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Human TSC-associated renal angiomyolipoma cells are hypersensitive to ER stress
- Source :
- American journal of physiology. Renal physiology. 303(6)
- Publication Year :
- 2012
-
Abstract
- Tuberous sclerosis complex (TSC), an inherited tumor predisposition syndrome associated with mutations in TSC1 or TSC2, affects ∼1 in 6,000 individuals. Eighty percent of TSC patients develop renal angiomyolipomas, and renal involvement is a major contributor to patient morbidity and mortality. Recent work has shown that mammalian target of rapamycin complex 1 (mTORC1) inhibition caused angiomyolipoma shrinkage but that this treatment may cause cytostatic not a cytotoxic effect. Endoplasmic reticulum (ER) stress can develop in TSC-associated cells due to mTORC1-driven protein translation. We hypothesized that renal angiomyolipoma cells experience ER stress that can be leveraged to result in targeted cytotoxicity. We used immortalized human angiomyolipoma cells stably transfected with empty vector or TSC2 (encoding tuberin). Using cell number quantification and cell death assays, we found that mTORC1 inhibition with RAD001 suppressed angiomyolipoma cell proliferation in a cytostatic manner. Angiomyolipoma cells exhibited enhanced sensitivity to proteasome inhibitor-induced ER stress compared with TSC2-rescued cells. After proteasome inhibition with MG-132, Western blot analyses showed greater induction of C/EBP-homologous protein (CHOP) and more poly (ADP-ribose) polymerase (PARP) and caspase-3 cleavage, supporting ER stress-induced apoptosis. Live cell numbers also were decreased and cell death increased by MG-132 in angiomyolipoma cells compared with TSC2 rescued. Intriguingly, while pretreatment of angiomyolipoma cells with RAD001 attenuated CHOP and BiP induction, apoptotic markers cleaved PARP and caspase-3 and eukaryotic translation initiation factor 2α phosphorylation were increased, along with evidence of increased autophagy. These results suggest that human angiomyolipoma cells are uniquely susceptible to agents that exacerbate ER stress and that additional synergy may be achievable with targeted combination therapy.
- Subjects :
- Pathology
medicine.medical_specialty
Angiomyolipoma
Physiology
Leupeptins
Eukaryotic Initiation Factor-2
Antineoplastic Agents
Apoptosis
Biology
Mechanistic Target of Rapamycin Complex 1
Transfection
Tuberous sclerosis
Tuberous Sclerosis
Cell Line, Tumor
Tuberous Sclerosis Complex 2 Protein
medicine
Humans
Everolimus
Phosphorylation
PI3K/AKT/mTOR pathway
Sirolimus
Caspase 3
TOR Serine-Threonine Kinases
Tumor Suppressor Proteins
Proteins
Articles
medicine.disease
Endoplasmic Reticulum Stress
Kidney Neoplasms
medicine.anatomical_structure
Multiprotein Complexes
Unfolded protein response
TSC1
TSC2
Poly(ADP-ribose) Polymerases
Proteasome Inhibitors
Immunosuppressive Agents
Transcription Factor CHOP
medicine.drug
Subjects
Details
- ISSN :
- 15221466
- Volume :
- 303
- Issue :
- 6
- Database :
- OpenAIRE
- Journal :
- American journal of physiology. Renal physiology
- Accession number :
- edsair.doi.dedup.....fa0c10c86c2b6bd402537099010fd944