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

A Nomogram for Preoperatively Predicting the Ki-67 Index of a Pituitary Tumor: A Retrospective Cohort Study

Background

The Ki-67 index is an indicator of proliferation and aggressive behavior in pituitary adenomas (PAs). This study aims to develop and validate a predictive nomogram for forecasting Ki-67 index levels preoperatively in PAs.

Methods

A total of 439 patients with PAs underwent PA resection at the Department of Neurosurgery in Jinling Hospital between January 2018 and October 2020; they were enrolled in this retrospective study and were classified randomly into a training cohort (n = 300) and a validation cohort (n = 139). A range of clinical, radiological, and laboratory characteristics were collected. The Ki-67 index was classified into the low Ki-67 index (<3%) and the high Ki-67 index (≥3%). Least absolute shrinkage and selection operator algorithm and uni- and multivariate logistic regression analyses were applied to identify independent risk factors associated with Ki-67. A nomogram was constructed to visualize these risk factors. The receiver operation characteristic curve and calibration curve were computed to evaluate the predictive performance of the nomogram model.

Results

Age, primary-recurrence subtype, maximum dimension, and prolactin were included in the nomogram model. The areas under the curve (AUCs) of the nomogram model were 0.694 in the training cohort and 0.658 in the validation cohort. A well-fitted calibration curve was also generated for the nomogram model. A subgroup analysis revealed stable predictive performance for the nomogram model. A correlation analysis revealed that age (R = −0.23; p < 0.01), maximum dimension (R = 0.17; p < 0.01), and prolactin (R = 0.16; p < 0.01) were all significantly correlated with the Ki-67 index level.

Conclusions

Age, primary-recurrence subtype, maximum dimension, and prolactin are independent predictors for the Ki-67 index level. The current study provides a novel and feasible nomogram, which can further assist neurosurgeons to develop better, more individualized treatment strategies for patients with PAs by predicting the Ki-67 index level preoperatively.

Ki67 in endocrine neoplasms: to count or not to count, this is the question! A systematic review from the English language literature

BACKGROUND

Endocrine neoplasms are generally slow-growing tumors that can show hormonal activity and give metastases. In most cases they are benign and clearly malignant forms are easy to diagnose. However, borderline forms may occur and be, for the pathologists, very difficult to classify. In these cases, there is a strong need to identify factors that may aid. Official classification systems for endocrine neoplasms are based on the evaluation of proliferation and, in most cases, they rely on mitotic count. In support, the study of Ki67 is carried out which, however, has not yet been included in any official classification system, except for neuroendocrine neoplasms of the gastro-entero-pancreatic tract.

PURPOSE

The aim of the present study was to investigate the proven or unproven role of Ki67 in endocrine neoplasms, in different districts, in order to bring to light the substantial differences, in terms of proliferation, existing between neoplasms so similar, but at the same time, so different.

METHODS

A thorough search of English language literature was performed, looking for articles concerning Ki67 in five endocrine neoplasms (pituitary adenomas, thyroid neoplasms, adrenocortical neoplasms, pheochromocytomas and paragangliomas).

RESULTS

From 2170, 236 articles were selected and it was seen that the endocrine neoplasm in which Ki67 was most studied was the pituitary, where it still shows a controversial role. In other neoplasms different roles were identified.

CONCLUSION

The pathologist should be aware of the contribution that this proliferative marker can give to the diagnosis and, sometimes, to the therapy selection, for the clinician.

Frequency and Role of CDKN2A Deletion in High-Risk Pituitary Neuroendocrine Tumors

The underlying mechanisms of aggressive pituitary neuroendocrine tumors (pitNETs) are still unclear. The p16 protein, encoded by the CDKN2A tumor suppressor gene on chromosome 9p21, is commonly reported to be lost in numerous types of cancer. For this reason, this study examined to examine the status of homozygous deletion of CDKN2A in high-risk pitNETs. Thirty-eight high-risk pitNETs (30 male, 8 female) were analyzed for CDKN2A deletion by fluorescent in situ hybridization (FISH). Demographic characteristics such as sex, patient age at operation, and sellar magnetic resonance imaging findings including tumor size and invasion status were recorded. The frequency of CDKN2A homozygous deletion by FISH was 3/38 (7.89%) in the high-risk pitNET group. All of these three cases with CDKN2A homozygous deletion were invasive densely granulated lactotroph tumors (p = 0.000). CDKN2A deletion was not correlated with patient age, sex, cavernous sinus invasion (CSI), and tumor size (p > 0.05). The Ki-67 proliferation index was significantly correlated with CDKN2A homozygous deletion (p = 0.003). The mean Ki-67 proliferation index was 10.7% in pitNETs with CDKN2A homozygous deletion and the Ki-67 proliferation index in the whole study group was 4.1%. CSI was significantly correlated with the morphofunctional tumor types including lactotroph tumor, invasive null cell tumor, and invasive gonadotroph tumor (p = 0.021). These findings suggest a close correlation between inactivation of p16 gene and invasive lactotroph tumors. Further investigations are needed to expand on the mechanism of p16 (CDKN2A) gene deletion in high-risk pitNETs.

Association of ApoE haplotype with clinical evidence of pituitary adenoma

PURPOSE

To evaluate the association of the presence, invasiveness, hormonal activity and recurrence of pituitary adenoma (PA) with ApoE genotypes and alleles.

MATERIALS AND METHODS

Our study group included 142 patients with PA and the control group included 256 healthy individuals. The genotyping of ApoE (rs7412 and rs429358) was performed using a real-time PCR method.

RESULTS

After statistical analysis we found that ApoE genotype E2/E3 was associated with 2.6-fold increased odds of active PA (OR = 2.609; 95%CI: 1.380-4.932; p = 0.003), while the presence of ApoE E3/E3 decreased odds of active PA by 65% (OR = 0.343; 95%CI: 0.205-0.575; p < 0.001). The frequency of the allele ε3 was lesser in the PA group (74.3% vs. 83%, p = 0.003) when compared to controls but it was statistically significantly more frequent in the invasive PA than in the noninvasive PA subgroup (80.4% vs. 65.5%, p = 0.005). The ApoE E2/E4 genotype was more frequent in the noninvasive PA subgroup (10.3% vs. 0%, p = 0.003) than in the invasive PA subgroup. The ApoE E4/E4 genotype was more frequent in the recurrent than in the non-recurrent PA subgroup (6.6% vs. 0%, p = 0.006). No associations between ApoE polymorphisms and Ki-67 labelling index were found.

CONCLUSION

The ApoE E2/E3 genotype is associated with the presence of PA while the ApoE genotype E2/E4 is associated with noninvasive PA development. The allele ε3 could possibly have a protective effect against PA. The genotype E4/E4 is associated with the development of recurrent PA.

