Acetyl-11-keto-β-boswellic acid suppresses invasion of pancreatic cancer cells through the downregulation of CXCR4 chemokine receptor expression

Targeting chemokine-receptor mediated molecular signaling by ethnopharmacological approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Infection and inflammation are critical to global human health status and the goal of current pharmacological interventions intends formulating medications/preventives as a measure to deal with this situation. Chemokines and their cognate receptors are major regulatory molecules in many of these ailments. Natural products have been a keen source to the drug development industry, every year contributing significantly to the growing list of FDA approved drugs. A multiverse of natural resource is employed as a part of curative regimen in folk/traditional/ethnomedicine which can be employed to discover, repurpose, and design potent medications for the diseases of clinical concern.

AIM OF THE STUDY

This review aims to systematically document the ethnopharmacologically active agents targeting the infectious-inflammatory diseases through the chemokine-receptor nexus.

MATERIALS AND METHODS

Articles related to chemokine/receptor modulating ethnopharmacological anti-inflammatory, anti-infectious natural sources, bioactive compounds, and formulations have been examined with special emphasis on women related diseases. The available literature has been thoroughly scrutinized for the application of traditional medicines in chemokine associated experimental methods, their regulatory outcomes, and pertinence to women's health wherever applicable. Moreover, the potential traditional regimens under clinical trials have been critically assessed.

RESULTS

A systematic and comprehensive review on the chemokine-receptor targeting ethnopharmaceutics from the available literature has been provided. The article discusses the implication of traditional medicine in the chemokine system dynamics in diverse infectious-inflammatory disorders such as cardiovascular diseases, allergic diseases, inflammatory diseases, neuroinflammation, and cancer. On this note, critical evaluation of the available data surfaced multiple diseases prevalent in women such as osteoporosis, rheumatoid arthritis, breast cancer, cervical cancer and urinary tract infection. Currently there is no available literature highlighting chemokine-receptor targeting using traditional medicinal approach from women's health perspective. Moreover, despite being potent in vitro and in vivo setups there remains a gap in clinical translation of these formulations, which needs to be strategically and scientifically addressed to pave the way for their successful industrial translation.

CONCLUSIONS

The review provides an optimistic global perspective towards the applicability of ethnopharmacology in chemokine-receptor regulated infectious and inflammatory diseases with special emphasis on ailments prevalent in women, consecutively addressing their current status of clinical translation and future directions.

The journey of boswellic acids from synthesis to pharmacological activities

There has been a lot of interest in using naturally occurring substances to treat a wide variety of chronic disorders in recent years. From the gum resin of Boswellia serrata and Boswellia carteri, the pentacyclic triterpene molecules known as boswellic acid (BA) are extracted. We aimed to provide a detailed overview of the origins, chemistry, synthetic derivatives, pharmacokinetic, and biological activity of numerous Boswellia species and their derivatives. The literature searched for reports of B. serrata and isolated BAs having anti-cancer, anti-microbial, anti-inflammatory, anti-arthritic, hypolipidemic, immunomodulatory, anti-diabetic, hepatoprotective, anti-asthmatic, and clastogenic activities. Our results revealed that the cytotoxic and anticancer effects of B. serrata refer to its triterpenoid component, including BAs. Three-O-acetyl-11-keto-BA was the most promising cytotoxic molecule among tested substances. Activation of caspases, upregulation of Bax expression, downregulation of nuclear factor-kappa B (NF-kB), and stimulation of poly (ADP)-ribose polymerase (PARP) cleavage are the primary mechanisms responsible for cytotoxic and antitumor effects. Evidence suggests that BAs have shown promise in combating a wide range of debilitating disease conditions, including cancer, hepatic, inflammatory, and neurological disorders.

Targeted delivery of genistein for pancreatic cancer treatment using hyaluronic-coated cubosomes bioactivated with frankincense oil

Pancreatic cancer is an aggressive malignancy that remains a major cause of cancer-related deaths. Research for innovative anticancer therapeutic options is thus imperative. In this regard, phytotherapeutics offer great promise as efficient treatment modalities, especially leveraging nanodrug delivery. Herein, we innovatively coloaded the flavonoid genistein (Gen) and frankincense essential oil (FO) within cubosomes, which were then coated with the bioactive ligand hyaluronic acid (HA/Gen-FO-Cub) for active-targeting of pancreatic cancer. The novel HA/Gen-FO-Cub displayed optimum nanosize (198.2 ± 4.5 nm), PDI (0.27 ± 0.01), zeta-potential (-34.7 ± 1.2 mV), Gen entrapment (99.3 ± 0.01 %), and controlled Gen release (43.7 ± 1.2 % after 120 h). HA/Gen-FO-Cub exerted selective anticancer activity on pancreatic cancer cells (PANC-1; 8-fold drop in IC50), cellular uptake and anti-migratory effect compared to Gen solution. HA/Gen-FO-Cub revealed prominent cytocompatibility (100 ± 5.9 % viability of human dermal fibroblast). Moreover, HA/Gen-FO-Cub boosted the in vivo anticancer activity of Gen in an orthotopic cancer model, affording tumor growth suppression (2.5-fold drop) and downregulation of NFκB and VEGF (2.9- and 1.8-fold decrease, respectively), compared to Gen suspension. Antimetastatic efficacy and Bcl-2-downexpression was histologically confirmed. Our findings demonstrate the promising anticancer aptitude of HA/Gen-FO-Cub as an effective phytotherapeutic nanodelivery system for pancreatic cancer therapy.

Anti-cancer properties of boswellic acids: mechanism of action as anti-cancerous agent

With the advent of highly effective plant-based medications with few or no side effects, the use of phytomedicines against complex diseases such as cancer is becoming more widespread. The broadly recognized pentacyclic triterpenes known as boswellic acids (BAs) are derived from the oleogum resin, or frankincense, extracted from the plant species of the genus Boswellia. The frankincense mixture contains various BA types, each having a different potential and helping treat certain cancers. This review focuses on details regarding the traits of the BAs, their roles as anti-cancer agents, the mechanism underlying their activities, and the function of their semi-synthetic derivatives in managing and treating certain cancers. The review also explores the biological sources of BAs, how they are conserved, and how biotechnology might help preserve and improve in vitro BA production. The review concludes that the BAs and their semi-synthetic derivatives are effective against a broad spectrum of cancer cell lines. The detailed information in the review can be helpful for researchers to gain more information about BAs and BA-based medications for efficient and cost-effective cancer treatments.

Epigenetic Regulation of CXCR4 Signaling in Cancer Pathogenesis and Progression

Signaling involving chemokine receptor CXCR4 and its ligand SDF-1/CXL12 has been investigated for many years for its possible role in cancer progression and pathogenesis. Evidence emerging from clinical studies in recent years has further established diagnostic as well as prognostic importance of CXCR4 signaling. CXCR4 and SDF-1 are routinely reported to be elevated in tumors, distant metastases, which correlates with poor survival of patients. These findings have kindled interest in the mechanisms that regulate CXCR4/SDF-1 expression. Of note, there is a particular interest in the epigenetic regulation of CXCR4 signaling that may be responsible for upregulated CXCR4 in primary as well as metastatic cancers. This review first lists the clinical evidence supporting CXCR4 signaling as putative cancer diagnostic and/or prognostic biomarker, followed by a discussion on reported epigenetic mechanisms that affect CXCR4 expression. These mechanisms include regulation by non-coding RNAs, such as, microRNAs, long non-coding RNAs and circular RNAs. Additionally, we also discuss the regulation of CXCR4 expression through methylation and acetylation. Better understanding and appreciation of epigenetic regulation of CXCR4 signaling can invariably lead to identification of novel therapeutic targets as well as therapies to regulate this oncogenic signaling.

