[Abelson interactor 1 (Abi1) in colorectal cancer. From synaptic plasticity to tumor cell migration]. / Abelson interactor 1 (Abi1) im kolorektalen Karzinom. Von der synaptischen Plastizität zur Tumorzellmigration.

BACKGROUND: Invasion and metastatic dissemination of tumor cells defines the prognosis of patients with colorectal cancer (CRC). The Abelson interactor 1 (Abi1), a 65 kD substrate of the eponymous Abelson tyrosine kinase, interacts with phosphatidylinositol-3-kinase (PI3K) and heterogeneous nuclear ribonucleoprotein K (hnRNP K) and is a key regulator of cytoskeletal reorganization during synaptic maturation and cellular migration. AIM: The aim of this study was the analysis of Abi1 expression patterns and to elucidate the role in cytoskeletal reorganization in colorectal carcinoma cells. MATERIAL AND METHODS: The methods used in this study were immunohistochemistry; immunofluorescence microscopy; liposomal transfection and protein analysis by Western blotting. RESULTS: The results showed that Abi1 is expressed at the invasive front of colorectal carcinomas and localizes to the leading edge of lamellipodia in cultured colorectal carcinoma cells. A phosphorylated isoform of Abi1 that stains positively in these microcompartments disappears after treatment with the tyrosine kinase inhibitor STI571 (Glivec®). The RNA interference (RNAi) approach knockdown of Abi1 as well as treatment with STI571 induce a shift in cellular morphology from broad lamellipodia-like to thin filopodia-like cellular protrusions. DISCUSSION: The initial results support a central role for phosphorylated Abi1 in the formation of lamellipodia-like cellular protrusions as a prerequisite for cellular migration of colorectal carcinoma cells. As phosphorylation of Abi1 could be pharmaceutically targeted with STI571, this indicates a possible therapeutic option to prevent the gain of a metastatic phenotype in colorectal cancer. This possibility will be further evaluated in ongoing research.

[U-HO1. A new cell line derived from a primary refractory classical Hodgkin lymphoma]. / U-HO1. Eine neue Zelllinie, abstammend von einem primär therapierefraktären klassischen Hodgkin-Lymphom.

The Hodgkin cell line U-HO1 was established from a malignant pleural effusion of a 23-yr-old male patient during the end stage of refractory nodular sclerosing classical Hodgkin lymphoma (cHL). Since its establishment in 2005, U-HO1 has maintained stable characteristics in vitro and has a doubling time of about 4 days under standard culture conditions. U-HO1 forms typical Reed/Sternberg cells in suspension, is EBV negative, lacks HLA-ABC- but expresses HLA-D- proteins/CD74 and surface exposes CD15 together with CD30 in the absence of CD19 and CD20. Karyotype analysis of U-HO1 revealed a hyperdiploid karyotype with multiple clonal aberrations. Most significant is an elongated chromosome 2, der(2)t(2;10)(q35;q16.1)add(2)(p13). CGH analysis revealed the following imbalances: ish cgh dim(1)(p13p31)(p12q21), enh(2)(p13p23), dim(4)(q31.3qter), enh(6)(q22q27), enh(12), enh(18),enh(20)(q13.1pter). FISH analysis showed about six-fold amplification of REL and BCL-11A, thus, U-HO1 is prototypical for cHL in every aspect tested so far. Compared to other HL cell lines, U-HO1 proved far less genetically aberrant suggesting that U-HO1's imbalances suffice to cause the full-blown phenotype of primary refractory cHL.

U-HO1, a new cell line derived from a primary refractory classical Hodgkin lymphoma.

The Hodgkin cell line U-HO1 was established from a malignant pleural effusion of a 23-year-old male patient during the end stage of refractory nodular sclerosing classical Hodgkin lymphoma (cHL). Since its establishment in 2005, U-HO1 has maintained stable characteristics in vitro and has a doubling time of about 4 days under standard culture conditions. U-HO1 forms typical Reed-Sternberg cells in suspension, is EBV negative, lacks HLA-A, -B, -C but expresses HLA-D proteins/CD74 and exposes CD15 together with CD30 in the absence of CD19 and CD20 on the cell surface. Karyotype analysis of U-HO1 revealed a hyperdiploid karyotype with multiple clonal aberrations. Most significant is an elongated chromosome 2, der(2)t(2;10)(q35; q16.1)add(2)(p13). CGH analysis revealed the following imbalances: ish cgh dim(1)(p13p31)(p12q21), enh(2)(p13p23), dim(4)(q31.3qter), enh(6)(q22q27), enh(12), enh(18), enh(20) (q13.1pter). FISH analysis showed about six-fold amplification of REL and BCL11A, thus, U-HO1 is prototypical for cHL in every aspect tested so far. As an outstanding feature compared to the existing HL cell lines, U-HO1 has high levels of microRNA transcripts of MIRN216 and MIRN217 located in the amplicon 2p16. Compared to other HL cell lines, U-HO1 proved far less genetically aberrant suggesting that U-HO1's imbalances suffice to cause the full-blown phenotype of primary refractory cHL.

