MicroRNA-93-5p regulates odontogenic differentiation and dentin formation via KDM6B

BACKGROUND

Epigenetic factors influence the odontogenic differentiation of dental pulp stem cells and play indispensable roles during tooth development. Some microRNAs can epigenetically regulate other epigenetic factors like DNA methyltransferases and histone modification enzymes, functioning as epigenetic-microRNAs. In our previous study, microarray analysis suggested microRNA-93-5p (miR-93-5p) was differentially expressed during the bell stage in human tooth germ. Prediction tools indicated that miR-93-5p may target lysine-specific demethylase 6B (KDM6B). Therefore, we explored the role of miR-93-5p as an epi-miRNA in tooth development and further investigated the underlying mechanisms of miR-93-5p in regulating odontogenic differentiation and dentin formation.

METHODS

The expression pattern of miR-93-5p and KDM6B of dental pulp stem cells (DPSCs) was examined during tooth development and odontogenic differentiation. Dual luciferase reporter and ChIP-qPCR assay were used to validate the target and downstream regulatory genes of miR-93-5p in human DPSCs (hDPSCs). Histological analyses and qPCR assays were conducted for investigating the effects of miR-93-5p mimic and inhibitor on odontogenic differentiation of hDPSCs. A pulpotomy rat model was further established, microCT and histological analyses were performed to explore the effects of KDM6B-overexpression and miR-93-5p inhibition on the formation of tertiary dentin.

RESULTS

The expression level of miR-93-5p decreased as odontoblast differentiated, in parallel with elevated expression of histone demethylase KDM6B. In hDPSCs, miR-93-5p overexpression inhibited the odontogenic differentiation and vice versa. MiR-93-5p targeted 3' untranslated region (UTR) of KDM6B, thereby inhibiting its protein translation. Furthermore, KDM6B bound the promoter region of BMP2 to demethylate H3K27me3 marks and thus upregulated BMP2 transcription. In the rat pulpotomy model, KDM6B-overexpression or miR-93-5p inhibition suppressed H3K27me3 level in DPSCs and consequently promoted the formation of tertiary dentin.

CONCLUSIONS

MiR-93-5p targets epigenetic regulator KDM6B and regulates H3K27me3 marks on BMP2 promoters, thus modulating the odontogenic differentiation of DPSCs and dentin formation.

Epigenetics in developmental defects of enamel: A scoping review

OBJECTIVES

The significant role of epigenetics has been revealed in normal enamel formation process and occurrence of developmental defects. This presented literature is aiming at summarizing the regulatory function of epigenetics in physiological amelogenesis process and reviewing the epigenetic mechanisms in occurrence of developmental defects of enamel (DDE), so as to provide biological foundation evidence to support early predication and clinical management of DDE.

METHOD

An extensive literature review was conducted using electronic databases MEDLINE (through PubMed), Web of Science and EMBASE up to November 30, 2022. Studies about epigenetic effects on enamel tissue or cells associated with amelogenesis, including in vivo studies using human or animal models, and in vitro studies, are selected.

RESULTS

A total of 22 studies were included. Epigenetic factors or effects specifically activate or silence certain genes, which may regulate related biological activities including cell proliferation, cell differentiation, enamel secretion, and mineralization during the process of amelogenesis. Once the status of epigenetic modification is altered, the quantity and quality of enamel may both be disturbed, which can finally result in DDE.

CONCLUSION

Epigenetics plays a noteworthy role of regulating the amelogenesis process and DDE potentially by altering the expression levels of genes related to enamel formation, providing a new perspective of early predication and clinical management of DDE.

[Aloin inhibits gastric cancer cell proliferation and migration by suppressing the STAT3/HMGB1 signaling pathway]

OBJECTIVE

To investigate the molecular mechanism underlying the inhibitory effect of aloin on the proliferation and migration of gastric cancer cells.

METHODS

Human gastric cancer MGC-803 cells treated with 100, 200 and 300 μg/mL aloin were examined for changes in cell viability, proliferation and migration abilities using CCK-8, EdU and Transwell assays. HMGB1 mRNA level in the cells was detected with RT-qPCR, and the protein expressions of HMGB1, cyclin B1, cyclin E1, E-cadherin, MMP-2, MMP-9 and p-STAT3 were determined using Western blotting. JASPAR database was used to predict the binding of STAT3 to HMGB1 promoter. In a BALB/c-Nu mouse model bearing subcutaneous MGC-803 cell xenograft, the effect of intraperitoneal injection of aloin (50 mg/kg) on tumor growth was observed. The protein expressions of HMGB1, cyclin B1, cyclin E1, E-cadherin, MMP-2, MMP-9 and p-STAT3 in the tumor tissue was examined using Western blotting, and tumor metastasis in the liver and lung tissues was detected using HE staining.

RESULTS

Treatment with aloin concentration-dependently inhibited the viability of MGC-803 cells (P < 0.05), significantly reduced the number of EdU-positive cells (P < 0.01), and attenuated the migration ability of the cells (P < 0.01). Aloin treatment dose-dependently down-regulated HMGB1 mRNA expression (P < 0.01), lowered the protein expressions of HMGB1, cyclin B1, cyclin E1, MMP-2, MMP-9 and p-STAT3, and up-regulated E-cadherin expression in MGC-803 cells. Prediction based on JASPAR database suggested that STAT3 could bind to the promoter region of HMGB1. In the tumor-bearing mice, aloin treatment significantly reduced the tumor size and weight (P < 0.01), lowered the protein expressions of cyclin B1, cyclin E1, MMP-2, MMP-9, HMGB1 and p-STAT3 and increased the expression of E-cadherin in the tumor tissue (P < 0.01).

CONCLUSION

Aloin attenuates the proliferation and migration of gastric cancer cells by inhibiting the STAT3/HMGB1 signaling pathway.

METTL3 enhances dentinogenesis differentiation of dental pulp stem cells via increasing GDF6 and STC1 mRNA stability

BACKGROUND

The dentinogenesis differentiation of dental pulp stem cells (DPSCs) is controlled by the spatio-temporal expression of differentiation related genes. RNA N6-methyladenosine (m⁶A) methylation, one of the most abundant internal epigenetic modification in mRNA, influences various events in RNA processing, stem cell pluripotency and differentiation. Methyltransferase like 3 (METTL3), one of the essential regulators, involves in the process of dentin formation and root development, while mechanism of METTL3-mediated RNA m⁶A methylation in DPSC dentinogenesis differentiation is still unclear.

