Lukas Bubendorf

Gene-expression profiles in hereditary breast cancer.

BACKGROUND Many cases of hereditary breast cancer are due to mutations in either the BRCA1 or the BRCA2 gene. The histopathological changes in these cancers are often characteristic of the mutant gene. We hypothesized that the genes expressed by these two types of tumors are also distinctive, perhaps allowing us to identify cases of hereditary breast cancer on the basis of gene-expression profiles. METHODS RNA from samples of primary tumor from seven carriers of the BRCA1 mutation, seven carriers of the BRCA2 mutation, and seven patients with sporadic cases of breast cancer was compared with a microarray of 6512 complementary DNA clones of 5361 genes. Statistical analyses were used to identify a set of genes that could distinguish the BRCA1 genotype from the BRCA2 genotype. RESULTS Permutation analysis of multivariate classification functions established that the gene-expression profiles of tumors with BRCA1 mutations, tumors with BRCA2 mutations, and sporadic tumors differed significantly from each other. An analysis of variance between the levels of gene expression and the genotype of the samples identified 176 genes that were differentially expressed in tumors with BRCA1 mutations and tumors with BRCA2 mutations. Given the known properties of some of the genes in this panel, our findings indicate that there are functional differences between breast tumors with BRCA1 mutations and those with BRCA2 mutations. CONCLUSIONS Significantly different groups of genes are expressed by breast cancers with BRCA1 mutations and breast cancers with BRCA2 mutations. Our results suggest that a heritable mutation influences the gene-expression profile of the cancer.

Tissue microarray (TMA) technology: miniaturized pathology archives for high-throughput in situ studies.

Tissue microarray (TMA) technology allows a massive acceleration of studies correlating molecular in situ findings with clinico‐pathological information. In this technique, cylindrical tissue samples are taken from up to 1000 different archival tissue blocks and subsequently placed into one empty ‘recipient’ paraffin block. Sections from TMA blocks can be used for all different types of in situ tissue analyses including immunohistochemistry and in situ hybridization. Multiple studies have demonstrated that findings obtained on TMAs are highly representative of their donor tissues, despite the small size of the individual specimens (diameter 0.6 mm). It is anticipated that TMAs will soon become a widely used tool for all types of tissue‐based research. The availability of TMAs containing highly characterized tissues will enable every researcher to perform studies involving thousands of tumours rapidly. Therefore, TMAs will lead to a significant acceleration of the transition of basic research findings into clinical applications. Copyright

Microarrays of bladder cancer tissue are highly representative of proliferation index and histological grade

The number of genes suggested to play a role in cancer biology is rapidly increasing. To be able to test a large number of molecular parameters in sufficiently large series of primary tumours, a tissue microarray (TMA) approach has been developed where samples from up to 1000 tumours can be simultaneously analysed on one glass slide. Because of the small size of the individual arrayed tissue samples (diameter 0.6 mm), the question arises of whether these specimens are representative of their donor tumours. To investigate how representative are the results obtained on TMAs, a set of 2317 bladder tumours that had been previously analysed for histological grade and Ki67 labelling index (LI) was used to construct four replica TMAs from different areas of each tumour. Clinical follow‐up information was available from 1092 patients. The histological grade and the Ki67 LI were determined for every arrayed tumour sample (4×2317 analyses each). Despite discrepancies in individual cases, the grade and Ki67 information obtained on minute arrayed samples were highly similar to the data obtained on large sections (p<0.0001). Most importantly, every individual association between grade or Ki67 LI and tumour stage or prognosis (recurrence, progression, tumour‐specific survival) that was observed in large section analysis could be fully reproduced on all four replica TMAs. These results show that intra‐tumour heterogeneity does not significantly affect the ability to detect clinico‐pathological correlations on TMAs, probably because of the large number of tumours that can be included in TMA studies. TMAs are a powerful tool for rapid identification of the biological or clinical significance of molecular alterations in bladder cancer and other tumour types. Copyright

Frequent high-level expression of the immunotherapeutic target Ep-CAM in colon, stomach, prostate and lung cancers.

