Human Colon Tumor Cell Research Articles

Tricyclic Pyrazoles: Synthesis, Characterization, Antimicrobial, Antituberculosis, and Antitumor Activity of N,1-Diphenyl-1,4-dihydrothiochro-meno[4,3-c]pyrazole-3-carboxamide-5,5-dioxide Derivatives

Aims: A series of N,1-diphenyl-1,4-dihydrothiochromeno[4,3-c]pyrazole-3-carboxamide 5,5-dioxide derivatives (6a-m) were synthesized and evaluated for anticancer, antibacterial, and antifungal activity.Methodology: Reaction of 2,3-dihydro-4H-thiochromen-4-one 1,1-dioxide 2 with diethyl oxalate in ethanol in the presence of a base afforded the Claisen condensation product 3. Subsequent reaction of 3 with phenylhydrazine hydrochloride at reflux in ethanol afforded ethyl 1-phenyl-1,4-dihydrothiochromeno[4,3-c]pyrazole-3-carboxylate 5,5-dioxide (4). Alkaline hydrolysis of 4 furnished the corresponding 1-phenyl-1,4-dihydrothiochromeno[4,3-c]pyrazole-3-carboxylic acid 5,5-dioxide 5. The pyrazole acid 5 was converted into the corresponding acid chloride followed by treatment with an excess of the appropriate amine to give 6a-m.Results: Compound 6k showed better activity than chloroamphenicol against Klebsiella pneumoniae and Escherichia coli and equipotent to clotrimazole in inhibiting the growth of Candida albicans (MIC 3.125 µg/mL). All compounds were screened for their cytotoxic activity against two tumor cell lines, namely, human colon tumor cell line (HCT116) and human cervical cancer cell line (HeLa) using the colorimetric MTT assay. Most of the tested compounds exhibited potent antitumor activity. Particularly, compound 6k displayed the highest activity among the tested compounds with IC50 equal to 17 µM (HeLa) and 15 µM (HCT116) respectively. Among the tested compounds, 6k was found to be more active against M. tuberculosis, (H37Rv) with minimum inhibitory concentration (7.8 µM).Conclusion: The chloro- (6b and 6c), 2-aminobenzothiazole- (6l), and 4-aminoantipyrine- (6k) linkages exhibited better antimicrobial activity than their counterparts. Compound 6k was found to possess comparatively more antimicrobial, antituberculosis, and antitumor activity against the other derivatives.

Determination of Cell Death Induced by Lovastatin on Human Colon Cell Line HT29 Using the Comet Assay

Apoptosis or programmed cell death is an essential process for elimination of damaged cells. Also, induction of apoptosis is fundamental for treating cancer. Screening for agents that induce apoptosis in tumor cells help in the development of novel agents for cancer treatment. Numerous studies suggest that the exposure of tumor cells to statins can lead to cell death via two separate processes: apoptosis or necrosis. Severe fragmentation of DNA during apoptosis can be readily measured by the neutral comet assay. Migration of DNA fragments of apoptotic cells by the electrical field can produce comet-like images. The aim of this study was to determine the type of cell death induced by lovastatin on human colon tumor cells by using the neutral comet assay and to evaluate the utility of this method for detection of apoptosis. HT29 cells were grown in DMEM medium then exposed to different concentrations of lovastatin, and DNA fragmentation associated with apoptosis was detected by the neutral comet assay method. Lovastatin induced an apoptotic response in the HT29 cell line and produced a comet pattern similar to the positive control. This study showed that lovastatin can induce apoptosis in the HT29 cell line and confirmed the utility of comet assay for detection of apoptosis.

Differential effect of adenosine receptors on growth of human colon cancer HCT 116 and HT-29 cell lines

