Proliferating cell nuclear antigen immunolocalization in gastro-intestinal epithelia

Association between colonic adenoma size and proliferative zone in the crypt

BACKGROUND

We previously reported unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. The proliferative zones of colorectal adenomas have three patterns: 'lower,' 'superficial' and 'entire'. This study aimed to clarify the characteristics of each adenoma pattern.

METHODS

We investigated 2925 consecutive patients who underwent colonoscopy at our institute. All polyps that were removed were histologically examined using hematoxylin and eosin staining. The location of the proliferative zone was assessed for adenomas. Data were compared using Dunn's and Kruskal-Wallis tests.

RESULTS

Colorectal adenomas with 'lower' proliferative zone often appeared similar to hyperplastic polyps (42.8%), and the frequency was significantly higher than that of adenomas with 'superficial' and 'entire' proliferative zones (p < 0.001). The mean sizes of adenomas were 2.4, 3.0 and 3.9 mm for 'lower,' 'superficial' and 'entire' proliferative zones, respectively. A significant gradual increase was observed. Regarding morphology, the proportion of type 0-I in adenomas with an 'entire' proliferative zone was significantly higher than that in adenomas with 'superficial' proliferative zone (p < 0.001).

CONCLUSION

While colorectal adenomas develop and increase in size, the proliferative zone appears to shift upward and become scattered.

Hyperplastic polyp-like adenoma: a subtype of colonic adenoma with a proliferative zone confined to the lower two-thirds of the crypt

BACKGROUND

The proliferative zone of colonic adenomas is confined to the upper third of the crypt or is scattered along its entire axis. In contrast, there are unusual adenomas with proliferative zones confined to the lower two-thirds of the crypt. We investigated the frequency and endoscopic features of adenomas with lower proliferative zones.

METHODS

We retrospectively reviewed consecutive patients who underwent colonoscopies between September 2022 and March 2023 at the Toyoshima Endoscopy Clinic. Colorectal polyps were endoscopically assessed using the Japan Narrow-Band Imaging Expert Team (JNET) classification. All resected polyps were histologically examined, and the proliferative zone locations were assessed in the adenomas.

RESULTS

The frequency of adenomas with a lower proliferative zone was 1.8% (44/2420) in adenomas. Among these adenomas, JNET type 1 incidence was 43.2% (19/44), which was significantly higher than that in adenomas with a normal proliferative zone. Adenomas with a lower proliferative zone were diminutive (mean size: 2.5 mm) and prone to develop in the proximal colon.

CONCLUSION

Colonic adenomas with proliferative zones confined to the lower two-thirds of the crypt often appear as diminutive, hyperplastic polyps.

Proliferating Cell Nuclear Antigen (PCNA) Immunoexpression in Hyperplastic Polyps and Adenomas of the Appendix

The aim of this study was to compare proliferating cell nuclear antigen (PCNA) immunoexpression in hyperplastic polyps and adenomas of the human vermiform appendix. We used the monoclonal antibody PC 10 in 13 hyperplastic polyps, 27 vil lous adenomas, and 13 adenomas with undulating or flat epithelium. In both the hyperplastic polyps and the villous adenomas, the labeling indices were significantly greater in the lower third than in the upper third. The labeling indices of the flat/undulating adenomas resembled those of the upper third of the villous adeno mas. In contrast to previous findings in colorectal adenomas, there were no signifi cant differences in labeling indices between the hyperplastic polyps and the villous adenomas. We concluded that PCNA labeling indices are unlikely to be of value in the distinction between villous adenomas and hyperplastic polyps in the appendix. The results may reflect the different spectrum of appendiceal adenomas versus col orectal adenomas. Int J Surg Pathol 2(4).-2 75-280, 1995

Effects of aflatoxin B1 exposure and sodium selenite supplementation on the histology, cell proliferation, and cell cycle of jejunum in broilers

