Lenvatinib in hepatocellular carcinoma: Resistance mechanisms and strategies for improved efficacy.

Hepatocellular carcinoma (HCC), one of the most prevalent and destructive causes of cancer-related deaths worldwide, approximately 70% of patients with HCC exhibit advanced disease at diagnosis, limiting the potential for radical treatment. For such patients, lenvatinib, a long-awaited alternative to sorafenib for first-line targeted therapy, has become a key treatment. Unfortunately, despite some progress, the prognosis for advanced HCC remains poor because of drug resistance development. However, the molecular mechanisms underlying lenvatinib resistance and ways to relief drug resistance in HCC are largely unknown and lack of systematic summary; thus, this review not only aims to explore factors contributing to lenvatinib resistance in HCC, but more importantly, summary potential methods to conquer or mitigate the resistance. The results suggest that abnormal activation of pathways, drug transport, epigenetics, tumour microenvironment, cancer stem cells, regulated cell death, epithelial-mesenchymal transition, and other mechanisms are involved in the development of lenvatinib resistance in HCC and subsequent HCC progression. To improve the therapeutic outcomes of lenvatinib, inhibiting acquired resistance, combined therapies, and nano-delivery carriers may be possible approaches.

Evaluation of antityrosinase activity and mechanism, antioxidation, and UV filter properties of theaflavin.

Tyrosinase is a key metalloenzyme for the biosynthesis of melanin that plays a critical role in the prevention of skin damage caused by ultraviolet (UV) radiation. However, the overproduction of melanin may cause a variety of skin diseases. Due to the toxicity and inefficiency of existing tyrosinase inhibitors, it is urgent to identify safe and potent alternatives from natural sources. Theaflavin, a single-component extracted from black tea, has been found to possess a variety of pharmacological activities. Herein, the inhibition kinetics of theaflavin on tyrosinase and inhibitory mechanism were determined using spectroscopy, molecular docking, and zebrafish model. The results showed that theaflavin inhibited the diphenolase activity of tyrosinase in a reversible mixed type manner with IC50 of 229.75 µmol/L and hindered the synthesis of melanin in zebrafish. This may be due to the formation of eight hydrogen bonds and hydrophobic effects between theaflavin and tyrosinase according to the results of molecular docking. To study the possible effects on the prevention of free radical-mediated skin cancer and photoaging caused by UV radiation, the antioxidation and UV filter properties of theaflavin were further verified. This study demonstrates that theaflavin is a potential multifunctional compound that can be used in cosmetic and medicinal products.

Structure-activity relationships of antityrosinase and antioxidant activities of cinnamic acid and its derivatives.

The related structure-activity relationships of cinnamic acid and its derivates have not been studied in details yet. Herein, antityrosinase and antioxidant activities of 18 compounds were evaluated. The results demonstrated that the substituents on the phenyl ring of cinnamic acid led to the enhancement of the inhibition on monophenolase and the weakening of the inhibition on diphenolase. Among these tested compounds, 9 was first discovered as a tyrosinase inhibitor in a reversible competitive manner with IC50 value of 68.6 ± 4.2 µm. Docking results demonstrated 9 located into the catalytic center of tyrosinase. Antioxidant assay indicated that only 1 hydroxyl group on the phenyl ring was not enough to possess the radical scavenging activity, and the number of hydroxyl groups may be more important. This study will be helpful in the development of new cinnamic acid derivates as tyrosinase inhibitors and antioxidants with higher efficacy.

Co-Delivery of Docetaxel and Curcumin Functionalized Mixed Micelles for the Treatment of Drug-Resistant Breast Cancer by Oral Administration.

Background: Chemotherapeutic drugs have some drawbacks in antineoplastic therapy, mainly containing seriously toxic side effects caused by injection and multi-drug resistance (MDR). Co-delivery with two or more drugs via nanomicelles is a promising strategy to solve these problems. Oral chemotherapy is increasingly preferred owing to its potential to enhance the life quality of patients. Methods and Results: The study intended to develop mixed micelles using D-α-Tocopherol poly(ethylene glycol) 1000 succinate (TPGS) and soluplus for the co-encapsulation of docetaxel (DTX) and curcumin (CUR), marked as (DTX+CUR)-loaded mixed micelles, treating drug-resistant breast cancer by oral administration. The (DTX+CUR)-loaded mixed micelles had a uniform particle size (~64 nm), high drug loading and encapsulation efficiency, in vitro sustained-release properties and good pH-dependent stability. In vitro cell study, the (DTX+CUR)-loaded mixed micelles displayed the highest cellular uptake, cytotoxicity, cell apoptosis-inducing rates and cell ROS-inducing levels on MCF-7/Adr cells. Notably, in vivo pharmacokinetic studies, (DTX+CUR)-loaded mixed micelles enhanced markedly the oral absorption of DTX compared to pure DTX, with a relative oral bioavailability of 574%. The (DTX+CUR)-loaded mixed micelles by oral administration had the same anticancer efficacy as taxotere by injection in resistant breast cancer bearing mice. Conclusion: (DTX+CUR)-loaded mixed micelles could provide a potential formulation for treating drug-resistant breast cancers by oral administration.

Fabrication and Evaluation of Glabridin Tip-loaded Dissolving Microneedles.

BACKGROUND: The clinical application of glabridin in treating skin diseases has been constrained by the limitations of its poor chemical stability and low skin permeability. OBJECTIVE: Here, we describe Tip-loading Dissolving Microneedles (TDMNs) encapsulating drugs only in the tips of needles for glabridin delivery with improved stability and skin permeability. METHODS: The TDMNs fabricated by solvent casting technique had sufficient mechanical strength to penetrate through the excised rat's skin without fracture. Drug delivery efficiency and drug residual in the skin of TDMNs were 63.16% and 49.28%, respectively. Glabridin encapsulated in the tips of TDMNs was effectively delivered into the abdominal skin of rat, and the in vivo delivery efficiency was inversely proportional to the drug doses. RESULTS: Transepidermal Water Loss (TEWL) significantly increased to 34.80 g/m2·h after the application of TDMNs and returned to normal levels (11.31 g/m2·h) after 8 h, indicating that the TDMNs were well tolerated. The stability of glabridin at room temperature was appreciably improved when loaded in TDMNs. CONCLUSION: These results suggest that intradermal delivery of glabridin by TDMNs is a safe and efficient alternative to currently available routes of administration.

Inhibition of Tyrosinase by Mercury Chloride: Spectroscopic and Docking Studies.

Inorganic mercury compounds have been used in skin-lightening products since ancient times. Although a previous study demonstrated that mercury impeded the transfer of Cu2+ to the apotyrosinase, the effect of mercury on tyrosinase is still unclear. In the present study, the mechanism of mercury chloride (HgCl2) induced inactivation of tyrosinase was investigated for the first time. The IC50 values were 29.97 and 77.93 µmol/L for monophenolase and diphenolase, respectively. A kinetic analysis revealed that HgCl2 inhibited tyrosinase activity in an irreversible non-competitive manner. The strong intrinsic fluorescence quenching suggested that the formation of the HgCl2-tyrosinase complex induced conformational changes of the enzyme, and HgCl2 had only one single binding site or a single class of binding site on tyrosinase. The molecular docking and further experiments demonstrated that HgCl2 bound to the amino residuals (His) in the catalytic center of tyrosinase. To our knowledge, these findings presented in this paper were the first evidence of the direct interactions between HgCl2 and tyrosinase, which provided a deep understanding of the inhibition mechanism of mercury on tyrosinase.