Celastrol Attenuates the Invasion and Migration and Augments the Anticancer Effects of Bortezomib in a Xenograft Mouse Model of Multiple Myeloma

TRAIL and Celastrol Combinational Treatment Suppresses Proliferation, Migration, and Invasion of Human Glioblastoma Cells via Targeting Wnt/β-catenin Signaling Pathway

OBJECTIVE

To investigate the mechanistic basis for the anti-proliferation and anti-invasion effect of tumor necrosis factor-related apoptosis-induced ligand (TRAIL) and celastrol combination treatment (TCCT) in glioblastoma cells.

METHODS

Cell counting kit-8 was used to detect the effects of different concentrations of celastrol (0-16 µmol/L) and TRAIL (0-500 ng/mL) on the cell viability of glioblastoma cells. U87 cells were randomly divided into 4 groups, namely control, TRAIL (TRAIL 100 ng/mL), Cel (celastrol 0.5 µmol/L) and TCCT (TRAIL 100 ng/mL+ celastrol 0.5 µmol/L). Cell proliferation, migration, and invasion were detected by colony formation, wound healing, and Transwell assays, respectively. Quantitative reverse transcription polymerase chain reaction and Western blotting were performed to assess the levels of epithelial-mesenchymal transition (EMT) markers (zona occludens, N-cadherin, vimentin, zinc finger E-box-binding homeobox, Slug, and β-catenin). Wnt pathway was activated by lithium chloride (LiCl, 20 mol/L) and the mechanism for action of TCCT was explored.

RESULTS

Celastrol and TRAIL synergistically inhibited the proliferation, migration, invasion, and EMT of U87 cells (P<0.01). TCCT up-regulated the expression of GSK-3β and down-regulated the expression of β-catenin and its associated proteins (P<0.05 or P<0.01), including c-Myc, Cyclin-D1, and matrix metalloproteinase (MMP)-2. In addition, LiCl, an activator of the Wnt signaling pathway, restored the inhibitory effects of TCCT on the expression of β-catenin and its downstream genes, as well as the migration and invasion of glioblastoma cells (P<0.05 or P<0.01).

CONCLUSIONS

Celastrol and TRAIL can synergistically suppress glioblastoma cell migration, invasion, and EMT, potentially through inhibition of Wnt/β-catenin pathway. This underlies a novel mechanism of action for TCCT as an effective therapy for glioblastoma.

Hypoxia signaling in hepatocellular carcinoma: Challenges and therapeutic opportunities

Hepatocellular carcinoma (HCC) is one of the most common cancers with a relatively high cancer-related mortality. The uncontrolled proliferation of HCC consumes a significant amount of oxygen, causing the development of a hypoxic tumor microenvironment (TME). Hypoxia-inducible factors (HIFs), crucial regulators in the TME, activate several cancer hallmarks leading to the hepatocarcinogenesis of HCC and resistance to current therapeutics. As such, HIFs and their signaling pathways have been explored as potential therapeutic targets for the future management of HCC. This review discusses the current understanding of the structure and function of HIFs and their complex relationship with the various cancer hallmarks. To address tumor hypoxia, this review provides an insight into the various potential novel therapeutic agents for managing HCC, such as hypoxia-activated prodrugs, HIF inhibitors, nanomaterials, antisense oligonucleotides, and natural compounds, that target HIFs/hypoxic signaling pathways in HCC. Because of HCC's relatively high incidence and mortality rates in the past decades, greater efforts should be put in place to explore novel therapeutic approaches to improve the outcome for HCC patients.

CXC chemokine receptor 4 (CXCR4) blockade in cancer treatment

CXC chemokine receptor type 4 (CXCR4) is a member of the G protein-coupled receptors (GPCRs) superfamily and is specific for CXC chemokine ligand 12 (CXCL12, also known as SDF-1), which makes CXCL12/CXCR4 axis. CXCR4 interacts with its ligand, triggering downstream signaling pathways that influence cell proliferation chemotaxis, migration, and gene expression. The interaction also regulates physiological processes, including hematopoiesis, organogenesis, and tissue repair. Multiple evidence revealed that CXCL12/CXCR4 axis is implicated in several pathways involved in carcinogenesis and plays a key role in tumor growth, survival, angiogenesis, metastasis, and therapeutic resistance. Several CXCR4-targeting compounds have been discovered and used for preclinical and clinical cancer therapy, most of which have shown promising anti-tumor activity. In this review, we summarized the physiological signaling of the CXCL12/CXCR4 axis and described the role of this axis in tumor progression, and focused on the potential therapeutic options and strategies to block CXCR4.

Bioactive Phytoconstituents and Their Therapeutic Potentials in the Treatment of Haematological Cancers: A Review

Haematological (blood) cancers are the cancers of the blood and lymphoid forming tissues which represents approximately 10% of all cancers. It has been reported that approximately 60% of all blood cancers are incurable. Despite substantial improvement in access to detection/diagnosis, chemotherapy and bone marrow transplantation, there is still high recurrence and unpredictable but clearly defined relapses indicating that effective therapies are still lacking. Over the past two decades, medicinal plants and their biologically active compounds are being used as potential remedies and alternative therapies for the treatment of cancer. This is due to their anti-oxidant, anti-inflammatory, anti-mutagenic, anti-angiogenic, anti-cancer activities and negligible side effects. These bioactive compounds have the capacity to reduce proliferation of haematological cancers via various mechanisms such as promoting apoptosis, transcription regulation, inhibition of signalling pathways, downregulating receptors and blocking cell cycle. This review study highlights the mechanistic and beneficial effects of nine bioactive compounds (quercetin, ursolic acid, fisetin, resveratrol, epigallocatechin gallate, curcumin, gambogic acid, butein and celastrol) as potential remedies for chemoprevention of haematological cancers. The study provides useful insights on the effectiveness of the use of bioactive compounds from plants for chemoprevention of haematological cancers.

Celastrol as an emerging anticancer agent: Current status, challenges and therapeutic strategies

Celastrol is a pentacyclic triterpenoid extracted from the traditional Chinese medicine Tripterygium wilfordii Hook F., which has multiple pharmacological activities. In particular, modern pharmacological studies have demonstrated that celastrol exhibits significant broad-spectrum anticancer activities in the treatment of a variety of cancers, including lung cancer, liver cancer, colorectal cancer, hematological malignancies, gastric cancer, prostate cancer, renal carcinoma, breast cancer, bone tumor, brain tumor, cervical cancer, and ovarian cancer. Therefore, by searching the databases of PubMed, Web of Science, ScienceDirect and CNKI, this review comprehensively summarizes the molecular mechanisms of the anticancer effects of celastrol. According to the data, the anticancer effects of celastrol can be mediated by inhibiting tumor cell proliferation, migration and invasion, inducing cell apoptosis, suppressing autophagy, hindering angiogenesis and inhibiting tumor metastasis. More importantly, PI3K/Akt/mTOR, Bcl-2/Bax-caspase 9/3, EGFR, ROS/JNK, NF-κB, STAT3, JNK/Nrf2/HO-1, VEGF, AR/miR-101, HSF1-LKB1-AMPKα-YAP, Wnt/β-catenin and CIP2A/c-MYC signaling pathways are considered as important molecular targets for the anticancer effects of celastrol. Subsequently, studies of its toxicity and pharmacokinetic properties showed that celastrol has some adverse effects, low oral bioavailability and a narrow therapeutic window. In addition, the current challenges of celastrol and the corresponding therapeutic strategies are also discussed, thus providing a theoretical basis for the development and application of celastrol in the clinic.