The study aimed to evaluate the impact of adenosine receptors (ARs) on human colon tumor cells (HCT 116, HT-29) growth and sensitivity to 5-Fluorouracil (5-FU) an anticancer chemotherapeutic drug. The exposure of cancer cells to a selective A3-AR agonist (IB-MECA) resulted in an increase in HT-29 cells number, whereas the number of HCT 116 cells decreased significantly. In the presence of IB-MECA (1μM) the percentage of apoptotic HT-29 cells significantly decreased, whereas the number of apoptotic and necrotic HCT 116 cells increased by 3- and 2,5-fold, respectively. The application of a selective A2A-AR agonist resulted in the increased survival of HCT 116 cells, but not HT-29 cells. The blockade of A2A-AR with ZM 241385 (0.1μM) significantly increased the cytotoxicity of 5-FU (1μM) in HCT 116 cells but not in HT-29 cells. The suppression of A3-AR with MRS 1523 (1μM) increased the sensitivity of HT-29 cells to 5-FU while response of HCT 116 cells to 5-FU decreased. The growth promoting effect of IB-MECA in HT-29 cells was associated with the decreased intracellular cAMP level, whereas IB-MECA growth inhibitory effect in HCT 116 cells was abolished by okadaic acid (2nM) indicating the involvement of protein phosphatase PP2A.

Analogues of N,1-diphenyl-4,5-dihydro-1H-[1]benzothiepino[5,4-c]pyrazole-3-carboxamide and N,1-diphenyl-4,5-dihydro-1H-[1]benzothiepino[5,4-c]pyrazole-3-carboxamide-6,6-dioxide: syntheses, characterization, antimicrobial, antituberculosis, and antitumor activity

A series of N,1-diphenyl-4,5-dihydro-1H-[1]benzothiepino[5,4-c]pyrazole-3-carboxamides (11a–m) and N,1-diphenyl-4,5-dihydro-1H-[1]benzothiepino[5,4-c]pyrazole-3-carboxamide-6,6-dioxides (12a–m) were synthesized by varying the active part (carboxamide group) of the pyrazole and were characterized by IR, 1H-NMR, 13C-NMR, mass spectral data, and elemental analyses. All compounds were evaluated for their antibacterial and antifungal activity. Compounds 11k and 12k showed higher activity than chloroamphenicol against Klebsiella pneumonia and Escherichia coli. Compounds 11b, 11c, 11l, 12b, 12c, and 12l displayed higher activity towards amikacin in inhibiting the growth of Escherichia coli (MIC 3.125 mg mL−1). Compounds 11k and 12k were equipotent to clotrimazole in inhibiting the growth of Candida albicans (MIC 3.125 mg mL−1). All compounds were screened for their cytotoxic activity against two tumor cell lines, namely the human colon tumor cell line (HCT116) and human cervical cancer cell line (HeLa). Most of the test compounds exhibited potent antitumor activity, especially compounds 11k and 12k, which displayed the highest activity among the test compounds with an IC50 equal to 18 and 12 μM for HeLa cells, and 16 and 10 μM for HCT116 cells, respectively. All the synthesized compounds showed low to moderate inhibitory activities against M. tuberculosis (MTB) H37Rv, whereas 11k and 12k were found to be more active against M. tuberculosis, with MIC values of 8.2 and 7.8 μM, compared to other analogues.

6r, a novel oxadiazole analogue of ethacrynic acid, exhibits antitumor activity both in vitro and in vivo by induction of cell apoptosis and S-phase arrest

This study investigated the in vitro and in vivo antitumor effects of 5-[2,3-Dichloro-4-(2-methylene-1-oxobutyl) phenoxymethyl]-3-methyl-1,2,4- oxadiazole (6r), a novel ethacrynic acid (EA) derivative. The in vitro effect of 6r on cell proliferation of human colon, leukemia, prostate, lung, breast, ovarian and cervical tumor cell lines was assessed using MTT assay and the in vivo effect was determined with an SW620 xenografts nude mice model. The effect of 6r on expressions of GST P1-1 and apoptosis-related proteins were measured by western blotting and the effect on cell apoptosis was analysed by Hoechst 33258 nuclear staining as well as by cell surface staining of annexin V/propidium iodide. The effect on cell cycle was assessed by flow cytometry. Results showed that 6r inhibit proliferation of a range of human cancer cells in vitro and growth of SW620 tumor xenografts in vivo. The anti-proliferative effect of 6r is associated with cell apoptosis as a result of increased ratio of cellular Bax/bcl-2 expression and subsequent cytochrome-c and caspase-3 activation. Unlike EA, 6r did not show any influence on cellular GST P1-1 expression and its anti-proliferative action was associated with cell cycle arrest in G1/S-phase. In conclusion, 6r has the potential to be developed as a chemotherapeutic agent by induction of cell apoptosis but not regulating GST P1-1.

