Importance of interphase nucleolar organizer regions in tumor pathology

CMTM6 attenuates cisplatin-induced cell death in OSCC by regulating AKT/c-Myc-driven ribosome biogenesis

CMTM6, a type 3 transmembrane protein, is known to stabilize the expression of programmed cell death ligand 1 (PD-L1) and hence facilitates the immune evasion of tumor cells. Recently, we demonstrated that CMTM6 is a major driver of cisplatin resistance in oral squamous cell carcinomas (OSCC). However, the detailed mechanism of how CMTM6 rewires cisplatin resistance in OSCC is yet to be explored. RNA sequencing analysis of cisplatin-resistant OSCC lines stably expressing Nt shRNA and CMTM6 shRNA revealed that CMTM6 might be a potential regulator of the ribosome biogenesis network. Knocking down CMTM6 significantly inhibited transcription of 47S precursor rRNA and hindered the nucleolar structure, indicating reduced ribosome biogenesis. When CMTM6 was ectopically over-expressed in CMTM6KD cells, almost all ribosomal machinery components were rescued. Mechanistically, CMTM6 induced the expression of C-Myc, which promotes RNA polymerase I mediated rDNA transcription. In addition to this, CMTM6 was also found to regulate the AKT-mTORC1-dependent ribosome biogenesis and protein synthesis in cisplatin-resistant lines. The nude mice and zebrafish xenograft experiments indicate that blocking ribosome synthesis either by genetic inhibitor (CMTM6KD) or pharmacological inhibitor (CX-5461) significantly restores cisplatin-mediated cell death in chemoresistant OSCC. Overall, our study suggests that CMTM6 is a major regulator of the ribosome biogenesis network and targeting the ribosome biogenesis network is a viable target to overcome chemoresistance in OSCC. The novel combination of CX-5461 and cisplatin deserves further clinical investigation in advanced OSCC.

The Ribosome Biogenesis-Cancer Connection

Multifaceted relations link ribosome biogenesis to cancer. Ribosome biogenesis takes place in the nucleolus. Clarifying the mechanisms involved in this nucleolar function and its relationship with cell proliferation: (1) allowed the understanding of the reasons for the nucleolar changes in cancer cells and their exploitation in tumor pathology, (2) defined the importance of the inhibition of ribosome biogenesis in cancer chemotherapy and (3) focused the attention on alterations of ribosome biogenesis in the pathogenesis of cancer. This review summarizes the research milestones regarding these relevant relationships between ribosome biogenesis and cancer. The structure and function of the nucleolus will also be briefly described.

Quantitative analysis of Argyrophilic Nucleolar organizer regions in odontogenic cysts and tumor - A comparative study

Background

The nucleolar organizer region (NOR) is by definition part of a chromosome, and nucleolus is a structure containing this chromosomal part and in addition the material which accumulate around the NOR, mostly rRNAs and their precursors as well as specific ribosomal proteins. Argyrophilic Nucleolar organizing region (AgNOR) are silver binding NORs often used to study cell proliferation in various types of tumors.

Aim

Quantitative assessment of Argyrophilic Nucleolar organizing region count and its comparison among dentigerous cyst, keratocystic odontogenic tumor and ameloblastoma.

Material and method

Forty-five histologically confirmed cases, 15 cases each of keratocystic odontogenic tumor, dentigerous cysts and ameloblastomas were examined for Argyrophilic Nucleolar organizing region. The sections were obtained and Argyrophilic Nucleolar organizer regions staining was done for comparing the proliferative capacity among these lesions.

Result

Post hoc analysis for inter-group comparison and one way ANOVA were done in all three groups in this study. P < 0.001 was considered significant. The results of AgNOR counts were higher in KCOTs as compared to ameloblastoma and least in dentigerous cysts. The mean AgNOR counts between the study groups were compared using one way ANOVA test and the differences were found to be significant (P < 0.001).

Conclusion

AgNOR counts were significantly higher in KCOT and ameloblastoma as compared to dentigerous cyst suggesting that these lesions have a higher proliferative capacity than dentigerous cyst. The finding of a significantly higher AgNOR counts in KCOT as compared to ameloblastoma represent a difference in proliferative activity and greater growth potential between these two lesions.

New roles for Dicer in the nucleolus and its relevance to cancer

The nucleolus is a distinct compartment of the nucleus responsible for ribosome biogenesis. Mis-regulation of nucleolar functions and of the cellular translation machinery has been associated with disease, in particular with many types of cancer. Indeed, many tumor suppressors (p53, Rb, PTEN, PICT1, BRCA1) and proto-oncogenes (MYC, NPM) play a direct role in the nucleolus, and interact with the RNA polymerase I transcription machinery and the nucleolar stress response. We have identified Dicer and the RNA interference pathway as having an essential role in the nucleolus of quiescent Schizosaccharomyces pombe cells, distinct from pericentromeric silencing, by controlling RNA polymerase I release. We propose that this novel function is evolutionarily conserved and may contribute to the tumorigenic pre-disposition of DICER1 mutations in mammals.

Evaluation of cell proliferation in malignant and potentially malignant oral lesions

Aims:

To evaluate the cell proliferation rate by the expression of proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizing region (AgNOR) counts and to assess its usefulness as a marker for malignant potential in oral epithelial lesions.

Materials and Methods:

The study group included 30 cases of leukoplakia, 15 nondysplastic (NDL), 15 dysplastic (DL), 15 cases of oral squamous cell carcinoma (OSCC) and 5 cases of normal oral mucosa. Formalin fixed paraffin embedded tissues were subjected to immunohistochemical staining for PCNA and AgNOR technique. The PCNA labeling index (LI) and the AgNOR dots were evaluated for the entire sample.

Statistical Analysis Used:

ANOVA, Tukey honestly significant difference, Pearson's correlation.

Results:

In this study, the AgNOR count of OSCC was lower than the DL lesions moreover the AgNOR counts were found to be higher in normal mucosa as compared to the DL and the NDL epithelium. The study results also showed that the mean AgNOR count failed to distinguish between DL and NDL lesions. Overall we observed increased PCNA expression from normal epithelium to NDL to DL lesion.

Conclusions:

Based on the findings of the present study on oral epithelial precancerous and cancerous lesions we conclude that mean AgNOR count alone cannot be a valuable parameter to distinguish between the normal, NDL, DL epithelium and OSCC but, on the other hand, we found out that PCNA can be a useful biomarker for delineating normal epithelium from DL epithelium and OSCC.

Evaluation of the efficacy of AgNOR as a proliferative marker in oral leukoplakia: A morphometric analysis

Background:

Silver stainable nucleolar organizer regions (AgNORs) are replicatory markers which may have a place in objectively characterizing dysplasia.

