Free digital image analysis software helps to resolve equivocal scores in HER2 immunohistochemistry.

Evaluation of human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) is subject to interobserver variation and lack of reproducibility. Digital image analysis (DIA) has been shown to improve the consistency and accuracy of the evaluation and its use is encouraged in current testing guidelines. We studied whether digital image analysis using a free software application (ImmunoMembrane) can assist in interpreting HER2 IHC in equivocal 2+ cases. We also compared digital photomicrographs with whole-slide images (WSI) as material for ImmunoMembrane DIA. We stained 750 surgical resection specimens of invasive breast cancers immunohistochemically for HER2 and analysed staining with ImmunoMembrane. The ImmunoMembrane DIA scores were compared with the originally responsible pathologists' visual scores, a researcher's visual scores and in situ hybridisation (ISH) results. The originally responsible pathologists reported 9.1 % positive 3+ IHC scores, for the researcher this was 8.4 % and for ImmunoMembrane 9.5 %. Equivocal 2+ scores were 34 % for the pathologists, 43.7 % for the researcher and 10.1 % for ImmunoMembrane. Negative 0/1+ scores were 57.6 % for the pathologists, 46.8 % for the researcher and 80.8 % for ImmunoMembrane. There were six false positive cases, which were classified as 3+ by ImmunoMembrane and negative by ISH. Six cases were false negative defined as 0/1+ by IHC and positive by ISH. ImmunoMembrane DIA using digital photomicrographs and WSI showed almost perfect agreement. In conclusion, digital image analysis by ImmunoMembrane can help to resolve a majority of equivocal 2+ cases in HER2 IHC, which reduces the need for ISH testing.

High NRBP1 expression in prostate cancer is linked with poor clinical outcomes and increased cancer cell growth.

BACKGROUND: We recently established the rationale that NRBP1 (nuclear receptor binding protein 1) has a potential growth-promoting role in cell biology. NRBP1 interacts directly with TSC-22, a potential tumor suppressor gene that is differently expressed in prostate cancer. Consequently, we analyzed the role of NRBP1 expression in prostate cancer cell lines and its expression on prostate cancer tissue microarrays (TMA). METHODS: The effect of NRBP1 expression on tumor cell growth was analyzed by using RNAi. NRBP1 protein expression was evaluated on two TMAs containing prostate samples from more than 1,000 patients. Associations with clinico-pathological features, the proliferation marker Ki67 and survival data were analyzed. RESULTS: RNAi mediated silencing of NRBP1 expression in prostate cancer cell lines resulted in reduced cell growth (P < 0.05). TMA analysis revealed NRBP1 protein expression in benign prostate hyperplasia in 6% as compared to 60% in both, high-grade intraepithelial neoplasia and prostate cancer samples. Strong NRBP1 protein expression was restricted to prostate cancer and correlated with higher expression of the proliferation marker Ki67 (P < 0.05). Further, patients with strong NRBP1 protein expression showed poor clinical outcomes (P < 0.05). Analysis of matched localized cancer tissues before and after castration revealed that post-therapy-related repression of NRBP1 expression was significantly associated with better overall survival. CONCLUSIONS: We demonstrate that expression of NRBP1 is up-regulated during the progression of prostate cancer and that high NRBP1 expression is linked with poor prognosis and enhanced tumor cell growth.

Amplification and overexpression of vinculin are associated with increased tumour cell proliferation and progression in advanced prostate cancer.

Androgen withdrawal is the standard treatment for advanced prostate cancer. Although this therapy is initially effective, nearly all prostate cancers become refractory to it. Approximately 15% of these castration-resistant prostate cancers harbour a genomic amplification at 10q22. The aim of this study was to explore the structure of the 10q22 amplicon and to determine the major driving genes. Application of high-resolution array-CGH using the 244k Agilent microarrays to cell lines with 10q22 amplification allowed us to narrow down the common amplified region to a region of 5.8 megabases. We silenced each of the genes of this region by an RNAi screen in the prostate cancer cell lines PC-3 and 22Rv1. We selected genes with a significant growth reduction in the 10q22 amplified cell line PC-3, but not in the non-amplified 22Rv1 cells, as putative target genes of this amplicon. Immunohistochemical analysis of the protein expression of these candidate genes on a tissue microarray enriched for 10q22 amplified prostate cancers revealed vinculin as the most promising target of this amplicon. We found a strong association between vinculin gene amplification and overexpression (p < 0.001). Further analysis of 443 specimens from across all stages of prostate cancer progression showed that vinculin expression was highest in castration-resistant prostate cancers, but negative or very low in benign prostatic hyperplasia (p < 0.0001). Additionally, high tumour cell proliferation measured by Ki67 expression was significantly associated with high vinculin expression in prostate cancer (p < 0.0001). Our data suggest that vinculin is a major driving gene of the 10q22 amplification in prostate cancer and that vinculin overexpression might contribute to prostate cancer progression by enhancing tumour cell proliferation.

