Simultaneous staining of exponentially growing versus plateau phase cells with the proliferation-associated antibody Ki-67 and propidium iodide: analysis by flow cytometry

Abstract. The antibody Ki-67, which detects proliferating cells, was used in combination with propidium iodide, a DNA-specific dye. The double-staining method allowed discrimination of cells in the phases of the cell cycle as well as the recognition of Ki-67 staining characteristics. Suspension cultures of U937 cells were measured in exponential growth and plateau phase in nutritional deprivation. The fraction of Ki-67 positive cells was nearly 100% 2 days after dilution and 46% 7 days after dilution of the cultures. Stathmokinetic measurements with colchicine and flow cytometry measurements with the BrdU-Hoechst technique yielded close to 100% proliferation at day 2 but only 18% and 6%, respectively, at day 7. The discrepancy between Ki-67 results and the results of the two other methods is considered to be a characteristic of nutritionally deprived cells.     

Follicular cells versus oocytes: cell population dynamics in the developing ovary

The aim of the current paper is to evaluate the correlation of germ and follicular cells kinetics during ovarian morphogenesis. Thus, immunohistochemical detection of PCNA and Ki-67 proteins has been examined using PC10 (Dako) and NCL-Ki-67 (Novocastra) antibodies in the developing ovaries of Wistar rat embryos and neonates [14.5, 18.5, 20.5days post-coitum (dpc), birth (day 0), 1, 3, 5, 7day post-partum (dpp)]. Estimation of reactive/total cell ratio, per cell type (germ and follicular cells) and visual field was achieved using the Image Pro Plus Software. The statistical interpretation of the results has shown that, before birth, using the PCNA antibody, the percentage of labeled/total germ cells (labeling index, LI) increases from 71.19% at 14.5dpc to 75.66% at 18.5dpc. It then decreases to 73.26% at 20.5dpc. At birth, the labeling index drops significantly (28.57%). Immediately after birth, the percentage of labeled/total germ cells increases, reaching 43.58% at 1dpp. Subsequently, a further decrease in the percentage of reactive cells is observed resulting to a maximum drop of the LI at 7dpp (18.41%). Using the Ki-67 antibody, the percentage of labeled/total germ cells is generally lower although the fluctuation is similar with that observed using the first marker of cell proliferation. Using the PCNA antibody, the LI of follicular cells in the developing ovary, increases from 0.70% (at 14.5dpc) to 28.94% (at 18.5dpc) and then drops to 18.03% (at 20.5dpc). At birth, the percentage of reactive follicular cells, reaches 27.66% and remains high thereafter. Similar results are obtained using the Ki-67 antibody. In conclusion, follicular cell reaction ratio, using both antibodies (PCNA and Ki-67), increases continuously throughout the examined period with a maximum value at 7dpp, suggesting a kinetics profile similar to that observed for Sertoli cells in the testis. In all age groups, PCNA labeling is more intense than Ki-67, a result that may be attributed to selective staining at different periods of the cell cycle.     

Cardiomyocytes undergo cells division following myocardial infarction is a spatially and temporally restricted event in rats

Dividing cardiomyocytes are observed in autopsied human hearts following recent myocardial infarction, however there is a lack of information in the literature on the division of these cells. In this study we used a rat model to investigate how and when adult mammalian cardiomyocytes proliferate by cell division after myocardial infarction. Myocardial infarction was induced in Wistar rats by ligation of the left coronary artery. The rats were sacrificed periodically up to 28 days following induced myocardial infarction, and the hearts subjected to microscopic investigation. Cardiomyocytes entering the cell cycle were assayed by observation of nuclear morphology and measuring expression of Ki-67, a proliferating cell marker. Ki-67 positive cardiomyocytes and dividing nuclei were observed initially after 1 day. After 2 days dividing cells gradually increased in number at the ischemic border zone, reaching a peak increase of 1.12% after 3 days, then gradually decreasing in number. Dividing nuclei increased at the ischemic border zone after 3 days, peaked by 0.14% at day 5, and then decreased. In contrast, Ki-67 positive cells and dividing nuclei were limited in number in the non-ischemic area throughout all experiments. In conclusion, mitogenic cardiomyocytes are present in the adult rat heart following myocardial infarction, but were spatially and temporally restricted.     