Abstract B59: Cyclic GMP phosphodiesterase: A molecular target for cancer chemoprevention

Abstract Nonsteroidal anti-inflammatory drugs (NSAIDs) can significantly reduce the incidence and risk of death from multiple cancers, but their long-term use for chemoprevention is not recommended because of potentially fatal toxicities resulting from cyclooxygenase (COX) inhibition. However, the mechanism responsible for their tumor cell growth inhibitory activity may not require COX inhibition, which suggests that NSAID derivatives lacking COX inhibitory activity have potential for improved safety and efficacy. Cyclic guanosine monophosphate phosphodiesterase (cGMP PDE) inhibition appears to be an important mechanism based on previous studies with the NSAID, sulindac. Here we characterize a novel sulindac derivative referred to as sulindac benzylamine (SBA) that does not inhibit COX-1 or COX-2, yet potently inhibits the growth and induces the apoptosis of human colon tumor cells. This activity is closely associated with cGMP PDE inhibition given that SBA can inhibit cGMP hydrolysis in colon tumor cell lysates, increase intracellular cGMP levels, and activate cGMP-dependent protein kinase G (PKG) at concentrations that suppress tumor cell growth and induce apoptosis. The cGMP-specific PDE isozyme, PDE5 is selectively inhibited by SBA and elevated in colon tumor cells compared with normal colonocytes that display reduced sensitivity to SBA. PKG activation by SBA is associated with the reduction of nuclear β-catenin levels and inhibition of Tcf transcriptional activity in which the anti-apoptosis gene, survivin is suppressed. These events preceded apoptosis induction by SBA and appear to result from the rapid elevation of intracellular cGMP levels following cGMP PDE inhibition. Transient transfection with PDE5 siRNA reduced PDE5 protein expression in both human normal (NCM460) colonocytes and colon tumor cell lines (HT29 and HCT116), but only suppressed cGMP PDE activity in the tumor cells, likely because of low PDE5 levels and/or the presence of other cGMP degrading isozymes in normal colonocytes. In accord, PDE5 siRNA selectively suppressed growth and induced apoptosis of colon tumor cells, but not normal colonocytes. Colon tumor cells transfected with PDE5 siRNA also displayed reduced β-catenin levels and Tcf transcriptional activity as well as increased sensitivity to SBA treatment. Finally, molecular modeling studies suggest that SBA directly interferes with cGMP binding within the catalytic domain of PDE5. However, additional cGMP degrading PDE isozymes may either be responsible for or contribute to the sensitivity of tumor cells to SBA given that PDE5 selective inhibitors (e.g. sildenafil) do not effectively suppress colon tumor cell growth. These results lead us to conclude that cGMP PDE inhibition is an important molecular target for cancer chemoprevention, although further studies are necessary to identify key cGMP degrading isozymes involved in tumorigenesis. This research was supported NIH grants, NCI 1R01CA131378 and 1R01CA148817-01A1. Citation Format: Gary A. Piazza, Nan Li, Gary D. Bernard, Xi Chen, Adam B. Keeton, Yaguang Xi, Bing Zhu, Wei Zhang, Alexandra Fajardo, Veronica Ramirez, Sara Sigler, Kevin Lee, Claire Cawthon, Evrim Gurpinar, Maya A. Brownby, Heather N. Tinsely, Ashraf Abadi, William Grizzle. Cyclic GMP phosphodiesterase: A molecular target for cancer chemoprevention. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B59.

Anti‐tumor effect of SLPI on mammary but not colon tumor growth

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that was related to cancer development and metastasis dissemination on several types of tumors. However, it is not known the effect of SLPI on mammary and colon tumors. The aim of this study was to examine the effect of SLPI on mammary and colon tumor growth. The effect of SLPI was tested on in vitro cell apoptosis and in vivo tumor growth experiments. SLPI over-expressing human and murine mammary and colon tumor cells were generated by gene transfection. The administration of murine mammary tumor cells over-expressing high levels of SLPI did not develop tumors in mice. On the contrary, the administration of murine colon tumor cells over-expressing SLPI, developed faster tumors than control cells. Intratumoral, but not intraperitoneal administration of SLPI, delayed the growth of tumors and increased the survival of mammary but not colon tumor bearing mice. In vitro culture of mammary tumor cell lines treated with SLPI, and SLPI producer clones were more prone to apoptosis than control cells, mainly under serum deprivation culture conditions. Herein we demonstrated that SLPI induces the apoptosis of mammary tumor cells in vitro and decreases the mammary but not colon tumor growth in vivo. Therefore, SLPI may be a new potential therapeutic tool for certain tumors, such as mammary tumors.

