High-grade Neuroendocrine Lung Tumors Research Articles

Chemokine Receptor CXCR4 Radioligand Targeted Therapy Using 177Lutetium-pentixather for Pulmonary Neuroendocrine Cancers.

Intermediate to high-grade lung neuroendocrine tumors (NETs; i.e., atypical carcinoid tumors) and neuroendocrine carcinomas (NECs) are currently difficult to cure. These tumors were found to express the CXCR4 G-protein coupled receptor that can be targeted with radioligands. PCR and flow cytometric analysis of lung NET and NEC cell lines using an anti-CXCR4 antibody demonstrated that all cell lines tested expressed CXCR4. PET/CT imaging with 68Galium-pentixafor in mouse xenografts of NETs and NECs verified tumor targeting that was blocked by a CXCR4 agonist. Clonogenic survival analysis demonstrated a more than additive enhancement of killing when 1 μM auranofin (a thioredoxin reductase inhibitor) was used as a radiosensitizer in combination with 177Lu-pentixather (10 μCi). DMS273 small cell lung cancer xenografts in female nude mice treated with 25 μCi/g 177Lu-pentixather induced inhibition of tumor growth and resulted in an increase in overall survival without causing unacceptable normal tissue toxicities. Immunohistochemical staining of 95 retrospective human samples (containing 90 small cell lung carcinomas) demonstrated 84% CXCR4 positivity. In a multivariable analysis of this cohort that included age, gender, stage, primary site, SSTR2 status, and CXCR4 status, Cox regression models determined that only distant metastasis at presentation (P < 0.01) and a CXCR4 H-score >30 (P = 0.04) were significantly associated with reduced survival. Prospective clinical testing of patient tumors identified CXCR4-positivity in 76% of 21 NECs, 67% of 15 lung NETs (including 8 of 10 atypical carcinoids), and 0% of 25 non-lung NETs (including 5 NETS G3s). These data support the hypothesis that CXCR4-targeted theranostics can be utilized effectively for select NETs and NECs.

Abstract 5305: Delta-like ligand 3 immunohistochemical expression landscape in high-grade lung neuroendocrine tumors

Abstract Background: High-grade lung neuroendocrine tumors are a heterogeneous group of cancers with aggressive common features and a lack of effective therapeutic options. Recently, efforts have been made to identify new targets and drugs to improve clinical outcomes in these patients. Because of its high expression in neuroendocrine tumors compared to normal tissue, delta-like ligand 3 (DLL3) has emerged as a new therapeutic target in this setting.1,2 Targeting DLL3 with the half-life extended bispecific T cell engager (HLE BiTE®) immune therapy, tarlatamab, in a phase 1 clinical trial has demonstrated promising anti-tumor activity in small cell lung cancer (SCLC) patients.3 In order to more precisely guide patient selection and clinical trial design, a better understanding and quantification of DLL3 expression is required. Thus, we investigated DLL3 immunohistochemical expression across SCLC, large cell neuroendocrine carcinoma (LCNEC), and neuroendocrine carcinoma with combined histology (CNEC), and its associations with clinicopathological characteristics. Design: Formalin-fixed and paraffin-embedded surgically resected lung neuroendocrine carcinomas (SCLC, n=17; LCNEC, n=20; CNEC, n=8) were selected based on tissue availability at MD Anderson Cancer Center and stained with a commercially available immunohistochemistry assay for DLL3 (clone SP347, Ventana). Total percentage and intensity of DLL3 expression of neuroendocrine carcinoma cells were scored and the results were presented as H-Score (0-300) and percentage (%) of DLL3 positive tumor cells. We correlated DLL3 expression with clinicopathological characteristics. Results: DLL3 expression was observed in 37/45 (82%) of all cases (SCLC: %, median=65%, 0-100%; H-score, median=95, 0-175; LCNEC: %, median=65%, 0-100%; H-score, median=100, 0-180; CNEC: %, median=55%, 0-95%; H-score, median=90, 0-175). In patients with LCNEC, DLL3 % was higher in male patients (p=0.0500) and former smokers (p=0.0298) compared to females and current smokers, respectively. No other clinicopathological associations were found with age, Tumor-Node-Metastasis (TNM) staging system, recurrence, neoadjuvant therapy or overall survival. Conclusion:Our work confirms that most high-grade neuroendocrine tumors express DLL3 across histology types and TNM stage. Our results suggest that a large subset of patients with high-grade lung neuroendocrine tumors may be a target population of interest for DLL3-targeted therapies.