Molecular evidences on anti-inflammatory, anticancer, and memory-boosting effects of frankincense

Chemical diversity of natural products with drug-like features has attracted much attention from medicine to develop more safe and effective drugs. Their anti-inflammatory, antitumor, analgesic, and other therapeutic properties are sometimes more successful than chemical drugs in controlling disease due to fewer drug resistance and side effects and being more tolerable in a long time. Frankincense, the oleo gum resin extracted from the Boswellia species, contains some of these chemicals. The anti-inflammatory effect of its main ingredient, boswellic acid, has been traditionally used to treat many diseases, mainly those target memory functions. In this review, we have accumulated research evidence from the beneficial effect of Frankincense consumption in memory improvement and the prevention of inflammation and cancer. Besides, we have discussed the molecular pathways mediating the therapeutic effects of this natural supplement.

Biosynthetic diversity in triterpene cyclization within the Boswellia genus

This review is not intended to describe the triterpenes isolated from the Boswellia genus, since this information has been covered elsewhere. Instead, the aim is to provide insights into the biosynthesis of triterpenes in Boswellia. This genus, which has 24 species, displays fascinating structural diversity and produces a number of medicinally important triterpenes, particularly boswellic acids. Over 300 volatile components have been reported in the essential oil of Boswellia, and more than 100 diterpenes and triterpenes have been isolated from this genus. Given that no triterpene biosynthetic enzymes have yet been isolated from any members of the Boswellia genus, this review will cover the likely biosynthetic pathways as inferred from structures in nature and the probable types of biosynthetic enzymes based on knowledge of triterpene biosynthesis in other plant species. It highlights the importance of frankincense and the factors and threats affecting its production. It covers triterpene biosynthesis in the genus Boswellia, including dammaranes, tirucallic acids, lupanes, oleananes, ursanes and boswellic acids. Strategies for elucidating triterpene biosynthetic pathways in Boswellia are considered. Furthermore, the possible mechanisms behind wound-induced resin synthesis by the tree and related gene expression profiling are covered. In addition, the influence of the environment and the genotype on the biosynthesis of resin and on variations in the compositions and types of resins will also be reviewed.

Acetyl-11-keto-β-boswellic acid enhances the cisplatin sensitivity of non-small cell lung cancer cells through cell cycle arrest, apoptosis induction, and autophagy suppression via p21-dependent signaling pathway

Cisplatin-based therapy is a widely used chemotherapeutic regimen for non-small cell lung cancer (NSCLC); however, drug resistance limits its efficacy. Acetyl-11-keto-β-boswellic acid (AKBA), a bioactive compound from frankincense, has been shown to exert anti-cancer effects. The aim of this study is to explore the potential of AKBA in combination with cisplatin as a new regimen for NSCLC. CCK8 assay and clone formation assay were used to determine the effects of AKBA in combination with cisplatin on cell viability of NSCLC cell lines. A three-dimensional spherification assay was used to simulate in vivo tumor formation. Flow cytometry was performed to examine cell cycle distribution and the percentages of apoptotic cells. The associated proteins and mRNA of cell cycle, apoptosis, and autophagy were measured by western blotting and real-time fluorescence quantitative PCR. Immunofluorescence assay was used to test apoptotic nuclei and autolysosome. Small interfering RNA experiments were used to silence the expression of p21. Combination treatment of AKBA and cisplatin inhibited cell viability, clone formation, and three-dimensional spherification, enhanced G₀/G₁ phase arrest, increased the percentages of apoptotic cells, and decreased the ratio of positive autolysosomes, compared with cisplatin alone. AKBA in combination with cisplatin suppressed the protein expressions of cyclin A2, cyclin E1, p-cdc2, CDK4, Bcl-xl, Atg5, and LC3A/B, and upregulated p27 and p21 mRNA levels in A549 cells. Downregulation of p21 decreased G₀/G₁ phase arrest and the percentages of apoptotic cells, and promoted autophagy in NSCLC A549 cells. Our study demonstrates that AKBA enhances the cisplatin sensitivity of NSCLC cells and that the mechanisms involve G₀/G₁ phase arrest, apoptosis induction, and autophagy suppression via targeting p21-dependent signaling pathway.

A Validated LC-MS/MS Method for Simultaneous Determination of 3-O-Acetyl-11-Keto-β-Boswellic Acid (AKBA) and its Active Metabolite Acetyl-11-Hydroxy-β-Boswellic Acid (Ac-11-OH-BA) in Rat Plasma: Application to a Pharmacokinetic Study

The aim of this study was to develop and validate a new, rapid, sensitive, selective and reliable liquid chromatography-tandem mass spectrometry method for simultaneous determination of 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) and its active metabolite 3-O-Acetyl-11-hydroxy-β-boswellic acid (Ac-11-hydroxy-BA) in rat plasma. Both analytes (AKBA and Ac-11-hydroxy-BA) and the internal standard (IS, ursolic acid) were extracted from 100 μL of rat plasma by protein precipitation. Chromatographic separation was achieved on PRP-H1 RP-C18 column (75 mm × 2 mm, 1.6 μm) using acetonitrile-water (95.5 v/v) as the mobile phase. Mass detection was conducted by electrospray ionization in positive ion multiple reaction monitoring (MRM) mode. A linear dynamic range of 1-1,000 ng/mL for both AKBA and Ac-11-hydroxy-BA was established with mean correlation coefficient (r (1)) of 0.999. Intra- and inter-day precision (% CV) of analysis were found in the range of 1.9-7.4%. The accuracy determined for these analytes ranged from 92.4 to 107.2%. The extraction recoveries for both analytes ranged from 92.6 to 97.3% for spiked plasma samples and were consistent. The % change in stability samples compared to nominal concentration ranged from 0.4 to 4.2%. This method was successfully tested to a pharmacokinetic (PK) study for estimation of AKBA and acetyl-11-hydroxy-BA in rat plasma following oral administration of AKBA. This method has been validated with the advantage of shorter run time that can be used for high-throughput analysis and has been successfully applied to the pharmacokinetic study of AKBA in rats.

Frankincense and myrrh and their bioactive compounds ameliorate the multiple myeloma through regulation of metabolome profiling and JAK/STAT signaling pathway based on U266 cells

BACKGROUND

Frankincense and myrrh are used as traditional anti-inflammatory and analgesic medicines in China. It has been reported that frankincense and myrrh have significant anti-tumor activities. The present study was designed to investigate the inhibitory efficacy of frankincense ethanol extracts (RXC), myrrh ethanol extracts (MYC), frankincense -myrrh ethanol extracts (YDC), frankincense -myrrh water extracts (YDS) and their main compounds on U266 human multiple myeloma cell line.

METHODS

The inhibition effects of cell proliferation was evaluated by MTT assays. Cell culture supernatant was collected for estimation of cytokines. Western blot analysis was designed to investigate the regulatory of JAK/STAT signal pathway. In addition, cell metabolomics based on the ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) had been established to investigate the holistic efficacy of frankincense and myrrh on U266 cells. Acquired data were processed by partial least-squares discriminant analysis (PLS-DA) and orthogonal projection to latent structures squares-discriminant analysis (OPLS-DA) to identify potential biomarkers.

