Pulmonary Neuroendocrine Tumors Research Articles

Cellular Localization of Protein Arginine Methyltransferase-5 Correlates With Grade of Pulmonary Neuroendocrine Tumors

Epigenetic regulation plays an important role in oncogenesis. Histone modification is recognized as one strategy for modifying epigenetic control and cancer therapies. Cell culture and animal models show that protein arginine methyltransferase-5 (PRMT5) is an important epigenetic modifier of histone and nonhistone proteins in lymphomas, breast, colorectal, and lung cancer. Overexpression of PRMT5 is associated with malignant phenotype in …

Clinicopathologic significance of immunostaining of α-thalassemia/mental retardation syndrome X-linked protein and death domain–associated protein in neuroendocrine tumors

α-Thalassemia/mental retardation syndrome X-linked protein (ATRX) and death domain-associated protein (DAXX) genes are tumor suppressors whose mutations have been identified in sporadic pancreatic neuroendocrine tumors as well as in patients with MEN1. However, it is unknown whether ATRX and DAXX alterations are specific for pancreatic neuroendocrine tumor. In addition, the association of ATRX/DAXX protein loss with tumor cell proliferation has not been examined. We, therefore, immunostained ATRX and DAXX in 10 gastric, 15 duodenal, 20 rectal, 70 pancreatic, and 22 pulmonary neuroendocrine tumors with 15 nonneoplastic pancreases and 27 pancreatic adenocarcinomas to elucidate the site-specific roles of ATRX/DAXX abnormalities. At least 1 loss of ATRX and DAXX immunoreactivity was detected in all neuroendocrine tumor cases but not in any of nonneoplastic pancreatic tissues or pancreatic adenocarcinomas. The loss of DAXX protein was correlated with the Ki-67 index (ATRX, P = .904; DAXX, P = .044). The status of DAXX immunoreactivity correlated positively with World Health Organization histologic grade (P = .026). These results suggest that the status of ATRX or DAXX protein loss in neuroendocrine tumor differed among the organs in which these tumors arose, and these proteins may play site-specific roles in the development of these tumors.

Combination of carbonic anhydrase inhibitor, acetazolamide, and sulforaphane, reduces the viability and growth of bronchial carcinoid cell lines

BackgroundBronchial carcinoids are pulmonary neuroendocrine cell-derived tumors comprising typical (TC) and atypical (AC) malignant phenotypes. The 5-year survival rate in metastatic carcinoid, despite multiple current therapies, is 14-25%. Hence, we are testing novel therapies that can affect the proliferation and survival of bronchial carcinoids.MethodsIn vitro studies were used for the dose–response (AlamarBlue) effects of acetazolamide (AZ) and sulforaphane (SFN) on clonogenicity, serotonin-induced growth effect and serotonin content (LC-MS) on H-727 (TC) and H-720 (AC) bronchial carcinoid cell lines and their derived NOD/SCID mice subcutaneous xenografts. Tumor ultra structure was studied by electron microscopy. Invasive fraction of the tumors was determined by matrigel invasion assay. Immunohistochemistry was conducted to study the effect of treatment(s) on proliferation (Ki67, phospho histone-H3) and neuroendocrine phenotype (chromogranin-A, tryptophan hydroxylase).ResultsBoth compounds significantly reduced cell viability and colony formation in a dose-dependent manner (0–80 μM, 48 hours and 7 days) in H-727 and H-720 cell lines. Treatment of H-727 and H-720 subcutaneous xenografts in NOD/SCID mice with the combination of AZ + SFN for two weeks demonstrated highly significant growth inhibition and reduction of 5-HT content and reduced the invasive capacity of H-727 tumor cells. In terms of the tumor ultra structure, a marked reduction in secretory vesicles correlated with the decrease in 5-HT content.ConclusionsThe combination of AZ and SFN was more effective than either single agent. Since the effective doses are well within clinical range and bioavailability, our results suggest a potential new therapeutic strategy for the treatment of bronchial carcinoids.

