Hsp90 and PKM2 Drive the Expression of Aromatase in Li-Fraumeni Syndrome Breast Adipose Stromal Cells.

Abstract

Li-Fraumeni syndrome (LFS) patients harbor germ line mutations in the TP53 gene and are at increased risk of hormone receptor-positive breast cancers. Recently, elevated levels of aromatase, the rate-limiting enzyme for estrogen biosynthesis, were found in the breast tissue of LFS patients. Although p53 down-regulates aromatase expression, the underlying mechanisms are incompletely understood. In the present study, we found that LFS stromal cells expressed higher levels of Hsp90 ATPase activity and aromatase compared with wild-type stromal cells. Inhibition of Hsp90 ATPase suppressed aromatase expression. Silencing Aha1 (activator of Hsp90 ATPase 1), a co-chaperone of Hsp90 required for its ATPase activity, led to both inhibition of Hsp90 ATPase activity and reduced aromatase expression. In comparison with wild-type stromal cells, increased levels of the Hsp90 client proteins, HIF-1α, and PKM2 were found in LFS stromal cells. A complex comprised of HIF-1α and PKM2 was recruited to the aromatase promoter II in LFS stromal cells. Silencing either HIF-1α or PKM2 suppressed aromatase expression in LFS stromal cells. CP-31398, a p53 rescue compound, suppressed levels of Aha1, Hsp90 ATPase activity, levels of PKM2 and HIF-1α, and aromatase expression in LFS stromal cells. Consistent with these in vitro findings, levels of Hsp90 ATPase activity, Aha1, HIF-1α, PKM2, and aromatase were increased in the mammary glands of p53 null versus wild-type mice. PKM2 and HIF-1α were shown to co-localize in the nucleus of stromal cells of LFS breast tissue. Taken together, our results show that the Aha1-Hsp90-PKM2/HIF-1α axis mediates the induction of aromatase in LFS.

• Authors: Kotha Subbaramaiah, Kristy A Brown, Heba Zahid, Gabriel Balmus, Robert S Weiss, Brittney-Shea Herbert, Andrew J Dannenberg
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 291 Issue 31 Pg. 16011-23 (07 29 2016) ISSN: 1083-351X [Electronic] United States
• PMID: 27467582 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural, Retracted Publication)
• Copyright: © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• AHSA1 protein, human
• Ahsa1 protein, mouse
• Carrier Proteins
• HSP90 Heat-Shock Proteins
• Membrane Proteins
• Molecular Chaperones
• Neoplasm Proteins
• Thyroid Hormones
• thyroid hormone-binding proteins
• Aromatase
• CYP19A1 protein, human

Topics

• Adipose Tissue (metabolism, pathology)
• Animals
• Aromatase (biosynthesis, genetics)
• Breast (metabolism, pathology)
• Carrier Proteins (genetics, metabolism)
• Cell Line
• Female
• Gene Expression Regulation, Enzymologic
• Gene Expression Regulation, Neoplastic
• HSP90 Heat-Shock Proteins (genetics, metabolism)
• Humans
• Li-Fraumeni Syndrome (genetics, metabolism, pathology)
• Mammary Glands, Animal (metabolism, pathology)
• Membrane Proteins (genetics, metabolism)
• Mice
• Mice, Knockout
• Molecular Chaperones (genetics, metabolism)
• Neoplasm Proteins (genetics, metabolism)
• Stromal Cells (metabolism, pathology)
• Thyroid Hormones (genetics, metabolism)