Stem Cell Protein PIWIL2 Promotes EMT Process and Stem Cell-Like Properties in MCF7 Breast Cancer Cell Line

Background

Piwi-like RNA-mediated gene silencing 2 (PIWIL2) is a member of AGO/PIWI gene family, which is enriched in cancer stem cells (CSCs). The purpose of this research was to investigate the overexpression of PIWIL2 and its role in the induction of EMT and CSC properties in MCF7 breast cancer cell line.

Materials and Methods

MCF7 cells were transfected with the human gene PIWIL2 (Hili) under the control of CMV promoter utilizing the neon electroporation method. Subsequently, the selection was conducted using G418, and doubling time was calculated in the transformed and control cells. RT and real-time PCR were also performed to analyze the expression of epithelial and mesenchymal genes and those related to CSCs.

Results

According to the observations from this study, transfecting MCF7 cells with PIWIL2 triggered the conversion of epithelial cells to mesenchymal cells and induced the genes specific for breast CSCs, which was coincident with 9-h reduction in the doubling time of the transfected cells. Furthermore, the molecular analyses revealed a significant reduction in the expression of epithelial markers, while a significant increase was detected in the expression of mesenchymal genes and many CSC biomarkers.

Conclusion

PIWIL2 protein acts as a master regulatory protein that is able to manipulate the transcription through specific signaling pathways, which allow the cells to gain stem cell-like properties.

Optimization of 3D islet-like cluster derived from human pluripotent stem cells: an efficient in vitro differentiation protocol

Development of an optimized protocol to produce sufficient functional human insulin-producing islet-like cluster is important as a potential therapeutic strategy for diabetes as well as in vitro studies. Here, we described a stepwise protocol for differentiation of the human induced pluripotent stem cell line (R1-hiPSC1) into the islet-like cluster using several growth factors and small molecules. Therefore, various differentiation steps have been adopted to maximize mimicking of developmental processes in order to form functional islet like cluster. The differentiation protocol enables us to generate 3D islet-like clusters with highly viable cells, which are insulin producer and glucose responsive. Transcriptome analysis of transcription factors and functional genes revealed high coordination between gene expressions and resembling to those reported during natural development of islet cell. This coordination was further confirmed by hierarchical clustering of genes during differentiation. Furthermore, the islet-like clusters were enriched with insulin producing cells and formed glucose responsiveness behavior upon stimulation with glucose. Our protocol provides a robust platform and well-behaved model for additional developmental studies and shed light our clusters as a good candidate for in vitro model. Further studies are needed to assess the hormonal content of this cluster as well as transplantation into the animal model.

Bcl11a and the Correlated Key Genes Ascribable to Globin Switching: An In-silico Study

BACKGROUND

Reactivation of HbF is a potential strategy to ameliorate symptoms of hemoglobinopathies such as sickle cell disease and b-thalassemia. After birth, there is a switch from fetal to adult hemoglobin, for which the molecular mechanisms and key regulators await further understanding in order to develop effective methods for HbF reactivation. BCL11A, one of the major HbF reactivation regulators, demonstrates no significant changes at transcriptional levels in F erythroblasts compared to the non-HbF expressing cells. Therefore, it is possible that post-transcriptional regulation and epigenetic effects, for which the miRNAs play an important role, are the primary causes of the decreased BCL11A protein level in adult erythroblasts.

OBJECTIVE

The aim of this paper is to determine the differentially expressed mRNAs and miRNAs of erythroblasts in HSCs from the fetal liver and bone marrow.

METHODS

Raw high-throughput sequencing data (GSE110936, GSE90878) was downloaded from Gene Expression Omnibus (GEO) database. After RNAseq analysis, several data sets and tools were used to select key genes and examine selection validation.

RESULTS

We selected 42 DEmRNAs and nine DEmiRs, including hsa-let-7f-5p, hsa-miR-21-5p, hsa-miR-22-3p, hsa-miR-126-5p, hsa-miR-146b-5p, hsa-miR-181a-5p, hsa-miR-92a-3p, hsa-miR-25-3p and hsa-miR-191-5p. Furthermore, hub genes including hist1h2bl, al133243.2, trim58, abcc13, bpgm, and fam210b were identified in the coexpression network, as well as RPS27A in the PPI network. Functional analysis revealed that these DEmRNAs and DEmiRs may play a role in gene expression regulation at multiple levels. Gene set enrichment analysis, in particular, revealed a possible role for genes in the globin switching process.

