Genome-wide RNAi analysis reveals that simultaneous inhibition of specific mevalonate pathway genes potentiates tumor cell death.
The mevalonate (MVA) pathway is often dysregulated or overexpressed in many cancers suggesting tumor dependency on this classic metabolic pathway. Statins, which target the rate-limiting enzyme of this pathway, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), are promising agents currently being evaluated in clinical trials for anti-cancer efficacy. To uncover novel targets that potentiate statin-induced apoptosis when knocked down, we carried out a pooled genome-wide short hairpin RNA (shRNA) screen. Genes of the MVA pathway were amongst the top-scoring targets, including sterol regulatory element binding transcription factor 2 (SREBP2), 3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) and geranylgeranyl diphosphate synthase 1 (GGPS1). Each gene was independently validated and shown to significantly sensitize A549 cells to statin-induced apoptosis when knocked down. SREBP2 knockdown in lung and breast cancer cells completely abrogated the fluvastatin-induced upregulation of sterol-responsive genes HMGCR and HMGCS1. Knockdown of SREBP2 alone did not affect three-dimensional growth of lung and breast cancer cells, yet in combination with fluvastatin cell growth was disrupted. Taken together, these results show that directly targeting multiple levels of the MVA pathway, including blocking the sterol-feedback loop initiated by statin treatment, is an effective and targetable anti-tumor strategy.
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.|Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Essen, Germany.
Aleksandra A
AA
Pandyra
Princess Margaret Cancer Centre, Toronto, ON, Canada.
Peter J
PJ
Mullen
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
Carolyn A
CA
Goard
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.|Now located at AstraZeneca R&D, Mölndal, Sweden.
Elke
E
Ericson
Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Essen, Germany.
Piyush
P
Sharma
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
Manpreet
M
Kalkat
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
Rosemary
R
Yu
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
Janice T
JT
Pong
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.
Kevin R
KR
Brown
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.
Traver
T
Hart
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.
Marinella
M
Gebbia
Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Essen, Germany.
Karl S
KS
Lang
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.|Now located at Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.
Guri
G
Giaever
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.|Now located at Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada.
Corey
C
Nislow
Donnelly Centre and Banting & Best Department of Medical Research, University of Toronto, Toronto, ON, Canada.
Jason
J
Moffat
Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
Linda Z
LZ
Penn
D000970:Antineoplastic Agents / Q000737:chemistry; D017209:Apoptosis; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004122:Dimethylallyltranstransferase / Q000235:genetics; D051231:Farnesyltranstransferase / Q000235:genetics; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D005260:Female; D000077340:Fluvastatin; D015972:Gene Expression Regulation, Neoplastic; D051228:Geranyltranstransferase / Q000235:genetics; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000235:genetics; D007211:Indoles / Q000737:chemistry; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism; D008798:Mevalonic Acid / Q000378:metabolism*; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics
D000970:Antineoplastic Agents; D005229:Fatty Acids, Monounsaturated; D007211:Indoles; D034741:RNA, Small Interfering; C497390:SREBF2 protein, human; D051782:Sterol Regulatory Element Binding Protein 2; D000077340:Fluvastatin; C553220:HMGCR protein, human; D006903:Hydroxymethylglutaryl CoA Reductases; D006904:Hydroxymethylglutaryl-CoA Synthase; D004122:Dimethylallyltranstransferase; D051228:Geranyltranstransferase; D051231:Farnesyltranstransferase; C495427:GGPS1 protein, human; D008798:Mevalonic Acid
SREBP2; feedback inhibition; mevalonate pathway; statins; tumor metabolism