Pulmonary neuroendocrine tumors with nuclear inclusion

Nuclear inclusion or pseudoinclusion is a peculiar cytological feature, and its recognition in appropriate clinicopathological settings can aid in the diagnosis of several disease entities. To the best of our knowledge, only 1 case of pulmonary neuroendocrine tumor (NET) with nuclear pseudoinclusion has been reported. A review of 227 patients who had undergone surgical resection for pulmonary NETs revealed 2 tumors with different mechanisms of nuclear inclusion. To explore the cause of nuclear inclusion, NET with nuclear inclusion was characterized immunohistochemically and ultrastructurally. Nuclear inclusions were observed in 2 of the 227 (0.9%) patients with pulmonary NETs. The first patient was a 46-year-old woman with small cell carcinoma. Tumor cells with nuclear inclusions were distributed focally. Ultrastructural analysis showed that these inclusions were pseudoinclusions. The second patient was a 62-year-old man with large-cell neuroendocrine carcinoma. Nuclear inclusions were observed in the focal area of the tumor. Immunohistochemical analysis revealed that the intra-nuclear materials consisted of biotin and aberrant cytoplasmic and nuclear accumulation of β-catenin. Mutational analysis revealed a CTNNB1 gene mutation. Although very rare, diagnostic errors may be observed in cases of pulmonary NETs with nuclear inclusions. The mechanisms of nuclear inclusion differed, with one due to herniation of the cytoplasm into the nucleus (pseudoinclusion) and the other due to accumulation of biotin resulting from a CTNNB1 gene mutation.

EComment. Surgical management of carcinoid tumours of the lung: sublobar resection versus lobectomy

Afoke and coworkers recently addressed the following question ‘Is sublobar resection equivalent to lobectomy for surgical management of peripheral carcinoid?’ [1]. Using a search strategy based on keywords ‘carcinoid tumour’ and ‘pulmonary surgical procedures’ the authors selected 10 articles to provide the best evidence to answer the question. Since the classification into two distinctive forms, typical (TC) and atypical carcinoids (AC), has changed over the years, this selection is, however, questionable. Indeed, in 1998, Travis and coworkers proposed new criteria for AC and its separation from TC. Based on these new criteria, the World Health Organization (WHO) established a definitive classification of pulmonary neuroendocrine tumours in 1999, which was confirmed in 2004. Consequently, in series of carcinoid tumours classified according to the old classifications (before 1999) there are some overlaps among the two entities (TC vs AC) in comparison with the definitive classification, leading to possible misleading factor in the Afoke and coworkers' study. In our opinion the series published before 1999 might be discarded to determine the long-term survival and disease recurrence such as we had done in a previous study in the field [2]. In fact, in the Afoke and coworkers' selection, there are only three valuable articles to address the question: the article by Chen and coworkers reporting a small group of patients included between 2000 and 2009 [1]; and two articles including patients before 1999, in which the pathology slide blocks were reviewed for reclassification according to the 1999 WHO criteria for neuroendocrine tumours [3, 4]. Finally, despite this limitation, the Afoke and coworkers' conclusion is in line with a recent study conducted in a large series of patients, in which the authors stated that ‘compared with lobectomy, sublobar resection is associated with non-inferior survival in patients with typical carcinoid of the lung’ [5].

Abstract 2375: Prognostic significance of the alternatively spliced ACTN4 variant in high-grade neuroendocrine pulmonary tumors.

Abstract Background: High-grade neuroendocrine tumours (HGNTs) of the lung manifest a wide spectrum of clinical behaviour, but no method of predicting their outcome has been established. Materials and methods: We newly established a monoclonal antibody specifically recognizing the product of the alternatively spliced ACTN4 transcript (namely, variant actinin-4), and used it to examine the expression of variant actinin-4 immunohistochemically in a total of 609 surgical specimens of various histological subtypes of lung cancer. Results: Variant actinin-4 was expressed in 55% (96/176) of HGNTs, but in only 0.8% (3/378) of non-neuroendocrine lung cancers. Expression of variant actinin-4 was significantly associated with unfavorable overall survival in HGNT patients (P = 0.00021, log-rank test). Multivariate analysis using the Cox proportional hazards model showed that expression of variant actinin-4 was the most significant independent negative predictor of survival in HGNT patients (hazard ratio, 2.18; P = 0.000714) after the presence of lymph node metastasis (hazard ratio, 2.30; P = 0.00012). Conclusions: Expression of variant actinin-4 is an independent prognostic factor for patients with HGNTs. This protein has high affinity for filamentous actin polymers and likely promotes aggressive behaviour of cancer cells. The present clinical findings clearly support this notion. Citation Format: Akihiko Miyanaga, Kazufumi Honda, Koji Tsuta, Mari Masuda, Akitomo Miyamoto, Shingo Shinagawa, Hitoshi Tsuda, Hisao Asamura, Akihiko Gemma, Tesshi Yamada. Prognostic significance of the alternatively spliced ACTN4 variant in high-grade neuroendocrine pulmonary tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2375. doi:10.1158/1538-7445.AM2013-2375 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Pulmonary Neuroendocrine Tumor Incidentally Detected by 18F-CH PET/CT

