Experimental Models Of Colon Cancer Research Articles

Expression of pro-angiogenic factors as potential biomarkers in experimental models of colon cancer.

RAS mutational status in colorectal cancer (CRC) represents a predictive biomarker of response to anti-EGFR therapy, but to date it cannot be considered an appropriate biomarker of response to anti-VEGF therapy. To elucidate the function of K-Ras in promoting angiogenesis, the effect of conditioned media from KRAS mutated and wild type colon cancer cell lines on HUVECs tubule formation ability and the correspondent production of pro-angiogenic factors have been evaluated by a specific ELISA assay. Ras-activated signaling pathways were compared by western blot analysis and RTq-PCR. In addition, VEGF, IL-8, bFGF and HIF-1α expression was determined in K-RAS silenced cells. Furthermore, we conducted an observational study in a cohort of RAS mutated metastatic CRC patients, treated with first-line bevacizumab-based regimens, evaluating VEGF-A and IL-8 plasma levels at baseline, and during treatment. K-RAS promotes VEGF production by cancer cell lines. At the transcriptional level, this is reflected to a K-RAS dependent HIF-1α over-expression. Moreover, the HIF-1α, VEGF and FGF expression inhibition in KRAS knocked cells confirmed these results. Within the clinical part, no statistically significant correlation has been found between progression-free survival (PFS) and VEGF-A/IL-8 levels, but we cannot exclude that these biomarkers could be further investigated as predictive or prognostic biomarkers in this setting. Our study confirmed the direct involvement of K-Ras in promoting angiogenesis into colon cancer cell lines.

Role of B vitamins on Oxidative Stress and Apoptotic Proteins Expression in Experimental Colon Cancer Model

BackgroundAzoxymethane is a potent carcinogenic agent commonly used to induce colon cancer and oxidative stress in rats. The endoplasmic reticulum (ER) stress response, represents an adaptive mechanism to support cellular survival in response to adverse microenvironment conditions by accumulating misfolded proteins and leading to apoptosis of cells. GRP78 has the potency of (potential to) inhibiting apoptosis by blocking BAX activity and thereby switching off intrinsic apoptotic pathway. Clinical studies continue to stress that oxidative stress (GRP78) is mediated B‐vitamins (folate and B12) deficiencies, oxidative and hyper homocysteinemia. However, it is relatively unknown how B vitamins affect oxidative stress on colon cancer tissue.ObjectiveTo study the expression of GRP78 and apoptotic proteins on azoxymethane(AOM) induced colon cancer using B vitamins and also to see any ultrastructure changes using Electron Microscopy.MethodsAzoxymethane (AOM)‐induced colon cancer model was used in Sprague‐Dawley rats were randomly divided into groups. The control group fed a basal diet with no AOM injection; the AOM‐treated group fed a basal diet with AOM intraperitoneal injections, whereas the other experimental groups received daily doses of folate or vitamin B12 supplementation in the presence or absence of AOM injection. Another 6 groups of rats were tested for the potential synergistic effects of both folate and vitamin B12 supplementation. All animals continuously fed ad‐libitumuntil 16 weeks, then all rats were sacrificed and the colon tissues were examined for the immunohistochemical and ultrastructural changes. Briefly, 2–3mm of colon tissue sections were stored in glutaraldehyde and from these semithin and ultrathin sections were cut and viewed to delineate the cellular organelles architecture in a transmission electron microscope (TEM). Paraffin blocks were cut and the expression of GRP78, Bcl2 and Bax was observed under a light microscope using Immunohistochemistry (IHC) technique.ResultsThere was over expression of GRP78 , Bcl2 and Bax proteins on IHC in colon cancer tissues treated with B vitamins however their expression was dose dependent. There were also ultrastructure changes in the cell organelles with dilation of endoplasmic reticulum and increase in the number of mitochondria. This is consistent with our earlier finding that early exposure to AOM causes morphological changes in the colonic mucosa of the assayed groups.ConclusionVitamin B12 and folate play a protective role against oxidative stress at both the cellular and protein levels and might ameliorate the metabolic stress on colon cells caused by cancer. Overexpression of GRP78 and the role of B vitamins will help in future to study the UPR components for understanding the cellular mechanisms involved in cancer progression.Support or Funding InformationSQU Institutional Fund

Immune Responses Raised in an Experimental Colon Carcinoma Model Following Oral Administration of Lactobacillus casei.

