Immunohistochemical markers of cellular proliferation: achievements, problems and prospects

Role of c-Fos in DNA damage repair

c-Fos, a member of the immediate early gene, serves as a widely used marker of neuronal activation induced by various types of brain damage. In addition, c-Fos is believed to play a regulatory role in DNA damage repair. This paper reviews the literature on c-Fos' involvement in the regulation of DNA damage repair and indicates that genes of the Fos family can be induced by various forms of DNA damage. In addition, cells lacking c-Fos have difficulties in DNA repair. c-Fos is involved in tumorigenesis and progression as a proto-oncogene that maintains cancer cell survival, which may also be related to DNA repair. c-Fos may impact the repair of DNA damage by regulating the expression of downstream proteins, including ATR, ERCC1, XPF, and others. Nonetheless, the underlying mechanisms necessitate further exploration.

Ki67 as a prognostic factor of craniopharyngioma's recurrence in paediatric population

PURPOSE

Craniopharyngioma is one of the most frequent benign tumours of the central nervous system in the paediatric population. Although it is a benign tumour according to the WHO classification, it significantly deteriorates the patient's quality of life. The aim of this study is to assess if proliferation index Ki67 can be a useful marker of the risk of craniopharyngioma's recurrence.

METHODS

Expression of Ki67 was examined in 85 specimens of primary craniopharyngioma and in 11 specimens of the recurring tumour. In all the cases, adamantinomatous type of craniopharyngioma was diagnosed. Values of Ki67 expression were compared between patients with and without recurrence, between patients with progression and relapse and between primary and recurrent tumours.

RESULTS

No statistically significant differences were found between proliferation index Ki67 values in tumours with recurrence and without (median values 2.5% and 3%, respectively, p = 0.69). The median value of proliferation index Ki67 in progression group was 1% and in the relapse group 4%; no statistical significance between those groups was found (p = 0.067). The median value of proliferation index Ki67 in primary tumours was 3% (0-20%) and in recurrent tumours it was 5% (0-14%). Despite the lack of statistical significance (p = 0.61), a tendency towards higher values of Ki67 in recurring tumours in comparison with primary tumours was shown.

CONCLUSIONS

Proliferation index Ki67 is not a reliable prognostic factor of craniopharyngioma's recurrence.

Spheroid Formation of Hepatocarcinoma Cells in Microwells: Experiments and Monte Carlo Simulations

The formation of spherical aggregates during the growth of cell population has long been observed under various conditions. We observed the formation of such aggregates during proliferation of Huh-7.5 cells, a human hepatocarcinoma cell line, in a microfabricated low-adhesion microwell system (SpheroFilm; formed of mass-producible silicone elastomer) on the length scales up to 500 μm. The cell proliferation was also tracked with immunofluorescence staining of F-actin and cell proliferation marker Ki-67. Meanwhile, our complementary 3D Monte Carlo simulations, taking cell diffusion and division, cell-cell and cell-scaffold adhesion, and gravity into account, illustrate the role of these factors in the formation of spheroids. Taken together, our experimental and simulation results provide an integrative view of the process of spheroid formation for Huh-7.5 cells.

Influence of Flow Behavior of Alginate-Cell Suspensions on Cell Viability and Proliferation

Tissue scaffolds with living cells fabricated by three-dimensional bioprinting/plotting techniques are becoming more prevalent in tissue repair and regeneration. In the bioprinting process, cells are subject to process-induced forces (such as shear force) that can result in cell damage and loss of cell function. The flow behavior of the biomaterial solutions that encapsulate living cells in this process plays an important role. This study used a rheometer to examine the flow behavior of alginate solution and alginate-Schwann cell (RSC96), alginate-fibroblast cell (NIH-3T3), and alginate-skeletal muscle cell (L8) suspensions during shearing with respect to effects on cell viability and proliferation. The flow behavior of all the alginate-cell suspensions varied with alginate concentration and cell density and had a significant influence on the viability and proliferation of the cells once sheared as well as on the recovery of the sheared cells. These findings provide a mean to preserve cell viability and/or retain cell proliferation function in the bioprinting process by regulating the flow behavior of cell-biomaterial suspensions and process parameters.

Neuronal Hyperactivity Disturbs ATP Microgradients, Impairs Microglial Motility, and Reduces Phagocytic Receptor Expression Triggering Apoptosis/Microglial Phagocytosis Uncoupling

