Nobiletin inhibits human osteosarcoma cells metastasis by blocking ERK and JNK-mediated MMPs expression

Unveiling the therapeutic potential of natural-based anticancer compounds inducing non-canonical cell death mechanisms

In the Mid-19th century, Rudolf Virchow considered necrosis to be a prominent form of cell death; since then, pathologists have recognized necrosis as both a cause and a consequence of disease. About a century later, the mechanism of apoptosis, another form of cell death, was discovered, and we now know that this process is regulated by several molecular mechanisms that "programme" the cell to die. However, discoveries on cell death mechanisms are not limited to these, and recent studies have allowed the identification of novel cell death pathways that can be molecularly distinguished from necrotic and apoptotic cell death mechanisms. Moreover, the main goal of current cancer therapy is to discover and develop drugs that target apoptosis. However, resistance to chemotherapeutic agents targeting apoptosis is mainly responsible for the failure of clinical therapy and adverse side effects of the chemotherapeutic agents currently in use pose a major threat to the well-being and lives of patients. Therefore, the development of natural-based anticancer drugs with low cellular and organismal side effects is of great interest. In this comprehensive review, we thoroughly examine and discuss natural anticancer compounds that specifically target non-canonical cell death mechanisms.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Nobiletin inhibits breast cancer cell migration and invasion by suppressing the IL-6-induced ERK-STAT and JNK-c-JUN pathways

BACKGROUND

Breast cancer is one of the most common cancers in women, affecting more than 2 million women worldwide annually. However, effective treatments for breast cancer are limited. Nobiletin is a flavonoid present in the dried mature pericarp of mandarin orange (Citrus reticulata Blanco), which is used to prepare Citri Renetulatae Pericarpium and can inhibit tumour growth and progression according to modern pharmacological studies. However, whether nobiletin exhibits an antimetastatic role in breast cancer and its potential mechanism need to be further investigated.

PURPOSE

This study aims to evaluate the inhibitory effect of nobiletin on breast cancer and to elucidate potential mechanisms against invasion and migration.

METHODS

Cell viability was determined by cell counting kit-8 and colony formation assays. Wound healing and Boyden chamber assays detected cancer cell migration and invasion capabilities. Immunoblotting and qPCR were applied to determine the protein and mRNA expression levels of extracellular signal-regulated kinases (ERK) and the c-Jun N-terminal kinase (JNK) signalling pathways. Molecular docking was used to assess the degree of nobiletin binding to phosphatidylinositol 3-kinase (PI3K). Xenografts and liver metastases were constructed in BALB/c nude mice to evaluate the anticancer effect of nobiletin in vivo. H&E staining and immunohistochemistry were used to detect proliferation and the expression of related proteins.

RESULTS

Nobiletin induced cell death in a concentration- and time-dependent manner and possessed anti-invasion and anti-migration effects on MCF-7 and T47D cells by suppressing the interleukin-6-induced ERK and JNK signalling pathways. In addition, nobiletin docked with the binding site of PI3K, and the binding score was -8.0 kcal/mol. Furthermore, the inhibition of breast cancer growth and metastasis by nobiletin was demonstrated by constructing xenografts and liver metastases in vivo.

CONCLUSION

Nobiletin inhibited liver metastasis of breast cancer by downregulating the ERK-STAT and JNK-c-JUN pathways, and its safety and efficacy were verified, indicating the potential of nobiletin as an anticancer agent.

Curcumin in human osteosarcoma: From analogs to carriers

Osteosarcoma (osteogenic sarcoma), the most prevalent primary malignant bone tumor in adolescents, confers low survival rates in patients with metastatic disease. Dietary curcumin has a number of anticancer properties but has poor bioavailability. To improve the clinical applications of curcumin, several potential curcumin analogs and nanobased curcumin delivery systems have been developed. In this critical review, we address the biological and pharmacological characteristics of curcumin and its analogs, with an emphasis on strategies to improve the bioactivity and bioavailability of curcumin analogs that may increase their application in the treatment of potent human metastatic osteosarcoma. We highlight promising current multifunctional nanoformulations and three-dimensional printed scaffold systems utilized for the targeting and delivery of curcumin in human osteosarcoma cells. Our purpose is to drive further research on curcumin analogs and carriers to improve their bioavailability and anti-osteosarcoma bioactivity.

Curcumin and its Analogs and Carriers: Potential Therapeutic Strategies for Human Osteosarcoma

Curcumin is a natural polyphenol phytochemical derived from turmeric with antioxidant, anti-inflammatory, and anticancer properties but is concerned about poor solubility in water, absorption, and metabolic stability. Potent metastatic osteosarcoma is the most common primary bone cancer in children, adolescents, and young adults. It is responsible for low survival rates because of its high rate of metastasis to the lungs. To improve poor bioavailability, numerous curcumin analogs were developed to possess anticancer characteristics through a variety of biological pathways involved in cytotoxicity, proliferation, autophagy, sensitizing chemotherapy, and metastases. This review provides an overview of their various pharmacological functions, molecular mechanisms, and therapeutic potential as a remedy for human osteosarcoma. To enhance therapeutic efficacy, several liposomal nanoparticles, nanocarriers, multifunctional micelles, and three-dimensional printed scaffolds have also been developed for the controlled delivery of curcumin targeting human osteosarcoma cells. Consequently, curcumin and several potential analogs and delivery formulations are optimistic candidates to improve the currently available strategy for human osteosarcoma. However, further insight into the mechanism of action of promising curcumin analogs and the development of carriers in clinical trials of osteosarcoma needs to be investigated to improve their overall potency and clinical utility, in particular the anti-metastatic effect.

Role of the JNK Pathway in Bladder Cancer

Bladder cancer, one of the most frequently diagnosed cancers worldwide, is associated with high morbidity and mortality and a poor prognosis. The bladder cancer types include 1) non-muscle invasive bladder cancer (NMIBC) and 2) muscle invasive bladder cancer (MIBC). Metastases and chemoresistance in MIBC patients are the leading causes of the high death rate. c-Jun N-terminal kinase (JNK) is an important factor for the undifferentiated state of cancer cells. JNK belongs to the mitogen-activated protein kinases (MAPKs) family; it is activated by various extracellular stimuli, such as stress, radiation, and growth factors and mediates diverse cellular functions, such as apoptosis, autophagy, proliferation, invasion, and migration by mediating AKT (Ak strain transforming), ATG (Autophagy related), mTOR (Mammalian target of rapamycin), and caspases 3, 8, and 9. This review describes the JNK-related functions, mechanisms, and signaling in bladder cancer.

Mechanism of Citri Reticulatae Pericarpium as an Anticancer Agent from the Perspective of Flavonoids: A Review

Citri Reticulatae Pericarpium (CRP), also known as “chenpi”, is the most common qi-regulating drug in traditional Chinese medicine. It is often used to treat cough and indigestion, but in recent years, it has been found to have multi-faceted anti-cancer effects. This article reviews the pharmacology of CRP and the mechanism of the action of flavonoids, the key components of CRP, against cancers including breast cancer, lung cancer, prostate cancer, hepatic carcinoma, gastric cancer, colorectal cancer, esophageal cancer, cervical cancer, bladder cancer and other cancers with a high diagnosis rate. Finally, the specific roles of CRP in important phenotypes such as cell proliferation, apoptosis, autophagy and migration–invasion in cancer were analyzed, and the possible prospects and deficiencies of CRP as an anticancer agent were evaluated.