The aim of this study was to investigate the effects of aflatoxin B1 (AFB1) exposure and sodium selenite supplementation on the histology, cell proliferation and cell cycle of jejunum in broilers. A total of 240 1-day-old male AA broilers were divided into four groups of 60 each, fed with basal diet (control group), 0.3 mg/kg AFB1 (AFB1 group), 0.4 mg/kg supplement Se (Se group), and 0.3 mg/kg AFB1 + 0.4 mg/kg supplement Se (AFB1 + Se group) for 21 days, respectively. Compared with the control group, decreased jejunal villus height, villus height/crypt ratio, and proliferation cell nuclear antigen (PCNA)-positive cells, and G2/M phase arrest and shedded epithelial cells on the tip of jejunal villus were observed in AFB1 groups at 7 and 14 days of age. However, the villus/crypt ratio, PCNA-positive cells and cell percentage of G0/G1, S, and G2/M phases had no significant differences between AFB1 group and control group at 21 days. Simultaneous supplementation with sodium selenite restored these parameters to be close to those in control group. In conclusion, 0.3 mg/kg AFB1 in the diet inhibits the development of broiler's jejunum by reducing cellular proliferation and inducing G2/M arrest during only the first 2 weeks after hatching. Supplementation of dietary sodium selenite at the concentration of 0.4 mg/kg Se had protective action against these toxic effects of AFB1.

Cell proliferation and differentiation during fracture healing are influenced by locally applied IGF-I and TGF-beta1: comparison of two proliferation markers, PCNA and BrdU

Growth factors IGF-I and TGF-beta1 are known to stimulate fracture healing. The purpose of this study was to investigate the role of locally applied IGF-I and TGF-beta1 during the early phase of fracture healing (Days 5, 10, and 15 after fracture) on cellular processes like proliferation and differentiation in a rat model. Two different immunohistochemical markers were used to analyze cell proliferation: (1) injection of the thymidine analogue BrdU and subsequent immunohistochemical staining for BrdU-positive nuclei, and (2) the antibody against the "proliferating cell nuclear antigen" (PCNA). In comparison, both methods revealed similar results concerning the types of proliferating cells at the different time points and the two groups. Labeling indices of both methods showed very good correlation (e.g., r(s): 0.887 and p < 0.001 at day 10 in the control group without growth factors). Comparison of the callus morphology and the proliferation rate showed differences during fracture healing due to the local application of IGF-I and TGF-beta1 from coated implants. At Day 5 the callus of the group treated with growth factors displayed an earlier appearance of cartilage compared to the control group. This was accompanied by an onset of cell proliferation in chondrocytes. Likewise, at the later time points an enhanced maturation of the callus tissue and the proliferation pattern were detectable in the growth-factor group. These results indicate that local application of IGF-I and TGF-beta1 accelerates early cellular processes during fracture healing.

Dietary restriction alters cell proliferation in rats: an immunohistochemical study by labeling proliferating cell nuclear antigen

Dietary restriction (DR) delays the onset of aging and lowers the incidence of both spontaneous and chemically induced cancers. The inhibition of cell proliferation has been suggested as a possible mechanism for this effect. We examined the effect of DR on cell proliferation in duodenum, forestomach, glandular stomach, and liver tissues of male Fischer 344 rats receiving 60% of the control feed intake for 24 months starting at 16 weeks of age. Rats were sacrificed, when 28 months old. Tissues were collected, histologically prepared, and stained immunohistochemically for proliferating cell nuclear antigen (PCNA). The PCNA-stained nuclei are detected in different phases of the cell cycle. A minimum sample of 2000 cells was counted in liver. The percentage of labeled S-phase cells per total cells counted was used as the labeling index for liver. The number of labeled S-phase epithelial cells per 1.1 mm of basement membrane or muscularis mucosa was used as the labeling index for duodenum, forestomach, and glandular stomach. Cell proliferation in glandular stomach and liver tissues was inhibited in rats DR for 24 months; however, cell proliferation in duodenum and forestomach mucosal tissues was unexpectedly enhanced by DR. These results indicated that while DR inhibits cell proliferation in tissues of rats, it is tissue-dependent. The decreased rate of cell division by DR in the designated tissues could be implicated in lowering the conversion of endogenous DNA damage or lesions to mutation and cancer.

