Endocrine-related cancers and the role of AMPK

Brown, Kristy A.; Samarajeewa, Nirukshi Udayanga Gunasinghe; Simpson, Evan R.

doi:10.1016/j.mce.2012.06.016

Cited by 53 publications

(38 citation statements)

References 129 publications

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“…HIF-1␣, a client protein of Hsp90 (26), has been shown to stimulate aromatase in human breast adipose stromal cells (10). Here, we show that increased Hsp90 ATPase activity found in LFS-derived stromal cells leads to enhanced HIF-1␣ levels, the increased binding of HIF-1␣ to the proximal promoter of CYP19A1 (PII promoter), and a consequent increase in aromatase expression.…”

Section: Discussionmentioning

confidence: 63%

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

Subbaramaiah

Brown

Zahid

et al. 2016

Journal of Biological Chemistry

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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 cochaperone 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-1␣, and PKM2 were found in LFS stromal cells. A complex comprised of HIF-1␣ and PKM2 was recruited to the aromatase promoter II in LFS stromal cells. Silencing either HIF-1␣ 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-1␣, and aromatase expression in LFS stromal cells. Consistent with these in vitro findings, levels of Hsp90 ATPase activity, Aha1, HIF-1␣, PKM2, and aromatase were increased in the mammary glands of p53 null versus wild-type mice. PKM2 and HIF-1␣ 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-1␣ axis mediates the induction of aromatase in LFS.Estrogen is an important mediator in the development and progression of breast cancer. Cytochrome P450 aromatase, a product of the CYP19A1 gene, catalyzes the synthesis of estrogens from androgens (1). In postmenopausal women, the adipose tissue becomes the main site of estrogen biosynthesis, and particularly, the breast adipose tissue is considered an important source of estrogens that drive the growth of hormone-dependent breast cancers. Consequently, it is important to elucidate the mechanisms that regulate the transcription of the CYP19A1 gene. The expression of aromatase is tightly regulated, with transcription being under the control of several distinct tissue-selective promoters (2-4). In normal breast adipose tissue, aromatase is expressed at low levels under the control of promoter I.4, whereas in obesity and cancer, the coordinated activation of the proximal promoters I.3 and promoter II (PII) 3 causes a significant increase in aromatase expression (3-5). The proximal promoters I.3 and PII are located close to each other, activated by stimulation of the cAMP 3 PKA 3 cAMP response element-binding protein (CREB) pathway (6, 7), and aided by many other regulators including CREB-regulated transcription co-activator 2 (CRTC2), p300, and hypoxia-inducible factor-1␣ (HIF-1␣) (8 -11).Several cytokines and tumor promoters, including prostaglandin E 2 , tumor necrosis ...

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Section: Discussionmentioning

confidence: 63%

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

Subbaramaiah

Brown

Zahid

et al. 2016

Journal of Biological Chemistry

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“…Hence, pharmacologic activation of AMPK would be advantageous in treating different endocrine-related tumors, including prostate and breast cancers (35)(36)(37). However, challenging this view, other studies have emerged that lead to the opposite conclusion, stating that inhibition of AMPK reduces cancer growth (35,36). In particular, the malignant human prostate tissue was shown to display a higher AMPK activity than normal tissue cells.…”

Section: Discussionmentioning

confidence: 99%

Adenosine Inhibits Tumor Cell Invasion via Receptor-Independent Mechanisms

Virtanen

Kukkonen-Macchi

Vainio

et al. 2014

Molecular Cancer Research

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Extracellular adenosine mediates diverse anti-inflammatory, angiogenic, and other signaling effects via binding to adenosine receptors, and it also regulates cell proliferation and death via activation of the intrinsic signaling pathways. Given the emerging role of adenosine and other purines in tumor growth and metastasis, this study evaluated the effects of adenosine on the invasion of metastatic prostate and breast cancer cells. Treatment with low micromolar concentrations of adenosine, but not other nucleosides or adenosine receptor agonists, inhibited subsequent cell invasion and migration through Matrigel-and laminin-coated inserts. These inhibitory effects occurred via intrinsic receptor-independent mechanisms, despite the abundant expression of A2B adenosine receptors (ADORA2B). Extracellular nucleotides and adenosine were shown to be rapidly metabolized on tumor cell surfaces via sequential ecto-5 0 -nucleotidase (CD73/NT5E) and adenosine deaminase reactions with subsequent cellular uptake of nucleoside metabolites and their intracellular interconversion into ADP/ATP. This was accompanied by concurrent inhibition of AMP-activated protein kinase and other signaling pathways. No differences in the proliferation rates, cytoskeleton assembly, expression of major adhesion molecules [integrin1b (ITGB1), CD44, focal adhesion kinase], and secretion of matrix metalloproteinases were detected between the control and treated cells, thus excluding the contribution of these components of invasion cascade to the inhibitory effects of adenosine. These data provide a novel insight into the ability of adenosine to dampen immune responses and prevent tumor invasion via two different, adenosine receptor-dependent and -independent mechanisms.Implications: This study suggests that the combined targeting of adenosine receptors and modulation of intracellular purine levels can affect tumor growth and metastasis phenotypes.

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“…Metformin exerts antitumor effects mainly through AMP-activated protein kinase [AMPK] activation and phosphatidylinositol 3-kinase [PI3K] -Akt-mammalian target of rapamycin [mTOR] inhibition (24)(25)(26)(27) (Figure 1). This drug, which inhibits mitochondrial oxidative phosphorylation and ATP production, leads to activation of the cellular energy-sensing liver kinase B1 [LKB1]/ AMPK pathway (25)(26)(27).…”

Section: Antineoplastic Activity Of Metforminmentioning

confidence: 99%