The role of dietary probiotic strains on host anti-cancer immune responses against experimental colon carcinoma was investigated. We have previously shown that Lactobacillus casei administration led to tumor growth suppression in an experimental colon cancer model. Here, we investigated the underlying immune mechanisms involved in this tumor-growth inhibitory effect. BALB/c mice received daily live lactobacilli per os prior to the establishment of a syngeneic subcutaneous CT26 tumor. Tumor volume, cytokine production, T cell differentiation and migration, as well as tumor cell apoptosis were examined to outline potential immunomodulatory effects following L. casei oral intake. Probiotic administration in mice resulted in a significant increase in interferon gamma (IFN-γ), Granzyme B and chemokine production in the tumor tissue as well as enhanced CD8+ T cell infiltration, accompanied by a suppression of tumor growth. Cytotoxic activity against cancer cells was enhanced in probiotic-fed compared to control mice, as evidenced by the elevation of apoptotic markers, such as cleaved caspase 3 and poly (ADP-ribose) polymerase 1 (PARP1), in tumor tissue. Oral administration of Lactobacillus casei induced potent Th1 immune responses and cytotoxic T cell infiltration in the tumor tissue of tumor-bearing mice, resulting in tumor growth inhibition. Thus, the microorganism may hold promise as a novel dietary immunoadjuvant in raising protective anti-cancer immune responses.

Effect of curcumin nano-micelle on of 1,2, dimethylhydrazine-induced rat colon carcinogenesis in comparison with 5FU

Objective Curcumin, a natural polyphenol that has anti-oxidative, anti-inflammatory and anti-cancer properties. Therapeutic potential of curcumin is substantially limited by the rather low water solubility, rapid metabolism and low bioavailability. Therefore it is necessary for its' suitable carriers. In the present study, it was aimed to assess of polymeric micelles of curcumin on experimental model of colon cancer in Rat. Method Pathogen-free male Sprague–Dawley rats divided into 4 groups. Animals from group A, B, C received DMH intraperitoneal injection once a week at a dose of 20 mg/kg body weight in 0.9% normal saline. Group A, as DMH control. B, C received Nano-micelle curcumin and 5-FU respectively 4 weeks before first carcinogen challenge and continued until week 30 of experimentation. After 4 weeks all animals were killed and their colon removed and investigated for morphological and immunohistochemistry studies of apoptosis and expression of Bcl2, BAX and Caspase9. Results It was observed significant morphological changes in Nano-curcumin groups compared with DMH group but for expression of apoptotic factors, although decrease in Bcl2 expression and increase in BAX and caspase9 observed in Nano-micelle group but these changes were not significant compared with DMH group (P > 0.05). Conclusion Results of this study indicate that Nano-micelle of curcumin has some preventive effect in experimental model of colon cancer in vivo but has not induced complete apoptotic effect and more studies that are complete are needed.

Chemotherapeutic Potential of Novel Selenium (Se) Analog of Histone Deacetylase (HDAC) Inhibitor, Suberoylanilide Hydroxamic Acid (SAHA) in Experimental Colorectal Cancer

