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At least 973 records · Page 54Linked to original sources
PubMed1999

A specifically radiolabeled somatostatin analog with strong antitumor activity induces apoptosis and accumulates in the cytosol and the nucleus of HT29 human colon carcinoma cells.

The new heptapeptide somatostatin analog TT-232 decreases proliferation of HT-29 human colon carcinoma cells in vitro by reducing mitotic and increasing apoptotic activity. We have synthesized and characterized a specifically tritium labeled 3H-Tyr3-TT-232 (30 Ci/mmol) to investigate the effect and the fate of this antitumor peptide on human colon tumor cells. 3H-labeled TT-232 could be detected on the cell surface, on cytoplasmic membranes and also in the nucleus of HT-29 cells, 1-6 h after the administration of 0.5 and 50 microg/mL [3H]TT-232. Binding and internalization of TT-232 to human colon tumor cells at a relatively high dose provide further evidence for the existence of low-affinity somatostatin receptors in such cells, which might mediate the apoptosis-inducing effect. Our data suggest the possible use of TT-232 in the treatment of human colon tumors.

Antineoplastic Agents↗
PubMed1995

Optimizing production of human monoclonal IgG antibodies by in vitro-primed human PBMC: influence of CD56+ NK cell depletion.

Freshly isolated human peripheral blood mononuclear cells (PBMC) were immunomagnetically depleted of CD56+ cells. When these CD56- PBMC populations were cultured in the presence of autologous donor serum, polyclonal activation with IL-2 and pokeweed mitogen (PWM) generally resulted in exclusive production of IgG antibodies. Fusion with SP2/O-Ag14 mouse myeloma cells was highly efficient and yielded a great number of IgG-producing heterohybridomas. These conditions were used for in vitro immunization with viable human HT29 tumor cells. After fusion, an increase in hybridoma clones producing IgG monoclonal antibodies (MAb) with HT29 specificity showing a higher portion of MAb binding to the surface of viable HT29 cells was recorded. This immunizing efficiency was not observed with HT29 membrane protein fractions or HT29 proteins integrated into ISCOM particles. Investigations with human anti-alpha Gal antibodies showed that the IgG antibodies produced by the human/mouse heterohybridomas did not contain the mouse-specific Gal alpha 1-3Gal epitope.

Adjuvants, Immunologic↗
PubMed2000

Increased expression of the mRNA encoding the somatostatin receptor subtype five in human colorectal adenocarcinoma.

Numerous studies have suggested that the antiproliferative potency of somatostatin (SS) analogues may be an efficient tool to improve the prognosis of colorectal cancer. In order to facilitate current efforts to design potent antitumour SS analogues, we studied the distribution of human SS receptors (hsst1-5) mRNAs in a large set of tumoural and normal colonic tissues. Localisation of hsst1-5 mRNAs in normal and tumoural tissues was performed by in situ hybridisation using radioactive antisense or sense riboprobes. Semi-quantitative analysis of hsst5 mRNA was performed using a computerised image analysis system. Hsst binding sites were characterised by studying the relative potency of SS14, SS28 or SS analogues in displacing [(125)I]Tyr degrees -d-Trp(8)-SS14 bound to HT29-D4 cells. Hsst5 mRNA was by far the most expressed subtype in both normal and transformed epithelial cells as well as in the HT29-D4 cell line. An increased expression of hsst5 mRNA was found in tumours. Hsst1 mRNA was expressed preferentially as clusters in immune cells in lamina propria and in stroma close to the tumour. A low expression of hsst4, hsst3 and hsst2 was seen in normal and tumoural tissue. In HT29-D4, binding experiments with SS14 demonstrated the existence of one SS binding class (K(d)=524 nM, B(max)=1fmol/10(6 )cells). In competition binding studies, SS28 and BIM23268 (an analogue that shows preferential specificity towards hsst5) effectively inhibited binding of [(125)I]Tyr degrees -d-Trp(8)-SS14 (IC(50)=15 and 157 nM respectively), while BIM23197 (an analogue that shows preferential affinity for hsst2) was ineffective. Our results show a high expression of hsst5 mRNA in human tumoural colonic tissue, while hsst5 protein is the predominant hsst protein subtype in a tumoural colonic cell line.