Phagocytosis is essential to maintain tissue homeostasis in a large number of inflammatory and autoimmune diseases, but its role in the diseased brain is poorly explored. Recent findings suggest that in the adult hippocampal neurogenic niche, where the excess of newborn cells undergo apoptosis in physiological conditions, phagocytosis is efficiently executed by surveillant, ramified microglia. To test whether microglia are efficient phagocytes in the diseased brain as well, we confronted them with a series of apoptotic challenges and discovered a generalized response. When challenged with excitotoxicity in vitro (via the glutamate agonist NMDA) or inflammation in vivo (via systemic administration of bacterial lipopolysaccharides or by omega 3 fatty acid deficient diets), microglia resorted to different strategies to boost their phagocytic efficiency and compensate for the increased number of apoptotic cells, thus maintaining phagocytosis and apoptosis tightly coupled. Unexpectedly, this coupling was chronically lost in a mouse model of mesial temporal lobe epilepsy (MTLE) as well as in hippocampal tissue resected from individuals with MTLE, a major neurological disorder characterized by seizures, excitotoxicity, and inflammation. Importantly, the loss of phagocytosis/apoptosis coupling correlated with the expression of microglial proinflammatory, epileptogenic cytokines, suggesting its contribution to the pathophysiology of epilepsy. The phagocytic blockade resulted from reduced microglial surveillance and apoptotic cell recognition receptor expression and was not directly mediated by signaling through microglial glutamate receptors. Instead, it was related to the disruption of local ATP microgradients caused by the hyperactivity of the hippocampal network, at least in the acute phase of epilepsy. Finally, the uncoupling led to an accumulation of apoptotic newborn cells in the neurogenic niche that was due not to decreased survival but to delayed cell clearance after seizures. These results demonstrate that the efficiency of microglial phagocytosis critically affects the dynamics of apoptosis and urge to routinely assess the microglial phagocytic efficiency in neurodegenerative disorders.

Phagocytosis by microglia is tightly coupled to apoptosis, swiftly removing apoptotic cells and actively maintaining tissue homeostasis, but the neuronal hyperactivity associated with epilepsy disrupts the ATP gradients that drive phagocytosis, leading to the accumulation of apoptotic cells and inflammation.

Phagocytosis, the engulfment and digestion of cellular debris, is at the core of the regenerative response of the damaged tissue, because it prevents the spillover of toxic intracellular contents and is actively anti-inflammatory. In the brain, the professional phagocytes are microglia, whose dynamic processes rapidly engulf and degrade cells undergoing apoptosis—programmed cell death—in physiological conditions. Thus, microglia hold the key to brain regeneration, but their efficiency as phagocytes in the diseased brain is only presumed. Here, we have discovered a generalized response of microglia to apoptotic challenge induced by excitotoxicity and inflammation, in which they boost their phagocytic efficiency to account for the increase in apoptosis. To our surprise, this apoptosis/microglial phagocytosis coupling was lost in the hippocampus from human and experimental mesial temporal lobe epilepsy (MTLE), a major neurodegenerative disorder characterized by excitotoxicity, inflammation, and seizures. This uncoupling was due to widespread ATP release during neuronal hyperactivity, which “blinded” microglia to the ATP microgradients released by apoptotic cells as “find-me” signals. The impairment of phagocytosis led to the accumulation of apoptotic cells and the build-up of a detrimental inflammatory reaction. Our data advocates for systematic assessment of the efficiency of microglial phagocytosis in brain disorders.

Correlation of TNFAIP8 overexpression with the proliferation, metastasis, and disease-free survival in endometrial cancer

Tumor necrosis factor alpha-induced protein 8 (TNFAIP8) is an apoptosis regulator proven to have an important function in the proliferation, invasion, metastasis, and progression of malignancies. In this study, we investigated the clinical role of TNFAIP8 overexpression in endometrial cancer (EC) and determined the relationship of TNFAIP8 with the proliferative antigen Ki-67 and metastasis-related gene matrix metallopeptidase 9 (MMP9) in 225 tumor specimens by immunohistochemistry and western blot, in order to elucidate more information on the role of TNFAIP8 protein with regard to the pathogenesis of EC. An association was observed between TNFAIP8 overexpression and clinicopathologic factors, such as advanced International Federation of Gynecology and Obstetrics stage (P<0.001), higher histologic grade (P=0.017), deep myometrial invasion (P=0.030), lymphovascular space invasion (P=0.011), lymph node metastasis (P<0.001), and recurrence. Furthermore, TNFAIP8 overexpression was strongly correlated with MMP9 and Ki-67 expression in the progression of ECs. Patients with high expression of TNFAIP8 (P<0.001 for both) and Ki-67 (P=0.007 and P=0.008) had poor overall survival and disease-free survival (DFS) rates. MMP9 overexpression did not affect survival outcomes (P>0.05). Multivariate Cox regression analysis revealed that TNFAIP8 (P=0.029) and lymph node metastasis (P=0.022) were independent factors of DFS in patients with EC. These findings suggested that TNFAIP8 may be used as a prognostic marker for the recurrence of EC, and its promotion of the proliferation and metastasis in EC may be due to its mediation of Ki-67 and MMP9.

Classic "broken cell" techniques and newer live cell methods for cell cycle assessment

Many common, important diseases are either caused or exacerbated by hyperactivation (e.g., cancer) or inactivation (e.g., heart failure) of the cell division cycle. A better understanding of the cell cycle is critical for interpreting numerous types of physiological changes in cells. Moreover, new insights into how to control it will facilitate new therapeutics for a variety of diseases and new avenues in regenerative medicine. The progression of cells through the four main phases of their division cycle [G(0)/G(1), S (DNA synthesis), G(2), and M (mitosis)] is a highly conserved process orchestrated by several pathways (e.g., transcription, phosphorylation, nuclear import/export, and protein ubiquitination) that coordinate a core cell cycle pathway. This core pathway can also receive inputs that are cell type and cell niche dependent. "Broken cell" methods (e.g., use of labeled nucleotide analogs) to assess for cell cycle activity have revealed important insights regarding the cell cycle but lack the ability to assess living cells in real time (longitudinal studies) and with single-cell resolution. Moreover, such methods often require cell synchronization, which can perturb the pathway under study. Live cell cycle sensors can be used at single-cell resolution in living cells, intact tissue, and whole animals. Use of these more recently available sensors has the potential to reveal physiologically relevant insights regarding the normal and perturbed cell division cycle.