Materials and Methods:

A study of various morphometric parameters related to AgNORs was performed in basal and parabasal layers of normal human oral epithelium, nondysplastic leukoplakia, and dysplastic leukoplakia employing photomicrographs of silver stained paraffin embedded sections using image analysis, to assess the usefulness of these parameters in distinguishing dysplastic leukoplakia from nondysplastic oral leukoplakia.

Results:

Out of various mean AgNOR related parameters, AgNOR count, area, perimeter, and proportion were found to be higher in dysplastic leukoplakia as compared to nondysplastic leukoplakia. On statistical analysis, AgNOR count showed statistically significant differentiation between dysplastic and nondysplastic leukoplakia. While other parameters can distinguish normal oral epithelium from dysplastic and nondysplastic leukoplakia.

Conclusion:

To conclude, the AgNOR count is the most appropriate marker to differentiate between dysplastic and nondysplastic leukoplakia.

Proportionally constant quantitative transmission of nucleolin and protein B23 in cycling cancer cells

Objective-To investigate whether and to what extent the two major AgNOR proteins, nucleolin and protein B23, are maintained after one cell division in proliferating cells.Design-Using three asynchronously growing human cancer cell lines, TG, SJNKP, and CHP 212 cells, nucleolin and protein B23 were first identified on SDS-polyacrylamide separated nucleolar proteins, transferred to nitrocellulose and silver stained for AgNOR proteins. Measurement of doubling time indicated a period very close to 24h for each of the cell lines. To quantify the percentage of nucleolin and protein B23 maintained in daughter cells after duplication, cells were labelled with [(35)S]-methionine and a 24h cold chase performed. Nucleolin and protein B23 labelling was evaluated by densitometric analysis on nitrocellulose autoradiograms.Results-The radioactivity relative to nucleolin and protein B23 bands maintained in the daughter cells was a constant fraction of that present before cell duplication. In the three cell lines the percentage of residual radioactivity measured in the nucleolin bands was 42.2, 40.6, and 41.2 and in protein B23 bands 48.0, 46.2, and 44.1.Conclusions-After one cell division the nucleolin and protein B23 quantity present in cells may be highly variable, depending on the amount of the two proteins present in the mother cell. This is important in relation to the correct utilisation of AgNOR protein quantity as an index for evaluating cell kinetics.

Image analysis of the AgNOR response in ras-transformed human breast epithelial cells

The argyrophylic staining of the nucleolar organizer regions (AgNOR positive response) in interphase nuclei is often related directly to the cellular demand for ribosome biogenesis and is considered of relevance in studies of tumor pathology. Transformation of human breast epithelial MCF-10A cells by the c-Ha-ras oncogene results in altered growth, invasiveness and tumorigenicity in nude mice. Since ras transformation may be associated with a more intense nucleolar activity, we examined the influence of transfection by the Ha-ras oncogene on AgNOR staining response in MCF-10A cells. Following assessment of the AgNOR response with video image analysis, the AgNOR-positive areas and the AgNOR area/nuclear area ratio, but not the number of AgNOR aggregates or dots per nucleus, were found to be much higher after ras transformation. A role of the Ha-ras transformation on the nucleolar activity of the MCF-10A is thus suggested as assessed by the AgNOR staining. Based on data in the literature, it is also hypothesized that a decreased wild-type p53 level, possibly promoted by the ras transformation, may be associated with the increased AgNOR response.

Increased specificity of colloidal silver staining by means of chemical attenuation

A modification of the silver staining procedure of Howell and Black (1980) is reported which makes use of teleostean gelatin as protective colloid and renders a high signal-to-noise ratio. We demonstrate that this ratio can be further increased by subsequent attenuation with a chemical reducer consisting of a mixture of potassium ferricyanide (III) and sodium thiosulphate. It is shown that slight changes of the concentration of the reactive compounds of the chemical reducer make the protocol applicable to human, plant (Aliium cepa, Rhinanthus minor) as well as meiotic insect (Acheta domesticus) chromosome preparations. Due to its broad applicability, the method could find utilization in studies on chromatin and chromosome functions in many species.

Histological investigation of physiologically resorbing primary teeth using Ag-NOR staining method

OBJECTIVE

The aim of this study was to investigate pulpal tissue of primary teeth in early and late stages of physiological resorption by means of silver-binding nucleolar organizer region (Ag-NOR) staining.

STUDY DESIGN

Ten primary teeth in early, ten in the late stage of resorption and five sound premolar teeth pulps as the control group were investigated by means of silver-binding nucleolar organizer region (Ag-NOR) staining.

RESULTS

The mean number of Ag-NOR's per nucleus increased with the continuing of the resorption process. The difference in the mean number of Ag-NORs was statistically significant both in the early and late stage of resorption compared with controls (P > 0.001). In the early stage of resorption calcific plates in the apical part of the pulps were observed. Odontoclasts, as well as inflammatory cells, were observed in the late stages of resorption.

CONCLUSIONS

The increase in the mean number of Ag-NORs per nucleus with the progression of the resorption process in primary teeth suggests that metabolic cell activity in the early stages of resorption is enhanced and increased with the continuing of the process, thus showing the importance of the pulp tissue in the resorption process.

Correlation between silver-stained nucleolar organizer region area and cell cycle time

BACKGROUND

The relationship between the population doubling time and the quantity of silver-stained nucleolar organizer region (AgNOR) interphase proteins was studied in cell culture at three different temperatures used to modulate the cell cycle duration.

METHODS

After MIB 1 and AgNOR combined staining, the quantity of AgNOR proteins was measured in cycling cells by image cytometry.

RESULTS

Among the several parameters calculated, the AgNOR relative area showed a strong correlation with the changes of the population doubling time induced by different temperatures.

CONCLUSIONS

The results support the hypothesis that the cell cycle time and the size of the ribogenesis machinery are coregulated and that measurements of AgNORs can thus be used as a static evaluation of the cell cycle duration in arbitrary units.

Proliferative Activity of Epidermal Basal Cells after Wounding

Quantitative changes in nucleolus organizer regions (NORs) are known markers of proliferation that can be demonstrated by a specific silver staining technique on paraffin-embedded sections. Wounding of skin induces proliferation of basal epidermal cells at the wound margin. The degree of proliferation depends on the survival time and can be measured by morphometric assessment of argyrophilic NORs (AgNORs). Following incision wounding of the pinnae, rats were allowed to survive for different intervals (7 rats per interval) up to 120 hours. Before each sacrifice, biopsies were taken and incubated in a bromodeoxyuridine (BrdU) solution, embedded in paraffin, and stained with an antibody against BrdU. At the same time morphometric analysis of AgNOR counts was performed on sections made from the same material. BrdU incorporating nuclei were assessed by simple counting, whereas morphometric analysis of AgNOR counts was computer aided. Both methods revealed an increase in the number of proliferating cells, a plateau phase being reached after about 36 hours, followed by a decline after about 70 hours. Both methods thus allowed a reliable temporal classification of the skin injury according to survival time. The molecular background of the AgNOR changes in relation to the proliferation of cellular elements is discussed in detail.

