Proliferating cell nuclear antigen (PCNA) and human malignant tumor nucleolar antigens (HMTNA) in nucleoli of human hematological malignancies

Mutant p53 perturbs DNA replication checkpoint control through TopBP1 and Treslin

Accumulating evidence supports the gain-of-function of mutant forms of p53 (mutp53s). However, whether mutp53 directly perturbs the DNA replication checkpoint remains unclear. Previously, we have demonstrated that TopBP1 forms a complex with mutp53s and mediates their gain-of-function through NF-Y and p63/p73. Akt phosphorylates TopBP1 and induces its oligomerization, which inhibits its ATR-activating function. Here we show that various contact and conformational mutp53s bypass Akt to induce TopBP1 oligomerization and attenuate ATR checkpoint response during replication stress. The effect on ATR response caused by mutp53 can be exploited in a synthetic lethality strategy, as depletion of another ATR activator, DNA2, in mutp53-R273H-expressing cancer cells renders cells hypersensitive to cisplatin. Expression of mutp53-R273H also makes cancer cells more sensitive to DNA2 depletion or DNA2 inhibitors. In addition to ATR-activating function during replication stress, TopBP1 interacts with Treslin in a Cdk-dependent manner to initiate DNA replication during normal growth. We find that mutp53 also interferes with TopBP1 replication function. Several contact, but not conformational, mutp53s enhance the interaction between TopBP1 and Treslin and promote DNA replication despite the presence of a Cdk2 inhibitor. Together, these data uncover two distinct mechanisms by which mutp53 enhances DNA replication: (i) Both contact and conformational mutp53s can bind TopBP1 and attenuate the checkpoint response to replication stress, and (ii) during normal growth, contact (but not conformational) mutp53s can override the Cdk2 requirement to promote replication by facilitating the TopBP1/Treslin interaction.

Nucleolus-derived mediators in oncogenic stress response and activation of p53-dependent pathways

Rapid growth and division of cells, including tumor ones, is correlated with intensive protein biosynthesis. The output of nucleoli, organelles where translational machineries are formed, depends on a rate of particular stages of ribosome production and on accessibility of elements crucial for their effective functioning, including substrates, enzymes as well as energy resources. Different factors that induce cellular stress also often lead to nucleolar dysfunction which results in ribosome biogenesis impairment. Such nucleolar disorders, called nucleolar or ribosomal stress, usually affect cellular functioning which in fact is a result of p53-dependent pathway activation, elicited as a response to stress. These pathways direct cells to new destinations such as cell cycle arrest, damage repair, differentiation, autophagy, programmed cell death or aging. In the case of impaired nucleolar functioning, nucleolar and ribosomal proteins mediate activation of the p53 pathways. They are also triggered as a response to oncogenic factor overexpression to protect tissues and organs against extensive proliferation of abnormal cells. Intentional impairment of any step of ribosome biosynthesis which would direct the cells to these destinations could be a strategy used in anticancer therapy. This review presents current knowledge on a nucleolus, mainly in relation to cancer biology, which is an important and extremely sensitive element of the mechanism participating in cellular stress reaction mediating activation of the p53 pathways in order to counteract stress effects, especially cancer development.

Three meta-analyses define a set of commonly overexpressed genes from microarray datasets on astrocytomas

Glioma is one of the most common tumors of the central nervous system, and one of its main types is astrocytoma. Microarray technology has been widely used to explore the molecular mechanism of cancer. It is universally accepted that meta-analysis considerably improves the statistical robustness of results, particularly in clinical research. To obtain the maximum reliability, we used three different meta-analyses to integrate the four microarray datasets, GSE16011, GSE4290, GSE2223, and GSE19728 (local), and defined the common differentially expressed genes (DEGs) in astrocytomas compared with normal brain tissue. Four DEGs, PCNA, CDC2, CDK2 and CCNB2, which are components of the cell cycle pathway, were chosen for Real-Time Polymerase Chain Reaction (RT-PCR) and immunohistochemistry validation. PCNA is similar to the P53 gene and has been widely implicated in various cancers including gliomas. Therefore, the expression status of PCNA in our study was considered as a reference to test our whole experimental scheme, and the results indicate that our methodology is valid. Although a few studies have reported the overexpression of the CDC2, CDK2 and CCNB2 genes in glioma cell lines, we are the first to identify the statuses of these genes in human astrocytoma tissues at the mRNA and protein levels. The results of the gene validations strongly suggested that the genes play an important role in astrocytomas and could potentially be valuable in the diagnosis and treatment of astrocytoma.

