Horst Bürger

Common Adult Stem Cells in the Human Breast Give Rise to Glandular and Myoepithelial Cell Lineages: A New Cell Biological Concept

Breast biology and pathology are currently shaped by the two-cell concept that recognizes only glandular and myoepithelial cells. In the present study, we have visualized a previously unidentified cell population within the epithelial compartment of the breast, which displays the phenotypic characteristics of a committed stem cell.Immunofluorescence double labeling with digital image processing and Western blotting were applied to normal breast tissue as well as to noninvasive and invasive breast cancers using antibodies to basal cytokeratin 5 (Ck5), glandular cytokeratins 8/18 (Ck8/18/19), and smooth muscle α-actin (SMA) as markers for myoepithelial cells (SMA).A distinct population of cells was identified that expressed Ck5 in the absence of Ck8/18/19 or SMA. These cells differentiate toward glandular epithelial or myoepithelial Ck5-negative end cells passing through either Ck5/Ck8/18/19 or Ck5/SMA-positive intermediates. Our experiments clearly demonstrate a precursor or committed stem cell function of the Ck5-positive cell that is responsible for regeneration of the human adult breast epithelium. However, the observation that the vast majority of breast cancers display the glandular epithelial immunophenotype strongly suggests that the neoplastic cells derive from a late stage of the glandular epithelial differentiation pathway. The significance of this new cell biological model is that it might serve as a tool to unravel the regulatory mechanisms that govern regeneration and abnormal proliferation of breast epithelium at the cellular level.

Twist Overexpression Induces In vivo Angiogenesis and Correlates with Chromosomal Instability in Breast Cancer

Aggressive cancer phenotypes are a manifestation of many different genetic alterations that promote rapid proliferation and metastasis. In this study, we show that stable overexpression of Twist in a breast cancer cell line, MCF-7, altered its morphology to a fibroblastic-like phenotype, which exhibited protein markers representative of a mesenchymal transformation. In addition, it was observed that MCF-7/Twist cells had increased vascular endothelial growth factor (VEGF) synthesis when compared with empty vector control cells. The functional changes induced by VEGF in vivo were analyzed by functional magnetic resonance imaging (MRI) of MCF-7/Twist-xenografted tumors. MRI showed that MCF-7/Twist tumors exhibited higher vascular volume and vascular permeability in vivo than the MCF-7/vector control xenografts. Moreover, elevated expression of Twist in breast tumor samples obtained from patients correlated strongly with high-grade invasive carcinomas and with chromosome instability, particularly gains of chromosomes 1 and 7. Taken together, these results show that Twist overexpression in breast cancer cells can induce angiogenesis, correlates with chromosomal instability, and promotes an epithelial-mesenchymal-like transition that is pivotal for the transformation into an aggressive breast cancer phenotype.

Modulation of the Osteosarcoma Expression Phenotype by MicroRNAs

Background Osteosarcomas are the most common primary malignant tumors of bone and show multiple and complex genomic aberrations. miRNAs are non-coding RNAs capable of regulating gene expression at the post transcriptional level, and miRNAs and their target genes may represent novel therapeutic targets or biomarkers for osteosarcoma. In order to investigate the involvement of miRNAs in osteosarcoma development, global microarray analyses of a panel of 19 human osteosarcoma cell lines was performed. Principal findings We identified 177 miRNAs that were differentially expressed in osteosarcoma cell lines relative to normal bone. Among these, miR-126/miR-126*, miR-142-3p, miR-150, miR-223, miR-486-5p and members of the miR-1/miR-133a, miR-144/miR-451, miR-195/miR-497 and miR-206/miR-133b clusters were found to be downregulated in osteosarcoma cell lines. All miRNAs in the paralogous clusters miR-17-92, miR-106b-25 and miR-106a-92 were overexpressed. Furthermore, the upregulated miRNAs included miR-9/miR-9*, miR-21*, miR-31/miR-31*, miR-196a/miR-196b, miR-374a and members of the miR-29 and miR-130/301 families. The most interesting inversely correlated miRNA/mRNA pairs in osteosarcoma cell lines included miR-9/TGFBR2 and miR-29/p85α regulatory subunit of PI3K. PTEN mRNA correlated inversely with miR-92a and members of the miR-17 and miR-130/301 families. Expression profiles of selected miRNAs were confirmed in clinical samples. A set of miRNAs, miR-1, miR-18a, miR-18b, miR-19b, miR-31, miR-126, miR-142-3p, miR-133b, miR-144, miR-195, miR-223, miR-451 and miR-497 was identified with an intermediate expression level in osteosarcoma clinical samples compared to osteoblasts and bone, which may reflect the differentiation level of osteosarcoma relative to the undifferentiated osteoblast and fully differentiated normal bone. Significance: This study provides an integrated analysis of miRNA and mRNA in osteosarcoma, and gives new insight into the complex genetic mechanisms of osteosarcoma development and progression.