Colorectal cancer (CRC), one of the leading causes of cancer related deaths worldwide is an outcome of both genetic and epigenetic changes in colonic epithelia leading to the formation of adenocarcinomas. Histone deacetylases (HDACs) through their key roles in regulation of cellular processes, are associated with the development and progression of cancer. Thus, in this regard, HDAC inhibitors have become promising therapeutic targets. These inhibitors induce cell cycle arrest, differentiation, autophagy and apoptotic cell death by inhibiting multiple signaling pathways. Suberoylanilide hydroxamic acid (SAHA), a second generation HDAC inhibitor has been approved by US‐FDA for the treatment of cutaneous T‐Cell lymphoma, however its anti‐cancerous effects against colorectal cancer is still unknown. Also, essential dietary element Selenium (Se) has been found to have an important role in CRC prevention via modulating redox sensitive molecular pathways. Therefore, the present study aimed to explore the anti‐tumorigenic role of SAHA and its Se analog namely, SelSA‐1 (25 mg/kg) in DMH induced experimental colon cancer model in Balb/c mice. The toxicity studies and pharmacokinetic characterization of SelSA‐1 exhibited better tolerance, absorption and elimination rate than SAHA. Further, histological and morphological analyses showed that SelSA‐1 has better/comparable chemotherapeutic potential compared to SAHA at lower doses than SAHA. Further, the positive redox modulatory effects of SelSA‐1 and SAHA in CRC associated oxidative stress were also noteworthy, projecting the plausible use of similar analogs as compounds of choice for cancer treatments based on their safety profiles, efficacy and specificity in terms of chemotherapeutic potential.Support or Funding InformationDepartment of Science and Technology (DST), Govt. of India, New Delhi; University Grant Commission (UGC), Govt. of India, New DelhiThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Estradiol and progesterone regulate proliferation and apoptosis in colon cancer.

Epidemiological studies describe estrogens as protectors in the development of colon cancer in postmenopausal women treated with hormone replacement therapy. However, the role of progesterone in colon cancer has been minimally studied and the results are controversial. For the above, the objective of this work was to determine the hormonal regulation exerted by natural ovarian steroids on proliferation and apoptosis in an experimental model of colon cancer in ovariectomized rats treated with 17-beta estradiol and progesterone. Sprague–Dawley rats were exposed to the carcinogen 1,2-dimethylhydrazine to induce colon tumors. Thirty days later, the rats were ovariectomized and treated with estradiol (60 μg/kg), progesterone (10 mg/kg), estradiol plus progesterone (60 μg/kg and 10 mg/kg) or vehicle. We observed no significant differences in colon cancer incidence and tumor multiplicity between the groups. Nevertheless, we observed a decrease in PCNA expression and a greater number of apoptotic index, higher expression of caspase 3, cleaved PARP and cleaved caspase 8 in tumors, confirming the activation of the extrinsic pathway of apoptosis by the combined treatment. In addition, we observed a higher expression of estrogen receptor beta in these tumors. We conclude that the action of both hormones, estradiol and progesterone, is necessary to reduce proliferation and increase apoptosis in colon tumors, probably through estrogen receptor beta activation.

Folate/Vitamin B12 Supplementation Combats Oxidative Stress-Associated Carcinogenesis in a Rat Model of Colon Cancer

Folate and vitamin B12 deficiency is associated with depletion of the major intracellular antioxidant glutathione, and oxidative stress is emerging as an etiological mechanism for colon cancer. Azoxymethane (AOM), a potent carcinogen, induces colon cancer in rats by causing pathophysiological changes and oxidative stress. We investigated the synergistic effect of folate and vitamin B12 supplementation against AOM-induced carcinogenesis and oxidative stress in rat colon. Adult male rats were distributed into four groups: 1) Basal diet only; 2) AOM injection (15 mg/kg once per week in weeks 5 and 6); 3) Folate and vitamin B12 supplemented diet; 4) Folate and B12 diet with AOM injection. After 16 weeks, rats were sacrificed, colon tissue dissected, indicators of oxidative stress were measured, and immunohistochemical and ultrastructural changes were evaluated. AOM-injected rats showed oxidative stress, evident by glutathione depletion, oxidation of cellular proteins, and DNA oxidative damage. AOM increased mucosal levels of antiapoptotic and proapoptotic proteins Bcl2 and Bax and caused ultrastructure changes in colonic cell organelles. Folate and vitamin B12 supplementation decreased the level of oxidative stress and ameliorated the cytotoxic effects of AOM. In this in vivo experimental model of colon cancer, folate and vitamin B12 supplementation combats carcinogen-induced oxidative stress.

A prospective evaluation of plasma polyphenol levels and colon cancer risk.

