Genetic counselling for at-risk family members with hereditary transthyretin amyloidosis: data from a single-centre study.

BACKGROUND: Hereditary transthyretin-related amyloidosis is an autosomal dominant disorder. Recently, disease-modifying therapies (DMTs) have been developed. For at-risk individuals, genetic analysis aids in the early administration of medical care; however, few studies have evaluated the current status of genetic counselling and management of presymptomatic carriers of amyloidogenic variants. METHODS: We retrospectively evaluated the medical records of 202 consecutive participants. RESULTS: A total of 103 clients who received genetic counselling for predictive testing were at-risk, and 83 underwent predictive testing. Genetic testing results were positive in 33 patients, 11 of whom had confirmed amyloid deposition and were administered DMTs. For presymptomatic V30M (p.V50M) carriers, 32.0 ± 2.4 years (median ± standard error) was the age when amyloid deposition was first identified (95% confidence interval 27.4-36.6). Serum transthyretin (TTR) levels decreased serially with an estimated slope of -1.2 mg/dL/year. CONCLUSIONS: Our study suggests the clinical utility of management using a combination of predictive testing and monitoring methods. Psychosocial support should be considered with collaboration between geneticists/genetic counsellors and psychologists. For a more optimised protocol for monitoring and designing future interventional trials in presymptomatic carriers, prospective cohort studies are necessary to clarify the natural history, particularly in the early stages of the disease.

Auditory Neuropathy Spectrum Disorder Progressing with Motor and Sensory Neuropathy Caused by an ATP1A1 Variant.

We encountered a 27-year-old Japanese woman with sensorineural deafness progressing to motor and sensory neuropathy. At 16 years old, she had developed weakness in her lower extremities and hearing impairment, which gradually deteriorated. At 22 years old, combined audiological, electrophysiological, and radiological examination results were consistent with auditory neuropathy spectrum disorder (ANSD). Genetic analyses identified a previously reported missense variant in the ATP1A1 gene (NM_000701.8:c.1799C>G, p.Pro600Arg). Although sensorineural deafness has been reported as a clinical manifestation of ATP1A1-related disorders, our case suggested that ANSD may underlie the pathogenesis of deafness in ATP1A1-related disorders. This case report broadens the genotype-phenotype spectrum of ATP1A1-related disorders.

Lysinuric protein intolerance exhibiting renal tubular acidosis/Fanconi syndrome in a Japanese woman.

Lysinuric protein intolerance (LPI), caused by pathogenic variants of SLC7A7, is characterized by protein aversion, failure to thrive, hyperammonemia, and hepatomegaly. Recent studies have reported that LPI can cause multiple organ dysfunctions, including kidney disease, autoimmune deficiency, pulmonary alveolar proteinosis, and osteoporosis. We report the case of a 47-year-old Japanese woman who was initially diagnosed with renal tubular acidosis (RTA), Fanconi syndrome, and rickets. At the age of 3 years, she demonstrated a failure to thrive. Urinary amino acid analysis revealed elevated lysine and arginine levels, which were masked by pan-amino aciduria. She was subsequently diagnosed with rickets at 5 years of age and RTA/Fanconi syndrome at 15 years of age. She was continuously treated with supplementation of vitamin D3, phosphate, and bicarbonate. A renal biopsy at 18 years of age demonstrated diffuse proximal and distal tubular damage with endocytosis-lysosome pathway abnormalities. Distinctive symptoms of LPI, such as protein aversion and postprandial hyperammonemia were not observed throughout the patient's clinical course. The patient underwent a panel-based comprehensive genetic testing and was diagnosed with LPI. As the complications of LPI involve many organs, patients lacking distinctive symptoms may develop various diseases, including RTA/Fanconi syndrome. Our case indicates that proximal and distal tubular damages are notable findings in patients with LPI. The possibility of LPI should be carefully considered in the management of RTA/Fanconi syndrome and/or incomprehensible pathological tubular damage, even in the absence of distinctive symptoms; furthermore, a comprehensive genetic analysis is useful for diagnosing LPI.

Tropomyosin-related Kinase B Is Potentially a Biomarker of Prognosis and Therapeutic Target for Malignant Thymic Epithelial Tumors.

