Gambogic acid sensitizes resistant breast cancer cells to doxorubicin through inhibiting P-glycoprotein and suppressing survivin expression

Elevated level of neuroserpin is an indication for the resistance to gambogic acid-induced apoptosis and oxidative stress in triple-negative breast cancer cells

Background

The triple-negative breast cancer (TNBC) subtype, characterized by loss of HER2, estrogen, and progesterone receptors, displays aggressive phenotype and poor prognosis compared to other BC subtypes. Since the TNBC cells are devoid of receptors, endocrine therapy is an ineffective option for TNBC patients, necessitating canonical chemotherapy strategies to treat TNBC. It is crucial to use alternative and natural agents to support chemotherapy in TNBC.

Objectives

To clarify the molecular mechanism of the tumorigenic effects of gambogic acid (GA) on TNBC cells with different epithelial character since GA has a wide spectrum of anticancer activity for most cancer types.

Methods

We determined the cytotoxic dose of GA incubation of TNBC cells (MDA-MB-231 and BT-20 cells) for 24 h. We performed the MTT test and toluidine blue (TB) staining protocol for TNBC cells. We analyzed E-cadherin, N-cadherin, Bax, and neuroserpin mRNAs in both cells by qPCR. We evaluated apoptosis using DAPI staining and assessed the ROS using the 2',7'-dichlorofluorescin diacetate (DCFH-DA) method.

Results

We determined the IC50 concentrations of GA in MDA-MB-231 and BT-20 cells to be 315.8 nM and 441.8 nM, respectively. TB staining showed that BT-20 cells survive at excessive cytotoxic doses of GA, while most of the MDA-MB-231 cells were killed. Also, we found that BT-20 cells are more resistant to GA-induced apoptosis and oxidative stress than the MDA-MB-231 cells. qPCR results showed that GA upregulated neuroserpin, an oxidative stress-relieving factor in the BT-20 cells, but not in the MDA-MB-231 cells.

Conclusions

The elevated level of neuroserpin could be a predictive marker to determine the development of resistance to chemotherapeutic agents.

Optimization of amino acid-based poly(ester urea urethane) nanoparticles for the systemic delivery of gambogic acid for treating triple negative breast cancer

Amino acid-based poly(ester urea urethane) (AA-PEUU) is developed from amino acid-based ester urea building blocks interconnected with urethane blocks functionalized with poly(ethylene glycol) (PEG). Each functional block consists of structural design features that could impact the properties and performances of AA-PEUU as a nanocarrier for the systemic delivery of gambogic acid (GA). The multifunctional AA-PEUU structure provides broad tunability to enable the optimization of nanocarriers. The study investigates the structure-property relationship by fine-tuning the structure of AA-PEUU, including the amino acid type, hydrocarbons, the ratio of functional building blocks, and PEGylation, to identify the nanoparticle candidate with optimized delivery performances. Compared to free GA, the optimized PEUU nanocarrier improves the intratumoral distribution of GA by more than 9-fold, which significantly enhances the bioavailability and persistence of GA after intravenous administration. In an MDA-MB-231 xenograft mouse model, GA delivered by the optimized AA-PEUU nanocarrier exhibits significant tumor inhibition, apoptosis induction, and the anti-angiogenesis effect. The study demonstrates the potency of engineering AA-PEUU nanocarriers with tailor-designed structures and versatile tunability for the systemic delivery of therapeutics in the treatment of triple negative breast tumor.

Natural products as chemo-radiation therapy sensitizers in cancers

Cancer is a devastating disease and is the second leading cause of death worldwide. Surgery, chemotherapy (CT), and/or radiation therapy (RT) are the treatment of choice for most advanced tumors. Unfortunately, treatment failure due to intrinsic and acquired resistance to the current CT and RT is a significant challenge associated with poor patient prognosis. There is an urgent need to develop and identify agents that can sensitize tumor cells to chemo-radiation therapy (CRT) with minimal cytotoxicity to the healthy tissues. While many recent studies have identified the underlying molecular mechanisms and therapeutic targets for CRT failure, using small molecule inhibitors to chemo/radio sensitize tumors is associated with high toxicity and increased morbidity. Natural products have long been used as chemopreventive agents in many cancers. Combining many of these compounds with the standard chemotherapeutic agents or with RT has shown synergistic effects on cancer cell death and overall improvement in patient survival. Based on the available data, there is strong evidence that natural products have a robust therapeutic potential along with CRT and their well-known chemopreventive effects in many solid tumors. This review article reports updated literature on different natural products used as CT or RT sensitizers in many solid tumors. This is the first review discussing CT and RT sensitizers together in cancer.

In Situ Nanoparticle Self-Assembly for Combination Delivery of Therapeutics to Non-Small Cell Lung Cancer

Chemotherapy often experiences several challenges including severe systemic toxicity and adverse effects. The combination chemotherapy arose as an effective clinical practice aimed at reducing doses of drugs to achieve synergistic actions with low toxicity. Our recent efforts demonstrated a synergistic therapeutic benefit of gambogic acid (GA) and gemcitabine (Gem) against lung cancer. However, simultaneous delivery of these two drugs at the tumor site is highly challenging. Therefore, the development of an injectable formulation that can effectively deliver both hydrophobic (GA) and hydrophilic (Gem) drugs in one formulation is a clinically unmet need. Herein, this study reports an in situ human serum albumin (HSA)- and tannic acid (TA)-mediated complexed GA and Gem nanoparticles (G-G@HTA NPs). G-G@HTA NP formation was confirmed by the particle size, Fourier transform infrared spectroscopy, and ¹H NMR spectroscopy. The superior therapeutic activity of G-G@HTA NPs was demonstrated by multiple in vitro functional assays. Additionally, G-G@HTA NPs revealed an obvious and precise targeting of tumors in vivo. The promoted and more synergistic anti-tumor efficacy of G-G@HTA NPs was attained than that of combined treatments and single drug treatments. These events have resulted in no apparent systemic and organ toxicities. Together, this study suggests that in situ HSA-TA-based combinatorial treatment strategy is a suitable approach for application in lung cancer treatment.

The Establishment of Quantitatively Regulating Expression Cassette with sgRNA Targeting BIRC5 to Elucidate the Synergistic Pathway of Survivin with P-Glycoprotein in Cancer Multi-Drug Resistance

Quantitative analysis and regulating gene expression in cancer cells is an innovative method to study key genes in tumors, which conduces to analyze the biological function of the specific gene. In this study, we found the expression levels of Survivin protein (BIRC5) and P-glycoprotein (MDR1) in MCF-7/doxorubicin (DOX) cells (drug-resistant cells) were significantly higher than MCF-7 cells (wild-type cells). In order to explore the specific functions of BIRC5 gene in multi-drug resistance (MDR), a CRISPR/Cas9-mediated knocking-in tetracycline (Tet)-off regulatory system cell line was established, which enabled us to regulate the expression levels of Survivin quantitatively (clone 8 named MCF-7/Survivin was selected for further studies). Subsequently, the determination results of doxycycline-induced DOX efflux in MCF-7/Survivin cells implied that Survivin expression level was opposite to DOX accumulation in the cells. For example, when Survivin expression was down-regulated, DOX accumulation inside the MCF-7/Survivin cells was up-regulated, inducing strong apoptosis of cells (reversal index 118.07) by weakening the release of intracellular drug from MCF-7/Survivin cells. Also, down-regulation of Survivin resulted in reduced phosphorylation of PI3K, Akt, and mTOR in MCF-7/Survivin cells and significantly decreased P-gp expression. Previous studies had shown that PI3K/Akt/mTOR could regulate P-gp expression. Therefore, we speculated that Survivin might affect the expression of P-gp through PI3K/Akt/mTOR pathway. In summary, this quantitative method is not only valuable for studying the gene itself, but also can better analyze the biological phenomena related to it.