Morphometric analysis of argyrophilic nucleolar organizer regions (AgNORs) in nasopharyngeal carcinoma

BACKGROUND

Nucleolar organizer regions (NORs), which are loops of DNA containing ribosomal RNA genes, have been shown to correlate with cell proliferation and malignant transformation. Conventional eyeball measurement of silver staining NORs (AgNORs) is time-consuming and subject to error. The diagnostic value of AgNOR area in nasopharyngeal carcinoma (NPC) by computer-assisted morphometric analysis is evaluated.

METHODS

Silver-staining of NORs was applied to 23 paraffin sections of NPC containing both normal squamous epithelial and malignant cells. Various parameters of the AgNORs of these two cell types were analyzed by a computer-assisted image analysis system and then compared.

RESULTS

The mean AgNOR area, AgNOR/nuclear area ratio, and AgNOR area/count ratio of malignant tumors were statistically significantly higher than those for the normal epithelium. There was no significant difference in the AgNOR counts between the two cell types.

CONCLUSIONS

Computer-assisted morphometric analysis of AgNOR is an objective and reliable assessment method applicable to paraffin sections of NPC. The AgNOR area and its derivatives may aid in the diagnosis of NPC.

Mutations in the beta-propeller domain of the Drosophila brain tumor (brat) protein induce neoplasm in the larval brain

Inactivation of both alleles of the fruit fly D. melanogaster brain tumor (brat) gene results in the production of a tumor-like neoplasm in the larval brain, and lethality in the larval third instar and pupal stages. We cloned the brat gene from a transposon-tagged allele and identified its gene product. brat encodes for an 1037 amino acid protein with an N-terminal B-boxl zinc finger followed by a B-box2 zinc finger, a coiled-coil domain, and a C-terminal beta-propeller domain with six blades. All these motifs are known to mediate protein-protein interactions. Sequence analysis of four brat alleles revealed that all of them are mutated at the beta-propeller domain. The clustering of mutations in this domain strongly suggests that it has a crucial role in the normal function of Brat, and defines a novel protein motif involved in tumor suppression activity. The brat gene is expressed in the embryonic central and peripheral nervous systems including the embryonic brain. In third instar larva brat expression was detected in the larval central nervous system including the brain and the ventral ganglion, in two glands - the ring gland and the salivary gland, and in parts of the foregut - the gastric caecae and the proventriculus. A second brat-like gene was found in D. melanogaster, and homologs were identified in the nematode, mouse, rat, and human. Accumulated data suggests that Brat may regulate proliferation and differentiation by secretion/transport-mediated processes.

Evaluation of argyrophilic nucleolar organiser regions (AgNORs) in multiple myeloma

AIM

To investigate the prognostic value of argyrophylic nucleolar organiser regions (AgNORs) in multiple myeloma.

METHODS

Bone marrow aspirates from 55 newly diagnosed patients with multiple myeloma were stained with the one step AgNO3 technique. The mean number of AgNORs in each plasma cell nucleus (AgNOR count) was tested for a possible correlation with other clinical and laboratory variables at presentation (clinical stage, substage, heavy and light chain isotype, haemoglobin concentration, platelet count, marrow infiltration rate, degree of skeletal lesions, M protein concentration, plasma cell morphology, and serum concentrations of calcium, albumin, lactate dehydrogenase, C reactive protein, and beta 2 microglobulin) and with outcome (response to first line treatment, first remission duration, and overall survival).

RESULTS

A significant association between mean (SD) AgNOR count was found only for clinical stage (stage I, 3.09 (1.19); stage II, 3.80 (1.53); stage III, 5.28 (1.79); p < 0.005) and, from all stage determinants, only for M protein concentration (high, 5.92 (1.80); low, 4.01 (1.92); p < 0.001). There was a linear relation between AgNOR count and serum M protein concentration for patients with both IgG (r = 0.450; p < 0.01) and IgA (r = 0.768; p < 0.002) producing multiple myeloma.

CONCLUSIONS

Unlike previous investigations, no clear prognostic value for the AgNOR count was found in multiple myeloma. Instead, the results indicate that the AgNOR count might be an index for M protein synthesis rate. This is consistent with other findings in tissues with low proliferative potential and high protein synthetic activity, and calls for a cautious interpretation of AgNORs in malignancies with similar features.

Prognostic relevance of AgNORs in tumor pathology

The importance of the analysis of the silver-stained nucleolar organizer regions (AgNORs) for prognostic purposes in tumor pathology has been reviewed. Current available data from the literature demonstrate that the evaluation of the quantity of interphase AgNORs is an independent prognostic factor in several types of human tumors. Results of our investigations indicate that AgNORs are the most powerful variable predicting survival in patients with pharyngeal carcinoma, multiple myeloma, male breast and prostate carcinoma. The combination of AgNOR counts and histologic pattern allows the stratification of patients with multiple myeloma, pharyngeal and prostate carcinoma into low- and high-risk groups, which could benefit from different therapy. Moreover, AgNOR analysis predicts response to treatment in adult patients with acute myelogenous leukemia, and appears as an independent prognostic factor in a prospective study on renal cell carcinoma. Therefore, AgNOR analysis is a really important prognostic factor for several human neoplasias. The experimental and theoretical justifications for AgNORs as a prognostic factor are also reviewed, in particular the strict correlation between AgNOR quantity and tumor cell doubling time. Lastly, the lack of prognostic significance of AgNOR analysis in some circumstances is critically discussed.

Incidence of nucleoli in erythroblasts in patients suffering from refractory anemia of myelodysplastic syndrome

Nucleoli of erythroblasts have been studied in patients suffering from refractory anemia (RA) of myelodysplastic syndrome (MDS) and in control patients without a disturbed erythropoiesis in order to provide information on the incidence of nucleoli and micronucleoli in these cells. Nucleoli in erythroblasts were visualized by a simple cytochemical procedure for the demonstration of RNA which facilitated the visualization not only large nucleoli but also micronucleoli in advanced stages of the erythroblastic maturation. In control patients nucleoli were detected in all stages of erythroblastic development. In patients suffering from RA of MDS, a relatively large population of polychromatic and orthochromatic erythroblasts was characterized by a loss of nucleoli accompanied by the decreased incidence of micronucleoli characteristic of these cells. In contrast to control patients, in patients suffering from RA of MDS the number of nucleoli expressed by the values of the nucleolar coefficient of erythroblasts was smaller, particularly in both the early and terminal stages of erythroblastic development. Thus in patients with RA of MDS both the abnormal loss of nucleoli and decreased number of nucleoli in erythroblasts apparently represent and reflect a further abnormality of disturbed erythropoiesis.