Immunohistochemical Expression of Cell Proliferating Nuclear Antigen (PCNA) and p53 Protein in Cervical Cancer

OBJECTIVE

This study was designed to evaluate the immunohistochemical expression of proliferating cell nuclear antigen (PCNA) and p53 protein expression in preneoplastic and neoplastic lesions in uterine cervix.

STUDY DESIGN

A total of 36 cervical biopsies were subjected for immunostaining and the results were correlated with different prognostic parameters. Bivariate and multivariate statistical analyses were done using "STATA" software.

RESULTS

PCNA labeling index and p53 expression increased with increasing severity of CIN lesions. PCNA labeling index was maximum (46.0) carcinoma cervix with intense positive staining. In bivariate statistical analysis, p53 and PCNALI were found to be insignificant (0.4184 and 0.4328, respectively). Menopausal stage was significantly associated with CA and CIN groups (P < 0.166 and P < 0.049), respectively.

CONCLUSION

These markers may be of greater importance in low-grade CIN lesions showing high proliferative index. This will place the low-grade lesions in higher grade indicating the utility of proliferative markers in decision making for intervention. This method is simple and cost effective and may be useful in developing countries where HPVDNA testing is still out of reach because of high cost.

Adult human neurogenesis: from microscopy to magnetic resonance imaging

Neural stem cells reside in well-defined areas of the adult human brain and are capable of generating new neurons throughout the life span. In rodents, it is well established that the new born neurons are involved in olfaction as well as in certain forms of memory and learning. In humans, the functional relevance of adult human neurogenesis is being investigated, in particular its implication in the etiopathology of a variety of brain disorders. Adult neurogenesis in the human brain was discovered by utilizing methodologies directly imported from the rodent research, such as immunohistological detection of proliferation and cell-type specific biomarkers in postmortem or biopsy tissue. However, in the vast majority of cases, these methods do not support longitudinal studies; thus, the capacity of the putative stem cells to form new neurons under different disease conditions cannot be tested. More recently, new technologies have been specifically developed for the detection and quantification of neural stem cells in the living human brain. These technologies rely on the use of magnetic resonance imaging, available in hospitals worldwide. Although they require further validation in rodents and primates, these new methods hold the potential to test the contribution of adult human neurogenesis to brain function in both health and disease. This review reports on the current knowledge on adult human neurogenesis. We first review the different methods available to assess human neurogenesis, both ex vivo and in vivo and then appraise the changes of adult neurogenesis in human diseases.

Assessing nanotoxicity in cells in vitro

Nanomaterials are commonly defined as particles or fibers of less than 1 microm in diameter. For these reasons, they may be respirable in humans and have the potential, based upon their geometry, composition, size, and transport or durability in the body, to cause adverse effects on human health, especially if they are inhaled at high concentrations. Rodent inhalation models to predict the toxicity and pathogenicity of nanomaterials are prohibitive in terms of time and expense. For these reasons, a panel of in vitro assays is described below. These include cell culture assays for cytotoxicity (altered metabolism, decreased growth, lytic or apoptotic cell death), proliferation, genotoxicity, and altered gene expression. The choice of cell type for these assays may be dictated by the procedure or endpoint selected. Most of these assays have been standardized in our laboratory using pathogenic minerals (asbestos and silica) and non-pathogenic particles (fine titanium dioxide or glass beads) as negative controls. The results of these in vitro assays should predict whether testing of selected nanomaterials should be pursued in animal inhalation models that simulate physiologic exposure to inhaled nanomaterials. Conversely, intrathoracic or intrapleural injection of nanomaterials into rodents can be misleading because they bypass normal clearance mechanisms, and non-pathogenic fibers and particles can test positively in these assays.

PCNA in situ hybridization: a novel and reliable tool for detection of dynamic changes in proliferative activity

In order to investigate developmental processes, several methods have been established that allow the visualization of local proliferation zones and to follow their dynamics during morphogenesis. In this study we present a detailed description of transitory and continuous proliferation zones in the developing chick embryo. By tracing the S-phase marker proliferating cell nuclear antigen (PCNA) at the mRNA level we were able to identify the initiation and termination of proliferation programs. This approach provides additional information in comparison to the well-known BrdU incorporation or the PCNA immunostaining, which exclusively labels cells that contain PCNA protein. By means of PCNA in situ hybridization we analyzed the normal expression pattern in the 2- to 5-day-old chick embryo. We furthermore monitored the effects on PCNA expression after various manipulations such as removal of the apical ectodermal ridge (AER), the zone of polarizing activity (ZPA), and the surface ectoderm. In addition, we applied morphogens, such as fibroblast growth factors (FGFs), bone morphogenetic proteins (BMPs), and retinoic acid (RA), and subsequently analyzed changes in the pattern of PCNA expression. While ablation of ZPA, AER, or ectoderm are known to reduce cell proliferation and were paralleled by loss of PCNA expression, neither BMP-2 nor BMP-4 affected PCNA expression. Upregulation of PCNA expression could be achieved by application of RA or FGFs, factors known to induce cell proliferation during limb bud outgrowth. The PCNA in situ hybridization data presented here clearly show that this method offers a novel, very sensitive tool for tracing cell proliferation and for visualizing the dynamic patterns arising due to the initiation and termination of the proliferation program.