Identification of Important Invasion-Related Genes in Non-functional Pituitary Adenomas

Non-functioning pituitary adenomas (NFPAs) are locally invasive with high morbidity. The objective of this study was to diagnose important genes and pathways related to the invasiveness of NFPAs and gain more insights into the underlying molecular mechanisms of NFPAs. The gene expression profiles of GSE51618 were downloaded from the Gene Expression Omnibus database with 4 non-invasive NFPA samples, 3 invasive NFPA samples, and 3 normal pituitary gland samples. Differentially expressed genes (DEGs) are screened between invasive NFPA samples and normal pituitary gland samples, followed by pathway and ontology (GO) enrichment analyses. Subsequently, a protein-protein interaction (PPI) network was constructed and analyzed for these DEGs, and module analysis was performed. In addition, a target gene-miRNA network and target gene-TF (transcription factor) network were analyzed for these DEGs. A total of 879 DEGs were obtained. Among them, 439 genes were upregulated and 440 genes were downregulated. Pathway enrichment analysis indicated that the upregulated genes were significantly enriched in cysteine biosynthesis/homocysteine degradation (trans-sulfuration) and PI3K-Akt signaling pathway, while the downregulated genes were mainly associated with docosahexaenoate biosynthesis III (mammals) and chemokine signaling pathway. GO enrichment analysis indicated that the upregulated genes were significantly enriched in animal organ morphogenesis, extracellular matrix, and hormone activity, while the downregulated genes were mainly associated with leukocyte chemotaxis, dendrites, and RAGE receptor binding. Subsequently, ESR1, SOX2, TTN, GFAP, WIF1, TTR, XIST, SPAG5, PPBP, AR, IL1R2, and HIST1H1C were diagnosed as the top hub genes in the upregulated and downregulated PPI networks and modules. In addition, HS3ST1, GPC4, CCND2, and SCD were diagnosed as the top hub genes in the upregulated and downregulated target gene-miRNA networks, while CISH, ISLR, UBE2E3, and CCNG2 were diagnosed as the top hub genes in the upregulated and downregulated target gene-TF networks. The new important DEGs and pathways diagnosed in this study may serve key roles in the invasiveness of NFPAs and indicate more molecular targets for the treatment of NFPAs.

The Prognostic Roles of the Ki-67 Proliferation Index, P53 Expression, Mitotic Index, and Radiological Tumor Invasion in Pituitary Adenomas

The fourth edition of the World Health Organization (WHO) classification of pituitary tumors recommended evaluation of tumor proliferation and invasion to identify aggressiveness. We aimed to assess the prognostic roles of the Ki-67 proliferation index, mitotic index, P53 expression, and cavernous sinus invasion in pituitary adenomas (PAs). Among the 601 patients who underwent transnasal/transsphenoidal adenomectomy from 2001 to 2016, 101 patients (16.8%) who had tumors with a high (≥ 3%) Ki-67 index (group A) and a control group consisting of 43 patients with a low (< 3%) Ki 67 index who were matched for age, gender, and tumor type were included. Mitotic index and P53 expressions were evaluated. Patient characteristics, histopathology reports, pre/postoperative magnetic resonance imaging (MRI), and follow-up data were assessed retrospectively. The frequency of macroadenomas and mean tumor size were greater in group A when compared to group B (67.4 vs. 94.1%, p< 0.01 and 25 ± 10.6 vs. 18 ± 11 mm, p< 0.01, respectively). Invasion to cavernous sinus was found in 53 (36.8%) patients and was more frequent in group A (p<0.01). The mean number of surgery was higher in group A than group B (p< 0.05). The mean follow-up period was 46.6 ± 34 months. The postoperative MRIs and follow-up data for at least 24 months were available in 117 patients. Recurrence risk was higher in group A than group B (p = 0.03). Tumors with high Ki-67 proliferation index were grouped as 3-5, 6-10, 11-15, and > 15%. The risk of recurrence was not different between groups of high Ki-67 index. The optimal cutoff point of the Ki-67 proliferation index that predicted recurrence was 2.5% with 84.6% sensitivity and 47.4% specificity. The cavernous sinus invasion on MRI was associated with recurrence (p = 0.03). Tumor size and recurrence risk were not associated with P53 expression. High P53 expression was related with cavernous sinus invasion (p = 0.03). The mitotic index was not associated with recurrence risk and tumor invasion. Recurrence risk was higher in tumors with ≥ 2 histopathological atypia criteria (p = 0.01). High Ki-67 index with a 2.5% cutoff point and cavernous sinus invasion on MRI are reliable markers for predicting recurrence in PAs. Recurrence risk is also higher in tumors with two histopathological aggressiveness criteria. Strict follow-up and more aggressive treatment approaches may be necessary for invasive-proliferative PAs.

Evaluation of the potential of the Ki67 index to predict tumor evolution in patients with pituitary adenoma

The aggressive course of a number of pituitary adenomas requires the investigation of potential predictors. This study aimed to investigate the proliferation marker Ki67 as a predictor of postoperative outcome in patients with pituitary adenoma regarding recurrence and regrowth of the tumor, using a Ki67 cut-off value of 3%. This retrospective study included 52 patients with pituitary adenoma who had undergone adenomectomy and had a pituitary image taken at least 1 year after surgery. Patients were divided according to Ki67 expression into high (≥3%) vs. low (<3%) levels of Ki67. The two groups were similar regarding the preoperative tumor invasion grade. The Ki67 index ranged from 0 to 30%; in 23 cases, Ki67 was ≥3%. The two groups were similar regarding tumor recurrence and regrowth: 4 cases (28%) of recurrence in the Ki67<3% group vs. none in the Ki67≥3% group (P=0.26); and 2 cases (13%) of regrowth in the Ki67<3% group vs. 7 cases (43%) in the Ki67≥3% group (P=0.11). A subgroup analysis was performed for nonfunctioning adenomas. Recurrence rates remained similar between groups (Ki67<3% group: 1 case [20%]; Ki67≥3% group: none; P>0.99), whereas regrowth rates were higher in the Ki67≥3% group (6 cases [67%] vs. 2 cases [17%] in the Ki67<3% group; P=0.03). The patient with the highest Ki67 index (30%) developed pituitary carcinoma. The results allow us to suggest the adoption of a stricter control of image monitoring in nonfunctioning adenomas with incomplete resection associated with a Ki67 index ≥3%.

Association of Ki-67 Labelling Index and IL-17A with Pituitary Adenoma

The aim of the present study was to determine if the Ki-67 labelling index reflects invasiveness of pituitary adenoma and to evaluate IL-17A concentration in blood serum of pituitary adenoma patients. The study was conducted in the Hospital of Lithuanian University of Health Sciences. All pituitary adenomas were analysed based on magnetic resonance imaging findings. The suprasellar extension and sphenoid sinus invasion by pituitary adenoma were classified according to Hardy classification modified by Wilson. Knosp classification system was used to quantify the invasion of the cavernous sinus. The Ki-67 labelling index was obtained by immunohistochemical analysis with the monoclonal antibody, and serum levels of IL-17A were determined by enzyme-linked immunosorbent assay (ELISA). Sixty-nine PA tissue samples were investigated. Serum levels of IL–17A were determined in 60 patients with PA and 64 control subjects. Analysis revealed statistically significantly higher Ki-67 labelling index in invasive compared to noninvasive pituitary adenomas. Median serum IL-17A level was higher in the pituitary adenoma patients than in the control group. Conclusion. IL-17A might be a significant marker for patients with pituitary adenoma and Ki-67 labelling index in case of invasive pituitary adenomas.

