Gemcitabine combined with gum mastic causes potent growth inhibition and apoptosis of pancreatic cancer cells

Effective combinations of anti-cancer and targeted drugs for pancreatic cancer treatment

Pancreatic cancer is highly aggressive and lethal. Due to the lack of effective methods for detecting the disease at an early stage, pancreatic cancer is frequently diagnosed late. Gemcitabine has been the standard chemotherapy drug for patients with pancreatic cancer for over 20 years, but its anti-tumor effect is limited. Therefore, FOLFIRINOX (leucovorin, fluorouracil, irinotecan, oxaliplatin) as well as combination therapies using gemcitabine and conventional agents, such as cisplatin and capecitabine, has also been administered; however, these have not resulted in complete remission. Therefore, there is a need to develop novel and effective therapies for pancreatic cancer. Recently, some studies have reported that combinations of gemcitabine and targeted drugs have had significant anti-tumor effects on pancreatic cancer cells. As gemcitabine induced DNA damage response, the proteins related to DNA damage response can be suitable additional targets for novel gemcitabine-based combination therapy. Furthermore, KRAS/ RAF/MEK/ERK signaling triggered by oncogenic mutated KRAS and autophagy are frequently activated in pancreatic cancer. Therefore, these characteristics of pancreatic cancer are potential targets for developing effective novel therapies.

In this minireview, combinations of gemcitabine and targeted drugs to these characteristics, combinations of targeted drugs, combinations of natural products and anti-cancer agents, including gemcitabine, and combinations among natural products are discussed.

Evaluation of natural gum-based cryogels for soft tissue engineering

In this study, three natural biomaterials, Locust bean gum (LBG), Xanthan gum (XG), and Mastic gum (MG), were combined to form cryogel scaffolds. Thermal and chemical characterizations revealed the successful blend formation from LBG-XG (LX) and LBG-XG-MG (LXM) polymers. All blends resulted in macro-porous scaffolds with interconnected pore structures under the size of 400 μm. The swollen cryogels had similar mechanical properties compared with other polysaccharide-based cryogels. The mean tensile and compressive modulus values of the wet cryogels were in the range of 3.5-11.6 kPa and 82-398 kPa, respectively. The sustained release of the small molecule Kartogenin from varying concentrations and ratios of cryogels was in between 32 and 66% through 21 days of incubation. Physical, mechanical, and chemical properties make LX and LXM polysaccharide-based cryogels promising candidates for cartilage and other soft tissue engineering, and drug delivery applications.

In vitro and in vivo evaluation of the genotoxic and antigenotoxic potential of the major Chios mastic water constituents

Chios mastic products are well-known for their broad applications in food industry, cosmetics, and healthcare since the antiquity. Given our recent finding that Chios mastic water (CMW) exerts antigenotoxic action, in the present study, we evaluated the genotoxic as well as the antigenotoxic potential of the four major compounds of CMW, namely, verbenone, α-terpineol, linalool, and trans-pinocarveol. The cytokinesis block micronucleus (CBMN) assay in cultured human lymphocytes and the Drosophila Somatic Mutation And Recombination Test (SMART), also known as the wing spot test, were employed. None of the four major CMW's constituents or their mixtures showed genotoxic or recombinogenic activity in either of the assays used. Co-treatment of each of the constituents with MMC revealed that all except trans-pinocarveol exerted antigenotoxic potential. Moreover, co-administration of verbenone with linalool or α-terpineol presented statistically significant reduction of MMC-induced mutagenicity. In conclusion, the major CMW constituents were shown to be free of genotoxic effects, while some exerted antigenotoxic activity either alone or in combinations, suggesting synergistic phenomena. Our results provide evidence on the key antigenotoxicity effectors of the plant extract CMW.

Natural Products as Adjunctive Treatment for Pancreatic Cancer: Recent Trends and Advancements

Pancreatic cancer is a type of common malignant tumors with high occurrence in the world. Most patients presented in clinic had pancreatic cancer at advanced stages. Furthermore, chemotherapy or radiotherapy had very limited success in treating pancreatic cancer. Complementary and alternative medicines, such as natural products/herbal medicines, represent exciting adjunctive therapies. In this review, we summarize the recent advances of using natural products/herbal medicines, such as Chinese herbal medicine, in combination with conventional chemotherapeutic agents to treat pancreatic cancer in preclinical and clinical trials.

Phytochemical Profile and Evaluation of the Biological Activities of Essential Oils Derived from the Greek Aromatic Plant Species Ocimum basilicum, Mentha spicata, Pimpinella anisum and Fortunella margarita

Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.