METHODS

Immunofluorescence staining and MeRIP-seq were performed to establish m⁶A modification profile in dentinogenesis differentiation. Lentivirus were used to knockdown or overexpression of METTL3. The dentinogenesis differentiation was analyzed by alkaline phosphatase, alizarin red staining and real time RT-PCR. RNA stability assay was determined by actinomycin D. A direct pulp capping model was established with rat molars to reveal the role of METTL3 in tertiary dentin formation.

RESULTS

Dynamic characteristics of RNA m⁶A methylation in dentinogenesis differentiation were demonstrated by MeRIP-seq. Methyltransferases (METTL3 and METTL14) and demethylases (FTO and ALKBH5) were gradually up-regulated during dentinogenesis process. Methyltransferase METTL3 was selected for further study. Knockdown of METTL3 impaired the DPSCs dentinogenesis differentiation, and overexpression of METTL3 promoted the differentiation. METTL3-mediated m⁶A regulated the mRNA stabiliy of GDF6 and STC1. Furthermore, overexpression of METTL3 promoted tertiary dentin formation in direct pulp capping model.

CONCLUSION

The modification of m⁶A showed dynamic characteristics during DPSCs dentinogenesis differentiation. METTL3-mediated m⁶A regulated in dentinogenesis differentiation through affecting the mRNA stability of GDF6 and STC1. METTL3 overexpression promoted tertiary dentin formation in vitro, suggesting its promising application in vital pulp therapy (VPT).

[Epigenetic regulation mechanism: roles in enamel formation and developmental defects of enamel]

Enamel formation is a series of complex physiological processes, which are regulated by critical genes spatially and temporally. These processes involve multiple developmental stages covering ages and are prone to suffer signal interference or gene mutations, ultimately leading to developmental defects of enamel (DDE). Epigenetic modifications have important regulatory roles in gene expression during enarnel development. New technologies including high-throughput sequencing, chromatin immunoprecipitation sequencing (ChIP-seq), and DNA methylation chip are emerging in recent years, making it possible to establish genome-wide epigenetic modification profiles during developmental processes. The regulatory role of epigenetic modification with spatio-temporal pattern, such as DNA methylation, histone modification and non-coding RNA, has significantly expanded our understanding of the regulatory network of enamel formation, providing a new theoretical basis of clinical management and intervention strategy for DDE. The present review briefly describes the enamel formation process of human beings' teeth as well as rodent incisors and summarizes the dynamic characteristics of epigenetic modification during enamel formation. The functions of epigenetic modification in enamel formation and DDE are also emphatically discussed.

Epigenetic regulation of dental-derived stem cells and their application in pulp and periodontal regeneration

Dental-derived stem cells have excellent proliferation ability and multi-directional differentiation potential, making them an important research target in tissue engineering. An increasing number of dental-derived stem cells have been discovered recently, including dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHEDs), stem cells from apical papilla (SCAPs), dental follicle precursor cells (DFPCs), and periodontal ligament stem cells (PDLSCs). These stem cells have significant application prospects in tissue regeneration because they are found in an abundance of sources, and they have good biocompatibility and are highly effective. The biological functions of dental-derived stem cells are regulated in many ways. Epigenetic regulation means changing the expression level and function of a gene without changing its sequence. Epigenetic regulation is involved in many biological processes, such as embryonic development, bone homeostasis, and the fate of stem cells. Existing studies have shown that dental-derived stem cells are also regulated by epigenetic modifications. Pulp and periodontal regeneration refers to the practice of replacing damaged pulp and periodontal tissue and restoring the tissue structure and function under normal physiological conditions. This treatment has better therapeutic effects than traditional treatments. This article reviews the recent research on the mechanism of epigenetic regulation of dental-derived stem cells, and the core issues surrounding the practical application and future use of pulp and periodontal regeneration.

Metabolic-epigenetic nexus in regulation of stem cell fate

Stem cell fate determination is one of the central questions in stem cell biology, and although its regulation has been studied at genomic and proteomic levels, a variety of biological activities in cells occur at the metabolic level. Metabolomics studies have established the metabolome during stem cell differentiation and have revealed the role of metabolites in stem cell fate determination. While metabolism is considered to play a biological regulatory role as an energy source, recent studies have suggested the nexus between metabolism and epigenetics because several metabolites function as cofactors and substrates in epigenetic mechanisms, including histone modification, DNA methylation, and microRNAs. Additionally, the epigenetic modification is sensitive to the dynamic metabolites and consequently leads to changes in transcription. The nexus between metabolism and epigenetics proposes a novel stem cell-based therapeutic strategy through manipulating metabolites. In the present review, we summarize the possible nexus between metabolic and epigenetic regulation in stem cell fate determination, and discuss the potential preventive and therapeutic strategies via targeting metabolites.

Symptomatic and Asymptomatic Chronic Carotid Artery Occlusion on High-Resolution MR Vessel Wall Imaging

BACKGROUND AND PURPOSE

Chronic carotid artery occlusion remains a poorly understood risk factor for subsequent stroke, and potential revascularization is dependent on understanding the anatomy and nature of the occlusion. Luminal imaging cannot assess the nature of an occlusion, so the internal structure of the occlusion must be inferred. The present study examines the signal characteristics of symptomatic and asymptomatic carotid occlusion that may point to management differentiation.

MATERIALS AND METHODS

We prospectively recruited patients who were diagnosed with chronic carotid artery occlusion defined as longer than 4 weeks and confirmed by DSA. All patients underwent high-resolution MR vessel wall imaging examinations after enrollment. Baseline characteristics, vessel wall imaging features, and DSA features were collected and evaluated. The vessel wall imaging features included segment involvement, signal intensity, contrast enhancement, and vessel wall thickness. The symptomatic and asymptomatic chronic carotid artery occlusions were compared.

RESULTS

A total of 44 patients with 48 lesions were included in this study from February 2020 to December 2020. Of the 48 lesions, 35 (72.9%) were symptomatic and 13 (27.1%) were asymptomatic. There was no difference in baseline and DSA features. On vessel wall imaging, C1 and C2 were the most commonly involved segments (91.7% and 68.8%, respectively). Compared with symptomatic lesions, asymptomatic lesions were more often isointense (69.2%) in the distal segment (P = .03). Both groups had diffuse wall thickening (80% and 100%).

CONCLUSIONS

Signal characteristics between those with symptomatic and asymptomatic carotid artery occlusions differ in a statistically significant fashion, indicating a different structure of the occlusion.