Analysis of Ki67, HMGA1, MDM2, and RB expression in nonfunctioning pituitary adenomas

Nonfunctioning pituitary adenomas (NFPAs) are the most prevalent type of pituitary macro-adenoma. Clarifying the relationship between NFPA markers and disease progression or recurrence could provide a basis for administration of adjuvant treatments. The present study examined the expression levels of high-mobility group (HMG)A1, Ki-67, mouse double minute 2 homolog (MDM2), and retinoblastoma (RB)with respect to NFPA recurrence. Immunohistochemistry was carried out using antibodies to Ki-67, MDM2, HMGA-1, and RB on tissue microarray slides of a cohort of 35 paired NFPA samples of primary and recurrence/regrowth tumors. Based on postoperative magnetic resonance imaging data, tumors were classified as recurrence (n = 20) included primary and recurrent tumors or regrowth (n = 15) included primary and regrowth tumors, which are paired. Protein expression was classified as negative or positive according to the H-score method and was analyzed with respect to clinical and pathological findings. MDM2-positive cases accounted for11/20 primary and 19/20 s recurrent tumors (χ² = 8.533, P = 0.003), and 9/15 primary tumors and 15/15 s regrowth tumors (χ² = 7.5, P = 0.006). MGA1-positive cases represented 9/20 primary tumors and 16/20 s recurrent tumors (χ² = 5.227, P = 0.022), and 4/15 primary tumors and 12/15 s regrowth tumors (χ² = 8.571, P = 0.003). There was no statistically significant difference in Ki-67 expression between primary and second recurrent/regrowth tumors although theKi67 labeling index was higher in the latter groups. RB was highly expressed in all groups with no significant difference between them. HMGA1 and MDM2 were more highly expressed in recurrence/regrowth cases of NFPA than in primary NFPA. HMGA1 and MDM2 are biomarkers and potential drug targets for NFPA treatment.

Clinical Impact of the Current WHO Classification of Pituitary Adenomas

WHO classifications should be used for comparing the results from different groups of pathologist and clinicians by standardized histopathological methods. Our present report describes the important parameters of pituitary adenoma pathology as demand of the WHO classification for correlation to endocrine data and prognosis. The combination of HE stain based structures with immunostainings for pituitary hormones allows subclassification of adenomas as the best method not only for correlations to clinical hyperfunctions but also for statements to the sensitivity of drug therapies (somatostatin analogs, dopamine agonists). GH-, PRL- and ACTH-secreting pituitary adenomas are further classified based on the size and number of their secretory granules by electron microscopy, or as is mostly the case nowadays by cytokeratin staining pattern, into densely and sparsely granulated. Granulation pattern may be considered for the prediction of treatment response in patients with GH-secreting adenomas, since the sparsely granulated subtype was shown to be less responsive to somatostatin analog treatment. For prognosis, it is important to identify aggressive adenomas by measurements of the Ki-67 index, of the number of mitoses, and of nuclear expression of p53. Among the criteria for atypical adenomas, high Ki-67 labeling index and invasive character are the most important adverse prognostic factors. Promising molecular markers have been identified that might supplement the currently used proliferation parameters. For defining atypical adenomas in a future histopathological classification system, we propose to provide the proliferative potential and the invasive character separately.

Factors influencing improvement of visual field after trans-sphenoidal resection of pituitary macroadenomas: a retrospective cohort study

AIM

To investigate the influencing factors of visual field improvement after trans-sphenoidal resection of pituitary macroadenomas.

METHODS

This retrospective cohort study included 201 patients (366 eyes) with visual field defect induced by pituitary macroadenomas. All of them were treated with trans-sphenoidal surgery. Ophthalmologic evaluation, best-corrected visual acuity (BCVA), and visual field examination were performed before and 3mo after surgery. BCVA, visual field defect index mean deviation (MD), duration of symptoms, age, sex, and volume of tumors were compared. Expression of vascular endothelial growth factor (VEGF) and Ki-67 of tumor tissue were detected by immunohistochemical technique.

RESULTS

The mean age of patients was 44.23±1.29y. Ninety-three patients were female and 108 were male. The mean tumor volume was 14.36±6.23 cm(3). The mean duration of preoperative symptoms was 11.50±0.88mo. Mean preoperative MD was -17.50±0.82 dB. Mean Preoperative visual acuity was 0.64±0.04. Postoperative visual field improved in 270 (73.77%) eyes, unchanged in 96 (26.23%) eyes. Multivariate logistic regression displayed that the factors independently influencing visual field improvement were young age (OR=1.71, 95%CI: 1.325-2.387, P=0.013), low preoperative MD absolute value (OR=1.277, 95%CI: 1.205-1.355, P<0.001), small volume of tumor (OR=1.458, 95%CI: 1.060-4.289, P<0.001), low expression of VEGF in tumor tissue (OR=1.554, 95%CI: 1.089-2.457, P=0.022), and low expression of Ki-67 in tumor tissue (OR=1.552, 95%CI: 1.161-2.847, P=0.026).

CONCLUSION

After pituitary macroadenomas trans-sphenoidal resection, the independent influencing factors of the visual fields recovery were low preoperative MD absolute value, young age, small volume of tumor, and expression levels of VEGF/ Ki-67.

Clinicopathological correlates of extrasellar growth patterns in pituitary adenomas

We reviewed clinical, imaging and histopathology details of 297 patients who underwent surgery for pituitary adenomas, with an equal distribution of functional and non-functioning tumors, to examine clinicopathological correlates of extrasellar growth. Knosp grades of 3 and 4 on MRI defined cavernous sinus invasion, Hardy grades of C and D defined significant suprasellar/subfrontal extension, and intraoperative evidence of tumor eroding through the clivus or sellar floor defined infrasellar invasion. Disease status at follow-up was known in 246 patients overall, including 35 patients who were evaluated for progression of residual disease on serial imaging. On univariate analysis, we found several statistically significant associations (p < 0.05) including adenoma size with age, sex and tumor protein p53 reactivity; cavernous sinus invasion with size, non-functional status, increased mitotic activity, an elevated MIB-1 proliferation index and p53 reactivity; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with age and tumor size. When adjusting for confounders with logistic regression, several significant associations were evident including adenoma size with male sex and p53 reactivity; cavernous sinus invasion with size and elevated MIB-1 proliferation index; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with adenoma size alone. Patients with early progression of postoperative residual tumor were younger with a non-significant trend towards higher MIB-1 proliferation indices. Individual patterns of extrasellar growth in pituitary adenomas are associated with unique clinical and immunohistochemical profiles. Younger patients with elevated MIB-1 values are probably at high risk for early recurrence of non-functioning tumors. Definitions of atypia must be standardized before more robust assumptions about tumor biology can be established.

Evaluation of prognostic utility of MIB-1 and p53 expression in pituitary adenomas: correlations with clinical behaviour and follow-up results

Pituitary adenomas (PAs) show a broad clinicomorphological spectrum. The proliferation activity, evaluated by MIB-1 labelling index (LI), and p53 expression have been pointed as predictive markers for invasiveness and progression. The aim of this study was to evaluate the proliferation rate and p53 expression and to look for any relationships with the clinical behaviour and follow-up results in a series of Bulgarian patients with PAs. A total of 93 patients with PAs (81 hormone-secreting, 12 non-functioning), who were operated on and followed up for a period of five years, were included. The MIB-1 LI and p53 expressions were determined by immunohistochemistry and correlated with various clinical and tumour variables. The whole group of PAs showed a low proliferation rate with evident variations in a small number of cases (MIB-1 LI – 0.50 ± 0.56, from 0.1 to 3.30). MIB-1 LI correlated with tumour size (p = 0.012) and was positively related with male gender (p = 0.23) and partial surgical resection (p = 0.036). We found no significant differences regarding the age, functional activity, invasion (n = 33), expansion (n = 37) and tumour recurrences (seven cases). Only 10 cases (10.8%) showed a focal, nuclear p53 immunoreactivity. The p53 positive tumours had higher proliferation rate (p = 0.0001) but no relationship with the other clinical and tumour variables. Among all cases, there was only one case with higher MIB-1 LI (3.3%), positive p53 expression and tumour recurrence after surgery. Our results show that most PAs have a low proliferation rate and lack of p53 expression, as well as no relationship with tumour invasion or postsurgical progression.

