Nucleolar organizer regions in hepatocellular carcinoma related to the cell cycle, cell proliferation and histologic grade

AgNORs count and DNA ploidy in liver biopsies from patients with schistosomal liver cirrhosis and hepatocellular carcinoma

OBJECTIVES

Argyrophilic nucleolar organizer regions (AgNOR) proteins are a set of argyrophilic nucleolar proteins that accumulate in highly proliferating cells, whereas their expression is very low in nonproliferating cells. The present study aimed to investigate the potential of DNA flow cytometry (FCM) and AgNORs count in the assessment of cellular kinetics of liver cirrhosis and hepatocellular carcinoma.

DESIGN AND METHODS

Small-needle liver biopsies (217) were included and were taken from 84 patients with hepatocellular carcinoma (HCC) (one biopsy from tumor lesion and the other from residual nontumor) liver tissues. Only one biopsy was taken from 49 patients with liver cirrhosis. One part of biopsy was subjected to flow cytometry, and the other, to histopathology and AgNORs counting.

RESULTS

An aneuploidy was shown in 44.5% of liver cirrhosis and in 78.6% of tumor sites. Aneuploid HCC cases showed high AgNORs count compared with diploid cases (3.407+/-1.18 vs. 1.74+/-0.9). An extremely significant increase in AgNORs count in tumor lesion (P<0.001) was found compared with residual liver tissues, liver cirrhosis and normal liver (3.89+/-0.827, 1.49+/-0.52, 1.62+/-0.29, and 1.3+/-0.17, respectively). In liver cirrhosis, dysplasia showed a significant relationship with ploidy (P<0.001) and AgNORs count (P<0.05).

CONCLUSION

AgNORs count and DNA ploidy analysis of core biopsy specimens are useful in the assessment of cellular kinetics of liver cirrhosis and hepatocellular carcinoma.

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.

Apoptosis and proliferation in relation to histopathological variables and prognosis in hepatocellular carcinoma

The prognosis of patients with resectable hepatocellular carcinoma depends mainly on the anatomical extent of the tumour and on the general condition of the patient. Given the growing evidence that proliferation indices may be of prognostic significance in hepatocellular carcinomas and that parameters of cell loss (usually, but not exclusively, due to programmed cell death) are biologically relevant, the identification and quantitation of proliferative capacity and apoptosis may be of prognostic importance. In this study four different methods have been used to assess proliferation in a series of 193 curatively (R0) resected hepatocellular carcinomas: mitotic count, immunohistochemical assessment of MIB-1 (Ki-67), proliferating cell nuclear antigen (PCNA), and silver-stained nucleolar organizer regions (AgNORs). Apoptosis was assessed using the in situ-end labelling (ISEL) technique in combination with morphological criteria. Patients who received liver transplantation were excluded. The results obtained were compared with histopathological stage (according to UICC), Edmondson grade, several other histopathological factors, and survival rate. Significant statistical correlations were seen between the mitotic index, the rate of nuclear positivity for MIB-1 and PCNA, and the number of AgNOR dots. In univariate survival analysis, tumour stage and Edmondson grade, mitotic index, MIB-1 and PCNA index, and mean AgNOR number were significant factors influencing patients' survival. On multivariate Cox survival analysis, mitotix index, concomitant cirrhosis, Edmondson grade, and patient age were the only significant independent prognostic factors. Apoptosis was not related to prognosis or to other parameters examined. These results indicated that mitotic index is an additional prognostic parameter which could provide auxiliary information for patients' outcome. MIB-1 and PCNA immunostaining and AgNORs showed a good correlation among themselves. Apoptosis did not predict prognosis in hepatocellular carcinoma.

Ki-67 expression as a prognostic marker in patients with hepatocellular carcinoma

Ki-67 expression in tumours has been shown to be associated with prognosis in patients with hepatocellular carcinoma (HCC). In this study, primary HCC samples were obtained from 67 patients undergoing surgical resection. None of these patients had been subjected previously to any other form of therapy, such as arterial embolization or chemotherapy. Histologically normal liver tissues from liver resection for metastatic colon cancer were taken as controls (n = 8). Monoclonal antibody against Ki-67 was used for immunostaining and flow cytometry was used to measure tumour DNA ploidy. The mean Ki-67 labelling index (percentage of Ki-67-positive cells) of the HCC (26 +/- 22%; range 0.1-89%) was significantly higher than that of the normal controls (39 +/- 0.8%, P < 0.05). The mean Ki-67 labelling index (19 +/- 15%; n = 28) of the tumours with diploid DNA pattern was significantly lower than those with aneuploid DNA pattern (32 +/- 25%, n = 39; P = 0.01). Hepatocellular carcinoma patients (n = 47) with Ki-67 index > 10% had a significantly lower disease-free and overall survival than those (n = 20) with Ki-67 index < or = 10% (P = 0.0009 and P = 0.02, respectively). Multivariate analysis showed that Ki-67 expression and tumour node metastasis stage were two independent prognostic factors for disease-free and overall survival rates. Our results suggest that the expression of Ki-67 is an independent prognostic indicator for patients with HCC after resection and could be of assistance in the decision-making of adjuvant therapy.