RESULTS

RXC, MYC significantly inhibited the proliferation of U266 cells at dose of 25-400 μg/mL, YDC and YDS at the dose of 12.5-400 μg/mL. 3-O-acetyl-α-boswellic acid, 3-acetyl-11 keto-boswellic acid and 11-keto-boswellic acid had the most significant anti- multiple myeloma activities in the 10 compounds investigated, therefore these 3 compounds were selected as representatives for Elisa assay and western blotting experiments. All the extracts and active compounds ameliorated the secretion of cytokines and down-regulated the expression of JAK/STAT signaling pathway-related proteins. Comparing RXC, MYC, YDC and YDS-treated U266 cells with vehicle control (DMSO), 13, 8, 7, 7 distinct metabolites and 2, 2, 3, 0 metabolic target pathways involved in amino acid metabolism, lipid metabolism, vitamin metabolism, arachidonic acid were identified, respectively.

CONCLUSIONS

Taken together our results suggest that the frankincense and myrrh and their bioactive compounds inhibit proliferation of U266 multiple myeloma cells by regulating JAK/STAT signaling pathway and cellular metabolic profile.

Anti-inflammatory and anti-cancer activities of frankincense: Targets, treatments and toxicities

The oleogum resins of Boswellia species known as frankincense have been used for ages in traditional medicine in India, China and the Arabian world independent of its use for cultural and religious rituals in Europe. During the past two decades, scientific investigations provided mounting evidence for the therapeutic potential of frankincense. We conducted a systematic review on the anti-inflammatory and anti-cancer activities of Boswellia species and their chemical ingredients (e.g. 3-O-acetyl-11-keto-β boswellic acid, α- and β-boswellic acids, 11-keto-β-boswellic acid and other boswellic acids, lupeolic acids, incensole, cembrenes, triterpenediol, tirucallic acids, and olibanumols). Frankincense acts by multiple mechanisms, e.g. by the inhibition of leukotriene synthesis, of cyclooxygenase 1/2 and 5-lipoxygenase, of oxidative stress, and by regulation of immune cells from the innate and acquired immune systems. Furthermore, frankincense modulates signaling transduction responsible for cell cycle arrest and inhibition of proliferation, angiogenesis, invasion and metastasis. Clinical trials showed the efficacy of frankincense and its phytochemicals against osteoarthritis, multiple sclerosis, asthma, psoriasis and erythematous eczema, plaque-induced gingivitis and pain. Frankincense revealed beneficial effects towards brain tumor-related edema, but did not reduce glioma size. Even if there is no treatment effect on brain tumors itself, the management of glioma-associated edema may represent a desirable improvement. The therapeutic potential against other tumor types is still speculative. Experimental toxicology and clinical trials revealed only mild adverse side effects. More randomized clinical trials are required to estimate the full clinical potential of frankincense for cancer therapy.

Markers of pancreatic cancer stem cells and their clinical and therapeutic implications

Pancreatic cancer (PC) is the fourth most common cause of death among all cancers. Poor prognosis of PC may be caused by a prevalence of cancer stem cells (CSCs). CSCs are a population of cancer cells showing stem cell-like characteristics. CSCs have the ability to self-renew and may initiate tumorigenesis. PC CSCs express markers such as CD133, CD24, CD44, DCLK1, CXCR4, ESA, Oct4 and ABCB1. There is a wide complexity of interaction and relationships between CSC markers in PC. These markers are negative prognostic factors and are connected with tumor recurrence and clinical progression. Additionally, PC CSCs are resistant to treatment with gemcitabine. Thus, most current therapies for PC are ineffective. Numerous studies have shown, that targeting of these proteins may increase both disease-free and overall survival in PC.

Induction of developmental toxicity and cardiotoxicity in zebrafish embryos/larvae by acetyl-11-keto-β-boswellic acid (AKBA) through oxidative stress

Acetyl-11-keto-β-boswellic acid (AKBA), a triterpenoid from Boswellia serrate, is regarded as an angiogenesis inhibitor. However, its toxicity is unknown. The aim of this study was to examine its developmental toxicity and cardiotoxicity. A developmental toxicity assay in zebrafish embryos/larvae from 4 to 96 hours post-fertilization (hpf) was performed and a cardiotoxicity assay was designed from 48 to 72 hpf. Markers of oxidative stress and related genes were selected to access the possible mechanisms. According to the results, AKBA induced pericardium edema, yolk-sac edema, abnormal melanin, spinal curvature, hatching inhibition and shortened body length. Further, increased SV-BA distance, reduced heart rate, increased pericardium area and decreased blood flow velocity were detected in AKBA treated groups. The inhibition of cardiac progenitor gene expression, such as Nkx2.5 and Gata4, may be related to cardiotoxicity. The activities of antioxidant enzymes were decreased and the content of MDA was increased. In addition, AKBA treatment decreased the expression levels of Mn-Sod, Cat, and Gpx. These results suggested that AKBA induced developmental toxicity and cardiotoxicity through oxidative stress. As far as we know, this is the first report on the toxicity of AKBA. It reminds us to pay attention to developmental toxicity and cardiotoxicity of AKBA.

Targeting CXCL12/CXCR4 Axis in Tumor Immunotherapy

Chemokines, which have chemotactic abilities, are comprised of a family of small cytokines with 8-10 kilodaltons. Chemokines work in immune cells by trafficking and regulating cell proliferation, migration, activation, differentiation, and homing. CXCR-4 is an alpha-chemokine receptor specific for stromal-derived-factor-1 (SDF-1, also known as CXCL12), which has been found to be expressed in more than 23 different types of cancers. Recently, the SDF-1/CXCR-4 signaling pathway has emerged as a potential therapeutic target for human tumor because of its critical role in tumor initiation and progression by activating multiple signaling pathways, such as ERK1/2, ras, p38 MAPK, PLC/ MAPK, and SAPK/ JNK, as well as regulating cancer stem cells. CXCL12/CXCR4 antagonists have been produced, which have shown encouraging results in anti-cancer activity. Here, we provide a brief overview of the CXCL12/CXCR4 axis as a molecular target for cancer treatment. We also review the potential utility of targeting CXCL12/CXCR4 axis in combination of immunotherapy and/or chemotherapy based on up-to-date literature and ongoing research progress.

Seeing the Unseen of the Combination of Two Natural Resins, Frankincense and Myrrh: Changes in Chemical Constituents and Pharmacological Activities

For the treatment of diseases, especially chronic diseases, traditional natural drugs have more effective therapeutic advantages because of their multi-target and multi-channel characteristics. Among many traditional natural medicines, resins frankincense and myrrh have been proven to be effective in the treatment of inflammation and cancer. In the West, frankincense and myrrh have been used as incense in religious and cultural ceremonies since ancient times; in traditional Chinese and Ayurvedic medicine, they are used mainly for the treatment of chronic diseases. The main chemical constituents of frankincense and myrrh are terpenoids and essential oils. Their common pharmacological effects are anti-inflammatory and anticancer. More interestingly, in traditional Chinese medicine, frankincense and myrrh have been combined as drug pairs in the same prescription for thousands of years, and their combination has a better therapeutic effect on diseases than a single drug. After the combination of frankincense and myrrh forms a blend, a series of changes take place in their chemical composition, such as the increase or decrease of the main active ingredients, the disappearance of native chemical components, and the emergence of new chemical components. At the same time, the pharmacological effects of the combination seem magically powerful, such as synergistic anti-inflammation, synergistic anticancer, synergistic analgesic, synergistic antibacterial, synergistic blood-activation, and so on. In this review, we summarize the latest research on the main chemical constituents and pharmacological activities of these two natural resins, along with chemical and pharmacological studies on the combination of the two.