Radically resected pituitary adenomas: prognostic role of Ki 67 labeling index in a monocentric retrospective series and literature review

Ki-67 Labeling Index is an immunocytochemical marker of cell proliferation. The correlation of Ki-67 expression with pituitary adenomas recurrence has been investigated and is highly debated. Aim of this study was to evaluate whether Ki-67 correlates with recurrence even in patients with an apparently completely removed pituitary adenoma. We retrospectively reviewed the database of the Hypothalamic-Pituitary Disease Unit at the Catholic University of Rome, collected between 2003 and 2011. Inclusion criteria were: patients who underwent surgery at the Department of Neurosurgery with an apparently complete removal of a pituitary adenoma; Ki-67 histological evaluation by the same operator and values of <3%. All patients underwent endocrine evaluation of the hypothalamic-pituitary function, ophthalmologic and neuro-radiological examinations, during the preoperative period and follow-up. Out of 490 patients recorded on the database of the Hypothalamic-Pituitary Disease Unit at the Catholic University of Rome, 191 cases met the inclusion criteria. Recurrence was observed in 49 cases (25.7% of the patients who had undergone radical excision). Optional cut-off value was identified at Ki-67 values of 1.50%. This was associated with worse disease-free survival time, even after correction for age at treatment, gender, positivity to p53, functional classification and Knosp grading. Ki-67 labeling index may be useful in postoperative management, even in patients who underwent radical PA removal. We suggest a Ki-67 cut-off value of 1.5% to plan an adequate clinical follow-up.

Nonfunctioning pituitary adenomas: association of Ki-67 and HMGA-1 labeling indices with residual tumor growth

BACKGROUND

The postoperative biological behavior of nonfunctioning pituitary adenomas (NFPAs) is variable. Some residual NFPAs are stable long-term, others grow, and some recur despite complete removal. The usual histological markers of tumor aggressiveness are often similar between recurring, regrowing, and stable tumors, and therefore are not reliable as prognostic parameters. In this study, the clinical utility of proliferation indices (labeling index, Li) based on immunohistochemistry targeted at antigens Ki-67 and High-mobility group A1 (HMGA-1) for prediction of NFPA prognosis was investigated.

METHODS

Fifty patients with NFPAs were investigated. In each patient, Ki-67 and HMGA-1 Li were evaluated. Based on postoperative magnetic resonance images, patients were classified as tumor-free (18 patients), or harboring a residual tumor (32 patients). The latter group was further subdivided into groups with stable tumor remnants (11 patients) or progressive tumor remnants (21 patients).

RESULTS

The median follow-up period was 8 years. No significant relationship between HMGA-1 Li and residual tumor growth was found. Growing residual tumors showed a trend towards higher Ki-67 Li compared with stable ones (p = 0.104). All tumor remnants with Ki-67 Li above 2.2% were growing. The relationship between residual tumor growth and Ki-67 Li exceeding the cutoff value of 2.2% was significant (p = 0.01 in univariate, p = 0.044 in multivariate analysis).

CONCLUSIONS

The prognostic significance of the HMGA-1 antigen was not confirmed. In contrast, the Ki-67 Li provides useful and valuable information for the postoperative management of NFPAs. In residual adenomas with a Ki-67 Li above 2.2%, regrowth should be expected, and these tumors may require shorter intervals of follow-up magnetic resonance imaging (MRI) and/or early adjuvant therapy. Future larger studies are needed to confirm the results of this study.

Transcription factor Ets1 cooperates with estrogen receptor α to stimulate estradiol-dependent growth in breast cancer cells and tumors

The purpose of this study was to explore the role of transcription factor Ets1 in estrogen receptor α (ERα)-positive breast cancer progression. We expressed human Ets1 or empty vector in four human ERα-positive breast cancer cell lines and observed increased colony formation. Further examination of cellular responses in stable Ets1-expressing MCF7 clones displayed increased proliferation, migration, and invasion. Ets1-expressing MCF7 tumors grown in the mammary fat pads of nude mice exhibited increased rates of tumor growth (7.36±2.47 mm(3)/day) compared to control MCF7 tumors (2.52±1.70 mm(3)/day), but maintained their dependence on estradiol for tumor growth. Proliferation marker Ki-67 staining was not different between control and Ets1-expressing tumors, but Ets1-expressing tumors exhibited large necrotic centers and elevated apoptotic staining. Ets1 was shown to cooperate with ERα and the p160 nuclear receptor coactivator (NCOA/SRC) family to increase activation of a consensus estrogen response element luciferase reporter construct. Ets1-expressing MCF7 cells also exhibited elevated expression of the ERα target genes, progesterone receptor and trefoil factor 1. Using GST-pulldown assays, Ets1 formed stable complexes containing both ERα and p160 nuclear receptor coactivators. Taken together, these data suggest that the Ets1-dependent estradiol sensitization of breast cancer cells and tumors may be partially due to the ability of Ets1 to cooperate with ERα and nuclear receptor coactivators to stimulate transcriptional activity of estrogen-dependent genes.

Correlation between histological subtypes and MRI findings in clinically nonfunctioning pituitary adenomas

Clinically nonfunctioning pituitary adenomas (CNFPAs) consist of several histological subtypes, including null cell adenoma (NCA), silent gonadotroph cell adenoma (SGA), silent corticotroph adenoma (SCA), and other silent adenomas (OSA) (i.e., GH, TSH, and prolactin adenomas). To detect possible correlations between MRI findings and the subtypes, we retrospectively studied 390 consecutive patients with CNFPA who underwent surgery between 2008 and 2010. They were classified into three groups: NCA/SGA (313 cases), SCA (39 cases), and OSA (36 cases); in addition there were two unusual cases of plurihormonal adenoma. Three MRI findings were less common in NCA/SGA than in the other groups (P < 0.0001): giant adenoma (>40 mm), marked cavernous sinus invasion (Knosp grade 4), and lobulated configuration of the suprasellar tumor. When these MRI findings were negative in patients older than 40 years old, 91.0% (212/233) were NCA/SGA. These MRI findings were frequently noted despite a low MIB-1 index in SCA. OSA showed a high MIB-1 index and a preponderance in younger patients. In conclusion, although SCA and OSA consisted of only 20% of CNFPAs, their frequency significantly increased when the tumor was large, invasive, and lobulated, and the patient was younger than 40 years old.

Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas

Pituitary-dependent hyperadrenocorticism (PDH) caused by pituitary corticotroph adenoma is a common endocrine disorder in dogs. The ratio between pituitary height and the area of the brain (P/B) has been used to evaluate the pituitary size. A P/B ratio > 0.31 indicates an enlarged pituitary, whereas a P/B ratio ≤ 0.31 indicates a nonenlarged pituitary. The aim of this study was to investigate the expression of proliferation markers Ki-67 and minichromosome maintenance-7 (MCM7) in canine corticotroph adenomas in enlarged and in nonenlarged pituitaries and to evaluate their relation with the size of canine pituitary corticotroph adenomas. Ki-67 and MCM7 expression in ACTH-positive tumor cells was determined by dual-labeling immunohistochemistry in resected corticotroph adenomas from 15 dogs with PDH. The mean ± SD Ki-67 labeling index (LI) was 0.55% ± 0.59% in corticotroph adenomas with nonenlarged pituitaries and 1.6% ± 0.6% in adenomas with enlarged pituitaries. The MCM7 LI in corticotroph adenomas with nonenlarged pituitaries and in adenomas with enlarged pituitaries was 2.9% ± 2.2% and 10.9% ± 3.7%, respectively. The Ki-67 LI and MCM7 LI were significantly greater in the adenomas with enlarged pituitaries than in the adenomas with nonenlarged pituitaries (P < 0.01 and P < 0.01, respectively). The MCM7 LI was significantly greater than the Ki-67 LI in adenomas (P < 0.01). The Ki-67 LI was positively correlated with the MCM7 LI (r = 0.820, P < 0.01), and the P/B ratio was positively correlated with the Ki-67 LI (r = 0.560, P = 0.03) and the MCM7 LI (r = 0.854, P < 0.01). In conclusion, canine corticotroph adenomas in enlarged pituitaries show greater proliferation potential than do adenomas in nonenlarged pituitaries. MCM7 expression was significantly greater than Ki-67 expression in canine pituitary corticotroph adenomas. Thus, MCM7 may be superior to Ki-67 as a proliferation marker in pituitary tumors.

The clinical significance of MIB-1 labeling index in pituitary adenomas

Pituitary adenomas are unique in several ways--they are rarely malignant and yet can be invasive of several compartments. Recurrences in tumors with bland histological features that have been radically excised are a reason for frustration faced by endocrinologists and neurosurgeons in treatment of pituitary adenomas. Several attempts have therefore been made to determine the growth potential of pituitary adenomas. The aim of the present study was to define the biological significance of the MIB-1 labelling index (MIB-1 LI) in pituitary adenomas. The study included 159 cases of surgically treated pituitary adenoma seen in a single institution. MIB-1 LI was not found to be related to age or gender. The mean MIB-1 LI for clinically functional adenomas was marginally higher than that for clinically non-functional adenomas. There was a significant difference in the MIB-1 LI for tumors with a maximum diameter of more than 4 cm at a MIB-1 LI of ≥2%, however this difference was not statistically significant at a higher MIB-1 LI cut off value of >3%. The mean MIB-1 LI was significantly higher in tumors causing hydrocephalus and in those with cavernous sinus invasion and not when invasion was defined as invasion by tumor in any direction. We conclude that large pituitary macroadenomas, tumors filling the third ventricle causing hydrocephalus and tumors with true cavernous sinus invasions are more likely to have a higher proliferation index. Close follow up of tumors showing these imaging features would be recommended.

Pituitary carcinoma diagnosed on fine needle aspiration: Report of a case and review of pathogenesis

Pituitary carcinoma (PC) is a very rare entity (0.2% of all pituitary tumors), with only about 140 cases reported in English literature. There are no reliable histological, immunohistochemical or ultrastructural features distinguishing pituitary adenoma (PA) from PC. By definition, a diagnosis of PC is made after a patient with PA develops non-contiguous central nervous system (CNS) or systemic metastases. To date, only three cases of PC have been reportedly diagnosed on fine needle aspiration (FNA). Two of the reported cases were diagnosed on FNA of the cervical lymph nodes and one on FNA of the vertebral bone lesion. Herein, we present a case of PC, diagnosed on FNA of the liver lesion. In this case, we describe cytologic features of PC and compare them to histologic features of the tumor in the pituitary. Clinical behavior of tumor, pathogenesis of metastasis and immunochemical and prognostic markers will also be described.

MIB-1 labeling index correlated with magnetic resonance imaging detected tumor volume doubling time in pituitary adenoma

OBJECTIVE

The purpose of this study was to evaluate whether MIB-1 labeling index (LI) could be used to predict growth velocity of residual pituitary adenomas after surgery.

MATERIALS AND METHODS

One hundred and sixty pituitary adenomas which had not received other treatment modality except for surgery were collected. Each of them had at least two post-operative magnetic resonance imaging (MRI) studies with an interval of at least 1 month apart. Tumor volume doubling time (TVDT) was calculated for those in which volume increased.

RESULTS

Post-operative tumor progression was noted in 54 (33.8%) cases, of which 39 (72.2%) cases were non-functioning adenomas. The MIB-1 LIs of the functioning and non-functioning adenomas were not significantly different. The median TVDT of these 54 cases was 34.6 months. The mean and median MIB-1 LI were 2.7 and 1.1 respectively (range 0.4-20.6). The MIB-1 LI was significantly correlated with log(2)(TVDT) (r=-0.363, P=0.007); when LI was <0.8, the TVDT of 90.5% cases was >or= 2 years.

CONCLUSIONS

Only one-third of the pituitary adenomas progressed after surgery, and their MIB-1 LIs were generally low. The MIB-1 LI was significantly correlated with the MRI detected TVDT of post-operative residual pituitary adenomas.

Labeling index in pituitary adenomas evaluated by means of MIB-1: is there a prognostic role? A critical review

OBJECTIVE

The present article presents an overview of the literature, and analyses the methods and the primary questions related to assessment of proliferation index using the Ki-67/MIB-1 labeling index in pituitary adenomas. Although atypical adenomas are characterized by their atypical morphological features by an elevated mitotic index, a Ki-67 (MIB-1) labeling index greater than 3% and extensive nuclear staining for p53, use of the proliferation index (LI) of pituitary adenomas in assessing the degree of tumor aggressiveness is a controversial topic in the literature, and there are disparate results involving many studies.

METHODS

A review of literature was carried out to correlate the role of Ki-67 LI and its correlation with clinical findings, tumor size, invasiveness, recurrence, adenoma subtype, adenoma doubling time, and pituitary carcinomas is addressed.

RESULTS

The prognosis cannot be predicted on the basis of the Ki-67 LI alone. Although there is no direct relation between Ki-67 LI and some of these variables and controversial data were found regarding some topics, our review justify the use of Ki-67 in the analysis of pituitary adenomas as an additional information for clinical decision.

CONCLUSION

Although assessment of proliferative may be helpful in predicting subsequent tumor recurrence or invasiveness, there are many other important and as yet unidentified factors pituitary tumors. It is clear that further research is needed to clarify these molecular mechanisms to predict those with a potentially poor clinical outcome.

