Phase I trial of vandetanib in combination with gemcitabine and capecitabine in patients with advanced solid tumors with an expanded cohort in pancreatic and biliary cancers

BACKGROUND

Vandetanib is a multitargeted tyrosine kinase inhibitor that affects vascular endothelial growth factor receptor (VEGF), epidermal growth factor (EGF), and rearranged during transfection (RET) mediated receptors which are important for growth and invasion of biliary and pancreatic cancers. This phase I study evaluated the safety profile of vandetanib in combination with standard doses of gemcitabine and capecitabine in order to determine the maximum tolerated dose (MTD).

METHODS

In this single center phase I trial, patients received gemcitabine intravenously (i.v.) at 1000 mg/m2 days 1, 8, 15 in a 28 day cycle, capecitabine orally at 850 mg/m2 twice daily on days 1-21, and escalating doses of vandetanib (200 or 300 mg orally daily). Once the MTD was defined, an expansion cohort of patients with advanced biliary cancers and locally advanced or metastatic pancreatic cancer was enrolled. Blood samples were also collected at predetermined time points for biomarker analysis.

RESULTS

Twenty-three patients were enrolled: 9 in the dose escalation and 14 in the dose expansion cohort. One dose limiting toxicity (DLT), of grade 4 neutropenia, occurred in the 200 mg vandetanib cohort. The most common adverse effects were diarrhea (39 %), nausea and vomiting (34%), and rash (33%). There were 3 partial responses and stable disease of >2 months (range 2-45, median 5) was observed in 15/23 patients. There was no association between changes in biomarker analytes and disease response.

CONCLUSION

The combination of gemcitabine, capecitabine and vandetanib is well tolerated at the recommended phase II dose of gemcitabine 1000 mg/m2 weekly for three consecutive weeks, capecitabine 850 mg/m2 BID days 1-21, and vandetanib 300 mg daily, every 28 days. This combination demonstrated promising activity in pancreaticobiliary cancers and further evaluation is warranted in these diseases. NCT00551096.

Association between BRAF and RAS mutations, and RET rearrangements and the clinical features of papillary thyroid cancer

OBJECTIVE

To evaluate the significance of BRAF (V600E) and Ras mutations, and RET rearrangements in papillary thyroid cancer (PTC) in the South central region of China.

METHODS

We included patients from Union hospital's pathology archive diagnosed with PTC and meeting the criteria for BRAF mutation, RAS mutation, and RET rearrangement testing. Medical records were analyzed for BRAF and RAS mutation status, RET rearrangements (positive or negative), and a list of standardized clinicopathologic features.

RESULTS

Positive BRAF mutation was found to be significantly associated with age and extrathyroidal extension (P=0.011 and P=0.013, respectively). However, there was no significant association between BRAF mutation and sex, tumor size, histological subtype, multifocality, or accompanying nodular goiter and Hashimoto's. On the other hand, none of these characteristics of PTC were been found to be associated with RAS mutation. Additionally, the frequency of RET rearrangements was higher in patients ≤45 years old than that in patients >45 years old.

CONCLUSIONS

We demonstrated that the BRAF (V600E) mutation slightly correlated with the clinicopathological characteristics of PTC in the Han population. Furthermore, neither RAS mutation nor RET rearrangements were found to be associated with the clinicopathological characteristics of PTCs. Our work provides useful information on somatic mutations to predict the risk of PTC in different ethnic groups.

Metastatic papillary thyroid carcinoma to the nose: report and review of cutaneous metastases of papillary thyroid cancer

Background:

Metastatic papillary thyroid carcinoma typically appears in local lymph nodes. Skin metastases are rare.

Purpose:

A man with progressive metastatic papillary thyroid carcinoma who developed a cutaneous metastasis on his nose is described. The clinical manifestations of metastatic papillary thyroid carcinoma to skin are reviewed.

Methods:

PubMed was used to search the following terms, separately and in combination: basal, cancer, carcinoma, cell, cutaneous, kinase, inhibitor, metastases, nose, papillary, rearranged during transfection, receptor, RET, thyroid, tyrosine, vandetanib.

Results:

Pathologic changes observed on the biopsy of the man’s nose lesion were similar to those of his original cancer. Genomic evaluation of the tumor revealed an aberration involving the rearranged during transfection (RET) receptor tyrosine kinase. The residual tumor was excised. Treatment with vandetanib, a RET inhibitor was initiated; his metastatic disease has been stable, without symptoms or recurrent cutaneous metastasis, for 2 years following the discovery of his metastatic nose tumor.

Conclusions:

Papillary thyroid carcinoma with skin metastases is rare. Nodules usually appear on the scalp or neck; the thyroidectomy scar is also a common site. Metastatic tumor, albeit infrequently, can present as a nose lesion. The prognosis for patients with cutaneous metastases from papillary thyroid carcinoma is poor. However, with the ability to test the tumor for genomic aberrations, molecular targeted therapies—such as tyrosine kinase inhibitors—may provide extended survival in these individuals.

Rapid dissemination of RET-transgene-driven melanoma in the presence of non-obese diabetic alleles: Critical roles of Dectin-1 and Nitric-oxide synthase type 2

Mice transgenic for the RET oncogene provide a remarkable model for investigating the mechanisms underlying the promotion and the development of melanoma. This model was established on the C57BL/6 genetic background. In the present study, we investigated an effect of the strongly proinflammatory and autoimmune genetic makeup of the non-obese diabetic (NOD) strain. We bred (NODxB6)F1 mice and backcrossed them with NOD mice. F1 mice and mice at subsequent generations of backcrossing showed marked acceleration of tumor development, in particular with a more frequent and earlier extension of the primary uveal melanoma. In close relation with this severe evolution, we observed a profound drop in Dectin-1 expression on CD11b(+)Ly6G(+) granulocytic myeloid cells correlating with an expansion of CD4(+)Foxp3(+) T regulatory cell and of interferon(IFN)γ-producing CD8(+) T cell subsets in tumors. IFNγ is a major inducer of the type 2 nitric-oxide synthase (Nos2) gene whose products are known to be tumorigenic. Germline inactivation of the Nos2 gene was associated with a dramatically improved tumor prognosis and a restoration of Dectin-1 expression on myeloid cells. Moreover, in vivo treatment of (NODxB6)F1.RET(+) mice with curdlan, a glucose polymer that binds Dectin-1, prevented tumor extension and was associated with marked reduction of the CD4(+)Foxp3(+) T cell subset. These observations highlight the (NODxB6)F1.RET(+) mice as a new model to investigate the role of the immune system in the host-tumor relationship and point to Dectin-1 and Nos2 as potentially promising therapeutic targets.

NSCLC: An Update of Driver Mutations, Their Role in Pathogenesis and Clinical Significance

Lung cancer is the most common malignancy in the US and causes the most cancer-related deaths. Non-small-cell lung carcinoma (NSCLC) accounts for the majority of cases. NSCLC historically was considered one entity, reflected by platinum-based therapy as the standard of care; however, with the discovery of EGFR mutations and ALK rearrangements, the landscape of treatment has become more personalized reflecting genomic heterogeneity. The molecular basis for tumor genesis was recognized and became a new method of classification. The availability of tumor sequencing and testing for these mutations is also becoming more accessible outside of major academic institutions. Targeted therapies offer alternatives to dangerous cytotoxic chemotherapy with equal or better efficacy. With these changes, driver mutations will play an increasing role in the diagnosis and treatment of NSCLC. In this review we will examine the characteristics of several NSCLC driver mutations and gene rearrangements and emerging data on therapies directed against them.

Contactin 1 as a potential biomarker promotes cell proliferation and invasion in thyroid cancer

Contactin 1 (CNTN1) as a member of the immunoglobulin superfamily plays important role in the development of nervous system. Recent studies find that elevated CNTN1 can promote the metastasis of cancer. However, the expression and function of CNTN1 in thyroid cancer are still unknown. Here, we firstly find CNTN1 is a new gene which can be regulated by RET/PTC3 (Ret proto-oncogene and Ret-activating protein ELE1) rearrangement gene and the protein level of CNTN1 is increasing in thyroid cancer. Besides this change is positively associated with the TNM stage and tumor size. Moreover, we confirm that knockdown of CNTN1 significantly inhibits the tumor proliferation, invasiveness and represses the expression of cyclin D1 (CCND1). In conclusion, CNTN1 will be a potential diagnosis biomarker and therapy target for thyroid cancer.