Potential function of loliolide as a novel blocker of epithelial-mesenchymal transition in colorectal and breast cancer cells

Loliolide (LL), a naturally occurring monoterpenoid lactone isolated from Vicia tenuifolia Roth, can exhibit numerous pharmacological effects such as those related to anti-Parkinson, anti-oxidant, anti-cholinesterase, and anti-depressant. Epithelial-mesenchymal transition (EMT) plays a pivotal role in regulating tumor metastasis. CXCR4 and CXCR7 are G-protein-coupled receptors (GPRs), which can be stimulated by CXCL12. CXCL12/CXCR4/CXCXR7 axis can cause activation of multiple pathways including MAPKs, JAK/STAT pathway, and manganese superoxide dismutase (MnSOD) signaling. These events can initiate EMT process and induce cell invasion and migration. Here, we investigated whether LL can modulate the CXCR4 and CXCR7 and EMT process in colon cancer and breast cancer cells. We found that LL suppressed levels of CXCR4 and CXCR7, and exerted an inhibitory effect on these chemokines even after stimulation by CXCL12. LL suppressed expression of MnSOD and mesenchymal markers, whereas induced epithelial markers. In addition, LL significantly attenuated cellular invasion, migration, and metastasis. We noted that LL inhibited CXCR4/7 and EMT process even after stimulation of CXCL12 and MnSOD overexpression. Therefore, in this study, we provide evidences that targeting CXCR4/7 and MnSOD could inhibit the invasion, migration, and metastasis of cancer cells as well as negatively regulate the EMT process. Overall, our study suggested that LL might act as a potent suppressor of EMT process against colon and breast cancer cells.

Disruption of Proteostasis by Natural Products and Synthetic Compounds That Induce Pervasive Unfolding of Proteins: Therapeutic Implications

Exposure of many cancer cells, including multiple myeloma cells, to cytotoxic concentrations of natural products celastrol and withaferin A or synthetic compounds of the IHSF series resulted in denaturation of a luciferase reporter protein. Proteomic analysis of detergent-insoluble extract fractions from HeLa-derived cells revealed that withaferin A, IHSF058 and IHSF115 caused denaturation of 915, 722 and 991 of 5132 detected cellular proteins, respectively, of which 440 were targeted by all three compounds. Western blots showed that important fractions of these proteins, in some cases approaching half of total protein amounts, unfolded. Relatively indiscriminate covalent modification of target proteins was observed; 1178 different proteins were modified by IHSF058. Further illustrating the depth of the induced proteostasis crisis, only 13% of these proteins detectably aggregated, and 79% of the proteins that aggregated were not targets of covalent modification. Numerous proteostasis network components were modified and/or found in aggregates. Proteostasis disruption caused by the study compounds may be more profound than that mediated by proteasome inhibitors. The compounds act by a different mechanism that may be less susceptible to resistance development. Multiple myeloma cells were particularly sensitive to the compounds. Development of an additional proteostasis-disrupting therapy of multiple myeloma is suggested.

Emerging RNA-Based Therapeutic and Diagnostic Options: Recent Advances and Future Challenges in Genitourinary Cancers

Renal cell carcinoma, bladder cancer, and prostate cancer are the most widespread genitourinary tumors. Their treatment and diagnosis have significantly evolved over recent years, due to an increasing understanding of oncogenic factors and the molecular mechanisms involved. Using sophisticated genome sequencing technologies, the non-coding RNAs, such as microRNAs, long non-coding RNAs, and circular RNAs, have all been implicated in the occurrence and progression of genitourinary cancers. Interestingly, DNA, protein, and RNA interactions with lncRNAs and other biological macromolecules drive some of these cancer phenotypes. Studies on the molecular mechanisms of lncRNAs have identified new functional markers that could be potentially useful as biomarkers for effective diagnosis and/or as targets for therapeutic intervention. This review focuses on the mechanisms underlying abnormal lncRNA expression in genitourinary tumors and discusses their role in diagnostics, prognosis, and treatment.

Brucein D imparts a growth inhibitory effect in multiple myeloma cells by abrogating the Akt-driven signaling pathway

The Akt signaling pathway is an oncogenic cascade activated in the bone marrow microenvironment of multiple myeloma (MM) cells and contributes to their uncontrolled proliferation. Abrogation of Akt signaling has been presented as one of the prime therapeutic targets in the treatment of MM. In the present report, we have investigated the effect of Brucein D (BD) on Akt-driven signaling events in MM cells. BD (300 nM) substantially inhibited cell viability and imparted growth-inhibitory effects in U266 cells as evidenced by cell viability assays and flow cytometric analysis. Effect of BD on cell viability was evaluated by MTT assay. Apoptotic cells and cell cycle arrest by BD were analyzed by flow cytometer. The results of the TUNEL assay and western blotting showed that BD induces apoptosis of MM cells by activating caspase-8 and 9 with subsequent reduction in the expression of antiapoptotic proteins (Bcl-2, Bcl-xl, survivin, cyclin D1, COX-2, VEGF, MMP-9). Analysis of activated kinases by Phospho-Kinase Array Kit revealed that Akt, p70S6K, HSP60, p53, and WNK1 were strongly expressed in untreated cells and BD treatment reversed this effect. Using transfection experiments, AKT depletion led to a decrease in phosphorylation of Akt, mTOR, p70S6K, and WNK. However, Akt overexpression led to increase in phosphorylation of these proteins. Depletion of Akt potentiated the apoptosis-inducing effect of BD whereas overexpression displayed resistance to BD-induced apoptosis suggesting the role of Akt in chemoresistance. Taken together, BD mitigates Akt-dependent signaling pathways in MM cells to impart its anticancer activity.

Graphene oxide nanoarchitectures in cancer biology: Nano-modulators of autophagy and apoptosis

Nanotechnology is a growing field, with many potential biomedical applications of nanomedicine for the treatment of different diseases, particularly cancer, on the horizon. Graphene oxide (GO) nanoparticles can act as carbon-based nanocarriers with advantages such as a large surface area, good mechanical strength, and the capacity for surface modification. These nanostructures have been extensively used in cancer therapy for drug and gene delivery, photothermal therapy, overcoming chemotherapy resistance, and for imaging procedures. In the current review, we focus on the biological functions of GO nanoparticles as regulators of apoptosis and autophagy, the two major forms of programmed cell death. GO nanoparticles can either induce or inhibit autophagy in cancer cells, depending on the conditions. By stimulating autophagy, GO nanocarriers can promote the sensitivity of cancer cells to chemotherapy. However, by impairing autophagy flux, GO nanoparticles can reduce cell survival and enhance inflammation. Similarly, GO nanomaterials can increase ROS production and induce DNA damage, thereby sensitizing cancer cells to apoptosis. In vitro and in vivo experiments have investigated whether GO nanomaterials show any toxicity in major body organs, such as the brain, liver, spleen, and heart. Molecular pathways, such as ATG, MAPK, JNK, and Akt, can be regulated by GO nanomaterials, leading to effects on autophagy and apoptosis. These topics are discussed in this review to shed some lights towards the biomedical potential of GO nanoparticles and their biocompatibility, paving the way for their future application in clinical trials.

