Proliferating cell nuclear antigen (PCNA) immunolocalization in paraffin sections: an index of cell proliferation with evidence of deregulated expression in some neoplasms

Immunoreactivity of proliferating cell nuclear antigen compared with bromodeoxyuridine incorporation in normal and neoplastic rat tissue

Monoclonal antibodies (MoAbs) against proliferating cell nuclear antigen (PCNA) represent a potentially useful tool for cell kinetic analysis of tumours. Because in paraffin-embedded tissue the relationship between PCNA immunoreactivity and tumour cell proliferation is not well characterized, we have compared PCNA positivity as detected by the PC10 MoAb with the bromodeoxyuridine labelling index (BrdUrd-LI) in two different transplantable hormone-dependent rat mammary tumours. Together, these two tumour models (MCR-83 and EMR-86) cover a wide range of S-phase fractions. Evaluating 31 methacarn-fixed tumours, a strong but non-linear relationship (r = 0.98) was obtained. PCNA-positive fractions were invariably higher than corresponding BrdUrd-LIs and also higher than the estimated growth faction: growth fractions as determined by continuous BrdUrd labelling of the tumour and stromal cell population in EMR-86 carcinomas were 12 and 26 per cent lower than PCNA-positive fractions, implying that a certain fraction of non-cycling cells can also express PCNA. A dramatic disturbance in the relationship of PCNA positivity and the BrdUrd-LI was observed in the EMR-86 model after growth arrest induced by hormonal ablation: PCNA immunoreactivity remained detectable for at least 3 days, whereas the BrdUrd-LI decreased almost immediately. In comparison, PCNA immunoreactivity persisted for a much shorter period in small intestinal cells that had stopped DNA replication when moving from the crypt towards the villus. It is concluded that although differences in PCNA expression exist between various tissues, PCNA as detected by the PC10 MoAb may be used in tumours as an operational marker for the growth fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferative activity determined by DNA flow cytometry and proliferating cell nuclear antigen (PCNA) immunohistochemistry as a prognostic factor in prostatic carcinoma

Proliferative activity was measured in 165 paraffin-embedded prostatic carcinomas using DNA flow cytometric analysis of the S-phase (SPF) and G2/M-phase fractions and CAS 200 image analysis of the proliferating cell nuclear antigen (PCNA) expression defined immunohistochemically by PC10 and 19A2 monoclonal antibodies. No significant associations were found between the flow cytometric and the two immunohistochemical measures of cell proliferation. Of the four indices, only SPF, S + G2/M, and immunostaining with 19A2 antibody were associated with the poor histological grade of the tumour. High SPF and S + G2/M were significantly associated with poor 10-year overall survival (P < 0.001) and prostatic carcinoma-specific survival (P < 0.01). Multivariate analyses of prostatic carcinoma-specific survival in patients with non-metastatic disease (M0-stage) indicated that only S + G2/M, T-stage, and histological grade (only if re-evaluated by a single pathologist) had independent prognostic significance. High-level PCNA staining (> 16 per cent of cells stained) with 19A2 antibody was associated with poor prognosis only in univariate analysis, and PC10 immunostaining had no prognostic value. In conclusion, a high proliferative activity as defined by flow cytometric S+G2/M is an independent predictor of poor survival in patients with non-metastatic prostatic carcinoma. PCNA immunostaining from formalin-fixed, paraffin-embedded prostatic carcinomas has little, if any, prognostic value.

Proliferating cell nuclear antigen in malignant and pre-malignant lesions of epithelial origin in the oral cavity and the skin: an immunohistochemical study

Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S phase of the cell cycle and immunohistochemical detection of the protein represents a useful marker for the proliferating fraction of cells in tissue specimens. A series of malignant and pre-malignant lesions of the oral cavity and skin were evaluated by the streptavidin biotin immunoperoxidase method for detection of this protein. Monoclonal anti-PCNA antibody (PC 10) labelled proliferating cells in all cases with varying intensity of nuclear staining. In squamous cell carcinoma (n = 48), PCNA positivity correlated with the differentiation and atypia of the tumour cells; however, in poorly differentiated tumours, the relationship between PCNA expression and proliferation was lost. Basal cell carcinoma showed an increased growth fraction in tiny epithelial nests (mean 43.8, SD 6.0, n = 20) than in neoplastic basal cells (mean 30.1, SD 6.9, n = 8). The growth fractions were significantly higher in the pre-malignant lesions (leukoplakia, mean 22.3, SD 7.7, n = 14; Bowen's disease, mean 45.2, SD 11.7, n = 12; senile keratosis, mean 41.2, SD 7.0, n = 12) than in the normal mucosa (mean 9.8, SD 4.9, n = 10), suggesting that cellular growth fractions correlate with the degree of dysplasia in pre-malignant lesions.

Proliferating cell nuclear antigen (PCNA) expression in Hodgkin's disease

Previous studies of the proliferating cell fraction in Hodgkin's disease (HD) have been directed towards the classical Hodgkin and Reed-Sternberg cells (HRS) to the exclusion of the background population and have not included cases of nodular lymphocyte predominant Hodgkin's disease (NLPHD). Using an antibody to proliferating cell nuclear antigen (PCNA), we have determined the growth fraction of HRS cells and L&H cells in paraffin sections of 15 cases of classical HD [12 nodular sclerosis (NS), 3 mixed cellularity (MC)] and eight cases of NLPHD. By double staining with anti-PCNA and antibodies to B cells (CD20) and T cells (CD45RO), we also determined the growth fraction and immunophenotype of the background population in each case. In classical HD, 50.4 per cent of HRS cells were PCNA-positive and judged to be proliferating, which is comparable to previous studies, while in NLPHD 76.9 per cent of L&H cells were PCNA-positive. In both classical HD and NLPHD, the majority of PCNA-positive cells in the background were T cells, which showed a growth fraction of 57.8 and 68.5 per cent, respectively; in comparison, only 4 per cent of B cells were PCNA-positive in each type of HD. L&H cells are widely accepted to be B cells and there is growing evidence that HRS cells are also B cell-derived. Our results underline a relationship between classical HD and NLPHD and suggest that the characteristic histological features of both diseases may be caused by the production and release of cytokines from altered B cells.

An immunohistochemical investigation of diagnostic biopsy material taken from short and long term survivors with small cell lung cancer

An immunohistochemical study has been carried out on fibre optic-biopsy specimens from patients with small cell lung cancer (SCLC) who had either died within 3 months, or who had survived more than 2 years. Long term survivors (LTS) were identified from completed clinical trials at major UK centres and were matched for age and sex within the trial with short term survivors (STS). The panel of immunohistochemical markers included those previously reported to be associated with prognosis, and reagents representative of both neuroendocrine and epithelial differentiation. A preliminary screen of 17 antibodies identified 11 as consistently reactive on paraffin-embedded material using streptavadin-biotin immunoperoxidase. Of 186 identified patients, 110 biopsy samples were retrieved. Of these, 70 gave sufficient material for analysis. All sections were scored by three observers without knowledge of the prognosis. The analysis failed to identify any antigen whose expression was correlated with prognosis. We conclude that, in fibre-optic biopsy specimens, immunohistochemical analysis does not add prognostic information in SCLC.