Sex-specific telomere length profiles and age-dependent erosion dynamics of individual chromosome arms in humans.

During aging, telomeres are gradually shortened, eventually leading to cellular senescence. By T/C-FISH (telomere/centromere-FISH), we investigated human telomere length differences on single chromosome arms of 205 individuals in different age groups and sexes. For all chromosome arms, we found a linear correlation between telomere length and donor age. Generally, males had shorter telomeres and higher attrition rates. Every chromosome arm had its individual age-specific telomere length and erosion pattern, resulting in an unexpected heterogeneity in chromosome-specific regression lines. This differential erosion pattern, however, does not seem to be accidental, since we found a correlation between average telomere length of single chromosome arms in newborns and their annual attrition rate. Apart from the above-mentioned sex-specific discrepancies, chromosome arm-specific telomere lengths were strikingly similar in men and women. This implies a mechanism that arm specifically regulates the telomere length independent of gender, thus leading to interchromosomal telomere variations.

[Biallelic mutation of SOCS-1 impairs JAK2 degradation and sustains phospho-JAK2 action in MedB-1 mediastinal lymphoma line]. / Die biallelische Mutation von SOCS-1 verhindert den Abbau von JAK2 und prolongiert die Wirkung von phospho-JAK2 in der mediastinalen B-Zell Lymphomlinie MedB-1.

Primary mediastinal B-cell lymphoma (PMBL) is a well-defined subtype of diffuse large B-cell lymphoma. Molecular cytogenetics revealed frequent gains of 9 p24. JAK2, mapping in this region, is presently regarded as a candidate oncogene since expression profiling showed high JAK2 transcript levels and JAK2 was found to be constitutively phosphorylated in mediastinal B-cell lymphomas. We confirm that in the MedB-1 mediastinal B-cell line, harbouring a trisomy 9, JAK2 transcription is elevated and the product is highly phosphorylated. However, JAK2 is not over-expressed at the protein level. On top, JAK2 protein turnover is even delayed. This unexpected finding coincides with a biallelic mutation of the SOCS-1 gene in this cell, which abrogates SOCS box function of the protein. Ectopic expression of wt-SOCS-1 in MedB-1 leads to growth arrest, dramatic reduction of phospho-JAK2 and its downstream partner phospho-STAT5. We conclude that, in MedB-1, action of phospho-JAK2 is sustained due to defective SOCS-1. Hence, SOCS-1 qualifies as a novel tumor suppressor. Of note, the SOCS-1 mutations are also present in the parental tumor of MedB-1 and were detected in 9 of 20 PMBL.

Sustained hyposmotic stress induces cell death: apoptosis by defeat.

We describe sustained hyposmotic stress as a novel type of environmental condition enforcing apoptosis. In a dose- and time-dependent fashion, hyposmotic stress leads to a delayed type of apoptosis with considerable variations in constitutive sensitivity among different cell types. For example, after 48 h at 84 mosmol/l, the death rate ranged from 10.8 +/- 0.7% in AsPc1 human pancreatic carcinoma cells to 72.0 +/- 1.6% in HK-2 human kidney tubule cells. Caspase inhibitors rendered cells more resistant to hyposmolar stress; the caspase 3 inhibitor Ac-Asp-Glu-Val-aspartic acid aldehyde was the most efficient. After 24 h of stress, HT-29 colon carcinoma and HK-2 cells had increased their mitochondrial mass. This went along with an increase in mitochondrial membrane potential in HT-29 cells but with a decrease in HK-2 cells. Starting at 2 h of stress, we detected transient CD95L transcription followed by surface expression of CD95L in HT-29 but not in HK-2 cells. Inhibitory CD95L antibody partially inhibited specific death in HT-29 but not in HK-2 cells. Thus, as in other types of stress-induced apoptosis, the CD95/CD95L system is one of the different routes to suicide optionally used by hyposmotically stressed cells. Our findings may have clinical implications for the prevention and treatment of tissue damage caused by severe hyposmolar states.