Growth hormone plus high protein diet promotes adaptation after massive bowel resection in aged rats

OBJECTIVE

To determine whether GH improves adaptation following massive bowel resection in the aged rat fed on a high protein-content diet.

MATERIAL AND METHODS

Seventy-seven male Wistar rats aged 22+/-1 months underwent 80% bowel resection or laparotomy (sham-operation). They were randomly placed into one of eight groups, treated with either growth hormone (1mg/kg/day) or saline, and fed a liquid diet containing either a high or a normal protein content. Intestinal tissue and blood samples were taken seven days after surgery and analysed to measure intestinal mucosal proliferation and mucosal height, as well as plasma levels of IGF-1 and somatostatin.

RESULTS

Resection of the small bowel in aged rats remarkably increased villous height and crypt proliferation. Growth hormone did not potentiate the increase in mucosal height and crypt proliferation observed after intestinal resection in aged rats fed a normal protein content diet, but did in those receiving a high-protein diet. Plasma levels of IGF-1 and somatostatin were not modified by surgery or treatment.

CONCLUSION

Growth hormone may increase the adaptation of intestinal mucosa in aged rats undergoing massive intestinal resection, but requires an adequate nutritional support with increased amounts of high quality protein.

Growth hormone effects in intestinal adaptation after massive bowel resection in the suckling rat

BACKGROUND

Massive small bowel resection provokes intestinal malabsorption that leads to diminished growth in the suckling rat. Growth hormone is one of the several factors that can enhance the adaptive response of the intestines in the adult rat; however, whether it also enhances postresection intestinal adaptation in the suckling rat, thus reducing the adverse effects of resection on growth, is still unclear.

METHODS

Seventy-four 30-day-old suckling Wistar rats underwent 80% midgut bowel resection, laparotomy (sham operation), or no surgery. They were treated with either growth hormone or saline for 15 days and studied 15 or 45 days after surgery. Body weight was monitored and samples of bone and intestinal mucosa were obtained at the end of the study period for analysis.

RESULTS

Resected rats lost body and bone weight regardless of growth hormone administration. Bowel resection provoked significant increases in the proliferation and size of the intestinal mucosa. Growth hormone significantly, but just barely, increased crypt height and mucosal mass at day 15 after surgery, but not at day 45. Lengthening of the intestines was the main effect of growth hormone.

CONCLUSIONS

The relatively small adaptive response of intestines to growth hormone is insufficient to promote body growth after intestinal resection in the suckling rat. This response is lower than that in older rats and may reflect an age-related differential response to growth hormone.

Cyclo-oxygenase-2 inhibitors suppress epithelial cell kinetics and delay gastric wound healing in rats

BACKGROUND AND AIMS

The present study examined the effects of NS-398, a specific cyclo-oxygenase-2 inhibitor, on gastric mucosal cell kinetics and gastric wound healing following acid-induced injury.

METHODS

Male Sprague-Dawley rats were fasted for 24 h and then 0.6 mol/L hydrochloric acid (HCl; 1 mL) was administered into the stomach; NS-398 or indomethacin was administered to the animals 10 min after the acid. Levels of constitutive cyclo-oxygenase (COX-1) and mitogen-inducible cyclo-oxygenase (COX-2) in the gastric mucosa were analysed using western blotting and immunohistochemical staining. The grade of the lesion was assessed using planimetry and histological examination, including immunohistochemistry for proliferating cell nuclear antigen (PCNA).

RESULTS

Although there was strong expression of COX-1, there was minimal expression of COX-2 in the gastric mucosa. Expression of COX-2 was enhanced mainly in surface epithelial cells and neck cells following HCl administration. Gastric mucosal ulcers and erosions healed within 48 h, during which time the proliferative zone expanded in the control animals. Indomethacin and NS-398 suppressed the expansion of the proliferative zone and delayed the healing of the gastric injury.

CONCLUSION

The present study demonstrated that cyclo-oxygenase-2 inhibitors delay gastric wound healing by suppressing expansion of the mucosal proliferative zone. These results provide evidence that cyclo-oxygenase-2 has an important role in gastric mucosal regeneration.

