Metabolic changes caused by PI-103 in human PTEN null PC3 prostate and PIK3CA mutant HCT116 colon carcinoma cell lines. A, representative in vitro 31P-MRS and expansion of the choline-containing metabolites region of 1H-MR spectra of PC3 aqueous cell extracts following treatment with PI-103 (5× GI50, 500 nmol/L) compared with vehicle-treated (DMSO) control; Gluc, glucose. B, representative in vitro 31P-MRS and expansion of the choline-containing metabolites region of 1H-MR spectra of HCT116 aqueous cell extracts following treatment with PI-103 (5× GI50, 5 μmol/L) compared with vehicle-treated (DMSO) control. C, comparison of cellular effects and 31P-MRS–detected metabolic changes caused by PI-103 (5× GI50) in PC3 prostate cancer and HCT116 colon cancer cells at 24 h. Results are expressed as % treated versus control (% T/C); columns, mean of at least three separate experiments; bars, SD. Statistically significantly different from the control; *, P ≤ 0.05; **, P < 0.01; †, P ≤ 0.005; and ‡, P < 0.0005; two-tailed unpaired t test was used for all comparisons.