Triterpenoids with modified A-ring as modulators of P-gp-dependent drug-resistance in cancer cells

Semi-synthetic A-cycle modified triterpenic derivatives with A-cycle condensed with a heterocyclic fragment (compound 1) and fragmented A-ring (compound 2) were tested for cytotoxicity against several tumor cell cultures and doxorubicin (Dox)-resistant cell lines. The equal cytotoxicity of the tested compounds to the parental tumor cell lines (HBL-100, K562) and their resistant subclones (HBL-100/Dox, K562/i-S9) was revealed. The overexpression of ABCB1 (MDR1) gene and P-glycoprotein (P-gp) was confirmed for both resistant subclones of tumor cells. Compounds 1 and 2 were shown to inhibit the ABC-transporter gene expression (MDR1, MRP, MVP, and BCRP) and the transport of well-known P-gp substrate Rhodamine 123 from resistant cells. The docking of triterpenoids 1 and 2 into the drug binding site of P-gp revealed a similarity between the conformation of the tested triterpenoids and that of classical inhibitor verapamil, thus assuming these compounds to be more likely the inhibitors than the substrates of P-gp. Any tested triterpenic derivatives, when combined at non-toxic concentrations with doxorubicin, improved cytotoxic effect of the therapeutic drug against resistant subclones of tumor cells.

One step assembly of ginsenoside Rb1-based nanovehicles with fast cellular transport in photothermal-chemical combined cancer therapy

Nowadays, the research of photothermal-chemical co-therapy provides new ideas for the treatment of cancer. However, the harsh photothermal temperature hinders the clinical development of photothermal therapy. To ensure low-temperature photothermal-chemical combined therapy, a safe and feasible drug delivery system is highly desirable. Herein, through one step co-precipitation method, ginsenoside Rb1-based nanovehicles composed of the hydrophobic drug doxorubicin, the photochemical reagent Cypate and the heat shock protein inhibitor gambogic acid was prepared, resulting from the amphiphilicity and membrane permeability of Rb1. Encouragingly, this platform exhibited excellent biocompatibility and rapid cellular uptake, both of which led to significant and irreversible death of breast cancer cells under the trigger of short-term near-infrared light.

Xanthones as P-glycoprotein modulators and their impact on drug bioavailability

Introduction: P-glycoprotein (P-gp) is an important efflux pump responsible for the extruding of many endogenous and exogenous substances out of the cells. P-gp can be modulated by different molecules - including xanthone derivatives - to surpass the multidrug resistance (MDR) phenomenon through P-gp inhibition, or to serve as an antidotal strategy in intoxication scenarios through P-gp induction/activation.Areas covered: This review provides a perspective on P-gp modulators, with particular focus on xanthonic derivatives, highlighting their ability to modulate P-gp expression and/or activity, and the potential impact of these effects on the pharmacokinetics, pharmacodynamics and toxicity of P-gp substrates.Expert opinion: Xanthones, of natural or synthetic origin, are able to modulate P-gp, interfering with its protein synthesis or with its mechanism of action, by decreasing or increasing its efflux capacity. These modulatory effects make the xanthonic scaffold a promising source of new derivatives with therapeutic potential. However, the mechanisms beyond the xanthones-mediated P-gp modulation and the chemical characteristics that make them more potent P-gp inhibitors or inducers/activators are still understudied. Furthermore, a new window of opportunity exists in the neuropathologies field, where xanthonic derivatives with potential to modulate P-gp should be further explored to optimize the prevention/treatment of brain pathologies.

Gambogic Acid as a Candidate for Cancer Therapy: A Review

Gambogic acid (GA), a kind of dry resin secreted by the Garcinia hanburyi tree, is a natural active ingredient with various biological activities, such as anti-cancer, anti-inflammatory, antioxidant, anti-bacterial effects, etc. An increasing amount of evidence indicates that GA has obvious anti-cancer effects via various molecular mechanisms, including the induction of apoptosis, autophagy, cell cycle arrest and the inhibition of invasion, metastasis, angiogenesis. In order to improve the efficacy in cancer treatment, nanometer drug delivery systems have been employed to load GA and form micelles, nanoparticles, nanofibers, and so on. In this review, we aim to offer a summary of chemical structure and properties, anti-cancer activities, drug delivery systems and combination therapy of GA, which might provide a reference to promote the development and clinical application of GA.

Gambogic Acid Inhibits the Progression of Gastric Cancer via circRNA_ASAP2/miR-33a-5p/CDK7 Axis

Background

Gastric cancer (GC) is a major cancer-related mortality disease. Gambogic acid (GA) has been investigated to inhibit cancer progression. In the present study, the molecular mechanism of GA in regulating GC progression was studied.

Methods

The expression levels of circular RNA ASAP2 (circ_ASAP2), miR-33a-5p and cyclin-dependent kinases 7 (CDK7) were detected by quantitative real-time polymerase reaction (qRT-PCR). CDK7 protein level was evaluated by Western blot. Cell colony formation assay, 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, transwell assay and flow cytometry analysis were employed to reveal the functional effects among circ_ASAP2, miR-33a-5p and CDK7 on GA-induced GC progression. Mechanistically, the binding relationship between miR-33a-5p and circ_ASAP2 or CDK7 was predicted with starBase v3.0 online database and verified by dual-luciferase reporter assay. In vivo tumor formation assay was used to explain the impacts of GA treatment on GC growth in vivo.

Results

Circ_ASAP2 and CDK7 expression were downregulated in GA-induced GC cells compared with GC cells. MiR-33a-5p expression was upregulated in GA-induced GC cells relative to GC cells. The protein expression level of CDK7 was lower in GA-induced GC cells than that in GC cells. Further, circ_ASAP2 overexpression decreased GA-induced inhibition effects on cell proliferation, migration and invasion and GA-induced promotion effect on cell apoptosis in both AGS and HGC-27 cells, whereas this phenomenon was reversed by miR-33a-5p. In addition, circ_ASAP2 functioned as a sponge of miR-33a-5p and miR-33a-5p was associated with CDK7. Furthermore, GA treatment inhibited GC growth in vivo.

Conclusion

Circ_ASAP2 overexpression promoted cell proliferation, migration and invasion, whereas inhibited cell apoptosis by upregulating CDK7 expression through binding to miR-33a-5p in GA-induced GC cells. This study provided a theoretical basis in GC treatment with GA.

Cell-penetrating peptides in oncologic pharmacotherapy: A review

Cancer is the second leading cause of death in the world and its treatment is extremely challenging, mainly due to its complexity. Cell-Penetrating Peptides (CPPs) are peptides that can transport into the cell a wide variety of biologically active conjugates (or cargoes), and are, therefore, promising in the treatment and in the diagnosis of several types of cancer. Some notable examples are TAT and Penetratin, capable of penetrating the central nervous system (CNS) and, therefore, acting in cancers of this system, such as Glioblastoma Multiforme (GBM). These above-mentioned peptides, conjugated with traditional chemotherapeutic such as Doxorubicin (DOX) and Paclitaxel (PTX), have also been shown to induce apoptosis of breast and liver cancer cells, as well as in lung cancer cells, respectively. In other cancers, such as esophageal cancer, the attachment of Magainin 2 (MG2) to Bombesin (MG2B), another CPP, led to pronounced anticancer effects. Other examples are CopA3, that selectively decreased the viability of gastric cancer cells, and the CPP p28. Furthermore, in preclinical tests, the anti-tumor efficacy of this peptide was evaluated on human breast cancer, prostate cancer, ovarian cancer, and melanoma cells in vitro, leading to high expression of p53 and promoting cell cycle arrest. Despite the numerous in vitro and in vivo studies with promising results, and the increasing number of clinical trials using CPPs, few treatments reach the expected clinical efficacy. Usually, their clinical application is limited by its poor aqueous solubility, immunogenicity issues and dose-limiting toxicity. This review describes the most recent advances and innovations in the use of CPPs in several types of cancer, highlighting their crucial importance for various purposes, from therapeutic to diagnosis. Further clinical trials with these peptides are warranted to examine its effects on various types of cancer.

