Evaluation of Antitumor Activity of Long-Circulating and pH-Sensitive Liposomes Containing Ursolic Acid in Animal Models of Breast Tumor and Gliosarcoma

Improving Water Solubility and Skin Penetration of Ursolic Acid through a Nanofiber Process to Achieve Better In Vitro Anti-Breast Cancer Activity

Woman's breast cancer has always been among the top ten causes of cancer death, and nearly 2% to 5% of locally advanced breast cancers develop a fungating breast wound. Fungal breast cancer leads to skin ulcers, wound ruptures, and other bacterial infections in patients. Ursolic acid (UA), a natural pentacyclic triterpene compound, is widely distributed in many fruits. Previous studies demonstrated that UA has anti-breast cancer, antifungal, and improved wound-healing effects. UA, however, had poor water solubility and low bioavailability, restricting its clinical application. Nanofibers have the advantages of rapid dissolution, improved stability, and bioavailability of active ingredients. We had successfully prepared ursolic acid nanofibers (UANFs) and effectively improved their water solubility and skin penetration. UANFs can increase water solubility by improving the physicochemical properties, including increased surface area, intermolecular bonding with excipients, and amorphous transformation. Furthermore, UANFs had better anti-breast cancer activity than raw UA. UANFs inhibited the expression of phospho-signal transducer and activator of transcription 3 (STAT3) and phospho-extracellular regulated protein kinases (ERK)1/2, and induced cleaved caspase-3 protein expression, but had no effect on the raw UA treatment. In summary, UANFs enhanced the skin absorption of UA and improved its anti-breast cancer efficacy. We expect that UANFs can be used as an anti-breast cancer treatment and reduce the discomfort of breast cancer patients during dressing changes, but more detailed efficacy and safety trials still need to be conducted in further studies.

Pentacyclic Triterpenoid Phytochemicals with Anticancer Activity: Updated Studies on Mechanisms and Targeted Delivery

Pentacyclic triterpenoids (TTs) represent a unique family of phytochemicals with interesting properties and pharmacological effects, with some representatives, such as betulinic acid (BA) and betulin (B), being mainly investigated as potential anticancer molecules. Considering the recent scientific and preclinical investigations, a review of their anticancer mechanisms, structure-related activity, and efficiency improved by their insertion in nanolipid vehicles for targeted delivery is presented. A systematic literature study about their effects on tumor cells in vitro and in vivo, as free molecules or encapsulated in liposomes or nanolipids, is discussed. A special approach is given to liposome-TTs and nanolipid-TTs complexes to be linked to microbubbles, known as contrast agents in ultrasonography. The production of such supramolecular conjugates to deliver the drugs to target cells via sonoporation represents a new scientific and applicative direction to improve TT efficiency, considering that they have limited availability as lipophilic molecules. Relevant and recent examples of in vitro and in vivo studies, as well as the challenges for the next steps towards the application of these complex delivery systems to tumor cells, are discussed, as are the challenges for the next steps towards the application of targeted delivery to tumor cells, opening new directions for innovative nanotechnological solutions.

Ursolic acid nanoparticles for glioblastoma therapy

BACKGROUND

Glioblastoma multiforme (GBM) is the most common and fatal primary tumor in the central nervous system (CNS). The effect of chemotherapy of GBM is limited due to the existence of blood-brain barrier (BBB). The aim of this study is to develop self-assembled nanoparticles (NPs) of ursolic acid (UA) for GBM treatment.

METHODS

UA NPs were synthesized by solvent volatilization method. Western blot analysis fluorescent staining and flow cytometry were launched to explore the anti-glioblastoma mechanism of UA NPs. The antitumor effects of UA NPs were further confirmed in vivo using intracranial xenograft models.

RESULTS

UA were successfully prepared. In vitro, UA NPs could significantly increase the protein levels of cleaved-caspase 3 and LC3-II to strongly eliminate glioblastoma cells through autophagy and apoptosis. In the intracranial xenograft models, UA NPs could further effectively enter the BBB, and greatly improve the survival time of the mice.