Immunogold labelling of PCNA and Ki-67 antigen at the ultrastructural level in laryngeal squamous cell carcinoma and its correlation with lymph node metastasis and histological grade

Streptavidin-gold was used for the immunolocalization of PCNA and Ki-67 antigen at the ultrastructural level with a postembedding technique in biopsies of 15 patients with laryngeal squamous cell carcinoma. Positive immunoelectron staining was obtained in 9 cases for PCNA (60%) and in 8 cases for Ki-67 (53%). PCNA was predominantly found in heterochromatin of the nucleus of laryngeal carcinoma cells in a granular pattern. Positivity for PCNA was not found in nucleoli. In 4 cases, positive staining was observed both in nucleus and cytoplasm. In the cytoplasm, it was found to be present on the endoplasmic reticulum and on ribosomes throughout the cytoplasm. Ki-67 antigen was localized in the nucleus where it was associated with heterochromatin and euchromatin. It was also observed in nucleoli in all cases. Cytoplasmic localization of Ki-67 antigen was similar to that of PCNA. All 8 cases that were positive for Ki-67 were also positive for PCNA. Control incubations did not result in labelling with steptavidin-gold particles for both antigens. A significant correlation between PCNA and Ki-67 expression in association with pathological characteristics such as nodal status and histological grade was not found. Our data indicate that Ki-67 antigen staining correlates with PCNA labelling, whereas a relationship between proliferation markers and tumour progression was not found.

An RNA polymerase III transcription unit located in the upstream control regions of the human proliferating-cell nucleolar protein p120 gene is transcribed in vitro and in vivo

An RNA polymerase III (Pol III) transcription unit containing homology to highly repeated Alu sequences was identified in the upstream flanking sequences of the gene for the human proliferating-cell nucleolar antigen p120. When transcribed in vitro, this Pol III unit produced three RNA transcripts, designated by nucleotide length as T150, T385 and T635; RNA transcript T635 was the most abundant accounting for over 90%. The transcription initiates at nucleotide -729 of the human p120 promoter and proceeds in the opposite orientation to the p120 gene transcription. Northern blot analysis and cDNA cloning followed by sequencing showed the presence of the T635 RNA in HeLa cells, indicating that this Pol III transcription unit is functional and transcribed in vivo. Disruption of this Pol III transcription unit by deletion of the Box A residues (-733 to -744) resulted in a sixfold reduction of the p120 gene transcription. A possible role for this Pol III transcription unit in p120 gene transcription is discussed.

Stereotactic radiosurgery of the rat dunning R3327-AT1 prostate tumor

PURPOSE

Stereotactic radiosurgery (RS) is being used increasingly for the treatment of small benign and malignant lesions, particularly in the brain. However, to fully realize the potential of this technique, more experimental data are needed. In this report we describe an RS technique suitable for small animals, and present the results obtained with different irradiation doses and volumes given to a rat prostate tumor.

METHODS AND MATERIALS

Single doses of RS were administered to the Dunning prostate R3327-AT1 carcinoma transplanted subcutaneously into the thigh of male Copenhagen rats. The tumors (approximately 5 mm in diameter) were localized within a stereotactic frame and irradiated at a linac facility (15 MV) with single doses of 15.3, 30.6, 46.0, 61.3, or 76.6 Gy at the 80% isodose level using narrow beams from 3- and 5-mm collimators (80% isodose field size of 5 or 8.5 mm, respectively) and a six-arc irradiation technique. Tumor size was measured three times a week (Mondays, Wednesdays, and Fridays). Conventional stains were used to examine the histologic status of the tumors. To evaluate the proliferative response of the tumors to RS and assess the prevalence and spatial distribution of proliferating cells, tissue slices were stained with the proliferation markers 5-bromo-2'- deoxyuridine and proliferating cell nuclear antigen 4 and 8 h, and 4, 8, 12, and 210 days after stereotactic irradiation with a dose of 61.3 Gy.

RESULTS

The extent of growth delay and local tumor control depended on the radiation dose, the field size, and the accuracy of irradiation. Local control at day 100 ranged from two of eight rats at 30.6 Gy, five of seven rats at 61.3 Gy, and six of seven at 76.6 Gy. No overt side effects in the surrounding tissues was observed. After 61.3 Gy, the immunohistochemical staining revealed a rapid decrease of proliferative active tumor cells after irradiation. The irradiated tumor tissue was gradually replaced by connective tissue. However, in one persistent nodule, a few proliferative cells were detected even after 200 days.

CONCLUSION

A radiosurgical technique was successfully developed for a small animal system. The technique was concluded to be reproducible and suitable for future use in single and fractionated treatment regimens.