Chromosomal aberrations associated with invasion in papillary superficial bladder cancer

Non‐invasive and invasive papillary transitional cell carcinomas of stages pTa and pT1 represent the first steps of tumour progression in bladder cancer. In order to analyse different chromosomal alterations of pTa and pT1 superficial bladder cancer, 46 tumour specimens were examined by comparative genomic hybridization (CGH). Losses of chromosome 9 material (11/20) and gains of chromosome 17 material (6/20) were frequently found in pTa tumours. Stage pT1 tumours were characterized by gains of chromosome 1q (14/26; including amplification at 1q21–q24 in three cases) and chromosome 17 material (15/26), as well as by losses of 11p (15/26) and 11q (13/26). Other loci frequently showing losses in pT1 tumours were 2q (9/26), 4q (10/26), 5q (9/26), 8p (10/26), 9p (9/26), 9q (12/26), 10q (8/26), 17p (7/26), and 18q (8/26). Amplifications were detected at 8q21/22, 5q21, 7q36, 10p14, 10p12, 10q25, 12q12, and 12q14. The most striking differences between grade 2 pTa and pT1 tumours were gains of 1q (P<0·01) and losses at 2q (P<0·025), 10q (P<0·05), 11p (P<0·01), 11q (P<0·01), and 17p (P<0·05), as well as the total number of aberrations (pTa grade 2: 4·1; pT1 grade 2: 8·6 aberrations per tumour). These data show characteristic chromosomal aberrations associated with invasion in superficial bladder cancer.

Tumor-Infiltrating Macrophages Are Associated with Metastasis Suppression in High-Grade Osteosarcoma: A Rationale for Treatment with Macrophage Activating Agents

Purpose: High-grade osteosarcoma is a malignant primary bone tumor with a peak incidence in adolescence. Overall survival (OS) of patients with resectable metastatic disease is approximately 20%. The exact mechanisms of development of metastases in osteosarcoma remain unclear. Most studies focus on tumor cells, but it is increasingly evident that stroma plays an important role in tumorigenesis and metastasis. We investigated the development of metastasis by studying tumor cells and their stromal context. Experimental Design: To identify gene signatures playing a role in metastasis, we carried out genome-wide gene expression profiling on prechemotherapy biopsies of patients who did (n = 34) and patients who did not (n = 19) develop metastases within 5 years. Immunohistochemistry (IHC) was performed on pretreatment biopsies from 2 additional cohorts (n = 63 and n = 16) and corresponding postchemotherapy resections and metastases. Results: A total of 118/132 differentially expressed genes were upregulated in patients without metastases. Remarkably, almost half of these upregulated genes had immunological functions, particularly related to macrophages. Macrophage-associated genes were expressed by infiltrating cells and not by osteosarcoma cells. Tumor-associated macrophages (TAM) were quantified with IHC and associated with significantly better overall survival (OS) in the additional patient cohorts. Osteosarcoma samples contained both M1- (CD14/HLA-DRα positive) and M2-type TAMs (CD14/CD163 positive and association with angiogenesis). Conclusions: In contrast to most other tumor types, TAMs are associated with reduced metastasis and improved survival in high-grade osteosarcoma. This study provides a biological rationale for the adjuvant treatment of high-grade osteosarcoma patients with macrophage activating agents, such as muramyl tripeptide. Clin Cancer Res; 17(8); 2110–9. ©2011 AACR.

Soft tissue reconstruction of megaprostheses using a trevira tube

In soft tissue reconstruction of megaprostheses, the reattachment of soft tissue and joint capsules is essential. Sixty-nine megaprostheses were implanted and a trevira tube was applied to support reconstruction of the capsule and soft tissue. In cases of proximal femur replacement (33 patients), total femur replacement (five patients), and proximal humerus replacement (16 patients), the trevira tube allowed for reconstruction of the capsule and refixation of the muscles and helped to minimize dislocation. In cases of proximal tibia replacement (seven patients), arthrodesis of the knee (three patients), total knee replacement (two patients), and distal femur replacement (three patients), the trevira tube allowed for attachment of muscle flaps and extensor apparatus. Dislocation was observed in two of 54 patients who had proximal femur replacements. No dislocation was observed in patients with a total femur endoprosthesis or a proximal humerus endoprosthesis. The trevira tube also was used to attach the gastrocnemius muscle in patients with a proximal tibia endoprosthesis and to reattach the rotator cuff in patients with a proximal humerus prosthesis. There was no significant increase in the rate of infection. The histopathologic findings in six patients showed tissue ingrowth into the tube.

