Brittney Short

Overexpression of high affinity Type I adenosine receptors promotes the growth of uterine leiomyomas

Abstract Leiomyomas are benign proliferations of uterine smooth muscle found in 60% of women. A spatial redistribution of ecto-5'-nucleotidase (CD73, NT5E) that results in reduced extracellular concentrations of adenosine has recently been described in leiomyomas. However, the mechanisms by which altered extracellular adenosine levels contribute to leiomyoma growth remain poorly understood. To address this deficiency, a series of tissue specimens and primary cultures generated from matched specimens of myometrium and leiomyoma were used. Overexpression of Type 1 adenosine receptors (ADORA1) was observed when matched specimens and primary cultures were interrogated by RT-qPCR and western blot. By immunohistochemistry, ADORA1 expression was diffusely observed in myocytes in the leiomyoma complex, with only limited expression in vascular and other structures. Overexpression of ADORA1 was also observed in fibroblasts and multiple smooth muscle subtypes in the leiomyoma complex when single-cell transcriptomics data were interrogated. Incubation with N6-cyclopentyladenosine (CPA), a selective ADORA1 agonist, resulted in decreased proliferation of primary leiomyoma cultures, accompanied by decreased intracellular cAMP and enhanced cyclin D1 and phospho-AKT1 expression. To confirm the specificity of this observation, ADORA1 expression was directly targeted by siRNA, resulting in decreased proliferation, increased intracellular cAMP, and lower levels of cyclin D1 and phospho-AKT1. Collectively, these data indicate that overexpression of the ADORA1 receptor is a robust feature of uterine leiomyomas, where its activation by residual levels of extracellular adenosine potentially contributes to tumor growth by regulating AKT1-mediated signaling.

Spatially restricted ecto‐5′‐nucleotidase expression promotes the growth of uterine leiomyomas by modulating Akt activity

Abstract Found in as many as 80% of women, uterine leiomyomas are a frequent cause of abnormal uterine bleeding, pelvic pain, and infertility. Despite their significant clinical impact, the mechanisms responsible for driving leiomyoma growth remain poorly understood. After obtaining IRB permission, expression of ecto‐5′‐nucleotidase ( NT5E, CD73 ) was assessed in matched specimens of myometrium and leiomyoma by real‐time qPCR, Western blot, and immunohistochemistry (IHC). Adenosine concentrations were measured by enzyme‐linked assay. Primary cultures were used to assess the impact of adenosine and/or adenosine receptor agonists on proliferation, apoptosis, and patterns of intracellular signaling in vitro. When compared to matched specimens of healthy myometrium, uterine leiomyomas were characterized by reduced CD73 expression. Largely limited to thin‐walled vascular structures and the pseudocapsule of leiomyomas despite diffuse myometrial distribution. Restricted intra‐tumoral CD73 expression was accompanied by decreased levels of intra‐tumoral adenosine. In vitro, incubation of primary leiomyoma cultures with adenosine or its hydrolysis‐resistant analog 2‐chloro‐adenosine (2‐CL‐AD) inhibited proliferation, induced apoptosis, and reduced proportion of myocytes in S‐ and G2‐M phases of the cell cycle. Decreased proliferation was accompanied by reduced expression of phospho‐Akt, phospho‐Cdk2‐Tyr15, and phospho‐Histone H3. Enforced expression of the A2B adenosine receptor (ADORA2B) and ADORA2B‐selective agonists similarly suppressed proliferation and inhibited Akt phosphorylation. Collectively, these observations broadly implicate CD73 and reduced extracellular concentrations of adenosine as key regulators of leiomyoma growth and potentially identify novel strategies for clinically managing these common tumors.