Colorectal Carcinoma Cell Line HT29 Research Articles

5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin Zinc and Chloro-aluminum Phthalocyanine Disulfonate in Photodynamic Therapy of Colorectal Adenocarcinoma In Vitro.

Colorectal cancer (CRC) is one of the most widespread malignancies. One of the alternative therapeutic methods appears to be photodynamic therapy (PDT). This study investigated the efficiency of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin zinc (ZnTPPS4) and chloro-aluminum phthalocyanine disulfonate (ClAlPcS2) with two commercial photosensitive compounds 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP) and tetramethylthionine chloride (methylene blue, MB) in PDT for CRC in vitro. In addition to the study of the photodynamic effect on the viability of the colorectal carcinoma cell line HT29, cellular uptake, ROS production, and DNA damage were investigated. All photosensitizers showed good accumulation within HT29 cells, high efficiency in killing the cells, and a concentration-dependent increase in the production of ROS. PDT using ZnTPPS4 and ClAlPcS2 may be effective in the treatment of CRC, achieving a similar photocytotoxic effect at much lower concentrations compared to MB.

Design and characterization of PROTAC degraders specific to protein N-terminal methyltransferase 1

Protein N-terminal methylation catalyzed by N-terminal methyltransferase 1 (NTMT1) is an emerging methylation present in eukaryotes, playing important regulatory roles in various biological and cellular processes. Although dysregulation of NTMT1 has been linked to many diseases such as colorectal cancer, their molecular and cellular mechanisms remain elusive due to inaccessibility to an effective cellular probe. Here we report the design, synthesis, and characterization of the first-in-class NTMT1 degraders based on proteolysis-targeting chimera (PROTAC) strategy. Through a brief structure-activity relationship (SAR) study of linker length, a cell permeable degrader 1 involving a von Hippel-Lindau (VHL) E3 ligase ligand was developed and demonstrated to reduce NTMT1 protein levels effectively and selectively in time- and dose-dependent manners in colorectal carcinoma cell lines HCT116 and HT29. Degrader 1 displayed DC50 = 7.53 μM and Dmax > 90% in HCT116 (cellular IC50 > 100 μM for its parent inhibitor DC541). While degrader 1 had marginal cytotoxicity, it displayed anti-proliferative activity in 2D and 3D culture environment, resulting from cell cycle arrested at G0/G1 phase in HCT116. Label-free global proteomic analysis revealed that degrader 1 induced overexpression of calreticulin (CALR), an immunogenic cell death (ICD) signal protein that is known to elicit antitumor immune response and clinically linked to a high survival rate of patients with colorectal cancer upon its upregulation. Collectively, degrader 1 offers the first selective cellular probe for NTMT1 exploration and a new drug discovery modality for NTMT1-related oncology and diseases.

Inhibitory effects of Lactobacilli cocktail on HT-29 colon carcinoma cells growth and modulation of the Notch and Wnt/β-catenin signaling pathways

Probiotics could be considered as attractive candidates for preventing tumor growth through maintaining homeostasis. The aim of this study was to evaluate the inhibitory effect of a cocktail of five Lactobacillus species on human colorectal carcinoma cell line HT-29. The anti-proliferative and apoptotic effects of Lactobacilli cocktail were evaluated using MTT and flow cytometry tests, respectively. Quantitative real-time polymerase chain reaction (qPCR) was used to analyze the expression of several genes in the Notch (notch, hes1, msi1, and numb) and Wnt/β-catenin (CTNNB1 and CCND1) pathways, following the treatment of HT-29 cells with Lactobacilli cocktail. The treatment by Lactobacilli cocktail induced a significant anti-proliferative effect and late stage apoptosis among the cancer cells (p < 0.05). Compared to the untreated cells, Lactobacilli cocktail induced the down-regulation of notch, hes1, and msi1 genes and up-regulation of numb gene in the Notch pathway as well as the down-regulation of CTNNB1 and CCND1 genes in the Wnt/β-catenin pathway in a time-dependent manner (p < 0.05). ConclusionLactobacilli cocktail was shown to have beneficial anti-tumor effects on HT-29 cells by modulating the Notch and Wnt/β-catenin pathways; therefore, the use of Lactobacilli probiotics as nutritional supplements may prevent the incidence of colon cancer.