Immunohistochemical detection of proliferating cell nuclear antigen in middle ear cholesteatoma

Cholesteatoma epithelium is characterized by a keratinocyte dysregulation accompanied by destruction of the ossicles and temporal bone. Immunohistochemical methods using antibodies to cell-cycle-related antigens can be used as a means for assessing various aspects of proliferation in cholesteatoma tissue. They also have the important advantage of preserving the spatial orientation of proliferating cells in histological sections. Proliferating cell nuclear antigen (PCNA) is a 36 kDa DNA-delta-polymerase-associated protein that is directly involved in the mechanisms of DNA synthesis. In the present study the expression of PCNA was investigated in formalin-fixed, paraffin-embedded biopsy specimens of cholesteatomas and normal skin. Normal skin revealed nuclear staining in a small number of keratinocytes (PCNA grade, 1.5) located in the basal cell layer. In contrast, an increased number of PCNA-labeled basal and suprabasal epidermal cells (PCNA grade, 9.3) were found in cholesteatoma samples. Our findings indicate that PCNA represents a reliable marker for epithelial proliferation, showing that cholesteatoma epithelium proliferates at a higher rate than normal epidermis. These findings also support the concept of keratinocyte dysregulation in middle ear cholesteatoma.

Enhanced polymer one-step staining (EPOS) for proliferating cell nuclear antigen (PCNA) and Ki-67 antigen: application to intra-operative frozen diagnosis

Enhanced polymer one-step staining (EPOS) is a novel, highly sensitive one-step immunostaining method. This simple and rapid technique was applied to intra-operative frozen diagnosis. The markers of choice were proliferating cell nuclear antigen (PCNA) and Ki-67 antigen. These cell proliferation markers were both identifiable in fresh frozen sections of the human tonsil in approximately 7 min. The suitable staining sequences are as follows. Frozen sections prepared using 3-aminopropyltrimethoxysilane-coated glass slides are immediately fixed, without air drying, for 15 s in a mixture of 50% formalin and 50% methanol for PCNA, and in 10% formalin for Ki-67 antigen. After a brief rinse in phosphate-buffered saline (PBS), sections are incubated with the EPOS antibody for 3 min, followed by PBS rinse for 1 min. The peroxidase activity is visualized in diaminobenzidine-H2O2 solution containing 10 mmol/L imidazole for 2 min. After a light rinse in tap water, the nuclei are briefly counterstained with 5% methyl green. When necessary, endogenous peroxidase blockage in 1% periodic acid solution for 1 min is added before the EPOS antibody incubation. This procedure is applicable to frozen sections of gastric cancers, malignant lymphomas, and brain, liver and peritoneal lesions in which differential diagnosis between benignancy and malignancy was required.

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)

Proliferative activity of human thyroid tumors evaluated by proliferating cell nuclear antigen/cyclin immunohistochemical studies

BACKGROUND

To clarify the proliferative activity of human thyroid tumors, the labeling index of various thyroid tumors was evaluated by proliferating cell nuclear antigen (PCNA)/cyclin immunostaining.

METHODS

Surgically removed thyroid carcinoma, adenoma, adenomatous goiter, normal thyroid, and breast carcinoma were used for the study. Small pieces of tissue from the surgical materials were fixed in Methacarn solution (methanol-chloroform-acetic acid = 6:3:1) (Wako junyaku Co., Osaka, Japan) and embedded in paraffin. Sections were stained with PCNA/cyclin monoclonal antibody.

RESULTS

The reaction product for PCNA/cyclin was observed mainly on nuclei. The ratio of the PCNA/cyclin-positive nuclei to the total number of nuclei was compared among the tumors. Ratios of PCNA/cyclin-positive nuclei were 4.9% in well-differentiated papillary carcinoma of the thyroid, 4.6% in poorly differentiated papillary carcinoma of the thyroid, 3.6% in thyroid follicular carcinoma, 1.9% in adenomatous goiter, 2.0% in thyroid follicular adenoma, and 0.6% in normal thyroid tissues.

CONCLUSIONS

It was shown in this study that the ratio of PCNA/cyclin-positive nuclei reflects the relative clinical behavior of thyroid tumors.

Monoclonal antibody JC1: new reagent for studying cell proliferation

AIM

To characterise a newly developed mouse monoclonal antibody JC1 which recognises a nuclear antigen present in proliferating cells in normal tissues and neoplastic lesions, and which is absent in resting cells.

METHODS

The methodology was established using a representative range of frozen sections from normal tissues and from certain tumours which were immunostained with antibodies Ki67 and JC1. The molecular weight of the antigen recognised by JC1 was obtained by western blot analysis and this was compared with that of Ki67. IM-9 cell lysates containing Ki67 derived plasmids were also tested with JC1 antibody.

