Transthyretin Stimulates Tumor Growth through Regulation of Tumor, Immune, and Endothelial Cells

Identification of modules and key genes associated with breast cancer subtypes through network analysis

Breast cancer is the most common malignancy in women around the world. Intratumor and intertumoral heterogeneity persist in mammary tumors. Therefore, the identification of biomarkers is essential for the treatment of this malignancy. This study analyzed 28,143 genes expressed in 49 breast cancer cell lines using a Weighted Gene Co-expression Network Analysis to determine specific target proteins for Basal A, Basal B, Luminal A, Luminal B, and HER2 ampl breast cancer subtypes. Sixty-five modules were identified, of which five were characterized as having a high correlation with breast cancer subtypes. Genes overexpressed in the tumor were found to participate in the following mechanisms: regulation of the apoptotic process, transcriptional regulation, angiogenesis, signaling, and cellular survival. In particular, we identified the following genes, considered as hubs: IFIT3, an inhibitor of viral and cellular processes; ETS1, a transcription factor involved in cell death and tumorigenesis; ENSG00000259723 lncRNA, expressed in cancers; AL033519.3, a hypothetical gene; and TMEM86A, important for regulating keratinocyte membrane properties, considered as a key in Basal A, Basal B, Luminal A, Luminal B, and HER2 ampl breast cancer subtypes, respectively. The modules and genes identified in this work can be used to identify possible biomarkers or therapeutic targets in different breast cancer subtypes.

Single-cell transcriptomics reveals stage- and side-specificity of gene modules in colorectal cancer

BACKGROUND

An understanding of mechanisms underlying colorectal cancer (CRC) development and progression is yet to be fully elucidated. This study aims to employ network theoretic approaches to analyse single cell transcriptomic data from CRC to better characterize its progression and sided-ness.

METHODS

We utilized a recently published single-cell RNA sequencing data (GEO-GSE178341) and parsed the cell X gene data by stage and side (right and left colon). Using Weighted Gene Co-expression Network Analysis (WGCNA), we identified gene modules with varying preservation levels (weak or strong) of network topology between early (pT1) and late stages (pT234), and between right and left colons. Spearman's rank correlation (ρ) was used to assess the similarity or dissimilarity in gene connectivity.

RESULTS

Equalizing cell counts across different stages, we detected 13 modules for the early stage, two of which were non-preserved in late stages. Both non-preserved modules displayed distinct gene connectivity patterns between the early and late stages, characterized by low ρ values. One module predominately dealt with myeloid cells, with genes mostly enriched for cytokine-cytokine receptor interaction potentiallystimulating myeloid cells to participate in angiogenesis. The second module, representing a subset of epithelial cells, was mainly enriched for carbohydrate digestion and absorption, influencing the gut microenvironment through the breakdown of carbohydrates. In the comparison of left vs. right colons, two of 12 modules identified in the right colon were non-preserved in the left colon. One captured a small fraction of epithelial cells and was enriched for transcriptional misregulation in cancer, potentially impacting communication between epithelial cells and the tumor microenvironment. The other predominantly contained B cells with a crucial role in maintaining human gastrointestinal health and was enriched for B-cell receptor signalling pathway.

CONCLUSIONS

We identified modules with topological and functional differences specific to cell types between the early and late stages, and between the right and left colons. This study enhances the understanding of roles played by different cell types at different stages and sides, providing valuable insights for future studies focused on the diagnosis and treatment of CRC.

Clinical spectrum of Transthyretin amyloidogenic mutations among diverse population origins

PURPOSE

Coding mutations in the Transthyretin (TTR) gene cause a hereditary form of amyloidosis characterized by a complex genotype-phenotype correlation with limited information regarding differences among worldwide populations.

METHODS

We compared 676 diverse individuals carrying TTR amyloidogenic mutations (rs138065384, Phe44Leu; rs730881165, Ala81Thr; rs121918074, His90Asn; rs76992529, Val122Ile) to 12,430 non-carriers matched by age, sex, and genetically-inferred ancestry to assess their clinical presentations across 1,693 outcomes derived from electronic health records in UK biobank.