Adenocarcinoma↗
PubMed2004

Antigenotoxicity of probiotics and prebiotics on faecal water-induced DNA damage in human colon adenocarcinoma cells.

Six strains of lactic acid producing bacteria (LAB) were incubated (1 x 10(8)cfu/ml) with genotoxic faecal water from a human subject. HT29 human adenocarcinoma cells were then challenged with the resultant samples and DNA damage measured using the single cell gel electrophoresis (comet) assay. The LAB strains investigated were Bifidobacterium sp. 420, Bifidobacterium Bb12, Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus bulgaricus and Enterococcus faecium. DNA damage was significantly decreased by all bacteria used with the exception of Strep. thermophilus. Bif. Bb12 and Lact. plantarum showed the greatest protective effect against DNA damage. Incubation of faecal water with different concentrations of Bif. Bb12 and Lact. plantarum revealed that the decrease in genotoxicity was related to cell density. Non-viable (heat treated) probiotic cells had no effect on faecal water genotoxicity. In a second study, HT29 cells were cultured in the presence of supernatants of incubations of probiotics with various carbohydrates including known prebiotics; the HT29 cells were then exposed to faecal water. Overall, incubations involving Lact. plantarum with the fructooligosaccharide (FOS)-based prebiotics Inulin, Raftiline, Raftilose and Actilight were the most effective in increasing the cellular resistance to faecal water genotoxicity, whereas fermentations with Elixor (a galactooligosaccharide) and Fibersol (a maltodextrin) were less effective. Substantial reductions in faecal water-induced DNA damage were also seen with supernatants from incubation of prebiotics with Bif. Bb12. The supernatant of fermentations involving Ent. faecium and Bif. sp. 420 generally had less potent effects on genotoxicity although some reductions with Raftiline and Elixor fermentations were apparent.

Adenocarcinoma↗
PubMed2001

Activation of the Fas pathway independently of Fas ligand during apoptosis induced by camptothecin in p53 mutant human colon carcinoma cells.

The present study explored the role of the cell surface receptor Fas (CD95/APO-1) in apoptosis induced by camptothecin (CPT) in the HT29 colon carcinoma cell line. CPT-induced apoptosis was associated with high molecular weight DNA fragmentation as measured by filter elution. This fragmentation was inhibited by the caspase inhibitor, z-VAD-fmk and by cycloheximide, which also prevented proteolytic activation of caspase-3 and poly(ADP-ribose)polymerase cleavage. Under such conditions, Fas, Fas ligand, Bax, and p21 expression were increased and Fas recruited the FADD adaptor. Fas expression increase was blocked by cycloheximide but not by z-VAD-fmk, consistent with caspase activation downstream from Fas. Treatment of HT29 cells with FasL or with the CH-11 agonistic anti-Fas antibody potentiated the apoptotic response of cells treated with CPT. The anti-Fas blocking antibody ZB4 and the Fas-ligand inhibitor failed to protect HT29 cells from CPT-induced apoptosis. Such a protection was obtained by transient expression of constructs encoding a dominant-negative mutant of FADD, FADD in an antisense orientation and E8 or MC159 viral proteins that inhibit Fas-induced apoptosis at the level of FADD and procaspase-8, respectively. Together, these data show that topoisomerase I-mediated DNA damage-induced apoptosis involves activation of the Fas pathway without detectable Fas-ligand requirement in CPT-treated cells.

Adaptor Proteins, Signal Transducing↗
PubMed2007

HSV-2- and HIV-1- permissive cell lines co-infected by HSV-2 and HIV-1 co-replicate HSV-2 and HIV-1 without production of HSV-2/HIV-1 pseudotype particles.