Tumor suppressive function of E2F-1 on PTEN-induced serrated colorectal carcinogenesis.

Many human cancers present Phosphatase and tensin homolog (PTEN) deficiency and between 20 and 30% of colorectal tumors show PTEN loss. The transcription factor, E2 promoter binding factor 1 (E2F-1), exhibits tumor promoter or suppressive functions depending on cellular type and tissue context, but its role in the progression and development of colorectal carcinogenesis was largely unknown. Here, using a tamoxifen-inducible PTEN knockout mouse model, we have demonstrated that loss of PTEN leads to the development of colorectal tumorigenesis through the serrated pathway. Next, we studied PTEN loss-driven colorectal lesions in the context of E2F-1 deficiency in vivo. Our results revealed that monoallelic and biallelic absence of E2F-1 led to an increased incidence and progression of serrated tumorigenesis induced by PTEN loss. Finally, we investigated the mechanisms by which double PTEN/E2F-1 deficiency leads to enhanced tumorigenesis. We found that colorectal tumors from PTEN/E2F-1 double knockout mice and the human colorectal carcinoma cell line HT29 with shRNA-mediated downregulation of PTEN and E2F-1 exhibit hyperactivation of the RAS-MAPK pathway, accumulation of DNA damage and resistance to apoptosis. To date, this is the first preclinical study evaluating the effect of genetic deletion of E2F-1 in colorectal malignancies driven by PTEN deficiency. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Aberrant DNA methylation of ADAMTS16 in colorectal and other epithelial cancers

BackgroundADAMs (a disintegrin and metalloproteinase) have long been associated with tumor progression. Recent findings indicate that members of the closely related ADAMTS (ADAMs with thrombospondin motifs) family are also critically involved in carcinogenesis. Gene silencing through DNA methylation at CpG loci around e.g. transcription start or enhancer sites is a major mechanism in cancer development. Here, we aimed at identifying genes of the ADAM and ADAMTS family showing altered DNA methylation in the development or colorectal cancer (CRC) and other epithelial tumors.MethodsWe investigated potential changes of DNA methylation affecting ADAM and ADAMTS genes in 117 CRC, 40 lung cancer (LC) and 15 oral squamous-cell carcinoma (SCC) samples. Tumor tissue was analyzed in comparison to adjacent non-malignant tissue of the same patients. The methylation status of 1145 CpGs in 51 ADAM and ADAMTS genes was measured with the HumanMethylation450 BeadChip Array. ADAMTS16 protein expression was analyzed in CRC samples by immunohistochemistry.ResultsIn CRC, we identified 72 CpGs in 18 genes which were significantly affected by hyper- or hypomethylation in the tumor tissue compared to the adjacent non-malignant tissue. While notable/frequent alterations in methylation patterns within ADAM genes were not observed, conspicuous changes were found in ADAMTS16 and ADAMTS2. To figure out whether these differences would be CRC specific, additional LC and SCC tissue samples were analyzed. Overall, 78 differentially methylated CpGs were found in LC and 29 in SCC. Strikingly, 8 CpGs located in the ADAMTS16 gene were commonly differentially methylated in all three cancer entities. Six CpGs in the promoter region were hypermethylated, whereas 2 CpGs in the gene body were hypomethylated indicative of gene silencing. In line with these findings, ADAMTS16 protein was strongly expressed in globlet cells and colonocytes in control tissue but not in CRC samples. Functional in vitro studies using the colorectal carcinoma cell line HT29 revealed that ADAMTS16 expression restrained tumor cell proliferation.ConclusionsWe identified ADAMTS16 as novel gene with cancer-specific promoter hypermethylation in CRC, LC and SCC patients implicating ADAMTS16 as potential biomarker for these tumors. Moreover, our results provide evidence that ADAMTS16 may have tumor suppressor properties.