Expression of Ki-67, PCNA, and p27kip1 in canine pituitary corticotroph adenomas

Pituitary-dependent hypercortisolism (PDH), which is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas, is a common endocrinopathy in dogs. Dogs with non-enlarged pituitaries harboring a microadenoma have a better prognosis than those with enlarged pituitaries. The aim of this study was to investigate the expression of the proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA) and the cell-cycle inhibitor p27kip1 in corticotroph adenomas in enlarged and non-enlarged pituitaries. The expression of Ki-67, PCNA, and p27kip1 was analyzed by immunohistochemical staining of 17 pituitary adenoma samples harvested during pituitary surgery in dogs with PDH. The labeling index was calculated by counting the number of immunopositive cells per 1,000 cells. The mean (+/- standard deviation) labeling index for Ki-67 was 8.4%+/-14.2% for the group with enlarged pituitaries, and 8.8%+/-5.5% for the group with non-enlarged pituitaries; that for PCNA was 35.5%+/-12.2% and 37.0%+/-15.5%; and that for p27kip1 was 29.3%+/-22.6% and 42.5%+/-27.9%, respectively. No significant differences in Ki-67, PCNA, and p27kip1 labeling indices were found between enlarged and non-enlarged pituitaries. However, a trend toward significance was observed when comparing the expression of p27kip1 in enlarged pituitaries versus normal pituitary tissue. It is concluded that Ki-67 and PCNA are not useful as proliferative markers for studying the pathobiology of pituitary corticotroph adenomas in dogs.

Determination of cell proliferation using Mcm2 antigen and evaluation of apoptosis and TGF-beta1 expression in GH-secreting or clinically nonfunctioning pituitary adenomas

Pituitary adenomas (PA) occasionally show aggressive behavior, with invasion of the surrounding tissues. The identification of markers able to recognize aggressive PA in early stages remains a challenge. We aimed to determine the expression of a new cell proliferation marker, Mcm2, and the presence of apoptosis in PA, and to evaluate the association of clinicopathological features with the apoptotic and proliferative indices. Additionally, the TGF-beta1 expression, an inducer of apoptosis, was determined. The proliferative index was determined in GH-secreting or clinically nonfunctioning PA using immunohistochemical (IH) methods for Mcm2 and Ki-67 antigens. The apoptosis was assessed by the TUNEL method and the TGF-beta1 expression by IH. A significant positive correlation was found between log Mcm2 index and log Ki-67 index (p < 0.001). Mcm2 and Ki-67 detected a similar number of proliferating cells. Mcm2 index showed a significant association with tumor extension (p = 0.02), but not with tumor invasion. Apoptosis was detected in 17% of the adenomas, with a maximum apoptotic index of 0.77%. Immunoreactivity to TGF-beta1 was observed in 77% of the adenomas, showing an association with tumor extension. We concluded that, in this sample, Mcm2 was similar to Ki-67 in the identification of the proliferating cells and that apoptosis was rare.

RNAi-mediated knockdown of AURKB and EGFR shows enhanced therapeutic efficacy in prostate tumor regression

Aurora B kinase (AURKB) and epidermal growth factor receptor 1 (EGFR) belong to serine/threonine and tyrosine kinase family of proteins. Both these kinases are found to overexpress in a large number of epithelial cancers, including hormonal refractory prostate cancer. In this communication, we present evidence for down-regulated expression of AURKB and EGFR, either alone or in combination, in prostate cancer cells. The results show that AURKB and EGFR were efficiently down-regulated in a dose-dependent manner. AURKB and EGFR siRNA in combination have shown enhanced therapeutic effect by inhibiting PC3 cell proliferation and inducing apoptosis in vitro, whereas androgen-dependent cancer cells LNCaP remain unaffected correlating the endogenous expression levels. Knockdown of AURKB and EGFR individually resulted in inhibition of prostate tumor growth in athymic nude mice and their combined knockdown resulted in tumor regression in which 40% of the treated mice were found to be tumor free, implicating the potential therapeutic benefits of AURKB-EGFR combination therapy.

Ki-67 in pituitary neoplasms: a review--part I

KI-67, A MARKER of cellular proliferation, has been studied extensively in pituitary neoplasia. It is of relevance to various clinicopathological parameters, including tumor subtype, size, invasiveness, and recurrence, as well as patient age and sex. Generally, pituitary tumors behaving aggressively have increased Ki-67 labeling indices. Nonetheless, there is considerable overlap in Ki-67 labeling between noninvasive and invasive adenomas as well as between adenomas and pituitary carcinomas. Not only is there no general agreement regarding the relationship of Ki-67 labeling index and tumor invasiveness, but the same is also true of the association with pituitary tumor size, growth fraction, and recurrence. Whereas a number of studies found conclusive associations of Ki-67 labeling indices with aggressive behavior, size, and/or adenoma subtype, others fail to do so. It is evident that discrepant data regarding tumor behavior in part has its basis in nonuniform study criteria. For example, different investigators use varying criteria of tumor invasion and recurrence. Herein, we review the literature relating Ki-67 expression and various other clinicopathological parameters and conclude that uniform definitions and methods, as well as new markers, are key to improved treatment of pituitary tumors.

Residual nonfunctioning pituitary adenomas: prognostic value of MIB-1 labeling index for tumor progression

Object

In residual nonfunctioning pituitary adenomas, reliable prognostic parameters indicating probability of tumor progression are needed. The Ki 67 expression/MIB-1 labeling index (LI) is considered to be a promising candidate factor. The aim in the present study was to analyze the clinical usefulness of MIB-1 LI for prognosis of tumor progression.

Methods

The authors studied a cohort of 92 patients with nonfunctioning pituitary adenomas. Based on sequential postoperative MR images, patients were classified as tumor free (51 patients) or as harboring residual tumor (41 individuals). The residual tumor group was further subdivided in groups with stable residual tumors (14 patients) or progressive residual tumors (27 patients). The MIB-1 LI was assessed in tumor specimens obtained in all patients, and statistical comparisons of MIB-1 LI of the various subgroups were performed.

Results

. The authors found no significant difference of MIB-1 LI in the residual tumor group compared with the tumor-free group. However, MIB-1 LI was significantly higher in the progressive residual tumor group, compared with the stable residual tumor group. Additionally, the time period to second surgery was significantly shorter in residual adenomas showing an MIB-1 LI > 3%.

Conclusions

The data indicate that MIB-1 LI in nonfunctioning pituitary adenomas is a clinically useful prognostic parameter indicating probability of progression of postoperative tumor remnants. The MIB-1 LI may be helpful in decisions of postoperative disease management (for example, frequency of radiographic intervals, planning for reoperation, radiotherapy, and/or radiosurgery).

Prognostic significance of the Ki-67 labeling index in growth hormone-secreting pituitary adenomas

CONTEXT

Ki-67 is a marker of proliferation activity associated with invasiveness and prognosis in human tumors.

OBJECTIVE

The aim of the study was to evaluate the Ki-67 index prognostic relevance in a group of acromegalic patients who underwent transsphenoidal surgery for a GH-secreting pituitary adenoma.

MATERIAL AND METHODS

We selected 68 consecutive acromegalic patients referred to our hospital during a 5-yr period. The Ki-67 index was determined by immunohistochemistry on tissue samples obtained from each adenoma after surgery. Those patients who were not completely cured after surgery began medical therapy with somatostatin analogs (SSAs). Periodical pituitary magnetic resonance imaging and hormonal evaluation were performed during the follow-up.