Gut permeability, intestinal morphology, and nutritional depletion

Nutritional depletion increases the risk for postoperative complications. The intestinal barrier may be important in the underlying pathophysiologic mechanism. In this study, 26 patients were evaluated to determine whether nutritional depletion was related to gut integrity and intestinal morphology. Nutritional depletion was estimated by calculating percentage ideal body weight (PIB) or percentage ideal fat free mass (PIFFM). To assess gut integrity, a lactulose/mannitol (L/M) test was performed. Duodenal biopsies were taken, and villous height, crypt depth, number of IgA-producing plasma cells, intraepithelial lymphocytes (IELs), and proliferating index were determined. The L/M ratio was increased, and villous height was decreased in depleted patients. Depletion was not associated with differences in the number of immune cells or proliferating index. The number of IgA-producing plasma cells was positively correlated with the L/M ratio. This study shows that nutritional depletion is associated with increased intestinal permeability and a decrease in villous height.

Glutamine and intestinal immune cells in humans

BACKGROUND

Total parenteral nutrition (TPN) is associated with depletion of intestinal immune cells and increased gut permeability (GP). Adding glutamine (GLN) to TPN preserves GP by an unknown mechanism. Intestinal immune cells situated between the enterocytes (intraepithelial lymphocytes, [IEL]) influence GP in vitro. To obtain insight into the underlying mechanism of GLN on GP, we investigated the effects of GLN-supplemented TPN on IEL, immunoglobulin A (IgA) plasma cells and goblet cells, and enterocyte proliferation in intestinal biopsies.

METHODS

Twenty patients randomly received GLN-enriched TPN (GT) or isonitrogenous standard TPN (ST). Proliferation and number of immune cells were measured in intestinal biopsies obtained before and after 10 days of TPN.

RESULTS

No change in proliferative activity or in number of IgA plasma cells was observed. Goblet cells increased in the ST group, whereas the change seen in the GT group did not reach significance. In the GT group, IEL decreased, whereas in the ST group, no change in the number of IEL was observed.

CONCLUSIONS

TPN was not associated with changes in proliferative activity or with depletion of gut immune cells. The data indicate that GLN-supplemented TPN has a different effect on intestinal immune cells compared with standard TPN.

Glial, vascular, and neuronal cytogenesis in whole-mounted cat retina

A method was developed for detecting cytogenesis in retinal whole-mount preparations by bromodeoxyuridine (BrdU) immunohistochemistry. Because BrdU is a nonspecific marker that labels all cells in the S phase of the cell cycle, it is ideally combined with other cell-specific markers to study the cytogenesis of specific cell types. Double-label protocols to visualize mitotically active astrocytes and cells associated with the forming vasculature have been developed and applied to the retina. This approach revealed that, during normal development of the kitten retina, vascular mitogenesis occurs predominantly in the ganglion cell and nerve fiber layers, where the inner retinal plexus is formed by a process involving transformation of mesenchymal precursor cells and division of vascular endothelial cells. The peak density of vascular mitogenesis moved in a central-to-peripheral manner and was associated with the leading edge of the forming capillary plexus. A small number of dividing vascular endothelial cells was also associated with angiogenesis, the process responsible for the formation of the outer retinal plexus, vessels at the area centralis, and the radial peripapillary capillaries. Cytogenesis associated with astrocytes occurred in the ganglion cell and nerve fiber layers but was apparent predominantly at or close to the optic nerve head. Confirming earlier studies, neuronal mitogenesis was shown to occur predominantly at the ventricular zone, first at the area centralis and spreading peripherally with increasing maturity. A second region of neuronal cytogenesis, at the subventricular zone, was also apparent. Tissue hyperoxia decreased the rate of vasculogenic cell division but had no apparent effect on neurogenic or astrocytic cell division. Four distinct zones of cell generation were therefore identified within the retina, each associated with either glial, vascular, or neuronal cytogenesis. Thus, BrdU immunohistochemistry in whole-mounted retinal preparations offers a fast and reliable alternative to [3H]thymidine autoradiography for the study of the topography of cytogenesis during development.