RESULTS

Biochemical investigation indicated that the antigen recognised by JC1 gives two molecular weight bands of 212 and 123 kilodaltons, which is distinct from the well characterised anti-proliferation monoclonal antibody Ki67 (395-345 kilodaltons). In addition recombinant Ki67 protein is not recognised by JC1. Immunohistological reactivity was seen in areas known to contain numerous proliferating cells such as lymphoid germinal centres, splenic white matter, cortical thymocytes and undifferentiated spermatogonia. In tumours many cells from adenocarcinomas, oat cell carcinomas, squamous cell carcinomas of lung, and seminomas were labelled by JC1 with a distribution and proportion similar to that seen with Ki67. In normal tissues the only apparent difference was in testis where JC1 stained a considerably greater number of cells than Ki67. In all cases studied the new antibody showed nuclear reactivity only. JC1 did not show any cytoplasmic crossreactivity with squamous cells as is frequently seen with Ki67.

CONCLUSION

Antibody JC1, which recognises a nuclear antigen present in proliferating cells, should provide a useful adjunct to Ki67 as a marker of proliferation especially in those cases such as squamous cell carcinomas where a Ki67 index cannot be determined.

Prognostic significance of the PC10 index as a prospective assay for cervical cancer treated with radiation therapy alone

The monoclonal antibody PC10 recognizes proliferating cell nuclear antigen (PCNA) in conventionally fixed and processed histologic materials. Formaldehyde-fixed and paraffin-embedded specimens taken from 194 patients with Stage III squamous cell carcinoma of the cervix treated with radiation therapy alone were investigated for PC10 positivity using immunohistochemical methods. A few squamous epithelial cells in the basal layer and the deepest zone of the prickle cell layer were positive for PC10. Cancer cells also were positive for PC10, showing a diffuse or granular nuclear staining pattern. The multiple logistic regression model analysis and the Kaplan-Meier method indicate that a strong correlation exists between the PC10 index and prognosis (P less than 0.001). Thus, the PC10 index may be a predictive indicator for the prognosis of patients with squamous cell carcinoma of the cervix treated with radiation therapy alone.

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.

Measurement of proliferation indices in non Hodgkin's lymphoma--is it useful?

In this review we discuss the possible value of additional information concerning growth characteristics of NHL's for the prognosis of the individual patient. Techniques for measuring cell cycle kinetic parameters (e.g. S-phase assessment) and proliferation related antigens (e.g. anti-transferrin receptor and Ki67) are shortly reviewed. This is followed by an overview of proliferation studies in NHL. Until now in most of these studies overall measurements of tumour tissue have been performed. Moreover the parameters that have been assessed are related to proliferation state rather than proliferation rate. None of the methods used has a convincing superiority with regard to clinical outcome. In the future, tumour specific assessment (by means of double-labeling techniques) of proliferation rate parameters might provide information, more relevant to the prognosis of the individual patient with NHL.

Distribution patterns and frequency of proliferating cells in cutaneous keratinocytic neoplasms. Immunohistochemical study with a monoclonal antibody (TOB7) used against proliferating cell nuclear antigen

BACKGROUND

Almost all markers for proliferating cells need freshly frozen tissues for evaluation; therefore retrospective study is impossible.

OBJECTIVE

In the present study, a murine monoclonal antibody (TOB7) against the proliferating cell nuclear antigen (PCNA) was used for the analysis of cell kinetics of cutaneous keratinocytic neoplasms. The antibody is applicable to formalin-fixed, paraffin-embedded tissues.

METHODS

The frequency of PCNA-positive cells and their distribution patterns were immunohistochemically investigated in various cutaneous keratinocytic neoplasms.

RESULTS

Squamous cell carcinoma and Bowen's disease showed significantly increased numbers of PCNA-positive cells when compared with other keratinocytic neoplasms. A characteristic marginal or random distribution pattern of PCNA-positive cells was observed in the lesions of each disease category.

CONCLUSION

Important information on the growth dynamics of keratinocytic neoplasms was obtained in this retrospective immunohistochemical study.

