Galactosylated poly(ethyleneglycol)-lithocholic Acid selectively kills hepatoma cells, while sparing normal liver cells

The Effect of Lithocholic Acid on the Gut-Liver Axis

Lithocholic acid (LCA) is a monohydroxy bile acid produced by intestinal flora, which has been found to be associated with a variety of hepatic and intestinal diseases. LCA is previously considered to be toxic, however, recent studies revealed that LCA and its derivatives may exert anti-inflammatory and anti-tumor effects under certain conditions. LCA goes through enterohepatic circulation along with other bile acids, here, we mainly discuss the effects of LCA on the gut-liver axis, including the regulation of gut microbiota, intestinal barrier, and relevant nuclear receptors (VDR, PXR) and G protein-coupled receptor five in related diseases. In addition, we also find that some natural ingredients are involved in regulating the detoxification and excretion of LCA, and the interaction with LCA also mediates its own biological activity.

Lithocholic acid-tryptophan conjugate (UniPR126) based mixed micelle as a nano carrier for specific delivery of niclosamide to prostate cancer via EphA2 receptor

Targeted delivery of chemotherapeutic agents is considered a prominent strategy for the treatment of cancer due to its site-specific delivery, augmented penetration, bioavailability, and improved therapeutic efficiency. In the present study, we employed UniPR126 as a carrier in a mixed nanomicellar delivery system to target and deliver anticancer drug NIC specifically to cancer cells via EphA2 receptors as these receptors are overexpressed in cancer cells but not in normal cells. The specificity of the carrier was confirmed from the significant enhancement in the uptake of coumarin-6 loaded mixed nanomicelle by EphA2 highly expressed PC-3 cells compared to EphA2 low expressed H4 cells. Further, niclosamide-loaded lithocholic acid tryptophan conjugate-based mixed nanomicelle has shown significant synergistic cytotoxicity in PC-3 but not in H4 cells. In vivo anticancer efficacy data in PC-3 xenograft revealed a significant reduction in the tumor volume (66.87%) with niclosamide-loaded lithocholic acid tryptophan conjugate nanomicelle, where pure niclosamide showed just half of the activity. Molecular signaling data by western blotting also indicated that niclosamide-loaded lithocholic acid tryptophan conjugate nanomicelle interfered with the EphA2 receptor signaling and inhibition of the Wnt/beta-catenin pathway and resulted in the synergistic anticancer activity compared to niclosamide pure drug.

Viramidine-Loaded Galactosylated Nanoparticles Induce Hepatic Cancer Cell Apoptosis and Inhibit Angiogenesis

Current estimates indicate that hepatocarcinoma is the leading cause of death globally. There is interest in utilizing nanomedicine for cancer therapy to overcome side effects of chemo-interventions. Ribavirin, an antiviral nucleoside inhibitor, accumulates inside red blood cells, causing anemia. Its analog, viramidine, can concentrate within hepatocytes and spare red blood cells, thus limiting anemia. Hepatocarcinoma cells have a large number of asialoglycoprotein receptors on their membranes that can bind galactosyl-terminating solid lipid nanoparticles (Gal-SLN) and internalize them. Here, viramidine, 5-fluorouracil, and paclitaxel-loaded Gal-SLN were characterized inside cells. Cytotoxicities of free-drug, nano-void, and drug-loaded Gal-SLN were evaluated using HepG2 cells; over 3 days, cell viability was measured. To test the mechanistic pathway, we investigated in vitro apoptosis using flow cytometry and in ovo angiogenesis using the CAM assay. Results showed that 1 and 2 μM of the viramidine-encapsulated Gal-SLN had the highest cytotoxic effect, achieving 80% cell death with a steady increase over 3 days, with induction of apoptosis and reduction of necrosis and angiogenesis, compared to free-drugs. Gal-SLN application on breast cancer MCF-7 cells confirmed its specificity against liver cancer HepG2 cells. We conclude that viramidine-encapsulated Gal-SLN has anticancer and anti-angiogenic activities against hepatocarcinoma.

Small Molecule Inhibitors of the PCSK9·LDLR Interaction

The protein-protein interaction between proprotein convertase subtilisin/kexin type 9 (PCSK9) and low-density lipoprotein receptor (LDLR) is a relatively new, and extremely important, validated therapeutic target for treatment and prevention of heart disease. Experts in the area agree that the first small molecules to disrupt PCSK9·LDLR would represent a milestone in this field, yet few credible leads have been reported. This paper describes how side-chain orientations in preferred conformations of carefully designed chemotypes were compared with LDLR side chains at the PCSK9·LDLR interface to find molecules that would mimic interface regions of LDLR. This approach is an example of the procedure called EKO (Exploring Key Orientations). The guiding hypothesis on which EKO is based is that good matches indicate the chemotypes bearing the same side chains as the protein at the sites of overlay have the potential to disrupt the parent protein-protein interaction. In the event, the EKO procedure and one round of combinatorial fragment-based virtual docking led to the discovery of seven compounds that bound PCSK9 (SPR and ELISA) and had a favorable outcome in a cellular assay (hepatocyte uptake of fluorescently labeled low-density lipoprotein particles) and increased the expression LDLR on hepatocytes in culture. Three promising hit compounds in this series had dissociation constants for PCSK9 binding in the 20-40 μM range, and one of these was modified with a photoaffinity label and shown to form a covalent conjugate with PCSK9 on photolysis.

