Shikonin Promotes Skin Cell Proliferation and Inhibits Nuclear Factor-κB Translocation via Proteasome Inhibition In Vitro

Research on traditional Chinese medicine as an effective drug for promoting wound healing

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of skin trauma is high and the repair process is complex, often leading to poor healing and other issues, which can result in significant economic and social burdens. Traditional Chinese medicine (TCM) is a valuable resource with proven effectiveness and safety in wound repair, widely utilized in clinical practice. A systematic analysis of wound healing with a focus on TCM research progress holds both academic and clinical importance.

AIM OF THE REVIEW

This article reviews the research progress of TCM in promoting wound healing, and provides basic data for the development of innovative drugs that promote wound healing.

MATERIALS AND METHODS

This article provides a review of the literature from the past decade and conducts a thorough analysis of various databases that contain reports on the use of TCM for wound repair. The data for this systematic research was gathered from electronic databases including CNKI, SciFinder, and PubMed. The study explores and summarizes the research findings and patterns by creating relevant charts.

RESULTS

This study reviewed the mechanism of wound healing, experimental TCM methods to promote wound healing, the theory and mode of action of TCM to promote wound healing, the active ingredients of TCM that promote wound healing, the efficacy of TCM formulae to promote wound healing, and the potential toxicity of TCM and its antidotes. This study enriched the theory of TCM in promoting wound healing.

CONCLUSION

Skin wound healing is a complex process that can be influenced by various internal and external factors. This article offers a theoretical foundation for exploring and utilizing TCM resources that enhance wound repair. By analyzing a range of TCM that promote wound healing, the article highlights the clinical importance and future potential of these medicines in promoting wound healing.

I-C-F-6 attenuates chronic cerebral hypoperfusion-induced neurological injury in mice by modulating microglia polarization

Chronic cerebral hypoperfusion (CCH) is the leading cause of chronic cerebral dysfunction syndrome with its complex pathological mechanisms involving cortical and hippocampal neuronal loss, white matter lesions, and neuroinflammation. I-C-F-6 is a septapeptide, which has anti-inflammatory and anti-fibrotic effects. This study aimed to evaluate the neuroprotective effect of I-C-F-6 in chronic cerebral hypoperfusion (CCH)-induced neurological injury. C57BL/6 J mice were subjected to bilateral common carotid artery stenosis (BCAS), and BV2 microglia cells were induced with oxygen-glucose deprivation (OGD). In vivo, mice were divided randomly into four groups: Sham, BCAS, GBE (30 mg/kg), and I-C-F-6 (0.5 mg/kg). In vitro, microglia were divided randomly into four groups: control, OGD, I-C-F-6 (25 μg/mL), and Shikonin (800 nmol/L). Through LFB, TUNEL, and NeuN staining, we found that I-C-F-6 was able to mitigate myelin pathology and reduce the number of apoptotic neurons. Furthermore, immunofluorescence staining revealed that I-C-F-6 was able to reduce microglia clustering and downregulate NF-κB p65. We also observed a significant downregulation of M1 phenotype microglia signature genes, such as TNF-α, iNOS, and upregulation of anti-inflammatory cytokines, such as Arg-1 and IL-10, indicating that I-C-F-6 may mainly reduce polarization towards the M1 phenotype in microglia. Notably, I-C-F-6 downregulated the expression of NF-κB signaling pathway-related proteins IKK-β and NF-κB p65, as well as pro-inflammatory cytokines IL-1β and iNOS. In conclusion, I-C-F-6 can improve neurological damage, alleviate neuroinflammation, and inhibit microglia polarization to the M1 phenotype via the NF-κB signaling pathway.

Potential Efficacy of Shiunko for Anti-Epidermal Growth Factor Receptor (EGFR) Monoclonal Antibody-Induced Skin Fissure: A Single Institutional Case Series

PURPOSE

Anti-epidermal growth factor receptor monoclonal antibody (anti-EGFR mAb) is the key drug for RAS/BRAF V600E wild-type metastatic colorectal cancer (mCRC). However, anti-EGFR mAb-induced skin fissures often affect a patient's quality of life. Shiunko, a traditional Japanese topical herbal medicine, is used for burns and dermatitis and may potentially have wound-healing effects. Herein, we report cases of patients with mCRC who were treated with Shiunko for anti-EGFR mAb-induced skin fissure.

