Inhibition of Cancer Angiogenesis Using Triptolide Nanoparticles

Triptolide Reduces MDA-MB-231 Cell Metastasis by Attenuating Epithelial-Mesenchymal Transition through the ROCK/PTEN/Akt Axis

Triple-negative breast cancer (TNBC) is a highly heterogeneous and invasive subtype of breast cancer. The prognosis of TNBC is poor because of its high distant metastasis rate. Triptolide is a type of diterpene trioxide natural compound with potential anti-tumor activities. This study explored the metastatic inhibitory effect of triptolide on MDA-MB-231 cells and its underlying mechanism. Triptolide suppressed cell proliferation and induced cell apoptosis in a time- and dose-dependent manner. Low doses of triptolide (0-8 nM) reduced the migration and invasion capabilities of MDA-MB-231 cells. Triptolide decreased ROCK1, p-Akt, N-cadherin, vimentin and MMP-9 expressions, but increased PTEN and E-cadherin expressions on protein and mRNA levels. Furthermore, the down-regulation of ROCK1 expression in MDA-MB-231 cells after being treated by triptolide could be rescued by ROCK1 specific inhibitor Y27632. Molecular docking showed that triptolide and Y27632 shared the same active center of ROCK1 protein. This article's findings taken together showed that ROCK1 is the primary target of triptolide, which can cause cell apoptosis and inhibit the epithelial-mesenchymal transition of MDA-MB-231 cells.

Current advances in nanoformulations of therapeutic agents targeting tumor microenvironment to overcome drug resistance

The tumor microenvironment (TME) plays a pivotal role in cancer development and progression. In this line, revealing the precise mechanisms of the TME and associated signaling pathways of tumor resistance could pave the road for cancer prevention and efficient treatment. The use of nanomedicine could be a step forward in overcoming the barriers in tumor-targeted therapy. Novel delivery systems benefit from enhanced permeability and retention effect, decreasing tumor resistance, reducing tumor hypoxia, and targeting tumor-associated factors, including immune cells, endothelial cells, and fibroblasts. Emerging evidence also indicates the engagement of multiple dysregulated mediators in the TME, such as matrix metalloproteinase, vascular endothelial growth factor, cytokines/chemokines, Wnt/β-catenin, Notch, Hedgehog, and related inflammatory and apoptotic pathways. Hence, investigating novel multitargeted agents using a novel delivery system could be a promising strategy for regulating TME and drug resistance. In recent years, small molecules from natural sources have shown favorable anticancer responses by targeting TME components. Nanoformulations of natural compounds are promising therapeutic agents in simultaneously targeting multiple dysregulated factors and mediators of TME, reducing tumor resistance mechanisms, overcoming interstitial fluid pressure and pericyte coverage, and involvement of basement membrane. The novel nanoformulations employ a vascular normalization strategy, stromal/matrix normalization, and stress alleviation mechanisms to exert higher efficacy and lower side effects. Accordingly, the nanoformulations of anticancer monoclonal antibodies and conventional chemotherapeutic agents also improved their efficacy and lessened the pharmacokinetic limitations. Additionally, the coadministration of nanoformulations of natural compounds along with conventional chemotherapeutic agents, monoclonal antibodies, and nanomedicine-based radiotherapy exhibits encouraging results. This critical review evaluates the current body of knowledge in targeting TME components by nanoformulation-based delivery systems of natural small molecules, monoclonal antibodies, conventional chemotherapeutic agents, and combination therapies in both preclinical and clinical settings. Current challenges, pitfalls, limitations, and future perspectives are also discussed.

Mechanisms of cancer cell death induction by triptolide

Drug resistance is a hot topic issue in cancer research and therapy. Although cancer therapy including radiotherapy and anti-cancer drugs can kill malignant cells within the tumor, cancer cells can develop a wide range of mechanisms to resist the toxic effects of anti-cancer agents. Cancer cells may provide some mechanisms to resist oxidative stress and escape from apoptosis and attack by the immune system. Furthermore, cancer cells may resist senescence, pyroptosis, ferroptosis, necroptosis, and autophagic cell death by modulating several critical genes. The development of these mechanisms leads to resistance to anti-cancer drugs and also radiotherapy. Resistance to therapy can increase mortality and reduce survival following cancer therapy. Thus, overcoming mechanisms of resistance to cell death in malignant cells can facilitate tumor elimination and increase the efficiency of anti-cancer therapy. Natural-derived molecules are intriguing agents that may be suggested to be used as an adjuvant in combination with other anticancer drugs or radiotherapy to sensitize cancer cells to therapy with at least side effects. This paper aims to review the potential of triptolide for inducing various types of cell death in cancer cells. We review the induction or resistance to different cell death mechanisms such as apoptosis, autophagic cell death, senescence, pyroptosis, ferroptosis, and necrosis following the administration of triptolide. We also review the safety and future perspectives for triptolide and its derivatives in experimental and human studies. The anticancer potential of triptolide and its derivatives may make them effective adjuvants for enhancing tumor suppression in combination with anticancer therapy.

