Nucleolar and AgNOR-analysis of prostatic intraepithelial neoplasia (PIN), atypical adenomatous hyperplasia (AAH) and prostatic carcinoma

Novel Assay to Detect RNA Polymerase I Activity In Vivo

This report develops an analytically validated chromogenic in situ hybridization (CISH) assay using branched DNA signal amplification (RNAscope) for detecting the expression of the 5' external transcribed spacer (ETS) of the 45S ribosomal (r) RNA precursor in formalin-fixed and paraffin-embedded (FFPE) human tissues. 5'ETS/45S CISH was performed on standard clinical specimens and tissue microarrays (TMA) from untreated prostate carcinomas, high-grade prostatic intraepithelial neoplasia (PIN), and matched benign prostatic tissues. Signals were quantified using image analysis software. The 5'ETS rRNA signal was restricted to the nucleolus. The signal was markedly attenuated in cell lines and in prostate tissue slices after pharmacologic inhibition of RNA polymerase I (Pol I) using BMH-21 or actinomycin D, and by RNAi depletion of Pol I, demonstrating validity as a measure of Pol I activity. Clinical human prostate FFPE tissue sections and TMAs showed a marked increase in the signal in the presumptive precursor lesion (high-grade PIN) and invasive adenocarcinoma lesions (P = 0.0001 and P = 0.0001, respectively) compared with non-neoplastic luminal epithelium. The increase in 5'ETS rRNA signal was present throughout all Gleason scores and pathologic stages at radical prostatectomy, with no marked difference among these. This precursor rRNA assay has potential utility for detection of increased rRNA production in various tumor types and as a novel companion diagnostic for clinical trials involving Pol I inhibition.Implications: Increased rRNA production, a possible therapeutic target for multiple cancers, can be detected with a new, validated assay that also serves as a pharmacodynamic marker for Pol I inhibitors. Mol Cancer Res; 15(5); 577-84. ©2017 AACR.

Fractal analysis and the diagnostic usefulness of silver staining nucleolar organizer regions in prostate adenocarcinoma

Pathological diagnosis of prostate adenocarcinoma often requires complementary methods. On prostate biopsy tissue from 39 patients including benign nodular hyperplasia (BNH), atypical adenomatous hyperplasia (AAH), and adenocarcinomas, we have performed combined histochemical-immunohistochemical stainings for argyrophilic nucleolar organizer regions (AgNORs) and glandular basal cells. After ascertaining the pathology, we have analyzed the number, roundness, area, and fractal dimension of individual AgNORs or of their skeleton-filtered maps. We have optimized here for the first time a combination of AgNOR morphological denominators that would reflect best the differences between these pathologies. The analysis of AgNORs' roundness, averaged from large composite images, revealed clear-cut lower values in adenocarcinomas compared to benign and atypical lesions but with no differences between different Gleason scores. Fractal dimension (FD) of AgNOR silhouettes not only revealed significant lower values for global cancer images compared to AAH and BNH images, but was also able to differentiate between Gleason pattern 2 and Gleason patterns 3–5 adenocarcinomas. Plotting the frequency distribution of the FDs for different pathologies showed clear differences between all Gleason patterns and BNH. Together with existing morphological classifiers, AgNOR analysis might contribute to a faster and more reliable machine-assisted screening of prostatic adenocarcinoma, as an essential aid for pathologists.

Changes in ribosome biogenesis may induce cancer by down-regulating the cell tumor suppressor potential

Many human pathological conditions, not linked to genetic alterations of oncogenes or tumor suppressors, are nevertheless associated with an increased risk of developing cancer, and some of them are characterized by quantitative and/or qualitative changes in ribosome biogenesis. Indeed, there is evidence that both an up-regulation of ribosome biogenesis, such as that occurring during the abnormal stimulation of cell growth, and intrinsic dysfunctions of ribosomes, such as those characterizing a series of inherited disorders, show an increased incidence of tumor onset. Here we discuss some recent insights into the mechanisms by which these alterations in ribosome biogenesis may facilitate tumorigenesis.

Mechanisms of Disease: high-grade prostatic intraepithelial neoplasia and other proposed preneoplastic lesions in the prostate

High-grade prostatic intraepithelial neoplasia (HGPIN) is the most likely precursor of prostatic adenocarcinoma according to virtually all available evidence. This lesion is characterized by cellular proliferations within pre-existing ducts and acini, with nuclear and nucleolar enlargements similar to those seen in prostate cancer, although unlike cancer HGPIN retains a basal-cell layer. The recognition of HGPIN is clinically important because of the strong association between this disease and prostatic carcinoma. The predictive value for cancer of an initial diagnosis of HGPIN on needle biopsy has substantially declined, with values falling from 36% to 21%. A major factor contributing to this decline is related to increased use of needle biopsy core sampling, which has provided the means for many cancers associated with HGPIN to be detected on initial biopsy; repeat biopsy, even with good sampling, does not detect many additional cancers. Other possible findings in the prostate might indicate premalignant disease (low-grade prostatic intraepithelial neoplasia, atrophy, malignancy-associated changes, and atypical adenomatous hyperplasia or adenosis), but the data for these premalignant diseases are much less convincing than those for HGPIN.

