Antigen Ki-67 is a nuclear protein expressed in proliferating mammalian cells. It is widely used in cancer histopathology but its functions remain unclear. Here, we show that Ki-67 controls heterochromatin organisation. Altering Ki-67 expression levels did not significantly affect cell proliferation in vivo. Ki-67 mutant mice developed normally and cells lacking Ki-67 proliferated efficiently. Conversely, upregulation of Ki-67 expression in differentiated tissues did not prevent cell cycle arrest. Ki-67 interactors included proteins involved in nucleolar processes and chromatin regulators. Ki-67 depletion disrupted nucleologenesis but did not inhibit pre-rRNA processing. In contrast, it altered gene expression. Ki-67 silencing also had wide-ranging effects on chromatin organisation, disrupting heterochromatin compaction and long-range genomic interactions. Trimethylation of histone H3K9 and H4K20 was relocalised within the nucleus. Finally, overexpression of human or Xenopus Ki-67 induced ectopic heterochromatin formation. Altogether, our results suggest that Ki-67 expression in proliferating cells spatially organises heterochromatin, thereby controlling gene expression.

The biologic behavior of oligodendrogliomas is somewhat unpredictable. A supplementary prognostic factor is, therefore, desirable.

We investigated CD4+ and CD8+ T cell turnover in both healthy and HIV-1-infected adults by measuring the nuclear antigen Ki-67 specific for cell proliferation. The mean growth fraction, corresponding to the expression of Ki-67, was 1.1% for CD4(+) T cells and 1.0% in CD8(+) T cells in healthy adults, and 6.5 and 4.3% in HIV-1-infected individuals, respectively. Analysis of CD45RA+ and CD45RO+ T cell subsets revealed a selective expansion of the CD8+ CD45RO+ subset in HIV-1-positive individuals. On the basis of the growth fraction, we derived the potential doubling time and the daily turnover of CD4+ and CD8+ T cells. In HIV-1-infected individuals, the mean potential doubling time of T cells was five times shorter than that of healthy adults. The mean daily turnover of CD4+ and CD8+ T cells in HIV-1-infected individuals was increased 2- and 6-fold, respectively, with more than 40-fold interindividual variation. In patients with <200 CD4+ counts, CD4+ turnover dropped markedly, whereas CD8+ turnover remained elevated. The large variations in CD4+ T cell turnover might be relevant to individual differences in disease progression.

P63 gene is a member of TP53 and its homologous gene family. Its expression was observed in some odontogenic lesions, more expression in aggressive lesions.

The Ki-67 proliferation index (PI) is a prognostic factor in neuroendocrine tumors (NETs) and defines tumor grade. Analysis of Ki-67 PI requires calculation of Ki-67-positive and Ki-67-negative tumor cells, which is highly subjective. To overcome this, we developed a deep learning-based Ki-67 PI algorithm (KAI) that objectively calculates Ki-67 PI. Our study material consisted of NETs divided into training (n = 39), testing (n = 124), and validation (n = 60) series. All slides were digitized and processed in the Aiforia® Create (Aiforia Technologies, Helsinki, Finland) platform. The ICC between the pathologists and the KAI was 0.89. In 46% of the tumors, the Ki-67 PIs calculated by the pathologists and the KAI were the same. In 12% of the tumors, the Ki-67 PI calculated by the KAI was 1% lower and in 42% of the tumors on average 3% higher. The DL-based Ki-67 PI algorithm yields results similar to human observers. While the algorithm cannot replace the pathologist, it can assist in the laborious Ki-67 PI assessment of NETs. In the future, this approach could be useful in, for example, multi-center clinical trials where objective estimation of Ki-67 PI is crucial.

T cells play a key role in the pathogenesis of chronic inflammatory enteropathy (CIE) in dogs. Cluster of differentiation 3 (CD3) antigen serves as a marker for T cells. In human medicine, Ki-67 is an indicator for cell growth but there are only a few studies in dogs with CIE.