Two new methoxylated flavones isolated from Casimiroa edulis La Llave and their MMP-9 inhibitory activity

Casimiroa edulis La Llave is known to contain unusual 5,6-dimethoxyflavones bearing a variously oxygenated B-ring. Phytochemical investigation of the leaves and the roots of C. edulis achieved the isolation of two new methoxylated flavones, named casedulones A (1) and B (2), together with 12 known analogues. Their unique structures were established with the aid of spectral analyses and total syntheses. Pre-treatment with 20 µM of 1 and 2 suppressed MMP-9 expression in LPS-mediated THP-1 cells, indicating that the characteristic flavonoids in C. edulis could be potential anti-angiogenics for cancer prevention.

Nobiletin as a chemopreventive natural product against cancer, a comprehensive review

As a leading cause of death, second only to heart disease, cancer has always been one of the burning topics in medical research. When targeting multiple signal pathways in tumorigenesis chemoprevention, using natural or synthetic anti-cancer drugs is a vital strategy to reduce cancer damage. However, toxic effects, multidrug resistance (MDR) as well as cancer stem cells (CSCs) all prominently limited the clinical application of conventional anticancer drugs. With low side effects, strong biological activity, unique mechanism, and wide range of targets, natural products derived from plants are considered significant sources for new drug development. Nobiletin is one of the most attractive compounds, a unique flavonoid primarily isolated from the peel of citrus fruits. Numerous studies in vitro and in vivo have suggested that nobiletin and its derivatives possess the eminent potential to become effective cancer chemoprevention agents through various cellular and molecular levels. This article aims to comprehensively review the anticancer efficacy and specific mechanisms of nobiletin, enhancing our understanding of its chemoprevention properties and providing the latest research findings. At the end of this review, we also give some discussion and future perspectives regarding the challenges and opportunities in nobiletin efficient exploitation.

Hesperetin Inhibits TGF-β1-Induced Migration and Invasion of Triple Negative Breast Cancer MDA-MB-231 Cells via Suppressing Fyn/Paxillin/RhoA Pathway

Triple-negative breast cancer is an aggressive subtype of breast cancer with poor clinical outcomes and poor prognosis. Hesperetin is an active component extracted from Citrus fruits and Traditional Chinese Medicine has a wide range of pharmacological effects. Here, we assessed the anti-migration and anti-invasive effects and explored inhibitory mechanisms of hesperetin on metastasis of human triple negative breast cancer MDA-MB-231 cells. Cell viability experiments revealed that 200 μM hesperetin has a clear inhibitory effect on MDA-MB-231 cells. TGF-β1 treatment induces apparent tumor progression in MDA-MB-231 cells including aberrant wound-healing and invasion ability, which is effectively suppressed by hesperetin co-treatment. Additionally, hesperetin inhibited the TGF-β1-mediated actin stress fiber formation. Western blot results showed that hesperetin suppressed the TGF-β1-mediated (i) activation of Fyn, (ii) phosphorylation of paxillin at Y31, Y88, and Y118 sites, (iii) the increased expression of RhoA, and (iv) activation of Rho-kinase. We demonstrated the increased interaction of Fyn with paxillin and RhoA protein in the TGF-β1-induced metastasis of MDA-MB-231 cells. Small interfering RNA Fyn inhibited phosphorylation of paxillin (Y31) and activation of Rho-kinase induced by TGF-β1. In conclusion, hesperetin has a significant inhibitory effect on migration and invasion of MDA-MB-231 cells induced by TGF-β1, which might be attributed to inhibiting the Fyn/paxillin/RhoA pathway.

Osteosarcoma and Metastasis

Osteosarcoma is the most common primary bone malignancy in adolescents. Its high propensity to metastasize is the leading cause for treatment failure and poor prognosis. Although the research of osteosarcoma has greatly expanded in the past decades, the knowledge and new therapy strategies targeting metastatic progression remain sparse. The prognosis of patients with metastasis is still unsatisfactory. There is resonating urgency for a thorough and deeper understanding of molecular mechanisms underlying osteosarcoma to develop innovative therapies targeting metastasis. Toward the goal of elaborating the characteristics and biological behavior of metastatic osteosarcoma, it is essential to combine the diverse investigations that are performed at molecular, cellular, and animal levels from basic research to clinical translation spanning chemical, physical sciences, and biology. This review focuses on the metastatic process, regulatory networks involving key molecules and signaling pathways, the role of microenvironment, osteoclast, angiogenesis, metabolism, immunity, and noncoding RNAs in osteosarcoma metastasis. The aim of this review is to provide an overview of current research advances, with the hope to discovery druggable targets and promising therapy strategies for osteosarcoma metastasis and thus to overcome this clinical impasse.

Potential of natural products in osteosarcoma treatment: Focus on molecular mechanisms

Osteosarcoma is the most frequent type of bone cancer found in children and adolescents, and commonly arises in the metaphyseal region of tubular long bones. Standard therapeutic approaches, such as surgery, chemotherapy, and radiation therapy, are used in the management of osteosarcoma. In recent years, the mortality rate of osteosarcoma has decreased due to advances in treatment methods. Today, the scientific community is investigating the use of different naturally derived active principles against various types of cancer. Natural bioactive compounds can function against cancer cells in two ways. Firstly they can act as classical cytotoxic compounds by non-specifically affecting macromolecules, such as DNA, enzymes, and microtubules, which are also expressed in normal proliferating cells, but to a greater extent by cancer cells. Secondly, they can act against oncogenic signal transduction pathways, many of which are activated in cancer cells. Some bioactive plant-derived agents are gaining increasing attention because of their anti-cancer properties. Moreover, some naturally-derived compounds can significantly promote the effectiveness of standard chemotherapy drugs, and in certain cases are able to ameliorate drug-induced adverse effects caused by chemotherapy. In the present review we summarize the effects of various naturally-occurring bioactive compounds against osteosarcoma.

Emetine exerts anticancer effects in U2OS human osteosarcoma cells via activation of p38 and inhibition of ERK, JNK, and β-catenin signaling pathways

Osteosarcoma (OS) is a primary bone neoplasm that is highly malignant. As advances in chemotherapy for the treatment of OS have stagnated, discovery of new reagents is required. Emetine is a phytochemical which can be isolated from a medicinal herb Cephaelis ipecacuanha and is traditionally used for amoebicides. Previous studies have demonstrated that emetine can possibly be repositioned for use in anticancer reagents. However, any anticancer effects and underlying mechanisms of emetine on human OS are not yet well understood. In this study, we analyzed the anticancer effects and involved cellular mechanisms after treatment with emetine to U2OS human OS cells. Emetine significantly reduced both the viability and proliferation, and induced apoptosis via activation of caspase-3 and caspase-7 in U2OS cells. Emetine effectively inhibited the migration and invasion of U2OS cells. Gelatinase activities of matrix metalloproteinase 2 (MMP-2) and MMP-9 were reduced by emetine. MMP-9 was transcriptionally inhibited, while MMP-2 was posttranscriptionally repressed, via the reduced expression of membrane-type I-matrix metalloproteinase (MT1-MMP). p38, which is closely related with induction of apoptosis, was stimulated by emetine. Extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and β-catenin, which are linked with expression of MMPs, were downregulated. Emetine exerted anticancer effects on MG63 human OS cells as well. Taken together, our study demonstrated the anticancer and antimetastatic potential of emetine in treating human OS for the first time. It is expected that emetine may be a promising drug candidate to be repositioned for chemotherapy of OS.