Correlation between clinical characteristics and proliferative activity in patients with craniopharyngioma

OBJECTIVES

The aim of the study was to correlate the Ki-67 and cyclin A labelling index (LI) with clinical characteristics and risk of recurrence of craniopharyngiomas.

METHODS

47 consecutive patients were studied, 21 female and 26 male, aged 34.3 (2.8) years. Immunohistochemical analysis was performed on paraffin wax embedded material using monoclonal antibodies directed against the proliferation associated nuclear antigen Ki-67 and cyclin A.

RESULTS

The median Ki-67 LI was 8.6% (interquartile range, 4.4%-14.0%). Ki-67 LI was significantly higher in tumours with a heavy inflammatory reaction and diabetes insipidus at presentation, whereas other clinical and histological features were not associated with the proliferation index. There was a strong linear correlation between Ki-67 LI and cyclin A LI (r = 0.77; p<0.0001); therefore, cyclin A LI showed the same clinical and histological relations described for Ki-67 LI. Recurrence of craniopharyngioma occurred in 13 of 46 patients (28.3%). The median Ki-67 LI in the 13 recurrent craniopharyngiomas (9.0%) was not significantly different from that of non-recurring tumours (7.9%). Cyclin A LI was also not associated with the risk of relapse.

CONCLUSIONS

This study confirms the great variability of proliferative activity in craniopharyngiomas. Ki-67 and cyclin A LIs were associated with the presence of a heavy inflammatory reaction and diabetes insipidus, but did not correlate with the long term risk of tumour regrowth.

Association between histology grade, expression of HsMCM2, and cyclin A in human invasive breast carcinomas

AIM

Increased proliferation of tumour cells has prognostic value in human invasive breast carcinomas (IBCs), and high histology grade and cyclin A expression, which may reflect high proliferation rate, are associated with poor prognosis. Expression of HsMCM2 is related to cell proliferation. This study evaluates the correlation between the expression of cyclins A, D1, D3, and E, Ki-67, proliferating cell nuclear antigen (PCNA), histology grade, and HsMCM2 expression, in addition to the independent prognostic value of HsMCM2 expression in human IBCs.

METHODS

Immunohistochemistry to evaluate HsMCM2, Ki-67, and PCNA expression in tumours from 147 patients with IBC.

RESULTS

Nuclear staining for HsMCM2 was seen in 10-30% of the tumour cells in 30 samples, in 30-70% in 40 samples, in > 70% in 44 samples, and in < 10% in 33 samples. One way ANOVA showed a significant association between expression of HsMCM2 and cyclin A, D3, E, histology grade, and Ki-67. A borderline correlation was seen between HsMCM2 and PCNA. In multivariate analysis, the only association was with cyclin A, in addition to a borderline association with histology grade. In a Cox regression hazards model, expression of HsMCM2 was associated with poor patient survival, although it lost its independent prognostic value when cyclin A expression was included. Ki-67 and PCNA expression were not associated with patient survival.

CONCLUSION

Cyclin A expression is independently associated with HsMCM2 expression, histology grade, and Ki-67. HsMCM2 expression is associated with poor patient survival, although it loses prognostic value when adjusted for cyclin A.

Apoptosis control and proliferation marker in human normal and neoplastic adrenocortical tissues

We evaluated by immunohistochemistry the expression of the Bcl-2 and p53 proteins, as markers of apoptosis control, and of MIB-1, as a marker of cell proliferation, in a series of normal and neoplastic adrenocortical tissues. The specimens were 13 normal adrenals, 13 aldosterone-producing adenomas, 13 non-functioning adenomas and 16 carcinomas. Results were calculated as percentage of immunostained cells by using specific antibodies. No p53 protein was detected in any of the adrenocortical adenomas (functioning and non functioning) or normal adrenals, while p53 was overexpressed in 15 out of 16 carcinomas. In particular, 10 adrenal cancer specimens (62.5%) showed strong staining in a high percentage (range 10-50%) of the malignant cells. The percentage of Bcl-2 positive cells was higher (P<0.05 or less) in non-functioning adenomas (8.1+/-1.9%) and in carcinomas (14.9+/-5.6%) than in normals (2.9+/-0.9%) and aldosterone-producing adenomas (5.3+/-1.3%) since four specimens of the non-functioning adenomas-group (30.7%) and six of the carcinomas-group (37.5%) showed over 10% positivity (cut-off for normal values, set at 90th percentile of our controls). MIB-1 positivity was 0.50+/-0.36% in normals, 0.54+/-0.08% in non-functioning adenomas and 0.54+/-0.08% in aldosterone-producing adenomas. MIB-1 was expressed in all carcinomas with values (13.7+/-3.1%) significantly (P<0.0006) higher than in the other groups. In conclusion, the present data indicate that the apoptosis control and proliferation activity evaluated by the p53 and MIB-1 proteins are impaired in adrenal carcinomas but preserved in adenomas, independently of their functional status. Therefore, these immunohistochemical markers, overexpressed in carcinomas only, may be useful in the diagnosis of malignancy in adrenocortical tumours. Whether Bcl-2 positivity found in some carcinomas and non-functioning adenomas may constitute, in the latter, a negative prognostic marker is still unknown.