Role of p38 Signaling Pathway in Pentagastrin-Regulated Cell Proliferation of Colorectal Carcinoma Cell Line HT-29

Objective: To investigate the effects and mechanisms of p38 signaling pathway in pentagastrin-regulated cell proliferation of colorectal carcinoma cell line HT-29. Methods: HT-29 cell line of colorectal carcinoma was in vitro incubated and divided into the control group, pentagastrin group, proglumide group, and pentagastrin + proglumide group. MTT reduction assay was performed to detect the proliferation status of HT-29 cell line and determine the optimal dosage of pentagastrin and proglumide. Annexin V-fluorescein isothiocyanate flow cytometry was used to detect the proliferation index (PI) and apoptosis rate (AR) of HT-29 cells. Reverse transcriptase polymerase chain reaction was performed to detect the mRNA expression of the pentagastrin receptor/cholecystokinin-B receptor (CCK-BR) and p38. The protein and phosphorylation levels of p38 were estimated by western blotting. Results: RT-PCR detection showed that CCK-BR mRNA was expressed in the HT-29 cell line. Pentagatrin improved HT-29 cell proliferation in dosage of 6.25 - 100 mg/L, and the optimal dosage of pentagastrin was 25.0 mg/L. Proglumide had no significant effect on the proliferation of HT-29 cells, but significantly inhibited the proliferation of HT-29 cells stimulated by pentagastrin when the dosage of proglumide was 8.0 - 128.0 mg/L, and the optimal dosage was 32.0 mg/L. The AR in the pentagastrin group was significantly lower than that in the control group and in the pentagastrin + proglumide group. The PI in the pentagastrin group was significantly higher than that in the control group and in the pentagastrin + proglumide group. P38 phosphorylation level in the pentagastrin group was significantly lower than that in the control group, and in the pentagastrin + proglumide group. There were no significant differences in the mRNA and protein expression of p38 in the control, pentagastrin, proglumide and pentagastrin + proglumide groups. Conclusion: Pentagastrin can improve proliferation of the CRC cell line HT-29 and inhibit apoptosis via the p38 signal transduction pathway. This mechanism may be associated with suppressed p38 protein phosphorylation level due to inhibition of proglumide, a gastrin receptor antagonist.

Positron emission tomography imaging of human colon cancer xenografts in mice with [18F]fluorothymidine after TAS-102 treatment.

TAS-102 is an orally administered anticancer agent composed of α,α,α-trifluorothymidine (FTD) and thymidine phosphorylase inhibitor (TPI). This study assessed 3'-deoxy-3'-[(18)F]fluorothymidine ([(18)F]FLT) uptake after TAS-102 administration. The human colorectal carcinoma cell lines HCT116, HT29, HCT8 and SW620 were exposed to FTD for 2h, further incubated for 0, 2 and 24h, and assayed for [(3)H]FLT uptake, nucleoside transport, thymidine kinase 1 (TK1) expression and TK1 activity. Static and 2-hdynamic [(18)F]FLT positron emission tomography (PET) was performed in mice bearing HT29 or SW620 tumours orally administered with vehicle or TAS-102. FTD decreased the viability of all cell lines, whereas increased [(3)H]FLT uptake (P<0.05). Increased nucleoside transport and/or TK1 expression were observed 24h after FTD, but not in 0-2h. Static [(18)F]FLT PET in mice bearing HT29 tumours showed accumulation of [(18)F]FLT in tumours 1h (day 1) after TAS-102. Two-hour dynamic PET in mice bearing SW620 tumours showed increased influx constant and volume of distribution of phosphorylated [(18)F]FLT on days 1 and 8 (P<0.05) after TAS-102 with decreased dephosphorylation on day 1 (P<0.001). Ex vivo studies showed that SW620 tumours after TAS-102 had higher TK1 expression than those with vehicle on days 8 and 15. TAS-102 administration induces an increase in [(18)F]FLT uptake. Mechanisms may involve decreased dephosphorylation of [(18)F]FLT phosphate early after TAS-102 administration. Increased TK1 expression and/or nucleoside transporter may be related to increased [(18)F]FLT uptake at a later time. [(18)F]FLT PET has a potential to assess the pharmacodynamics of TAS-102 in cancer patients.

