Injectable (-)-gossypol-loaded Pluronic P85 micelles for cancer chemoradiotherapy

Gossypol and Its Natural Derivatives: Multitargeted Phytochemicals as Potential Drug Candidates for Oncologic Diseases

Despite the vast amounts of research and remarkable discoveries that have been made in recent decades, cancer remains a leading cause of death and a major public health concern worldwide. Gossypol, a natural polyphenolic compound derived from the seeds, roots, and stems of cotton (Gossypium hirsutum L.), was first used as a male contraceptive agent. Due to its diverse biological properties, including antifertility, antiviral, antioxidant, antibacterial, antimalarial, and most notably antitumor activities, gossypol has been the subject of numerous studies. Nevertheless, no systematic review has been performed that analyzes the antineoplastic potential of gossypol and related natural compounds in an organ-specific manner while delineating the molecular mechanisms of action. Hence, we have performed an extensive literature search for anticancer properties of gossypol and their natural derivatives against various types of cancer cells utilizing PubMed, ScienceDirect, Google Scholar, and Scopus. The sources, distribution, chemical structure, and toxicity of gossypol and its constituents are briefly reviewed. Based on emerging evidence, gossypol and related compounds exhibit significant antineoplastic effects against various cancer types through the modulation of different cancer hallmarks and signaling pathways. Additionally, the synergistic activity of gossypol and its derivatives with chemotherapeutic agents has been observed. Our evaluation of the current literature suggests the potential of gossypol and its derivatives as multitargeting drug candidates to combat multiple human malignancies.

Cyclic RGD-Decorated Liposomal Gossypol AT-101 Targeting for Enhanced Antitumor Effect

Introduction

(-)-Gossypol (AT-101), the (-)-enantiomer of the natural compound gossypol, has shown significant inhibitory effects on various types of cancers such as osteosarcoma, myeloma, glioma, lung cancer, and prostate cancer. However, the clinical application of (-)-gossypol was often hindered by its evident side effects and the low bioavailability via oral administration, which necessitated the development of suitable (-)-gossypol preparations to settle the problems. In this study, injectable cyclic RGD (cRGD)-decorated liposome (cRGD-LP) was prepared for tumor-targeted delivery of (-)-gossypol.

Methods

The cRGD-LP was prepared based on cRGD-modified lipids. For comparison, a non-cRGD-containing liposome (LP) with a similar chemical composition to cRGD-LP was specially designed. The physicochemical properties of (-)-gossypol-loaded cRGD-LP (Gos/cRGD-LP) were investigated in terms of the drug loading efficiency, particle size, morphology, drug release, and so on. The inhibitory effect of Gos/cRGD-LP on the proliferation of tumor cells in vitro was evaluated using different cell lines. The biodistribution of cRGD-LP in vivo was investigated via the near-infrared (NIR) fluorescence imaging technique. The antitumor effect of Gos/cRGD-LP in vivo was evaluated in PC-3 tumor-bearing nude mice.

Results

Gos/cRGD-LP had an average particle size of about 62 nm with a narrow size distribution, drug loading efficiency of over 90%, and sustained drug release for over 96 h. The results of NIR fluorescence imaging demonstrated the enhanced tumor targeting of cRGD-LP in vivo. Moreover, Gos/cRGD-LP showed a significantly enhanced inhibitory effect on PC-3 tumors in mice, with a tumor inhibition rate of over 74% and good biocompatibility.

Conclusion

The incorporation of cRGD could significantly enhance the tumor-targeting effect of the liposomes and improve the antitumor effect of the liposomal (-)-gossypol in vivo, which indicated the potential of Gos/cRGD-LP that warrants further investigation for clinical applications of this single-isomer drug.

BH3-mimetics: recent developments in cancer therapy

The hopeful outcomes from 30 years of research in BH3-mimetics have indeed served a number of solid paradigms for targeting intermediates from the apoptosis pathway in a variety of diseased states. Not only have such rational approaches in drug design yielded several key therapeutics, such outputs have also offered insights into the integrated mechanistic aspects of basic and clinical research at the genetics level for the future. In no other area of medical research have the effects of such work been felt, than in cancer research, through targeting the BAX-Bcl-2 protein-protein interactions. With these promising outputs in mind, several mimetics, and their potential therapeutic applications, have also been developed for several other pathological conditions, such as cardiovascular disease and tissue fibrosis, thus highlighting the universal importance of the intrinsic arm of the apoptosis pathway and its input to general tissue homeostasis. Considering such recent developments, and in a field that has generated so much scientific interest, we take stock of how the broadening area of BH3-mimetics has developed and diversified, with a focus on their uses in single and combined cancer treatment regimens and recently explored therapeutic delivery methods that may aid the development of future therapeutics of this nature.