RESULTS

In individuals of African descent (AFR), Val122Ile mutation was linked to multiple outcomes related to the circulatory system (fold-enrichment = 2.96, p = 0.002) with the strongest associations being cardiac congenital anomalies (phecode 747.1, p = 0.003), endocarditis (phecode 420.3, p = 0.006), and cardiomyopathy (phecode 425, p = 0.007). In individuals of Central-South Asian descent (CSA), His90Asn mutation was associated with dermatologic outcomes (fold-enrichment = 28, p = 0.001). The same TTR mutation was linked to neoplasms in European-descent individuals (EUR, fold-enrichment = 3.09, p = 0.003). In EUR, Ala81Thr showed multiple associations with respiratory outcomes related (fold-enrichment = 3.61, p = 0.002), but the strongest association was with atrioventricular block (phecode 426.2, p = 2.81 × 10- 4). Additionally, the same mutation in East Asians (EAS) showed associations with endocrine-metabolic traits (fold-enrichment = 4.47, p = 0.003). In the cross-ancestry meta-analysis, Val122Ile mutation was associated with peripheral nerve disorders (phecode 351, p = 0.004) in addition to cardiac congenital anomalies (fold-enrichment = 6.94, p = 0.003).

CONCLUSIONS

Overall, these findings highlight that TTR amyloidogenic mutations present ancestry-specific and ancestry-convergent associations related to a range of health domains. This supports the need to increase awareness regarding the range of outcomes associated with TTR mutations across worldwide populations to reduce misdiagnosis and delayed diagnosis of TTR-related amyloidosis.

The impact of inflammation and acute phase activation in cancer cachexia

The development of cachexia in the setting of cancer or other chronic diseases is a significant detriment for patients. Cachexia is associated with a decreased ability to tolerate therapies, reduction in ambulation, reduced quality of life, and increased mortality. Cachexia appears intricately linked to the activation of the acute phase response and is a drain on metabolic resources. Work has begun to focus on the important inflammatory factors associated with the acute phase response and their role in the immune activation of cachexia. Furthermore, data supporting the liver, lung, skeletal muscle, and tumor as all playing a role in activation of the acute phase are emerging. Although the acute phase is increasingly being recognized as being involved in cachexia, work in understanding underlying mechanisms of cachexia associated with the acute phase response remains an active area of investigation and still lack a holistic understanding and a clear causal link. Studies to date are largely correlative in nature, nonetheless suggesting the possibility for a role for various acute phase reactants. Herein, we examine the current literature regarding the acute phase response proteins, the evidence these proteins play in the promotion and exacerbation of cachexia, and current evidence of a therapeutic potential for patients.

Transthyretin promotes the invasion of combined hepatocellular cholangiocarcinoma by tumor-associated macrophages

BACKGROUND

Patients with combined hepatocellular-cholangiocarcinoma (cHCC-CCA) have limited treatment options and poor prognosis. Tumor-associated macrophages (TAMs) are the most abundant infiltrating immune cells in the tumor microenvironment and promote tumor stemness, proliferation, invasion and metastasis. Evidence suggested that transthyretin (TTR) influenced the prolifetation and invasion functions of different tumors and play an essential role in the tumor microenvironment.

AIMS

To investigate the involvement of TTR in TAMs affecting the invasion of cHCC-CCA.

METHODS AND RESULTS

Data sets obtained from the Gene Expression Omnibus database were integrated. Differentially expressed genes (DEGs) were obtained using R software, and modules associated with cHCC-CCA were screened by weighted gene co-expression network analysis (WGCNA). Human THP-1 cells were induced to differentiate into macrophages and then co-cultured with HCCC9810 cells and tumor necrosis factor-α (TNF-α) to simulate the inflammatory microenvironment of cHCC-CAA. In addition, small interfering RNA against TTR was transfected into HCCC9810 cells, and recombinant TTR and ERK and AKT-specific inhibitors were added to HCCC9810 cells, respectively; after that, the levels of NF-κB protein and phosphorylated ERK and AKT were measured. The invasive abilities of HCCC9810 cells were also tested. One hundred forty-five DEGs were associated with cHCC-CCA, of which TTR was up-regulated. Turquoise modules containing TTR in WGCNA were most significantly associated with cHCC-CCA. TTR was highly expressed in HCCC9810 compared to Huh-28. HCCC9810 showed enhanced invasive capacity after co-culture with TNF-α + macrophages (p < .05). After interfering with TTR, the invasive ability of HCCC9810 was diminished, accompanied by decreased expression of NF-κB, p-ERK1/2, and p-AKT (p < .05). After treating HCCC9810 with ERK and AKT-specific inhibitors, the invasive ability of HCCC9810 was diminished, accompanied by decreased expression of NF-κB and TTR (p < .05).

CONCLUSION

TTR can promote the invasive ability of cHCC-CCA by regulating AKT/NF-κB and ERK pathways with the assistance of TAMs.