Neuronal Differentiation in Schwann Cell Lineage Underlies Postnatal Neurogenesis in the Enteric Nervous System

Elucidation of the cellular identity of neuronal precursors provides mechanistic insights into the development and pathophysiology of the nervous system. In the enteric nervous system (ENS), neurogenesis persists from midgestation to the postnatal period. Cellular mechanism underlying the long-term neurogenesis in the ENS has remained unclear. Using genetic fate mapping in mice, we show here that a subset of Schwann cell precursors (SCPs), which invades the gut alongside the extrinsic nerves, adopts a neuronal fate in the postnatal period and contributes to the ENS. We found SCP-derived neurogenesis in the submucosal region of the small intestine in the absence of vagal neural crest-derived ENS precursors. Under physiological conditions, SCPs comprised up to 20% of enteric neurons in the large intestine and gave rise mainly to restricted neuronal subtypes, calretinin-expressing neurons. Genetic ablation of Ret, the signaling receptor for glial cell line-derived neurotrophic factor, in SCPs caused colonic oligoganglionosis, indicating that SCP-derived neurogenesis is essential to ENS integrity. Identification of Schwann cells as a physiological neurogenic source provides novel insight into the development and disorders of neural crest-derived tissues.

SIGNIFICANCE STATEMENT

Elucidating the cellular identity of neuronal precursors provides novel insights into development and function of the nervous system. The enteric nervous system (ENS) is innervated richly by extrinsic nerve fibers, but little is known about the significance of extrinsic innervation to the structural integrity of the ENS. This report reveals that a subset of Schwann cell precursors (SCPs), which invades the gut alongside the extrinsic nerves, adopts a neuronal fate and differentiates into specific neuronal subtypes. SCP-specific ablation of the Ret gene leads to colonic oligoganglionosis, demonstrating a crucial role of SCP-derived neurogenesis in ENS development. Cross-lineage differentiation capacity in SCPs suggests their potential involvement in the development and pathology of a wide variety of neural crest-derived cell types.

HO-1, RET and PML as possible markers for risk stratification of acute myelocytic leukemia and prognostic evaluation

Heme oxygenase-1 (HO-1) is an inducible isoform of HO that is activated in response to oxidative stress and has anti-apoptotic and pro-proliferative effects on leukemia cells. RET, a tyrosine kinase receptor; its expression levels are associated with the differentiation degree of acute myelocytic leukemia (AML) cells. The promyelocytic leukemia (PML) gene inhibits cell proliferation and tumor growth, participates in the differentiation of hematopoietic progenitor cells and induces cell apoptosis. However, the association between the expression levels of HO-1, RET and PML genes and the risk stratification of AML and prognosis have not previously been reported. In the present study, HO-1 was expressed in the human AML Kasumi-1, HL-60 and THP-1 cell lines, and HO-1 expression was regulated by Hemin (20 µmol/l) and ZnPPIX (10 µmol/l). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis demonstrated that expression of RET and PML were positively and negatively correlated with HO-1 expression, respectively. Bone marrow samples (18 favorable, 55 intermediate, 15 adverse and 2 unknown karyotype AML cases and 20 healthy donors) were collected from 90 randomly selected AML patients upon their first visit. The mRNA and protein expression of HO-1, RET and PML in samples was detected by RT-qPCR and western blot analysis. At the mRNA level, the adverse group expressed significantly higher levels of HO-1 and RET compared with the levels in the favorable and normal groups. The PML mRNA expression levels in adverse patient samples was lower compared with those of the intermediate group and favorable group. Western blot analysis demonstrated that the expression levels of HO-1, RET and PML proteins in all risk groups exhibited the same pattern of expression as was observed for the mRNA levels. The overall survival and relapse-free survival rates were shortest in AML patients with high HO-1 expression (Kaplan-Meier; log-rank, P<0.01). The results of the present study therefore indicate that HO-1, RET and PML may be critical in the risk-stratification and prognosis of AML. However, additional samples and clinical data should be collected and analyzed in order to provide stronger evidence for this hypothesis.

The treatment landscape in thyroid cancer: a focus on cabozantinib

Although patients with thyroid cancer generally fare well, there is a subset for which this is not necessarily true. Progress in understanding the molecular aberrations in thyroid cancer has led to a change in the management of these cases. Since 2011, four multikinase inhibitors (MKIs) have been approved by the US Food and Drug Administration for thyroid cancer – cabozantinib and vandetanib for medullary thyroid cancer and sorafenib and lenvatinib for differentiated thyroid cancer. This change in the treatment landscape has raised challenges for practitioners who may not be familiar with the use of MKIs or with the treatment and natural history of advanced thyroid cancer in general. This article reviews the epidemiology, molecular drivers, and initial treatment of patients with thyroid cancer and offers practical guidance to assist with the determination of when to appropriately start an MKI. As an example, cabozantinib and its efficacy are discussed in detail. Close monitoring is required for all patients on targeted agents to assess for adverse effects and response to therapy. An approach to managing drug-related adverse events is detailed. Since these drugs are not curative and have not yet proven to prolong overall survival, it is critical to weigh the risks and benefits of treatment at every visit. The potential value of changing to a different agent following failure of an MKI is also addressed.

Biomarkers and targeted systemic therapies in advanced non-small cell lung cancer

The last decade has witnessed significant growth in therapeutic options for patients diagnosed with lung cancer. This is due in major part to our improved technological ability to interrogate the genomics of cancer cells, which has enabled the development of biologically rational anticancer agents. The recognition that lung cancer is not a single disease entity dates back many decades to the histological subclassification of malignant neoplasms of the lung into subcategories of small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). While SCLC continues to be regarded as a single histologic and therapeutic category, the NSCLC subset has undergone additional subcategorizations with distinct management algorithms for specific histologic and molecular subtypes. The defining characteristics of these NSCLC subtypes have evolved into important tools for prognosis and for predicting the likelihood of benefit when patients are treated with anticancer agents.

The role of genetic screening in medullary thyroid cancer: a clinician's view on the recent ATA guidelines

The American Thyroid Association recently released its revised guidelines on the management of medullary thyroid carcinoma. This editorial highlights the American Thyroid Association recommendations on genetic screening for medullary thyroid carcinoma and briefly discusses the future perspectives from the clinician's standpoint.

Association of Basal and Calcium-stimulated Calcitonin Levels with Pathological Findings After Total Thyroidectomy

BACKGROUND/AIM

Medullary thyroid carcinoma (MTC) originates from thyroid C-cells and is a calcitonin-secreting tumor. Calcitonin is also elevated in C-cell hyperplasia (CCH). The objective of the study was to determine the optimal basal (bCT) and peak stimulated calcitonin (psCT) cut-off value for differentiating MTC from CCH, and to examine the histological findings of thyroidectomy in patients with maximum psCT >100 pg/ml.

PATIENTS AND METHODS

Fifty-five patients had a maximum calcium-psCT >100 pg/ml and underwent total thyroidectomy.

RESULTS

A total of 20 patients were diagnosed with MTC and the remaining 35 with CCH. A bCT level >17.4 pg/ml and psCT level >452 pg/ml demonstrated the best sensitivity and positive predictive value for differenting MTC from CCH.

CONCLUSION

The overlap of calcitonin levels between MTC and CCH reduces the accuracy of the calcium stimulation test. Remarkably, an appreciable number of patients with psCT levels >100 pg/ml harbor differentiated thyroid carcinoma of follicular origin.