CONCLUSION

According to our findings, a number of the DEmRNAs and DEmiRs may play significant roles in globin switching regulation and thus have the potential to be applied for HbF reactivation.

Y Chromosome Genes May Play Roles in the Development of Neural Rosettes from Human Embryonic Stem Cells

BACKGROUND

The human Y chromosome harbors genes that are mainly involved in the growth, development, sexual dimorphism, and spermatogenesis process. Despite many studies, the function of the male-specific region of the Y chromosome (MSY) awaits further clarification, and a cell-based approach can help in this regard.

RESULTS

In this study, we have developed four stable transgenic male embryonic stem cell (ESCs) lines that can overexpress male-specific genes HSFY1, RBMY1A1, RPS4Y1, and SRY. As a proof of principle, we differentiated one of these cell lines (RPS4Y1 over-expressing ESCs) to the neural stem cell (rosette structure) and characterized them based on the expression level of lineage markers. RPS4Y1 expression in the Doxycycline-treated group was significantly higher than control groups at transcript and protein levels. Furthermore, we found Doxycycline-treated group had a higher differentiation efficiency than the untreated control groups.

CONCLUSIONS

Our results suggest that the RPS4Y1 gene may play a critical role in neurogenesis. Also, the generated transgenic ESC lines can be widely employed in basic and preclinical studies, such as sexual dimorphism of neural and cardiac functions, the development of cancerous and non-cancerous disease models, and drug screening.

The Contribution of Y Chromosome Genes to Spontaneous Differentiation of Human Embryonic Stem Cells into Embryoid Bodies In Vitro

Objective

Sexual dimorphism in mammals can be described as subsequent transcriptional differences from their distinct sex chromosome complements. Following X inactivation in females, the Y chromosome is the major genetic difference between sexes. In this study, we used a male embryonic stem cell line (Royan H6) to identify the potential role of the male-specific region of the Y chromosome (MSY) during spontaneous differentiation into embryoid bodies (EBs) as a model of early embryonic development.

Materials and Methods

In this experimental study, RH6 cells were cultured on inactivated feeder layers and Matrigel. In a dynamic suspension system, aggregates were generated in the same size and were spontaneously differentiated into EBs. During differentiation, expression patterns of specific markers for three germ layers were compared with MSY genes.

Results

Spontaneous differentiation was determined by downregulation of pluripotent markers and upregulation of fourteen differentiation markers. Upregulation of the ectoderm markers was observed on days 4 and 16, whereas mesoderm markers were upregulated on the 8th day and endodermic markers on days 12-16. Mesoderm markers correlated with 8 MSY genes namely DDX3Y, RPS4Y1, KDM5D, TBL1Y, BCORP1, PRY, DAZ, and AMELY, which were classified as a mesoderm cluster. Endoderm markers were co-expressed with 7 MSY genes, i.e. ZFY, TSPY, PRORY, VCY, EIF1AY, USP9Y, and RPKY, which were grouped as an endoderm cluster. Finally, the ectoderm markers correlated with TXLNGY, NLGN4Y, PCDH11Y, TMSB4Y, UTY, RBMY1, and HSFY genes of the MSY, which were categorized as an ectoderm cluster. In contrast, 2 MSY genes, SRY and TGIF2LY, were more highly expressed in RH6 cells compared to EBs.

Conclusion

We found a significant correlation between spontaneous differentiation and upregulation of specific MSY genes. The expression alterations of MSY genes implied the potential responsibility of their gene co-expression clusters for EB differentiation. We suggest that these genes may play important roles in early embryonic development.

