Squamous cell Carcinomas of the Head and Neck Cultured in Floating Collagen Gels: 1. The Maintenance of Stromal and Epithelial Elements in Vitro without Fibroblast Overgrowth

The study of the molecular biology of head and neck squamous cell carcinomas has been heavily reliant on the analysis of cell lines. This is largely because the maintenance of primary cell cultures is difficult. However, being monoclonal, cell lines are not representative of the primary tumor because of the loss of tumor cell heterogeneity. We report a technique for primary culture of squamous cell carcinomas with maintenance of epithelial and stromal cell components without overgrowth of the fibroblast cells. Phenotypic markers for fibroblasts and squamous cells were present up to 45 days after initiation of culture, and expression of epidermal growth factor receptor and involucrin in cultures paralleled that in the primary tumor. In vivo, tumor stromal elements are thought to play an important role in the support of epithelial cell growth. In the collagen gel system the preservation of the stromal cell component likely improves culture viability and growth. More importantly, this culture system allows the in vitro tumor to more accurately reflect the tumor from which it was derived, and it permits the study of primary squamous cell carcinomas under in vitro conditions.

Proliferating cell nuclear antigen (PCNA) and Ki-67 immunopositivity in human astrocytic tumours

To compare the Ki-67 and Proliferating Cell Nuclear Antigen (PCNA), markers of cell proliferation, paraffin embedded surgical specimens from 56 human astrocytic tumours (8 pilocytic tumours, grade I; 9 low (II) grade and 9 anaplastic (grade III) astrocytomas and 30 glioblastomas, grade IV) were immunolabelled with the anti-PCNA (PC 10, DAKO) and anti-Ki-67 (DAKO) antibodies. For the latter immunostaining the microwave oven processing was performed. The Ki-67 and PCNA labelling indices (LIs) were statistically compared. For the majority of cases, PCNA LI was higher than that obtained with anti-Ki-67 antibody and the intensity of staining for PCNA was more variable. The statistically significant difference of the percentage of PCNA LIs was found only between low grade (I and II) and high grade (III and IV) tumours, while Ki-67 LIs discriminates each group of glial tumours; thus this latter marker is more sensitive and specific.

Comparative evaluation of p53-protein expression and the PCNA and Ki-67 proliferating cell indices in human astrocytomas

Mutations of the p53 gene are one of the most frequent genomic alterations of human tumours of astrocytic lineage. Because the physiological role of this gene is a suppression of cellular proliferation and growth, the overexpression of p53-protein may correlate with the expression of PCNA or Ki-67, established markers of cell proliferation. Paraffin-embedded surgical specimens from 60 human astrocytomas (9 pilocytic tumours, 12 WHO grade II, 9 anaplastic astrocytomas [WHO grade III] and 30 glioblastomas [WHO grade IV]) were stained with anti-PCNA (PC10), anti-p53(DO-7) and anti-Ki-67 antibodies (DAKO). Approximately 40% of all the cases were p53-protein immunopositive (53.3% glioblastomas, 33.3% anaplastic, 41.7% low grade astrocytomas but no pilocytic tumor). Statistical analysis did not reveal statistically significant correlation between p53-immunopositivity and PCNA or Ki-67 labeling indices. The Ki-67- and PCNA LI-s were statistically correlated, and the former better discriminated groups of different grades of malignancy.

Rectal cancer: the influence of tumor proliferation on response to preoperative irradiation

PURPOSE

Regression of rectal carcinoma after preoperative irradiation is variable, likely reflecting differences in the physical and biologic properties of these tumors. This study examines the association between the pathologic response of rectal cancer after irradiation and its pretreatment proliferative state as assayed by the activity of the proliferative dependent antigens (Ki-67, PCNA) and mitotic counts.

METHODS AND MATERIALS

One hundred and twenty-two patients with locally advanced rectal cancer received preoperative irradiation followed by surgery. Pretreatment tumor biopsies were scored for the extent of Ki-67 and PCNA immunostaining and the number of mitoses per 10 high-powered fields. Postirradiation surgical specimens were examined for extent of residual disease.

RESULTS

The tumors of 38 of 122 patients (31%) exhibited marked pathologic downstaging (no residual tumor or cancer confined to the rectal wall) after preoperative irradiation. Two features were associated with the likelihood of marked pathologic regression after preoperative irradiation: tumor proliferative activity and lesion size. When stratified by lesion size, marked tumor regression occurred most frequently in smaller tumors with high Ki-67, PCNA, and mitotic activity compared to larger tumors with lower Ki-67, PCNA, and mitotic activity. Intermediate downstaging rates were seen for small or large tumors with moderate Ki-67, PCNA, and mitotic activity.