CONCLUSIONS

We successfully synthesized UA NPs which could effectively enter the BBB and show strong anti-tumor effect which may have great potential in the treatment of human glioblastoma.

Advanced Phytochemical-Based Nanocarrier Systems for the Treatment of Breast Cancer

As the world's most prevalent cancer, breast cancer imposes a significant societal health burden and is among the leading causes of cancer death in women worldwide. Despite the notable improvements in survival in countries with early detection programs, combined with different modes of treatment to eradicate invasive disease, the current chemotherapy regimen faces significant challenges associated with chemotherapy-induced side effects and the development of drug resistance. Therefore, serious concerns regarding current chemotherapeutics are pressuring researchers to develop alternative therapeutics with better efficacy and safety. Due to their extremely biocompatible nature and efficient destruction of cancer cells via numerous mechanisms, phytochemicals have emerged as one of the attractive alternative therapies for chemotherapeutics to treat breast cancer. Additionally, phytofabricated nanocarriers, whether used alone or in conjunction with other loaded phytotherapeutics or chemotherapeutics, showed promising results in treating breast cancer. In the current review, we emphasize the anticancer activity of phytochemical-instigated nanocarriers and phytochemical-loaded nanocarriers against breast cancer both in vitro and in vivo. Since diverse mechanisms are implicated in the anticancer activity of phytochemicals, a strong emphasis is placed on the anticancer pathways underlying their action. Furthermore, we discuss the selective targeted delivery of phytofabricated nanocarriers to cancer cells and consider research gaps, recent developments, and the druggability of phytoceuticals. Combining phytochemical and chemotherapeutic agents with nanotechnology might have far-reaching impacts in the future.

Stimuli-responsive liposomal nanoformulations in cancer therapy: Pre-clinical & clinical approaches

The site-specific delivery of antitumor agents is of importance for providing effective cancer suppression. Poor bioavailability of anticancer compounds and the presence of biological barriers prevent their accumulation in tumor sites. These obstacles can be overcome using liposomal nanostructures. The challenges in cancer chemotherapy and stimuli-responsive nanocarriers are first described in the current review. Then, stimuli-responsive liposomes including pH-, redox-, enzyme-, light-, thermo- and magneto-sensitive nanoparticles are discussed and their potential for delivery of anticancer drugs is emphasized. The pH- or redox-sensitive liposomes are based on internal stimulus and release drug in response to a mildly acidic pH and GSH, respectively. The pH-sensitive liposomes can mediate endosomal escape via proton sponge. The multifunctional liposomes responsive to both redox and pH have more capacity in drug release at tumor site compared to pH- or redox-sensitive alone. The magnetic field and NIR irradiation can be exploited for external stimulation of liposomes. The light-responsive liposomes release drugs when they are exposed to irradiation; thermosensitive-liposomes release drugs at a temperature of >40 °C when there is hyperthermia; magneto-responsive liposomes release drugs in presence of magnetic field. These smart nanoliposomes also mediate co-delivery of drugs and genes in synergistic cancer therapy. Due to lack of long-term toxicity of liposomes, they can be utilized in near future for treatment of cancer patients.

The Optimized Delivery of Triterpenes by Liposomal Nanoformulations: Overcoming the Challenges

The last decade has witnessed a sustained increase in the research development of modern-day chemo-therapeutics, especially for those used for high mortality rate pathologies. However, the therapeutic landscape is continuously changing as a result of the currently existing toxic side effects induced by a substantial range of drug classes. One growing research direction driven to mitigate such inconveniences has converged towards the study of natural molecules for their promising therapeutic potential. Triterpenes are one such class of compounds, intensively investigated for their therapeutic versatility. Although the pharmacological effects reported for several representatives of this class has come as a well-deserved encouragement, the pharmacokinetic profile of these molecules has turned out to be an unwelcomed disappointment. Nevertheless, the light at the end of the tunnel arrived with the development of nanotechnology, more specifically, the use of liposomes as drug delivery systems. Liposomes are easily synthesizable phospholipid-based vesicles, with highly tunable surfaces, that have the ability to transport both hydrophilic and lipophilic structures ensuring superior drug bioavailability at the action site as well as an increased selectivity. This study aims to report the results related to the development of different types of liposomes, used as targeted vectors for the delivery of various triterpenes of high pharmacological interest.