Googling the Guggul (Commiphora and Boswellia) for Prevention of Chronic Diseases

Extensive research during last 2 decades has revealed that most drugs discovered today, although costs billions of dollars for discovery, and yet they are highly ineffective in their clinical response. For instance, the European Medicines Agency has approved 68 anti-cancer drugs, and out of which 39 has reached the market level with no indication of increased survival nor betterment of quality of life. Even when drugs did improve survival rate compared to available treatment strategies, most of these were found to be clinically insignificant. This is a fundamental problem with modern drug discovery which is based on thinking that most chronic diseases are caused by alteration of a single gene and thus most therapies are single gene-targeted therapies. However, extensive research has revealed that most chronic diseases are caused by multiple gene products. Although most drugs designed by man are mono-targeted therapies, however, those designed by "mother nature" and have been used for thousands of years, are "multi-targeted" therapies. In this review, we examine two agents that have been around for thousands of years, namely "guggul" from Commiphora and Boswellia. Although we are all familiar with the search engine "google," this is another type of "guggul" that has been used for centuries and being explored for its various biological activities. The current review summarizes the traditional uses, chemistry, in vitro and in vivo biological activities, molecular targets, and clinical trials performed with these agents.

Combined acetyl-11-keto-β-boswellic acid and radiation treatment inhibited glioblastoma tumor cells

Glioblastoma multiforme (GBM) is the most common and most aggressive subtype of malignant gliomas. The current standard of care for newly diagnosed GBM patients involves maximal surgical debulking, followed by radiation therapy and temozolomide chemotherapy. Despite the advances in GBM therapy, its outcome remains poor with a median survival of less than two years. This poor outcome is partly due to the ability of GBM tumors to acquire adaptive resistance to therapy and in particular to radiation. One of the mechanisms contributing to GBM tumor progression and resistance is an aberrant activation of NF-ĸB, a family of inducible transcription factors that play a pivotal role in regulation of many immune, inflammatory and carcinogenic responses. Acetyl-11-keto-β-boswellic acid (AKBA) is a pentacyclic terpenoid extracted from the gum Ayurvedic therapeutic plant Boswellia serrata. AKBA is anti-inflammatory agent that exhibits potent cytotoxic activities against various types of tumors including GBM. One of the mechanisms underlying AKBA anti-tumor activity is its ability to modulate the NF-ĸB signaling pathway. The present study investigated in vitro and in vivo the effect of combining AKBA with ionizing radiation in the treatment of GBM and assessed AKBA anti-tumor activity and radio-enhancing potential. The effect of AKBA and/or radiation on the survival of cultured glioblastoma cancer cells was evaluated by XTT assay. The mode of interaction of treatments tested was calculated using CalcuSyn software. Inducing of apoptosis following AKBA treatment was evaluated using flow cytometry. The effect of combined treatment on the expression of PARP protein was analysed by Western blot assay. Ectopic (subcutaneous) GBM model in nude mice was used for the evaluation of the effect of combined treatment on tumor growth. Immunohistochemical analysis of formalin-fixed paraffin-embedded tumor sections was used to assess treatment-related changes in Ki-67, CD31, p53, Bcl-2 and NF-ĸB-inhibitor IĸB-α. AKBA treatment was found to inhibit the survival of all four tested cell lines in a dose dependent manner. The combined treatment resulted in a more significant inhibitory effect compared to the effect of treatment with radiation alone. A synergistic effect was detected in some of the tested cell lines. Flow cytometric analysis with Annexin V-FITC/PI double staining of AKBA treated cells indicated induction of apoptosis. AKBA apoptotic activity was also confirmed by PARP cleavage detected by Western blot analysis. The combined treatment suppressed tumor growth in vivo compared to no treatment and each treatment alone. Immunohistochemical analysis showed anti-angiogenic and anti-proliferative activity of AKBA in vivo. It also demonstrated a decrease in p53 nuclear staining and in Bcl-2 staining and an increase in IĸB-α staining following AKBA treatment both alone and in combination with radiotherapy. In this study, we demonstrated that AKBA exerts potent anti-proliferative and apoptotic activity, and significantly inhibits both the survival of glioblastoma cells in vitro and the growth of tumors generated by these cells. Combination of AKBA with radiotherapy was found to inhibit factors which involved in cell death regulation, tumor progression and radioresistence, therefore it may serve as a novel approach for GBM patients.

Expanding the Application and Formulation Space of Amorphous Solid Dispersions with KinetiSol®: a Review

Due to the high number of poorly soluble drugs in the development pipeline, novel processes for delivery of these challenging molecules are increasingly in demand. One such emerging method is KinetiSol, which utilizes high shear to produce amorphous solid dispersions. The process has been shown to be amenable to difficult to process active pharmaceutical ingredients with high melting points, poor organic solubility, or sensitivity to heat degradation. Additionally, the process enables classes of polymers not conventionally processable due to their high molecular weight and/or poor organic solubility. Beyond these advantages, the KinetiSol process shows promise with other applications, such as the production of amorphous mucoadhesive dispersions for delivery of compounds that would also benefit from permeability enhancement.

Artemin regulates CXCR4 expression to induce migration and invasion in pancreatic cancer cells through activation of NF-κB signaling

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal human malignant tumor because of the early onset of local invasion and distant metastasis. Perineural invasion is a prominent characteristic of pancreatic adenocarcinoma, which is a multifactorial process that involves various signaling molecules from different signaling pathways. The glial cell line-derived neurotrophic factor family of ligands was reported to be involved in perineural invasion in pancreatic cancer. Artemin is one member of the glial cell line-derived neurotrophic factor family of ligands. Although Artemin has previously been demonstrated to promote invasiveness of pancreatic cancer, the mechanisms remain poorly understood. In this study, we performed an analysis to determine the effects of Artemin on modulating tumor cell metastatic potential and invasion activity and explored its mechanisms in pancreatic cancer. We indicated that Artemin and CXCR4 were overexpressed in cancer tissues and widely expressed in pancreatic cancer cell lines. We observed that activation of ERK1/2 and Akt in Artemin-treated cells led to enhanced nuclear accumulation of NF-κB, which then induced CXCR4 expression. Through regulation of the expression of CXCR4, Artemin functionally promoted the migration and invasion in pancreatic cancer cells. The present study indicated that Artemin induced CXCR4 expression by activating Akt and ERK 1/2/NF-κB signaling, thereby modulating tumor cell metastatic potential and invasion activity in pancreatic cancer by regulating SDF-1α/CXCR4 axis. Artemin might be an effective and potent therapeutic target for pancreatic cancer metastasis, especially in perineural invasion.

Methanolic extract of Boswellia serrata exhibits anti-cancer activities by targeting microsomal prostaglandin E synthase-1 in human colon cancer cells

BACKGROUND

Colorectal cancer (CRC) is the most common cancer. A proper method to reduce mortality of CRC is chemoprevention to prevent initiation and promotion of intestinal tumorgenesis. One of the promising and developing chemopreventive agents is natural compounds found in plants. Frankincense, the resin extract from the Boswellia specious, has been used in traditional and modern medicine for treating various diseases with very minimal side effects. In the current study, we investigated the anti-cancer activity of methanolic extract of Boswellia serrata (B. serrata) on HT-29 human colon cancer cells.