Polyphenols have been shown to exert biological activity in experimental models of colon cancer; however, human data linking specific polyphenols to colon cancer is limited. We assessed the relationship between pre‐diagnostic plasma polyphenols and colon cancer risk in a case–control study nested within the European Prospective Investigation into Cancer and Nutrition study. Using high pressure liquid chromatography coupled to tandem mass spectrometry, we measured concentrations of 35 polyphenols in plasma from 809 incident colon cancer cases and 809 matched controls. We used multivariable adjusted conditional logistic regression models that included established colon cancer risk factors. The false discovery rate (q values) was computed to control for multiple comparisons. All statistical tests were two‐sided. After false discovery rate correction and in continuous log2‐transformed multivariable models, equol (odds ratio [OR] per log2‐value, 0.86, 95% confidence interval [95% CI] = 0.79–0.93; q value = 0.01) and homovanillic acid (OR per log2‐value, 1.46, 95% CI = 1.16–1.84; q value = 0.02) were associated with colon cancer risk. Comparing extreme fifths, equol concentrations were inversely associated with colon cancer risk (OR = 0.61, 95% CI = 0.41–0.91, p trend = 0.003), while homovanillic acid concentrations were positively associated with colon cancer development (OR = 1.72, 95% CI = 1.17–2.53, p trend < 0.0001). No heterogeneity for these associations was observed by sex and across other colon cancer risk factors. The remaining polyphenols were not associated with colon cancer risk. Higher equol concentrations were associated with lower risk, and higher homovanillic acid concentrations were associated with greater risk of colon cancer. These findings support a potential role for specific polyphenols in colon tumorigenesis.

Abscopal effect of boron neutron capture therapy (BNCT): proof of principle in an experimental model of colon cancer.

The aim of the present study was to evaluate, for the first time, the abscopal effect of boron neutron capture therapy (BNCT). Twenty-six BDIX rats were inoculated subcutaneously with 1×106 DHD/K12/TRb syngeneic colon cancer cells in the right hind flank. Three weeks post-inoculation, the right leg of 12 rats bearing the tumor nodule was treated with BPA-BNCT (BPA-Boronophenylalanine) at the RA-3 nuclear reactor located in Buenos Aires, Argentina, at an absorbed dose of 7.5Gy to skin as the dose-limiting tissue. The remaining group of 14 tumor-bearing rats were left untreated and used as control. Two weeks post-BNCT, 1×106 DHD/K12/TRb cells were injected subcutaneously in the contralateral left hind flank of each of the 26 BDIX rats. Tumor volume in both legs was measured weekly for 7weeks to determine response to BNCT in the right leg and to assess a potential influence of BNCT in the right leg on tumor development in the left leg. Within the BNCT group, a statistically significant reduction was observed in contralateral left tumor volume in animals whose right leg tumor responded to BNCT (post-treatment/pre-treatment tumor volume<1) versus animals who failed to respond (post/pre≥1), i.e., 13±15 vs 271±128mm3. In addition, a statistically significant reduction in contralateral left leg tumor volume was observed in BNCT-responsive animals (post/pre<1) vs untreated animals, i.e., 13±15 vs 254±251mm3. The present study performed in a simple animal model provides proof of principle that the positive response of a tumor to BNCT is capable of inducing an abscopal effect.

Dietary mastic oil extracted from Pistacia lentiscus var. chia suppresses tumor growth in experimental colon cancer models

Plant-derived bioactive compounds attract considerable interest as potential chemopreventive anticancer agents. We analyzed the volatile dietary phytochemicals (terpenes) present in mastic oil extracted from the resin of Pistacia lentiscus var. chia and comparatively investigated their effects on colon carcinoma proliferation, a) in vitro against colon cancer cell lines and b) in vivo on tumor growth in mice following oral administration. Mastic oil inhibited - more effectively than its major constituents- proliferation of colon cancer cells in vitro, attenuated migration and downregulated transcriptional expression of survivin (BIRC5a). When administered orally, mastic oil inhibited the growth of colon carcinoma tumors in mice. A reduced expression of Ki-67 and survivin in tumor tissues accompanied the observed effects. Notably, only mastic oil -which is comprised of 67.7% α-pinene and 18.8% myrcene- induced a statistically significant anti-tumor effect in mice but not α-pinene, myrcene or a combination thereof. Thus, mastic oil, as a combination of terpenes, exerts growth inhibitory effects against colon carcinoma, suggesting a nutraceutical potential in the fight against colon cancer. To our knowledge, this is the first report showing that orally administered mastic oil induces tumor-suppressing effects against experimental colon cancer.

