Celecoxib attenuates 5-fluorouracil-induced apoptosis in HCT-15 and HT-29 human colon cancer cells

Repositioning of simvastatin for diabetic colon cancer: role of CDK4 inhibition and apoptosis

There is increased risk of colon cancer in both men and women having diabetes. The objective of the study was to evaluate the role of simvastatin in colon cancer associated with type 2 diabetes mellitus. Diabetes was induced by administering high fat diet with low dose streptozotocin model. 1,2 dimethylhydrazine (25 mg/kg, sc) was used for colon cancer induction. MTT assay, scratch assay, clonogenic assay and annexin V-FITC assay using flow cytometry were performed on HCT-15 cell line. Simvastatin controlled diabetes and colon cancer in animal models and reduced mRNA expression of CDK4 in colon tissues. In vitro studies revealed that simvastatin showed a decrease in cell viability and produced dose dependent decrease in clone formation. There was decrease in the rate of migration with increase in concentration of simvastatin in scratch assay. Moreover, simvastatin induced apoptosis as depicted from annexin V-FITC assay using flow cytometry as well as that revealed by tunnel assay. Our data suggest that simvastatin exhibits protective role in colon cancer associated with diabetes mellitus and acts possibly via down regulation of CDK4 and induction of apoptosis and hence can be considered for repositioning in diabetic colon cancer.

In Vitro Assessment of the Synergistic Effect of Aspirin and 5-Fluorouracil in Colorectal Adenocarcinoma Cells

Although remarkable progress has been made, colorectal cancer remains a significant global health issue. One of the most challenging aspects of cancer treatment is the resistance of tumor cells to classical chemotherapy. Conventional therapy for colorectal cancer often involves the use of 5-fluorouracil as a chemotherapeutic agent. Aspirin, a drug used primarily to prevent cardiovascular complications, became a focus of attention due to its potential use as an antitumor agent. The purpose of the study was to evaluate the potential synergistic cytotoxic effects of aspirin and 5-fluorouracil on colorectal adenocarcinoma cells. The viability of cells, the impact on the morphology and nuclei of cells, the potential antimigratory effect, and the impact on the expression of the major genes associated with cell apoptosis (Bcl-2, Bax, Bad), as well as caspases 3 and 8, were evaluated. The results indicated that the two compounds exerted a synergistic effect, causing a reduction in cell viability accompanied by changes characteristic of the apoptosis process-the condensation of nuclei and the reorganization of actin filaments in cells, the reduction in the expression of the Bcl-2 gene, and the increase in the expression of Bax and Bad genes, along with caspases 3 and 8. Considering all these findings, it appears that aspirin may be investigated in depth in order to be used in conjunction with 5-fluorouracil to increase antitumor activity.

Effect of Ketorolac on Pharmacokinetics and Pharmacodynamics of 5-Fluorouracil: In Vivo and In Vitro Study

Background. This study aimed to evaluate the impact of ketorolac on the pharmacokinetics of 5-FU and its effect on the efficacy of 5-fluorouracil (5-FU) on the HT-29 cell line. Methods. Cell culture: the HT-29 cell line was treated with different concentrations of 5-FU, ketorolac, and combination of 5-FU and ketorolac for 24 and 48 hours. The cell viability (%) was calculated by the MTT assay. Animal study: rats were randomly divided into control and pretreatment groups. The control group received physiological saline, whereas the pretreatment group received ketorolac by intraperitoneal (i.p.) injections on a daily basis for 14 days. On the 15th day, both groups received 5-FU (i.p.). Blood samples were collected at different times for HPLC analysis, and 5-FU pharmacokinetic parameters were calculated. Results. At cell culture study, in a certain concentration range, combination therapy showed synergistic effects (<0.05). However, at concentrations above this range, combination therapy showed antagonistic effects on 5-FU efficacy (<0.05). According to the pharmacokinetic analysis, pretreatment with ketorolac resulted in a significant increase in AUC, Cmax, and Tmax of 5-FU (<0.05) and a significant decrease in V/F and Cl/F of 5-FU (<0.05). Conclusions. Combination therapy with ketorolac and 5-FU, depending on time and concentration, has a synergistic effect on reducing the viability of cancer cells. Also, ketorolac is able to alter the pharmacokinetics of 5-FU. Since there is a close relationship between pharmacokinetic parameters of 5-FU and its effectiveness/toxicity, it seems that these changes are towards creating a synergistic effect on 5-FU cytotoxicity. These results suggest the need to optimize the dose of these drugs in order to increase clinical efficacy and reduce the toxicity associated with them.