Angiotensin II blockade reduces radiation-induced proliferation in experimental radiation nephropathy

Total-body irradiation or renal irradiation is followed by a well-defined sequence of changes in renal function leading eventually to renal failure. Previous studies in a rat model have shown that inhibition of angiotensin-converting enzyme or blockade of angiotensin II receptors can prevent the structural and functional changes that occur after renal irradiation, and that these interventions are particularly important between 3 and 10 weeks after irradiation. We have now shown that in the same rat model, total-body irradiation induces proliferation of renal tubular cells (i.e., an increase in the number of cells staining positive for proliferating cell nuclear antigen) within 5 weeks after irradiation. Treatment with an angiotensin II receptor blocker delays this radiation-induced tubular proliferation and decreases its magnitude. Renal radiation also induces proliferation of glomerular cells, but the relative increase in glomerular proliferation is not as great as that seen in renal tubular cells, and the increase is not delayed or decreased by treatment with an angiotensin II receptor blocker. We hypothesize that angiotensin II receptor blockers exert their beneficial effect in radiation nephropathy by delaying the proliferation (and hence the eventual mitotic death) of renal tubular cells that have been genetically crippled by radiation.

Lack of correlation between Ki-67 labelling index and tumor size of anterior pituitary adenomas

AIMS AND BACKGROUND

The Ki-67 is a nuclear antigen detected by the monoclonal antibody MIB-1 and its Labeling Index (LI) is considered a marker of normal and abnormal cell proliferation. Pituitary adenomas are generally well differentiated neoplasms, even if in about one third of cases they are invasive of surrounding tissues. The aim of this study is to evaluate the correlation between Ki-67 labelling index and tumor size of pituitary adenomas extimated by means CT and MRI and confirmed at operation.

METHODS

Using the monoclonal antibody MIB-1, we evaluated the expression of Ki-67 in 121 anterior pituitary adenomas consecutively operated on in a 48-month period.

RESULTS

In relation to neuroradiological (CT and MRI) and surgically verified tumor size, we identified 24 microadenomas, 27 intrasellar macroadenomas, 34 intra-suprasellar macroadenomas, and 36 intra-supra-parasellar macroadenomas. The adenomas were non-infiltrating (76 cases) and infiltrating (45 cases) adenomas. The wall of the cavernous sinus (CS) was infiltrated in 18 cases. Forty-eight adenomas were non-functioning and 73 functioning. The overall mean +/- SD Ki-67 LI was 2.72 +/- 2.49% (median 1.6). It was 2.59 +/- 1.81 in microadenomas, 2.63 +/- 3.45 in intrasellar macroadenomas, 1.91 +/- 2.11 in intra-suprasellar macroadenomas, and 3.29 +/- 5.45 in intra-supra-parasellar macroadenomas (p = 0.27). It was 3.73 +/- 5.13% in infiltrating and 2.03 +/- 2.41% in non-infiltrating adenomas (p = 0.02), and 5.61 +/- 7.19% in CS-infiltrating versus 2.09 +/- 2.37% in CS-non-infiltrating adenomas (p = 0.0005).

CONCLUSIONS

Our preliminary results seem to exclude significative correlations between Ki-67 LI and tumor size of anterior pituitary adenomas, even if this index can be considered a useful marker in the determination of the infiltrative behaviour of these tumors.

Apoptosis of proliferative cortical tubular epithelia in chronic progressive nephrosis of rats

To investigate the role of apoptosis in the pathogenesis of rat chronic progressive nephrosis (CPN), the kidney of male F344/DuCrj rats, 19, 59, and 111 weeks of age, was examined histologically. In situ analysis for DNA fragmentation and proliferating cell nuclear antigen (PCNA) was performed simultaneously by TdT-mediated dUTP-biotin nick end labeling (TUNEL) and immunohistochemistry, respectively. CPN was seen in all the kidneys of 59-week-old (n=6) and 111-week-old rats (n=16), correlating significantly (p<0.01) with age. There were apoptotic bodies (ABs) in the single-layered epithelia of dilated tubules (SLD) and the multilayered epithelia (ML) of the cortical tubules. There were no ABs in any of the kidneys of the 19-week-old (n=5) or 59-week-old rats (n=6). Proliferative activity might have been enhanced in the single-layered and flattened epithelia, SLD, and ML of the cortical tubules in the kidneys of the 59-week-old rats (n=6) compared with that in 111-week-old rats (n=8). The correlations between the TUNEL-positive ratio and number of PCNA-positive cells, and age and the CPN grade were significant (p<0.01) exclusively in the ML. Thus, the results suggest that apoptosis occurs in the proliferative ML of rat CPN, and the pathological significance might be the removal of abnormal or excess cells.

Ki-67 labelling index and invasiveness among anterior pituitary adenomas: analysis of 103 cases using the MIB-1 monoclonal antibody

AIMS

To investigate the relation between proliferative activity of anterior pituitary adenomas, quantified by the Ki-67 labelling index, and their invasive behaviour.

METHODS

Expression of Ki-67 was evaluated in 103 anterior pituitary adenomas consecutively operated on in a 36 month period and correlated with surgical evidence of invasiveness.