Synergistic antitumour activity of RAF265 and ZSTK474 on human TT medullary thyroid cancer cells

Medullary thyroid cancer (MTC) is an aggressive malignancy responsible for up to 14% of all thyroid cancer-related deaths. It is characterized by point mutations in the rearranged during transfection (RET) proto-oncogene. The activated RET kinase is known to signal via extracellular signal regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K), leading to enhanced proliferation and resistance to apoptosis. In the present work, we have investigated the effect of two serine/threonine-protein kinase B-Raf (BRAF) inhibitors (RAF265 and SB590885), and a PI3K inhibitor (ZSTK474), on RET-mediated signalling and proliferation in a MTC cell line (TT cells) harbouring the RETC634W activating mutation. The effects of the inhibitors on VEGFR2, PI3K/Akt and mitogen-activated protein kinases signalling pathways, cell cycle, apoptosis and calcitonin production were also investigated. Only the RAF265+ ZSTK474 combination synergistically reduced the viability of treated cells. We observed a strong decrease in phosphorylated VEGFR2 for RAF265+ ZSTK474 and a signal reduction in activated Akt for ZSTK474. The activated ERK signal also decreased after RAF265 and RAF265+ ZSTK474 treatments. Alone and in combination with ZSTK474, RAF265 induced a sustained increase in necrosis. Only RAF265, alone and combined with ZSTK474, prompted a significant drop in calcitonin production. Combination therapy using RAF265 and ZSTK47 proved effective in MTC, demonstrating a cytotoxic effect. As the two inhibitors have been successfully tested individually in clinical trials on other human cancers, our preclinical data support the feasibility of their combined use in aggressive MTC.

Molecular pathology of hereditary and sporadic medullary thyroid carcinomas

OBJECTIVES

Medullary thyroid carcinoma (MTC) is a relatively uncommon type of thyroid malignancy, with unique histologic features and molecular pathology. It is important to recognize, because its management, which is in part driven by the genetic basis of this disease, is different from follicular-derived thyroid tumors. The aim of this article is to briefly review the histopathologic features of MTC and then explore its molecular pathology, including the role of molecular diagnostic testing and the use of targeted therapy for advanced disease.

METHODS

A review of published literature was performed.

RESULTS

A subset of MTC cases is hereditary and due to germline mutations in the RET tyrosine kinase receptor gene. Somatic mutations in either RET or RAS are also present in most sporadic tumors.

CONCLUSIONS

Molecular genetic testing is routinely performed to identify hereditary cases. In addition, understanding the molecular basis of both hereditary and sporadic MTC has led to the development of targeted therapy with tyrosine kinase inhibitors. Although additional data are needed, tumor mutation status may affect response to targeted therapy. Therefore, it is possible that genetic testing of tumor tissue to predict treatment response, as is currently done for other cancer types, may come into practice in the future.

Targeted Therapies in Non-Small Cell Lung Cancer-Beyond EGFR and ALK

Systemic therapy for non-small cell lung cancer (NSCLC) has undergone a dramatic paradigm shift over the past decade. Advances in our understanding of the underlying biology of NSCLC have revealed distinct molecular subtypes. A substantial proportion of NSCLC depends on oncogenic molecular aberrations (so-called "driver mutations") for their malignant phenotype. Personalized therapy encompasses the strategy of matching these subtypes with effective targeted therapies. EGFR mutations and ALK translocation are the most effectively targeted oncogenes in NSCLC. EGFR mutations and ALK gene rearrangements are successfully being targeted with specific tyrosine kinase inhibitors. The number of molecular subgroups of NSCLC continues to grow. The scope of this review is to discuss recent data on novel molecular targets as ROS1, BRAF, KRAS, HER2, c-MET, RET, PIK3CA, FGFR1 and DDR2. Thereby the review will focus on therapeutic strategies targeting these aberrations. Moreover, the emerging challenge of acquired resistance to initially effective therapies will be discussed.

The RET fusion gene and its correlation with demographic and clinicopathological features of non-small cell lung cancer: a meta-analysis

PURPOSE

The RET fusion gene is a novel oncogene observed in a subset of NSCLC in recent years. Nevertheless, the results of epidemiological studies concerning the gene remain unclear. Thus, a meta-analysis was conducted to evaluate the correlation of RET fusion gene with demographic and clinicopathological features of NSCLC.

METHODS

PubMed, Embase, and Web of Science databases were searched to identify eligible studies. The association of RET fusion gene occurrence with gender, age, smoking status, histology type and tumor stage were analyzed in meta-analysis. Subgroup analysis according to patients' location (Asian and non-Asian) was also conducted. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated to assess the correlation.

RESULTS

Nine studies with a total of 6,899 NSCLC patients met the inclusion criteria. A total of 84 patients with RET fusion gene were detected. The RET fusion gene was identified at significantly higher frequencies in female (OR = 0.55, 95%CI = 0.35-0.85) than male patients and in young (<60) patients (OR = 0.43, 95%CI = 0.19-0.99) than old patients (≤60), particularly in patients from Asian. A significant higher frequency was also identified in non-smokers (OR = 0.28, 95% CI = 0.16-0.49), and in patients with lung adenocarcinomas (OR = 3.59, 95%CI = 1.50-8.56). Additionally, no association between RET fusion gene and the TNM stage of tumor was observed.

CONCLUSION

RET fusion gene occurred predominantly in Asian females with younger age, in non-smokers, and in lung adenocarcinomas patients. This subset of NSCLC patients might be good candidates for personalized diagnostic and therapeutic approaches.

RET polymorphisms might be the risk factors for thyroid cancer

AIMS

The purpose of the study is to investigate the relationship between rs1799939, rs1800858 and rs74799832 polymorphisms of RET with thyroid cancer (TC) susceptibility.

METHODS

Genotypes distribution of control groups were tested by Hardy-Weinberg equilibrium (HWE). Rs1799939, rs1800858 and rs74799832 polymorphisms of RET were researched in 135 patients with TC and 135 healthy people using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Odds ratio (OR) with 95% confidence interval (CI) were calculated to evaluate the association between RET polymorphisms and the risk of TC by Chi-squared test.

RESULTS

Genotypes frequencies of the control group were consistent with HWE. The frequency of genotype AA and allele A in rs1799939 were significantly higher in patients with TC than controls (OR=3.768, P=0.046; OR=1.695, P=0.035). Genotype GG and allele G of rs1800858 remarkably increased the risk of TC (OR=2.149, P=0.039; OR=1.45, P=0.039). Moreover, CC genotype and C allele in rs74799832 polymorphism was related with TC susceptibility. (OR=2.28, P=0.049; OR=1.566, P=0.049).

CONCLUSION

In present result, RET rs1799939, rs1800858 and rs74799832 polymorphisms might be the risk factors for TC.

Neurotrophin receptors and perineural invasion in desmoplastic melanoma

BACKGROUND

Perineural invasion (PNI) in desmoplastic melanoma is associated with increased local recurrence and reduced disease-free survival. The biological mechanisms underlying PNI remain unclear although several lines of evidence implicate neurotrophins and their receptors.

OBJECTIVES

We investigated the expression of p75NGFR and TrkA, and the presence of functional RET polymorphism (RETp) as they relate to PNI in desmoplastic melanoma.

METHODS

In all, 43 cases of desmoplastic melanoma were immunohistochemically evaluated for TrkA and p75NGFR expression and RETp was detected by direct DNA sequencing.

RESULTS

PNI was present in 67% of cases. On univariate analysis, p75NGFR was associated with PNI (expression detected in 79% of PNI-positive cases compared with 36% of PNI-negative cases, P = .005), increased Breslow depth (P = .007), and greater Clark level (P = .01). RETp was noted in 28% of cases but was not significantly associated with PNI (P = .27) or other histopathologic variables. TrkA expression was absent in all cases. PNI was associated with increased Breslow depth and Clark level (P = .01 and P = .009, respectively). Controlling for the association between p75NGFR and depth, p75NGFR remained associated with an increased propensity for PNI (odds ratio 4.68, P = .04).

LIMITATIONS

The sample size was limited.

CONCLUSION

In desmoplastic melanoma, p75NGFR expression is significantly associated with PNI and a more locally aggressive phenotype.

