Human papillomavirus (HPV) and somatic EGFR mutations are essential, mutually exclusive oncogenic mechanisms for inverted sinonasal papillomas and associated sinonasal squamous cell carcinomas.

Background: Inverted sinonasal (Schneiderian) papilloma (ISP) is a locally aggressive neoplasm often associated with sinonasal squamous cell carcinoma (SNSCC). While the etiology of ISP is not well understood, human papillomavirus (HPV) has been detected in a subset of cases. Our group recently identified activating somatic EGFR mutations in the majority of ISP and ISP-associated SNSCC. However, the relationship between EGFR mutations and HPV infection has not been explored. Patients and methods: We evaluated 58 ISP and 22 ISP-associated SNSCC (including 13 patients with matched ISP/SNSCC samples), as well as 14 SNSCC without clinical or pathologic evidence of an associated ISP. Formalin-fixed, paraffin-embedded samples were evaluated for EGFR mutations using Sanger sequencing and for HPV infection using GP5+/GP6+ PCR. HPV subtyping based on the L1 sequence was done for HPV positive cases including temporally distinct tumors for four patients. Clinicopathologic data including progression free survival was also analyzed. Results: All ISP and ISP-associated SNSCC demonstrated either an EGFR mutation or HPV infection. HPV and EGFR mutation were mutually exclusive in all cases of ISP-associated SNSCC and all but one ISP; this case was only weakly HPV positive, and analysis of a prior temporally distinct ISP specimen from this patient failed to show HPV infection, suggesting transient infection/incidental colonization. HPV subtypes in ISP and ISP-associated SNSCC were predominantly low-risk, in contrast with SNSCC without ISP association, which showed frequent high-risk HPV. All paired ISP and associated SNSCC samples demonstrated concordant HPV status and EGFR genotypes. ISP progression to SNSCC was significantly associated with the presence of HPV infection and the absence of an EGFR mutation (log-rank = 9.620, P = 0.002). Conclusions: Collectively our data show that EGFR mutations and HPV infection represent essential, alternative oncogenic mechanisms in ISP and ISP-associated SNSCC.

Myelodysplastic syndromes without peripheral monocytosis but with evidence of marrow monocytosis share clinical and molecular characteristics with CMML.

MDS patients may present with monocytic marrow proliferation not fulfilling criteria for CMML. We analyzed MDS patients with or without a marrow monocytic proliferation by following up the amount of monocytic proliferation and characterizing their molecular profile. 315 MDS patients of Duesseldorf MDS registry were divided into two groups: A) 183 patients with monocytic esterase positive cells in marrow and monocytes between 101 and 900/µl in blood and B) 132 patients without monocytic esterase positive cells in marrow and monocytes in blood ≤100/µl. Twenty patients of each group were screened with regard to ASXL1, TET2, RUNX1, SETBP1, NRAS, and SRSF2 using Illumina myeloid panel. Group A patients were older, had significantly higher WBC, hemoglobin levels, neutrophils and platelets. CMML evolution rates were 4.9% and 1.5%, respectively (p=n.s.). TET2, NRAS and SRFS2 mutation frequencies were higher in group A and four patients had coexisting TET2 and SRFS2 mutation, which was shown to be characteristic but not specific for CMML. MDS patients with marrow monocytic proliferation have a more CMML-like pheno- and genotype and develop CMML more often. Those patients could potentially be very early stages of CMML or represent a CMML-like myeloid neoplasma with marrow adherence of the monocytic cell population.

The influence of laser scribing on magnetic domain formation in grain oriented electrical steel visualized by directional neutron dark-field imaging.

The performance and degree of efficiency of transformers are directly determined by the bulk magnetic properties of grain oriented electrical steel laminations. The core losses can be improved by post manufacturing methods, so-called domain refinement techniques. All these methods induce mechanical or thermal stress that refines the domain structure. The most commonly used technique is laser scribing due to the no-contact nature and the ease of integration in existing production systems. Here we show how directional neutron dark-field imaging allows visualizing the impact of laser scribing on the bulk and supplementary domain structure. In particular, we investigate the domain formation during magnetization of samples depending on laser treatment parameters such as laser energy and line distances. The directional dark-field imaging findings were quantitatively interpreted in the context with global magnetic hysteresis measurements. Especially we exploit the orientation sensitivity in the dark-field images to distinguish between different domain structures alignment and their relation to the laser scribing process.