Combination therapy with doxorubicin-loaded galactosylated poly(ethyleneglycol)-lithocholic acid to suppress the tumor growth in an orthotopic mouse model of liver cancer

Despite advances in technology, neither conventional anti-cancer drugs nor current nanoparticle (NP) drugs have gained substantial success in cancer treatment. While conventional chemotherapy drugs have several limitations such as low potency, poor in vivo stability and limited bioavailability, non-specific targeting of NP drugs diminishes their potency at actual target sites. In addition, the development of drug resistance to anti-cancer drugs is another challenging problem. To overcome these limitations, we aimed to develop a polymer-drug conjugate, which functions as an active NP drug and drug carrier both, to deliver a chemotherapeutic drug for combination therapy. Accordingly, we made targeting NP carrier of lithocholic acid-poly(ethylene glycol)-lactobionic acid (LPL) loading doxorubicin (Dox) to produce Dox/LPL NPs. The cellular uptake of Dox/LPL NPs was relatively higher in human liver cancer cell line (SK-HEP-1) due to galactose ligand-asialoglycoprotein receptor interaction. Consequently, the cellular uptake of Dox/LPL NPs led to massive cell death of SK-HEP-1 cells by two different mechanisms, particularly apoptotic activity by LPL and mitotic catastrophe by Dox. Most importantly, Dox/LPL NPs, when administered to orthotopic xenograft model of liver cancer, greatly reduced proliferation, invasion, migration, and angiogenesis of liver tumor in vivo. Thus, this study exemplifies the superiority of combination therapy over individual NP drug or conventional small molecule drug for cancer therapy. Overall, we present a promising approach of combinatorial therapy to inhibit the hepatic tumor growth and metastasis in the orthotopic xenograft model mice, thus representing an effective weapon for cancer treatment.

Lithocholic acid induces endoplasmic reticulum stress, autophagy and mitochondrial dysfunction in human prostate cancer cells

Lithocholic acid (LCA) is a secondary bile acid that is selectively toxic to human neuroblastoma, breast and prostate cancer cells, whilst sparing normal cells. We previously reported that LCA inhibited cell viability and proliferation and induced apoptosis and necrosis of androgen-dependent LNCaP and androgen-independent PC-3 human prostate cancer cells. In the present study, we investigated the roles of endoplasmic reticulum (ER) stress, autophagy and mitochondrial dysfunction in the toxicity of LCA in PC-3 and autophagy deficient, androgen-independent DU-145 cells. LCA induced ER stress-related proteins, such as CCAAT-enhancer-binding protein homologous protein (CHOP), and the phosphorylation of eukaryotic initiation factor 2-alpha (p-eIF2α) and c-Jun N-terminal kinases (p-JNK) in both cancer cell-types. The p53 upregulated modulator of apoptosis (PUMA) and B cell lymphoma-like protein 11 (BIM) levels were decreased at overtly toxic LCA concentrations, although PUMA levels increased at lower LCA concentrations in both cell lines. LCA induced autophagy-related conversion of microtubule-associated proteins 1A/1B light chain 3B (LC3BI-LC3BII), and autophagy-related protein ATG5 in PC-3 cells, but not in autophagy-deficient DU-145 cells. LCA (>10 µM) increased levels of reactive oxygen species (ROS) concentration-dependently in PC-3 cells, whereas ROS levels were not affected in DU-145 cells. Salubrinal, an inhibitor of eIF2α dephosphorylation and ER stress, reduced LCA-induced CHOP levels slightly in PC-3, but not DU-145 cells. Salubrinal pre-treatment increased the cytotoxicity of LCA in PC-3 and DU-145 cells and resulted in a statistically significant loss of cell viability at normally non-toxic concentrations of LCA. The late-stage autophagy inhibitor bafilomycin A1 exacerbated LCA toxicity at subtoxic LCA concentrations in PC-3 cells. The antioxidant α-tocotrienol strongly inhibited the toxicity of LCA in PC-3 cells, but not in DU-145 cells. Collectively, although LCA induces autophagy and ER stress in PC-3 cells, these processes appear to be initially of protective nature and subsequently consequential to, but not critical for the ROS-mediated mitochondrial dysfunction and cytotoxicity of LCA. The full mechanism of LCA-induced mitochondrial dysfunction and cytotoxicity in the similarly sensitive DU-145 cells remains to be elucidated.