CONCLUSION

Tumor Ki-67, PCNA, and mitotic activity predicts the likelihood of response to irradiation, which may aid in formulating treatment policies for patients with rectal cancer.

Detection of proliferating cell nuclear antigen in tissues of three small fish species

An immunohistochemical assay for proliferating cell nuclear antigen (PCNA) identifies cells in all active phases of the cell cycle. In this study, PCNA methodology, which was developed primarily for mammalian tissues, was adapted to three small fish species, medaka (Oryzias latipes), guppy (Poecilia reticulata), and western mosquitofish (Gambusia affinis) that are used in carcinogenesis bioassays and environmental sentinel studies. Our study showed that PCNA can be identified in routinely processed, paraffin embedded specimens of these fishes. Optimum staining conditions were dependent on fixative, primary antibody, antigen retrieval processing, and protein blocking reagent. Best results were achieved using 10% neutral buffered formalin as the fixative, clone PC10 as the primary antibody, and a combination of powdered milk and bovine serum albumin as a protein block. Except for medaka specimens, antigen retrieval was not required for specimens preserved in 10% neutral buffered formalin, but was required for the other fixatives tested. In whole fish specimens, PCNA marked cells in normally proliferating tissues such as testis, ovary, primary filament epithelium of the gill, hematopoietic tissues, thymus, retina and alimentary tract. The study demonstrated the successful application of mammalian-based PCNA technology to these aquatic species. Further applications of the assay will aid in understanding the role of cell proliferation in normal, diseased, and toxicant-affected tissues of aquatic animals.

Methodologies for the preservation of proliferation associated antigens PCNA, p120, and p105 in tumor cell lines for use in flow cytometry

The retention of antigen expression of PCNA, p120, and p105 in two tumor cell lines (MOLT-4 and MDA-MD-175-VII) under various conditions of fixation was investigated using flow cytometric analysis. Four currently utilized procedures for fixation/permeabilization of intracellular antigens were compared for their ability to stain the nuclear antigens. A procedure using a brief incubation in a solution of lysolecithin in paraformaldehyde followed by fixation in ice-cold methanol prior to antibody staining was selected to evaluate reagent protocols aimed at preserving antigen expression. Holding samples overnight at 4 degrees C in 2.5% fetal bovine serum after the lysolecithin/paraformaldehyde and methanol fixation steps prior to staining with monoclonal antibodies resulted in no decline in the percentage of cells positively stained for all three markers with little decrease in intensity of fluorescence and no increase in DNA coefficient of variation (c.v.). Fixed/permeabilized MOLT-4 cells held longer than 24 h before staining were lower in PCNA fluorescence than freshly stained cells; holding samples of either cell line longer than 48 h resulted in decreased PCNA and p120 staining. Prefixing and holding cells in 50% methanol or 50% ethanol overnight before processing and staining severely depressed PCNA and p120 fluorescence. Prefixing either cell line in a range of concentrations (0.25-1.0%) of paraformaldehyde also resulted in reduced intensity of PCNA and p120 fluorescence along with increased DNA c.v. P105 staining appeared to be relatively unaffected by all prefixation/storage conditions tested, except for a decline of fluorescence when MDA cells were prefixed in 50% ethanol. Cells cryopreserved in liquid nitrogen for 1 week before processing showed < 5% loss of PCNA and p120 fluorescence compared to freshly processed cells, but p105 fluorescence dropped 29% in cryopreserved MDA cells. These results underscore the fact that specific protocols for the fixation and storage of biological samples prior to staining and analysis must be determined for the specific nuclear antigen marker under investigation.