Epigenetic regulation of dental pulp stem cells and its potential in regenerative endodontics

Regenerative endodontics (RE) therapy means physiologically replacing damaged pulp tissue and regaining functional dentin–pulp complex. Current clinical RE procedures recruit endogenous stem cells from the apical papilla, periodontal tissue, bone marrow and peripheral blood, with or without application of scaffolds and growth factors in the root canal space, resulting in cementum-like and bone-like tissue formation. Without the involvement of dental pulp stem cells (DPSCs), it is unlikely that functional pulp regeneration can be achieved, even though acceptable repair can be acquired. DPSCs, due to their specific odontogenic potential, high proliferation, neurovascular property, and easy accessibility, are considered as the most eligible cell source for dentin–pulp regeneration. The regenerative potential of DPSCs has been demonstrated by recent clinical progress. DPSC transplantation following pulpectomy has successfully reconstructed neurovascularized pulp that simulates the physiological structure of natural pulp. The self-renewal, proliferation, and odontogenic differentiation of DPSCs are under the control of a cascade of transcription factors. Over recent decades, epigenetic modulations implicating histone modifications, DNA methylation, and noncoding (nc)RNAs have manifested as a new layer of gene regulation. These modulations exhibit a profound effect on the cellular activities of DPSCs. In this review, we offer an overview about epigenetic regulation of the fate of DPSCs; in particular, on the proliferation, odontogenic differentiation, angiogenesis, and neurogenesis. We emphasize recent discoveries of epigenetic molecules that can alter DPSC status and promote pulp regeneration through manipulation over epigenetic profiles.

MDA5 attenuate autophagy in chicken embryo fibroblasts infected with IBDV

1. The role of melanoma differentiation-associated protein 5 (MDA5) in infectious bursal disease virus (IBDV)-induced autophagy was studied in chicken embryos.2. Chicken embryo fibroblasts (CEF) were used as the research model and small interfering RNA (siRNA), western blot, indirect enzyme-linked immunosorbent assay (ELISA), real-time fluorescence quantitative polymerase chain reaction (PCR) and transmission electron microscopy were used to detect autophagy, IBDV replication, CEF damage, and activation of both MDA5 and its signalling pathway.3. The results showed that CEF infected with IBDV activated the intracellular MDA5 signalling pathway and caused autophagy via inactivation of the AKT/mTOR pathway. While autophagy promotes IBDV proliferation, MDA5 weakens IBDV-induced CEF autophagy thus inhibiting IBDV replication and protecting CEF cells.4. The results indicated that chMDA5 can be activated by IBDV and attenuate CEF autophagy caused by IBDV infection, thereby inhibiting IBDV replication. This study provided a foundation for further exploring the relationship between viruses, autophagy and the pathogenic mechanism of the MDA5 pathway involved in IBDV.

Roles of Dental Mesenchymal Stem Cells in the Management of Immature Necrotic Permanent Teeth

Dental caries and trauma always lead to pulp necrosis and subsequent root development arrest of young permanent teeth. The traditional treatment, apexification, with the absence of further root formation, results in abnormal root morphology and compromises long-term prognosis. Regeneration endodontics procedures (REPs) have been developed and considered as an alternative strategy for management of immature permanent teeth with pulpal necrosis, including cell-free and cell-based REPs. Cell-free REPs, including revascularization and cell homing with molecules recruiting endogenous mesenchymal stem cells (MSCs), have been widely applied in clinical treatment, showing optimistic periapical lesion healing and continued root development. However, the regenerated pulp-dentin complex is still absent in these cases. Dental MSCs, as one of the essentials of tissue engineering, are vital seed cells in regenerative medicine. Dental MSC-based REPs have presented promising potential with pulp-dentin regeneration in large animal studies and clinical trials via cell transplantation. In the present review, we summarize current understanding of the biological basis of clinical treatments for immature necrotic permanent teeth and the roles of dental MSCs during this process and update the progress of MSC-based REPs in the administration of immature necrotic permanent teeth.

Bisphenol A Exposure Disrupts Enamel Formation via EZH2-Mediated H3K27me3

Enamel formation is a serial and complex biological process, during which related genes are expressed progressively in a spatiotemporal manner. This process is vulnerable to environmental cues, resulting in developmental defects of enamel (DDE). However, how environmental factors are biologically integrated during enamel formation is still poorly understood. Here, we investigated the mechanism of DDE elicited by a model endocrine-disrupting chemical, bisphenol A (BPA), in mouse incisors. We show that BPA exposure leads to DDE in mouse incisors, as well as excessive proliferation in dental epithelial stem/progenitor cells. Western blotting, chromatin immunoprecipitation sequencing, and immunofluorescence staining revealed that this effect was accompanied by upregulation of a repressive mark, H3K27me3, in the labial cervical loop of mouse incisors. Perturbation of H3K27me3 methyltransferase EZH2 repressed the level of H3K27me3 and partially attenuated the excessive proliferation in dental epithelial stem/progenitor cells and DDE induced by BPA exposure. Overall, our results demonstrate the essential role of repressive histone modification H3K27me3 in DDE elicited by exposure to an endocrine-disrupting chemical.

New insight into dental epithelial stem cells: Identification, regulation, and function in tooth homeostasis and repair

Tooth enamel, a highly mineralized tissue covering the outermost area of teeth, is always damaged by dental caries or trauma. Tooth enamel rarely repairs or renews itself, due to the loss of ameloblasts and dental epithelial stem cells (DESCs) once the tooth erupts. Unlike human teeth, mouse incisors grow continuously due to the presence of DESCs that generate enamel-producing ameloblasts and other supporting dental epithelial lineages. The ready accessibility of mouse DESCs and wide availability of related transgenic mouse lines make mouse incisors an excellent model to examine the identity and heterogeneity of dental epithelial stem/progenitor cells; explore the regulatory mechanisms underlying enamel formation; and help answer the open question regarding the therapeutic development of enamel engineering. In the present review, we update the current understanding about the identification of DESCs in mouse incisors and summarize the regulatory mechanisms of enamel formation driven by DESCs. The roles of DESCs during homeostasis and repair are also discussed, which should improve our knowledge regarding enamel tissue engineering.

Prevalence and antimicrobial resistance of Salmonellaisolates from goose farms in Northeast China

BACKGROUND

Salmonella is one of the most important enteric pathogenic bacteria that threatened poultry health.