RESULTS

Non-invasive (n = 65) and invasive (n = 38) adenomas were identified from surgically verified infiltration of sellar floor dura and bone. The wall of the cavernous sinus was infiltrated in 16 cases. Forty one adenomas were non-functioning and 62 functioning (24 prolactin, 21 growth hormone, 10 ACTH, seven mixed). The overall mean (SD) Ki-67 labelling index was 2.64 (3.69) per cent (median 1.5). The mean index was 3.08 (4.59) per cent in functioning and 1.97 (1.78) per cent in non-functioning tumours; 5.47 (9.52) per cent in ACTH adenomas and 2.33 (2.42) per cent in others (p = 0.01); 3.71 (5.17) per cent in invasive and 2.01 (2.45) per cent in non-invasive adenomas (p = 0.027); and 5.58 (7.24) per cent in cavernous sinus infiltrating v 2.10 (2.39) per cent in cavernous sinus non-infiltrating adenomas (p = 0.0005). To identify a value of labelling index beyond which adenomas should be considered invasive and another beyond which cavernous sinus infiltration should be suspected, normality Q-Q plots were obtained: a threshold labelling index of 3.5% for invasive adenomas and of 5% for cavernous sinus infiltrating adenomas was defined, with statistically significant differences (p = 0.02 and p = 0.004, respectively).

CONCLUSIONS

The Ki-67 labelling index can be considered a useful marker in determining the invasive behaviour of anterior pituitary adenomas.

Association between nm23-H1 expression, proliferation and apoptosis in non-small cell lung carcinomas

Twelve non-small cell lung carcinomas and adjacent normal lung tissues were examined for mutations of the nm23-H1 gene by using SSCP analysis and for an expression of the nm23-H1 protein by immunohistochemistry. No mutations could be found in either the carcinomas or in the adjacent normal tissues. In contrast, six of 12 carcinomas showed protein expression while only one adjacent normal lung tissue yielded a positive staining result. Therefore, the expression of nm23-H1 protein was analysed in a larger group of non-small cell lung carcinomas (n = 185) to determine whether or not the expression of nm23 protein may be of prognostic relevance. Only a weak relationship between nm23-H1 expression and lymph node involvement was observed. However, a significant correlation between proliferation and nm23-H1 expression was detected. Additionally, a direct correlation between apoptosis and nm23-H1 expression or between myc and nm23-H1 expression was found. Finally, non-small cell lung carcinomas that expressed nm23-H1 protein were more frequently sensitive to doxorubicin than carcinomas that did not express this protein.

Proliferation indices as molecular pharmacodynamic endpoints in evaluation of anticancer drug effect in human solid tumors

PURPOSE

The present study compared proliferative indices, i.e. incorporation of DNA precursor (i.e. thymidine or TdR, and bromodeoxyuridine or BrdU) and expression of proliferating cell nuclear antigen (PCNA), as molecular pharmacodynamic endpoints in evaluation of anticancer drug effect in human solid tumors.

METHODS

Tumor specimens obtained from patients were grown as histocultures. After treatment with doxorubicin, mitomycin C, and/or paclitaxel, cells labeled by [3H]TdR were identified using autoradiography, and cells labeled by BrdU and PCNA were identified using immunohistochemical techniques. Drug effect was measured as reduction of DNA precursor-labeled cells or PCNA-expressing cells.

RESULTS

The results indicate that (a) the two DNA precursors, TdR and BrdU, labeled the same cells and resulted in identical pharmacodynamics, (b) the pharmacodynamics established using inhibition of DNA precursor incorporation were qualitatively and quantitatively different from the pharmacodynamics established using inhibition of PCNA expression, (c) the inhibition of PCNA expression was erratic in some tumors, and (d) the differences in pharmacodynamics established using the two end points are drug-specific, with greater differences for paclitaxel than for mitomycin C.

CONCLUSIONS

The erratic results measured by the PCNA labeling method suggest that this method may be less reliable than the conventional DNA precursor labeling method. The finding of identical pharmacodynamics of doxorubicin and paclitaxel established using BrdU and [3H]TdR indicates that the two precursors are interchangeable. Because the methodology for detecting BrdU incorporation requires less time and does not require the use of radioactivity, we conclude that inhibition of BrdU incorporation represents a useful endpoint for evaluating the antiproliferative activity of anticancer drugs in human solid tumors.

Role of p27Kip1 and cyclin-dependent kinase 2 in the proliferation of non-small cell lung cancer

The cell cycle is governed by a family of cyclin-dependent kinases (Cdks). Cdk2 forms a functional complex with cyclin E and plays a pivotal role in the regulation of G1/S transition. Cdk2 activity is negatively regulated by interactions with inhibitors. p27Kip1, one of the most potent inhibitors of Cdk2, was recently identified as a powerful negative prognostic marker in non-small cell lung cancer as well as in colorectal and breast cancer. In the present study, the expression of p27 and Ki-67 antigen in nonneoplastic and cancerous lung tissues was determined by immunohistochemistry. After establishing that the antibody-measured p27 labeling index was a good reflection of the level of p27 expression measured by Western blotting, we show that p27 labeling index is decreased in cancerous lung tissues, compared with nonneoplastic lung tissues, and exhibits a significant inverse relation to the proliferation marker Ki-67 antigen, detected with monoclonal antibody MIB-1. Consistent with these data, all cancerous lung tissues showed enhanced degradation activity of p27 compared with nonneoplastic lung tissues and, in addition, increased levels of the phosphorylated form of Cdk2, as determined with Western blot analysis. The H1 histone kinase activity associated with Cdk2 was also increased in non-small cell lung cancers. Statistical analysis showed that proliferative activity as measured by MIB-1 labeling index was highly correlated with Cdk2 activity (r = 0.767, P < 0.0015). These results suggest that p27 and Cdk2 may play an important role in the proliferation of non-small cell cancer.