Proliferating cell nuclear antigen expression in Wistar rat livers. A retrospective immunohistochemical study of normal and neoplastic livers

Formalin-fixed, paraffin-embedded liver specimens from 27 2-year-old Wistar rats, including 10 normal livers, 11 hepatocellular adenomas, 2 hepatocellular carcinomas, and 4 cystic cholangiomas, were immunostained using the streptavidin/peroxidase method and the PC10 monoclonal antibody (Mab), which recognizes an epitope on the proliferating cell nuclear antigen (PCNA). The following PCNA labeling index (LI) mean values were found for the above four groups of liver specimens: normal livers, 0.43 +/- 0.31%; hepatocellular adenomas, 1.51 +/- 0.59%; hepatocellular carcinomas, 24.80% +/- 10.28%; and cystic cholangiomas, 0.61 +/- 0.21%. Our findings indicate that PCNA LI clearly separates liver malignancies from other benign liver tumors, as well as from normal, non-neoplastic, liver tissues. Although the mean PCNA LI values seemed to reflect histological grading (i. e. normal, neoplastic benign, neoplastic malignant), overlapping between normal livers and hepatocellular adenomas was observed in five cases (i. e. in 2 normal livers and 3 hepatocellular adenomas, where the PCNA LI values varied between 0.74% and 0.96%). It thus appears that PCNA immunohistochemistry represents a promising tool for investigating liver cell proliferation in laboratory rats, and permits distinguishing between benign and malignant liver parenchymal tumors.

Pseudomalignant spindle cell proliferations of the urinary bladder

Twelve cases of polypoid, nonrecurrent, pseudomalignant spindle cell proliferations of the urinary bladder (eight women and four men) were analyzed. Two patients had a simultaneous urinary bladder carcinoma. The lesions were characterized by proliferating spindle- or strap-shaped cells, which on electron microscopic examination (performed in all 12 cases) revealed characteristics of fibroblasts and myofibroblasts. The cells showed immunoreactivity for vimentin in all cases, for alpha-smooth muscle-specific and muscle-specific actin in six cases, for cytokeratins in five cases, and for CD 34 in one case. No immunoreactivity was observed for desmin, myoglobin, epithelial membrane antigen, S-100 protein, endothelial cell antigen (H and Y), CD 68, or factor VIII RAG. Immunoreactivity for Ki-67 and proliferating cell nuclear antigen was detected in up to 30% of the spindle cell nuclei. The static cytometric DNA analysis revealed a diploid, or in two cases a hyperdiploid, stem cell line. An awareness of this type of spindle cell lesion and its immunophenotypic characteristics and diversity is of importance to avoid an erroneous diagnosis of spindle cell sarcoma (in particular leiomyosarcoma and embryonal rhabdomyosarcoma) or spindle cell carcinoma.

Proliferating cell nuclear antigen (PCNA) expression of megakaryocytopoiesis in normal human bone marrow and reactive lesions with special emphasis on HIV-myelopathy

A morphometric analysis was performed on bone marrow trephine biopsies using sequential double-immunostaining, to evaluate endoreduplicative activity of megakaryocytopoiesis. A total of 104 marrow specimens were studied with employment of monoclonal antibodies PC10 (anti-proliferating cell nuclear antigen-PCNA) and Y2/51-CD61 (anti-platelet glycoprotein IIIa). In addition to the control group patients included non-specific inflammatory changes, HIV-myelopathy with normal or decreased platelet counts, idiopathic thrombocytopenic purpura (ITP), and finally reactive thrombocytosis (TH). To exclude an undue overexpression of PCNA, in a comparative pilot study we also applied MIB1 (Ki-67 antigen) on normal bone marrow specimens. In accordance with the various modalities of cell-cycle marker expression, no significantly different findings were disclosed. PCNA-labelling index was relatively low, ranging from 0.8 to 1.7% of the total megakaryocytopoiesis (promegakaryoblasts to mature platelet-shedding megakaryocytes). A significant relationship between megakaryocyte size and PCNA-expression was determinable. This implies that some of the cases with a prevalence of small megakaryocytes, like ITP, have the tendency to show a higher proportion of positively-stained cells. Moreover, this feature confirms a hypothesis postulating a decrease in the time for DNA-synthesis (S-phase) and a relative prolongation of the G1/G2-phases of the cell-cycle at higher ploidy levels (large-sized megakaryocytes). On the other hand, it may be speculated that some of the hyperpolyploid giant megakaryocytes may have reached their endstage of endoreduplication and enter into G0-phase. In comparison with the control group and the other entities under study, a significant reduction of PCNA-reactivity was recognizable in HIV-myelopathy accompanied by thrombocytopenia.(ABSTRACT TRUNCATED AT 250 WORDS)

Splenic haematopoiesis in primary (idiopathic) osteomyelofibrosis: immunohistochemical and morphometric evaluation of proliferative activity of erytro- and endoreduplicative capacity of megakaryopoiesis (PCNA- and Ki-67 staining)