Epithelial cell adhesion molecule (Ep-CAM; CD326) is used as a target by many immunotherapeutic approaches, but little data are available about Ep-CAM expression in major human malignancies with respect to level, frequency, tumour stage, grade, histologic tumour type and impact on survival. We analysed by immunohistochemical staining tissue microarrays with 4046 primary human carcinoma samples from colon, stomach, prostate and lung cancers for both frequency and intensity of Ep-CAM expression under highly standardised conditions. A total of 3360 samples were analysable. High-level Ep-CAM expression was observed in 97.7% (n=1186) of colon, 90.7% of gastric (n=473), and 87.2% of prostate cancers (n=414), and in 63.9% of lung cancers (n=1287). No detectable Ep-CAM staining was found with only 0.4% of colon, 2.5% of gastric, 1.9% of prostate cancers, and 13.5% of lung cancers. The only significant correlation of Ep-CAM expression with tumour grading was observed in colon cancer where high-level Ep-CAM expression on grade 3 tumours was down to 92.1% (P<0.0001). Adenosquamous and squamous carcinomas of the lung had a lower percentage of high-level Ep-CAM expression compared to adenocarcinomas with 35.4 and 53.6%, respectively, and with 45.5 and 17.3% of tumours being Ep-CAM negative. With the exception of moderately differentiated colon carcinoma, where patients not expressing Ep-CAM on their tumours showed an inferior survival (P=0.0014), correlation of Ep-CAM expression with survival did not reach statistical significance for any of the other cancer indications and subgroups. In conclusion, the data strongly support the notion that Ep-CAM is a prime target for immunotherapies in major human malignancies. This is because the most common human cancers show (i) a low frequency of Ep-CAM-negative tumours, (ii) a high frequency of Ep-CAM expression on cells of a given tumour, and (iii) for most cancers, an insignificant influence of tumour staging, grading and histology on Ep-CAM expression.

Multiprobe FISH for Enhanced Detection of Bladder Cancer in Voided Urine Specimens and Bladder Washings

The aim of this study was to evaluate the UroVysion (Vysis, Downers Grove, IL) fluorescence in situ hybridization (FISH) test for improved detection of bladder cancer in urinary specimens. Three groups of specimens were examined, including voided urine specimens (1) collected before resection of bladder cancer, (2) from cystoscopically negative bladders of patients with previous bladder cancer, and (3) from patients with benign prostatic hyperplasia (controls). FISH positivity was defined as more than 2 urothelial cells with an abnormal signal copy number of at least 1 of the 4 probes. FISH was positive in 1 of 27 control specimens and in 33 (73%) of 45 pTa, 12 (100%) of 12 pT1, and 13 (100%) of 13 pT2-4 tumors. The results were similar in a series of 68 bladder washings. In addition, FISH of voided urine specimens was positive in 5 of 10 patients with negative follow-up cystoscopy results. Subsequent recurrence was found in 4 of these patients but in none of 5 patients with FISH-negative results. Multiprobe FISH markedly improves the sensitivity and specificity of cytology for the detection of bladder cancer in urine specimens.

Chromosomal imbalances in papillary renal cell carcinoma: genetic differences between histological subtypes.

Papillary renal-cell carcinoma (RCC) is a renal carcinoma variant with distinct gross, microscopic, and cytogenetic features. Recently, a type 1 (pale cytoplasm, small-cell) and a type 2 (eosinophilic cytoplasm, large-cell) subtype of papillary RCC have been described. Chromosomal alterations associated with these tumor types were examined in 25 papillary RCCs by comparative genomic hybridization. Relative copy number gains were frequently detected at chromosomes 7p (56%), 7q (44%), 12q (28%), 16q (32%), 17p (56%), 17q (76%), and 20q (32%). Chromosomal regions that were most often lost included 1p (24%), 4q (36%), 6q (40%), 9p (36%), 13q (36%), Xp (28%), Xq (36%), and Y (73%). There were clinical and genetic differences between the subtypes of papillary RCC. Type 2 tumors were of higher nuclear grade (P = 0.0012) and higher stage (P = 0.01) and had a worse prognosis (P = 0.03) than type 1 tumors. The number of DNA gains per tumor, especially gains of 7p and 17p, was significantly higher in type 1 than in type 2 tumors (P < 0.01). These data suggest the existence of two distinct morphological and genetic subgroups of papillary RCC. Losses of chromosome Xp were associated with short patient survival (P < 0.01). Despite the small number of cases, this finding suggests that a gene on chromosome Xp may contribute to papillary RCC progression.

Signal Transducer and Activator of Transcription-5 Activation and Breast Cancer Prognosis

