Tumor-infiltrating lymphocytes and POLE mutation in endometrial carcinoma.

BACKGROUND: Polymerase-ε (POLE)-mutated endometrial carcinomas (ECs) have displayed an increased number of tumor-infiltrating lymphocytes (TIL) compared to POLE-wild-type ECs. However, it is unclear if TIL may aid in identifying POLE-mutated ECs when molecular data are unavailable. The identification of a POLE mutation surrogate may be crucial to translate TCGA/ProMisE risk assessment in the clinical practice. AIM: To assess TIL as histological surrogate of POLE mutation in EC. MATERIALS AND METHODS: Seven electronic databases were searched from their inception to September 2020 for studies that allowed data extraction about TIL and TCGA/ProMisE groups of EC. We calculated pooled sensitivity, specificity, positive and negative likelihood ratios (LR+ and LR-), diagnostic odds ratio (DOR) and area under the curve (AUC) on SROC curves of TIL in distinguishing POLE-mutated from i) POLE-wild-type, ii) no specific molecular profile (NSMP), iii) POLE-wild-type/MMR-proficient, iii) MMR-deficient ECs. RESULTS: 10 studies assessing 1169 women were included in the qualitative analysis. TIL-high pattern showed: sensitivity = 0.65, specificity = 0.63, LR + =2.06, LR- = 0.48, DOR = 4.39, AUC = 0.7532 for POLE-mutant vs POLE-wild-type ECs; sensitivity = 0.85, specificity = 0.73, LR + =2.80, LR- = 0.22, DOR = 15.17 for POLE-mutant vs NSMP ECs; sensitivity = 0.85, specificity = 0.66, LR + =2.49, LR- = 0.25, DOR = 10.30 for POLE-mutant vs POLE-wild-type/MMR-proficient ECs; sensitivity = 0.68, specificity = 0.44, LR + =1.38, LR- = 0.64, DOR = 2.68, AUC = 0.6694 for POLE-mutant vs MMR-deficient ECs. CONCLUSION: TIL-high pattern shows a moderate accuracy in distinguishing POLE-mutated from POLE-wild-type ECs after the exclusion of MMR-deficient cases. TIL might be considered in an integrate algorithm to identify POLE-mutated ECs when sequencing is unavailable. Further studies are necessary in this regard.

Coupling transcriptional activation of CRISPR-Cas system and DNA repair genes by Csa3a in Sulfolobus islandicus.

CRISPR-Cas system provides the adaptive immunity against invading genetic elements in prokaryotes. Recently, we demonstrated that Csa3a regulator mediates spacer acquisition in Sulfolobus islandicus by activating the expression of Type I-A adaptation cas genes. However, links between the activation of spacer adaptation and CRISPR transcription/processing, and the requirement for DNA repair genes during spacer acquisition remained poorly understood. Here, we demonstrated that de novo spacer acquisition required Csa1, Cas1, Cas2 and Cas4 proteins of the Sulfolobus Type I-A system. Disruption of genes implicated in crRNA maturation or DNA interference led to a significant accumulation of acquired spacers, mainly derived from host genomic DNA. Transcriptome and proteome analyses showed that Csa3a activated expression of adaptation cas genes, CRISPR RNAs, and DNA repair genes, including herA helicase, nurA nuclease and DNA polymerase II genes. Importantly, Csa3a specifically bound the promoters of the above DNA repair genes, suggesting that they were directly activated by Csa3a for adaptation. The Csa3a regulator also specifically bound to the leader sequence to activate CRISPR transcription in vivo. Our data indicated that the Csa3a regulator couples transcriptional activation of the CRISPR-Cas system and DNA repair genes for spacer adaptation and efficient interference of invading genetic elements.

Polymerase ε (POLE) ultra-mutated tumors induce robust tumor-specific CD4+ T cell responses in endometrial cancer patients.