Visualizing the morphology of vortex lattice domains in a bulk type-II superconductor.

Alike materials in the solid state, the phase diagram of type-II superconductors exhibit crystalline, amorphous, liquid and spatially inhomogeneous phases. The multitude of different phases of vortex matter has thence proven to act as almost ideal model system for the study of both the underlying properties of superconductivity but also of general phenomena such as domain nucleation and morphology. Here we show how neutron grating interferometry yields detailed information on the vortex lattice and its domain structure in the intermediate mixed state of a type-II niobium superconductor. In particular, we identify the nucleation regions, how the intermediate mixed state expands, and where it finally evolves into the Shubnikov phase. Moreover, we complement the results obtained from neutron grating interferometry by small-angle neutron scattering that confirm the spatially resolved morphology found in the intermediate mixed state, and very small-angle neutron scattering that confirm the domain structure of the vortex lattice.

Integrative molecular profiling of routine clinical prostate cancer specimens.

BACKGROUND: Comprehensive molecular profiling led to the recognition of multiple prostate cancer (PCa) molecular subtypes and driving alterations, but translating these findings to clinical practice is challenging. PATIENTS AND METHODS: We developed a formalin-fixed paraffin-embedded (FFPE) tissue compatible integrative assay for PCa molecular subtyping and interrogation of relevant genetic/transcriptomic alterations (MiPC). We applied MiPC, which combines capture-based next generation sequencing and quantitative reverse transcription PCR (qRT-PCR), to 53 FFPE PCa specimens representing cases not well represented in frozen tissue cohorts, including 8 paired primary tumor and lymph node metastases. Results were validated using multiplexed PCR based NGS and Sanger sequencing. RESULTS: We identified known and novel potential driving, somatic mutations and copy number alterations, including a novel BRAF T599_V600insHT mutation and CYP11B2 amplification in a patient treated with ketoconazole (a potent CYP11B2 inhibitor). qRT-PCR integration enabled comprehensive molecular subtyping and provided complementary information, such as androgen receptor (AR) target gene module assessment in advanced cases and SPINK1 over-expression. MiPC identified highly concordant profiles for all 8 tumor/lymph node metastasis pairs, consistent with limited heterogeneity amongst driving events. MiPC and exome sequencing were performed on separately isolated conventional acinar PCa and prostatic small cell carcinoma (SCC) components from the same FFPE resection specimen to enable direct comparison of histologically distinct components. While both components showed TMPRSS2:ERG fusions, the SCC component exclusively harbored complete TP53 inactivation (frameshift variant and copy loss) and two CREBBP mutations. CONCLUSIONS: Our results demonstrate the feasibility of integrative profiling of routine PCa specimens, which may have utility for understanding disease biology and enabling personalized medicine applications.

Oat1/3 restoration protects against renal damage after ischemic AKI.

Expression of proximal tubular organic anion transporters Oat1 and Oat3 is reduced by PGE2 after renal ischemia and reperfusion (I/R) injury. We hypothesized that impaired expression of Oat1/3 is decisively involved in the deterioration of renal function after I/R injury. Therefore, we administered probenecid, which blocks proximal tubular indomethacin uptake, to abolish the indomethacin-mediated restoration of Oat1/3 regulation and its effect on renal functional and morphological outcome. Ischemic acute kidney injury (iAKI) was induced in rats by bilateral clamping of renal arteries for 45 min with 24-h follow-up. Low-dose indomethacin (1 mg/kg) was given intraperitoneally (ip) at the end of ischemia. Probenecid (50 mg/kg) was administered ip 20 min later. Indomethacin restored the expression of Oat1/3, PAH net secretion, and PGE2 clearance. Additionally, indomethacin improved kidney function as measured by glomerular filtration rate (GFR), renal perfusion as determined by corrected PAH clearance, and morphology, whereas it reduced renal cortical apoptosis and nitric oxide production. Notably, indomethacin did not affect inflammation parameters in the kidneys (e.g., monocyte chemoattractant protein-1, ED1+ cells). On the other hand, probenecid blocked the indomethacin-induced restoration of Oat1/3 and moreover abrogated all beneficial effects. Our study indicates that the beneficial effect of low-dose indomethacin in iAKI is not due to its anti-inflammatory potency, but in contrast to its restoration of Oat1/3 expression and/or general renal function. Inhibition of proximal tubular indomethacin uptake abrogates the beneficial effect of indomethacin by resetting the PGE2-mediated Oat1/3 impairment, thus reestablishing renal damage. This provides evidence for a mechanistic effect of Oat1/3 in a new model of the induction of renal damage after iAKI.