Prevalence of Delta-Like Protein 3 in a Consecutive Series of Surgically Resected Lung Neuroendocrine Neoplasms.

Delta-like protein 3 (DLL3) is a protein of the Notch pathway, and it is a potential therapeutic target for high-grade lung neuroendocrine tumors (NETs), i.e., small cell lung carcinoma (SCLC) and large cell neuroendocrine carcinoma (LCNEC). However, DLL3 prevalence in lung NETs and its association with clinicopathological characteristics and prognosis remained unclear. We analyzed the immunohistochemical expression of DLL3 and its prognostic role in a consecutive series of 155 surgically resected lung NETs, including typical carcinoid (TC), atypical carcinoid (AC), LCNEC, and SCLC patients. The DLL3 expression was categorized as high (>50% positive tumor cells) or low (<50%). In addition, tumors were categorized by H-score (i.e., percentage of positive cells by staining intensity, ≥150 vs. <150). DLL3 staining was positive in 99/155 (64%) samples, and high DLL3 expression was frequently observed in high-grade tumors. In detail, 46.9% and 75% of SCLC and 48.8% and 53.7% of LCNEC specimens showed a high DLL3 expression by using H-score and percentage of positive tumor cells, respectively. Regarding low-grade NETs, only 4.9% and 12.2% TCs and 19.5% and 24.4% ACs had high DLL3 expression considering H-score and percentage of positive tumor cells, respectively. High DLL3 expression was associated with advanced American Joint Committee on Cancer (AJCC) stage, peripheral location, and chromogranin A expression in high-grade tumors (p < 0.05). In low-grade NETs, high DLL3 expression was associated with female sex, peripheral location, a higher number of mitoses, higher Ki-67 index, presence of necrosis, and pleural infiltration (p < 0.05). No association was observed between high DLL3 expression and overall survival (OS) and disease-free survival (DFS) in high-grade NETs, whereas high DLL3 expression was associated with lower DFS in ACs (p = 0.01). In conclusion, our study demonstrated a high prevalence of DLL3 expression in high-grade lung NET patients and its association with aggressive clinicopathological features. These findings confirm that DLL3 could represent a useful biomarker for target therapy in high-grade tumors. Our results also suggest that the DLL3 expression could identify a subset of AC tumors with more aggressive behavior, thus providing the basis for new therapeutic options in this group of patients.

P47.11 DLL-3 and ASCL-1 Expression Emerge as Promising Therapeutic Targets in High-Grade Neuroendocrine Lung Tumors: A Preliminary Study

P47.11 DLL-3 and ASCL-1 Expression Emerge as Promising Therapeutic Targets in High-Grade Neuroendocrine Lung Tumors: A Preliminary Study

ES17.03 Updates in Squamous Cell Carcinoma and Neuroendocrine Tumors of the Lung

ES17.03 Updates in Squamous Cell Carcinoma and Neuroendocrine Tumors of the Lung

EP1.12-40 Neuroendocrine Tumors of the Lung: Clinico-Pathological Characterization and Follow-Up of Patients Treated at an Argentinean University Hospital in the Last 10 Years

