Primary Neuroendocrine Neoplasia of the Liver.

ABSTRACT: The presence of primary neuroendocrine tumors in the liver is still a matter of controversy. We present a case of a somatostatin-receptor-positive mass of the liver in the 68Ga-DOTATOC PET/CT. No other primary tumor was found after conventional imaging, endoscopically, and after liver-segment resection. Immunohistochemically, a constellation of findings was found to be compatible with a primary neuroendocrine neoplasm of the liver.

Mechanisms of Targeting the MDM2-p53-FOXM1 Axis in Well-Differentiated Intestinal Neuroendocrine Tumors.

BACKGROUND/AIMS: The tumor suppressor p53 is rarely mutated in gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) but they frequently show a strong expression of negative regulators of p53, rendering these tumors excellent targets for a p53 recovery therapy. Therefore, we analyzed the mechanisms of a p53 recovery therapy on intestinal neuroendocrine tumors in vitro and in vivo. METHODS: By Western blot and immunohistochemistry, we found that in GEP-NEN biopsy material overexpression of MDM2 was present in intestinal NEN. Therefore, we analyzed the effect of a small-molecule inhibitor, nutlin-3a, in p53 wild-type and mutant GEP-NEN cell lines by proliferation assay, flow cytometry, immunofluorescence, Western blot, and by multiplex gene expression analysis. Finally, we analyzed the antitumor effect of nutlin-3a in a xenograft mouse model in vivo. During the study, the tumor volume was determined. RESULTS: The midgut wild-type cell line KRJ-I responded to the treatment with cell cycle arrest and apoptosis. By gene expression analysis, we could demonstrate that nutlins reactivated an antiproliferative p53 response. KRJ-I-derived xenograft tumors showed a significantly decreased tumor growth upon treatment with nutlin-3a in vivo. Furthermore, our data suggest that MDM2 also influences the expression of the oncogene FOXM1 in a p53-independent manner. Subsequently, a combined treatment of nutlin-3a and cisplatin (as chemoresistance model) resulted in synergistically enhanced antiproliferative effects. CONCLUSION: In summary, MDM2 overexpression is a frequent event in p53 wild-type intestinal neuroendocrine neoplasms and therefore recovery of a p53 response might be a novel personalized treatment approach in these tumors.

Proteasome inhibitor bortezomib enhances the effect of standard chemotherapy in small cell lung cancer.

Small cell lung cancer (SCLC) is an aggressive cancer showing a very poor prognosis because of metastasis formation at an early stage and acquisition of chemoresistance. One key driver of chemoresistance is the transcription factor Forkhead box protein M1 (FOXM1) that regulates cell cycle proliferation, maintenance of genomic stability, DNA damage response, and cell differentiation in numerous tumor entities. In this study we investigated the role of FOXM1 in SCLC progression and analyzed the effect of FOXM1 inhibition using two proteasome inhibitors, bortezomib and siomycin A. FOXM1 was strongly expressed in patient-derived SCLC samples (n=123) and its nuclear localization was associated with the proliferation marker Ki-67. Both proteasome inhibitors successfully inhibited FOXM1 expression leading to a significantly reduced proliferation and a decreased mitotic rate along with cell cycle arrest and apoptosis induction. These effects were further enhanced by addition of bortezomib to standard chemotherapy. Treatment of mice bearing chemoresistant SCLC xenografts with bortezomib reduced the mean bioluminescence signal of tumors by 54%. Similarly, treatment with cisplatin as a standard chemotherapy reduced the mean bioluminescence signal of tumors by 58%. However, in combination with standard chemotherapy bortezomib further reduced the mean bioluminescence signal by 93% (p=0.0258). In conclusion, we demonstrate the effect of bortezomib in inhibiting FOXM1 expression and thus in sensitizing resistant SCLC cells to standard chemotherapy. Thus, addition of bortezomib to standard chemotherapy might potently improve SCLC therapy, particularly in an extensive cancer stage.

131I and 124I Accumulation in a Thymic Cyst.

A 65-year-old woman presented with increased human thyroglobulin (3.3 ng/mL) 5 years after resection of a papillary thyroid carcinoma and successful I radioiodine therapy. I whole-body scintigraphy showed a small focus ventrally in the right lower neck, leading to suspicion of a papillary thyroid carcinoma recurrence. I-PET/CT and real-time PET/US fusion matched to a small hypoechoic/anechoic ovoid structure situated between the right sternoclavicular joint and the brachiocephalic trunk. After surgical resection, histology allowed a diagnosis of thymic cyst. A follow-up I whole-body scintigraphy showed no residual iodine accumulation.

FOXM1: A novel drug target in gastroenteropancreatic neuroendocrine tumors.