Genome-wide analysis of sixteen chordomas by comparative genomic hybridization and cytogenetics of the first human chordoma cell line, U-CH1.

Cytogenetic information on chordomas is rudimentary and restricted to GTG-banding analysis of 26 cases worldwide. In this study, we present the chromosomal imbalances detected in a series of 16 chordomas (10 sacrococcyeal, five sphenooccipital, and one spinal) from 13 patients using comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). On average, 3.2 losses and 4.2 gains were detected per tumor. The most common DNA copy number alterations were losses on chromosomal arms 3p (50%) and 1p (44%). Losses of 3p were detected in five of seven primary chordomas. Therefore, the loss of 3p might be an early event in chordoma genesis. The most common gains involved 7q (69%), 20 (50%), 5q (38%), and 12q (38%). Additionally, we raised the first human chordoma cell line, U-CH1, from a recurrence of a sacral chordoma. U-CH1 and its parent tumor had almost the same CGH profile. According to GTG-banding and multicolor FISH, U-CH1 has the following clonal chromosomal abnormalities: der(1)t(1;22), del(4), +del(5), +del(6), +7, del(9), del(10), +der(20)t(10;20), +21. Thus, the novel permanent human chordoma cell line U-CH1 has chordoma-typical cytogenetic aberrations. Our data suggest that tumor suppressor genes or mismatch repair genes (located at 1p31 and 3p14) and oncogenes (located in 7q36) might be involved in chordoma genesis.

MedB-1, a human tumor cell line derived from a primary mediastinal large B-cell lymphoma.

Primary mediastinal B-cell lymphoma is a locally highly aggressive but poorly disseminating tumor composed of medium sized or large cells most probably of thymic medullary origin. It has a mature B-cell phenotype, typically lacks immunoglobulin expression and has variable defects in expression of HLA-molecules. We present here a cell line, MedB-1, derived from such a tumor. As is frequently found in mediastinal B-cell lymphomas in situ, MedB-1 is CD10(-), CD19(+), CD21(-), CD22(+), CD23(+), CD25(-), CD37(+), CD38(-), CD39(+), CD40(+), CD54(+), CD95(+). Like the parental tumor, MedB-1 lacks HLA-A,B,C alpha-chains and beta(2)microglobulin and expresses HLA-D molecules at decreased levels. Both parental tumor and MedB-1 cells are clonally related as shown by immunoglobulin heavy chain gene rearrangement analysis. Unlike the parental tumor tissue, the MedB-1 cell line cytoplasmically expresses IgG/kappa in a very small subset of cells under standard culture conditions. MedB-1 does not contain any Epstein-Barr virus DNA. In a tissue adhesion assay MedB-1 cells showed an extensive binding to the medullary region of normal thymus. Altogether, MedB-1 is a suitable tool for functional and molecular analysis of this distinct lymphoma entity.

Low frequency of chromosomal imbalances in anaplastic ependymomas as detected by comparative genomic hybridization.

We screened 26 ependymomas in 22 patients (7 WHO grade I, myxopapillary, myE; 6 WHO grade II, E; 13 WHO grade III, anaplastic, aE) using comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH). 25 out of 26 tumors showed chromosomal imbalances on CGH analysis. The chromosomal region most frequently affected by losses of genomic material clustered on 13q (9/26). 6/7 myE showed a loss on 13q14-q31. Other chromosomes affected by genomic losses were 6q (5/26), 4q (5/26), 10 (5/26), and 2q (4/26). The most consistent chromosomal abnormality in ependymomas so far reported, is monosomy 22 or structural abnormality 22q, identified in approximately one third of Giemsa-banded cases with abnormal karyotypes. Using FISH, loss or monosomy 22q was detected in small subpopulations of tumor cells in 36% of cases. The most frequent gains involved chromosome arms 17 (8/26), 9q (7/26), 20q (7/26), and 22q (6/26). Gains on 1q were found exclusively in pediatric ependymomas (5/10). Using FISH, MYCN proto-oncogene DNA amplifications mapped to 2p23-p24 were found in 2 spinal ependymomas of adults. On average, myE demonstrated 9.14, E 5.33, and aE 1.77 gains and/or losses on different chromosomes per tumor using CGH. Thus, and quite paradoxically, in ependymomas, a high frequency of imbalanced chromosomal regions as revealed by CGH does not indicate a high WHO grade of the tumor but is more frequent in grade I tumors.