Nimbolide enhances the antitumor effect of docetaxel via abrogation of the NF-κB signaling pathway in prostate cancer preclinical models

Prostate cancer is the second most frequent type of cancer that affects men. Docetaxel (DTX) administration is the front-line therapy for patients with advanced prostate cancer and unfortunately, half of these patients develop resistance to DTX which could be due to its ability to activate the NF-κB pathway. The combinational effect of DTX and nimbolide on proliferation, apoptosis, activation of NF-κB, DNA binding ability of NF-κB, and expression of NF-κB-targeted gene products was investigated. The antitumor and antimetastatic effect of DTX or NL alone or in combination was also examined. The co-administration of NL and DTX resulted in a significant loss of cell viability with enhanced apoptosis in DTX-sensitive/resistant prostate cancer cells. NL abrogated DTX-triggered NF-κB activation and expression of its downstream antiapoptotic factors (survivin, Bcl-2, and XIAP). The combination of NL and DTX significantly reduced the DNA binding ability of NF-κB in both cell types. NL significantly enhanced the antitumor effect of DTX and reduced metastases in orthotopic models of prostate cancer. NL abolishes DTX-induced-NF-κB activation to counteract cell proliferation, tumor growth, and metastasis in the prostate cancer models.

Celastrol suppresses the growth of vestibular schwannoma in mice by promoting the degradation of β-catenin

Vestibular schwannoma (VS), one of characteristic tumors of neurofibromatosis type 2 (NF2), is an intracranial tumor that arises from Schwann cells of the vestibular nerve. VS results in hearing loss, tinnitus, dizziness, and even death, but there are currently no FDA-approved drugs for treatment. In this study, we established a high-throughput screening to discover effective compounds that could inhibit the viability of VS cells. Among 1019 natural products from the Korea Chemical Bank screened, we found that celastrol, a pentacyclic triterpene derived from a Tripterygium Wilfordi plant, exerted potent inhibitory effect on the viability of VS cells with an IC50 value of 0.5  µM. Celastrol (0.5, 1  µM) dose-dependently inhibited the proliferation of primary VS cells derived from VS patients. Celastrol also inhibited the growth, and induced apoptosis of two other VS cell lines (HEI-193 and SC4). Aberrant activation of Wnt/β-catenin signaling has been found in VS isolated from clinically defined NF2 patients. In HEI-193 and SC4 cells, we demonstrated that celastrol (0.1, 0.5 μM) dose-dependently inhibited TOPFlash reporter activity and protein expression of β-catenin, but not mRNA level of β-catenin. Furthermore, celastrol accelerated the degradation of β-catenin by promoting the formation of the β-catenin destruction complex. In nude mice bearing VS cell line SC4 allografts, administration of celastrol (1.25 mg · kg-1 · d-1, i.p. once every 3 days for 2 weeks) significantly suppressed the tumor growth without showing toxicity. Collectively, this study demonstrates that celastrol can inhibit Wnt/β-catenin signaling by promoting the degradation of β-catenin, consequently inhibiting the growth of VS.

SHP2 inhibition improves celastrol-induced growth suppression of colorectal cancer

This study aimed to explore novel targets for celastrol sensitization in colorectal cancer (CRC) based on differentially regulated signals in response to high- or low-dose celastrol. Targeting signals were investigated using Western blotting or phosphorylated receptor tyrosine kinase (RTK) arrays. Corresponding inhibitors for the signals were individually combined with low-dose celastrol for the assessment of combined anti-CRC effects, based on proliferation, apoptosis, colony assays, and xenograft models. The potential mechanism for the combination of celastrol and SHP2 inhibition was further examined. Low-dose celastrol (&lt;1 µM) did not effectively suppress AKT and ERK signals in CRC cells compared to high-dose celastrol (&gt;1 µM). However, when combined with an AKT or ERK inhibitor, low-dose celastrol could cooperatively suppress CRC proliferation. Furthermore, failed AKT or ERK inhibition by low-dose celastrol may be due to reactivated RTK-SHP2 signaling with negative feedback. The combination of celastrol and the SHP2 inhibitor resulted in greatly reduced AKT and ERK signals, as well as greater inhibition of CRC growth than celastrol alone. Moreover, the mechanism underlying combination suppression was also involved in the activation of immune cell infiltration (mainly for CD8+ cells) in CRC tissues. Failure to inhibit RTK-SHP2-AKT/ERK signaling contributed to the lack of CRC growth suppression by low-dose celastrol. However, the combination of celastrol and the SHP2 inhibitor resulted in synergistic inhibition of CRC growth and provided a promising therapeutic target.

Potential Application of Leelamine as a Novel Regulator of Chemokine-Induced Epithelial-to-Mesenchymal Transition in Breast Cancer Cells

CXCR7 and CXCR4 are G protein-coupled receptors (GPCRs) that can be stimulated by CXCL12 in various human cancers. CXCR7/4–CXCL12 binding can initiate activation of multiple pathways including JAK/STAT and manganese superoxide dismutase (MnSOD) signaling, and initiate epithelial–mesenchymal transition (EMT) process. It is established that cancer cell invasion and migration are caused because of these events. In particular, the EMT process is an important process that can determine the prognosis for cancer. Since the antitumor effect of leelamine (LEE) has been reported in various previous studies, here, we have evaluated the influence of LEE on the CXCR7/4 signaling axis and EMT processes. We first found that LEE suppressed expression of CXCR7 and CXCR4 both at the protein and mRNA levels, and showed inhibitory effects on these chemokines even after stimulation by CXCL12 ligand. In addition, LEE also reduced the level of MnSOD and inhibited the EMT process to attenuate the invasion and migration of breast cancer cells. In addition, phosphorylation of the JAK/STAT pathway, which acts down-stream of these chemokines, was also abrogated by LEE. It was also confirmed that LEE can induce an imbalance of GSH/GSSG and increases ROS, thereby resulting in antitumor activity. Thus, we establish that targeting CXCR7/4 in breast cancer cells can not only inhibit the invasion and migration of cancer cells but also can affect JAK/STAT, EMT process, and production of ROS. Overall, the findings suggest that LEE can function as a novel agent affecting the breast cancer.

Assembly of Celastrol to Zeolitic Imidazolate Framework-8 by Coordination as a Novel Drug Delivery Strategy for Cancer Therapy

Celastrol (Cel), a compound derived from traditional Chinese medicine Tripterygium wilfordii Hook. F, has attracted considerable attention as an anticancer drug. However, its clinical application is limited due to its low bioavailability and potential toxicity. With the advancement of nanoscale metal organic frameworks (MOF), the nano-delivery of drugs can effectively improve those disadvantages. Nevertheless, hydrophobic drugs apparently cannot be encapsulated by the hydrophilic channels of MOF-based drug delivery systems. To address these issues, a new assembly strategy for hydrophobic Cel was developed by coordinating the deprotonated Cel to zeolitic imidazolate framework-8 (ZIF-8) with the assistance of triethylamine (Cel-ZIF-8). This strategy greatly elevates the assembly efficiency of Cel from less than 1% to ca. 80%. The resulted Cel-ZIF-8 remains stable in the physiological condition while dissociating and releasing Cel after a 45-minute incubation in an acidic tumor microenvironment (pH 5.5). Furthermore, Cel-ZIF-8 is proved to be easily taken up by cancer cells and exhibits a better therapeutic effect on tumor cells than free Cel. Overall, the Cel-ZIF-8 provides a novel assembly strategy for hydrophobic drugs, and the findings are envisaged to facilitate the application of Cel in cancer therapies.

Molecular Landscape of LncRNAs in Prostate Cancer: A focus on pathways and therapeutic targets for intervention

Background

One of the most malignant tumors in men is prostate cancer that is still incurable due to its heterogenous and progressive natures. Genetic and epigenetic changes play significant roles in its development. The RNA molecules with more than 200 nucleotides in length are known as lncRNAs and these epigenetic factors do not encode protein. They regulate gene expression at transcriptional, post-transcriptional and epigenetic levels. LncRNAs play vital biological functions in cells and in pathological events, hence their expression undergoes dysregulation.