Quantitation of conventional histologic parameters and biologic factors in prostatic needle biopsy are useful to distinguish paramalignant from malignant disease

The scope of this work was to determine the potential use of prostatic conventional histologic parameters and biologic factors in distinguishing between paramalignant and malignant prostatic disease, taking into account benign fragments of biopsies obtained from patients with prostatic cancer or from patients suspected to have cancer. Each prostate sample was semi-quantified for macronucleoli, mucin, crystalloid, collagen micronodules, and quantified for glands, stroma, AgNOR, and p53. The database covered 185 biopsy specimens from 136 patients: 56 samples from the same number of patients in whom all the biopsies were benign; 49 samples from patients whose biopsies showed malignant features, and 80 malignant samples. Discriminant analysis of the results showed statistical differences for four parameters: macronucleoli, mucin, gland volume, and AgNOR, allowing us to identify three patterns of prostate involvement: normal, paramalignant, and malignant. The discriminant function permitted an adequate classification of the three patterns in 84% of the cases. Normal areas showed glands with a mean volume of 38.93 microm3, inconspicuous nucleoli, low mucin production, and a mean AgNOR area of 1.26 microm2. Prostatic biopsies with prominent nucleoli and the presence of mucin (60%), gland volume of 22.31 microm3, and AgNOR area of 2.14 microm2 characterized the paramalignant condition. Malignant areas were characterized by mean glands with a volume of 8.11 microm3, prominent nucleoli, high mucin secretion (100%), and AgNOR area of 4.47 microm2. We concluded that modifications in prostate histoarquitecture and function, such as the presence of macronucleoli, volume of glands, abnormal secretion of acid mucin and AgNOR expression, represent important parameters that must be incorporated in the pathologist's evaluation of prostate biopsies to the purpose of indicating a subsequent biopsy, particulary in those patients with clinical suspicion of malignancy, and whose prostate biopsy specimen showed paramalignant areas.

Molecular aspects of diagnostic nucleolar and nuclear envelope changes in prostate cancer

Prostate cancer is still diagnosed by pathologists based on subjective assessment of altered cell and tissue structure. The cellular-level structural changes diagnostic of some forms of cancer are known to be induced by cancer genes, but the relation between specific cellular-level structural features and cancer genes has not been explored in the prostate. Two important cell structural changes in prostate cancer-nucleolar enlargement and nuclear envelope (NE) irregularity-are discussed from the perspective that they should also relate to the function of the genes active in prostate cancer. Enlargement of the nucleolus is the key diagnostic feature of high-grade prostatic intraepithelial neoplasia (PIN), an early stage that appears to be the precursor to the majority of invasive prostate cancers. Nucleolar enlargement classically is associated with increased ribosome production, and production of new ribosomes appears essential for cell-cycle progression. Several cancer genes implicated in PIN are known (in other cell types) to augment ribosome production, including c-Myc, p27, retinoblastoma, p53, and growth factors that impact on ERK signaling. However, critical review of the available information suggests that increased ribosome production per se may be insufficient to explain nucleolar enlargement in PIN, and other newer functions of nucleoli may therefore need to be invoked. NE irregularity develops later in the clonal evolution of some prostate cancers, and it has adverse prognostic significance. Nuclear irregularity has recently been shown to develop dynamically during interphase following oncogene expression, without a requirement for post-mitotic NE reassembly. NE irregularity characteristic of some aggressive prostate cancers could reflect cytoskeletal forces exerted on the NE during active cell locomotion. NE irregularity could also promote chromosomal instability because it leads to chromosomal asymmetry in metaphase. Finally, NE irregularity could impact replication competence, transcriptional programming and nuclear pore function.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Histological markers of risk and the role of high-grade prostatic intraepithelial neoplasia

The marked discrepancy between the prevalence of preclinical prostate cancer and the incidence of clinically manifest disease indicates a long latency phase and significant heterogeneity in the progression potential of early neoplastic lesions. There are a variety of histologic changes within prostatic epithelium that have been termed atypical or dysplastic. The 2 most widely studied of these lesions are prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia (AAH). Although associations between AAH and adenocarcinoma are spurious, those linking high-grade PIN (HGPIN) to cancer are far more established. There is a significantly increased risk for patients with isolated HGPIN to have prostate cancer confirmed on subsequent biopsy, suggesting that HGPIN is a marker for prostate carcinoma in addition to its potential role as a premalignant lesion. Autopsy studies reveal that HGPIN is found in association with cancer in 63% to 94% of malignant and 25% to 43% of benign prostates. Data on age and race reveal that African American men develop more extensive HGPIN at a younger age than white men. A wide spectrum of molecular/genetic abnormalities appears to be common to both HGPIN and prostate cancer. Data loss of 8p, 10q, 16q, 18q, and gain of 7q31, 8q, multiple copies of the c-myc genes, along with changes in chromatin texture, telomerase activity, cell cycle status, and proliferative indices collectively suggest that HGPIN is intermediate between benign epithelium and prostatic carcinoma with respect to these markers. These data indicate that HGPIN is important in neoplastic progression, and may present an appropriate target/marker for chemoprevention.

