Butyrate-mediated acquisition of chemoresistance by human colon cancer cells

Butyrate is a short-chain fatty acid produced by the intestinal microflora and it not only induces apoptosis but also inhibits the proliferation of cancer cells. Recently, it has been reported that butyrate may cause resistance in colon cancer cells. Therefore, we investigated the effects of increased resistance to butyrate in HCT116 colon cancer cells. We established HCT116 cells resistant to butyrate (HCT116/BR) by treating HCT116 parental cells (HCT116/PT) with increasing concentrations of butyrate to a maximum of 1.6 mM for 3 months. The butyrate concentrations that inhibited cell growth by 50% (IC50) were 0.508 and 5.50 mM in HCT116/PT and HCT116/BR cells. The values after treatment with paclitaxel, 5-fluorouracil (5-FU), doxorubicin and trichostatin A (TSA) were 2.42, 2.36, 4.31 and 11.3-fold higher, respectively, in HCT116/BR cells compared with HCT116/PT cells. The protein expression of drug efflux pumps, such as P-glycoprotein (P-gp), breast cancer-resistant protein (BCRP) and the multidrug resistance associated protein 1 (MRP1), did not differ between HCT116/PT and HCT116/BR cells. The expression level of the anti-apoptotic Bcl-xL protein was increased while those of pro-apoptotic Bax and Bim proteins were reduced in HCT116/BR cells. There were no significant differences in cell motility and invasion. This study suggests that exposure of colon cancer cells to butyrate results in development of resistance to butyrate, which may play a role in the acquisition of chemoresistance in colon cancer.

Novel piroxicam-loaded nanospheres generated by the electrospraying technique: physicochemical characterisation and oral bioavailability evaluation

To determine if a novel electrospraying technique could be applied to an oral drug delivery system for improving the solubility and oral bioavailability of poorly water-soluble piroxicam; the nanospheres were generated with drug and polyvinylpyrrolidone (PVP) using electrospraying technique; and their physicochemical properties, solubility, release and pharmacokinetics were evaluated in comparison with piroxicam powder. All nanospheres had significantly increased drug solubility and dissolution rates in comparison with the drug powder. In particular, the nanosphere composed of piroxicam and PVP at a weight ratio of 2:8 gave about 600-fold higher solubility, 15-fold higher release rate and 3-fold higher AUC in comparison to piroxicam powder, leading to significantly enhanced oral bioavailability in rats, due to the mingled effect of nanonisation along with transformation to the amorphous state. Thus, this electrospraying technique can be utilised to produce a novel oral nanosphere delivery system with enhanced solubility and oral bioavailability for poorly water-soluble piroxicam.

Pharmacokinetics of YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, in rats

YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, was developed for treating asthma and atopic dermatitis. We studied the pharmacokinetic characteristics of YJC-10592 after intravenous (5, 10 and 20 mg/kg) and oral (100 and 200 mg/kg) administration of the drug to rats. Tissue distribution of YJC-10592 was also evaluated after intravenous administration of YJC-10592, 10 mg/kg, to rats. The pharmacokinetics of YJC-10592 was dose-dependent from 20 mg/kg after intravenous administration to rats. The values of the area under the plasma concentration-time curve from time zero to infinity (AUC) of YJC-10592 were dose-dependent from 20 mg/kg and the time-averaged total body (CL) and nonrenal (CLNR) clearances of YJC-10592 were significantly lower at dose of 20 mg/kg, suggesting that saturable metabolism may be involved. The absolute bioavailability (F) of YJC-10592 was generally low (<2.55 %) for both oral doses due to incomplete absorption and low urinary excretion. YJC-10592 had a great affinity to all rat tissues studied except brain, which was supported by a relatively high value of the apparent volume of distribution at steady state (V ss) (890-1385 mL/kg). In conclusion, YJC-10592 showed dose-dependent pharmacokinetics and low F value due to slower elimination and incomplete absorption.