BACKGROUND/AIM: Thymic epithelial tumors (TETs) mainly consist of thymoma and thymic carcinoma. Complete surgical resection is vital for the successful management of these TETs, and adjuvant therapy such as systematic chemotherapy and/or radiotherapy plays important roles in the management of recurrent or metastasized disease. However, there is still a lack of a standard treatment after the failure of these adjuvant therapies. There is thus a need to develop molecular targeted therapies for advanced malignant TETs. In the present study, we evaluated the biological significance of brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling for TETs. MATERIALS AND METHODS: The expression of TrkB in 48 formalin-fixed, paraffin-embedded TET specimens (43 thymoma and 5 thymic carcinoma) collected by surgical resection was evaluated immunohistochemically. A thymic carcinoma cell line was evaluated for the role of BDNF/TrkB signaling pathway in an in vitro assay. RESULTS: High TrkB expression was related to significantly poor prognosis in patients with TETs. In vitro experiments showed that BDNF/TrkB signaling was involved in the proliferation of Ty-82 cells, but not their invasion and migration. CONCLUSION: TrkB expression is a biomarker of the prognosis for TETs and the BDNF/TrkB signaling pathway is potentially a new therapeutic target for mTETs.

PTPN3 Could Βe a Therapeutic Target of Pancreatic Cancer.

BACKGROUND/AIM: Recently, protein tyrosine phosphatase non-receptor type 3 (PTPN3) has gained attention. However, the role of PTPN3 in cancer has not been fully elucidated. In the present study, we analyzed the role of PTPN3 in pancreatic cancer and investigated whether PTPN3 could be a new therapeutic target for pancreatic cancer. MATERIALS AND METHODS: Two pancreatic ductal adenocarcinoma (PDAC) cell lines were used as target cells. Cell proliferation was investigated using cell counting and a xenograft mouse model. Migration and invasion were analyzed using Transwell inserts. Activation-related signaling molecules were examined by western blotting. RESULTS: PTPN3 contributes to the proliferation, migration, and invasion of PDAC cells in vitro. PTPN3 promotes tumor growth in a mouse xenograft model, an action mediated partially through the MAPK pathway. CONCLUSION: PTPN3 could be a new therapeutic target for pancreatic cancer.

Cancer therapy that targets the Hedgehog signaling pathway considering the cancer microenvironment (Review).

Recently, the cancer microenvironment (CME) has received significant attention. At the local site of the tumor, cancer progression is affected by secreted cytokines and conditions derived from the CME and stimulation by cancer­induced cytokines in an autocrine manner. The CME is characterized by various types of conditions, such as hypoxia, inflammation stimulation, and angiogenesis, and contains various components, such as reactive oxygen species, cancer­associated fibroblasts, infiltrated immune cells, exosomes, and cancer stem cells (CSCs). These conditions and components complicate the progression of cancer. The Hedgehog (HH) signaling pathway is a morphogenesis signaling pathway that is reactivated in some cancers. In these cancers, reactivated HH signaling is involved in the induction of the malignant phenotype. HH signaling is also activated under hypoxic conditions and is considered to be strongly correlated with the CME, including the induction of cancer fibrosis and maintenance of CSCs. The aim of the present review was to elucidate a cancer therapy that targets HH signaling by considering the CME, particularly focusing on hypoxia.

Moyamoya Disease-like Cerebrovascular Stenotic Lesions Are an Important Phenotype of POEMS Syndrome-associated Vasculopathy.

A 41-year-old woman was diagnosed with polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome based on polyneuropathy, hepatosplenomegaly, sclerotic bone lesions, IgA-λ M-protein, and an elevated level of serum vascular endothelial growth factor. One month after the initiation of lenalidomide-dexamethasone with prophylactic aspirin, she developed facial paralysis, dysarthria, and left hemiplegia. Multiple cerebral infarctions and internal carotid artery stenosis were detected. Five months after switching to pomalidomide-dexamethasone, she again developed cerebral infarction. Progressed stenotic lesions in the bilateral internal carotid artery terminal portions were detected, showing a moyamoya disease-like appearance. Quasi-moyamoya disease can be an important phenotype of systemic vasculopathies of POEMS syndrome.

[Genetic counseling and predictive testing for hereditary neuromuscular diseases].

Recent progress in genetic analysis can provide a precision diagnosis for many hereditary neuromuscular diseases in daily practice. Moreover, disease-modifying therapies such as nucleic acid medicine for patients with several neuromuscular diseases (i.e., hereditary ATTR amyloidosis, spinal muscular atrophy, and Duchenne muscular dystrophy) have been approved in Japan. For all neurologists, knowledge and practical skills of genetic counseling, especially predictive testing, will increase in importance. To promote personalized medicine for patients with neuromuscular diseases and their families, it is necessary to develop of genetic counseling systems, including nurturing genetic professionals.

TrkB/BDNF Signaling Could Be a New Therapeutic Target for Pancreatic Cancer.