Gain of chromosome arm 9p is characteristic of primary mediastinal B-cell lymphoma (MBL): comprehensive molecular cytogenetic analysis and presentation of a novel MBL cell line.

Primary mediastinal B-cell lymphoma (MBL) is an aggressive Non-Hodgkin's Lymphoma, which has been recognized as a distinct disease entity. We performed a comprehensive molecular cytogenetic study analyzing 43 MBLs. By comparative genomic hybridization (CGH), the most common aberrations were gains of chromosome arms 9p and Xq, which were present in 56% and 40% of cases, respectively. Based on the limited resolution of CGH, this technique may underestimate the real incidence of aberrations. Therefore, we also did an interphase cytogenetic study with eight DNA probes mapping to chromosome regions frequently altered in B-cell lymphomas. With this approach, both 9p and Xq gains were found in more than 70% of cases (75% and 87%, respectively). The findings were compared with results obtained in 308 other B-cell lymphomas. Gains in 9p were identified in only six of the 308 cases, and only one of these lymphomas with 9p gains was not primarily extranodal in origin (P < 10-(20) for CGH data and P < 10-(11) for fluorescence in situ hybridization data). We also present a novel MBL cell line, MedB-1, which carries the genetic aberrations characteristic of this entity.

LiSa-2, a novel human liposarcoma cell line with a high capacity for terminal adipose differentiation.

LiSa-2 is a stable cell line derived from a poorly differentiated, pleomorphic liposarcoma. In serum-containing medium, LiSa-2 cells are fibroblastoid and rapidly dividing. In a serum-free, chemically defined culture medium containing physiological concentrations of insulin, triiodothyronine and cortisol, LiSa-2 cells divide slower and, extensively storing fat, acquire adipocyte morphology. In contrast to fibroblastoid LiSa-2 cells, these adipocyte-like LiSa-2 cells highly express transcripts for peroxisome proliferator-activated receptor-gamma, lipoprotein lipase, fatty acid synthetase, hormone-sensitive lipase, adipocyte most abundant gene transcript-1, glycerol-3-phosphate-dehydrogenase and the insulin-sensitive glucose transporter-4, all of which are specific for differentiated adipocytes. However, leptin mRNA expression was demonstrated only after preventing DNA methylation by incorporation of 5-aza-deoxycytidine into cellular DNA. Functionally, adipocyte-like LiSa-2 cells show increased insulin-dependent glucose uptake and lipid synthesis and are sensitive to lipolytic agents. This cell line may serve as an in vitro model for studying the regulation of human liposarcoma differentiation and for screening drugs for induction of differentiation-associated growth arrest in liposarcomas.

Delineation of the 6p22 amplification unit in urinary bladder carcinoma cell lines.

Eight cell lines from transitional cell carcinoma of the urinary bladder were analyzed by comparative genomic hybridization. All tumor lines exhibited frequent chromosome gains (11.5/cell line) and losses (8.4/cell line). In six cell lines, gain of chromosome 5p was associated with gains of 6p and 20q. In five of these cell lines, amplification of parts of 6p was observed. Cytogenetic investigation combined with fluorescence in situ hybridization analysis revealed typical marker chromosomes with homogeneously staining regions (HSRs) containing material from 6p. By hybridizing individual yeast artificial chromosome probes from a chromosome 6p contig to these HSRs, a contig of three yeast artificial chromosomes common to all 6p HSRs was identified that spans less than 2 Mb. The genes SOX4 and PRL were shown to map to this region and to be coamplified in the cell lines. However, SOX4 was not overexpressed in any cell line and PRL was not expressed at all. Thus, the presumptive 6p oncogene remains to be conclusively identified.

Detailed marker chromosome analysis in cell line U-BLC1, established from transitional-cell carcinoma of the bladder.