Anti-Tumor Xanthones from Garcinia nujiangensis Suppress Proliferation, and Induce Apoptosis via PARP, PI3K/AKT/mTOR, and MAPK/ERK Signaling Pathways in Human Ovarian Cancers Cells

Background

Ovarian cancer (OC) is a serious public health concern in the world. It is important to develop novel drugs to inhibit OC.

Purpose

This study investigated the isolation, elucidation, efficiency, molecular docking, and pharmaceutical mechanisms of xanthones isolated from Garcinia nujiangensis.

Methods

Xanthones were isolated, and purified by different chromatography, including silica gel, reversed-phase silica gel (ODS-C₁₈), and semipreparative HPLC, then identified by analysis of their spectral data. Three xanthones were estimated for their efficiency on the human OC cells HEY and ES-2. 2 was found to be the most potent cytotoxic xanthones of those tested. Further, its mechanisms of action were explored by molecular docking, cell apoptosis, and Western blotting analysis.

Results

Bioassay-guided fractionation of the fruits of Garcinia nujiangensis led to the separation of a new xanthone named nujiangexanthone G (1) and two known xanthones. Among these, isojacareubin (2) exhibited the most potent cytotoxic compound against the HEY and ES-2 cell lines. The analysis of Western blot suggested that 2 inhibited OC via regulating the PARP, PI3K/AKT/mTOR, and ERK/MAPK signal pathways in the HEY cell lines.

Conclusion

In conclusion, isojacareubin (2) might be a potential drug for the treatment of OC.

Dual drug-loaded nano-platform for targeted cancer therapy: toward clinical therapeutic efficacy of multifunctionality

Background

Poor targeting and penetration of chemotherapy drugs in solid tumors, and the development of resistance to chemotherapeutic agents are currently hindering the therapy of breast cancer; meanwhile, breast cancer metastasis is one of the leading causes of death in breast cancer patients. With the development of nanotechnology, nanomaterials have been widely used in tumor therapy.

Results

A multi-functional nano-platform containing gambogic acid (GA) and paclitaxel (PTX) was characterized by a small size, high encapsulation efficiency, slow release, long systemic circulation time in vivo, showed good targeting and penetrability to tumor tissues and tumor cells, and exhibited higher anti-tumor effect and lower systemic toxicity in BALB/c mice bearing 4T1 tumor. GA not only overcame the multidrug resistance of PTX by inhibiting P-glycoprotein (P-gp) activity in MCF-7/ADR cells, but also inhibited MDA-MB-231 cells migration and invasion, playing a crucial role in preventing and treating the lung metastasis of breast cancer caused by PTX; meanwhile, the synergistic anti-tumor effect of GA and PTX has also been verified in vitro and in vivo experiments.

Conclusion

Our data described the better recognition and penetration of tumor cells of R9dGR-modified versatile nanosystems containing GA and PTX, which exerted one stone three birds clinical therapeutic efficacy of multifunctionality.

Gambogic acid potentiates gemcitabine induced anticancer activity in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most frequent type of lung cancer accounting up to 80-85% of all lung cancer (LC) cases. Gemcitabine (Gem), a pyrimidine nucleoside antimetabolite, is widely used chemotherapy offering several months survival benefit in patients with NSCLC. The emergence of Gem resistance is a main clinical concern in cancer treatment and thus a continuous demand for development of new therapeutic strategies to improve its antitumor activity. Hence, we report an adjuvant therapeutic regimen based on natural compound, gambogic acid (GA) which has been shown to enhanced Gem induced inhibition of cancer cell growth, arrest cell cycle, and induce apoptosis by enhanced accumulation of Gem. The in vitro cell viability, clonogenicity, invasion, and migration assays demonstrated a significant higher therapeutic effect of Gem when it was combined with GA in A549 and H1299 cells. A better access of internalization of drug molecules achieved in rhodamine 123 assay when GA was used as adjuvant treatment. Further, GA and Gem combination significantly reduced tubular formation of HUVEC cells indicates lowering angiogenesis potential. Microarray and Western blot studies confirm that GA + Gem co-treatment strategy promotes cancer cell death by downregulating anti-apoptotic proteins, chemoresistance-associated proteins, and upregulation of apoptosis proteins. More importantly, a significant higher therapeutic benefit was noticed for GA and Gem combination in A549 xenograft mice model. Together, these results offer a rationale to evaluate the clinical translational possibility of GA as adjuvant therapy to overcome Gem resistance. This combination regimen can be a new therapeutic concept to eradicate this devastating disease.

Development of ROS-responsive amino acid-based poly(ester amide) nanoparticle for anticancer drug delivery

Reactive oxygen species (ROS) play an important role in cellular metabolism and many oxidative stress related diseases. Oxidative stress results from toxic effects of ROS and plays a critical role in the pathogenesis of a variety of diseases like cancers and many important biological processes. It is known that the unique feature of high intracellular ROS level in cancer cells can be considered as target and utilized as a useful cancer-related stimulus to mediate intracellular drug delivery. Therefore, biomaterials responsive to excess level of ROS are of great importance in biomedical applications. In this study, a novel ROS-responsive polymer based on L-methionine poly(ester amide) (Met-PEA-PEG) was designed, synthesized, characterized and self-assembled into nano-micellar-type nanoparticles (NP). The Met-PEA-PEG NP exhibited responsiveness to an oxidative environment. The size and morphology of the nanoparticle changed rapidly in the presence of H₂ O₂ . The Nile Red dye was loaded into the Met-PEA-PEG NP to demonstrate a H₂ O₂ concentration induced time-dependent release behavior. The Met-PEA-PEG NP was sensitive to high intracellular ROS level of PC3 prostate cancer cells. Furthermore, the Met-PEA-PEG NP was investigated as a carrier of a Chinese medicine-based anticancer component, gambogic acid (GA). Compared to free GA, the GA-loaded nanocomplex (GA-NP) showed enhanced cytotoxicity toward PC3 and HeLa cells. The GA-NP also induced a higher level of apoptosis and mitochondrial depolarization in PC3 cells than free GA. The Met-PEA-PEG NP improved the therapeutic effect of GA and may serve as a potential carrier for anticancer drug delivery.

The novel camptothecin derivative, CPT211, induces cell cycle arrest and apoptosis in models of human breast cancer

OBJECTIVE

Breast cancer is the second leading cause of cancer deaths in women worldwide and represents a highly aggressive nature with limited therapeutic options; thus, investigating novel therapeutic agents for breast cancer is much needed. In this study, we investigated the anticancer effects of a novel camptothecin derivative, CPT211, against human breast cancer.

METHODS

We used hormone receptor-positive MCF-7, triple-negative (TNBC) MDA-MB-231, and HER2-positive BT-474 human breast cancer cells to examine cytotoxicity of CPT211. We measured cell viability with dose dependence of CPT211 treatments by an MTT assay and investigated the potential underlying mechanism through flow cytometric and Western blot methods. Furthermore, we evaluated the efficacy of the treatment combination of CPT211 and doxorubicin in a mouse model bearing MDA-MB-231 xenografts.