OBJECTIVE: Around 7-10% of endometrial carcinomas are characterized by polymerase-ε-(POLE) exonuclease-domain-mutations, an ultra-mutated-phenotype and a favorable prognosis. It is currently unknown whether POLE ultra-mutated-tumors are more immunogenic when compared to the other groups of endometrial cancers. METHODS: We used autologous-dendritic-cells (DC) pulsed with whole-tumor-extracts to assess the level of CD8+ and CD4+ T-cell-activation induced by POLE-ultramutated (+) and POLE wild-type (-) endometrial cancer cells in vitro. T-lymphocyte-proliferations were evaluated using CFSE and/or ([3H])thymidine-incorporation-assays while the ability to specifically kill autologous-tumor-cells by cytotoxic-T-lymphocyte (CTL) was tested in standard 4-h-(51)Cr-cytotoxicity-assays. In order to correlate cytotoxic activity and proliferation by CD4+ and CD8+ T-lymphocytes, respectively, with a particular lymphoid subset, two-color-flow-cytometric analysis of intracellular-cytokine-expression (IFN-γ vs IL-4) at the single cell level was also performed. RESULTS: DC-pulsed with tumor extracts were able to induce CTL-responses against autologous-tumor-cells in both POLE (+) and POLE (-) cancer patients (P=0.305). These CD8+ T-cell-populations were cytotoxic against tumor-cells but they did not lyse PHA-stimulated-autologous-lymphocytes or autologous-EBV-transformed-lymphoblastoid-control-cell-lines. In contrast, only POLE (+) tumor-lysate-pulsed-DC were able to induce significant proliferation and high IFN-γ expression (i.e., Th1-cytokine-bias) in autologous in vitro DC-stimulated CD4+ T-cells as well as naïve CD4+ and CD8+ T-cells from patients-peripheral-blood (P<0.05). CONCLUSIONS: POLE ultra-mutated-tumors are significantly more immunogenic when compared to POLE (-) tumors, in particular to the helper arm of the immune system. These data lend support to the hypothesis that the better prognosis of patients with POLE (+) tumors may at least in part be linked to their enhanced immunogenicity.

POLE Proofreading Mutations Elicit an Antitumor Immune Response in Endometrial Cancer.

PURPOSE: Recent studies have shown that 7% to 12% of endometrial cancers are ultramutated due to somatic mutation in the proofreading exonuclease domain of the DNA replicase POLE. Interestingly, these tumors have an excellent prognosis. In view of the emerging data linking mutation burden, immune response, and clinical outcome in cancer, we investigated whether POLE-mutant endometrial cancers showed evidence of increased immunogenicity. EXPERIMENTAL DESIGN: We examined immune infiltration and activation according to tumor POLE proofreading mutation in a molecularly defined endometrial cancer cohort including 47 POLE-mutant tumors. We sought to confirm our results by analysis of RNAseq data from the TCGA endometrial cancer series and used the same series to examine whether differences in immune infiltration could be explained by an enrichment of immunogenic neoepitopes in POLE-mutant endometrial cancers. RESULTS: Compared with other endometrial cancers, POLE mutants displayed an enhanced cytotoxic T-cell response, evidenced by increased numbers of CD8(+) tumor-infiltrating lymphocytes and CD8A expression, enrichment for a tumor-infiltrating T-cell gene signature, and strong upregulation of the T-cell cytotoxic differentiation and effector markers T-bet, Eomes, IFNG, PRF, and granzyme B. This was accompanied by upregulation of T-cell exhaustion markers, consistent with chronic antigen exposure. In silico analysis confirmed that POLE-mutant cancers are predicted to display more antigenic neoepitopes than other endometrial cancers, providing a potential explanation for our findings. CONCLUSIONS: Ultramutated POLE proofreading-mutant endometrial cancers are characterized by a robust intratumoral T-cell response, which correlates with, and may be caused by an enrichment of antigenic neopeptides. Our study provides a plausible mechanism for the excellent prognosis of these cancers.

DNA polymerase epsilon is required for coordinated and efficient chromosomal DNA replication in Xenopus egg extracts.

DNA polymerase epsilon (Pol epsilon) is thought to be involved in DNA replication, repair, and cell-cycle checkpoint control in eukaryotic cells. Although the requirement of other replicative DNA polymerases, DNA polymerases alpha and delta (Pol alpha and delta), for chromosomal DNA replication has been well documented by genetic and biochemical studies, the precise role, if any, of Pol epsilon in chromosomal DNA replication is still obscure. Here we show, with the use of a cell-free replication system with Xenopus egg extracts, that Xenopus Pol epsilon is indeed required for chromosomal DNA replication. In Pol epsilon-depleted extracts, the elongation step of chromosomal DNA replication is markedly impaired, resulting in significant reduction of the overall DNA synthesis as well as accumulation of small replication intermediates. Moreover, despite the decreased DNA synthesis, excess amounts of Pol alpha are loaded onto the chromatin template in Pol epsilon-depleted extracts, indicative of the failure of proper assembly of DNA synthesis machinery at the fork. These findings strongly suggest that Pol epsilon, along with Pol alpha and Pol delta, is necessary for coordinated chromosomal DNA replication in eukaryotic cells.