Effective treatment of advanced estrogen-independent MXT mouse mammary cancers with targeted cytotoxic LH-RH analogs

Cytotoxic agents linked to hormonal carriers provide new approaches to tumor therapy, and LH-RH receptors expressed by breast cancers can be used for targeting chemotherapeutic compounds. In the present study, large, advanced estrogen-independent MXT mouse mammary cancers were treated with cytotoxic LH-RH analog AN-152 containing doxorubicin (DOX) or AN-207 incorporating superactive derivative 2-pyrrolino-DOX (AN-201). These cytotoxic hybrid molecules were administered once i.v., close to their maximum tolerated doses, at various time intervals after transplantation of tumors. The cytotoxic LH-RH analogs and the radicals alone, given at earlier stages of tumor development, inhibited growth of MXT cancers. Cytotoxic LH-RH conjugate AN-207 had significantly stronger effect than its respective cytotoxic radical, particularly when larger tumors were treated, causing 95%, 89%, 100% and 96% tumor growth reduction when administered on days 1, 7, 10 or 14, respectively. AN-152, AN-201, and DOX, given on day 14, were virtually ineffective. Histological characteristics of tumor cell proliferation and cell death were analyzed in large MXT cancers 1-4 days after treatment with AN-207 and AN-201. AgNOR scores were decreased and apoptotic indices increased after treatment of tumors with AN-207 or AN-201, but enhanced apoptosis and decreased AgNOR numbers persisted longer in the case of AN-207. In contrast to AN-201, AN-207 also increased the extent of necrosis in tumors. In conclusion, on the basis of its powerful inhibitory effect on the aggressive MXT mouse mammary tumor, the cytotoxic LH-RH analog AN-207 could be considered for treatment of advanced human mammary carcinomas that express LH-RH receptors.

Standardized in situ AgNOR analysis in breast pathology: diagnostic and cell kinetic implications

The aim of the present study was to assess the diagnostic value of the recently standardized morphometric analysis of silver-stained nucleolar organizer region-associated proteins (AgNORs) [30] in a variety of 155 routinely processed benign and malignant breast lesions. 5 normal breast samples, 21 adenoses, 20 ductal hyperplasias, 10 atypical ductal hyperplasias, 20 in situ and 43 invasive ductal carcinomas, 10 in situ and 26 invasive lobular carcinomas were investigated. A statistically highly significant difference was found between normal/ordinary hyperplastic and neoplastic breast lesions with all 4 consensus AgNOR parameters (mean area, mean number, CV of area, CV of number) evaluated. AgNOR quantity was significantly related to histological grade of both in situ and invasive carcinomas. However, variable overlap was found between AgNOR values in different diagnostic groups. We conclude that standardized AgNOR analysis is a prerequisite for objective and reproductible AgNOR assessment in archival tissues. Despite its limited diagnostic utility for individual breast lesions, standardized AgNOR analysis bears a significant potential for characterizing cell kinetic and metabolical activity of breast lesions. This may give insight into the biological background of breast carcinogenesis, differentiation and tumor progression and may also underlie the independent prognostic value of AgNORs in breast cancer.

The prognostic significance of AgNOR counts and PCNA-positive cell counts in canine malignant lymphomas

The behaviour of canine malignant lymphomas is difficult to predict on the basis of histomorphology alone, but the majority of such tumours are "high-grade" by most classifications. The aim of this study was to examine the prognostic significance of argyrophilic nucleolar organizer region (AgNOR) counts and of proliferating cell nuclear antigen (PCNA)-positive cell counts in canine malignant lymphomas; and to relate the results to the histological grade (Kiel classification) and to the survival time of treated and untreated dogs. Low- and high-grade malignant lymphomas differed significantly in having mean AgNOR counts of 3.3 and 5.7 respectively. Untreated dogs with a mean AgNOR count higher than 5.5 did not survive more than 85 days; the median survival time for this group was 38.5 days. Untreated dogs with a mean AgNOR count lower than 4.0 survived at least 82 days and one dog more than 300 days; the median survival time for this group was 154 days. Treated dogs with a mean AgNOR count higher than 5.5 did not survive more than 126 days; the median survival time for this group was 73.5 days. Treated dogs with a mean AgNOR count lower than 4.0 had a median survival time of 205.5 days and one dog survived 367 days. The mean AgNOR count would seem to be a valuable prognostic marker for canine malignant lymphomas, but PCNA counts had no prognostic significance in relation to the median survival time in treated or untreated dogs.

ncl-1 is required for the regulation of cell size and ribosomal RNA synthesis in Caenorhabditis elegans

Regulation of ribosome synthesis is an essential aspect of growth control. Thus far, little is known about the factors that control and coordinate these processes. We show here that the Caenorhabditis elegans gene ncl-1 encodes a zinc finger protein and may be a repressor of RNA polymerase I and III transcription and an inhibitor of cell growth. Loss of function mutations in ncl-1, previously shown to result in enlarged nucleoli, result in increased rates of rRNA and 5S RNA transcription and enlarged cells. Furthermore, ncl-1 adult worms are larger, have more protein, and have twice as much rRNA as wild-type worms. Localization studies show that the level of NCL-1 protein is independently regulated in different cells of the embryo. In wild-type embryos, cells with the largest nucleoli have the lowest level of NCL-1 protein. Based on these results we propose that ncl-1 is a repressor of ribosome synthesis and cell growth.

Argyrophilic nucleolar organiser regions (AgNORs) count as indicator of post-surgical prognosis in feline mammary carcinomas

Feline mammary carcinomas (FMC) were surgically resected from 51 cats to verify that the nucleolar organiser regions (AgNORs) count is related to the post-surgical survival time (PST). After one year post-surgery, 27 cats (group A) were still alive (52.9 per cent) while (41.7 per cent) (group B) had died as a consequence of FMC. Formalin-fixed, paraffin wax-embedded histological sections were stained with silver nitrate and the AgNORs were then counted at x 100 oil immersion objective. In FMC AgNORs count ranged from 1.2 to 12.1 (6.10+/-2.3). A statistically significant difference (P=0.000112) in the AgNORs count was found between cats from group A and group B. No other statistically significant differences were found between group A and B. AgNORs count was not correlated to age or different histological type, according to the WHO classification. Using this technique it is possible to identify two populations of FMC with a statistically significant difference in the PST.

Correlations between mitotic and apoptotic indices, number of interphase NORs, and histological grading in squamous cell lung cancer

Proliferative activity of tumors is strongly associated with prognosis and response to therapy. The reason for faster and uncontrolled growth rate of tumors compared with normal tissue may be caused by the greater proliferation of cells, the smaller rate of cell death, or both. Cell production vs. cell loss rates, and their correlation with a grade of tumor cell differentiation (G) was estimated in 45 cases of squamous cell lung cancers (SCLC) by the use of mitotic indices (MI), number of interphase NORs, and apoptotic indices (AI) as parameters. The mitotic figures as well as apoptotic cells were observed on paraffin sections (4-microm thick) stained with haematoxylin and eosin, and with Feulgen reaction with Schiff-type reagent containing 0.5% Toluidine Blue. According to our results, all three parameters distinguish significantly (P < 0.05) between well and moderately or poorly differentiated groups, but not between the first two groups, and clearly discriminate between low- and high-grade malignancy. These results suggest classification of squamous cell lung cancers into two groups, a group of low and a group of high proliferative activity, despite their morphological appearance. Regression analysis revealed a significant (P < 0.0005) correlation between MI and AgNOR counts per cell nucleus as proliferative markers and AI as a marker of cell loss. The number of mitoses and apoptoses, especially when they are expressed as a percentage of the total number of tumor cells, are markers of tumor proliferation rate. They both can be used in biofunctional staging, based on cell kinetics, to provide more prognostic information about lung cancers than clinicopathological staging.