Mitotic indices, anti-PCNA immunostaining, and AgNORs in thick cutaneous melanomas displaying paradoxical behaviour

Those melanomas which fail to behave as expected from their Breslow thickness provide interesting material for study. In an attempt to explain differences in behaviour, we have evaluated three distinct proliferative markers in 23 thick melanomas which failed to metastasize and in 20 well-matched control tumours with documented metastasis. The test group demonstrated significantly greater numbers of mitoses when expressed as an index (mitoses per 1000 cells), whilst no difference was found when the results were expressed in terms of mitoses per unit area. Tumours showing epidermal ulceration possessed higher mitotic indices than those of non-ulcerated lesions. High fractions of PCNA immunolabelling combined with low mitotic indices were observed frequently in the non-metastasizing group. This result and its possible relation to survival advantage are discussed in detail. Both AgNOR numbers and patterns failed to act as prognostic variables--indeed, AgNORs failed to correlate with the other proliferative indices, suggesting that their value as a marker of tumour growth is severely limited.

Cell proliferative activity in adenomatous hyperplasia of the liver and small hepatocellular carcinoma. An immunohistochemical study demonstrating proliferating cell nuclear antigen

BACKGROUND

Recently, adenomatous hyperplasia (AH) of the liver, a sizable parenchymal nodule in the cirrhotic liver, has been considered a preneoplastic lesion in human hepatocarcinogenesis.

METHODS

The authors evaluated cell proliferative activity by immunostaining for proliferating cell nuclear antigen (PCNA) in AH (n = 30), small hepatocellular carcinoma (HCC) (n = 14), and their surrounding regenerative nodules (SRN).

RESULTS

AH was categorized histologically as ordinary or atypical. Ordinary AH (n = 8) had no hepatocellular atypia, whereas atypical AH (n = 22) was composed of atypical hepatocytes that were equivocal as to benignity and malignancy. Three atypical AH contained overt malignant foci. The PCNA labeling index of ordinary AH was lower than that of SRN and the index of atypical AH was higher than that of SRN except in two cases. The PCNA labeling index of malignant foci within atypical AH was higher than that of nonmalignant areas of atypical AH and was similar to that of small HCC. For small HCC, the PCNA labeling index was much higher than that of SRN and correlated with small HCC grades.

CONCLUSIONS

These data suggest that ordinary AH is a largely developed regenerative nodule with little proliferative activity and that it is not a preneoplastic lesion; the data also indicate that atypical AH has much proliferative activity, from which malignant foci with greater proliferative activity emerge. Atypical AH with or without malignant foci may represent an early stage of multi-step hepatocarcinogenesis in humans.

Collagen fibril structure of normal, aging, and osteoarthritic cartilage

The collagen architecture in normal, aging, and osteoarthritic articular cartilage was studied optically using a new silver staining technique based on specimens from 50 autopsy cases, four amputated limbs, and six osteoarthritic knees. In the normal articular cartilage, the collagen fibrils in the superficial zone were compactly arranged into layers of decussating flat ribbons mostly parallel to the artificial split lines. The fibrils showed a tendency to condense into vertical arcade columns undergirded by tangential bundles in the intermediate zone. In the deep zone, the fibrils formed a random meshwork with a slight preponderance of vertical fibrils in the perilacunar region. Three types of early degradative lesions involving the collagen network were identified. Type I lesions consisted of focal superficial disruptions related to age and friction. Type II lesions consisted of focal disruptions of tangential fibrils in the intermediate zone leading to cyst formation, probably representing a form of local stress failure. Type III lesions were found in the patella and consisted of marked swelling of the superficial zone, the cause of which was unknown. Lesions of varying severity were seen within each of the three types; the morphological changes of the more severe lesions overlapped with those of clinically overt osteoarthritis.

PCNA and Ki67 expression in breast carcinoma: correlations with clinical and biological variables

AIMS

To investigate the expression of two cell cycle related antigens (proliferating cell nuclear antigen (PCNA) and Ki67 related antigen) in a series of breast cancers; and the possible correlations between the PCNA and Ki67 labelling indexes (PCNA-LI and Ki67-LI) and their associations with other biological and clinicopathological variables.

METHODS

Ninety six ductal and 10 lobular carcinoma specimens were investigated. Samples were fixed in formalin and in Methacarnoy for localisation of PCNA. Ki67 was immunostained on frozen sections. The PCNA-LI and Ki67-LI were evaluated in relation to tumour size, mitotic count, histological grade, nodal state as well as receptor content and altered expression of the p53 gene.

RESULTS

PCNA-LI did not correlate with Ki67-LI, nor was it associated with any other variable examined. A high KI67-LI (above the median value of 13.5) was associated with high grade and mitotic count, negative receptor content, and altered expression of the p53 gene, but not with other variables.

CONCLUSIONS

The PCNA-LI does not seem to be a substitute for the Ki67-LI in evaluating the growth fraction in breast cancer.

Proliferating cell nuclear antigen expression in normal, preneoplastic, and neoplastic colonic epithelium of the rat

Expression of the proliferating cell nuclear antigen (PCNA) was examined in normal rat intestinal tissues and in carcinogen-treated nonneoplastic and neoplastic colonic mucosa. In the normal intestine, PCNA expression was confined to the expected region of the proliferative compartment. A strong correlation was observed between PCNA labeling index and both [3H]thymidine labeling index (R = 0.993, P = 0.007) and percent of cells in S phase as determined by flow cytometry (R = 0.982, P = 0.018) and between the location of the maximal staining for PCNA and [3H]thymidine (R = 0.997, P less than 0.05). In animals treated with dimethylhydrazine (DMH), crypt hyperplasia, an increased PCNA labeling index, and shifts in both the region of maximal and the upper extent of PCNA expression were observed during DMH exposure; significant crypt hyperplasia and expansion of the PCNA-positive compartment persisted after completion of DMH injections. The patterns of PCNA expression and bromodeoxyuridine incorporation were similar in DMH-induced tumors. It is concluded that PCNA immunohistochemistry can be used as a reliable marker of the proliferative compartment in both normal and neoplastic colonic mucosa.

