Ellen C. Obermann

The nanomechanical signature of breast cancer.

Cancer initiation and progression follow complex molecular and structural changes in the extracellular matrix and cellular architecture of living tissue. However, it remains poorly understood how the transformation from health to malignancy alters the mechanical properties of cells within the tumour microenvironment. Here, we show using an indentation-type atomic force microscope (IT-AFM) that unadulterated human breast biopsies display distinct stiffness profiles. Correlative stiffness maps obtained on normal and benign tissues show uniform stiffness profiles that are characterized by a single distinct peak. In contrast, malignant tissues have a broad distribution resulting from tissue heterogeneity, with a prominent low-stiffness peak representative of cancer cells. Similar findings are seen in specific stages of breast cancer in MMTV-PyMT transgenic mice. Further evidence obtained from the lungs of mice with late-stage tumours shows that migration and metastatic spreading is correlated to the low stiffness of hypoxia-associated cancer cells. Overall, nanomechanical profiling by IT-AFM provides quantitative indicators in the clinical diagnostics of breast cancer with translational significance.

Frequent genetic alterations in flat urothelial hyperplasias and concomitant papillary bladder cancer as detected by CGH, LOH, and FISH analyses.

Flat urothelial hyperplasia, defined as markedly thickened urothelium without cytological atypia, is regarded in the new WHO classification as a urothelial lesion without malignant potential. Frequent deletions of chromosome 9 detected by fluorescence in situ hybridization (FISH) have been previously reported in flat urothelial hyperplasias found in patients with papillary bladder cancer. Using comparative genomic hybridization (CGH) and microsatellite analysis, these hyperplasias and concomitant papillary tumours of the same patients were screened for other genetic alterations to validate and extend the previous findings. Eleven flat hyperplasias detected by 5‐ALA‐induced fluorescence endoscopy and ten papillary urothelial carcinomas (pTaG1–G2) from ten patients were investigated. After microdissection, the DNA of the lesions was pre‐amplified using whole genome amplification (I‐PEP‐PCR). Loss of heterozygosity (LOH) analyses were performed with five microsatellite markers at chromosomes 9p, 9q, and 17p. CGH was performed using standard protocols. In 6 of 11 hyperplasias and 7 of 10 papillary tumours, deletions at chromosome 9 were simultaneously shown by FISH, LOH, and CGH analyses. There was a good correlation between FISH, LOH, and CGH analyses, with identical results in 6 of 10 patients. In addition to deletions at chromosome 9, further genetic alterations were detected by CGH in 9 of 10 investigated hyperplasias, including changes frequently found in invasive papillary bladder cancer (loss of chromosomes 2q, 4, 8p, and 11p; gain of chromosome 17; and amplification at 11q12q13). There was considerable genetic heterogeneity between hyperplasias and papillary tumours, but a clonal relationship was suggested by LOH and/or CGH analyses in 5 of 10 cases. These data support the hypothesis that flat urothelial hyperplasias can display many genetic alterations commonly found in bladder cancer and could therefore be an early neoplastic lesion in the multistep development of invasive urothelial carcinoma. Copyright

DNA replication licensing in somatic and germ cells

The DNA replication (or origin) licensing system ensures precise duplication of the genome in each cell cycle and is a powerful regulator of cell proliferation in metazoa. Studies in yeast, Drosophila melanogaster and Xenopus laevis have characterised the molecular machinery that constitutes the licensing system, but it remains to be determined how this important evolutionary conserved pathway is regulated in Homo sapiens. We have investigated regulation of the origin licensing factors Cdc6, Cdt1, Mcm2 and Geminin in human somatic and germ cells. Cdc6 and Cdt1 play an essential role in DNA replication initiation by loading the Mcm2-7 complex, which is required for unwinding the DNA helix, onto chromosomal origins. Geminin is a repressor of origin licensing that blocks Mcm2-7 loading onto origins. Our studies demonstrate that Cdc6, Cdt1 and Mcm2 play a central role in coordinating growth during the proliferation-differentiation switch in somatic self-renewing systems and that Cdc6 expression is rate-limiting for acquisition of replication competence in primary oocytes. In striking contrast, we show that proliferation control during male gametogenesis is not linked to Cdc6 or Mcm2, but appears to be coordinated by the negative regulator Geminin with Cdt1 becoming rate-limiting in late prophase. Our data demonstrate a striking sexual dimorphism in the mechanisms repressing origin licensing and preventing untimely DNA synthesis during meiosis I, implicating a pivotal role for Geminin in maintaining integrity of the male germline genome.