Intestinal maturation in mice lacking CCAAT/enhancer-binding protein alpha (C/EPBalpha)

In rodents, there is a surge of intestinal expression of CCAAT/enhancer-binding protein alpha (C/EBPalpha) in the late fetal phase just before morphological maturation and the onset of expression of numerous epithelial genes. To investigate directly the hypothesis that C/EBPalpha plays a causal role in the latter phenomena, we have assessed both structural and functional maturation in neonatal intestine from C/EBPalpha-null mice and their littermates. No effects of C/EBPalpha genotype were observed on mucosal architecture or on the size of the proliferative zone in the intestinal crypts. Likewise, the mRNA levels for the glucose transporter 2 (GLUT2), intestinal and liver fatty acid-binding proteins, and apolipoprotein A-IV in newborn intestine were similar in all genotypes. Paradoxically, Na+/glucose co-transporter (SGLT1), lactase phlorizin-hydrolase and apolipoprotein B mRNAs were more abundant in the C/EBPalpha-deficient animals. In wild-type intestines, C/EBPbeta and C/EBPdelta mRNAs were detectable throughout the late fetal period and increased toward term in parallel with C/EBPalpha mRNA. In newborn intestine, there was no compensatory up-regulation of these isoforms in the C/EBPalpha-deficient mice. We conclude that C/EBPalpha has no essential role in morphological maturation of the intestine, the pattern of proliferation of the epithelium, or the onset of expression of this cluster of epithelial mRNAs. However, since other C/EBP isoforms are present in the developing intestine, it is possible that there is a generic requirement for a member of the C/EBP family.

CD26 (Dipeptidyl Aminopeptidase IV) Expression in Normal and Diseased Human Thyroid Glands

The objective of the present study was to investigate CD26 (dipeptidyl aminopeptidase IV) expression in normal and diseased thyroids and its relation to differentiation and cell proliferation. CD 26 was also evaluated as a possible marker of malignancy in thyroid neoplasias. A total of 38 normal thyroids and 117 diseased thyroids (neoplastic and non-neoplastic) were evaluated. CD26 and thyroglobulin (Tg) expression was determined by analyzing at least 200 cells/specimen. A minimum of 500 cells/specimen were counted to calculate the MIB-1-positive cell rate expressed as a percentage of total nucleated epithelial cells. CD26 expression was absent in all thyroids from fetuses and children. Among the adults, 7.1 % had CD26 expression only in oncocytic metaplastic areas. In 3 of the 7 elderly subjects, CD26 expression was present in 0.2-90% of epithelial cells. CD26 expression was observed in all diseased thyroids. Since this enzyme is also expressed in benign conditions, it is not useful as a marker of malignancy. There was no relationship between CD26 and Tg expression. The MIB-1-positive cell rate was found to be low for all kinds of thyroid tissues, and when the cell proliferation rate was analyzed according to CD26 expression, a greater cell proliferation rate was found in CD26-positive differentiated (follicular and papillary) carcinomas than in CD26-negative carcinomas. These results demonstrate that expression of this enzyme is related to the proliferative activity of follicular cells.

MIB-1 proliferative activity in invasive breast cancer measured by image analysis

AIMS

To determine cell proliferation in infiltrating breast carcinomas.

METHODS

Using the MIB-1 monoclonal antibody, the proliferation index was measured in paraffin wax sections of 871 breast cancers. The MIB-1 proliferation index was compared with other markers of disease progression: size, lymph node status, histotype, oestrogen and progesterone receptor status, expression of p53 and Neu, and DNA ploidy. All parameters were measured using image analysis. In 347 tumours, the MIB-1 and Ki-67 proliferation indexes were compared. Follow up data were available for 170 cases (median 66.5 months).

RESULTS

Of the tumours, 314 (36%) had a high proliferation index. The MIB-1 proliferation index was correlated directly with size, nodal status, overexpression of p53 and Neu, and the DNA index; and inversely with oestrogen and progesterone receptor status. The correlation between MIB-1 and Ki-67 proliferation indexes was statistically significant. In patients with pT1 tumours, a low proliferation index correlated with a longer relapse-free interval and overall survival; node negative patients with a low proliferation index had a longer overall survival.

CONCLUSIONS

The MIB-1 proliferation index is a reliable, practical and useful method of measuring proliferative activity and is an important predictor of clinical behaviour.