A new gorgostane derivative from the Egyptian Red Sea soft coral Heteroxenia ghardaqensis

Chemical investigation of the chloroform extract of the Egyptian Red Sea soft coral, Heteroxenia ghardaqensis (Family Xeniidae), led to the isolation of three gorgostane derivatives, namely gorgosten-5(E)-3β-ol (1), gorgostan-3β,5α,6β, 11α-tetraol (sarcoaldosterol A) (2) and gorgostan-3β,5α,6β-triol-11α-acetate (3). To our knowledge, sterol 3 is reported in this article for the first time. The structure elucidation of these compounds was deduced by 1-D and 2-D NMR as well as ESIMS. Sterol 1 showed moderate activity as growth inhibitor of human colon tumour cell lines.

A Novel Sulindac Derivative that Potently Suppresses Colon Tumor Cell Growth by Inhibiting cGMP Phosphodiesterase and β-Catenin Transcriptional Activity

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely reported to inhibit tumor growth by a COX-independent mechanism, although alternative targets have not been well defined or used to develop improved drugs for cancer chemoprevention. Here, we characterize a novel sulindac derivative referred to as sulindac benzylamine (SBA) that does not inhibit COX-1 or COX-2, yet potently inhibits the growth and induces the apoptosis of human colon tumor cells. The basis for this activity appears to involve cyclic guanosine 3',5',-monophosphate phosphodiesterase (cGMP PDE) inhibition as evident by its ability to inhibit cGMP hydrolysis in colon tumor cell lysates and purified cGMP-specific PDE5, increase intracellular cGMP levels, and activate cGMP-dependent protein kinase G at concentrations that suppress tumor cell growth. PDE5 was found to be essential for colon tumor cell growth as determined by siRNA knockdown studies, elevated in colon tumor cells as compared with normal colonocytes, and associated with the tumor selectivity of SBA. SBA activation of PKG may suppress the oncogenic activity of β-catenin as evident by its ability to reduce β-catenin nuclear levels, Tcf (T-cell factor) transcriptional activity, and survivin levels. These events preceded apoptosis induction and appear to result from a rapid elevation of intracellular cGMP levels following cGMP PDE inhibition. We conclude that PDE5 and possibly other cGMP degrading isozymes can be targeted to develop safer and more efficacious NSAID derivatives for colorectal cancer chemoprevention.

Woodylides A–C, New Cytotoxic Linear Polyketides from the South China Sea Sponge Plakortis simplex

Three new polyketides, woodylides A–C (1–3), were isolated from the ethanol extract of the South China Sea sponge Plakortis simplex. The structures were elucidated by spectroscopic data (IR, 1D and 2D NMR, and HRESIMS). The absolute configurations at C-3 of 1 and 3 were determined by the modified Mosher’s method. Antifungal, cytotoxic, and PTP1B inhibitory activities of these polyketides were evaluated. Compounds 1 and 3 showed antifungal activity against fungi Cryptococcus neoformans with IC50 values of 3.67 and 10.85 µg/mL, respectively. In the cytotoxicity test, compound 1 exhibited a moderate effect against the HeLa cell line with an IC50 value of 11.2 µg/mL, and compound 3 showed cytotoxic activity against the HCT-116 human colon tumor cell line and PTP1B inhibitory activity with IC50 values of 9.4 and 4.7 µg/mL, respectively.