We report the case of a pulmonary neuroendocrine tumor (NET) incidentally detected by F-CH PET/CT performed during restaging in a 68-year-old patient affected by prostate cancer. To clarify the nature of the pulmonary lesion, the patient underwent a CT-guided biopsy which revealed the presence of a pulmonary NET. A subsequent Ga-DOTANOC PET/CT demonstrated the somatostatin receptor expression in the pulmonary lesion. The patient underwent a right lung lobectomy; at pathology, a well-differentiated NET was confirmed. Our case highlights that pulmonary NETs should be considered in the differential diagnosis of pulmonary lesions showing uptake of radiolabeled choline.

Promyelocytic leukemia zinc finger and histone H1.5 differentially stain low- and high-grade pulmonary neuroendocrine tumors: a pilot immunohistochemical study

Promyelocytic leukemia zinc finger is a zinc finger transcription factor that functions as a transcriptional repressor. Its expression has been shown to be down-regulated in hematopoietic, melanocytic, and mesothelial malignancies. Histone H1.5 is a variant of histone H1, a family of linker proteins that organizes chromosomes into higher order structures. Its function is of key importance in gene expression and has been linked to more aggressive forms of prostatic carcinoma. This study aimed to investigate the immunohistochemical detectability of promyelocytic leukemia zinc finger and histone H1.5 in pulmonary neuroendocrine tumors, comprising 11 carcinoid tumorlets, 24 typical carcinoids, 12 atypical carcinoids, 20 small cell carcinomas, 11 large cell neuroendocrine carcinomas, and 2 combined small cell carcinomas-large cell neuroendocrine carcinomas. Promyelocytic leukemia zinc finger immunohistochemistry revealed moderate or strong nuclear staining in all carcinoid tumorlets, 23 of 24 typical carcinoids, and 7 of 12 atypical carcinoids in contrast to 9 of 11 large cell neuroendocrine carcinomas, all small cell carcinoma, and both combined small cell carcinoma-large cell neuroendocrine carcinomas, which showed no nuclear immunoreactivity. Histone H1.5 immunohistochemistry revealed only focal or no immunoreactivity in all carcinoid tumorlets and 19 of 24 typical carcinoids, whereas 7 of 12 atypical carcinoids, 19 of 20 small cell carcinomas, 10 of 11 large cell neuroendocrine carcinomas, and both combined small cell carcinomas-large cell neuroendocrine carcinomas displayed positive (≥ 10%) nuclear immunoreactivity-ranging from a minority of weak staining to a majority of strong staining cases. Our data suggest that the relative expression ratios of promyelocytic leukemia zinc finger and histone H1.5 may correlate with grade of pulmonary neuroendocrine tumors. Immunohistochemical stains for these markers, especially on small biopsies with crush artifact, may prove to be diagnostically useful.

Morphologic Analysis of Pulmonary Neuroendocrine Tumors

BackgroundFew studies on how to diagnose pulmonary neuroendocrine tumors through morphometric analysis have been reported. In this study, we measured and analyzed the characteristic parameters of pulmonary neuroendocrine tumors using an image analyzer to aid in diagnosis.MethodsSixteen cases of typical carcinoid tumor, 5 cases of atypical carcinoid tumor, 15 cases of small cell carcinoma, and 51 cases of large cell neuroendocrine carcinoma were analyzed. Using an image analyzer, we measured the nuclear area, perimeter, and the major and minor axes.ResultsThe mean nuclear area was 0.318±0.101 µm2 in typical carcinoid tumors, 0.326±0.119 µm2 in atypical carcinoid tumors, 0.314±0.107 µm2 in small cell carcinomas, and 0.446±0.145 µm2 in large cell neuroendocrine carcinomas. The mean nuclear circumference was 2.268±0.600 µm in typical carcinoid tumors, 2.408±0.680 µm in atypical carcinoid tumors, 2.158±0.438 µm in small cell carcinomas, and 3.247±1.276 µm in large cell neuroendocrine carcinomas. All parameters were useful in distinguishing large cell neuroendocrine carcinoma from other tumors (p=0.001) and in particular, nuclear circumference was the most effective (p=0.001).ConclusionsPulmonary neuroendocrine tumors showed nuclear morphology differences by subtype. Therefore, evaluation of quantitative nuclear parameters improves the accuracy and reliability of diagnosis.