METHODS

We retrospectively reviewed consecutive patients with mCRC who received an anti-EGFR mAb-containing regimen and were treated with Shiunko twice a day for skin fissures at the National Cancer Center Hospital East between March 2022 and December 2022. Skin fissures were assessed at baseline and at every visit until 28 days after Shiunko initiation according to CTCAE v5.0.

RESULTS

Among the 11 patients, 5 patients were female; the median age was 61 (range, 43-79) years. The median treatment duration with anti-EGFR mAb before Shiunko initiation was 13.1 (range, 6-52) weeks. Skin moisturizer and topical steroids were applied for skin fissures in 11 and 5 patients, respectively. All patients had grade 2 skin fissures at baseline of Shiunko initiation. Two weeks after Shiunko initiation, complete recovery was noted in 4 patients and improvement to grade 1 was noted in 6 patients. There were no Shiunko-related adverse events. Ten patients continued anti-EGFR mAb treatment until disease progression, while 1 patient discontinued anti-EGFR mAb treatment due to severe eruptions.

CONCLUSION

Shiunko could be a treatment option for anti-EGFR mAb-induced skin fissure. Further studies are warranted to investigate the efficacy and safety of Shiunko for anti-EGFR mAb-induced skin fissure.

Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review

Currently, skin injuries have a serious impact on people's lives and socio-economic stress. Shikonin, a naphthoquinone compound derived from the root of the traditional Chinese medicine Shikonin, has favorable biological activities such as anti-inflammatory, antibacterial, immunomodulatory, anticancer, and wound-healing-promoting pharmacological activities. It has been reported that Shikonin can be used for repairing skin diseases due to its wide range of pharmacological effects. Moreover, the antimicrobial activity of Shikonin can play a great role in food and can also reduce the number of pathogenic bacteria in food. This paper summarizes the research on the pharmacological effects of Shikonin in recent years, as well as research on the mechanism of action of Shikonin in the treatment of certain skin diseases, to provide certain theoretical references for the clinical application of Shikonin, and also to provides research ideas for the investigation of the mechanism of action of Shikonin in other skin diseases.

The anti-leukemia activity and mechanisms of shikonin: a mini review

Leukemia encompasses a group of highly heterogeneous diseases that pose a serious threat to human health. The long-term outcome of patients with leukemia still needs to be improved and new effective therapeutic strategies continue to be an unmet clinical need. Shikonin (SHK) is a naphthoquinone derivative that shows multiple biological function includes anti-tumor, anti-inflammatory, and anti-allergic effects. Numerous studies have reported the anti-leukemia activity of SHK during the last 3 decades and there are studies showing that SHK is particularly effective towards various leukemia cells compared to solid tumors. In this review, we will discuss the anti-leukemia effect of SHK and summarize the underlying mechanisms. Therefore, SHK may be a promising agent to be developed as an anti-leukemia drug.

Natural Plant-Derived Compounds in Food and Cosmetics: A Paradigm of Shikonin and Its Derivatives

Shikonin and its derivatives are the natural naphthoquinone compounds produced in the roots of the Boraginaceae family. These red pigments have been used for a long time in coloring silk, as food colorants, and in the Chinese traditional system of medicines The resurgence of public interest in natural and plant-based products has led to this category of compounds being in high demand due to their wide range of biological activities including antioxidant, antitumor, antifungal, anti-inflammatory ones. Different researchers worldwide have reported various applications of shikonin derivatives in the area of pharmacology. Nevertheless, the use of these compounds in the food and cosmetics fields needs to be explored more in order to make them available for commercial utilization in various food industries as a packaging material and to enhance their shelf life without any side effects. Similarly, the antioxidant properties and skin whitening effects of these bioactive molecules may be used successfully in various cosmetic formulations. The present review delves into the updated knowledge on the various properties of shikonin derivatives in relation to food and cosmetics. The pharmacological effects of these bioactive compounds are also highlighted. Based on various studies, it can be concluded that these natural bioactive molecules have potential to be used in different sectors, including functional food, food additives, skin, health care, and to cure various diseases. Further research is required for the sustainable production of these compounds with minimum disturbances to the environment and in order to make them available in the market at an economic price. Simultaneous studies utilizing recent techniques in computational biology, bioinformatics, molecular docking, and artificial intelligence in laboratory and clinical trials would further help in making these potential candidates promising alternative natural bioactive therapeutics with multiple uses.