Abstract 2877: Perifosine alone and in combination with antimetabolites interferes with NF-kB pathway activation in colon cancer cell lines

Abstract Background: Perifosine, a novel, first-in-class, oral Akt inhibitor, in combination with the antimetabolite Capecitabine is currently in Phase III clinical trials for the treatment of refractory advanced colorectal cancer. We have shown previously that Perifosine in combination with antimetabolites displayed synergistic cytotoxicity and apoptosis in colon cancer and other cell lines [1]. Constitutive NF-kB activation is frequently observed in colorectal cancer and, moreover, is associated with resistance to chemotherapy [2]. Hence we analysed, wether downregulation of the NF-kB pathway contributes to Perifosine mechanism of action and to the observed synergism with antimetabolites in colon cancer cell lines. Methods: Cellular NF-kB activation in nuclear extracts was measured by the TransAm NF-kB p65 ELISA (Active Motif, USA) monitoring binding of NF-kB to its response element. To allow for higher throughput of NF-kB pathway analysis a monoclonal SW620 colon cancer cell line ectopically expressing a NF-kB response element driven reporter gene (Promega, USA) was established. Cellular cytotoxicity and apoptosis assays as well as western blotting were performed according to standard procedures. The analysis of drug combinations was conducted by CalcuSyn software (Biosoft, UK) [3]. Results: Perifosine pretreatment decreased TNFα-induced NF-kB activation in SW620 cells in both independent assay sytems with IC50 values of about 7-10 µM. This effect seems to be specific, since the results were not mimicked by cytotoxic effects of Perifosine. Some of the antimetabolites alone upregulated NF-kB activity in the reporter gene assay. In the presence of these antimetabolites Perifosine was still capable to downregulate NF-kB activity. Conclusions: In summary, these results demonstrate that downregulation of the NF-kB pathway may contribute to the mechanism of action of Perifosine. Moreover, cotreatment with Perifosine has the potential to interfere with the development of antimetabolite resistance due to NF-kB activation in colon cancer. Further experiments addressing Perifosine's mechanism of action in combination with antimetabolites in gastric cancer cell lines are ongoing.

Chemical screening of sixty-one actinomycete strains and anti-methicillin-resistant Staphylococcus aureus assays of target strains

AimTo discover actinomycete strains-producing analogs and structure-types with anti-methicillin-resistant Staphylococcus aureu (anti-MRSA) activity from a soil used as an anti-infection folk medicine. MethodsPlate method was used for the isolation of actinomycete strains with an improved Gauss medium, and chemical screening of these strains was achieved with HPLC-UV technique. The anti-MRSA activities and minimum inhibitory concentrations (MICs) of the extracts of the cultures of target strains were performed by agar diffusion and broth microdilution respectively, and their cytotoxicity was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) method using human colon tumor cell HCT-116. ResultsSixty-one actinomycete strains were isolated from the soil sample collected in Zhuzhou County, Hunan, China. Based on the analogs and structure-types in the HPLC profiles of the extracts of their cultures, three strains ZZ027, ZZ021 and ZZ044 were targeted by chemical screening. The extract (500 g) of the culture of ZZ027 and ZZ021 showed anti-MRSA activity with inhibition zones of 29–35 and 17–24 mm respectively, and their MICs were 0.625–1.25 and 2.50 mg·mL−1 respectively. The extract obtained from ZZ021 showed remarkable cytotoxicity against HCT-116 in vitro with IC50 value of 6.4 μg·mL−1, while those of ZZ027 and ZZ044 showed no cytotoxicity (IC50 values were more than 20 μg·mL−1). ConclusionFrom a soil sample used as an anti-infectious folk medicine, three strains ZZ027, ZZ021 and ZZ044 were obtained by selective isolation and chemical screening. ZZ027 and ZZ021 showed anti-MRSA activities, and ZZ021 showed remarkable cytotoxicity.

Further insights into chemical characterization through GC–MS and evaluation for anticancer potential of Dracaena draco leaf and fruit extracts

The present study reports for the first time the amino acid and fatty acid compositions and the antitumoral activity of aqueous extracts obtained from Dracaena draco L. leaf and fruit. Metabolite profiles were determined by gas chromatography-ion trap-mass spectrometry (GC–IT-MS), with several amino acids, palmitic, linolenic and stearic acid being identified in the leaf extract, and only proline, oleic and stearic acid in the fruit extract. The in vitro antiproliferative activities of the extracts were tested against human colon (Caco-2), kidney (A-498), and liver (HepG2) cancer cell lines. In addition, primary cultures of normal and cancerous renal cells derived from kidney cancer patients were treated with D. draco extracts (0–400μg/mL). Antiproliferative and cytotoxic effects were determined by the MTT assay. D. draco extracts inhibited proliferation of human colon and renal tumor cells in vitro, whereas no or weak effect was observed in HepG2 cells. Compared to the fruit extract, D. draco leaf extract exhibited stronger antiproliferative activity against all cancer cells. Our results indicate that D. draco, particularly the leaf, may be useful as a cancer chemopreventive and/or chemotherapeutic agent for colon and kidney cancers.