A permanent cell line, U-BLC1, was established from a primary transitional-cell carcinoma, TCC, of the urinary bladder. Karyotype analysis showed the line to be highly aberrant, with a near-triploid chromosome number of 68 to 73. Comparative genomic hybridization revealed some distinct differences between the primary tumor and the established cell line. Karyotype analysis showed 3 marker chromosomes with homogeneously staining regions, HSRs, in the cell line. The HSRs were isolated by microdissection and the microdissection probes were hybridized to normal metaphase chromosomes. The HSRs contain sequences known to be frequently involved in amplification in transitional-cell carcinoma of the bladder, 6p22, 7p11-p12, 9p23-pter, and one region not yet reported to be amplified in primary TCC of the bladder, 1p31-p32. A candidate-gene approach showed that in the region 7p11-p12 the EGFR locus is amplified and highly expressed.

Chromosomal changes during progression of transitional cell carcinoma of the bladder and delineation of the amplified interval on chromosome arm 8q.

The cascade of genetic alterations leading to malignant transformation has been described for adenocarcinoma of the colon but is not established for other common tumor entities. In the present study, different stages of transitional cell carcinoma (TCC) of the bladder are analyzed by comparative genomic hybridization. A dynamic pattern of the chromosomal changes during tumor progression is described. Deletion of chromosome arm 9q is the earliest genetic alteration in pTa tumors. In stage pT1 carcinomas, losses of 9q, 9p, and 11p and gain of 1q and 8q are the most common. In addition to the changes specific for earlier stages, gain of 5p and 20q becomes prominent in carcinomas stage > or =pT2. Association analysis reveals a remarkable cooccurrence of 9p deletion with gain of 5p and 20q in > or =pT2 tumors. In order to determine more precisely the size of the amplified segment and the degree of amplification on chromosome arm 8q in stage pT1 tumors, this region was analyzed by semiquantitative PCR using polymorphic microsatellite markers. These studies revealed an up to 13-fold amplification. The common region of amplification could be narrowed down to 8q22.3 and between GAAT1A4 and D8S1834 (about 7 cM).

Pleural mesothelioma mimics the integrin profile of activated, sessile rather than detached mesothelial cells.

Mesothelial cells (MC) form a polarized monolayer lining serosal cavities. During serositis, the MC lining undergoes hyperplasia, and MC are shed into effusions. During these processes, contact with basement membrane and, ultimately, neighboring cells is at least temporarily lost, suggesting regulated alterations in cell/matrix and cell/cell adhesion. Such interactions are primarily mediated by integrins. Malignant mesothelioma has a growth pattern characterized by lateral, limited invasive but contiguous spread. During serositis, activated MC, both sessile and detached, expressed an extended spectrum of beta1, beta3 and beta4 integrins compared with resting MC, as shown by immunohistology. Malignant mesothelioma had an integrin repertoire and a subcellular distribution resembling that of activated sessile rather than floating MC. In vitro, MC exposed a more comprehensive pattern of integrins than that of the newly established mesothelioma cell lines ME-HD-1 and ME-HD-2, as shown by flow cytometry. MC consistently adhered better than mesothelioma cells to laminin, tenascin, fibronectin and collagen type IV. Adhesion of MC and mesothelioma cells to these matrix proteins was, at least in part, mediated via beta1 integrins. The different integrin profiles and adhesion properties of cultured MC and mesothelioma cells may reflect a limited functional differentiation of the latter.

Primary mediastinal (thymic) B-cell lymphoma is characterized by gains of chromosomal material including 9p and amplification of the REL gene.

Primary mediastinal (thymic) B-cell lymphoma is a high-grade non-Hodgkin's lymphoma with unique features. By using comparative genomic hybridization and interphase cytogenetics, 26 tumors were analyzed to identify genomic imbalances. Gains of chromosomal material were much more frequent than losses (110 v 10) and involved chromosomes 9p, 12q, and Xq (31% to 50%). Interestingly, gain of Xq coincided with gain of 9p. Distinct high-level amplifications were found in four subregions. In 2 cases, amplifications of proto-oncogene REL were shown by filter hybridization, indicating a possible pathogenic role of this gene. The characteristic pattern of chromosomal imbalances distinct from other B-cell lymphomas suggests a specific pathway of genetic changes associated with this lymphoma.

Microwave irradiation of paraffin-embedded tissue sensitizes the TUNEL method for in situ detection of apoptotic cells.