METHODS

HT-29 cells were treated with different concentrations of B. serrata and cell viability was assessed by MTT assay. mRNA expression of microsomal prostaglandin E synthase-1 (mPGES-1), vascular endothelial growth factor (VEGF), C-X-C chemokine receptor type 4 (CXCR4), matrix metalloproteinase-2 (MMP-2), MMP-9 and hypoxia-inducible factor-1 (HIF-1) were examined by quantitative real-time PCR. Apoptosis was evaluated by the proportion of sub-G1 cells. Prostaglandin E2 (PGE2) level and caspase 3 activity were determined by ELISA assay. Tube formation potential and HT-29 cells migration were assessed using three-dimensional vessel formation assay and scratch test.

RESULTS

B. serrata extract considerably decreased the expression of mPGES-1, VEGF, CXCR4, MMP-2, MMP-9 and HIF-1. The caspase 3 activity and percent of cells in sub-G1 phase were increased by B. serrata extract. Cell viability, PGE2 generation, in vitro tube formation and cell migration were decreased significantly in B. serrata-treated HT-29 compared to the control group.

CONCLUSION

Our findings suggest that B. serrata extract inhibits proliferation, angiogenesis and migration and induces apoptosis in HT-29 cells by inhibiting of mPGES-1 and decreasing the PGE2 level and its downstream targets.

Emerging roles of the CXCL12/CXCR4 axis in pancreatic cancer progression and therapy

Chemokine networks regulate a variety of cellular, physiological, and immune processes. These normal functions can become appropriated by cancer cells to facilitate a more hospitable niche for aberrant cells by enhancing growth, proliferation, and metastasis. This is especially true in pancreatic cancer, where chemokine signaling is a vital component in the development of the supportive tumor microenvironment and the signaling between the cancer cells and surrounding stromal cells. Although expression patterns vary among cancer types, the chemokine receptor CXCR4 has been implicated in nearly every major malignancy and plays a prominent role in pancreatic cancer development and progression. This receptor, in conjunction with its primary chemokine ligand CXCL12, promotes pancreatic cancer development, invasion, and metastasis through the management of the tumor microenvironment via complex crosstalk with other pathways. Thus, CXCR4 likely contributes to the poor prognoses observed in patients afflicted with this malignancy. Recent exploration of combination therapies with CXCR4 antagonists have demonstrated improved outcomes, and abolishing the contribution of this pathway may prove crucial to effectively treat pancreatic cancer at both the primary tumor and metastases.

Canonical and alternative transcript expression of PAX6 and CXCR4 in pancreatic cancer

Pancreatic cancer is a lethal disease with a propensity for invading and metastasizing into the surrounding tissues, including the liver and intestines. A number of factors are aberrantly overexpressed in this tumor type and actively promote cancer progression and metastasis. The present study demonstrates that paired box transcription factor 6 (PAX6) and C-X-C chemokine receptor 4 (CXCR4) are frequently co-expressed in primary pancreatic adenocarcinoma tumors and established cell lines. Expression analysis methods used in the present study included evaluation of protein expression by western blot analysis and immunofluorescence, transcript expression levels by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and luciferase assays utilizing regulatory elements from the CXCR4 gene locus. Canonical PAX6 and alternative splice variant PAX6(5a) proteins are expressed in pancreatic cancer and can drive gene expression through a conserved enhancer element within the first intron of the CXCR4 gene. As demonstrated by the introduction of an exogenous reporter construct with or without the intronic enhancer, loss of this element inhibited gene expression within numerous pancreatic cancer cell lines including Panc1, MIA-PaCa2 and BxPC3. All of the pancreatic cancer cell lines expressed the canonical CXCR4B transcript in addition to the alternatively spliced variant CXCR4A as determined by RT-qPCR experiments. The discovery of variant transcripts in pancreatic cancer cells may provide new candidates for future targeted therapies.

Biological Activities of Essential Oils: From Plant Chemoecology to Traditional Healing Systems

Essential oils are complex mixtures of hydrocarbons and their oxygenated derivatives arising from two different isoprenoid pathways. Essential oils are produced by glandular trichomes and other secretory structures, specialized secretory tissues mainly diffused onto the surface of plant organs, particularly flowers and leaves, thus exerting a pivotal ecological role in plant. In addition, essential oils have been used, since ancient times, in many different traditional healing systems all over the world, because of their biological activities. Many preclinical studies have documented antimicrobial, antioxidant, anti-inflammatory and anticancer activities of essential oils in a number of cell and animal models, also elucidating their mechanism of action and pharmacological targets, though the paucity of in human studies limits the potential of essential oils as effective and safe phytotherapeutic agents. More well-designed clinical trials are needed in order to ascertain the real efficacy and safety of these plant products.

Pharmacological evidences for cytotoxic and antitumor properties of Boswellic acids from Boswellia serrata

ETHNOPHARMACOLOGICAL RELEVANCE

Increasing research on traditional herbal medicines and their phytoconstituents has recognized their usefulness in complementary as adjuvant to chemotherapy in various types of cancers. The oleo-gum resin of Boswellia serrata tree is one such folk medicine, which has been traditionally used for religious, cosmetic as well as medical purposes since ages. The oleo-gum resin of the plant has been used in traditional medicine to treat variety of conditions including inflammatory diseases like arthritis, asthma, chronic pain, bowel conditions and many other diseases. This review presents an overview of scientific studies on cytotoxic and antitumor properties of B. serrata and its constituents.

MATERIALS AND METHODS

Literature search was carried out for activities of B. serrata and various isolated boswellic acids such as β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid reported in various cancer types in vitro as well as in vivo.

RESULTS

The triterpenoidal fraction of B. serrata (containing boswellic acids) is responsible for the cytotoxic and antitumor properties. Among the screened compounds, 3-O-acetyl-11-keto-β-boswellic acid has been found to be most promising cytotoxic molecule. The cytotoxic and antitumor effects are mainly due to induction of apoptosis through caspase activation, increased Bax expression, NF-κB down regulation and induction of poly (ADP)-ribose polymerase (PARP) cleavage.

CONCLUSIONS

Boswellic acids appear to be promising candidates for anticancer drug development in future. However, further in vivo studies are needed. Studies in combination with clinically used anticancer drugs and QSAR studies on individual boswellic acid also need to be carried out.

Phytochemical Analysis and Anti-cancer Investigation of Boswellia serrata Bioactive Constituents In Vitro