The psychometric properties of the Quantitative-Checklist for Autism in Toddlers (Q-CHAT) as a measure of autistic traits in a community sample of Singaporean infants and toddlers

Background

There is growing research evidence that subclinical autistic traits are elevated in relatives of individuals with autism spectrum disorder (ASD), continuously distributed in the general population and likely to share common etiology with ASD. A number of measures have been developed to assess autistic traits quantitatively in unselected samples. So far, the Quantitative-Checklist for Autism in Toddlers (Q-CHAT) is one of very few measures developed for use with toddlers as young as 18 months, but little is known about its measurement properties and factor structure.

Methods

The present study examined internal consistency, factor structure, test-retest stability, and convergent validity of the Q-CHAT in a sample of toddlers in Singapore whose caregivers completed the Q-CHAT at 18 (n = 368) and 24 months (n = 396).

Results

Three factors were derived accounting for 38.1 % of the variance: social/communication traits, non-social/behavioral traits, and a speech/language factor. Internal consistency was suboptimal for the total and speech/language scores, but acceptable for the social/communication and non-social/behavioral factor scores. Scores were generally stable between 18 and 24 months. Convergent validity was found with the Pervasive Developmental Disorders subscale of the Child Behavior Checklist (CBCL) completed by caregivers when their children were 24 months. Q-CHAT total scores in this sample were higher than those reported in other unselected samples from the UK.

Conclusions

The Q-CHAT was found to have a three-factor structure, acceptable internal consistency for its two main factor scores (social/communication and non-social/behavioral), normally distributed scores in an unselected sample, and similar structure and measurement properties as those reported in other published studies. Findings are discussed in relation to existing literature and future directions for the validation of the Q-CHAT.

Solid self-nanoemulsifying drug delivery system (SNEDDS) for enhanced oral bioavailability of poorly water-soluble tacrolimus: physicochemical characterisation and pharmacokinetics

To develop a novel self-nanoemulsifying drug delivery system (solid SNEDDS) with better oral bioavailability of tacrolimus, the solid SNEDDS was obtained by spray-drying the solutions containing the liquid SNEDDS and colloidal silica. Its reconstitution properties were determined and correlated to solid state characterisation of the powder. Moreover, the dissolution and pharmacokinetics in rats was done in comparison to the commercial product. Among the liquid SNEDDS formulations tested, the liquid SNEDDS comprised of Capryol PGMC, Transcutol HP and Labrasol (10:15:75, v/v/v) presented the highest dissolution rate. In the solid SNEDDS, this liquid SNEDDS was absorbed in the pores and attached onto the surface of the colloidal silica. Drug was present in the amorphous state in it. The solid SNEDDS with 5% w/v tacrolimus produced the nanoemulsions and improved the oral bioavailability of tacrolimus in rats. Therefore, this solid SNEDDS would be a potential candidate for enhancing the oral bioavailability of tacrolimus.

Effects of triglycerides on the hydrophobic drug loading capacity of saturated phosphatidylcholine-based liposomes

A high drug-loading capacity is a critical factor for the clinical development of liposomal formulations. The accommodation of hydrophobic drugs within the liposomal membrane is often limited in saturated phosphatidylcholine (PC)-based liposomes owing to the rigidity of the lipid acyl chain. In the current study, we explored the possibility of improving the hydrophobic drug loading capacity of liposomes by incorporating triglyceride into liposomal membranes. Incorporation of Captex 300, a medium chain triglyceride, into liposomes composed of dimyristoylphosphatidylcholine and cholesterol greatly increased the fluidity and lamellarity of the resultant liposomes. Liposomal incorporation of medium or long chain, but not short chain, triglycerides greatly enhanced the concentration of loaded paclitaxel (PTX) in saturated PC-based liposomes. The enhancing effect of triglyceride saturated at a triglyceride content corresponding to the amount required to fluidize the liposome structure. In addition, the enhancing effect was not observed in unsaturated PC-based liposomes and was not associated with the solubility of PTX in each triglyceride. Triglycerides also enhanced the loading of docetaxel, another hydrophobic drug. Taken together, our results suggest that triglyceride incorporation in saturated PC-based liposomes provide an improved dosage form that enables increased hydrophobic drug loading by altering the fluidity and structure of liposomal membranes.