The Application of Citrus folium in Breast Cancer and the Mechanism of Its Main Component Nobiletin: A Systematic Review

Citrus folium and its main ingredient nobiletin (NOB) have received widespread attention in recent years due to their antitumor effects. The antitumor effect of Citrus folium is related to the traditional use, mainly in its Chinese medicinal properties of soothing the liver and promoting qi, resolving phlegm, and dispelling stagnation. Some studies have proved that Citrus folium and NOB are more effective for triple-negative breast cancer (TNBC), which is related to the syndrome of stagnation of liver qi. From the perspective of modern biomedical research, NOB has anticancer effects. Its potential molecular mechanisms include inhibition of the cell cycle, induction of apoptosis, and inhibition of angiogenesis, invasion, and migration. Citrus folium and NOB can also reduce the side effects of chemotherapy drugs and reverse multidrug resistance (MDR). However, more research studies are needed to clarify the underlying mechanisms. The modern evidence of Citrus folium and NOB in breast cancer treatment has a strong connection with the traditional concepts and laws of applying Citrus folium in Chinese medicine (CM). As a low-toxic anticancer drug candidate, NOB and its structural changes, Citrus folium, and compound prescriptions will attract scientists to use advanced technologies such as genomics, proteomics, and metabolomics to study its potential anticancer effects and mechanisms. On the contrary, there are relatively few studies on the anticancer effects of Citrus folium and NOB in vivo. The clinical application of Citrus folium and NOB as new cancer treatment drugs requires in vivo verification and further anticancer mechanism research. This review aims to provide reference for the treatment of breast cancer by Chinese medicine.

Utilizing network pharmacology to explore potential mechanisms of YiSui NongJian formula in treating myelodysplastic syndrome

The study aims to explore potential mechanisms of YiSui NongJian formula (YSNJF) in treating myelodysplastic syndromes (MDS) by network pharmacology-based strategy. Active compounds and corresponding potential therapeutic targets of YSNJF were harvested by utilizing the database of TCMSP (Traditional Chinese Medicine Systems Pharmacology) and BATMAN-TCM (Bioinformatics Analysis Tool for Molecular mechanism of Traditional Chinese Medicine). MDS targets were adopted from GeneCard, KEGG (Kyoto Encyclopedia of Genes and Genomes), TTD (Therapeutic Target Database), DrugBank, and DisGeNet. Then a network of YSNJF- compounds-target-MDS network was harvested. The protein–protein interaction (PPI) network was then generated by the Sting database and subjected to Cytoscape software to harvest major and core targets network by topological analysis. Genes from the core targets network were further subjected to Gene Ontology (GO) and KEGG enrichment analysis to figure out potential targeting pathways. Finally, a compounds-targets-pathways network was generated by Cytoscape. A total of 210 active compounds and 768 corresponding potential therapeutic targets were harvested from ingredients of YSNJF. MDS was shown to have 772 potential treating targets with 98 intersected targets corresponding to 98 active compounds in YSNJF. Topological analysis revealed that 15 targets formed the core PPI network. Further, GO and KEGG enrichment analysis revealed that those core targets were mainly enriched on cell cycle- and immune-related pathways. The present study revealed that therapeutic effects of YSNJF on MDS might be achieved through regulating cell cycle- and immune-related pathways.

Nobiletin Inhibits Cell Growth, Migration and Invasion, and Enhances the Anti-Cancer Effect of Gemcitabine on Pancreatic Cancer Cells

Natural products are very promising adjuvants with a variety of biological activities. Nobiletin, a citrus polymethoxyflavone, has been shown to exert an anticancer effect in various cell lines. In this study, we investigated the effects of nobiletin on cell viability, sphere formation, migration and invasion of pancreatic cancer cells, and the underlying mechanisms. Our results demonstrate that nobiletin significantly inhibited PANC-1 cell migration and invasion, and these effects were associated with downregulation of MMP-2. We also found that nobiletin, in a low concentration, exhibited a strong inhibitory effect on sphere formation. The potential molecular mechanisms were related to significant downregulation of p-mTOR and p-STAT3. Furthermore, we found that nobiletin combined with gemcitabine synergistically inhibited PANC-1 cell viability and sphere formation. The underlying mechanisms of the synergistic inhibition on growth were associated with decreases in p-STAT3 expression. Overall, our results suggest that nobiletin may be a promising candidate for pancreatic cancer adjuvant treatment.

Nobiletin promotes the pyroptosis of breast cancer via regulation of miR-200b/JAZF1 axis

Nobiletin is a polymethoxylated flavone present in citrus fruits, which has been reported to have inhibitory effects on tumorigenesis of cancers. However, the biological function of nobiletin in breast cancer (BC) is largely unknown. To investigate the effect of nobiletin on growth of BC cells, the cell viability of BC was measured by MTT assay. In addition, gene and protein expressions were detected by qRT-PCR and western blot, respectively. The apoptosis and pyroptosis of BC cells were tested by flow cytometry. Finally, the correlation between miR-200b and JAZF1 was detected by dual luciferase report. The data indicated that nobiletin inhibited the proliferation of BC cells in a dose-dependent manner. Moreover, miR-200b mimics-induced pyroptosis of BC cells was further increased by nobiletin. Meanwhile, JAZF1 was found to be the target of miR-200b. Moreover, nobiletin induced apoptosis and pyroptosis of BC cells via miR-200b/JAZF1/NF-κB axis. In conclusion, nobiletin inhibited the tumorigenesis of BC via regulation of miR-200b/JAZF1 axis. Thus, nobiletin might serve as a new agent for the treatment of BC.

Curcumin Analogue L48H37 Suppresses Human Osteosarcoma U2OS and MG-63 Cells' Migration and Invasion in Culture by Inhibition of uPA via the JAK/STAT Signaling Pathway

Osteosarcoma, the most prevalent malignant bone tumor in the pediatric age group, is responsible for the great majority of cancer-associated deaths owing to its highly metastatic potential. The anti-metastatic effects of the new curcumin analogue L48H37 in human osteosarcoma are still unknown; hence, we investigated whether L48H37 represses human osteosarcoma cells’ biological behavior of migratory potential and invasive activities and attempted to delve into its underlying mechanisms. L48H37 up to 5 μM inhibited, without cytotoxicity, the motility, migration, and invasion of human osteosarcoma U2OS and MG-63 cells. In U2OS cells, the human protease array revealed an obvious decrease in urokinase plasminogen activator (uPA) expression after L48H37 treatment, and L48H37 actually reduced the level, protein and mRNA expression, and promoter activity of uPA dose-dependently. L48H37 decreased the phosphorylation of STAT3, JAK1, JAK2, and JAK3 in U2OS cells, but did not affect the phosphorylation of ERK, JNK, p38, and Akt. Using colivelin, an activator of STAT3, the L48H37-induced decrease in uPA and migratory potential could be countered as expected. Collectively, L48H37 represses the invasion and migration capabilities of U2OS and MG-63 cells by the suppression of uPA expression and the inhibition of JAK/STAT signaling. These results suggest that L48H37 may be a potential candidate for anti-metastatic treatment of human osteosarcoma.

