Tumor Labeling Index Research Articles

Prognostic Utility of the Ki-67 Labeling Index in Follicular Thyroid Tumors: a 20-Year Experience from a Tertiary Thyroid Center

Follicular thyroid tumors pose a diagnostic challenge on the preoperative level, as the discrimination between follicular thyroid carcinoma (FTC) and adenoma (FTA) demands careful histopathological investigation. Moreover, prognostication of FTCs is mostly based on tumor size and extent of invasive properties, while immunohistochemical markers pinpointing high-risk cases are lacking. We have routinely established a Ki-67 labeling index for follicular thyroid tumors since 1999. To assess the potential value of Ki-67 as an adjunct tool to (1) correctly separate FTCs from FTAs and (2) help identify poor-prognosis FTCs, we collected histopathological and clinical data from 818 follicular thyroid tumors with a histological Ki-67 labeling index established in clinical routine practice (516 FTAs, 252 FTCs, and 50 follicular thyroid tumors of uncertain malignant potential (FT-UMPs)). The Ki-67 labeling index was higher in FTCs (mean 5.8%) than in FTAs (mean 2.6%) (P < 0.001), and a receiver operating characteristic curve analysis revealed a cut-off value of 4% to separate FTC from FTA with a sensitivity and specificity of 65% and 83%, respectively. Similarly, a Ki-67 labeling index above 4% was found to identify FTCs that later metastasized from clinically indolent FTCs with a sensitivity and specificity of 80% and 48%, respectively. Ki-67 constituted an independent predictor of future FTC metastases/recurrence and death of disease, and a value > 4% was a reliable prognostic marker within individual pT staging groups. We conclude that Ki-67 is a potentially valuable marker for the prognostication of FTCs, and future implementation in the histopathological assessments of follicular thyroid tumors could be beneficial if reproduced in international series.

Utility of preoperative computed tomography features in predicting the Ki-67 labeling index of gastric gastrointestinal stromal tumors

PurposeTo evaluate the value of preoperative computed tomography (CT) features including morphologic and quantitative features for predicting the Ki-67 labeling index (Ki-67LI) of gastric gastrointestinal stromal tumors (GISTs). MethodsWe retrospectively included 167 patients with gastric GISTs who underwent preoperative contrast-enhanced CT. We assessed the morphologic features of preoperative CT images and the quantitative features including the maximum diameter of tumor, total tumor volume, mean total tumor CT value, necrosis volume, necrosis volume ratio, enhanced tissue volume, and mean CT value of enhanced tissue. Potential predictive parameters to distinguish the high-level Ki-67LI group (>4%, n = 125) from the low-level Ki-67LI group (≤4%, n = 42) were compared and subsequently determined in multivariable logistic regression analysis. ResultsGrowth pattern (p = 0.036), shape (p = 0.000), maximum diameter (p = 0.018), total tumor volume (p = 0.021), mean total tumor CT value (p = 0.009), necrosis volume (p = 0.006), necrosis volume ratio (p = 0.000), enhanced tissue volume (p = 0.027), and mean CT value of enhanced tissue (p = 0.004) were significantly different between the two groups. Multivariate logistic regression analysis indicated that lobulated/irregular shape (odds ratio [OR] = 3.817; p = 0.000) and high necrosis volume ratio (OR = 1.935; p = 0.024) were independent factors of high-level Ki-67LI. ConclusionsHigher necrosis volume ratio in combination with lobulated/irregular shape could potentially predict high expression of Ki-67LI for gastric GISTs.

Ki-67 expression as a diagnostic biomarker in odontogenic cysts and tumors: A systematic review and meta-analysis.

