An Ethanol Extract of Hawaiian Turmeric: Extensive In Vitro Anticancer Activity Against Human Colon Cancer Cells.

CONTEXT: Turmeric (Curcuma longa) is a food spice and colorant reported to be beneficial for human health. Curcumin (diferuloylmethane) is the major ingredient in turmeric, and existing data suggest that the spice, in combination with chemotherapy, provides a superior strategy for treatment of gastrointestinal cancer. However, despite its significant effects, curcumin suffers from poor bioavailability, due to poor absorption in the body. OBJECTIVE: The research team intended to evaluate a liquid extract of turmeric roots (TEx) that the team had formulated for its in vitro, anticancer activity against several human, colorectal cancer cell lines. DESIGN: The research team performed in vitro studies evaluating the anticancer efficacy via short and long-term assays and also evaluated invasion using Matrigel (Corning Life Sciences, Tewksbury, MA, USA). Further, in vitro anticancer activity of TEx was tested against 3-D cultures of HCT166 spheroids, which were subsequently analyzed by flow cytometry. SETTING: ADNA, Inc, Columbus, OH, USA; Foundation for Biomedical Research of the Academy of Athens, Athens, Greece; and Laboratory of Pharmacology, Faculty of Medicine, University of Thessaly, Larissa, Greece. INTERVENTION: The study used 4 human cell lines of colorectal cancer-HT29, HCT15, DLD1, and HCT116-and 2 breast cancer cell lines-SW480 and MDA-MB231. For a short-term assay, the extract was dissolved into culture mediums of HT29, HCT15, DLD1, HCT116, and SW480 at four 10-fold dilutions (100 to 0.1 µg/mL). For a long-term assay, TEx was added to the cultures of the same cell lines at 3 dilutions-20, 10, and 5 µg/mL. For an invasion assay, 100 µL per well of Matrigel was added and allowed to polymerize prior seeding of the MDA-MB231 cells. For cultures treated with the TEx, the TEx was mixed with the cell suspension prior to the seeding step. For the spheroid testing, the TEx was added to HCT116 cells either at the beginning of an experiment (ie, before the addition of the cancer cells), which was a chemopreventive approach, or 48 h later, on the addition of cells to the wells to allow the generation of spheroids, which was a chemotherapeutic approach. OUTCOME MEASURES: The in vitro activities of TEx were evaluated using a 48-h-incubation, short-term assay and a 2-wk, long-term (clonogenic) assay. To analyze the anti-invasive activity of the extract, images for the Matrigel invasion assay were taken with a camera at the 24-h time point. The in vitro, anticancer activity of TEx was also tested against 3-D cultures of HCT116 spheroids that were subsequently analyzed using flow cytometry. RESULTS: TEx had potently inhibited the growth of all human colon cancer cell lines tested in a dose- and time-dependent manner. TEx inhibited the formation of HCT116 spheroids when the cells were incubated with the extract. The extract also disrupted the formation of tubules formed by MDA-MB231 cells grown on Matrigel at concentrations that did not affect the overall viability of the cells, indicating a potent anti-invasive activity. CONCLUSIONS: These data suggest a potential therapeutic activity for TEx against human colon cancer, most likely due to the enhanced bioavailability of the turmeric.

In vitro activity of dietary flavonol congeners against human cancer cell lines.

