Tissue-type transglutaminase expression in the Dunning tumor

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Transglutaminases (TGs) exhibit diverse functions and tissue distributions.
• Tissue-type TG (tTG) is involved in membrane stabilization and inhibited by guanosine triphosphate (GTP).
• A GTP-insensitive secretory TG is androgen-dependently synthesized in the rat dorsal prostate, a potential origin for Dunning tumors.

Purpose of the Study:

• To investigate transglutaminase expression and activity in Dunning tumor lines.
• To biochemically and immunocytochemically characterize the transglutaminase in Dunning tumors.
• To determine if secretory transglutaminase is present in Dunning tumors and assess their prostatic origin.

Main Methods:

• Biochemical assays to measure transglutaminase activity.
• Immunohistochemistry to localize enzyme expression.
• Western blot analysis to detect specific transglutaminase forms.
• Study of various Dunning tumor sublines, focusing on the H subline.

Main Results:

• High transglutaminase activity was predominantly observed in the less differentiated HI-F tumor line.
• Immunohistochemistry and Western blot revealed no secretory transglutaminase in any Dunning tumor lines.
• The observed transglutaminase activity in Dunning tumors originates from the non-organ-specific tissue-type enzyme.

Conclusions:

• Dunning tumor transglutaminase activity is attributed to the tissue-type enzyme, not a secretory form.
• The absence of secretory transglutaminase in Dunning tumors does not support their proposed origin from the rat dorsal prostate.
• These findings refine the understanding of Dunning tumor biology and their relevance as prostate cancer models.