Detection of EpCAM positive and negative circulating tumor cells in metastatic breast cancer patients.

BACKGROUND: Immunomagnetic EpCAM based methods are used to enrich circulating tumor cells (CTCs) in metastatic breast cancer (mBC) patients. EpCAM negative CTCs may be missed. We addressed the question of the reliability of an EpCAM dependent assay to enrich CTCs. METHODS: To elucidate this issue, our study has been designed to assess two different CTC enrichment technologies (i) in EpCAM positive (+) and EpCAM negative cell lines and (ii) in mBC patients in dependency on their respective EpCAM expression. These two technologies encompass one anti-EpCAM immunomagnetic enrichment technology, MACS HEA MicroBeads(®) (MACS), and one EpCAM independent density centrifugation method, OncoQuick(®) plus (OQ+). Furthermore, the coherence between EpCAM expression in the primary tumor tissue of mBC patients and the CTC detection rates in the corresponding patients is analyzed. RESULTS: (i) MACS recovered significantly more EpCAM (+) than EpCAM (-) tumor cells (p < 0.001) in spiked blood samples. With OQ+ no significantly different recovery rates between EpCAM (+) and EpCAM (-) tumor cells (p = 0.796) were detected. (ii) In mBC patients MACS yielded a significantly higher (p = 0.024) detection rate of EpCAM (+) CTCs. No statistically significant difference (p = 0.070) was found concerning the EpCAM status-based detection rate of CTCs by OQ+. (iii) CTC detection rates are independent of the primary tumors' EpCAM expression. CONCLUSIONS: EpCAM (-) CTCs can not be detected by immunomagnetic EpCAM dependent enrichment methods. EpCAM independent enrichment technologies seem to be superior to detect the entire CTC population. Evaluation of CTCs as prognostic marker should compromise EpCAM (+) and (-) subpopulations.

The high affinity IgE receptor Fc epsilonRI is expressed by human intestinal epithelial cells.

BACKGROUND: IgE antibodies play a paramount role in the pathogenesis of various intestinal disorders. To gain insights in IgE-mediated pathophysiology of the gut, we investigated the expression of the high affinity IgE receptor Fc epsilonRI in human intestinal epithelium. METHODOLOGY/PRINCIPAL FINDINGS: Fc epsilonRI alpha-chain, as detected by immunohistochemistry, was positive in epithelial cells for eight of eleven (8/11) specimens from colon cancer patients and 5/11 patients with inflammation of the enteric mucosa. The Fc epsilonRIalpha positive epithelial cells co-expressed Fc epsilonRIgamma, whereas with one exception, none of the samples was positive for the beta-chain in the epithelial layer. The functionality of Fc epsilonRI was confirmed in situ by human IgE binding. In experiments with human intestinal tumor cell lines, subconfluent Caco-2/TC7 and HCT-8 cells were found to express the alpha- and gamma-chains of Fc epsilonRI and to bind IgE, whereas confluent cells were negative for gamma-chains. CONCLUSIONS/SIGNIFICANCE: Our data provide the first evidence that the components of a functional Fc epsilonRI are in vitro expressed by the human intestinal epithelial cells depending on differentiation and, more importantly, in situ in epithelia of patients with colon cancer or gastrointestinal inflammations. Thus, a contribution of Fc epsilonRI either to immunosurveillance or pathophysiology of the intestinal epithelium is suggested.

The candidate oncogene CYP24A1: A potential biomarker for colorectal tumorigenesis.