Synergistic potential of dual andrographolide and melatonin targeting of metastatic colon cancer cells: Using the Chou-Talalay combination index method

Colorectal cancer (CRC) mortality has diminished for decades due to new and improved treatment profiles. However, CRC still ranks as the third most diagnosed cancer in the US. Therefore, a new therapeutic approach is needed to overcome colospheroids inhibition and drug resistance. It is well documented that andrographolide (AGP) and melatonin (MLT) have anti-carcinogenic properties. Our goal was to evaluate their synergistic effects on metastatic colon cancer cells (mCRC) and colospheroids. HT-29 and HCT-15 mCRC cells were simultaneously treated with serial dilutions of AGP and MLT for 24, 48 and 72 h. Cell viability was monitored using the MTT assay. The Chou-Talalay method for drug combination is based on the median effect equation, providing a theoretical basis for the combination index and the isobologram equation. This allows quantitative determination of drug interactions using the CompuSyn software, where CI < 1, = 1, and >1 indicates synergistic, additive, and antagonistic effects respectively. Our results demonstrate that AGP and MLT in combination show synergism with CI values of 0.35293 and 0.34152 for HT-29 and HCT-15 respectively and a fractional inhibition of Fa = 0.50-0.90, as shown by the Fa-CI plot and isobologram. The synergism value was validated in colospheroids (HT-29-s and HCT-15-s) based on morphology, viability, and colony formation and in 5-FU drug resistant cell (HT-29R and HCT-116R) viability. The mechanism(s) of decreased cell viability are due to the induction of ER stress proteins and angiogenic inhibition. Our results provide rationale for using AGP in combination with MLT on mCRC.

Celecoxib induces apoptosis through Akt inhibition in 5-fluorouracil-resistant gastric cancer cells

Gastric cancer is the fifth leading cause of cancer and a global public health problem. 5-Fluorouracil (5-FU) is the primary drug chosen for the treatment of advanced gastric cancer, but acquired cancer drug resistance limits its effectiveness and clinical use. Proliferation assays showed that a gastric carcinoma cell line, AGS and 5-FU-resistant AGS cells (AGS FR) treated with 3-100 μM 5-FU for 48 h or 72 h showed different sensitivities to 5-FU. Immunoblot assay demonstrated that AGS FR cells expressed more COX-2 and PGE₂-cognated receptor EP2 than AGS cells. AGS FR cells considerably produced PGE₂ than AGS upon stimulation with 5-FU. These results suggest that COX-2 expression is associated with 5-FU resistance. Unlike AGS FR cells, AGS cells showed increased levels of both cleaved caspase-3 and Bax following 5-FU treatment. Treatment of cells with the COX-2 selective inhibitor celecoxib induced cell death of AGS FR cells in a time- and concentration-dependent manner. FACS analysis showed that celecoxib at high doses caused apoptotic cell death, demonstrating a concentration-dependent increase in the cell populations undergoing early apoptosis and late apoptosis. This apoptotic induction was strongly supported by the expression profiles of apoptosis- and survival-associated proteins in response to celecoxib; pro-apoptotic cellular proteins increased while expressions of COX-2 and p-Akt were downregulated in a concentration-dependent manner. An increase in PTEN expression was accompanied with downregulation of p-Akt. Based on the data that downregulation of COX-2 was correlated with the concentrations of celecoxib, COX-2 may play a key role in celecoxib-induced cell death of AGS FR cells. Butaprost, the EP2 agonist, promoted proliferative activity of AGS FR cells in a concentration-dependent manner compared with AGS cells. In cells exposed to butaprost, expressions of COX-2 and p-Akt were increased in a concentration-dependent manner with concomitantly reduced PTEN levels. Taken together, 5-FU-resistance in gastric cancer is correlated with COX-2 expression, and therefore the selective inhibition of COX-2 leads to suppression of cell proliferation of AGS FR cells. Modulation of COX-2 expression and its catalytic activity may be a potential therapeutic strategy to overcome 5-FU-resistant gastric cancer.