A neutralizing antibody against human DNA polymerase epsilon inhibits cellular but not SV40 DNA replication.

The contribution of human DNA polymerase epsilon to nuclear DNA replication was studied. Antibody K18 that specifically inhibits DNA polymerase activity of human DNA polymerase epsilon in vitro significantly inhibits DNA synthesis both when microinjected into nuclei of exponentially growing human fibroblasts and in isolated HeLa cell nuclei. The capability of this neutralizing antibody to inhibit DNA synthesis in cells is comparable to that of monoclonal antibody SJK-132-20 against DNA polymerase alpha. Contrary to the antibody against DNA polymerase alpha, antibody K18 against DNA polymerase epsilon did not inhibit SV40 DNA replication in vitro. These results indicate that DNA polymerase epsilon plays a role in replicative DNA synthesis in proliferating human cells like DNA polymerase alpha, and that this role for DNA polymerase epsilon cannot be modeled by SV40 DNA replication.

Detection of antibodies against DNA polymerase of hepatitis B virus in HBsAg-positive sera using ELISA.

OBJECTIVES: DNA polymerase (pol) of Hepatitis B virus (HBV) includes 3 different domains such as terminal protein (TP), reverse transcriptase (RT) and RNase H. Humoral immune responses to each of these proteins have not been well documented previously, although antibody to pol was detected in serum of patients with chronic hepatitis B. We have constructed TP (amino acids 1-182), RT (amino acids 346-685) and RNase H (amino acids 690-832). METHODS: By ELISA using each protein expressed in E. coli as antigens, the corresponding antibodies were tested in serum from 40 patients with type B viral chronic liver diseases. (20 HBeAg-positive and 20 HBeAg-negative). As negative controls, sera from 3 healthy young men were used. With the mean values of the OD, which were tested 4 times per each test sample and 3 times per each control sample, we considered to be positive if the mean OD of each test sample is 2-fold or higher than that of controls. RESULTS: Five of 40 sera (12.5%) contained one or two different antibodies detectable by this method: 4 of 20 HbeAg-positive sera (20%) and 1 of 20 HbeAg-negative sera (5%). Anti-TP, anti-RT and anti-RNase H antibodies were detected in 2.5% (1/40), 10% (4/40) and 7.5% (3/40), respectively. Among 4/20 HbeAg-positive ELISA-positive sera, anti-TP, anti-RT and anti-RNase H were positive in 5% (1/20), 20% (4/20) and 10% (2/20), respectively, while 1 HBeAg-negative ELISA-positive sera were positive only for anti-RNase H. CONCLUSIONS: These results suggest that the corresponding antibody responses to individual recombinant peptides derived from 3 domains of DNA polymerase may tend to be detected more frequently in HBeAg-positive sera than in HBeAg-negative sera from various patients with type B viral chronic liver diseases.

Detection of antibodies against DNA polymerase of hepatitis B virus in HBsAg-positive sera using ELISA

OBJECTIVES: DNA polymerase (pol) of Hepatitis B virus (HBV) includes 3 different domains such as terminal protein (TP), reverse transcriptase (RT) and RNase H. Humoral immune responses to each of these proteins have not been well documented previously, although antibody to pol was detected in serum of patients with chronic hepatitis B. We have constructed TP (amino acids 1-182), RT (amino acids 346-685) and RNase H (amino acids 690-832). METHODS: By ELISA using each protein expressed in E. coli as antigens, the corresponding antibodies were tested in serum from 40 patients with type B viral chronic liver diseases. (20 HBeAg-positive and 20 HBeAg-negative). As negative controls, sera from 3 healthy young men were used. With the mean values of the OD, which were tested 4 times per each test sample and 3 times per each control sample, we considered to be positive if the mean OD of each test sample is 2-fold or higher than that of controls. RESULTS: Five of 40 sera (12.5%) contained one or two different antibodies detectable by this method: 4 of 20 HbeAg-positive sera (20%) and 1 of 20 HbeAg-negative sera (5%). Anti-TP, anti-RT and anti-RNase H antibodies were detected in 2.5% (1/40), 10% (4/40) and 7.5% (3/40), respectively. Among 4/20 HbeAg-positive ELISA-positive sera, anti-TP, anti-RT and anti-RNase H were positive in 5% (1/20), 20% (4/20) and 10% (2/20), respectively, while 1 HBeAg-negative ELISA-positive sera were positive only for anti-RNase H. CONCLUSIONS: These results suggest that the corresponding antibody responses to individual recombinant peptides derived from 3 domains of DNA polymerase may tend to be detected more frequently in HBeAg-positive sera than in HBeAg-negative sera from various patients with type B viral chronic liver diseases.

