Constitutive androstane receptor weakens the induction of panaxytriol on CYP3A4 by repressing the activation of pregnane X receptor.

Nuclear receptors pregnane X receptor (PXR; NR1I2) and constitutive androstane receptor (CAR; NR1I3) play a vital role in regulating CYP3A4. Our previous studies have demonstrated that panaxytriol (PXT) upregulates the expression of CYP3A4 via the PXR regulatory pathway. This study aimed to explore how CAR mediates the regulation of CYP3A4 in the presence of PXT using HepG2 cell, hCAR-overexpressing HepG2 cell and hCAR-silenced HepG2 cell models. In HepG2 cells, PXT induced the expression of CYP3A4 in a concentration-dependent manner (10-80 µM) and the high concentration of PXT (80 µM) upregulated the expression of CAR. The concentrations of PXT (10-40 µM) had no impact on the expression of CAR, but could significantly induce the expression of CYP2B6 target gene by activating CAR. The dual-luciferase reporter gene assay also showed that CAR-mediated CYP3A4 luciferase activity can be promoted by 80 µM of PXT (1.54-fold), while 5, 10, 20, and 40 µM of PXT had no influence on CAR-mediated CYP3A4 luciferase activity. In hCAR-overexpressing HepG2 cells, PXT concentrations (10-40 µM) that significantly induced PXR and CYP3A4 in HepG2 cells had no impact on the expression of CYP3A4, CAR and PXR, whereas a high concentration of PXT (80 µM) could weakly induce the mRNA and protein levels of CAR and CYP3A4. Moreover, the expression of PXR and CYP3A4 in hCAR-silenced HepG2 cells was markedly elevated compared with the blank control or with normal HepG2 cells treated with 10-80 µM of PXT. In conclusion, CAR significantly weakens the ability of PXT to induce CYP3A4 expression by repressing the activation of PXR. There may be a cross-talk mechanism between PXR and CAR on the regulation of CYP3A4 in the presence of PXT. Additionally, a high concentration of PXT (80 µM) induced CYP3A4 via the CAR regulatory pathway.

Multi-Scale Agent-Based Multiple Myeloma Cancer Modeling and the Related Study of the Balance between Osteoclasts and Osteoblasts.

RESEARCH BACKGROUND: Currently, multiple myeloma is the second most common hematological malignancy in the U.S., constituting 1% of all cancers. With conventional treatment, the median survival time is typically 3-4 years, although it can be extended to 5-7 years or longer with advanced treatments. Recent research indicated that an increase in osteoclast (OC) activity is often associated withmultiple myeloma (MM) and that a decrease inosteoblast (OB) activity contributesto the osteolytic lesions in MM. Normally, the populations of OCs and OBs are inequilibrium, and an imbalance in this statecontributes to the development of lesions. RESEARCH PROCEDURES: A multi-scale agent-based multiple myeloma model was developed to simulate the proliferation, migration and death of OBs and OCs. Subsequently, this model was employed to investigate the efficacy of thethree most commonly used drugs for MM treatment under the following two premises: the reduction in the progression of MM and the re-establishment of the equilibrium between OCs and OBs. RESEARCH PURPOSES: The simulated results not only demonstrated the capacity of the model to choose optimal combinations of the drugs but also showed that the optimal use of the three drugs can restore the balance between OCs and OBs as well as kill MMs. Furthermore, the drug synergism analysis function of the model revealed that restoring the balance between OBs and OCs can significantly increase the efficacy of drugs against tumor cells.

PK of immunoconjugate anticancer agent CMD-193 in rats: ligand-binding assay approach to determine in vivo immunoconjugate stability.

BACKGROUND: Antibody-drug conjugates (ADCs) are a new generation of anticancer therapeutics. The objective of this manuscript is to propose a methodology that can be used to assess the stability of the ADCs by using the PK data obtained by ligand-binding assays that measure various components of ADCs. RESULTS: The ligand-binding assays format of different components of ADCs provided unique valuable PK information. The mathematical manipulation of the bioanalytical data provided an insight into the in vivo integrity, indicating that the loading of the calicheamicin on the G193 antibody declines in an apparent slow first-order process. CONCLUSION: This report demonstrates the value of analyzing various components of the ADC and their PK profiles to better understand the disposition and in vivo stability of ADCs.

Factor VII light chain-targeted lidamycin shows intensified therapeutic efficacy for liver cancer.

The overexpression of tissue factor (TF) observed in numerous cancer cells and clinical samples of human cancers makes TF an ideal target for cancer therapy. The purpose of this study is to develop a TF-targeting energized fusion protein hlFVII-LDP-AE, which is composed of a human Factor VII light chain (hlFVII) as the targeting domain conjugated to the cytotoxic antibiotic lidamycin (LDM, LDP-AE) as the effector domain. The potential efficacy of hlFVII-LDP-AE for cancer therapy was tested in vitro by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays and in vivo with a BALB/c nude mouse xenograft model of human liver cancer line HepG2. The inhibitory concentration (IC(50)) value of hlFVII-LDP-AE varied from 0.15 to 0.64 nM for the various human tumor lines. hlFVII-LDP-AE showed a tumor growth inhibition rate of 90.6% at the dose of 0.6 mg/kg in in vivo animal experiments. The mechanism through which hlFVII-LDP-AE inhibits tumor growth also was determined by Hoechst 33342 staining and Tdt-mediated dUTP nick-end labeling (TUNEL) assay. hlFVII-LDP-AE causes tumor cell death through inducing chromatin condensation and cleavage of genomic DNA. These findings suggest that the hlFVII-LDP-AE protocol is efficacious and tolerated in the mouse model of human liver cancer HepG2 and has clinical applicability for treating cancer patients.

Simultaneous determination of lidamycin enediyne chromophore (LDC) and its aromatized derivative (LDCA) using puerarin as internal standard in rat plasma by LC-MS/MS.

Lidamycin (LDM), a promising enediyne antitumor antibiotic, was quantified by detecting lidamycin enediyne chromophore (LDC) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the first time. A simple, rapid and reliable method was developed and validated to determine LDC and its aromatized derivative (LDCA) simultaneously in plasma. Puerarin was used as an internal standard (IS), and plasma samples were pretreated with one-step precipitation by acetonitrile. Separation was achieved on a reverse-phase C(18) column with a mobile phase composed of methanol and water containing 5 mm ammonium acetate at pH 3.5 in gradient elution mode. Detection was performed on a triple quadrupole tandem mass spectrometer using electrospray ionization (ESI) by multiple reaction monitoring (MRM) in the negative ion mode. Good linearity was obtained over the concentration range of 0.2-100 µg/mL for LDM. Precision and accuracy were validated by RSD% values in the range of 2.6-13.0% and RE% values between -4.6 and 3.8%, respectively. In addition, no specificity and matrix effects were observed. The recovery was found to be 99.2-111.0% and stability in various conditions was found to be acceptable. This method was applied in preclinical pharmacokinetic studies for routine monitoring of LDM in rat plasma.