BACKGROUND/AIM: Tropomyosin-related kinase B (TrkB)/brain-derived neurotrophic factor (BDNF) signaling plays a role in inducing malignant phenotypes in several aggressive types of cancers. To create a conclusive therapy targeting TrkB/BDNF signaling in solid refractory cancers, the biological significance of TrkB/BDNF signaling was analyzed in pancreatic ductal adenocarcinoma (PDAC) cells. MATERIALS AND METHODS: Three PDAC cell lines were used as target cells to investigate proliferation and invasiveness. Small interfering RNA (siRNA) and the TrkB tyrosine kinase inhibitor k252a were used as TrkB/BDNF signaling inhibitors. RESULTS: All PDAC cell lines expressed TrkB and BDNF. When TrkB and BDNF were inhibited by siRNA or k252a, the invasiveness of PANC-1 and SUIT-2 cells significantly decreased. When TrkB was inhibited by siRNA or k252a, proliferation was significantly inhibited in PDAC cells. CONCLUSION: TrkB/BDNF signaling may be a new therapeutic target for PDAC. Therapies targeting TrkB/BDNF signaling may be a conclusive cancer therapy for refractory solid cancer.

PTPN3 is a potential target for a new cancer immunotherapy that has a dual effect of T cell activation and direct cancer inhibition in lung neuroendocrine tumor.

In our previous study, we found that inhibition of protein tyrosine phosphatase non-receptor type 3 (PTPN3), which is expressed in lymphocytes, enhances lymphocyte activation, suggesting PTPN3 may act as an immune checkpoint molecule. However, PTPN3 is also expressed in various cancers, and the biological significance of PTPN3 in cancer cells is still not well understood, especially for lung neuroendocrine tumor (NET).Therefore, we analyzed the biological significance of PTPN3 in small cell lung cancer and examined the potential for PTPN3 inhibitory treatment as a cancer treatment approach in lung NET including small cell lung cancer (SCLC) and large cell neuroendocrine cancer (LCNEC). Experiments in a mouse xenograft model using allo lymphocytes showed that PTPN3 inhibition in SCLC cells enhanced the anti-tumor effect of PTPN3-suppressed activated lymphocytes. In addition, PTPN3 was associated with increased vascularization, decreased CD8/FOXP3 ratio and cellular immunosuppression in SCLC clinical specimens. Experiments in a mouse xenograft model using autocrine lymphocytes also showed that PTPN3 inhibition in LCNEC cells augmented the anti-tumor effect of PTPN3-suppressed activated lymphocytes. In vitro experiments showed that PTPN3 is involved in the induction of malignant traits such as proliferation, invasion and migration. Signaling from PTPN3 is mediated by MAPK and PI3K signals via tyrosine kinase phosphorylation through CACNA1G calcium channel. Our results show that PTPN3 suppression is associated with lymphocyte activation and cancer suppression in lung NET. These results suggest that PTPN3 suppression could be a new method of cancer treatment and a major step in the development of new cancer immunotherapies.

Late-onset Hereditary ATTR Amyloidosis with a Novel p.P63S (P43S) Transthyretin Variant.

The patient was an 82-year-old Japanese man with no family history suggestive of amyloidosis. He developed bilateral leg edema and shortness of breath and was referred to our hospital. An electrocardiogram showed atrial fibrillation with right bundle branch block. Echocardiography showed concentric LV hypertrophy. An endomyocardial biopsy showed severe ATTR amyloid deposits. A genetic analysis of the transthyretin (TTR) gene revealed a heterozygous c.187C>T missense variant resulting in p.P63S (P43S). In silico analyses predicted that this variant only modestly altered the structure and function of the TTR protein. The p.P63S variant might be associated with an elderly-onset cardiac-dominant ATTRv phenotype.

A Late-onset and Relatively Rapidly Progressive Case of Pure Spinal Form Cerebrotendinous Xanthomatosis with a Novel Mutation in the CYP27A1 Gene.

A 61-year-old Japanese man with the pure spinal form of cerebrotendinous xanthomatosis developed dysesthesia of the lower limbs and gait disturbance at 57 years of age. At 61 years old, he was unable to walk without support. A neurological examination showed spasticity and sensory disturbance in the lower limbs. Spinal MRI showed long hyperintense lesions involving the lateral and posterior funiculus in the cervical and thoracic cord on T2-weighted images. His serum cholestanol level was markedly elevated. A CYP27A1 gene analysis identified two missense variants, p.R474W, and a novel p.R262C variant. Combination therapy with chenodeoxycholic acid and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase decreased his serum cholestanol level.

Antibody Therapy Targeting RAN Proteins Rescues C9 ALS/FTD Phenotypes in C9orf72 Mouse Model.