Information-incorporated sparse convex clustering for disease subtyping

MOTIVATION

Heterogeneity in human diseases presents clinical challenges in accurate disease characterization and treatment. Recently available high throughput multi-omics data may offer a great opportunity to explore the underlying mechanisms of diseases and improve disease heterogeneity assessment throughout the treatment course. In addition, increasingly accumulated data from existing literature may be informative about disease subtyping. However, the existing clustering procedures, such as Sparse Convex Clustering (SCC), cannot directly utilize the prior information even though SCC produces stable clusters.

RESULTS

We develop a clustering procedure, information-incorporated Sparse Convex Clustering, to respond to the need for disease subtyping in precision medicine. Utilizing the text mining approach, the proposed method leverages the existing information from previously published studies through a group lasso penalty to improve disease subtyping and biomarker identification. The proposed method allows taking heterogeneous information, such as multi-omics data. We conduct simulation studies under several scenarios with various accuracy of the prior information to evaluate the performance of our method. The proposed method outperforms other clustering methods, such as SCC, K-means, Sparse K-means, iCluster+, and Bayesian Consensus Clustering. In addition, the proposed method generates more accurate disease subtypes and identifies important biomarkers for future studies in real data analysis of breast and lung cancer-related omics data. In conclusion, we present an information-incorporated clustering procedure that allows coherent pattern discovery and feature selection.

AVAILABILITY AND IMPLEMENTATION

The code is available upon request.

Evaluation of Genotoxicity and Toxicity of Annona muricata L. Seeds and In Silico Studies

Cancer is a multifactorial organic dysfunction for which great efforts are being devoted in searching for new treatments and therapeutic adjuvants. Annona muricata is a fruit that has promising activity against several types of cancer, as it contains acetogenins, the metabolite group associated with this action. Thus, the objective of this study was to evaluate, in experimental models, the toxic behavior of an extract and fraction rich in acetogenins from A. muricata seeds and study the acetogenin, Annonacin, in silico. Phytochemical characterization was made by thin layer chromatography, spectroscopy in the infrared region and nuclear magnetic resonance. Toxicity was evaluated by tests of Allium cepa and Artemia salina, and in silico studies using the SwissDock servers DockThor, PharmMapper, ADMETLab, PreADME, Osiris and ProTox. The extract and fraction showed genotoxic activity against meristematic cells of A. cepa, reducing the mitotic index; however, the extract produced great deleterious effects on the system, even causing cell necrosis. In A. Saline, the extract was more toxic than the fraction, but both samples were considered toxic. Annonacin was effectively linked to complex I, and presented different activities regarding toxicity. Thus, the results of this study are promising, highlighting the anticancer potential of acetogenins.

Combining serum peptide signatures with International Federation of Gynecology and Obstetrics (FIGO) risk score to predict the outcomes of patients with gestational trophoblastic neoplasia (GTN) after first-line chemotherapy

Background

Gestational trophoblastic neoplasia (GTN) is a group of clinically rare tumors that develop in the uterus from placental tissue. Currently, its satisfactory curability derives from the timely and accurately classification and refined management for patients. This study aimed to discover biomarkers that could predict the outcomes of GTN patients after first-line chemotherapy.

Methods

A total of 65 GTN patients were included in the study. Patients were divided into the good or poor outcome group and the clinical characteristics of the patients in the two groups were compared. Furthermore, the serum peptide profiles of all patients were uncovered by using weak cation exchange magnetic beads and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Feature peaks were identified by three machine learning algorithms and then models were constructed and compared using five machine learning methods. Additionally, liquid chromatography mass spectrometry was used to identify the feature peptides.

Results

Multivariate logistic regression analysis showed that the International Federation of Gynecology and Obstetrics (FIGO) risk score was associated with poor outcomes. Eight feature peaks (m/z =1287, 2042, 2862, 2932, 2950, 3240, 3277 and 6626) were selected for model construction and validation by the three algorithms. Based on the panel combining FIGO risk score and peptide serum signatures, the neural network (nnet) model showed promising performance in both the training (AUC=0.9635) and validation (AUC=0.8788) cohorts. Peaks at m/z 2042, 2862, 2932, 3240 were identified as the partial sequences of transthyretin, fibrinogen alpha chain (FGA), beta-globin and FGA, respectively.