Androgen receptor amplification is associated with increased cell proliferation in prostate cancer.

Mechanisms of prostate cancer progression during hormonal therapy and the pathobiologic consequences of androgen receptor (AR) gene amplification are inadequately known. To further investigate the hypothesis that AR gene amplification is associated with increased cell proliferation, we analyzed 123 paraffin-embedded prostate cancer specimens from men who experienced tumor relapse during androgen withdrawal therapy. We used fluorescence in situ hybridization to quantify AR gene copy number and Ki-67 immunohistochemistry to determine cell proliferation. One third of the tumors showed AR gene amplification. Among tumors with AR amplification, the mean cell proliferation rate was 19.8 (SD, 12.3; 95% confidence interval [CI], 15.4-24.1), whereas it was 13.0 (SD, 15.9; 95% CI, 9.1-16.8) in tumors without amplification (P = .032). In the best fitting logistic regression model, only proliferation remained significant (P = .040). When the median Ki-67 labeling index (6.7%) of all tumors was used as a cutoff point, the tumors with AR amplification were more frequently highly proliferating than tumors with no amplification (P = .010; odds ratio, 3.4; 95% CI, 1.4-8.3). Our results imply that progression of prostate cancer during androgen withdrawal therapy is associated with AR gene amplification and increased cell proliferation rate in one third of tumors. We suggest that AR gene amplification is an important molecular mechanism underlying the increase in proliferation rate of a substantial fraction of recurrent prostate carcinomas. However, efforts should be targeted to develop prostate cancer cell lines to study causal relationships between AR gene amplification and various biologic variables.

Virtual microscopy in prostate histopathology: simultaneous viewing of biopsies stained sequentially with hematoxylin and eosin, and alpha-methylacyl-coenzyme A racemase/p63 immunohistochemistry.

PURPOSE: Histopathological diagnosis of small focus carcinomas in prostatic needle biopsies is often assisted by IHC. To make a definitive diagnosis the pathologist must compare IHC findings with hematoxylin and eosin stained tissue morphology. We introduce what is to our knowledge a new application of virtual microscopy, in which hematoxylin and eosin, and IHC stains done sequentially on the same microscope slide can be simultaneously displayed and compared on a computer screen. MATERIALS AND METHODS: A total of 30 hematoxylin and eosin stained prostatic needle biopsies were scanned with a computer controlled microscope. The slides were destained and then immunostained with a cocktail of AMACR and p63 antibodies, which labels the nuclei of nonmalignant basal cells (p63) and the cytoplasm of neoplastic glandular cells suspicious for malignancy (AMACR). The slides were then scanned again and the pairs of virtual slides were aligned for synchronized viewing. RESULTS: The presented technique was found helpful when suspicious lesions were small and when examining the immunoprofile of specimens was warranted, in addition to examining hematoxylin and eosin stained tissue morphology. The usefulness of our approach based on virtual microscopy can be evaluated on the website , which also serves as an educational tool for self-learning the correlation between hematoxylin and eosin stained tissue morphology, and AMACR/p63 IHC in prostate biopsies. CONCLUSIONS: The technology for simultaneously viewing sequentially hematoxylin and eosin and IHC stained prostate biopsies can be readily used for educational purposes, as exemplified by our website, and along with the availability of rapid virtual slide scanners it can also be used for clinical diagnostics.

Expression patterns of potential therapeutic targets in prostate cancer.

Androgen withdrawal is the only effective therapy for patients with advanced prostate cancer, but progression to androgen independence ultimately occurs in almost all patients. Novel therapeutic strategies targeting molecular mechanisms that mediate resistance to hormonal and chemotherapeutic treatment are highly warranted. Here, we aimed to evaluate the expression of potential therapeutic targets in advanced prostate cancer. A tissue microarray (TMA) containing samples from 535 tissue blocks was constructed, including benign prostatic hyperplasia as controls (n = 65), prostatic intraepithelial neoplasia (PIN; n = 78), clinically localized prostate cancers (n = 181), as well as hormone-refractory local recurrences (n = 120) and distant metastases (n = 91). The expression of 13 different proteins was analyzed using immunohistochemistry (Bcl-2, p53, ILK, Syndecan-1, MUC-1, EGFR, HER2/neu, HSP-90, Ep-CAM, MMP-2, CD-10, CD-117 and Ki67). Significant overexpression in hormone-refractory prostate cancer and metastatic tissue compared to localized prostate cancer was found for Ki67 (64% vs. 9%), Bcl-2 (11% vs. 1%), p53 (35% vs. 4%), Syndecan-1 (38% vs. 3%), EGFR (16% vs. 1%) and HER2/neu (16% vs. 0%). Overexpression of CD-117 was restricted to 1 single metastasis. All other markers did not show relevant differences in expression between subgroups. Taken together, p53, Bcl-2, Syndecan-1, EGFR and HER2/neu are preferentially expressed in hormone-refractory and metastatic prostate cancer. Selected inhibition of these targets might offer a strategy to treat advanced tumors and prevent further progression. Treatment decisions should not be based on findings in primary tumors but rather on tissues from recurrent or metastatic lesions.