Ki-67 is a marker of cell proliferation, used as an important diagnostic marker in the pathologic differentiation of various lesions. It is also relevant for developing targeted molecular therapies. We carried out a systematic review to assess the Ki-67 labeling index (LI) in odontogenic cysts and tumors. Databases were searched, including PubMed (MEDLINE), Scopus, CINHAL, PsycoInfo, the Cochrane Library, and Proquest. The meta-analysis was carried out based on the data of 608 lesions. When a 5% cut-off point was set, ki-67 LI of all benign odontogenic tumors dropped below this point. All the malignant tumors demonstrated an LI of over 15.3%; a significantly higher Ki-67 LI in malignant odontogenic lesions (17.59±2.80) was observed. Among benign tumors, the largest and the smallest Ki-67 LIs were seen in ameloblastoma (4.39±0.47) and adenomatoid odontogenic tumor (0.91±1.71). The mean values of Ki-67 LI in tumors and cysts were 4.23 (0.38) and 1.04 (0.07), respectively. Among odontogenic cysts, the highest Ki-67 LI was found in odontogenic keratocyst (OKC) (3.58±0.51), and the lowest in the radicular cyst (1.29±0.62%). Ki-67 LIs in all odontogenic cysts were <3%, except for OKC. This controversial lesion seems to have a profile more similar to a tumor, and a treatment plan similar to tumors might be suggested. We found that odontogenic lesions have diverse proliferative activities that help differentiate between various lesions and suggest therapeutic plans.

Ki-67 Labeling Index in Pulmonary Carcinoid Tumors: Comparison Between Small Biopsy and Resection Using Tumor Tracing and Hot Spot Methods.

Pulmonary carcinoids are classified as typical or atypical by assessing necrosis and mitoses, which usually cannot be adequately assessed on small biopsies. Ki-67 is not currently used to grade pulmonary carcinoids, but it may be helpful to determine preliminary grade in biopsies. However, the rate at which Ki-67 could underestimate or overestimate grade on small biopsies has not been well studied. To compare Ki-67 labeling obtained on small biopsies to subsequent resection. Ki-67 was performed on paired biopsy and resection specimens from 55 patients. Slides were scanned using Aperio ScanScope. Labeling index was determined using automated hot spot and tumor tracing methods. The study included 41 typical and 14 atypical carcinoids. Atypical carcinoids were larger and had more distant metastases. Death from disease occurred in 3 patients (all had atypical carcinoids). Median hot spot Ki-67 labeling index was greater in resection compared with biopsy by 0.7% (P = .02). Median tumor tracing Ki-67 was lower in resection compared with biopsy by 0.5% (P < .001). Receiver-operating characteristic analysis showed similar hot spot Ki-67 cutoffs to predict atypical histology (3.5% for biopsy, 3.6% for resection; area under the curve [AUC], 0.75 and 0.74, respectively). Different optimal cutoffs were needed for tracing method based on biopsy (2.1%; AUC, 0.75) compared with resection (1.0%; AUC, 0.67). Hot spot Ki-67 tends to underestimate grade on small biopsies, whereas grade is overestimated by tumor tracing. Hot spot Ki-67 cutoff of 3.5% predicted atypical histology for both biopsy and resection. Different biopsy and resection cutoffs were necessary for tumor tracing, which would make clinical implementation more difficult.

Revisiting the role of the pathological grading in pediatric adrenal cortical tumors: results from a national cohort study with pathological review

The prognosis of malignant pediatric adrenocortical tumors is closely related to disease stage, which is used to guide perioperative treatment recommendations. However, current scoring systems are inadequate to distinguish between benign and malignant adrenocortical tumors. Robust microscopic prognostic features that could help determine perioperative therapy are also lacking. The aim of this national study was to review the prognostic value of the Wieneke scoring criteria and Ki67 labeling index in unselected pediatric adrenocortical tumors. Using strict definitions previously defined by expert pathologists, a Wieneke score was re-attributed to each tumor after an independent and centralized review. In addition, Ki67 proliferation index was performed and reviewed for each case. A total of 95 cases were selected; all were treated between 2000 and 2018 and had histopathologic material and sufficient outcome-related information available. Localized disease was found in 88% of patients. Among those with advanced disease, 6% had tumor extension into adjacent organs and 5% had metastases at diagnosis. Median follow-up was 5 years and 3 months. The 5-year PFS was 82%, 95% CI [73%–91%]. Tumor stage significantly correlated with PFS (p < 0.0001). Tumor weight up to 200 g, extra-adrenal extension and initial non-complete surgical resection were statistically associated with worse outcomes. No recurrences nor metastases occurred when the Ki67 index was < 15%. Up to two of the following five factors including tumor necrosis, adrenal capsular invasion, venous invasion, mitotic count > 15/20 high-power fields, and Ki67 index > 15%, significantly correlated with worse outcomes. We propose a pathological scoring system incorporating the Ki67 index as part of a two-step approach after disease staging to guide adjuvant treatment in pediatric adrenocortical tumors, especially after incomplete resection. These results should be validated in an independent cohort.