Conclusion

We combined FIGO risk score and serum peptide signatures using the nnet method to construct the model which can accurately predict outcome of GTN patients after first-line chemotherapy. With this model, patients can be further classified and managed, and those with poor predicted outcomes can be given more attention for developing treatment failure.

The differential usage of molecular machinery in brain cancer patients with iron-enriched glioma environments

Gliomas are neuroepithelial tumors in the brain or spinal cord that arise from glial or precursor cells and include astrocytomas, oligodendrogliomas, and ependymomas. They are the most common malignant primary central nervous system tumors, representing 75% of cases in adults and 24% of all cases of primary brain and CNS tumors [1,2].

Construction of 2DE Patterns of Plasma Proteins: Aspect of Potential Tumor Markers

The use of tumor markers aids in the early detection of cancer recurrence and prognosis. There is a hope that they might also be useful in screening tests for the early detection of cancer. Here, the question of finding ideal tumor markers, which should be sensitive, specific, and reliable, is an acute issue. Human plasma is one of the most popular samples as it is commonly collected in the clinic and provides noninvasive, rapid analysis for any type of disease including cancer. Many efforts have been applied in searching for “ideal” tumor markers, digging very deep into plasma proteomes. The situation in this area can be improved in two ways—by attempting to find an ideal single tumor marker or by generating panels of different markers. In both cases, proteomics certainly plays a major role. There is a line of evidence that the most abundant, so-called “classical plasma proteins”, may be used to generate a tumor biomarker profile. To be comprehensive these profiles should have information not only about protein levels but also proteoform distribution for each protein. Initially, the profile of these proteins in norm should be generated. In our work, we collected bibliographic information about the connection of cancers with levels of “classical plasma proteins”. Additionally, we presented the proteoform profiles (2DE patterns) of these proteins in norm generated by two-dimensional electrophoresis with mass spectrometry and immunodetection. As a next step, similar profiles representing protein perturbations in plasma produced in the case of different cancers will be generated. Additionally, based on this information, different test systems can be developed.

Mitochondrial Oxidative Stress Induces Cardiac Fibrosis in Obese Rats through Modulation of Transthyretin

A proteomic approach was used to characterize potential mediators involved in the improvement in cardiac fibrosis observed with the administration of the mitochondrial antioxidant MitoQ in obese rats. Male Wistar rats were fed a standard diet (3.5% fat; CT) or a high-fat diet (35% fat; HFD) and treated with vehicle or MitoQ (200 μM) in drinking water for 7 weeks. Obesity modulated the expression of 33 proteins as compared with controls of the more than 1000 proteins identified. These include proteins related to endoplasmic reticulum (ER) stress and oxidative stress. Proteomic analyses revealed that HFD animals presented with an increase in cardiac transthyretin (TTR) protein levels, an effect that was prevented by MitoQ treatment in obese animals. This was confirmed by plasma levels, which were associated with those of cardiac levels of both binding immunoglobulin protein (BiP), a marker of ER stress, and fibrosis. TTR stimulated collagen I production and BiP in cardiac fibroblasts. This upregulation was prevented by the presence of MitoQ. In summary, the results suggest a role of TTR in cardiac fibrosis development associated with obesity and the beneficial effects of treatment with mitochondrial antioxidants.

Assessment of the Safety and Efficacy of an Oral Probiotic-Based Vaccine Against Aspergillus Infection in Captive-Bred Humboldt Penguins (Spheniscus humboldti)

Aspergillosis is a fungal infection caused mainly by Aspergillus fumigatus that often results in respiratory disease in birds. Aspergillosis is a major cause of morbidity and mortality in captive-bred penguin species. Currently, there is no registered vaccine to prevent aspergillosis. Recent research demonstrated that oral administration of gram-negative bacteria expressing high levels of galactose-α-1,3-galactose (α-Gal) modulates anti-α-Gal immunity and protects turkeys from clinical aspergillosis caused by experimental A. fumigatus infection. The role of anti-α-Gal immunity in penguins has not been studied. Here, we tested the distribution of α-1,3-galactosyltransferase (α1,3GT) genes in the fecal microbiome of Humboldt penguins (Spheniscus humboldti). The occurrence of natural anti-α-Gal antibodies (Abs) in sera and eggs of healthy Humboldt penguins was also assessed. A trial was then conducted to test whether oral administration of Escherichia coli Nissle, expressing high α-Gal levels, modulates anti-α-Gal immunity in a colony of Humboldt penguins. Animals in the vaccination and placebo groups were evaluated before the trial and followed for one year for aspergillosis detection using a diagnostic panel including computed tomography scans, capillary zone electrophoresis, 3-hydroxybutyrate levels, and anti-A. fumigatus Abs. Anti-α-Gal Abs were detected in sera (IgM and IgY) and eggs (IgY) of healthy penguins. Microbiota analysis and functional predictions revealed the presence of α1,3GT genes in the microbiota of Humboldt penguins and other penguin species. A strong decrease in anti-α-Gal IgM levels was observed in all animals in the placebo group three months after vaccination protocol. This decrease was not observed in E. coli Nissle-treated penguins. After the vaccination protocol, we found a positive correlation between anti-E. coli IgY and anti-α-Gal IgY in the E. coli Nissle group, suggesting a correlation between the presence of the bacteria and these Abs. During the study period, three penguins exhibited respiratory signs consistent with aspergillosis. Two were from the placebo group whose symptoms resolved with specific treatments, while a single vaccinated individual developed fatal respiratory aspergillosis eight months after the trial. We conclude that E. coli Nissle represents a safe potential probiotic with a protective effect against aspergillosis in Humboldt penguins that deserves to be further explored for therapeutic uses in these animals.