Role of cholecystokinin in pancreatic adaptation to massive enterectomy

Since pancreatic adaptation to massive proximal small bowel resection (PSBR) may be modulated through cholecystokinin (CCK) secretion, we tested the effect of the CCK antagonist CR-1409 on this response. Male Wistar rats (n = 72) weighing 220-225 g were randomised to receive either PSBR or transection/resuture followed by saline or CR-1409 (12 mg/kg daily subcutaneously). Rats were killed one, two, and three weeks post-operatively, at which time blood was obtained for CCK assay and the pancreas was assessed for proliferative activity by three parameters: nucleic acid and protein content, bromode-oxyuridine (BrdUrd) labelling index, and proliferating cell nuclear antigen (PCNA) expression. PSBR increased plasma CCK concentration by 83-102% at 1-3 weeks, irrespective of CR-1409 administration. Total pancreatic DNA content per 100 g body weight increased by 34% at two weeks (p less than 0.05) and by 82% at three weeks (p less than 0.05), while RNA content increased by 60% and 178% (p less than 0.001) and protein content by 20% and 57% (p less than 0.05). PSBR increased the BrdUrd labelling index and the percentage of PCNA immunoreactive cells. CR-1409 completely abolished this proliferative response and also prevented the rise in nucleic acid and protein contents. Apart from growth stimulation, PSBR also enhanced pancreatic exocrine function, as shown by ultrastructural evidence of an appreciable decrease in zymogen granules; CR-1409 also inhibited this functional effect of hypercholecystokininaemia. The results confirm the tropic role of CCK after PSBR, and CR-1409 prevents this pancreatic adaptation.

Expression of proliferative cell nuclear antigen (PCNA) in urinary bladder carcinoma. Evaluation of antigen retrieval methods

Proliferative cell nuclear antigen (PCNA) expression was analyzed in formalin-fixed and paraffin-embedded specimens from patients with urinary bladder cancer using three different anti-PCNA monoclonal antibodies. In 20 recent cases a positive correlation was found between the extent and intensity of PCNA staining and grade of malignancy. In 95 specimens, three to six years old, extensive positive staining was detected in 15 and 23% of grade 2B and 3-4 tumors, respectively. No equivalent staining was found in the grade 1 and 2A tumors. In material more than six years old, a remarkably weak staining was observed regardless of grade. Similarly, in a test of archival material of tonsils a very weak immuno-reactivity was found as compared with fresh material. However, antigen retrieval by microwave heating of the tissue sections was possible in the majority of all cases, and the difference in extent and intensity of the staining between low and high grade tumors remained.

Production of human papillomavirus and modulation of the infectious program in epithelial raft cultures. OFF

Human papillomaviruses trophic for anogenital epithelia cause benign warts, and certain genotypes are closely associated with cervical neoplasia. By using our modifications of the epithelial raft culture system, we were able to recapitulate and modulate the infectious program of a papillomavirus in vitro for the first time. Small pieces of a condyloma containing human papillomavirus type 11 were explanted onto a dermal equivalent consisting of a collagen matrix with fibroblasts and were cultured at the medium-air interface. The infected stem cells proliferated rapidly across the matrix, stratified, and differentiated, as judged by histology. The results correlated with the state of epithelial differentiation, which, in turn, was dependent on the type of fibroblast in the matrix. Under conditions where the epithelial outgrowth underwent terminal differentiation, the entire productive program took place, leading to virion assembly. In contrast, using an alternative condition where the outgrowth failed to achieve terminal differentiation, only the E-region RNAs from the E1 promoter accumulated to any appreciable extent. The proliferating cell nuclear antigen was induced in the differentiated suprabasal cells in the productive cyst growth, which also exhibited high copy viral DNA and abundant E6-E7 RNAs. Comparable cells in the nonproductive cyst outgrowth were negative for all three. These results suggest that the E6 and E7 proteins may play a role in establishing a cellular environment conducive to vegetative viral replication. The culture conditions described should be useful for genetic analysis of this family of important human pathogens and for testing potential pharmacological agents.

The assessment of cellular proliferation by immunohistochemistry: a review of currently available methods and their applications

Immunohistochemical methods using antibodies to cell cycle-related antigens may be used as a means of assessing various aspects of proliferation in tissue, and have the important advantage of preserving the spatial orientation of proliferating cells in histological sections. Currently, the most widely available antibodies for this purpose are antibodies to bromodeoxyuridine (BrdU), Ki67 and antibodies to proliferating cell nuclear antigen (PCNA). BrdU is a thymidine analogue incorporated during the S phase of the cell cycle, which can be introduced by 'in vitro' incubation, and monoclonal antibodies are available to display its localization. Ki67 demonstrates a nuclear antigen expressed in all phases of the cell cycle, except G0 and early G1, but can only be applied to frozen tissue. PCNA is a nuclear antigen which is essential for DNA synthesis, two commercially available antibodies to PCNA work in paraffin-embedded tissue, but may have different staining characteristics under different conditions of fixation. The main advantages and disadvantages of these different techniques are discussed, together with their main applications to date.

Expression of SV-40 T antigen in the small intestinal epithelium of transgenic mice results in proliferative changes in the crypt and reentry of villus-associated enterocytes into the cell cycle but has no apparent effect on cellular differentiation programs and does not cause neoplastic transformation

The mouse intestinal epithelium represents a unique mammalian system for examining the relationship between cell division, commitment, and differentiation. Proliferation and differentiation are rapid, perpetual, and spatially well-organized processes that occur along the crypt-to-villus axis and involve clearly defined cell lineages derived from a common multipotent stem cell located near the base of each crypt. Nucleotides -1178 to +28 of the rat intestinal fatty acid binding protein gene were used to establish three pedigrees of transgenic mice that expressed SV-40 large T antigen (TAg) in epithelial cells situated in the uppermost portion of small intestinal crypts and in already committed, differentiating enterocytes as they exited these crypts and migrated up the villus. T antigen production was associated with increases in crypt cell proliferation but had no apparent effect on commitment to differentiate along enterocytic, enteroendocrine, or Paneth cell lineages. Single- and multilabel- immunocytochemical studies plus RNA blot hybridization analyses suggested that the differentiation programs of these lineages were similar in transgenic mice and their normal littermates. This included enterocytes which, based on the pattern of [3H]thymidine and 5-bromo-2'- deoxyuridine labeling and proliferating nuclear antigen expression, had reentered the cell cycle during their migration up the villus. The state of cellular differentiation and/or TAg production appeared to affect the nature of the cell cycle; analysis of the ratio of S-phase to M-phase cells (collected by metaphase arrest with vincristine) and of the intensities of labeling of nuclei by [3H]thymidine indicated that the duration of S phase was longer in differentiating, villus- associated enterocytes than in the less well-differentiated crypt epithelial cell population and that there may be a block at the G2/M boundary. Sustained increases in crypt and villus epithelial cell proliferation over a 9-mo period were not associated with the development of gut neoplasms--suggesting that tumorigenesis in the intestine may require that the initiated cell have many of the properties of the gut stem cell including functional anchorage.

Measurement of cell proliferation in gastric carcinoma: comparative analysis of Ki-67 and proliferative cell nuclear antigen (PCNA)

Immunostaining to identify nuclear antigens expressed throughout the cell cycle provides a convenient way of assessing proliferating kinetics in tumours. We studied proliferation activity of gastric carcinomas by Ki-67 and PCNA immunostaining and the two methods were compared. The mode of tissue preparation differed, fresh frozen for Ki-67 and formalin-fixed paraffin-embedded for PCNA. Immunostaining with avidin-biotin was used in both. The labelling index (LI) and a semi-quantitative grading of cell proliferation were assessed in both markers. Significant correlation was shown between LI and grading with either Ki-67 and PCNA. However, no correlation was found between PCNA and Ki-67. This lack of relationship between the two markers may be attributed to a number of factors. 1. The most likely is the marked inter- and intra-tumour heterogeneity of gastric carcinomas reflected in high standard deviation values. 2. Preparation of tissue and small size sampling with Ki-67. 3. Long life of PCNA leading to detection of cells that have recently left the cell cycle. 4. One may be observing deregulated expression of DNA as seen in certain tumours. PCNA offers the advantage of being applicable to archival material.