The intronic C9orf72 G4C2 expansion, the most common genetic cause of ALS and FTD, produces sense- and antisense-expansion RNAs and six dipeptide repeat-associated, non-ATG (RAN) proteins, but their roles in disease are unclear. We generated high-affinity human antibodies targeting GA or GP RAN proteins. These antibodies cross the blood-brain barrier and co-localize with intracellular RAN aggregates in C9-ALS/FTD BAC mice. In cells, α-GA1 interacts with TRIM21, and α-GA1 treatment reduced GA levels, increased GA turnover, and decreased RAN toxicity and co-aggregation of proteasome and autophagy proteins to GA aggregates. In C9-BAC mice, α-GA1 reduced GA as well as GP and GR proteins, improved behavioral deficits, decreased neuroinflammation and neurodegeneration, and increased survival. Glycosylation of the Fc region of α-GA1 is important for cell entry and efficacy. These data demonstrate that RAN proteins drive C9-ALS/FTD in C9-BAC transgenic mice and establish a novel therapeutic approach for C9orf72 ALS/FTD and other RAN-protein diseases.

Liprin-α4 as a New Therapeutic Target for SCLC as an Upstream Mediator of HIF1α.

BACKGROUND/AIM: Small-cell lung cancer (SCLC) remains one of deadliest types of cancers. Cis-diamminedichloroplatinum (CDDP) is a key chemotherapeutic agent for SCLC, however, its therapeutic effect is limited. Recently, hypoxia in the cancer microenvironment has been suggested to influence the effect of cancer therapy. MATERIALS AND METHODS: Using small interfering RNA inhibition of leukocyte common antigen-related interacting protein alpha 4 (liprin-α4), and of hypoxia-inducible factor (HIF)-1α, proliferation, invasion, migration and chemosensitivity were investigated in SBC-5 SCLC cells, under normoxia and hypoxia. RESULTS: Liprin-α4 was found to contribute to proliferation, but not migration and invasion of SBC-5 cells both under normoxia and hypoxia. Inhibition of liprin-α4 increased chemosensitivity of SBC-5 cells under hypoxia. Liprin-α4 signaling occurs through mitogen-activated protein kinase pathways via activation of HIF1α expression. Inhibition of HIF1α reduced proliferation and increased chemosensitivity of SBC-5 cells under hypoxia. CONCLUSION: Liprin-α4 inhibition may enhance the effect of CDDP and liprin-α4 might be a novel therapeutic target in SCLC.

RBPJ and MAML3: Potential Therapeutic Targets for Small Cell Lung Cancer.

BACKGROUND/AIM: Small cell lung cancer (SCLC) is still a deadly type of cancer for which there are few effective therapeutic strategies. Development of a new molecule targeting agent is urgently desired. Previously we showed that recombination signal binding protein for immunoglobulin-kappa-J region (RBPJ) and mastermind-like 3 (MAML3) are new therapeutic targets for pancreatic cancer. In the present study, we analyzed whether RBPJ/MAML3 inhibition could also be a new therapeutic strategy for SCLC. MATERIALS AND METHODS: Using silencing of RBPJ/MAML3, proliferation, invasion, migration and chemosensitivity of SBC-5 cells were investigated. RESULTS: RBPJ/MAML3 inhibition reduced Smoothened and HES1 expression, suggesting that RBPJ/MAML3 signaling was through Hedgehog and NOTCH pathways. In the analysis of cell functions, RBPJ/MAML3 inhibition significantly reduced proliferation and invasiveness via reduction of expression of matrix metalloproteinases. On the other hand, RBPJ/MAML3 inhibition also reduced chemosensitivity to cis-diamminedichlo-roplatinum and gemcitabine. CONCLUSION: These results suggest that RBPJ and MAML3 could be new therapeutic targets for SCLC, however, chemosensitivity may be reduced in combinational use with other chemo-therapeutic agents.

Hedgehog Inhibition Upregulates TRK Expression to Antagonize Tumor Suppression in Small Cell Lung Cancer Cells.