Down-Regulation of miR-126 Is Associated with Colorectal Cancer Cells Proliferation, Migration and Invasion by Targeting IRS-1 via the AKT and ERK1/2 Signaling Pathways

BackgroundColorectal carcinoma (CRC) is one of the leading causes of cancer-related mortality worldwide. MicroRNAs (miRNAs, miRs) play important roles in carcinogenesis. MiR-126 has been shown to be down-regulated in CRC. In this study, we identified the potential effects of miR-126 on some important biological properties of CRC cells and clarified the regulation of insulin receptor substrate 1 (IRS-1) and its possible signaling pathway by miR-126.MethodsThe effect of miR-126 on IRS-1, AKT, and ERK1/2 expression was assessed in the CRC cell lines HT-29 and HCT-116 with a miR-126 mimic or inhibitor to increase or decrease miR-126 expression. Furthermore, the roles of miR-126 in regulation of the biological properties of CRC cells were analyzed with miR-126 mimic or inhibitor-transfected cells. The 3′-untranslated region (3′-UTR) of IRS-1 regulated by miR-126 was analyzed by using a dual-luciferase reporter assay.ResultsWe found that IRS-1 is the functional downstream target of miR-126 by directly targeting the 3′-UTR of IRS-1. Endogenous miR-126 and exogenous miR-126 mimic inhibited IRS-1 expression. Furthermore, gain-of-function or loss-of-function studies showed that over-expression of miR-126 down-regulated IRS-1, suppressed AKT and ERK1/2 activation, CRC cells proliferation, migration, invasion, and caused cell cycle arrest, but had no effect on cell apoptosis. Knockdown of miR-126 promoted these processes in HCT-116 cells and promoted AKT and ERK1/2 activation by up-regulating the expression of the IRS-1 protein.ConclusionsMiR-126 may play roles in regulation of the biological behavior of CRC cells, at least in part, by targeting IRS-1 via AKT and ERK1/2 signaling pathways.

SERPINA3K induces apoptosis in human colorectal cancer cells via activating the Fas/FasL/caspase‐8 signaling pathway

SERPINA3K, also known as kallikrein-binding protein (KBP), is a serine proteinase inhibitor with anti-inflammatory and anti-angiogenic activities. Our previous studies showed that SERPINA3K inhibited proliferation in a dose-dependent manner and induced apoptosis of endothelial cells but had no influence on SGC-7901 gastric carcinoma cells or HepG2 hepatocarcinoma cells. However, it is unknown whether SERPINA3K has a direct impact on other carcinoma cells and which mechanisms are involved. In this study, we report for the first time that SERPINA3K not only decreased cell viability but also induced apoptosis in the colorectal carcinoma cell lines SW480 and HT-29. SERPINA3K-induced apoptosis of SW480 and HT-29 was rescued by interference with Fas ligand (FasL) small hairpin RNA. Moreover, SERPINA3K increased the expression of FasL and activated caspase-8. Peroxisome proliferator-activated receptor γ (PPARγ), a transcription factor of FasL, was also upregulated by SERPINA3K in a dose-dependent manner. The upregulation effect of FasL induced by SERPINA3K was reversed after interference with PPARγ small interfering RNA. These results demonstrated that SERPINA3K-induced SW480 and HT-29 cell apoptosis was mediated by the PPARγ/Fas/FasL signaling pathway. Therefore, our study provides additional insight into the direct anti-tumor function by inducing tumor cell apoptosis of SERPINA3K in colorectal tumors.