INHIBITION OF CARSINOGENESIS BY SEED AND SOYBEAN MEAL EXTRACT IN COLON OF MICE: APOPTOSIS AND DYSPLASIA

Objective: Colon cancer is a major public health problem. Soybean has demonstrated chemopreventive and anti-cancer. Here, we have investigated the effect of a standardized seed and soybean meal extract with content of lunasin, here named GE and SE. They are botanical drug substance in experimental models of colon cancer in vivo.Methods:The effect of GE and SEwere examined onthe preneoplastic lesions (aberrant crypt foci), polyps and tumours induced by the carcinogenic agentazoxymethane (AOM) (10 mg/kg) and dextran sodium sulfate (DSS) 2% as well as in a xenograft model of colon cancer in mice.Results:.GE and SE increased apoptosis (p = 0,001). GE (150 mg/kg) has the highest impact level of apoptosis (p = 0,009). GE and SE decreased dysplasia (p = 0,024). GE (200 mg/kg) has the highest impact level of dysplasia (p = 0,002) and SE (200 mg/kg) has the second impact level of dysplasia (p = 0,003).Conclusions: GE and SE inhibition of colon carsinogenesis with incrase level of apoptosis and decrease level of dysplasiaKeyword: soybean, lunasin, colon cancer, azoxymethane, dextran sodium sulfate, apoptosis, dysplasia

Apoptotic Proteins Expression in Experimental Colon Cancer Model

BackgroundColon and rectum cancers are the third commonly diagnosed cancers worldwide. Modifiable risk factors associated with these cancers are B‐vitamins (folate and B12) deficiencies, oxidative stress, and Hyperhomocysteinemia. It is relatively unknown how B viatmins affect oxidative stress and hyperhomocysteinemia‐mediated carcinogenesis in colon tissue.ObjectiveTo study the expression of antiapoptotic and proapoptotic proteins (Bcl2, Bax) on azoxymethane induced colon cancer using B vitamins and also to see any ultrastructural changes using Electron Microscopy.MethodsAzoxymethane (AOM)‐induced colon cancer model was used in Sprague‐Dawley male rats were randomly divided into groups. The control group fed a basal diet with no AOM injection; the AOM‐treated group fed a basal diet with AOM intraperitoneal injections, whereas the other experimental groups received daily doses of folate or vitamin B12 supplementation in the presence or absence of AOM injection. Another 6 groups of rats were tested for the potential synergistic effects of both folate and vitamin B12 supplementation. All animals continuously fed ad‐libitum until 16 weeks, then all rats were sacrificed and the colon tissues were examined for the immunohistochemical and ultrastructural changes. Briefly, 2–3mm of colon tissue sections were stored in glutaraldehyde and from these semithin and ultrathin sections were cut and viewed to delineate the cellular organelles architecture in a transmission electron microscope (TEM). Paraffin blocks were cut and the expression of Bcl2 and Bax was observed under a light microscope using Immunohistochemistry(IHC) technique. Rabbit polyclonal and mouse monoclonal antibodies were procured from ABCAM and Dako respectively.ResultsThere was over expression of Bcl2 and Bax proteins in colon cancer tissues treated with B vitamins however their expression was dose dependent. There were also ultra structural changes in the cell organelles with dilation of endoplasmic reticulum and increase in the number of mitochondria. This is consistent with our earlier finding that early exposure to AOM causes morphological changes in the coloni mucosa of the assayed groups.ConclusionVitamin B12 and folate play a protective role against oxidative stress at both the cellular and protein levels and might ameliorate the metabolic stress on colon cells caused by cancer.Support or Funding InformationAcknowledging Sultan Qaboos University Scholarship for my PhD Studies.