Immunohistochemical Detection of Proliferative Marker Ki-67 in Benign and Malignant Salivary Gland Tumors

Introduction: Salivary gland tumors are the most histologically heterogeneous group of tumors with the greatest diversity of morphologic features among their cells and tissues. The present study was aimed at assessing the validity of Ki-67, a cell proliferation marker, as a prognostic factor in benign and malignant salivary gland tumors and to study whether it is related to age, sex, anatomical site, and size of the lesion in salivary gland tumors. Materials and methods: A retrospective study consisted of benign salivary gland tumors (BSGTs) (n = 15), malignant salivary gland tumors (n = 18), and normal salivary gland parenchyma (n = 15). Results: There was a significant difference of Ki-67 labeling index (LI, %) in normal salivary gland parenchyma, BSGTs, and malignant salivary gland tumors. The Ki-67 LI (%) in normal salivary gland parenchyma is negligible (0.27 ± 0.31%), whereas malignant salivary gland tumors showed very high Ki-67 LI (%) of 18.79 ± 18.06% compared with BSGTs being 0.76 ± 2.02%. There was a significant correlation statistically of mean ± standard deviation (SD) of Ki-67 LI (%) with the age of the patients being the maximum (32.68 ± 15.87%) in the 50 to 59 years age group, whereas sex, site of the lesion, and size of the lesion in salivary gland tumors had no significant correlation. Conclusion: The Ki-67 is a useful marker for assessing prolif-erative potential of tumors. Clinical significance: The Ki-67 LI% can be used as a reliable adjuvant diagnostic tool to differentiate between the subtypes and grading of certain malignant tumors, such as mucoepi-dermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), and acinic cell carcinoma (AcCC), which are usually difficult to diagnose on histopathological criteria alone. Keywords: Immunohistochemistry, Ki-67, Salivary gland neoplasms.

Ki-67 labeling index of neuroendocrine tumors of the lung has a high level of correspondence between biopsy samples and surgical specimens when strict counting guidelines are applied

Optimal histopathological analysis of biopsies from metastases of neuroendocrine tumor (NET) of the lung requires more than morphology only. Additional parameters such as Ki-67 labeling index are required for adequate diagnosis, but few studies have compared reproducibility of different counting protocols and modalities of reporting on biopsies of lung NET. We compared the results of four different manual counting techniques to establish Ki-67 LI. On 47 paired biopsies and surgical specimens from 22 typical carcinoids (TCs), 14 atypical carcinoids (ACs), six large cell neuroendocrine carcinomas (LCNECs), and five small cell carcinomas (SCCs) immunohistochemical staining of Ki-67 antigen was performed. We counted, in regions of highest nuclear staining (HSR), a full ×40-high-power field (diameter=0.55mm), 500 or 2000 cells, or 2mm2 surface area, including the HSR or the entire biopsy fragment(s). Mitoses and necrosis were evaluated in an area of 2mm2 or the entire biopsy fragment(s). Between the four counting methods, no differences in Ki-67 LI were observed. However, a Ki-67 LI higher than 5% was found in only four cases when in an HSR, 500 cells were counted (18%), five (23%) when in an HSR 2000 cells were counted, four (18%) when 2mm2 were counted, and one (5%) TC case when the entire biopsy was counted. A 20% cutoff distinguished TC and AC from LCNEC and SCC with 100% specificity and sensitivity, while mitoses and necrosis failed to a large extent. Ki-67 LI in biopsy samples was concordant with that in resection specimens when 2000 cells, 2mm2, or the entire biopsy fragment(s) were counted. Our results are important for clinical management of patients with metastases of a lung NET.

Prospero homeobox 1 mediates the progression of gastric cancer by inducing tumor cell proliferation and lymphangiogenesis.

