Vandetanib versus Cabozantinib in Medullary Thyroid Carcinoma: A Focus on Anti-Angiogenic Effects in Zebrafish Model.

Medullary thyroid carcinoma (MTC) is a tumor deriving from the thyroid C cells. Vandetanib (VAN) and cabozantinib (CAB) are two tyrosine kinase inhibitors targeting REarranged during Transfection (RET) and other kinase receptors and are approved for the treatment of advanced MTC. We aim to compare the in vitro and in vivo anti-tumor activity of VAN and CAB in MTC. The effects of VAN and CAB on viability, cell cycle, and apoptosis of TT and MZ-CRC-1 cells are evaluated in vitro using an MTT assay, DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, respectively. In vivo, the anti-angiogenic potential of VAN and CAB is evaluated in Tg(fli1a:EGFP)y1 transgenic fluorescent zebrafish embryos by analyzing the effects on the physiological development of the sub-intestinal vein plexus and the tumor-induced angiogenesis after TT and MZ-CRC-1 xenotransplantation. VAN and CAB exert comparable effects on TT and MZ-CRC-1 viability inhibition and cell cycle perturbation, and stimulated apoptosis with a prominent effect by VAN in MZ-CRC-1 and CAB in TT cells. Regarding zebrafish, both drugs inhibit angiogenesis in a dose-dependent manner, in particular CAB shows a more potent anti-angiogenic activity than VAN. To conclude, although VAN and CAB show comparable antiproliferative effects in MTC, the anti-angiogenic activity of CAB appears to be more relevant.

Serotonin Pathway in Cancer.

Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic monoamine produced from the essential amino acid tryptophan. Serotonin's role as a neurotransmitter in the central nervous system and a motility mediator in the gastrointestinal tract has been well defined, and its function in tumorigenesis in various cancers (gliomas, carcinoids, and carcinomas) is being studied. Many studies have shown a potential stimulatory effect of serotonin on cancer cell proliferation, invasion, dissemination, and tumor angiogenesis. Although the underlying mechanism is complex, it is proposed that serotonin levels in the tumor and its interaction with specific receptor subtypes are associated with disease progression. This review article describes serotonin's role in cancer pathogenesis and the utility of the serotonin pathway as a potential therapeutic target in cancer treatment. Octreotide, an inhibitor of serotonin release, is used in well-differentiated neuroendocrine cancers, and the tryptophan hydroxylase (TPH) inhibitor, telotristat, is currently being investigated in clinical trials to treat patients with metastatic neuroendocrine tumors and advanced cholangiocarcinoma. Several in vitro studies have shown the anticancer effect of 5-HT receptor antagonists in various cancers such as prostate cancer, breast cancer, urinary bladder, colorectal cancer, carcinoid, and small-cell lung cancer. More in vivo studies are needed to assess serotonin's role in cancer and its potential use as an anticancer therapeutic target. Serotonin is also being evaluated for its immunoregulatory properties, and studies have shown its potential anti-inflammatory effect. Therefore, it would be of interest to explore the combination of serotonin antagonists with immunotherapy in the future.

Cabozantinib can block growth of neuroendocrine prostate cancer patient-derived xenografts by disrupting tumor vasculature.

With the advent of potent second-line anti-androgen therapy, we and others have observed an increased incidence of androgen receptor (AR)-null small cell or neuroendocrine prostate cancer (SCNPC) in metastatic castration-resistant prostate cancer (mCRPC). Our study was designed to determine the effect of cabozantinib, a multi-targeted tyrosine kinase inhibitor that inhibits VEGFR2, MET and RET on SCNPC. Transcriptome analysis of the University of Washington rapid autopsy and SU2C mCRPC datasets revealed upregulated MET and RET expression in SCNPCs relative to adenocarcinomas. Additionally, increased MET expression correlated with attenuated AR expression and activity. In vitro treatment of SCNPC patient-derived xenograft (PDX) cells with the MET inhibitor AMG-337 had no impact on cell viability in LuCaP 93 (MET+/RET+) and LuCaP 173.1 (MET-/RET-), whereas cabozantinib decreased cell viability of LuCaP 93, but not LuCaP 173.1. Notably, MET+/RET+ LuCaP 93 and MET-/RET- LuCaP 173.1 tumor volumes were significantly decreased with cabozantinib treatment in vivo, and this activity was independent of MET or RET expression in LuCaP 173.1. Tissue analysis indicated that cabozantinib did not inhibit tumor cell proliferation (Ki67), but significantly decreased microvessel density (CD31) and increased hypoxic stress and glycolysis (HK2) in LuCaP 93 and LuCaP 173.1 tumors. RNA-Seq and gene set enrichment analysis revealed that hypoxia and glycolysis pathways were increased in cabozantinib-treated tumors relative to control tumors. Our data suggest that the most likely mechanism of cabozantinib-mediated tumor growth suppression in SCNPC PDX models is through disruption of the tumor vasculature. Thus, cabozantinib may represent a potential therapy for patients with metastatic disease in tumor phenotypes that have a significant dependence on the tumor vasculature for survival and proliferation.