Optimization of activin-A: a breakthrough in differentiation of human induced pluripotent stem cell into definitive endoderm

The first step in differentiation of pluripotent stem cell toward endoderm-derived cell/organ is differentiation to definitive endoderm (DE) which is the central issue in developmental biology. Based on several evidences, we hypothesized that activin-A optimization as well as replacement of fetal bovine serum (FBS) with knockout serum replacement (KSR) is important for differentiation of induced pluripotent stem cell (iPSC) line into DE. Therefore, a stepwise differentiation protocol was applied on R1-hiPSC1 cell line. At first, activin-A concentration (30, 50, 70 and 100 ng/ml) was optimized. Then, substitution of FBS with KSR was evaluated across four treatment groups. The amount of differentiation of iPSC toward DE was determined by quantitative gene expression analyses of pluripotency (NANOG and OCT4), definitive endoderm (SOX17 and FOXA2) and endoderm-derived organs (PDX1, NEUROG3, and PAX6). Based on gene expression analyses, the more decrease in concentrations of activin-A can increase the differentiation of iPSC into DE, therefore, 30 ng/ml activin-A was chosen as the best concentration for the differentiation of R1-hiPSC1 line toward endoderm-derived organ. Moreover, complete replacement of FBS with gradually increased KSR improved the differentiation of iPSC toward DE. For this reason, the addition of 0% KSR at day 1, 0.2% at day 2 and 2% for the next 3 days was the best optimal protocol of the differentiation of iPSC toward DE. Overall, our results demonstrate that optimization of activin-A is important for differentiation of iPSC line. Furthermore, the replacement of FBS with KSR can improve the efficiency of iPSC differentiation toward DE.

Potential role of RAB6C-AS1 long noncoding RNA in different cancers

BACKGROUND

Long noncoding RNAs (lncRNAs) refer to a group of non-protein-coding RNAs that are usually more than 200 nucleotides. These long transcripts play significant roles in diverse cellular processes, mostly through epigenetic mechanisms. Thus, dysregulation of lncRNAs is associated with various diseases, especially cancer. This study aims to investigate the probable roles of RAB6C-AS1 lncRNA in different cancers.

METHODS

Real-time quantitative reverse transcription-polymerase chain reaction was applied for the analysis of RAB6C-AS1 lncRNA amplification in gastric cancer (GC) samples compared with normal ones. Also, several online and offline data sets and tools were used to analyze the relation between RAB6C-AS1 lncRNA and different cancers.

RESULTS

The end result of our analyses indicated that RAB6C-AS1 was overexpressed in 40% of the investigated GC specimens. Also, the results demonstrated a true relation between RAB6C-AS1 overexpression and higher GC tumor grades. However, bioinformatic analyses showed that while RAB6C-AS1 possibly functions as an oncogene in some cancer types, including prostate and breast cancers, it might have a tumor suppressive function in some others including brain tumors.

CONCLUSIONS

We found that RAB6C-AS1 lncRNA is mostly overexpressed in GC. Also, based on bioinformatic and systems biology analyses, RAB6C-AS1 might function either as an oncogenic factor or tumor suppressor in a tissue-specific manner. Thus, RAB6C-AS1 could be considered as a candidate biomarker for various malignancies, especially prostate and brain cancers. According to our results, RAB6C-AS1 has a notable prognostic value for patients with brain lower grade glioma.

In vitro-derived gametes from stem cells

Sperm and eggs are essential cells for reproduction and fertility in mammals. Lack of sperm production is one of the leading causes of infertility, a major and growing problem in the developed world affecting 13 to 18% of reproductive-age couples. The birth of the first test tube baby by in vitro fertilization marked an advance in infertility treatment. Later on, several important new techniques called assisted reproductive technologies were developed to help couples who experience infertility. One limiting factor is the requirement of reproductive cells (gametes) for use in in vitro fertilization. For azoospermic men lacking sperm cells, producing gametes in vitro could be a new window to overcome infertility. In the past few years, several reports have been published on generating germ cells from stem cells, one of the epitomes of which was the report on functional in vitro-derived (IVD) germ cells. These mature haploid sperm cells from mouse embryonic stem cells were capable of egg fertilization and producing live offspring. In tandem with previous advancements in germ cell research, development of new technologies based on IVD gametes will change the future of infertility and provide a new basis for the establishment of novel therapeutic approaches to cure more complicated conditions of infertility. In addition, IVD gametogenesis provides an accessible system for studying the specification and differentiation of sperm cells and related processes such as meiosis, morphogenesis, and motility.

