Cancer stem cells are underestimated by standard experimental methods in clear cell renal cell carcinoma.
Rare cancer stem cells (CSC) are proposed to be responsible for tumour propagation and re-initiation and are functionally defined by identifying tumour-initiating cells (TICs) using the xenotransplantation limiting dilution assay (LDA). While TICs in clear cell renal cell carcinoma (ccRCC) appeared rare in NOD/SCID/IL2Rγ(-/-) (NSG) mice, xenografts formed more efficiently from small tumour fragments, indicating the LDA underestimated ccRCC TIC frequency. Mechanistic interrogation of the LDA identified multiple steps that influence ccRCC TIC quantitation. For example, tissue disaggregation destroys most ccRCC cells, common assays significantly overestimate tumour cell viability, and microenvironmental supplementation with human extracellular factors or pharmacological inhibition of anoikis increase clonogenicity and tumourigenicity of ccRCC cell lines and primary tumour cells. Identification of these previously uncharacterized concerns that cumulatively lead to substantial underestimation of TICs in ccRCC provides a framework for development of more accurate TIC assays in the future, both for this disease and for other cancers.
School of Biomedical Sciences and Pharmacy, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.|Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Craig
C
Gedye
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Danylo
D
Sirskyj
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Nazleen C
NC
Lobo
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Jalna
J
Meens
Hospital for Sick Children, Program in Genetics and Genome Biology, Toronto, ON, M5G 0A4, Canada.
Elzbieta
E
Hyatt
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Michael
M
Robinette
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Neil
N
Fleshner
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Robert J
RJ
Hamilton
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Girish
G
Kulkarni
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Alexandre
A
Zlotta
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Andrew
A
Evans
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Antonio
A
Finelli
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.
Michael A S
MA
Jewett
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 1L7, Canada.|Dept. of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada.
Laurie E
LE
Ailles
D000818:Animals; D002292:Carcinoma, Renal Cell / Q000503:physiopathology*; D002452:Cell Count / Q000379:methods*; D004195:Disease Models, Animal; D064593:Heterografts; D051379:Mice; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000502:physiology*; D010336:Pathology / Q000379:methods*