BACKGROUND/AIM: Previously we have shown that tropomyosin-related kinase B (TRKB) and Hedgehog (Hh) signalling pathways induce malignant phenotypes in many cancer types. However, results from small cell lung cancer (SCLC) clinical trials using TRK and Hh inhibitors have been disappointing. One reason for this may be the existence of crosstalk between TRKB and Hh signalling pathways. In this study, we detected negative crosstalk between the TRKB and Hh-GLI1 signalling pathways. MATERIALS AND METHODS: The human small cell lung carcinoma cell line, SBC-5, was used. Using small interfering RNA to inhibit TRKB and Hh signalling, whether TRKB and Hh signaling contribute to proliferation and invasiveness in SBC-5 cells were investigated. RESULTS: TRKB expression in GLI1 siRNA-transfected SBC-5 cells was higher than that of control cells. GLI1-knockdown alone did not affect invasiveness of SBC-5 cells. However, combined knockdown of TRKB and GLI1 significantly decreased invasiveness. Moreover, combined TRKB and GLI1 knockdown inhibited proliferation and migration to a greater extent than when either was inhibited alone. CONCLUSION: These results suggest that Hh inhibition increases TrkB expression to counter tumor suppression in SBC-5 cells. The combined use of TRKB and Hh inhibitors may, therefore, be useful for the treatment of refractory SCLC.

Inter-generational instability of inserted repeats during transmission in spinocerebellar ataxia type 31.

The causative mutation for spinocerebellar ataxia type 31 (SCA31) is an intronic insertion containing pathogenic pentanucleotide repeats, (TGGAA)n. We examined to what degree the inserted repeats were unstable during transmission. In 14 parent-child pairs, the average change of onset age was -6.4±7.3 years (mean±s.d.) in the child generation when compared with the parent generation. Of the 11 pairs analyzed, six showed expansion of inserted repeat length during transmission, and five showed contraction. On average, the inserted repeats expanded by 12.2±32.7 bp during transmission, but their mean length (with a 95% confidence interval) was not significantly different between parent and child generations. We consider that the length of the inserted repeats in SCA31 is changeable during transmission, but inter-generational instability is not marked, as far as the current sizing method can determine.

Brain-derived neurotrophic factor/tropomyosin-related kinase B signaling pathway contributes to the aggressive behavior of lung squamous cell carcinoma.

The tropomyosin-related kinase (Trk) family consists of TrkA, TrkB, and TrkC, which play essential roles in tumor progression and/or suppression in various cancers. Little is known about the biological significance of the Trk family in human lung squamous cell carcinoma (SCC). Here we investigated the clinical significance of the protein expression of Trk family members in samples from 99 SCC patients, and we explored the relationship between invasion/proliferation activities and Trk expression using lung SCC cell lines to clarify the biological significance of the Trk family in lung SCC. Immunohistochemical high expression of TrkB was significantly correlated with vascular invasion (P=0.004), lymph node metastasis (P<0.001), and advanced stage (P=0.0015). The overall survival of the patients with TrkB-high expression was significantly shorter than those with TrkB-low expression (P=0.0110). TrkA/TrkC expressions were not predictors of poor prognosis. An in vitro assay demonstrated that the inhibition of brain-derived neurotrophic factor (BDNF) (a TrkB ligand) and TrkB by K252a (a Trk inhibitor) or siRNA (BDNF-siRNA, TrkB-siRNA) suppressed the invasion, migration, and proliferative activities of lung SCC cells. The administration of recombinant human BDNF (rhBDNF) enhanced the invasion, migration, and proliferation activities, which were abrogated by K252a. TrkB-siRNA transfection increased the protein expression of E-cadherin and decreased vimentin expressions in lung SCC cells. Matrix metalloproteinase-2 (MMP-2)-mediated gelatin degradations were decreased in lung SCC cells transfected with TrkB-siRNA. Thus, TrkB-high expression is an indicator of poor prognosis in lung SCC, probably due to invasion/proliferation activities promoted by the BDNF/TrkB signaling pathway, which could become a therapeutic target for lung SCC.

Prevalence of Fabry disease and GLA c.196G>C variant in Japanese stroke patients.

Fabry disease is an important underlying disease in young cryptogenic stroke patients. However, little is known regarding the frequency of Fabry disease in the general stroke population, especially in elderly patients. A total of 588 stroke patients (61.7% men; average age 74.1±12.5 years) were enrolled in this prospective study. Blood samples were obtained to produce blood spots to determine α-galactosidase A (α-GalA) activity and for GLA gene analysis. One 65-year-old female patient had a known GLA gene mutation, c.2T>C (p.M1T), causing Fabry disease. Five male patients and two female patients had GLA c.196G>C (p.E66Q) variant, which is not associated with the full clinical manifestations of Fabry disease. The allele frequency of GLA c.196G>C was significantly higher in male patients with small-vessel occlusion (odds ratio 3.95, P=0.048) and non-cardioembolism (odds ratio 4.08, P=0.012) than that in the general Japanese population. Fabry disease is rare in the general Japanese stroke population. However, screening identified one elderly female patient with Fabry disease. GLA c.196G>C variant is a genetic risk factor for cerebral small-vessel occlusion and non-cardioembolism in Japanese males but not in females.