RESULTS

CPT211 treatment led to dose-dependent decreases in cell viability of both MCF-7 and MDA-MB-231 cells, but not BT-474 cells. Analysis of the underlying molecular mechanism revealed that CPT211 activated p53-mediated apoptosis, by triggering intrinsic and extrinsic apoptotic pathways in MCF-7 cells. Additionally, CPT211 induced apoptosis and cell cycle arrest of MDA-MB-231 cells by activating Fas/FADD/caspase-8 signaling, suggesting that CPT211-mediated MDA-MB-231 cell apoptosis may occur through an extrinsic apoptosis pathway. CPT211 treatment with doxorubicin in mice bearing MDA-MB-231 xenografts was shown to enhance caspase-8 and caspase-7 activation, resulting in significant inhibition of tumor growth.

CONCLUSIONS

These results indicate that Fas/FADD/caspase-8 activation plays an important role in CPT211-mediated tumor growth suppression in TNBC, and the novel camptothecin derivative, CPT211, can be exploited for specific targeted therapies and potentially improve approaches to combination treatments for human breast cancer.

Gambogic acid: A shining natural compound to nanomedicine for cancer therapeutics

The United States Food and Drug Administration has permitted number of therapeutic agents for cancer treatment. Most of them are expensive and have some degree of systemic toxicity which makes overbearing in clinical settings. Although advanced research continuously applied in cancer therapeutics, but drug resistance, metastasis, and recurrence remain unanswerable. These accounts to an urgent clinical need to discover natural compounds with precisely safe and highly efficient for the cancer prevention and cancer therapy. Gambogic acid (GA) is the principle bioactive and caged xanthone component, a brownish gamboge resin secreted from the of Garcinia hanburyi tree. This molecule showed a spectrum of biological and clinical benefits against various cancers. In this review, we document distinct biological characteristics of GA as a novel anti-cancer agent. This review also delineates specific molecular mechanism(s) of GA that are involved in anti-cancer, anti-metastasis, anti-angiogenesis, and chemo-/radiation sensitizer activities. Furthermore, recent evidence, development, and implementation of various nanoformulations of gambogic acid (nanomedicine) have been described.

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.

Gambogic acid suppresses colon cancer cell activity in vitro

The aim of the present study was to elucidate the underlying mechanism of antitumor activity of gambogic acid (GA) in colon cancer. Human colon cancer SW620 cells were divided into five treatment groups, including no-treatment control (NC), low dose GA (10 µg/ml), medium dose GA (50 µg/ml), high dose GA (100 µg/ml) and 5-fluorouracil (10 µg/ml). Differences in cell proliferation, apoptosis and cell cycle, invasion, and migration were measured between groups using MTT, flow cytometry, transwell and wound-healing assays, respectively. Western blotting was used to analyze relative protein expression levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), P21, and matrix metalloprotease (MMP)-2 and −9 between groups. Compared with the NC group, GA (low, middle and high) inhibited SW620 cell proliferation, invasion and migration (all P<0.05). Furthermore, there were significant differences in proliferation, invasion and migration between groups administered with different doses of GA (all P<0.05). Compared with the NC group, the expression levels of PI3K, AKT, phosphorylated-AKT, P21 and MMP-2 and −9 were significantly altered in a dose dependent manner following treatment with GA (all P<0.05). The results of the current study indicated that GA suppressed proliferation and dispersion of human colon cancer cells in a dose-dependent manner, possibly through a PI3K/AKT/P21/MMP-2/9-dependent pathway.

Gambogic acid increases the sensitivity to paclitaxel in drug‑resistant triple‑negative breast cancer via the SHH signaling pathway

Paclitaxel is the most frequently used therapy regimen for triple-negative breast cancer (TNBC). However, chemoresistance frequently occurs, leading to enhanced failure rates of chemotherapy in TNBC; therefore, novel biological therapies are urgently needed. Gambogic acid (GA) has potent anticancer effects and inhibits tumor growth in several types of human cancer. However, the effects of GA on paclitaxel-resistant TNBC remain unknown. In the present study, the Cell Counting Kit-8 assay was used to examine the effect of GA and/or paclitaxel on the viability of TNBC cells; flow cytometry was used to examine the effects of GA on cell apoptosis; and western blotting and reverse transcription-quantitative PCR were used to determine the effects of GA on the expression of sonic hedgehog (SHH) signaling pathway target genes. The present results indicated that GA significantly inhibited the viability and enhanced the rate of apoptosis in paclitaxel-resistant MDA-MB-231 cells via activating the SHH signaling pathway. In vivo experiments confirmed that GA treatment enhanced the sensitivity of MDA-MB-231 cells to paclitaxel via the SHH signaling pathway. In conclusion, the combination of GA with paclitaxel may increase the antitumor effects on paclitaxel-resistant TNBC via downregulating the SHH signaling pathway.

Dimeric c(RGD) peptide conjugated nanostructured lipid carriers for efficient delivery of Gambogic acid to breast cancer

Background and purpose: Gambogic acid (GA) is a natural compound that exhibited a promising multi-target antitumor activity against several types of cancer. However, the clinical application of this drug is limited due to its poor solubility and low tumor cell-specific delivery. In this study, the monomeric and dimeric Cyclo (Arg-Gly-Asp) c(RGD) tumor targeting peptides (c(RGDfK) and E-[c(RGDfK)2]) were used to modify GA loaded nanostructured lipid carriers (NLC) to reduce the limitations associated with GA and improve its antitumor activity. Methods: GA-NLC was prepared by emulsification and solvent evaporation methods and the surface of the NLC was conjugated with the c(RGD) peptides via an amide bond. The formulations were characterized for particle size, morphology and zeta potential, encapsulation efficiency and drug loading. The in-vitro cytotoxicity and cell uptake studies were conducted using 4T1 cell. Furthermore, the in-vivo antitumor activity and bio-distribution study were performed on female BALB/c nude mice. Results: The c(RGD) peptides modified GA-NLC was successfully prepared with the particles size about 20 nm. The HPLC analysis, FT-IR and 1H-NMR spectra confirmed the successful conjugation of the peptides with the NLC. The in-vitro cytotoxicity study on 4T1 cells revealed that c(RGD) peptides modified GA-NLCs showed significantly higher cytotoxicity at 0.25 and 0.5 µg/mL as compared to unmodified GA-NLC. Furthermore, the cell uptake study demonstrated that better accumulation of E-[c(RGDfK)2] peptides modified NLC in 4T1 cell after 12 h incubation. Moreover, the in-vivo study showed that c(RGD)s functionalized GA-NLC exhibited better accumulation in tumor tissue and tumor growth inhibition. In contrast to the monomeric c(RGD) peptide, the dimeric c(RGD) peptide (E-[c(RGDfK)2]) conjugated GA-NLC showed the improved antitumor activity and tumor targeting ability of GA-NLC. Conclusion: These data provide further support for the potential clinical applications of E-[c(RGDfK)2]-GA-NLC in breast cancer therapy.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Hyaluronic acid-decorated redox-sensitive chitosan micelles for tumor-specific intracellular delivery of gambogic acid

Introduction: Herein, a hyaluronic acid (HA)-coated redox-sensitive chitosan-based nanoparticle, HA(HECS-ss-OA)/GA, was successfully developed for tumor-specific intracellular rapid delivery of gambogic acid (GA).