BACKGROUND: Herpes simplex virus type 2 (HSV-2) is a major cofactor of human immunodeficiency virus type 1 (HIV-1) sexual acquisition and transmission. In the present study, we investigated whether HIV-1 and HSV-2 may interact at the cellular level by forming HIV-1 hybrid virions pseudotyped with HSV-2 envelope glycoproteins, as was previously reported for HSV type 1. METHODS: We evaluated in vitro the production of HSV-2/HIV-1 pseudotypes in mononuclear CEM cells and epithelial HT29 and P4P cells. We analyzed the incorporation into the HIV-1 membrane of HSV-2 gB and gD, two major HSV-2 glycoproteins required for HSV-2 fusion with the cell membrane, in co-infected cells and in HIV-1-infected P4P cells transfected by plasmids coding for gB or gD. RESULTS: We show that HSV-2 and HIV-1 co-replicated in dually infected cells, and gB and gD were co-localized with gp160. However, HIV-1 particles, produced in HIV-1-infected cells expressing gB or gD after transfection or HSV-2 superinfection, did not incorporate either gB or gD in the viral membrane, and did not have the capacity to infect cells normally non-permissive for HIV-1, such as epithelial cells. CONCLUSION: Our results do not support the hypothesis of HSV-2/HIV-1 pseudotype formation and involvement in the synergistic genital interactions between HIV-1 and HSV-2.

Animals↗
PubMed1998

Changes in glycosaminoglycan structure and composition of the main heparan sulphate proteoglycan from human colon carcinoma cells (perlecan) during cell differentiation.

Colon carcinoma cells provide a useful model to study the biochemical processes associated with cell differentiation. Undifferentiated HT29, differentiated HT29MTX(-3) and HT29MTX(-6), and Caco2 human colon carcinoma cells have been used to study the production of proteoglycans and to characterize the glycosaminoglycan structure of the heparan sulphate chains. All the cell lines produce mainly a heparan sulphate proteoglycan that is found partly in the extracellular medium and associated to the cell membrane. The heparan sulphate proteoglycans from the media were purified by ion-exchange chromatography and subjected to structural analysis. The heparan sulphate proteoglycan from differentiated cells is larger and more homogeneous in size than the heparan sulphate proteoglycan from undifferentiated HT29 cells. No differences in protein core structure were observed when cells were labeled with [35S]methionine and the protein cores visualized by gel electrophoresis. Nevertheless, differences in glycosaminoglycan composition were found correlated with the degree of differentiation. The heparan sulphate chains from differentiated HT29MTX(-3) and HT29MTX(-6) cells have a higher sulphation degree than those from undifferentiated HT29 cells. The heparan sulphate from Caco2 cells is the most highly sulphated species. The differences are mainly attributed to O-sulphate groups. The increase in O-sulphation was more pronounced for D-glucosamine 6-O-sulphate than for L-iduronic acid 2-O-sulphate groups.

Carbohydrate Sequence↗
PubMed2004

Orexins acting at native OX(1) receptor in colon cancer and neuroblastoma cells or at recombinant OX(1) receptor suppress cell growth by inducing apoptosis.