Cancer is a major health obstacle around the world, with hepatocellular carcinoma (HCC) and colorectal cancer (CRC) as major causes of morbidity and mortality. Nowadays, there isgrowing interest in the therapeutic use of natural products for HCC and CRC, owing to the anticancer activity of their bioactive constituents. Boswellia serrata oleo gum resin has long been used in Ayurvedic and traditional Chinese medicine to alleviate a variety of health problems such as inflammatory and arthritic diseases. The current study aimed to identify and explore the in vitro anticancer effect of B. Serrata bioactive constituents on HepG2 and HCT 116 cell lines. Phytochemical analysis of volatile oils of B. Serrata oleo gum resin was carried out using gas chromatography- mass spectrometry (GC/MS). Oleo-gum-resin of B. Serrata was then successively extracted with petroleum ether (extract 1) and methanol (extract 2). Gas-liquid chromatography (GLC) analysis of the lipoidal matter was also performed. In addition, a methanol extract of B. Serrata oleo gum resin was phytochemically studied using column chromatography (CC) and thin layer chromatography (TLC) to obtain four fractions (I, II, III and IV). Sephadex columns were used to isolate β-boswellic acid and identification of the pure compound was done using UV, mass spectra, 1H NMR and 13C NMR analysis. Total extracts, fractions and volatile oils of B. Serrata oleo-gum resin were subsequently applied to HCC cells (HepG2 cell line) and CRC cells (HCT 116 cell line) to assess their cytotoxic effects. GLC analysis of the lipoidal matter resulted in identification of tricosane (75.32%) as a major compound with the presence of cholesterol, stigmasterol and β-sitosterol. Twenty two fatty acids were identified of which saturated fatty acids represented 25.6% and unsaturated fatty acids 74.4% of the total saponifiable fraction. GC/MS analysis of three chromatographic fractions (I,II and III) of B. Serrata oleo gum resin revealed the presence of pent-2-ene-1,4-dione, 2-methyl- levulinic acid methyl ester, 3,5- dimethyl- 1- hexane, methyl-1-methylpentadecanoate, 1,1- dimethoxy cyclohexane, 1-methoxy-4-(1-propenyl)benzene and 17a-hydroxy-17a-cyano, preg-4-en-3-one. GC/MS analysis of volatile oils of B. Serrata oleo gum resin revealed the presence of sabinene (19.11%), terpinen-4-ol (14.64%) and terpinyl acetate (13.01%) as major constituents. The anti-cancer effect of two extracts (1 and 2) and four fractions (I, II, III and IV) as well as volatile oils of B. Serrata oleo gum resin on HepG2 and HCT 116 cell lines was investigated using SRB assay. Regarding HepG2 cell line, extracts 1 and 2 elicited the most pronounced cytotoxic activity with IC50 values equal 1.58 and 5.82 μg/mL at 48 h, respectively which were comparable to doxorubicin with an IC50 equal 4.68 μg/mL at 48 h. With respect to HCT 116 cells, extracts 1 and 2 exhibited the most obvious cytotoxic effect; with IC50 values equal 0.12 and 6.59 μg/mL at 48 h, respectively which were comparable to 5-fluorouracil with an IC50 equal 3.43 μg/ mL at 48 h. In conclusion, total extracts, fractions and volatile oils of B. Serrata oleo gum resin proved their usefulness as cytotoxic mediators against HepG2 and HCT 116 cell lines with different potentiality (extracts > fractions > volatile oil). In the two studied cell lines the cytotoxic acivity of each of extract 1 and 2 was comparable to doxorubicin and 5-fluorouracil, respectively. Extensive in vivo research is warranted to explore the precise molecular mechanisms of these bioactive natural products in cytotoxicity against HCC and CRC cells.

Antioxidant effects of hydroxysafflor yellow A and acetyl-11-keto-β-boswellic acid in combination on isoproterenol-induced myocardial injury in rats

Oxidative stress plays an important role in the initiation and development of myocardial injury (MI). The peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway is considered to be a potential target for cardioprotection in MI. Acetyl-11-keto-β-boswellic acid (AKBA) is the major organic acid component extracted from Boswellia serrata Roxb. ex Colebr. Hydroxysafflor yellow A (HSYA) is the principal active constituent of Carthamus tinctorius L. In the present study, we aimed to investigate the cardioprotective effects of HSYA and AKBA in combination in vivo and in vitro, as well as the underlying mechanisms responsible for these effects. For this purpose, MI was produced in Sprague-Dawley rats by subcutaneous injection with isoproterenol. To model ischemic-like conditions in vitro, H9C2 cells were subjected to oxygen-glucose deprivation (OGD). The levels of creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), malondialdehyde (MDA) as well as superoxide dismutase (SOD) activity were examined as well as apoptotic cell death. Mitochondrial reactive oxygen species (ROS) production and mitochondrial membrane potential (ΔΨm or MMP) were measured using MitoSOX Red and 5,5′,6,6′-tetraethylbenzimidazolylcarbocya-nine iodide (JC-1) dye. The expression of PGC-1α and Nrf2 was quantified by western blot analysis and immunohistochemistry. HSYA and AKBA prevented myocardial pathological changes, significantly reduced the blood levels of CK-MB and LDH, and decreased apoptotic cell death. They significantly increased the expression of PGC-1α and Nrf2, and the activity of the antioxidant enzyme SOD and also decreased the levels of MDA and ROS. Moreover, the reduction in MMP was partly prevented by HSYA and AKBA. Taken together, these findings elucidate the underlying mechanisms through which HSYA and AKBA protect against MI. Additionally, HSYA and AKBA appear to act synergistically in order to exert cardioprotective effects.

Bioavailability enhancement of a BCS IV compound via an amorphous combination product containing ritonavir

Objectives

To evaluate the effect of ritonavir (RTV) co-administration on the bioavailability of an amorphous dispersion of acetyl-11-keto-beta-boswellic acid (AKBA) and to develop a pharmaceutically acceptable AKBA–RTV combination tablet.

Methods

A pharmacokinetic (PK) study in rats was conducted to evaluate the influence of RTV co-administration on the oral bioavailability of an AKBA amorphous dispersion. KinetiSol was utilized to enable production of an improved RTV formulation that facilitated the development of an AKBA–RTV combination tablet. Following in-vitro characterization, the PK performance of the tablets was evaluated in male beagles.

Key findings

Co-administration of RTV increased oral absorption of AKBA by about fourfold over the AKBA dispersion alone and approximately 24-fold over the pure compound. The improved RTV amorphous dispersion exhibited similar purity and neutral-phase dissolution to Norvir. The AKBA–RTV combination tablets yielded a substantial increase in AKBA's bioavailability in dogs.

Conclusions

Oral absorption of AKBA is substantially limited by intestinal CYP3A activity and poor aqueous solubility. Consequently, AKBA's oral bioavailability is maximized by administration from a supersaturating formulation in conjunction with a CYP3A inhibitor. The AKBA–RTV combination tablet presented herein represents a breakthrough in the oral delivery of the compound facilitating future use as a drug therapy for broad spectrum cancer treatment.

CXCR4 in breast cancer: oncogenic role and therapeutic targeting

Chemokines are 8–12 kDa peptides that function as chemoattractant cytokines and are involved in cell activation, differentiation, and trafficking. Chemokines bind to specific G-protein-coupled seven-span transmembrane receptors. Chemokines play a fundamental role in the regulation of a variety of cellular, physiological, and developmental processes. Their aberrant expression can lead to a variety of human diseases including cancer. C-X-C chemokine receptor type 4 (CXCR4), also known as fusin or CD184, is an alpha-chemokine receptor specific for stromal-derived-factor-1 (SDF-1 also called CXCL12). CXCR4 belongs to the superfamily of the seven transmembrane domain heterotrimeric G protein-coupled receptors and is functionally expressed on the cell surface of various types of cancer cells. CXCR4 also plays a role in the cell proliferation and migration of these cells. Recently, CXCR4 has been reported to play an important role in cell survival, proliferation, migration, as well as metastasis of several cancers including breast cancer. This review is mainly focused on the current knowledge of the oncogenic role and potential drugs that target CXCR4 in breast cancer. Additionally, CXCR4 proangiogenic molecular mechanisms will be reviewed. Strict biunivocal binding affinity and activation of CXCR4/CXCL12 complex make CXCR4 a unique molecular target for prevention and treatment of breast cancer.