Aim of review

The role of epigenetic alterations in prostate cancer development are emphasized here. Therefore, lncRNAs were chosen for this purpose and their expression level and interaction with other signaling networks in prostate cancer progression were examined.

Key scientific concepts of review

The aberrant expression of lncRNAs in prostate cancer has been well-documented and progression rate of tumor cells are regulated via affecting STAT3, NF-κB, Wnt, PI3K/Akt and PTEN, among other molecular pathways. Furthermore, lncRNAs regulate radio-resistance and chemo-resistance features of prostate tumor cells. Overexpression of tumor-promoting lncRNAs such as HOXD-AS1 and CCAT1 can result in drug resistance. Besides, lncRNAs can induce immune evasion of prostate cancer via upregulating PD-1. Pharmacological compounds such as quercetin and curcumin have been applied for targeting lncRNAs. Furthermore, siRNA tool can reduce expression of lncRNAs thereby suppressing prostate cancer progression. Prognosis and diagnosis of prostate tumor at clinical course can be evaluated by lncRNAs. The expression level of exosomal lncRNAs such as lncRNA-p21 can be investigated in serum of prostate cancer patients as a reliable biomarker.

Fangchinoline targets epithelial-mesenchymal transition process by modulating activation of multiple cell-signaling pathways

Epithelial-mesenchymal transition (EMT) is a key process, which can promote the transition of tumor cells into other organs by weakening the cell-cell junctions. Tumor cell invasion and metastasis arising because of EMT can determine the prognosis of cancer. EMT can be induced by several growth factors including transforming growth factor-β (TGF-β), which can exert their effects by affecting several cell-signaling pathways. Fangchinoline (FCN), a kind of bisbenzylisoquinoline, belongs to the family Menispermaceae. FCN can display substantial antitumor effects against various malignant cell lines but its possible impact on EMT has not been explored. We examined the potential impact of FCN in affecting the activation of EMT in human colon cancer cells. We evaluated the influence of FCN on EMT in colon cancer cells by using Western blot analysis and reverse transcription-polymerase chain reaction assays. The cellular invasion and migration were observed by Boyden chamber and wound healing assays. Thereafter, the effect of the drug on proliferation and invasion was also evaluated by real-time cell analysis. FCN suppressed the levels of TGF-β-induced mesenchymal markers, such as fibronectin, vimentin, MMP-9, MMP-2, N-cadherin, Twist, and Snail. However, FCN markedly enhanced the expression of epithelial markers such as occludin and E-cadherin. These results imply that FCN can potentially inhibit tumor metastasis through abrogating EMT. In addition, FCN downregulated c-Met/PI3K/Akt/mTOR and Wnt/β-catenin cell signaling pathways and mitigated tumor migration as well as invasion. Overall, our study suggests a potential novel role of FCN as an antimetastatic agent against human colon cancer cells.

NF-κB as a regulator of cancer metastasis and therapy response: A focus on epithelial-mesenchymal transition

Metastasis of tumor cells is a complex challenge and significantly diminishes the overall survival and prognosis of cancer patients. The epithelial-to-mesenchymal transition (EMT) is a well-known mechanism responsible for the invasiveness of tumor cells. A number of molecular pathways can regulate the EMT mechanism in cancer cells and nuclear factor-kappaB (NF-κB) is one of them. The nuclear translocation of NF-κB p65 can induce the transcription of several genes involved in EMT induction. The present review describes NF-κB and EMT interaction in cancer cells and their association in cancer progression. Due to the oncogenic role NF-κB signaling, its activation enhances metastasis of tumor cells via EMT induction. This has been confirmed in various cancers including brain, breast, lung and gastric cancers, among others. The ZEB1/2, transforming growth factor-β, and Slug as inducers of EMT undergo upregulation by NF-κB to promote metastasis of tumor cells. After EMT induction driven by NF-κB, a significant decrease occurs in E-cadherin levels, while N-cadherin and vimentin levels undergo an increase. The noncoding RNAs can potentially also function as upstream mediators and modulate NF-κB/EMT axis in cancers. Moreover, NF-κB/EMT axis is involved in mediating drug resistance in tumor cells. Thus, suppressing NF-κB/EMT axis can also promote the sensitivity of cancer cells to chemotherapeutic agents.

Targeting autophagy in prostate cancer: preclinical and clinical evidence for therapeutic response

Prostate cancer is a leading cause of death worldwide and new estimates revealed prostate cancer as the leading cause of death in men in 2021. Therefore, new strategies are pertinent in the treatment of this malignant disease. Macroautophagy/autophagy is a “self-degradation” mechanism capable of facilitating the turnover of long-lived and toxic macromolecules and organelles. Recently, attention has been drawn towards the role of autophagy in cancer and how its modulation provides effective cancer therapy. In the present review, we provide a mechanistic discussion of autophagy in prostate cancer. Autophagy can promote/inhibit proliferation and survival of prostate cancer cells. Besides, metastasis of prostate cancer cells is affected (via induction and inhibition) by autophagy. Autophagy can affect the response of prostate cancer cells to therapy such as chemotherapy and radiotherapy, given the close association between autophagy and apoptosis. Increasing evidence has demonstrated that upstream mediators such as AMPK, non-coding RNAs, KLF5, MTOR and others regulate autophagy in prostate cancer. Anti-tumor compounds, for instance phytochemicals, dually inhibit or induce autophagy in prostate cancer therapy. For improving prostate cancer therapy, nanotherapeutics such as chitosan nanoparticles have been developed. With respect to the context-dependent role of autophagy in prostate cancer, genetic tools such as siRNA and CRISPR-Cas9 can be utilized for targeting autophagic genes. Finally, these findings can be translated into preclinical and clinical studies to improve survival and prognosis of prostate cancer patients.

• Prostate cancer is among the leading causes of death in men where targeting autophagy is of importance in treatment;

• Autophagy governs proliferation and metastasis capacity of prostate cancer cells;

• Autophagy modulation is of interest in improving the therapeutic response of prostate cancer cells;

• Molecular pathways, especially involving non-coding RNAs, regulate autophagy in prostate cancer;

• Autophagy possesses both diagnostic and prognostic roles in prostate cancer, with promises for clinical application.

The Protective Role of Celastrol in Renal Ischemia-Reperfusion Injury by Activating Nrf2/HO-1, PI3K/AKT Signaling Pathways, Modulating NF-κb Signaling Pathways, and Inhibiting ERK Phosphorylation

Celastrol, a natural triterpenoid derived from Tripterygium wilfordii, possesses numerous biological effects. We investigated celastrol's antioxidant potential through nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) and its effect on phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling, nuclear factor-kappa B (NF-κB) pathways, and extracellular signal-regulated kinase (ERK) activation in kidney ischemia-reperfusion injury (IRI) rat model. Rats were given celastrol 2 mg/kg orally for 1 week before subjection to renal ischemia-reperfusion surgery. Kidney functions, renal MDA, and reduced glutathione were determined; also, renal levels of ERK1/2, HO-1, PI3K, IL-6, TNF-α, IκBα, NF-κB/p65, and cleaved caspase-3 were measured. In addition, gene expression of kidney injury molecule-1 (KIM-1), Nrf-2, and AKT were determined. Celastrol pretreatment attenuated oxidative stress and increased Nrf2 gene expression and HO-1 level. Also, it activated the PI3K/AKT signaling pathway and decreased the p-ERK:t- ERK ratio and NFκBp65 level, with a remarkable decrease in inflammatory cytokines and cleaved caspase-3 levels compared with those in renal IRI rats. Conclusively, celastrol showed a reno-protective potential against renal IRI by suppressing oxidative stress through enhancing the Nrf2/HO-1 pathway, augmenting cell survival PI3K/AKT signaling pathways, and reducing inflammation by inhibiting NF-κB activation.