AIMS

This study aimed to investigate the prevalence and antimicrobial resistance of Salmonella isolates in goose farms.

METHODS

A total of 244 cloacal swabs were collected from goose farms to detect Salmonella in Northeast China. Antimicrobial susceptibility, and resistance gene distribution of Salmonella isolates were investigated.

RESULTS

Twenty-one Salmonella isolates were identified. Overall prevalence of Salmonella in the present study was 8.6%. Among the Salmonella isolates, the highest resistance frequencies belonged to amoxicillin (AMX) (85.7%), tetracycline (TET) and trimethoprim/sulfamethoxazole (SXT) (81%), followed by chloramphenicol (CHL) (76.2%), florfenicol (FLO) (71.4%), kanamycin (KAN) (47.6%), and gentamycin (GEN) (38.1%). Meanwhile, only 4.8% of the isolates were resistant to ciprofloxacin (CIP) and cefotaxime (CTX). None of the isolates was resistant to cefoperazone (CFP) and colistin B (CLB). Twenty isolates (95%) were simultaneously resistant to at least two antimicrobials. Ten resistance genes were detected among which the bla _TEM-1, cmlA, aac(6')-Ib-cr, sul1, sul2, sul3, and mcr-1.1 were the most prevalent, and presented in all 21 isolates followed by tetB (20/21), qnrB (19/21), and floR (15/21).

CONCLUSION

Results indicated that Salmonella isolates from goose farms in Northeast China exhibited multi-drug resistance (MDR), harboring multiple antimicrobial resistance genes. Our results will be useful to design prevention and therapeutic strategies against Salmonella infection in goose farms.

A large pool of actively cycling progenitors orchestrates self-renewal and injury repair of an ectodermal appendage

The classical model of tissue renewal posits that small numbers of quiescent stem cells (SCs) give rise to proliferating transit-amplifying cells before terminal differentiation. However, many organs house pools of SCs with proliferative and differentiation potentials that diverge from this template. Resolving SC identity and organization is therefore central to understanding tissue renewal. Here, using a combination of single-cell RNA sequencing (scRNA-seq), mouse genetics and tissue injury approaches, we uncover cellular hierarchies and mechanisms that underlie the maintenance and repair of the continuously growing mouse incisor. Our results reveal that, during homeostasis, a group of actively cycling epithelial progenitors generates enamel-producing ameloblasts and adjacent layers of non-ameloblast cells. After injury, tissue repair was achieved through transient increases in progenitor-cell proliferation and through direct conversion of Notch1-expressing cells to ameloblasts. We elucidate epithelial SC identity, position and function, providing a mechanistic basis for the homeostasis and repair of a fast-turnover ectodermal appendage.

Epiregulin enhances odontoblastic differentiation of dental pulp stem cells via activating MAPK signalling pathway

Objectives

The odontoblastic differentiation of dental pulp stem cells (DPSCs) contributes to tertiary dentin formation. Our previous study indicated that epiregulin (EREG) enhanced odontogenesis potential of dental pulp. Here, we explored the effects of EREG during DPSC odontoblastic differentiation.

Methods

The changes in EREG were detected during tertiary dentin formation. DPSCs were treated with recombinant human EREG (rhEREG), EREG receptor inhibitor gefitinib and short hairpin RNAs. The odontoblastic differentiation was assessed with ALP staining, ALP activity assay, alizarin red S staining and real‐time RT‐PCR of DSPP, OCN, RUNX2 and OSX. Western blot was conducted to examine the levels of p38 mitogen‐activated protein kinase (p38 MAPK), c‐Jun N‐terminal kinase (JNK) and extracellular signal‐regulated kinase 1/2 (Erk1/2). The expression of EREG and odontoblastic differentiation‐related markers was investigated in human dental pulp from teeth with deep caries and healthy teeth.

Results

Epiregulin was upregulated during tertiary dentin formation. rhEREG enhanced the odontoblastic differentiation of DPSCs following upregulated p38 MAPK and Erk1/2 phosphorylation, but not JNK, whereas depletion of EREG suppressed DPSC differentiation. Gefitinib decreased odontoblastic differentiation with decreased phosphorylation of p38 MAPK and Erk1/2. And suppression of p38 MAPK and Erk1/2 pathways attenuated DPSC differentiation. In human dental pulp tissue, EREG upregulation in deep caries correlates with odontoblastic differentiation enhancement.

Conclusion

Epiregulin is released during tertiary dentin formation. And EREG enhanced DPSC odontoblastic differentiation via MAPK pathways.

A randomized controlled trial protocol assessing the effectiveness, safety and cost-effectiveness of methotrexate vs. ciclosporin in the treatment of severe atopic eczema in children: the TREatment of severe Atopic eczema Trial (TREAT)

BACKGROUND

Oral systemic immunomodulatory medication is regularly used off-licence in children with severe atopic eczema. However, there is no firm evidence regarding the effectiveness, safety, cost-effectiveness and impact on quality of life from an adequately powered randomized controlled trial (RCT) using systemic medication in children.

OBJECTIVES

To assess whether there is a difference in the speed of onset, effectiveness, side-effect profile and reduction in flares post-treatment between ciclosporin (CyA) and methotrexate (MTX), and also the cost-effectiveness of the drugs. Treatment impact on quality of life will also be examined in addition to whether FLG genotype influences treatment response. In addition, the trial studies the immune-metabolic effects of CyA and MTX.

METHODS

Multicentre, parallel group, assessor-blind, pragmatic RCT of 36 weeks' duration with a 24-week follow-up period. In total, 102 children aged 2-16 years with moderate-to-severe atopic eczema, unresponsive to topical treatment will be randomized (1 : 1) to receive MTX (0·4 mg kg^-1 per week) or CyA (4 mg kg^-1 per day).

RESULTS

The trial has two primary outcomes: change from baseline to 12 weeks in Objective Severity Scoring of Atopic Dermatitis (o-SCORAD) and time to first significant flare following treatment cessation.

CONCLUSIONS

This trial addresses important therapeutic questions, highlighted in systematic reviews and treatment guidelines for atopic eczema. The trial design is pragmatic to reflect current clinical practice.