Tumor-Derived Chemokine CCL5 Enhances TGF-β–Mediated Killing of CD8+ T Cells in Colon Cancer by T-Regulatory Cells

Chemokine CCL5/RANTES is highly expressed in cancer where it contributes to inflammation and malignant progression. In this study, we show that CCL5 plays a critical role in immune escape in colorectal cancer. We found that higher levels of CCL5 expression in human and murine colon tumor cells correlated with higher levels of apoptosis of CD8+ T cells and infiltration of T-regulatory cells (T(reg)). In mouse cells, RNA interference (RNAi)-mediated knockdown of CCL5 delayed tumor growth in immunocompetent syngeneic hosts but had no effect on tumor growth in immunodeficient hosts. Reduced tumor growth was correlated with a reduction in T(reg) infiltration and CD8(+) T-cell apoptosis in tumors. Notably, we found that CCL5 enhanced the cytotoxicity of T(reg) against CD8(+) T cells. We also found tumor growth to be diminished in mice lacking CCR5, a CCL5 receptor, where a similar decrease in both T(reg) cell infiltration and CD8(+) T-cell apoptosis was noted. TGF-β signaling blockade diminished apoptosis of CD8(+) T cells, implicating TGF-β as an effector of CCL5 action. In support of this concept, CCL5 failed to enhance the production of TGF-β by CCR5-deficient T(reg) or to enhance their cytotoxic effects against CD8(+) T cells. CCR5 signaling blockade also diminished the in vivo suppressive capacity of T(reg) in inhibiting the antitumor responses of CD8(+) T cells, in the same way as CCL5 signaling blockade. Together, our findings establish that CCL5/CCR5 signaling recruits T(reg) to tumors and enhances their ability to kill antitumor CD8(+) T cells, thereby defining a novel mechanism of immune escape in colorectal cancer.

Interventional role of Haridra (Curcuma longaLinn) in cancer

Haridra (Curcuma longa Linn (Zingiberaceae family)) is a rhizomatous household spice and has been a widely used herb in India since ancient times. Ayurvedic pharmacodynamics of C. longa are described as follows: Rasa - tikta and katu, Guna - rukhsha and laghu, Virya - ushna, Vipak - katu and Doshaghnata - tridoshshamak. It is used as a tonic, carminative, antidiarrheal, hepatoprotective and as a purifying agent. It is also used in cancer management. Since years, haridra has been used as a hemostyptic agent. However, the oncopreventive aspect of haridra has drawn the scientists towards it. Use of haridra in medoja arbuda is documented in Sushrut Samhita. Recently, it has been found that chronic inflammation has played a role in cancer formation. The kapha and vata shamaka property is responsible for the shothghna activity of haridra. Several studies have also proved the anti-inflammatory condition of haridra. The essential oil, containing ar-turmerone, as a major component has been shown to possess anti-inflammatory effect of haridra. Experimental studies 'in vitro and in vivo' in diverse models have also proved the anti-tumor activity of haridra. Curcumin,the chief ingredient, of it is mainly responsible for anticancer property. However other constituents like Turmerone and polysacchrides also play a major role in anti cancer activity. The free radical scavenging activity as well as inhibition of lipid peroxidation by curcumin has been reported by Kuttan et al. The mechanisms underlying the anticancer potential of curcumin are complex. Many reports in literature mention about that work carried out regarding the suppression of proliferation of cells of different tumors. They include the down regulation of transcription factors, inhibiting COX2, LOX, inducible nitric oxide synthase, matrix metalloproteinases 9, cell adhesion molecules along with TNF-α. Curcumin inhibits TNF-α-induced AKT activation whereby levels required for NFkβ gene expression are suppressed. Curcumin suppresses the tumor angiogenesis resulting in regression in the tumor metastatic growth. Goel et al. have shown the inhibition of expression of COX2 in human colon tumor cell line (Vaidya et al.). Kuttan et al. showed that the ethanol extract of turmeric as well as the ointment of curcumin produced remarkable symptomatic relief in 62 patients with external cancerous lesions. Scientists at institute of cytology and preventive oncology (ICPO) based in Noida, UP, have found that curcumin protects body from HPV that is one of the primary causes of cervical cancer. Bhide et al. showed the therapeutic effect of turmeric oil and turmeric oleoresin on oral submucous fibrosis (SMF) patients. At MRC KHS, a cervical cancer prevention study was approved by an independent ethics committee. The primary objective was to see whether administration of oral turmeric oil for a period of 12 weeks, resulted in the arrest or regression of the premalignant condition, LGSIL, i.e. low grade squamous intraepithelial lesion as detected by Pap smears during the therapy period. It was observed that the lesion in Pap smears was arrested in 3/19 cases and regressed in 16/19 cases (Joshi et al, Asian Pac J Cancer Prev 2011). Experimental data suggest that curcumin acts at each stage of promotion, progression, and metastasis of cancer. Haridra which has anticancer potential ,can be considered as complementary medicine for cancer treatment as well as prevention.