Quantification of the sensitivity range in neutron dark-field imaging.

In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons.

Macrophage capping protein CapG is a putative oncogene involved in migration and invasiveness in ovarian carcinoma.

The actin binding protein CapG modulates cell motility by interacting with the cytoskeleton. CapG is associated with tumor progression in different nongynecologic tumor entities and overexpression in breast cancer cell lines correlates with a more invasive phenotype in vitro. Here, we report a significant CapG overexpression in 18/47 (38%) of ovarian carcinomas (OC) analyzed by qRealTime-PCR analyses. Functional analyses in OC cell lines through siRNA mediated CapG knockdown and CapG overexpression showed CapG-dependent cell migration and invasiveness. A single nucleotide polymorphism rs6886 inside the CapG gene was identified, affecting a CapG phosphorylation site and thus potentially modifying CapG function. The minor allele frequency (MAF) of SNP rs6886 (c.1004A/G) was higher and the homozygous (A/A, His335) genotype was significantly more prevalent in patients with fallopian tube carcinomas (50%) as in controls (10%). With OC being one of the most lethal cancer diseases, the detection of novel biomarkers such as CapG could reveal new diagnostic and therapeutic targets. Moreover, in-depth analyses of SNP rs6886 related to FTC and OC will contribute to a better understanding of carcinogenesis and progression of OC.

Nitric oxide-induced regulation of renal organic cation transport after renal ischemia-reperfusion injury.

Renal organic cation transporters are downregulated by nitric oxide (NO) in rat endotoxemia. NO generated by inducible NO synthase (iNOS) is substantially increased in the renal cortex after renal ischemia-reperfusion (I/R) injury. Therefore, we investigated the effects of iNOS-specific NO inhibition on the expression of the organic cation transporters rOct1 and rOct2 (Slc22a1 and Slc22a2, respectively) after I/R injury both in vivo and in vitro. In vivo, N(6)-(1-iminoethyl)-L-lysine (L-NIL) completely inhibited NO generation after I/R injury. Moreover, L-NIL abolished the ischemia-induced downregulation of rOct1 and rOct2 as determined by qPCR and Western blotting. Functional evidence was obtained by measuring the fractional excretion (FE) of the endogenous organic cation serotonin. Concordant with the expression of the rate-limiting organic cation transporter, the FE of serotonin decreased after I/R injury and was totally abolished by L-NIL. In vitro, ischemia downregulated both rOct1 and rOct2, which were also abolished by L-NIL; the same was true for the uptake of the organic cation MPP. We showed that renal I/R injury downregulates rOct1 and rOct2, which is most probably mediated via NO. In principle, this may be an autocrine effect of proximal tubular epithelial cells. We conclude that rOct1, or rOct1 and rOct2 limit the rate of the renal excretion of serotonin.

Comprehensive array CGH of normal karyotype myelodysplastic syndromes reveals hidden recurrent and individual genomic copy number alterations with prognostic relevance.

About 40% of patients with myelodysplastic syndromes (MDSs) present with a normal karyotype, and they are facing different courses of disease. To advance the biological understanding and to find molecular prognostic markers, we performed a high-resolution oligonucleotide array study of 107 MDS patients (French American British) with a normal karyotype and clinical follow-up through the Duesseldorf MDS registry. Recurrent hidden deletions overlapping with known cytogenetic aberrations or sites of known tumor-associated genes were identified in 4q24 (TET2, 2x), 5q31.2 (2x), 7q22.1 (3x) and 21q22.12 (RUNX1, 2x). One patient with a 7q22.1 deletion had an additional 5q31.2 deletion of the acute myeloid leukemia/MDS region, the smallest deletion identified so far and including the putative tumor suppressor (ts) genes, EGR1 and CTNNA1. One TET2 deletion was homozygous and one heterozygous, with a missense mutation in the remaining allele, further supporting its role as a ts gene. Besides these recurrent alterations, additional individual imbalances were found in 34 cases; in total, 42/107 (39%) cases had genomic imbalances. These patients had an inferior survival as compared with the rest of the patients (P=0.002). This study emphasizes the heterogeneity of MDS, but points to interesting genes that may have diagnostic and prognostic impact.