Melanoma in the liver: Oxidative stress and the mechanisms of metastatic cell survival.

Metastatic melanoma is a fatal disease with a rapid systemic dissemination. The most frequent target sites are the liver, bone, and brain. Melanoma metastases represent a heterogeneous cell population, which associates with genomic instability and resistance to therapy. Interaction of melanoma cells with the hepatic sinusoidal endothelium initiates a signaling cascade involving cytokines, growth factors, bioactive lipids, and reactive oxygen and nitrogen species produced by the cancer cell, the endothelium, and also by different immune cells. Endothelial cell-derived NO and H2O2 and the action of immune cells cause the death of most melanoma cells that reach the hepatic microvascularization. Surviving melanoma cells attached to the endothelium of pre-capillary arterioles or sinusoids may follow two mechanisms of extravasation: a) migration through vessel fenestrae or b) intravascular proliferation followed by vessel rupture and microinflammation. Invading melanoma cells first form micrometastases within the normal lobular hepatic architecture via a mechanism regulated by cross-talk with the stroma and multiple microenvironment-related molecular signals. In this review special emphasis is placed on neuroendocrine (systemic) mechanisms as potential promoters of liver metastatic growth. Growing metastatic cells undergo functional and metabolic changes that increase their capacity to withstand oxidative/nitrosative stress, which favors their survival. This adaptive process also involves upregulation of Bcl-2-related antideath mechanisms, which seems to lead to the generation of more resistant cell subclones.

Application of contrast-enhanced ultrasonography for large cell neuroendocrine carcinoma in the urinary bladder: a case report.

BACKGROUND: Large cell neuroendocrine carcinoma (LCNEC) of the urinary bladder is an uncommon malignant bladder tumor, and the overall prognosis is poor. Contrast-enhanced ultrasound (CEUS) provides a new effective modality for tumor detection and diagnosis. CASE PRESENTATION: A 30-year-old man complained of repeated painless gross haematuria for half a month. Conventional ultrasound demonstrated a hypoechoic solitary lesion with hyperechoic margins measuring 3.4 × 3.1 cm in the anterior wall of the bladder. Superb microvascular imaging (SMI) showed a strong flow signal in the mass. CEUS revealed that the lesion was characterized by hyper-enhancement in the early phase and hypo-enhancement in the late phase. The entire bladder wall was disrupted by homogeneous hyper-enhanced tumor tissue on CEUS. Time-intensity curves (TICs) showed a rapid wash-in with a high maximum signal intensity (SI) and quick wash-out. Finally, partial cystectomy was performed and the pathological examination confirmed the diagnosis of LCNEC with invasion into the whole layer of the bladder wall. CONCLUSION: This case suggested that CEUS was a valuable imaging method to detect and diagnose LCNEC in the bladder, and that CEUS can provide information related to the depth of wall invasion and the microvasculature.

Clinical routine use of virtual monochromatic datasets based on spectral CT in patients with hypervascularized abdominal tumors - evaluation of effectiveness and efficiency.