BACKGROUND: Flavonoids have physiological activity and a variety of pharmacological properties, including anticancer activity in vitro, but structure-anticancer activity relationships are unclear. AIM: The objectives of this work were to investigate the activity of dietary flavonol congeners against cell lines derived from human solid tumours and to examine whether the in vitro activity was associated with specific structural feature(s) of the molecules. METHODS: Antiproliferative activity of the flavonol congeners was investigated against eight different human cancer cell lines representing different types of human solid tumour, using the sulforhodamine B (SRB) assay in accordance with the instructions published by the NCI. Cell cycle perturbations caused by the congeners were monitored by flow-cytometric analysis of DNA stained with propidium iodide. RESULTS: Most of the flavonols examined had weak antiproliferative and cytotoxic activity. Of all the flavonol congeners tested peracetylated tiliroside found to be the most powerful, with significant antiproliferative and cytotoxic activity. Most flavonols induced similar cell cycle perturbations, whereas induction of apoptosis was significant only for cells treated with peracetylated tiliroside. CONCLUSIONS: These findings indicated that the -OH groups of aromatic ring B were not linked to the cytotoxic and antiproliferative activity of the tested flavonols whereas peracetylation of the glycosides resulted in moderate improvement. In contrast, acetylation of tiliroside esterified with coumaric acid at position 5 of the sugar moiety greatly improved the activity of this congener. Overall, the results of this study suggest a critical role of sugar moiety substituents in the anticancer activity of the flavonols.

Nanoparticle-based delivery of siDCAMKL-1 increases microRNA-144 and inhibits colorectal cancer tumor growth via a Notch-1 dependent mechanism.

BACKGROUND: The development of effective drug delivery systems capable of transporting small interfering RNA (siRNA) has been elusive. We have previously reported that colorectal cancer tumor xenograft growth was arrested following treatment with liposomal preparation of siDCAMKL-1. In this report, we have utilized Nanoparticle (NP) technology to deliver DCAMKL-1 specific siRNA to knockdown potential key cancer regulators. In this study, mRNA/miRNA were analyzed using real-time RT-PCR and protein by western blot/immunohistochemistry. siDCAMKL-1 was encapsulated in Poly(lactide-co-glycolide)-based NPs (NP-siDCAMKL-1); Tumor xenografts were generated in nude mice, treated with NP-siDCAMKL-1 and DAPT (γ-secretase inhibitor) alone and in combination. To measure let-7a and miR-144 expression in vitro, HCT116 cells were transfected with plasmids encoding the firefly luciferase gene with let-7a and miR-144 miRNA binding sites in the 3'UTR. RESULTS: Administration of NP-siDCAMKL-1 into HCT116 xenografts resulted in tumor growth arrest, downregulation of proto-oncogene c-Myc and Notch-1 via let-7a and miR-144 miRNA-dependent mechanisms, respectively. A corresponding reduction in let-7a and miR-144 specific luciferase activity was observed in vitro. Moreover, an upregulation of EMT inhibitor miR-200a and downregulation of the EMT-associated transcription factors ZEB1, ZEB2, Snail and Slug were observed in vivo. Lastly, DAPT-mediated inhibition of Notch-1 resulted in HCT116 tumor growth arrest and down regulation of Notch-1 via a miR-144 dependent mechanism. CONCLUSIONS: These findings demonstrate that nanoparticle-based delivery of siRNAs directed at critical targets such as DCAMKL-1 may provide a novel approach to treat cancer through the regulation of endogenous miRNAs.

Inhibition of angiogenesis- and inflammation-inducing factors in human colon cancer cells in vitro and in ovo by free and nanoparticle-encapsulated redox dye, DCPIP.