Materials and methods: The redox-sensitive polymer, HECS-ss-OA, was prepared through a well-controlled synthesis procedure with a satisfactory reproducibility and stable resulted surface properties of the assembled cationic micelles. GA was solubilized into the inner core of HECS-ss-OA micelles, while HA was employed to coat outside HECS-ss-OA/GA for CD44-mediated active targeting along with protection from cation-associated in vivo defects. The desirable redox-sensitivity of HA(HECS-ss-OA)/GA was demonstrated by morphology and particle size changes alongside in vitro drug release of nanoparticles in different simulated reducing environments.

Results: The results of flow cytometry and confocal microscopy confirmed the HA-receptor mediated cellular uptake and burst drug release in highly reducing cytosol of HA(HECS-ss-OA)/GA. Consequently, HA(HECS-ss-OA)/GA showed the highest apoptosis induction and cytotoxicity over the non-sensitive (HA(HECS-cc-OA)/GA) and HA un-coated (HECS-ss-OA/GA) controls against A549 NSCLC model both in vitro and in vivo. Furthermore, a diminished systemic cytotoxicity was observed in HA(HECS-ss-OA)/GA treated mice compared with those treated by HA un-coated cationic ones and GA solution.

Potential Anticancer Agents Characterized from Selected Tropical Plants

Higher plants are well known for their value in affording clinically useful anticancer agents, with such compounds acting against cancer cells by a range of mechanisms of action. There remains a strong interest in the discovery and development of plant secondary metabolites as additional cancer chemotherapeutic lead compounds. In the present review, progress on the discovery of plant-derived compounds of the biflavonoid, lignan, sesquiterpene, steroid, and xanthone structural types is presented. Several potential anticancer leads of these types have been characterized from tropical plants collected in three countries as part of our ongoing collaborative multi-institutional project. Preliminary structure-activity relationships and work on in vivo testing and cellular mechanisms of action are also discussed. In addition, the relevant work reported by other groups on the same compound classes is included herein.

Combination of shikonin with paclitaxel overcomes multidrug resistance in human ovarian carcinoma cells in a P-gp-independent manner through enhanced ROS generation

Background

Shikonin (SKN), a naphthoquinone compound, is isolated from Chinese herbal medicine Lithospermum root and has been studied as an anticancer drug candidate in human tumor models. This study is designed to investigate whether SKN can sensitize the therapeutic effect of paclitaxel (PTX) in drug-resistant human ovarian carcinoma cells.

Methods

Human ovarian carcinoma A2780 cell along with the paired PTX-resistant A2780/PTX cells were used. The effects of SKN, PTX or their combination on cell viability were conducted using Sulforhodamine B assay. P-glycoprotein (P-gp) expression was analyzed by flow cytometry after staining with P-gp-FITC anti-body. P-gp activity was determined by a fluorometric MDR assay kit or a rhodamine 123-based efflux assay, respectively. Apoptosis was evaluated by flow cytometry after Annexin V-FITC/PI co-staining. The effect of SKN, PTX or their combination on reactive oxygen species (ROS) generation and expression of pyruvate kinase M2 (PKM2) were investigated using flow cytometry or western blotting, respectively. PKM2 activity was detected by a Pyruvate Kinase Assay Kit.

Results

SKN/PTX co-treatment led to synergistically enhanced cytotoxicity and apoptosis in PTX-resistant ovarian cancer cells, indicating the circumvention of multidrug resistance (MDR) of PTX by SKN. Further study indicated that the MDR reversal effect of SKN was independent of inhibiting activity of the efflux transporter P-gp. Notably, SKN/PTX significantly increased the generation of intracellular ROS in A2780/PTX cells, and scavenging intracellular ROS blocked the sensitizing effects of SKN in PTX-induced cytotoxicity and apoptosis in A2780/PTX cells, but not in A2780 cells. Furthermore, SKN/PTX-induced downregulation of PKM2 (a key enzyme in glycolysis) and the suppression of its activity were inhibited by a ROS scavenger N-acetyl cysteine (NAC), suggesting that the synergy of the SKN/PTX combination may be not rely on PKM2 suppression.

Conclusions

These results reveal a P-gp-independent mechanism through ROS generation for the SKN/PTX combination to overcome MDR in ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s13020-019-0231-3) contains supplementary material, which is available to authorized users.

Gambogic acid reverses oxaliplatin resistance in colorectal cancer by increasing intracellular platinum levels

Resistance to oxaliplatin (L-OHP) is a major obstacle to successful chemotherapy in colorectal cancer (CRC). In the present study, the ability of gambogic acid (GA) to reverse L-OHP resistance in CRC LoVo cells was investigated. L-OHP-resistant LoVo/L-OHP cells were established by exposing them to increasing concentrations of L-OHP. GA-reversed L-OHP-sensitive LoVo/L-OHP/GA cells were established by exposure to 0.5 µmol/l GA for 2 weeks. A Cell Counting Kit-8 assay was used to assess levels of proliferation. Flow cytometry was applied to detect apoptosis rates. Transwell assays were used to analyse invasion. Inductively coupled plasma mass spectrometry was used to determine intracellular platinum (Pt) content. Western blot analysis was used to reveal the protein levels of Human copper transporter 1 (hCTR1), Copper-transporting p-type adenosine triphosphatases 1 (ATP7A) and Copper-transporting p-type adenosine triphosphatases 2 (ATP7B). LoVo/L-OHP and LoVo/L-OHP/GA cell lines were successfully established, and it was identified that L-OHP inhibited the proliferation of LoVo, LoVo/L-OHP and LoVo/L-OHP/GA cells in a dose-dependent manner. Compared with the parent LoVo cells, the anti-apoptosis and invasion properties of LoVo/L-OHP cells were enhanced, and were reversed by GA treatment. Intracellular Pt content was highest in the LoVo cells, followed by LoVo/L-OHP/GA cells, and then lowest in the LoVo/L-OHP cells. Downregulated hCTP1 and upregulated ATP7A and ATP7B were associated with L-OHP resistance, and GA reversed the resistance by increasing levels of hCTR1 and decreasing levels of ATP7A and ATP7B. In conclusion, GA has the potential ability to reverse L-OHP resistance in CRC cells by increasing intracellular Pt content, which it achieves by increasing hCTR1 levels and decreasing ATP7A and ATP7B levels. GA may represent a promising treatment agent for L-OHP resistance.

Bromodomain‑containing protein 4 is critical for the antiproliferative and pro‑apoptotic effects of gambogic acid in anaplastic thyroid cancer

Gambogic acid (GA) has been widely used as an anticancer drug for different tumors, including thyroid cancer. However, the potential function and molecular mechanisms of GA in anaplastic thyroid cancer (ATC) has not been illustrated thus far. The aim of the present study was to demonstrate the antitumor effects of GA on ATC cells and investigate its underlying molecular mechanisms. The results revealed that GA significantly decreased the viability and proliferation, as well as induced cell apoptosis in ATC cell lines. Next, it was demonstrated that GA decreased the expression of bromodomain‑containing protein 4 (BRD4), which has been reported to function as an oncogene in various types of cancer. BRD4 expression was significantly higher in ATC tissues compared with that in adjacent normal thyroid tissues. In addition, BRD4 silencing significantly repressed the cell viability and proliferation, and increased the cell apoptotic rate in vitro, while it also delayed the tumor growth in vivo. Notably, ectopic BRD4 expression significantly weakened the biological effects of GA on ATC cells in vitro and in vivo, which suggested that GA served its anticancer functions partially via downregulating BRD4. In conclusion, BRD4, functioning as an oncogene in ATC, is important for the antiproliferative and pro‑apoptotic effects of GA.