Testin is a protein expressed in normal human tissues, being responsible, with other cytoskeleton proteins, for the proper functioning of cell−cell junction areas and focal adhesion plaques. It takes part in the regulation of actin filament changes during cell spreading and motility. Loss of heterozygosity in the testin-encoding gene results in altered protein expression in many malignancies, as partly described for cervical cancer. The aim of our study was the assessment of the immunohistochemical (IHC) expression of testin in cervical cancer and its analysis in regard to clinical data as well the expression of the Ki-67 antigen and p16 protein. Moreover, testin expression was assessed by Western blot (WB) in commercially available cell lines. The IHC analysis disclosed that the expression of testin inversely correlated with p16 (r = −0.2104, p < 0.0465) and Ki-67 expression (r = −0.2359, p < 0.0278). Moreover, weaker testin expression was observed in cancer cases vs. control ones (p < 0.0113). The WB analysis of testin expression in the cervical cancer cell lines corresponded to the IHC results and showed a weaker expression compared to that in the control cell line. When we compared the expression of testin in cervical cancer cell lines, we found a weaker expression in HPV-negative cell lines. In summary, we found that the intensity of testin expression and the number of positive cells inversely correlated with the expression of Ki-67 (a marker of proliferation) and p16 (a marker of cell cycle dysregulation). This study shows that the combined assessment of testin, Ki-67 and p16 expression may improve cervical cancer diagnostics.

The odontogenic keratocyst (OKC) is a controversial lesion that was reclassified as a tumor with the name "keratocystic odontogenic tumor" in 2005. The reclassification was revoked recently in 2017, with a conclusion on the need for further studies on the subject. In this study, the expressions of an important regulatory protein (maspin), an important integral membrane proteoglycan (syndecan-1), and a universal proliferation marker (Ki-67) in the epithelium of the OKC were investigated in comparison with the dentigerous cyst (DC) and ameloblastoma (AB). Twenty-six OKCs, eleven DCs, and ten conventional ABs were immunohistochemically stained for maspin, syndecan-1, and Ki-67. ImageJ was used to analyze the positivity of maspin and syndecan-1. The Ki-67 score was calculated as the percentage of positive nuclei in 5 high power fields. Analysis of variance (ANOVA) test and Student t-test were used as appropriate. Lower expressions of maspin were noted in OKC and DC compared to those in AB, and lower expressions of syndecan-1 were noted in OKC and AB compared to those in DC. The differences, however, did not reach statistical significance (ANOVA and t-test: P > 0.05). The Ki-67 score was significantly higher in OKC than in DC (t-test: P < 0.05), and not significantly different from AB (t-test: P > 0.05). In conclusion, expressions of maspin and syndecan-1 are not strongly representative of differences in behavior between OKC, AB, and DC. However, the expression of Ki-67 indicates comparable proliferative activities of OKC and AB, which are higher than that of DC. Further investigation on the biologic behavior of OKC is still recommended to arrive at more specific conclusions regarding its classification.

To identify glioma radiomic features associated with proliferation-related Ki-67 antigen and cellular tumour antigen p53 levels, common immunohistochemical markers for differentiating benign from malignant tumours, and to generate radiomic prediction models.

We examined data from 374 laboratories staining for Ki-67 as part of external quality assessment over 8 runs between 2013 and 2017 (total data sets=2601). One of 5 primary antibodies was used for 94.8% of submissions, with MIB-1 (Agilent Dako) comprising 58.8% of the total. Examining assessment score as a continuous variable showed the 30-9 (Ventana) and K2 (Leica Biosystems) clones were associated with the highest mean scores (17.0; 95% confidence interval, 16.8-17.2 and 16.3; 95% confidence interval, 15.9-16.6, respectively). Stain quality was not significantly different between them. Both were associated with significantly better staining compared with MIB-1 (Agilent Dako), MM1 (Leica Biosystems), and SP6 from various suppliers (P<0.05). Similarly, categorical assessment of "Good" versus "Not good" staining quality showed that the 30-9 and K2 clones were both significantly associated with "Good" staining (both P<0.001). Other methodological parameters were examined for significant primary antibody-specific effects; none were seen for 30-9, K2, or SP6. The MM1 clone was more likely to be associated with good quality staining when it was used with Leica Biosystems sourced antigen retrieval, detection, and platform, all statistically significant at P<0.01. MIB-1 was more likely to be associated with good quality staining results when it was used with Agilent Dako antigen retrieval, detection, and staining platforms (P<0.0001), and less likely at the same significance level when used with Leica Biosystems reagents and equipment. The data presented here show the importance of not just primary antibody choice but also matching that choice to other methodological factors.