Assessment of specimen fixation in a surgical pathology service

The quality of specimen fixation was examined within a routine diagnostic histopathology service. For each specimen the adequacy of fixation was assessed and the transit time between operating theatre and the laboratory was measured. Preliminary fixation was found to be inadequate in 25% of specimens and some form of manipulation to assist fixation was required in 36% of specimens. The mean transit time was 22 (SD 10.7) hours. Specimen fixation and transport are additional factors to consider in quality assurance of histopathology.

Cell kinetic analyses and expression of carcinoembryonic antigen, carbohydrate antigen 19-9 and DU-PAN-2 in hyperplastic, pre-neoplastic and neoplastic lesions of intrahepatic bile ducts in livers with hepatoliths

We evaluated cell proliferative activity and expression of carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9) and DU-PAN-2 in various bile duct lesions in livers with hepatoliths, using histochemical and immunohistochemical methods. Histologically, the bile duct lesions were divisible into hyperplasia, dysplasia, adenocarcinoma in situ and invasive adenocarcinoma. All cases showed mucosal hyperplasia in stone-bearing bile ducts. Livers with invasive adenocarcinoma frequently contained adenocarcinoma in situ and dysplasia, and livers with adenocarcinoma in situ occasionally harboured dysplasia. Proliferating cell nuclear antigen (PCNA) labelling index was low in hyperplasia (mean +/- SD = 20.5 +/- 8.7%), intermediate in dysplasia (35.4 +/- 15.9%), and high in adenocarcinoma in situ (46.4 +/- 9.3%). The mean number of argyrophilic nucleolar organizer regions (AgNORs) was low in hyperplasia (1.52), intermediate in dysplasia (2.26) and high in adenocarcinoma in situ (2.69). There was a significant positive correlation between PCNA labelling index and AgNORs count. CEA was expressed on invasive adenocarcinoma cells and adenocarcinoma in situ cells in most cases and on dysplastic cells in about a half, while CEA was never present in hyperplastic epithelia. Expression of CA 19-9 was low in adenocarcinoma, intermediate in dysplasia and rather high in hyperplasia. There was no significant difference in DU-PAN-2 expression among these bile duct lesions. These data suggest that cell replicative activity is low in hyperplasia, intermediate in dysplasia and high in adenocarcinoma in situ, and that CEA appears in the following order: dysplasia, adenocarcinoma in situ, invasive adenocarcinoma. We suggest that carcinogenesis in biliary epithelial in livers with stones is a multi-step process through hyperplasia, dysplasia and adenocarcinoma in situ to invasive adenocarcinoma.

Proliferating cell nuclear antigen in oesophageal diseases; correlation with transforming growth factor alpha expression

This study was designed to correlate mucosal proliferation in Barrett's oesophagus with expression of a growth promoting peptide, transforming growth factor alpha (TGF alpha). Oesophageal mucosa was studied from 50 patients with oesophageal disease who had been treated by oesophagectomy. Histological analysis showed a range of oesophageal pathology - 18 patients had gastric type Barrett's mucosa, 18 had intestinal type Barrett's mucosa, and 14 had oesophageal adenocarcinomas. Sections were stained immunohistochemically for proliferating cell nuclear antigen (PCNA) (an index of cellular proliferation) and TGF alpha. PCNA immunostaining was seen mainly in the basal cells of the neck/foveolar epithelial compartment of the glands in Barrett's oesophagus. However, in mucosa with high grade dysplasia, the proliferative compartment extended upwards into the superficial layers of the glands. At least 2000 cells were counted in each patient to determine the proportion with PCNA immunoreactivity (PCNA labelling index). The labelling index was highest in adenocarcinoma (25%) and in Barrett's intestinal type mucosa with high grade dysplasia (26%) compared with intestinal type mucosa with no significant dysplasia (20%) and Barrett's gastric type mucosa (12%). There was a significant positive correlation between PCNA labelling indices and TGF alpha expression in Barrett's mucosa (p less than 0.01). In glands showing high grade dysplasia, TGF alpha immunoreactivity was seen in the same regions of the glands as PCNA immunoreactivity, indicating the possibility of involvement of TGF alpha in (pre) neoplastic proliferation in Barrett's oesophagus.

Proliferating cell nuclear antigen in breast lesions: Correlation of c-erbB-2 oncoprotein and EGF receptor and its clinicopathological significance in breast cancer

Monoclonal anti-proliferating cell nuclear antigen (PCNA PC10), which is directed against a 36 kDa auxiliary protein for DNA polymerase delta specific for the S-phase of cell cycle, was used to measure tumour cell proliferation in 4 lactating breasts and 98 benign and malignant breast tumours. The percentage of PCNA-positive cells determined by point counting was significantly lower in the lactating breast [mean 3.6%, standard deviation (SD) 0.67, n = 5] than in fibroadenoma and mastopathy (mean 23.7, SD 5.0, n = 2). Primary breast carcinoma showed a PCNA index ranging from 2% to 36% (mean 12.3, SD 9.3, n = 50), whereas in recurrent carcinoma the index was mean 28.5, SD 4.0. A high index was correlated with c-erbB-2 and epidermal growth factor (EGF) receptor membrane reactivity, worsening histological grade, poor survival and disease-free survival. The expression of c-erbB-2 and EGF receptor was associated with poor survival and disease-free survival in primary breast cancer patients.

Over-expression of p53 nuclear oncoprotein in colorectal adenomas

p53 is a nuclear phosphoprotein which controls normal cell growth. Normal p53 protein is undetectable by standard immunohistochemical staining and the over-expression found in neoplastic cells correlates with the presence of point mutations of evolutionary conserved regions of the p53 gene. We examined the expression of p53 protein in a series of 36 colorectal adenomas (13 tubular, 17 tubulovillous, 6 villous) showing different degrees of dysplasia (11 mild, 19 moderate, 6 severe), 11 moderately differentiated adenocarcinomas (6 Duke's A, 4 Duke's B, 1 Duke's C) and 5 metaplastic polyps using the polyclonal antibody CM1 which recognises p53 protein in conventionally fixed and processed histological material. We found that 15 out of 36 colorectal adenomas showed p53 immunoreactivity, although in 4 positive cases (26%) the staining was very focal (less than 0.1% positive cells). More than 80% of severely dysplastic adenomas showed strong p53 immunoreactivity and this over-expression was correlated with increased cell proliferative rate as detected by the proliferating-cell-nuclear-antigen (PCNA) staining. p53 nuclear staining was also seen in 8 out of 11 (65%) colorectal adenocarcinomas as previously shown. Our data suggest that the p53 gene mutation, with the subsequent over-expression of the protein, occurs in colorectal adenomas and may therefore be a fundamental genetic event underlying the dysplasia and loss of proliferative control that are characteristic of adenomas with malignant potential.

