Somatostatin and CXCR4 expression patterns in adenocarcinoma and squamous cell carcinoma of the lung relative to small cell lung cancer

Comparative evaluation of somatostatin and CXCR4 receptor expression in different types of thyroid carcinoma using well-characterised monoclonal antibodies

Background

Papillary and follicular thyroid carcinomas can be treated surgically and with radioiodine therapy, whereas therapeutic options for advanced stage IV medullary and for anaplastic tumours are limited. Recently, somatostatin receptors (SSTs) and the chemokine receptor CXCR4 have been evaluated for the treatment of thyroid carcinomas, however, with contradictory results.

Methods

The expression of the five SSTs and of CXCR4 was assessed in 90 samples from 56 patients with follicular, papillary, medullary, or anaplastic thyroid carcinoma by means of immunohistochemistry using well-characterised monoclonal antibodies. The stainings were evaluated using the Immunoreactivity Score (IRS) and correlated to clinical data. In order to further substantiate the immunohistochemistry results, in serial sections of a subset of the samples receptor expression was additionally examined at the mRNA level using qRT-PCR.

Results

Overall, SST and CXCR4 protein expression was low in all four entities. In single cases, however, very high IRS values for SST2 and CXCR4 were observed. SST2 was the most frequently expressed receptor, found in 38% of cases, followed by SST5 and SST4, found in 14 and 9% of tumours, respectively. SST1 and SST3 could not be detected to any significant extent. CXCR4 was present in 12.5% of medullary and 25% of anaplastic carcinomas. Expression SST3, SST4, SST5 and CXCR4 was positively correlated with expression of the proliferation marker Ki-67. Additionally, a negative interrelationship between SST4 or SST5 expression and patient survival and a positive association between SST3 expression and tumour diameter were observed. qRT-PCR revealed a similar receptor expression pattern to that seen at the protein level. However, probably due to the low overall expression, no correlation was found for the SSTs or the CXCR4 between the IRS and the mRNA values.

Conclusions

SST- or CXCR4-based diagnostics or therapy in thyroid carcinomas should not be considered in general but may be feasible in single cases with high levels of expression of these receptors.

The clinicopathological and prognostic value of CXCR4 expression in patients with lung cancer: a meta-analysis

Background

The C-X-C chemokine receptor 4 (CXCR4) has been suggested to play an important role in several types of cancers and is related to biological behaviors connected with tumor progression. However, the clinical significance and application of CXCR4 in lung cancer remain disputable. Thus, we conducted a meta-analysis to investigate the impact of CXCR4 expression on survival and clinicopathological features in lung cancer.

Methods

Comprehensive literature searches were conducted in PubMed, Embase and Web of Science for relevant studies. We pooled hazard ratios (HRs)/odds ratios (ORs) with 95% confidence intervals (CIs) by STATA 12.0 to evaluate the potential value of CXCR4 expression.

Results

Twenty-seven relevant articles involving 2932 patients with lung cancer were included in our meta-analysis. The results revealed that CXCR4 expression was apparently associated with poor overall survival (OS) (HR 1.61, 95% CI 1.42–1.82) and disease-free survival (HR 3.39, 95% CI 2.38–4.83). Furthermore, a significant correlation with poor OS was obvious in non-small cell lung cancer patients (HR 1.59, 95% CI 1.40–1.81) and in patients showing CXCR4 expression in the cytoplasm (HR 2.10, 95% CI 1.55–2.84) and the membrane (HR 1.74, 95% CI 1.24–2.45). CXCR4 expression was significantly associated with men (OR 1.32, 95% CI 1.08–1.61), advanced tumor stages (T3-T4) (OR 2.34, 95% CI 1.28–4.28), advanced nodal stages (N > 0) (OR 2.34, 95% CI 1.90–2.90), distant metastasis (OR 3.65, 95% CI 1.53–8.69), advanced TNM stages (TNM stages III, IV) (OR 3.10, 95% CI 1.95–4.93) and epidermal growth factor receptor (EGFR) expression (OR 2.44, 95% CI 1.44–4.12) but was not associated with age, smoking history, histopathology, differentiation, lymphatic vessel invasion or local recurrence.