Red American ginseng enhances the effect of fluorouracil on human colon cancer cells via both paraptosis and apoptosis pathways

INTRODUCTION

As a commonly used chemotherapeutic agent, fluorouracil (5-FU) has serious dose-limiting side effects. In this study, we evaluated the synergy between red American ginseng (RAG) and 5-FU on human colorectal cancer cells, and explored the potential mechanisms.

METHODS

Ginsenoside contents of white American ginseng (WAG) and RAG were determined by HPLC. Cell proliferation was evaluated by MTS assay. Combination Index (CI) analysis was executed using CompuSyn software. Paraptotic events were observed after crystal violet staining. Cell cycle distribution, cyclin A expression and apoptotic induction were analyzed using flow cytometry.

RESULTS

We observed the heat treatment remarkably increased levels of ginsenoside Rg3, 20R-Rg3, Rk1 and Rg5. When the combinations of 5-FU and RAG were applied, cell proliferation inhibition rates were notably increased, indicating that RAG significantly enhanced 5-FU's effect. Additionally, CI analysis suggested that there was a synergistic action of 5-FU and RAG when combined. The cell cycle data indicated 5-FU induced S phase arrest, and the combination of 5-FU and RAG increased G1 phase. Further, the RAG's ability to enhance the anti-cancer effects of 5-FU was linked to both paraptosis and apoptosis inductions.

CONCLUSION

RAG may have clinical utility to decrease the dosage of 5-FU in colorectal cancer therapeutics.

Synergistic antiproliferative effects of curcumin and celecoxib in hepatocellular carcinoma HepG2 cells

Hepatocellular carcinoma (HCC) is still a leading cancer killer in the community. Molecular targeted therapy with celecoxib (CXB) has shown promising antitumor effects; however, its use may be limited due to serious side effects. Curcumin (CUR) has also shown beneficial effects against HCC. Then, it was aimed to investigate the effects of adding CUR to CXB on HCC HepG2 cells. HepG2 cells were treated with CXB and/or CUR at increasing concentrations to investigate synergistic drug interactions, as calculated combination index (CI). Combination treatment effects on cell viability and caspase-3 activation were assessed. The levels of Akt, nuclear factor-kappa B (NF-κB), prostaglandin E₂ (PGE₂), malondialdehyde (MDA), cyclin D1 (CD1), and vascular endothelial growth factor (VEGF) were also evaluated. CXB (3.13-100 μM) and/or CUR (1.25-40 μM) reduced HepG2 cell viability dose-dependently. Nevertheless, lower combined concentrations showed higher synergism (CI < 1) and higher CXB dose reduction index (DRI > 1). Also, the addition of CUR to CXB resulted in increased cytotoxicity and caspase-3 activation, as compared to CXB alone. In addition, the selected combination significantly reduced the levels of Akt, NF-κB, PGE₂, MDA, CD1, and VEGF, as compared to either agent alone. In conclusion, CUR augmented the CXB-mediated antitumor effects in HepG2 cells through, at least in part, antiproliferative, antioxidant, and pro-apoptotic mechanisms. This may allow the further use of CXB at lower concentrations, combined with CUR, as a promising safer targeted strategy for HCC management.

Repurposing of sodium valproate in colon cancer associated with diabetes mellitus: Role of HDAC inhibition

BACKGROUND AND PURPOSE

Diabetic patients are at greater risk for colon cancer. Histone deacetylases (HDACs) serve as common target for both. The key objective of the study was to evaluate the effect of sodium valproate in type 2 diabetes mellitus associated colon cancer.

EXPERIMENTAL APPROACH

High fat diet and streptozotocin were used to induce type 2 diabetes. Following this, after diabetes confirmation, colon cancer was induced using 1,2 dimethylhydrazine (25 mg/kg, s.c.) once weekly from 7th week to 20th weeks. Sodium valproate (200 mg/kg) treatment was given from 20th to 24th week. At the end of 24 weeks, several enzymatic and biochemical parameters, were estimated. MTT, clonogenic and scratch wound healing assay were carried out in HCT-15 cell line.