Effect of resveratrol on doxorubicin resistance in breast neoplasm cells by modulating PI3K/Akt signaling pathway

In the study, we probed into the effect of Resveratrol (RES) on Doxorubicin (DOX)-resistant breast neoplasm cell line MCF-7/DOX as well as the mechanism of RES underlying the DOX-resistant breast cancer. CCK-8 assay was utilized to assess the survival rates and sensitivity of breast neoplasm cell lines MCF-7 or MDA-MB-231 to DOX and RES. DOX-resistant MCF-7 cell line was successfully cultivated with DOX dose increasing and was named MCF-7/DOX. Afterwards, wound healing and Transwell assays were performed to measure the migration and invasion capabilities of MCF-7/DOX cells, while cell propagation and apoptosis were determined by colony formation assay and flow cytometry analysis. Both western blotting and immunohistochemistry were conducted to examine the expression of proteins involved in PI3K/Akt signaling pathway. Nude mice xenograft model was constructed to further verify the effects of DOX and RES on breast neoplasm in vivo. RES restored DOX sensitivity in MCF-7/DOX cells, inhibiting biological functions of MCF-7/DOX cells and promoting cell apoptosis in vitro and impeding tumor growth in vivo. It was revealed by the mechanistic studies that MCF-7/DOX cells could regain the drug sensibility with RES treatment through inactivating the PI3K/Akt signal transduction pathway. RES could reverse DOX resistance in breast neoplasm cells and inhibited DOX-resistant breast cancer cell propagation and metastasis and facilitated cell apoptosis by modulating PI3K/Akt signaling pathway. © 2018 IUBMB Life, 70(6):491-500, 2018.

Cell-penetrating peptide conjugates of gambogic acid enhance the antitumor effect on human bladder cancer EJ cells through ROS-mediated apoptosis

Background

Gambogic acid (GA) is the main active ingredient of resin gamboges and possesses anti-cancer activity toward various human cancer cells. However, clinical application of GA has been limited by its poor aqueous solubility and dose-limiting toxicities. Cell-penetrating peptides (CPPs) are widely used to deliver anti-cancer drugs into cancer cells and to enhance the water solubility of drugs.

Purpose

The object of this study was to synthesize peptide-drug conjugates in which the cell-penetrating peptide TAT (trans-activator of transcription) was conjugated to GA and evaluated the anti-cancer activity of this GA-CPP conjugate (GA-TAT) in EJ bladder cancer cells.

Methods

GA is built onto the TAT, and the GA-TAT conjugates are cleaved from the solid support and purified via HPLC. The equilibrium solubility of GA-TAT was measured using the shake-flask method. The effects of GA-TAT on EJ cell viability and proliferation were determined by MTT assay, Edu assay and colony formation assay, respectively. After treated with 1.0 μM GA-TAT for 24 h, the apoptosis rate of EJ cells were detected by Acridine orange/ethidium bromide (AO/EB) assay and flow cytometry assay. The proteins of caspase-3 (processing), caspase-9 (processing), Bcl-2 and Bax were analyzed by Western blotting, and the intracellular reactive oxygen species (ROS) production was evaluated by a reactive oxygen species assay.

Results

In contrast to free GA, the solubility of GA-TAT in water was significantly improved. Meanwhile, GA-TAT significantly increased EJ cellular uptake, toxicity and apoptosis. Mechanistic analysis revealed that GA-TAT enhanced the anti-cancer effect of GA against EJ cells through ROS-mediated apoptosis. The results were demonstrated that GA-TAT increased the ROS level in EJ cells, and N-acetyl-L-cysteine (NAC; a well-known ROS scavenger) inhibited GA-TAT-induced ROS generation and apoptosis. Additionally, GA-TAT activated caspase-3 and caspase-9 and down-regulated the Bcl-2/Bax ratio, but these effects were largely rescued by NAC.

Conclusion

GA-TAT has outstanding potential for promoting tumor apoptosis and exhibits promise for use in bladder cancer therapy.

Co-delivery of gambogic acid and TRAIL plasmid by hyaluronic acid grafted PEI-PLGA nanoparticles for the treatment of triple negative breast cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-based combination therapy and gene therapy are new strategies to potentially overcome the limitations of TRAIL, however, the lack of efficient and low toxic vectors remains the major obstacle. In this study, we developed a hyaluronic acid (HA)-decorated polyethylenimine-poly(d,l-lactide-co-glycolide) (PEI-PLGA) nanoparticle (NP) system for targeted co-delivery of TRAIL plasmid (pTRAIL) and gambogic acid (GA) in triple-negative breast cancer (TNBC) therapy. GA was encapsulated into the core of the PEI-PLGA NPs while pTRAIL was adsorbed onto the positive NP surface via charge adsorption. The coating of HA on PEI-PLGA NPs functions as a targeting ligand by binding to CD44 receptor of TNBC cells and a shell to neutralize the excess positive charge of inner NPs. The resultant pTRAIL and GA co-loaded HA-coated PEI-PLGA NPs exhibited spherical shape (121.5 nm) and could promote the internalization of loaded cargoes into TNBC cells through the CD44-dependent endocytic pathway. The dual drug-loaded NPs significantly augmented apoptotic cell death in vitro and inhibited TNBC tumor growth in vivo. This multifunctional NP system efficiently co-delivered GA and pTRAIL, thus representing a promising strategy to treat TNBC and bringing forth a platform strategy for co-delivery of therapeutic DNA and chemotherapeutic agents in combinatorial TNBC therapy.

Therapeutic potential of gambogic acid, a caged xanthone, to target cancer

Natural compounds have enormous biological and clinical activity against dreadful diseases such as cancer, as well as cardiovascular and neurodegenerative disorders. In spite of the widespread research carried out in the field of cancer therapeutics, cancer is one of the most prevalent diseases with no perfect treatment till date. Adverse side effects and the development of chemoresistance are the imperative limiting factors associated with conventional chemotherapeutics. For this reason, there is an urgent need to find compounds that are highly safe and efficacious for the prevention and treatment of cancer. Gambogic acid (GA) is a xanthone structure extracted from the dry, brownish gamboge resin secreted from the Garcinia hanburyi tree in Southeast Asia and has inherent anti-cancer properties. In this review, the molecular mechanisms underlying the targets of GA that are liable for its effective anti-cancer activity are discussed that reveal the potential of GA as a pertinent candidate that can be appropriately developed and designed into a capable anti-cancer drug.

Inclusion complex from cyclodextrin-grafted hyaluronic acid and pseudo protein as biodegradable nano-delivery vehicle for gambogic acid

β-Cyclodextrin can form inclusion complex with a series of guest molecules including phenyl moieties, and has gained considerable popularity in the study of supramolecular nanostructure. In this study, a biodegradable nanocomplex (HA(CD)-4Phe4 nanocomplex) was developed from β-cyclodextrin grafted hyaluronic acid (HA) and phenylalanine based poly(ester amide). The phenylalanine based poly(ester amide) is a biodegradable pseudo protein which provides the encapsulation capacity for gambogic acid (GA), a naturally-derived chemotherapeutic which has been effectively employed to treat multidrug resistant tumor. The therapeutic potency of free GA is limited due to its poor solubility in water and the lack of tumor-selective toxicity. The nanocomplex carrier enhanced the solubility and availability of GA in aqueous media, and the HA component enabled the targeted delivery to tumor cells with overexpression of CD44 receptors. In the presence of hyaluronidase, the release of GA from the nanocomplex was significantly accelerated, due to the enzymatic biodegradation of the carrier. Compared to free GA, GA-loaded nanocomplex exhibited improved cytotoxicity in MDA-MB-435/MDR multidrug resistant melanoma cells, and induced enhanced level of apoptosis and mitochondrial depolarization, at low concentration of GA (1-2µM). The nanocomplex enhanced the therapeutic potency of GA, especially when diluted in physiological environment. In addition, suppressed matrix metalloproteinase activity was also detected in MDA-MB-435/MDR cells treated by GA-loaded nanocomplex, which demonstrated its potency in the inhibition of tumor metastasis. The in vitro data suggested that HA(CD)-4Phe4 nanocomplex could provide a promising alternative in the treatment of multidrug resistant tumor cells.