Conclusion

High expression of CXCR4 is related to tumor progression and might be an adverse prognostic factor for lung cancer.

Reassessment of SST4 Somatostatin Receptor Expression Using SST4-eGFP Knockin Mice and the Novel Rabbit Monoclonal Anti-Human SST4 Antibody 7H49L61

Among the five somatostatin receptors (SST1–SST5), SST4 is the least characterized, which is in part due to the lack of specific monoclonal antibodies. We generated a knockin mouse model that expresses a carboxyl-terminal SST4-eGFP fusion protein. In addition, we extensively characterized the novel rabbit monoclonal anti-human SST4 antibody 7H49L61 using transfected cells and receptor-expressing tissues. 7H49L61 was then subjected to immunohistochemical staining of a series of formalin-fixed, paraffin-embedded normal and neoplastic human tissues. Characterization of SST4-eGFP mice revealed prominent SST4 expression in cortical pyramidal cells and trigeminal ganglion cells. In the human cortex, 7H49L61 disclosed a virtually identical staining pattern. Specificity of 7H49L61 was demonstrated by detection of a broad band migrating at 50–60 kDa in immunoblots. Tissue immunostaining was abolished by preadsorption of 7H49L61 with its immunizing peptide. In the subsequent immunohistochemical study, 7H49L61 yielded a predominant plasma membrane staining in adrenal cortex, exocrine pancreas, and placenta. SST4 was also found in glioblastomas, parathyroid adenomas, gastric and pancreatic adenocarcinomas, pheochromocytomas, and lymphomas. Altogether, we provide the first unequivocal localization of SST4 in normal and neoplastic human tissues. The monoclonal antibody 7H49L61 may also prove of great value for identifying SST4-expressing tumors during routine histopathological examinations.

In Vivo Targeting of CXCR4-New Horizons

Given its pre-eminent role in the context of tumor cell growth as well as metastasis, the C-X-C motif chemokine receptor 4 (CXCR4) has attracted a lot of interest in the field of nuclear oncology, and clinical evidence on the high potential of CXCR4-targeted theranostics is constantly accumulating. Additionally, since CXCR4 also represents a key player in the orchestration of inflammatory responses to inflammatory stimuli, based on its expression on a variety of pro- and anti-inflammatory immune cells (e.g., macrophages and T-cells), CXCR4-targeted inflammation imaging has recently gained considerable attention. Therefore, after briefly summarizing the current clinical status quo of CXCR4-targeted theranostics in cancer, this review primarily focuses on imaging of a broad spectrum of inflammatory diseases via the quantification of tissue infiltration with CXCR4-expressing immune cells. An up-to-date overview of the ongoing preclinical and clinical efforts to visualize inflammation and its resolution over time is provided, and the predictive value of the CXCR4-associated imaging signal for disease outcome is discussed. Since the sensitivity and specificity of CXCR4-targeted immune cell imaging greatly relies on the availability of suitable, tailored imaging probes, recent developments in the field of CXCR4-targeted imaging agents for various applications are also addressed.

CXCR4 is a prognostic marker that inhibits the invasion and migration of gastric cancer by regulating VEGF expression

Metastasis is the main cause of poor prognosis of patients with gastric cancer (GC). Thus, current research is focused on identifying biomarkers that can predict the prognosis of patients with GC. C-X-C motif chemokine receptor 4 (CXCR4) and vascular endothelial growth factor (VEGF) have been reported to play important roles in different types of malignancies; however, their role in the prognosis of GC remains unknown. The present study aimed to investigate the potential role of CXCR4 and VEGF in predicting the prognosis of patients with GC. Immunohistochemistry analysis was performed to analyze the expression levels of CXCR4 and VEGF in a GC tissue microarray containing GC tissues and adjacent normal tissues. The association between CXCR4 or VEGF expression levels and the clinicopathological characteristics or survival outcomes were assessed. Furthermore, Transwell and wound healing assays were performed to determine the cell invasive and migratory abilities in vitro. The results demonstrated that CXCR4 promoted AGS cell invasion and migration by regulating VEGF expression. In addition, CXCR4 and VEGF expression levels were significantly upregulated in GC tissues compared with adjacent normal tissues, which was associated with a poorer overall survival (OS). Cox regression analysis demonstrated that both upregulated CXCR4 and VEGF expression were independent negative biomarkers of OS. To the best of our knowledge, the present study was the first to discover that CXCR4 and VEGF exert synergistic roles as efficient prognostic indicators for patients with GC.