Natural products are an important source for proteasome regulating agents

BACKGROUND

Natural medicines have a long history in the prevention and treatment of various diseases in East Asian region, especially in China. Modern research has proved that the pharmacological effects of numerous natural medicines involve the participation of ubiquitin proteasome system (UPS). UPS can degrade the unwanted and damaged proteins widely distributed in the nucleus and cytoplasm of various eukaryotes.

PURPOSE

The objective of the present study was to review and discuss the regulatory effects of natural products and extracts on proteasome components, which may help to find new proteasome regulators for drug development and clinical applications.

METHODS

The related information was compiled using the major scientific databases, such as CNKI, Elsevier, ScienceDirect, PubMed, SpringerLink, Wiley Online, and GeenMedical. The keywords "natural product" and "proteasome" were applied to extract the literature. Nature derived extracts, compounds and their derivatives involved in proteasome regulation were included, and the publications related to synthetic proteasome agents were excluded.

RESULTS

The pharmacological effects of more than 80 natural products and extracts derived from phytomedicines related to the proteasome regulation were reviewed. These natural products were classified according to their chemical properties. We also summarized some laws of action of natural products as proteasome regulators in the treatment of diseases, and listed the action characteristics of the typical natural products.

CONCLUSION

Natural products derived from nature can induce the degradation of damaged proteins through UPS or act as regulators to directly regulate the activity of proteasome. But few proteasome modulators are applied clinically. Summary of known rules for proteasome modulators will contribute to discover, modify and synthesize more proteasome modulators for clinical applications.

Potential function of oxymatrine as a novel suppressor of epithelial-to-mesenchymal transition in lung tumor cells

AIMS

Tumor cells metastasis as well as proliferation are important factors that can substantially determines the prognosis of cancer. In particular, epithelial-mesenchymal transition (EMT) is key phenomena which can cause tumor cell transition into other organs by promoting the disruption of the cell-cell junctions. Because oxymatrine (OMT) have been reported to attenuate the tumor growth, we investigated whether OMT can down-regulate EMT process in tumor cells. We also focused on transforming growth factor-β (TGF-β)-induced EMT process because EMT process can be significantly induced by this growth factor.

MAIN METHODS

The cell viability was measured by MTT and real time cell analysis (RTCA) assay. The expression levels of various proteins involved in the regulation of EMT and Akt/mTOR/PI3K signaling pathway were evaluated by Western blot analysis. mRNA levels of several important EMT markers were analyzed by reverse transcription polymerase chain reaction (RT-PCR). The effects of OMT on the cellular invasion and migration were evaluated by RTCA, wound healing assay, and boyden chamber assays.

KEY FINDINGS

OMT suppressed the expression of both constitutive and TGF-β-induced mesenchymal markers, such as fibronectin, vimentin, MMP-9, MMP-2, N-cadherin, Twist, and Snail, but induced the levels of epithelial markers. Moreover, OMT down-regulated oncogenic PI3K/Akt/mTOR pathways which lead to a significant attenuation of invasive and migratory potential of lung cancer cells.

SIGNIFICANCE

Overall, our study established a novel anti-metastatic role of OMT against human lung cancer cells.

Celastrol in cancer therapy: Recent developments, challenges and prospects

Cancer is one of the world's biggest healthcare burdens and despite the current advancements made in treatment plans, the outcomes for oncology patients have yet to reach their full potential. Hence, there is a pressing need to develop novel anti-cancer drugs. A popular drug class for research are natural compounds, due to their multi-targeting potential and enhanced safety profile. One such promising natural bioactive compound derived from a vine, Tripterygium wilfordii is celastrol. Pre-clinical studies revolving around the use of celastrol have revealed positive pharmacological activities in various types of cancers, thus suggesting the chemical's potential anti-cancerous effects. However, despite the numerous preclinical studies carried out over the past few decades, celastrol has not reached human trials for cancer. In this review, we summarize the mechanisms and therapeutic potentials of celastrol in treatment for different types of cancer. Subsequently, we also explore the possible reasons hindering its development for human use as cancer therapy, like its narrow therapeutic window and poor pharmacokinetic properties. Additionally, after critically analysing both in vitro and in vivo evidence, we discuss about the key pathways effected by celastrol and the suitable types of cancer that can be targeted by the natural drug, thus giving insight into future directions that can be taken, such as in-depth analysis and research of the druggability of celastrol derivatives, to aid the clinical translation of this promising anti-cancer lead compound.

Ginkgolide C promotes apoptosis and abrogates metastasis of colorectal carcinoma cells by targeting Wnt/β-catenin signaling pathway

Ginkgolide C (GGC), isolated from Ginkbiloba, has been reported to display various pharmacological actions, although, anti-cancer effect of GGC has been poorly understood till now. This study aimed to investigate whether GGC can exhibit anti-neoplastic effects against colon cancer cells and explore underlying mechanism. The Wnt/β-catenin signaling can regulate cell proliferation, survival, metastasis, and migration. Wnt/β-catenin signaling pathway plays important role in colorectal cancer (CRC) and acts as a potential therapeutic target. Abnormal activation of this signaling cascades has been reported in colon CRC. We found that GGC down-regulated Wnt/β-catenin signaling cascade. GGC inhibited the expression of Wnt3a, β-catenin, and β-catenin down-stream signals (Axin-1, p-GSK3β, and β-TrCP). Also, GGC suppressed the expression of Wnt/β-catenin pathway target genes including c-myc, cyclin D1, and survivin. Additionally, GGC induced apoptosis and suppressed cell proliferation, invasion, and migration. GGC down-regulated the expressions of matrix metalloproteinase (MMP)-9 and MMP-2 proteins. Moreover, silencing of β-catenin by small interfering RNA (siRNA) enhanced the GGC-induced apoptosis and inhibitory action of GGC on invasion. Overall, our results indicate that GGC can reduce proliferation and promote apoptosis in colon cancer cells through inhibition of the Wnt/β-catenin signaling pathway. Thus, GGC can serve as a potent therapeutic agent for management of colon cancer as a novel wnt signaling inhibitor.

Blockage of the JAK/STAT3 signaling pathway in multiple myeloma by leelamine

BACKGROUND

Leelamine (LEE) is a lipophilic diterpene amine phytochemical, which can be naturally extracted from pine's bark trees. It has been extensively studied recently for its promising chemopreventive and anti-cancer effects against various cancers such as that of prostate and breast.

HYPOTHESIS

We examined the potential impact of LEE in affecting the activation of signal transducer and activator of transcription 3 (STAT3) and promoting apoptosis in human multiple myeloma (MM) cells.

METHODS

We evaluated the effect of LEE on STAT3 signaling pathway in MM cells by using Western blot analysis and reverse transcription polymerase chain reaction (RT-PCR). Thereafter, apoptosis was evaluated using cell cycle analysis and Annexin V assay.

RESULTS

We noted that LEE could attenuate the phosphorylation of STAT3 and other up-stream signaling molecules such as JAK1, JAK2, and Src activation in U266 and MM.1S cells. It also diminished STAT3 translocation into the nucleus and enhanced the expression of protein-tyrosine phosphatase epsilon (PTPε). Additionally, LEE caused cell cycle arrest and synergistically augmented the apoptotic actions of bortezomib against MM cells.