Neuroendocrine tumors (NETs) comprise a heterogeneous group of malignancies that arise from neuroendocrine cells throughout the body, most commonly from the lungs and gastrointestinal tract. Histological characteristics and clinical behaviour define lung NETs, which are classified into four groups: typical (TC) and atypical carcinoids (AC), large-cell neuroendocrine carcinoma (LCNC) and small-cell lung cancer (SCLC). The identification and differentiation of TCs from ACs or LCNECs and SCLC is essential for treatment options and prognosis. We performed a retrospective review of patients with lung NETs treated in our institution in the last decade. We analysed histological confirmed primary lung NETs cases. Demographics, clinical characteristics, imaging, treatment and outcome are described for this patient population. A total of 91 patients with lung NETs were included; 28/91 (30.8%) were lung carcinoids (TC:14 and AT: 14) and 63/91 (69.2%) were high grade lung NETs (SCLC: 54 and LCNC: 9). Comparing low and high grade NETs groups of patients, we could identify differences in the following variables: mean age at diagnosis (51±14 vs 61 ±9 years, p=0.000), mean time from the beginning of symptoms to achievement of pathologic diagnosis (10.5±15.9 vs 3.9 ± 2.6 months, p=0.002), ECOG³2 (14% vs 42%, p=0.001), smokers (57% vs 95%, p=0.000), median % of Ki67 expression (4%, (1-30%) vs 50%, (20-90), p=0.000), history of inflammatory lung disease (18% vs 32%, p=0.028) and presence extra-thoracic disease at diagnosis (47% vs 68%, p=0.000). No statistically differences between groups were observed in: sex, family history of lung cancer, second diagnosis of cancer and body mass index at diagnosis. Functioning carcinoid syndrome was observed in 10% (3/28) of patients with lung carcinoids. For the entire cohort, the median overall survival (OS) was 19 months (IC95%: 14-24 months). The five year OS for patients with lung carcinoids was 62% and 13% for high grade NETs. In our series of lung carcinoids we observed a high frequency of: atypical carcinoids, advanced disease at presentation and smoking history. However, the 5-year overall survival is the expected for this population. More knowledge is needed about this entity in South American countries.

Identification of key modules and hub genes for small-cell lung carcinoma and large-cell neuroendocrine lung carcinoma by weighted gene co-expression network analysis of clinical tissue-proteomes.

Small-cell lung carcinoma (SCLC) and large-cell neuroendocrine lung carcinoma (LCNEC) are high-grade lung neuroendocrine tumors (NET). However, comparative protein expression within SCLC and LCNEC remains unclear. Here, protein expression profiles were obtained via mass spectrometry-based proteomic analysis. Weighted gene co-expression network analysis (WGCNA) identified co-expressed modules and hub genes. Of 34 identified modules, six were significant and selected for protein–protein interaction (PPI) network analysis and pathway enrichment. Within the six modules, the activation of cellular processes and complexes, such as alternative mRNA splicing, translation initiation, nucleosome remodeling and deacetylase (NuRD) complex, SWItch/Sucrose Non-Fermentable (SWI/SNF) superfamily-type complex, chromatin remodeling pathway, and mRNA metabolic processes, were significant to SCLC. Modules enriched in processes, including signal recognition particle (SRP)-dependent co-translational protein targeting to membrane, nuclear-transcribed mRNA catabolic process of nonsense-mediated decay (NMD), and cellular macromolecule catabolic process, were characteristically activated in LCNEC. Novel high-degree hub genes were identified for each module. Master and upstream regulators were predicted via causal network analysis. This study provides an understanding of the molecular differences in tumorigenesis and malignancy between SCLC and LCNEC and may help identify potential therapeutic targets.

Abstract IA28: The genomic landscape of SCLC and other neuroendocrine lung tumors

Abstract Small cell lung cancer (SCLC) accounts for 15% of all lung cancers and belongs to the family of pulmonary neuroendocrine tumors. This tumor subgroup additionally includes large-cell neuroendocrine carcinomas (LCNEC) and pulmonary carcinoids (PCA), which occur in 3% and 2% of all lung cancer patients, respectively. Carcinoids are usually clinically benign, whereas SCLC and LCNEC are characterized as high-grade malignant tumors. Clinical and histologic studies have suggested similarities between SCLC and LCNECs: Both lung tumor subtypes are associated with heavy smoking and reveal an aggressive tumor growth resulting in a poor overall survival. We have performed comprehensive and multilevel genomic profiling on SCLC and LCNECs, including genome, exome, and transcriptome sequencing. SCLC and LCNEC tumors reveal high mutation rates with an average of 9.5 and 8.6 mutations per megabase, respectively. Our sequencing studies have shown that SCLC tumors are characterized by bi-allelic inactivation of TP53 and RB1 in almost 100% of the cases. LCNECs, on the other hand, are composed of two mutually exclusive subgroups, which we categorized as “type I LCNECs” and “type II LCNECs.” Type I LCNECs harbor TP53 and STK11 or KEAP1 alterations. Despite sharing genomic alterations with lung adenocarcinomas and squamous cell carcinomas, type I LCNECs exhibit a high neuroendocrine profile with close similarity to SCLC tumors. Type II LCNECs harbor loss of TP53 and RB1, thus showing genetic resemblance to SCLC. However, these tumors were revealed to be different from the majority of SCLC with reduced levels of neuroendocrine markers, an upregulated immune signaling profile, and high activity of the NOTCH pathway. Conclusively, our studies show marked biologic differences between high-grade neuroendocrine lung tumors and we emphasize the precise distinction of LCNEC subgroups from SCLC. Citation Format: Julie George. The genomic landscape of SCLC and other neuroendocrine lung tumors [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr IA28.

Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors

Pulmonary large-cell neuroendocrine carcinomas (LCNECs) have similarities with other lung cancers, but their precise relationship has remained unclear. Here we perform a comprehensive genomic (n = 60) and transcriptomic (n = 69) analysis of 75 LCNECs and identify two molecular subgroups: “type I LCNECs” with bi-allelic TP53 and STK11/KEAP1 alterations (37%), and “type II LCNECs” enriched for bi-allelic inactivation of TP53 and RB1 (42%). Despite sharing genomic alterations with adenocarcinomas and squamous cell carcinomas, no transcriptional relationship was found; instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC. While type I LCNECs and SCLCs exhibit a neuroendocrine profile with ASCL1high/DLL3high/NOTCHlow, type II LCNECs bear TP53 and RB1 alterations and differ from most SCLC tumors with reduced neuroendocrine markers, a pattern of ASCL1low/DLL3low/NOTCHhigh, and an upregulation of immune-related pathways. In conclusion, LCNECs comprise two molecularly defined subgroups, and distinguishing them from SCLC may allow stratified targeted treatment of high-grade neuroendocrine lung tumors.

Prise en charge thérapeutique des tumeurs neuroendocrines peu différenciées pulmonaires et des carcinomes neuroendocrines digestifs

Poorly differentiated neuroendocrine tumors are rare but their incidence is rising. High-grade neuroendocrine lung tumors, including small-cell lung cancer, are part of this group. Outside of the lung, they most often arise within the gastrointestinal tract (oesophagus, guts and pancreas) and are called neuroendocrine carcinomas. Due to their rarity, very little is known about neuroendocrine carcinomas of the pancreas and the gastrointestinal tract and few studies have been done. Therefore, most therapeutic recommendations are issued from studies on small-cell lung cancers. Histological scores have grown more accurate these past few years: poorly differentiated neuroendocrine tumors regroup various entities such as small-cells, large-cells and mix tumors, which seem to have different prognosis. They are diagnosed at a metastatic state in more than 50% of cases. In localised disease, surgery is performed on selected patients. Adjuvant chemotherapy is administered in poorly differentiated neuroendocrine tumors of the lung and is an option in neuroendocrine carcinomas, without proof of efficacy. If not operable, radiochemotherapy is done for tumors of the lung, rectum, and eosophagus. If the disease is diagnosed at a metastatic state, chemotherapy is administered with a combination of platin salts (cisplatin or carboplatin) and etoposide. In poorly differentiated neuroendocrine tumors of the lung, prophylactic cranial irradiation is performed in localized disease if there is a good response to chemotherapy. Even if these therapies have improved the overall survival, no improvement has been made during the past four decades and the prognosis remains low.

Transcription Factor NFIB Is a Driver of Small Cell Lung Cancer Progression in Mice and Marks Metastatic Disease in Patients

SummarySmall cell lung cancer (SCLC) is an aggressive neuroendocrine tumor, and no effective treatment is available to date. Mouse models of SCLC based on the inactivation of Rb1 and Trp53 show frequent amplifications of the Nfib and Mycl genes. Here, we report that, although overexpression of either transcription factor accelerates tumor growth, NFIB specifically promotes metastatic spread. High NFIB levels are associated with expansive growth of a poorly differentiated and almost exclusively E-cadherin (CDH1)-negative invasive tumor cell population. Consistent with the mouse data, we find that NFIB is overexpressed in almost all tested human metastatic high-grade neuroendocrine lung tumors, warranting further assessment of NFIB as a tumor progression marker in a clinical setting.