STATEMENT OF SIGNIFICANCE

Gambogic acid (GA), naturally derived from genus Garcinia trees, exhibited significant cytotoxic activity against multiple types of tumors with resistance to traditional chemotherapeutics. Unfortunately, the poor solubility of GA in conventional pharmaceutical solvents and non-targeted distribution in normal tissues greatly limited its therapeutic potency. To overcome the challenges, we develop a nanoplatform from the supramolecular assembly of β-cyclodextrin grafted hyaluronic acid (HA) and phenylalanine based pseudo protein. The pseudo protein in the nanocomplex provided the hydrophobic interaction and loading capacity for GA, while the HA component targeted the overexpressed CD44 receptor and improved the selective endocytosis in multidrug resistant melanoma cells. The supramolecular nanocomplex provide a promising platform for the delivery of hydrophobic chemotherapeutics to improve the bioavailability and efficiency.

Polymeric mixed micelles loaded mitoxantrone for overcoming multidrug resistance in breast cancer via photodynamic therapy

Mitoxantrone (MIT) is an anticancer agent with photosensitive properties that is commonly used in various cancers. Multidrug resistance (MDR) effect has been an obstacle to using MIT for cancer therapy. Photochemical internalization, on account of photodynamic therapy, has been applied to improve the therapeutic effect of cancers with MDR effect. In this study, an MIT-poly(ε-caprolactone)-pluronic F68-poly(ε-caprolactone)/poly(d,l-lactide-co-glycolide)–poly(ethylene glycol)–poly(d,l-lactide-co-glycolide) (MIT-PFP/PPP) mixed micelles system was applied to reverse the effect of MDR in MCF-7/ADR cells via photochemical reaction when exposed to near-infrared light. MIT-PFP/PPP mixed micelles showed effective interaction with near-infrared light at the wavelength of 660 nm and exerted great cytotoxicity in MCF-7/ADR cells with irradiation. Furthermore, MIT-PFP/PPP mixed micelles could improve reactive oxygen species (ROS) levels, decrease P-glycoprotein activity, and increase the cellular uptake of drugs with improved intracellular drug concentrations, which induced cell apoptosis in MCF-7/ADR cells under irradiation, despite MDR effect, as indicated by the increased level of cleaved poly ADP-ribose polymerase. These findings suggested that MIT-PFP/PPP mixed micelles may become a promising strategy to effectively reverse the MDR effect via photodynamic therapy in breast cancer.

Schisandrin B reverses doxorubicin resistance through inhibiting P-glycoprotein and promoting proteasome-mediated degradation of survivin

Acquired drug resistance poses a great challenge in cancer therapy. Drug efflux and anti-apoptotic processes are the most two common mechanisms that confer cancer drug resistance. In this study, we found that Schisandrin B (Sch B), one of the major dibenzocyclooctadiene derivatives extracted from Chinese herbal medicine Schisandrae Chinensis Fructus, could significantly enhance the sensitivity of doxorubicin (DOX)-resistant breast cancer and ovarian cancer cells to DOX. Our results showed that Sch B increased the intracellular accumulation of DOX through inhibiting expression and activity of P-glycoprotein (P-gp). Meanwhile, Sch B could markedly downregulate the expression of anti-apoptotic protein survivin. Overexpression of survivin attenuated the sensitizing effects of Sch B, while silencing of survivin enhanced Sch B-mediated sensitizing effects. Furthermore, Sch B preferentially promoted chymotryptic activity of the proteasome in a concentration-dependent manner, and the proteasome inhibitor MG-132 prevented Sch B-induced survivin downregulation. Taken together, our findings suggest that Sch B could be a potential candidate for combating drug resistant cancer via modulating two key factors that responsible for cancer resistance.

Dihydromyricetin Induces Apoptosis and Reverses Drug Resistance in Ovarian Cancer Cells by p53-mediated Downregulation of Survivin

Ovarian cancer is one of the leading causes of death in gynecological malignancies, and the resistance to chemotherapeutic agents remains a major challenge to successful ovarian cancer chemotherapy. Dihydromyricetin (DHM), a natural flavonoid derived from Ampeopsis Grossdentata, has been widely applied in food industry and medicine for a long time. However, little is known about the effects of DHM on ovarian cancer and the underlying mechanisms. In this study, we demonstrated that DHM could effectively inhibit the proliferation of ovarian cancer cells and induce cell apoptosis. Survivin, an inhibitor of apoptosis (IAPs) family member, exhibited a decreased expression level after DHM treatment, which may be attributed to the activation of p53. Moreover, DHM markedly sensitized paclitaxel (PTX) and doxorubicin (DOX) resistant ovarian cancer cells to PTX and DOX by inhibiting survivin expression. Collectively, our findings highlight a previously undiscovered effect of DHM, which induces apoptosis and reverses multi-drug resistance against ovarian cancer cells through downregulation of survivin.

Combined effects of furanodiene and doxorubicin on the migration and invasion of MDA-MB-231 breast cancer cells in vitro

Furanodiene is one of the major bioactive components isolated from the natural product of the plant, Curcuma wenyujin Y.H. Chen et C. Ling. Furanodiene has been found to exert anticancer effects in various types of cancer cell lines, as well as exhibit antimetastatic activities. However, the antimetastatic capacity of furanodiene in combination with the common chemotherapy drug doxorubicin has not been investigated. We found that doxorubicin at a non-toxic concentration induced cell migration and cell invasion in highly metastatic breast cancer cells. Combinational treatments with furanodiene and doxorubicin blocked the invasion and migration of MDA-MB-231 breast cancer cells in vitro. We also clarified the effects of the combination on the signaling pathways involved in migration, invasion, and cytoskeletal organization. When combined with doxorubicin, furanodiene downregulated the expression of integrin αV and β-catenin and inhibited the phosphorylation of paxillin, Src, focal adhesion kinase (FAK), p85, and Akt. Moreover, combinational treatments also resulted in a decrease in matrix metalloproteinase-9 (MMP-9). Further study demonstrated that the co-treatments with furanodiene did not significantly alter the effects of doxorubicin on the tubulin cytoskeleton, represented by no influence on the expression levels of RhoA, Cdc42, N-WASP, and α/β tubulin. These observations indicate that furanodiene is a potential agent that may be utilized to improve the anticancer efficacy of doxorubicin and overcome the risk of chemotherapy in highly metastatic breast cancer.