Optimization of Invasion-Specific Effects of Betulin Derivatives on Prostate Cancer Cells through Lead Development

The anti-invasive and anti-proliferative effects of betulins and abietane derivatives was systematically tested using an organotypic model system of advanced, castration-resistant prostate cancers. A preliminary screen of the initial set of 93 compounds was performed in two-dimensional (2D) growth conditions using non-transformed prostate epithelial cells (EP156T), an androgen-sensitive prostate cancer cell line (LNCaP), and the castration-resistant, highly invasive cell line PC-3. The 25 most promising compounds were all betulin derivatives. These were selected for a focused secondary screen in three-dimensional (3D) growth conditions, with the goal to identify the most effective and specific anti-invasive compounds. Additional sensitivity and cytotoxicity tests were then performed using an extended cell line panel. The effects of these compounds on cell cycle progression, mitosis, proliferation and unspecific cytotoxicity, versus their ability to specifically interfere with cell motility and tumor cell invasion was addressed. To identify potential mechanisms of action and likely compound targets, multiplex profiling of compound effects on a panel of 43 human protein kinases was performed. These target de-convolution studies, combined with the phenotypic analyses of multicellular organoids in 3D models, revealed specific inhibition of AKT signaling linked to effects on the organization of the actin cytoskeleton as the most likely driver of altered cell morphology and motility.

Novel Evidence for Curcumin and Boswellic Acid-Induced Chemoprevention through Regulation of miR-34a and miR-27a in Colorectal Cancer

Colorectal cancer is one of the most common causes of cancer-associated mortality worldwide, but it is truly a preventable disease. Both curcumin and boswellic acids are well-established dietary botanicals with potent antitumorigenic properties that have been shown to modulate multiple oncogenic pathways. Recent data suggest that the chemopreventive effects of these botanicals may, in part, be mediated through regulation of key cancer-related microRNAs (miRNA) and their downstream gene targets. Here, we investigated the antitumorigenic effects of curcumin and 3 acetyl-11-keto-β-boswellic acid (AKBA) on modulation of specific cancer-related miRNAs in colorectal cancer cells and validated their protective effects in vivo using a xenograft mouse model. Both curcumin and AKBA inhibited cellular proliferation, induced apoptosis and cell-cycle arrest in colorectal cancer cell lines, and these effects were significantly enhanced with combined treatment. Gene-expression arrays revealed that curcumin and AKBA regulated distinct cancer signaling pathways, including key cell-cycle regulatory genes. Combined bioinformatics and in silico analysis identified apoptosis, proliferation, and cell-cycle regulatory signaling pathways as key modulators of curcumin and AKBA-induced anticancer effects. We discovered that curcumin and AKBA induced upregulation of tumor-suppressive miR-34a and downregulation of miR-27a in colorectal cancer cells. Furthermore, we demonstrated in a mouse xenograft model that both curcumin and AKBA treatments suppressed tumor growth, which corresponded with alterations in the expression of miR-34a and miR-27a, consistent with our in vitro findings. Herein, we provide novel mechanistic evidence for the chemopreventive effects of curcumin and AKBA through regulation of specific miRNAs in colorectal cancer.

Silibinin, a novel chemokine receptor type 4 antagonist, inhibits chemokine ligand 12-induced migration in breast cancer cells

PURPOSE

C-X-C chemokine receptor type 4 (CXCR4) signaling has been demonstrated to be involved in cancer invasion and migration; therefore, CXCR4 antagonist can serve as an anti-cancer drug by preventing tumor metastasis. This study aimed to identify the CXCR4 antagonists that could reduce and/or inhibit tumor metastasis from natural products.

METHODS AND RESULTS

According to the molecular docking screening, we reported here silibinin as a novel CXCR4 antagonist. Biochemical characterization showed that silibinin blocked chemokine ligand 12 (CXCL12)-induced CXCR4 internalization by competitive binding to CXCR4, therefore inhibiting downstream intracellular signaling. In human breast cancer cells MDA-MB-231, which expresses high levels of CXCR4, inhibition of CXCL12-induced chemomigration can be found under silibinin treatment. Overexpression of CXCL12 sensitized MDA-MB-231 cells to the inhibition of silibinin, which was abolished by CXCR4 knockdown. The inhibition of silibinin was also observed in MCF-7/CXCR4 cells rather than MCF-7 cells that express low level of CXCR4.

CONCLUSIONS

Our work demonstrated that silibinin is a novel CXCR4 antagonist that may have potential therapeutic use for prevention of tumor metastasis.

786-0 Renal cancer cell line-derived exosomes promote 786-0 cell migration and invasion in vitro

Emerging evidence indicates that cancer-derived exosomes contribute to angiogenesis, tumor immunology and invasion. However, whether cancer cell-derived exosomes regulate the migration and invasion of the cancer cell itself, and the underlying mechanisms are not well understood. In the present study, exosomes derived from the 786-0 human renal cancer cell line were isolated, purified and 100 μg/ml were co-cultured with 786-0 cells for 24 h. The 786-0 cells were harvested for a cell invasion and migration assay. The expression of chemokine receptor type 4 (CXCR4) and matrix metalloproteinase-9 (MMP-9) in the 786-0 cells was examined by western blot analysis and revealed that the migration and invasion capabilities of the 786-0 cells were increased, however, the cell adhesion abilities were decreased as a result of the 24-h treatment with 786-0-derived exosomes. Furthermore, the expression levels of CXCR4 and MMP-9 in the 786-0 cells were increased. In conclusion, the 786-0 renal cancer cell line-derived exosomes increased migration and invasion, however, they decreased the adhesion ability of the 786-0 cells. The exosomes may have increased the CXCR4 and MMP-9 expression levels in the 786-0 cells. These findings indicated that renal tumor-derived exosomes may contribute to renal cancer development and progression.

Frankincense essential oil prepared from hydrodistillation of Boswellia sacra gum resins induces human pancreatic cancer cell death in cultures and in a xenograft murine model

Background

Regardless of the availability of therapeutic options, the overall 5-year survival for patients diagnosed with pancreatic cancer remains less than 5%. Gum resins from Boswellia species, also known as frankincense, have been used as a major ingredient in Ayurvedic and Chinese medicine to treat a variety of health-related conditions. Both frankincense chemical extracts and essential oil prepared from Boswellia species gum resins exhibit anti-neoplastic activity, and have been investigated as potential anti-cancer agents. The goals of this study are to identify optimal condition for preparing frankincense essential oil that possesses potent anti-tumor activity, and to evaluate the activity in both cultured human pancreatic cancer cells and a xenograft mouse cancer model.

Methods

Boswellia sacra gum resins were hydrodistilled at 78°C; and essential oil distillate fractions were collected at different durations (Fraction I at 0–2 h, Fraction II at 8–10 h, and Fraction III at 11–12 h). Hydrodistillation of the second half of gum resins was performed at 100°C; and distillate was collected at 11–12 h (Fraction IV). Chemical compositions were identified by gas chromatography–mass spectrometry (GC-MS); and total boswellic acids contents were quantified by high-performance liquid chromatography (HPLC). Frankincense essential oil-modulated pancreatic tumor cell viability and cytotoxicity were determined by colorimetric assays. Levels of apoptotic markers, signaling molecules, and cell cycle regulators expression were characterized by Western blot analysis. A heterotopic (subcutaneous) human pancreatic cancer xenograft nude mouse model was used to evaluate anti-tumor capability of Fraction IV frankincense essential oil in vivo. Frankincense essential oil-induced tumor cytostatic and cytotoxic activities in animals were assessed by immunohistochemistry.

Results

Longer duration and higher temperature hydrodistillation produced more abundant high molecular weight compounds, including boswellic acids, in frankincense essential oil fraactions. Human pancreatic cancer cells were sensitive to Fractions III and IV (containing higher molecular weight compounds) treatment with suppressed cell viability and increased cell death. Essential oil activated the caspase-dependent apoptotic pathway, induced a rapid and transient activation of Akt and Erk1/2, and suppressed levels of cyclin D1 cdk4 expression in cultured pancreatic cancer cells. In addition, Boswellia sacra essential oil Fraction IV exhibited anti-proliferative and pro-apoptotic activities against pancreatic tumors in the heterotopic xenograft mouse model.

