Pharmacologic characterization of TBP1901, a prodrug form of aglycone curcumin, and CRISPR-Cas9 screen for therapeutic targets of aglycone curcumin.

Curcumin (aglycone curcumin) has antitumor properties in a variety of malignancies via the alteration of multiple cancer-related biological pathways; however, its clinical application has been hampered due to its poor bioavailability. To overcome this limitation, we have developed a synthesized curcumin ß-D-glucuronide sodium salt (TBP1901), a prodrug form of aglycone curcumin. In this study, we aimed to clarify the pharmacologic characteristics of TBP1901. In ß-glucuronidase (GUSB)-proficient mice, both curcumin ß-D-glucuronide and its active metabolite, aglycone curcumin, were detected in the blood after TBP1901 injection, whereas only curcumin ß-D-glucuronide was detected in GUSB-impaired mice, suggesting that GUSB plays a pivotal role in the conversion of TBP1901 into aglycone curcumin in vivo. TBP1901 itself had minimal antitumor effects in vitro, whereas it demonstrated significant antitumor effects in vivo. Genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 screen disclosed the genes associated with NF-κB signaling pathway and mitochondria were among the highest hit. In vitro, aglycone curcumin inhibited NF-kappa B signaling pathways whereas it caused production of reactive oxygen species (ROS). ROS scavenger, N-acetyl-L-cysteine, partially reversed antitumor effects of aglycone curcumin. In summary, TBP1901 can exert antitumor effects as a prodrug of aglycone curcumin through GUSB-dependent activation.

Curcumin ß-D-glucuronide exhibits anti-tumor effects on oxaliplatin-resistant colon cancer with less toxicity in vivo.

The NF-kappa B (NF-κB) pathway plays a pivotal role in tumor progression and chemoresistance, and its inhibition has been shown to suppress tumor growth in a variety of preclinical models. Recently, we succeeded in synthesizing a water-soluble injectable type of curcumin ß-D-glucuronide (CMG), which is converted into a free-form of curcumin by ß-glucuronidase in vivo. Herein, we aimed to clarify the efficacy, safety and pharmacokinetics of CMG in a xenograft mouse model. First, we confirmed that the presence of KRAS/TP53 mutations significantly increased the IC50 of oxaliplatin (L-OHP) and NF-κB activity in HCT116 cells in vitro. Then, we tested the efficacy of CMG in an HCT116 colon cancer xenograft mice model. CMG demonstrated superior anticancer effects compared to L-OHP in an L-OHP-resistant xenograft model. With regard to safety, significant bodyweight loss, severe myelosuppression and AST/ALT elevation were observed in L-OHP-treated mice, whereas none of these toxicity was noted in CMG-treated mice. The combination of CMG and L-OHP exhibited additive effects in these xenograft models without increasing toxicity. Pharmacokinetic analysis revealed that high levels of free-form curcumin were maintained in the tumor tissue after 48 hours following CMG administration, but it was not detected in other major organs, such as the heart, liver and spleen. Immunohistochemistry revealed reduced NF-κB activity in the tumor tissue extracted from CMG-treated mice compared with that from control mice. These results indicated that CMG could be a promising anticancer prodrug for treating colon cancer with minimal toxicity.