Abstract LB-129: Evidence from expression profiling, proteomics, metabolomics and FDG-PET of an estrogen-dependent metabolic switch in tuberin-null cells.
Authors: Sun Yang , Li Chenggang , Marks Kevin , Zhang Erik , Morrison Tasha , Park Mi-Ae , Wang Shuyan , Dillon Simon , Bhasin Manoj , Libermann Towia , Driggers Edward , Gerbaudo Victor , Henske Elizabeth Petri , Yu Jane 
Published: August 2014

Lymphangioleiomyomatosis (LAM) is a female predominant lung disease characterized by widely-distributed nodules of ‘LAM’ cells and progressive cyst formation that leads to respiratory failure. LAM cells typically have mutation or inactivation of TSC2, leading to mTORC1 activation. We previously demonstrated that estrogen promotes the survival of tuberin-deficient ELT3 cells both in vitro and in vivo, and that estrogen treatment of mice bearing ELT3 cells xenograft tumors promotes lung metastasis. This estrogen-induced cell survival and metastasis was inhibited in vivo by the MEK inhibitor CI-1040.

To elucidate pro-survival events mediated by estrogen in tuberin-null cells, we compared Tsc2-null ELT3 cell xenograft tumors from estrogen or placebo-treated mice using expression profiling and proteomic analysis . Expression profiling of ELT3 cell xenograft tumors revealed that estrogen upregulates the expression of genes in lipid and amino acid metabolism pathways. Among these genes, the estrogen-induced expression of amino adipatetransferase (AADAT), which is involved in lysine degradation, has been confirmed by immunoblotting of tumor lysates. Using iTRAQ proteomics from ELT3 xenograft tumors, we identified 40 proteins that are significantly regulated by estrogen, including proteins involved in carbohydrate metabolism (creatine kinase), amino acid degradation (aspartate aminotransferase) and lipid metabolism (isocitrate dehydrogenase). Metabolic profiling by LC/MS/MS of TSC2-null angiomyolipoma-derived cells from a LAM patient (621-101 cells) showed a temporal effect of rapamycin (10 nM) on the accumulation of pentose phosphate pathway intermediates and glycolytic metabolites. Cellular amino acid levels were reduced after rapamycin treatment.

Consistent with a metabolic switch occurring in LAM, we found, using IHC staining, that the tumor-associated PKM2 is abundantly expressed in ELT3 cell xenograft tumors, lung metastatic lesions from estrogen-treated mice bearing ELT3 cell xenograft tumors, and in human LAM cell nodules. Finally, using FDG-PET, we found that xenograft ELT3 cell tumors in estrogen-treated mice exhibited higher levels of uptake compared with placebo-treated mice.

In conclusion, gene expression profiling indicated that estrogen enhances the expression of genes which products regulate glucose and amino acid metabolism. Proteomic analysis showed estrogen-regulated candidates involved in glycolysis, amino acid, and lipid metabolisms. Metabolomic screening revealed that cells lacking tuberin have a metabolic response to rapamycin treatment. FDG-PET imaging showed enhanced uptake in estrogen-treated xenograft tumors. Collectively, these data indicate that cellular metabolic alterations may contribute to the pathogenesis of LAM. Targeting metabolic regulators might have therapeutic benefit for LAM.

Citation Format: Yang Sun, Chenggang Li, Kevin Marks, Erik Zhang, Tasha Morrison, Mi-Ae Park, Shuyan Wang, Simon Dillon, Manoj Bhasin, Towia Libermann, Edward Driggers, Victor Gerbaudo, Elizabeth Petri Henske, Jane Yu. Evidence from expression profiling, proteomics, metabolomics and FDG-PET of an estrogen-dependent metabolic switch in tuberin-null cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-129. doi:10.1158/1538-7445.AM2013-LB-129