BACKGROUND: Virtual monochromatic images (VMI) generated using spectral computed tomography (CT) are promising recently available tools to improve diagnostic performance in oncologic patients. PURPOSE: To investigate if virtual monochromatic datasets are suitable for clinical routine use in patients with hypervascularized abdominal tumors. MATERIAL AND METHODS: A total of 41 patients with hypervascularized hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), or neuroendocrine tumors (NET) were enrolled in the study; 451 CT series were analyzed. In an intra-individual study design, virtual monochromatic datasets of the arterial phase of each scan were computed. Image quality was assessed objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) and subjectively by using five-point Likert-scales. The volume CT dose index (CTDIvol) was taken from each radiation dose report. The increase in reading time was estimated from the increase in the number of images. RESULTS: Intra-individual comparison of the spectral mode in the arterial phase with the portal venous phase revealed no significant increase in the applied dose. SNR, CNRtumor-to-liver , and CNRtumor-to-muscle were significantly increased by lowering virtual monochromatic energy. Subjective image quality scores revealed an increase of contrast in low energy datasets, resulting in significantly higher diagnostic confidence, but an increased image noise at low energies. While diagnostic confidence improved, taking all datasets into account resulted in a significantly longer estimated reading time. CONCLUSION: In clinical practice, the use of low energy VMI improved diagnostic confidence without a significant increase in dose. The main disadvantage is a decrease in efficiency due to longer reading times.

Percutaneous Isolated Hepatic Perfusion: Hemodynamic Monitoring and Goal-Directed Anesthetic Management: A Case Report.

The percutaneous isolated hepatic perfusion utilizes a venovenous bypass to administer high-dose chemotherapy exclusively in the liver, getting depurated through a hemofilter before returning to the systemic circulation. The hepatic perfusion is managed under general anesthesia and invasive monitoring as a result of very abrupt changes in venous return and vascular resistances because of the isolation of the hepatic territory and absorption of circulating catecholamines by the hemofilter. We report a case in which we describe the technique, physiologic implications, anesthetic, and goal-directed hemodynamic management for this procedure.

The Rip1Tag2 Transgenic Mouse Model.

The Rip1Tag2 transgenic mouse model of ß-cell carcinogenesis has been instrumental in studying various aspects of tumor angiogenesis and in investigating the response to anti-angiogenic therapeutics. Thereby, the in-depth assessment of blood and lymphatic vessel phenotypes and functionality represents key experimental analyses. In this chapter, we describe basic protocols to assess tumor blood vessel morphology (pericyte coverage), functionality (perfusion, leakiness, and hypoxia), lymphatic tumor coverage, and tumor cell proliferation and apoptosis based on immunofluorescence microscopy analysis.

The association of intravascular stromal cells with prognosis in high-grade neuroendocrine carcinoma of the lung.

PURPOSE: Histological vascular invasion (VI) is major predictor of recurrence after surgery for several cancer types. We previously reported that VI with abundant stromal cell infiltrates was a negative prognostic factor in lung adenocarcinoma. This study examined whether stromal cell infiltrates within VI are associated with prognosis in high-grade neuroendocrine carcinoma (HGNEC) of the lung. METHODS: We investigated the relationship between the frequency and density of VI and recurrence-free survival (RFS) of 60 resected HGNEC patients without adjuvant chemotherapy. We examined prognostic effects of CD204 (+) macrophages, CD34 (+) microvessels and α-smooth muscle actin (+) myofibroblasts within VI. Correlation between expressions of stem cell-related molecules (ALDH-1, Notch 1, CD44) and epithelial-mesenchymal transition-related molecules (E-cadherin, S100A4) in cancer cells within VI and RFS was also analyzed. RESULTS: Among 60 cases, 51 cases showed VI. Although the presence of VI was a significant predictor for worse RFS (P = 0.04), the frequency and density of VI were not correlated with RFS. The number of CD204 (+) macrophage, CD34 (+) microvessels and α-smooth muscle actin (+) myofibroblasts within VI did not influence on the RFS. On the contrary, cases with higher Notch 1 expression in cancer cells in the VI displayed significantly shorter RFS than lower expression group (7.6 vs. 29.4 months, P = 0.02). CONCLUSIONS: The current study revealed the presence of stromal cells within VI was not significant predictor for recurrence in HGNEC. This suggests that in HGNEC, unlike adenocarcinoma, intravascular stromal cells are not major contributors to metastasis.

New targeted agents in gastroenteropancreatic neuroendocrine tumors.

Neuroendocrine carcinomas are rare neoplasms although of increasing incidence and concern. While traditionally considered of indolent nature, once they progress beyond surgical resectability, the outcome is ultimately fatal for the majority of patients. Somatostatin analogs are useful to control symptoms in functioning tumors and may slow tumor progression in certain disease settings, but sensitivity to conventional cytotoxic chemotherapy is rather limited. In this context, results of the recently published randomized trials with sunitinib and everolimus have demonstrated for the first time that there are agents able to positively impact on the natural history of this complex disease. In this review, we will discuss available data on angiogenesis and mammalian target of rapamycin inhibitors for the treatment of advanced well-differentiated gastroenteropancreatic neuroendocrine tumors.