Lack of prognostic significance of the monoclonal antibody Ki-S1, a novel marker of proliferative activity, in node-negative breast carcinoma

In a series of 205 node-negative breast cancers (NNBC), we determined staining by the novel antibody Ki-S1, a marker of tumor cell proliferation, in order to test its association with other prognostic variables and its prognostic significance. Ki-S1 was determined in routinely formalin-fixed paraffin-embedded tumor samples. Ki-S1 gave a nuclear staining in the majority of the carcinomas (188 of 205), with percentages of reacting nuclei ranging from 2% to 90% (median value of 7%). In 107 tumors frozen sections were available to also assess the Ki-67 antibody. Among these, 94 had a nuclear staining of cancer cells ranging from 5% to 80% (median value of 7%). In 46 tumors we also determined the MIB-1 antibody. The percentage of MIB-1 nuclear staining ranged from 1% to 50% (median value of 20%). There was no significant relationship between Ki-S1 and the other two cell kinetic markers. Ki-S1 labeling was significantly associated only with tumor size (p = 0.03). With a median follow-up of 6 years, Ki-S1 had no significant prognostic value for either relapse-free survival (RFS) or overall survival (OS) (Ki-S1 as continuous logarithmic variable; p = 0.86 and p = 0.23, respectively). For RFS the following variables had a significant prognostic value: Ki-67 (< or = 10% vs > 10%; p = 0.037); progesterone receptor (PgR) expression (- vs+/++; p = 0.041); tumor size (pT1 vs pT2-3; p = 0.042) and grading (GI vs GII-III; p = 0.047). For OS, tumor size (p = 0.0044), age (continuous variable; p = 0.0060), and Ki-67 (p = 0.043) were significantly prognostic. In multivariate analysis (final model), only tumor size retained a significant and independent prognostic value for RFS (p = 0.0042). For OS, both tumor size (p = 0.0029) and age (< or = 55 years vs > 55 years; p = 0.041) retained significance in the multivariate model. In conclusion, Ki-S1 does not seem to have prognostic relevance in this series of NNBC. Possible hypotheses to explain this observation are discussed.

Epitope analysis of antibodies recognising the cell proliferation associated nuclear antigen previously defined by the antibody Ki-67 (Ki-67 protein)

AIMS--To elucidate the fine specificities of the antibodies MIB 1 and MIB 3 and of additional monoclonal antibodies which also recognise the Ki-67 protein (MIB 5, IND.64, JG-67-2a). METHODS--Different parts of the Ki-67 protein cDNA were expressed in Escherichia coli. Bacterial lysates were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and blotted on to nitrocellulose. Additionally different peptides were synthesised on a membrane support (SPOT-Blot). The immunoreactivity of the antibodies with the recombinant proteins and the immobilised synthetic peptides, respectively, was analysed. A competition enzyme linked immunosorbent assay (ELISA) using a soluble synthetic peptide was also performed. RESULTS--The epitopes of all antibodies tested were contained within the same region of seven amino acids. The antibodies MIB 1 and MIB 3 required the five amino acid sequence FKELF for binding, whereas Ki-67, JG-67-2a, MIB 5 and IND.64 detected the sequence FKEL. CONCLUSIONS--It is concluded that the amino acid sequence FKELF represents an immunodominant area of the Ki-67 protein and that there is no correlation between the ability to detect the Ki-67 protein in paraffin wax sections irradiated with microwaves and the epitopes recognised by the antibodies.

Comparison of labelling by bromodeoxyuridine, MIB-1, and proliferating cell nuclear antigen in gastric mucosal biopsy specimens

AIMS

To compare proliferating cell nuclear antigen (PCNA) and MIB-1 with bromodeoxyuridine (BrdU) pulse labelling, a specific marker of cell proliferation, in endoscopic gastric biopsy specimens.

METHODS

Twenty four biopsy specimens were obtained from 12 patients: 10 antral and eight body specimens were suitable. Each specimen was routinely processed and stained with haematoxylin and eosin. A modified Giemsa stain was used to detect the presence of Helicobacter pylori. Sections of the specimens were labelled with BrdU, MIB-1, and PC10. Gastric mucosa specimens were divided into three zones. The numbers of positively staining nuclei for 500 epithelial cell nuclei were counted in each zone and expressed as a percentage.

RESULTS

The proportion of PCNA positive cells (range 0-90%) was much greater in all specimens (10 antrum, eight body). BrdU positive cells were virtually all confined to zone 2 (0-17% cells in this zone were positive) (zone 1 = surface and gastric pit, zone 2 = isthmus, zone 3 = gland base), while PCNA positive cells were present in all three zones (1 = 23-90%, 2 = 43-90%, 3 = 0-74%). Spearman's rank coefficient correlation of 0.57 confirmed that the percentage of positively staining cells varied in the same direction for both PCNA and BrdU (p < 0.001). PCNA, however, was overexpressed in all zones of the gastric epithelium compared with BrdU. In 38 biopsy specimens from 19 patients, of which 14 antrum and 11 body were suitable, the proportion of MIB-1 positive cells (0-59%) was greater than BrdU in most. As with BrdU labelling, the MIB-1 positive cells were confined to zone 2 (zone 1 = 1-11%); zone 2 = 21-59%; zone 3 = 0-13%) and the coefficient correlation for MIB-1 and BrdU was 0.63 (p < 0.001).

CONCLUSIONS

MIB-1 accurately reflects the S-phase fraction in gastric mucosa, determined by BrdU labelling in conventionally processed gastric biopsy material. Caution is needed in the interpretation of PCNA labelling detected by PC10, which should not be accepted uncritically as a marker of cell proliferation in paraffin wax embedded material.