BACKGROUND: The redox dye, DCPIP, has recently shown to exhibit anti-melanoma activity in vitro and in vivo. On the other hand, there is increasing evidence that synthetic nanoparticles can serve as highly efficient carriers of drugs and vaccines for treatment of various diseases. These nanoparticles have shown to serve as potent tools that can increase the bioavailability of the drug/vaccine by facilitating absorption or conferring sustained and improved release. Here, we describe results on the effects of free- and nanoparticle-enclosed DCPIP as anti-angiogenesis and anti-inflammation agents in a human colon cancer HCT116 cell line in vitro, and in induced angiogenesis in ovo. RESULTS: The studies described in this report indicate that (a) DCPIP inhibits proliferation of HCT116 cells in vitro; (b) DCPIP can selectively downregulate expression of the pro-angiogenesis growth factor, VEGF; (c) DCPIP inhibits activation of the transcriptional nuclear factor, NF-kappaB; (d) DCPIP can attenuate or completely inhibit VEGF-induced angiogenesis in the chick chorioallantoic membrane; (e) DCPIP at concentrations higher than 6 mug/ml induces apoptosis in HCT116 cells as confirmed by detection of caspase-3 and PARP degradation; and (f) DCPIP encapsulated in nanoparticles is equally or more effective than free DCPIP in exhibiting the aforementioned properties (a-e) in addition to reducing the expression of COX-2, and pro-inflammatory proteins IL-6 and IL-8. CONCLUSIONS: We propose that, DCPIP may serve as a potent tool to prevent or disrupt the processes of cell proliferation, tissue angiogenesis and inflammation by directly or indirectly targeting expression of specific cellular factors. We also propose that the activities of DCPIP may be long-lasting and/or enhanced if it is delivered enclosed in specific nanoparticles.

Curcumin and turmeric attenuate arsenic-induced angiogenesis in ovo.

Trivalent arsenic [As(III)] is currently approved by the FDA for the treatment of chronic and acute leukemias. However, As(III) has also demonstrated damaging effects on human health, including development of cardiovascular disease, diabetes, and cancer. Further, As(III) is a potent angiogenic agent. In this context, curcumin, an active ingredient in the dietary agent turmeric, has demonstrated potent antiproliferative, antiinflammatory, and antiangiogenic properties. In this report, we have shown that both curcumin and turmeric inhibit expression of vascular endothelial growth factor in HCT-116 human colon cancer cells exposed to As(III). Further, in the chicken chorioallantoic membrane assay model, treatment with low As(III) concentrations results in extensive increase in blood vessel density, which, however, is reduced in the presence of curcumin or turmeric. Collectively, the findings reported here strongly suggest that turmeric and curcumin can dramatically attenuate the process of angiogenesis induced by low As(III) concentrations.

14-3-3sigma-dependent resistance to cisplatin.

BACKGROUND: A major factor that impedes the clinical success of cisplatin-based chemotherapy for cancer is cisplatin resistance by cancer cells. MATERIALS AND METHODS: The sensitivity of parental HCT116 human colon cancer cell line and its isogenic gene-knockout sub-lines to cisplatin was determined by clonogenicity assay; furthermore, p53 activation, p21 expression, cell cycle arrest and senescence in these cells after cisplatin treatment were investigated. RESULTS: Parental cells were six times more resistant than 14-3-3sigma-knockout (sigma-KO) cells to cisplatin. Moreover, activation of p53, p53-dependent expression of p21 and p21-dependent senescence were observed in sigma-KO, but not parental cells after a treatment with a low cisplatin dose. CONCLUSION: A 14-3-3sigma-dependent mechanism inhibits p53 activation in parental cells treated with a low cisplatin dose, thereby blocking p21 expression that is essential for senescence and consequently conferring to the parental cells a significant degree of resistance to cisplatin.

A mastic gum extract induces suppression of growth of human colorectal tumor xenografts in immunodeficient mice.

BACKGROUND: We recently reported that ethanol and hexane extracts of the plant product, mastic gum (MG), contain constituents which can induce p53- and p21-independent G1-phase arrest followed by apoptosis of human HCT116 colon cancer cells in vitro. Herein, we extended these studies to investigate the in vivo anticancer activity of the hexane extract of MG (He-MG) against human colon tumor. The in vivo anticancer activity of He-MG was assessed in a human colon cancer/immunodeficient mouse model. MATERIALS AND METHODS: Control and HCT116 tumor bearing SCID mice were injected intraperitoneally with He-MG at different administration schedules and doses ranging from 100 to 220 mg/kg body weight and tumor growth (size) was monitored. RESULTS: He-MG administered at a dose of 200 mg/kg administered daily for 4 consecutive days (followed by 3 days without treatment) inhibited tumor growth by approximately 35% in the absence of toxicity (side-effects) after 35 days. CONCLUSION: He-MG was found to possess antitumor activity against human colorectal cancer under the experimental conditions of this study. The extent of suppression and toxicity by a specific He-MG dose depends on the schedule of administration.