Angiogenesis and tumor progression in neuroendocrine digestive tumors.

BACKGROUND: Clinical observations suggest that in neuroendocrine digestive tumors a high intratumoral microvascular density is associated with good prognosis. We used an experimental orthotopic xenograft model to analyze the relations between angiogenic activity and tumor progression in this tumor subset. MATERIAL AND METHODS: We compared 2 endocrine cell lines: STC-1, a low vascular endothelial growth factor (VEGF)-producing cell line, and INS-r3, a high VEGF-producing cell line. Tumor cells were grafted in the adventitial layer of the caecal wall of nude mice, sacrificed after 8 wk. RESULTS: At 8 wk, "primary" tumors were present in all animals. STC-1 derived tumors were morphologically moderately differentiated, with high proliferative and apoptotic activities; in contrast, INS-r3 derived tumors were well differentiated, with low proliferative and apoptotic activities. VEGF was expressed in <50% grafted STC-1 cells but in >90% of grafted INS-r3 cells. Microvascular density was significantly higher in INS-r3 derived tumors than in STC-1 derived tumors. All STC-1 derived tumors (n = 8) have invaded the mucosa, in contrast to none of the INS-r3 derived tumors (n = 8); liver metastases were detected in 7/8 animals bearing STC-1 derived tumors and in 0/8 animals with INS-r3 derived tumors, despite the presence of lymph node metastases. CONCLUSIONS: Our experimental data concur with clinical findings to suggest that in well differentiated digestive neuroendocrine tumors angiogenesis is disconnected from tumor progression: the development of a highly vascular tumor microenvironment is correlated with VEGF secretion but is not associated with invasive and metastatic properties; it must therefore be regarded as an indirect marker of differentiation.

Yttrium-90 microsphere radioembolotherapy of hepatic metastatic neuroendocrine carcinomas after hepatic arterial embolization.

Hepatic artery radioembolization was performed in a cohort of patients with unresectable neuroendocrine hepatic metastases who exhibited hepatic progression or toxicity despite technically adequate embolization procedures without other reasonable therapeutic options. Eight patients (five men) with a median age of 55.5 years met the study criteria. Infusions of yttrium-90 resin microspheres were performed in a lobar fashion. Standard clinical, laboratory, and imaging follow-up was performed. Median hepatic parenchyma replacement by tumor was 55% (range, 25%-60%). Twelve (90)Y resin microsphere infusions were performed, and the median delivered activity was 33.25 mCi (range, 23-55 mCi). One partial response, four cases of disease stabilization, and three cases of progressive disease were noted. No cases of radiation-induced liver disease occurred. Median survival times were 14 months (range, 3-15 months) from the time of (90)Y microsphere treatment and 36.5 months (range, 16-105 months) from the time of diagnosis of hepatic metastases. In this cohort, (90)Y microsphere radioembolization of neuroendocrine hepatic metastases was not precluded by previous nonradioactive embolization procedures, but the effectiveness in this population requires further investigation.

Elevated expression of vascular endothelial growth factor correlates with increased angiogenesis and decreased progression-free survival among patients with low-grade neuroendocrine tumors.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a critical proangiogenic factor in solid tumors. However, its expression and role in human neuroendocrine tumor development and progression remains unclear. METHODS: Using immunohistochemistry, VEGF and Sp1 expression patterns were investigated in 50 cases of human gastrointestinal neuroendocrine tumor having various clinicopathologic characteristics. RESULTS: It was found that strong VEGF expression was detected in tumor cells, whereas no or very weak VEGF expression was detected in stromal cells surrounding or within the tumors. The levels of VEGF expression directly correlated with the expression levels of Sp1 and microvessel density. Strong, weak, and negative VEGF expression was observed in 32%, 54%, and 14% of cases, respectively. Compared with the group with negative VEGF expression, VEGF (weak/strong) expression was associated with metastasis (14% versus 58%; P = .03). The median progression-free survival (PFS) durations of patients with strong and weak VEGF expression were 29 months and 81 months, respectively. With a median follow-up duration of 50 months, the median PFS duration for the group with negative VEGF expression has not been reached. Compared with the log-rank test, VEGF expression was associated with poor PFS (P = .02). Using in vitro and in vivo models, human carcinoid cell lines were treated with bevacizumab, a monoclonal antibody targeting VEGF. Bevacizumab did not inhibit the growth of carcinoid cells in vitro but significantly reduced tumor angiogenesis and impaired tumor growth in animals. CONCLUSIONS: The data suggest that overexpression of VEGF promotes the growth of human neuroendocrine tumors in part through up-regulation of angiogenesis.