Cell proliferation in childhood acute leukemia. Comparison of Ki-67 and proliferating cell nuclear antigen immunocytochemical and DNA flow cytometric analysis

The proliferative activity of bone marrow leukemia cells was determined by DNA flow cytometric (FCM) analysis and labeling index (LI) of Ki-67 monoclonal antibodies and proliferating cell nuclear antigen (PCNA) autoantibodies in 73 children with acute leukemia. LI of Ki-67 varied greatly from patient to patient (range, 0.4% to 42.2%; mean, 18.8%) and differed significantly between acute lymphoblastic leukemia (ALL) and acute nonlymphoblastic leukemia (ANLL). In ALL, the Ki-67 LI showed a positive correlation with the S-phase fraction (SPF) determined by DNA FCM analysis, whereas, in ANLL, there was a discrepancy between the Ki-67 LI and SPF. In contrast, LI of PCNA varied less among the patients (range, 57.2% to 100%; mean, 90.3%), and the value was always higher than that of the Ki-67 LI in individual patients. A significant relationship between PCNA LI and the percentage of blast cells was found in peripheral blood leukocytes from patients with leukemia. These results suggest that the Ki-67 LI reflects differences in the proliferative activity depending on the subtype of the disease and that the PCNA LI is useful as a marker of proliferating cells.

Sp1 is essential and its position is important for p120 gene transcription: a 35 bp juxtaposed positive regulatory element enhances transcription 2.5 fold

Human proliferating cell nucleolar antigen p120 is expressed in tumor cells in the early G1 phase of the cell cycle. Deletion analyses of the essential cis-acting region -537/-278 showed that a 58 bp sequence from -457 to -400 is an important cis-acting element. An Sp1 transcription factor binds to the sequence AGAGGCGGGG (-425 to -416) within the -458/-400 cis-acting region. Deletion of the Sp1 binding sequence eliminated transcription. Substitution of the Sp1 box(-437/-406), containing the Sp1 recognition site, for the entire cis-acting region (-537/-278) restored transcription only at a very low level (18%). Deletion of the -537/-278 cis-acting region followed by substitutions showed that the Sp1 box (-437/-406) stimulated transcription 2.4 fold, when juxtaposed and downstream of a 35 bp (-472 GGGCGAGCGTAAGTTCCGGGTGCGGCGGCCGACTA -438) positive regulatory cis-element (PRE) over that by substitution of the Sp1 box alone. When the -406/-278 sequence was downstream of the PRE-Sp1 box, transcription was stimulated 4.4 fold over that produced by substitution of the Sp1 box alone. These results suggest that Sp1 is essential and its proper position in the 5' flanking sequence, juxtaposed and down stream of a 35 bp positive regulatory sequence, is required for efficient transcription.

Proliferating cell nuclear antigen and Ki-67 immunohistochemistry in brain tumors: a comparative study

Proliferating cell nuclear antigen (PCNA) is a 36-kDa DNA polymerase-delta auxiliary protein which accumulates in the nucleus during S phase of the cell cycle. Immunohistochemical labeling indices (LI) of PCNA and Ki-67 were compared using an avidin-biotin complex method on frozen sections of 27 nervous system tumors. 3 normal cerebral cortices, and 3 peripheral nerves. In glial tumors, PCNA and Ki-67 LI increased with increasing tumor grade (Daumas-Duport system). In 5 low-grade glial tumors, PCNA and Ki-67 LI were less than or equal to 1%, except for one optic nerve glioma (Ki-67 LI = 6%). In 7 grade 3 astrocytomas and 1 mixed glioma, PCNA LI were less than or equal to 1-1.5%, while Ki-67 LI were 2%-10%. In 7 grade 4 astrocytomas and 1 metastatic carcinoma, PCNA LI ranged from 6%-15% while Ki-67 LI ranged from 17%-30%. In 5 of 6 schwannomas, focally high PCNA LI (4%-65%) were noted, despite low LI with Ki-67 (less than or equal to 1.6%). Scattered normal schwann cell nuclei also stained with PCNA, but normal cerebral cortex did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferating cell nuclear antigen (PCNA)/cyclin expression during the cell cycle in normal and leukemic cells