Effects of Salicylic Acid and Methyl Jasmonate Treatments on Flavonoid and Carotenoid Accumulation in the Juice Sacs of Satsuma Mandarin In Vitro

Salicylic acid and jasmonic acid are two important plant hormones that trigger the plant defense responses and regulate the accumulation of bioactive compounds in plants. In the present study, the effects of salicylic acid (SA) and methyl jasmonate (MeJA) on flavonoid and carotenoid accumulation were investigated in the juice sacs of Satsuma mandarin in vitro. The results showed that SA treatment was effective to enhance the contents of eriocitrin, narirutin, poncirin, and β-cryptoxanthin in the juice sacs (p < 0.05). In contrast, the MeJA treatment inhibited flavonoid and carotenoid accumulation in the juice sacs (p < 0.05). Gene expression results showed that the changes of flavonoid and carotenoid contents in the SA and MeJA treatments were highly regulated at the transcriptional level. In addition, a transcriptional factor CitWRKY70 was identified in the microarray analysis, which was induced by the SA treatment, while suppressed by the MeJA treatment. In the SA and MeJA treatments, the change in the expression of CitWRKY70 was consistent with that of flavonoid and carotenoid biosynthetic key genes. These results indicated that CitWRKY70 might be involved in the regulation of flavonoid and carotenoid accumulation in response to SA and MeJA treatments in the juice sacs of citrus fruit.

New insights into antimetastatic signaling pathways of melatonin in skeletomuscular sarcoma of childhood and adolescence

Melatonin is an indole produced by the pineal gland at night under normal light or dark conditions, and its levels, which are higher in children than in adults, begin to decrease prior to the onset of puberty and continue to decline thereafter. Apart from circadian regulatory actions, melatonin has significant apoptotic, angiogenic, oncostatic, and antiproliferative effects on various cancer cells. Particularly, the ability of melatonin to inhibit skeletomuscular sarcoma, which most commonly affects children, teenagers, and young adults, is substantial. In the past few decades, the vast majority of references have focused on the concept of epithelial-mesenchymal transition involvement in invasion and migration to allow carcinoma cells to dissociate from each other and to degrade the extracellular matrix. Recently, researchers have applied this idea to sarcoma cells of mesenchymal origin, e.g., osteosarcoma and Ewing sarcoma, with their ability to initiate the invasion-metastasis cascade. Similarly, interest of the effects of melatonin has shifted from carcinomas to sarcomas. Herein, in this state-of-the-art review, we compiled the knowledge related to the molecular mechanism of antimetastatic actions of melatonin on skeletomuscular sarcoma as in childhood and during adolescence. Utilization of melatonin as an adjuvant with chemotherapeutic drugs for synergy and fortification of the antimetastatic effects for the reinforcement of therapeutic actions are considered.

Therapeutic Potential of Ursonic Acid: Comparison with Ursolic Acid

Plants have been used as drugs to treat human disease for centuries. Ursonic acid (UNA) is a naturally occurring pentacyclic triterpenoid extracted from certain medicinal herbs such as Ziziphus jujuba. Since the pharmacological effects and associated mechanisms of UNA are not well-known, in this work, we attempt to introduce the therapeutic potential of UNA with a comparison to ursolic acid (ULA), a well-known secondary metabolite, for beneficial effects. UNA has a keto group at the C-3 position, which may provide a critical difference for the varied biological activities between UNA and ULA. Several studies previously showed that UNA exerts pharmaceutical effects similar to, or stronger than, ULA, with UNA significantly decreasing the survival and proliferation of various types of cancer cells. UNA has potential to exert inhibitory effects in parasitic protozoa that cause several tropical diseases. UNA also exerts other potential effects, including antihyperglycemic, anti-inflammatory, antiviral, and antioxidant activities. Of note, a recent study highlighted the suppressive potential of UNA against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Molecular modifications of UNA may enhance bioavailability, which is crucial for in vivo and clinical studies. In conclusion, UNA has promising potential to be developed in anticancer and antiprotozoan pharmaceuticals. In-depth investigations may increase the possibility of UNA being developed as a novel reagent for chemotherapy.

Expression and functional analysis of the nobiletin biosynthesis-related gene CitOMT in citrus fruit

Nobiletin, a polymethoxy flavone (PMF), is specific to citrus and has been reported to exhibit important health-supporting properties. Nobiletin has six methoxy groups at the 3′,4′,5,6,7,8-positions, which are catalyzed by O-methyltransferases (OMTs). To date, researches on OMTs in citrus fruit are still limited. In the present study, a novel OMT gene (CitOMT) was isolated from two citrus varieties Satsuma mandarin (Citrus unshiu Marc.) and Ponkan mandarin (Citrus reticulata Blanco), and its function was characterized in vitro. The results showed that the expression of CitOMT in the flavedo of Ponkan mandarin was much higher than that of Satsuma mandarin during maturation, which was consistent with the higher accumulation of nobiletin in Ponkan mandarin. In addition, functional analysis showed that the recombinant protein of CitOMT had methylation activity to transfer a methyl group to 3′-hydroxy group of flavones in vitro. Because methylation at the 3′-position of flavones is vital for the nobiletin biosynthesis, CitOMT may be a key gene responsible for nobiletin biosynthesis in citrus fruit. The results presented in this study will provide new strategies to enhance nobiletin accumulation and improve the nutritional qualities of citrus fruit.

Nobiletin affects circadian rhythms and oncogenic characteristics in a cell-dependent manner

The natural product nobiletin is a small molecule, widely studied with regard to its therapeutic effects, including in cancer cell lines and tumors. Recently, nobiletin has also been shown to affect circadian rhythms via their enhancement, resulting in protection against metabolic syndrome. We hypothesized that nobiletin's anti-oncogenic effects, such as prevention of cell migration and formation of anchorage independent colonies, are correspondingly accompanied by modulation of circadian rhythms. Concurrently, we wished to determine whether the circadian and anti-oncogenic effects of nobiletin differed across cancer cell lines. In this study, we assessed nobiletin's circadian and therapeutic characteristics to ascertain whether these effects depend on cell line, which here also varied in terms of baseline circadian rhythmicity. Three cell culture models where nobiletin's effects on cell proliferation and migration have been studied previously were evaluated: U2OS (bone osteosarcoma), which possesses robust circadian rhythms; MCF7 (breast adenocarcinoma), which has weak circadian rhythms; and MDA-MB-231 (breast adenocarcinoma), which is arrhythmic. We found that circadian, migration, and proliferative effects following nobiletin treatment were subtle in the U2OS and MCF7 cells. On the other hand, changes were clear in MDA-MB-231s, where nobiletin rescued rhythmicity and substantially reduced oncogenic features, specifically two-dimensional cell motility and anchorage-independent growth. Based on these results and those previously described, we posit that the effects of nobiletin are indeed cell-type dependent, and that a positive correlation may exist between nobiletin's circadian and therapeutic effects.

New insights into molecular and cellular mechanisms of zoledronate in human osteosarcoma

Osteosarcoma is the most common primary malignant tumor of the skeleton in teenagers and young adults and continues to confer a generally poor prognosis in patients who do not respond to chemotherapy or who present with metastatic diseases at diagnosis. The nitrogen-containing zoledronate, the third generation bisphosphonate (BP), effectively inhibits osteoclastic bone resorption and is widely utilized in the treatment of metabolic and metastatic bone diseases nowadays. Owing to an acceptable safety profile and tolerability, zoledronate is the only BP currently approved for the prevention and treatment of skeletal relevant events in patients with metastatic bone lesions, especially bone metastases from advanced renal cell carcinoma and prostate cancer, and breast cancer, due to all solid malignancy. Moreover, zoledronate possesses diverse anti-osteosarcoma properties and may have potential to become an adjunctive treatment for high-grade osteosarcoma to enhance survival rates and to obliterate complications of the chemotherapy. Herein we highlighted the pharmacology of BPs and its underlying molecular mechanisms in osteoclasts and various cancer cells. We further provided the available literature on in vitro studies to illustrate the new insights into the intracellular molecular mechanisms of zoledronate in human osteosarcoma cell lines and in vivo animal models that led to the development and regulatory approval of zoledronate in patients with human osteosarcoma. This review also addresses clinical trials to focus on the efficacy of zoledronate on human osteosarcoma.

