Icaritin

Carboxylesterase 2 (CES2), a member of the serine hydrolase superfamily, plays a crucial role in catalyzing the hydrolysis of numerous endogenous and exogenous compounds containing ester bonds. The commonly used clinical drug irinotecan (CPT-11) exerts its anti-tumor effect by being hydrolyzed by CES2 to generate SN-38. Epimedium, a widely used traditional Chinese herb with multiple pharmacological properties, has not yet been characterized for its effects on CES2. Our study systematically evaluated the three principal bioactive components of Epimedium for their effects on CES2 activity, revealing that icaritin significantly activated this enzyme. In vitro, Western blot and RT-PCR assays demonstrated that icaritin significantly upregulated CES2 expression at both mRNA and protein levels. Furthermore, icaritin further enhanced CES2 expression by activating the PXR pathway and increased the protein level of P53. Molecular docking simulations demonstrated that the interation energy between CES2 and icaritin was significantly higher than that with cisplatin (a reported CES2 activator), which might suggest that CES2 has a higher affinity for icaritin than cisplatin. In vivo studies confirmed that icaritin increased the hydrolytic activity and protein expression of Ces in mouse liver and intestinal tissues with a concentration-dependent manner. In conclusion, icaritin can enhance the hydrolysis of irinotecan in vitro and in vivo, and this enhancement is related to the activation of CES2 and the increase of CES2 gene and protein expression. These findings have important clinical significance for reducing chemotherapy drug resistance in cancer patients. Abbreviations: CES2, Carboxylesterase 2; CRC, Colorectal cancer; CPT-11, Irinotecan; CYP3A, Cytochrome P450 3A; NR, Nuclear receptor; P53, Tumor protein p53; PPAR-α, Peroxisome proliferator-activated receptor α; PXR, Pregnane X receptor; SN-38, 7-Ethyl-10-hydroxycamptothecin; UGT1A1, UDP-glucuronosyltransferase 1A1.

Tracking the in vivo fate of nanodrugs remains a significant challenge. In this study, we developed a dual-fluorescence-labeled macromolecular lipid (TPE-PEG2000-ICG; TIP) and a corresponding dual-fluorescence-labeled icaritin microemulsion (TIP-IC-MEs) that could in real time trace both nanocarrier distribution and structural integrity. The design couples the aggregation-caused quenching (ACQ) of indocyanine green (ICG) with the aggregation-induced emission (AIE) of tetraphenylethylene (TPE) via a flexible polyethyleneglycol 2000 (PEG2000) chain. The TPE-AIE moiety could enhance the ACQ effect of the ICG channel, greatly increasing its quenching sensitivity in aqueous environments. This improvement significantly reduced the fluorescence recovery rate of TIP upon probe release from the formulation, which improved the accuracy and reliability of TIP when studying the in vivo fate of nanoformulations. TIP-IC-MEs exhibited favorable physicochemical stability, pH-responsive drug release and in vivo safety. In vitro and in vivo studies further elucidated the critical role of the protein corona in modulating hepatic targeting and clearance pathways of TIP-IC-MEs. Proteomic analysis demonstrated that TIP-IC-MEs selectively recruited specific protein corona components associated with immune recognition, cellular transport, and metabolic reprogramming within the hepatocellular carcinoma model. These corona constituents collectively facilitated tumor-targeted delivery of TIP-IC-MEs through a "cell-hitchhiking" mechanism. This study revealed a dual, context-dependent regulatory role of the protein corona on the in vivo behavior of nanoformulations, providing a novel imaging technology and a mechanistic foundation for rational nanocarrier design and supports the clinical translation of nanomedicines.