Botanical Drugs in Traditional Chinese Medicine With Wound Healing Properties

Chronic and unhealed wound is a serious public problem, which brings severe economic burdens and psychological pressure to patients. Various botanical drugs in traditional Chinese medicine have been used for the treatment of wounds since ancient time. Nowadays, multiple wound healing therapeutics derived from botanical drugs are commercially available worldwide. An increasing number of investigations have been conducted to elucidate the wound healing activities and the potential mechanisms of botanical drugs in recent years. The aim of this review is to summarize the botanical drugs in traditional Chinese medicine with wound healing properties and the underlying mechanisms of them, which can contribute to the research of wound healing and drug development. Taken together, five botanical drugs that have been developed into commercially available products, and 24 botanical drugs with excellent wound healing activities and several multiherbal preparations are reviewed in this article.

Effect of alfalfa substituted with ramie on the expression of apoptotic genes in the gastrointestinal tracts of goats

The study investigated the effect of alfalfa hay substituted with ramie silage on the expression of apoptotic genes in the gastrointestinal tract of goats. Thirty‐two goats were randomly allocated into four groups, in which the alfalfa was substituted with ramie at 0%, 35%, 75%, and 100% levels, respectively. In the rumen, the mRNA expression of Bax was significantly up‐regulated (p = .0007) when alfalfa was 100% substituted by ramie; the mRNA expression of Bcl‐2/Bax was significantly down‐regulated (p = .02) when alfalfa was 100% substituted by ramie compared with the 75% substituted treatment; the protein expression of Bcl‐xl was significantly down‐regulated (p = .03) when alfalfa was 100% substituted by ramie compared with 35% and 75% substituted treatments, respectively. In the jejunum, the mRNA expression of p53 was significantly up‐regulated (p = .01) when alfalfa was 100% substituted by ramie compared with 0% and 35% substituted treatments; the protein expression of p53 was significantly up‐regulated (p = .001) when alfalfa was 35% substituted by ramie compared with 0% and 75% substituted treatments. However, the activity of Caspase‐3 was not affected by different substituting levels of ramie in the rumen and jejunum of goats (p > .05). In conclusion, ramie with high substitution had strong antinutritional effect, which might promote the apoptosis in the gastrointestinal tract of goats in a caspase‐independent manner, thus affecting the growth and development of goat. It was suggested that ramie should not replace alfalfa more than 35% in the process of goat feeding.

Traditional Chinese Medicine is an Alternative Therapeutic Option for Treatment of Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is an opportunistic pathogen causing life-threatening infections in cystic fibrosis patients and immunocompromised individuals, and it is a leading cause of nosocomial infections associated with significant morbidity and mortality. Treatment of P. aeruginosa infections is challenging due to the antibiotic resistance to most of the conventional antibiotics. Development of alternative therapeutic options is urgently demanded for the patients who have antibiotic-resistant infections. Traditional Chinese medicine (TCM) has a clinical history of thousands of years for prevention and treatment of infectious diseases in China, taking advantages of improving clinical outcomes, producing less side effects, inhibiting pathogen, and modulating host immunity. Recent research has revealed a variety of natural products derived from TCM showing significant antimicrobial effects on antibiotic-resistant strains of P. aeruginosa alone or combined with antibiotics in vitro or in animal models, suggesting that TCM is a promising complementary and alternative therapeutic approach for treatment of chronic P. aeruginosa infections. This review summarizes the recent findings attempting to dissect the mechanisms of TCM combating P. aeruginosa infections and highlights the molecular targets of TCM on P. aeruginosa and host.