Nobiletin in Cancer Therapy: How This Plant Derived-Natural Compound Targets Various Oncogene and Onco-Suppressor Pathways

Cancer therapy is a growing field, and annually, a high number of research is performed to develop novel antitumor drugs. Attempts to find new antitumor drugs continue, since cancer cells are able to acquire resistance to conventional drugs. Natural chemicals can be considered as promising candidates in the field of cancer therapy due to their multiple-targeting capability. The nobiletin (NOB) is a ubiquitous flavone isolated from Citrus fruits. The NOB has a variety of pharmacological activities, such as antidiabetes, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective. Among them, the antitumor activity of NOB has been under attention over recent years. In this review, we comprehensively describe the efficacy of NOB in cancer therapy. NOB induces apoptosis and cell cycle arrest in cancer cells. It can suppress migration and invasion of cancer cells via the inhibition of epithelial-to-mesenchymal transition (EMT) and EMT-related factors such as TGF-β, ZEB, Slug, and Snail. Besides, NOB inhibits oncogene factors such as STAT3, NF-κB, Akt, PI3K, Wnt, and so on. Noteworthy, onco-suppressor factors such as microRNA-7 and -200b undergo upregulation by NOB in cancer therapy. These onco-suppressor and oncogene pathways and mechanisms are discussed in this review.

Metastasis-associated gene MAPK15 promotes the migration and invasion of osteosarcoma cells via the c-Jun/MMPs pathway

Osteosarcoma (OS) is the most common and destructive primary bone malignancy to affect children and adolescents. Metastases remain the primary cause of death in patients with OS. In the present study, weight gene co-expressed network analysis (WGCNA) and differentially-expressed gene analysis were used to identify key genes associated with the metastasis of OS. Reverse transcription-quantitative PCR and immunohistochemical staining were then used to detect the expression levels of these key genes in OS tissues, and to determine the hub genes of interest. Wound-healing and transwell assays, in addition to a lung metastasis model, were used to detect the effects of the hub genes on OS cell proliferation and metastasis in vitro and in vivo. Using WGCNA and differential expression analysis, deleted in lung and esophageal cancer protein 1 (DLEC1), Forkhead box J1 (FOXJ1) and mitogen-activated protein kinase 15 (MAPK15) were predicted to be key metastasis-associated genes, and highly expressed in metastatic OS tissues; among them, the protein and mRNA expression levels of MAPK15 were most significantly increased in our OS tissues from patients who exhibited metastases at diagnosis, and thus MAPK15 was determined to be a metastasis-associated hub gene to further study. Furthermore, inhibiting MAPK15 expression significantly decreased OS cell metastasis in vitro and in vivo, as well as suppressing c-Jun/matrix metalloproteinase (MMP)-associated pathways. Overexpression of MAPK15 activated the c-Jun/MMPs pathway and promoted OS cell metastasis, while inhibition of c-Jun blocked this effect. Taken together, MAPK15 was indicated to be an OS metastasis-associated gene, and was confirmed to promote the migration and invasion of OS cells via the c-Jun/MMP pathway. MAPK15 may therefore be an effective target for the treatment of OS.

Nobiletin, a citrus polymethoxyflavone, enhances the effects of bicalutamide on prostate cancer cells via down regulation of NF-κB, STAT3, and ERK activation

Natural products have shown potential to be combined with current cancer therapies to improve patient outcomes. Nobiletin (NBT) is a citrus polymethoxyflavone and has been shown to exert an anticancer effect in various cancer cells. We investigated the effects and mechanisms of NBT in combination with bicalutamide (BCT), a commonly used anti-androgen drug in prostate cancer therapy, on prostate cancer cells. Our results demonstrate that the combined treatment with NBT and BCT produces an enhanced inhibitory effect on the growth of prostate cancer cells compared to either compound alone. The synergistic action of NBT and BCT was confirmed using isobologram analysis. Moreover, this study has shown that NBT and BCT synergistically inhibited colony formation and migration as well as induced apoptosis. Mechanistic studies demonstrate that NBT and BCT combination reduced key cellular signaling regulators including: p-Erk/Erk, p-STAT3/STAT3 and NF-κB. Overall, these results suggest that NBT combination with BCT may be an effective treatment for prostate cancer.

Tomatidine Represses Invasion and Migration of Human Osteosarcoma U2OS and HOS Cells by Suppression of Presenilin 1 and c-Raf-MEK-ERK Pathway

Osteosarcoma, which is the most prevalent malignant bone tumor, is responsible for the great majority of bone cancer-associated deaths because of its highly metastatic potential. Although tomatidine is suggested to serve as a chemosensitizer in multidrug-resistant tumors, the anti-metastatic effect of tomatidine in osteosarcoma is still unknown. Here, we tested the hypothesis that tomatidine suppresses migration and invasion, features that are associated with metastatic process in human osteosarcoma cells and also investigate its underlying pathway. Tomatidine, up to 100 μM, without cytotoxicity, inhibited the invasion and migration capabilities of human osteosarcoma U2OS and HOS cells and repressed presenilin 1 (PS-1) expression of U2OS cells. After the knockdown of PS-1, U2OS and HOS cells’ biological behaviors of cellular invasion and migratory potential were significantly reduced. While tomatidine significantly decreased the phosphorylation of c-Raf, mitogen/extracellular signal-regulated kinase (MEK), and extracellular signal-regulated protein kinase (ERK)1/2 in U2OS cells, no obvious influences on p-Jun N-terminal kinase, p38, and Akt, including their phosphorylation, were observed. In ERK 1 silencing U2 OS cells, tomatidine further enhanced the decrease of their migratory potential and invasive activities. We conclude that both PS-1 derived from U2OS and HOS cells and the c-Raf–MEK–ERK pathway contribute to cellular invasion and migration and tomatidine could inhibit the phenomenons. These findings indicate that tomatidine might be a potential candidate for anti-metastasis treatment of human osteosarcoma.

Sudachitin, a polymethoxyflavone from Citrus sudachi, induces apoptosis via the regulation of MAPK pathways in human keratinocyte HaCaT cells

Although we recently reported that sudachitin (5,7,4'-trihydroxy-6,8,3'-trimethoxyflavone), a polymethoxyflavone isolated from the peel of Citrus sudachi, can induce apoptosis in human keratinocyte HaCaT cells, the mechanism underlying its action remains unclear. In this study, we explored the mechanisms underlying sudachitin-induced apoptosis in HaCaT cells. Sudachitin activated p38MAPK and inhibited ERK1/2, whereas another polymethoxyflavone, nobiletin (5,6,7,8,3',4'-hexamethoxyflavone), activated ERK1/2. The p38MAPK inhibitor SB203580 significantly attenuated sudachitin-induced heat shock protein 27 phosphorylation, downstream of p38MAPK, and subsequent apoptosis, indicating that sudachitin induces apoptosis via the p38MAPK pathway. Additionally, sudachitin inhibited serum- and EGF-stimulated Raf-1-ERK1/2 activation, and blocked EGF-induced cell migration and proliferation in HaCaT cells. These results suggest that small structural differences in polymethoxyflavones can induce different cellular responses by altering the regulation of MAPK activities and that sudachitin may be a potential candidate for developing new drugs for skin diseases such as psoriasis.

The tetraspanin CD81 mediates the growth and metastases of human osteosarcoma

PURPOSE

CD81 is a member of the tetraspanin family of membrane proteins. Recently, it has been shown that CD81 may be involved in cancer cell proliferation and metastasis. As yet, however, there have been few reports on the expression and role of CD81 in osteosarcoma.