Imaging Biomarkers in Lung Cancer with 68Ga-DOTATATE, 18F-Fluoride, and 18F-FDG PET/CT Scans and the Theranostics Paradigm

Lung cancer is the number 1 cause of cancer deaths in the United States. The prognosis is quite grim with the exception of stage 1. When faced with several failed therapeutic regimens and rapid progression of the disease, considering alternative therapies such as radiopharmaceutical therapies may be an option. We describe the case of a 36-y-old man with lung adenocarcinoma who had imaging molecular characterization of his disease with ¹⁸F-FDG, ⁶⁸Ga-DOTATATE, and ¹⁸F-fluoride PET/CT scans that were able to shed some light on molecular characterization of his disease and serve as a guide to potential targeted or personalized radiopharmaceutical therapeutic options.

The mechanism of m6A methyltransferase METTL3-mediated autophagy in reversing gefitinib resistance in NSCLC cells by β-elemene

N⁶-methyladenosine (m⁶A) modification can alter gene expression by regulating RNA splicing, stability, translocation, and translation. Emerging evidence shows that m⁶A modification plays an important role in cancer development and progression, including cell proliferation, migration and invasion, cell apoptosis, autophagy, and drug resistance. Until now, the role of m⁶A modification mediated autophagy in cancer drug resistance is still unclear. In this study, we found that m⁶A methyltransferase METTL3-mediated autophagy played an important role in reversing gefitinib resistance by β-elemene in non-small cell lung cancer (NSCLC) cells. Mechanistically, in vitro and in vivo studies indicated that β-elemene could reverse gefitinib resistance in NSCLC cells by inhibiting cell autophagy process in a manner of chloroquine. β-elemene inhibited the autophagy flux by preventing autophagic lysosome acidification, resulting in increasing expression of SQSTM1 and LC3B-II. Moreover, both β-elemene and gefitinib decreased the level of m⁶A methylation of gefitinib resistance cells. METTL3 was higher expressed in lung adenocarcinoma tissues than that of paired normal tissues, and was involved in the gefitinib resistance of NSCLC cells. Furthermore, METTL3 positively regulated autophagy by increasing the critical genes of autophagy pathway such as ATG5 and ATG7. In conclusion, our study unveiled the mechanism of METTL3-mediated autophagy in reversing gefitinib resistance of NSCLC cells by β-elemene, which shed light on providing potential molecular-therapy target and clinical-treatment method in NSCLC patients with gefitinib resistance.

Evaluation of a New 177Lu-Labeled Somatostatin Analog for the Treatment of Tumors Expressing Somatostatin Receptor Subtypes 2 and 5

Targeted radionuclide therapy of somatostatin receptor (SST)-expressing tumors is only partially addressed by the established somatostatin analogs having an affinity for the SST subtype 2 (SST2). Aiming to target a broader spectrum of tumors, we evaluated the bis-iodo-substituted somatostatin analog ST8950 ((4-amino-3-iodo)-d-Phe-c[Cys-(3-iodo)-Tyr-d-Trp-Lys-Val-Cys]-Thr-NH2), having subnanomolar affinity for SST2 and SST5, labeled with [177Lu]Lu3+ via the chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). Human Embryonic Kidney (HEK) cells stably transfected with the human SST2 (HEK-SST2) and SST5 (HEK-SST5) were used for in vitro and in vivo evaluation on a dual SST2- and SST5-expressing xenografted mouse model. natLu-DOTA-ST8950 showed nanomolar affinity for both subtypes (IC50 (95% confidence interval): 0.37 (0.22-0.65) nM for SST2 and 3.4 (2.3-5.2) for SST5). The biodistribution of [177Lu]Lu-DOTA-ST8950 was influenced by the injected mass, with 100 pmol demonstrating lower background activity than 10 pmol. [177Lu]Lu-DOTA-ST8950 reached its maximal uptake on SST2- and SST5-tumors at 1 h p.i. (14.17 ± 1.78 and 1.78 ± 0.35%IA/g, respectively), remaining unchanged 4 h p.i., with a mean residence time of 8.6 and 0.79 h, respectively. Overall, [177Lu]Lu-DOTA-ST8950 targets SST2-, SST5-expressing tumors in vivo to a lower extent, and has an effective dose similar to clinically used radiolabeled somatostatin analogs. Its main drawbacks are the low uptake in SST5-tumors and the persistent kidney uptake.