RESULTS

Twenty-eight of 68 patients were cured after surgery (41%). Among the 40 patients treated with SSAs, 13 were considered uncontrolled. Pituitary magnetic resonance imaging showed residual/recurrent disease in 25 of 68 patients after 6 months. No correlation was found between Ki-67 index and age, tumor size, GH, or IGF-I plasma levels. Tumors described as having cavernous sinus invasion had a higher mean Ki-67 index as compared with noninvasive tumors (P < 0.01). The Ki-67 index was significantly lower in tumors in patients cured after surgery as compared with patients considered not cured (P < 0.01) and in tumors in patients controlled by SSA therapy as compared with patients considered as uncontrolled (P < 0.05).

CONCLUSION

The Ki-67 labeling index may predict clinical outcome in postsurgical management of acromegalic patients. We suggest routine Ki-67 evaluation in GH-secreting pituitary adenomas.

Thiazolidinediones inhibit the growth of PC12 cells both in vitro and in vivo

Thiazolidinediones (TZDs) have recently been proposed as a therapy for PPARgamma-expressing tumors. Pheochromocytoma (PHEO) is associated with high morbidity and mortality due to excess catecholamine production, and few effective drug therapies currently exist. We investigated the effects of TZDs on PHEO both in vitro and in vivo. PPARgamma protein was expressed in human adrenal PHEO tissues as well as in rat PHEO cells, PC12. TZDs, including rosiglitazone (RGZ) and pioglitazone (PGZ), inhibited proliferation of PC12 cells in a dose-dependent manner and increased casapse-3 expression of PC12 cells. TZDs also reduced expression of cyclin E and cyclin-dependent kinase2. RGZ inhibited nerve growth factor-induced neurite outgrowth and reduced expression of catecholamine-synthesizing enzymes. Finally, rat PHEO growth generated by subcutaneous injection of PC12 cells was slowed in an RGZ-treated mouse. These data suggest that TZDs may be a promising therapeutic approach for medical treatment for PHEO.

A study of the correlation between morphological findings and biological activities in clinically nonfunctioning pituitary adenomas

OBJECTIVE

The aims of this study are to review the histology of the clinically nonfunctioning pituitary adenomas (CNFPAs) we have observed and to determine whether or not the frequency of cavernous sinus invasion is different among each type of morphology.

METHODS

In addition, several proliferative markers, including Ki67, p53, E-cadherin, matrix metallo-proteinase 9 and pituitary tumor derived fibroblast growth factor receptor 4 (ptd-FGFR4), were also investigated in invasive and non-invasive tumors.

RESULTS

Our consequent 213 CNFPAs were diagnosed as follows: 64% were silent gonadotroph adenomas, 18% were null cell adenomas, 12% were silent corticotroph adenomas, 4% were silent Subtype 3 adenomas, and 1% were other types of adenomas. Female patients or younger patients showed a significant preponderance in silent corticotroph adenomas and in silent Subtype 3 adenomas, respectively. Cavernous sinus invasion occurs most frequently in silent corticotroph adenomas (85%) followed by Subtype 3 adenomas (67%), null cell adenomas (38%), and silent gonadotroph adenomas (11%). There were no significant differences in the Ki67, p53, E-cadherin, matrix metallo-proteinase 9, and ptd-FGFR4 expression between tumors with and without cavernous sinus invasion.

CONCLUSION

From a clinical standpoint, it is quite important to differentiate morphological type in CNFPAs to aid the clinician in assessing the clinical behavior and prognosis of the tumor. Therefore, we suggest that all CNFPAs be examined not only by conventional light microscopy but also by immunohistochemistry, preferably by electron microscopy, to achieve a correct morphological diagnosis.

Ultrastructural and immunohistochemical characteristics of developing human pituitary gland

The development and differentiation of the human pituitary gland and its relationship to other structures of the head were analysed in nine human embryos and fetuses aged 5-10 weeks old using morphological and immunohistochemical methods. In the 5th developmental week, the primordium of Rathke's pouch was closely associated with the cranial tip of the notochord, head mesenchyme and diencephalon. Cells of the Rathke's pouch displayed typical epithelial features that transformed into gland-like structures during development. Numerous Ki-67 positive cells characterised the Rathke's pouch, the diencephalon (neurohypophysis) and the associated mesenchyme. The highest proliferation rate was noticed in the earliest developmental stage, while it significantly decreased in the 7th week of development. The first intermediate filaments to appear in the Rathke's pouch showed cytokeratin 8 immunolabelling which decreased with advanced maturation. The diencephalon and infundibulum displayed parallel immunolabelling of vimentin, glial fibrillary acidic protein (GFAP) and neurofilament protein (NF), while the surrounding mesenchyme showed only vimentin labelling. Changes in the labelling of Ki-67 proliferation marker and intermediate filament proteins in the developing human pituitary gland coincided with separation of the Rathke's pouch from the pharyngeal epithelium and subsequent differentiation of different parts of the gland.

Relevance of Ki-67 and prognostic factors for recurrence/progression of gonadotropic adenomas after first surgery

OBJECTIVE

Gonadotropin-secreting pituitary adenomas carry a high risk of local recurrence or progression (R/P) of remnant tumor after first surgery. The clinical characteristics and the long-term outcome of these silent adenomas, which show no signs of endocrine hyperfunction, differ from those of other types of pituitary adenomas. However, to date, no study has focused specifically on gonadotropic adenomas.

MATERIALS AND METHODS

To identify prognostic factors of R/P of remnants, we studied the postoperative outcome of 32 gonadotropic pituitary adenomas, defined on immunohistochemical staining, according to their clinical and radiological characteristics as well as the Ki-67 labeling index (LI).

RESULTS

The Ki-67 LI failed to provide independent information for the identification of patients at risk of progression of remnants or recurrence. Multivariate survival analysis (Cox regression) showed that neither invasiveness nor remnant tumors nor hyposomatotropism influenced tumor recurrence. The strongest predicting factors of R/P were the antero-posterior (AP) diameter in the sagittal plane (P = 0.014), and the age of the patient at surgery (P = 0.047), with younger patients being at greater risk. Hazard ratios were 2.11 for each 5 mm increase in AP diameter and 0.57 for every 10 years of age.

CONCLUSION

The two simple clinical criteria revealed by our study, the AP diameter of the tumor and the age of the patient, should be helpful in planning clinical management and radiological monitoring after first surgery of gonadotropic adenomas, while awaiting the identification of other pathological parameters.

Matrix metalloproteinase-2 expression correlates with cavernous sinus invasion in pituitary adenomas

The aim of this study was to evaluate the relationship between expression of matrix metalloproteinase-2 (MMP-2) and cavernous sinus invasion in pituitary adenoma.

METHOD

Tissue samples from 54 pituitary adenomas were examined for expression of MMP-2 protein by immunohistochemistry. In sixteen tumors, the expression of MMP-2 mRNA was also examined by RT-PCR. Immunostaining was semiquantatively scored based on intensity (0-3) and distribution (0-3).

RESULTS

There were 34 women and 20 men, with a mean age of 49.9 years (range 18-76). There were 12 tumors with cavernous sinus invasion, and 42 noninvasive cases. The MMP-2 score of pituitary adenomas with cavernous sinus invasion (3.9 +/- 0.5) was significantly higher than those without invasion (2.3 +/- 0.2; P < 0.01). There was no difference in MMP-2 score between macroadenomas (3.0 +/- 0.3) and microadenomas (2.1 +/- 0.4; P > 0.05), and also, no difference between the functioning adenomas (2.8 +/- 0.3) and non-functioning adenomas (2.8 +/- 0.3; P > 0.05). We found no correlation between the MMP-2 score and the Ki-67 labeling index (r2 = -0.05; P = 0.72). MMP-2 mRNA expression was also intense in invasive pituitary adenomas and was significantly higher in invasive pituitary adenomas than those without invasion (68.2 +/- 15.3; 21.8 +/- 8.2; P < 0.05).