CONCLUSIONS

Our data indicates that LEE could block STAT3 signaling cascade linked to tumorigenesis and can be used in combination with approved anti-cancer agents in attenuating MM growth and survival.

Diosgenin attenuates tumor growth and metastasis in transgenic prostate cancer mouse model by negatively regulating both NF-κB/STAT3 signaling cascades

Prostate cancer (PCa) is a common disease among men especially in the old age. The deregulated activation of oncogenic and pro-survival transcription factors has been linked with tumor progression in PCa patients. The consequence of diosgenin treatment on NF-κB/STAT3 activation in PCa cells as well as transgenic mouse model was determined. We also validated the hypothesis of targeting these transcription factors using in silico proteomics simulation model. Diosgenin abrogated NF-κB/STAT3 activation and this action was caused as a result of suppression of protein kinases and reporter gene activity that led to a substantial reduction in the expression of various tumorigenic gene products. In vivo, diosgenin (2% w/w) when mixed in diet and fed to mice abrogated tumor progression in transgenic mice. Diosgenin was also detected in serum and was well absorbed orally. Overall, our data highlights the promising efficacy of diosgenin in PCa therapy.

Celastrol acts synergistically with afatinib to suppress non-small cell lung cancer cell proliferation by inducing paraptosis

Non-small cell lung cancer (NSCLC) with wild-type epidermal growth factor receptor (EGFR) is intrinsic resistance to EGFR-tyrosine kinase inhibitors (TKIs), such as afatinib. Celastrol, a natural compound with antitumor activity, was reported to induce paraptosis in cancer cells. In this study, intrinsic EGFR-TKI-resistant NSCLC cell lines H23 (EGFR wild-type and KRAS mutation) and H292 (EGFR wild-type and overexpression) were used to test whether celastrol could overcome primary afatinib resistance through paraptosis induction. The synergistic effect of celastrol and afatinib on survival inhibition of the NSCLC cells was evaluated by CCK-8 assay and isobologram analysis. The paraptosis and its modulation were assessed by light and electron microscopy, Western blot analysis, and immunofluorescence. Xenografts models were established to investigate the inhibitory effect of celastrol plus afatinib on the growth of the NSCLC tumors in vivo. Results showed that celastrol acted synergistically with afatinib to suppress the survival of H23 and H292 cells by inducing paraptosis characterized by extensive cytoplasmic vacuolation. This process was independent of apoptosis and not associated with autophagy induction. Afatinib plus celastrol-induced cytoplasmic vacuolation was preceded by endoplasmic reticulum stress and unfolded protein response. Accumulation of intracellular reactive oxygen species and mitochondrial Ca2+ overload may be initiating factors of celastrol/afatinib-induced paraptosis and subsequent cell death. Furthermore, Celastrol and afatinib synergistically suppressed the growth of H23 cell xenograft tumors in vivo. The data indicate that a combination of afatinib and celastrol may be a promising therapeutic strategy to surmount intrinsic afatinib resistance in NSCLC cells.

Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis

In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells-highlight some future perspectives in cancer therapy by targeting cytoskeleton.

MicroRNAs as Modulators of Oral Tumorigenesis-A Focused Review

Oral cancers constitute the majority of head and neck tumors, with a relatively high incidence and poor survival rate in developing countries. While the five-year survival rates of the oral cancer patients have increased to 65%, the overall survival for advanced stages has been at 27% for the past ten years, emphasizing the necessity for further understanding the etiology of the disease, diagnosis, and formulating possible novel treatment regimens. MicroRNAs (miRNAs), a family of small non-coding RNA, have emerged as master modulators of gene expression in various cellular and biological process. Aberrant expression of these dynamic molecules has been associated with many human diseases, including oral cancers. The deregulated miRNAs have been shown to control various oncogenic processes, including sustaining proliferative signaling, evading growth suppressors, resisting cell death activating invasion and metastasis, and inducing angiogenesis. Hence, the aberrant expression of miRNAs associated with oral cancers, makes them potential candidates for the investigation of functional markers, which will aid in the differential diagnosis, prognosis, and development of novel therapeutic regimens. This review presents a holistic insight into our understanding of the role of miRNAs in regulating various hallmarks of oral tumorigenesis.

An overview of the potential anticancer properties of cardamonin

Cancer is one of the leading causes of mortality, contributing to 9.6 million deaths globally in 2018 alone. Although several cancer treatments exist, they are often associated with severe side effects and high toxicities, leaving room for significant advancements to be made in the field. In recent years, several phytochemicals from plants and natural bioresources have been extracted and tested against various human malignancies using both in vitro and in vivo preclinical model systems. Cardamonin, a chalcone extracted from the Alpinia species, is an example of a natural therapeutic agent that has anti-cancer and anti-inflammatory effects against human cancer cell lines, including breast, lung, colon, and gastric, in both in vitro culture systems as well as xenograft mouse models. Earlier, cardamonin was used as a natural medicine against stomach related issues, diarrhea, insulin resistance, nephroprotection against cisplatin treatment, vasorelaxant and antinociceptive. The compound is well-known to inhibit proliferation, migration, invasion, and induce apoptosis, through the involvement of Wnt/β-catenin, NF-κB, and PI3K/Akt pathways. The good biosafety and pharmacokinetic profiling of cardamonin satisfy it as an attractive molecule for the development of an anticancer agent. The present review has summarized the chemo-preventive ability of cardamonin as an anticancer agent against numerous human malignancies.

Celastrol: A Review of Useful Strategies Overcoming its Limitation in Anticancer Application

Celastrol, a natural bioactive ingredient derived from Tripterygium wilfordii Hook F, exhibits significant broad-spectrum anticancer activities for the treatment of a variety of cancers including liver cancer, breast cancer, prostate tumor, multiple myeloma, glioma, etc. However, the poor water stability, low bioavailability, narrow therapeutic window, and undesired side effects greatly limit its clinical application. To address this issue, some strategies were employed to improve the anticancer efficacy and reduce the side-effects of celastrol. The present review comprehensively focuses on the various challenges associated with the anticancer efficiency and drug delivery of celastrol, and the useful approaches including combination therapy, structural derivatives and nano/micro-systems development. The specific advantages for the use of celastrol mediated by these strategies are presented. Moreover, the challenges and future research directions are also discussed. Based on this review, it would provide a reference to develop a natural anticancer compound for cancer treatment.

PRMT5 inhibition attenuates cartilage degradation by reducing MAPK and NF-κB signaling

OBJECTIVES

A role for the type II arginine methyltransferase PRMT5 in various human diseases has been identified. In this study, the potential mechanism underlying the involvement of PRMT5 in the pathological process leading to osteoarthritis (OA) was investigated.

METHODS

PRMT5 expression in cartilage tissues from patients with OA and control individuals was assessed by immunohistochemical staining. The regulatory and functional roles of PRMT5 in the chondrocytes of patients with OA and control individuals were determined by western blotting and reverse transcription polymerase chain reaction. The effects of the PRMT5 inhibitor EPZ on interleukin-1β-induced inflammation were examined in the chondrocytes of patients with OA and in the destabilized medial meniscus (DMM) of a mouse model of OA.

RESULTS

PRMT5 was specifically upregulated in the cartilage of patients with OA. Moreover, adenovirus-mediated overexpression of PRMT5 in human chondrocytes caused cartilage degeneration. This degeneration was induced by elevated expression levels of matrix-degrading enzymes (matrix metalloproteinase-3 (MMP-3) and matrix metalloproteinase-13 (MMP-13)) in chondrocytes. The activation of the MAPK and nuclear factor κB signaling pathways was evidenced by elevated levels of p-p65, p-p38, and p-JNK. These effects were attenuated by inhibiting the expression of PRMT5. In the mouse model, EPZ inhibited PRMT5 expression, thus protecting mouse cartilage from DMM-induced OA.