Proliferative activity in peripheral ossifying fibroma and ossifying fibroma

A proliferative activity study analysing morphometric and quantitative aspects of nucleolar organizer regions (NORs) and proliferating cell nuclear antigen (PCNA) expression was conducted in 10 cases of peripheral ossifying fibroma (POF) and 10 cases of ossifying fibroma (OF). For NOR identification, the silver staining technique (AgNOR technique) was used. PCNA expression was determined by immunohistochemical staining using the PC10 antibody. The AgNOR analysis for the two lesions showed a profile characteristic of benign lesions. OF showed higher AgNOR number and PCNA expression than POF. Our results suggest increased proliferative activity in OF compared with POF.

Silver staining method for nucleolar organizer regions in cervical smears

The distribution of nucleolar organizer regions (NORs) was studied in Papanicolaou preparations of cervical smears in order to distinguish benign from preneoplastic lesions. Destained smears (six defined as normal, six as inflammatory with squamous metaplasia, six as CIN I, six as CIN II, and five as CIN III) were submitted to the Ag-NOR method after staining with Orange G and EA36. Ag-NOR count was performed in previously outlined fields on the smears. Statistically significant differences (P < .05) were found between the normal smears, inflammatory smears with squamous metaplasia, and each grade of CIN. We conclude that the Ag-NOR technique could be useful to evaluate cervical smears of doubtful interpretation, using previous demarcation of the abnormal fields/cells.

The AgNoR count in ulcerative colitis with and without dysplasia

The numbers of specific intranuclear AgNOR silver precipitates (AgNORs) and their relation to the Inflammatory Bowel Disease-Dysplasia Morphology Study Group's classification were studied in 134 colonscopic biopsy specimens of ulcerative colitis (UC) with and without dysplastic findings from 73 patients with active and inactive disease. In addition, 40 cases of colonic adenocarcinomas and 22 normal colonic mucosae were also assessed for comparison with the one-step silver staining AgNOR technique. Statistical comparison of the mean AgNOR number revealed a highly significant inter-class difference (P < 0.001) between UC without dysplasia and UC with dysplasia as well as between active and inactive UC. On the contrary, the AgNORs count did not separate colonic adenocarcinomas from UC with dysplasia either high or low grade nor these three classes from the group of UC with indefinite dysplasia. The quantitative evaluation of epithelial changes occurring in UC by the AgNOR method may help to establish the clinical management of colitis patients, in addition to qualitative morphological criteria.

Morphometric study of nucleolar organiser regions in ameloblastoma and basal cell carcinoma

Ameloblastoma and basal cell carcinoma share histological similarities. Morphometric analysis of nucleolar organiser regions (NORs) from ameloblastoma and basal cell carcinoma (BCC) was carried out by silver (Ag) staining. Mean counts were lower in ameloblastoma (1.652 +/- 0.032) compared to those in BCC (2.354 +/- 0.054). Ameloblastoma presented one or two NORs per nucleus, in a narrow distribution (one to four NORs per nucleus). In contrast, BCC exhibited two or three NORs per nucleus, in a broad distribution (one to six NORs per nucleus). Perimeter and area measurements of AgNOR dots yielded significantly higher mean values for ameloblastoma. Our data suggest that most BCC cells are in mitosis, showing small and numerous NORs in each nucleus, while ameloblastoma cells are in interphase, showing one or two large NORs in each nucleus. Although ameloblastoma and BCC are neoplasms with similar growth patterns, they have cell populations with statistically significant differences in AgNOR patterns.

Studies on the proliferative activity of diethylnitrosamine-induced hepatocellular carcinomas in monkeys

In this study, synthetic phase fractions (SPFs) determined by flow cytometry and AgNOR counts were analysed in benign liver lesions (regenerative nodules and adenomas), hepatocellular carcinomas (HCCs), and lung metastases of a monkey hepatocarcinogenesis model to find out if AgNOR counts and SPFs can discriminate between malignant and non-malignant liver lesions. The average per cent SPF values and the AgNOR counts were significantly (P = 0.001) increased in regenerative liver nodules (5.30 per cent; 4.96), adenomas (5.34 per cent; 3.46) and well-differentiated HCCs (6.75 per cent; 4.47), compared with the untreated control livers (3.18 per cent; 0.98), but the differences between these three groups were not significant. In the poorly differentiated HCC group, however, the average SPF value (9.60 per cent) and AgNOR count (7.14) were significantly higher than in any of the other liver lesions examined. A significant correlation was found between the SPF values and AgNOR counts on the one hand, and differentiation and cytological grade of the HCC samples on the other. The results of this study show that the SPF values and AgNOR counts are not reliable in differentiating between regenerating liver nodules, adenomas, and experimental well-differentiated HCCs. The SPF value, however, may serve as a prognostic factor in HCC, since it was found to be significantly higher in HCCs with lung metastasis than in those without.

Argyrophilic nucleolar organizer regions staining is useful in predicting recurrence-free interval in oral tongue and floor of mouth squamous cell carcinoma

BACKGROUND

Argyrophilic nucleolar organizer regions (AgNORs) represent a tissue marker of cell proliferative activity. The purpose of this study was to assess the prognostic value of AgNORs expression in oral squamous cell carcinoma (SCC).

METHODS

The AgNORs area/nucleus was studied in paraffin sections by means of digital image analysis in 43 cases of stage II oral tongue and floor of the mouth SCC.

RESULTS

Time free of disease was considered a dependent variable of a binary indicator of AgNORs expression (7.77 microns2/nucleus as a cut-off point). High AgNORs level was associated with a statistically significant negative effect on recurrence-free interval of disease in a Cox proportional hazards models controlled for occult lymph node metastasis, involvement of the surgical margins, thickness of the lesion, and vascular invasion.

CONCLUSIONS

The AgNORs area increased the capability of predicting which patients have a high risk of recurrence of cancer, and its evaluation may provide useful information for the therapeutic approach to the oral tongue and floor of the mouth SCC.

