Abstract PR06: Identification of metabolic dependencies in tuberous sclerosis and lymphangioleiomyomatosis

Abstract

Abstract The mammalian target of rapamycin complex (mTORC1) is constitutively active in many human cancers and in Tuberous Sclerosis Complex (TSC). Lymphangioleiomyomatosis (LAM) is a rare neoplastic disease of women in which TSC2-deficient cells metastasize to the lungs, causing cystic lung destruction. LAM can lead to oxygen dependency and death in young women. Inhibition of mTORC1 has a cytostatic effect in LAM and TSC, decreasing the size of kidney and brain tumors and stabilizing lung function. Lifelong therapy appears to be required, since tumors regrow upon treatment cessation. Hyperactive mTORC1 leads to low autophagic flux, contributing to the metabolic dependencies of TSC-deficient cells. Previously we found that the survival of TSC2-deficient cells is autophagy dependent. A Phase I clinical trial is currently underway testing the combination of rapamycin and hydroxychloroquine (which inhibits autophagy) in LAM. To further define autophagy dependent cellular pathways in TSC2-deficient cells we utilized the L1000 high-throughput gene expression assay. TSC2-null patient-derived cells were treated with chloroquine (CQ, 5 uM) for 24 hrs or 72 hrs. Pathway enrichment analysis revealed that the cholesterol biosynthesis pathway is significantly induced upon CQ treatment. TSC2-deficient cells exhibit differential sensitivity to the combination of CQ and a HMG-CoA reductase inhibitor supporting the L1000 finding. In parallel, we performed a high throughput synthetic lethality screen of TSC2-deficient and TSC2-expressing cells in the presence or absence of CQ. Four libraries consisting of 4,500 compounds were screened. Six compounds exhibited synergy with CQ by suppressing ATP levels in TSC2-deficient cells but not TSC2-expressing cells. Follow-up analyses of these compounds are ongoing. In conclusion we utilized gene expression profiling and a high throughput drug screen to identify genetic and chemical perturbations that act synergistically with autophagy inhibition to target TSC2-deficient cells. Abundant data suggests that TSC2-deficient cells can be exploited through their autophagy-dependent metabolic vulnerabilities. Our long-term goal is to identify novel cytocidal therapeutic strategies for clinical translation in TSC and LAM. Citation Format: Harilaos Filippakis, Damir Khabibullin, Carmen Priolo, Elizabeth P. Henske. Identification of metabolic dependencies in tuberous sclerosis and lymphangioleiomyomatosis. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr PR06.