Systemic and CNS activity of the RET inhibitor vandetanib combined with the mTOR inhibitor everolimus in KIF5B-RET re-arranged non-small cell lung cancer with brain metastases

In-frame fusion KIF5B (the-kinesin-family-5B-gene)-RET transcripts have been characterized in 1-2% of non-small cell lung cancers and are known oncogenic drivers. The RET tyrosine kinase inhibitor, vandetanib, suppresses fusion-induced, anchorage-independent growth activity. In vitro studies have shown that vandetanib is a high-affinity substrate of breast cancer resistance protein (Bcrp1/Abcg2) but is not transported by P-glycoprotein (P-gp), limiting its blood-brain barrier penetration. A co-administration strategy to enhance the brain accumulation of vandetanib by modulating P-gp/Abcb1- and Bcrp1/Abcg2-mediated efflux with mTOR inhibitors, specifically everolimus, was shown to increase the blood-brain barrier penetration. We report the first bench-to-bedside evidence that RET inhibitor combined with an mTOR inhibitor is active against brain-metastatic RET-rearranged lung cancer and the first evidence of blood-brain barrier penetration. A 74-year-old female with progressive adenocarcinoma of the lung (wild-type EGFR and no ALK rearrangement) presented for therapy options. A deletion of 5'RET was revealed by FISH assay, indicating RET-gene rearrangement. Because of progressive disease in the brain, she was enrolled in a clinical trial with vandetanib and everolimus (NCT01582191). Comprehensive genomic profiling revealed fusion of KIF5B (the-kinesin-family-5B-gene) and RET, in addition to AKT2 gene amplification. After two cycles of therapy a repeat MRI brain showed a decrease in the intracranial disease burden and PET/CT showed systemic response as well. Interestingly, AKT2 amplification seen is a critical component of the PI3K/mTOR pathway, alterations of which has been associated with both de novo and acquired resistance to targeted therapy. The addition of everolimus may have both overcome the AKT2 amplification to produce a response in addition to its direct effects on the RET gene. Our case report forms the first evidence of blood-brain barrier penetration by vandetanib in combination with everolimus. Further research is required in this setting.

Molecular methods for somatic mutation testing in lung adenocarcinoma: EGFR and beyond

Somatic mutational profiling in cancer has revolutionized the practice of clinical oncology. The discovery of driver mutations in non-small cell lung cancer (NSCLC) is an example of this. Molecular testing of lung adenocarcinoma is now considered standard of care and part of the diagnostic algorithm. This article provides an overview of the workflow of molecular testing in a clinical diagnostic laboratory discussing in particular novel assays that are currently in use for somatic mutation detection in NSCLC focussing on epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK), ROS1 and RET rearrangements.

Non-equilibrium atmospheric pressure plasmas modulate cell cycle-related gene expressions in melanocytic tumors of RET-transgenic mice

The incidence of cutaneous malignant melanoma is increasing at a greater rate than that of any other cancer in the world. However, an effective therapy for malignant melanoma has not been established. Recently, some studies have shown an antitumor effect of non-equilibrium atmospheric pressure plasmas (NEAPPs) in vitro. Here, we examined the in vivo effect of NEAPP on cell cycle regulators, key elements for malignant transformation, in spontaneously developed benign melanocytic tumors in a hairless animal model. NEAPP irradiation decreased expression levels of cell cycle promoters, Cyclin D1, E1 and E2, and increased expression level of a cell cycle repressor, p27(KIP) (1) . Cyclin D1, E1 and E2 and p27(KIP) expression levels were associated with malignant transformation of the benign tumor in the animal model. Our results suggest that NEAPP irradiation suppresses malignant transformation of a benign melanocytic tumor via control of the expression levels of cell cycle regulators.

Activated RET and ROS: two new driver mutations in lung adenocarcinoma

Rearrangements of ROS1 and RET have been recently described as new driver mutations in lung adenocarcinoma with a frequency of about 1% each. RET and ROS1 rearrangements both represent unique molecular subsets of lung adenocarcinoma with virtually no overlap with other known driver mutations described so far in lung adenocarcinoma. Specific clinicopathologic characteristics have been described and several multitargeted receptor kinase inhibitors have shown in vitro activity against NSCLC cells harbouring these genetic alterations. In addition, the MET/ALK/ROS inhibitor crizotinib has already shown impressive clinical activity in patients with advanced ROS1-positive lung cancer. Currently, several early proof of concept clinical trials are testing various kinase inhibitors in both molecular subsets of lung adenocarcinoma patients. Most probably, personalized treatment of these genetically defined new subsets of lung adenocarcinoma will be implemented in routine clinical care of lung cancer patients in the near future.

Exome sequencing reveals mutant genes with low penetrance involved in MEN2A-associated tumorigenesis

Activating rearranged during transfection (RET) mutations function as the initiating causative mutation for multiple endocrine neoplasia type 2A (MEN2A). However, no conclusive findings regarding the non-RET genetic events have been reported. This is the first study, to our knowledge, examining genomic alterations in matched MEN2A-associated tumors. We performed exome sequencing and SNP array analysis of matched MEN2A tumors and germline DNA. Somatic alterations were validated in an independent set of patients using Sanger sequencing. Genes of functional interest were further evaluated. The germline RET mutation was found in all MEN2A-component tumors. Thirty-two somatic mutations were identified in the nine MEN2A-associated tumors, of which 28 (87.5%) were point mutations and 4 (12.5%) were small insertions, duplications, or deletions. We sequenced all the mutations as well as coding sequence regions of the 12 genes in an independent sample set including 35 medullary thyroid cancers (20 MEN2A) and 34 PCCs (22 MEN2A), but found no recurrent mutations. Recurrent alterations were found in 13 genes with either mutations or alterations in copy number, including an EIF4G1 mutation (p. E1147V). Mutation of EIF4G1 led to increased cell proliferation and RET/MAPK phosphorylation, while knockdown of EIF4G1 led to reduced cell proliferation and RET/MAPK phosphorylation in TT, MZ-CRC1, and PC-12 cells. We found fewer somatic mutations in endocrine tumors compared with non-endocrine tumors. RET was the primary driver in MEN2A-associated tumors. However, low-frequency alterations such as EIF4G1 might participate in MEN2A-associated tumorigenesis, possibly by regulating the activity of the RET pathway.

Quantitative analysis of receptor tyrosine kinase-effector coupling at functionally relevant stimulus levels

A major goal of current signaling research is to develop a quantitative understanding of how receptor activation is coupled to downstream signaling events and to functional cellular responses. Here, we measure how activation of the RET receptor tyrosine kinase on mouse neuroblastoma cells by the neurotrophin artemin (ART) is quantitatively coupled to key downstream effectors. We show that the efficiency of RET coupling to ERK and Akt depends strongly on ART concentration, and it is highest at the low (∼100 pM) ART levels required for neurite outgrowth. Quantitative discrimination between ERK and Akt pathway signaling similarly is highest at this low ART concentration. Stimulation of the cells with 100 pM ART activated RET at the rate of ∼10 molecules/cell/min, leading at 5-10 min to a transient peak of ∼150 phospho-ERK (pERK) molecules and ∼50 pAkt molecules per pRET, after which time the levels of these two signaling effectors fell by 25-50% while the pRET levels continued to slowly rise. Kinetic experiments showed that signaling effectors in different pathways respond to RET activation with different lag times, such that the balance of signal flux among the different pathways evolves over time. Our results illustrate that measurements using high, super-physiological growth factor levels can be misleading about quantitative features of receptor signaling. We propose a quantitative model describing how receptor-effector coupling efficiency links signal amplification to signal sensitization between receptor and effector, thereby providing insight into design principles underlying how receptors and their associated signaling machinery decode an extracellular signal to trigger a functional cellular outcome.

Molecular diagnosis and comprehensive treatment of multiple endocrine neoplasia type 2 in Southeastern Chinese

Background

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome. Early and normative surgery is the only curative method for MEN 2-related medullary thyroid carcinoma (MTC). In patients with adrenal pheochromocytoma, cortical-sparing adrenalectomy (CSA) can be utilized to preserve adrenocortical function.