Electrospun wound dressings containing bioactive natural products: physico-chemical characterization and biological assessment

Background

Current research on skin tissue engineering has been focusing on novel therapies for the effective management of chronic wounds. A critical aspect is to develop matrices that promote growth and uniform distribution of cells across the wound area, and at the same time offer protection, as well as deliver drugs that help wound healing and tissue regeneration. In this context, we aimed at developing electrospun scaffolds that could serve as carriers for the bioactive natural products alkannin and shikonin (A/S).

Methods

A series of polymeric nanofibers composed of cellulose acetate (CA) or poly(ε-caprolactone) (PCL) and varying ratios of a mixture of A/S derivatives, has been successfully fabricated and their physico-chemical and biological properties have been explored.

Results

Scanning electron microscopy revealed a uniform and bead-free morphology for CA scaffolds, while for PCL beads along the fibers were observed. The average diameters for all nanofibers ranged between 361 ± 47 and 487 ± 88 nm. During the assessment of physicochemical characteristics, CA fiber mats exhibited a more favored profile, while the assessment of the biological properties of the scaffolds showed that CA samples containing A/S mixture up to 1 wt.% achieved to facilitate attachment, survival and migration of Hs27 fibroblasts. With respect to the antimicrobial properties of the scaffolds, higher drug-loaded (1 and 5 wt.%) samples succeeded in inhibiting the growth of Staphylococcus epidermidis and S. aureus around the edges of the fiber mats. Finally, carrying out a structure-activity relationship study regarding the biological activities (fibroblast toxicity/proliferation and antibacterial activity) of pure A/S compounds – present in the A/S mixture – we concluded that A/S ester derivatives and the dimeric A/S augmented cell proliferation after 3 days, whereas shikonin proved to be toxic at 500 nM and 1 μM and alkannin only at 1 μM. Additionally, alkannin, shikonin and acetyl-shikonin showed more pronounced antibacterial properties than the other esters, the dimeric derivative and the A/S mixture itself.

Conclusions

Taken together, these findings indicate that embedding A/S derivatives into CA nanofibers might be an advantageous drug delivery system that could also serve as a potential candidate for biomedical applications in the field of skin tissue engineering.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-021-00223-9.

HMGCR inhibition stabilizes the glycolytic enzyme PKM2 to support the growth of renal cell carcinoma

Renal cell carcinoma (RCC) is responsible for most cases of the kidney cancer. Previous research showed that low serum levels of cholesterol level positively correlate with poorer RCC-specific survival outcomes. However, the underlying mechanisms and functional significance of the role of cholesterol in the development of RCC remain obscure. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) plays a pivotal role in RCC development as it is the key rate-limiting enzyme of the cholesterol biosynthetic pathway. In this study, we demonstrated that the inhibition of HMGCR could accelerate the development of RCC tumors by lactate accumulation and angiogenesis in animal models. We identified that the inhibition of HMGCR led to an increase in glycolysis via the regulated HSP90 expression levels, thus maintaining the levels of a glycolysis rate-limiting enzyme, pyruvate kinase M2 (PKM2). Based on these findings, we reversed the HMGCR inhibition-induced tumor growth acceleration in RCC xenograft mice by suppressing glycolysis. Furthermore, the coadministration of Shikonin, a potent PKM2 inhibitor, reverted the tumor development induced by the HMGCR signaling pathway.

Network pharmacology-based preventive effect of XZF on cutaneous toxicities induced by EGFR inhibitor

Skin toxicities induced by epidermal growth factor receptor inhibitors such as Erlotinib plagues clinical challenges. Chinese formulas have a unique advantage in reducing side effects. Here, we aim to investigate the skin protecting function of XiaoZhenFang (XZF), a clinical adjuvant prescription made up of Lonicerae Japonicae Flos, Lithospermum Erythrorhizon, Smilacis Glabrae Rhizoma, Forsythiae Fructus, Spirodelae Herba, Cortex Moutan and Prunellae Spica. Our data showed that XZF aqueous extract effectively reduced skin toxicities induced by Erlotinib in vivo using established mice model. Next, we used a systems pharmacology approach to investigate the pharmacological mechanism of XZF with the goal of understanding its effects at the system, organ, and molecular levels. 44 candidate compounds and 103 potential targets were identified by network pharmacology. Inflammation, cell stress and the EGFR-related signal pathways, which may participate in the skin protection afforded by XZF, were analyzed by gene enrichment. Importantly, our in vivo experimental results largely validated XZF's mechanism of action, as predicted by the system pharmacology analysis. Our study uncovered the effect and mechanism of XZF in attenuating skin toxicities induced by EGFRI, providing a basis for the development of in-hospital preparations and new drugs for the prevention of skin toxicities.