Evaluation of the Expression of the Low Weight Heat Shock Protein αB-crystallin in Pulmonary Neuroendocrine Tumours

B-crystallin is a major heat-inducible small heat shock protein, which is supposed to be implicated in tumour cell proliferation, differentiation, invasion, metastasis and apoptosis. Still the expression pattern of the phosphorylated on serin 59 form ofB-crystallin in lung cancer is not yet investigated. The aim of the present work is to study this pattern in different histological subtypes of pulmonary neuroendocrine tumours (pNETs). Surgically resected specimens from 143 patients with pNETs were studied. The histological subtype, pathological Tumour-Node-Metastasis stage and the immunohistochemical expression of phosphorylatedB-crystallin were evalu- ated. We demonstrated that the nucleus was the major localization site of the protein although there were some rare cases showing also diffuse cytoplasmic expression. High grade pNETs (small cell lung carcinoma and large cell neu- roendocrine carcinoma) showed nuclear expression in all cases but most fre- quently it was in less than 50% of the tumour cells; cytoplasmic expression was shown in single cases. Just the opposite was observed in low and intermediate grade pNETs (typical carcinoids and atypical carcinoids) - nuclear expression was not seen in all of the cases, but when it was present it was in almost all tumour cells; the cases expressing phosphorylatedB-crystallin also in the cy- toplasm were mainly typical carcinoids. We demonstrated that cytoplasmic This study was financially supported by the Council for Medical Science, Medical University of Sofia, Project Contract No 18-D/2010 and Project Contract No 1-D/2011.

Elevated CA 19-9 Levels Observed in Association with a Pulmonary Neuroendocrine Tumour and Amyloid

Investigations completed in a 77-year-old ex-smoker presenting with weight loss showed raised CA 19-9 levels. The findings of chest radiograph, abdominal computed tomography (CT) and gastrointestinal endoscopic examinations were all normal. On follow-up, the patient developed left upper lobe collapse on chest radiograph with increasing CA 19-9 levels. Chest CT findings suggested the presence of a left upper lobe tumour. The results of a biopsy of the left upper lobe nodule seen on bronchoscopy suggested a diagnosis of amyloidosis; however, this was not the only diagnosis. The left upper lobe mass comprised a neuroendocrine tumour with amyloid deposition just beneath the bronchial epithelium and focally between the nests of the tumour cells. We report and discuss this uncommon association and presentation.

79 Pulmonary neuroendocrine tumours: diagnostic and prognostic factors

79 Pulmonary neuroendocrine tumours: diagnostic and prognostic factors

Clinical Course of Neuroendocrine Tumors With Different Origins (the Pancreas, Gastrointestinal Tract, and Lung)

Neuroendocrine tumor originates from several sites. This study was conducted to reveal the differences in clinical course of neuroendocrine tumors by the origin. We reviewed data of patients diagnosed with neuroendocrine tumor between January 1996 and July 2007. A total of 371 patients were enrolled [pancreas 60, gastrointestinal (GI) tract 210, lung 35, other sites 46, unknown primary sites 20]. The primary tumor site correlated with the stage (P=0.000) and grade (P=0.000). At diagnosis, metastasis was observed in 28.3%, 6.7%, and 2.9% of the cases in pancreatic, GI, and pulmonary neuroendocrine tumors, respectively. Grade 3 neuroendocrine tumor was observed in 7.7%, 0.5%, and 0.0% in pancreatic, GI, and pulmonary neuroendocrine tumors. Overall survival was 116.0 months (95% confidence interval, 86.9-145.1). Overall survival was 116.0 months in pancreatic neuroendocrine tumor, not reached in GI neuroendocrine tumor and 120.0 months in pulmonary neuroendocrine tumor (P=0.024). The recurrence rate was 18.0%. It was 20.9%, 11.9%, and 2.9% in pancreatic, GI, and pulmonary neuroendocrine tumors (P=0.062). In multivariate analysis, stage, grade, and age were prognostic for overall survival (OS). Stage, grade, and sex were prognostic for disease-free survival. Neuroendocrine tumors from the pancreas, GI tract, and lung showed different clinical characteristics.