KEY RESULTS

Hyperglycemia, hyperinsulinemia, increase in cytokines (TNF-α and IL-1β) and carcinoembryonic antigen and presence of proliferating cells was seen in disease control animals which was prevented by sodium valproate treatment. Overexpression of relative HDAC2 mRNA levels was found in diseased control animals, which was reduced by sodium valproate treatment. IC₅₀ of sodium valproate was found to be 3.40 mM and 3.73 mM at 48 h and 72 h respectively on HCT-15 cell line. Sodium valproate also dose dependently prevented colony formation and cell migration.

CONCLUSION AND IMPLICATIONS

Sodium valproate can be considered for repurposing in colon cancer associated with diabetes mellitus.

Transferrin-targeted poly(butylene adipate)/terephthalate nanoparticles for targeted delivery of 5-fluorouracil in HT29 colorectal cancer cell line

The purpose of this study was to design 5-fluorouracil-loaded poly(butylene adipate)/terephthalate (Ecoflex®) nanoparticles for targeting colorectal cancer. The nanoparticles were prepared by emulsification–solvent evaporation method and optimized by a full factorial design. The effects of polymer and surfactant concentration, surfactant type, and stirrer rate were studied on the particle size, zeta potential, loading efficiency, and release efficiency of nanoparticles. For production of targeted nanoparticles, chitosan was conjugated to transferrin which was then coated on the surface of Ecoflex nanoparticles via electrostatic interactions. The conjugation of transferrin/chitosan was verified by Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) methods and quantified by ultraviolet spectroscopy assay. The cytotoxicity of 5-fluorouracil loaded in targeted and non-targeted nanoparticles was studied on human colon adenocarcinoma  cell line (HT29), Michigan Cancer Foundation-7 (MCF-7), and human umbilical vein endothelial cells using MTT (thiazolyl blue tetrazolium bromide) assay. The best results were obtained from nanoparticles prepared by 0.2% of the polymer, 2% of Tween 20, and stirrer speed of 17,500 r/min. The successful conjugation of transferrin/chitosan was confirmed by Fourier transform infrared spectrum and SDS-PAGE results and was about 80%. The targeted nanoparticles showed significantly more cytotoxic effects on HT29 cells compared to free 5-fluorouracil and non-targeted nanoparticles. Blocking transferrin receptors resulted in a significantly higher cell survival for targeted nanoparticles which confirmed receptor-mediated cellular uptake of targeted nanoparticles.

Nicotine increases survival in human colon cancer cells treated with chemotherapeutic drugs

Cigarette smoking is implicated in the development of colon cancer. Furthermore, nicotine increases cell proliferation and inhibits apoptosis through α7-nicotinic acetylcholine receptor (α7-nAChR) activation in human colon carcinoma cells. An open issue is whether nicotine interfere with colorectal cancer pharmacological treatment, by inhibiting drug-mediated apoptosis. To assess this hypothesis, we evaluated nicotine effect on Caco-2 and HCT-8 colon cancer cells, treated with 5-Fluorouracil (5-FU) and Camptothecin (CPT), chemotherapeutics commonly utilized as adjuvant treatment of colon cancer. Nicotine decreased anti-proliferative and pro-apoptotic effects exerted by chemotherapeutics on both cell lines. These effects partially reverted by exposure to α-bungarotoxin (α-BTX), an inhibitor of α7-nAChR. Nicotine addition to Caco-2 and HCT-8, treated with 5-FU or CPT, decreased the cleavage of substrate of caspase 3 and 7, poly-ADP-ribose polymerase (PARP). Moreover, P-ERK/ERK ratio was modified by nicotine addition to 5-FU and CPT treated cells in an opposite manner. However, when co-administrating PD98059, an ERK phosphorylation inhibitor, an increased apoptosis was observed. In Caco-2 and HCT-8 nicotine reverted 5-FU and CPT apoptotic effects through AKT phosphorylation, as demonstrated by apoptotic increase in presence of LY294002, an AKT phosphorylation inhibitor. Nicotine interfered with colorectal cancer pharmacological treatment in vitro by inhibiting apoptosis induced by chemotherapeutic drugs. Nicotine anti-apoptotic effects were exerted through ERK and AKT pathway activation.

Increase of cyclooxygenase-2 inhibition with celecoxib combined with 5-FU enhances tumor cell apoptosis and antitumor efficacy in a subcutaneous implantation tumor model of human colon cancer

Background

The purpose of this study was to investigate the anti-tumor effect and explore the mechanisms of celecoxib (a selective cyclooxygenase-2 inhibitor) combined with 5-fluorouracil (5-FU) on the treatment of human colorectal cancer in a BALB/C nude mouse subcutaneous xenograft model.