The main autocrine/paracrine role of the active metabolite of vitamin D(3), 1alpha,25-dihydroxyvitamin D(3) (1,25-D(3)), is inhibition of cell growth and induction of cell differentiation and/or apoptosis. Synthesis and degradation of the secosteroid occurs not only in the kidney but also in normal tissue or malignant extrarenal tissues such as the colon. Because 25-hydroxyvitamin D(3) 24-hydroxylase (CYP24A1) is considered to be the main enzyme determining the biological half-life of 1,25-D(3), we have examined expression of the CYP24A1 mRNA (by real-time RT-PCR) and protein (by immunohistochemistry) in normal human colon mucosa, colorectal adenomas, and adenocarcinomas in 111 patients. Although 76% of the normal and benign colonic tissue was either completely devoid of or expressed very low levels of CYP24A1, in the majority of the adenocarcinomas (69%), the enzyme was present at high concentrations. A parallel increased expression of the proliferation marker Ki-67 in the same samples suggests that overexpression of CYP24A1 reduced local 1,25-D(3) availability, decreasing its antiproliferative effect.

Chemoprevention of colorectal neoplasia by estrogen: potential role of vitamin D activity.

Postmenopausal hormone replacement therapy lowers colon cancer incidence. In humans, the mechanism is unknown, but animal models suggest that it may involve activation of the vitamin D receptor (VDR) pathway. The aims of our study were to determine whether estrogen intervention affects global gene expression in rectal mucosal biopsies and whether vitamin D-related genes are affected. Estradiol was given to raise serum estradiol to premenopausal levels in 10 postmenopausal women under close nutritional control. Primary end points were expression of VDR, CYP24A1, CYP27B1, and E-cadherin in rectal mucosa by reverse transcription-PCR and examining response to estradiol by genome-wide arrays. Responses in gene expression in rectal biopsies to estrogen were determined in each subject individually and compared with a human estrogen response gene array database and a custom array in vitro-generated database. Cluster analysis showed that subjects maintained their overall gene expression profile and that interindividual differences were greater than intraindividual differences after intervention. Eight of 10 subjects showed significant enrichment in estrogen-responsive genes. Gene array group analysis showed activation of the VDR pathway and down-regulation of inflammatory and immune signaling pathways. Reverse transcription-PCR analysis showed significant up-regulation of VDR and E-cadherin, a downstream target of vitamin D action. These data suggest that the chemopreventive action of hormone replacement therapy on colon neoplasia results, at least in part, from changes in vitamin D activity. Evaluation of gene arrays is useful in chemopreventive intervention studies in small groups of subjects.

Clone-specific expression, transcriptional regulation, and action of interleukin-6 in human colon carcinoma cells.

BACKGROUND: Many cancer cells produce interleukin-6 (IL-6), a cytokine that plays a role in growth stimulation, metastasis, and angiogenesis of secondary tumours in a variety of malignancies, including colorectal cancer. Effectiveness of IL-6 in this respect may depend on the quantity of basal and inducible IL-6 expressed as the tumour progresses through stages of malignancy. We therefore have evaluated the effect of IL-6 modulators, i.e. IL-1beta, prostaglandin E2, 17beta-estradiol, and 1,25-dihydroxyvitamin D3, on expression and synthesis of the cytokine at different stages of tumour progression. METHODS: We utilized cultures of the human colon carcinoma cell clones Caco-2/AQ, COGA-1A and COGA-13, all of which expressed differentiation and proliferation markers typical of distinct stages of tumour progression. IL-6 mRNA and protein levels were assayed by RT-PCR and ELISA, respectively. DNA sequencing was utilized to detect polymorphisms in the IL-6 gene promoter. RESULTS: IL-6 mRNA and protein concentrations were low in well and moderately differentiated Caco-2/AQ and COGA-1A cells, but were high in poorly differentiated COGA-13 cells. Addition of IL-1beta (5 ng/ml) to a COGA-13 culture raised IL-6 production approximately thousandfold via a prostaglandin-independent mechanism. Addition of 17beta-estradiol (10-7 M) reduced basal IL-6 production by one-third, but IL-1beta-inducible IL-6 was unaffected. Search for polymorphisms in the IL-6 promoter revealed the presence of a single haplotype, i.e., -597A/-572G/-174C, in COGA-13 cells, which is associated with a high degree of transcriptional activity of the IL-6 gene. IL-6 blocked differentiation only in Caco-2/AQ cells and stimulated mitosis through up-regulation of c-myc proto-oncogene expression. These effects were inhibited by 10-8 M 1,25-dihydroxyvitamin D3. CONCLUSION: In human colon carcinoma cells derived from well and moderately differentiated tumours, IL-6 expression is low and only marginally affected, if at all, by PGE2, 1,25-dihydroxyvitamin D3, and 17beta-estradiol. However, IL-6 is highly abundant in undifferentiated tumour cells and is effectively stimulated by IL-1beta. In case of overexpression of an IL-6 gene variant with extreme sensitivity to IL-1beta, massive release of the cytokine from undifferentiated tumour cells may accelerate progression towards malignancy by paracrine action on more differentiated tumour cells with a still functioning proliferative IL-6 signalling pathway.