In situ analysis of the changes in expression of ovarian inhibin subunit mRNAs during follicle recruitment after ovulation in pigs

In situ hybridization was used on frozen tissue sections with digoxigenin-labelled antisense riboprobes to inhibin/activin alpha and beta(A) subunits to determine whether inhibin/activin subunit mRNA expression was associated with development of growing, steroidogenically active follicles during follicle recruitment after ovulation. Cell proliferation-associated nuclear antigen Ki-67 protein and cytochrome P450 aromatase expression in granulosa cells were determined immunohistochemically and used as markers for granulosa cell proliferation and steroidogenesis, respectively, on days 3, 5 and 7 after the onset of oestrus. The amounts of inhibin/activin alpha and beta(A) subunit mRNA and P450 aromatase protein were greater (102, 93, and 238%, respectively; P < 0.05) in medium than in small non-atretic follicles and were positively correlated with Ki-67 and with each other. Inhibin/activin alpha and beta(A) mRNA, P450 aromatase, and Ki-67 in granulosa cells were reduced by 66-83% (P < 0.001) in atretic follicles compared with non-atretic follicles. In addition, inhibin/activin alpha and beta(A) mRNA and P450 aromatase in small (1-2 mm) non-atretic follicles decreased (P < 0.05) between day 3 and day 7 independently of morphological or biochemical signs of atresia. The pattern of inhibin/activin subunit mRNA expression supports the notion that activin and inhibin have roles in growth and steroidogenesis in follicle recruitment during the early luteal phase of the oestrous cycle.     

Immunohistochemical evaluation of proliferative activity (Ki-67 index) in different histological types of cutaneous basal cell carcinoma

Evaluation of tumor cell proliferation status belongs to the basic prognostic indicators in a routine biopsy report. In cutaneous basal cell carcinoma (BCC), however, there are discrepancies about a true prognostic significance of this histopathological parameter. The aim of this study was to assess a proliferative activity (Ki-67 index) in BCCs of the skin. Biopsy specimens from 80 cutaneous BCCs (63 primary, 17 recurrent) of different histological types from 75 subjects (34 men, 41 women) were enrolled into this study. All samples were immunohistochemically stained by antibody against Ki-67 antigen (DAKO, clone MIB-1, dilution 1:100). For the statistical analysis, χ ² test was employed. We found a striking percentage variability of nuclear Ki-67 expression in individual tumors (range 2–70%). Mean value of Ki-67 index was 27.4% (in primary tumors 28.1 %, in recurrent lesions 25.6%). The highest Ki-67 expression occurred in infiltrative BCCs (average 38.1%), morpheaform BCCs (average 37.0%), and superficial BCCs (average 35.7%), the lowest expression was recorded in nodular BCCs (average 21.7%) and BCCs with adnexal (trichoepithelial) differentiation (18.6%). There were not persuasive and statistically significant quantitative differences in proliferation activity of tumor cells between the individual histological BCC types, as well as between primary and recurrent lesions. A distribution of Ki-67 positive cells in tumor nests was mostly irregular and areas with a high number of Ki-67 labeled cells often occurred adjacent to areas with a lower number of cells expressing this marker. Because of a marked Ki-67 staining variability, we can conclude that the simple quantification of BCC proliferation activity alone may not be sufficient for the prediction of further biological behavior, evolution and clinical outcome of this malignancy.     