Biological Effects of Shikonin in Human Gingival Fibroblasts via ERK 1/2 Signaling Pathway

Shikonin, an active ingredient of Lithospermum erythrorhizon, exerts anti-inflammatory and antibacterial effects, and promotes wound healing. We investigated whether shikonin stimulated gingival tissue wound healing in human gingival fibroblasts (hGF). In addition, we evaluated the effects of shikonin on the mitogen-activated protein kinase (MAPK) signaling pathway, which has an important role in wound healing. hGF were subjected to primary culture using gingiva collected from patients. The cells were exposed to/treated with Shikonin at concentrations ranging from 0.01 to 100 μM. The optimal concentration was determined by cell proliferation and migration assays. Type I collagen and fibronectin synthesis, the gene expression of vascular endothelial growth factor (VEGF) and FN, and the phosphorylation of Extracellular signal-regulated kinase (ERK) 1/2 were investigated. Identical experiments were performed in the presence of PD98059 our data suggest, a specific ERK 1/2 inhibitor. Shikonin significantly promoted hGF proliferation and migration. Shikonin (1 µM) was chosen as the optimal concentration. Shikonin promoted type I collagen and FN synthesis, increased VEGF and FN expression, and induced ERK 1/2 phosphorylation. These changes were partially suppressed by PD98059. In conclusion, Shikonin promoted the proliferation, migration, type I collagen and FN synthesis, and expression of VEGF and FN via ERK 1/2 signaling pathway in hGFs. Therefore, shikonin may promote periodontal tissue wound healing.

Pharmacological properties and derivatives of shikonin-A review in recent years

Shikonin is the major bioactive component extracted from the roots of Lithospermum erythrorhizon which is also known as "Zicao" in Traditional Chinese Medicine (TCM). Recent studies have shown that shikonin demonstrates various bioactivities related to the treatment of cancer, inflammation, and wound healing. This review aimed to provide an updated summary of recent studies on shikonin. Firstly, many studies have demonstrated that shikonin exerts strong anticancer effects on various types of cancer by inhibiting cell proliferation and migration, inducing apoptosis, autophagy, and necroptosis. Shikonin also triggers Reactive Oxygen Species (ROS) generation, suppressing exosome release, and activate anti-tumor immunity in multiple molecular mechanisms. Examples of these effects include modulating the PI3K/AKT/mTOR and MAPKs signaling; inhibiting the activation of TrxR1, PKM2, RIP1/3, Src, and FAK; and regulating the expression of ERP57, MMPs, ATF2, C-MYC, miR-128, and GRP78 (Bip). Next, the anti-inflammatory and wound-healing properties of shikonin were also reviewed. Furthermore, several studies focusing on shikonin derivatives were reviewed, and these showed that, with modification to the naphthazarin ring or side chain, some shikonin derivatives display stronger anticancer activity and lower toxicity than shikonin itself. Our findings suggest that shikonin and its derivatives could serve as potential novel drug for the treatment of cancer and inflammation.

Sub-chronic oral toxicity of the aqueous extract of lithospermi radix in Fischer 344 rats

ETHNOPHARMACOLOGICAL RELEVANCE

Lithospermi radix has been prescribed in traditional folk medicine to treat diverse diseases like cancer.

AIM OF THE STUDY

The present study assessed the sub-chronic oral toxicity of an aqueous extract of lithospermi radix (WLR) in Fischer 344 rats over a period of 13 weeks.