Pulmonary neuroendocrine tumors: An entity in search of cytologic criteria

Pulmonary neuroendocrine tumors (PNET) are histologically subclassified into typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC), and small cell carcinoma (SCLC). The criteria for subclassification in cytological specimens are not well defined. In this study, we reviewed histologically confirmed 18 TC, 8 AC, 10 LCNEC, and 10 SCLC cytologic specimens from 45 patients. The following features were reviewed: small clusters, geographic sheets, trabecular structures, pseudo-rosettes, single cells, doublets, triplets or short cords, papillary-like structures, capillary vasculatures, necrosis, smear background, cell size, cell pleomorphism, amount of cytoplasm, plasmacytoid cells, spindle cells, nuclear atypia, molding, palisading and smearing, chromatin textures, nucleoli, and mitotic figure count. Based on our results, geographic clusters and necrosis were often seen in LCNEC and SCLC; while AC only showed scattered single cell necrosis. TC and AC commonly exhibited trabecular structures. Papillary-like structures and capillary vasculature were only present in TC, AC, and LCNEC. Cells forming doublets, triplets, and short cords were more commonly seen in SCLC and rarely seen in other entities. Plasmacytoid and spindle cells were only seen in TC and AC. Nuclear smearing was not identified in TC, rare in AC, focally present in LCNEC and obvious in SCLC. Mitotic figures were nearly absent in TC, ≤5/10 HPF in AT, and ≥10/10 HPF in SCLC. LCNEC showed a wide span of mitotic count ranging between 2 and 16/10 HPF. In this study, we propose a set of cytological features that are essential for subclassification of PNETs in cytologic specimens.

Histone (H1.5) and Prolmyelocytic Leukemia Zinc Finger (PLZF) Staining Patterns Differentiate Carcinoid from Small Cell Carcinoma in Fine Needle Aspirations (FNA)

Introduction: Typical (TC) and atypical carcinoid (AC) can be difficult to differentiate from high grade neuroendocrine carcinomas, particularly small cell carcinoma (SCC) on cytologic samples and often have overlapping immunohistochemical markers. Promyelocytic Leukemia Zinc Finger (PLZF) and Histone H1.5 (H1.5) have recently been presented as markers of low and high malignant potential, respectively, in tissue biopsies of pulmonary neuroendocrine tumors. PLZF is a transcriptional repressor, mostly studied in leukemia, with tumor suppressor like activity. H1.5, conversely, is associated with active transcription. Materials and Methods: We applied these findings to FNAs not limited to the lung. We retrieved cell blocks from 48 cases including SCC (nZ28; 22 pulmonary, 3 mediastinal, 2 cervical lymph nodes, 1 abdominal wall), TC (nZ19; 12 pulmonary, 2 rectal, 2 liver, 1 pancreas, 1 duodenal, 1 mediastinal), and AC (nZ1 pulmonary) and performed immunohistochemical stains for anti PLZF using concentrations varying from 1:500-1:2000 and H1.5 (conc. 1:800-1:2000). The intensity and location of the stain were recorded and the difference in staining patterns between SCC and carcinoid tumors was examined. Results: H1.5 stained 28 (100%) of the SCC and 5 (25%) of the carcinoids (5 TC; 4 pulmonary, 1 mediastinal, 0 AC) (p<0.01). PLZF was positive in 13 (65%) of the carcinoids (12 TC; 9 pulmonary, 2 rectal, 1 liver, 1 AC) and negative in all of the SCC (p<0.01). H1.5 is very sensitive for SCC (100% sensitivity; 63% specificity). The positive predictive value for SCC staining with H1.5 was 84% with a 100% negative predictive value. PLZF is specific for carcinoid when differentiating it from SCC (100% specificity; 65% sensitivity). The positive predictive value for carcinoid staining with PLZF was 100% with an 80% negative predictive value. H1.5 and PLZF stains are exclusively nuclear. The H1.5 staining was more intense than that for PLZF in all cases. PLZF staining was diffuse in 80%, patchy in 20% of the positive specimens; moderate in 90%, weak in 10%. H1.5 was strong in 77%, weak in 23% of the positive specimens. No difference in staining pattern was noted between pulmonary and extrapulmonary sites. Conclusions: Either positive staining with PLZF or negative staining with H1.5 excludes SCC. PLZF positivity is suggestive of TC or AC; H1.5 positivity is suggestive of SCC. These findings are consistent with previous studies done on pulmonary biopsies. PLZF and H1.5 may be diagnostically useful in cytologic preparations where the differences between carcinoid tumors and SCC are often subtle.