Methods

Effects of celecoxib combined with 5-FU on the proliferation of xenograft carcinoma induced by HT-29 were investigated. The apoptotic cells were detected by electron microscope and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay. Immunohistochemistry and Western blot were used to estimate the expression of cytochrome C, caspase-3 and caspase-9.

Results

Compared with the control group, treatment groups showed significant inhibition of tumor growth. More apoptotic cells existed after treatment with celecoxib combined with 5-FU. Cytochrome C, caspase-3 and caspase-9 were increased in treated groups, and more obviously in the drug combination group. Cyclooxygenase-2 (COX-2) were decreased after treatment with celecoxib only or combined with 5-FU. And the combined group showed a greater decrease.

Conclusions

Celecoxib combined with 5-FU could inhibit the growth of tumors in vivo by inducing apoptosis and activation of the cytochrome C dependency apoptosis signal pathway. A decrease of COX-2 and an increase of cytochrome C, caspase-3 and caspase-9 may be involved in this process.

Resistance of colon cancer to 5-fluorouracil may be overcome by combination with chloroquine, an in vivo study

Autophagy is a complex of adaptive cellular response that enhances cancer cell survival in the face of cellular stresses such as chemotherapy. Recently, chloroquine diphosphate (CQ), a widely used antimalarial drug, has been studied as a potential inhibitor of autophagy. Here, we aimed to investigate the role of CQ in potentiating the effect of 5-fluorouracil (5-FU), the chemotherapeutic agent of first choice for the treatment of colorectal cancer, in an animal model of colon cancer. The mouse colon cancer cell line colon26 was used. For the in-vivo study, colon26 cells were injected subcutaneously into BALB/c mice, which were treated with saline as a control, CQ (50 mg/kg/day), 5-FU (30 mg/kg/day), or the combination therapy (CQ plus 5-FU). The tumor volume ratio and body weight were monitored. After the sacrifice, tumor tissue protein extracts and tumor sections were prepared and subjected to immunoblotting for the analysis of autophagy-related and apoptosis-related proteins, and the terminal transferase uridyl end labeling assay. The combination of CQ resulted in the inhibition of 5-FU-induced autophagy and a significant enhancement in the 5-FU-induced inhibition of tumor growth. Furthermore, the combination treatment of CQ and 5-FU resulted in a significant increase in the ratio of apoptotic cells compared with other treatments. The expression levels of the proapoptotic proteins, namely Bad and Bax, were increased by the CQ treatment in the protein extracts from tumors. Our findings suggest that the combination therapy of CQ and 5-FU should be considered as an effective strategy for the treatment of colorectal cancer.

Dual blockade of the EGFR and COX-2 pathways: a phase II trial of cetuximab and celecoxib in patients with chemotherapy refractory metastatic colorectal cancer

OBJECTIVES

The epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) pathways play key and often complementary roles in the pathogenesis of colorectal cancer (CRC). This study explores the clinical and biological effects of combined blockade of these pathways.

METHODS

Cetuximab-naive patients with refractory CRC were treated with cetuximab (400 mg/m loading dose followed by weekly cetuximab at 250 mg/m) and celecoxib (200 mg orally twice daily). Urinary PGE-M, a stable metabolite of PGE2 that correlates with in vivo COX-2 activity, and serum TGF-α, a ligand that binds to EGFR, were measured serially to assess the biological effect of COX-2 and EGFR blockade.

RESULTS

Seventeen patients accrued in this study. Of the 13 patients evaluable for response, 2 (15.4%) had confirmed partial responses, 4 (30.8%) had stable disease, and 7 (53.8%) had progressive disease. The median progression-free survival for all evaluable patients was 55 days (95% confidence interval, 45-112; range, 10-295 d). This study was terminated early owing to lack of sufficient clinical activity. There were no statistically significant differences in serum TGF-α or urinary PGE-M between cycles in responders or nonresponders.

CONCLUSIONS

This regimen resulted in response rates similar to those published for cetuximab monotherapy in patients with recurrent CRC. Apart from a higher than expected rate of infusion reactions, no other unexpected toxicities were observed. No differences in serum TGF-α or urinary PGE-M between cycles were seen, suggesting that the appropriate targets may not have been hit.