Prospero homeobox 1 (PROX1) functions as a tumor suppressor gene or an oncogene in various cancer types. However, the distinct function of PROX1 in gastric cancer is unclear. We determined whether PROX1 affected the oncogenic behavior of gastric cancer cells and investigated its prognostic value in patients with gastric cancer. A small interfering RNA against PROX1 was used to silence PROX1 expression in gastric cancer cell lines AGS and SNU638. Expression of PROX1 in gastric cancer tissues was investigated by performing immunohistochemistry. Apoptosis, proliferation, angiogenesis, and lymphangiogenesis were determined by performing the TUNEL assay and immunohistochemical staining for Ki-67, CD34, and D2-40. PROX1 knockdown induced apoptosis by activating cleaved caspase-3, caspase-7, caspase-9, and poly(ADP-ribose) polymerase, and by decreasing the expression of anti-apoptotic proteins Bcl-2 and Bcl-xL. PROX1 knockdown also suppressed tumor cell proliferation. In addition, PROX1 knockdown decreased lymphatic endothelial cell invasion and tube formation and the expression of vascular endothelial growth factor (VEGF)-C and -D and cyclooxygenase (COX)-2. However, PROX1 knockdown only decreased umbilical vein endothelial cell invasion, not tube formation. The mean Ki-67 labeling index and lymphatic vessel density value of PROX1-positive tumors were significantly higher than those of PROX1-negative tumors. However, no significant difference was observed between PROX1 expression and apoptotic index or microvessel density. PROX1 expression was significantly associated with age, cell differentiation, lymph node metastasis, cancer stage, and poor survival. These results indicate that PROX1 mediates the progression of gastric cancer by inducing tumor cell proliferation and lymphangiogenesis.

Association between axillary lymph node status and Ki67 labeling index in triple-negative medullary breast carcinoma.

Medullary breast carcinoma is a rare breast carcinoma with good prognosis. Although it has been established that axillary lymph node metastasis is a poor prognostic factor, little is known about the relationship between axillary lymph node metastasis and clinicopathological characteristics of medullary breast carcinoma patients. The aim of this study was to identify factors that predict occurrence of axillary lymph node metastasis in medullary breast carcinoma patients. We performed a retrospective study of axillary lymph node status and the relevant clinicopathological characteristics in 49 triple-negative medullary breast carcinoma patients with axillary lymph node dissection between November 2004 and July 2011. A total of 49 patients were enrolled in the study. Fourteen patients (28.6%) had axillary lymph node metastasis that was confirmed pathologically. Axillary lymph node metastasis was not associated with age, menopausal status, primary tumor size or its location, the degree of inflammation within the tumor or mitotic count. However, we found a statistically significant association between axillary lymph node metastasis and Ki67 labeling index in primary tumors (P < 0.001). There is a positive association between Ki67 labeling index in the primary tumor and axillary lymph node metastasis in triple-negative medullary breast carcinoma patients.

Prospective Analysis of Ki-67 as an Independent Predictor of Oncologic Outcomes in Patients with High Grade Upper Tract Urothelial Carcinoma

We determined the association of the proliferation marker Ki-67 with pathological parameters and oncologic outcomes in patients with high grade upper tract urothelial carcinoma. Immunohistochemical staining for Ki-67 was done prospectively in 101 consecutive patients undergoing radical nephroureterectomy/ureterectomy for high grade upper tract urothelial carcinoma. Data were compared based on Ki-67 status (normal vs over expressed). Survival was assessed by the Kaplan-Meier method. Cox regression analysis was done to identify independent predictors of time dependent outcomes. Median patient age was 70.0 years and median followup was 22.0 months (range 1 to 77). Overall, 30.2% of the population experienced recurrence and 24.8% died of upper tract urothelial carcinoma. Organ confined disease (T2 or less and lymph node negative), lymphovascular invasion and sessile architecture were present in 56.3%, 33.3% and 20.8% of patients, respectively. Ki-67 was over expressed in 73.3% of patients and associated with adverse pathological features. Patients with over expressed Ki-67 had significantly worse recurrence-free survival (43.2 vs 69.0 months, p = 0.006) and cancer specific survival (48.9 vs 68.9 months, p = 0.031) than patients with normal Ki-67. Patients with nonmetastatic disease similarly had worse recurrence-free survival (40.7 vs 71.8 months, p = 0.003) and cancer specific survival (41 months vs not attained, p = 0.008) for over expressed vs normal Ki-67. After adjusting for the effects of organ vs nonorgan confined disease Ki-67 over expression was an independent predictor of recurrence-free survival in the total cohort (HR 4.3, p = 0.05) and in patients with nonmetastatic disease (HR 8.5, p = 0.038). Ki-67 over expression was associated with adverse pathological features in cases of upper tract urothelial carcinoma. It was also an independent predictor of recurrence-free survival in patients with high grade upper tract urothelial carcinoma.