AIP1 suppresses neovascularization by inhibiting the NOX4-induced NLRP3/NLRP6 imbalance in a murine corneal alkali burn model

Background

Apoptosis signal-regulating kinase 1-interacting protein 1 (AIP1) participates in inflammatory neovascularization induction. NADPH oxidase 4 (NOX4) produces reactive oxygen species (ROS), leading to an imbalance in nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) and NLR family pyrin domain containing 6 (NLRP6) expression. The mechanisms of AIP1, NOX4, ROS and inflammasomes in corneal neovascularization were studied herein.

Methods

C57BL/6 and AIP1-knockout mice were used in this study. The alkali burn procedure was performed on the right eye. Adenovirus encoding AIP1 plus green fluorescence protein (GFP) (Ad-AIP1-GFP) or GFP alone was injected into the right anterior chamber, GLX351322 was applied as a NOX4 inhibitor, and then corneal neovascularization was scored. The expression of related genes was measured by quantitative real-time polymerase chain reaction, western blotting and immunofluorescence staining. 2′,7′-Dichlorofluorescin diacetate staining was used to determine the ROS levels.

Results

The expression of AIP1 was decreased, while that of cleaved interleukin-1β (clv-IL-1β) and vascular endothelial growth factor A (VEGFa) was increased after alkali burn injury. NOX4 expression was increased, the imbalance in NLRP3/NLRP6 was exacerbated, and corneal neovascularization was increased significantly in AIP1-knockout mice compared with those in C57BL/6 mice after alkali burns. These effects were reversed by AIP1 overexpression. NLRP3/NLRP6 expression was imbalanced after alkali burns. GLX351322 reversed the imbalance in NLRP3/NLRP6 by reducing the ROS levels. This treatment also reduced the expression of clv-IL-1β and VEGFa, suppressing neovascularization.

Conclusions

AIP1 and NOX4 can regulate corneal inflammation and neovascularization after alkali burn injury. Based on the pathogenesis of corneal neovascularization, these findings are expected to provide new therapeutic strategies for patients.

Plain English summary

Corneal alkali burn injury is a common type of ocular injury that is difficult to treat in the clinic. The cornea is a clear and avascular tissue. Corneal neovascularization after alkali burn injury is a serious complication; it not only seriously affects the patient’s vision but also is the main reason for failed corneal transplantation. Corneal neovascularization affects approximately 1.4 million patients a year. We show for the first time that AIP1 and NOX4 can regulate corneal inflammation and neovascularization after alkali burns. The expression of AIP1 was decreased, while that of clv-IL-1β and VEGFa was increased after alkali burns. We tried to elucidate the specific molecular mechanisms by which AIP1 regulates corneal neovascularization. NOX4 activation was due to decreased AIP1 expression in murine corneas with alkali burns. NOX4 expression was increased, the imbalance in NLRP3/NLRP6 was exacerbated, and corneal neovascularization was increased significantly in AIP1-knockout mice compared with those in C57BL/6 mice after alkali burns. These effects were reversed by AIP1 overexpression. Additionally, NLRP3/NLRP6 expression was unbalanced, with NLRP3 activation and NLRP6 suppression in the corneal alkali burn murine model. Eye drops containing GLX351322, a NOX4 inhibitor, reversed the imbalance in NLRP3/NLRP6 by reducing ROS expression. This treatment also reduced the expression of clv-IL-1β and VEGFa, reducing neovascularization. Therefore, we provide new gene therapeutic strategies for patients. With the development of neovascularization therapy, we believe that in addition to corneal transplantation, new drug or gene therapies can achieve better results.

Delivery of triptolide: a combination of traditional Chinese medicine and nanomedicine

As a natural product with various biological activities, triptolide (TP) has been reported in anti-inflammatory, anti-tumor and anti-autoimmune studies. However, the narrow therapeutic window, poor water solubility, and fast metabolism limit its wide clinical application. To reduce its adverse effects and enhance its efficacy, research and design of targeted drug delivery systems (TDDS) based on nanomaterials is one of the most viable strategies at present. This review summarizes the reports and studies of TDDS combined with TP in recent years, including passive and active targeting of drug delivery systems, and specific delivery system strategies such as polymeric micelles, solid lipid nanoparticles, liposomes, and stimulus-responsive polymer nanoparticles. The reviewed literature presented herein indicates that TDDS is a multifunctional and efficient method for the delivery of TP. In addition, the advantages and disadvantages of TDDS are sorted out, aiming to provide reference for the combination of traditional Chinese medicine and advanced nano drug delivery systems (NDDS) in the future.