Cyclin E and histone H3 levels are regulated by 5-fluorouracil in a DNA mismatch repair-dependent manner

Several studies indicate that the DNA mismatch repair (MMR) system may trigger cytotoxicity upon 5-fluorouracil (5-FU) recognition, but signaling pathways regulated by MMR in response to 5-FU are unknown. We hypothesize that recognition of 5-FU in DNA by MMR proteins trigger specific signaling cascades that results in slowing of the cell cycle and cell death. Whole human genome cDNA microarrays were used to examine relative signaling responses induced in MMR-proficient cells after 5-FU (5 μM) treatment for 24 hours. Analysis revealed 43 pathways differentially affected by 5-FU compared to control (P 1.4-fold) and downregulated cdc25C, cyclins B1 and B2, histone H2A, H2B, and H3 (< -1.4-fold) over control. Cell cycle analysis revealed a G1/S arrest by 5-FU that was congruent with increased cyclin E and decreased cdc25C protein expression. Importantly, with knockdown of hMLH1 and hMSH2, we observed that decreased histone H3 expression by 5-FU was dependent on hMLH1. Additionally, 5-FU treatment dramatically decreased levels of several histone H3 modifications. Our data suggest that 5-FU induces a G1/S arrest by regulating cyclin E and cdc25C expression, and MMR recognition of 5-FU in DNA may modulate cyclin E to affect the cell cycle. Furthermore, MMR recognition of 5-FU reduces histone H3 levels that could be related to DNA access by proteins and/or cell death during the G1/S phase of the cell cycle.

Celecoxib enhances the inhibitory effect of cisplatin on Tca8113 cells in human tongue squamous cell carcinoma in vivo and in vitro

BACKGROUND

Overexpression of cyclooxygenase-2 (COX-2) is associated with carcinogenesis, invasiveness, and metastasis of malignant tumors. Inhibition of COX-2 is one hot topic of research in prevention and treatment of malignant tumors. Because of the selective and specific inhibition on the activity of COX-2, the roles of celecoxib in prevention and treatment of tumors have attracted broad attention in recent years. In this study, we investigated the inhibitory effect of celecoxib combined with cisplatin on the proliferation of human tongue squamous cell carcinoma cell line Tca8113 in vivo and in vitro.

METHODS

Human tongue squamous cell carcinoma tumor cells Tca8113 and a mouse model with Tca8113 cells were used to study the growth inhibition of cisplatin enhanced by celecoxib. Drug treatment of Tca8113 in vitro and mice bearing xenografts in vivo were used. The level of COX-2 expression was detected by Western blotting. Sensitivity of cells to drug treatment was analyzed by MTT assay.

RESULTS

Treatment of Tca8113 cells with cisplatin (CDDP) had less effect on the expression of COX-2, whereas the COX-2 expression was significantly down-regulated after treatment with celecoxib alone or in combination with CDDP for 24 h. In addition, the combination of celecoxib with CDDP was also able to inhibit the Tca8113 line heterotransplanted in Balb/c nude mice.

CONCLUSIONS

Those findings indicate that a low dose of celecoxib could augment CDDP-induced growth inhibition of Tca8113 cells and its xenograft in Balb/c nude mice.

Effects of Oplopanax horridus on human colorectal cancer cells

AIM

In this study, we investigated the inhibitive effects of Oplopanax horridus extract (OhE) and its fractions (OhF1, OhF2, OhF3, OhF4 and OhF5) on the growth of human colorectal cancer cells and the possible mechanisms involved were investigated.

MATERIALS AND METHODS

The antiproliferative effects were evaluated by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) cell proliferation assay. Apoptotic effects and cell cycle distribution were analyzed by flow cytometry after staining with Annexin V/PI or PI/RNase.

RESULTS

After treatment for 48 h, OhE, OhF4 and OhF5 (10-100 microg/ml) inhibited proliferation of HCT-116, SW-480 and HT-29 cell lines, and cell growth decreased most with the treatment of OhF4. On the other hand, OhF1, OhF2 and OhF3 were not observed to have obvious suppressive effects on these cell lines at concentrations of 10-100 microg/ml. OhE, OhF4 and OhF5 (1-10 microg/ml) noticeably induced apoptosis time- and concentration-dependently compared to the control at the same time point. Treatment with OhE, OhF4 or OhF5 (1-10 microg/ml) for 24 h distinctly induced a G(2)/M-phase arrest of the cell cycle in a dose-dependent manner. The trend of increasing cyclin A and cyclin B1 were similar to the increase of G(2)/M phase cells in all treated groups.