C-myc is required for the G0/G1-S transition of primary hepatocytes stimulated with a deleted form of hepatocyte growth factor

Primary rat hepatocytes stimulated in vitro with the addition of a deleted form of hepatocyte growth factor (dHGF) enter the S-phase 48 h after addition of the growth factor. The c-myc gene is believed to play a role in a variety of cellular stages, such as proliferation, differentiation and cell death. In primary hepatocytes c-myc was expressed constitutively at both mRNA and protein levels, independently of the growth conditions. dHGF induced significant c-myc expression at times correlated with the long-lasting pre-S phase, and no induction was observed at the G0/G1 traverse compared with the unstimulated hepatocytes. An antisense construct coding for all three exons of c-myc was imported into hepatocytes by using the transferrin receptor-mediated endocytosis methodology (transferrinfection). Expression of the antisense construct inhibited the biosynthesis of the c-Myc protein, however it did not interfere with the expression of c-met, encoding the receptor for HGF/dHGF. Continuous expression of the antisense construct inhibited entry of the hepatocytes into the S-phase. Regulated induction of the antisense c-myc by dexamethasone for up to 6 h in culture, did not interfere with the entry of hepatocytes into the S-phase. c-myc expression was shown to be required between 6 and 12 h in dHGF-stimulated hepatocytes, and inhibition of its expression during this time by the antisense myc construct did not allow these cells to enter the S-phase. Inhibition of c-myc biosynthesis between 24 and 48 h hours slightly affected the DNA synthetic response. It is proposed that the expression of c-Myc protein interferes with the "priming' of hepatocytes to become responsive to growth-factor stimuli, or in the absence of such stimuli it interferes with the maintenance of a non-proliferating phenotype and subsequent in vitro de-differentiation.

Detection of ras oncogene point mutations and simultaneous proliferative fraction estimation in gallbladder cancer

Gallbladder cancer is notorious for its poor clinical evolution; so, a study of parameters with any prognostic potential is of particular interest. In this study, we investigated 23 adenocarcinomas regarding both the presence of point mutations in the ras gene family and the quantitative expression of Proliferating Cell Nuclear Antigen (PCNA). We respectively used molecular biology techniques and immunohistochemistry. Our results were related to several clinicopathologic determinators as well as to patients' survival. Mutations in codon 12 of the K-ras gene were detected in four gallbladder neoplasms (17%). This specific type of mutation is likely to be partially involved in this organ's tumourigenesis, particularly since no H-ras codon 12 or K-ras codon 13 (aspartic acid) mutations were detected in any of our specimens. PCNA immunoreactivity was generally limited in all tumours studied except for those morphologically characterized as being particularly aggressive. Notably, the four tumours in which K-ras mutation was detected, demonstrated relatively high PCNA positive immunoexpression in their malignant cells. This finding reinforces a possible correlation between the presence of ras mutations and increased cell growth. Staging was the only factor which was statistically associated with survival (p < 0.01). Therefore, the poor evolution of this cancer is probably due to late diagnosis and not related to a model of increased biologic aggressiveness.

Proliferative activity of gastric epithelium in progressive stages of Helicobacter pylori infection

Helicobacter pylori (HP) infection is the main etiopathogenetic agent responsible for inflammatory and ulcerative changes in gastroduodenal mucosa and the basis for both intestinal and diffuse types of gastric carcinoma. In this latter case, intestinal metaplasia is the intermediary between gastritis and cancer. In this study we describe the proliferative activity of gastric epithelium in the progressive stages of HP infection. The expression of proliferating cell nuclear antigen (PCNA), which has proven to be a reliable method for this evaluation, was used as a marker. The study was performed on endoscopic biopsies of the gastric antrum of 40 patients, who were divided into five groups, eight in each group: normal histology and endoscopy, HP-; histological HP+ gastritis with normal endoscopy; histological HP+ gastritis with endoscopic evidence of chronic erosions; complete and incomplete intestinal metaplasia in a HP+ stomach. PCNA was detected by immunohistochemistry and expressed as labeling index, ie, percentage of positive nuclei either in the whole or upper third of foveolae. Our data show a progressive increase of epithelial proliferation in the successive stages of HP infection ranging from gastritis alone to the development of incomplete intestinal metaplasia, a well-known precancerous condition. The proliferative pattern tended to expand towards the upper foveolar third, which in normal conditions does not represent a site of epithelial renewal. These alterations may be related to the development of neoplastic transformations of gastric epithelium. It is well known that genetic mutations are facilitated in proliferating cells. Therefore, our results indicate that the high epithelial turnover, expressed by PCNA LI, may be an indicator of increased risk of neoplastic changes in long-standing untreated HP+ chronic gastritis.