Laminin alpha2 chain-positive vessels and epidermal growth factor in lung neuroendocrine carcinoma: a model of a novel cooperative role of laminin-2 and epidermal growth factor in vessel neoplastic invasion and metastasis.

Capillaries expressing the laminin alpha2 chain in basement membranes may be considered early developing vessels in normal and neoplastic human tissues. Therefore, we investigated whether up-regulation of this extracellular matrix protein favors transendothelial migration of neoplastic cells and then metastasis. In lung small and large cell neuroendocrine carcinomas, which exhibit a stronger metastatic tendency among carcinomas, laminin alpha2 chain-positive vessels were more numerous than in carcinoid tumors and supraglottis, breast, and lung non-small cell carcinomas, suggesting a direct relationship between these vessels and metastasis. In vitro studies showed that epidermal growth factor (EGF) induced a more efficient migration of the AE-2 lung neuroendocrine carcinoma cell line through the purified laminin alpha2 chain rather than through the laminin beta1 chain and fibronectin. AE-2 cells constitutively expressed all EGF receptors and the alpha6beta1 integrin, which is one of the laminin alpha2 chain receptors. EGF up-regulated alpha6beta1 expression in several tumors. In this regard, we show that EGF increased the chemo-kinetic migration of AE-2 cells through EAHY endothelial monolayers, which was inhibited by the anti-alpha6 integrin chain monoclonal antibody. These data indicate that laminin alpha2 chain and alpha6beta1 may be mutually involved in EGF-dependent migration of AE-2 cells and that laminin alpha2 chain-positive vessels may favor metastasis of EGF-dependent tumors.

Prognostic value of lymphatic and blood vessel invasion in neuroendocrine tumors of the lung.

Few data on the influence of vessel invasion on the progression of neuroendocrine lung tumors are available. Because of the lack of specific markers, previous studies could not reliably discriminate lymphatic and blood vessels. By immunostaining for podoplanin, specific for lymphatic endothelium, and CD34 antigen, we assessed lymphatic and blood vessel invasion in 120 tissue specimens of patients with neuroendocrine lung tumors. Lymphovascular invasion was correlated with clinicopathologic parameters, and its prognostic relevance was evaluated. Lymphatic vessels were identified exclusively at the tumor invasion front, whereas blood capillaries were also seen within tumors. Lymphatic vessel as well as lymphatic and blood vessel invasion was prevalent in patients with high-grade neuroendocrine tumors and advanced tumor stages, closely associated with lymph node metastases (P < 0.0001). In univariate analysis, these two invasion types correlated with decreased disease-free survival (both P < 0.0001), whereas blood vessel invasion alone did not. In multivariate analysis, only tumor grade and lymph node status remained statistically significant factors for prognosis (P = 0.016 and P < 0.0001). Our results suggest that evaluation of lymphatic vessel invasion is important in neuroendocrine lung tumors serving as a prognostic parameter for disease-free survival.

Pancreatic neuroendocrine tumor with extensive vascularisation and parathyroid hormone-related protein (PTHrP)--associated hypercalcemia of malignancy.

We report the case of a 34 year old male presenting with symptomatic hypercalcemia due to excessive PTHrP secretion from a pancreatic neuroendocrine carcinoma with extensive hypervascularization and without any evidence for metastatic disease. In the early phase of the disease conventional chemotherapy with streptozocin and doxorubicin was able to control functional activity as well as tumor growth. However, after 2 years tumor escape was indicated by severe therapy-resistant hypercalcemia. Therapeutic options were reduced due to the excessive tumor vascularization and the patient died from his disease after a short period of intensified therapy. The role of PTHrP in hypercalcemia of malignancy (HHM) and its association with neuroendocrine pancreatic tumors as well as possible therapeutic options are reviewed.