The Origin and Identification of Mesenchymal Stem Cells in Teeth: from Odontogenic to Non-odontogenic

BACKGROUND

Mesenchymal stem cells (MSCs) in teeth have been exploited as vital seed cells for stem cell-based dental medicine. To date, several mesenchymal stem cell populations originated from odontogenic tissue have been isolated and characterized by their expression of MSC surface markers and capacity of multi-lineage differentiation, including dental pulp stem cells (DPSCs), stem cells from human exfoliated deciduous teeth (SHED), stem cells from apical papilla (SCAP) and so on. However, their identity in vivo remains elusive, which hinders further understanding of their application in stem cell-based tooth regeneration. Label retaining and lineage tracing analyses, which serve as gold standards for identification of stem cells in vivo, provide feasibility for identifying MSCs in teeth.

OBJECTIVES

In this review, we will discuss the issues of MSCs, including the origin and identification of both odontogenic and non-odontogenic MSCs, and address the role of nerve-derived Sonic hedgehog (Shh) in the regulation of MSCs in the neurovascular bundle (NVB).

CONCLUSION

Based on label retaining and lineage tracing analyses, latest studies have found new populations of non-odontogenic MSCs in teeth, periarterial-derived and glial-derived, regulated by the Shh derived from nerves in the NVB, which provides a new hope for tooth regeneration.

Insight into the Role of Long Non-coding RNAs During Osteogenesis in Mesenchymal Stem Cells

BACKGROUND

Long non-coding RNAs (LncRNAs) are non-protein coding transcripts longer than 200 nucleotides in length. Instead of being "transcriptional noise", lncRNAs are emerging as a key modulator in various biological processes and disease development. Mesenchymal stem cells can be isolated from various adult tissues, such as bone marrow and dental tissues. The differentiation processes into multiple lineages, such as osteogenic differentiation, are precisely orchestrated by molecular signals in both genetic and epigenetic ways. Recently, several lines of evidence suggested the role of lncRNAs participating in cell differentiation through the regulation of gene transcriptions. And the involvement of lncRNAs may be associated with initiation and progression of mesenchymal stem cell-related diseases.

OBJECTIVE

We aimed at addressing the role of lncRNAs in the regulation of osteogenesis of mesenchymal stem cells derived from bone marrow and dental tissues, and discussing the potential utility of lncRNAs as biomarkers and therapeutic targets for mesenchymal stem cell-related diseases.

RESULTS

Numerous lncRNAs were differentially expressed during osteogenesis or odontogenesis of mesenchymal stem cells, and some of them were confirmed to be able to regulate the differentiation processes through the modifications of chromatin, transcriptional and post-transcriptional processes. LncRNAs were also associated with some diseases related with pathologic differentiation of mesenchymal stem cells.

CONCLUSION

LncRNAs involve in the osteogenic differentiation of bone marrow and dental tissuederived mesenchymal stem cells, and they could become promising therapeutic targets and prognosis parameters. However, the mechanisms of the role of lncRNAs are still enigmatic and require further investigation.

Epigenetic Regulation of Gene Expression in Epithelial Stem Cells Fate

BACKGROUND

Epithelial tissues have the ability to self-renew throughout animal's life due to the presence of the epithelial stem cells. Except for complicated genes regulation, the fate of epithelial stem cells is also regulated by the epigenetics, including DNA methylation, histone modification and microRNAs, which are emerging as vital elements of epigenetic regulation for epithelial stem cells self-renewal and differentiation. However, the mechanisms underlying these are still poorly understood.

OBJECTIVE

In this review, we focus on the epigenetic regulation of gene expression in epithelial stem cells fate, using intestinal and epidermal stem cells as models. Meanwhile, a brief description of recent research about the possible impact of network regulation in epithelial stem cell-based amelogenesis by epigenetic regulation is therefore, being discussed.

CONCLUSION

Epigenetic modification plays a vital role in the epithelial stem cells fate choice through the gene expression. The interaction between epigenetic modification and molecular signaling in epithelial stem cells fate choice still needs further exploration.

Bivalent Histone Modifications and Development

BACKGROUND

Development is an epigenetic regulation dependent event. As one pretranscriptional regulator, bivalent histone modifications were observed to be involved in development recently. It is believed that histone methylation potentially takes charge of cell fate determination and differentiation. The synchronous existence of functionally opposite histone marks at transcript start sequence (TSS) is defined as "Bivalency", which mainly mark development related genes. H3K4me3 and H3K27me3, the prominent histone methylations of bivalency, are implicated in transcriptional activation and transcriptional repression respectively. The delicate balance between H3K4me3 and H3K27me3 produces diverse chromatin architectures, resulting in different transcription states of downstream genes: "poised", "activated" or "repressed".

OBJECTIVE

In order to explore the developmental role of bivalent histone modification and the underlying mechanism, we did systematic review and rigorous assessment about relative literatures.

RESULT

Bivalent histone modifications are considered to set up genes for activation during lineage commitment by H3K4me3 and repress lineage control genes to maintain pluripotency by H3K27me3. Summarily, bivalency in stem cells keeps stemness via poising differentiation relevant genes. After receiving developmental signals, the balance between "gene activation" and "gene repression" is broken, which turns genes transcription state from "poised" effect to switch on or switch off effect, thus initiates irreversible and spontaneous differentiation procedures.

CONCLUSION

Bivalent histone modifications and the associated histone-modifying complexes safeguard proper and robust differentiation of stem cells, thus playing an essential role in development.

DNA Methylation: A Frontier in Tooth Organogenesis and Developmental Dental Defects

BACKGROUND

Tooth development relies on interactions between epithelial and mesenchymal tissues, which are controlled by sophisticated networks of conserved signaling. The signaling networks regulating odontogenesis have been well characterized, but the epigenetic mechanisms underlying remain to be elucidated.

OBJECTIVE

In this review, we describe current researches regarding the control of various genes expression by DNA methylation during odontogenesis, summarize genomic mapping of DNA methylation in various stages of tooth formation and diverse dental tissues by high-throughput approaches, and highlight the roles of DNA methylation in odontogenesis.

RESULTS

Researches on mammals have revealed that the genomic methylation, which occurs on cytosine residues, regulates certain genes transcription. Consequently, DNA methylation plays a crucial role in spatiotemporal organization of signaling pathways, and is essential for organogenesis. Recently, mounting evidence proves that methylation of genomes contributes to the spatiotemporal gene dynamics during odontogenesis. With emerging new technologies of mapping cytosine modifications in global genome, investigators are seeking an overall view of DNA methylome dynamics that characterize genetic information to manifest across incredibly varied tooth development stages, dental tissues, and developmental dental defects.

