Abstract 1538: Inhibition of adenosine-mediated stabilization of intercellular adhesions promotes hypoxia-stressed endometrial carcinoma cell metastasis

• Published in: Cancer research (Chicago, Ill.) Ill.), 2011-04, Vol.71 (8_Supplement), p.1538-1538
• Main Authors: Bowser, Jessica L., Blackburn, Michael R., Shipley, Gregory L., Xie, Susu, Broaddus, Russell R.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2011-1538

Hypoxic microenvironments are commonly encountered in multiple epithelial malignancies. Epithelial cells classically up-regulate cellular adhesive mechanisms to counter the noxious effects of hypoxia. Inhibiting these tissue protective mechanisms is necessary for carcinoma cell invasion and metastasis. Our previous studies utilizing a transgenic model deficient for 5’nucleotidase (CD73), an enzyme responsible for adenosine biosynthesis, demonstrated that adenosine is required to circumvent hypoxia-mediated disruption of cellular adhesiveness in the normal endometrium. In endometrial carcinoma (EC), CD73 is down-regulated in poorly-differentiated, invasive, and metastatic ECs, but is expressed and functional in well-differentiated and non-metastatic disease. Based on these findings, we hypothesized that the malignant progression of EC is dependant on the loss of adenosine-mediated regulation of intercellular adhesions. Modified and unmodified Boyden chambers were used to assess migration and invasion of endometrial adenocarcinoma cells HEC-1A and HEC-1B. Hypoxia (5% or 1.5% O2) significantly reduced HEC-1A and HEC-1B migration and invasion in vitro; this effect was abrogated by CD73 RNA interference and the CD73 enzymatic inhibitor, α, β- methylenediphosphate (AoPCP). The inhibitory effect of CD73 on EC cell migration and invasion was restored by the stable, receptor-targeting adenosine analog, 5’-N-ethylcarboxamido adenosine (NECA). Quantitative RT-PCR identified two adenosine receptors, A1R and A2BR, to be expressed in HEC-1A and HEC-1B. Inhibition of the A2BR by MRS1754 significantly increased HEC-1B migration and invasion, while A1R antagonism (DPCPX) had no effect. A2BR inhibition in HEC-1A monolayers also resulted in increased paracellular permeability to FITC-labeled dextrans. Moreover, A2BR antagonism lowered cellular levels of junctional adhesion proteins claudin-1 and claudin-2, and resulted in increased accumulation of β-catenin within the cytoplasm. Intracellular pools of β-catenin re-organized to the cell membrane with NECA application. In summary, we have shown that CD73-generated adenosine is necessary to maintain normal protective epithelial barrier function in the uterus. Our results demonstrate for the first time that inhibition of adenosine-mediated stabilization of intercellular adhesions promotes cancer cell invasion and metastasis in a hypoxic microenvironment. (NIH TL1RR024147 and NIH 1P50CA098258-01) Citation Format: {Authors}. {Abst