Breast carcinoma is the most common malignancy among women and it has a major impact on mortality. Studies of primary chemoprevention with tamoxifen have generated high expectations and considerable success rates. The efficacy of lower doses of tamoxifen is similar to that seen with a standard dose of the drug, and there has been a reduction in healthcare costs and side effects. The immune reaction to monoclonal antibody Ki-67 (MIB-1) and the expression of estrogen receptors (1D5) and progesterone receptors (PgR 636) in breast carcinoma were studied in patients treated with 10 mg of tamoxifen for a period of 14 days. A prospective randomized clinical trial was conducted with 38 patients divided into two groups: Group A: N = 20 (control group--without medication) and Group B: N = 18 (tamoxifen/10 mg/day for 14 days). All patients signed an informed consent term previously approved by both institutions. Patients underwent incisional biopsy before treatment and 14 days later a tumor tissue sample was obtained during surgical treatment. Positivity was quantitatively assessed, counting at least 1.000 cells per slide. For statistical data analysis, a Wilcoxon non-parametric test was used, and alpha was set at 5%. Both groups (A and B) were considered homogeneous regarding control variables. In Group A (control), there was no statistically significant reduction in Ki-67 (MIB-1) (p = 0.627), estrogen receptor (1D5) (p = 0.296) and progesterone receptor positivity (PgR 636) (p = 0.381). In Group B (tamoxifen 10 mg/day), the mean percentage of nuclei stained by Ki-67 (MIB-1) was 24.69% before and 10.43% after tamoxifen treatment. Mean percentage of nuclei stained by estrogen receptor (1D5) was 59.53% before and 25.99% after tamoxifen treatment. Mean percentage of nuclei stained by progesterone receptor (PgR 636), was 59.34 before and 29.59% after tamoxifen treatment. A statistically significant reduction was found with the three markers (p < 0.001). Tamoxifen significantly reduced monoclonal antibody Ki-67 (MIB-1), estrogen receptor (1D5) and progesterone receptor positivity (PgR 636) in the breast epithelium of carcinoma patients treated with a 10 mg dose of tamoxifen for 14 days.

The current nested case-control study was conducted to explore the prognostic value of cyclin-dependent kinase inhibitor 2A (p16INK4a), marker of proliferation Ki-67 (Ki-67) and immunohistochemical cocktail containing antibodies directed against topoisomerase IIα (TOP2A) and minichromosome maintenance 2 (MCM2) proteins (ProExC) immuno-qualitative features to predict low-grade squamous intraepithelial lesion (LSIL) progression. A total of 92 LSIL patients were followed-up for 2 years, where those with high-grade squamous intraepithelial lesion (HSIL) or persistent LSIL were designated as the case group and those who spontaneously regressed were designated as the control group. The infection status of human papillomavirus (HPV) was evaluated using flow-through hybridization and gene chip, whilst the expression of p16INK4a, Ki-67 and ProExC were tested in LSIL patient biopsies by immunohistochemistry. All data were collected at the beginning of the follow-up and patient outcomes were diagnosed by histopathological examination. To analyze the risk factors for LSIL progression, sensitivity, specificity, positive-negative predictive value (PPV-NPV), positive-negative likelihood ratio (PLR-NLR), Youden's index (YI) and multinomial logistic regression analysis was performed. The expression rates of p16INK4a, Ki-67, and ProExC were found to be higher in the progression group compared with those in the persistence and regression groups. Only p16INK4a expression significantly associated with high-risk HPV infection. With respect to predicting HSIL, p16INK4a staining was the most sensitive but Ki-67 staining was found to be the most specific. YI was the highest (42.1%) for p16INK4a expression in the present study, followed by ProExC (39.5%) and Ki-67 (28.3%). However, the expression of ProExC was found to be an independent risk factor for LSIL progression into HSIL. In conclusion, whilst immunohistochemical staining for p16INK4a, Ki-67, and ProExC can be used to predict HSIL progression, only ProExC expression can be applied an independent risk factor for LSIL progression.