不同肝病变组织中CD34、CD31、Ki-67的表达及意义

目的比较正常肝组织、慢性肝炎、肝硬化、肝细胞肝癌组织及肝转移腺癌中CD34、CD31、Ki-67不同表达,寻找有助于鉴别不同性质病变的生物学标记物.方法正常肝及病变肝组织标本共104例;其中,正常肝组织10例;慢生C型肝炎组织73例;肝硬化组织7例;肝细胞肝癌7例;结肠癌肝转移5例;乳腺癌肝转移2例.73例慢性C型肝炎组织全部为肝穿活检标本,其余组织均为手术切除标本.所有病例标本分别行CD34、CD31、Ki-67免疫组织化学染色,半定量评分系统评价染色结果.统计学分析结果数据.结果在非肿瘤组织,抗CD34阳性染色主要存在于汇管区,亦可见于汇管区周围的肝实质内血窦.阳性染色内皮细胞呈点状、线状、半环状及环状,散在或簇状分布.肿瘤组织内抗CD34阳性染色特征与非肿瘤组织相似,阳性染色血管在肿瘤组织内散布分布.CD34指数在各病变组中的表达排列顺序依次为:肝细胞肝癌>乳腺癌肝转移>结肠癌肝转移>肝硬化>慢性C型肝炎>正常肝组织,从正常肝组织至慢性肝炎至肝细胞肝癌,CD34表达明显增强.组织中,抗CD31阳性染色分布、定位、形态特征与CD34相似.CD31在慢性肝炎、肝硬化、肝细胞肝癌、结肠癌肝转移及乳腺癌肝转移组织中阳性表达率分别为:6.8%(5/73)、100%(7/7)、100%(7/7)、100%(5/5)、100%(2/2);肝癌组织中CD31染色强度明显大于非癌组织中,组间比较具有显著差异(P<0.05).Ki-67阳性染色细胞呈棕黄色核着色,散在分布于肝实质内.阳性染色细胞无形态特殊性,亦无分布上的特殊性.Ki-67在各病变组间的阳性表达率分别为:64.4%(47/73)、28.6%(2/7)、100%(7/7)、100%(5/5)、100%(2/2),其中以在结肠癌肝转移组织中表达最明显;组间比较具有非常显著差异(P<0.05).在正常肝脏、慢性C型肝炎、肝硬化、肝细胞肝癌CD34、CD31、Ki-67三种生物学标记物在同一标本同时表达的阳性率分别为:0%(0/0)、4.1%(3/73)、28.6%(2/7)、100%(7/7),CD34、CD31、Ki-67其中任两种同时表达的阳性率分别为0%(0/10)、63.0%(46/73)、100%(7/7)、100%(7/7).结论 CD34是慢性肝病、肝癌临床病理评价的指标之一,CD34与CD31、Ki-67同时分析有助于建立可靠的诊断.     

Cell Proliferation and Neuroblast Differentiation in the Rat Dentate Gyrus After Intrathecal Treatment with Adipose-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) have emerged as a new therapeutic tool for a number of clinical applications, because they have multipotency and paracrine effects via various factors. In the present study, we investigated the effects of adipose-derived MSC (Ad-MSC) transplantation via intrathecal injection through the cisterna magna on cell proliferation and differentiation of endogenous stem cells in the hippocampal dentate gyrus (DG) using Ki-67 (a marker for proliferating cells), and doublecortin (DCX, a marker for neuroblasts). The transplanted Ad-MSC were detected in the meninges, not in the hippocampal parenchyma. However, the number of Ki-67-immunoreactive cells was significantly increased by 83% in the DG 2 days after single Ad-MSC injection, and by 67% at 23 days after repeated Ad-MSC treatment compared with that in the vehicle-treated group after Ad-MSC transplantation. On the other hand, the number of DCX-immunoreactive cells in the DG was not changed at 2 days after single Ad-MSC injection; however, it was significantly increased by 62% 9 days after single Ad-MSC injection. At 23 days after repeated Ad-MSC application, the number of DCX-immunoreactive cells was much more increased (223% of the vehicle-treated group). At this time point, DCX protein levels were also significantly increased compared with those in the vehicle-treated group. These results suggest that the intrathecal injection of Ad-MSC could enhance endogenous cell proliferation, and the repeated Ad-MSC injection could be more efficient for an enhancement of endogenous cell proliferation and differentiation in the brain.     

Glutathione S-transferase and UDP-glucuronyltransferase activity in primary cultures of rainbow trout gill epithelial cells

The objective of this study was to characterize rainbow trout (Oncorhynchus mykiss) gill epithelial cells in primary culture by evaluating their ability to maintain glutathione and glucuronide conjugating enzymes. The activity and inducibility of the phase II enzymes was investigated as a function of culture time. Glutathione S-transferase (GST) and UDP-glucuronyltransferase (UDPGT) enzyme activities were measured in freshly isolated cells and in cells cultured for 7 and 12 days. GST activity, determined with 1-chloro-2,4-dinitrobenzene, decreased gradually to 72% after 7 days and to 38% after 12 days in culture compared with freshly isolated cells. There was no significant difference between UDPGT activities in freshly isolated cells compared with cells cultured up to 12 days although a transient decrease in activity was observed at day 7. In vitro induction of the enzymes was studied using beta-naphtoflavone (BNF) and 3-methylcholanthrene (3-MC) as inducers. GST activity increased 2-fold after exposure to BNF and 1.5-fold after 3-MC exposure for 48 h in 7 days old cultures. No induction was observed in 12 days old cultures. UDPGT activity was not induced either at day 7 or 12.     