AC093797.1 as a Potential Biomarker to Indicate the Prognosis of Hepatocellular Carcinoma and Inhibits Cell Proliferation, Invasion, and Migration by Reprogramming Cell Metabolism and Extracellular Matrix Dynamics

Purpose: The risk signature composed of four lncRNA (AC093797.1, POLR2J4, AL121748.1, and AL162231.4.) can be used to predict the overall survival (OS) of patients with hepatocellular carcinoma (HCC). However, the clinical significance and biological function of AC093797.1 are still unexplored in HCC or other malignant tumors. In this study, we aimed to investigate the biological function of AC093797.1 in HCC and screen the candidate hub genes and pathways related to hepatocarcinogenesis.

Methods: RT-qPCR was employed to detect AC093797.1 in HCC tissues and cell lines. The role of AC093797.1 in HCC was evaluated via the cell-counting kit-8, transwell, and wound healing assays. The effects of AC093797.1 on tumor growth in vivo were clarified by nude mice tumor formation experiments. Then, RNA-sequencing and bioinformatics analysis based on subcutaneous tumor tissue was performed to identify the hub genes and pathways associated with HCC.

Results: The expression of AC093797.1 decreased in HCC tissues and cell lines, and patients with low expressed AC093797.1 had poor overall survival (OS). AC093797.1 overexpression impeded HCC cell proliferation, invasion, and migration in vitro and suppressed tumor growth in vivo. Compared with the control group, 710 differentially expressed genes (243 upregulated genes and 467 downregulated genes) were filtered via RNA-sequencing, which mainly enriched in amino acid metabolism, extracellular matrix structure constituents, cell adhesion molecules cams, signaling to Ras, and signaling to ERKs.

Conclusion: AC093797.1 may inhibit cell proliferation, invasion, and migration in HCC by reprograming cell metabolism or regulating several pathways, suggesting that AC093797.1 might be a potential therapeutic and prognostic marker for HCC patients.

Integrative Analysis of Epigenome and Transcriptome Data Reveals Aberrantly Methylated Promoters and Enhancers in Hepatocellular Carcinoma

DNA methylation is a key transcription regulator, whose aberration was ubiquitous and important in most cancers including hepatocellular carcinoma (HCC). Whole-genome bisulfite sequencing (WGBS) was conducted for comparison of DNA methylation in tumor and adjacent tissues from 33 HCC patients, accompanying RNA-seq to determine differentially methylated region-associated, differentially expressed genes (DMR-DEGs), which were independently replicated in the TCGA-LIHC cohort and experimentally validated via 5-aza-2-deoxycytidine (5-azadC) demethylation. A total of 9,867,700 CpG sites showed significantly differential methylation in HCC. Integrations of mRNA-seq, histone ChIP-seq, and WGBS data identified 611 high-confidence DMR-DEGs. Enrichment analysis demonstrated activation of multiple molecular pathways related to cell cycle and DNA repair, accompanying repression of several critical metabolism pathways such as tyrosine and monocarboxylic acid metabolism. In TCGA-LIHC, we replicated about 53% of identified DMR-DEGs and highlighted the prognostic significance of combinations of methylation and expression of nine DMR-DEGs, which were more efficient prognostic biomarkers than considering either type of data alone. Finally, we validated 22/23 (95.7%) DMR-DEGs in 5-azadC-treated LO2 and/or HepG2 cells. In conclusion, integration of epigenome and transcriptome data depicted activation of multiple pivotal cell cycle-related pathways and repression of several metabolic pathways triggered by aberrant DNA methylation of promoters and enhancers in HCC.

