ASM cells, and it required coadministration with the specific mTOR (mammalian target of rapamycin) inhibitor rapamycin to be effective in TSC2 2/2 ASM cells. Rapamycin enhanced rosuvastatin effect in inhibiting cell proliferation in TSC22/2 and TSC2 -/meth ASM cells. Rosuvastatin alone did not alter phosphorylation of S6 and extracellular signal-regulated kinase (ERK), and at the higher concentration, rosuvastatin and rapamycin slightly decreased ERK phosphorylation. These results suggest that rosuvastatin may potentially represent a treatment adjunct to the therapy with mTOR inhibitors now in clinical development for TSC. In particular, rosuvastatin appears useful when the disease is originated by epigenetic defects.

TSC2 epigenetic defect in primary LAM cells. Evidence of an anchorage‐independent survival

“…In the light of this considerations, our findings in TSC2 −/meth ASM cells and LAM/TSC cells indicate that different epigenetic signatures related to closed chromatin conformation can affect TSC2 and may be crucial in the development of TSC lesions because they lead to the absence of tuberin expression as it is caused by the deletion of the wild‐type allele in TSC2 −/− ASM cells. A better comprehension of the aberrant epigenetic events occurring in LAM/TSC cells may be useful in the development of more effective therapeutic interventions also based on chromatin‐remodelling agents aimed at the epigenetic silencing relief of the TSC2 .…”

A phase II clinical trial of the Safety Of Simvastatin (SOS) in patients with pulmonary lymphangioleiomyomatosis and with tuberous sclerosis complex

“…In contrast, the combination of sirolimus and simvastatin has also been shown to inhibit xenograft tumor growth, including preventing recurrence of tumors after treatment withdrawal, suggesting a synergistic effect [13]. Data on the use of other statins such as rosuvastatin are limited but some pre-clinical studies suggest efficacy in combination with sirolimus [22].…”

LAM/TSC Cell Migration to Uterus in an Experimental Model of Lymphangioleiomyomatosis. Regulation by Anti-Epidermal Growth Factor Receptor Antibody and Rapamycin

“…LAM is a neoplasm arising from constitutive activation of the mTOR signaling pathway dysregulated by a functional loss of TSC genes [2,3]. Our group has contributed to elucidate some of the properties of human TSC and LAM cells including the role of epigenetic modification in causing the loss of heterozigosity, their metastatic properties described in a LAM model and the specific pharmacological actions of agents such rapamycin, anti-EGFR antibody and rosuvastatin [15][16][17][18]25,26].…”