The influence of glyco-nitric oxide conjugate on proliferation of breast cancer cells in vitro

The aim of the study was to evaluate the influence of a nitric oxide donor: Glyco-2-SNAP on the proliferation status of two breast cancer cell lines: MDA-MB-231 and MCF-7. The study was performed by the thymidine incorporation method as well as by the immunocytochemical detection of the Ki-67 antigen. We found that the donor significantly inhibits the process of proliferation. The effect of the Glyco-2-SNAP is significant in both lines, however stronger in MDA -MB-231 cells where the donor at 100 microM inhibited DNA synthesis from 70462.000 dpi (SD +/-2066.175, n=4) for control to about 3120.250 dpi (SD +/-971.689 n=4). In UCF-7 cells the control gave 31142.500 dpi (SD +/-712.9214, n=4) and the treatment with 100 microM of Glyco-2 SNAP resulted in 4095.50 dpi. (SD +/-315.723, n=4). In both lines SNAP, classical NO donor also had an inhibitory effect but much higher concentrations. Ki-67 protein expression was significantly influenced by Glyco-2-SNAP at 100 microM (42.5% +/-6.45) concentrations in MDA-MB 231. No effect of G-SNAP was seen in MCF-7 cells. The control staining for both lines was about 90%. Our results presesent the possibility of exploiting a novel kind of NO donor as a potential mode of treatment that may be an alternative to classical therapeutic strategies in breast cancer.     

Evidence for the isolation,growth, and characterization of malignant cells in primary cultures of human tumors

Isolation and growth of malignant cells from solid tumors have often met with disappointing results. Consequently, we have developed a cell culture methodology based on ex vivo explantation of tumor tissue, with subsequent monolayer cell outgrowth. In an attempt to assess methods for detection of malignant cells in these cultures, we analyzed and compared the results of cytopathology, growth in soft agar, and detection of telomerase activity with those of standard immunohistochemistry (IHC) techniques for the detection of cytokeratins, tumor marker p53, and proliferation marker Ki-67. The sensitivity of detection of malignant cells was 85% (22/26) for cytopathological examination, 30% (3/10) for soft agar growth, and 100% (12/12) for detection of telomerase activity. From these data, we concluded that both cytopathological examination and assessment of telomerase activity contribute to the detection of malignant cells in primary cultures of human solid tumors, whereas growth in soft agar was not a good indicator of malignant cells. Although not specific for malignant cells per se, IHC detection for epithelial cell cytokeratins showed a high degree of sensitivity (100%, 23/23), whereas the sensitivity for detection of tumor marker p53 and proliferation marker Ki-67 was 30% (7/23) and 70% (16/23), respectively. These data also provide proof that malignant tumor cells, derived from a diverse number of human solid tumors, can be isolated and grown in primary cell culture.     

Cell cycle-dependent reactivity with the monoclonal antibody Ki-67 during myeloid cell differentiation

The specificity and sensitivity of the monoclonal antibody Ki-67 in identifying proliferating cell compartments was tested with the human promyelocytic leukemia cell line HL-60 using multi-parameter flow cytometry. While correlated measurements of DNA content and Ki-67 immunofluorescence indicated that the antigen was present in all phases of the cell cycle, reactivity with the antibody was highest in proliferating S and G2+M cells. The analysis of the BrdU content of cells sorted on the basis of reactivity with Ki-67 showed a correlation between Ki-67 reactivity and BrdU uptake. In HL-60 cells induced to differentiate with dimethyl sulfoxide (DMSO), the loss of reactivity with Ki-67 paralleled the exit of cells from the cell cycle. This was not observed in DMSO-resistant HL-60 cells. These results validate the usefulness of the Ki-67 antibody for determining the proliferative stage of mammalian cells in culture.     

Docosahexaenoic Acid Is Required for the Survival of Rat Retinal Photoreceptors In Vitro

Abstract: The effect of docosahexaenoic acid (DHA) on neuronal survival was studied in cultured cells isolated from newborn rat retina. In vivo, the content of DHA in the retina increased nearly fourfold from days 2 to 12 after birth, whereas in retinal cells in culture it remained constant. Unlike amacrine cells, the photoreceptor cells in control cultures underwent a selective degeneration, starting at day 7, that led to their massive death by day 11. The addition of DHA at day 7 led to its active incorporation by the cultures, increasing from 6 to 21% of total fatty acids in cell lipids, and completely prevented photo-receptor cell death. When other fatty acids were tested, both neuronal fatty acid composition and photoreceptor death were the same as in control cultures. These results indicate that DHA is specifically required for the survival of retinal photoreceptors.     