Immunohistochemical demonstration of proliferating cell nuclear antigen in glioblastomas: pronounced heterogeneity and lack of prognostic significance

In order to evaluate a possible significance of the expression of proliferating cell nuclear antigen (PCNA) as clinically useful prognostic parameter, we retrospectively investigated a series of 40 glioblastomas by means of immunohistochemistry and compared the results to patient survival. All glioblastomas included in the study had been treated by operation, radiotherapy and intraarterial ACNU [3-(4-amino-2-methyl-5-pyrimidinylmethyl)-1-(2-chloroethyl)-1-nitr osourea] chemotherapy. Patient survival ranged from 2 months to 42 months (mean: 14.2 months). PCNA values varied widely, ranging from 0.5% to 75% (mean: 24.9%). Statistical analysis revealed no significant correlation between PCNA index and patient survival. Our study thus indicates that the expression of PCNA appears not to be a useful prognostic parameter for glioblastoma patients.

Hepatocyte regeneration in acute fulminant and nonfulminant hepatitis: a study of proliferating cell nuclear antigen expression

It has been suggested that in fulminant hepatitis it is the lack of hepatocyte regeneration that in the presence of an ongoing loss of hepatocytes leads to hepatic failure and ultimately determines the grim prognosis of this disease. However, little data are available concerning hepatocyte regeneration in human acute hepatitis. We compared the nuclear expression of proliferating cell nuclear antigen with the incorporation of bromodeoxyuridine in formalin-fixed, paraffin-embedded liver tissues of rats at different stages of regeneration after two-thirds partial hepatectomy. Immunohistochemical staining for proliferating cell nuclear antigen was performed using the monoclonal antibody 19F4. A good correlation was seen between nuclear labeling for bromodeoxyuridine and proliferating cell nuclear antigen, which indicates that the immunoreactivity for proliferating cell nuclear antigen accurately reflects hepatocyte proliferation. Subsequently, we determined the nuclear expression of proliferating cell nuclear antigen on archival paraffin-embedded samples of the normal human liver (8 cases), acute nonfulminant hepatitis (10 cases) and fulminant hepatitis (4 cases). The mean proliferating cell nuclear antigen labeling indices were the following: normal liver = 0.4%; acute nonfulminant hepatitis = 43.0%; and fulminant hepatitis = 45.9%. The indices for proliferating cell nuclear antigen were significantly greater in acute hepatitis than in the normal liver, reflecting the high cell turnover in hepatitis. However, no significant difference was seen between the expression of proliferating cell nuclear antigen in nonfulminant and fulminant acute hepatitis. These data suggest that the net loss of hepatocytes in fulminant hepatitis may not be caused by a lack of hepatocyte regeneration but rather results from overwhelming hepatocyte injury with subsequent cell death.

Primary central nervous system lymphoma

Primary central nervous system lymphomas (PCNSL) are uncommon neoplasms accounting for less than 2% of brain tumours. Their incidence appears to be increasing across a wide age range, in both immunocompetent and immunosuppressed populations. Particular risk groups include those with congenital and acquired immunodeficiencies and transplant recipients. The spread of the AIDS epidemic has seen large numbers of complicating PCNSL develop. Epstein-Barr virus infection appears to play a role in the development of these lymphomas in the immunosuppressed population. The aetiology of these tumours in the immunocompetent is uncertain. Their tendency to remain within the nervous system is not well understood but may be a function of CNS binding molecules carried by lymphocytes. Clinically PCNSL may present with a wide variety of signs and symptoms and has a capacity to mimic many other neurological conditions. Radiologically they appear as hyperdense homogenous deposits in subcortical white matter. Although most lesions are intermediate or high grade B cell lymphomas, T cell lymphomas are being recognised with increasing frequency. Immunohistochemistry and genotypic analysis have an important role in accurately characterising PCNSL, particularly in stereotactic biopsies. Involvement of multiple areas of the neuraxis, the eye and multiple intracranial sites can occur in the absence of obvious systemic lymphoma. The role of surgery in their treatment is uncertain. A combination of radiotherapy and chemotherapy can increase the length of survival. The prognosis, however, remains poor in comparison with nodal lymphomas, and particularly so in those with AIDS.

Tumour suppressor gene products, proliferation, and differentiation markers in lung neuroendocrine neoplasms

Typical carcinoid, atypical carcinoid, and small cell lung cancer (SCLC) fall within the spectrum of neuroendocrine lung neoplasms. This paper investigates the immunohistochemical expression of the products of tumour suppressor genes p53 and retinoblastoma (RB), together with proliferation (PCNA and Ki67) and neuroendocrine differentiation markers, in 14 typical carcinoids, ten atypical carcinoids, four borderline atypical carcinoid/SCLC, and 11 SCLC. We demonstrated that the phosphoprotein p53 and RB product can be immunolocalized on routine histological material. p53 protein was absent in all typical and atypical carcinoids, while it was abnormally expressed in eight SCLC and one borderline case. RB product was detected in all typical carcinoids and in two atypical carcinoids, while it was consistently absent in the other cases. PCNA-labelled cells were less than 4 per cent in typical carcinoids, about 40 per cent in atypical carcinoids, and over 70 per cent in SCLC. PCNA labelling index discriminates between typical and atypical carcinoids. Neuroendocrine differentiation was evaluated by a semi-quantitative method: a mean score value was obtained, which was high in typical carcinoids, intermediate in atypical carcinoids, and low in SCLC. Our data was obtained, which was high in typical carcinoids, intermediate in atypical carcinoids, and low in SCLC. Our data show that the decrease in neuroendocrine features from typical carcinoid to SCLC is paralleled by an increase in proliferative activity and by an altered expression of tumour suppressor gene products. The above findings have diagnostic relevance.

Immunolocalization of regenerating cells after submassive liver necrosis using PCNA staining

Little data exist on the proliferative state of liver cells and its relationship with various morphological findings in acute liver failure (ALF) in man. In this study we used the monoclonal antibody NCL-PCNA (clone PC-10) against the proliferating cell nuclear antigen (PCNA) to detect cycling cells in paraffin sections of 3 normal livers, 14 post-mortem needle-specimens of submassive hepatic necrosis (SHN) due to paracetamol overdosage (POD), and 10 hepatectomy specimens obtained at transplantation in patients with acute or subacute liver failure of presumed viral aetiology. In normal livers, only occasional sinusoid-lining cells were stained, whereas in SHN following POD or presumed viral hepatitis, hepatocytes of variable morphology showed significant immunoreactivity. Following POD, immunoreactivity was higher in samples taken within 5-6 days than in those obtained at 9-11 days, a pattern reminiscent of the decrease in the rate of regeneration, previously documented after partial hepatectomy in humans. Immunolabelled hepatocytes were aggregated in multiacinar 'nodules' in cases with a map-like distribution of collapsed and non-collapsed parenchyma. Ductules demonstrated comparatively less staining, but extensive labelling was exceptionally found in areas of complete hepatocellular dropout. In these areas, small elongated cells with strongly PCNA-positive ovoid nuclei, forming periportal sprouting cords or incorporated into the lining of ductules, were most remarkable in that they closely resembled 'oval cells' described in animal studies.