Interpretation of liver stiffness measurement-based approach for the monitoring of hepatitis B patients with antiviral therapy: A 2-year prospective study

Liver biopsy is not routinely performed in treated chronic hepatitis B. Liver stiffness measurement has been validated for noninvasive liver fibrosis assessment in pretreatment chronic hepatitis B but has not been assessed for fibrosis monitoring during antiviral therapy. Liver stiffness was systemically monitored by Fibroscan^® every 6 months in a cohort of patients with hepatitis B receiving antiviral therapy and compared with liver biopsies at baseline and week 104. A total of 534 hepatitis B e antigen-positive treatment-naive patients receiving telbivudine-based therapy with qualified liver stiffness measurement at baseline and week 104 were analyzed, 164 of which had adequate paired liver biopsies. Liver stiffness decreased rapidly (-2.2 kPa/24 weeks) in parallel with alanine aminotransferase (ALT) from 8.6 (2.6-49.5) kPa at baseline to 6.1 (2.2-37.4) kPa at week 24. Interestingly, liver stiffness decreased slowly (-0.3 kPa/24 weeks) but continually from week 24 to week 104 (6.1 vs 5.3 kPa, P < .001) while ALT levels remained stable within the normal range. More importantly, liver stiffness declined significantly irrespective of baseline ALT levels and liver necroinflammation grades. From baseline to week 104, the proportion of patients with no or mild fibrosis (Ishak, 0-2) increased from 74.4% (122/164) to 93.9% (154/164). Multivariate analysis revealed that percentage decline of 52-week liver stiffness from baseline was independently associated with 104-week liver fibrosis regression (odds ratio, 3.742; P = .016). Early decline of 52-week liver stiffness from baseline may reflect the remission of both liver inflammation and fibrosis and was predictive of 104-week fibrosis regression in treated patients with chronic hepatitis B.

The incidence of military training-related injuries in Chinese new recruits: a systematic review and meta-analysis

INTRODUCTION

Training-related injuries are the main reason for disability, long-term rehabilitation, functional impairment and premature discharge from military service. The aim of this study was to identify the incidence of injuries in the training of Chinese new recruits via a systematic review of the literature.

METHOD

A systematic review and meta-analysis was conducted to evaluate the combined incidence of military training-related injuries in Chinese new recruits. The electronic databases of full-text journals were searched, and the Loney criteria were used to assess the quality of eligible articles. Summary estimates were obtained using random-effects models. Subgroup analyses and publication bias tests were performed.

RESULTS

Fifty-five eligible articles representing 109 611 Chinese new recruits met the inclusion criteria, of which 21 253 recruits were clinically diagnosed with military training-related injuries. The combined incidence of military training-related injuries in Chinese new recruits was found to be 21.04%.

CONCLUSIONS

An increased incidence of training injuries was found in more recent years, underscoring the need for further research on the risk factors associated with their causation.

Bivalent Histone Codes on WNT5A during Odontogenic Differentiation

Lineage-committed differentiation is an essential biological program during odontogenesis, which is tightly regulated by lineage-specific genes. Some of these genes are modified by colocalization of H3K4me3 and H3K27me3 marks at promoter regions in progenitors. These modifications, named "bivalent domains," maintain genes in a poised state and then resolve for later activation or repression during differentiation. Wnt5a has been reported to promote odontogenic differentiation in dental mesenchyme. However, relatively little is known about the epigenetic modulations on Wnt5a activation during tooth development. Here, we investigated the spatiotemporal patterns of H3K4me3 and H3K27me3 marks in developing mouse molars. Associated H3K4me3 methylases (mixed-lineage leukemia [MLL] complex) and H3K27me3 demethylases (JMJD3 and UTX) were dynamically expressed between early and late bell stage of human tooth germs and in cultured human dental papilla cells (hDPCs) during odontogenic induction. Poised WNT5A gene was marked by bivalent domains containing repressive marks (H3K27me3) and active marks (H3K4me3) on promoters. The bivalent domains tended to resolve during inducted differentiation, with removal of the H3K27me3 mark in a JMJD3-dependent manner. When JMJD3 was knocked down in cultured hDPCs, odontogenic differentiation was suppressed. The depletion of JMJD3 epigenetically repressed WNT5A activation by increased H3K27me3 marks. In addition, JMJD3 could physically interact with ASH2L, a component of the MLL complex, to form a coactivator complex, cooperatively modulating H3K4me3 marks on WNT5A promoters. Overall, our study reveals that transcription activities of WNT5A were epigenetically regulated by the negotiated balance between H3K27me3 and H3K4me3 marks and tightly mediated by JMJD3 and MLL coactivator complex, ultimately modulating odontogenic commitment during dental mesenchymal cell differentiation.

Energy transfer channels and turbulence cascade in Vlasov-Maxwell turbulence

Analysis of the Vlasov-Maxwell equations from the perspective of turbulence cascade clarifies the role of electromagnetic work, and reveals the importance of the pressure-strain relation in generating internal energy. Particle-in-cell simulation demonstrates the relative importance of the several energy exchange terms, indicating that the traceless pressure-strain interaction "Pi-D" is of particular importance for both electrons and protons. The Pi-D interaction and the second tensor invariants of the strain are highly localized in similar spatial regions, indicating that energy transfer occurs preferentially in coherent structures. The collisionless turbulence cascade may be fruitfully explored by study of these energy transfer channels, in addition to examining transfer across spatial scales.

Characterization of Extensive Microstructural Variations Associated with Punctate White Matter Lesions in Preterm Neonates

BACKGROUND AND PURPOSE

Punctate white matter lesions are common in preterm neonates. Neurodevelopmental outcomes of the neonates are related to the degree of extension. This study aimed to characterize the extent of microstructural variations for different punctate white matter lesion grades.

MATERIALS AND METHODS

Preterm neonates with punctate white matter lesions were divided into 3 grades (from mild to severe: grades I-III). DTI-derived fractional anisotropy, axial diffusivity, and radial diffusivity between patients with punctate white matter lesions and controls were compared with Tract-Based Spatial Statistics and tract-quantification methods.