PURPOSE Transcription factor signal transducer and activator of transcription-5 (Stat5) promotes breast epithelial cell differentiation. We retrospectively analyzed whether levels of active Stat5 in breast cancer were linked to clinical outcome. MATERIALS AND METHODS Immunohistochemistry was used to detect active, tyrosine-phosphorylated Stat5 in paraffin-embedded breast cancer specimens from three archival tissue microarray materials A, B, and C. Material A included 19 healthy human breast tissues and a progression series of primary lymph node-negative, primary lymph node-positive, and metastatic breast cancer (n = 400). Materials B (n = 785) and C (n = 570) represented two independent arrays of unselected primary breast cancer specimens with clinical follow-up data. RESULTS Material A demonstrated that Stat5 activation, but not Stat5 protein expression, was gradually lost during cancer progression, with detectable activation in 100% of healthy breast specimens compared with less than 20% of node-positive breast cancers and metastases. Stat5 activation in tumors of material B was associated with favorable prognosis. This observation was confirmed and extended in material C to include both breast cancer-specific survival and disease-free survival. Stat5 activation remained an independent prognostic marker after adjusting for patient age, tumor size, histological grade, estrogen receptor, progesterone receptor, and Her2/neu status by Cox multivariate analysis (hazard ratio, 2.0; P =.029). Stat5 activation was a particularly favorable marker in the lymph node-negative breast cancer subpopulation (hazard ratio, 7.5; P =.003). CONCLUSION In our study, active Stat5 distinguishes breast cancer patients with favorable prognosis, and may be a useful marker for selection of more individualized treatment, especially in localized disease. These findings require confirmation in a large prospective study.

Stat3 promotes metastatic progression of prostate cancer.

There are currently no effective therapies for metastatic prostate cancer because the molecular mechanisms that underlie the metastatic spread of primary prostate cancer are unclear. Transcription factor Stat3 is constitutively active in malignant prostate epithelium, and its activation is associated with high histological grade and advanced cancer stage. In this work, we hypothesized that Stat3 stimulates metastatic progression of prostate cancer. We show that Stat3 is active in 77% of lymph node and 67% of bone metastases of clinical human prostate cancers. Importantly, adenoviral gene delivery of wild-type Stat3 (AdWTStat3) to DU145 human prostate cancer cells increased the number of lung metastases by 33-fold in an experimental metastasis assay compared with controls. Using various methods to inhibit Stat3, we demonstrated that Stat3 promotes human prostate cancer cell migration. Stat3 induced the formation of lamellipodia in both DU145 and PC-3 cells, further supporting the concept that Stat3 promotes a migratory phenotype of human prostate cancer cells. Moreover, Stat3 caused the rearrangement of cytoplasmic actin stress fibers and microtubules in both DU145 and PC-3 cells. Finally, inhibition of the Jak2 tyrosine kinase decreased both activation of Stat3 and prostate cancer cell motility. Collectively, these data indicate that transcription factor Stat3 is involved in metastatic behavior of human prostate cancer cells and may provide a therapeutic target to prevent metastatic spread of primary prostate cancer.

Ki67 LABELLING INDEX: AN INDEPENDENT PREDICTOR OF PROGRESSION IN PROSTATE CANCER TREATED BY RADICAL PROSTATECTOMY

The clinical course of prostate cancer is highly variable and cannot satisfactorily be predicted by histological criteria alone. Both tumour cell proliferation and neuroendocrine differentiation have been suggested as additional prognostic parameters, neuroendocrine differentiation being considered to enhance tumour cell proliferation. This study investigated the prognostic value of tumour cell proliferation [Ki67 labelling index (LI), MIB 1] and neuroendocrine differentiation and their relationship to each other. One hundred and thirty‐seven paraffin‐embedded radical prostatectomy specimens were examined. Neuroendocrine differentiation was found in 58 per cent of cases, but was not associated with pTN stage, Gleason score, Ki67 LI, or tumour progression. Ki67 LI was not significantly associated with pTN stage or with Gleason score. High grade (P=0·0005), advanced local stage (P=0·0004), positive lymph nodes (P=0·02), and high Ki67 LI (P=0·0203) were predictors of tumour progression if univariate analysis was performed, but Cox stepwise regression showed that only advanced local stage (P=0·0025) and Ki67 LI (P=0·0105) were independent predictors of tumour progression, the relative risk being 3·6 and 2·5, respectively. It is concluded that Ki67 is an important prognostic marker in prostate cancer with a potential for routine application.

Nonsense-mediated decay microarray analysis identifies mutations of EPHB2 in human prostate cancer

The identification of tumor-suppressor genes in solid tumors by classical cancer genetics methods is difficult and slow. We combined nonsense-mediated RNA decay microarrays and array-based comparative genomic hybridization for the genome-wide identification of genes with biallelic inactivation involving nonsense mutations and loss of the wild-type allele. This approach enabled us to identify previously unknown mutations in the receptor tyrosine kinase gene EPHB2. The DU 145 prostate cancer cell line, originating from a brain metastasis, carries a truncating mutation of EPHB2 and a deletion of the remaining allele. Additional frameshift, splice site, missense and nonsense mutations are present in clinical prostate cancer samples. Transfection of DU 145 cells, which lack functional EphB2, with wild-type EPHB2 suppresses clonogenic growth. Taken together with studies indicating that EphB2 may have an essential role in cell migration and maintenance of normal tissue architecture, our findings suggest that mutational inactivation of EPHB2 may be important in the progression and metastasis of prostate cancer.