1: Radiat Res. 2007 Oct;168(4):428-32.

Thyroid status is a key modulator of tumor oxygenation: implication for radiation
therapy.

Jordan BF, Christian N, Crokart N, Grégoire V, Feron O, Gallez B.

Laboratory of Biomedical Magnetic Resonance, Université Catholique de Louvain,
B-1200 Brussels, Belgium.

In normal tissues, thyroid hormones play a major role in the metabolic activity
and oxygen consumption of cells. Because the rate of oxygen consumption is a key 
factor in the response of tumors to radiation, we hypothesized that thyroid
hormones may affect the metabolic activity of tumor cells and hence modulate the 
response to cytotoxic treatments. We measured the influence of thyroid status on 
the tumor microenvironment in experimental tumors. Hypothyroidism and
hyperthyroidism were generated in mice by chronic treatment with propyl
thiouracil and l-thyroxine. Thyroid status significantly modified tumor pO(2) as 
measured with EPR oximetry. Mechanistically, this was the result of the profound 
changes in oxygen consumption rates. Thyroid status was associated with a
significant change in tumor radiosensitivity since the regrowth delay was
increased in hypothyroid mice compared to euthyroid mice, an effect that was
abolished when temporarily clamped tumors were irradiated. This study provides
unique insights into the impact of modulating tumor oxygen consumption and could 
have implications in the management of cancer patients with thyroid disorders.

PMID: 17903037 [PubMed - indexed for MEDLINE]

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