Keita Saito1, Shingo Matsumoto1, H Douglas Morris2, Martin J. Lizak2, Jeeva P. Munasinghe2, Nallathamby Devasahayam1, Sankaran Subramanian1, James B. Mitchell1, Murali C. Krishna1
1Radiation Biology Branch, National Cancer Institute, Bethesda, MD, United States; 2National Institute of Neurological Disorder and Stroke, Bethesda, MD, United States
We investigated effects of X-irradiation on pyruvate metabolism in squamous cell carcinoma (SCC) implanted in mice leg using 13C-MRI with hyperpolarized [1-13C]pyruvate. [1-13C]lactate to [1-13C]pyruvate ratio (Lac/Pyr) in the SCC tumors increased as tumor grew in non-irradiated control mice. 10 Gy irradiation to SCC tumors slightly suppressed the increase of Lac/Pyr, but there was no significance compared with the control. However, Lac/Pyr significantly droped after three 10 Gy irradiations (10 Gy/day, total dose 30 Gy). So, X-irradiation suppressed increase of LDH activity in SCC tumor, and lactate formation from pyruvate would become a useful marker for tumor response to radiotherapy.