TSA downregulates Wilms tumor gene 1 (Wt1) expression at multiple levels

Area of Science:

• Molecular Biology
• Cancer Biology
• Genetics

Background:

• The Wilms tumor gene (WT1) encodes a transcription factor crucial for kidney and gonad development.
• WT1 is implicated in various cancers, acting as a tumor suppressor in Wilms tumors but an oncogene in hematologic malignancies.
• WT1 overexpression is observed in acute lymphoblastic leukemia and myelodysplastic syndromes, where its reduction inhibits leukemic cell proliferation.

Purpose of the Study:

• To investigate the effect of histone deacetylase inhibitors (HDACi) on WT1 expression levels.
• To elucidate the mechanisms by which HDACi modulate WT1 expression.

Main Methods:

• Treatment of various cell lines with Trichostatin A (TSA), a known HDAC inhibitor.
• Analysis of WT1 mRNA and protein levels following TSA treatment.
• Investigation of transcriptional regulation and protein degradation pathways involved in WT1 modulation.

Main Results:

• TSA treatment led to rapid and significant downregulation of WT1 expression across different cell lines.
• The downregulation was primarily mediated by transcriptional repression, involving sequences in WT1 intron 3.
• TSA also enhanced WT1 protein degradation via the proteasome, partly through inducing the ubiquitin-conjugating enzyme UBCH8.

Conclusions:

• HDAC inhibitors like TSA effectively downregulate WT1 expression in cancer cells.
• These findings suggest that WT1 downregulation is a contributing factor to the anti-cancer effects of HDAC inhibitors.
• This provides a potential therapeutic strategy targeting WT1 in hematologic malignancies and other cancers where it is overexpressed.