Dose intensity of chemotherapy for osteosarcoma and outcome in the Cooperative Osteosarcoma Study Group (COSS) trials

The prognostic relevance of dose intensity in the treatment of osteosarcoma is still under discussion. The aim of this study was to investigate whether higher dose intensities of chemotherapy correlated with better outcomes.

Identification of Osteosarcoma Driver Genes by Integrative Analysis of Copy Number and Gene Expression Data

High‐grade osteosarcoma is a tumor with a complex genomic profile, occurring primarily in adolescents with a second peak at middle age. The extensive genomic alterations obscure the identification of genes driving tumorigenesis during osteosarcoma development. To identify such driver genes, we integrated DNA copy number profiles (Affymetrix SNP 6.0) of 32 diagnostic biopsies with 84 expression profiles (Illumina Human‐6 v2.0) of high‐grade osteosarcoma as compared with its putative progenitor cells, i.e., mesenchymal stem cells (n = 12) or osteoblasts (n = 3). In addition, we performed paired analyses between copy number and expression profiles of a subset of 29 patients for which both DNA and mRNA profiles were available. Integrative analyses were performed in Nexus Copy Number software and statistical language R. Paired analyses were performed on all probes detecting significantly differentially expressed genes in corresponding LIMMA analyses. For both nonpaired and paired analyses, copy number aberration frequency was set to >35%. Nonpaired and paired integrative analyses resulted in 45 and 101 genes, respectively, which were present in both analyses using different control sets. Paired analyses detected >90% of all genes found with the corresponding nonpaired analyses. Remarkably, approximately twice as many genes as found in the corresponding nonpaired analyses were detected. Affected genes were intersected with differentially expressed genes in osteosarcoma cell lines, resulting in 31 new osteosarcoma driver genes. Cell division related genes, such as MCM4 and LATS2, were overrepresented and genomic instability was predictive for metastasis‐free survival, suggesting that deregulation of the cell cycle is a driver of osteosarcomagenesis.

Telomerase Is a Highly Sensitive and Specific Molecular Marker in Fine-Needle Aspirates of Breast Lesions

PURPOSE Telomerase has been detected in a majority of human malignant tumors, making telomerase activity (TA) one key difference between mortal and immortal cells. In this study, we evaluated in blind-trial fashion the association of TA with cytologic and final clinical/pathologic diagnosis in fine-needle aspirates (FNAs) of breast lesions. MATERIALS AND METHODS In 172 FNAs, including 80 samples that were cytologically malignant, 18 that were atypical but not diagnostic for malignancy, and 74 that were cytologically benign, TA was determined by a modified nonradioactive telomeric repeat amplification protocol (TRAP) assay. Final diagnosis was made by pathologic examination of follow-up surgical material available for all the cytologically malignant samples, a majority of the cytologically atypical samples, and a portion of the cytologically benign samples. RESULTS TA was detected in 85 of 172 samples. Comparison of the cytologic and histologic diagnoses with TA showed that 80 of 87 samples from patients with breast cancer were telomerase-positive, resulting in a sensitivity of 92%. TA was found in four of five FNAs from carcinomas that were considered cytologically atypical but not diagnostic for malignancy. Eighty of 85 samples from patients with benign breast lesions were telomerase-negative, revealing a specificity of 94%. The five positive cases in this group were all fibroadenomas with low TA. Among the 18 cases with a cytologic diagnosis of atypia, there was a strong positive relationship between TRAP findings and histologic diagnosis. CONCLUSION The detection of TA in FNAs of breast lesions is a highly sensitive and specific marker of malignancy and may be used as an adjunct in cases with an equivocal cytologic diagnosis.

Patterns of chromosomal aberrations in urinary bladder tumours and adjacent urothelium.

Bladder cancer is often characterized by recurrent and multifocal growth, and tumours are frequently accompanied by precancerous alterations of the surrounding urothelium. These findings have led to the hypothesis that cells from areas of genetically aberrant but morphologically non‐cancerous or even unremarkable mucosa may be the source of bladder carcinomas. Fluorescence in situ hybridization (FISH) was performed using ten probes targeting five different chromosomes that are known to be frequently altered in bladder cancer (centromere 1, 8, 9, 11, 17 and 1p36, 8p23, 9p21, 11q13, 17p13) on paraffin‐embedded tissue sections of 11 superficial bladder cancers. Copy number changes of the tumours were compared to those in the urothelium adjacent to the tumour. Eleven of 11 (100%) tumours and eight of 11 (73%) samples of adjacent urothelium showed copy number changes of at least one chromosome. The occurrence of similar patterns of chromosomal aberrations in the tumours and their associated urothelium supports the hypothesis of a clonal relationship. It is concluded that FISH analysis targeting five different chromosomes is more sensitive than conventional histology for distinguishing between neoplastic and normal cells of the urothelium. Copyright