RESULTS

Thirty-three preterm neonates with punctate white matter lesions and 33 matched controls were enrolled. There were 15, 9, and 9 patients, respectively, in grades I, II, and III. Punctate white matter lesions were mainly located in white matter adjacent to the lateral ventricles, especially regions lateral to the trigone, posterior horns, and centrum semiovale and/or corona radiata. Extensive microstructural changes were observed in neonates with grade III punctate white matter lesions, while no significant changes in DTI metrics were found for grades I and II. A pattern of increased axial diffusivity, increased radial diffusivity, and reduced/unchanged fractional anisotropy was found in regions adjacent to punctate white matter lesion sites seen on T1WI and T2WI. Unchanged axial diffusivity, increased radial diffusivity, and reduced/unchanged fractional anisotropy were observed in regions distant from punctate white matter lesion sites.

CONCLUSIONS

White matter microstructural variations were different across punctate white matter lesion grades. Extensive change patterns varied according to the distance to the lesion sites in neonates with severe punctate white matter lesions. These findings may help in determining the outcomes of punctate white matter lesions and selecting treatment strategies.

Insights into the Regulation of Yap/Taz from Cellular Systems and Mouse Models

BACKGROUND

The Hippo signaling pathway serves as a main regulator of tissue growth and organ size through the moderation of cell cycle dynamics across many different species. In mammals, the two downstream transcriptional regulators of this pathway are Yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ). Recent studies found in addition to the core Hippo signaling pathway, other signaling pathways can also regulate YAP/TAZ activity, either directly or through crosstalk with the Hippo pathway.

OBJECTIVE

In this review, we discuss what is known about the regulation of YAP/TAZ from studies conducted using both cell line and mouse models.

CONCLUSION

To add to the complexity of YAP/TAZ regulation, the activity of YAP/TAZ is also controlled by mechanical and cytoskeletal cues and by multiple extracellular factors.

Stem Cell-based Tooth Engineering and their Potential in Dental Medicine

Stem cells are unspecialized cells, which have the capacity to self-renew and generate differentiated cell types. They hold great promises in regenerative medicine, which has the potential to revolutionize our approach to treat diseases and alleviate problems caused by trauma and aging. The dental field has been an active area for researching stem cell based therapies and a great effort has been made to develop strategies for utilizing embryonic stem cells (ESCs), adult dental stem cells and more recently, induced pluripotent stem (iPS) cells in tooth regeneration. In this review, we focus on these three main sources of stem cells, describe findings that have laid the foundation for using these cells in tooth regeneration, and discuss the potential as well as challenges of tooth bioengineering in clinical application.

Histone Modification in Osteogenic Differentiation of Skeletal Stem Cells

Osteogenic differentiation of skeletal stem cells is an integral part of bone development and homeostasis, and the perturbation of this process is one of the causes to skeletal disease. Understanding of how epigenetic events regulate skeletal stem cell differentiation is therefore of great importance. While the basic epigenetic modifications leading to bone formation are somewhat under explored, a significant amount of research has defined the regulatory roles of histone modifications in osteogenic differentiation. The orchestration of histone modifications is a requirement to establish the epigenetic status which regulates gene transcription during osteogenic differentiation of skeletal stem cells. Here we focus on the roles of histone modification during osteogenic differentiation and review studies that have advanced our knowledge in the field. Before this summary, a brief description is given regarding the up-to-date understanding of the definition of skeletal stem cells and the main mechanisms responsible for histone modifications.

E-selectin expression induced by Porphyromonas gingivalis in human endothelial cells via nucleotide-binding oligomerization domain-like receptors and Toll-like receptors

Porphyromonas gingivalis, an important periodontal pathogen, has been proved to actively invade cells, induce endothelial cell activation, and promote development of atherosclerosis. Innate immune surveillance, which includes the activity of nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) and Toll-like receptors (TLRs), are essential for the control of microbial infections; however, the roles of receptor families in P. gingivalis infections remain unclear. Here, we examined the roles of NLRs and TLRs in endothelial cell activation caused by P. gingivalis. Live P. gingivalis and whole cell sonicates were used to stimulate endothelial cells, and both showed upregulation of E-selectin as well as NOD1, NOD2, and TLR2. In addition, silencing of these genes in endothelial cells infected with P. gingivalis led to a reduction in E-selectin expression. Porphyromonas gingivalis also induced nuclear factor-κB (NF-κB) and P38 mitogen-activated protein kinase (MAPK) activity in endothelial cells, whereas small interfering RNA targeting NOD1 significantly reduced these signals. Moreover, inhibition of either NOD2 or TLR2 inhibited NF-κB significantly, but had only a weak inhibitory effect on P38 MAPK signaling. Direct inhibition of NF-κB and P38 MAPK significantly attenuated E-selectin expression induced by P. gingivalis in endothelial cells. Taken together, these findings suggest that NOD1, NOD2, and TLR2 play important, non-redundant roles in endothelial cell activation following P. gingivalis infection.

Anisotropy in solar wind plasma turbulence

A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters.

Intermittent Dissipation and Heating in 3D Kinetic Plasma Turbulence

High resolution, fully kinetic, three dimensional (3D) simulation of collisionless plasma turbulence shows the development of turbulence characterized by sheetlike current density structures spanning a range of scales. The nonlinear evolution is initialized with a long wavelength isotropic spectrum of fluctuations having polarizations transverse to an imposed mean magnetic field. We present evidence that these current sheet structures are sites for heating and dissipation, and that stronger currents signify higher dissipation rates. The analyses focus on quantities such as J·E, electron, and proton temperatures, and conditional averages of these quantities based on local electric current density. Evidently, kinetic scale plasma, like magnetohydrodynamics, becomes intermittent due to current sheet formation, leading to the expectation that heating and dissipation in astrophysical and space plasmas may be highly nonuniform. Comparison with previous results from 2D kinetic simulations, as well as high frequency solar wind observational data, are discussed.

Crosstalk between miR-34a and Notch Signaling Promotes Differentiation in Apical Papilla Stem Cells (SCAPs)

Stem cells from the apical papilla (SCAPs) are important for the formation and regeneration of root dentin. Here, we examined the expression of Notch signaling components in SCAPs and investigated crosstalk between microRNA miR-34aand Notch signaling during cell differentiation. We found that human SCAPs express NOTCH2, NOTCH3, JAG2, DLL3, and HES1, and we tested the relationship between Notch signaling and both cell differentiation and miR-34a expression. NOTCH activation in SCAPs inhibited cell differentiation and up-regulated the expression of miR-34a, whereas miR-34a inhibited Notch signaling in SCAPs by directly targeting the 3'UTR of NOTCH2 and HES1 mRNA and suppressing the expression of NOTCH2, N2ICD, and HES1. DSPP, RUNX2, OSX, and OCN expression was consequently up-regulated. Thus, Notch signaling in human SCAPs plays a vital role in maintenance of these cells. miR-34a interacts with Notch signaling and promotes both odontogenic and osteogenic differentiation of SCAPs.