Androgen receptor mutations in high-grade prostate cancer before hormonal therapy.

Androgen action is mediated through androgen receptor (AR), which appears to undergo structural and functional alterations during prostate cancer (CaP) progression. AR mutations have been infrequently reported in CaP before hormonal therapy, but in untreated, advanced tumors AR mutations are suggested to be more common. To investigate the frequency of AR mutations in aggressive CaP before hormonal therapy, we have analyzed AR coding region for aberrations in 21 paraffin-embedded prostate carcinoma samples (14 primary tumors, 7 metastases) of poor histologic differentiation. Single-stranded conformational polymorphism and sequencing analyses revealed AR missense mutations in 29% (4/14) of the primary tumors and in one (14%) metastasis. Mutations resided in the transactivation domain and in the hinge region. One of the hinge region mutants, Ser646Phe, that was identified in a patient with short endocrine therapy response, exhibited a markedly increased transcriptional activity on single androgen response element-containing promoters. In conclusion, AR mutations are frequent in high-grade CaP before initiation of hormonal therapy, and these mutations may play a role in poor therapy response and emergence of hormone-refractory CaP in some cases.

Deletion, mutation, and loss of expression of KLF6 in human prostate cancer.

Kruppel-like factors (KLFs) are a group of transcription factors that appear to be involved in different biological processes including carcinogenesis. In a recent study, KLF6 was reported as a tumor suppressor gene in prostate cancer because of its frequent loss of heterozygosity (LOH) and mutation as well as functional suppression of cell proliferation. Loss of chromosomal locus spanning KLF6 is relatively infrequent in other published studies of prostate cancer, however. To clarify the role of KLF6 in prostate cancers, particularly those that are high grade, we examined KLF6 for deletion, mutation, and loss of expression in 96 prostate cancer samples including 21 xenografts/cell lines. Loss of heterozygosity occurred in 4 (19%) of 21 xenografts/cell lines and 8 (28%) of 29 informative tumors. Fourteen of the 96 (15%) samples showed 15 somatic sequence changes in the KLF6 gene, including 7 that changed KLF6 peptide sequences, 4 that did not, and 4 that were located in untranslated regions. Expression levels of KLF6 were significantly lost in 4 of 20 (20%) xenografts/cell lines of prostate cancer, as detected by RT-PCR and Northern blot analysis. These findings indicate that significant genetic alterations of KLF6 occur in a minority of high-grade prostate cancers.

Pattern of somatic androgen receptor gene mutations in patients with hormone-refractory prostate cancer.

Progression to hormone-refractory growth of prostate cancer has been suggested to be mediated by androgen receptor (AR) gene alterations. We analyzed AR for mutations and amplifications in 21 locally recurrent prostate carcinomas treated with orchiectomy, estrogens, or a combination of orchiectomy and estramustine phosphate using fluorescence in situ hybridization, single-strand conformation polymorphism, and DNA sequence analyses. Amplification was observed in 4 of 16 (25%) and amino acid changing mutations was observed in 7 of 21 (33%) of the tumors, respectively. Two (50%) tumors with AR amplification also had missense mutation of the gene. Four of five (80%) cancers that were treated with a combination of orchiectomy and estramustine phosphate had a mutation clustered at codons 514 to 533 in the N-terminal domain of AR. In functional studies, these mutations did not render AR more sensitive to testosterone, dihydrotestosterone, androstenedione, or beta-estradiol. Tumors treated by orchiectomy had mutations predominantly in the ligand-binding domain. In summary, we found molecular alterations of AR in more than half of the prostate carcinomas that recurred locally. Some tumors developed both aberrations, possibly enhancing the cancer cell to respond efficiently to low levels of androgens. Furthermore, localization of point mutations in AR seems to be influenced by the type of treatment.