Metabolism and anticancer activity of the curcumin analogue, dimethoxycurcumin.

PURPOSE: The plant-derived compound curcumin has shown promising abilities as a cancer chemoprevention and chemotherapy agent in vitro and in vivo but exhibits poor bioavailability. Therefore, there is a need to investigate modified curcumin congeners for improved anticancer activity and pharmacokinetic properties. EXPERIMENTAL DESIGN: The synthetic curcumin analogue dimethoxycurcumin was compared with curcumin for ability to inhibit proliferation and apoptosis of human HCT116 colon cancer cells in vitro by estimating the GI(50) and LC(50) values and detecting the extent of apoptosis by flow cytometry analysis of the cell cycle. Metabolic stability and/or identification of metabolites were evaluated by recently developed mass spectrometric approaches after incubation with mouse and human liver microsomes and cancer cells in vitro. Additionally, circulating levels of dimethoxycurcumin and curcumin were determined in mice following i.p. administration. RESULTS: Dimethoxycurcumin is significantly more potent than curcumin in inhibiting proliferation and inducing apoptosis in HCT116 cells treated for 48 h. Nearly 100% of curcumin but <30% of dimethoxycurcumin was degraded in cells treated for 48 h, and incubation with liver microsomes confirmed the limited metabolism of dimethoxycurcumin. Both compounds were rapidly degraded in vivo but dimethoxycurcumin was more stable. CONCLUSIONS: Compared with curcumin, dimethoxycurcumin is (a) more stable in cultured cells, (b) more potent in the ability to kill cancer cells by apoptosis, (c) less extensively metabolized in microsomal systems, and (d) more stable in vivo. It is likely that the differential extent of apoptosis induced by curcumin and dimethoxycurcumin in vitro is associated with the metabolite profiling and/or the extent of stability.

Analysis of the in vitro metabolites of diferuloylmethane (curcumin) by liquid chromatography--tandem mass spectrometry on a hybrid quadrupole linear ion trap system: newly identified metabolites.

In this study, we have described a novel approach for determining the metabolic scheme of diferuloylmethane (curcumin) in mouse and human liver microsomal preparations using a hybrid quadrupole linear ion trap mass spectrometer coupled with liquid chromatography for the detection of new metabolites. Application of various acquisition modes allowed targeted searches for metabolites with high sensitivity and selectivity using information of the mass spectral fragmentation properties of curcumin. Structural assignments for metabolites previously reported in the literature were made with confidence using the described approach. In addition, we identified curcumin metabolites that had not previously been reported, such as curcumin bisglucuronide and O-demethylated derivatives. The major pathways of curcumin metabolism in vitro have been summarized. Finally, very similar metabolic pathways of curcumin were observed in human and mouse microsomes.

Down-regulation of estrogen receptor-alpha in MCF-7 human breast cancer cells after proteasome inhibition.

The eukaryotic proteasome is a 26S ATP-dependent proteolytic complex, which possesses chymotrypsin-like, trypsin-like and peptidyl glutamyl peptide hydrolase (PGPH) activities, which enable the proteasome to degrade all short-lived and many long-lived proteins, and consequently regulate a myriad of activities in cells. In this study, we observed that inhibition of the proteasome, and more specifically, inhibition of the chymotrypsin-like activity of the proteasome, in MCF-7 human breast cancer cells resulted in selective down-regulation of the nuclear estrogen receptor-alpha (ERalpha). Our data indicated that estrogen had no effect, whereas the ERalpha antagonist, tamoxifen, reduced the amount of ERalpha that could be subjected to down-regulation after proteasome inhibition. Furthermore, our data demonstrated that protein synthesis was required for the down-regulation of ERalpha to occur. Collectively, these data indicate the existence of a proteasome-dependent mechanism that is utilized by MCF-7 cells to maintain a steady-state level of ERalpha.