Functional Effects of Prebiotic Fructans in Colon Cancer and Calcium Metabolism in Animal Models.

Inulin-type fructans are polymers of fructose molecules and are known for their capacity to enhance absorption of calcium and magnesium, to modulate gut microbiota and energy metabolism, and to improve glycemia. We evaluated and compared the effects of Chicory inulin “Synergy 1®” and inulin from Mexican agave “Metlin®” in two experimental models of colon cancer and bone calcium metabolism in mice and rats. Inulins inhibited the development of dextran sulfate sodium-induced colitis and colon cancer in mice; these fructans reduced the concentration of tumor necrosis factor alpha and prevented the formation of intestinal polyps, villous atrophy, and lymphoid hyperplasia. On the other hand, inulin treatments significantly increased bone densitometry (femur and vertebra) in ovariectomized rats without altering the concentration of many serum biochemical parameters and urinary parameters. Histopathology results were compared between different experimental groups. There were no apparent histological changes in rats treated with inulins and a mixture of inulins-isoflavones. Our results showed that inulin-type fructans have health-promoting properties related to enhanced calcium absorption, potential anticancer properties, and anti-inflammatory effects. The use of inulin as a prebiotic can improve health and prevent development of chronic diseases such as cancer and osteoporosis.

Abstract 266: The G-quadruplex ligand EMICORON potentiates the antitumor efficacy of chemotherapy on colon cancer experimental models

Abstract Background. G-quadruplex (G4) structures, present at the telomeric ends of chromosomes and in the promoters of a wide range of genes important in cell signaling, gained interest as therapeutic targets and several small molecules able to bind and stabilize G4 structures have been developed. However, due to the poor drug-like properties and/or selectivity profile none of the G4 ligands has progressed through the drug discovery pipeline. Our group recently showed that the novel G4 ligand EMICORON exhibited a favourable pharmacological profile, was well tolerated in mice and elicited antitumor efficacy against advanced experimental models of colon cancer. Based on these results, our aim was to study the ability of EMICORON to increase the efficacy of the standard chemotherapy for human colon cancer. Matherials and Methods. We assessed the in vitro cytotoxic activity of EMICORON in combination with SN-38, 5-Fluorouracil and Oxaliplatin by clonogenic and 3D tumor-spheroid formation assay on HT29 colon cancer cells. The combination index (CI) values indicating synergism (CI 0.9 1.2) was evaluated. In vivo experiments were performed in mice bearing HT29 tumors treated with Irinotecan followed by EMICORON in one or two cycles of administration. Moreover, efficacy of the standard FOLFIRI (5-Fluorouracil, Leucovorin and Irinotecan) or FOLFOX (5-Fluorouracil, Leucovorin and Oxaliplatin) was evaluated in two different colon cancer patient-derived xenografts (PDXs). Results and conclusions. The exposure of HT29 cells to the combination of EMICORON with chemotherapeutics resulted strongly synergistic when the drugs were administered following the sequence SN-38→EMICORON, EMICORON→5-Fluoruracil or EMICORON→Oxaliplatin, while the opposite sequences were additive or slightly antagonistic. The high activity of SN-38 followed by EMICORON was confirmed in the HT29-formed spheroids. When mice bearing HT29 xenografts were treated with EMICORON or Irinotecan, a tumor weight inhibition (TWI) of 35 or 65% was observed respectively, while the treatment with Irinotecan followed by EMICORON resulted more effective with a TWI of 80%. This marked antitumor effect of the combination produced an increase in overall survival of mice of 85%. Interestingly, the administration of a second cycle of treatment produced an impressive increase of survival of mice to 114%. Then, we tested the efficacy of FOLFOX or FOLFIRI therapeutic regimens on two colon cancer PDXs and as expected these treatments were very effective in reducing the tumor mass and delaying the tumor regrowth, but the relapse of the disease was observed in all the mice. In conclusion, our results demonstrating that EMICORON is able to increase the potency of any single drug, provide a compelling argument to suggest that the integration of EMICORON in standard chemotherapeutic regimens could be a highly valuable strategy. Citation Format: Manuela Porru, Simona Artuso, Luca Pompili, Carla Caruso, Armandodoriano Bianco, Marcella Mottolese, Carla A. Amoreo, Annamaria Biroccio, Carlo Leonetti. The G-quadruplex ligand EMICORON potentiates the antitumor efficacy of chemotherapy on colon cancer experimental models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 266.