Abstract 3182: Tobacco smoke induces pulmonary neuroendocrine alterations in vivo

Abstract Tobacco smoke is the leading cause of lung cancer. High-grade malignant pulmonary neuroendocrine tumors, including small cell lung cancers (SCLCs) and large cell neuroendocrine carcinomas (LCNECs), are almost exclusively associated with tobacco smoking. Unanalogous to most of other lung tumors such as squamous cell carcinomas, adenocarcinoma, adenosquamous carcinoma or carcinoid, no precursor lesions for high-grade lung neuroendocrine tumors have so far been identified. The purpose of the present study was to investigate the effects of tobacco smoke on pulmonary neuroendocrine alterations in phenotypically normal cells in vivo. Male BALB/c mice were exposed to tobacco smoke for 6h/day, 7days/week for 12 weeks. Pulmonary histology, neuroendocrine differentiation as well as MAPK/AP-1 activation were examined in lung tissues. Exposure to tobacco smoke significantly induced expression of neuroendocrine differentiation markers such as chromogranin A, neural cell adhesion molecule/(CD56), synaptophysin, and neuron specific enolase, as demonstrated by immunohistochemistry, Western blotting and real-time PCR. The expression levels of epithelial markers, including E-cadherin, zona ocludens-1, cytokeratin 5 and involucrin, were downregulated by tobacco smoke. Moreover, tobacco smoke significantly increased levels of p-ERK1/2, p-JNK and p-p38, while it suppressed p-ERK5 level. Expression of Jun and Fos proteins were differentially regulated by tobacco smoke. Taken together, the present study provides experimental evidence for the first time that tobacco smoke induces pulmonary neuroendocrine differentiation, shedding new light on the carcinogenic process of pulmonary neuroendocrine tumors. Citation Format: Wei Xie, Zhaofeng Liang, Ying Yin, Chunfeng Xie, Hao Geng, Li Zhao, Rui Wu, Xiaoting Li, Feifei Deng, Jieshu Wu, Shanshan Geng, Mingming Zhu, Jianyun Zhu, Weiwei Zhu, Cong Huang, Caiyun Zhong. Tobacco smoke induces pulmonary neuroendocrine alterations in vivo. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3182. doi:10.1158/1538-7445.AM2014-3182

Complexin-2 (CPLX2) as a potential prognostic biomarker in human lung high grade neuroendocrine tumors

The present study aimed to identify novel useful clinical biomarker of high grade lung neuroendocrine tumors (LNETs). Based on the results of QSTAR LC-MS/MS analysis, we selected complexin-2 (CPLX2) (upregulated 8.7-fold) as a potential biomarker in high grade human LNETs, and validated its expression immunohistochemically in comparison with non-small cell lung carcinomas (NSCLCs). CPLX2 was strongly positive in 16.3% of examined LNETs, but completely negative in all adjacent non-cancerous tissues and NSCLCs. Importantly, positive CPLX2 expression was associated with lymph vessel invasion (P=0.016), pathological stage (P=0.031), and poor disease-specific survival (P=0.004) of patients with LNETs. Preoperative serum CPLX2 level measured by ELISA was significantly elevated in high grade LNETs as compared with %NCs non-cancer controls (NCs) (P=0.002) and NSCLCs (P< 0.001). Receiver operating characteristic (ROC) curve analysis was used for separating high-grade LNET patients from NSCLC patients. The area under the ROC curve (AUC) was 0.825. The calculated optimal cut-off point for CPLX2 level in the serum was 17.8 pg/ml (Youden index=0.591), while sensitivity and specificity was 94.1% and 65.0%, respectively. CPLX2 is suggested as a novel potential clinically useful biomarker for the diagnosis, prognosis and adequate choice of therapy for patients with high grade LNETs.

High grade neuroendocrine lung tumors: Pathological characteristics, surgical management and prognostic implications