Downregulation of ATP-Binding Cassette Subfamily C Member 4 Increases Sensitivity to Neoadjuvant Radiotherapy for Locally Advanced Rectal Carcinoma

This study was designed to verify the effect of ATP-binding cassette subfamily C member 4 on radiosensitivity of locally advanced rectal carcinoma. The expression of ATP-binding cassette subfamily C member 4 protein in 121 pretreatment tissue samples from locally advanced rectal carcinoma patients was detected by immunohistochemistry. Pathological response to radiotherapy was evaluated according to tumor regression grading by postoperative histological examinations after they received long-course preoperative neoadjuvant radiotherapy, and the association between clinicopathological data and tumor regression grading was analyzed retrospectively. For further validation, short hairpin RNA was constructed and transfected into colorectal carcinoma cell line HT29. The knockdown efficiency was confirmed at both RNA and protein levels. The altered radiosensitivity was evaluated by methylthiazolyl tetrazolium assay, colony formation assay, flow cytometry, and Hoechst 33258 staining. Univariate analysis revealed that ATP-binding cassette subfamily C member 4 expression (p < 0.001), P53 type (p = 0.069), and CEA (p = 0.100) were possibly associated with tumor regression grading, and multivariate analysis demonstrated that ATP-binding cassette subfamily C member 4 expression (p < 0.001) and P53 type (p = 0.039) were positively correlated with response to neoadjuvant radiotherapy in locally advanced rectal carcinoma patients. Lentiviral vector was successfully introduced into HT29 cells and inhibited ATP-binding cassette subfamily C member 4 expression efficiently and persistently. Downregulation of ATP-binding cassette subfamily C member 4 expression significantly enhanced inhibition of cell proliferation, decreased colony formation capacity, and increased cell apoptosis induced by irradiation, as examined by a series of experiments in vitro. In addition, radiobiological parameters calculated according to the single-hit multitarget model were also decreased significantly. Our data indicate that ATP-binding cassette subfamily C member 4 may be a useful molecular marker in predicting radiosensitivity, and a potential target in improving the response to neoadjuvant radiotherapy in locally advanced rectal carcinoma patients.

Cell–cell contacts induce STAT3 activity in colon carcinoma cells through an autocrine stimulation loop

Signal transducer and activator of transcription 3 (STAT3) is persistently activated in colorectal carcinoma (CRC) cells in the tumor context, but inactive in cultivated CRC cell lines. We approached mechanisms leading to STAT3 activation in CRC by mimicking "tumor-like" growth conditions and forcing cell-cell contacts of HT-29 CRC cells in culture. Further aims were to analyze in how far HT-29 cells growing in a tumorous manner spread STAT3 activity by secretion of soluble factors. Non-adhesive growth and aggregation of HT-29 cells were achieved by cultivation on non-coated plastic surfaces. STAT3 activity was assessed by Western blot employing a phospho-STAT3-specific antibody as well as by electrophoretic mobility shift assay (EMSA). Expression changes of STAT3 target gene mmp-1 were quantified by real-time RT-PCR, Cytokine/chemokine patterns in conditioned media were characterized by cytokine arrays. Forced aggregation and non-adhesive growth of HT-29 CRC cells resulted in enhanced tyrosine phosphorylation of STAT3 and elevated expression of matrix metalloproteinase MMP-1. Furthermore, an activity was secreted into the medium that evoked STAT3 phosphorylation in adhesively growing HT-29 cells. The degree of activity in the conditioned medium was enhanced when wild-type STAT3 was overexpressed and reduced when a dominant variant of STAT3 was expressed in HT-29 cells. A characteristic panel of chemokines appeared in STAT3-activating conditioned medium. Changing cultivation conditions of the CRC cell line HT-29 toward detachment and aggregation, thus toward the situation in tumors, induces STAT3 activity and evokes an autocrine STAT3 activation loop.