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are heterogeneous tumors that need to be molecularly defined to obtain novel therapeutic options. Forkheadbox protein M1 (FOXM1) is a crucial transcription factor in neoplastic cells and has been associated with differentiation and proliferation. We found that FOXM1 is strongly associated with tumor differentiation and occurrence of metastases in gastrointestinal NENs. In vitro inhibition by the FOXM1 inhibitor siomycin A led to down-regulation of mitotic proteins and resulted in a strong inhibitory effect. Siomycin A decreased mitosis rate, induced apoptosis in GEP-NEN cell lines and exerts synergistic effects with chemotherapy. FOXM1 is associated with clinical outcome and FOXM1 inhibition impairs survival in vitro. We therefore propose FOXM1 as novel therapeutic target in GEP-NENs.

Diagnostic and prognostic impact of desmocollins in human lung cancer.

OBJECTIVE: Desmosomes are intercellular junctions that confer strong cell-cell adhesion. Two main members of desmosomal cadherins, desmogleins (DSGs) and desmocollins (DSCs), are involved in carcinogenesis. However, their role in human lung cancer remained elusive. The aims of this study were to analyse the expression of DSCs and to evaluate their clinical application in lung cancer. METHODS: The expression of DSC1-3 mRNAs was analysed by RT-PCR. The methylation status of DSCs was analysed by demethylation tests and bisulphite sequencing. Protein expression of DSCs in primary lung cancer was evaluated by immunohistochemistry on tissue microarrays. RESULTS: DSC1-3 mRNAs were downregulated in lung cancer cells, and the expression was restored in four out of seven cell lines, respectively, after 5-aza-2'-deoxycytidine treatment. A heterogeneous methylation pattern was detected by bisulphite sequencing in exon 1 of DSC2 and DSC3. In 199 patients with primary lung cancer, we found that lower protein expression of DSC1 was significantly linked to worse tumour differentiation (p=0.017), DSC3 proteins were more expressed in squamous cell carcinoma (SCC) compared with adenocarcinoma (ADC) (p<0.001), and reduced expression of DSC1 and DSC3 was significantly correlated with poor clinical outcome (p=0.045 and p=0.007, respectively). CONCLUSIONS: Our data suggest that downregulation of DSC1-3 may be explained by DNA methylation, DSC1 may be a marker for tumour differentiation, DSC3 has a potential diagnostic value in subclassification of non-small cell lung carcinoma into SCC and ADC, and furthermore, DSC1 and DSC3 may be prognostic markers for lung cancer.

FGFR1 expression and gene copy numbers in human lung cancer.

FGFR1 is a receptor tyrosine kinase of which the ligands belong to the fibroblast growth factor family. To evaluate the significance of FGFR1 in lung cancer, we analysed tumours by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Tissue microarrays were constructed containing 380 lung cancer samples including squamous cell carcinomas (SCC), adenocarcinomas (ADC), non-small cell lung cancer not otherwise specified, metastases, neuroendocrine tumours, large cell lung cancer and small cell lung cancer. FGFR1 expression was analysed by IHC and scored semi-quantitatively by a four-tier approach (0, 1, 2, 3). Using dual-colour interphase FISH with probes specific for the locus on 8p12 and the centromere of chromosome 8 (CEN8), copy numbers of FGFR1 were determined. High expression of FGFR1 was associated with increased FGFR1 gene copy numbers in squamous cell carcinoma (p < 0.001). The FGFR1 locus was equally affected by copy number losses and gains. The higher FGFR1 gene copy numbers in SCC compared to ADC did not reach statistical significance. High copy number amplification of FGFR1 was a very rare event, the FGFR1/CEN8 signal ratio reaching a maximum value of 2.75. There were no significant associations between FGFR1 and clinicopathological parameters. Fibroblast growth factor signalling represents an interesting therapeutic target in lung cancer. However, the pathways are complex with potential oncogenic and anti-oncogenic activities. Our data may help to define criteria for selecting patients that may benefit from these new therapeutic options.

Concomitant lung and gastroenteropancreatic neuroendocrine tumors and the value of gallium-68 PET/CT.

Well-differentiated neuroendocrine tumors (NETs) of the lung occur as typical and atypical carcinoids. Little is known about the biology of these tumors in respect of their ability to metastasize or the probability of development of concomitant neuroendocrine tumors. Here we report a patient diagnosed with a second neuroendocrine tumor of the ileum 4 years after curative resection of a typical carcinoid of the left lung. The intestinal neuroendocrine tumor was successfully detected by gallium-68 based somatostatin receptor positron emission tomography (PET)/computed tomography (CT) and surgically removed using gamma probe detection based on the same labeling. This case report underlines the utility of somatostatin receptor PET/CT based detection and follow-up of NETs.