Pretargeted immuno-PET of CEA-expressing intraperitoneal human colonic tumor xenografts: a new sensitive detection method

BackgroundIn this study, pretargeted immuno-positron-emission tomography [PET] with a bispecific monoclonal anti-carcinoembryonic antigen [CEA] (CEACAM5) × anti-hapten antibody (bispecific monoclonal antibody [bsmAb]) and a small (1.5 kD) peptide labeled with 68Ga was compared to fludeoxyglucose [18F-FDG]-PET for detecting intraperitoneal [i.p.] CEA-expressing human colonic tumor xenografts in nude mice.MethodsTwo groups of female BALB/c nude mice were inoculated with LS174T human colonic tumor cells i.p. One group received 5 MBq 18F-FDG, and the other received intravenous injections of the bsmAb, followed 16 h later with 5 MBq of 68Ga-labeled peptide. One hour after the radiolabeled peptide or FDG was given, micro-PET/computed tomography images were acquired. Thereafter, the uptake of the 68Ga or 18F in dissected tissue was determined.ResultsWithin 1 h, high uptake of the 68Ga-labeled peptide in the tumor lesions (23.4 ± 7.2% ID/g) and low background activity levels were observed (e.g., tumor-to-intestine ratio, 58 ± 22). This resulted in a clear visualization of all intra-abdominal tumor lesions ≥ 10 μL and even some tumors as small as 5 μL (2 mm diameter). 18F-FDG efficiently localized in the tumors (8.7 ± 3.1% ID/g) but also showed physiological uptake in various normal tissues (e.g., tumor-to-intestine ratio, 3.9 ± 1.1).ConclusionsPretargeted immuno-PET with bsmAb and a 68Ga-labeled peptide could be a very sensitive imaging method for imaging colonic cancer, disclosing occult lesions.

STAT3 Is Necessary for Proliferation and Survival in Colon Cancer–Initiating Cells

STAT3 is constitutively activated in colon cancer but its contributions in cancer-initiating cells have not been explored. In this study, we characterized STAT3 in aldehyde dehydrogenase (ALDH)-positive (ALDH(+)) and CD133-positive (CD133(+)) subpopulations of human colon tumor cells that exhibited more potent tumor-initiating ability than ALDH(-)/CD133(-) cells in tumor xenograft assays in mice. We found that ALDH(+)/CD133(+) cells expressed higher levels of the active phosphorylated form of STAT3 than either ALDH(-)/CD133(-) or unfractionated colon cancer cells. STAT3 inhibition by RNA interference-mediated knockdown or small-molecule inhibitors LLL12 or Stattic blocked downstream target gene expression, cell viability, and tumorsphere-forming capacity in cancer-initiating cells. Similarly, treatment of mouse tumor xenografts with STAT3 short hairpin RNA (shRNA), interleukin 6 shRNA, or LLL12 inhibited tumor growth. Our results establish that STAT3 is constitutively activated in colon cancer-initiating cells and that these cells are sensitive to STAT3 inhibition. These findings establish a powerful rationale to develop STAT3 inhibitory strategies for treating advanced colorectal cancers.