Nanoformulations of Ursolic Acid: A Modern Natural Anticancer Molecule

Background: Ursolic acid (UA) is a natural pentacyclic triterpene derived from fruit, herb, and other plants. UA can act on molecular targets of various signaling pathways, inhibit the growth of cancer cells, promote cycle stagnation, and induce apoptosis, thereby exerting anticancer activity. However, its poor water-solubility, low intestinal mucosal absorption, and low bioavailability restrict its clinical application. In order to overcome these deficiencies, nanotechnology, has been applied to the pharmacological study of UA.

Objective: In this review, we focused on the absorption, distribution, and elimination pharmacokinetics of UA in vivo, as well as on the research progress in various UA nanoformulations, in the hope of providing reference information for the research on the anticancer activity of UA.

Methods: Relevant research articles on Pubmed and Web of Science in recent years were searched selectively by using the keywords and subheadings, and were summarized systematically.

Key finding: The improvement of the antitumor ability of the UA nanoformulations is mainly due to the improvement of the bioavailability and the enhancement of the targeting ability of the UA molecules. UA nanoformulations can even be combined with computational imaging technology for monitoring or diagnosis.

Conclusion: Currently, a variety of UA nanoformulations, such as micelles, liposomes, and nanoparticles, which can increase the solubility and bioactivity of UA, while promoting the accumulation of UA in tumor tissues, have been prepared. Although the research of UA in the nanofield has made great progress, there is still a long way to go before the clinical application of UA nanoformulations.

The Role and Therapeutic Targeting of JAK/STAT Signaling in Glioblastoma

Glioblastoma remains one of the deadliest and treatment-refractory human malignancies in large part due to its diffusely infiltrative nature, molecular heterogeneity, and capacity for immune escape. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway contributes substantively to a wide variety of protumorigenic functions, including proliferation, anti-apoptosis, angiogenesis, stem cell maintenance, and immune suppression. We review the current state of knowledge regarding the biological role of JAK/STAT signaling in glioblastoma, therapeutic strategies, and future directions for the field.

Anticancer activities of phytoconstituents and their liposomal targeting strategies against tumor cells and the microenvironment

Various bioactive ingredients have been extracted from Chinese herbal medicines (CHMs) that affect tumor progression and metastasis. To further understand the mechanisms of CHMs in cancer therapy, this article summarizes the effects of five categories of CHMs and their active ingredients on tumor cells and the tumor microenvironment. Despite their treatment potential, the undesirable physicochemical properties (poor permeability, instability, high hydrophilicity or hydrophobicity, toxicity) and unwanted pharmacokinetic profiles (short half-life in blood and low bioavailability) restrict clinical studies of CHMs. Therefore, development of liposomes through relevant surface modifying techniques to achieve targeted CHM delivery for cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature, have been reviewed. Current challenges of liposomal targeting of these phytoconstituents and future perspective of CHM applications are discussed to provide an informative reference for interested readers.