Gender-specific modulation of markers for premalignancy by nutritional soy and calcium in the mouse colon.

Sporadic colorectal cancer develops as a multistep process during decades of latency. Multiple factors, in particular nutrition, influence progression. Both nutritional calcium and soy are known to reduce sporadic cancer incidence. Soy contains high levels of phytoestrogens. Among them genistein is recognized as an antioxidant and cell-cycle inhibitor. However, timing and length of consumption of genistein as well as gender- and colon site-specific activity may result in beneficial or detrimental effects. We therefore evaluated the effect in mice of a basic AIN76A diet containing 20% soy as main protein source fed for 1 or 2 generations. In another set of animals, normal calcium levels (0.5%) were replaced by low calcium (0.04%) with or without supplementation of genistein (0.04%). Expression of the vitamin D receptor, cyclooxygenase (COX)-2, proapoptotic Bak and antiapoptotic Bcl-2 protein, as well as estrogen receptor (ER)-alpha and ER-beta mRNA were evaluated. Results were identical whether soy was fed for 1 or 2 generations. Soy decreased Bak and increased COX-2 and ER-alpha expression site-specifically in female mice. Vitamin D receptor protein was reduced only in males. In animals fed 0.04% dietary calcium, COX-2 protein was increased mainly in females, but supplementation of genistein to the diet lowered COX-2 expression significantly in both genders. Our results suggest that genistein counteracts the induction of a marker of colonic premalignancy by low nutritional calcium in both genders. However, soy itself enhances COX-2 and reduces Bak, but only in females. This suggests detrimental activity of an unknown component of soy triggered by a high-estrogen background.

Differentiation-dependent expression and mitogenic action of interleukin-6 in human colon carcinoma cells: relevance for tumour progression.

Interleukin (IL)-6 mRNA expression in general is low in normal, adenomatous and cancerous human colon mucosa, except in rather undifferentiated lesions, in which IL-6 is overexpressed. Cytokeratin (CK) 8-positive carcinoma cells were identified by double immunostaining as almost exclusive source of IL-6. Likewise, in five (sub)clones of primary culture COGA-1 and COGA-13 human colon carcinoma cells, and in three established cell lines (Caco-2/AQ, Caco-2/15 and HT-29), efficient translation of IL-6 mRNA into protein was observed only in the least differentiated COGA-13 cells. Notably, IL-1beta (5 ng/ml) enhanced IL-6 release in COGA-13 cultures by three orders of magnitude. Although all cell clones studied expressed the IL-6 receptor (IL-6R), rhIL-6 (1-100 ng/ml) had a significant effect on cellular proliferation only in highly differentiated Caco-2 cells. Our data imply that IL-6, when released from rather undifferentiated carcinoma cells, particularly in response to IL-1beta, can advance tumour progression through paracrine growth stimulation of normal or highly differentiated colon tumour cells with intact STAT-3-mediated IL-6 signalling.

The Vitamin D endocrine system of the gut--its possible role in colorectal cancer prevention.