Methods

We present twenty-six of 33 MEN2 patients underwent prophylactic thyroidectomy with varying neck dissection and eight of 24 MEN2A patients with PHEO underwent adrenal-sparing surgery. Direct sequencing of entire RET exons was performed in all participants.

Results

The RET mutations (p.C634Y [n = 10], p.C634R [n = 9], p.C634F [n = 2], p.C618Y [n = 8], p.C618R [n = 3], and p.M918T [n = 1]) were confirmed in 20 symptomatic patients and identified in 13 at-risk relatives (RET carriers). Twenty-six of 33 MEN2 patients underwent thyroidectomies with neck dissections; the mean age at the time of the first thyroid surgery and the tumor diameter of the 6 RET carriers was decreased compared with 20 symptomatic patients (P < 0.001 and P = 0.007, respectively), while the disease-free survival was increased (80% vs.10%, P = 0.0001). Seven RET carriers who were declined surgery. One of 20 symptomatic patients with MTC bone metastases after surgery received vandetanib therapy for 20 months and responded well. Additionally, 8 of 24 MEN2A patients who initially had unilateral pheochromocytomas underwent CSA, 1 developed contralateral pheochromo cytomas 10 years later, then also accepted and also agreed to a CSA. None of the patients required steroid replacement therapy.

Conclusions

Based on our results, integrated RET screening and the pre-operative calcitonin level is an excellent strategy to ensure earlier diagnosis and standard thyroidectomy. CSA can be utilized to preserve adrenocortical function in patients with pheochromocytomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s13053-015-0026-1) contains supplementary material, which is available to authorized users.

Thyroid C-Cell Biology and Oncogenic Transformation

The thyroid parafollicular cell, or commonly named "C-cell," functions in serum calcium homeostasis. Elevations in serum calcium trigger release of calcitonin from the C-cell, which in turn functions to inhibit absorption of calcium by the intestine, resorption of bone by the osteoclast, and reabsorption of calcium by renal tubular cells. Oncogenic transformation of the thyroid C-cell is thought to progress through a hyperplastic process prior to malignancy with increasing levels of serum calcitonin serving as a biomarker for tumor burden. The discovery that multiple endocrine neoplasia type 2 is caused by activating mutations of the RET gene serves to highlight the RET-RAS-MAPK signaling pathway in both initiation and progression of medullary thyroid carcinoma (MTC). Thyroid C-cells are known to express RET at high levels relative to most cell types; therefore, aberrant activation of this receptor is targeted primarily to the C-cell, providing one possible cause of tissue-specific oncogenesis. The role of RET signaling in normal C-cell function is unknown though calcitonin gene transcription appears to be sensitive to RET activation. Beyond RET, the modeling of oncogenesis in animals and screening of human tumors for candidate gene mutations have uncovered mutation of RAS family members and inactivation of Rb1 regulatory pathway as potential mediators of C-cell transformation. A growing understanding of how RET interacts with these pathways, both in normal C-cell function and during oncogenic transformation, will help in the development of novel molecular-targeted therapies.

Paracrine regulation of glioma cells invasion by astrocytes is mediated by glial-derived neurotrophic factor

It was suggested that the brain microenvironment plays a role in glioma progression. Here we investigate the mechanism by which astrocytes which are abundant in glioma tumors, promote cancer cell invasion. In this study, we evaluated the effects of astrocytes on glioma biology both in vitro and in vivo and determined the downstream paracrine effect of glial-derived neurotrophic factor (GDNF) on tumor invasion. Astrocytes-conditioned media (ACM) significantly increased human and murine glioma cells migration compared to controls. This effect was inhibited when the activity of GDNF on glioma cells was blocked by RET-Fc chimera or anti-GDNF Ab and by small interfering RNA directed against GDNF expression by astrocytes. Glioma cells incubated with ACM led to time dependent phosphorylation of the GDNF receptor, RET and downstream activation of AKT. Tumor migration and GDNF-RET-AKT activation was inhibited by the RET small-molecule inhibitor pyrazolopyrimidine-1 (PP1) and by the AKT inhibitor LY294002. Finally, blocking of RET by PP1 or knockout of the RET coreceptor GFRα1 in glioma cells reduced the size of brain tumors in immunocompetent mice. We suggest a mechanism by which astrocytes attracted to the glioma tumors facilitate brain invasion by secretion of GDNF and activation of RET/GFRα1 receptors expressed by the cancer cells.

Tandem Germline RET Mutations in a Family Pathogenetic for Multiple Endocrine Neoplasia 2B, Confirmed by a Natural Experiment

A family with germline tandem V804M/Y806C mutations in the RET proto-oncogene was reported. The in vitro study results showing that these mutations were on the same allele and that RET with these mutations had a moderate transforming activity were confirmed by the clinical features of the offspring as a natural experiment. Thus, the tandem double RET mutations are pathogenetic for MEN 2B.

Identification of two novel RET kinase inhibitors through MCR-based drug discovery: design, synthesis and evaluation

From an MCR fragment library, two novel chemical series have been developed as inhibitors of RET, which is a kinase involved in the pathology of medullary thyroid cancer (MTC). Structure activity relationship studies (SAR) identified two sub-micromolar tractable leads, 6g and 13g. 6g was confirmed to be a Type-II RET inhibitor. 13g and 6g inhibited RET in cells transformed by RET/C634. A RET DFG-out homology model was established and utilized to predict Type-II inhibitor binding modes.

Gain of copy number and amplification of the RET gene in lung cancer

RET rearrangement represents a unique molecular subset of lung cancer. The identification of specific clinicopathologic characteristics and RET gene status would provide critical information on targeted therapeutics. In this study, we investigated the patterns of RET gene in a series of lung carcinomas. Of one hundred and sixteen tumors, a low frequency (1.7%) of RET translocation was identified. Only two specimens of lung adenocarcinomas displayed the rearrangement of RET in 54% and 78% of tumor cells respectively. A high incidence of gain of copy number (3-4 copies) and amplification (≥ 5 copies) of the RET gene was observed in 52% and 12% of all 116 samples. An association between increased copy number of RET and EGFR mutation was statistically significant (p < 0.05) in these lung carcinomas. This study sheds light on the unique molecular characteristics of the RET gene in lung carcinomas.

The molecular mechanisms of a novel multi-kinase inhibitor ZLJ33 in suppressing pancreatic cancer growth

ZLJ33, an oral active multi-kinase inhibitor, was evaluated both in vitro and in vivo against human pancreatic cancer. It could effectively inhibit cell proliferation, induce apoptosis, and cause inhibition of invasion in pancreatic cancer cells. At a dose of 15.0 mg/kg, ZLJ33 induced tumor shrink in Mia-PaCa2, Capan2, and AsPC-1 xenografts models by 60.59%, 74.19%, and 71.54% according to the tumor weight, respectively. The effect of ZLJ33 on pancreatic cancer was mainly mediated by inactivation of p-PDGFRβ, p-c-Raf, and p-RET. Treatment with ZLJ33 did not cause side effect of hematology indexes in the pancreatic cancer xenograft model. ZLJ33 could be a potential therapeutic agent against pancreatic cancer.

Potent antitumor activity of cabozantinib, a c-MET and VEGFR2 inhibitor, in a colorectal cancer patient-derived tumor explant model

Antiangiogenic therapy is commonly used for the treatment of colorectal cancer (CRC). Although patients derive some clinical benefit, treatment resistance inevitably occurs. The MET signaling pathway has been proposed to be a major contributor of resistance to antiangiogenic therapy. MET is upregulated in response to vascular endothelial growth factor pathway inhibition and plays an essential role in tumorigenesis and progression of tumors. In this study, we set out to determine the efficacy of cabozantinib in a preclinical CRC patient-derived tumor xenograft model. We demonstrate potent inhibitory effects on tumor growth in 80% of tumors treated. The greatest antitumor effects were observed in tumors that possess a mutation in the PIK3CA gene. The underlying antitumor mechanisms of cabozantinib consisted of inhibition of angiogenesis and Akt activation and significantly decreased expression of genes involved in the PI3K pathway. These findings support further evaluation of cabozantinib in patients with CRC. PIK3CA mutation as a predictive biomarker of sensitivity is intriguing and warrants further elucidation. A clinical trial of cabozantinib in refractory metastatic CRC is being activated.