MATERIALS AND METHODS

The chemical compositions of WLR were analyzed using ultra-high performance liquid chromatography (UHPLC). WLR was daily administered to Fischer 344 rats at 0, 500, 1000, and 2000 mg/kg body weights (bw) for 13 weeks via oral gavage. Changes in mortalities, body weights, and intakes of food and water were monitored during the WLR treatment period. Urine was collected and analyzed 12 h before necropsy. Organ weights, hematological parameters, and plasma biochemical parameters were determined along with histopathological examination.

RESULTS

When compared with the normal control group, no remarkable toxic signs or parameter variations related with WLR treatment were observed in mortality, body weights, organ weights, food and water consumptions, urinalysis, hematological and plasma biochemical analyses, and histopathological examination. Mortalities observed in one male at 2000 mg/kg bw and three females at 1000 mg/kg bw were not related with WLR treatment because no gross findings of toxicity were observed in both morphological and histological examination. Some significant changes in clinical parameters or histological lesions observed in WLR-treated animals were not related with WLR treatment because the differences were marginal and did not show dose-dependent or directional changes.

CONCLUSIONS

Based on these findings, the calculated no-observed-adverse-effect-level (NOAEL) in rats was higher than 2000 mg/kg bw.

Shikonin Suppresses Lymphangiogenesis via NF-κB/HIF-1α Axis Inhibition

Lymphangiogenesis, the formation of lymphatic vessels from preexisting ones, promotes cancer growth and metastasis. Finding natural compounds with anti-lymphangiogenic activity will be useful for preventive treatment of lymphatic metastasis. Shikonin, an ingredient of a traditional Japanese and Chinese medicinal herb Lithospermum erythrorhizon, has been widely used in several pharmaceutical and cosmetic preparations, as well as in food colorants. Shikonin has been reported to inhibit lymphangiogenesis in vitro, but the mechanism of inhibition has not been determined. The aim of this study is to investigate the mechanism of anti-lymphangiogenesis of shikonin in primary human lymphatic endothelial cells (HMVEC-dLy). Shikonin, at non-toxic concentrations, significantly inhibited cord formation ability of lymphatic endothelial cells in a dose- and time-dependent manner. Western blotting analysis showed that shikonin decreased nuclear factor-kappaB (NF-κB) activation, as indicated by phosphorylation and nuclear translocation of NF-κB p65, and also reduced both mRNA and protein levels of hypoxia-inducible factor-1 (HIF-1)α. Use of an NF-κB inhibitor (BAY 11-7085) and HIF-1α small interfering RNA (siRNA) transfection revealed that NF-κB activation was upstream of HIF-1α expression, which controls cord formation by HMVEC-dLy. In addition, the reduction of vascular endothelial growth factor C (VEGF-C) and vascular endothelial growth factor receptor-3 (VEGFR-3) mRNA levels were also found in HMVEC-dLy that treated with shikonin. In conclusion, shikonin inhibits lymphangiogenesis in vitro by interfering the NF-κB/HIF-1α pathway and involves in suppression of VEGF-C and VEGFR-3 mRNA expression.

Cytotoxicity and antigenotoxicity evaluation of acetylshikonin and shikonin

Shikonin (SH) is used as a red pigment for food coloring and cosmetics, and has cytotoxic activity towards cancer cells. However, due to strong toxicity SH has limited potential as an anticancer drug. Acetylshikonin (ASH) is one of the SH derivatives with promising anticancer potential. In present study, we attempted to evaluate and compare the cytotoxicity of SH and ASH towards a normal cell line (V79) and in addition to evaluate their antigenotoxic activity. The evaluation was made with the use of the set of cytotoxicity assays with V79 line and the micronucleus test in vitro performed using clinafloxacin (CLFX), ethyl methanesulfonate (EMS) as direct genotoxins and cyclophosphamide (CPA) as indirect genotoxin. For CPA and EMS the simultaneous protocol was used and for CLFX three different variants were performed: pretreatment, simultaneous, and post-treatment. A higher cytotoxic effect was observed for SH. The EC50 values obtained for SH were approximately twofold lower compared to that of ASH. Moreover, ASH exhibited an antigenotoxic potential against CPA-induced genotoxicity, whereas SH has no activity. However, ASH increased the EMS-induced genotoxicity, when SH exhibited no effect. Both compounds decreased the genotoxicity of CLFX in pretreatment and simultaneous protocol. Based on the results of the present study it can be concluded that ASH is less cytotoxic than SH to normal cells and has comparable antigenotoxic potential.