Screening of 26 gut peptides for their ability to inhibit growth of human colon cancer HT29-D4 cells grown in 10% fetal calf serum identified orexin-A and orexin-B as anti-growth factors. Upon addition of either orexin (1 microM), suppression of cell growth was total after 24 h and >70% after 48 or 72 h, with an EC(50) of 5 nm peptide. Orexins did not alter proliferation but promoted apoptosis as demonstrated by morphological changes in cell shape, DNA fragmentation, chromatin condensation, cytochrome c release into cytosol, and activation of caspase-3 and caspase-7. The serpentine G protein-coupled orexin receptor OX(1)R but not OX(2)R was expressed in HT29-D4 cells and mediated orexin-induced Ca(2+) transients in HT29-D4 cells. The expression of OX(1)R and the pro-apoptotic effects of orexins were also indicated in other colon cancer cell lines including Caco-2, SW480, and LoVo but, most interestingly, not in normal colonic epithelial cells. The role of OX(1)R in mediating apoptosis was further demonstrated by transfecting Chinese hamster ovary cells with OX(1)R cDNA, which conferred the ability of orexins to promote apoptosis. A neuroblastoma cell line SK-N-MC, which expresses OX(1)R, also underwent growth suppression and apoptosis upon treatment with orexins. Promotion of apoptosis appears to be an intrinsic property of OX(1)R regardless of the cell type where it is expressed. In conclusion, orexins, acting at native or recombinant OX(1)R, are pro-apoptotic peptides. These findings add a new dimension to the biological activities of these neuropeptides, which may have important implications in health and disease, in particular colon cancer.

Animals↗
PubMed1999

Differentiation of human colon cancer cells changes the expression of beta-tubulin isotypes and MAPs.

The human colon adenocarcinoma HT29-D4 cell line is an interesting model for studies on epithelial cell differentiation. Undifferentiated cells are malignant proliferating cells, whereas differentiated cells act like epithelial polarized cells. In the present study, we first characterized the action of taxoids on the microtubular network of HT29-D4 cells according to the state of differentiation. Microtubular bundles were found in undifferentiated cells but not in differentiated cells, even with 500-fold higher taxoid concentrations for 96 h. This finding led us to study changes in microtubules according to the polarity status of the cell. E-MAP-115 was expressed only in differentiated cells; expression of beta-tubulin isotypes was altered in them relative to undifferentiated cells. Classes I, II, III, IVa and IVb isotypes were expressed in both phenotypes; however, differentiated epithelial cells displayed a specific increase in class III beta-tubulin. Thus, the increase in expression of this beta-tubulin isotype in differentiated cells is not restricted to neuronal cells. Moreover, these expression changes may reflect a higher stability of microtubular network in differentiated cells, which may explain the lower activity of anti-microtubule agents, independently of the mitotic process. These results indicate that the composition of microtubules should be considered as one of the criteria involved in the response of tumour cells to chemotherapy with anti-microtubule agents.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Regulation of vascular endothelial growth factor expression in human colon cancer by insulin-like growth factor-I.

We investigated the role of insulin-like growth factor (IGF)-I and IGF-binding proteins (IGFBPs) in the regulation of vascular endothelial growth factor (VEGF) expression in colon cancer cells and the mechanism by which this regulation occurs. HT29 human colon cancer cells were treated with IGF-I for various time periods. VEGF mRNA expression increased within 2 h and peaked at 24 h. SW620 colon cancer cells exhibited a peak induction of VEGF mRNA 8 h after IGF-I treatment. IGF-I induction of VEGF was confirmed at the protein level. In experiments using transient transfection of VEGF promoter-reporter constructs into HT29 cells, IGF-I increased the activity of the VEGF promoter, and pretreatment of HT29 cells with dactinomycin abrogated the induction of VEGF mRNA by IGF-I. The half-life of VEGF mRNA was not prolonged by treatment with IGF-I. Blocking the activity of IGFBP-4 did not significantly modulate the effect of IGF-I induction of VEGF mRNA in HT29 cells. Treating cells with des-(1-3)-IGF-I (an active derivative of IGF-I that does not bind to binding proteins) had effects on VEGF mRNA expression that were similar to those of IGF-I. These findings suggest that IGF-I regulates VEGF expression in human colon cancer cells by induction of transcription of the VEGF gene. IGFBPs do not significantly affect IGF-I induction of VEGF.

Colonic Neoplasms↗
PubMed1975

Immunohistology of the antigenic pattern of a continuous cell line from a human colon tumor.