While Vitamin D insufficiency in the US and European population is rising, epidemiological studies suggest an inverse correlation between low serum levels of 25-hydroxyvitamin D(3) (25-OH-D(3)) and colorectal cancer incidence. The antimitotic, prodifferentiating and proapoptotic active metabolite 1alpha,25-dihydroxyvitamin D(3) (1,25-(OH)(2)-D(3)) is synthesized also by colonocytes, since these possess Vitamin D synthesizing (CYP27B1) and catabolic (CYP24) hydroxylases similar to the kidney. Early during colon tumor progression, expression of CYP27B1 and of the Vitamin D receptor increases, suggesting an autocrine/paracrine growth control in colon tissue as a physiological restriction against tumor progression. However, in human adenocarcinomas expression of the catabolic CYP24 is also enhanced when compared with adjacent normal mucosa. Therefore, to maintain colonic accumulation of 1,25-(OH)(2)-D(3) its catabolism needs to be restricted. Our studies in mice show that low nutritional calcium causes hyperproliferation of colon crypts and significant elevation of CYP24 expression, which can be completely abrogated by soy feeding. We suggest that phytoestrogens in soy, known to be estrogen receptor modulators, are responsible for decreased CYP24 expression. These results and our observation that 17beta-estradiol can elevate CYP27B1 expression in rectal tissue of postmenopausal women, may underlie the observed protective effect of estrogens against colorectal cancer in females.

Colon-specific regulation of vitamin D hydroxylases--a possible approach for tumor prevention.

Epidemiological data suggest a protective role of calcium and vitamin D against colorectal tumor pathogenesis. 1,25-dihydroxyvitamin D3 (1,25-D3) is a key determinant of calcium homeostasis, cell proliferation and differentiation. Calcium in the intestinal lumen functions as a growth regulator and may prevent cancer by direct reduction of colonocyte proliferation. While calcium or vitamin D can counteract proliferation by itself, they could also interact if nutritional calcium were to modulate colonic vitamin D synthesis. In this paper we demonstrate that colonic and renal vitamin D hydroxylases are regulated independently. When mice were fed a modified AIN-76 diet containing low dietary calcium (0.1 or 0.04%) fecal calcium content was as low as 5% of that found in mice on a 0.9% calcium containing diet. Low fecal calcium concentration enhanced proliferating cell nuclear antigen expression in the colon mucosa and reduced that of the cyclin dependent kinase inhibitor p21. While low dietary calcium did not affect colonic expression of VDR or 25-hydroxyvitamin D3 1alpha-hydroxylase (CYP27B1) mRNA, it influenced their renal expression in the expected manner by elevating the CYP27B1 expression and reducing VDR and 25-hydroxyvitamin D3 24-hydroxylase (CYP24) expression. In contrast, low calcium diets significantly augmented colonic CYP24 mRNA expression, but only in the ascending colon. This might result in reduced colonic accumulation of 1,25-D3 during hyperproliferation caused by low dietary calcium and might support site-specific tumorigenesis. The important realization that low dietary calcium by itself is a risk factor for colorectal carcinogenesis and that colonic and renal vitamin D hydroxylases indeed are regulated differently from each other will provide novel approaches for colon cancer prevention.

25-hydroxyvitamin D3-1alpha-hydroxylase expression in normal and malignant human colon.

1,25-dihydroxyvitamin D(3) has anti-mitotic, pro-differentiating, and pro-apoptotic activity in tumor cells. We demonstrated that the secosteroid can be synthesized and degraded not only in the kidney but also extrarenally in intestinal cells. Evaluation of 1,25-dihydroxyvitamin D(3)-synthesizing CYP27B1 hydroxylase mRNA (real-time PCR) and protein (immunoblotting, immunofluorescence) showed enhanced expression in high- to medium-differentiated human colon tumors compared with tumor-adjacent normal mucosa or with colon mucosa from non-cancer patients. In high-grade undifferentiated tumor areas expression was lost. Many cells co-expressed CYP27B1 and the vitamin D receptor. We suggest that autocrine/paracrine antimitotic activity of 1,25-dihydroxyvitamin D(3) could prevent intestinal tumor formation and progression.