Proteasome-independent down-regulation of estrogen receptor-alpha (ERalpha) in breast cancer cells treated with 4,4'-dihydroxy-trans-stilbene.

Treatment of cells with estrogens and several pure ERalpha antagonists rapidly induces down-regulation of the alpha-type estrogen receptor (ERalpha) in the nucleus by mechanisms that are sensitive to the proteasome inhibitors, MG132 and clasto-lactacystin-beta-lactone. Hence, it is believed that these ER ligands induce down-regulation of ERalpha by proteasome-dependent mechanisms, which serve to control both the amount of transcriptional activity and the level of ligand-bound ERalpha in cells. In this study, we observed that treatment of cultured MCF-7 and T47D human breast cancer cells with the low affinity ER ligand, 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), inhibited the transcriptional activity of ERalpha and induced slow and gradual decrease in the amount of ERalpha protein (henceforth referred to as down-regulation of ERalpha). The 4,4'-DHS-induced down-regulation of ERalpha in MCF-7 cells involved a mechanism that was insensitive to the two most specific proteasome inhibitors, clasto-lactacystin-beta-lactone and epoxomycin, but sensitive to MG132 at concentrations exceeding that required for maximal inhibition of the proteasome in MCF-7 cells. Therefore, 4,4'-DHS appears to induce down-regulation of ERalpha by a proteasome-independent mechanism. Here, we present data to show that both 4-OH and 4'-OH are critical for the ability of 4,4'-DHS to induce down-regulation of ERalpha and suggest that 4,4'-DHS provides a useful scaffold for development of novel ERalpha antagonists.

Apoptotic susceptibility of cancer cells selected for camptothecin resistance: gene expression profiling, functional analysis, and molecular interaction mapping.

To study the molecular mechanisms by which drug resistance develops, we compared DU145 humanprostate cancer cells with a subline selected for resistance to camptothecin. Differences in gene expression level were assessed by hybridizing the two cell types against each other using quadruplicate "Oncochip" cDNA microarrays that included 1648 cancer-related genes. Expression levels differing by a factor of >1.5 were detected for 181 of the genes. These differences were judged statistically reliable on the basis of a stratum-adjusted Kruskal-Wallis test, after taking into account a dye-dependent variable. The 181 expression-altered genes included a larger than expected number of the "apoptosis-related" genes (P = 0.04). To assess whether this observation reflected a generalized resistance of RCO.1 to apoptosis, we exposed the cells to a range of stresses (cisplatin, staurosporine, UV, ionizing radiation, and serum starvation) and found greatly reduced apoptotic responses for RC0.1 (relative to DU145) using flow cytometric Annexin V and terminal deoxynucleotidyl transferase-mediated nick end labeling assays. We next examined the apoptosis-related genes in the context of a molecular interaction map and found expression differences in the direction "expected" on the basis of the apoptosis-resistance of RC0.1 for BAD, caspase-6, and genes that signal via the Akt pathway. Exposure of the cells to wortmannin, an inhibitor of the Akt effector phosphatidylinositol 3-kinase, provided functional support for involvement of the Akt pathway. However, closer examination of the molecular interaction map revealed a paradox: many of the expression differences observed for apoptosis-related genes were in the direction "contrary" to that expected given the resistance of RC0.1. The map indicated that most of these unexpected expression differences were associated with genes involved in the nuclear factor kappa B and transforming growth factor beta pathways. Overall, the patterns that emerged suggested a two-step model for the selection process that led to resistance in RC0.1 cells. The first hypothesized step would involve a decrease in apoptotic susceptibility through changes in the apoptosis-control machinery associated with the Bcl-2 and caspase gene families, and also in antiapoptotic pathways operating through Akt/PKB. The second step would involve changes in multifunctional upstream genes (including some genes in the nuclear factor kappa B and transforming growth factor beta pathways) that can facilitate apoptosis but that would also tend to contribute to cell proliferation in the presence of drug. Thus, we propose that a downstream blockade of apoptosis was "permissive" for the selection of upstream pathway changes that would otherwise have induced apoptosis. This model is analogous to one suggested previously for the relationship between oncogene function and apoptosis in carcinogenesis.