CONCLUSION

This study suggests that MMP-2 may be associated with aggressiveness and invasion in pituitary adenoma but is not related to tumor size or secretory function. MMP-2 may be a useful tool for assessing the invasive potential.

Expression of p53, Ki-67 and c-erb B2 in growth hormone-and/or prolactin-secreting pituitary adenomas

The subcellular events implicated on the formation and behavior of pituitary adenomas are not fully understood. In this study we investigated the presence of p53, Ki-67 and c-erb B2 in 38 pituitary adenomas with immunohistochemical positivity for GH and prolactin (n=26; 68.4%), for prolactin (n=9; 23.7%) and for GH (n=3. 7.8%). The analyses revealed the following results: 24 (63.2%) tumors expressed variable positivity for c-erb B2, 11 (28.9%) expressed p53 positivity and 11 (28.9%) tumors were variably positive for Ki-67. Our results demonstrated a high percentage of GH/prolactin-, prolactin- and GH-secreting tumors with immunohistochemical positivity for c-erb B2. Once this membrane receptor is related to growth factors EGF and TGFalpha and both have a definite effect on tumor growth, our data suggest a possible role for c-erb B2 on the evolution of these tumors.

Expression of proliferation markers in human pituitary incidentalomas

This study aimed to immunohistochemically assess the proliferation activity of pituitary incidentalomas. A series of 52 incidentalomas studied included 22 gonadotroph cell adenomas, 21 null cell adenomas, and 9 clinically silent adenomas (identified as functioning by immunohistochemistry). We also analyzed the differences in proliferation activity between 43 non-functioning pituitary incidentalomas (not including 9 silent adenomas), and 43 symptomatic non-functioning adenomas (NFAs) that caused visual disturbance. Cell proliferation markers were immunostained using monoclonal Ki-67 (MIB-1) antibody and monoclonal anti-topoisomerase II alpha (Topo-II alpha) antibody. The average of MIB-1 labeling indices in pituitary incidentalomas was 0.61% +/- 0.06%. Overall, both MIB-1 and Topo-II alpha labeling indices of the incidentalomas were significantly lower than those of symptomatic NFAs. There were no significant differences in immunopositivity between the two groups based on gender, age, or subtype. The MIB-1 index of the smallest adenoma group in pituitary incidentalomas was significantly lower than in symptomatic NFAs, while the Topo-II alpha incidentaloma was significantly lower than in symptomatic NFAs. Our findings suggest that small or less invasive pituitary incidentalomas should be observed with follow-up MRI. Large or invasive incidentalomas should be surgically treated if the patients show visual disturbances, hypopituitarism, or pituitary apoplexy during the follow-up period.

Relevance of high Ki-67 in pituitary adenomas

Pituitary adenomas are heterogeneous in growth rate, invasiveness, and recurrence. To understand the biological behavior of the individual adenoma more fully, cell proliferation markers such as monoclonal antibodies targeted against the Ki-67 antigen have been applied. The Ki-67 antigen is a protein related to cell proliferation and is expressed in cell nuclei throughout the entire cell cycle. The authors report the case of an extremely rapidly growing pituitary adenoma with cavernous sinus invasion. The lesion, which displayed a high Ki-67 labeling index (LI; 22%), was found in a 54-year-old woman who presented with diplopia and headaches. The patient underwent three transsphenoidal operations in less than 6 months and, ultimately, was treated with fractionated intensity-modulated radiation therapy. The relationships between high Ki-67 LIs and tumor recurrence, invasiveness, and growth velocity in pituitary adenomas are reviewed.

Matrix metalloproteinase 2 and 9 expression correlated with cavernous sinus invasion of pituitary adenomas

OBJECT

Matrix metalloproteinase (MMP) 2 and 9 are important for tissue breakdown in the process of tumor invasion. The aim of this study is to evaluate the relationship between the expression of MMP-2, MMP-9, MIB-1 LI and cavernous sinus invasion in pituitary adenomas.

METHODS

Tissue samples from 54 patients with pituitary adenomas were studied. Expression of MMP-2, MMP-9, and MIB-1 labeling index (LI) were evaluated by immunohistochemical method. In sixteen cases, the expression of MMP-2 and MMP-9 mRNA was also examined by RT-PCR assay.

RESULTS

Thirty-four patients were women and 20 were men, with a mean age of 49.9 years old (range 18-76 years). There were 12 cases with cavernous sinus invasion, and 42 were noninvasive cases. MMP-2 and MMP-9 score of invasive case (3.9 +/- 0.5,4.1 +/- 0.4) were significantly higher than those (2.3 +/- 0.2; p < 0.01; 2.6 +/- 0.2; p < 0.01) without invasion. The MIB-1 LI of this study presented no significantly difference between the invasive and noninvasive pituitary adenomas. The percentage of MMP-2 mRNA/beta-actin mRNA and MMP-9 mRNA/beta-actin mRNA were also observed significantly higher in invasive pituitary adenomas (68.2 +/- 15.3%; 59.7 +/- 12.5%) than noninvasive pituitary adenomas (21.8 +/- 8.2%, p < 0.05; 33.3 +/- 5.4%, p < 0.05).

CONCLUSIONS

Our study suggests that the expression of MMP-2 and MMP-9 may have a value to assess the invasive pituitary adenomas, and proliferation and invasion of pituitary adenomas may present a different mechanism.

Expression of Ki-67 antigen in nonfunctioning pituitary adenomas: correlation with growth velocity and invasiveness

Object. The cell cycle—dependent nuclear antigen Ki-67 is related to growth potential in a variety of tumors. Elevated expression of Ki-67 was previously shown in recurrent pituitary adenomas; however, it has remained unclear whether this expression is related to the growth velocity or invasive behavior of these tumors. The aim of this study was to determine the correlation of Ki-67 antigen expression, growth velocity, and invasiveness in nonfunctioning pituitary adenomas.

Methods. Between April 1998 and April 2002, 23 patients with nonfunctioning pituitary adenomas who had participated in an observation period in which multiple computerized tomography and magnetic resonance imaging studies had been performed were surgically treated in our department. Tumor volumes were assessed using a stereological method based on the Cavalieri principle. The growth rate was calculated for each patient. Expression of Ki-67 antigen was examined using the monoclonal antibody MIB-1.

The assessed growth velocity of the adenomas was best described by a linear growth model. The correlation between Ki-67 expression and growth rate was highly significant. Rapidly growing adenomas (>0.07% daily increase in size) were found to have a Ki-67 labeling index (LI) exceeding 1.5%, whereas all five adenomas with a very slow growth rate (< 0.02% daily increase in size) had a Ki-67 LI lower than 1.5%. No correlation was found between the growth rate and the invasive character of the adenomas.

Conclusions. Expression of Ki-67 antigen is significantly correlated to the growth velocity of pituitary adenomas. Invasive behavior is a feature independent of proliferative activity. The extent of Ki-67 expression is helpful for clinical decision making and routine assessment of Ki-67 is recommended during the histopathological workup of pituitary adenomas.