Ki-67 Labeling Index Is a Predictor of Postoperative Persistent Disease and Cancer Growth and a Prognostic Indicator in Papillary Thyroid Carcinoma

Background: We previously reported that the Ki-67 labeling index (LI) in primary tumors and the thyroglobulin (Tg)-doubling time (DT) were potent prognostic indicators in patients with papillary thyroid carcinoma (PTC). Objectives: To elucidate the relationship between these two factors. Methods: A total of 390 patients with PTC who underwent total thyroidectomy between 1998 and 2004 and in whom the Tg-DT was calculated were enrolled. We determined the Ki-67 LI in primary tumors and compared these values with the patients' clinicopathological factors, postoperative Tg status, Tg-DT, and prognosis. Tg status was categorized by postoperative serum Tg values: biochemically persistent disease (BPD), equivocal state, and biochemical remission. Results: The Ki-67 LI was ≤5% in 312 patients (80%), 5%-10% in 48 patients (12%), and >10% in 30 patients (8%). Ki-67 LI was significantly associated with BPD (p < 0.0001). The proportion of BPD patients increased with the higher Ki-67 LI category: 24, 67, and 87%, respectively. The Ki-67 LI had a significant inverse correlation with the Tg-DT (Spearman's ρ = −0.5267, p < 0.0001). Of the 378 patients without distant metastasis at surgery, 68 patients had recurrence, and 6 of the 390 patients died of PTC during the follow-up (mean 88 months). On multivariate analyses, the Ki-67 LI remained an independent predictor of disease-free survival and disease-specific survival when Tg-DT and Tg status were excluded from the analyses. Conclusions: Evaluation of the Ki-67 LI in primary tumors may allow the prediction of the postoperative Tg status, Tg-DT and prognosis of patients with PTC.

Factors Affecting 18F-FDG Uptake by Metastatic Lymph Nodes in Gastric Cancer

We assessed factors affecting fluorine F 18 fluorodeoxyglucose (F-FDG) uptake of metastatic lymph nodes (LNs) in advanced gastric cancer (AGC) due to low F-FDG uptake of metastatic LNs in gastric cancer. Retrospective analyses were performed on 31 patients with AGCs who underwent preoperative F-FDG positron emission tomography (PET) and subsequent gastrectomy. Metastatic LNs were compared with primary tumors (on a one-to-one basis) with respect to maximum standardized uptake values, glucose transporter type 1 (GLUT-1) expression, proliferation indices (using Ki-67), microvessel density, and lymphatic vessel density. Maximum standardized uptake values of metastatic LNs were significantly correlated with % GLUT-1 expression (ρ = 0.80, P < 0.0001) and Ki-67 labeling index (ρ = 0.57, P = 0.001) in LNs. These uptake values were also significantly correlated with SUVs (ρ = 0.54; P = 0.002), % GLUT-1 expression (ρ = 0.71, P < 0.0001), and Ki-67 labeling index (ρ = 0.43, P = 0.019) in primary tumors. In multiple regression analysis, only % GLUT-1 expression in primary tumors and metastatic LNs were significant factors in predicting maximum standardized uptake value of metastatic LNs. In AGCs, GLUT-1 expression and Ki-67 labeling index are important factors in predicting F-FDG uptake by metastatic LNs.

Ki67 Labeling Index in Neuroendocrine Tumors of the Gastrointestinal and Pancreatobiliary Tract

Department of Pathology and Laboratory Medicine, Emory University Hospital, Atlanta, GA Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Volkan Adsay, MD, Department of Pathology and Laboratory Medicine, 1364 Clifton Road NE, Room H-180B, Atlanta, GA (e-mail: [email protected]).