Prognostic impact of somatostatin receptor expression in advanced bladder cancer

INTRODUCTION AND OBJECTIVES

Somatostatin receptors (SSTR) recently have been identified as potential targets for treatment of solid tumors. Furthermore, they have been shown to be of high relevance for tumor biology and prognosis in various types of cancer. However, there is a lack of clinical data for SSTR in bladder cancer (BC). Aim of this study was to determine the expression of all relevant somatostatin receptor subtypes in benign urothelium and tumor tissue of patients with muscle invasive BC. Furthermore, their potential role as prognostic factor for cancer-specific survival (CSS) and overall survival (OS) was evaluated.

METHODS

The collective included BC and benign urothelium tissue of 103 patients (Median age 69; range 32-84, 79 male, 24 female) who underwent a radical cystectomy. A tissue microarray with subsequent immunohistochemical staining was used to assess membranous expression of SSTR1-5. Results were correlated to clinical and histopathological data as well as CSS and OS.

RESULTS

Expressions of SSTR1-4 were significantly decreased in BC compared to benign urothelium (P < 0.002 each), whereas SSTR5 expression was increased (P = 0.0017). Expression of SSTR1 was associated with organ-confined disease (≤pT2) (P = 0.0477). No correlation between SSTR1-5 expression and N- and M-stage was observed. Univariate analyses showed a significantly longer CSS and OS in patients with high expression of SSTR3 (P = 0.0316 and 0.0044). Multivariate analyses confirmed SSTR3 expression as independent marker of improved CSS and OS (P = 0.0324 and 0.0076).

CONCLUSIONS

The majority of somatostatin receptor subtypes exhibit decreased expression in BC compared to benign bladder tissue. Expression of SSTR3 is an indicator for favorable prognosis in patients with muscle-invasive BC. These results support preclinical investigations using somatostatin receptor analogues such as octreotide to influence BC growth.

Evaluation of Somatostatin and CXCR4 Receptor Expression in a Large Set of Prostate Cancer Samples Using Tissue Microarrays and Well-Characterized Monoclonal Antibodies

BACKGROUND: Prostate cancer (PCa) is the most common type of cancer among men in Western countries. Despite numerous therapeutic options, few treatments are available for patients with end-stage disease. In the present study, different somatostatin receptors (SSTs) and the chemokine receptor CXCR4 were evaluated for their suitability as novel therapeutic targets in PCa. MATERIALS AND METHODS: The expression of SST subtypes 1, 2A, 3, and 5 and of CXCR4 was evaluated in 276 PCa tumor samples on a tissue microarray (TMA) in 23 whole-block tumor samples and in 3 PCa cell lines by immunohistochemistry using well-characterized monoclonal antibodies. RESULTS: Overall, the frequency and intensity of expression of SSTs and CXCR4 were very low among the PCa samples investigated. Specifically, SST5, SST2A, and SST3 were expressed, albeit at low intensity, in 10.5%, 9.1%, and 0.7% of the TMA samples, respectively. None of the TMA samples showed SST1 or CXCR4 expression. Only a single small-cell-type neuroendocrine carcinoma that was coincidentally included among the whole-block samples exhibited strong SST2A, SST5, and CXCR4 and moderate SST3 expression. Independent of the tumor cells, the tumor capillaries in many of the PCa samples were strongly positive for SST2A, SST3, SST5, or CXCR4 expression. SST expression in the tumor cells was associated with advanced tumor grade and stage. CONCLUSION: Overall, SST and CXCR4 expression levels are clearly of no therapeutic relevance in PCa. SST- or CXCR4-based therapy might be feasible, however, in rare cases of small-cell-type neuroendocrine carcinoma of the prostate.