SEPT9 gene sequencing analysis reveals recurrent mutations in hereditary neuralgic amyotrophy.

BACKGROUND: Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant disorder that manifests as recurrent, episodic, painful brachial neuropathies. A gene for HNA maps to chromosome 17q25.3 where mutations in SEPT9, encoding the septin-9 protein, have been identified. OBJECTIVE: To determine the frequency and type of mutations in the SEPT9 gene in a new cohort of 42 unrelated HNA pedigrees. METHODS: DNA sequencing of all exons and intron-exon boundaries for SEPT9 was carried out in an affected individual in each pedigree from our HNA cohort. Genotyping using microsatellite markers spanning the SEPT9 gene was also used to identify pedigrees with a previously reported founder haplotype. RESULTS: Two missense mutations were found: c.262C>T (p.Arg88Trp) in seven HNA pedigrees and c.278C>T (p.Ser93Phe) in one HNA pedigree. Sequencing of other known exons in SEPT9 detected no additional disease-associated mutations. A founder haplotype, without defined mutations in SEPT9, was present in seven pedigrees. CONCLUSIONS: We provide further evidence that mutation of the SEPT9 gene is the molecular basis of some cases of hereditary neuralgic amyotrophy (HNA). DNA sequencing of SEPT9 demonstrates a restricted set of mutations in this cohort of HNA pedigrees. Nonetheless, sequence analysis will have an important role in mutation detection in HNA. Additional techniques will be required to find SEPT9 mutations in an HNA founder haplotype and other pedigrees.

Downregulation of organic anion transporters OAT1 and OAT3 correlates with impaired secretion of para-aminohippurate after ischemic acute renal failure in rats.

Ischemic acute renal failure (iARF) was described to reduce renal extraction of the organic anion para-aminohippurate (PAH) in humans. The rate-limiting step of renal organic anion secretion is its basolateral uptake into proximal tubular cells. This process is mediated by the organic anion transporters OAT1 and OAT3, which both have a broad spectrum of substrates including a variety of pharmaceutics and toxins. Using a rat model of iARF, we investigated whether impairing the secretion of the organic anion PAH might be associated with downregulation of OAT1 or OAT3. Inulin and PAH clearance was determined starting from 6 up to 336 h after ischemia-reperfusion (I/R) injury. Net secretion of PAH was calculated and OAT1 as well as OAT3 expression was analyzed by RT-PCR and Western blotting. Inulin and PAH clearance along with PAH net secretion were initially diminished after I/R injury with a gradual recovery during follow-up. This initial impairment after iARF was accompanied by decreased mRNA and protein levels of OAT1 and OAT3 in clamped animals compared with sham-operated controls. In correlation to the improvement of kidney function, both mRNA and protein levels of OAT1 and OAT3 were upregulated during the follow-up. Thus decreased expression of OAT1 and OAT3 is sufficient to explain the decline of PAH secretion after iARF. As a result, this may have substantial impact on excretion kinetics and half-life of organic anions. As a consequence, the biological effects of a variety of organic anions may be affected after iARF.

Aberrant methylation of the Wnt antagonist SFRP1 in breast cancer is associated with unfavourable prognosis.

The canonical Wnt signalling pathway plays a key role during embryogenesis and defects in this pathway have been implicated in the pathogenesis of various types of tumours, including breast cancer. The gene for secreted frizzled-related protein 1 (SFRP1) encodes a soluble Wnt antagonist and is located in a chromosomal region (8p22-p12) that is often deleted in breast cancer. In colon, lung, bladder and ovarian cancer SFRP1 expression is frequently inactivated by promoter methylation. We have previously shown that loss of SFRP1 protein expression is a common event in breast tumours that is associated with poor overall survival in patients with early breast cancer. To investigate the cause of SFRP1 loss in breast cancer, we performed mutation, methylation and expression analysis in human primary breast tumours and breast cell lines. No SFRP1 gene mutations were detected. However, promoter methylation of SFRP1 was frequently observed in both primary breast cancer (61%, n=130) and cell lines analysed by methylation-specific polymerase chain reaction (MSP). We found a tight correlation (P<0.001) between methylation and loss of SFRP1 expression in primary breast cancer tissue. SFRP1 expression was restored after treatment of tumour cell lines with the demethylating agent 5-aza-2'-deoxycytidine. Most interestingly, SFRP1 promoter methylation was an independent factor for adverse patient survival in Kaplan-Meier analysis. Our results indicate that promoter hypermethylation is the predominant mechanism of SFRP1 gene silencing in human breast cancer and that SFRP1 gene inactivation in breast cancer is associated with unfavourable prognosis.