Regional Differences in Gallbladder Cancer Pathogenesis: Insights from a Comparison of Cell Cycle-Regulatory, PI3K, and Pro-Angiogenic Protein Expression

The variable incidence of gallbladder cancer (GBCA) suggests regional pathogenetic differences. This study compares cell cycle-regulatory, angiogenesis-related, and PI3K pathway protein expression in GBCAs from three continents. Immunohistochemical expression of several proteins was assessed, correlated with clinicopathologic variables, and compared among centers from Chile (Fundación Arturo López Pérez [FALP]), Japan (Yokohama City University [YCU]), and the United States (Memorial Sloan-Kettering Cancer Center [MSKCC]). Hierarchical clustering was used to partition the data based on protein-expression and treatment center. Tissue from 117 patients (MSKCC = 76; FALP = 22; YCU = 19) was analyzed. Mdm2 overexpression was seen only at MSKCC (p < 0.0001). Absence of p21 (p = 0.03) and VEGFR2 (p = 0.018) were more common and p27 expression was less frequent (p = 0.047) in tumors from YCU. Ki-67 labeling index in YCU tumors (median = 10) was two-thirds lower than at other centers. On hierarchical clustering analysis, all YCU patients (p = 0.017) and those with early tumors (p = 0.017) clustered separately from MSKCC. Median disease-specific survival after curative intent (R0) resection was 27 months and was similar among centers (p = 0.9). Median disease-specific survival of patients with early tumors was 28.4 months and was higher at YCU (not reached, p = 0.06). Cell cycle-regulatory protein expression patterns of YCU tumors differed from those treated at FALP and MSKCC. The differential clustering of protein expression and survival in patients with early tumors suggest regional differences in pathogenesis and disease biology.

1158P - KI-67 Index Variability in Neuroendocrine Tumors

ABSTRACT Introduction The Ki-67 labeling index is now well recognized as an integral factor in the identification and treatment of neuroendocrine tumors (NETs) from both a prognosis and treatment perspective. In 2010, the WHO endorsed a grading system of NETs dividing tumors into G1 (Ki-67 20%) classes. Previous studies have associated higher Ki-67 scores with greater morbidity, with G3 tumors behaving particularly aggressively, often requiring cytotoxic chemotherapy. Currently Ki-67 is determined from a single biopsy in a majority of cases. Little is known about the variability of the Ki-67 labeling index during the disease course or between primary and metastatic deposits, and there are no consensus guidelines on taking multiple biopsy specimens throughout the disease course. AIMS: To compare Ki-67 labeling among multiple biopsy samples in individual patients to examine for variability. Methods The Sunnybrook Odette NETs database (n = 327) was retrospectively reviewed for patients with a confirmed diagnosis of NET and multiple ( > = 2) biopsy or surgical pathologic specimens, either at variable times in their disease course or biopsies of both the primary and metastasis. All but 2 cases were reviewed by our expert local neuroendocrine pathologist. Changes in WHO classification between multiple specimens in individual patients were determined. Results 43 patients were identified for inclusion in the analysis. 39 patients had pathology on their primary tumor as well as a metastatic focus, while 4 had pathology on multiple metastatic foci only. 16/43 patients (37.2%) were identified who had enough variability between Ki-67 indices resulting in differing WHO classification grades. Twelve cases of 43 (27.9%) resulted in a second sample that increased the WHO grade by at least one level. Seven of 43 (16.3%) resulted in a new WHO classification of G3. Conclusions The Ki67 labeling index in neuroendocrine tumors may change throughout the disease course, may differ between primary tumor and metastases, and may behave more aggressively later in the disease. Given the reliance on this index for management decisions, multiple biopsies of both the primary and metastatic tumor as well as through the disease course may be required to effectively treat these heterogeneous malignancies. Disclosure All authors have declared no conflicts of interest.