Proliferating cell nuclear antigen (PCNA) expression in formalin-fixed tissue of non-small cell lung carcinoma

An immunohistochemical study of non-small cell lung carcinoma using PC10, a monoclonal antibody against PCNA, was performed on tissues routinely processed with formalin fixation and paraffin embedding. The PCNA labelling index and mitotic index were determined from sections of these tissues. Tumours showed a high mean PCNA labelling index of 53.3%. The mean mitotic index was 10.3/1000 cells. Inter-examiner agreement of mitotic counting was good. A linear correlation between the PCNA labelling index and mitotic index was demonstrated (r = 0.71, P less than 0.00001). It is concluded that immunohistochemical nuclear labelling with anti-PCNA on routinely processed tissue is a simple technique for the assessment of proliferation in non-small cell lung carcinoma.

Measures of tumor proliferative activity

Tumor proliferative activity, or labeling index, is of interest for gaining insight into the biologic properties of human neoplasm and for providing clinical information that might guide patient management. There has been an abundance of literature reporting experience with standard and newer techniques of measuring tumor proliferative activity. These methods are reviewed with emphasis on technical issues. Particular attention is paid to the development and use of monoclonal antibodies, Ki-67 and anti-PCNA/cyclin. These antibodies are readily available and relatively simple to use. The former has recently been shown to be of prognostic value in non-Hodgkin's large cell lymphomas. A number of studies suggest that indices using these techniques could be useful for a variety of carcinomas, soft tissue tumors, and tumors of the central nervous system.

Will a tumor metastasize? Quantitate, semi-quantitate or pseudo-quantitate? A brief review of the microscopic prediction of tumor metastasis

This review examines ways in which histopathologists can attempt to predict whether a neoplasm will metastasize by microscopic examination of surgically removed samples of human neoplasms. These include qualitative description, semi-quantitative analysis of differentiation and proliferation, or of the nature of the edge of the neoplasm, and quantitative analysis of mitotic counts. More recently measurement of DNA content, analysis of DNA turnover, measurement of proliferation antigens, measurement of nucleolar organizing areas, counting nucleoli, morphometry of nuclei and identification of genetic change have become possible. There is no test capable of uniform accurate prediction of prognosis. In certain types of neoplasms in individual sites useful prognostic information can be obtained either by rigorous semi-quantitative microscopic analysis or by quantitative microscopical analysis. There is still doubt as to whether newer quantitative techniques will perform uniformly better than older semi-quantitative techniques. The simple subjective statement "high-grade malignancy, average malignancy, low malignancy" is better than elaborate non-reproducible pseudo-quantitation.

A comparison of proliferating cell nuclear antigen (PCNA) immunostaining, nucleolar organizer region (AGNOR) staining, and histological grading in gastrointestinal stromal tumours

Gastrointestinal stromal tumours are lesions in which it is difficult to predict clinical outcome from the histological appearances. Sixty cases were studied using three different methods of assessing aspects of cellular proliferation; these were (i) immunostaining for proliferating cell nuclear antigen (PCNA), (ii) interphase nucleolar organizer region staining (AgNORs), and (iii) a histological grading system based on mitotic counts. Both PCNA immunostaining and AgNOR counts were found to correlate well with histological grading and all three methods independently showed good correlations with survival. This suggests that these proliferation-associated markers may be used as additional features to support histological grading in this relatively uncommon group of tumours.

A study of cell proliferation in formalin-fixed, wax-embedded bone marrow trephine biopsies using the monoclonal antibody PC10, reactive with proliferating cell nuclear antigen (PCNA)

We have investigated proliferation in bone marrow trephine biopsies from 32 patients with normal or abnormal haemopoiesis, using the monoclonal antibody PC10, which detects proliferating cell nuclear antigen (PCNA), together with immunohistochemical markers of haemopoietic cell lineage. PCNA immunostaining revealed the pattern of proliferation within individual haemopoietic lineages in normal marrow. Two unexpected observations were made: of erythroid cells, only pro-erythroblasts and occasional early normoblasts reacted, and positivity of megakaryocytes was unrelated to nuclear lobulation or CD61 expression. The pathological cases represented conditions in which haemopoiesis is increased (reactive hyperplasia, chronic granulocytic leukaemia, myeloproliferative and myelodysplastic syndromes, megaloblastic anaemia). Increases in the number, and disturbances of the spatial organization, of PCNA-expressing cells were present to a variable extent in all cases. Sheets of PCNA-positive megaloblastoid erythrocytes were frequently found in myelodysplastic and myeloproliferative tissue, associated with marked disturbances in the spatial organization of all haemopoietic lineages. Cases of megaloblastic anaemia due to vitamin B12/folate deficiency also demonstrated greatly increased erythroid PCNA expression, with positivity in some giant metamyelocytes. In addition to reflecting increased proliferation, elevated PCNA expression in some bone marrow pathologies may be due to altered kinetics of the protein induced by disturbances in growth factor production.

Phenotypic characterisation of mononuclear and multinucleated cells of giant cell tumour of bone

Studies were carried out on 3 giant cell tumours of bone (GCTB) to characterise further the cells forming the distinctive mononuclear and multinucleated components. Samples of tumours were grown as explants in vitro and implanted subcutaneously in athymic mice. Cells were characterised in terms of their cell morphology and cytochemical, antigenic and functional phenotype. In culture, giant cells formed a non-proliferative, relatively homogeneous population of cells which expressed features characteristic of the osteoclast phenotype. The mononuclear cell component was heterogeneous and included macrophage-like cells, which persisted for a short time in culture, and fibroblast-like cells which proliferated. In subcutaneous implants, the fibroblast-like cells formed a tissue which included areas of bone formation associated with regions of alkaline phosphatase activity. These observations are consistent with earlier suggestions that the neoplastic component in GCTB consists of a mononuclear stromal cell which elicits a macrophage/osteoclast response.

Flow-cytometric analysis of growth-regulatory peptides and their receptors in Barrett's oesophagus and oesophageal adenocarcinoma

The conventional assessment of the premalignant potential of Barrett's oesophagus is unsatisfactory. However, it has recently been shown that abnormalities of growth-regulatory peptides and their receptors may be important in the pathogenesis of this condition. In an attempt to improve the diagnostic and prognostic criteria we have studied 21 consecutive patients with Barrett's oesophagus and 7 others with adenocarcinoma of the oesophagus. In each patient biopsy specimens were taken from the columnarlined oesophagus or the adenocarcinoma and from the gastric cardiac mucosa for routine histologic evaluation. Immediately adjacent specimens were taken from both the Barrett's mucosa or adenocarcinoma and from the gastric mucosa for flow-cytometric study. The latter samples were disaggregated and labelled with antibodies to epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and epidermal growth factor receptor (EGF-R). The flow cytometer selected cells labelled with each antibody and expressed them as a percentage of the total number of disaggregated cells (average, 5500 cells). Epidermal growth factor receptors were expressed in a greater number of cells from Barrett's mucosa, with the intestinal type or those with dysplasia, than in gastric cardiac mucosa (p less than 0.05). All seven adenocarcinoma had many more cells expressing EGF, TGF-alpha, and EGF-R than normal gastric mucosa (p less than 0.01). We conclude that flow-cytometric evaluation of EGF-R can help in the understanding of the pathogenesis of Barrett's oesophagus.

