Nucleolar organizer region counts predict complete remission, remission duration, and survival in adult acute myelogenous leukemia patients

Analysis of Argyrophilic Nucleolar Organizer Regions (AgNORs) in Acute Leukemia in Adults

The evaluation of argyrophilic nucleolar organizer regions (AgNORs) uses a simple method used in research into neoplasm. Bone marrow aspirates from 70 patients with acute leukemia underwent morphological, immunophenotypic, and genetic assessment and were stained with silver nitrate. In leukemic cells, the mean AgNORs number, mean AgNORs area, and mean AgNOR-area-to-nucleus-area ratio were calculated in patients with acute myeloid leukemia (AML), patients with acute lymphoblastic leukemia (ALL), and selected risk groups. A higher value of all measured AgNOR parameters was observed in patients with AML compared to the ALL group. In AML patients, a higher mean AgNOR area was found in the ELN3 cytogenetic group compared to the ELN2 cytogenetic group. A higher value of the mean AgNOR count was observed in patients with white blood cells (WBCs) > 12 × 109/L than in the group with WBCs ≤ 12 × 109/L, as well as in patients with >20% blasts in peripheral blood (PB) than in patients with ≤20% blasts in PB. In the ALL group, a higher mean AgNOR-area-to-nucleus-area ratio was found in group with the presence of Philadelphia chromosome Ph(+) than without the Philadelphia chromosome Ph(−). AgNOR parameter analysis is a valuable method for differentiation of AML and ALL in adults.

Expression Profiling of Ribosome Biogenesis Factors Reveals Nucleolin as a Novel Potential Marker to Predict Outcome in AML Patients

Acute myeloid leukemia (AML) is a heterogeneous disease. Prognosis is mainly influenced by patient age at diagnosis and cytogenetic alterations, two of the main factors currently used in AML patient risk stratification. However, additional criteria are required to improve the current risk classification and better adapt patient care. In neoplastic cells, ribosome biogenesis is increased to sustain the high proliferation rate and ribosome composition is altered to modulate specific gene expression driving tumorigenesis. Here, we investigated the usage of ribosome biogenesis factors as clinical markers in adult patients with AML. We showed that nucleoli, the nucleus compartments where ribosome production takes place, are modified in AML by analyzing a panel of AML and healthy donor cells using immunofluorescence staining. Using four AML series, including the TCGA dataset, altogether representing a total of about 270 samples, we showed that not all factors involved in ribosome biogenesis have clinical values although ribosome biogenesis is increased in AML. Interestingly, we identified the regulator of ribosome production nucleolin (NCL) as over-expressed in AML blasts. Moreover, we found in two series that high NCL mRNA expression level was associated with a poor overall survival, particular in elderly patients. Multivariate analyses taking into account age and cytogenetic risk indicated that NCL expression in blast cells is an independent marker of reduced survival. Our study identifies NCL as a potential novel prognostic factor in AML. Altogether, our results suggest that the ribosome biogenesis pathway may be of interest as clinical markers in AML.

Multidrug resistance 1 gene expression and AgNOR in childhood acute leukemias

The multidrug resistance 1 (MDR1) gene product, P-glycoprotein (Pgp/p170) is a membrane protein, which acts as an ATP dependant efflux pump that expels a wide variety of organic compounds including chemotherapeutic agents from the cell. Pgp over expression has been demonstrated to be linked with poor treatment outcome and poor prognosis in a number of malignant tumors. AgNORs is a simple, reliable and inexpensive method of evaluating the proliferative activity of a tumor. We have studied MDR1 expression and AgNORS in 41 cases of acute leukemia in children. In this study, AgNOR counts in patients with acute lymphoblastic leukemia (ALL) L2 subtype (FAB classification) were significantly higher as compared to the ALL L1 subtype. Similarly, mean AgNOR count in the acute myeloid Leukemia (AML) M2 subtype was significantly higher as compared to the ALL L1 subtype. However, there was no correlation between AgNOR and treatment outcome or between AgNOR counts and MDR1 expression in any of the subtypes of acute leukemia included in this series. In AML, MDR1 gene expression was found to be related to reduced remission induction rates and hence poorer prognosis. In ALL, our study has shown no difference in remission induction between MDR1 positive and MDR1 negative cases. This would suggest that factors other than MDR1 may be of relevance in Pediatric ALL.

Nucleolus organizer regions (AgNORs) and total tumor mass are independent prognostic parameters for treatment-free period in chronic lymphocytic leukemia

The aim of our study was to evaluate whether the nucleolus organizer regions (AgNOR) of circulating lymphocytes in chronic lymphocytic leukemia (CLL) could predict the duration of the stable phase (treatment-free period) of this disease. Age, sex, peripheral lymphoctes, hemoglobin, platelet count, Binet's stage, total tumor mass (TTM) and AgNOR pattern at diagnosis were assessed in 57 patients and compared with the time from diagnosis until patients fulfilled the criteria to start chemotherapy. In univariate Cox regression, Binet's stage, hemoglobin, number of peripheral lymphocytes, TTM and the percentage of lymphocytes containing one AgNOR cluster (circulating proliferative fraction) had predictive value. In the multivariate Cox model, only TTM and the percentage of cells with one AgNOR cluster were independent factors predicting the duration of the stable phase. Repetition of these analyses in 500 data sets created by bootstrap resampling confirmed the results. Summing up the percentage of lymphocytes with an AgNOR cluster and the TTM value, a simple prognostic index could be created to give information about the duration of the stable phase in CLL.

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.

Nucleolar size indicates the rapidity of cell proliferation in cancer tissues

In order to define the importance of the nucleolus in tumour pathology, the relationship between nucleolar size and function and tumour mass growth rate was studied in vivo. Ten established human cancer cell lines from colon carcinomas and neuroblastomas were inoculated subcutaneously in athymic mice and the doubling time (DT) of the xenograft tumour mass was calculated. The tumour DTs ranged from 3.2 to 15.7 days. Nucleolar size was evaluated in sections from formalin-fixed and paraffin-embedded tumour samples after silver staining for AgNOR proteins, using a specific image analysis system. The nucleolar area values were inversely related to the xenograft tumour mass DTs (r=-0.90; p<0.001). Nucleolar functional activity was also evaluated using rapid, intermediate, and slow growing tumours (one each). The values of RNA polymerase I activity measured in vitro were strongly related to the corresponding tumour DTs (r=-0. 99; p=0.03). The labelling indices (LIs) of three proliferation markers, MIB1, PCNA, and bromodeoxyuridine (BrdU), were also evaluated. As revealed by the MIB1 and PCNA LIs, almost all the cells of the xenograft tumours were cycling (86.6+/-5.6 SD and 95. 5+/-2.0 SD, respectively). Neither the MIB1, PCNA or BrdU LIs were related to the xenograft tumour mass DT, showing that the different growth rates of tumour xenografts were not due to different growth fractions, but were mainly related to different cell proliferation rates. The present data demonstrate that the size and function of the nucleolus are related to the cell proliferation rate of cancer tissue. Evaluation of nucleolar size after silver staining of AgNOR proteins represents a unique parameter for the histological assessment of rapidity of cell proliferation in tumour lesions.

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.