FADD-dependent apoptosis induction in Jurkat leukemia T-cells by the resveratrol analogue, 3,4,5-trihydroxy-trans-stilbene.

The plant-produced compound, resveratrol (3,5,4'-trihydroxy-trans-stilbene, 3,4,5-THS), induces apoptosis in various human leukemia cell types in vitro, and thus appears to be a promising anti-leukemia agent. In this study, we observed that treatment of resveratrol-resistant Jurkat cells with the resveratrol analogue, 3,4,5-trihydroxy-trans-stilbene (3,4,5-THS), rapidly induced extensive apoptosis, indicating that the apoptotic activity of the analogue differed from that of the parental compound resveratrol. Indeed, we found that treatment of Jurkat cells with 3,4,5-THS, unlike treatment with resveratrol, induced activation of caspase-8 and apoptosis by a Fas-associated death domain (FADD) protein-dependent mechanism without involving the known death ligands CD95 ligand (CD95L), tumor necrosis factor alpha (TNFalpha) and TNF-related apoptosis-inducing ligand (TRAIL). Therefore, 3,4,5-THS induced activation of a FADD-dependent apoptotic mechanism that was unresponsive to the parental compound resveratrol. Therefore, the ability of 3,4,5-THS, but not resveratrol, to induce apoptosis demonstrates a structure-associated apoptotic activity of the resveratrol analogue.

Induction of apoptosis in human colon cancer HCT116 cells treated with an extract of the plant product, Chios mastic gum.

A hexane extract of the plant product Chios mastic gum (He-CMG) is demonstrated to kill human colon cancer cells in vitro via the process of anoikis. Specifically, the sequence of events includes He-CMG-induced GI-arrest of the cells, detachment of the cells from the substrate and subsequent apoptosis. Anoikis is dependent on the concentration and duration of treatment with He-CMG. Presence of the pan-caspase inhibitor, Z-VAD-fmk, did not prevent cell detachment, but it did prevent apoptosis of the detached cells indicating that the process of cell detachment, but not apoptosis, is independent of caspase activation. He-CMG-induced apoptosis is associated with activation of the initiator caspases-8, and -9 and the effector caspase-3. Caspases are activated in cells at a relatively long time after detachment, and caspase-3 activation may require caspase-8 or caspase-9 activation, as determined by using HCT116 isogenic clones impaired in apoptosis mechanisms that involve these two caspases. Finally, electron microscopy observations indicated a time-dependent appearance of morphological features both typical and non-typical of apoptosis in cells treated with He-CMG for various periods of time. Taken together, the results demonstrated that He-CMG induces apoptosis in HCT116 cells and, therefore, further in vivo and in vitro studies of the anticancer activities of this plant product are warranted.

Reduction of 9-nitrocamptothecin-triggered apoptosis in DU-145 human prostate cancer cells by ectopic expression of 14-3-3zeta.