Kinome sequencing reveals RET G691S polymorphism in human neuroendocrine lung cancer cell lines

Neuroendocrine (NE) lung tumors comprise 20-25% of all invasive lung malignancies. Currently, no effective treatments are available to cure these tumors, and it is necessary to identify a molecular alteration(s) that characterizes NE lung tumor cells. We aimed to identify a kinase mutation(s) associated with NE lung tumor by screening 517 kinase-encoding genes in human lung cancer cell lines. Our next-generation sequencing analysis of six NE lung tumor cell lines (four small cell lung cancer lines and two non-small cell lung cancer lines) and three non-NE lung tumor lines revealed various kinase mutations, including a nonsynonymous mutation in the proto-oncogene RET (c.2071G>A; p.G691S). Further evaluation of the RET polymorphism in total 15 lung cancer cell lines by capillary sequencing suggested that the frequency of the minor allele (A-allele) in NE lung tumor lines was significantly higher than its frequency in a reference population (p = 0.0001). However, no significant difference between non-NE lung tumor lines and a reference group was detected (p = 1.0). Nevertheless, neither RET expression levels were correlated with the levels of neuron-specific enolase (NSE), a key NE marker, nor vandetanib and cabozantinib, small molecule compounds that inhibit RET, affected NSE levels in lung cancer cells. Our data suggest a potential association of G691S RET polymorphism with NE lung tumor, proposing the necessity of more thorough evaluation of this possibility. The dataset of kinase mutation profiles in this report may help choosing cell line models for study of lung cancer.

Epigenetic-related gene expression profile in medullary thyroid cancer revealed the overexpression of the histone methyltransferases EZH2 and SMYD3 in aggressive tumours

Epigenetic control of gene expression plays a major influence in the development and progression of many cancer types. Aim of the present study was to investigate the expression of epigenetic regulators in a large cohort of medullary thyroid carcinomas (MTC), correlating the data with the clinical outcome and mutational status of the patients. Taqman Low Density Arrays (TLDAs) were used to analyze expression levels of several genes involved in the epigenetic control of transcription in a series of 54 MTCs. The patients cohort included 13 familial MTCs and 41 sporadic forms; 33 hosted a RET mutation and 13 a RAS somatic mutation. The expression profiling revealed in the more aggressive diseases (i.e. occurrence of metastases; persistent disease; disease-related death) a significant increase of EZH2 and SMYD3 gene expression. The increased levels of EZH2 and SMYD3 did not correlate significantly with mutational status of RET or RAS genes. Thus, the histone methyltransferases EZH2 and SMYD3 mRNA expression may represent useful prognostic biomarkers tailoring the most appropriate follow-up and timing of therapeutic approaches.

Molecular diagnostics of fine needle aspiration for the presurgical screening of thyroid nodules

"The incidence of thyroid cancer, the most common endocrine malignancy, is rising. The two most common types of thyroid cancer are papillary and follicular" thyroid carcinomas. "Fine-needle aspiration (FNA) of thyroid nodules" can permit to detect many genetic mutations and other molecular alterations, including RAS and BRAF point mutations, PAX8/peroxisome proliferator-activated receptor (PPAR)γ and "RET/PTC rearrangements, occurring in thyroid papillary and follicular carcinomas" (more than 70% of cases), which can be used successfully to improve the diagnosis "and the management of patients with thyroid nodules". The most extensive experience has been accumulated with "the diagnostic use of BRAF mutation", which is highly specific for malignancy. "Testing FNA samples for a panel of mutations" that typically includes RAS, BRAF, PAX8/PPARγ and RET/PTC could permit to achieve the biggest diagnostic impact. "The accuracy of cancer diagnosis in thyroid nodules could be improved significantly using these and other emerging molecular markers".

HOXB5 binds to multi-species conserved sequence (MCS+9.7) of RET gene and regulates RET expression

RET gene is crucial for the development of enteric nervous system, and dys-regulation of RET expression causes Hirschsprung disease. HOXB5 regulates RET transcription, and perturbations in transcriptional regulation by HOXB5 caused reduced RET expression and defective enteric nervous system development in mice. The mechanisms by which HOXB5 regulate RET transcription are unclear. Thus, unraveling the regulatory mechanisms of HOXB5 on RET transcription could lead to a better understanding of the etiology of Hirschsprung disease. In this study, we identified and confirmed HOXB5 binding to the multi-species conserved sequence (MCS+9.7) in the first intron of the RET gene. We developed a RET mini-gene reporter system, and showed that MCS+9.7 enhanced HOXB5 trans-activation from RET promoter in human neuroblastoma SK-N-SH cells and in chick embryos. The deletion of HOXB5 binding site interfered with HOXB5 trans-activation. Furthermore, transfection of HOXB5 induced endogenous RET transcription, enhanced the co-precipitation of TATA-box binding protein with the transcription start site of RET, and induced histone H3K4 trimethylation in chromatin regions upstream and downstream of RET transcription start site. In conclusion, (i) HOXB5 physically interacted with MCS+9.7 and enhanced RET transcription, (ii) HOXB5 altered chromatin conformation and histone modification of RET locus, which could facilitate the formation of transcription complex, and enhance RET transcription, (iii) expression of RET was mediated by a complex regulatory network of transcription factors functioning in a synergistic, additive and/or independent manners. Hence, dys-regulation of RET expression by HOXB5 could result in insufficient RET expression and Hirschsprung disease.

Mild recessive mutations in six Fraser syndrome-related genes cause isolated congenital anomalies of the kidney and urinary tract

Congenital anomalies of the kidney and urinary tract (CAKUT) account for approximately 40% of children with ESRD in the United States. Hitherto, mutations in 23 genes have been described as causing autosomal dominant isolated CAKUT in humans. However, >90% of cases of isolated CAKUT still remain without a molecular diagnosis. Here, we hypothesized that genes mutated in recessive mouse models with the specific CAKUT phenotype of unilateral renal agenesis may also be mutated in humans with isolated CAKUT. We applied next-generation sequencing technology for targeted exon sequencing of 12 recessive murine candidate genes in 574 individuals with isolated CAKUT from 590 families. In 15 of 590 families, we identified recessive mutations in the genes FRAS1, FREM2, GRIP1, FREM1, ITGA8, and GREM1, all of which function in the interaction of the ureteric bud and the metanephric mesenchyme. We show that isolated CAKUT may be caused partially by mutations in recessive genes. Our results also indicate that biallelic missense mutations in the Fraser/MOTA/BNAR spectrum genes cause isolated CAKUT, whereas truncating mutations are found in the multiorgan form of Fraser syndrome. The newly identified recessive biallelic mutations in these six genes represent the molecular cause of isolated CAKUT in 2.5% of the 590 affected families in this study.

Prevalence of driver mutations in non-small-cell lung cancers in the People's Republic of China

Lung cancer is a leading cause of cancer-related mortality worldwide and in the People’s Republic of China. Recently, the pathological proportions of the various forms of lung cancer have changed. A shift to a preponderance of adenocarcinoma at the expense of squamous cell carcinoma is observable. Treatment decisions have historically been based on tumor histology, and evolution of our molecular understanding of cancer has led to development of targeted therapeutic agents. It is essential to further understand mutations that drive cancer development (driver mutations) in relevant genes and their effects on cancer cell proliferation and survival. The epidemiology of lung cancer in the People’s Republic of China has been extensively reviewed elsewhere. However, molecular epidemiological data from mainland China are scarce. Consequently, we herein review the prevalence of driver mutations in Chinese patients.