On the presence of DNA polymerase alpha in human lymphocyte nuclei and chromosomes.

Experiments were carried out to correlate the cytological localization of DNA polymerase alpha with the presence of its specific mRNA in human lymphocytes studied at different times after phytohaemagglutinin stimulation. Our data indicated that in resting cells it is not possible to detect DNA polymerase alpha protein or mRNA by Northern hybridization. By contrast, in stimulated cells the detection of mRNA specific for DNA polymerase alpha synthesis is possible after 16 h phytohaemagglutin stimulation, whereas immunolocalization is possible after only 4 h stimulation. Observation of cytological preparations from cells stimulated for times long enough to obtain mitoses surprisingly showed an intense immunoreaction in mitotic chromosomes treated with monoclonal antibodies to DNA polymerase alpha.

Expression patterns of DNA replication enzymes and the regulatory factor DREF during Drosophila development analyzed with specific antibodies.

Specific antibodies were prepared against Drosophila DNA polymerase epsilon and DREF, a regulatory factor for DNA replication-related genes. Using these antibodies together with those for DNA polymerase alpha and proliferating cell nuclear antigen (PCNA), we examined expression patterns and sub-cellular distributions of these proteins during Drosophila development. DNA polymerase alpha, epsilon and PCNA proteins were maternally stored in unfertilized eggs and maintained at high levels during embryogenesis. With distinct nuclear localization, proteins were observed in embryos at interphase stages throughout the 13 nuclear division cycles, suggesting that they all participate in rapid nuclear DNA replication during these cycles. In contrast, maternal storage of a DREF protein was relatively low and its level increased throughout embryogenesis. Strong nuclear staining with the anti-DREF antibody was not observed until the nuclear division cycle 8. Immunostaining of various larval tissues from transgenic flies carrying the PCNA gene promoter-lacZ fusion gene revealed co-expression of DREF, PCNA and lacZ, suggesting that DREF regulates the expression of PCNA gene in these tissues. In addition, we detected a relatively high level of DREF in adult males as well as females. Since DNA polymerase alpha, epsilon and PCNA are hardly detectable in adult males, DREF very likely regulates genes other than those closely linked to DNA replication in adult males.

The significance of nucleolar organizer region (AgNOR) score in predicting meningioma recurrence.

BACKGROUND: Argyrophilic nucleolar organizer region (AgNOR) has been demonstrated in recent studies of human brain tumors, including meningiomas. The authors used this technique in meningiomas to analyze whether the mean numbers of AgNOR per nucleus (AgNOR score) are related to the recurrence rate or the proliferative potential of meningiomas. METHODS: AgNOR staining technique was applied to paraffin-embedded sections of 60 meningiomas. Twenty of these specimens also were investigated immunohistochemically with monoclonal antibody (MoAb) against DNA polymerase alpha (Pol.alpha) and with MoAb Ki-67 to compare the AgNOR score with the proliferative potential. RESULTS: There was a statistically significant difference between the AgNOR score in nonrecurrent meningiomas (2.48 +/- 0.73) and recurrent histologically benign meningiomas after gross total resection (3.20 +/- 0.96) (P < 0.02). The recurrence rate of tumors after gross total resection with an AgNOR score of 3.0 or more was significantly higher than that with an AgNOR score of less than 3.0. The AgNOR score did not always correlate with Pol.alpha or Ki-67 score; the AgNOR score of malignant meningioma that had high proliferative score was not always high. CONCLUSIONS: This study indicates that AgNOR staining appears to be a simple and useful method for estimating the probability of histologically benign meningioma recurrence even after gross total resection.