Using monoclonal antibodies against proliferating cell nuclear antigen or PCNA (PC10) and the Ki-67 antigen (MIB1), an immunohistochemical and morphometric study was performed on routinely processed splenic tissue from ten patients with primary (idiopathic) osteomyelofibrosis (OMF). To determine the proliferation capacity of erythroid precursors and the endoreduplicative activity of megakaryocytes, corresponding antibodies (Ret40f and CD61) were applied in combination with the cell-cycle markers (sequential double-immunostaining). Morphometric analysis revealed no significant differences in PCNA or Ki-67 reactivity in either cell lineages. In comparison with previous studies on normal bone marrow, in splenic tissue showing myeloid metaplasia, the numbers of PCNA-labelled proerythroblasts, erythroblasts and megakaryocytes were conspicuously increased. Considering the ineffective erythropoiesis in OMF, there seemed to be a disproportional enhancement in PCNA and Ki-67 immunostaining of the red cell lineage. Similarly, the small size of megakaryocytes in advanced, OMF-associated myeloid metaplasia was in keeping with an impairment of endoreduplicative activity. In addition to various other contributory factors, anaemia in OMF may be partially caused by secondary folate (haematinic) deficiency. From experimental studies this defect is known to cause an abnormal arrest in the S-phase of the cell-cycle, comparable to that characterising pernicious anaemia. As a sequel of this pathomechanism, an undue overexpression of PCNA and Ki-67 has to be assumed, that is not necessarily associated with DNA synthesis or cell cycling.

Immunostaining for proliferating cell nuclear antigen: its role in determination of proliferation in routinely processed human brain tumor specimens

Alcohol- and formalin-fixed, paraffin-embedded samples of 71 brain tumors (35 gliomas, 22 metastatic carcinomas, 8 meningiomas and 6 other tumors) were investigated by immunocytochemistry with three different monoclonal antibodies against proliferating cell nuclear antigen (PCNA)/cyclin (19A2; 19F4; PC10). PC10 was found to work best; it is applicable to both alcohol- and formalin-fixed tumor samples. PCNA labeling indices (LIs) were compared in the same tumors with LIs obtained by Ki-67 immunostaining of frozen sections and by in vitro incubation with bromodeoxyuridine (BrdUrd); in the latter preparations, BrdUrd LIs could be compared with PCNA LIs in the very same areas of serial sections. In gliomas, PCNA LIs were 0.7-80.2% (mean 31.7%), in metastases 0-76.0% (mean 47.8%), and in meningiomas 0-53.0% (mean 19.3%). In general, PCNA LIs were highly significantly correlated with Ki-67 LIs (P = 0.0002) and BrdUrd LIs (P = 0.0001). However, when tumor subgroups are considered, only gliomas show a significant correlation with Ki-67 and BrdUrd LIs. Despite this statistical correlation, PCNA expression was out of proportion to proliferation indices as determined by both other methods in almost one third of all brain tumors. Immunocytochemistry for PCNA produces a broad spectrum of staining intensity of labeled nuclei, whose number is dependent upon the sensitivity of the immunocytochemical technique used. Thus, inter-observer and inter-laboratory variabilities in PCNA LI determination may occur. Overlapping of PCNA LIs between tumor subgroups of varying malignancy further limits the informational value for the individual case.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical analysis of the proliferative capacity of duct and acinar cells during ligation-induced atrophy and subsequent regeneration of rat parotid gland

To study the proliferative capacity of salivary gland, an animal model of regeneration was developed. A clamp, which induced atrophy in parotid gland by obstructing the main excretory duct but allowed restoration of duct patency following removal, was implanted in a series of rats. When it was removed (Day 7), the weight of the glands was reduced by 50% and acinar cells had decreased from 93.8% to 8.2% of total cell population. Regeneration occurred rapidly following removal of the clamp. The number and location of cycling intercalated, striated, and excretory duct cells and acinar cells were monitored using an antibody to proliferating cell nuclear antigen (PCNA). All cell types were induced to cycle but the predominant cell to cycle was the acinar cell. During regeneration the number of PCNA+ acinar cells increased 38.7-fold from steady-state values. Results demonstrate that acinar cells have a significant potential for cycling, contrary to current histogenetic theories of salivary gland tumourigenesis which exclude acinar cells as potential progenitor cells on the grounds of their putative limited cycling capacity.