Bivariate flow cytometric analysis of the cell proliferation-associated nuclear protein, identified as the "proliferating cell nuclear antigen" (PCNA)/cyclin and of nuclear DNA content, was performed in quiescent and mitogen-stimulated human peripheral blood lymphocytes, in EUE (human embryonic epithelium) cells, before and after a long-term exposure to a hypertonic (HT) medium, in 4 human leukemic cell lines and in fresh bone marrow (BM) cells from 10 patients with untreated acute non-lymphoblastic leukemia (ANLL). The PCNA/cyclin was detected using both an autoantibody extracted from sera of systemic lupus erythematosus patients and the recently produced mouse monoclonal antibody (MoAb) IgG, named 19F4. The distribution of cells in the different phases of the cycle and the percentage of S-phase cells were obtained in duplicate samples, by DNA flow cytometry (FCM) and by dual parameter FCM of DNA content and bromodeoxyuridine (BUDR) incorporation. In all cell types, the non-specific cytoplasmic background fluorescence was significantly lower with the MoAb compared to that obtained with the polyclonal Ab. The percentage of PCNA-positive cells (both with the autoantibody and the 19F4 MoAb) was always higher than that of S-phase cells by DNA FCM and of BUDR-labeled cells. The pattern of PCNA-expression in both normal proliferating cells and acute leukemia cells, showed that most G0/G1 cells did not express significant amounts of PCNA; an increase in PCNA immunofluorescence was found in late G1 cells, and further increases were observed in S- and G2-M phase cells. PCNA/cyclin, as revealed both with autoantibodies and with the 19F4 MoAb, is associated with all actively or potentially dividing (i.e. G1, S and G2-M) cells thus identifying the proliferative cellular compartment. Combined with the use of multiparameter FCM techniques, the PCNA immunolocalization offers a useful tool to study cell kinetics in normal and leukemic human cell populations.

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

Proliferating cell nuclear antigen (PCNA) is a 36 kD nuclear protein associated with the cell cycle. A monoclonal antibody, PC10, that recognizes a fixation and processing resistant epitope has been used to investigate its tissue distribution. Nuclear PCNA immunoreactivity is found in the proliferative compartment of normal tissues. PCNA immunoreactivity is induced in lectin stimulated peripheral blood mononuclear cells in parallel with bromodeoxyuridine incorporation and the number of cells with PCNA immunoreactivity is reduced by induction of differentiation in HL60 cells. In non-Hodgkin's lymphomas a linear relation between Ki67 and PCNA staining was demonstrated. These data suggest that in normal tissues and lymphoid neoplasms, PCNA immunolocalization can be used as an index of cell proliferation. However, in some forms of neoplasia, including breast and gastric cancer and in vitro cell lines, the simple relation between PCNA expression and cell proliferation is lost. In some breast and pancreatic tumours there is apparent deregulation of PCNA with increased expression in tissues adjacent to the tumours. The over-expression in some tumours and in adjacent morphologically normal tissue may represent autocrine or paracrine growth factor influence on PCNA gene expression.

The upstream sequence -537 to -278 is necessary for transcription of the human nucleolar antigen p120 gene

Two cis-acting elements in the p120 gene play important roles in transcription; the region from -537 to -278 is necessary for initiation of transcription, and the region from -1426 to -1223 is necessary for efficient transcription. The distal element(s) which lies upstream of -278 is required for initiation of transcription.

The upstream sequence -537 to -278 is necessary for transcription of the human nucleolar antigen p120 gene

Two cis-acting elements in the p120 gene play important roles in transcription; the region from -537 to -278 is necessary for initiation of transcription, and the region from -1426 to -1223 is necessary for efficient transcription. The distal element(s) which lies upstream of -278 is required for initiation of transcription.

Activated peripheral blood mononuclear cells detected by murine monoclonal antibodies to proliferating cell nuclear antigen in active lupus patients

Hybridoma producing monoclonal antibody to proliferating cell nuclear antigen (PCNA/cyclin) (TOB7, IgG1 kappa) was newly established. Using TOB7, PCNA was detected in the peripheral blood mononuclear cells (PBMC) in patients with systemic lupus erythematosus (SLE). Forty-four of 58 patients with SLE had PBMC expressing PCNA. The percentage of PCNA-positive PBMC in patients with SLE was 0-20% (mean: 2.63%) which was significantly higher (P less than 0.01) compared with normal controls (mean: 0.18%), patients with rheumatoid arthritis (mean: 0.83%), and patients with mixed connective tissue disease (mean: 0.38%). Patients with high numbers of PCNA positive PBMC tended to complicate pulmonary disorders (P less than 0.005), especially pulmonary fibrosis (P less than 0.005). In addition, the percentage of PCNA-positive cells in SLE patients correlated with the disease activity (r = 0.45, P less than 0.01). The lymphocyte subsets of PCNA-positive PBMC were examined, and most of those cells belonged to CD4- or CD8-positive T-cell populations in three lupus patients. Our findings indicate that PCNA-positive activated PBMC are present in SLE patients and the percentage of PCNA-positive PBMC may be used as an indicator of disease activity.