Triptolide delivery: Nanotechnology-based carrier systems to enhance efficacy and limit toxicity

Triptolide (TP) possesses a wide range of biological and pharmacological activities involved in the treatment of various diseases. However, widespread usages of TP raise the urgent issues of the severe toxicity, which hugely limits its further clinical application. The novel functional nanostructured delivery system, which is of great significance in enhancing the efficacy, reducing side effects and improving bioavailability, could improve the enrichment, penetration and controlled release of drugs in the lesion location. Over the past decades, considerable efforts have been dedicated to designing and developing a variety of TP delivery systems with the intention of alleviating the adverse toxicity effects and enhancing the bioavailability. In this review, we briefly summarized and discussed the recent functionalized nano-TP delivery systems for the momentous purpose of guiding further development of novel TP delivery systems and providing perspectives for future clinical applications.

Triptolide Suppresses Glomerular Mesangial Cell Proliferation in Diabetic Nephropathy Is Associated with Inhibition of PDK1/Akt/mTOR Pathway

Mesangial cell proliferation has been identified as a mainly contributing factor to glomerulosclerosis, which is typical of diabetic nephropathy. However, the specific mechanisms and therapies remain unclear. PDK1 is a critical regulator of cell proliferation, but the specific role of PDK1 in diabetic nephropathy has not been fully illuminated. In the current study, we demonstrated that triptolide (TP) ameliorated albuminuria in the high fat diet/STZ-induced diabetic rats. TP also suppressed the increased proliferating cell markers Ki-67 and PCNA in the kidney tissues. Our results of MTT and cell cycle analysis further confirmed that TP significantly inhibited mesangial cell proliferation, and the inhibition of PDK1/Akt/mTOR pathway might be the underlying mechanisms. In addition, we also found that the PDK1 activator (PS48) could reverse the cell proliferation inhibition role of TP. These data suggest that TP may be useful in prevention of diabetic glomerulosclerosis and that PDK1/Akt/mTOR pathway might be the underlying mechanism.

Triptolide prevents extracellular matrix accumulation in experimental diabetic kidney disease by targeting microRNA-137/Notch1 pathway

MicroRNAs (miRNAs) are involved in multiple biological functions via suppressing target genes. Triptolide is a monomeric compound isolated from a traditional Chinese herb, which exerts protective roles in many kinds of glomerular diseases. However, our understanding of the triptolide effect on miRNAome is still limited. In this study, we found that triptolide significantly decreased albuminuria and improved glomerulosclerosis in rats with diabetic kidney disease (DKD). And triptolide also inhibited extracellular matrix (ECM) protein accumulation and the notch1 pathway activation under diabetic conditions. MiR-137 was significantly decreased in the HG (high glucose)-treated HRMCs and in the kidney tissues of the diabetic rats, but was upregulated by triptolide. In addition, overexpression of miR-137 exerted similar effects to those of triptolide, while miR-137 inhibition aggravated ECM protein accumulation. Luciferase reporter assay results demonstrated that miR-137 directly targets Notch1. Furthermore, the miR-137-dependent effects were due to Notch1 suppression that in turn inhibited ECM protein expression, key mediators of glomerulosclerosis. Finally, downregulation of miR-137 reversed the ECM inhibition role of triptolide in HG cultured HRMCs. Taken together, these findings indicate that triptolide is a potential therapeutic option for DKD and that miR-137/Notch1 pathway play roles in the anti-glomerulosclerosis mechanism of triptolide.

Recent developments in nanomedicine for melanoma treatment

Melanoma is a most aggressive skin cancer with limited therapeutic options and its incidence is increasing rapidly in recent years. The discovery and application of new targeted therapy agents have shown significant benefits. However, adverse side-effects and resistance to chemotherapy remain formidable challenges in the clinical treatment of malignant melanoma. Nanotherapeutics offers an important prospect of overcoming these drawbacks. The anti-tumoral applications of nanomedicine are varied, including those in chemotherapy, RNA interference, photothermal therapy, and photodynamic therapy. Furthermore, nanomedicine allows delivery of the effector structures into the tumor site via passive or active targeting, thereby allowing increased therapeutic specificity and reduced side effects. In this review, we summarize the latest developments in the application of nanocarrier-mediated targeted drug delivery to melanoma and nanomedicine-related clinical trials in melanoma treatment. We also discuss existing problems and opportunities for future developments, providing direction and new thoughts for further studies.