Arginine deiminase augments the chemosensitivity of argininosuccinate synthetase-deficient pancreatic cancer cells to gemcitabine via inhibition of NF-κB signaling

Background

Pancreatic cancer is a leading cause of cancer-related deaths in the world with a 5-year survival rate of less than 6%. Currently, there is no successful therapeutic strategy for advanced pancreatic cancer, and new effective strategies are urgently needed. Recently, an arginine deprivation agent, arginine deiminase, was found to inhibit the growth of some tumor cells (i.e., hepatocellular carcinoma, melanoma, and lung cancer) deficient in argininosuccinate synthetase (ASS), an enzyme used to synthesize arginine. The purpose of this study was to evaluate the therapeutic efficacy of arginine deiminase in combination with gemcitabine, the first line chemotherapeutic drug for patients with pancreatic cancer, and to identify the mechanisms associated with its anticancer effects.

Methods

In this study, we first analyzed the expression levels of ASS in pancreatic cancer cell lines and tumor tissues using immunohistochemistry and RT-PCR. We further tested the effects of the combination regimen of arginine deiminase with gemcitabine on pancreatic cancer cell lines in vitro and in vivo.

Results

Clinical investigation showed that pancreatic cancers with reduced ASS expression were associated with higher survivin expression and more lymph node metastasis and local invasion. Treatment of ASS-deficient PANC-1 cells with arginine deiminase decreased their proliferation in a dose- and time-dependent manner. Furthermore, arginine deiminase potentiated the antitumor effects of gemcitabine on PANC-1 cells via multiple mechanisms including induction of cell cycle arrest in the S phase, upregulation of the expression of caspase-3 and 9, and inhibition of activation of the NF-κB survival pathway by blocking NF-κB p65 signaling via suppressing the nuclear translocation and phosphorylation (serine 536) of NF-κB p65 in vitro. Moreover, arginine deiminase can enhance antitumor activity of gemcitabine-based chemotherapy in the mouse xenograft model.

Conclusions

Our results suggest that arginine deprivation by arginine deiminase, in combination with gemcitabine, may offer a novel effective treatment strategy for patients with pancreatic cancer and potentially improve the outcome of patients with pancreatic cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-686) contains supplementary material, which is available to authorized users.

Modulation of CYP1A1 and CYP1A2 hepatic enzymes after oral administration of Chios mastic gum to male Wistar rats

Chios mastic gum (CMG), a resin derived from Pistacia lentiscus var. chia, is known since ancient times for its pharmacological activities. CYP1A1 and CYP1A2 enzymes are among the most involved in the biotransformation of chemicals and the metabolic activation of pro-carcinogens. Previous studies referring to the modulation of these enzymes by CMG have revealed findings of unclear biological and toxicological significance. For this purpose, the modulation of CYP1A1 and CYP1A2 enzymes in the liver of male Wistar rats following oral administration of CMG extract (CMGE), at the levels of mRNA and CYP1A1 enzyme activity, was compared to respective enzyme modulation following oral administration of a well-known bioactive natural product, caffeine, as control compound known to involve hepatic enzymes in its metabolism. mRNA levels of Cyp1a1 and Cyp1a2 were measured by reverse transcription real-time polymerase chain reaction and their relative quantification was calculated. CYP1A1 enzyme induction was measured through the activity of ethoxyresorufin-O-deethylase (EROD). The results indicated that administration of CMGE at the recommended pharmaceutical dose does not induce significant transcriptional modulation of Cyp1a1/2 and subsequent enzyme activity induction of CYP1A1 while effects of the same order of magnitude were observed in the same test system following the administration of caffeine at the mean daily consumed levels. The outcome of this study further confirms the lack of any toxicological or biological significance of the specific findings on liver following the administration of CMGE.

Evaluation of the genotoxic and antigenotoxic effects of Chios mastic water by the in vitro micronucleus test on human lymphocytes and the in vivo wing somatic test on Drosophila

Chios mastic gum, a plant-derived product obtained by the Mediterranean bush Pistacia lentiscus (L.) var. chia (Duham), has generated considerable interest because of its antimicrobial, anticancer, antioxidant and other beneficial properties. Its aqueous extract, called Chios mastic water (CMW), contains the authentic mastic scent and all the water soluble components of mastic. In the present study, the potential genotoxic activity of CMW, as well as its antigenotoxic properties against the mutagenic agent mitomycin-C (MMC), was evaluated by employing the in vitro Cytokinesis Block MicroNucleus (CBMN) assay and the in vivo Somatic Mutation And Recombination Test (SMART). In the former assay, lymphocytes were treated with 1, 2 and 5% (v/v) of CMW with or without MMC at concentrations 0.05 and 0.50 µg/ml. No significant micronucleus induction was observed by CMW, while co-treatment with MMC led to a decrease of the MMC-induced micronuclei, which ranged between 22.8 and 44.7%. For SMART, larvae were treated with 50 and 100% (v/v) CMW with or without MMC at concentrations 1.00, 2.50 and 5.00 µg/ml. It was shown that CMW alone did not modify the spontaneous frequencies of spots indicating lack of genotoxic activity. Τhe simultaneous administration of MMC with 100% CMW led to considerable alterations of the frequencies of MMC-induced wing spots with the total mutant clones showing reduction between 53.5 and 74.4%. Our data clearly show a protective role of CMW against the MMC-induced genotoxicity and further research on the beneficial properties of this product is suggested.

