In vitro validation of inhibitors targeting TCF-4 and beta catenin interaction in WNT-activated tumors

Document Type

Article

Publication Date

Summer 2021

JAX Location

In: Student Reports, Summer 2021, The Jackson Laboratory

Abstract

Craniopharyngioma (CP) is a rare, histologically benign brain tumor which affects both children and adults. Histologically distinct from its adult counterpart, a majority of pediatric CP patients present with abnormal nuclear accumulation of the protein β-catenin caused by a mutation in the third exon of the encoded gene, CTNNB1, which has been hypothesized as the driver of tumor growth. Current treatment strategies involve tumor resection and radiation, but this approach often risks imparting significant reductions in patient quality of life due to the suprasellar location of the tumor. Small molecule targeting therapy targeting the transcriptional regulation of oncogenic proteins could serve as a novel approach. In particular, we look to identify a therapeutic compound that will specifically target the WNT pathway, which is known to activate oncogene transcription. Blocking the binding interaction between transcription factors β-catenin and TCF-4 via a small molecule could prevent cellular proliferation and ultimately lead to tumor regression. Initial screening of 51 compounds created through a collaboration revealed three compounds with high cytotoxic effect. To test whether such activity was pathway specific, 72-hour cytotoxicity assays were performed on a negative control cell line, HEK293, using CellTiter-Glo. Additionally, 24-hour cytotoxicity assays were run concurrently with 24-hour One-Glo Luciferase assays to detect whether reduction in pathway signaling once cells were treated with compound was due to non-specific cell kill. Similar cytotoxic trends across all three cell lines for compound #139 and #852 confirmed that such effects are not pathway specific because the drops in Luciferase signal coincided with reduction in cell viability, with the exception of #139 on HuH6 cells at low dosage. Immunocytochemistry assays confirmed nuclear β-catenin localization in our surrogate cell lines, HepG2 and HuH6, and membrane localization in the negative control, HEK293. Compound #862 yielded highly cytotoxic effects, but its mode of action is pathway independent. Future research will include determining chronic compound effect via clonogenic assay and establishing PDX models for CP for additional compound experimentation.

Please contact the Joan Staats Library for information regarding this document.

COinS