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Abstract: PO1857

Recapitulating Kidney Angiomyolipoma with Renal Organoids Generated from Tuberous Sclerosis Complex Patient-Derived Induced Pluripotent Stem Cells

Session Information

Category: Onco-Nephrology

  • 1500 Onco-Nephrology

Author

  • Lemos, Dario R., Brigham and Women's Hospital, Boston, Massachusetts, United States

Group or Team Name

  • Lemos Lab
Background

Angiomyolipomas (AMLs) constitute 80% of the renal lesions found in patients with Tuberous Sclerosis Complex. AML can cause kidney failure and lead to premature death due to the formation of vascular aneurysms that are prone to spontaneous bleeding. Key aspects of the pathobiology of AMLs, and most remarkably the cell(s) type(s) and developmental mechanisms that give raise to the lesions, remain unknown. Previous efforts to recapitulate AML experimentally using transgenic mice have failed to produce reliable models of AMLs, precluding our ability to study tumor mechanisms and develop novel therapies.

Methods

We directed the nephric differentiation of a series of TSC patient-derived iPSC lines that included a line carrying a heterozygous microdeletion in the TSC2 locus (TSC2+/-), a TALEN-engineered isogenic cell line carrying microdeletions in both TSC2 alleles (TSC2−/−) and a cell line in which the original mutation present in the patient was corrected using CRISPR-Cas9 (TSC2+/+).

Results

We derived renal organoids from isogenic TSC2-/-, TSC2+/- and TSC2+/+ iPSCs. Flow cytometry analysis of kidney organoids derived from TSC2-/- hiPSCs but not from isogenic TSC2+/- or TSC2+/+ hiPSCs were enriched in ACTA2+ cells, a percentage of which (~24%) co-expressed melanocyte markers including premelanosome protein (PMEL), melanin A (MLANA) and cathepsin K (CTSK) indicative of a myomelanocytic phenotype that is a hallmark of kidney AMLs. Morphologically, ACTA2+ cells found in TSC2-/- organoids had a plump myoid morphology that matched the well-characterized morphology of kidney AML cells. Whole transcriptome RNA sequencing (RNA-seq) of TSC2+/-, TSC2+/+ and TSC2-/- organoids identified MLANA, PMEL, GPNMB, MITF, CTSK and ACTA2 as genes that were exclusively upregulated in TSC2-/- organoids, confirming the myomelanocytic phenotype of TSC2-/- AML organoids. Hallmark gene sets enriched in expression in TSC2-/- renal organoids in each comparison included IL6-JAK-STAT3 signaling, adipogenesis, angiogenesis, fatty acid metabolism, KRAS signaling and estrogen response, as major pathways shared with kidney AMLs.

Conclusion

Collectively, our findings support the notion that AMLs originate from cells of the renal lineage and suggest a central role for TSC2 loss-of-heterozygosity (LOH) genetic mechanisms in the etiology of AML.

Funding

  • NIDDK Support