Detection of ALK-Positive Non-Small-Cell Lung Cancers on Cytological Specimens High Accuracy of Immunocytochemistry with the 5A4 Clone

Introduction: Lung cancer is often diagnosed by cytology, necessitating predictive molecular marker analyses on cytological specimens. The gold standard for detection of predictive anaplastic lymphoma kinase (ALK)-rearrangements is fluorescence in situ hybridization (FISH), but FISH is both expensive and often challenging to interpret. The aim of our study was to investigate the accuracy of ALK immunocytochemistry (ICC) on cytological specimens of non–small-cell lung cancers (NSCLCs). Methods: Forty-one cytological specimens with available ALK FISH results were retrospectively analyzed with the 5A4 monoclonal antibody (Novocastra; Leica Biosystems) on a fully automated slide stainer. The specimens were enriched for ALK FISH-positive NSCLCs (14 of 41; 34.1%). Evaluation of the ICC staining was performed blinded to the FISH results. The staining intensity and the percentage of stained cancer cells were recorded. Any ICC staining was regarded as a positive result. The ALK ICC results were compared with the FISH results. In case of a discrepancy the ICC-stained slide and the FISH signals were reviewed. Results: ICC was evaluable on 40 of 41 specimens. Fifteen of 40 NSCLCs (37.5%) were ALK ICC-positive, with staining of the majority of cancer cells (median 100%; mean 82.3%). Twelve of the ICC-positive NSCLCs (80.0%) showed an intense staining (3+). Compared with the ALK FISH results, only one NSCLC was false-negative, and one false-positive by ICC, respectively. The sensitivity, specificity, and positive and negative predictive values for ALK ICC compared with ALK FISH were 93.3%, 96.0%, 93.3%, and 96%, respectively. Conclusion: ALK ICC is highly accurate for detecting ALK-rearranged NSCLCs.

Aberrations of the MYC gene in unselected cases of diffuse large B-cell lymphoma are rare and unpredictable by morphological or immunohistochemical assessment.

Diffuse large B-cell lymphomas (DLBCL) with aberrations of MYC probably represent a distinct clinicopathological entity following an aggressive course. Their incidence in unselected DLBCL collectives is debatable and the identification of such cases may be difficult. Therefore, the molecular epidemiology of MYC aberrations in DLBCL and whether they can be predicted by morphology and immunohistochemistry were studied on tissue microarrays containing 333 cases. Evaluation of MYC by fluorescence in situ hybridisation was successful in 220/333 (66%) cases. 9/220 (4%) cases showed MYC breaks. Re-evaluation of these tumours did not show any specific morphological and/or immunohistochemical features. The median survival time was 9 months for the respective patients, as opposed to 80 for patients without MYC breaks. The presence of MYC breaks in DLBCL cannot be reliably predicted by conventional methods. Since such patients might profit from different forms of treatment, routine testing of all DLBCL for MYC aberrations is suggested.

Role of KCNMA1 in breast cancer

KCNMA1 encodes the α-subunit of the large conductance, voltage and Ca2+-activated (BK) potassium channel and has been reported as a target gene of genomic amplification at 10q22 in prostate cancer. To investigate the prevalence of the amplification in other human cancers, the copy number of KCNMA1 was analyzed by fluorescence-in-situ-hybridization (FISH) in 2,445 tumors across 118 different tumor types. Amplification of KCNMA1 was restricted to a small but distinct fraction of breast, ovarian and endometrial cancer with the highest prevalence in invasive ductal breast cancers and serous carcinoma of ovary and endometrium (3–7%). We performed an extensive analysis on breast cancer tissue microarrays (TMA) of 1,200 tumors linked to prognosis. KCNMA1 amplification was significantly associated with high tumor stage, high grade, high tumor cell proliferation, and poor prognosis. Immunofluorescence revealed moderate or strong KCNMA1 protein expression in 8 out of 9 human breast cancers and in the breast cancer cell line MFM223. KCNMA1-function in breast cancer cell lines was confirmed by whole-cell patch clamp recordings and proliferation assays, using siRNA-knockdown, BK channel activators such as 17ß-estradiol and the BK-channel blocker paxilline. Our findings revealed that enhanced expression of KCNMA1 correlates with and contributes to high proliferation rate and malignancy of breast cancer.

CD8+ T cells Reactive to Survivin Antigen in Patients with Multiple Myeloma

Purpose: Survivin is a member of the inhibitors of apoptosis family and is overexpressed in different types of malignancies. Cytotoxic T cells recognizing survivin epitopes can be elicited in vitro and by vaccination in patients with leukemia, breast cancer, and melanoma. We did this study to investigate whether survivin-specific CD8+ T cells occur in patients with multiple myeloma. Experimental Design: An HLA-A2.1–binding survivin peptide was used to detect peptide-specific T cells by a quantitative real-time PCR to measure antigen-specific IFN-γ mRNA expression in 23 patients with myeloma and 21 healthy volunteers. T cells producing IFN-γ in response to survivin were further analyzed for expression of CD45RA and CCR7 to determine phenotypic characterization. Additional immunohistochemical analyses of survivin antigen expression in bone marrow specimens of patients was done. Results: T cells recognizing HLA-A2.1–binding survivin peptide were detected in 9 of 23 patients and in 1 of 21 healthy volunteers. Survivin-reactive T cells were identified as terminally differentiated effector T cells (CD8+, CD45RA+, and CCR7−). Positive survivin expression of myeloma cells in bone marrow specimens was shown in 7 of 11 patients. Conclusion: We provide, for the first time, evidence of T cell reactivity against survivin antigen in patients with multiple myeloma. Our data suggest the immunogenicity of survivin antigen in multiple myeloma and that immunotherapeutic strategies using survivin as a target antigen might be an option for patients with this disease.