Assessing cellular proliferation: what's worth measuring?

The assessment of cellular proliferation is, in the main, carried out on histological material. Ideally, such methods should be applicable to routinely processed tissues, they should be relatively inexpensive and the results easily quantified and interpreted. A knowledge of what is 'normal' within the tissue from both a temporal and spatial point of view is essential. There is a burgeoning literature on novel markers of cell proliferation, usually these are immunohistochemically based, each method with its own unique set of conditions for optimal tissue processing. Some would argue this is simply a process of 'reinventing the wheel' since mitotic counting is a perfectly adequate indicator of proliferation, but we could justly counter that a labelling index (S-phase or growth fraction) is more likely to produce an accurate assessment when the sample size is small. In tumours, tissue heterogeneity is likely to render any single measurement meaningless. To date, there are no reliable validated immunohistochemical markers of the labelling index in animal tissues which visualise naturally occurring proliferation-associated molecules, though this may change shortly.

A cautionary note regarding the application of Ki-67 antibodies to paraffin-embedded breast cancers

Immunocytochemical studies examining the Ki-67 proliferation marker in paraffin-embedded material have recently been made possible by the availability of several antibodies, notably MIB-1, which are readily applicable to microwaved sections. Using breast cancer material, the present study examines correlations shown by these new paraffin assays and also by PCNA (proliferating cell nuclear antigen), an existing marker of proliferation, with the established Ki-67 cryosection assay. Paraffin sections were microwaved prior to incubation with Ki-67 or MIB-1 antibodies. Signal detection was carried out with a biotinylated secondary antibody, peroxidase-conjugated streptavidin, and DAB/H2O2 chromogen. The results suggest that caution is required when studying proliferation in paraffin-embedded breast cancers by immunostaining using Ki-67 antibodies. Nuclear staining in wax sections (Ki-Par, MIB-1, PCNA) greatly exceeded that in cryosections (Ki-Froz) and thus correlations were notably absent between Ki-Par or PCNA immunostaining and the routine Ki-Froz assay. Immunostaining with MIB-1 or PCNA may, however, be useful to assess proliferation if cut-offs are applied to eliminate weak immunostaining associated with wax sections. Thus, an approximately linear relationship was seen between MIB-1/Ki-Froz, which was improved if only moderately or moderately/strongly MIB-1-positive cells were scored. Similarly, a significant correlation was also revealed between PCNA/Ki-Froz if such a cut-off was applied.

Proliferating cell nuclear antigen (PCNA) immunostaining--a prognostic factor in ovarian cancer?

The measurement of tumour cell proliferation is becoming increasingly recognised in defining prognostic groups. Proliferating cell nuclear antigen (PCNA) immunolocalisation can be used as an index of cell proliferation and may define the extent of departure from normal growth control. The monoclonal antibody PC10 stains PCNA in archival paraffin-embedded tissue. This study investigates its potential as a prognostic marker in early and advanced ovarian cancer. A three-stage immunoperoxidase technique was developed to detect the monoclonal antibody PC10. Archival paraffin-embedded tissue from 19 stage I ovarian tumours (13 malignant and six borderline) and 79 advanced (stage IIb-IV) ovarian tumours (patients entered into the Third North-West Thames Ovarian Cancer Trial) was immunostained with PC10. PC10 immunostaining was performed successfully in 91.8% of cases. The PC10 labelling index (PC10 LI) ranged from 1.5% to 88% with a mean value of 47.4%. Stage I borderline tumours had significantly lower PCNA labelling indexes than stage I malignant tumours (P < 0.048). In advanced disease there was an inverse correlation between PC10 and overall survival, and in those patients who underwent good debulking surgery (37 patients with disease < 2 cm diameter) a low PC10 value (< 36.5%) correlated with improved survival (log-rank trend test for survival, chi 2 = 5.75, P = 0.017). PCNA immunostaining defines a good prognostic subgroup in adequately debulked patients with ovarian cancer.