Clinicopathologic significance of CXCR4 expressions in patients with esophageal squamous cell carcinoma

AIMS

This study was designed to investigate the biological function of CXCR4 in esophageal squamous cell carcinoma and to explore the underlying mechanism to provide potential targets for esophageal squamous cell carcinoma.

METHODS

A total of 101 patients with esophageal squamous cell carcinoma were included, and the relationship between CXCR4 and clinicopathological factors was analyzed. Laser scanning confocal microscopy was used to observe numbers of autophagosomes in TE-1 cell line and the ability of proliferation and invasion were evaluated meanwhile.

RESULTS

CXCR4 is overexpressed in ESCC specimens and is associated with poor differentiation and lymphocyte metastasis. In the survival analysis, CXCR4 predicted a poor overall survival prognosis. The number of autophagosomes in the siR-CXCR4 group was decreased compared with negative group (P < 0.05), while was increased in the pcDNA3.1-CXCR4 group (P < 0.05).Western blot result show upregulation of LC3II, the ratio of LC3II/LC3I and Beclin1 in pcDNA3.1-CXCR4 group and decreased expression of LC3II, the ratio of LC3II/LC3I and Beclin1 in siR-CXCR4 group. Transwell assay show CXCR4 overexpression promote the invasion of TE-1 cells and was attenuated by autophagy inhibitor 3-Methyladenine.On the contrary, invasion cell numbers decreased in siR-CXCR4 group and was rescued by autophagy inducer Rapamycin.

CONCLUSION

CXCR4 is an indicator of poor prognosis for ESCC. CXCR4 promote autophagy and regulate cell invasion through autophagy in ESCC. Our study provides new insights for the treatment of esophageal squamous cell carcinoma and CXCR4 may serve as a therapeutic target for ESCC.

Effects of VEGFR1+ hematopoietic progenitor cells on pre-metastatic niche formation and in vivo metastasis of breast cancer cells

The pre-metastatic niche has been shown to play a critical role in tumor metastasis, and its formation is closely related to the tumor microenvironment. However, the underlying molecular mechanisms remain unclear. In the present study, we successfully established a mouse model of lung metastasis using luciferase-expressing MDA-MB-435s cells. In this model, recruitment of vascular endothelial growth factor receptor-1 (VEGFR1)⁺CD133⁺ hematopoietic progenitor cells (HPCs) was gradually increased in lung but gradually decreased after the formation of tumor colonies in lung. We also established a highly metastatic MDA-MB-435s (MDA-MB-435s-HM) cell line from the mouse model. Changes in protein profiles in different culture conditions were investigated by protein microarray analysis. The levels of CXC chemokine ligand 16, interleukin (IL)-2Rα, IL-2Rγ, matrix metalloproteinase (MMP)-1, MMP-9, platelet-derived growth factor receptor (PDGFR)-α, stromal cell-derived factor (SDF)-1α, transforming growth factor (TGF)-β, platelet endothelial cell adhesion molecule (PECAM)-1 and vascular endothelial (VE)-cadherin were significantly greater (> fivefold) in the culture medium from MDA-MB-435s-HM cells than in that from MDA-MB-435s cells. Moreover, the levels of MMP-9, PDGFR-α, and PECAM-1 were significantly greater in the co-culture medium of MDA-MB-435s-HM cells and CD133⁺ HPCs than in that from MDA-MB-435s-HM cells. Differentially expressed proteins were validated by enzyme-linked immunosorbent assay, and expression of their transcripts was confirmed by quantitative real-time polymerase chain reaction. Moreover, inhibition of MMP-9, PDGFR-α, and PECAM-1 by their specific inhibitors or antibodies significantly decreased cell migration, delayed lung metastasis, and decreased recruitment of VEGFR1⁺CD133⁺ HPCs into lung. Intra-hepatic growth of HPCs enhanced the invasive growth of MDA-MB-435s-HM cells in the liver. Our data indicate that VEGFR1⁺CD133⁺ HPCs contribute to lung metastasis.