Cell cycle expression of two replicative DNA polymerases alpha and delta from Schizosaccharomyces pombe.

We have investigated the expression of two Schizosaccharomyces pombe replicative DNA polymerases alpha and delta during the cell cycle. The pol alpha+ and pol delta+ genes encoding DNA polymerases alpha and delta were isolated from S. pombe. Both pol alpha+ and pol delta+ genes are single copy genes in haploid cells and are essential for cell viability. In contrast to Saccharomyces cerevisiae homologs, the steady-state transcripts of both S. pombe pol alpha+ and pol delta+ genes were present throughout the cell cycle. Sequence analysis of the pol alpha+ and pol delta+ genes did not reveal the Mlu I motifs in their upstream sequences that are involved in cell cycle-dependent transcription of S. cerevisiae DNA synthesis genes as well as the S. pombe cdc22+ gene at the G1/S boundary. However, five near-match Mlu I motifs were found in the upstream region of the pol alpha+ gene. S. pombe DNA polymerases alpha and delta proteins were also expressed constantly throughout the cell cycle. In addition, the enzymatic activity of the S. pombe DNA polymerase alpha measured by in vitro assay was detected at all stages of the cell cycle. Thus, these S. pombe replicative DNA polymerases, like that of S. pombe cdc17+ gene, are expressed throughout the cell cycle at the transcriptional and protein level. These results indicate that S. pombe has at least two regulatory modes for the expression of genes involved in DNA replication and DNA precursor synthesis.

Analysis of proliferating biliary epithelial cells in human liver disease using a monoclonal antibody against DNA polymerase alpha.

The proliferative activity and ultrastructural characteristics of proliferating biliary epithelial cells were analysed immunohistocytochemically in 39 biopsied liver specimens from patients with acute viral hepatitis, chronic hepatitis and liver cirrhosis using a monoclonal antibody against DNA polymerase alpha (DNA-PA). In acute viral hepatitis with perivenular confluent necrosis, proliferation of typical bile ducts was found frequently in portal areas. In chronic aggressive hepatitis and cirrhosis, ductular proliferation of both typical and atypical forms was found in enlarged portal and periportal areas and in confluent necrotic areas. The number of proliferating biliary epithelial cells that stained positive for DNA-PA was small. There were very few positively stained cells in atypical bile ducts in confluent necrotic areas of cirrhosis. Atypical bile ducts seen in chronic aggressive hepatitis, cirrhosis and acute hepatitis with confluent necrosis were positively stained for both cytokeratins 8 and 19. In cirrhosis, the number of stained biliary epithelial cells in typical bile ducts was larger than the number of such cells in atypical bile ducts (P < 0.01). By electron microscopy, the cells positively stained for DNA-PA were mostly so-called clear cells with irregular nuclei containing coarse nucleoplasm, and a few small cells with scanty cytoplasm and few organelles.

Expression of p53 protein in colorectal cancer and its relationship to short-term prognosis.

BACKGROUND AND METHODS: The expression of p53 protein in 100 large bowel cancers was studied immunohistochemically by use of a monoclonal antibody (PAb1801). RESULTS: Immunoreactivity was found in 61.0% of specimens from 100 patients with colorectal cancer. The pattern of p53 expression was mainly detected in the nuclei of the cancer cells. There was no significant correlation between the expression of p53 and the histologic grade, tumor size, serosal invasion, lymphatic invasion, venous invasion, lymph node metastasis, or liver metastasis. However, patients with p53-positive tumors had a greater relative risk of death compared with those with p53-negative tumors. The p53 negative-tumors showed a recurrence rate of 5.9%; for the p53 positive-tumors, a recurrence rate of 23.8% was recorded. The 3-year survival rate was 96.7% of 39 patients with p53-negative carcinomas and 61.8% for the patients with p53-positive tumors; there was a significant difference in the rate between the two groups of patients (P < 0.05). The growth fraction of p53-positive tumors determined with a monoclonal antibody against DNA polymerase alpha (49.0%) was significantly higher than that of p53-negative tumors (40.7%, P < 0.01). CONCLUSIONS: These results suggest that the immunoreactivity of p53 may be a biologic marker of prognostic significance.

Embedding and fixation techniques for immunohistochemical staining with anti-DNA polymerase alpha and Ki-67 monoclonal antibodies to analyze the proliferative potential of tumors.