Estrogen receptors, progesterone receptors, and cell proliferation in human breast cancer

The breast is a target organ for estrogens and progesterone. These hormones control several functions of the normal and abnormal mammary epithelium including cell proliferation. Most of the actions of estrogens and progesterone are mediated via specific steroid receptors, and one would expect that proliferating cells should contain estrogen receptors (ER) and/or progesterone receptors (PR). However, the correlation between receptor expression and cell proliferation is still controversial. In the present study we have examined 29 human breast cancer samples; in 17 of them we evaluated the simultaneous ER and PR localization with that of proliferating cell nuclear antigen (PCNA) and silver-stained nucleolar organizer regions (AgNORs) in a cell-by-cell study. We found that in almost 50% of the tumor biopsies examined, the cells expressing ER were significantly associated with elevated cell proliferation. In another group (38%) there were not significant differences between ER expression and cell proliferation. In only one of the samples (6%) the cells expressing ER showed lower cell proliferation. The study also revealed that in 44% of the tumors the PR expressing cells were associated with elevated cell proliferation. In a second group the PR expression was not significantly associated with cell proliferation (33% of the cases). Finally, in 22% of the samples the cells carrying PR showed lower cell proliferation. We also detected lower ER immunoreactivity in 30% of the breast cancer biopsies with one of the monoclonal antibodies against ER (antibody 1D5 directed against the A/B domain). This group of tumors was PR-negative (or very weakly positive) and had high proliferation. The presence of tumors with 'abnormal' ER proteins and displaying ER/PR significantly associated with elevated cell proliferation could have implications in human breast cancer treatment.

Standardized AgNOR analysis: its usefulness in surgical oncology

Recent improvements both in the staining quality and computer-aided quantitation of silver-stained nucleolar organizer region (AgNOR)-associated proteins offer the possibility to reliably investigate these proteins on routinely processed archival material. This article deals with the historical background, the recent introduction of a standardized quantitation, the clinical relevance, and future perspective for AgNOR evaluation. It is specifically emphasized that AgNOR analysis after both standardized staining and computer-aided quantitation (as recommended by the Committee on AgNOR Quantitation of the European Society of Pathology) is now regarded as the gold standard whenever routinely formalin-fixed and paraffin-embedded material is investigated.

Demonstration of silver-stained nucleolar organizer region associated proteins (AgNORs) after wet autoclave pretreatment in breast carcinoma: correlation to tumor stage and long-term survival

Argyrophilic nucleolar organizer region associated proteins (AgNORs) are known to reflect cellular and nucleolar activity. Due to a novel staining procedure, which substantially improves visualisation of AgNORs on formalin-fixed and paraffin-embedded material, AgNORs can be reliably demonstrated as true substructures of the nucleoli. The aim of the present study was to apply a standardized morphometric AgNOR quantification on a large series of breast carcinomas with regard to its prognostic relevance. AgNOR quantity was evaluated on archival tumor tissues of 115 adenocarcinomas of the breast treated with the wet autoclave method prior to standardized silver-staining and morphometric analysis. AgNOR parameters were correlated to prognostic features (steroid hormonal receptor status, tumor type, tumor size, histological grading, pTNM, and UICC stage) carrying out both univariate and multivariate survival analyses. AgNOR number and area were proven to be statistically significantly related (Pearson correlation coefficient: 0.67, Bonferroni adjusted P = 0.0001). Almost all AgNOR parameters, in particular CV (coefficient of variation) of corrected area (delta-area) and CV of number, were statistically significantly correlated to estrogen and progesterone receptor status as well as histological grading of tumors. Increased AgNOR parameters were statistically significantly associated with early tumor relapse and cancer related death. Univariate and multivariate analysis by means of Cox regression revealed independent prognostic significance for CV of delta-area and number of AgNORs. Various AgNOR parameters (CV of number, CV of delta-area, CV of area, mean delta-area, and mean area of AgNORs per nucleus) determined on wet autoclave pre-treated formalin-fixed and paraffin-embedded breast cancer tissues are statistically highly significantly associated with the prognostic outcome, independently predicting tumor-free and overall survival.

Effect of a cytotoxic analog of LH-RH (T-98) on the growth of estrogen-dependent MXT mouse mammary cancers: correlations between growth characteristics and EGF receptor content of tumors

Female BDF mice bearing estrogen-dependent MXT mouse mammary cancers were treated for 4 weeks with a cytotoxic analog of luteinizing hormone-releasing hormone (LH-RH). T-98 (agonist [D-Lys6]LH-RH linked to glutaryl-2(hydroxymethyl)anthraquinone). The effects of T-98 were compared to those of equimolar amounts of the cytotoxic moiety 2-(hydroxymethyl)anthraquinone hemiglutarate (G-HMAQ) and carrier LH-RH agonist [D-Lys6]LH-RH. Both T-98 and [D-Lys6]LH-RH significantly inhibited the growth of MXT cancers, but G-HMAQ had only a minor non-significant effect. Cytotoxic analog T-98 and the carrier [D-Lys6]LH-RH had similar inhibitory hormonal activities on the pituitary-gonadal axis, but T-98 caused a larger reduction in tumor volume and decreased proliferation characteristics such as mitotic activity and AgNOR numbers in tumor cells to a greater extent than the carrier. Tumor inhibition by T-98, [D-Lys6]LH-RH, and ovariectomy was connected with a significant decrease in binding capacity of EGF receptors in tumor cell membranes. The concentration of EGF receptors remained high in tumors that continued to enlarge in spite of treatment and in all control untreated tumors, even those of small size. Thus, the changes in EGF receptors are likely to be the result of the therapy. Treatment with T-98 caused a greater reduction in the binding capacity of EGF receptors in tumors than [D-Lys6]LH-RH. This could explain the higher inhibitory effect of the cytotoxic analog on tumor growth. Since radiolabeled T-98 was shown to accumulate in MXT cancers 3 hours after a subcutaneous injection, this indicates that specific targeting might play a role in the antitumor effect exerted by this cytotoxic analog.

Gallbladder carcinoma: a video image analysis of AgNOR distribution and its relation to tumour stage and grade

The amount and distribution of interphase argyrophilic nucleolar organizer regions (AgNORs) was studied in 51 gallbladder surgical specimens including 32 primary carcinomas, 10 adenomas and 9 cases of chronic cholecystitis with calculi. The mean nuclear AgNOR area (NORA) and the AgNOR distribution score (NORDS), i.e. the percentage of cells carrying nucleolar aggregates with more than 6 distinct silver dots, were evaluated in 200 epithelial nuclei per specimen by means of automated image analysis and direct counting respectively. Statistical analysis (variance analysis and Student-Neuman-Keuls' test) performed on the pooled mean AgNOR values showed a significant difference (p < 0.001) between carcinomas and non-carcinomatous lesions. Both NORA and NORDS highly discriminated carcinomas with histopathological grade 4 versus cases with grade 1, 2 or 3 (p < 0.001); a less statistically significative p value (< 0.05) was encountered when NORDS values of well differentiated grade 1 carcinomas and adenomas were compared. The NORA parameter permitted the discrimination of stage IV versus stage I carcinomas (p < 0.001), while carcinomas in stage IV and those in stage II were distinguished with a p < 0.05; the NORDS parameter allowed also to distinguish stage IV from both stage I or II tumours (p < 0.001). Our results indicate that the above-mentioned AgNOR parameters may be utilized as additional, more objective quantitative criteria in the clinical-pathological assessment of the outcome of gallbladder carcinomas.