USP7 promotes cell proliferation through the stabilization of Ki-67 protein in non-small cell lung cancer cells

The Ki-67 antigen (Ki-67) is the most reliable immunohistochemical marker for evaluation of cell proliferation in non-small cell lung cancer. However, the mechanisms underlying the regulation of protein levels of Ki-67 in non-small cell lung cancer have remained elusive. In this study, we found that Ki-67 and ubiquitin-specific processing protease 7 (USP7) protein were highly expressed in the nucleus of non-small cell lung cancer cells. Furthermore, statistical analysis uncovered the existence of a strong correlation between Ki-67 and USP7 levels. We could also show that the protein levels of Ki-67 in non-small cell lung cancer cells significantly decreased after treatment with P22077, a selective chemical inhibitor of USP7, while the Ki-67 mRNA levels were unperturbed. Similar results were obtained by knocking down USP7 using short hairpin RNA (shRNA) in lung cancer cells. Interestingly, we noticed that ubiquitination levels of Ki-67 increased dramatically in USP7-silenced cells. The tests in vitro and vivo showed a significant delay in tumor cell growth upon knockdown of USP7. Additionally, drug sensitivity tests indicated that USP7-silenced A549 cells had enhanced sensitivity to paclitaxel and docetaxel, while there was no significant change in sensitivity toward carboplatin and cisplatin. Taken together, these data strongly suggest that the overexpression of USP7 might promote cell proliferation by deubiquitinating Ki-67 protein, thereby maintaining its high levels in the non-small cell lung cancer. Our study also hints potential for the development of deubiquitinase-based therapies, especially those targeting USP7 to improve the condition of patients diagnosed with non-small cell lung cancer.     

Effects of low-dose tamoxifen on breast cancer biomarkers Ki-67, estrogen and progesterone receptors

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 α 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.     

Elevated Ki-67 expression is correlated with TNFalpha- and IFNgamma-induced apoptosis in tumour cells

Abstract. The expression of Ki-67 in tumour cells induced to apoptosis by tumour-necrosis-factor α (TNFα) and interferon γ (IFNγ) was studied. Ki-67 is known as a proliferation marker which is expressed in cycling cells, but not in resting quiescent or G_o cells. In numerous studies, the proportion of tumours expressing Ki-67 was determined and related to tumour grade or prognosis. A high percentage of Ki-67 expressing cells and a low apoptotic index were regarded as an indication of a progressive tumour. This implied that Ki-67 expression and apoptosis were contrary traits. In this study, the level of Ki-67 expression in human tumour cells in culture was measured after induction of apoptosis. The Ki-67 level was determined by flow cytometry and apoptosis was measured by various methods including PARP degradation (western blot) in detached and floating cells. While the floating cells were all apoptotic, more than 80% of the attached cells showed no apoptotic signs. The Ki-67 level of apoptotic cells was elevated about 3-fold compared to viable attached control cells. However, the cytokine-treated attached cells also expressed Ki-67 at similar high levels to the apoptotic floating cells, depending on sensitivity. The plot of Ki-67 level vs. remaining cells after treatment revealed a strong correlation between the level of Ki-67 expression and the sensitivity to cytokine-induced apoptosis. This implies that proliferation pathways and apoptotic signal transduction are connected.     

Evaluation of immunohistochemical markers of germ cells' proliferation in the developing rat testis: a comparative study

Germ cells' proliferation during testicular organogenesis in Wistar rat embryos and neonates [14.5, 18.5, 20.5 days post conception (dpc), birth (day 0), 1, 3, 5, 7 days post partum (dpp)] was evaluated via immunohistochemistry, using the PCNA and Ki-67 nuclear antibodies. Estimation of the reactive/total cell ratio, per visual field [labeIing index (LI)] was achieved using the Image Pro Plus Software. Immunostaining of the fetal testis, with both antibodies, revealed increasing germ cells' numbers between 14.5 dpc and birth. From birth onwards, a sharp decline of germ cells' population was observed in the first 3 days of postnatal life. Then, a transient increase of the LI, between 3 and 5 dpp, was noted. Afterwards, proliferation of germ cells ceased. These results indicate that, during fetal and neonatal life, two peaks of proliferative activity of germ cells are noticed. Following estimation of the LI for both PCNA and Ki-67, a prominent labeling for the first antibody was observed throughout the examined period. Ki-67 staining follows a similar pattern, showing, however, significant fluctuation in the obtained values, in comparison to PCNA. The significant differences observed don't seem to be simply a result of the different half lives of the two markers, but rather a consequence of additional underlying cellular activity associated with PCNA, such as DNA repair.     