Ex-vivo model of colon cancer in normothermic conditions: Applications in nanomedicine

ABSTRACTColorectal cancer is one of the most accessible experimental models for the study of neoplasia, being widely used in experimental nanomedicine. Although in-vitro and in-vivo models are available and commonly used in this field, the experimental results cannot accurately predict the clinical efficiency of the tested nanobioconjugate. Ex-vivo models are particularly important in research, providing the most similar conditions to natural ones. Currently, there are few such models, existing ones being done under hypothermia, this resulting in modification of cellular metabolism. Taking this in account, we considered important to test an ex-vivo experimental colon cancer model, experiment conducted under normothermia, whose feasibility has been demonstrated previously by our team. In the present study, we underscored the usefulness that such an experimental model may have in nanomedicine, by demonstrating a positive gold nanoparticles accumulation in tumor cells by passive targeting, while maintaining cell viability for a sufficient period of time.

Oncostatic effects of fluoxetine in experimental colon cancer models

Colon cancer is one of the most common tumors in the human population. Recent studies have shown a reduced risk for colon cancer in patients given the antidepressant fluoxetine (FLX). The exact mechanism by which FLX might protect from colon cancer remains however controversial. Here, FLX reduced the development of different colon tumor xenografts, as well as proliferation in hypoxic tumor areas within them. FLX treatment also decreased microvessel numbers in tumors. Although FLX did not increase serum and tumor glucose levels as much as the colon chemotherapy gold standard Fluorouracil did, lactate levels were significantly augmented within tumors by FLX treatment. The gene expression of the MCT4 lactate transporter was significantly downregulated. Total protein amounts from the third and fifth mitochondrial complexes were significantly decreased by FLX in tumors. Cell culture experiments revealed that FLX reduced the mitochondrial membrane potential significantly and disabled the reactive oxygen species production of the third mitochondrial complex. Furthermore, FLX arrested hypoxic colon tumor cells in the G0/G1 phase of the cell-cycle. The expression of key cell-cycle-related checkpoint proteins was enhanced in cell culture and in vivo experiments. Therefore, we suggest FLX impairs energy generation, cell cycle progression and proliferation in tumor cells, especially under condition of hypoxia. This then leads to reduced microvessel formation and tumor shrinkage in xenograft models.

Parthenolide induces apoptosis in colitis-associated colon cancer, inhibiting NF-κB signaling.

Recently, the nuclear factor (NF)-κB inhibitor parthenolide (PT) was identified as a promising anticancer agent for the promotion of cancer cell apoptosis. Additionally, our previous study demonstrated that PT administration suppresses tumor growth in a xenograft model of colorectal cancer cells via regulation of the B-cell lymphoma-2 (Bcl-2) family. However, the role of PT in the development of colitis-associated colon cancer (CAC) is poorly understood. Therefore, the aim of the present study was to investigate the effects of PT administration on CAC using a murine model. Azoxymethane (AOM) and dextran sulfate sodium (DSS) were administered to induce experimental CAC in the following three groups of treated mice: i) AOM and DSS plus vehicle; ii) AOM, DSS and 2 mg/kg PT; and iii) AOM, DSS and 4 mg/kg PT. It was demonstrated that the histological acuteness of AOM/DSS-induced CAC was significantly reduced following the administration of PT, resulting in decreased NF-κB p65 expression levels via a blockade of phosphorylation and subsequent degradation of inhibitor of κB-α (IκBα). Furthermore, PT administration appeared to enhance the process of carcinogenesis via the downregulation of the antiapoptotic proteins Bcl-2 and Bcl-extra large, mediated by inhibition of NF-κB activation. Apoptosis and caspase-3 expression were markedly increased in the PT-treated group. These findings indicate that PT inhibits IκBα phosphorylation and NF-κB activation, resulting in the initiation of apoptosis and the eventual suppression of CAC development. The beneficial effects of PT treatment observed in the experimental CAC model indicate the potential chemopreventive and therapeutic role of PT in CAC.