Squamous cell carcinoma (SCC) is the most frequent oral cancer whose 5-year survival rate is 80% for early-detected lesions and nearly 30-50% for advanced lesions. Early detection of oral cancers and precancerous lesions can improve the patient's survival and decrease the morbidity.

We analyzed the immunohistochemical expression of Ki-67, pRb, Bax, and MMP-9 during the human secondary palate formation (7th to 12th developmental weeks (DWs). The most significant proliferation was observed in the seventh DW with 32% of Ki-67-positive cells in the epithelium, while loose ectomesenchyme condensations (lec) and loose non-condensing ectomesenchyme (lnc) had only 18 and 11%, respectively (Kruskal-Wallis, p < 0.001), and diminished afterwards. Contrarily, pRb-positive cells were mostly located in the lnc (67%), with significant difference in comparison to epithelium and lec in all investigated periods (Kruskal-Wallis, p < 0.001). Ki-67- and pRb-positive cells co-expressed occasionally in all investigated periods. MMP-9 displayed a strong expression pattern with the highest number of positive cells during the seventh DW in the epithelium, with significant difference in comparison to lec and lnc (Kruskal-Wallis, p < 0.0001). The ninth DW is particularly important for the Bax expression, especially in the epithelium (84%), in comparison to lec (58%) and lnc (47%) (Kruskal-Wallis, p < 0.001). The co-expression of Bax and MMP-9 was seen only in the epithelium during seventh and ninth DWs. Our study indicates the parallel persistence of proliferation (Ki-67, pRb) and remodeling (MMP-9) that enables growth and apoptotic activity (Bax) that enable the removal of the epithelial cells at the fusion point during secondary palate formation.

The significance of human epidermal growth factor receptor 2 (Her2) and nucleus-associated antigen Ki-67 expression remains controversial in gastric adenocarcinoma (GaC). The aim of this study was to investigate the expression and clinicopathologic and prognostic significance of Her2 and Ki-67 in resected GaC without distant metastasis.

The Ki-67 antigen was identified in the early steps of polymerase I-dependent ribosomal RNA synthesis. Although it seems that this protein has an important function in cell division, its exact role is still unclear and there is little published work on its overall function. The aim of the present study was to evaluate the contribution of the level of Ki-67 with respect to tumor recurrence in molecularly classified groups of breast cancer patients. Ki-67 was divided into the percentage levels up to and including 20% and over 20%. Immunohistochemistry and fluorescence in-situ hybridization are described for the results of estrogen receptor, progesterone receptor, c-erb-B2, and Ki-67 biomarkers. Formaldehyde-fixed breast samples were paraffin wax embedded and processed for paraffin sections. The protocol of the present study started in 1995 and finished in 2010. Nine hundred and sixteen patients with breast cancer were examined: 291 were grouped as luminal A, 228 as luminal B, 221 as the Her-2 subtype, and 107 as basal cell (triple negative). Follow-up ranged from 3 to 15 years following diagnosis. It was found that in luminal A patients, only one had a Ki-67 level higher than 20%. In luminal B, the Ki-67 was higher than 20% in 51.16% of the patients and recurrence occurred in 23.68%. In the Her-2 subtype, the Ki-67 level was more than 20% in 48.63%. In basal cell triple-negative patients, Ki-67 was more than 20% in 63.86%. The data presented here indicate that the level of Ki-67 may be considered one of the valuable biomarkers in breast cancer patients with respect to process and recurrence.