A promising family of anticancer agents, the camptothecins, is noted for their ability to induce apoptosis specifically in malignant cells. However, a major obstacle for successful cancer treatment by these and other chemotherapeutic agents is the intrinsic or acquired resistance to drug treatment. Resistance to 9NC6, a camptothecin derivative, has been modeled in vitro using a human prostate cancer cell line. To elucidate the mechanism for acquired 9NC resistance, we have used a subtractive cloning approach to identify genes whose altered expression level is reflective of 9NC resistance or susceptibility. Differential gene expression was compared between wild-type human prostate cancer cell line, DU-145, and a 9NC-resistant subline, RC1. Results were confirmed by Northern and Western blot analyses. In this report, we focus on one gene, 14-3-3zeta. An expression vector of a full-length myc-epitope-tagged 14-3-3zeta cDNA was constructed and used for transfection into DU-145 cells. We consistently observed that 14-3-3zeta message and protein levels were dramatically increased in 9NC resistant cells. The expression levels of other 14-3-3 family members were unaffected. Strikingly, ectopic overexpression of 14-3-3zeta in wild-type 9NC-susceptible prostate cancer cells decreased 9NC-induced apoptosis. Our results suggest a novel direct or indirect role of 14-3-3zeta in mediating resistance of DU-145 cells to the topoisomerase I inhibitor, 9NC. We are currently exploring whether this represents a more general pathway for drug resistance as well.

Camptothecin and 9-nitrocamptothecin (9NC) as anti-cancer, anti-HIV and cell-differentiation agents. Development of resistance, enhancement of 9NC-induced activities and combination treatments in cell and animal models.

The anticancer drug, 9-nitrocamptothecin (9NC), has demonstrated an unprecedented activity against human caner cells grown in cultures and as xenografts in nude mice. 9NC-induced apoptosis of cancer cells is mediated by the nuclear enzyme, topoisomerase I, and executed by pathways that involve cytochrome c release from the mitochondrion and/or activation of death receptors depending on the cell type. Alternatively, 9NC has exhibited ability to induce differentiation or senescence of certain cell types in vitro. In several instances, the 9NC activities can be regulated by Bcl-2 family proteins and cell cycle-associated proteins, p53, p21 and Cdks. Also, 9NC can inhibit HIV replication in infected T- and monocytic cells in vitro. Development of resistance to 9NC, associated with mutations in the topoisomerase I gene, can be overcome by regulating specific proteins, such as RKIP, other than topoisomerase I. Finally, derivatives (i.e., alkyl esters) of 9NC, liposome-encapsulated 9NC and combined treatment of 9NC with ionizing radiation or hyperthermia are other approaches to enhance the apoptotic activity of 9NC against human cancer cells.

The antibacterial drug taurolidine induces apoptosis by a mitochondrial cytochrome c-dependent mechanism.

The antibacterial agent taurolidine (TRD) has been used as a lavage antibiotic to prevent development of peritonitis in patients after surgery. We recently showed that TRD induced growth arrest and apoptosis of a variety of cultured cell lines derived from human solid tumors and also significantly inhibited the growth of human ovarian tumors in a mouse model. In this report, we present data to show that TRD, at concentrations below the doses that are used to treat patients in the clinic, induces apoptosis of human leukemia HL-60 cells by a mitochondrial cytochrome c-dependent pathway.

XMD8-92 inhibits pancreatic tumor xenograft growth via a DCLK1-dependent mechanism.

XMD8-92 is a kinase inhibitor with anti-cancer activity against lung and cervical cancers, but its effect on pancreatic ductal adenocarcinoma (PDAC) remains unknown. Doublecortin-like kinase1 (DCLK1) is upregulated in various cancers including PDAC. In this study, we showed that XMD8-92 inhibits AsPC-1 cancer cell proliferation and tumor xenograft growth. XMD8-92 treated tumors demonstrated significant downregulation of DCLK1 and several of its downstream targets (including c-MYC, KRAS, NOTCH1, ZEB1, ZEB2, SNAIL, SLUG, OCT4, SOX2, NANOG, KLF4, LIN28, VEGFR1, and VEGFR2) via upregulation of tumor suppressor miRNAs let-7a, miR-144, miR-200a-c, and miR-143/145; it did not however affect BMK1 downstream genes p21 and p53. These data taken together suggest that XMD8-92 treatment results in inhibition of DCLK1 and downstream oncogenic pathways (EMT, pluripotency, angiogenesis and anti-apoptotic), and is a promising chemotherapeutic agent against PDAC.

