PCNA and Ki-67 labelling indices in pre-irradiated and post-irradiated astrocytomas: a comparative immunohistochemical analysis for evaluation of proliferative activity

Correlation of immunoglobulin G expression and histological subtype and stage in breast cancer

INTRODUCTION

Recently, growing evidence indicates that immunoglobulins (Igs) are not only produced by mature B lymphocytes or plasma cells, but also by various normal cells types at immune privileged sites and neoplasm, including breast cancer. However, the association of breast cancer derived IgG with genesis and development of the disease has not yet been established.

METHODS

In this study we examined the expression of IgG in 186 breast cancers, 20 benign breast lesions and 30 normal breast tissues. Both immunohistochemistry with antibodies to Igκ (immunoglobulin G κ light chain) and Igγ (immunoglobulin G heavy chain) and in situ hybridization with an antisense probe to IgG1 heavy chain constant region gene were performed. Various clinicopathological features were also analyzed.

RESULTS

We found that IgG is specifically expressed in human breast cancer cells. Both infiltrating ductal carcinoma and infiltrating lobular carcinoma had significantly greater numbers of Igκ and Igγ positive cancer cells as compared with medullary carcinoma, carcinoma in situ, and benign lesions (all p<0.05). In addition, IgG expression was correlated with breast cancer histological subtypes (p<0.01) and AJCC stages (p<0.05), with more abundance of IgG expression in more malignant histological subtypes or in more advanced stage of the disease.

CONCLUSIONS

IgG expression in breast cancer cells is correlated with malignancy and AJCC stages of the cancers. This suggests that breast cancer derived IgG may be associated with genesis, development and prognosis of the cancer.

Long-term molecular changes in WHO grade II astrocytomas following radiotherapy

Monitoring the long-term radiotherapy-associated molecular changes in low-grade gliomas (LGGs) facilitates the understanding of LGG response to radiotherapy. In this study, we used immunohistochemistry to analyze the expression of Ki-67, tumor protein P53 (TP53), P21, and P27 in 8 paired WHO grade II astrocytoma samples. The interval between radiotherapy (RT) and the second surgery was more than 3 months in all cases. The average Ki-67 labeling index (LI) was 5.3% in pre-RT samples and 11.54% in post-RT samples. Ki-67 LI was higher in the primary tumors that underwent malignant transformation observed at the second surgery after radiation. Post-RT Ki-67 LI decreased in 2 cases with an interval of less than 12 months between RT and the second surgery. TP53 expression was found in 3 out of 4 pre-RT samples with malignant transformation and in 1 out of 4 pre-RT samples without malignant transformation. Post-RT TP53 increased in 2 cases in which increased expression of P21 or P27 was also observed. Our study suggests that radiotherapy can inhibit WHO grade II astrocytoma proliferation as reflected by Ki-67 LI, but the effect attenuates with time. In addition, there is a tendency of malignant transformation for WHO grade II astrocytomas with a high Ki-67 level or TP53 expression in initial samples.

Distribution and differentiation of microglia in the human encephalon during the first two trimesters of gestation

We describe the topographical distribution of microglial subpopulations during development of the human diencephalon and telencephalon. Brains from embryos and fetuses age 5-23.5 gestational weeks (gw) were subjected to single- and double-immunolabeling for lectin RCA-1 (Ricinus Communis Agglutinin 1), Iba1 (a microglial marker), CD68 (specific of macrophages), CD45 (marker for mononucleate cells of hematopoietic lineage), CD34 (expressed on endothelial cells), and MIB1 and Ki67 (markers for cell proliferation). At 5.5 gw the first intracerebral microglial cells were seen close to the meninges and choroid plexus near the di-telencephalic fissure. They were amoeboid and positive for Iba1, CD45, and RCA-1, whereas cells in the deep parenchyma expressed Iba1/CD68/RCA-1 and constituted clusters. In the developing diencephalon, microglial clusters were located in junctional regions of the white matter anlagen, most notably at the junctions of the internal capsule with the thalamic projections, the external capsule, and the cerebral peduncle. In the cortical anlagen, Iba1+/RCA-1/CD68+/CD45+ cells accumulated at 10-12 gw, constituting a tangential band at the junction between the cortical plate and the subplate. Between 10 and 16 gw microglial clusters increased markedly in size and cellular density. Contact between Iba1+ microglia and CD34+ blood vessels was clearly visible from 10-12 gw onward, first in microglial clusters of the white matter anlagen and subsequently throughout the parenchyma. From the middle of the second trimester onward microglial cells colonized the entire cerebral parenchyma, developed a ramified morphology, and downregulated their surface antigens, but remained more numerous in the white matter.

Proliferation markers in the adult rodent brain: bromodeoxyuridine and proliferating cell nuclear antigen

The rostral migratory stream is one of the few regions of the adult mammalian central nervous system in which cellular migration and proliferation have been described. Most rostral migratory stream cells divide rapidly and hence different proliferation markers have been employed to identify them. Nitrogen base substitutes, such as tritiated thymidine or 5-bromo-2'-deoxyuridine (BrdU), together with endogenous molecules, such as Proliferating Cell Nuclear Antigen (PCNA), are the cell cycle markers most widely employed. Protocols for BrdU and PCNA localization are both plentiful and diverse, but to date no optimized protocol for obtaining trustworthy double staining of both markers has been described. In this work, we propose optimized protocols for achieving both single staining and the joint detection of BrdU and PCNA in the rodent brain using double-immunofluorescence procedures. The double labeling described allows the discrimination of different cell cycle stages in migratory cells from the mouse brain.

Immunohistochemical Proliferation Markers May Overestimate the Growth Potential After Ionizing Radiation: In Vivo Study in the Rat Anterior Pituitary Gland

The effect of ionizing radiation on the expression of immunohistochemical proliferation markers was examined in the rat pituitary gland. Rats were irradiated in the pituitary region with a dose of 40 Gy, or were sham-irradiated as controls. Bromodeoxyuridine (BrdU) was given to the rats after one week, either one hour (Br-1 group) or 17 hours (Br-17 group) before perfusion fixation. Immunohistochemical staining for BrdU, topoisomerase II-alpha (TopoII), Ki-67 (MIB-5), p21WAF1/Cip1 (p21), and p27Kip1 (p27) was performed. Apoptotic cells were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labeling method. The mean BrdU labeling index (LI) and MIB-5 LI were significantly higher in the irradiated rats than in the sham rats in the Br-1 group. TopoII LI was higher in the irradiated rats than in the sham rats, although not significantly. p27-positive cells decreased in irradiated rats, but p21-positive cells increased more than in the sham rats. The number of apoptotic cells increased significantly after radiation. BrdU LIs were lower in the irradiated rats than in the sham rats in the Br-17 group. A few small BrdU-positive fragments with apoptotic features were phagocytosed in the anterior lobe cells. These results indicate that some "immunohistochemically proliferating cells" subsequently undergo apoptosis in the irradiated pituitary gland. The values of proliferative indices should be cautiously interpreted after irradiation of tissue.