Icariin potentiates the antitumor activity of gemcitabine in gallbladder cancer by suppressing NF-κB

AIM

Gemcitabine has been increasingly prescribed for the treatment of gallbladder cancer. However, the response rate is low. The aim of this study is to determine whether icariin, a flavonoid isolated from Epimedi herba, could potentiate the antitumor activity of gemcitabine in gallbladder cancer.

METHODS

Human gallbladder carcinoma cell lines GBC-SD and SGC-996 were tested. Cell proliferation and apoptosis were analyzed using MTT assay and flow cytometry, respectively. The expression of apoptosis- and proliferation-related molecules was detected with Western blotting. Caspase-3 activity was analyzed using colorimetric assay, and NF-κB activity was measured with ELISA. A gallbladder cancer xenograft model was established in female BALB/c (nu/nu) mice. The mice were intraperitoneally administered gemcitabine (125 mg/kg) in combination with icariin (40 mg/kg) for 2 weeks.

RESULTS

Icariin (40-160 μg/mL) dose-dependently suppressed cell proliferation and induced apoptosis in both GBC-SD and SGC-996 cells, with SGC-996 cells being less sensitive to the drug. Icariin (40 μg/mL) significantly enhanced the antitumor activity of gemcitabine (0.5 μmol/L) in both GBC-SD and SGC-996 cells. The mice bearing gallbladder cancer xenograft treated with gemcitabine in combination with icariin exhibited significantly smaller tumor size than the mice treated with either drug alone. In GBC-SD cells, icariin significantly inhibited both the constitutive and gemcitabine-induced NF-κB activity, enhanced caspase-3 activity, induced G(0)-G(1) phase arrest, and suppressed the expression of Bcl-2, Bcl-xL and surviving proteins.

CONCLUSION

Icariin, by suppressing NF-κB activity, exerts antitumor activity, and potentiates the antitumor activity of gemcitabine in gallbladder cancer. Combined administration of gemcitabine and icariin may offer a better therapeutic option for the patients with gallbladder cancer.

Current evidence on the anticancer potential of Chios mastic gum

Chios mastic gum derived from the plant Pistacia lentiscus L. variation chia has been shown to exert beneficial effects on a wide range of human disorders. The most comprehensive data so far have indicated that mastic gum provides protection against gastrointestinal malfunctions and bacterial infections. Substantial evidence has also suggested that mastic gum exhibits hepatoprotective and cardioprotective, antiinflammatory/antioxidant, and antiatherogenic properties. In the last decade, an increasing number of studies further evaluated the potential antiproliferative properties of mastic gum against several types of human neoplasia. The present review aims to summarize the current data concerning the anticancer activities of mastic gum and their major constituents, highlighting also the molecular mechanisms through which they exert anticancer function. Mastic gum constituents that belong to the chemical class of triterpenoids appear to be mainly responsible for its anticancer potential. Thus, a brief discussion is dedicated to the anticancer activity of synthetic and naturally occurring triterpenoid analogues with similar chemical structure to mastic gum constituents. Taking into consideration the available data so far, Chios mastic gum could be considered as a conglomeration of effective anticancer drugs.

β2-adrenoceptor blocker synergizes with gemcitabine to inhibit the proliferation of pancreatic cancer cells via apoptosis induction

The stimulation of β2-adrenoceptor, which is a major mediator for chronic stress-induced cancers, has been implicated in the progression in the number of cancer cells, including pancreatic cancer, which remains one of the most aggressive and lethal diseases worldwide. Whether β-adrenoceptor antagonists potentiate gemcitabine, a standard first-line treatment for advanced pancreatic cancer that offers only modest benefit due to acquired chemoresistance, has not been elucidated. Thus, we studied the antiproliferative and apoptotic effects and the underlying mechanisms of gemcitabine combined with the β2-adrenoceptor blocker ICI 118551 (1-[2,3-(dihydro-7-methyl-1H-iden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol), in human pancreatic cancer BxPC-3 and MIA PaCa-2 cells. Results show that ICI 118551 significantly synergized the antiproliferative and pro-apoptotic effects induced by gemcitabine in both BxPC-3 and MIA PaCa-2 cells (P<0.05 combination vs. control or gemcitabine alone). When cells were treated with the combination of gemcitabine and ICI 118551, NF-κB activation was blocked; the expression of Bax protein was substantially increased; and Bcl-2 protein was downregulated. Taken together, the data suggest that ICI 118551 potentiates the antiproliferative effects of gemcitabine by inducing apoptosis in pancreatic cancer cells. Our study implies that this combination may be an effective therapeutic strategy for pancreatic cancer.