METHODS

The expression of CD81 was investigated in human osteoblast cell line hFOB1.19 and in human osteosarcoma cell lines Saos2, MG63 and 143B. The expression of CD81 was inhibited in osteosarcoma cells using siRNA after which cell proliferation, migration and invasion were assessed. We also used Western blotting to investigate the phosphorylation status of Akt, Erk, JNK and p38, and measured the expression of MMP-2, MMP-9 and MT1-MMP. In addition, we used a CRISPR/Cas9 system to stably knock out CD81 expression in 143B cells, transplanted the cells into mice, and assessed tumor formation and lung metastasis in these mice compared to those in the control group.

RESULTS

We found that CD81 was expressed in the human osteoblast cell line and in all osteosarcoma cell lines tested. The osteosarcoma cell line 143B exhibited a particularly high level of expression. In addition, we found that osteosarcoma cell proliferation, migration and invasion were decreased after CD81 inhibition, and that the phosphorylation of Akt and Erk was suppressed. Also, the expression levels of MMP-2, MMP-9 and MT1-MMP were found to be suppressed, with MMP-9 showing the greatest suppression. In vivo, we found that mice transplanted with CD81 knockout 143B cells exhibited significantly less tumor formation and lung metastasis than mice in the control group.

CONCLUSION

Based on our findings we conclude that inhibition of CD81 suppresses intracellular signaling and reduces tumorigenesis and lung metastasis in osteosarcoma cells.

Nobiletin and Derivatives: Functional Compounds from Citrus Fruit Peel for Colon Cancer Chemoprevention

The search for effective methods of cancer treatment and prevention has been a continuous effort since the disease was discovered. Recently, there has been increasing interest in exploring plants and fruits for molecules that may have potential as either adjuvants or as chemopreventive agents against cancer. One of the promising compounds under extensive research is nobiletin (NOB), a polymethoxyflavone (PMF) extracted exclusively from citrus peel. Not only does nobiletin itself exhibit anti-cancer properties, but its derivatives are also promising chemopreventive agents; examples of derivatives with anti-cancer activity include 3'-demethylnobiletin (3'-DMN), 4'-demethylnobiletin (4'-DMN), 3',4'-didemethylnobiletin (3',4'-DMN) and 5-demethylnobiletin (5-DMN). In vitro studies have demonstrated differential efficacies and mechanisms of NOB and its derivatives in inhibiting and killing of colon cancer cells. The chemopreventive potential of NOB has also been well demonstrated in several in vivo colon carcinogenesis animal models. NOB and its derivatives target multiple pathways in cancer progression and inhibit several of the hallmark features of colorectal cancer (CRC) pathophysiology, including arresting the cell cycle, inhibiting cell proliferation, inducing apoptosis, preventing tumour formation, reducing inflammatory effects and limiting angiogenesis. However, these substances have low oral bioavailability that limits their clinical utility, hence there have been numerous efforts exploring better drug delivery strategies for NOB and these are part of this review. We also reviewed data related to patents involving NOB to illustrate the extensiveness of each research area and its direction of commercialisation. Furthermore, this review also provides suggested directions for future research to advance NOB as the next promising candidate in CRC chemoprevention.

Identification of compounds that rescue otic and myelination defects in the zebrafish adgrg6 (gpr126) mutant

Adgrg6 (Gpr126) is an adhesion class G protein-coupled receptor with a conserved role in myelination of the peripheral nervous system. In the zebrafish, mutation of adgrg6 also results in defects in the inner ear: otic tissue fails to down-regulate versican gene expression and morphogenesis is disrupted. We have designed a whole-animal screen that tests for rescue of both up- and down-regulated gene expression in mutant embryos, together with analysis of weak and strong alleles. From a screen of 3120 structurally diverse compounds, we have identified 68 that reduce versican b expression in the adgrg6 mutant ear, 41 of which also restore myelin basic protein gene expression in Schwann cells of mutant embryos. Nineteen compounds unable to rescue a strong adgrg6 allele provide candidates for molecules that may interact directly with the Adgrg6 receptor. Our pipeline provides a powerful approach for identifying compounds that modulate GPCR activity, with potential impact for future drug design.

Pathological and therapeutic aspects of matrix metalloproteinases: Implications in osteosarcoma

Osteosarcoma (OS) is one of the most common malignant bone tumors in children and adolescents, and the eighth leading form of childhood cancer. Matrix metalloproteinases (MMPs) are proteolytic enzymes implicated in certain cancers including OS. In this review, we discuss the mechanism of actions of MMPs in progression of OS, and the therapeutic use of MMPs inhibitors in the treatment of OS with subsequent clinical studies and future management. The expression of MMPs is upregulated in cancer cells by a variety of cytokines and growth factors, and upregulation of MMPs induces degradation of the extracellular matrix that contributes to cell proliferation by releasing growth factors. MMPs promote the detachment and migration of endothelial cells, cross the basement membrane as well as invade the surrounding lymphatic vessels and causes cancer metastasis. The use of selective MMP inhibitors with limited side effects might be promising therapeutic strategy in the treatment of OS. More clinical trials are necessary to evaluate the role of selective MMPs inhibitors in the prevention and treatment of OS along with their assessment of toxicity.

Nobiletin Protects against Systemic Inflammation-Stimulated Memory Impairment via MAPK and NF-κB Signaling Pathways

Neuroinflammation has been intensively demonstrated to be related to various neurodegenerative diseases including Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Alzheimer's disease (AD). A natural polymethoxylated flavone, nobiletin (NOB) has been reported to alleviate oxidative stress, insulin resistance, and obesity. In this study, we evaluated the protection effects of NOB on neuroinflammation and memory deficit. Three-month mice were administrated with NOB by oral gavage every day for 6 weeks (100 mg/kg/day); subsequently mice were injected intraperitoneally with lipopolysaccharide (LPS) for 7 days. Results of behavioral tests revealed that NOB dramatically ameliorated LPS-triggered memory deficit regarding synaptic dysfunctions and neuronal loss. Also, NOB suppressed the microglial activation and proinflammatory cytokine secretion, such as COX-2, IL-1β, TNF-α, and iNOS. Similarly, upon LPS stimulation, pretreatment NOB diminished the secretion of the proinflammatory cytokines in BV-2 microglia cells by exposure to LPS via modulating MAPKs, PI3K/AKT, and NF-κB signaling pathways. In addition, NOB alleviated LPS-amplified redox imbalance, disturbance of mitochondrial membrane potential (MMP), and dampening of the expression of protein related to mitochondrial respiration. The present study provides compelling evidence that NOB decreased LPS-stimulated neuroinflammation and memory impairment through maintaining cellular oxidative balance and blocking the NF-κB transcriptional pathway, illustrating that the nutritional compound NOB may serve as a potential approach to alleviate neuroinflammation-related diseases.

A critical review on anti-angiogenic property of phytochemicals

Angiogenesis, a process involved in neovascularization, has been found to be associated with several metabolic diseases like cancer, retinopathy etc. Thus, currently, the focus on anti-angiogenic therapy for treatment and prevention of diseases has gained significant attention. Currently available Food and Drug Administration (FDA) approved drugs are targeting either vascular endothelial growth factor or it's receptor, but in the long term, these approaches were shown to cause several side effects and the chances of developing resistance to these drugs is also high. Therefore, identification of safe and cost-effective anti-angiogenic molecules is highly imperative. Over the past decades, dietary based natural compounds have been studied for their anti-angiogenic potential which provided avenues in improving the angiogenesis based therapy. In this review, major emphasis is given to the molecular mechanism behind anti-angiogenic effect of natural compounds from dietary sources.

