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Modeling Wilms tumor in human kidney organoids

Waehle, Verena. Modeling Wilms tumor in human kidney organoids. 2021, Doctoral Thesis, University of Basel, Faculty of Science.

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Abstract

Wilms tumor is a pediatric kidney cancer that affects one in 10,000 children and is thought to arise from impaired nephrogenesis, leading to an expansion of immature cells at the expense of functional kidney tissue. In the past years, numerous genetic alterations associated with Wilms tumor have been identified. These include loss of the tumor suppressor gene WT1, biallelic expression of IGF2, as well as mutations in CTNNB1, miRNA processing genes like LIN28 and DROSHA, and the kidney progenitor transcription factors SIX1 and SIX2. Several model systems have been developed to study Wilms tumor, including cell lines, transgenic mice, patient-derived xenografts, and three-dimensional cultures from patient tissues. However, these systems often fail to recapitulate tumor properties accurately, and most of them are generated from patient tumors and are therefore unsuitable to study tumor initiation. Pluripotent stem cell-derived kidney organoids recapitulate human kidney development in vitro and largely reflect the cellular composition and architecture of the kidney. In combination with gene editing technologies, they offer a promising platform to study Wilms tumorigenesis.
In this thesis, I introduced previously described Wilms tumor mutations into human kidney organoids in order to develop an in vitro model for Wilms tumor.
We showed that overexpression of the miRNA processing genes LIN28A and LIN28B impairs organoid formation, without retaining kidney progenitor cells or enhancing proliferation. We observed similar phenotypes upon induction of the nephron progenitor transcription factor SIX2 and its Wilms tumor-specific variant SIX2 Q177R. This indicates that overexpression of both, SIX2 / SIX2 Q177R and LIN28A / B are insufficient to induce Wilms tumorigenesis in kidney organoids.
Moreover, we used ectopic chemical activation of canonical WNT signaling to mimic a stabilizing mutation of CTNNB1 and found defects in epithelialization and nephron patterning. While this recapitulates known functions of WNT signaling in nephrogenesis, further experiments are needed to confirm if this reflects a Wilms tumor phenotype.
Finally, loss of the tumor suppressor gene WT1 results in a Wilms tumor phenotype accompanied by a developmental arrest of kidney progenitors, enhanced proliferation and impaired differentiation into nephron cell types. As shown by transcriptional profiling, WT1 KO organoids resemble human Wilms tumors and share a subtype-specific upregulation of muscle-related transcription. Using serial passaging and in vitro transplantation experiments, we showed that cells derived from WT1 KO organoids can be maintained in a SIX2-expressing state in the presence of “fetal” and differentiated wildtype cells.
In conclusion, we developed the first human kidney organoid model for Wilms tumor. We provide evidence for the applicability of kidney organoids to study kidney development and developmental diseases, and for their use as a surrogate system for tumor cell propagation. This work sets the stage for generating additional organoid models for pediatric kidney cancers, and proposes to extend the use of kidney organoids as transplantation platforms in kidney cancer research.
Advisors:Gasser, Susan and Betschinger, Jörg and Lienkamp, Soeren
Faculties and Departments:03 Faculty of Medicine > Bereich Operative Fächer (Klinik) > Innere Organe > Urologie Kliniken BL (Gasser)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Operative Fächer (Klinik) > Innere Organe > Urologie Kliniken BL (Gasser)
09 Associated Institutions > Friedrich Miescher Institut FMI > Quantitative Biology > Nuclear organization in development and genome stability (Gasser)
UniBasel Contributors:Gasser, Susan
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:14052
Thesis status:Complete
Number of Pages:XI, 136
Language:English
Identification Number:
  • urn: urn:nbn:ch:bel-bau-diss140529
edoc DOI:
Last Modified:11 May 2021 04:30
Deposited On:10 May 2021 11:41

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