Next-generation proteasome inhibitor oprozomib enhances sensitivity to doxorubicin in triple-negative breast cancer cells

Doxorubicin (DOX) is the most common chemotherapeutic drug for treatment of breast cancer but intrinsic and acquired resistance frequently occurs and severe side effects occur at high doses. DOX might induce activation of NF-κB causing this resistance, in which case proteasome inhibitors could inhibit activation of NF-κB by blocking inhibitory factor κB-alpha degradation. Triple-negative breast cancer (TNBC) is highly progressive and there are no established therapeutic targets against TNBC. Although some proteasome inhibitors have been shown to have antitumor effects in breast cancer, the effect of orally bioavailable proteasome inhibitor oprozomib on TNBC proliferation remains unclear. In the present study, we investigated the role of oprozomib in two TNBC lines, MDA-MB-231 and BT-549. Oprozomib had cytotoxic effects on TNBC cells and increased DOX-induced cytotoxic effects and apoptosis by enhancing DOX-induced JNK/p38 MAPK phosphorylation and inhibiting DOX-induced inhibitory factor êB alpha degradation. These results suggest that oprozomib has potent antitumor effects on TNBC in vitro and can sensitize TNBC cells to DOX treatment. The combination of DOX and oprozomib may be an effective and feasible therapeutic option for TNBC.

Second-generation proteasome inhibitor carfilzomib enhances doxorubicin-induced cytotoxicity and apoptosis in breast cancer cells

Proteasome inhibition is an attractive approach for anticancer therapy. Doxorubicin (DOX) is widely used for treatment in a number of cancers including breast cancer; however, the development of DOX resistance largely limits its clinical application. One of the possible mechanisms of DOX-resistance is that DOX might induce the activation of NF-κB. In this case, proteasome inhibitors could inhibit the activation of NF-κB by blocking inhibitory factor κB (IκB) degradation. Carfilzomib, a second-generation proteasome inhibitor, overcomes bortezomib resistance and lessens its side-effects. Currently, the effect of carfilzomib on breast cancer cell proliferation remains unclear. In this study, we exploited the role of carfilzomib in seven breast cancer cell lines, MCF7, T-47D, MDA-MB-361, HCC1954, MDA-MB-468, MDA-MB-231, and BT-549, representing all major molecular subtypes of breast cancer. We found that carfilzomib alone had cytotoxic effects on the breast cancer cells and it increased DOX-induced cytotoxic effects and apoptosis in combination by enhancing DOX-induced JNK phosphorylation and inhibiting DOX-induced IκBα degradation. The results suggest that carfilzomib has potent antitumor effects on breast cancer in vitro and can sensitize breast cancer cells to DOX treatment. DOX in combination with carfilzomib may be an effective and feasible therapeutic option in the clinical trials for treating breast cancer.

Biosynthesis and molecular actions of specialized 1,4-naphthoquinone natural products produced by horticultural plants

The 1,4-naphthoquinones (1,4-NQs) are a diverse group of natural products found in every kingdom of life. Plants, including many horticultural species, collectively synthesize hundreds of specialized 1,4-NQs with ecological roles in plant-plant (allelopathy), plant-insect and plant-microbe interactions. Numerous horticultural plants producing 1,4-NQs have also served as sources of traditional medicines for hundreds of years. As a result, horticultural species have been at the forefront of many basic studies conducted to understand the metabolism and function of specialized plant 1,4-NQs. Several 1,4-NQ natural products derived from horticultural plants have also emerged as promising scaffolds for developing new drugs. In this review, the current understanding of the core metabolic pathways leading to plant 1,4-NQs is provided with additional emphasis on downstream natural products originating from horticultural species. An overview on the biochemical mechanisms of action, both from an ecological and pharmacological perspective, of 1,4-NQs derived from horticultural plants is also provided. In addition, future directions for improving basic knowledge about plant 1,4-NQ metabolism are discussed.