CONCLUSION

These results showed that OhE had potential antiproliferative effects on human colorectal cancer cells, and the active components are enriched in the OhF4 and OhF5 fractions. The anticancer mechanism of OhE, OhF4 and OhF5 might be attributed to the induction of apoptosis and the regulation of cell cycle transition.

Overexpression of FADD enhances 5-fluorouracil-induced apoptosis in colorectal adenocarcinoma cells

To investigate the mechanism of enhancing apoptosis-inducing effects of 5-fluorouracil on human colorectal adenocarcinoma cells by stable transfection of extrinsic Fas-associated death domain protein (FADD) gene, both in vitro and in vivo. FADD gene of stable overexpression was determined by reverse transcription polymerase chain reaction (RT-PCR) assay and Western blotting assay. After treatment with 5-fluorouracil as an apoptotic inducer, in vitro cell growth activities were investigated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis and its rates were evaluated by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay and flow cytometry of annexin V-FITC/PI staining. To examine the combination therapeutic effect of FADD and 5-fluorouracil, tumor xenograft model was prepared for in vivo study. Compared with SW480 and SW480/neo cells, FADD mRNA and protein levels of SW480/FADD cells were higher. Chemosensitivity and apoptosis rates of SW480/FADD cells were remarkably higher than SW480 and SW480/neo cells when treated with 5-fluorouracil. In in vivo study, overexpression of FADD increased the efficacy of 5-fluorouracil-induced inhibition of tumor growth in nude mice. Stable overexpression of extrinsic FADD gene can conspicuously ameliorate apoptosis-inducing effects of 5-fluorouracil on colorectal adenocarcinoma cells, which is a novel strategy to improve chemotherapeutic effects on colorectal cancer.

Synergistic effect of 5-fluorouracil with gambogic acid on BGC-823 human gastric carcinoma

The design of novel targeted or combination therapies may improve treatment options for gastric cancer. In this study, we determined the inhibitory effects of 5-fluorouracil (5-FU) combined with gambogic acid (GA) on BGC-823 human gastric carcinoma cells in vitro and in vivo and investigated the underlying mechanisms. 5-FU combined with GA inhibited the viability of BGC-823 human gastric cells in a concentration-dependent manner. The pro-apoptotic activity of the two-drug combination was much stronger than single. Furthermore, the results showed GA could regulate the metabolic enzymes of 5-FU. GA decreased the mRNA levels of thymidine synthetase (TS) and dihydropyrimidine dehydrogenase (DPD), while increased the mRNA level of orotate phosphoribosyltransferase (OPRT). Moreover, combined treatment caused significantly growth inhibition of human tumor xenografts in vivo. Taken together, our data showed that GA attenuated 5-FU-induced apoptosis by modulating metabolic enzymes of 5-FU and the antigastric cancer effect of two drugs combination was much stronger than that of GA or 5-FU alone.

Celecoxib pre-treatment in human colorectal adenocarcinoma patients is associated with gene expression alterations suggestive of diminished cellular proliferation

Cancer cells treated with the cyclooxygenase-2 inhibitor celecoxib show growth inhibition and induced apoptosis. This study was conducted to determine if the same processes are relevant to celecoxib's effects on human colorectal adenocarcinomas treated in vivo. A cohort of 23 patients with primary colorectal adenocarcinomas was randomised to receive a 7-d course of celecoxib (400mg b.i.d.) or no drug prior to surgical resection. Gene expression profiling was performed on resected adenocarcinomas from the cohort of patients. Using fold change (>1.5) and p-value (<0.05) cut-offs, 190 genes were differentially expressed between adenocarcinomas from patients receiving celecoxib and those that did not. The celecoxib pre-treated samples showed decreased expression levels in multiple genes involved in cellular lipid and glutathione metabolism; changes associated with diminished cellular proliferation. Celecoxib pre-treatment for 7 d in vivo is associated with alterations in colorectal adenocarcinoma gene expression which are suggestive of diminished cellular proliferation.