Cell proliferation, apoptosis, oncogene, and tumor suppressor gene status in adenosis with comparison to benign prostatic hyperplasia, prostatic intraepithelial neoplasia, and cancer

There is scant information on the cell proliferation, apoptosis, oncogenes, and tumor suppressor genes status in adenosis. Forty-eight foci of adenosis were studied with immunohistochemistry for MIB-1; c-erbB-2, c-erbB-3, bcl-2 oncogenes; and p53. To evaluate apoptosis, the TdT dUTP nick end labeling (TUNEL) method was applied. Results were compared with the same studies on benign prostatic hyperplasia (BPH) (n = 20), low-grade prostatic intraepithelial neoplasia (PIN) (n = 10); high-grade PIN (n = 20), Gleason sum 2 to 6 cancer (n = 16); and Gleason sum 7 to 10 cancer (n = 22). MIB-1 proliferation index was lowest in BPH, followed by adenosis, low-grade prostatic intraepithelial neoplasia (PIN), low-grade cancer, high-grade PIN, and high-grade cancer. The apoptotic rate was generally low in all groups, although it was higher in PIN and cancer. In BPH and adenosis, bcl-2 was absent in luminal cells. In low- and high-grade PIN, both basal and luminal cells expressed bcl-2, whereas in cancer, expression was found in only 1 case (3%). C-erbB-2 showed absent or low values for cancer and adenosis, whereas it was commonly expressed in BPH and low- and high-grade PIN. Low expression in adenosis was also found with c-erbB-3 (6%) compared with all other groups. Expression of p53 was confined to cancer. Despite a significantly higher proliferation index rate compared with BPH, adenosis showed a markedly lower proliferating index when compared with low-grade PIN, high-grade PIN, and cancer. Expression of the oncogenes c-erbB-2 and cerbB-3 was very low in adenosis, and the staining pattern for bcl-2 was similar to that of BPH. These results provide additional evidence to that of prior studies that adenosis is a histological small acinar proliferation more akin to BPH than high-grade PIN or adenocarcinoma.

High and low risk prostate carcinoma determined by histologic grade and proliferative activity

BACKGROUND

Histologic grade of differentiation is a strong prognostic factor for prostate carcinoma. However, most tumors fall in the intermediate group. Nuclear and nucleolar morphometry and analysis of the argyrophilic nucleolar organizer regions (AgNORs) were performed to improve prognosis, especially for patients with intermediate histologic grade tumors.

METHODS

Core needle biopsies from 65 patients with primary prostate carcinoma at diagnosis were studied. Patients received only hormone therapy. Formalin fixed and paraffin embedded sections were stained with the method of Ploton. The mean AgNOR count was calculated in 100 tumor cells for each case. Nuclear and nucleolar areas from 100 cells were measured with an automated image analyzer. One-way analysis of variance and uni- and multivariate survival analyses were used for statistical evaluation.

RESULTS

In the whole series, World Health Organization (WHO) tumor grade, nuclear and nucleolar areas, and AgNOR counts were correlated with survival time. By multivariate analysis, only AgNOR counts retained independent prognostic significance. In WHO Grade 2 carcinoma, the 5-year survival rate for patients with AgNOR/cell < or = 7.84 was 77%, but was only 12% for those with higher counts (P < 0.0001). These survival rates were similar to those obtained when patients with WHO Grade 1 carcinoma and Grade 2 carcinoma plus low AgNOR counts were compared with patients with Grade 3 carcinoma and Grade 2 carcinoma plus high AgNOR counts. In Gleason intermediate Grade 6 and 7 carcinomas, the 5-year survival rate for patients with AgNOR/cell < or = 7.84 was 71%, but was only 7% for those having higher counts (P = 0.0001).

CONCLUSIONS

Nuclear and nucleolar areas, as well as AgNOR counts, supplement histologic grading in the prognostic assessment of prostate carcinoma in patients receiving only hormone therapy. AgNOR count also is a prognostic factor for patients with intermediate grade tumors. The combination of histologic grade and proliferative activity allows the stratification of patients into low and high risk groups.

Cell kinetic studies on prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia (AAH) of the prostate

To investigate possible cell kinetic relations between benign prostatic hyperplasia (BPH), atypical adenomatous hyperplasia (AAH), prostatic intraepithelial neoplasia (PIN) and carcinoma, cell kinetic analyses were performed using radiolabelled DNA-precursors (3H-thymidine autoradiography), immunohistochemistry (proliferation marker Ki67/MIB1 and/or PCNA) and silver staining of nucleolar organizer regions (AgNOR). All methods yielded the lowest values for BPH and AAH, while maximal values were found in carcinoma of high malignancy. PIN was equal to GII-carcinomas, while AAH was between BPH and carcinoma of low malignancy. This investigation ranks BPH, AAH, low grade carcinoma, PIN and high grade carcinoma in order using different methods of cell kinetic analysis. The preneoplastic character of PIN is apparent whereas the character of AAH remains uncertain.