Von Kármán energy decay and heating of protons and electrons in a kinetic turbulent plasma

Decay in time of undriven weakly collisional kinetic plasma turbulence in systems large compared to the ion kinetic scales is investigated using fully electromagnetic particle-in-cell simulations initiated with transverse flow and magnetic disturbances, constant density, and a strong guide field. The observed energy decay is consistent with the von Kármán hypothesis of similarity decay, in a formulation adapted to magnetohydrodyamics. Kinetic dissipation occurs at small scales, but the overall rate is apparently controlled by large scale dynamics. At small turbulence amplitudes the electrons are preferentially heated. At larger amplitudes proton heating is the dominant effect. In the solar wind and corona the protons are typically hotter, suggesting that these natural systems are in the large amplitude turbulence regime.

Efficacy and safety of continuous 4-year telbivudine treatment in patients with chronic hepatitis B

In the phase-III GLOBE/015 studies, telbivudine demonstrated superior efficacy vs lamivudine during 2-year treatment in HBeAg-positive and HBeAg-negative chronic hepatitis B (CHB). After completion, 847 patients had an option to continue telbivudine treatment for further 2 years. A total of 596 (70%) of telbivudine-treated patients, who were serum HBV DNA positive or negative and without genotypic resistance to telbivudine at the end of the GLOBE/015 trials, were enrolled into a further 2-year extension study. A group of 502 patients completed 4 years of continuous telbivudine treatment and were included in the telbivudine per-protocol population. Amongst 293 HBeAg-positive patients, 76.2% had undetectable serum HBV DNA and 86.0% had normal serum ALT at the end of 4 years. Notably, the cumulative rate of HBeAg seroconversion was 53.2%. Amongst 209 HBeAg-negative patients, 86.4% had undetectable HBV DNA and 89.6% had normal serum ALT. In patients who had discontinued telbivudine treatment due to HBeAg seroconversion, the HBeAg response was durable in 82% of patients (median 111 weeks of off-treatment follow-up). The cumulative 4-year resistance rate was 10.6% for HBeAg-positive and 10.0% for HBeAg-negative patients. Most adverse events were mild or moderate in severity and transient. Renal function measured by estimated glomerular filtration rate (eGFR) increased by 14.9 mL/min/1.73 m(2) (16.6%) from baseline to 4 years (P < 0.0001). In conclusion, in HBeAg-positive and HBeAg-negative CHB patients without resistance after 2 years, two additional years of telbivudine treatment continued to provide effective viral suppression with a favourable safety profile. Moreover, telbivudine achieved 53% of HBeAg seroconversion in HBeAg-positive patients.

microRNA miR-34a regulates cytodifferentiation and targets multi-signaling pathways in human dental papilla cells

Odontogenesis relies on the reciprocal signaling interactions between dental epithelium and neural crest-derived mesenchyme, which is regulated by several signaling pathways. Subtle changes in the activity of these major signaling pathways can have dramatic effects on tooth development. An important regulator of such subtle changes is the fine tuning function of microRNAs (miRNAs). However, the underlying mechanism by which miRNAs regulate tooth development remains elusive. This study determined the expression of miRNAs during cytodifferentiation in the human tooth germ and studied miR-34a as a regulator of dental papilla cell differentiation. Using microarrays, miRNA expression profiles were established at selected times during development (early bell stage or late bell stage) of the human fetal tooth germ. We identified 29 differentially expressed miRNAs from early bell stage/late bell stage comparisons. Out of 6 miRNAs selected for validation by qPCR, all transcripts were confirmed to be differentially expressed. miR-34a was selected for further investigation because it has been previously reported to regulate organogenesis. miR-34a mimics and inhibitors were transfected into human fetal dental papilla cells, mRNA levels of predicted target genes were detected by quantitative real-time PCR, and levels of putative target proteins were examined by western blotting. ALP and DSPP expression were also tested by qPCR, western blotting, and immunofluorescence. Findings from these studies suggested that miR-34a may play important roles in dental papilla cell differentiation during human tooth development by targeting NOTCH and TGF-beta signaling.

Intermittent dissipation at kinetic scales in collisionless plasma turbulence

High resolution kinetic simulations of collisionless plasma driven by shear show the development of turbulence characterized by dynamic coherent sheetlike current density structures spanning a range of scales down to electron scales. We present evidence that these structures are sites for heating and dissipation, and that stronger current structures signify higher dissipation rates. Evidently, kinetic scale plasma, like magnetohydrodynamics, becomes intermittent due to current sheet formation, leading to the expectation that heating and dissipation in astrophysical and space plasmas may be highly nonuniform and patchy.

3 distinct regions of chromosome-6 are targets of loss of heterozygosity in human ovarian carcinomas

We performed mapping studies of allelic deletions on chromosome 6 in 52 ovarian carcinomas using 20 polymorphic markers assigned to various regions of both chromosomal arms. Loss of heterozygosity was seen in 28 (55%) tumors. The allelic losses, however, did not involve the whole chromosome in 18 of those tumors, allowing further localization of the targeted chromosomal region(s). Three different chromosomal regions appeared involved based on the distribution of partial deletions, 2 on the long arm and one on the short arm. One of the 2 regions on the long arm was confined to band 6q27 whereas the other was between the Arg1 and estrogen receptor loci. The targeted region on the short arm was bounded by the D6S89 and D6S248 loci. These results suggest the presence of at least 3 different tumor suppressor genes important for the control of ovarian tumorigenesis on chromosome 6.

Overexpression of activin A inhibits growth, induces apoptosis, and suppresses tumorigenicity in an androgen-sensitive human prostate cancer cell line LNCaP

The effects of overexpression of activin A in the androgen-sensitive human prostate cancer cell line LNCaP were studied. A full-length cDNA of activin beta A coding region was inserted into a eukaryotic expression vector and transfected into the LNCaP cells. Overexpression of activin BA significantly inhibited growth of this cell line. An increased death rate was also noted in these activin-overproducing cells, which was believed to be due to apoptosis as manifested by morphological change, DNA laddering, and FAGS analysis. The expression of bcl-2 was suppressed and the expression of c-myc was stimulated in these cells. In addition, the efficiency of soft agar colony formation and the tumorigenicity in the nude mice were suppressed for the activin producing LNCaP cells.