The Effect of Tafamidis on Circulating Endothelial Progenitor Cells in Patients with Transthyretin Cardiac Amyloidosis

AIMS

Endothelial microvascular dysfunction is a known mechanism of vascular pathology in cardiac amyloidosis (CA). Scientific evidence regarding the possible protective role of the amyloid transthyretin (ATTR) stabilizer, tafamidis, is lacking. Circulating endothelial progenitor cells (cEPCs) have an important role in the process of vascular repair. We aimed to examine the effect of tafamidis on cEPCs.

METHODS AND RESULTS

Study population included patients with ATTR-CA. cEPCs were assessed using flow cytometry by the expression of CD34⁽⁺⁾/CD133⁽⁺⁾ and vascular endothelial growth factor receptor (VEGFR)-2⁽⁺⁾ and by the formation of colony-forming units (CFUs) and production of VEGF. Tests were repeated at pre-specified time-points up to 12 months following the initiation of tafamidis. Included were 18 ATTR-CA patients at a median age of 77 (IQR 71, 85) years and male predominance (n = 15, 83%). Following the initiation of tafamidis and during 12 months of drug treatment, there was a gradual increase in the levels of CD34⁽⁺⁾/VEGFR-2⁽⁺⁾ (0.43 to 2.42% (IQR 1.53, 2.91)%, p = 0.002) and CD133⁽⁺⁾/VEGFR-2⁽⁺⁾ (0.49 to 1.64% (IQR 0.97, 2.90)%, p = 0.004). Functionally, increase in EPCs-CFUs was microscopically evident following treatment with tafamidis (from 0.5 CFUs (IQR 0.0, 1.0) to 3.0 (IQR 1.3, 3.8) p < 0.001) with a concomitant increase in EPC's viability as demonstrated by an MTT assay (from 0.12 (IQR 0.03, 0.16) to 0.30 (IQR 0.18, 0.33), p < 0.001). VEGF levels increased following treatment (from 54 (IQR 52, 72) to 107 (IQR 62, 129) pg/ml, p = 0.039).

CONCLUSIONS

Tafamidis induced the activation of the cEPCs pathway, possibly promoting endothelial repair in ATTR-CA.

The role of transthyretin in cell biology: impact on human pathophysiology

Transthyretin (TTR) is an extracellular protein mainly produced in the liver and choroid plexus, with a well-stablished role in the transport of thyroxin and retinol throughout the body and brain. TTR is prone to aggregation, as both wild-type and mutated forms of the protein can lead to the accumulation of amyloid deposits, resulting in a disease called TTR amyloidosis. Recently, novel activities for TTR in cell biology have emerged, ranging from neuronal health preservation in both central and peripheral nervous systems, to cellular fate determination, regulation of proliferation and metabolism. Here, we review the novel literature regarding TTR new cellular effects. We pinpoint TTR as major player on brain health and nerve biology, activities that might impact on nervous systems pathologies, and assign a new link between TTR and angiogenesis and cancer. We also explore the molecular mechanisms underlying TTR activities at the cellular level, and suggest that these might go beyond its most acknowledged carrier functions and include interaction with receptors and activation of intracellular signaling pathways.

Neuroprotection in early stages of Alzheimer's disease is promoted by transthyretin angiogenic properties

Background

While still controversial, it has been demonstrated that vascular defects can precede the onset of other AD hallmarks features, making it an important therapeutic target. Given that the protein transthyretin (TTR) has been established as neuroprotective in AD, here we investigated the influence of TTR in the vasculature.

Methods

We evaluated the thickness of the basement membrane and the length of brain microvessels, by immunohistochemistry, in AβPPswe/PS1A246E (AD) transgenic mice and non-transgenic mice (NT) bearing one (TTR+/−) or two (TTR+/+) copies of the TTR gene. The angiogenic potential of TTR was evaluated in vitro using the tube formation assay, and in vivo using the chick chorioallantoic membrane (CAM) assay.