Research progress on nanotechnology for delivery of active ingredients from traditional Chinese medicines

There is growing acceptance of traditional Chinese medicines (TCMs) as potential sources of clinical agents based on the demonstrated efficacies of numerous bioactive compounds first identified in TCM extracts, such as paclitaxel, camptothecin, and artemisinin. However, there are several challenges to achieving the full clinical potential of many TCMs, particularly the generally high hydrophobicity and low bioavailability. Recently, however, numerous studies have attempted to circumvent the limited in vivo activity and systemic toxicity of TCM ingredients by incorporation into nanoparticle-based delivery systems. Many of these formulations demonstrate improved bioavailability, enhanced tissue targeting, and greater in vivo stability compared to the native compound. This review summarizes nanoformulations of the most promising and extensively studied TCM compounds to provide a reference for further research. Combining these natural compounds with nanotechnology-based delivery systems may further improve the clinical utility of these agents, in turn leading to more intensive research on traditional medicinal compounds.

Pluronic-based nanovehicles: Recent advances in anticancer therapeutic applications

Pluronics are a class of amphiphilic tri-block copolymers with wide pharmaceutical applicability. In the past decades, the ability to form biocompatible nanosized micelles was exploited to formulate stable drug nanovehicles with potential use in antitumor therapy. Due to the great potential for tuning physical and structural properties of Pluronic unimers, a panoply of drug or polynucleotide-loaded micelles was prepared and tested for their antitumoral activity. The attractive inherent antitumor properties of Pluronic polymers in combination with cell targeting and stimuli-responsive ligands greatly improved antitumoral therapeutic effects of tested drugs. In spite of that, the extraordinary complexity of biological challenges in the delivery of micellar drug payload makes their therapeutic potential still not exploited to the fullest. In this review paper we attempt to present the latest developments in the field of Pluronic based nanovehicles and their application in anticancer therapy with an overview of the chemistry involved in the preparation of these nanovehicles.

The aldehyde group of gossypol induces mitochondrial apoptosis via ROS-SIRT1-p53-PUMA pathway in male germline stem cell

As a widely grown economic crop, cotton is the major oil and protein resource for human and livestock. But the highly toxic of gossypol in cottonseed severely restricts its effective utilization, consequently creating huge resource waste. Previous studies have shown the male germline stem cells were the most vulnerable cells in gossypol damages, but the mechanism was still unclear. We found gossypol induced cell viability decline resulted from apoptosis. And the increase of Caspase-9 activity in gossypol treatment hinted the mitochondrial apoptosis. So the mitochondrial dysfunction was confirmed by the decreased mitochondrial membrane potential and ATP concentration. We found the higher intracellular H₂O₂ level did not accompany with the O₂^·- associated increase in gossypol-treated, which indicated that gossypol obstructed the intracellular reactive oxygen species (ROS) elimination. Manipulated gossypol-induced H₂O₂ level by H₂O₂ and α-lipoic acid, we demonstrated that the mitochondrial dysfunction resulted from the excessive intracellular H₂O₂. Treated with Apogossypolone (ApoG2), an aldehyde group removed derivative of gossypol, the GSH/GSSG ratio and H₂O₂ did not decrease. ApoG2 also did not cause the mitochondrial apoptosis. So the aldehyde group is key factor in gossypol cytotoxicity. We respectively detected the NAD⁺/NADH ratio, SIRT1 activity, the relative protein level and apoptosis. Comparing with the specific inhibitors groups, the data illustrated that gossypol induced apoptosis through SIRT1-P53-PUMA pathway. This study helped to overcome barriers of gossypol cytotoxicity, which is crucial in feed and food use of cottonseed. This also provides a reference for the gossypol derivatives using in male contraception and anticancer.