Gambogic acid potentiates the chemosensitivity of colorectal cancer cells to 5-fluorouracil by inhibiting proliferation and inducing apoptosis

Chemotherapy using 5-fluorouracil (5-FU) for colorectal cancer (CRC) has low specificity and response rates, leading to severe side effects. Gambogic acid (GA), a traditional Chinese medicine, has multi-targeted anticancer effects, including growth inhibition and apoptosis induction. However, it is unclear whether a combination of 5-FU and GA has synergistic anticancer effects in CRC cells. In this study, SW480 and HCT116 human CRC cells and human intestinal epithelial cells (IECs) were treated with different concentrations of 5-FU, GA or 5-FU+GA. A Cell Counting kit-8 assay was conducted to quantify cell proliferation. The combination index (CI) was calculated and the median-effect principle was applied to analyze the interaction between 5-FU and GA. Flow cytometry was used to determine the percentage of cells undergoing apoptosis. Reverse transcription-quantitative polymerase chain reaction and western blotting were applied to measure P53, survivin and thymidylate synthase (TS) mRNA and protein levels. It was found that 5-FU+GA more pronouncedly inhibited cell growth and induced apoptosis, compared with either monotherapy. CI values <1 indicated the synergistic effects of the drugs. 5-FU+GA further decreased P53, survivin and TS mRNA and protein levels in the two CRC cell lines compared with single drugs, whereas increased P53 protein levels were observed in HCT116 cells. Moreover, 5-FU+GA did not increase cytotoxicity to IECs. These results demonstrate that GA enhances the anticancer effects of 5-FU on CRC cells. Combined treatment with 5-FU and GA is effective and safe for CRC cells, and may become a promising chemotherapy treatment.

NSCA-1-a novel N-substituted coumalamide derivative-increases Adriamycin sensitivity in HepG2/adriamycin cells through modulating Akt/GSK-3β signaling and p53-dependant apoptotic pathway

Coumalamide derivatives are one of 2-pyrones derivatives, exerting multifunctional bioactivity. An array of coumalamide derivatives have been developed and presented good antiproliferative properties on cancer cells. However, the synthesis of 5-substituted coumalamide derivatives has not yet been published. Resistance to chemotherapeutic drugs is a major obstacle in hepatocellular carcinoma therapy. Recent evidence suggests that overexpression of constitutively active Akt confers on cancer cells resistance to chemotherapy. In this study, we report the synthesis and biological evaluation of a novel N-substituted coumalamide derivative (NSCA-1). The results indicated that NSCA-1 exerts synergistic cytotoxicity with Adriamycin in HepG2/ADR (HepG2/adriamycin) cells. Furthermore, both of the Akt kinase activity and phosphorylated Akt (Ser473) were found to be inhibited by NSCA-1 and subsequently resulting in decreased phosphorylation of GSK-3β. The intracellular accumulation of Adriamycin was also boosted by NSCA-1 via reducing the expression of p-gp. In addition, we found that combined treatment with NSCA-1 enhance cell apoptosis induced by Adriamycin via p53-dependant apoptotic pathway.

Anti-CD22-conjugated CdTe QDs co-loaded with doxorubicin and gambogic acid: a novel platform for lymphoma treatment

DOX/GA–CdTe–CD22 can precisely target lymphoma and deliver DOX and GA to lymphoma cells to improve their therapeutic effects.

BIRC5 (survivin): a pejorative prognostic marker in stage II/III breast cancer with no response to neoadjuvant chemotherapy

PURPOSE

Neoadjuvant systemic therapy (NAC) is currently used in the treatment of stage II/III breast cancer. Pathological complete response as a surrogate endpoint for clinical outcomes is not completely validated for all subgroups of breast cancers. Therefore, there is a need for reliable predictive tests of the most effective treatment.

METHODS

We used a combination of predictive clinical, pathological, and gene expression-based markers of response to NAC in a prospective phase II multicentre randomized clinical trial in breast cancer patients, with a long follow-up (8 years). This study concerned the subpopulation of 188 patients with similar levels of pathological response rates to sequential epirubicin/cyclophosphamide and docetaxel to determine predictive marker of pCR and DFS. We used a set of 45 genes selected from high throughput analysis and a standardized RT-qPCR. We analyzed the predictive markers of pathological complete response (pCR) and DFS in the overall population and DFS the subpopulation of 159 patients with no pCR.

RESULTS

In the overall population, combining both clinical and genomic variables, large tumor size, low TFF1, and MYBL2 overexpression were significantly associated with pCR. T4 Stage, lymphovascular invasion, negative PR status, histological type, and high values of CCNB1 were associated with DFS. In the no pCR population, only lymphovascular invasion and high values of BIRC5 were associated with DFS.

CONCLUSIONS

We confirm the importance of ER-related and proliferation genes in the prediction of pCR in NAC-treated breast cancer patients. Furthermore, we identified BIRC5 (survivin) as a main pejorative prognostic factor in patients with breast cancers with no pCR. These results also open perspective for predictive markers of new targeted therapies.

Regulation of MAPKs Signaling Contributes to the Growth Inhibition of 1,7-Dihydroxy-3,4-dimethoxyxanthone on Multidrug Resistance A549/Taxol Cells

1,7-Dihydroxy-3,4-dimethoxyxanthone (XAN) is a bioactive compound isolated from Securidaca inappendiculata Hassk. and validated with antiproliferative activities on a panel of cancer cell lines. This study was designed to investigate its growth inhibitory effects on multidrug resistance (MDR) non-small cell lung carcinoma (NSCLC) cell line A549/Taxol and explore the possible linkage between modulation of MAPKs and the bioactivities. Its growth inhibitory potency on the cells was estimated by MTT assay, and flow cytometric analysis was employed to investigate its potential cell cycle arrest and proapoptosis effects. Expressions of hallmark proteins were assessed by Western-Blot method. The results showed A549/Taxol cells were sensitive to XAN. XAN inhibited the proliferation of A549/Taxol cells in the time and concentration dependent manners. It acted as a potent inducer of apoptosis and cell cycle arrest in the cells. Western-Blot investigation validated the proapoptosis and cell cycle arrest activities of XAN and the potential of MDR reversion. Upregulation of p38 by XAN, which accounted for the cell cycle arrest at G2 phase, and the downregulation of ERK associated with the proapoptosis activity were also revealed. Further analysis found p53 may be the central role mediated the bioactivities of MAPKs in A549/Taxol cells. Based on these evidences, a conclusion has been deduced that XAN could be a potential agent for MDR NSCLC therapy targeting specifically MAPKs.

Combination of gambogic acid with cisplatin enhances the antitumor effects on cisplatin-resistant lung cancer cells by downregulating MRP2 and LRP expression

Cisplatin resistance is a main clinical problem of lung cancer therapy. Gambogic acid (GA) could prohibit the proliferation of a variety of human cancer cells. However, the effects of GA on cisplatin-resistant lung cancer are still unclear. The objective of the present study was to find out the antitumor effects of GA on cisplatin-resistant human lung cancer A549/DDP cells and further explore its underlying mechanisms. Cell Counting Kit-8 assay was used to observe the impacts of GA and/or cisplatin on the proliferation of lung cancer cells; flow cytometry was used to detect the effects of GA on cell cycle and apoptosis; Western blot was used to examine the effects of GA on the expression of lung resistance protein (LRP) and multidrug resistance-associated protein 2 (MRP2) protein in A549/DDP cells. Our results showed that GA dose- and time-dependently prohibited the proliferation and induced significant cell apoptosis in A549 and A549/DDP cells. GA also induced G0/G1 arrest in both A549/DDP and A549 cells. Moreover, GA upregulated protein expression level of cleaved caspase-3 and Bax and downregulated protein expression level of pro-caspase-9 and Bcl-2 in time- and dose-dependent way in A549/DDP cells. GA combined with cisplatin enhanced the cells apoptotic rate and reduced the cisplatin resistance index in A549/DDP cells. In addition, GA reduced the MRP2 and LRP protein expression level in A549/DDP cells. GA inhibits the proliferation, induces cell cycle arrest and apoptosis in A549/DDP cells. Combination of GA with cisplatin enhances the antitumor effects on cisplatin-resistant lung cancer cells by downregulating MRP2 and LRP expression.