Sex steroid receptor expression in the oviduct and uterus of sheep with estrus synchronized with progestagen or prostaglandin analogues

The objective of this study was to investigate differences in the expression of estrogen receptor-alpha (ERalpha), progesterone receptor (PR) and the proliferative indexes (Ki-67), in the uterus and oviduct of sheep with estrus synchronized either by prostaglandin analogues (Group PA, n=27) or by treatment with progestagens (Group P, n=29) on days 4 and 7 (day 0=estrus), when the embryos were collected. Immunohistochemical methods were used to quantify ERalpha, PR and Ki-67 in six superficial and deep compartments in the uterus and oviduct. The expression of ERalpha was significantly (P<0.01) lower in progestagen treated ewes than in prostaglandin analogues treated group in the luminal epithelium, superficial glands and superficial stroma in the uterus on day 4. The expression of PR was significantly lower in progesterone treated ewes than in the PA Group in the superficial gland (P<0.05) in both days studied. The lowest expression of PR was observed in the luminal caruncular epithelium and superficial glands in both treatments, obtaining the lowest levels on day 4 (P<0.05). There were significant differences between days 4 and 7 in the Ki-67 immunostaining in the luminal epithelium (P<0.01) and superficial glands (P<0.05). A higher cell proliferation was observed in the uterine epithelium (P<0.05) on day 4 in the animals treated with progestagens. Results indicate that sheep with synchronization of estrus with progestagens showed a reduction of ERalpha and PR protein expression in most of oviductal and uterine cells.     

Cell cycle-related proteins: a flow cytofluorometric study in human tumors

We used 2-parameter flow cytometry (FCM) to investigate the relationship between the cell cycle phases and 3 proteins whose expression is known to increase in proliferating cells: the surface antigen transferrin receptor (Trf-r), the "cyclin" (a proliferating cell nuclear antigen, PCNA), and the nuclear antigen recognized by the monoclonal antibody (MoAb) Ki-67. FITC-labeled antibodies against Trf-r, PCNA, and the Ki-67-reactive antigen, as well as propidium iodide-DNA distribution, were simultaneously measured on human leukemia HL-60 and K562, and breast carcinoma MCF-7 cell lines and on fresh human leukemic and glioblastoma cells. The 70% ethanol fixation for Trf-r and PCNA and the 95% acetone fixation for Ki-67 plus permeabilization (with 0.1% and 1% Triton X100, respectively, for the surface and the nuclear antigens) produced cell suspensions with negligible cell clumping, high-quality DNA profiles, and bright specific immunofluorescent staining. The investigated proteins have different relationships with the proliferative state of the cell. Trf-r is expressed mainly at the transition from G0/G1 to S-phase. PCNA expression is prominent in late G1 and through S-phase and decreases in G2-M. The Ki-67-reactive antigen is widely distributed in G1, S, and G2-M phases. Knowledge regarding the relationships between proliferation-associated antigens and cell cycle phase in normal and neoplastic cells could improve our understanding of the mechanisms underlying growth regulation and neoplastic transformation. Bivariate FCM is an easy method for obtaining these data from large numbers of cells.     

Ki-67 labeling in postmitotic cells defines different Ki-67 pathways within the 2c compartment

Simultaneous quantification of DNA and Ki-67 proliferation-associated antigen was performed using fluorescence image cytometry. In the MCF-7 cell line, the Ki-67 antigen content increases during the cell cycle, and its intranuclear distribution pattern varies. Quantitative evolution of Ki-67 content as a function of nuclear area makes it possible to define several pathways followed by cells going through the 2c compartment. 1) In some cells, the amount of Ki-67 antigen remains constant during G1 (Ki-67 stable pathway), and a characteristic speckled pattern can be observed. 2) In the larger fraction of cells analyzed, there is a postmitotic decrease in the Ki-67 (Ki-67 decrease pathway) content. In this pathway, labeling is located in the nucleoplasm in small nuclei, is located in nucleoli in intermediate-sized nuclei, and is absent from larger nuclei (G0). A progressive increase in Ki-67 content (Ki-67 increase pathway) was observed from intermediate-sized nuclei to S phase nuclei. From these results, we hypothesize that the Ki-67 stable pathway is the G1 phase of newly formed cells going directly to S phase in local optimal conditions of growth and that Ki-67 decrease pathway and Ki-67 increase pathway correspond to cells whose progression to S phase is regulated by extracellular factors.