The antigenic surface pattern of a continuous cell line (HT29) derived from a human primary carcinoma of the colon was studied by the immunofluorescence technique. Monovalent and polyvalent immune sera were used. The cells of this long-term culture kept the ability to synthesize the three principal colon tumor antigens: carcinoembryonic and nonspecific cross-reacting antigens, and the membrane-associated tissular autoantigen. On the HT29 cells, which still carry the original blood group of the tumor donor, no receptors for human Ig's were detected.

Antigens, Neoplasm↗
PubMed1996

Effect of Clostridium difficile toxin A on human intestinal epithelial cells: induction of interleukin 8 production and apoptosis after cell detachment.

Clostridium difficile is the aetiological agent of pseudomembranous colitis, and animal studies suggest the essential role of secreted toxin A in inducing disease. This study examined the biological responses to toxin A by human intestinal epithelial cells. Confluent monolayers of Caco2, HT29, and T84 cells and primary epithelial cells in organ cultures of human colonic biopsy specimens and after detachment with EDTA were studied. Interleukin 8 was assayed using enzyme linked immunosorbent assay (ELISA). Purified C difficile toxin A induced cell rounding and detachment of monolayers of the epithelial cell lines. Cells in detached monolayers initially remained viable while adherent to each other. Subsequently, an increasing number of apoptotic cells appeared in suspension. Exposure to toxin A for 24 hours induced interleukin 8 production in T84 and HT29 cells. Toxin A also induced epithelial cell rounding, detachment, and apoptosis in organ cultures of human colonic biopsy specimens. During culture (in medium only), EDTA detached colonic epithelial cells produced interleukin 8 and cell death occurred by apoptosis. Colonic disease by C difficile may be initiated by toxin A mediated induction of epithelial cell interleukin 8 production and apoptosis after cell detachment from the basement membrane. Studies on isolated (toxin untreated) colonic epithelial cells suggest that interleukin 8 production and apoptosis occur as a consequence of cell injury and detachment.

Apoptosis↗
PubMed2006

Visualization of astaxanthin localization in HT29 human colon adenocarcinoma cells by combined confocal resonance Raman and fluorescence microspectroscopy.

Astaxanthin, a carotenoid found in plants and seafood, exhibits antiproliferative, antioxidant and anticarcinogenic properties. We show that astaxanthin delivered with tetrahydrofuran is effectively taken up by cultured colon adenocarcinoma cells and is localized mostly in the cytoplasm as detected by confocal resonance Raman and broad-band fluorescence microspectroscopy image analysis. Cells incubated with beta-carotene at the same concentration as astaxanthin (10 microM) showed about a 50-fold lower cellular amount of beta-carotene, as detected by HPLC. No detectable Raman signal of beta-carotene was found in cells, but a weak broad-band fluorescence signal of beta-carotene was observed. beta-Carotene, like astaxanthin, was localized mostly in the cytoplasm. The heterogeneity of astaxanthin and beta-carotene cellular distribution in cells of intestinal origin suggests that the possible defense against reactive molecules by carotenoids in these cells may also be heterogeneous.

Chromatography, High Pressure Liquid↗
PubMed2026

UBE2D4 Upregulation Promotes Cuproptosis Sensitivity in Colorectal Cancer.