Increased chemoresistance to paclitaxel in the MCF10AT series of human breast epithelial cancer cells

The MCF10AT cell series of human breast epithelial cancer cells includes normal MCF10A (10A), premalignant MCF10AT (10AT) and MCF10ATG3B (10ATG3B), and fully malignant MCF10CA1a (10CA1a) cells. The series is a unique model system showing progressive tumorigenic potential with the same origin. The effects of paclitaxel, a microtubule inhibitor, were evaluated in this cell system. Paclitaxel inhibited cell proliferation in a time-dependent (24, 48 and 72 h) and concentration-dependent (0-10 nM) manners with less sensitivity in 10CA1a cells. Treatment with paclitaxel (10 nM) for 24 h induced apoptosis in 10A, 10AT, 10ATG3B and 10CA1a cells, with 23.6, 26.1, 25.2 and 8.96%, respectively, in the sub-G1 phase. Treatment with paclitaxel (0-10 nM) for 24 h, resulted in the appearance of DNA fragmentation (a hallmark of apoptosis) with less sensitivity in the 10CA1a tumor cells. Paclitaxel increased p53 protein expression in 10A, 10AT, 10ATG3B and 10CA1a cells, by 87, 102, 812 and 84%, respectively. The p21Waf1/Cip1 protein expression increased by 2.57-, 1.53- and 2.48-fold in 10A, 10AT and 10ATG3B cells, respectively, with negligible detection in the 10CA1a cells. Activation of the Akt signaling pathway was observed in the MCF10AT cell lineage and the protein expression of phospho-Akt (Ser473 and Thr308). The downstream targets of this pathway, phospho-p70S6K and phospho-S6RP, were also inhibited by paclitaxel in 10A, 10AT and 10ATG3B cells, but minimally inhibited in 10CA1a cells, suggestive of chemoresistance in 10CA1a cells. The effects of paclitaxel on the multidrug resistance 1 (MDR1), MRP1 and breast cancer resistance protein (BCRP) gene expression were not significant in the MCF10AT cell lineage. These results collectively indicated that paclitaxel inhibited cell proliferation and induced apoptosis in the MCF10AT cell lineage, with chemoresistance in 10CA1a tumor cells. The decreased responsiveness to paclitaxel observed in 10CA1a tumor cells was likely due, in part, to activation of the Akt signaling pathway and a high expression of wild-type p53 with lack of p21Waf1/Cip1.

Fluorescent iodized emulsion for pre- and intraoperative sentinel lymph node imaging: validation in a preclinical model

PURPOSE

To validate the usefulness of a newly developed tracer for preoperative gastric sentinel lymph node (LN) (SLN) mapping and intraoperative navigation after a single preoperative submucosal injection in rat and beagle models.

MATERIALS AND METHODS

This study was approved by the Experimental Animal Ethical Committee of Yonsei University College of Medicine according to the eighth edition of the Guide for the Care and Use of Laboratory Animals published in 2011. An emulsion was developed that contained indocyanine green in iodized oil, which can be visualized with both computed tomography (CT) and near-infrared (NIR) optical imaging and has the property of delayed washout. This emulsion was injected into the footpad of rats (n = 6) and the gastric submucosa of beagles (n = 8). CT lymphography was performed. The degree of enhancement of popliteal LNs was measured in rats, and the enhancing LNs were identified and the degree of enhancement of the enhancing LNs was measured in beagles. Next, NIR imaging was performed in beagles during open, laparoscopic, and robotic surgery to identify LNs containing the fluorescent signals of indocyanine green. The enhanced LNs detected with CT lymphography and NIR imaging were matched to see if they corresponded.

RESULTS

Preoperative CT lymphography facilitated SLN mapping, and 26 SLNs were identified in eight beagles. NIR imaging enabled high-spatial-resolution visualization of both SLNs and the intervening lymphatic vessels and was useful for intraoperative SLN navigation.

CONCLUSION

SLN mapping with fluorescent iodized oil emulsion is effective and feasible for both CT and NIR imaging.