Among non-small cell lung cancers (NSCLC), large cell carcinoma (LCC) is credited of significant adverse prognosis. Its neuroendocrine subtype has even a poorer diagnosis, with long-term survival similar to small cell lung cancer (SCLC). Our purpose was to review the surgical characteristics of those tumors. The clinical records of patients who underwent surgery for lung cancer in two French centers from 1980 to 2009 were retrospectively reviewed. We more particularly focused on patients with LCC or with high grade neuroendocrine lung tumors. High grade neuroendocrine tumors were classified as pure large cell neuroendocrine carcinoma (pure LCNEC), NSCLC combined with LCNEC (combined LCNEC), and SCLC combined with LCNEC (combined SCLC). There were 470 LCC and 155 high grade neuroendocrine lung tumors, with no difference concerning gender, mean age, smoking habits. There were significantly more exploratory thoracotomies in LCC, and more frequent postoperative complications in high grade neuroendocrine lung tumors. Pathologic TNM and 5-year survival rates were similar, with 5-year ranging from 34.3% to 37.6% for high grade neuroendocrine lung tumors and LCC, respectively. Induction and adjuvant therapy were not associated with an improved prognosis. The subgroups of LCNEC (pure NE, combined NE) and combined SCLC behaved similarly, except visceral pleura invasion, which proved more frequent in combined NE and less frequent in combined SCLC. Survival analysis showed a trend toward a lower 5-year survival in case of combined SCLC.Therefore, LCC, LCNEC and combined SCLC share the same poor prognosis, but surgical resection is associated with long-term survival in about one third of patients.

Biomarker Discovery for high-grade lung neuroendocrine tumors with poor oucome

Biomarker Discovery for high-grade lung neuroendocrine tumors with poor oucome

Extensive Expression of Collapsin Response Mediator Protein 5 (CRMP5) is a Specific Marker of High-grade Lung Neuroendocrine Carcinoma

The diagnosis of high-grade neuroendocrine tumors has strong clinical relevance because it identifies patients at higher risk of an unfavorable outcome who should receive multimodal treatment. However, these tumors can be mistaken for poorly differentiated nonsmall cell carcinoma or carcinoid lung tumors. In fact, no immunohistochemical marker can currently distinguish between histologic lung subtypes. Because the collapsin response mediator protein (CRMP) family is involved in an autoimmune disease associated with small cell lung carcinoma, we explored the relationship between CRMP5 expression and lung tumor behavior. Using World Health Organization morphologic criteria, 123 lung neuroendocrine tumors and 41 randomly selected non-neuroendocrine tumors were classified. CRMP5 protein expression in tumors, metastases, and healthy lung tissue was assessed using immunostaining method. Strong and extensive CRMP5 expression was seen in 98.6% of high-grade neuroendocrine lung tumors, including small cell lung carcinoma and large cell lung neuroendocrine carcinoma, but not in any of the squamous cell carcinomas or lung adenocarcinomas in our series. In contrast, the majority of low-grade neuroendocrine lung tumors were negative for CRMP5 staining, although weak CRMP5 expression was seen in some, with 2 different staining patterns of either scattered positive cells or small foci of positive cells. Our findings point at CRMP5 as a novel marker for routine pathologic evaluation of lung tumors surgical samples in distinguishing between highly aggressive neuroendocrine carcinoma and the other lung cancers.

E2F-1, Skp2 and cyclin E oncoproteins are upregulated and directly correlated in high-grade neuroendocrine lung tumors

The transcription factor E2F-1 plays a crucial role in the control of cellular growth. We previously reported its differential pattern of expression in human lung tumors. In this study, we have investigated the relationships linking the status of E2F-1 and a mediator of its proteasomal degradation, the S-phase kinase-associated protein 2 (Skp2) F-box protein. Using immunohistochemistry in a series of 129 lung tumors of all histological types, we demonstrate that Skp2 accumulates preferentially in high-grade neuroendocrine (HGNE) lung carcinomas (86%, P<0.0001), and show that Skp2 overexpression is associated with advanced stages (P<0.0001) and nodal metastasis (P<0.0001) in neuroendocrine (NE) lung tumors. Unexpectedly, we observe that Skp2 and E2F-1 expression directly correlates in NE lung tumors (P<0.0001). Moreover, using cellular models, we identify Skp2 as a new E2F-1 transcriptional target. Furthermore, we also provide evidence that Skp2 interacts physiologically with E2F-1 and stimulates its transcriptional activity toward the cyclin E promoter. Consistently, we demonstrate that cyclin E expression directly correlates with Skp2 (P<0.0001) and E2F-1 (P=0.0001) status in NE lung tumors. Overall, our data provide the first evidence of a direct and functional interconnection between the E2F-1, Skp2 and cyclin E oncoproteins in HGNE lung carcinomas.