Small G protein signalling modulator 2 (SGSM2) is involved in oestrogen receptor-positive breast cancer metastasis through enhancement of migratory cell adhesion via interaction with E-cadherin

The function of small G protein signalling modulators (SGSM1/2/3) in cancer remains unknown. Our findings demonstrated that SGSM2 is a plasma membrane protein that strongly interacted with E-cadherin/β-catenin. SGSM2 downregulation enhanced the phosphorylation of focal adhesion kinase (FAK; Y576/577), decreased the expression of epithelial markers such as E-cadherin, β-catenin, and Paxillin, and increased the expression of Snail and Twist-1, which reduced cell adhesion and promoted cancer cell migration. Oestrogen and fibronectin treatment was found to promote the colocalization of SGSM2 at the leading edge with phospho-FAK (Y397). The BioGRID database showed that SGSM2 potentially interacts with cytoskeleton remodelling and cell-cell junction proteins. These evidences suggest that SGSM2 plays a role in modulating cell adhesion and cytoskeleton dynamics during cancer migration.

Nobiletin inhibits hypoxia-induced epithelial-mesenchymal transition in renal cell carcinoma cells

Hypoxia is a universal characteristic of solid tumor and involving cancer metastasis via epithelial-mesenchymal transition (EMT). Nobiletin (3',4',5,6,7,8-hexamethoxyflavone), a dietary polymethoxylated flavonoid found in citrus fruits, has been reported to have anticancer effects. However, the possible role of nobiletin in renal cell carcinoma (RCC) remains unclear. Thus, the aim of this study was to identify the effect of nobiletin on hypoxia-induced EMT in RCC cells. We found that nobiletin significantly inhibited the migration and invasion induced by hypoxia in RCC cells. In addition, nobiletin reversed the hypoxia-induced EMT process in RCC cells. Furthermore, nobiletin suppressed the activation of NF-κB and Wnt/β-catenin signaling pathways in hypoxia-stimulated RCC cells. In conclusion, these findings demonstrate that nobiletin inhibits hypoxia-induced EMT in human RCC cells via the inactivation of the NF-κB and Wnt/β-catenin signaling pathways.

Effect of Nobiletin on Experimental Model of Epilepsy

Background

The effects of nobiletin, a plant-derived flavonoid was examined against pentylenetetrazole (PTZ)-induced seizures. The study also aimed to assess whether nobiletin potentiated the effects of antiepileptic drug clonazepam (CZP).

Methods

PTZ (92 mg/kg, subcutaneous) was used to induce seizures in mice. Treatment groups (n = 18/group) received nobiletin (12.5, 25, or 50 mg/kg) via oral gavage for 6 consecutive days and 45 min prior to PTZ injection. CZP (0.015-2.0 mg/kg) was administered 15 min prior to PTZ. Skeletal muscle strength was assessed by measuring grip strength and Chimney test was performed to study the motor performance in animals. TUNEL assay was done to study neuro-apoptosis. RT-PCR and Western blot analysis were performed for assessment of mRNA and protein expressions.

Results

Nobiletin and CZP improved muscle strength and motor coordination and reduced seizure severity significantly. The administration of nobiletin and CZP, individually or in combination, downregulated seizure-induced increases in apoptotic cell count and apoptotic protein expression, modulated the expression of gamma-aminobutyric acid (GABA)A and glutamate decarboxylase 65 and restored the glutamate/GABA balance. Nobiletin and CZP administration significantly upregulated phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling.

Conclusion

Nobiletin exerted protective effect against seizures by regulating signaling pathways associated with epileptogenesis and potentiated the effects of CZP.

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1-Disrupting Peptides

Protein phosphatase‐1 (PP1)‐disrupting peptides (PDPs) are selective chemical modulators of PP1 that liberate the active PP1 catalytic subunit from regulatory proteins; thus allowing the dephosphorylation of nearby substrates. We have optimized the original cell‐active PDP3 for enhanced stability, and obtained insights into the chemical requirements for stabilizing this 23‐mer peptide for cellular applications. The optimized PDP‐Nal was used to dissect the involvement of PP1 in the MAPK signaling cascade. Specifically, we have demonstrated that, in human osteosarcoma (U2OS) cells, phosphoMEK1/2 is a direct substrate of PP1, whereas dephosphorylation of phosphoERK1/2 is indirect and likely mediated through enhanced tyrosine phosphatase activity after PDP‐mediated PP1 activation. Thus, as liberators of PP1 activity, PDPs represent a valuable tool for identifying the substrates of PP1 and understanding its role in diverse signaling cascades.

Melatonin attenuates osteosarcoma cell invasion by suppression of C-C motif chemokine ligand 24 through inhibition of the c-Jun N-terminal kinase pathway

Osteosarcoma, with its high metastatic potential, is the most prevalent malignant bone tumor in children and adolescents. Melatonin possesses multiple tumor-suppressing properties for a myriad of tumors, but little is known about the effects of melatonin on osteosarcoma metastasis. In this study, we demonstrated that melatonin elicited very low cytotoxicity and significantly inhibited cellular motility, migration, and invasion in human osteosarcoma U2OS and HOS cells. Moreover, using RNA sequencing technology, we revealed that melatonin repressed C-C motif chemokine ligand 24 (CCL24) gene expression in U2OS cells. Manipulation of CCL24 levels influenced the motility of osteosarcoma cells as cell migration and invasion were enhanced by the addition of recombinant human CCL24 and attenuated by the silencing of CCL24. Moreover, melatonin increased and decreased the activation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) 1/2, respectively, in a dose-dependent manner in U2OS and HOS cells while exerting no evident influence on the level and activation of p38, Akt, FAK, steroid receptor coactivator, or Raf. In further functional experiments, the use of JNK inhibitors (SP600125 and DN-JNK) confirmed that the pharmaceutic inhibition of JNK augmented the melatonin-mediated CCL24 suppression and migration of U2OS cells. Overall, our results revealed that melatonin attenuated chemokine CCL24 levels through inhibition of the JNK pathway to hinder human osteosarcoma cell invasion, thereby highlighting the therapeutic potential of melatonin for osteosarcoma metastasis.

PBN11-8, a Cytotoxic Polypeptide Purified from Marine Bacillus, Suppresses Invasion and Migration of Human Hepatocellular Carcinoma Cells by Targeting Focal Adhesion Kinase Pathways

The development of antitumor drugs has attracted cancer researchers and the identification of novel antitumor lead compounds is certainly of great interest. The fermentation broth of Bacillus sp. N11-8, which was isolated from the Antarctic waters, showed cytotoxicity towards different cells. A cytotoxic polypeptide, PBN11-8, was purified from the fermentation broth of Bacillus sp. N11-8 using ultrafiltration, ammonium sulfate precipitation, anion exchange liquid chromatography and high performance liquid chromatography (HPLC). Cloning and sequence analysis showed that PBN11-8 polypeptide (MW: ~19 kDa by the electrospray-ionization (ESI)) displayed high similarity with peptidase M84 from Bacillus pumilus. PBN11-8 possessed moderate cytotoxicity towards several cancer cell lines with IC₅₀ values of 1.56, 1.80, 1.57, and 1.73 µg/mL against human hepatocellular carcinoma cell line BEL-7402, human renal clear cell adenocarcinoma cell line 786-0, human hepatocellular carcinoma cell line HepG2, and human pancreatic cancer cell line Panc-28, respectively. Moreover, the polypeptide displayed weak cytotoxicity towards normal cell line renal tubular epithelial cell line HK2 and human normal liver cell line L02 cells. Wound healing migration and Transwell experiments demonstrate that PBN11-8 could inhibit the migration and invasion of BEL-7402. Further investigation revealed that PBN11-8 suppresses focal adhesion kinase (FAK)-mediated adhesion, migration, and invasion by disturbing FAK/extracellular regulated protein kinases (ERK) signaling and matrix metalloproteinase-2(MMP-2) and matrix metalloproteinase-9 (MMP-9) in BEL-7402 cells. Thus, PBN11-8 represents a potential novel anti-cancer lead compound.