Regulation of hepcidin through GDF-15 in cancer-related anemia

BACKGROUND

High prevalence and unresponsiveness to erythropoiesis-stimulating agents are 2 major limitations to the treatment of cancer-related anemia (CRA). They are often related to the dis-regulation of iron metabolism regulated by hepcidin, but the regulatory pathway of hepcidin in CRA is poorly understood. Enhanced GDF-15 levels contribute to the cancer progression and metastasis, and also have been found to suppress hepcidin expression in anemia characterized by ineffective erythropoiesis. The pathophysiological mechanisms and the relationship of GDF-15 and hepcidin in CRA remain to be elucidated.

METHODS

The concentrations of hepcidin and GDF-15 as well as the hematological and the iron parameters were determined in sera from 131 patients with cancer and 40 healthy controls.

RESULTS

Serum GDF-15 levels were increased significantly in patients with the severe CRA, compared with the mild or no CRA patients and the controls. Increasing GDF-15 levels corresponded to decreasing hepcidin concentrations. A trend toward a correlation between high levels of GDF-15 and poor prognosis of cancer was also found. Elevation of GDF-15 concentrations suppressed hepcidin expression at high concentrations.

CONCLUSIONS

Our findings suggest that tumor progression results in increased GDF-15 secretion, which may down-regulate hepcidin expression, resulting in iron overload in cancer patients; this phenomenon has also been found in some patients with sideropenic anemia due to chronic blood loss.

Metabolic depression during warm torpor in the Golden spiny mouse (Acomys russatus) does not affect mitochondrial respiration and hydrogen peroxide release

Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Recently, depression of mitochondrial substrate oxidation in isolated liver mitochondria was observed and associated to hypothermic/hypometabolic states in Djungarian hamsters, mice and hibernators. We aimed to clarify whether hypothermia or hypometabolism causes mitochondrial depression during torpor by studying the Golden spiny mouse (Acomys russatus), a desert rodent which performs daily torpor at high ambient temperatures of 32°C. Notably, metabolic rate but not body temperature is significantly decreased under these conditions. In isolated liver, heart, skeletal muscle or kidney mitochondria we found no depression of respiration. Moderate cold exposure lowered torpor body temperature but had minor effects on minimal metabolic rate in torpor. Neither decreased body temperature nor metabolic rate impacted mitochondrial respiration. Measurements of mitochondrial proton leak kinetics and determination of P/O ratio revealed no differences in mitochondrial efficiency. Hydrogen peroxide release from mitochondria was not affected. We conclude that interspecies differences of mitochondrial depression during torpor do not support a general relationship between mitochondrial respiration, body temperature and metabolic rate. In Golden spiny mice, reduction of metabolic rate at mild temperatures is not triggered by depression of substrate oxidation as found in liver mitochondria from other cold-exposed rodents.

Ponatinib is a potent inhibitor of wild-type and drug-resistant gatekeeper mutant RET kinase

RET kinase is aberrantly activated in thyroid cancers and in rare cases of lung and colon cancer, and has been validated as a molecular target in these tumors. Vandetanib was recently approved for the treatment of medullary thyroid cancer. However, vandetanib is ineffective in vitro against RET mutants carrying bulky aminoacids at position 804, the gatekeeper residue, similarly to drug-resistant BCR-ABL mutants in chronic myeloid leukemia. Ponatinib is a multi-target kinase inhibitor that was recently approved for treatment-refractory Philadelphia-positive leukemia. We show here potent inhibition of oncogenic RET by ponatinib, including the drug-insensitive V804M/L mutants. Ponatinib inhibited the growth of RET+ and BCR-ABL+ cells with similar potency, while not affecting RET-negative cells. Both in biochemical and in cellular assays ponatinib compared favorably with known RET inhibitors, such as vandetanib, cabozantinib, sorafenib, sunitinib and motesanib, used as reference compounds. We suggest that ponatinib should be considered for the treatment of RET+ tumors, in particular those expressing vandetanib-resistant V804M/L mutations.

Swimming training prevents fat deposition and decreases angiotensin II-induced coronary vasoconstriction in ovariectomized rats

We investigated the effects of chronic swimming training (ST) on the deposition of abdominal fat and vasoconstriction in response to angiotensin II (ANG II) in the coronary arterial bed of estrogen deficient rats. Twenty-eight 3-month old Wistar female rats were divided into 4 groups: sedentary sham (SS), sedentary-ovariectomized (SO), swimming-trained sham (STS) and swimming-trained ovariectomized (STO). ST protocol consisted of a continuous 60-min session, with a 5% BW load attached to the tail, completed 5 days/week for 8-weeks. The retroperitoneal, parametrial, perirenal and inguinal fat pads were measured. The intrinsic heart rate (IHR), coronary perfusion pressure (CPP) and a concentration-response curve to ANG II in the coronary bed was constructed using the Langendorff preparation. Ovariectomy (OVX) significantly reduced 17-β-estradiol plasma levels in SO and STO groups (p<0.05). The STO group had a significantly reduced retroperitoneal and parametrial fat pad compared with the SO group (p<0.05). IHR values were similar in all groups; however, baseline CPP was significantly reduced in the SO, STS and STO groups compared with the SS group (p<0.05). ANG II caused vasoconstriction in the coronary bed in a concentration-dependent manner. The SO group had an increased response to ANG II when compared with all other experimental groups (p<0.05), which was prevented by 8-weeks of ST in the STO group (p<0.05). OVX increased ANG II-induced vasoconstriction in the coronary vascular bed and abdominal fat pad deposition. Eight weeks of swimming training improved these vasoconstrictor effects and decreased abdominal fat deposition in ovariectomized rats.

GDNF family ligand dependent STAT3 activation is mediated by specific alternatively spliced isoforms of GFRα2 and RET

Neurturin (NRTN), a member of the GDNF family of ligands (GFL), is currently investigated in a series of clinical trials for Parkinson's disease. NRTN signals through its cognate receptor GFRα2 and co-receptor RET to induce neurite outgrowth, but the underlying mechanism remains to be better understood. STAT3 was previously shown to be activated by oncogenic RET, independent of ligand and GFRα. In this study, we demonstrated that NRTN induced serine(727) but not tyrosine(705) phosphorylation of STAT3 in primary cortical neuron and neuronal cell lines. Remarkably, STAT3 phosphorylation was found to be mediated specifically by GFRα2c and RET9 isoforms. Furthermore, serine but not tyrosine dominant negative mutant of STAT3 impaired NRTN induced neurite outgrowth, indicative of the role of STAT3 as a downstream mediator of NRTN function. Similar to NGF, the NRTN induced P-Ser-STAT3 was localized to the mitochondria but not to the nucleus. Mitochondrial STAT3 was further found to be intimately involved in NRTN induced neurite outgrowth. Collectively, these findings demonstrated the hitherto unrecognized and novel role of specific GFRα2 and RET isoforms in mediating NRTN activation of STAT3 and the transcription independent mechanism whereby the mitochondria localized P-Ser-STAT3 mediated NRTN induced neurite outgrowth.

Recombinant leukemia inhibitory factor suppresses human medullary thyroid carcinoma cell line xenografts in mice

Medullary thyroid carcinoma (MTC) is a neoplasm of the endocrine system, which originates from parafollicular C-cells of the thyroid gland. For MTC therapy, the Food and Drug Administration recently approved vandetanib and cabozantinib, multi-kinase inhibitors targeting RET and other tyrosine kinase receptors of vascular endothelial growth factor, epidermal growth factor, or hepatocyte growth factor. Nevertheless, not all patients with the progressive MTC respond to these drugs, requiring the development of additional therapeutic modalities that have distinct activity. Previously, we reported that expression of activated Ras or Raf in the human MTC cell lines, TT and MZ-CRC-1, can induce growth arrest and RET downregulation via a leukemia inhibitory factor (LIF)-mediated autocrine/paracrine loop. In this study, we aimed to evaluate bacterially-produced recombinant human LIF for its efficacy to suppress human MTC xenografts in mice. Here, we report that, consistent with its effects in vitro, locally or systemically administered recombinant LIF effectively suppressed growth of TT and MZ-CRC-1 xenografts in mice. Further, as predicted from its effects in TT and MZ-CRC-1 cell cultures in vitro, recombinant LIF activated the JAK/STAT pathway and downregulated RET and E2F1 expression in tumors in mice. These results suggest that LIF is a potent cytostatic agent for MTC cells, which regulates unique mechanisms that are not targeted by currently available therapeutic agents.