The P16/cyclin D1/Rb pathway in neuroendocrine tumors of the lung

Rb protein in its hypophosphorylated form acts as a cell cycle regulator for G1 arrest. Both cyclin D1 overexpression and P16INK4 loss of protein produce persistent hyperphosphorylation of Rb with resultant evasion of cell cycle arrest. To better establish the mechanisms of loss of Rb function in neuroendocrine lung tumors, we performed an immunohistochemical analysis of the P16INK4/cyclin D1/Rb pathway in the spectrum of neuroendocrine tumors, including 34 typical carcinoids (TCs), 25 atypical carcinoids (ACs), 42 large cell neuroendocrine carcinomas (LCNECs), and 79 small cell lung carcinomas (SCLCs). Absence of Rb expression was not observed in TCs but was seen in 21% of ACs, 68% of LCNECs, and 87% of SCLCs. P16 was expressed in 91% of TCs, 77% of ACs, 78% of LCNECs, and 93% of SCLCs. Cyclin D1 was overexpressed in 6% of TCs, 20% of ACs, 9.5% of LCNECs, and 1.3% of SCLCs. There was an inverse relationship between Rb and P16 in high-grade tumors (P <0.001) and a direct relationship between cyclin D1 and Rb (P <0.001) in all tumors, demonstrating that P16 and cyclin D1 act exclusively on the Rb pathway for cell cycle regulation. Overall, the Rb pathway (Rb/P16INK4/cyclin D1) was altered more frequently in ACs than in TCs (P = 0.001) and more frequently in LCNECs than in ACs (P = 0.001). Although Rb-negative tumors had shorter survival in the overall group (P <0.001) as a result of lack of Rb in most SCLCs, cyclin D1 overexpression and P16 loss did not influence survival in any individual category. We conclude that Rb pathway of G1 arrest is consistently compromised in high-grade neuroendocrine lung tumors (92%), primarily through loss of Rb protein, and is intact in low-grade TCs. In ACs an intermediate level of alterations (59%) is seen, consistent with their less-aggressive behavior compared with high-grade tumors. The specific profile of the Rb pathway parameters might provide specific therapeutic targets in neuroendocrine lung tumors. HUM PATHOL 34:136-142. Copyright 2003, Elsevier Science (USA). All rights reserved.

Molecular alterations to human chromosome 3p loci in neuroendocrine lung tumors.

The origins of and interrelations between low grade and high grade neuroendocrine lung tumors, typical and atypical carcinoids, and small cell lung carcinoma (SCLC) have not been elucidated. Karyotypic and molecular genetic studies have demonstrated deletions in 3p in 100% of SCLCs and the candidate lung tumor suppressor gene, FHIT, at 3p14.2 is not expressed in the majority of SCLCs. Similar studies of typical and atypical carcinoids could clarify the interrelations among these tumors. For molecular genetic analyses, archival carcinoids and paired normal cells were microdissected from paraffin sections, deparaffinized, and DNA prepared. Oligonucleotide primer pairs for 12 microsatellite markers mapping between 3p14.2 and 3p21.3 were used to amplify allelic DNA fragments from 13 typical and 6 atypical carcinoids. In addition, an independent series of archival sections of carcinoids and SCLCs was tested by immunohistochemistry for expression of Fhit protein. Of the six atypical carcinoids examined, three had lost an allele at all informative markers, whereas one had lost alleles in two distinct regions and two showed allele loss in a subregion of the chromosome region tested. Of the 13 typical carcinoids, 3 showed allele loss at only 1 or 2 loci each. Typical carcinoids, similar to normal lung epithelia, were strongly positive for the cytoplasmic Fhit protein, SCLCs were uniformly negative, and atypical carcinoids appeared to express an intermediate level of Fhit protein. Loss of heterozygosity at 3p14.2-p21.3 is significantly more extensive in all atypical carcinoids. Atypical carcinoids, which exhibit clinicopathologic features intermediate between typical carcinoids and small cell carcinomas and have been considered well differentiated neuroendocrine carcinomas, also are intermediate between typical carcinoids and SCLC on the basis of extent of loss of 3p alleles and reduced expression of Fhit protein.

Molecular biology of neuroendocrine lung tumors

Molecular biology of neuroendocrine lung tumors