BACKGROUND: Cuproptosis, a copper-dependent form of regulated cell death, represents a potential therapeutic vulnerability in colorectal cancer (CRC). However, the regulatory mechanisms governing cuproptosis in CRC remain largely unknown. METHODS: UBE2D4 expression was analyzed in the TCGA-COAD cohort and validated in CRC cell lines (HCT116, HT29) and normal colon epithelial cells (FHC) by qRT-PCR and western blot. Paired CRC and adjacent normal tissues (n = 5) were also examined by western blot. UBE2D4-knockdown HT29 cells were generated by transient siRNA transfection to assess cell viability (CCK-8), migration (wound healing assay), and expression of cuproptosis-related genes (DLAT, HSP70, LIAS) under copper overload conditions (elesclomol+CuSO4). RESULTS: UBE2D4 was significantly upregulated in CRC tissues and cell lines compared to normal controls. In paired clinical samples, western blot confirmed that UBE2D4 protein expression was elevated in tumor tissues, accompanied by increased DLAT, HSP70 and LIAS. Copper overload induced typical cuproptotic mitochondrial morphology and triggered a marked upregulation of UBE2D4, DLAT, and HSP70, alongside downregulation of LIAS. UBE2D4 silencing had no effect on baseline cell viability or migration but significantly rescued cells from copper-induced cytotoxicity. Genetically, UBE2D4 knockdown specifically attenuated the copper-induced elevation of DLAT, while restoring HSP70 and LIAS to near-baseline levels. CONCLUSION: These findings identify UBE2D4 as a genetically upregulated and functionally significant gene in colorectal cancer. Its upregulation correlates with altered expression of cuproptosis-related genes, particularly DLAT, suggesting that UBE2D4 expression status may represent a genetic determinant of cuproptosis sensitivity in CRC. This study provides a genetic basis for stratifying CRC patients who might benefit from copper-based therapeutic strategies.

Humans↗
PubMed1997

Up-regulation of insulin/insulin-like growth factor-I hybrid receptors during differentiation of HT29-D4 human colonic carcinoma cells.

To assess the autocrine function of insulin-like growth factor II (IGF-II) in the balance of proliferation and differentiation in HT29-D4 human colonic cancer cells, we studied the expression of IGF-I receptors (IGF-IR) and insulin receptors (IR) in relation to the state of cell differentiation. IGF-IR and IR were expressed in both undifferentiated and enterocyte-like differentiated HT29-D4 cells. IGF-IR had two isoforms with a 97-kDa and a 102-kDa beta-subunit. In addition, HT29-D4 cells expressed hybrid receptors (HR) formed by the association of two alphabeta heterodimers from both IR and IGF-IR. HR were evidenced through 1) inhibition of IGF-I binding by the B6 anti-IR antibody and 2) immunoprecipitation with the alpha-IR3 anti-IGF-IR antibody, which revealed an additional 95-kDa IR beta-subunit that disappeared when the heterotetrameric receptor was dissociated by disulfide reduction into alphabeta heterodimers before immunoprecipitation. Like IGF-IR, HR had a high affinity for IGF-I (Kd, approximately 1.5 nM), but did not bind insulin significantly; the latter interacted with the native IR only (Kd, approximately 4 nM). In the differentiated HT29-D4 cell monolayer, all receptor species were strongly polarized (>97%) toward the basolateral membrane. Moreover, HT29-D4 cell differentiation was accompanied by an approximately 2-fold increase in the number of IR, whereas the number of IGF-I-binding sites was unaltered. However, in differentiated HT29-D4 cells, approximately 55% of the latter were involved in HR vs. approximately 20% in undifferentiated HT29-D4 cells. Thus, HT29-D4 cell differentiation is characterized by an up-regulation (approximately 3-fold) of the level of HR coupled to a down-regulation (approximately 40%) of the level of native tetrameric IGF-IR. Alterations were induced early during the cell differentiation process, i.e. 5 days postconfluence, and remained unchanged for at least 21 days. Taken together, these results suggest that the IGF-II autocrine loop in HT29-D4 cells may trigger distinct signaling pathways if it activates native IGF-IR, which predominate in undifferentiated cells, or if it activates HR, which are up-regulated in differentiated cells.

Binding, Competitive↗
PubMed2002

Lack of NQO1 induction in human tumor cells is not due to changes in the promoter region of the gene.