Expression of proliferating cell nuclear antigen/cyclin in human keratinocytes

The expression of proliferating cell nuclear antigen (PCNA), also called cyclin, in human keratinocytes was examined by using the serum obtained from a SLE patient and a murine monoclonal antibody against PCNA/cyclin. In the normal epidermis, few of the nuclei were labeled with anti-PCNA/cyclin. This was in contrast to the positive nuclear staining seen in active lesions of psoriasis. In a primary culture of human keratinocytes growing as a monolayer, 20%-30% of cells expressed PCNA/cyclin. SV40-transformed human keratinocytes showed positive nuclear staining in about 40% of the cell population. In stratified keratinocytes cultured in a high Ca++ medium, PCNA/cyclin expression was decreased and only the cells in the basal and suprabasal layers showed positive staining. These results indicate that the expression of PCNA/cyclin correlates with the proliferating state in human keratinocytes and may not be associated with the mechanism of differentiation in keratinocytes.

The use of a monoclonal antibody against a proliferating cell nuclear matrix antigen in the study of solid human tumors

A monoclonal antibody (MAb) identifies the nuclear antigen p125/6.5 associated with the nuclear matrix and present in proliferating human cells. By direct and indirect immunofluorescence, the presence and distribution of the antigen p125/6.5 in cryostat sections from primary and metastatic solid human tumors has been investigated. The antigen is present in nuclei of malignant and benign tumor cells, but is not detected in adjacent normal tissues. The antigen displays a speckled nucleoplasmic distribution, while nucleoli are negative. The intensity of the immunofluorescence reaction is markedly higher in the nuclei of some individual or grouped tumor cells.

The cell-cycle regulated proliferating cell nuclear antigen is required for SV40 DNA replication in vitro

Cell-free extracts prepared from human 293 cells, supplemented with purified SV40 large-T antigen, support replication of plasmids containing the SV40 origin of DNA replication. A cellular protein (Mr approximately 36,000) that is required for efficient SV40 DNA synthesis in vitro has been purified from these extracts. This protein is recognized by human autoantibodies and is identified as the cell-cycle regulated protein known as proliferating cell nuclear antigen (PCNA) or cyclin.

Immunochemical and biochemical analysis of the proliferating cell nuclear antigen (PCNA) in HeLa cells

PCNA, also known a cyclin, a protein of molecular weight (MW) 35 000, accumulates in the nuclei of dividing and transformed cells and reacts with autoantibodies from certain lupus patients. Using an indirect immunofluorescence technique, we show that lupus sera containing anti-PCNA antibodies reveal a heterogeneous nuclear fluorescence pattern upon reaction with asynchronous HeLa cells, whereas with synchronized cells a sequence of distinct patterns is disclosed on progression through the cell cycle. Cell-free translation of HeLa cell mRNA followed by immunoprecipitation with anti-PCNA sera shows a single protein with the same apparent MW as PCNA labelled in vivo, suggesting that PCNA is not derived from a larger precursor protein and not grossly modified by post-translational events. However, a group of at least nine nuclear polypeptides ranging in MW from about 12 000 to 110 000 are recognized by immunoblotting with anti-PCNA sera, indicating either that additional antigenic sites are produced on denaturation of native proteins or that additional autoantibodies are present in these sera. We also show that PCNA and several of these polypeptides are associated with nuclear structures containing chromatin.

Nuclear patterns of cyclin (PCNA) antigen distribution subdivide S-phase in cultured cells--some applications of PCNA antibodies

Immunofluorescence studies using PCNA autoantibodies specific for the proliferation-sensitive protein cyclin have revealed dramatic changes in the nuclear distribution of this protein during the S-phase of normal and transformed cells. Patterns of cyclin antigen distribution subdivide S-phase and have provided new cell cycle landmarks. Some of these (nucleolar exclusion or staining), mimic topographical patterns of DNA synthesis thus arguing for a role of this protein in some specific aspect of DNA replication. Cells outside S-phase (G0 included) stain only weakly with PCNA antibodies, stressing the usefulness of this reagent for identifying proliferating cells (S-phase cells) of both normal and malignant origins.

Ultracytochemical localization of X-prolyl-dipeptidyl (amino)peptidase in microglobules and endoplasmic membranes accumulated in pep4-3 mutant of Saccharomyces cerevisiae