Antitumor effects of guanosine-analog phosphonates identified by molecular modelling

Aiming to address new drug targets, molecular modelling is gaining increasing importance although the prediction capability of the in silico method is still under debate. For an improved treatment of actinic keratosis and squamous cell carcinoma, inhibitors of human DNA polymerase α (pol α) are developed by docking nucleoside phosphonate diphosphates into the active site of pol α. The most promising prodrugs OxBu and OxHex were then prepared by total synthesis and tested in the squamous cancer cell line SCC25. OxBu and OxHex proved cytotoxic and antiproliferative in the nanomolar concentration range and thus exceeded activity of aphidicolin, the relevant model compound, and 5-fluorouracil, the current standard for the therapy of actinic keratosis. Interestingly, the cytotoxicity in normal human keratinocytes with OxHex was clearly less pronounced and even not detectable with OxBu. Moreover, cytotoxicity of OxBu in particular with the colorectal carcinoma cell line HT29 even surmounted cytotoxicity in SCC25, and other tumor cell lines were influenced, too, by both agents. Taken together, OxBu and OxHex may offer a new approach to cancer therapy, given the agents are sufficiently well tolerated in vivo which is to be suspected beside their chemical structure.

Programmed cell death induced by lovastatin and tocopherol in human colorectal carcinoma cell line HT29

Programmed cell death induced by lovastatin and tocopherol in human colorectal carcinoma cell line HT29

Suppression of N-Myc Downstream-Regulated Gene 2 Is Associated with Induction of Myc in Colorectal Cancer and Correlates Closely with Differentiation

NDRG2, a new member of the N-Myc downstream-regulated gene (NDRG) family, is a focus for study at present. Up to now, its expression and function in carcinoma remain to be elucidated. In this study, using a colorectal cancer tissue array and a series of 213 colorectal cancer samples, the relationship between Ndrg2 and c-MYC expression and tumor differentiation level was investigated. Immunohistochemistry showed that Ndrg2 expression was reduced and that c-Myc was increased in colorectal carcinomas. In addition, Ndrg2 protein levels increased from poorly differentiated to well-differentiated carcinomas (p=0.005). Real-time polymerase chain reaction and Western blots demonstrated quantitatively that NDRG2 mRNA and protein levels were lower in colorectal carcinomas compared to the adjacent tissue and normal tissue from the same individual (p=3x10(-8)). Also, the NDRG2 expression level in adjacent carcinoma tissue was lower than that of normal tissue. However, the expression pattern of c-MYC was the inverse (p=5x10(-8)). Finally, we induced the differentiation of the colorectal carcinoma cell lines HT29, SW480 and SW620 and found that NDRG2 expression increased and that c-MYC expression declined with increasing differentiation. These novel data show a disparity in both the mRNA and protein expression levels of Ndrg2 and c-Myc between colorectal cancers and normal tissues. Taken together, NDRG2 may play a role during the differentiation of colorectal cancer cells, and the function of NDRG2 in the development of colorectal cancer should be further investigated.

Cannabinoid receptor-independent cytotoxic effects of cannabinoids in human colorectal carcinoma cells: synergism with 5-fluorouracil