Altered expression of microRNA miR‐21, miR‐155, and let‐7a and their roles in pulmonary neuroendocrine tumors

MicroRNA (miRNA) has a critical effect on tumorigenesis through post-transcriptional modification and is considered to be potential biomarkers for cancer diagnosis and treatment monitoring. We evaluated the expression pattern of three selected miRNAs (miR-21, miR-155, and let-7a) to evaluate their potential roles by quantitative reverse transcription-polymerase chain reaction using formalin-fixed and paraffin-embedded tissues of 63 surgically resected pulmonary neuroendocrine (NE) tumors (19 typical carcinoids (TCs), 6 atypical carcinoids (ACs), 19 large cell NE carcinomas (LCNECs), and 19 small cell lung carcinomas (SCLCs). Control amplification for U6 small nuclear RNA (U6) was performed in all samples. Normalized Ct values were calculated (Ct(Experimental miRNA) -Ct(U6) ) for each case and recorded. The expression levels of miR-21 and miR-155 were significantly higher in high-grade NE carcinomas (LCNECs and SCLCs) than in carcinoid tumors (TCs and ACs) (each P < 0.001). The expression level of miR-21 in carcinoid tumors with lymph node metastasis was significantly higher than in carcinoid tumors without lymph node metastasis (P= 0.010). To the best of our knowledge, the present study is the first to examine the expression patterns of miR-21 and miR-155 as an adjunctive diagnostic tool or clinically relevant biomarkers for pulmonary NE tumors.

Systemic Therapy of Neuroendocrine Tumors of the Lung

SUMMARY Pulmonary neuroendocrine tumors (pNETs) are normally included in trials comprising neuroendocrine tumors (NETs) of different organs of origin. Typical and atypical carcinoids are regarded as low-grade NETs and show low proliferation rates and minor responses with classic chemotherapy regimens. Somatostatin analogs were traditionally applied in patients with carcinoid syndrome and recently also demonstrated tumor response. Recently, novel agents such as sunitinib and everolimus showed improved survival in randomized studies. These trials contained only low numbers of pNETs. Another promising field of targeted therapy in low-grade NETs includes peptide receptor radionuclide therapy. High-grade pNETs include large-cell neuroendocrine carcinoma and small-cell lung cancer. We will discuss large-cell neuroendocrine carcinoma and will address small-cell lung cancer at the end of this review.

Neuroendocrine Tumors of the Lung

Neuroendocrine tumors may develop throughout the human body with the majority being found in the gastrointestinal tract and bronchopulmonary system. Neuroendocrine tumors are classified according to the grade of biological aggressiveness (G1–G3) and the extent of differentiation (well-differentiated/poorly-differentiated). The well-differentiated neoplasms comprise typical (G1) and atypical (G2) carcinoids. Large cell neuroendocrine carcinomas as well as small cell carcinomas (G3) are poorly-differentiated. The identification and differentiation of atypical from typical carcinoids or large cell neuroendocrine carcinomas and small cell carcinomas is essential for treatment options and prognosis. Pulmonary neuroendocrine tumors are characterized according to the proportion of necrosis, the mitotic activity, palisading, rosette-like structure, trabecular pattern and organoid nesting. The given information about the histopathological assessment, classification, prognosis, genetic aberration as well as treatment options of pulmonary neuroendocrine tumors are based on own experiences and reviewing the current literature available. Most disagreements among the classification of neuroendocrine tumor entities exist in the identification of typical versus atypical carcinoids, atypical versus large cell neuroendocrine carcinomas and large cell neuroendocrine carcinomas versus small cell carcinomas. Additionally, the classification is restricted in terms of limited specificity of immunohistochemical markers and possible artifacts in small biopsies which can be compressed in cytological specimens. Until now, pulmonary neuroendocrine tumors have been increasing in incidence. As compared to NSCLCs, only little research has been done with respect to new molecular targets as well as improving the classification and differential diagnosis of neuroendocrine tumors of the lung.