Liposome Delivery of Natural STAT3 Inhibitors for the Treatment of Cancer

In the tumor microenvironment, cytokines, growth factors, and oncogenes mediate constitutive activation of the signal transducer and activator of transcription 3 (STAT3) signaling pathway in both cancer cells and infiltrating immune cells. STAT3 activation in cancer cells drives tumorigenic changes that allow for increased survival, proliferation, and resistance to apoptosis. The modulation of immune cells is more complicated and conflicting. STAT3 signaling drives the myeloid cell phenotype towards an immune suppressive state, which mediates T cell inhibition. On the other hand, STAT3 signaling in T cells leads to proliferation and T cell activity required for an anti-tumor response. Targeted delivery of STAT3 inhibitors to cancer cells and myeloid cells could therefore improve therapeutic outcomes. Many compounds that inhibit the STAT3 pathways for cancer treatment include peptide drugs, small molecule inhibitors, and natural compounds. However, natural compounds that inhibit STAT3 are often hydrophobic, which reduces their bioavailability and leads to unfavorable pharmacokinetics. This review focuses specifically on liposome-encapsulated natural STAT3 inhibitors and their ability to target cancer cells and myeloid cells to reduce tumor growth and decrease STAT3-mediated immune suppression. Many of these liposome formulations have led to profound tumor reduction and examples of combination formulations have been shown to eliminate tumors through immune modulation.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

Numerous natural products originated from Chinese herbal medicine exhibit anti-cancer activities, including anti-proliferative, pro-apoptotic, anti-metastatic, anti-angiogenic effects, as well as regulate autophagy, reverse multidrug resistance, balance immunity, and enhance chemotherapy in vitro and in vivo. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2011) on the key compounds with anti-cancer effects derived from Chinese herbal medicine (curcumin, epigallocatechin gallate, berberine, artemisinin, ginsenoside Rg3, ursolic acid, silibinin, emodin, triptolide, cucurbitacin B, tanshinone I, oridonin, shikonin, gambogic acid, artesunate, wogonin, β-elemene, and cepharanthine) in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we focused on their recently discovered and/or investigated pharmacological effects, novel mechanism of action, relevant clinical studies, and their innovative applications in combined therapy and immunomodulation. In addition, the present review has extended to describe other promising compounds including dihydroartemisinin, ginsenoside Rh2, compound K, cucurbitacins D, E, I, tanshinone IIA and cryptotanshinone in view of their potentials in cancer therapy. Up to now, the evidence about the immunomodulatory effects and clinical trials of natural anti-cancer compounds from Chinese herbal medicine is very limited, and further research is needed to monitor their immunoregulatory effects and explore their mechanisms of action as modulators of immune checkpoints.

Ursolic acid suppresses the biological function of osteosarcoma cells

Osteosarcoma is a highly malignant tumour that occurs in adolescents. Upregulation or the constitutive activation of epidermal growth factor receptor (EGFR) is a hallmark of osteosarcoma. To investigate the effect of ursolic acid on the biological function of osteosarcoma, MTT assay was used to detect the effect of ursolic acid on the proliferation of HOS and MG63 cells, while flow cytometry was used to analyse the effect on the cell cycle and apoptosis. Transwell and Matrigel assays were used to detect the effect of ursolic acid on cell migration and invasion, respectively. Western blot analysis and reverse transcription-quantitative polymerase chain reaction were used to detect the effects of different concentrations of ursolic acid on EGFR signaling pathway-related proteins, cell cycle, apoptosis and cell migration-related proteins. After overexpression or silencing of EGFR, the effects of ursolic acid on EGFR pathway and cell biological function were subsequently detected, using the same methods. The present study identified that ursolic acid had inhibitory effects on the growth and metastatic ability of osteosarcoma cells by suppressing EGFR.

Ursolic acid: Pharmacokinetics process in vitro and in vivo, a mini review

Ursolic acid (UA) is a natural triterpene compound found in various fruits and vegetables. UA has a widespread pharmacologic effect, including antitumor, anti-inflammatory, anti-oxidant, anti-apoptotic, anti-allergy, and anti-carcinogenic effects. UA can be used as an alternative medicine for the treatment and prevention of many diseases. However, the bioavailability of UA by oral administration is low since it is absorbed by the intestine through passive diffusion. Therefore, some novel technologies are used to produce UA preparations that can change the pharmacokinetics process and increase its solubility and bioavailability. At present, pharmacokinetic studies on UA are few. In this paper, we will review the pharmacokinetics features of free UA and some novel UA preparations in vitro and in vivo, in order to provide a reference for rational utilization and drug design of UA.