Conclusion

All fractions of frankincense essential oil from Boswellia sacra are capable of suppressing viability and inducing apoptosis of a panel of human pancreatic cancer cell lines. Potency of essential oil-suppressed tumor cell viability may be associated with the greater abundance of high molecular weight compounds in Fractions III and IV. Although chemical component(s) responsible for tumor cell cytotoxicity remains undefined, crude essential oil prepared from hydrodistillation of Boswellia sacra gum resins might be a useful alternative therapeutic agent for treating patients with pancreatic adenocarcinoma, an aggressive cancer with poor prognosis.

Boswellic acid exerts antitumor effects in colorectal cancer cells by modulating expression of the let-7 and miR-200 microRNA family

Colorectal cancer (CRC) is a complex disease with genetic and epigenetic alterations in many key oncogenes and tumor suppressor genes. The active principle of a gum resin from Boswellia serrata, 3-acetyl-11-keto-β-boswellic acid (AKBA), has recently gained attention as a chemopreventive compound due to its ability to target key oncogenic proteins such as 5-lipoxygenase and nuclear factor-kappaB. AKBA has been shown to inhibit the growth of CRC cells; however, the precise molecular mechanisms underlying its anticancer activities in CRC remain unclear. We hypothesized that boswellic acids may achieve their chemopreventive effects by modulating specific microRNA (miRNA) pathways. We found that AKBA significantly up-regulated expression of the let-7 and miR-200 families in various CRC cell lines. Both let-7 and miR-200 are putative tumor-suppressive miRNAs. AKBA modulated the expression of several downstream targets of the let-7 and miR-200 families, such as CDK6, vimentin and E-cadherin. These data were further strengthened by miRNA knockdown studies, which revealed that inhibition of let-7i facilitated enhanced cancer cell proliferation, migration and invasion. In addition, AKBA also induced similar modulation of the let-7 and miR-200 downstream genes in CRC tumors orthotopically implanted in nude mice. These results indicate that AKBA-induced antitumor effects in CRC occur, at least partly through the up-regulation of specific miRNA pathways. Our data provide novel evidence that anticancer effects of boswellic acids are due in part to their ability to regulate cellular epigenetic machinery and further highlight the promise for this phytochemical in the preventative and therapeutic applications of CRC.

Ursane-type pentacyclic triterpenoids as useful platforms to discover anticancer drugs

This review highlights the potential of natural and semisynthetic ursane-type triterpenoids as candidates for the design of multi-target bioactive compounds, with focus on their anticancer effects. A brief illustration of the biosynthesis, sources, and general biological effects of the main classes of naturally occurring pentacyclic triterpenoids (PTs) are provided.

Retigeric acid B exhibits antitumor activity through suppression of nuclear factor-κB signaling in prostate cancer cells in vitro and in vivo

Previously, we reported that retigeric acid B (RB), a natural pentacyclic triterpenic acid isolated from lichen, inhibited cell growth and induced apoptosis in androgen-independent prostate cancer (PCa) cells. However, the mechanism of action of RB remains unclear. In this study, we found that using PC3 and DU145 cells as models, RB inhibited phosphorylation levels of IκBα and p65 subunit of NF-κB in a time- and dosage-dependent manner. Detailed study revealed that RB blocked the nuclear translocation of p65 and its DNA binding activity, which correlated with suppression of NF-κB-regulated proteins including Bcl-2, Bcl-x_L, cyclin D1 and survivin. NF-κB reporter assay suggested that RB was able to inhibit both constitutive activated-NF-κB and LPS (lipopolysaccharide)-induced activation of NF-κB. Overexpression of RelA/p65 rescued RB-induced cell death, while knockdown of RelA/p65 significantly promoted RB-mediated inhibitory effect on cell proliferation, suggesting the crucial involvement of NF-κB pathway in this event. We further analyzed antitumor activity of RB in in vivo study. In C57BL/6 mice carrying RM-1 homografts, RB inhibited tumor growth and triggered apoptosis mainly through suppressing NF-κB activity in tumor tissues. Additionally, DNA microarray data revealed global changes in the gene expression associated with cell proliferation, apoptosis, invasion and metastasis in response to RB treatment. Therefore, our findings suggested that RB exerted its anti-tumor effect by targeting the NF-κB pathway in PCa cells, and this could be a general mechanism for the anti-tumor effect of RB in other types of cancers as well.

Stem cells as the root of pancreatic ductal adenocarcinoma

Emerging evidence suggests that stem cells play a crucial role not only in the generation and maintenance of different tissues, but also in the development and progression of malignancies. For the many solid cancers, it has now been shown that they harbor a distinct subpopulation of cancer cells that bear stem cell features and therefore, these cells are termed cancer stem cells (CSC) or tumor-propagating cells. CSC are exclusively tumorigenic and essential drivers for tumor progression and metastasis. Moreover, it has been shown that pancreatic ductal adenocarcinoma does not only contain one homogeneous population of CSC rather than diverse subpopulations that may have evolved during tumor progression. One of these populations is called migrating CSC and can be characterized by CXCR4 co-expression. Only these cells are capable of evading the primary tumor and traveling to distant sites such as the liver as the preferred site of metastatic spread. Clinically even more important, however, is the observation that CSC are highly resistant to chemo- and radiotherapy resulting in their relative enrichment during treatment and rapid relapse of disease. Many laboratories are now working on the further in-depth characterization of these cells, which may eventually allow for the identification of their Achilles heal and lead to novel treatment modalities for fighting this deadly disease.

Boswellic acid suppresses growth and metastasis of human pancreatic tumors in an orthotopic nude mouse model through modulation of multiple targets

Pancreatic cancer (PaCa) is one of the most lethal cancers, with an estimated 5-year survival of <5% even when patients are given the best treatment available. In addition, these treatments are often toxic and expensive, thus new agents which are safe, affordable and effective are urgently needed. We describe here the results of our study with acetyl-11-keto-β-boswellic acid (AKBA), an agent obtained from an Ayurvedic medicine, gum resin of Boswellia serrata. Whether AKBA has an activity against human PaCa, was examined in in vitro models and in an orthotopic nude mouse model of PaCa. We found that AKBA inhibited the proliferation of four different PaCa cell lines (AsPC-1, PANC-28, and MIA PaCa-2 with K-Ras and p53 mutations, and BxPC-3 with wild-type K-Ras and p53 mutation). These effects correlated with an inhibition of constitutively active NF-κB and suppression of NF-κB regulating gene expression. AKBA also induced apoptosis, and sensitized the cells to apoptotic effects of gemcitabine. In the orthotopic nude mouse model of PaCa, p.o. administration of AKBA alone (100 mg/kg) significantly inhibited the tumor growth; this activity was enhanced by gemcitabine. In addition, AKBA inhibited the metastasis of the PaCa to spleen, liver, and lungs. This correlated with decreases in Ki-67, a biomarker of proliferation, and CD31, a biomarker of microvessel density, in the tumor tissue. AKBA produced significant decreases in the expression of NF-κB regulating genes in the tissues. Immunohistochemical analysis also showed AKBA downregulated the expression of COX-2, MMP-9, CXCR4, and VEGF in the tissues. Overall these results demonstrate that AKBA can suppress the growth and metastasis of human pancreatic tumors in an orthotopic nude mouse model that correlates with modulation of multiple targets.