Enzymatic cytochemistry, DNA ploidy and AgNOR quantitation in hepatocellular nodules of uncertain malignant potential in liver cirrhosis

Conventional histological examination of echo-guided biopsy specimens can be inconclusive in small nodular lesions in cirrhotic livers. We investigated the diagnostic potential of cytochemical analysis of dipeptidyl-peptidase IV (DPP IV), of image analysis of nuclear DNA content, and of interphase silver-stained nucleolar organizer regions (AgNORs) in 12 cases of small (13- to 29-mm in diameter) hepatic nodules visualized in cirrhotic patients by ultrasonography. All cases underwent an echo-guided liver biopsy at the time of detection and in none of them were histological signs of malignancy found. Characterization with the above-mentioned techniques was always done at the time of histological examination. These patients underwent a mean (+/- SD) follow-up of 27.0 (+/- 11.2) months after biopsy, with repeated ultrasound (US) examinations. In the seven patients with subsequent neoplastic growth, DPP IV score was altered in five of six; the fraction of mononucleated polyploid cells was altered in six of seven; and the AgNOR quantity exceeded the cutoff value of 4 microns2 in five of five cases. Among the five lesions whose US appearance remained unchanged during the follow-up, only one abnormality (AgNORs) was found in one case. The combined cytochemical analysis of DPP IV, nuclear DNA content, and quantitative evaluation of interphase AgNORs in biopsy samples may contribute to the differential diagnosis of hepatocellular nodules of uncertain type in the cirrhotic liver.

Correlation of two argyrophilic nucleolar organizer region counting methods with the Ki-67 labeling index in uterine smooth muscle cell tumors

The argyrophilic nucleolar organizer regions (AgNOR) are silver stained granules that are thought to correlate with cell proliferation activity. Two AgNOR counting methods: the mean AgNOR count (mAgNOR, the mean number of AgNOR granules in 100 cells) and the AgNOR proliferative index (pAgNOR, the percentage of cells exhibiting five or more AgNOR granules per nuclei) have been proposed. In this study, the two counting methods were applied to 58 cases of normal uterine corpus and uterine corpus tumors and were compared with the Ki-67 labeling index (Ki-67 LI) using MIB-1 monoclonal antibody and other histopathological criteria. Notable differences in the number of AgNOR and the Ki-67 LI were observed between benign and malignant smooth muscle tissue. Histopathologic features are well correlated to the proliferative activity of tumors. Although the most reliable method of predicting malignant potential cannot be determined, the methods outlined by this study are thought to be highly useful in assessing proliferative activities.

In hepatocellular carcinoma AgNOR protein expression correlates with tumour mass doubling time

AIMS/METHODS

The relationship between AgNOR protein expression and doubling time was evaluated in 20 untreated nodules of hepatocellular carcinoma arising in cirrhotic liver. AgNOR protein quantity within the lesion was defined by image cytometry on histological sections from frozen biopsies obtained under ultrasound-guidance, selectively stained for AgNOR proteins. Tumour doubling time was calculated 6 months after diagnosis by measuring the volume variations of the nodules over a fixed period by "real time" ultrasonography.

RESULTS

The doubling time of nodules characterized by high AgNOR protein area values (> 5.50 microns2, corresponding to the median AgNOR protein value) was shorter than that of nodules with low AgNOR protein area values (< 5.50 microns2). A highly significant difference in the mean doubling time values between the two groups (6.31 +/- 2.68 (E.S.) versus 15.92 +/- 3.03 (E.S.) months, respectively; p = 0.009) was found. Moreover, when the relationship between AgNOR protein and doubling time values was tested by linear regression analysis, a significant inverse correlation was observed (r = -0.68; p < 0.005).

CONCLUSIONS

Our results indicate that AgNOR protein quantity represents a reliable parameter for predicting the tumour growth rate of untreated hepatocellular carcinoma nodules. Among the procedures commonly employed for the assessment of cell proliferation, the evaluation of the AgNOR parameter seems to be particularly suitable for kinetic analysis of ultrasound-guided fine-needle liver biopsies.

Changes of nucleolar organizer regions in granulopoietic precursors during the course of chronic myeloid leukemia

The aim of the present study was to analyze the nucleolar organizer region (AgNOR) pattern of granulopoietic precursors in chronic myeloid leukemia (CML) at diagnosis and during the course of the disease. Clusters of AgNORs and isolated dots were counted separately in 24 cases of CML at diagnosis, in 19 cases during the relapse of the chronic phase after treatment, and in 16 cases of blast crisis. For comparison, 20 cases of normal bone marrow were studied. Each cell type had its own characteristic AgNOR pattern, as has been described for normal bone marrow. There was no significant difference in the number of AgNORs between cells in the peripheral blood and bone marrow. Compared with normal granulopoiesis, myeloblasts in CML at diagnosis had lower numbers of clusters, which decreased further during relapse of chronic phase and in blast crisis. Promyelocytes and myelocytes showed significantly fewer dots. The number of AgNOR clusters correlates inversely with the duration of the cell cycle. Therefore, these findings are consistent with the progressive loss in proliferative activity of immature precursors described during the course of CML. As the number of dots indicates cellular maturation, their lower number in promyelocytes and myelocytes in CML favors the concept of a discordant maturation process described in this disease. The separate counting of clusters and dots provides a useful, simple, and cheap method of describing cytokinetic changes during the course of this myeloproliferative disorder.

Cell proliferation in lung fibrosis-associated hyperplastic lesions

1. Cell proliferative activity of atypical bronchioalveolar epithelia in lung fibrosis cases treated with bleomycin (BLM) or radiation was investigated by studying the histochemistry of the argyrophil nucleolar organiser regions (AgNORs) and proliferating cell nuclear antigen (PCNA). 2. Five and 14 autopsy cases of individuals who died of pulmonary fibrosis, caused by BLM treatment and irradiation respectively, were compared with (i) six control subjects who proved to have no apparent fibrosis of the lung at autopsy and (ii) four lung squamous cell carcinoma cases. 3. Histopathologically, both the BLM-treated and irradiated cases showed extensive collapse of the lung caused by severe fibrosis, although proliferative epithelial lesions such as atypical bronchioloalveolar hyperplasia and squamous metaplasia were more prominent in the former. 4. The mean AgNOR numbers in both atypical hyperplasias and metaplasias, of either BLM or irradiation cases, were significantly higher than in control bronchioalveolar epithelial areas, whereas they were lower than in the lung cancers. Data for PCNA-labelling indices were in time with those for AgNORs. 5. The results indicate that atypical hyperplastic lesions in the bronchioloalveoli arising during the fibrosing process as induced by BLM, and by irradiation, are highly proliferative.