CONCLUSIONS

Our results demonstrate that PRMT5 is a crucial regulator of OA pathogenesis, implying that EPZ has therapeutic value in the treatment of this cartilage-destroying disease.

An Overview of the Potential Antineoplastic Effects of Casticin

Cancer persists as one of the leading causes of deaths worldwide, contributing to approximately 9.6 million deaths per annum in recent years. Despite the numerous advancements in cancer treatment, there is still abundant scope to mitigate recurrence, adverse side effects and toxicities caused by existing pharmaceutical drugs. To achieve this, many phytochemicals from plants and natural products have been tested against cancer cell lines in vivo and in vitro. Likewise, casticin, a flavonoid extracted from the Vitex species, has been isolated from the leaves and seeds of V. trifolia and V. agnus-castus. Casticin possesses a wide range of therapeutic properties, including analgesic, anti-inflammatory, antiangiogenic, antiasthmatic and antineoplastic activities. Several studies have been conducted on the anticancer effects of casticin against cancers, including breast, bladder, oral, lung, leukemia and hepatocellular carcinomas. The compound inhibits invasion, migration and proliferation and induces apoptosis (casticin-induced, ROS-mediated and mitochondrial-dependent) and cell cycle arrest (G0/G1, G2/M, etc.) through different signaling pathways, namely the PI3K/Akt, NF-κB, STAT3 and FOXO3a/FoxM1 pathways. This review summarizes the chemo-preventive ability of casticin as an antineoplastic agent against several malignancies.

Celastrol Alleviates Gamma Irradiation-Induced Damage by Modulating Diverse Inflammatory Mediators

The present study aimed to explore the possible radioprotective effects of celastrol and relevant molecular mechanisms in an in vitro cell and in vivo mouse models exposed to gamma radiation. Human keratinocytes (HaCaT) and foreskin fibroblast (BJ) cells were exposed to gamma radiation of 20 Gy, followed by treatment with celastrol for 24 h. Cell viability, reactive oxygen species (ROS), nitric oxide (NO) and glutathione (GSH) production, lipid peroxidation, DNA damage, inflammatory cytokine levels, and NF-κB pathway activation were examined. The survival rate, levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in blood, and p65 and phospho-p65 expression were also evaluated in mice after exposure to gamma radiation and celastrol treatment. The gamma irradiation of HaCaT cells induced decreased cell viability, but treatment with celastrol significantly blocked this cytotoxicity. Gamma irradiation also increased free radical production (e.g., ROS and NO), decreased the level of GSH, and enhanced oxidative DNA damage and lipid peroxidation in cells, which were effectively reversed by celastrol treatment. Moreover, inflammatory responses induced by gamma irradiation, as demonstrated by increased levels of IL-6, TNF-α, and IL-1β, were also blocked by celastrol. The increased activity of NF-κB DNA binding following gamma radiation was significantly attenuated after celastrol treatment. In the irradiated mice, treatment with celastrol significantly improved overall survival rate, reduced the excessive inflammatory responses, and decreased NF-κB activity. As a NF-κB pathway blocker and antioxidant, celastrol may represent a promising pharmacological agent with protective effects against gamma irradiation-induced injury.

Attenuation of STAT3 Signaling Cascade by Daidzin Can Enhance the Apoptotic Potential of Bortezomib against Multiple Myeloma

Daidzin (DDZ) extracted from Pueraria lobate (Fabaceae) is a widely known phytoestrogen. DDZ can display anti-cancer activities against breast and prostate cancers, but its anti-oncogenic actions in multiple myeloma (MM) cells have not been studied. The signal transducer and activator of transcription 3 (STAT3) can control key processes including proliferation, differentiation, and survival in MM cells. Here, we noted that DDZ abrogated STAT3 activation (both constitutive as well as inducible) at Tyr705 and Ser727 in MM cells. Additionally, DDZ mitigated the phosphorylation of STAT3 upstream Janus-activated kinases (JAK1/2) and c-Src kinases. Pervanadate (tyrosine phosphatase blocker) exposure altered the DDZ-induced inhibition of STAT3 activation, thus affecting the action of this phytoestrogen on apoptosis. Moreover, DDZ impeded proliferation and augmented the apoptotic effects of bortezomib (Bor) in MM cells. Overall, the data indicate that DDZ may act as a potent suppressor of STAT3 signaling cascade, and the co-treatment of DDZ and Bor could be a promising therapeutic strategy, specifically in MM.

Fangchinoline, a Bisbenzylisoquinoline Alkaloid can Modulate Cytokine-Impelled Apoptosis via the Dual Regulation of NF-κB and AP-1 Pathways

Fangchinoline (FCN) derived from Stephaniae tetrandrine S. Moore can be employed to treat fever, inflammation, rheumatism arthralgia, edema, dysuria, athlete’s foot, and swollen wet sores. FCN can exhibit a plethora of anti-neoplastic effects although its precise mode of action still remains to be deciphered. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) can closely regulate carcinogenesis and thus we analyzed the possible action of FCN may have on these two signaling cascades in tumor cells. The effect of FCN on NF-κB and AP-1 signaling cascades and its downstream functions was deciphered using diverse assays in both human chronic myeloid leukemia (KBM5) and multiple myeloma (U266). FCN attenuated growth of both leukemic and multiple myeloma cells and repressed NF-κB, and AP-1 activation through diverse mechanisms, including attenuation of phosphorylation of IκB kinase (IKK) and p65. Furthermore, FCN could also cause significant enhancement in TNFα-driven apoptosis as studied by various molecular techniques. Thus, FCN may exhibit potent anti-neoplastic effects by affecting diverse oncogenic pathways and may be employed as pro-apoptotic agent against various malignancies.

An Update on Pharmacological Potential of Boswellic Acids against Chronic Diseases

Natural compounds, in recent years, have attracted significant attention for their use in the prevention and treatment of diverse chronic diseases as they are devoid of major toxicities. Boswellic acid (BA), a series of pentacyclic triterpene molecules, is isolated from the gum resin of Boswellia serrata and Boswellia carteri. It proved to be one such agent that has exhibited efficacy against various chronic diseases like arthritis, diabetes, asthma, cancer, inflammatory bowel disease, Parkinson’s disease, Alzheimer’s, etc. The molecular targets attributed to its wide range of biological activities include transcription factors, kinases, enzymes, receptors, growth factors, etc. The present review is an attempt to demonstrate the diverse pharmacological uses of BA, along with its underlying molecular mechanism of action against different ailments. Further, this review also discusses the roadblocks associated with the pharmacokinetics and bioavailability of this promising compound and strategies to overcome those limitations for developing it as an effective drug for the clinical management of chronic diseases.

Formononetin Regulates Multiple Oncogenic Signaling Cascades and Enhances Sensitivity to Bortezomib in a Multiple Myeloma Mouse Model

Here, we determined the anti-neoplastic actions of formononetin (FT) against multiple myeloma (MM) and elucidated its possible mode of action. It was observed that FT enhanced the apoptosis caused by bortezomib (Bor) and mitigated proliferation in MM cells, and these events are regulated by nuclear factor-κB (NF-κB), phosphatidylinositol 3-kinase (PI3K)/AKT, and activator protein-1 (AP-1) activation. We further noted that FT treatment reduced the levels of diverse tumorigenic proteins involved in myeloma progression and survival. Interestingly, we observed that FT also blocked persistent NF-κB, PI3K/AKT, and AP-1 activation in myeloma cells. FT suppressed the activation of these oncogenic cascades by affecting a number of signaling molecules involved in their cellular regulation. In addition, FT augmented tumor growth-inhibitory potential of Bor in MM preclinical mouse model. Thus, FT can be employed with proteasomal inhibitors for myeloma therapy by regulating the activation of diverse oncogenic transcription factors involved in myeloma growth.