Chromatin assembly factor 1 (CAF-1) deposits histones during DNA synthesis. The p150 subunit of human CAF-1 contains an N-terminal domain (p150N) that is dispensable for histone deposition but promotes the localization of specific loci (nucleolar-associated domains [NADs]) and proteins to the nucleolus during interphase. One of the p150N-regulated proteins is proliferation antigen Ki-67, whose depletion also decreases the nucleolar association of NADs. Ki-67 is also a fundamental component of the perichromosomal layer (PCL), a sheath of proteins surrounding condensed chromosomes during mitosis. We show here that a subset of p150 localizes to the PCL during mitosis and that p150N is required for normal levels of Ki-67 accumulation on the PCL. This activity requires the sumoylation-interacting motif within p150N, which is also required for the nucleolar localization of NADs and Ki-67 during interphase. In this manner, p150N coordinates both interphase and mitotic nuclear structures via Ki67.

Cutaneous Squamous Cell Carcinoma (cSCC) is a malignant keratinocyte tumour that develops through the suprabasal epidermis. This malignant tumour is the second most common skin malignancy after Basal Cell Carcinoma (BCC). The increased incidence of cSCC is directly proportional to increasing age. Generally, the predisposing factor of cSCC is exposure to recurrent sunlight for a long time, so localisation of cSCC is a part of the body that often exposed to direct sunlight, such as the forehead, face, ears, scalp, neck, and back of the hand. The carcinogenesis process of cSCC is a cumulation of a series of events, one of which plays an important role is the proliferation index assessed by Ki-67. Forty-eight tissue paraffin blocks were diagnosed histopathologically as cutaneous squamous cell carcinoma from the Anatomical Pathology Laboratory of the Faculty of Medicine, Universitas Sumatera Utara and the Anatomical Pathology Unit of Haji Adam Malik General Hospital Medan, as the research sample. The results of protein expression from Ki-67 were assessed based on area. There was no significant correlation between cSCC grading and Ki-67 expression (p > 0.05). Ki-67 antigen tumour marker, widely used to determine the level of tumour cell proliferation.

We assessed the effect of sulindac sulfide (SS), a colon cancer chemopreventive agent, on the proliferation and apoptosis in the colon cancer cell lines HCT-15 and HT-29. We applied a triparameter flow cytometric analysis that simultaneously determined DNA content, expression of Ki-67 or proliferating cell nuclear antigen (PCNA), and extent of DNA strand breaks by TUNEL (TdT-mediated dUTP nick end labeling). HCT-15 and HT-29 cells were exposed to SS 200 microM and 175 microM, respectively, for up to 72 h. As expected, SS inhibited proliferation and induced apoptosis. SS also induced several subpopulations of cells defined by their expression of proliferation markers and DNA strand breaks. By 72 h the rapidly proliferating cells [PCNA/Ki-67(+)/TUNEL(-)] were reduced from > 90% to about one third. Of the remaining cells, about one third were apoptotic [PCNA/Ki-67(-)/TUNEL(+)] and one third were quiescent [PCNA/Ki-67(-)/TUNEL(-)]. Another subpopulation was detected that was PCNA/Ki-67(+)/TUNEL(+), some had a dominant subdiploid peak and over half were in S or G2/M phases by DNA content. Thus, a subpopulation of apoptotic cells strongly expressed PCNA and Ki-67, suggesting that their specificity as proliferation markers may need reassessment. Similar results were obtained with the HL-60 promyelocytic cell line.

In the era of "precision medicine," the availability of high-quality tumor biomarker tests is critical and tumor proliferation evaluated by Ki-67 antibody is one of the most important prognostic factors in breast cancer. But the evaluation of Ki-67 index has been shown to suffer from some interobserver variability. The goal of the study is to develop an easy, automated, and reliable Ki-67 assessment approach for invasive breast carcinoma in routine practice.