Mcm2 predicts recurrence hazard in stage Ta/T1 bladder cancer more accurately than CK20, Ki67 and histological grade

Stage Ta/T1 urothelial carcinoma of the bladder (Ta/T1 BC) has a marked tendency to recur. Besides histopathology, markers such as CK20 expression and proliferation index (Ki67) have been shown to predict its clinical course. The replication-licensing factor minichromosome maintenance protein 2 (Mcm2) is a marker of proliferative potential shown to be a promising prognostic marker in various malignancies. The aim of the present study was to evaluate the prognostic value of Mcm2 in comparison to stage, grade, CK20 and Ki67. Initial sporadic Ta/T1 BC (n=71) were evaluated for their expression of CK20, Ki67 and Mcm2 by immunohistochemistry and tissue microarray technology. Prognostic power was analysed by univariate and multivariate Cox regression model for tumour recurrence rate. Median follow-up period was 39 months. A total of 35% patients experienced recurrence. While CK20 was not predictive, grade, Ki67 and Mcm2 were significantly related to recurrence rate in univariate Cox regression model. Only grade (HR 2.37; 95% CI 1.24–4.51; P=0.009) and Mcm2 expression with a cutoff ⩾40% (HR 5.81; 95% CI 2.41–14.00; P<0.001) were independent predictors of recurrence rate in multivariate Cox regression analysis. In addition to grade, expression of Mcm2 is an independent predictor of recurrence in Ta/T1 BC.

Diffuse large B-cell lymphoma with overexpression of cyclin e substantiates poor standard treatment response and inferior outcome.

Purpose: Gold standard to predict survival and stratify patients for risk-adapted therapy in diffuse large B-cell lymphoma (DLBCL) is the international prognostic index, although it does not consider the molecular heterogeneity of DLBCL. Deregulation of cyclin E (CCNE) is a strong predictor of poor prognosis in some neoplastic diseases. In tumor cells, it induces chromosomal instability with an increased rate of aneuploidy/polyploidy. Experimental Design: We analyzed in this retrospective study the prognostic value of immunohistochemical CCNE expression on a validated tissue microarray containing 101 de novo DLBCLs and, in 9 cases, the CCNE-induced chromosomal instability as assessed by cytometry. Results: Forty-six of 98 evaluable DLBCLs expressed CCNE in a mean proportion of 20 ± 29% of tumor cells; 38 cases expressed CCNE in ≥20% of tumor cells. CCNE-positive samples were aneuploid compared with near tetraploidy in CCNE-negative cases. Multivariate analysis showed CCNE expression in ≥20% of tumor cells to be an international prognostic index–independent, Adriamycin-based treatment-independent, and BCL2-independent prognostic factor for poor disease-specific survival. CCNE expression in ≥80% of tumor cells was associated with dismal short-term prognosis. CCNE expression in ≥50% of tumor cells emerged as an independent predictive factor for standard CHOP treatment resistance. Conclusions: CCNE expression assessment is easy on paraffin-embedded tissue. The high prognostic value of CCNE expression in DLBCL may be the basis for future prospective trials. In addition, a high CCNE expression hints at the presence of a possible target for individualized cancer therapy.

DNA replication licensing in peripheral B-cell lymphoma

Peripheral B‐cell lymphomas representing 90% of lymphoid neoplasms are divided into low‐ and high‐growth fraction lymphomas. Here we investigate regulation of DNA replication licensing during B‐cell lymphomagenesis. Combined analysis of origin licensing factors Mcm2 and geminin with the proliferation marker Ki67 in SLL/CLL, MCL, DLBCL and Burkitt lymphoma reveals for the first time the precise cell cycle state of these entities. Given that tight Mcm2 downregulation defines the quiescent state (G0) and that both high‐ and low‐growth fraction lymphomas express Mcm2, the data demonstrate that neoplastic lymphocytes of SLL/CLL and MCL reside in an “in‐cycle” G1 state and not in G0 as previously thought. Absence of the S/G2/M phase marker geminin in SLL/CLL and MCL further indicates failure of cell cycle progression in these tumours. In contrast, the high‐growth fraction lymphomas DLBCL and Burkitt lymphoma exhibit differential expression of geminin, with the geminin/Ki67 ratio increasing for more aggressive neoplasms in keeping with a shortened G1 phase and thus representing an important discriminator for differential diagnosis. These data provide new insights into abrogation of cell cycle control during B cell lymphomagenesis and suggest that combined analysis of origin licensing factors may contribute to improved treatment decisions and prognosis in haematopoietic malignancies. Copyright