Formulation and in vitro and in vivo evaluation of a cationic emulsion as a vehicle for improving adenoviral gene transfer

Advancements in the use of adenoviral vectors in gene therapy have been limited by the need for specific receptors on targeted cell types, immunogenicity and hepatotoxicity following systemic administration. In an effort to overcome the current limitations of adenovirus-mediated gene transfer, cationic emulsions were explored as a vehicle to improve adenoviral vector-mediated gene transfer. Complexation of adenovirus with emulsions containing the cationic lipid 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) enhanced the potency of adenoviral gene transfer as compared to DOTAP liposomes. Among the various emulsion formulations examined, those containing the iodized oil, Lipiodol, as an inner core and stabilized by DOTAP/cholesterol/1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(poly-ethylene glycol)-5000 most efficiently enhanced adenovirus-mediated gene transfer. Optimized Lipiodol-containing emulsions appear to be more strongly associated with adenoviral particles, exhibiting higher complex stability compared to other formulations. They provide the adenovirus with an additional cellular entry mechanism through caveolae-dependent endocytosis, thereby increasing adenovirus entry into cells. Furthermore, adenovirus-emulsion complexation significantly reduced transgene expression in the liver following systemic administration. These findings indicate that emulsion complexation may be a promising strategy for overcoming many of the challenges associated with the use of adenoviruses in gene therapy. Additionally, the observation of increased transgene expression in lung together with reduced expression in liver demonstrates that the adenovirus-emulsion complex may act as a lung-targeting adenoviral gene delivery system.

Long chain microRNA conjugates in calcium phosphate nanoparticles for efficient formulation and delivery

A long chain microRNA-34a conjugate (lc-miRNA) was prepared by chemical crosslinking in order to improve entrapment efficiency into calcium phosphate nanoparticles (CaPs) and intracellular delivery. Thiol-modified miRNA at both terminal ends was chemically conjugated using crosslinkers to form lc-miRNA which was encapsulated within CaPs by a conventional co-precipitation method. Encapsulation efficiencies, physicochemical properties, and in vitro intracellular delivery efficiencies of the prepared linear polyethyleneimine (LPEI)-coated CaPs (LPEI-CaP) containing common miRNA and lc-miRNA were comparatively evaluated. The prepared lc-miRNA exhibited noticeably enhanced encapsulation efficiency during the CaP formulation process when compared to common miRNA. LPEI-CaP/lc-miRNAs consisted of nano-sized particles with great homogeneity and were observed to be successfully delivered into PC-3 cells. Fabricated LPEI-CaPs with duplex form of lc-miRNA (lc-miRNA-d) suppressed cancer cell proliferation as well as migration much more efficiently than those with duplex form of miRNA (miRNA-d). In addition, LPEI-CaP/lc-miRNA-d conferred negligible cytotoxicity on PC-3 cells. Chemical crosslinking of therapeutic miRNAs via a reducible linkage may allow more efficient encapsulation within CaPs as well as homogeneous particle formulation due to a higher spatial charge density than common miRNAs. The well-formulated LPEI-CaPs with lc-miRNA-d have the potential to provide superior miRNA transfection efficiency and inhibition of cancer proliferation.

Computed tomography-guided screening of surfactant effect on blood circulation time of emulsions: application to the design of an emulsion formulation for paclitaxel

PURPOSE

In an effort to apply the imaging techniques currently used in disease diagnosis for monitoring the pharmacokinetics and biodisposition of particulate drug carriers, we sought to use computed tomography (CT) scanning methodology to investigate the impact of surfactant on the blood residence time of emulsions.

METHODS

We prepared the iodinated oil Lipiodol emulsions with different compositions of surfactants and investigated the impact of surfactant on the blood residence time of emulsions by CT scanning.

RESULTS

The blood circulation time of emulsions was prolonged by including Tween 80 or DSPE-PEG (polyethylene glycol 2000) in emulsions. Tween 80 was less effective than DSPE-PEG in terms of prolongation effect, but the blood circulating time of emulsions was prolonged in a Tween 80 content-dependent manner. As a proof-of-concept demonstration of the usefulness of CT-guided screening in the process of formulating drugs that need to be loaded in emulsions, paclitaxel was loaded in emulsions prepared with 87 or 65% Tween 80-containing surfactant mixtures. A pharmacokinetics study showed that paclitaxel loaded in 87% Tween 80 emulsions circulated longer in the bloodstream compared to those in 65% Tween 80 emulsions, as predicted by CT imaging.

CONCLUSIONS

CT-visible, Lipiodol emulsions enabled the simple evaluation of surfactant composition effects on the biodisposition of emulsions.