DT-diaphorase is a two-electron reducing enzyme that is an important detoxifying enzyme and activator of bioreductive antitumor agents. Expression of the DT-diaphorase gene, NQO1, appears to be transcriptionally regulated, and the gene is induced by a wide variety of compounds. We showed that 1,2-dithiole-3-thione can selectively increase DT-diaphorase activity in human and murine tumors, and that this enhanced the antitumor activity of bioreductive antitumor agents. However, we found that DT-diaphorase activity was not increased in some human tumor cell lines after treatment with the inducer, and this appeared to be due to a lack of increased transcription. To determine if this lack of increased transcription was due to a mutation in the promoter region of the NQO1 gene in these cells, we sequenced approximately 2000 bases of the NQO1 promoter region from non-induced cells and compared these with sequences from human HT29 colon cancer cells, which showed significant increases in NQO1 transcription, and the sequence reported for human liver cells in Genbank. Sequence analysis showed no changes in the sequences of the major transcriptional elements, XRE, CAT box, ARE, AP1 site or AP2 site, in the tumor cells compared with the Genbank sequences. The only major change was a deletion of a 20 base repeat region approximately 400 bases 5' to the XRE element in all the cells, including the HT29 cells, compared with the sequence reported in Genbank. There were also several insertions of a single base in various parts of the sequences which occurred in most, or all, of the cell lines compared with the reported sequence, and a small number of single base changes, insertions or deletions that occurred in a single cell line. However, these changes did not appear to correlate with differences in induced transcription of the NQO1 gene. These results suggest that the differences in transcription of the NQO1 gene after treatment with DT-diaphorase inducers was not due to alterations in the promoter region of the gene.

DNA Mutational Analysis↗
PubMed2000

Experimental and clinicopathologic studies on the function of the HGF receptor in human colon cancer metastasis.

The organ-specific metastasis characterizes several human cancers, including colon carcinoma, a disease that frequently involves metastases in the liver. The data on the molecular mechanisms of liver metastasis would therefore be highly useful for prognostic purposes. Although the upregulation/amplification of the hepatocyte growth factor (HGF) receptor, c-met, has been frequently observed in colon cancer metastasis, the actual functional significance of the feature in the liver metastatization is not yet known. We have used three human colon carcinoma cell lines (HT29, HT25 and WiDr), characterized by different liver metastatic potentials in SCID mice, to analyze the expression of c-met and the biological effects of HGF. We found that HGF induces scattering in in vitro liver-metastatic cell lines (HT25 and WiDr) only at doses which are non-mitogenic (1-20 ng/ml). Analysis of the c-met expression revealed that the metastatic cell lines express authentic c-met gene and protein material, unlike the non-metastatic HT29 cell line, which expresses only the c-terminal cytoplasmic domain of the c-met beta-chain. Interestingly, c-met was found to be localized in the substrate-attached peripheral membrane and partially colocalized with phosphotyrosine-proteins in the metastatic cells only when kept on fibronectin. On the other hand, we have analyzed 86 primary human colon cancers in Dukes' B (invasive but non-metastatic) and C (invasive and lymph node metastatic) stages. Western blotting of the proteins isolated from the tumor tissues and immunohistochemical control study on the paraffin samples of a third of these cases (25/86) all indicated a significant upregulation of the c-met protein in the Dukes' C tumor glands compared to the Dukes' B stages (P < 0.001 and P < 0.05, respectively). Since the two stages differ in the involvement of the regional lymph nodes but not in the invasion depth, the clinicopathological data and our experimental findings further support the notion that the c-met expression in human colon cancer can be considered as a marker of the metastatic potential due to its involvement in the generation of the motility signal.

Adenocarcinoma↗
PubMed1993

Cloning and expression of a complementary DNA encoding a high affinity human neurotensin receptor.

A human neurotensin receptor (hNTR) cDNA was cloned from the colonic adenocarcinoma cell line HT29. The cloned cDNA encodes a putative peptide of 418 amino acids with 7 transmembrane domains. The amino acid sequence of the hNTR is 84% identical to the rat NTR [Neuron, 4 (1990) 847-854]. Transfection of this cDNA into COS cells results in the expression of receptors with pharmacological properties similar to those found with HT29 cells. Northern blot analysis using the hNTR cDNA probe indicated a single transcript of 4 kb in the brain, the small intestine and blood mononuclear cells.

Amino Acid Sequence↗