Silver-stained nucleolar (Ag-NOR) cluster size in feline mammary carcinomas: lack of correlation with histological appearance, mitotic activity, tumour stage, and degree of nuclear atypia

The relationship between Ag-NOR cluster size, mitotic index, tumour stage, degree of nuclear atypia and histological appearance was evaluated in a series of feline mammary carcinomas. The mean Ag-NOR cluster area per cell in these tumours ranged from 1.86 to 6.25 microns 2 and was not related to any other parameter studied. This suggests that Ag-NOR cluster size measurement is of poor diagnostic and prognostic value for feline mammary carcinomas.

Assessment of the nucleolar organizer regions by automated image analysis in benign and malignant colonic tumours and adjacent tissues in rats

An automated computer image analysis technique was used to study the morphological parameters of argyrophilic nucleolar organizer regions (AgNORs) in chemically induced rat colonic tumours of different grades. Different nuclear parameters were of different diagnostic value. For distinguishing tumorous tissue from normal tissue all the parameters studied were capable of serving as diagnostic markers. Malignant processes could, however, be more reliably detected by means of the area of the nucleus, nuclear shape factor, area of AgNOR and ratio of AgNOR area to nuclear area. In macroscopically normal tissue adjacent to a tumour, the values of all the AgNOR parameters studied were similar to those in tumorous tissues. It can be concluded that the initial stages in tumorigenesis are accompanied by changes in all of the nucleus and AgNOR parameters, but as malignancy develops, only some of these parameters continue to change. Close correlations between nuclear parameters in malignant tissue suggest that for diagnostic purposes only nuclear and AgNOR areas should be used.

Bone Hemangioendothelioma: An Immunohistochemical Study Related to Histological Malignancy and Proliferative Activity (NORs)

Aims and Background

Forty-four bone hemangioendotheliomas (HEs) of different histological grades were studied to evaluate the expression and distribution of laminin, type IV collagen, cathepsin G and cathepsin D in cell differentiation and malignancy.

Results

In poorly-differentiated HEs the discontinuous distribution of laminin and type IV collagen around angioblastic cords, tubes and cavities revealed an irregular and disorganized basement membrane (BM) architecture corresponding to an increased cell proliferation and secretion of cathepsin D and cathepsin G by tumor cells.

Conclusions

The mean nucleolar organizer region (NOR) area, as a measure of cell proliferation, was significantly higher in grade 4 malignancies than in lower grades, revealing novel prognostic parameters.

Quantification of nucleolar organiser regions in canine perianal gland tumours

The proliferative activity in 28 canine perianal gland tumours was examined by the quantitative evaluation of the nucleolar organiser regions associated with argyrophil proteins (AgNORs). These regions were stained with a specific silver stain and quantified directly by light microscopy and by computerised image analysis. The relationships between some of the parameters used (the number of AgNORs per nucleus, the area of AgNORs per nucleus and the ratio of the area of AgNORs to the area of the nucleus) were also examined in relation to the histopathological grades of the tumours. All the parameters showed a high correspondence with the tumours' proliferative activity, and the ratio of the area of AgNORs to the area of the nucleus was the most significantly correlated with the tumours' histological patterns.

Standardized staining and analysis of argyrophilic nucleolar organizer region associated proteins (AgNORs) in radically resected colorectal adenocarcinoma--correlation with tumour stage and long-term survival

Quantification of silver-stained nucleolar organizer region associated proteins (AgNORs) was introduced in histopathology as a marker of cellular and nucleolar activity. However, due to the poor staining quality obtained on routinely processed archival material, the method yielded controversial and sometimes non-reproducible results. The recent introduction of wet autoclave pretreatment has reliably improved AgNOR staining quality on routinely formalin-fixed and paraffin-embedded tissues. In the present study, 92 routinely processed colorectal carcinomas were investigated, applying this novel staining technique. Subsequent standardized morphometric analysis revealed, irrespective of common tumour staging or grading classifications, a statistically highly significant correlation between AgNOR parameters and clinical course. The usefulness of standardized AgNOR parameters for the independent prediction of patient survival was proven by uni- and multivariate analysis.

Determination of epidermal proliferative activity in experimental mouse tail test by AgNOR analysis

Nucleolar organizer regions are segments of DNA coding ribosomal genes, which can be histologically detected by silver technique as so-called AgNORs. The estimation of AgNOR number and AgNOR size are currently under investigation as markers of cellular proliferation activity. We therefore examined the epidermal AgNOR expression after topical application of different antiproliferative compounds using the mouse tail test. The epidermis of 0.025% fluocinolone acetonide-treated mouse tails had the lowest AgNOR expression. Pretreatment with 0.2% Anthralin, 1% propyl gallate and 2% 3,4-hexaalkylbenzoylacrylic acid, an experimental phospholipase-A2 inhibitor, also revealed significant inhibition effects of epidermal AgNOR expression. Native and petrolatum-treated epidermis as control showed the highest AgNOR expression. The AgNOR results in basal cells proved to be more informative than these in the stratum spinosum, the best parameter was the AgNOR number. The obtained results were closely related to the values of the corresponding studies of PCNA expression. The AgNOR method seems to be useful for estimation of antiproliferative efficiency of pharmacological substances. This technique is simple in handling and can be applied using paraffin-embedded tissue sections.

Prognostic relevance of pretreatment proliferative rapidity of marrow blast cells in childhood acute lymphoblastic leukaemia

Cell proliferation rate is a well-established prognostic factor in cancer, but it has not been considered to identify the risk group of childhood acute lymphoblastic leukaemia (ALL) at presentation. We carried out a study to demonstrate the prognostic importance of the rapidity of cell proliferation in patients with ALL. To measure the rapidity of cell proliferation we used the parameter relative to the area of silver-stained nucleolar organiser regions (AgNORs) as evaluated by morphometric analysis on smeared marrow blast cells. The mean AgNOR area of leukaemic marrow cells was measured in 119 children. By using a cut-off value of 3 microns2, we identified a group of 91 children with low proliferating blast activity (mean AgNOR value 2.11 microns2) and a group of 28 children with high proliferating activity (mean AgNOR value 3.29 microns2). The group of patients with a mean AgNOR value > 3 microns2 was characterised by a higher number of deaths, more frequent relapse and shorter time interval to relapse than the group of patients with mean AgNOR value < 3 microns2 (P < 0.01). Multivariate analysis performed to include T-cell immunophenotype, FAB morphology, leucocyte count and presence of mediastinal mass showed that the mean AgNOR value was the only independent predictor of unfavourable event-free survival probability (P > 0.01). Our results indicate that the rapidity of marrow blast cell proliferation is an important prognostic parameter in childhood ALL and should be routinely introduced in the group risk definition.