The influence of hormones on CD44 expression in endometrial and breast carcinomas.

The expression of distinct variant isoforms of the cell surface glycoprotein CD44 (CD44v) has been found to be associated with metastatic potential of rodent adenocarcinoma cells and with an altered prognosis in several types of human cancer. In hormone-dependent gynecological cancers, different CD44v expression patterns have been observed. The influence of ovarian steroid hormones and their antagonists on CD44v expression is still unclear, since there are only retrospective correlation studies so far. Therefore, we examined the CD44 mRNA expression in a standardized stimulation experiment in a number of breast and endometrial carcinoma cell lines varying in estrogen receptor (ER) status. Higher CD44 overall expression was observed in ER positive endometrial and breast carcinoma cell lines when compared to corresponding ER negative cell lines. The number and composition of alternatively spliced isoforms showed no clear correlation to the ER expression status. Three CD44v isoforms were detected in all cell lines expressing CD44v, two of which have not been reported previously in normal endometrial cells. These isoforms may have specific functions in this type of carcinoma. In the second part of the study, the influence of (anti-) hormones on CD44 expression in endometrial carcinoma cell lines was examined. CD44 overall expression showed an increase when the cells were grown in medium containing fetal calf serum (FCS) as compared to cells maintained in medium-free of FCS. CD44 expression was transiently increased by estradiol (1 h). The CD44 splice pattern of endometrial cancer cell lines RL95-2 and Hec-1-A, after treatment with (anti-) hormones showed constant and high expression rates for distinct CD44v-isoforms such as CD44E (CD44v8-v10). Only certain weakly expressed isoforms changed their expression level during the experimental period, but no direct correlation to hormone treatment was observed. In conclusion, estradiol or FCS increase CD44 overall expression, but there seems to be no direct influence of ovarian steroid hormones on the CD44v splice machinery in endometrial carcinoma cell lines.

Resistance to CD95-mediated apoptosis in breast cancer is not due to somatic mutation of the CD95 gene.

Resistance to CD95 (Apo-1/Fas)-mediated apoptosis is a typical feature of breast cancer cells. Recent studies identified deleterious mutations of the CD95 gene not only in a variety of B cell lymphomas but also in a number of solid tumor entities. Therefore, we amplified and sequenced selected regions of the CD95 gene from 48 breast cancer cases and 10 cell lines but no mutation was found. In the presence of both polymorphic alleles, loss of heterozygosity was excluded in 27 informative cases. We conclude, that relevant somatic mutations of the CD95 gene occur, if at all, at a low frequency and are not the primary cause for resistance to CD95-mediated apoptosis in breast cancer.

Characterization of SWI/SNF protein expression in human breast cancer cell lines and other malignancies.

Organization of genomic DNA into chromatin aids in the regulation of gene expression by limiting access to transcriptional machinery. The SWI/SNF family of complexes, which are conserved from yeast to humans, are ATP-dependent chromatin-remodeling enzymes required for the transcription of a number of genes in yeast. In humans, the gene encoding the BAF47/hSNF5 subunit of the complex, located at 22q11.2, has been found to be mutated in a number of human tumors including rhabdoid, rhabdomyosarcoma, chronic myeloid leukemia, and CNS tumors such as medulloblastomas and choroid plexus carcinomas. In addition, loss of heterozygosity (LOH) has been reported for the BAF47 region in breast and liver cancer. LOH has also been reported in breast and ovarian cancer within 17q12-25, a gene-rich area including BRCA1, BAF60B, and BAF57. Interestingly, the gene encoding the BAF155/hSWI3 subunit of the complex maps to 3p21-p23, an area of chromosomal deletion seen in a number of human adenocarcinomas including breast, kidney, pancreas, and ovary. To look for abnormalities in these proteins as well as the SWI/SNF complex in general, we have determined the protein status of core human SWI/SNF components BAF170, BAF155, BAF57, BAF53a, and BAF47 in 21 breast cell lines. The complex status in other human tumor cell lines of various tissue types was also examined. We also determined the protein status of the human SWI2 homologues, hBRM/SWI2alpha and BRG1/SWI2beta as well as two other proteins found in human SWI/SNF complexes, BAF180 and BAF250. In this study, we identified the first cell line negative for the BAF57 protein as well as a pancreatic carcinoma cell line negative for both the BRG-1 and hBRM proteins.