DCLK1 regulates pluripotency and angiogenic factors via microRNA-dependent mechanisms in pancreatic cancer.

Stem cell pluripotency, angiogenesis and epithelial-mesenchymal transition (EMT) have been shown to be significantly upregulated in pancreatic ductal adenocarcinoma (PDAC) and many other aggressive cancers. The dysregulation of these processes is believed to play key roles in tumor initiation, progression, and metastasis, and is contributory to PDAC being the fourth leading cause of cancer-related deaths in the US. The tumor suppressor miRNA miR-145 downregulates critical pluripotency factors and oncogenes and results in repressed metastatic potential in PDAC. Additionally, the miR-200 family regulates several angiogenic factors which have been linked to metastasis in many solid tumors. We have previously demonstrated that downregulation of DCLK1 can upregulate critical miRNAs in both in vitro and in vivo cancer models and results in downregulation of c-MYC, KRAS, NOTCH1 and EMT-related transcription factors. A recent report has also shown that Dclk1 can distinguish between normal and tumor stem cells in Apc (min/+) mice and that ablation of Dclk1(+) cells resulted in regression of intestinal polyps without affecting homeostasis. Here we demonstrate that the knockdown of DCLK1 using poly(lactide-co-glycolide)-encapsulated-DCLK1-siRNA results in AsPC1 tumor growth arrest. Examination of xenograft tumors revealed, (a) increased miR-145 which results in decreased pluripotency maintenance factors OCT4, SOX2, NANOG, KLF4 as well as KRAS and RREB1; (b) increased let-7a which results in decreased pluripotency factor LIN28B; and (c) increased miR-200 which results in decreased VEGFR1, VEGFR2 and EMT-related transcription factors ZEB1, ZEB2, SNAIL and SLUG. Specificity of DCLK1 post-transcriptional regulation of the downstream targets of miR-145, miR-200 and let-7a was accomplished utilizing a luciferase-based reporter assay. We conclude that DCLK1 plays a significant master regulatory role in pancreatic tumorigenesis through the regulation of multiple tumor suppressor miRNAs and their downstream pro-tumorigenic pathways. This novel concept of targeting DCLK1 alone has several advantages over targeting single pathway or miRNA-based therapies for PDAC.

Review: Chios mastic gum: a plant-produced resin exhibiting numerous diverse pharmaceutical and biomedical properties.

Chios mastic gum (CMG) is a resin produced by the plant Pistacia lentiscus var. chia. CMG is used to extract the mastic gum essential oil (MGO). CMG and MGO consist of nearly 70 constituents and have demonstrated numerous and diverse biomedical and pharmacological properties including (a) eradication of bacteria and fungi that may cause peptic ulcers, tooth plaque formation and malodor of the mouth and saliva; (b) amelioration or dramatic reduction of symptoms of autoimmune diseases by inhibiting production of pro-inflammatory substances by activated macrophages, production of cytokines by peripheral blood mononuclear cells in patients with active Crohn's disease, and suppression of production of inflammatory cytokines and chemokines in an asthma model in mice; (c) protection of the cardiovascular system by effectively lowering the levels of total serum cholesterol, low-density lipoprotein and triglycerides in rats, and protection of low-density lipoprotein from oxidation in humans; (d) induction of apoptosis in human cancer cells in vitro and extensive inhibition of growth of human tumors xenografted in immunodeficient mice; and (e) improvement of symptoms in patients with functional dyspepsia. Collectively taken, these numerous and diverse medical and pharmaceutical properties of CMG and MGO warrant further research in an effort to enhance specific properties and identify specific constituent(s) that might be associated with each property.