Apoptosis is a morphologically distinct form of programmed cell death that plays an important role in the growth regulation of a variety of tissues and also in the elimination of self-reacting immunocompetent cells. Several techniques for the qualitative and quantitative detection of this process have been established; recently, an in situ nick end-labelling technique based on the detection of DNA fragmentation, which is a molecular characteristic of apoptotic cell death, was described. Applying this method to paraffin sections of human tissues, sensitivity was observed to be inconsistently low with regard to the expected number of apoptotic cells. In the present study we show that irradiation of the tissue sections in 10 mM citrate buffer, pH 6.0, by microwaves at 750 W considerably enhances the sensitivity of this nick end-labelling technique.

Expression of APO-1 (CD95), a member of the NGF/TNF receptor superfamily, in normal and neoplastic colon epithelium.

APO-1 is a 48-kDa cell-membrane protein identical to the Fas antigen now designated CD95. It is a member of the NGF/TNF receptor superfamily. Anti-APO-1 monoclonal antibody induces apoptosis in a variety of cell types expressing this antigen. We immunohistochemically investigated APO-1 expression in normal colon mucosa, 20 adenomas, 258 colon carcinomas and 10 liver metastases and carried out in vitro studies using a panel of colon-carcinoma cell lines. Immunohistochemically, APO-1 was regularly expressed at the basolateral membrane of normal colon epithelia. In a minor fraction of colon adenomas and in 39.1% of colon carcinomas APO-1 expression was diminished and in 48.1% of carcinomas, predominantly of the non-mucinous type, APO-1 expression was completely abrogated. The normal level of APO-1 in carcinomas was correlated with the mucinous type. Reduced/lost APO-1 expression was more frequent in rectal carcinomas. Complete loss of APO-1 was more frequent in tumors that had already metastasized. APO-1 expression in liver metastases essentially corresponded to that of the primary tumors. Comparative analysis with data from previous studies revealed that the mode of APO-1 expression is correlated with that of HLA-A,B,C./beta 2m, HLA-DR, HLA-D-associated invariant chain and of the secretory component. Surface expression of APO-1 was heterogeneous in colon-carcinoma cell lines; SW480 expressed considerable amounts of APO-1 on all cells, while HT-29 constitutively did less so and only in a minority of cells. Surface density of APO-1 and the fraction of positive cells in HT-29 was enhanced by interferon-gamma (IFN-gamma) and, additively, by tumor necrosis factor-alpha (TNF-alpha), whereas in SW480 APO-1 expression was not modulated by these cytokines. We conclude that neoplastic transformation of colon epithelium often leads to a loss of the physiologic, high level of surface APO-1 by giving rise either to a stable lack of APO-1 or to an IFN-gamma/TNF-alpha-sensitive phenotype of inducible APO-1 expression.

Comparative evaluation of integrin alpha- and beta-chain expression in colorectal carcinoma cell lines and in their tumours of origin.

The integrin family consists of broadly expressed cell surface adhesion receptors, each member of which is composed of a non-covalently linked alpha/beta heterodimer. Integrin receptors are involved in the interaction with matrix proteins and may contribute to invasion and metastasis of carcinomas. To examine the biological role integrins play in colorectal carcinoma we compared the expression of integrin alpha- and beta-subunits in situ and in vitro. Eight newly established cell lines derived from immunohistochemically characterized colorectal carcinomas together with two sublines obtained after nude mouse passage and the commonly used colon carcinoma lines HT-29, SW480, SW620, and COLO 205 were investigated by immunocytochemistry and flow cytometry. The carcinomas in situ expressed alpha 1-, alpha 2-, alpha 3-, alpha 6-, alpha v- and beta 1-subunits in variable amounts while being devoid of alpha 4, alpha 5, and beta 3. The individual integrin profile of the tumour in tissue was essentially maintained in vitro. However, a neo expression of the alpha 5 chain was found, together with an induction or increase in alpha 1, alpha 2, alpha 3, alpha v and beta 1 levels. No decrease in integrin subunit expression was observed. Standard-serum and serum-free medium revealed no striking differences in alpha- and beta-chain expression in the cell lines HT-29 and COLO 205. In serum-free medium, SW480 showed a slight increase of alpha 1 and alpha 5 and a decrease of alpha 3 and alpha v while SW620 expressed more alpha 1. We conclude that the great variability of adhesion receptor expression of the integrin family in colorectal carcinomas in situ is essentially maintained in vitro, although culture conditions which are only marginally influenced by serum factors unpredictably lead to some increase in expression or even induction of several integrin subunits.