Low Aryl Hydrocarbon Receptor-Interacting Protein Expression Is a Better Marker of Invasiveness in Somatotropinomas than Ki-67 and p53

Background: Some pituitary adenomas exhibit fast growth and invade surrounding structures. To date, there is no robust marker to predict invasiveness. Aim: To evaluate Ki-67, p53 and aryl hydrocarbon receptor-interacting protein (AIP) expression and compare these between invasive and noninvasive somatotropinomas and nonfunctioning pituitary adenomas (NFPAs). Methods: Protein expression was determined by immunohistochemistry. Tumors were classified according to percentage of immunolabeled nuclei for Ki-67 and p53. AIP immunopositivity was graded according to a score encompassing pattern and intensity. Invasiveness was defined according to radiological and surgical criteria. Results: Thirty-eight sporadic somatotropinomas were studied. Median Ki-67 labeling index in invasive and noninvasive tumors was 1.6 (range 0–20.6) and 0.26 (0–2.2), respectively (p = 0.01). With a 2.3% cut-off point obtained by ROC curve analysis, invasive adenomas were distinguished with 100% specificity, 39% sensitivity, and 63% accuracy. Low AIP expression was also correlated with tumor invasiveness (p = 0.001), with sensitivity, specificity and accuracy of 78, 80, and 79%, respectively. Expression of p53 was not different among tumors. Twenty-nine NFPAs were studied, with no significant difference between Ki-67, p53 and AIP expression in invasive and noninvasive tumors. High AIP expression was more frequent in NFPAs, with Ki-67 >3% (p = 0.051), especially when only gonadotrope cell adenomas (n = 25) were considered (p = 0.012). Conclusions: These data suggest, for the first time, that AIP is a better marker of invasiveness in somatotropinomas than Ki-67 and p53. In addition, low AIP expression is observed in invasive somatotropinomas, in contrast with high AIP expression in NFPAs (mainly gonadotrope cell tumors) with high proliferative indices.

DNA methyltransferases 1, 3a, and 3b overexpression and clinical significance in gastroenteropancreatic neuroendocrine tumors

The alteration of DNA methylation is one of the most common epigenetic changes in human cancers. Three genes, namely, DNA methyltransferase 1, 3a, and 3b, which code for DNA methyltransferases that affect promoter methylation status, are thought to play an important role in the development of cancers and may be good anticancer therapy targets. The methylation of tumor suppressor genes has been reported in gastroenteropancreatic neuroendocrine tumors; however, there have been no studies about DNA methyltransferase protein expression and its clinical significance in gastroenteropancreatic neuroendocrine tumors. In this study, the expression of DNA methyltransferase 1, 3a, and 3b was studied in 63 gastroenteropancreatic neuroendocrine tumors by immunohistochemistry. The expression of DNA methyltransferase 1, 3a, and 3b was frequently detected in gastroenteropancreatic neuroendocrine tumors (87%, 81%, and 75%, respectively). The DNA methyltransferase 3a expression level was significantly higher in poorly differentiated neuroendocrine carcinomas than in well-differentiated neuroendocrine tumors or well-differentiated neuroendocrine carcinomas (P < .01 and P < .05, respectively). The expression of DNA methyltransferase 1, 3a, and 3b showed significantly higher levels in stage IV tumors than in stage I or II tumors. In addition, the expression levels of DNA methyltransferase 1, 3a, and 3b were positively correlated with the MIB-1 labeling index in gastroenteropancreatic neuroendocrine tumors (R = 0.293, P = .019; R = 0.457, P = .001; and R = 0.249, P = .049; respectively). In addition, the expression levels and positive immunostaining frequencies of DNA methyltransferase 3a and 3b were significantly lower in midgut neuroendocrine tumors than in foregut or hindgut neuroendocrine tumors. Our findings suggest that the overexpression of DNA methyltransferase 1, 3a, and 3b is related to tumorigenesis and the progression of gastroenteropancreatic neuroendocrine tumors.

Improvement in predicting tumorigenic phenotype of androgen‐insensitive human LNCaP prostatic cancer cell subline in recombination with rat urogenital sinus mesenchyme