Cannabinoids (CBs) have been found to exert antiproliferative effects upon a variety of cancer cells, including colorectal carcinoma cells. However, little is known about the signalling mechanisms behind the antitumoural effect in these cells, whether the effects are shared by endogenous lipids related to endocannabinoids, or whether such effects are synergistic with treatment paradigms currently used in the clinic. The aim of this preclinical study was to investigate the effect of synthetic and endogenous CBs and their related fatty acids on the viability of human colorectal carcinoma Caco-2 cells, and to determine whether CB effects are synergistic with those seen with the pyrimidine antagonist 5-fluorouracil (5-FU). The synthetic CB HU 210, the endogenous CB anandamide, the endogenous structural analogue of anandamide, N-arachidonoyl glycine (NAGly), as well as the related polyunsaturated fatty acids arachidonic acid and eicosapentaenoic acid showed antiproliferative and cytotoxic effects in the Caco-2 cells, as measured by using [(3)H]-thymidine incorporation assay, the CyQUANT proliferation assay and calcein-AM fluorescence. HU 210 was the most potent compound examined, followed by anandamide, whereas NAGly showed equal potency and efficacy as the polyunsaturated fatty acids. Furthermore, HU 210 and 5-FU produced synergistic effects in the Caco-2 cells, but not in the human colorectal carcinoma cell lines HCT116 or HT29. The compounds examined produced cytotoxic, rather than antiproliferative effects, by a mechanism not involving CB receptors, since the CB receptor antagonists AM251 and AM630 did not attenuate the effects, nor did pertussis toxin. However, alpha-tocopherol and the nitric oxide synthase inhibitor L-NAME attenuated the CB toxicity, suggesting involvement of oxidative stress. It is concluded that the CB system may provide new targets for the development of drugs to treat colorectal cancer.

Triterpene Acids from the Leaves ofPlanchonella Duclitan(Blanco) Bakhuizan

From the methanolic extract of the leaves of Planchonella duclitan, 2α,3α,19α,23-tetrahydroxy-13,27-cyclours-11-en-28-oic acid (1), myrianthic acid (2), 2-hydroxyursolic acid (3), ursolic acid (4), pomolic acid (5), rotundic acid (6), andjacoumaric acid (7) were isolated, and their structures were elucidated on the basis of their spectroscopic analysis. Among them, compound 1 was a new cyclopropyl ursane-type triterpene acid. Additionally, compounds 4 and 7 showed significant cytotoxicity toward human colorectal carcinoma cell line HT29 and human breast carcinoma cell line MCF-7 with IC 50 values ranging from 5.8 ± 1.4 to 6.5 ± 1.9 μM.

Comparative analysis of metastatic variants from the colorectal tumor cell line HT-29

OBJECTIVE: To analyze the relationship between metastatic potential and related facters of colorectal tumor cell lines. METHODS: The variants HT-29c and HT-29d cell lines derived from the selection of HT-29 cells were injected into nude rats and the metastatic potential of the two tumor cell variants was analyzed. Expression of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) were measured with ELISA in vitro in colorectal carcinoma cell lines WiDr, HT-29 and HT-29d. Expression of carcinoembryonic antigen (CEA) and phosphoinositide 3-kinase (PI3-Kinase) were determined with immunohistochemistry, (IHC) in vitro and in vivo in WiDr, HT-29 and HT-29d cell lines. In addition, CEA expression was demonstrated with fluorescence activated cell sorter (FACS) in vitro. RESULTS: The liver metastasis rate of the variant HT-29d (with 4 cycles of selection), increased as compared with that of parental HT-29 cells and that of variant HT-29b cells (with 2 cycle of selection). The uPA concentration of variant HT-29d cell line was significantly higher than that of the non metastatic WiDr and the low metastatic HT-29 cells (P<0.05). The variant HT-29d cells produced stronger PI3-kinase expression as compared with the non-anetastatic WiDr cells and the low metastatic HT-29 cells in vivo. CONCLUSION: The selected variant cell lines can exhibit an enhanced metastatic potential. The level of uPA and PAI-1 are positively correlated with the metastatic capacity of tumor cells. The expression of PI3 kinasecorrelates with tumor development and metastasis.

Influence of cytokines, monoclonal antibodies and chemotherapeutic drugs on epithelial cell adhesion molecule (EpCAM) and LewisY antigen expression.