Results

AD transgenic mice with TTR genetic reduction, AD/TTR+/−, exhibited a thicker BM in brain microvessels and decreased vessel length than animals with normal TTR levels, AD/TTR+/+. Further in vivo investigation, using the CAM assay, revealed that TTR is a pro-angiogenic molecule, and the neovessels formed are functional. Also, TTR increased the expression of key angiogenic molecules such as proteins interleukins 6 and 8, angiopoietin 2, and vascular endothelial growth factor, by endothelial cells, in vitro, under tube formation conditions. We showed that while TTR reduction also leads to a thicker BM in NT mice, this effect is more pronounced in AD mice than in NT animals, strengthening the idea that TTR is a neuroprotective protein. We also studied the effect of TTR tetrameric stabilization on BM thickness, showing that AD mice treated with the TTR tetrameric stabilizer iododiflunisal (IDIF) displayed a significant reduction of BM thickness and increased vessel length, when compared to non-treated littermates.

Conclusion

Our in vivo results demonstrate the involvement of TTR in angiogenesis, particularly as a modulator of vascular alterations occurring in AD. Since TTR is decreased early in AD, its tetrameric stabilization can represent a therapeutic avenue for the early treatment of AD through the maintenance of the vascular structure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-021-00883-8.

Molecular Characteristics of Amyloid Precursor Protein (APP) and Its Effects in Cancer

Amyloid precursor protein (APP) is a type 1 transmembrane glycoprotein, and its homologs amyloid precursor-like protein 1 (APLP1) and amyloid precursor-like protein 2 (APLP2) are highly conserved in mammals. APP and APLP are known to be intimately involved in the pathogenesis and progression of Alzheimer's disease and to play important roles in neuronal homeostasis and development and neural transmission. APP and APLP are also expressed in non-neuronal tissues and are overexpressed in cancer cells. Furthermore, research indicates they are involved in several cancers. In this review, we examine the biological characteristics of APP-related family members and their roles in cancer.

Transthyretin Amyloidosis: Update on the Clinical Spectrum, Pathogenesis, and Disease-Modifying Therapies

ATTR amyloidosis is caused by systemic deposition of transthyretin (TTR) and comprises ATTRwt (wt for wild-type) amyloidosis, ATTRv (v for variant) amyloidosis, and acquired ATTR amyloidosis after domino liver transplantation. ATTRwt amyloidosis has classically been regarded as cardiomyopathy found in the elderly, whereas carpal tunnel syndrome has also become a major initial manifestation. The phenotypes of ATTRv amyloidosis are diverse and include neuropathy, cardiomyopathy, and oculoleptomeningeal involvement as the predominant features, depending on the mutation and age of onset. In addition to variant TTR, the deposition of wild-type TTR plays a significant role, even in patients with ATTRv amyloidosis. The formation of amyloid fibrils tends to occur in association with the basement membrane. The thickening or reduplication of the basement membrane surrounding endoneurial microvessels, which is similar to diabetic neuropathy, is observed in ATTRv amyloidosis, suggesting that common mechanisms, such as an accumulation of advanced glycation end products, may participate in the disease process. In addition to direct damage caused by amyloid fibrils, recent studies have suggested that the toxicity of nonfibrillar TTRs, such as TTR oligomers, participates in the process of tissue damage. Although liver transplantation has been performed for patients with ATTRv amyloidosis since 1990, late-onset patients were not eligible for this treatment. However, as the efficacy of orally administered tafamidis and diflunisal, which stabilize TTR tetramers, was suggested in the early 2010s, such late-onset patients have also become targets for disease-modifying therapies. Additionally, recent studies of small interfering RNA (patisiran) and antisense oligonucleotide (inotersen) therapies have demonstrated the efficacy of these gene-silencing agents. A strategy for monitoring patients that enables the choice of an appropriate treatment from comprehensive and long-term viewpoints should be established. As many patients with ATTR amyloidosis are aged and have heart failure, they are at increased risk of aggravation if they are infected by SARS-CoV2. The optimal interval of evaluation should also be considered, particularly in this COVID-19 era.

Transthyretin increases migration and invasion of rat placental trophoblast cells