Anti-DNA polymerase alpha and Ki-67 are monoclonal antibodies that recognize nuclear antigens expressed in proliferating cells. In this study, we evaluated various methods of embedding and fixing brain tumor specimens to optimize staining with these antibodies. In fresh frozen sections, postfixation with 4% paraformaldehyde, 100% methanol, 95% ethanol and 10% buffered formalin were tested; also tested were prefixation with 4% paraformaldehyde followed by freezing and fixation with 100% methanol, 95% ethanol, or 10% buffered formalin followed by embedding in paraffin. For both antibodies, postfixation of fresh frozen sections with 4% paraformaldehyde at 4 C gave the most intense staining and lowest background activity while preserving histological features. This technique can be used in routine clinical practice to predict the growth potential of tumors.

The replication of DNA containing the simian virus 40 origin by the monopolymerase and dipolymerase systems.

The influence of DNA polymerase (pol) alpha and DNA primase on SV40 DNA replication was examined in both the monopolymerase and dipolymerase systems. The synthesis of oligoribonucleotides in the monopolymerase and dipolymerase systems, followed by pulse labeling with deoxynucleoside triphosphates, yielded short Okazaki fragments approximately 35 nucleotides in length that were chased into full-length Okazaki fragments with time. In the presence of activator 1 and proliferating cell nuclear antigen (PCNA), but no pol delta, these short fragments hardly increased in size with time. DNA fragments of similar size (approximately 35 nucleotides) were previously observed in SV40 replication reactions carried out with crude extracts of HeLa cells in the presence of antibodies directed against PCNA (Bullock, P. A., Seo, Y.S., and Hurwitz, J. (1991) Mol. Cell. Biol. 11, 2350-2361). Thus, the pol alpha-primase complex appears to act processively for only a short distance. At high levels of pol alpha and primase, both short and long DNA products were formed in both systems. In the presence of limiting amounts of pol alpha and excess primase, the monopolymerase system inefficiently yielded longer length Okazaki fragments than those formed with excess pol alpha and primase, whereas the dipolymerase system yielded both short and long DNA fragments. In the presence of limiting amounts of primase and excess pol alpha, long products were formed in both systems, and virtually no short products accumulated. Thus, the ratio between the polymerase and primer ends available controls the size of the nascent product DNA strands. We examined whether PCNA, the T4 phage-encoded gene product 45 (T4 gp45), and the Escherichia coli beta subunit of DNA polymerase III (dnaN gene product) supported SV40 DNA replication and the elongation of single-stranded DNA-binding protein-coated singly primed DNA in reactions catalyzed by pol delta, T4 DNA pol, and E. coli DNA pol III*, respectively. In the presence of T4 gp44/62 and T4 gp32 (but not human single-stranded DNA-binding protein isolated from HeLa cells), T4 DNA pol was weakly activated by PCNA and the beta subunit in lieu of T4 gp45 in the elongation of singly primed phi X174 DNA. However, the other systems were specific for their analogous auxiliary factors. This specificity indicates the importance of protein-protein interactions.

Structural and functional relationships of human DNA polymerases.

A continuing theme of our laboratory has been the understanding of human DNA polymerases at the structural level. We have purified DNA polymerases delta, epsilon and alpha from human placenta. Monoclonal antibodies to these polymerases were isolated and used as tools to study their immunochemical relationships. These studies have shown that while DNA polymerases delta, epsilon and alpha are discrete proteins, they must share common structural features by virtue of the ability of several of our monoclonal antibodies to exhibit cross-reactivity. A second approach we have taken is the molecular cloning of human DNA polymerase delta and epsilon. We have cloned the DNA polymerase delta cDNA, and this has allowed us to compare its primary structure to those of human polymerase alpha and other members of this polymerase family. Multiple sequence alignments have revealed that human DNA polymerase delta is also closely related to the herpes virus family of DNA polymerases. In situ hybridization has shown that the human DNA polymerase delta gene is localized to chromosome 19 q13.3-q13.4. In order to further determine the functional regions of the DNA polymerase delta structure we are currently expressing human pol delta in E. coli and baculovirus systems. Other work in our laboratory is directed toward examining the expression of DNA polymerase delta during the cell cycle.

