Fig. 10

CEST imaging of protease enzyme expression in cancer. a GluCEST map of 9L cancer cells cultured without PLG. b GluCEST map of 9L cell line cultured in the presence of PLG showed ~17 % increased GluCEST contrast compared to (a), which is due to the cleavage of PLG by CtB present in the tumor cells. c PLG solution in PBS does not show any appreciable GluCEST contrast. d Western blot analysis shows expression of cathepsin B in both mature and pro form while cathepsin L only in the pro form. The cleavage of PLG in this tumor cell line is predominantly due to CtB. e, f Anatomical image and GluCEST map from a rat brain with a 9L tumor. g At 60 min post intra-venous injection of PLG increased GluCEST contrast was observed in the tumor region due to cleavage of PLG possibly by proteases. Reproduced with permission from the Nature Publishing Group and Haris et al. [100]