Showing papers by "Sanford A. Stass published in 2008"

Targeted disruption of Aurora A causes abnormal mitotic spindle assembly, chromosome misalignment and embryonic lethality

Abstract: Aurora A (also known as STK15/BTAK in humans), a putative oncoprotein naturally overexpressed in many human cancers, is a member of the conserved Aurora protein serine/threonine kinase family that is implicated in the regulation of G2–M phases of the cell cycle. In vitro studies utilizing antibody microinjection, siRNA silencing and small molecule inhibitors have indicated that Aurora A functions in early as well as late stages of mitosis. However, due to limitations in specificity of the techniques, exact functional roles of the kinase remain to be clearly elucidated. In order to identify the physiological functions in vivo, we have generated Aurora A null mouse embryos, which show severe defects at 3.5 d.p.c. (days post-coitus) morula/blastocyst stage and lethality before 8.5 d.p.c. Null embryos at 3.5 d.p.c. reveal growth retardation with cells in mitotic disarray manifesting disorganized spindle, misaligned and lagging chromosomes as well as micronucleated cells. These findings provide the first unequivocal genetic evidence for an essential physiological role of Aurora A in normal mitotic spindle assembly, chromosome alignment segregation and maintenance of viability in mammalian embryos.

Magnetic enrichment of bronchial epithelial cells from sputum for lung cancer diagnosis.

Abstract: Nonsmall-cell lung cancer (NSCLC), mainly comprising adenocarcinomas and squamous cell carcinomas of lung, is the number 1 cancer killer in the US and worldwide.1,2 Given the poor prognosis associated with advanced-stage lung cancer, diagnosing the disease earlier could reduce the mortality. Chest X-ray has been used for the early detection of lung cancer; however, the sensitivity is low.3 Computerized tomographic (CT) radiologic imaging is more sensitive for diagnosing lung tumors in the peripheral lung fields than for those in the more central bronchial airways, where interpretation of CT imaging is less certain.4 The fluorescence bronchoscopy excels at detecting centrally occurring lung tumors.5 However, it is an invasive technique, and not suitable for lung cancer early detection, particularly screening populations at high risk for lung cancer. Thus, the development of sensitive and noninvasive approaches for the early diagnosis of lung cancer is clearly important to reduce mortality. Because sputum is 1 of the most easily accessible materials and contains exfoliated airway epithelial cells from the bronchial tree, it has been considered a suitable diagnostic material for assessing carcinogenic damage in lung tumors.3,4 Morphologic analysis of sputum by cytology has been used for the early diagnosis of lung cancer, particularly bronchogenic squamous cell carcinoma.5 However, the sensitivity is very low, because the sputum cytology depends mainly on the skills required for identifying subtle morphologic abnormalities in cells. Furthermore, there is a dramatic variation in intra- and interobserver agreement in determining cancer cells because of the uncertainties of pattern recognition and classification by cytopathologists.3–5 In addition, because of the low percentage of bronchial epithelial cells in sputum, 10 cytocentrifuge slides are needed to have enough bronchial epithelial cells to be analyzed, making sputum cytology very labor-intensive and time-consuming. Instead of observing morphologic characterization by cytology, molecular genetic study of sputum could identify the cells containing tumor-related genetic aberrations, which occur in microscopically normal-appearing epithelium and are specific signs of the progression of tumorigenesis.6 We have recently found that the combined assessment of deletions of both HYAL2 and FHIT tumor suppressor genes could detect abnormal cells not only in all the cytologically positive sputum, but also in 55% cytologically negative sputum from lung cancer patients, suggesting that testing genetic aberrations in sputum could be more sensitive than cytology in identifying cancer cells.7 Therefore, molecular genetic studies might overcome the limitation of sputum cytology and detect genetically abnormal cells that escape cytologic examination, providing a potential diagnostic tool for early-stage lung cancer. However, the use of sputum for molecular genetic analyses is limited by its cellular heterogeneity, which includes about 1% bronchial epithelial cells.8–10 The large excess of macrophages and neutrophils that account for >95% sputum cell population could obscure detection and quantitation of neoplastic changes occurring in the bronchial epithelial cells.7 Therefore, enrichment of bronchial epithelial cells before the actual detection procedure is needed to improve the efficiency and accuracy of genetic and cytologic diagnosis of lung cancer in sputum samples.10 Magnetic cell sorting (MACS) is a process of immunomagnetic cell selection based on the recognition of cell-specific antibodies coupled to magnetic beads.11 MACS has been developed to specifically separate rare circulating tumor cells from whole blood for predicting recurrence in patients with solid cancers.12–14 The objective of the study was to obtain concentrated and purified bronchial epithelial cells from sputum to improve diagnosis of lung cancer in sputum samples. Using MACS with anti-CD14 and anti-CD16 antibody beads to specifically deplete macrophages and neutrophils, we enriched bronchial epithelial cells from sputum of stage I NSCLC patients, cancer-free heavy smokers, and healthy nonsmokers. We then analyzed the enriched sputum by using fluorescence in situ hybridization (FISH) for the detection of genetic deletion of FHIT.

C-MYC rearrangements are frequent in aggressive mature B-cell lymphoma with atypical morphology

Abstract: Diagnosis and classification of aggressive mature B-cell lymphoma with atypical morphology remains a challenge. To identify factors that may contribute to the atypical morphology, we selected eight such cases and evaluated their morphologic, immunophenotypic and cytogenetic features and clinical outcomes. The neoplastic cells showed a diffuse monotonous infiltrating pattern with a spectrum of morphology including: 1) L1 lymphoblastic; 2) centroblastic; 3) immunoblastic; and 4) mixed centroblastic and immunoblastic. The lymphoma cells in most cases were positive for CD10 and/or BCL6, and showed BCL2 expression. 6 of 8 cases showed C-MYC rearrangements, and interestingly, all 6 cases demonstrated a proliferation index of ≤90%. 3 of the 6 cases also demonstrated t(14;18). Clinical follow-up indicated that aggressive mature B-cell lymphoma may benefit from more intensified chemotherapeutic regimens used for BL. Our study suggests that aggressive mature B-cell lymphoma with atypical morphology may be another “grey zone lymphoma” lying in the spectrum between Burkitt lymphoma and diffuse large B-cell lymphoma.

Original Article C-MYC Rearrangements are Frequent in Aggressive Mature B-Cell Lymphoma with Atypical Morphology

Abstract: Diagnosis and classification of aggressive mature B-cell lymphoma with atypical morphology remains a challenge. To identify factors that may contribute to the atypical morphology, we selected eight such cases and evaluated their morphologic, immunophenotypic and cytogenetic features and clinical outcomes. The neoplastic cells showed a diffuse monotonous infiltrating pattern with a spectrum of morphology including: 1) L1 lymphoblastic; 2) centroblastic; 3) immunoblastic; and 4) mixed centroblastic and immunoblastic. The lymphoma cells in most cases were positive for CD10 and/or BCL6, and showed BCL2 expression. 6 of 8 cases showed C- MYC rearrangements, and interestingly, all 6 cases demonstrated a proliferation index of <90%. 3 of the 6 cases also demonstrated t(14;18). Clinical follow-up indicated that aggressive mature B-cell lymphoma may benefit from more intensified chemotherapeutic regimens used for BL. Our study suggests that aggressive mature B-cell lymphoma with atypical morphology may be another "grey zone lymphoma" lying in the spectrum between Burkitt lymphoma and diffuse large B-cell lymphoma.