Toward targeted therapy in chemotherapy-resistant pancreatic cancer with a smart triptolide nanomedicine

Chemoresistance is the major impediment for treating pancreatic cancer. Herb-derived compound triptolide (TP) can inhibit proliferation of chemo-resistant pancreatic cancer (CPC) cell lines through multiple mechanisms, which exhibited superior anticancer efficacy compared with gemcitabine. However, toxicity due to non-specific exposure to healthy tissues hindered its clinical translation. Herein we successfully achieved targeting CPC cells and avoiding exposure to healthy tissues for TP by nucleolin-specific aptamer (AS1411) mediated polymeric nanocarrier. We conjugated AS1411 aptamer to carboxy terminated poly(ethylene glycol)–block–poly(d, l-lactide) (HOOC-PEG-PDLLA), then prepared AS1411-PEG-PDLLA micelle loading TP (AS-PPT) through solid dispersion technique. AS-PPT showed more antitumor activity than TP and equivalent specific binding ability with gemcitabine-resistant human pancreatic cancer cell (MIA PaCa-2) to AS1411 aptamer in vitro. Furthermore, we studied the distribution of AS-PPT (Cy3-labed TP) at tissue and cellular levels using biophotonic imaging technology. The results showed AS1411 facilitated TP selectively accumulating in tumor tissues and targeting CPC cells. The lifetime of the MIA PaCa-2 cell-bearing mice administrated with AS-PPT was efficiently prolonged than that of the mice subjected to the clinical anticancer drug Gemzar^®in vivo. Such work provides a new strategy for overcoming the drug resistance of pancreatic cancer.

Catalytic Asymmetric Formal Total Synthesis of (-)-Triptophenolide and (+)-Triptolide

Catalytic asymmetric formal synthesis of (-)-Triptophenolide and (+)-Triptolide have been achieved. Key reaction involves Palladium catalyzed asymmetric conjugate addition of aryl boronic acid to 3-methyl cyclohexe-1-none to form quaternary carbon. Claisen rearrangement and subsequent aldol reaction furnished trans-decaline key intermediate, which assured a formal total synthesis of (-)-Triptophenolide and (+)-Triptolide.

Self-assembled Micelle Loading Cabazitaxel for therapy of Lung Cancer

Lung cancer is a leading cause of cancer deaths worldwide, chemotherapy has improved overall survival but remains limited at <12 months median overall survival. Cabazitaxel is hopeful to do the same in advanced lung cancer as well as in metastatic prostate cancer. However, its clinical application was restricted due to its high hydrophobicity and severe side effects. To overcome these problems, we developed self-assembled micelle loading cabazitaxel (CBZ-PM) for therapy of lung cancer. The CBZ-PM has high drug loading (10.52%) and encapsulation efficiency (99.30%) with particle size of 28.77 ± 0.52 nm and polydisperse index of 0.114 ± 0.012. The transmission electron microscope image presented its spherical and homogeneous appearance. In vitro release profile showed CBZ-PM has a sustained-release behavior. Furthermore, the result of cell proliferation assays proved that CBZ-PM could induce the Lewis lung carcinoma (LLC) cells death through G2/M arrest more effectively than free CBZ. In vivo anti-tumor activity of CBZ-PM was further studied in mice model of LLC. The tumor inhibitory rate of CBZ-PM was more than 50% and the survival time of LLC bearing mice was efficiently prolonged following administration of CBZ-PM. In addition, the immunohistochemical study showed that more apoptosis cells were detected in the tumor tissue of CBZ-PM group than that of the positive control group. All these indicated that CBZ-PM served as a potential anti-lung cancer agent.

Well-defined labile diselenide-centered poly(ε-caprolactone)-based micelles for activated intracellular drug release

Diselenide groups were introduced into aliphatic polyesters to develop a novel well-defined reduction-labile biodegradable diselenide-containing polymeric drug delivery system (mPEG–PCL–Se)₂.

Triptolide: A Critical Review on Antiangiogenesis in Cancer and Scope in Therapeutics

Triptolide (TPL) is a traditional Chinese medicine and an active component of a Chinese herbTripterygium wilfordiiF. (Celastraceae). Triptolide has been used to treat a variety of ailments, including rheumatoid arthritis, nephritic syndrome and Lupus erythematosus. It is also a strong antitumor agent. Several angiogenesis assays in numerous research studies have shown that triptolide is an angiogenesis inhibitor. Numerous preclinical studies have shown that TPL inhibits cell proliferation, induces apoptosis and limits tumor metastasis. TPL also has a synergistic action with other treatment methods whereby, it enhances the effects of other antitumor treatments, as studied in various cancer cell lines. This review summarizes the recent developments and discussion of antiangiogenic mechanisms of TPL in cancer, brief outline of its clinical trials and its future in cancer therapeutics.