The constitutive expression of galectin-3 is downregulated in the intestinal epithelia of Crohn's disease patients, and tumour necrosis factor alpha decreases the level of galectin-3-specific mRNA in HCT-8 cells.

OBJECTIVE: Galectin-3, a lectin with specificity for beta galactoside, is expressed by a variety of cells, including intestinal epithelial cells. Among other functions, galectin-3 mediates cell adhesion and is involved in inflammatory processes. In this study, we assessed the expression of galectin-3 in intestinal epithelial cells from Crohn's disease patients (n = 10), ileum adjacent to resected colon carcinoma (n = 9), unspecific bowel inflammation (n = 1), diverticulosis (n = 1), ulcerative colitis (n = 3) and healthy jejunum used for interposition in larynx carcinoma (n = 1). The role of cytokines on galectin-3 expression was a further aim of our study. METHODS: The galectin-3 distribution in intestinal epithelia was analysed by immunohistochemistry, immunoblotting, immunofluorescence and reverse transcriptase polymerase chain reaction (RT-PCR). Human intestinal epithelial cell line (HCT-8) and primary cultured intestinal epithelial cells were treated with cytokines, and the effects on galectin-3 expression were determined by RT-PCR. RESULTS: Galectin-3 showed a homogeneous distribution in epithelia from control patients. In contrast, in epithelial cells from Crohn's disease lesions, galectin-3 staining was strongly spotted and heterogeneous. In inflamed and reorganized tissue, galectin-3 expression was markedly reduced, and was associated with disintegration of epithelia. Primary cultured epithelial cells as well as HCT-8 cells expressed galectin-3 protein and mRNA. Incubation of HCT-8 cells with tumour necrosis factor alpha (TNF-alpha), but not with other cytokines, substantially reduced galectin-3 expression as shown by semiquantitative RT-PCR. CONCLUSIONS: Downregulation of galectin-3 in the intestinal epithelium of Crohn's disease patients may be a consequence of enhanced TNF-alpha production by inflammatory cells, thereby contributing to the pathophysiology of the disease.

Clonal differences in expression of 25-hydroxyvitamin D(3)-1alpha-hydroxylase, of 25-hydroxyvitamin D(3)-24-hydroxylase, and of the vitamin D receptor in human colon carcinoma cells: effects of epidermal growth factor and 1alpha,25-dihydroxyvitamin D(3).

Human colon carcinoma cells express 25-hydroxyvitamin D(3)-1alpha-hydroxylase (CYP27B1) and thus produce the vitamin D receptor (VDR) ligand 1alpha,25-dihydroxyvitamin D(3) (1,25-D3), which can be metabolized by 25-hydroxyvitamin D(3)-24-hydroxylase (CYP24). Expression of VDR, CYP27B1, and CYP24 determines the efficacy of the antimitotic action of 1,25-D3 and is distinctly related to the degree of differentiation of cancerous lesions. In the present study we addressed the question of whether the effects of epidermal growth factor (EGF) and of 1,25-D3 on VDR, CYP27B1, and CYP24 gene expression in human colon carcinoma cell lines also depend on the degree of cellular differentiation. We were able to show that slowly dividing, highly differentiated Caco-2/15 cells responded in a dose-dependent manner to both EGF and 1,25-D3 by up-regulation of VDR and CYP27B1 expression, whereas in highly proliferative, less differentiated cell lines, such as Caco-2/AQ and COGA-1A and -1E, negative regulation was observed. CYP24 mRNA was inducible in all clones by 1,25-D3 but not by EGF. From the observed clonal differences in the regulatory effects of EGF and 1,25-D3 on VDR and CYP27B1 gene expression we suggest that VDR-mediated growth inhibition by 1,25-D3 would be efficient only in highly differentiated carcinomas even when under mitogenic stimulation by EGF.