The isolation and characterization of renal cancer initiating cells from human Wilms' tumour xenografts unveils new therapeutic targets

Abstract

There are considerable differences in tumour biology between adult and paediatric cancers. The existence of cancer initiating cells/cancer stem cells (CIC/CSC) in paediatric solid tumours is currently unclear. Here, we show the successful propagation of primary human Wilms' tumour (WT), a common paediatric renal malignancy, in immunodeficient mice, demonstrating the presence of a population of highly proliferative CIC/CSCs capable of serial xenograft initiation. Cell sorting and limiting dilution transplantation analysis of xenograft cells identified WT CSCs that harbour a primitive undifferentiated – NCAM1 expressing – “blastema” phenotype, including a capacity to expand and differentiate into the mature renal-like cell types observed in the primary tumour. WT CSCs, which can be further enriched by aldehyde dehydrogenase activity, overexpressed renal stemness and genes linked to poor patient prognosis, showed preferential protein expression of phosphorylated PKB/Akt and strong reduction of the miR-200 family. Complete eradication of WT in multiple xenograft models was achieved with a human NCAM antibody drug conjugate. The existence of CIC/CSCs in WT provides new therapeutic targets.

Targeted therapy aimed at cancer stem cells: Wilms’ tumor as an example

“…In vitro data corroborated in vivo experiments disclosing "stemness" properties of NCAM1 + ALDH1 + WT cells; qRT-PCR of NCAM1 + ALDH1 + demonstrated significant elevation of transcripts of renal progenitor genes (i.e., NCAM1, SALL1, SIX2, OSR1), "stemness" genes (i.e., BMI1, EZH2, OCT4) and poor prognostic genes (i.e., TOP2A, N-MYC, CRAB2P) in comparison to NCAM1 + ALDH1 − cells. In addition, colony-forming assays showed a significantly higher number of clones and larger colonies in NCAM1 + ALDH1 + compared to NCAM1 + ALDH1 − cells, in line with their CSC phenotype [42]. Fig.…”

“…Studying the CSC model in WT employs the use of single tumorigenic WT cells upon xeno-transplantation. This presented two main inherent limitations: first, tumorigenicfavorable histology WT cell lines are not obtainable, and second, primary Wilms' tumor tissues, like other pediatric solid tumors, are less available compared to fresh surgical adult carcinomas [42]. Moreover, establishment of WT xenografts from single cells, derived from fresh primary WT, has been estimated at 30 % graft take [43] and in our experience approximately 10 %, while after culture and in vitro growth of primary WT cells, xenograft formation is unattainable.…”

“…Later, by working with the WT xenograft model, performing limiting xenotransplantation (LDTA), we were able to show that the initiation and propagation of human WT xenografts by unsorted WT-xenograft-derived cells required a minimum of 10,000 cells. Hence, the propagation of human WT in mice self-enriches for the CSC phenotype [6,42]. However, only prospective isolation of the NCAM1 + WT cell fraction from xenografts enabled tumor initiation and propagation from as few as 500 cells.…”

“…We have recently shown that targeting the human NCAM + cell fraction with an anti-NCAM antibody-drug conjugate (ADC) (HuN901-DMI) resulted in loss of the WT CSCs, both in vitro and in vivo [42]. In vitro, treatment of both primary and xenograft-derived WT cell cultures with the anti-NCAM ADC, resulted in depletion of their "stemness" properties (CFU capacity, proliferation).…”

The Ever–Expanding Kidney Repair Shop

“…13 In the case of in vivo manipulation, retention of iPSCs at the nephron progenitor state and lack of maturation have potential to carry increased risk for tumorigenicity, because these cells may serve as precursors for human Wilms tumors. 14 It seems that other applications aside from renal regenerative medicine would benefit instantly from our ability to assemble nephron tubular and glomerular structures from human IPSCs as documented by Nishinakamura and colleagues. 3 Human disease models of inherited and congenital kidney diseases, nephrotoxicity assays, and drug screens are examples of extended use.…”