The ultracytochemical localization of X-prolyl-dipeptidyl (amino)peptidase (DPP) activity was studied in a late exponential culture of a haploid (alpha) wild-type strain of Saccharomyces cerevisiae and its pep4-3 mutant. Yeast cells were fixed for 20 min in cold 1% glutaraldehyde buffered with 50 mM TES buffer to pH 7.0 and then incubated for 80 min with 1.2 mM L-alanyl-L-proline-4-methoxy-2-naphthylamide (Ala-Pro-MNA) or Lys-Pro-MNA as cytochemical substrates plus 0.06% hexazonium p-rosaniline (HPR) buffered with 160 mM cacodylate to pH 7.0. The osmiophilic azoindoxyl complex was formed by coupling HPR with MNA liberated by DPP activity and was then osmicated during an overnight post-fixation of cells in cold 1% OsO4. In the wild-type strain, conspicuous deposits of DPP reaction product were observed in vacuolar membranes. When compared with the parent strain, the pep4-3 mutant cells were enriched in endoplasmic reticulum (ER), cytoplasmic lipoprotein, and microcompartments: membranous vesicles and microglobules. In the mutant, DPP reaction product was found in about 50% of non-vacuolated cells at the following sites: the nuclear envelope, polar layers of ER sheets and of membranous vesicles (diameter, 40-90 nm), the surface or the lumen of these vesicles, the cytoplasmic membrane (under some bud scars) and the periplasmic space. The largest amount of reaction product was found in microglobules (diameter, 20-50 nm) that were mainly observed in the cytoplasmic matrix but were also present in nuclei (nucleoli) and mitochondria. These microglobules had a single-line boundary and appeared to be composed of lipoprotein. The surface ultrastructure of sectioned microglobules in the cytoplasmic matrix was similar to that of the coated vesicles found in mammalian cells. Only sparse amounts of DPP reaction product were seen in budding yeast. In all pep4-3 cells with electron-lucent vacuoles, the reaction product was confined to the vacuolar membranes (i.e. homologous to the ER), microglobules and the periplasmic space. Polysaccharides with free vic-groups were shown by the cytochemical reaction to be present on the surface of ER membranes, in microglobules, in the periplasmic space and in the cell wall. Our cytochemical results indicate that microglobules participate in the exocytosis of both DPP and glycoproteins, and reveal new features of vacuolar morphogenesis in yeast.

The spectrum of complement-fixing antinuclear antibodies in patients with hepatocellular carcinoma

Sera from 230 hepatocellular carcinoma patients were tested for antinuclear antibodies by anticomplement immunofluorescence in 16 types of transformed, diploid or primary cells of human, monkey, chimpanzee or rat origin. As controls, we tested 85 sera from patients with chronic liver diseases, 48 sera from patients with nonhepatic cancers and 164 sera of normal controls. Exactly 11.2% of all cancer patients but only 3.6% of noncancer patients had complement-fixing antinuclear antibody that reacted with all substrates. Only sera from hepatocellular carcinoma reacted with subsets of the tumor cell substrates. These sera reacted with hepatocellular carcinoma cells and nonhepatic cancer cells (antitumor) or only with one or more of the human hepatocellular carcinoma cell lines, PLC/PRF/5, Hep3B and Mahlavu, that were derived from HBsAg-positive patients (antihepatocellular carcinoma). Three of these reacted only with hepatitis B virus DNA-positive cells (PLC/PRF/5 and Hep3B) that contained "hepatitis B-associated nuclear antigen," 1 reacted only with hepatitis B virus DNA-negative Mahlavu cells, 1 reacted with PLC/PRF/5 and Mahlavu and 3 reacted with all 3 cells. The nuclear antigen in Mahlavu was expressed as a homogeneous fluorescence that spared the nucleoli, was present in a lower percentage of cells than hepatitis B-associated nuclear antigen and was more thermostable than hepatitis B-associated nuclear antigen. However, it resembled hepatitis B-associated nuclear antigen in kinetics of expression and susceptibility to digestion with DNase, RNase and proteinase K. The nature of the nuclear antigens in the hepatocellular carcinoma cells is poorly understood but one possibility is that they may represent the expression of viral or tumor-related genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Identity of the proliferating cell nuclear antigen and cyclin

Studies of growth regulation and cellular transformation will be assisted by the identification of proteins that are preferentially synthesized in dividing cells. The 'proliferating cell nuclear antigen' ( PCNA ), distinguished by its apparent association with cell division, is defined by reaction with an antibody found in the autoimmune disease systemic lupus erythematosus (SLE). This antibody reacts with proliferating cells including tumour cells but gives weak or undetectable immunofluorescence with resting cells of normal tissues. Peripheral blood lymphocytes are devoid of PCNA until activated by mitogen in vitro. In synchronized cultures its level and distribution fluctuate through the cell cycle, with a striking accumulation in the nucleolus late in the G1 phase and early in the S phase. Many of these properties are shared by ' cyclin '. This nuclear protein, identified by its position in a two-dimensional separation of cell proteins, is also transformation-sensitive and is preferentially synthesized in the S phase. We establish here that PCNA and cyclin are identical, and show that PCNA is an acidic nuclear protein of apparent molecular weight 35,000.