MoAbs against tumour-associated antigens (TAA) may be useful for the treatment of colorectal cancer. Since an increased expression of TAA may lead to enhanced antibody-dependent cellular cytotoxicity we examined whether the cytokines IL-2, IL-4, IL-6, IL-10, IL-12, interferon-alpha (IFN-alpha), IFN-gamma, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor and tumour necrosis factor-alpha can influence EpCAM and LewisY expression on the surface of the colorectal carcinoma cell lines HT29, LoVo and SW480. We found that only IFN-alpha increased significantly whereas IL-4 decreased both EpCAM and LewisY expression. IFN-gamma significantly increased LewisY expression only. When tumour cells were treated with MoAb, the LewisY-specific MoAb BR55-2 down-regulated LewisY antigen expression, whereas MoAb 17-1A, which binds to EpCAM, up-regulated this TAA after 3 days of culture. The cytokines IFN-alpha or IFN-gamma combined with MoAb 17-1A enhanced further slightly the expression of EpCAM. In additional experiments with chemotherapeutic drugs commonly used for the treatment of colorectal cancer, we found that 5-fluorouracil, mitomycin-C and oxaliplatin up-regulated EpCAM and LewisY antigen expression. Raltitrexed enhanced LewisY and down-regulated EpCAM expression, whereas CPT-11 had no influence at all. The highest expression for EpCAM on HT29 cells was achieved by the combination of IFN-alpha, 5-fluorouracil and MoAb 17-1A. Our results may be useful for defining combinations of biological and chemotherapeutic drugs for the treatment of colorectal cancer. Further trials should evaluate to what extent these combinations enhance antibody-dependent cellular cytotoxicity.

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The peripheral benzodiazepine receptor (PBR) has been implicated in growth control of various tumour models. Although colorectal cancers were found to overexpress PBR, the functional role of PBR in colorectal cancer growth has not been addressed to date. Using primary cell cultures of human colorectal cancers and the human colorectal carcinoma cell lines HT29, LS174T, and Colo320 DM we studied the involvement of PBR in the growth control and apoptosis of colorectal cancers. Both mRNA and protein expression of PBR were detected by RT-PCR and flow cytometry. Using confocal laser scanning microscopy and immunohistochemistry the PBR was localized in the mitochondria. The specific PBR ligands FGIN-1-27, PK 11195, or Ro5-4864 inhibited cell proliferation dose-dependently. FGIN-1-27 decreased the mitochondrial membrane potential, which indicates an early event in apoptosis. Furthermore, FGIN-1-27, PK 11195 or Ro5-4864 increased caspase-3 activity. In addition to their apoptosis-inducing effects, PBR ligands induced cell cycle arrest in the G1/G0-phase. Thus, our data demonstrate a functional involvement of PBR in colorectal cancer growth and qualify the PBR as a possible target for innovative therapeutic approaches in colorectal cancer. © 2001 Cancer Research Campaign http://www.bjcancer.com

Expression and interaction of different catenins in colorectal carcinoma cells

Aberrant signalling activities of beta-catenin, originally identified as a component of cell-adhesion complexes, are now considered to be an important factor in colorectal carcinogenesis. However, recently it was shown that also gamma- as well as p120 catenins have a dual role either in cell adhesion or in affecting some gene activation. Therefore, the levels and interactions of these three catenins in human colorectal carcinoma cell lines were analysed. A great heterogeneity in the expression of all catenins tested was found in colorectal carcinoma cell lines HT29 and LS174T. Detailed analysis of beta-catenin interactions was done. GST-APC fragment-fused proteins were used to absorb beta-catenin and its complexes from cell lysates. Similarly, the E-cadherin binding capacity of the residual pool of beta-catenin was analysed using the GST-ECT construct. It was found that the level of beta-catenin does not necessarily depend either on the APC or beta-catenin gene mutations and that co-precipitation of beta-, gamma-, and p120 catenins is not limited to cells that express E-cadherin.