Cell proliferation kinetics of human gastric carcinoma: an immunohistochemical study with a monoclonal antibody against DNA polymerase-alpha.

Cell proliferation kinetics of human gastric carcinoma were studied immunohistochemically using a monoclonal antibody against DNA polymerase-alpha (Pol-alpha). The distribution patterns and percentages of proliferative cells were examined in cases with various histological types of gastric carcinoma and compared with those of normal epithelium of the gastric foveolae. Pol-alpha-positive epithelial cells were localised at the isthmus of the normal foveola, while Pol-alpha-positive cancer cells were distributed irregularly in the cancer nests. The percentage of Pol-alpha-positive cells (%PPC) was significantly higher in the carcinoma [mean (S.D.) 41.6 (12.9)%] than in the normal foveola [24.8 (6.4)%] (P < 0.01). Also, the intestinal-type carcinoma showed a relatively higher %PPC [44.9 (12.0)%] than the diffuse type [36.2 (15.1)%] (P<0.05), and the %PPC of signet ring cell carcinoma was extremely low [7.3 (2.2)%] (P< 0.01). Pol-alpha-positive cancer cells were observed most abundantly in the lamina propria of the mucosa. They decreased in number with the depth of cancer infiltration down to the subserosa.

Histochemical study of pituitary adenomas with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine labeling, and nucleolar organizer region counts.

The growth potential of 65 pituitary adenomas was determined by histochemical analysis with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine (BrdUdR) labeling, and counts of argyrophilic nucleolar organizer regions (Ag-NORs). The mean proliferating cell indices (PCIs) determined by Ki-67 and anti-DNA polymerase alpha and the BrdUdR labeling index (LI) were generally very low [1.0 +/- 0.2%, 1.1 +/- 0.2%, and 0.5 +/- 0.1% (+/- SE), respectively]. Apart from adrenocorticotropic hormone-positive adenomas, which had significantly higher indices, there were no statistically significant differences in the indices among the other subtypes of pituitary adenomas. Recurrent tumors had higher Ki-67 and DNA polymerase alpha PCIs and BrdUdR LIs (3.6%, 4.2%, 1.4%) than primary tumors (0.8%, 0.8%, 0.3%; P less than 0.005). The number of Ag-NORs did not correlate significantly with any of the three indices. The mean number of Ag-NORs was higher in nonfunctioning adenomas than in functioning adenomas (2.04 vs 1.66, P less than 0.005); among prolactin-positive adenomas, those treated preoperatively with bromocriptine had more Ag-NORs than untreated tumors (1.75 vs 1.57, P less than 0.005). These results suggest that the Ki-67 and DNA polymerase alpha PCIs and the BrdUdR LI predict the growth potential of individual pituitary adenomas, whereas the number of Ag-NORs appears to correlate with hormone production rather than with the proliferative potential.

Developmental expression of the embryonic chicken brain DNA polymerase alpha and its binding with monoclonal antibodies against human KB cell DNA polymerase alpha.

Changes in DNA polymerase alpha activity accompanying tissue development have been well established in several systems. In most cases, DNA polymerase alpha activity decreases with development. Here, we report observed changes in DNA polymerase alpha activity throughout embryonic chicken brain (ECB) development. The level of DNA polymerase alpha activity was found to gradually decrease by 60% (2.3 to 0.8 nmol of [3H]dCMP incorporated/mg protein/h) between 9- and 19-day-old ECB. An enzyme-linked immunosorbent assay of DNA polymerase alpha utilizing monoclonal antibody SJK 237-71 (human KB cell DNA pol-alpha binder) also demonstrated a gradual decrease (up to 60%) of antigen over this same range of development. Analysis of DNA polymerase alpha from 11- and 19-day-old ECB by a 10 to 30% glycerol density gradient revealed a high molecular weight peak sedimenting near catalase (11.3 S) with activity at the 11th day being approximately 3-fold greater than activity at the 19th day. A Western immunoblot analysis utilizing monoclonal antibody SJK 237-71 (against human KB cell DNA polymerase alpha) showed a decrease in DNA polymerase alpha from 186 kilodaltons in 9- and 11-day ECB cell-free extracts to 120 kilodaltons in extracts from 13- to 19-day ECB. The conversion of DNA polymerase alpha from a higher to a lower molecular weight form may be a regulatory mechanism in eukaryotic DNA replication.