A novel in vitro model for cancer stem cell culture using ectopically expressed piwil2 stable cell line

OBJECTIVE

Piwil2, a member of Ago/Piwi gene family containing Piwi and PAZ domains, has been shown to be ectopically expressed in different cancer cells, especially its remarkable expression in cancer stem cells (CSCs), and is also known to be essential for germ line stem cell self-renewal in various organisms. The hypothesis that CSC may hold the key to the central problem of clinical oncology and tumor relapse leads to more anticancer treatment studies. Due to emerging controversies and extreme difficulties in studying of CSC, like the cells using in vivo models, more attempts have expended to establish different in vitro models. However, the progress was slow owing to the problems associated with establishing proper CSC cultures in vitro. To overcome these difficulties, we prompted to establish a novel stable cell line over-expressing Piwil2 to develop a potential proper in vitro CSC model.

MATERIALS AND METHODS

In this experimental study, mouse embryonic fibroblasts (MEFs) were isolated and electroporated with a construct containing Piwil2 cDNA under the control of the cytomegalovirus promoter (CMV). Stable transfectants were selected, and the established MEF-Piwil2 cell line was characterized and designated as CSC-like cells using molecular markers. Functional assays, including proliferation, migration, and invasion assays were performed using characterized CSC like cells in serum-free medium. Additionally, MEF-Piwil2 cell density and viability were measured by direct and indirect methods in normoxic and hypoxic conditions.

RESULTS

The results of reverse transcriptase-polymerase chain reaction (RT-PCR), western blot, and immunocytochemistry revealed an overexpression for Piwil2 in the transfected Piwil2 cells both in the RNA and protein levels. Furthermore, analysis of the kinetic and stoichiometric parameters demonstrated that the specific growth rate and the yield of lactate per glucose were significantly higher in the MEF-Piwil2 group compared to the MEF cells (ANOVA, p< 0.05). Also, analysis of functional assays including migration and invasion assays demonstrated a significantly higher number of migrated and invaded cells in the MEF-Piwil2 compared to that of the MEF cells (ANOVA, p< 0.05). The MEF-Piwil2 cells tolerated hypoxia mimetic conditions (CoCl2 ) with more than 95% viability.

CONCLUSION

According to the molecular and functional studies, it has been realized that Piwil2 plays a key role(s) in tumor initiation, progression and metastasis. Therefore, Piwil2 can be used not only as a common biomarker for tumor, but also as a target for the development of new anticancer drug. Finally, the main outcome of our study was the establishment of a novel CSC-like in vitro model which is expected to be utilized in understanding the complex roles played by CSC in tumor maintenance, metastasis, therapy resistance or cancer relapse.

Pathways of proliferation and antiapoptosis driven in breast cancer stem cells by stem cell protein piwil2

Cancer stem cell studies may improve understanding of tumor pathophysiology and identify more effective strategies for cancer treatment. In a variety of organisms, Piwil2 has been implicated in multiple roles including stem cell self-renewal, RNA silencing, and translational control. In this study, we documented specific expression of the stem cell protein Piwil2 in breast cancer with predominant expression in breast cancer stem cells. In patients who were evaluated, we determined that 90% of invasive carcinomas and 81% of carcinomas in situ exhibited highest expression of Piwil2. In breast cancer cells, Piwil2 silencing suppressed the expression of signal transducer and activator of transcription 3, a pivotal regulator of Bcl-X(L) and cyclin D1, whose downregulation paralleled a reduction in cell proliferation and survival. Our findings define Piwil2 and its effector signaling pathways as key factors in the proliferation and survival of breast cancer stem cells.

mtRF1a is a human mitochondrial translation release factor decoding the major termination codons UAA and UAG

Human mitochondria contain their own genome, encoding 13 polypeptides that are synthesized within the organelle. The molecular processes that govern and facilitate this mitochondrial translation remain unclear. Many key factors have yet to be characterized—for example, those required for translation termination. All other systems have two classes of release factors that either promote codon-specific hydrolysis of peptidyl-tRNA (class I) or lack specificity but stimulate the dissociation of class I factors from the ribosome (class II). One human mitochondrial protein has been previously identified in silico as a putative member of the class I release factors. Although we could not confirm the function of this factor, we report the identification of a different mitochondrial protein, mtRF1a, that is capable in vitro and in vivo of terminating translation at UAA/UAG codons. Further, mtRF1a depletion in HeLa cells led to compromised growth in galactose and increased production of reactive oxygen species.