Expression of proliferating cell nuclear antigen in hyperplastic polyps, adenomas and inflammatory cloacogenic polyps of the large intestine

AIMS

To compare proliferating cell nuclear antigen (PCNA) immunoexpression in hyperplastic polyps, adenomas, and inflammatory cloacogenic polyps of the human colon and rectum using paraffin wax embedded tissue.

METHODS

The monoclonal antibody PC10 was used to demonstrate PCNA immunoreactivity in 88 polypoid lesions from 68 patients. Cases in which immunoexpression was completely absent were excluded, leaving 32 hyperplastic polyps, 31 adenomas, and seven inflammatory cloacogenic polyps for analysis. Labelling indices for the upper and lower third of each lesion and for adjacent normal mucosa were calculated.

RESULTS

The upper third labelling indices for adenomas were substantially higher than those for hyperplastic polyps or normal mucosa, whereas those for the upper thirds of hyperplastic polyps and normal mucosa did not differ greatly. The differences between the lower third samples were not significant. In 16 (50%) hyperplastic polyps positive cells persisted onto the luminal surface. Some adenomas showed the most intense staining and the highest labelling indices in the upper third, with strong staining of surface cells; this pattern was not seen in the other lesions. The inflammatory cloacogenic polyps did not show a consistent pattern of immunoexpression.

CONCLUSIONS

Differences in cell kinetics between adenomas, hyperplastic polyps, and normal mucosa may be shown in formalin fixed, paraffin wax embedded tissue using PC10 as a marker of proliferative activity. PCNA expression also persists into the upper portions of hyperplastic polyps. Assuming that hyperplastic polyps are hypermature lesions with a slower rate of cell migration, this finding suggests that there may be an alteration in PCNA protein metabolism.

Hepatocyte proliferation in primary biliary cirrhosis as assessed by proliferating cell nuclear antigen and Ki-67 antigen labelling

Expression of the proliferating cell nuclear antigen and Ki-67 antigen by hepatocytes was investigated in liver tissue specimens of 29 patients with primary biliary cirrhosis (stage I 13, stage II 6, stage III 5 and stage IV 5 patients) prior to treatment with ursodeoxycholic acid and of five control subjects using immunocytochemical methods. Proliferating cell nuclear antigen and Ki-67 expression were reevaluated in seven patients after 3 years of treatment with ursodeoxycholic acid. Proliferating cell nuclear antigen labelling indices were significantly higher in primary biliary cirrhosis (stage I, 6.4% to 32.4%, median, 10.9%; stage II, 9.6% to 21.6%, median 11.4%; stage III, 5.2% to 12.5%, median, 7.6%; stage IV, 3.8% to 8.9%, median, 5.6%) than in controls (0% to 0.5%, median, 0.1%; p < 0.005). Ki-67 antigen labelling counts were lower than proliferating cell nuclear antigen indices but elevated in all stages of primary biliary cirrhosis (stage I, 0.5% to 3.5%, median 2.0%; stage II, 1.8% to 3.6%, median 2.6%; stage III, 1.3% to 2.5%, median 1.9%; stage IV, 0.4% to 1.7%, median 1.0%) compared with controls (0% to 0.5%, median 0.3%; p < 0.005). After ursodeoxycholic acid treatment, mean proliferating cell nuclear antigen and Ki-67 labelling indices decreased from a median of 9.0% (range, 3.8% to 32.4%) to a median of 7.8% (range, 4.5% to 17.2%; p = 0.045) for proliferating cell nuclear antigen and from a median of 2.5% (range, 0.8% to 3.6%) to a median of 2.1% (range, 0.9% to 3.1%; p = 0.031) for Ki-67 antigen. It is concluded that hepatocyte proliferation is markedly increased in primary biliary cirrhosis, particularly in the early stages of the disease, and that ursodeoxycholic acid treatment reduces proliferative activity in primary biliary cirrhosis.