Cycloastragenol can negate constitutive STAT3 activation and promote paclitaxel-induced apoptosis in human gastric cancer cells

BACKGROUND

Cycloastragenol (CAG), a triterpene aglycone is commonly prescribed for treating hypertension, cardiovascular disease, diabetic nephropathy, viral hepatitis, and various inflammatory-linked diseases.

HYPOTHESIS

We investigated CAG for its action on signal transducer and activator of transcription 3 (STAT3) activation cascades, and its potential to sensitize gastric cancer cells to paclitaxel-induced apoptosis.

METHODS

The effect of CAG on STAT3 phosphorylation and other hallmarks of cancer was deciphered using diverse assays in both SNU-1 and SNU-16 cells.

RESULTS

We observed that CAG exhibited cytotoxic activity against SNU-1 and SNU-16 cells to a greater extent as compared to normal GES-1 cells. CAG predominantly caused negative regulation of STAT3 phosphorylation at tyrosine 705 through the abrogation of Src and Janus-activated kinases (JAK1/2) activation. We noted that CAG impaired translocation of STAT3 protein as well as its DNA binding activity. It further decreased cellular proliferation and mediated its anticancer effects predominantly by causing substantial apoptosis rather than autophagy. In addition, CAG potentiated paclitaxel-induced anti-oncogenic effects in gastric tumor cells.

CONCLUSIONS

Our results indicate that CAG can function to impede STAT3 activation in human gastric tumor cells and therefore it may be a suitable candidate agent for therapy of gastric cancer.

Focus on Formononetin: Anticancer Potential and Molecular Targets

Formononetin, an isoflavone, is extracted from various medicinal plants and herbs, including the red clover (Trifolium pratense) and Chinese medicinal plant Astragalus membranaceus. Formononetin's antioxidant and neuroprotective effects underscore its therapeutic use against Alzheimer's disease. Formononetin has been under intense investigation for the past decade as strong evidence on promoting apoptosis and against proliferation suggests for its use as an anticancer agent against diverse cancers. These anticancer properties are observed in multiple cancer cell models, including breast, colorectal, and prostate cancer. Formononetin also attenuates metastasis and tumor growth in various in vivo studies. The beneficial effects exuded by formononetin can be attributed to its antiproliferative and cell cycle arrest inducing properties. Formononetin regulates various transcription factors and growth-factor-mediated oncogenic pathways, consequently alleviating the possible causes of chronic inflammation that are linked to cancer survival of neoplastic cells and their resistance against chemotherapy. As such, this review summarizes and critically analyzes current evidence on the potential of formononetin for therapy of various malignancies with special emphasis on molecular targets.

Sanguinarine Induces Apoptosis Pathway in Multiple Myeloma Cell Lines via Inhibition of the JaK2/STAT3 Signaling

Sanguinarine (SNG), a benzophenanthridine alkaloid, has displayed various anticancer abilities in several vivo and in vitro studies. However, the anticancer potential of SNG is yet to be established in multiple myeloma (MM), a mostly incurable malignancy of plasma cells. In this study, we aimed to investigate the potential anti-proliferative and pro-apoptotic activities of SNG in a panel of MM cell lines (U266, IM9, MM1S, and RPMI-8226). SNG treatment of MM cells resulted in a dose-dependent decrease in cell viability through mitochondrial membrane potential loss and activation of caspase 3, 9, and cleavage of PARP. Pre-treatment of MM cells with a universal caspase inhibitor, Z-VAD-FMK, prevented SNG mediated loss of cell viability, apoptosis, and caspase activation, confirming that SNG-mediated apoptosis is caspase-dependent. The SNG-mediated apoptosis appears to be resulted from suppression of the constitutively active STAT3 with a concomitant increase in expression of protein tyrosine phosphatase (SHP-1). SNG treatment of MM cells leads to down-regulation of the anti-apoptotic proteins including cyclin D, Bcl-2, Bclxl, and XIAP. In addition, it also upregulates pro-apoptotic protein, Bax. SNG mediated cellular DNA damage in MM cell lines by induction of oxidative stress through the generation of reactive oxygen species and depletion of glutathione. Finally, the subtoxic concentration of SNG enhanced the cytotoxic effects of anticancer drugs bortezomib (BTZ) by suppressing the viability of MM cells via induction of caspase-mediated apoptosis. Altogether our findings demonstrate that SNG induces mitochondrial and caspase-dependent apoptosis, generates oxidative stress, and suppresses MM cell lines proliferation. In addition, co-treatment of MM cell lines with sub-toxic doses of SNG and BTZ potentiated the cytotoxic activity. These results would suggest that SNG could be developed into therapeutic agent either alone or in combination with other anticancer drugs in MM.

Pleiotropic Pharmacological Actions of Capsazepine, a Synthetic Analogue of Capsaicin, against Various Cancers and Inflammatory Diseases

Capsazepine is a synthetic analogue of capsaicin that can function as an antagonist of TRPV1. Capsazepine can exhibit diverse effects on cancer (prostate cancer, breast cancer, colorectal cancer, oral cancer, and osteosarcoma) growth and survival, and can be therapeutically used against other major disorders such as colitis, pancreatitis, malaria, and epilepsy. Capsazepine has been reported to exhibit pleiotropic anti-cancer effects against numerous tumor cell lines. Capsazepine can modulate Janus activated kinase (JAK)/signal transducer and activator of the transcription (STAT) pathway, intracellular Ca²⁺ concentration, and reactive oxygen species (ROS)-JNK-CCAAT/enhancer-binding protein homologous protein (CHOP) pathways. It can inhibit cell proliferation, metastasis, and induce apoptosis. Moreover, capsazepine can exert anti-inflammatory effects through the downregulation of lipopolysaccharide (LPS)-induced nuclear transcription factor-kappa B (NF-κB), as well as the blockage of activation of both transient receptor potential cation channel subfamily V member 1 (TRPV1) and transient receptor potential cation channel, subfamily A, and member 1 (TRPA1). This review briefly summarizes the diverse pharmacological actions of capsazepine against various cancers and inflammatory conditions.

FBXW7 in Cancer: What Has Been Unraveled Thus Far?

: The FBXW7 (F-box with 7 tandem WD40) protein encoded by the gene FBXW7 is one of the crucial components of ubiquitin ligase called Skp1-Cullin1-F-box (SCF) complex that aids in the degradation of many oncoproteins via the ubiquitin-proteasome system (UPS) thus regulating cellular growth. FBXW7 is considered as a potent tumor suppressor as most of its target substrates can function as potential growth promoters, including c-Myc, Notch, cyclin E, c-JUN, and KLF5. Its regulators include p53, C/EBP-δ, Numb, microRNAs, Pin 1, Hes-5, BMI1, Ebp2. Mounting evidence has indicated the involvement of aberrant expression of FBXW7 for tumorigenesis. Moreover, numerous studies have also shown its role in cancer cell chemosensitization, thereby demonstrating the importance of FBXW7 in the development of curative cancer therapy. This comprehensive review emphasizes on the targets, functions, regulators and expression of FBXW7 in different cancers and its involvement in sensitizing cancer cells to chemotherapeutic drugs.