Flow cytometric characterisation of proliferating cell nuclear antigen using the monoclonal antibody PC10

Anti-PCNA antibodies have aroused considerable interest recently as potential immunohistochemical markers of proliferation for use on clinical samples. PC10 is a monoclonal antibody which has been shown to recognise its epitope on formalin-fixed, paraffin-embedded, archival material. However, whilst PC10 gives the expected labelling pattern for growth fraction in normal tissues and some tumours, discrepant results have been obtained, for example, in carcinoma of the breast. By means of flow cytometry, we have attempted to characterise the different staining patterns that can be obtained with PC10. Intact fixed cells from proliferative mammalian cultures show 100% labelling, consistent with a growth fraction estimate. In contrast, detergent-extracted nuclei show S-phase specific staining. Nuclei extracted by treatment of fixed cells with pepsin show a different staining pattern again, with many G1 cells weakly stained and staining intensity increasing through S-phase into G2. The results demonstrate that multiparametric flow cytometry can define the cell populations which label with proliferation-related antibodies, such as PC10, under a variety of experimental conditions.

An inter-observer and intra-observer variability study on the diagnosis of lymph node biopsy specimens

One hundred lymph node biopsy specimens were examined on two separate occasions by seven pathologists differing in experience in lymphoreticular pathology. Neither history nor immunohistochemistry was provided and the study, therefore, focused on morphological interpretation alone. The participants evaluated each case using a constructed response form in which the confidence with which they entered each response was also entered. Agreement on various points, between pathologists, between the two rounds, and with the referring centre was assessed. Whilst there was a high level of agreement over a diagnosis of benign vs. malignant and non-Hodgkin lymphoma vs. Hodgkin's disease, there was considerably less agreement over both T vs. B cell phenotype and high vs. low grade. The lack of agreement over grade, an evaluation which is usually made independent of immunohistochemistry, is particularly important, because of the relevance to selection of treatment. Proliferation markers may be more appropriate determinants of treatment choice.

Relationship of proliferating cell nuclear antigen (PCNA) in prostatic carcinomas to various clinical parameters

Proliferating cell nuclear antigen (PCNA) expression was determined immunohistochemically, using a monoclonal antibody PC10, in 102 prostatic carcinoma samples and in prostate tissue from 21 patients with benign prostatic hyperplasis (BPH). The percentage of cells with stained nuclei ranged from 1% to 58% in the carcinoma specimens and 0% to 10% in the BPH specimens. A semiquantitative scoring system was devised for the degree of PCNA positivity observed in the tumors. Statistical analysis of the PCNA score in relation to the histological grade of the tumors gave a significant positive or negative correlation between these parameters P less than 0.001. No significant correlation between PCNA score was, however, seen with metastatic status, T category (TMN classification) of the primary tumor, or the patient's age at diagnosis. In 65 prostatic cancer patients of known survival, those individuals whose tumors had a PCNA score of +/- (less than 10% of nuclei stained) were compared with those patients whose tumors were either 1+, 2+, or 3+ (greater than 10% of nuclei stained). Life table analysis of the two groups indicated that the patients with the lower PCNA score survived significantly longer than those with the higher PCNA scores, P less than 0.04. Comparison of the Ki-67 expression in frozen sections with the PCNA expression in wax-embedded tissue of 86 prostatic carcinomas was also undertaken. A significant correlation between these two parameters was found, P less than 0.001, although the growth fraction estimated by Ki-67 expression was generally lower than that given by the PCNA scoring system.

Primary central nervous system lymphomas--an update

Primary CNS lymphomas (PCNSL), until recently representing about 1% of all brain tumors, show dramatically increased incidence both in high-risk groups (immunocompromised, AIDS) and in the general population. They are extranodal diffuse non-Hodgkin's lymphomas, the morphology and classification of which are identical to those of systemic lymphomas, although PCNSL show different biological behavior and diagnosis according to the New Working Formulation and updated Kiel classification may be difficult. The majority are large B cell variants of high-grade malignancy; low-grade subtypes and T cell lymphomas are rare. Sixty per cent occur in the supratentorial space (hemispheres, periventricular) and 12% in the posterior fossa; 30% are multiple (50%-70% in AIDS). PCNSL show a male preponderance with a peak incidence in the 5th-7th decade (3rd-4th in AIDS). The duration of diffuse or focal clinical symptoms averages 1-2 months. Computed tomography and magnetic resonance imaging scans show single or multiple or diffuse, often typical lesions. Diagnosis is achieved by evaluation of stereotactic biopsy material or cerebrospinal fluid cytology using immunocytological markers. Current therapy in immunocompetent patients, radiation plus corticosteroids and pre- or postradiation polychemotherapy, shows response rates of 85% with a median survival of 17-44 months, a prognosis similar to that for glioblastoma. Meningeal PCNSL is treated with intrathecal methotrexate or cytosine arabinoside. Transliquoral seeding of PCNSL is frequent, distant metastases occurring in 6%-8%. Therapy of AIDS-related PCNSL makes use of radiation and corticosteroids, and rarely of chemotherapy. The pathogenesis of PCNSL is unknown, but Epstein-Barr virus may be a contributory factor.

Cell proliferation

The composition of a series of critical summaries is necessarily idiosyncratic, but in this compilation I have been guided by the recent publication of reviews and monographs on the subject. Consequently, it seems reasonable to focus on more fundamental areas of research which may lie outside the normal reading of most pathologists. Nevertheless, I regard these burgeoning areas as being likely to impinge on our research, if not our practice, in the near future. I will concentrate on four areas that I consider of particular interest. First, regulation of the cell cycle; second, arrest of proliferation; third, programmed cell death; and finally, the generation of novel markers of proliferation.

A comparison of immunohistochemical markers of cell proliferation with experimentally determined growth fraction

The relationship between immunoreactivity for cell proliferation markers (Ki67 and PCNA) and the growth fraction as determined by the fraction of labelled mitoses method was assessed in xenograft tumours grown from the LoVo cell line in nude mice. FLM curves were constructed by injecting tritiated thymidine and then preparing autoradiographs from the tumours. From this data an estimate of growth fraction and cell cycle time were made. Using frozen material from the same tumours, the Ki67 index was determined by immunostaining. PCNA staining was determined in the fixed material which had been used for the autoradiographs. The results show that Ki67 staining follows the same trend as the FLM-determined growth fraction as the tumour increases in size and the rate of growth decreases. However the Ki67 index does produce a consistent overestimate of the growth fraction in this in-vivo system, as compared to observations in cell culture. PCNA staining showed virtually 100 per cent positive staining in all the tumours, which is likely to reflect the long half-life of the antigen, compared to the very fast cell-cycle time of the xenograft tumours. These results show that staining with proliferation markers is not a precise determinant of growth fraction. Ki67 staining is a method that can be usefully applied as an operational marker of cell proliferation, but should not be used uncritically. Further caution is necessary in the use of PCNA. The findings also demonstrate the need to use a range of methods when assessing a new proliferation marker.

