Metabolic signatures of androgen-dependent (LNCaP) and androgen-independent (CSS90) prostate tumors were investigated using hyperpolarized [1-13C]pyruvate imaging. Higher pyruvate-to-lactate conversion in CSS90 were confirmed by higher glycolysis in CSS90 measured by extracellular acidification rate of the tumor slices. Treatment with MDV3100 lead to higher oxidative phosphorylation measured by oxygen consumption rate. Initial in vivo experiments suggested a reduced pyruvate-to-lactate conversion in LNCaP tumors after treatment, potentially a marker for positive response to therapy. These findings demonstrated that conversion of hyperpolarized pyruvate to lactate is a useful biomarker to both characterize tumor androgen sensitivity and potentially to evaluate response to therapy.