Preeclampsia (PE) is a hypertensive disorder of pregnancy. Early diagnosis of PE is currently contingent on regular prenatal physical examinations and may be facilitated by identification of novel diagnostic markers. Transthyretin (TTR), also known as prealbumin, is primarily responsible for maintaining the normal levels of thyroxine and retinol binding protein. The expression of TTR is lower in patients with severe PE as compared with healthy controls. Here, we examined the suitability of TTR as a diagnostic marker in pregnant hypertensive rats. N'-nitro-l-arginine-methylesterhydrochloride (l-NAME) was used to generate a rat model of hypertension during pregnancy. Rat placental trophoblast cells were divided into control and TTR groups for in vitro experiments. Systolic blood pressure, diastolic blood pressure, mean blood pressure and urinary protein of hypertensive pregnant rats were higher than those of healthy pregnant rats, but these effects could be reversed by TTR treatment. There were no significant changes in blood pressure and urinary protein in healthy pregnant rats before or after TTR treatment. TTR levels in the serum and placental tissues of pregnant hypertensive rats were significantly reduced compared with those of healthy pregnant rats. Changes in placental and fetal weights in the hypertensive model could also be rescued by TTR treatment. TTR treatment significantly increased the level of matrix metalloproteinase-2/9 in hypertensive rats. Finally, in vivo and in vitro experiments demonstrated that TTR effectively increased the migration and invasion of rat placental trophoblast cells, as well as matrix metalloproteinase-2/9 levels in these cells. In conclusion, our data from a rat model suggest that TTR may have potential as a novel marker for PE diagnosis.

Undiscovered Roles for Transthyretin: From a Transporter Protein to a New Therapeutic Target for Alzheimer's Disease

Transthyretin (TTR), an homotetrameric protein mainly synthesized by the liver and the choroid plexus, and secreted into the blood and the cerebrospinal fluid, respectively, has been specially acknowledged for its functions as a transporter protein of thyroxine and retinol (the latter through binding to the retinol-binding protein), in these fluids. Still, this protein has managed to stay in the spotlight as it has been assigned new and varied functions. In this review, we cover knowledge on novel TTR functions and the cellular pathways involved, spanning from neuroprotection to vascular events, while emphasizing its involvement in Alzheimer’s disease (AD). We describe details of TTR as an amyloid binding protein and discuss its interaction with the amyloid Aβ peptides, and the proposed mechanisms underlying TTR neuroprotection in AD. We also present the importance of translating advances in the knowledge of the TTR neuroprotective role into drug discovery strategies focused on TTR as a new target in AD therapeutics.

Spatial Arrangements of Connexin43 in Cancer Related Cells and Re-Arrangements under Treatment Conditions: Investigations on the Nano-Scale by Super-Resolution Localization Light Microscopy

Cancer studies suggest that the spatial localization of connexin43 (Cx43) could play an important role during tumor genesis and the formation of metastasis. Cx43 has been shown to be upregulated in cancer cells; thereby a shift from Cx43 normal localization in gap junctions in the cell membrane towards a primarily cytoplasmic localization was observed in many studies. So far neither the spatial arrangements of Cx43 in breast cancer cells nor the effects of treatment outcome (ionizing radiation and antibody therapy) on the spatial arrangements of Cx43, have been microscopically studied on the nanoscale. This has brought up the idea to study the micro- and nanoscaled spatial Cx43 arrangements in a model of breast cancer-related cell types, i.e., SkBr3 breast cancer cells, BJ fibroblasts, and primary human internal mammary artery endothelial cells (HIMAECs). The cells were treated with neuregulin1 (NRG1), trastuzumab (Herceptin), or 6MeV-photon irradiation at a dose of 4 Gy. NRG1 stimulates further NRG1 release in the tumor endothelium that may lead to an enhanced tumor protective effect whereas Herceptin, used in antibody treatment, works in an antagonistic fashion to NRG1. After fluorescent labelling with specific antibodies, the molecular positions of Cx43 in the perinuclear cytosol and in the cell periphery at the membrane were determined for the three treatment related applications (NRG1, trastuzumab, 4 Gy irradiation) using confocal laser scanning microscopy (CLSM) and single molecule localization microscopy (SMLM). These techniques enable investigations of Cx43 enrichment and topological arrangements of Cx43 molecules from the micro-scale of a whole cell to the nano-scale of single molecules. In SkBr3 cells with and without radiation treatment high density accumulations were detected which seem to be diluted after NRG1 and trastuzumab treatment although the SMLM distance frequency distributions did not significantly vary. In BJ fibroblasts and HIMAECs differences between periphery and perinuclear cytosol were observed after the different treatment processes. HIMAECs showed significant Cx43 accumulation after NRG1, trastuzumab, and radiation treatment in the perinuclear region whereas in the periphery radiation has less influence as compared to the control. BJ cells were reacting to the treatments by Cx43 accumulations in the perinuclear region but also in the periphery. In conclusion, it was shown that by using CLSM and super-resolution SMLM, treatment effects on the spatial and thus functional arrangements of Cx43 became detectable for investigations of tumor response mechanisms.