Expression pattern and biologic relevance of Bcl-2 and Mcl-1 in pulmonary neuroendocrine tumors.

7097 Background: Bcl-2 protein overexpression is frequently described in small cell lung cancer (SCLC) but the biological relevance remains unclear. To better elucidate the role of Bcl2 dysfunction in SCLC, we assessed the total and the biologically relevant phosphorylated forms of the anti-apoptotic Bcl2 family members (Bcl2, pBcl-2, Mcl-1, pMcl-1) in pulmonary neuroendocrine (NE) tumors. Methods: We analyzed archival samples of pulmonary carcinoid, SCLC and large-cell NE carcinoma (LCNEC) by immunohistochemistry (IHC) using specific antibodies. Protein expression was assessed by light microscopy using standard scoring of intensity (0, 1, 2 and 3) and percent cell staining and correlated with age, gender, smoking status, tumor type, stage and survival. Significant differences in expression pattern and correlation with clinical variables were assessed by Wilcoxon two-sample test, t-test, ANOVA, Spearman and Pearson correlation coefficients and Cox regression model. Results: We retrieved 77 cases: carcinoid (16) SCLC (41) and LCNEC (20); median age (61 yrs), gender (62% females). Bcl2 and pBcl2 expression was higher in SCLC and LCNEC compared to benign carcinoid tumor. pBcl-2 showed stronger correlation with adverse features including smoking, malignant histology, higher stage at diagnosis and worse survival. No significant association of Mcl1 or pMcl-1 expression with clinical or pathologic parameters. Conclusions: pBcl-2 expression pattern and correlation with adverse prognostic features indicate a key role in SCLC biology and relevance as a therapeutic target. [Table: see text]

Abstract 4159: PTEN nucleo-cytoplasmic protein compartmentalization and gene status are correlated with aggressiveness of pulmonary neuroendocrine tumors

Abstract Introduction: Lung neuroendocrine tumors (NET) comprise typical (TC) and atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Phosphatase and tensin homolog (PTEN) protein is a known cytosolic tumor suppressor with recently described novel nuclear functions. We investigated this differential PTEN protein compartmentalization together with its genomic status in pulmonary NETs. Patients and Methods: A retrospective multicenter cohort of 192 patients with lung NET was investigated on a tissue microarray (TMA, surgical resections = 183/autopsies = 9) by immunohistochemistry (IHC, cytoplasm and nucleus) and fluorescence in-situ hybridization (FISH, nucleus). Results were correlated with markers of neuroendocrine differentiation (synaptophysin, chromogranin A), proliferation (mib-1), cell cycle (p27, cyclin D1) and survival data. Results: The histotypes represented were TC in 58 patients, AC in 42, LCNEC in 32 and SCLC in 60. All NETs showed higher PTEN immunoreactivity in the cytoplasm than in the nucleus, whereby the greatest nucleo-cytoplasmic difference was found for SCLC. In both compartments, immunoreactivity was higher in the carcinoids than in LCNEC and SCLC. Loss of cytosolic or nuclear PTEN protein was correlated with increased mitotic rate, with low synaptophysin or chromogranin A and with PTEN genomic deletion. Loss of nuclear PTEN protein correlated with high nuclear TTF1, whereas loss of cytosolic protein correlated with low p27 and low cyclin D1 (all p-values &amp;lt;0.05). Patients with PTEN genomic deletion or low PTEN immunoreactivity had poorer survivals. Conclusion: PTEN genomic deletion or PTEN protein loss is linked to dedifferentiation and poor prognosis of lung NET. Nucleo-cytoplasmic shuttling of PTEN protein could play a role in the different PTEN inactivation mechanisms. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4159. doi:1538-7445.AM2012-4159