Divergent effects of epidermal growth factor and calcipotriol on human rectal cell proliferation

Vitamin D may protect against colorectal cancer by reducing cell proliferation and inducing differentiation. By contrast, epidermal growth factor (EGF) stimulates cell proliferation and may encourage gastrointestinal mucosal healing. This study investigated the effect of a synthetic vitamin D analogue, calcipotriol, and EGF on human rectal epithelial cell proliferation in patients with familial adenomatous polyposis (FAP). In addition, a new technique to measure the cell cycle time is described. Sigmoidoscopic biopsy specimens were obtained from 14 patients with FAP. Tissue was established in organ culture, with or without the addition of EGF (n = 8), or calcipotriol (n = 6). Proliferation was determined using (a) metaphase arrest to measure the crypt cell production rate, (b) native mitotic index, and (c) the growth fraction using PC10 antibody. EGF receptor expression was shown using a polyclonal antibody AP12E. Calcipotriol reduced crypt cell production rate by 52% from mean (SEM) 5.29 (1.18) to 2.56 (0.80) cells/crypt/hour (p < 0.01) and EGF increased crypt cell production rate by 102% from 3.62 (0.59) to 7.33 (0.90) cells/crypt/hour (p < 0.05), and this tissue expressed the EGF receptor. The growth fraction was 48.40 (4.0)%, and the native mitotic index 1.08 (0.14)%. The cell cycle time was estimated as 94.5 hours and the time for mitosis as one hour. Thus, calcipotriol and EGF have divergent effects on human rectal mucosal proliferation.

Comparison of different monoclonal antibodies for the immunohistochemical assessment of cell proliferation in routine colorectal biopsy specimens

In a series of paraffin-embedded colorectal biopsy specimens the monoclonal antibodies 19F4 and PC10 against the proliferating cell nuclear antigen (PCNA) and the antibody mib1, which recognizes the Ki67 antigen in formalin-fixed material, were compared with the Ki67 method on equivalent frozen sections to assess the applicability of these 'proliferation markers'. A high correspondence was found between the localization of the mib1 and the Ki67 immunoreaction product, associated with a highly significant quantitative correlation of the two indices (r = 0.70, p < 0.001). In contrast, after formalin fixation the two PCNA antibodies additionally stained cells outside the proliferative compartment so that a reliable assessment of cell proliferation was only possible after controlled paraformaldehyde or methacarn fixation. In the routine material mib1 was superior to PC10 because of its ability to distinguish the differences in cell proliferation among normal colorectal mucosa (29.1 +/- 6.8% positive cells), adenomas (43.3 +/- 10.6%), and carcinomas (52.9 +/- 8.7%), which PC10 did not possess (normal, 41.4 +/- 5.6%; adenomas, 37.5 +/- 8.7%; carcinomas, 51.5 +/- 8.2%).

Toxicological and pathological applications of proliferating cell nuclear antigen (PCNA), a novel endogenous marker for cell proliferation

A major stimulus to study cell proliferation, particularly in rodent carcinogenicity assays and human tumors, has been the belief that the quantification of this fundamental biological process will provide the toxicologist and pathologist with objective data allowing a better understanding of the mechanisms involved in the toxicity and/or carcinogenicity of certain compounds as well as guiding more effective management of patients afflicted with neoplasia. Among the markers used for cell proliferation measurement, PCNA has recently gained much attention and holds much promise as it is intricately involved in the cell replication processes. It not only could allow measurement of the replication rates without necessitating pretreatment of the animal/tissue in prospective studies, but also would allow retrospective assessment of the proliferative rates in archival tissues due to the conservation of this marker in fixed and paraffin-embedded tissues. Finally, knowledge of the function of PCNA in the cell cycle and its regulation by other factors may help us understand the advantages and limitations of PCNA as a cell proliferation marker in its application in toxicology and as a prognostic marker in human tumors.