Electrically induced resistance training in individuals with motor complete spinal cord injury

OBJECTIVE

To examine the effects of 16 weeks of electrically induced resistance training on insulin resistance and glucose tolerance, and changes in muscle size, composition, and metabolism in paralyzed muscle.

DESIGN

Pre-post intervention.

SETTING

University-based trial.

PARTICIPANTS

Participants (N=14; 11 men and 3 women) with chronic (>2y post spinal cord injury), motor complete spinal cord injury.

INTERVENTION

Home-based electrically induced resistance exercise training twice weekly for 16 weeks.

MAIN OUTCOME MEASURES

Plasma glucose and insulin throughout a standard clinical oral glucose tolerance test, thigh muscle and fat mass via dual-energy x-ray absorptiometry, quadriceps and hamstrings muscle size and composition via magnetic resonance imaging, and muscle oxidative metabolism using phosphorus magnetic resonance spectroscopy.

RESULTS

Muscle mass increased in all participants (mean ± SD, 39%±27%; range, 5%-84%). The mean change ± SD in intramuscular fat was 3%±22%. Phosphocreatine mean recovery time constants ± SD were 102±24 and 77±18 seconds before and after electrical stimulation-induced resistance training, respectively (P<.05). There was no improvement in fasting blood glucose levels, homeostatic model assessment calculated insulin resistance, 2-hour insulin, or 2-hour glucose.

CONCLUSIONS

Sixteen weeks of electrical stimulation-induced resistance training increased muscle mass, but did not reduce intramuscular fat. Similarly, factors associated with insulin resistance or glucose tolerance did not improve with training. We did find a 25% improvement in mitochondrial function, as measured by phosphocreatine recovery rates. Larger improvements in mitochondrial function may translate into improved glucose tolerance and insulin resistance.

Novel targets in non-small cell lung cancer: ROS1 and RET fusions

The discovery of chromosomal rearrangements involving the anaplastic lymphoma kinase (ALK) gene in non-small cell lung cancer (NSCLC) has stimulated renewed interest in oncogenic fusions as potential therapeutic targets. Recently, genetic alterations in ROS1 and RET were identified in patients with NSCLC. Like ALK, genetic alterations in ROS1 and RET involve chromosomal rearrangements that result in the formation of chimeric fusion kinases capable of oncogenic transformation. Notably, ROS1 and RET rearrangements are rarely found with other genetic alterations, such as EGFR, KRAS, or ALK. This finding suggests that both ROS1 and RET are independent oncogenic drivers that may be viable therapeutic targets. In initial screening studies, ROS1 and RET rearrangements were identified at similar frequencies (approximately 1%-2%), using a variety of genotyping techniques. Importantly, patients with either ROS1 or RET rearrangements appear to have unique clinical and pathologic features that may facilitate identification and enrichment strategies. These features may in turn expedite enrollment in clinical trials evaluating genotype-directed therapies in these rare patient populations. In this review, we summarize the molecular biology, clinical features, detection, and targeting of ROS1 and RET rearrangements in NSCLC.

Q-site inhibitor induced ROS production of mitochondrial complex II is attenuated by TCA cycle dicarboxylates

The impact of complex II (succinate:ubiquinone oxidoreductase) on the mitochondrial production of reactive oxygen species (ROS) has been underestimated for a long time. However, recent studies with intact mitochondria revealed that complex II can be a significant source of ROS. Using submitochondrial particles from bovine heart mitochondria as a system that allows the precise setting of substrate concentrations we could show that mammalian complex II produces ROS at subsaturating succinate concentrations in the presence of Q-site inhibitors like atpenin A5 or when a further downstream block of the respiratory chain occurred. Upon inhibition of the ubiquinone reductase activity, complex II produced about 75% hydrogen peroxide and 25% superoxide. ROS generation was attenuated by all dicarboxylates that are known to bind competitively to the substrate binding site of complex II, suggesting that the oxygen radicals are mainly generated by the unoccupied flavin site. Importantly, the ROS production induced by the Q-site inhibitor atpenin A5 was largely unaffected by the redox state of the Q pool and the activity of other respiratory chain complexes. Hence, complex II has to be considered as an independent source of mitochondrial ROS in physiology and pathophysiology.

Expression patterns of CXCR4 in different colon tissue segments of patients with Hirschsprung's disease

C-X-C chemokine receptor type 4 (CXCR4) plays a crucial role in a wide range of physiological and pathological processes, including the migration of stem cells, such as neural crest-derived cells. Hirschsprung's disease (HSCR), a developmental disorder characterized by the absence of ganglion cells, is regarded as the consequence of the premature arrest of the craniocaudal migration of neural crest-derived cells (NCDCs) in the gastrointestinal tract during the development of the enteric nervous system (ENS). In this study, colon tissue samples from 61 HSCR patients were surgically collected and divided into aganglionic, oligoganglionic and normal ganglionic segments. Quantitative real-time polymerase chain reactions (PCR), Western blotting, and immunohistochemical and immunofluorescence staining were performed to analyze the expression levels and patterns of CXCR4 in different colon tissue segments. The expression levels of CXCR4 mRNA and protein in the aganglionic segments were decreased compared to the normal ganglionic and oligoganglionic colon segments (p<0.01). Immunohistochemical staining showed that intensive CXCR4 staining was detected in the ganglion cells and the supporting glial cells in the ganglion in control colon specimens and normal ganglionic and oligoganglionic colon segments from the HSCR patients; however, CXCR4 staining was significantly decreased in the aganglionic colon segments. Immunofluorescence staining showed that CXCR4 staining was mainly detected in the ganglia where RET-positive ganglion cells were observed. Elucidating CXCR4 expression patterns in colon segments could be the basis for further investigations of the potential role of CXCR4 in ENS development.

Novel tandem germline RET proto-oncogene mutations in a patient with multiple endocrine neoplasia type 2B: report of a case and a literature review of tandem RET mutations with in silico analysis

BACKGROUND

Multiple endocrine neoplasia type 2B (MEN2B) is the rarest and most aggressive form of MEN2. MEN2B cases usually carry either an M918T or A883T mutation of the RET, but to date, there are 3 atypical MEN2B caused by tandem mutations.

METHODS AND RESULTS

A 32-year-old woman with no family history of medullary thyroid carcinoma (MTC) presented with a neck tumor and multiple mucosal nodules. She was diagnosed with MEN2B. Genetic analyses of RET revealed that she had 2 mutations, Q781R and V804M. Subclone and genetic analyses revealed that Q781R was on the paternal allele and V804M was a de novo. In silico analysis of the tandem mutations showed a high prediction score.

CONCLUSIONS

We describe a novel combination of tandem RET mutations (Q781R/V804M) in a MEN2B-like patient. In silico analysis showed a high prediction score, which was compatible with the clinical phenotype in the present case.

Profile of cabozantinib and its potential in the treatment of advanced medullary thyroid cancer

Medullary thyroid cancer is an uncommon malignancy for which until recently little effective treatment existed. It is often characterized by mutation and overexpression of the receptor tyrosine kinases RET (rearranged during transfection), VEGFR2 (vascular endothelial growth factor receptor 2) and MET (mesenchymal-epithelial transition factor), which make attractive targets for drug development. Cabozantinib is an orally bioavailable tyrosine kinase inhibitor which blocks MET, VEGRF2 and RET, and has shown considerable activity in medullary thyroid cancer in a Phase III trial, including in heavily pretreated patients. Its novel combination of vascular endothelial growth factor and MET inhibition is believed to address the MET escape pathway, which is thought to be the cause of nonsustained tumor responses resulting from inhibition of vascular endothelial growth factor alone.