Abstract B46: Dietary acrylamide differentially modulates azoxymethane-induced F344 rat colon tumor formation and ectopic growth of human colon tumor cells in nude (nu/nu) mice

Abstract Acrylamide, a known rodent and a possible human carcinogen is ubiquitously formed in foods at high temperature. We earlier reported that dietary acrylamide at doses known to cause rodent tumors, did not increase the formation of azoxymethane (AOM)-induced colon aberrant crypt foci (ACF), putative precancerous lesions. On the contrary, we observed a significant decrease in ACF in rats receiving acrylamide at 10 and 50 mg/kg diet and a trend to increase ACF at the lowest dose (5mg acrylamide/kg diet) tested. In this study using two rodent models, we assessed if dietary acrylamide, at levels reflecting those in popular human foods, modulated colon tumor formation and progression. In Experiment-1, 4 groups of weanling male F344 rats received AIN-93G diets with acrylamide at 0.5, 1.0 or 2.0 mg/kg diet or without (0 mg/kg diet, control). After two weeks, rats in each diet group received either two weekly s.c. injections of AOM or saline. All rats were on the experimental diets ad libitum for 20 weeks post AOM/saline injections after which they were killed and their colons assessed for tumors. In Experiment-2, athymic nude (nu/nu) mice were s.c. injected with HT-29 human colon adenocarcinoma cells and tumors were allowed to grow for 3 weeks after which they received one of the 4 experimental diets; tumor growth was monitored bi-weekly and mice were killed 4 weeks after. None of the saline-injected rats had tumors in their colon. 23 rats that received acrylamide had blood in their stool at 19 weeks post-AOM injections, and hence the study was stopped in a timely manner at 20 weeks post-AOM injections. The colon tumor incidence was 54.2% in the control group and 66.67% in the highest acrylamide-treated group (2 mg/kg diet). Tumor multiplicity was similar across all diet groups. However, tumor size and burden were higher in the group that received 2 mg/kg acrylamide by comparison to the control. These results suggest acrylamide by itself is not a “carcinogen” at upper exposure levels commonly seen in popular foods, but acts as a “co-carcinogen” at the highest tested dose by exacerbating the risk of developing colon tumors by a known colon-specific carcinogen AOM. The nude mice study indicated no differences in ectopic human colon tumor growth between acrylamide-treated and control mice suggesting that acrylamide at the levels tested does not aid in the progression of established human tumors in this experimental model. Our data provides characterization of acrylamide as a possible colon cancer promoter in association with a known and possibly other environmental tumor initiators/promoters. This additional information will be useful in defining the health risks of acrylamide when exposed through the diet, and will assist regulators in developing a better understanding of the relevance to humans. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B46.

Synthesis and antitumor activity of novel pyrazolo[1,5-a]pyrimidine derivatives

A novel series of pyrazolo[1,5- a ]pyrimidine-3-carbonitriles substituted with 7-amino, 7-substituted amino and 5-substituted amino groups was synthesized. Some of the newly synthesized compounds were tested in vitro on human colon tumor cell line (HCT116). Compound 14a displayed the highest activity among the tested compounds with IC 50 that equals to 0.0020 μM.

Pregnane X receptor activation induces FGF19-dependent tumor aggressiveness in humans and mice

The nuclear receptor pregnane X receptor (PXR) is activated by a range of xenochemicals, including chemotherapeutic drugs, and has been suggested to play a role in the development of tumor cell resistance to anticancer drugs. PXR also has been implicated as a regulator of the growth and apoptosis of colon tumors. Here, we have used a xenograft model of colon cancer to define a molecular mechanism that might underlie PXR-driven colon tumor growth and malignancy. Activation of PXR was found to be sufficient to enhance the neoplastic characteristics, including cell growth, invasion, and metastasis, of both human colon tumor cell lines and primary human colon cancer tissue xenografted into immunodeficient mice. Furthermore, we were able to show that this PXR-mediated phenotype required FGF19 signaling. PXR bound to the FGF19 promoter in both human colon tumor cells and "normal" intestinal crypt cells. However, while both cell types proliferated in response to PXR ligands, the FGF19 promoter was activated by PXR only in cancer cells. Taken together, these data indicate that colon cancer growth in the presence of a specific PXR ligand results from tumor-specific induction of FGF19. These observations may lead to improved therapeutic regimens for colon carcinomas.