Role of signal transducer and activator of transcription 6 in the development of colitis associated colorectal cancer (TUM7P.959)

Abstract STAT6 signaling pathway has important pathophysiologic implications in a variety of cell types and diseases. On cancer studies, mice lacking STAT6 display enhanced tumor immunity to both primary and metastatic mammary carcinomas. In humans, STAT6 protein has been found to be constitutively activated in several cancer types. However, the role of STAT6 in influencing the resistance or susceptibility of colon cancer cells to apoptosis and invasiveness/metastasis has not yet been validated during in vivo colitis-associated colon cancer (CAC).This study aims to identify the effects of STAT6 in tumorigenesis utilizing STAT6-KO mice in an experimental CAC model and evaluating changes in immune cell populations in the absence of this gene. CAC was induced in both STAT6-KO and WT mice by injection of 12.5 mg/kg AOM followed by three rounds of 2% DSS exposure to elicit colitis. On day 63 after CAC induction, mice were sacrificed. Colonic inflammation, proliferation and tumorigenesis were evaluated. Tumor numbers per mouse (0.8 versus 19.6; P=0.0001), and bowel weight (0.3 versus 0.6 g; P=0.05) were significantly decreased in STAT6-KO mice compared to WT mice. Furthermore, both inflammation and proliferation scores in colon from STAT6-KO mice were significantly lower than WT mice. Although additional studies are needed to clarify the mechanism(s) underlying improved anti-tumor immunity in STAT6-KO mice, these results may be a basis for an immunotherapy strategy in CAC development.

Inhibition of colon carcinogenesis by a standardized Cannabis sativa extract with high content of cannabidiol

PurposeColon cancer is a major public health problem. Cannabis-based medicines are useful adjunctive treatments in cancer patients. Here, we have investigated the effect of a standardized Cannabis sativa extract with high content of cannabidiol (CBD), here named CBD BDS, i.e. CBD botanical drug substance, on colorectal cancer cell proliferation and in experimental models of colon cancer in vivo. MethodsProliferation was evaluated in colorectal carcinoma (DLD-1 and HCT116) as well as in healthy colonic cells using the MTT assay. CBD BDS binding was evaluated by its ability to displace [3H]CP55940 from human cannabinoid CB1 and CB2 receptors. In vivo, the effect of CBD BDS was examined on the preneoplastic lesions (aberrant crypt foci), polyps and tumours induced by the carcinogenic agent azoxymethane (AOM) as well as in a xenograft model of colon cancer in mice. ResultsCBD BDS and CBD reduced cell proliferation in tumoral, but not in healthy, cells. The effect of CBD BDS was counteracted by selective CB1 and CB2 receptor antagonists. Pure CBD reduced cell proliferation in a CB1-sensitive antagonist manner only. In binding assays, CBD BDS showed greater affinity than pure CBD for both CB1 and CB2 receptors, with pure CBD having very little affinity. In vivo, CBD BDS reduced AOM-induced preneoplastic lesions and polyps as well as tumour growth in the xenograft model of colon cancer. ConclusionsCBD BDS attenuates colon carcinogenesis and inhibits colorectal cancer cell proliferation via CB1 and CB2 receptor activation. The results may have some clinical relevance for the use of Cannabis-based medicines in cancer patients.

Animal Models to Test Adjuvant Treatment: An Experimental Model of Colon Cancer

The recent failure of a clinical trial testing new adjuvant treatment administered after complete resection of localized colorectal cancer has shown the need for new animal models of this and similar pathology. However, animal models are the subject of debate for many reasons, including ethics, relevance, and cost. Here we develop an experimental model for use in testing adjuvant treatment of colon cancer. Different models of colon cancer are discussed, and limitations reported. An animal model of primary tumor resection using immune-deficient mice is proposed; treatment types which could be tested and biological information which could be obtained by use of this model are detailed; and limits of the method, including statistical limitations, are discussed and the first results of the model are reported.