Fisetin induces apoptosis through mitochondrial apoptosis pathway in human uveal melanoma cells

Fisetin, a diatery flavonoid, been reported that possess anticancer effects in various cancers. The purpose of the study was to investigate the antitumor effects of fisetin in cultured uveal melanoma cell lines and compared with normal retinal pigment epithelial (RPE) cells. MTT assay was used for evaluating cytotoxic effects of fisetin. Flow cytometry study was used for the determination of apoptosis. JC-1 fluorescent reader was used to determine mitochondrial transmembrane potential changes. The results shown that fisetin dose-dependently decreased the cell viability of uveal melanoma cells but not influenced the cell viability of RPE cells. Apoptosis of uveal melanoma cells was induced by fisetin efficiently. Fisetin inhibited antiapoptotic Bcl-2 family proteins and damaged the mitochondrial transmembrane potential. The levels of proapoptotic Bcl-2 proteins, cytochrome c, and various caspase activities were increased by fisetin. In conclusion, fisetin induces apoptosis of uveal melanoma cells selectively and may be a promising agent to be explored for the treatment of uveal melanoma.

Antimetastatic potentials of salvianolic acid A on oral squamous cell carcinoma by targeting MMP-2 and the c-Raf/MEK/ERK pathway

The metastasis of oral squamous cell carcinoma (OSCC) is one of the most important causes of cancer-related deaths. Thus, various therapeutic strategies have been developed to prevent the metastasis of OSCC. Salvianolic acid A (SAA), a traditional Chinese medicine, has antithrombosis, antiplatelet, anti-inflammation, and antitumor activities. Here, we provide molecular evidence indicating that SAA exerts its antimetastatic effects by markedly inhibiting the invasion and migration of oral squamous SCC-9 and SCC-25 cells. SCC-9 and SCC-25 cells were treated with various concentrations of SAA to further investigate the precise involvement of SAA in cancer metastasis. The results of zymography, and Western blotting indicated that SAA treatment may decrease matrix metallopoteinase-2 (MMP-2) expression. SAA also inhibited p-c-Raf, p-MEK1/2, and p-ERK1/2 protein expression. In addition, treating SCC-9 cells with U0126, a MEK-specific inhibitor, decreased MMP-2 expression and concomitantly inhibited cell migration. Our findings suggested that SAA inhibits the invasion and migration of OSCC by inhibiting the c-Raf/MEK/ERK pathways that control MMP-2 expression. Our findings provide new insights into the molecular mechanisms that underlie the antimetastatic effect of SAA and are thus valuable for the development of treatment strategies for metastatic OSCC.

Alpha-mangostin induces apoptosis through activation of reactive oxygen species and ASK1/p38 signaling pathway in cervical cancer cells

Alpha-mangostin, a natural xanthonoid, has been reported to possess the anti-cancer property in various types of human cancer. However, its effects and mechanism of α-mangostin in cervical cancer remain unclear. We found that α-mangostin effectively inhibited cell viability, resulted in loss of mitochondrial membrane potential (MMP), release of cytochrome C, increase of Bax, decrease of Bcl-2, and activation of caspase-9/caspase-3 cascade in cervical cancer cells. Alpha-mangostin elevated the contents of reactive oxygen species (ROS) to activate p38. Disrupting ASK1/p38 signaling pathway by a specific inhibitor of p38, or by the siRNAs against ASK1, MKK3/6, or p38, significantly abolished α-mangostin-induced cell death and apoptotic responses. Moreover, α-mangostin also repressed tumor growth in accordance with increased levels of p-ASK1, p-p38, cleaved-PARP and cleaved-caspase-3 in the tumor mass from the mouse xenograft model of cervical cancer. In the current study, we provided first evidence to demonstrate that dietary antioxidant α-mangostin could inhibit the tumor growth of cervical cancer cells through enhancing ROS amounts to activate ASK1/p38 signaling pathway and damage the integrity of mitochondria and thereby induction of apoptosis in cervical cancer cells.

MMP-11 promoted the oral cancer migration and Fak/Src activation

Matrix metalloproteinase-11 (MMP-11) has been observed in most invasive human carcinomas. The current study investigated the association between the clinicopathological characteristics and MMP-11 expression in oral squamous cell carcinoma (OSCC) patients. Immunohistochemistry (IHC) staining was performed to assess MMP-11 expression in 279 patients with OSCC. In addition, the metastatic effects of the MMP-11 overexpression on the OSCC cells were also investigated. We found that MMP-11 expression was present in 118/279 (42.3%) cases and expression of MMP-11 was associated with higher incidence of lymph node metastasis and worse grade of tumor differentiation. Importantly, OSCC patients with strong expression of MMP-11 had a significantly lower survival rate (p=0.010). Furthermore, MMP-11 overexpression in OSCC cells increased in vitro cell migration. Mechanistically, MMP-11 increased the cell motility of OSCC cells through focal adhesion kinase/Src kinase (FAK/Src) pathway. In conclusion, our results revealed that the MMP-11 expression in OSCC samples can predict the progression, especially lymph node metastasis, and the survival of OSCC patients in Taiwan.

Speckle-Type POZ Protein Down-Regulates Matrix Metalloproteinase 2 Expression via Sp1/PI3K/Akt Signaling Pathway in Colorectal Cancer

BACKGROUND

Elevated expression of matrix metalloproteinases (MMPs) is correlated with invasion and metastasis of colorectal cancer (CRC). Recently, a previous study has suggested that speckle-type POZ protein (SPOP) could inhibit cancer cell proliferation and migration through down-regulation of MMP2 and MMP7, with a mechanism remaining unknown.

AIM

In this study, we, by using both CRC cells and normal colorectal cells, aimed to investigate the causal relationship between SPOP and MMP2, as well as the potential signaling pathways.

METHODS

The causal relationship between SPOP and MMP2 was determined by both RT-PCR and Western blot in cells with SPOP expression or siRNA interference. The signaling pathway involved in MMP2 down-regulation by SPOP was subsequently identified by determination on the expression and phosphorylation of key signaling pathway proteins. Transcription factor involving in this MMP2 regulation was identified by determination on expression, phosphorylation, and nuclear translocation of key transcription factors.

RESULTS

SPOP overexpression could significantly decrease MMP2 expression, while the knockdown of SPOP, in contrast, resulted in enhanced MMP2 level. Measurement of expression and phosphorylation of key signaling pathway proteins revealed that SPOP could inhibit PI3K and p-Akt level. Further tests on transcription factors showed that SPOP could inhibit SP1 phosphorylation and nuclear translocation.

CONCLUSIONS

SPOP could down-regulate MMP2 expression in CRC, and this regulation is mediated by inhibiting SP1 phosphorylation and nuclear translocation through PI3K/Akt signaling pathway. Our findings in this study provide understanding of MMP2 regulation in CRC and may also shed lights on the development of anti-CRC treatments.