The Satz-Mogel short form of the Wechsler Adult Intelligence Scale--revised: effects of global mental status and age on test-retest reliability.

Abbreviated versions of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) have been developed as time saving devices that provide accurate estimates of overall level of general intellectual functioning while decreasing test administration time. The Satz-Mogel short form of the WAIS-R has received substantial attention in the literature as an accurate measure of intellectual functions when compared with the Full WAIS-R. However, most studies comparing the Satz-Mogel version to the Full WAIS-R have only provided correlational analyses. Our study was an attempt to apply a more rigorous statistical methodology in determining if the Full WAIS-R and abbreviated versions are equivalent. We explored the impact of level of global mental status and age on the Satz-Mogel version. Although the two forms of the test correlated highly, repeated measures design indicated significant differences between Satz-Mogel and Full WAIS-R when participants were divided into groups based on level of global impairment and age. Our results suggest that the Satz-Mogel version of the test may not be equivalent to the full WAIS-R and is likely to misrepresent a patient's level of intellectual functioning, particularly for patients with progressive degenerative conditions. The implications of applying Satz-Mogel scoring to the Wechsler Adult Intelligence Scale-III (WAIS-III) are discussed.

Alteration of hSNF5/INI1/BAF47 detected in rhabdoid cell lines and primary rhabdomyosarcomas but not Wilms' tumors.

The organization of genomic DNA into chromatin aids in the regulation of gene expression by limiting the access of transcriptional binding domains. The SWI/SNF family of chromatin-remodeling complexes, which are conserved from yeast to humans, open the chromatin to facilitate the transcriptional machinery to access their targets. The gene encoding the BAF47/hSNF5 subunit of the complex has been found mutated in both rhabdoid cell lines and in primary rhabdoid tumors. Since the pediatric tumors rhabdomyosarcoma (RMS) and Wilms' tumor (WT) share a similar genetic link with rhabdoid tumors, it was hypothesized that they may also show alterations of the BAF47 gene. Using primary tumors, the BAF47 protein was detected in all WT but less than 75% of the RMS tested. In cell lines, the BAF47 protein was missing in all rhabdoid cell lines and one RMS cell line. Analysis of sample DNA displayed either a mutation or deletion of the BAF47 gene in all samples negative for the protein. Several other subunits of the human SWI/SNF complex, including BRG1 which is the subunit directly interacting with the Rb tumor suppressor gene, were detected in all tumor samples. Alteration of BAF47 may be a genetic marker associated with the poor prognosis seen in all rhabdoid tumors but only some RMS.

CD95 ligand expression in dedifferentiated breast cancer.

CD95 ligand expression has been observed in various malignancies. Studying the CD95 ligand (CD95L) and receptor (CD95) system in eight non-malignant mammary tissues and 40 breast cancer tissues, mRNA and protein expression was determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescence. mRNA levels of CD95L correlated positively (r=0.90; p< 0.01) and transmembrane CD95 inversely (r=-0.88; p< 0.01) with histopathological grading of the breast tumours: CD95L mRNA levels were low in adenomas, but increased by 20-fold in grade I, 120-fold in grade II, and 310-fold in grade III breast cancer. In contrast, CD95 mRNA levels were low in high-grade carcinomas, but high in benign mammary tissues. Since CD95L acts as an efficient inducer of apoptosis in CD95(+) cells, apoptotic cells were identified on the tissue sections. Tumour-infiltrating lymphocytes and stromal cells in close proximity to CD95L-expressing breast cancer underwent apoptosis. As a functional test, CD95(+) target cells were cultured on breast cancer tissue sections. The target cells underwent apoptosis when cultured on breast cancer sections, but could be rescued when CD95L was specifically blocked by a CD95-Fc fusion molecule. The data suggest an inverse regulation of CD95 ligand and receptor expression during dedifferentiation of breast cancer. Killing of bystander cells by the CD95L-expressing breast tumour could be involved in tissue invasion.