Prognostic value of various molecular and cellular features in oral squamous cell carcinomas: a review

Recent findings of prognostic value for oral squamous cell carcinomas (OSCCs) which may supplement clinical staging are reviewed. Many reports show that histopathologic grading, measurements of tumor-thickness and DNA-content have independent prognostic value and may thus be of clinical value. Features regarding cells at the invading margins of the tumors are probably of higher prognostic value than features within other parts of the tumors. Reportedly, various other cellular and serum markers have prognostic associations worthwhile further research.

An enhancement method for immunohistochemical staining of proliferating cell nuclear antigen in archival rodent tissues

An enhanced immunohistochemical procedure to detect proliferating cell nuclear antigen (PCNA), an endogenous cell replication marker, has been successfully applied to formalin-fixed, paraffin-embedded archival rat and mouse tissues. The procedure involves microwave oven heating of tissue sections in a commercially available antigen retrieval solution of heavy metal salts. Successful immunohistochemical staining of PCNA can be consistently obtained in tissues fixed for over 24 months in formalin and in sections made from paraffin blocks stored in our tissue archives for up to 19 months. Use of this technique will allow retrospective staining of rodent tissues for identification of S phase cells as an indication of DNA replicative activity in previously conducted toxicity and carcinogenicity studies.

Proliferating cell nuclear antigen expression in central nervous system neoplasms

Proliferating cell nuclear antigen (PCNA) is a cell-cycle-regulated protein, which can be demonstrated in routinely fixed specimens. Studies on various tissues, cell cultures and neoplasms have shown that PCNA labelling index (LI) correlates with flow cytometry, tritiated thymidine LI, bromodeoxyuridine (BrdU) incorporation and Ki67 LI. PCNA LI may have prognostic value in various neoplasms. The present study concerns PCNA immunostaining in a series of neuroglial tumours. We demonstrate that there is a relation between PCNA LI and histological grade, and between PCNA LI and reported thymidine LI, BrdU LI and Ki67 LI. Pleomorphic xanthoastrocytomas and low-grade astrocytomas had the lowest LI, whereas metastases of small cell lung cancer and medulloblastomas had the highest LI. Glioblastomas sometimes showed a certain degree of intratumoral heterogeneity of distribution of immunostained cells. Intratumoral heterogeneity underscores the critical importance of representative sampling of central nervous system neoplasms for kinetic studies. As expected, PCNA LI are somewhat higher than tritiated thymidine LI, BrdU LI and Ki67 LI because PCNA is a marker of G1, S, G2 and M-phases of the cell cycle and not of S-phase only. In addition, because of its long half-life, PCNA may be detected immunohistochemically in cells that have recently left the cell cycle. The immunohistochemical evaluation of PCNA LI is easy to perform on routinely processed material, allowing retrospective studies. PCNA LI may be a useful tool in grading gliomas. However, its prognostic value must be validated by comparing PCNA LI with the follow-up of the neoplasms, and possibly with the responsiveness to anti-proliferative therapy.

Prognostic value of proliferating cell nuclear antigen in gastric carcinoma

A new monoclonal antibody to proliferating cell nuclear antigen (PCNA), PC10, which can be used on routinely processed tissue, was applied to 93 cases of gastric carcinoma. Significant intra-tumoural variation in staining occurred. In addition to a PCNA index (percentage of positive cells per 1000 tumour cells), a semiquantitative PCNA grading system was devised, based on estimates of less than or more than 50% of positive tumour cells in whole sections. Neither PCNA index nor PCNA grade showed any correlation with established histological variables, tumour stage, or the presence of lymph node metastases. No significant correlation was observed between PCNA index and S + G2M phase fraction measured by flow cytometric analysis. To analyse survival tumours with PCNA indices above and below the median level (41%) were compared. Those with a higher index tended to have a worse prognosis, but when PCNA grade was considered, it was found to have definite independent prognostic value, tumours of low grade surviving better than those of high grade. The ability of semiquantitative PCNA grading to allow for intra-tumoural variation suggests it may have advantages over absolute counting, which is prone to sampling error when tumour heterogeneity is a major factor. The prognostic value of PC10 staining in gastric carcinoma is therefore promising.

The assessment of proliferating cell nuclear antigen (PCNA) immunostaining in primary gastrointestinal lymphomas and its relationship to histological grade, S+G2+M phase fraction (flow cytometric analysis) and prognosis

PCNA is a nuclear protein that is synthesized in late G1 and S phases of the cell cycle and is, therefore, correlated with the cell proliferative state. A new monoclonal antibody (PC10) to genetically engineered PCNA has been shown to label proliferating cells in formalin-fixed paraffin-embedded normal human tissues. Previous studies in lymphomas, using various markers of cell proliferation, have shown a strong correlation between indices of cell proliferation and histological grade. These studies have shown that within each histological subtype there is often a wide range of proliferative indices and that these may be of some prognostic significance. Thirty-one gastrointestinal lymphomas were studied. Our results show that there is a good correlation between PC10 index and histological grade of tumour (0.01 P greater than P greater than 0.001) and also a significant relationship between PC10 index and S+G2+M phase fraction as measured by flow cytometric analysis (r2 = 0.62; P less than 0.01). Twenty-three cases were available for survival analysis. In these cases a high PC10 score correlated with poor survival (P = 0.04). Based on this series, it appears that there is a significant relationship between PC10 index and histological grade, and between PC10 index and S+G2+M phase as measured by flow cytometric analysis. In addition, our results suggest that a high PC10 index is an adverse prognostic factor in primary gastrointestinal lymphoma.

Haemangiopericytomas: the prognostic value of immunohistochemical staining with a monoclonal antibody to proliferating cell nuclear antigen (PCNA)

Forty-two cases of haemangiopericytoma were studied retrospectively using immunohistochemical staining with PC10, a monoclonal antibody to PCNA. The percentage of tumour cells with positive staining for PCNA was found to correlate well with histological grading. Clinical follow-up data were available in 25 adults and showed no known deaths in 11 cases with a low proportion (less than 14%) of positive cells. Out of 14 cases with a high number (greater than or equal to 14%) of positive cells, seven patients are known to have died, two had metastases, and in a further two there have been multiple recurrences of tumour. DNA flow cytometry was performed on 26 cases but this showed no correlation with PC10 staining or clinical outcome. Staining with PC10 may be of particular value in the identification of patients at greatest risk of rapid tumour metastasis and early death.