Effect of butyrate on the heregulin/ErbB-mediated proliferation of human colorectal cancer cells

The expression of ErbB proteins, together with heregulin, was found to be increased in colon cancer cells compared with normal mucosa, and heregulin-stimulated activation of ErbB signaling was observed to contribute to the proliferation of colon cancer cells. Butyrate produced during the fermentation of fiber by intestinal bacteria is known to exert diverse anticancer effects, including the induction of differentiation, cell cycle arrest and growth suppression in human colon cancer cells. In this study, we investigated whether butyrate affects the heregulin/ErbB-mediated proliferation of colon cancer cells. The growth of human CaCo-2 and SNU-C4 colon cancer cells, which express ErbB1-4 proteins, was stimulated by heregulin in a concentration-dependent manner. Pretreatment with sodium butyrate abolished heregulin-stimulated proliferation in both cell lines. Although butyrate did not alter ErbB protein expression and activation, it did block the prolonged activation of Akt and Erk1/2, which are known to be important ErbB downstream molecules mediating heregulin-stimulated proliferation. Our data suggest that the inhibitory effects of butyrate on the heregulin-stimulated proliferation of colorectal cancer cells are, in part, associated with the suppression of the Akt and Erk signaling pathway. Butyrate may act as a preventive and therapeutic agent in the progression of colorectal cancer through the regulation of heregulin-stimulated mitogenic signaling.

Docosahexaenoic acid sensitizes colon cancer cells to sulindac sulfide-induced apoptosis

Sulindac analogs represent one of the most efficacious groups of NSAIDs reducing the risk of colon cancer. Recent studies have shown that sulindac sulfide, a sulindac analog effective at lower doses compared to its parent compound, triggers the death receptor (DR)5-dependent extrinsic apoptotic pathway. Induction of apoptosis via activation of the DR-mediated pathway would be an ideal therapeutic strategy to eliminate cancer cells. In this study, we investigated the possibility that colon cancer cells are sensitized to sulindac sulfide-induced apoptosis by docosahexaenoic acid (DHA), via activation of the DR/extrinsic apoptotic pathway. Our data demonstrated that DHA combination sensitized colon cancer cells to sulindac sulfide-induced apoptosis, leading to enhanced growth suppression of human colon cancer xenografts. The combination effect was primarily attributed to increased cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-8 activation. Moreover, pretreatment with z-IETD-FMK (caspase-8 inhibitor) or stable expression of dominant negative caspase-8 genes blocked DHA/sulindac sulfide cotreatment-induced apoptosis. In view of the finding that DR5 silencing abrogated the combination-stimulated apoptosis, we propose that apoptotic synergy induced by sulindac sulfide plus DHA is mediated via DR5. Our findings collectively support the utility of a combination of sulindac sulfide and DHA in the effective prevention and treatment of colon cancer.

Comparison of three tocopherol analogs as an inhibitor of production of proinflammatory mediators in macrophages

Anti-inflammatory effects of tocopherol (TOL) analogs have been attributed to their potent antioxidant activities. However, we and others have separately reported that γTOL or α-tocopheryl succinate (αTOS), despite their lower antioxidant activities, inhibit lipopolysaccharide (LPS)-induced production of prostaglandin E(2) (PGE(2)) in macrophages and lung epithelial cells more effectively than αTOL. In the present study, we sought to directly analyze the effect of three TOL analogs (αTOL, αTOS, and γTOL) on LPS-induced production of pro-inflammatory mediators in macrophages. Our data demonstrated that the inhibitory effects of all three TOL analogs on nitric oxide production were very limited. In contrast, αTOS dose-dependently and significantly inhibited LPS-induced PGE(2) production in both RAW264.7 cells and peritoneal macrophages, whereas αTOL and γTOL were much less effective. Although αTOS had no effect on LPS-induced cyclooxygenase-2 expression, it did inhibit COX activity in intact cells. αTOS in combination with sulforaphane, a compound that blocked LPS-induced COX-2 expression, cooperatively and more significantly inhibited PGE(2) production. These findings suggest that αTOS is a more potent inhibitor of the pro-inflammatory mediator PGE(2). The inclusion of αTOS in vitamin supplements may further enhance the effectiveness of strategies for preventing diseases associated with inflammation.