Hormone-refractory prostate cancer, a heterogeneous disease, has varying degrees of androgen sensitivity. To understand the physiological changes in the hormone-refractory state, the present study used a lineage-derived androgen receptor (AR)-positive, androgen-insensitive prostate cancer cell line and evaluated the tumorigenic phenotype, focusing on tumor-stromal interactions in vivo. First, tumorigenic differences of cancer cells alone were examined in an androgen-insensitive AR-positive LNCaP subline, AIDL, compared with those of the androgen-sensitive AR-positive parental LNCaP and the androgen-insensitive AR-negative PC-3 cells transplanted into subcutaneous, sub-renal and prostatic orthotopic graft sites. Next, cancer cells were recombined with rat urogenital sinus mesenchyme (rUGM) to simulate the tumor-stromal microenvironment. Tumors of AIDL and LNCaP without stromal components both formed well-defined globular tumors and contained large blood-filled areas, with no significant difference in tumor growth or histopathology regardless of the cell line's androgen sensitivity or graft site. In contrast, tumors of AIDL and LNCaP recombined with rUGM both showed reduction of blood-filled areas in the tumors and increased tumor growth compared with cancer cells alone. Tumors of AIDL + rUGM recombinants were approximately three times as large as those of LNCaP + rUGM recombinants, whereas tumors of AIDL and LNCaP without rUGM were not different in size. In addition to the tumor size, cell proliferation (Ki-67 labeling index) in tumors of AIDL + rUGM recombinants was significantly higher than that in tumors of LNCaP + rUGM recombinants. Immunoreactivities of AR, E-cadherin and beta-catenin were decreased in AIDL + rUGM recombinants relative to AIDL alone and LNCaP + rUGM recombinants. These results demonstrated that tumorigenic features of androgen-insensitive AR-positive prostate cancer cells could be significantly influenced by rUGM. Therefore, this in vivo recombination model with rUGM may be useful in developing new treatment strategies.

Increased Expression of CENP-H Gene in Human Salivary Gland Carcinomas

There have been very few studies on the expression of Centromere proteins in human salivary gland carcinomas. The purpose of this study was to clarify the correlation between Centromere protein H (CENP-H) expression and clinicopathologic factors in salivary gland carcinomas. The expression of CENP-H mRNA was investigated in 28 human salivary gland tumors (7 pleomorphic adenomas, 3 Warthin tumors, 6 mucoepidermoid carcinomas, 6 adenoid cystic carcinomas, 5 acinic cell carcinomas and 1 malignant myoepithelioma) and 8 normal submandibular glands using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). The labeling index of PCNA and Ki-67 were also investigated immunohistochemically in 16 salivary gland carcinomas. The mean expression level of CENP-H mRNA was significantly higher in malignant tumors (0.55 ± 0.68) than normal submandibular glands (0.10 ± 0.029). A significant correlation between the PCNA labeling index and CENP-H mRNA expression was also found (Spearman's correlation coefficient by rank test, P=0.033). We also found a significant correlation between the Ki-67 labeling index and CENP-H mRNA expression in malignant tumors (Spearman's correlation coefficient by rank test, P=0.040). These results indicate that human CENP-H mRNA is closely linked to increased or abnormal cell proliferation in malignant salivary gland tumors.

Mechanisms of chemoresistance and poor prognosis in ovarian clear cell carcinoma

Clear cell carcinoma (CCC) accounts for 4% to 12% of epithelial ovarian cancer in Western countries and, for some unknown reasons, it comprises more than 20% of such cancers in Japan. CCC shows unique clinical features such as a high incidence of stage I disease, a large pelvic mass, an increased incidence of vascular thromboembolic complications, and hypercalcemia. It is frequently associated with endometriosis. Compared to serous adenocarcinoma (SAC), CCC is relatively resistant to conventional platinum, or taxane-based chemotherapy which is associated with its poor prognosis. However, the mechanisms underlying CCC's resistance to chemotherapy have not been understood. Although several mechanisms involved in drug resistance exist in CCC, including decreased drug accumulation, increased drug detoxification, and an increased DNA repair activity; however, no particular chemoresistance system has been identified. On the other hand, an in vitro study revealed that low cell proliferation may cause the insensitivity of CCC to cisplatin. The Ki-67 labeling index in CCC tumors was significantly lower than SAC. The Ki-67 labeling index for responders was significantly higher than that for non-responders in both tumor types. A multivariable analysis revealed that Ki-67 labeling index and residual tumor size were independent prognostic factors in CCC. Therefore, lower proliferation of the tumor cells may contribute to their resistance to chemotherapy. However, further investigation into the molecular biology and genetics of CCC is warranted. This review discusses the current state of knowledge of the chemoresistance mechanism in CCC and novel treatment strategies for CCC.