Targeting of the tumor suppressor GRHL3 by a miR-21-dependent proto-oncogenic network results in PTEN loss and tumorigenesis

Exosomal miR-532-5p from bone marrow mesenchymal stem cells reduce intervertebral disc degeneration by targeting RASSF5

The transplantation of bone marrow mesenchymal stem cells (BMSCs) has been found to be used as an effective therapy of intervertebral disc degeneration (IDD). However, the underlying mechanisms of BMSCs in the progress of IDD are not fully explained. In this study, we found that exosomes derived from BMSCs (BMSCs-Exos) inhibited the apoptotic rate, extracellular matrix (ECM) degradation, and fibrosis deposition in TNF-α-induced nucleus pulposus cells (NPCs). Importantly, the level of miR-532-5p was observed to be decreased in apoptotic NPCs, but abundant in BMSCs-Exos with TNF-α treatment. The results showed that BMSCs-Exos under TNF-α stimuli exerted better effects on NPCs than BMSCs-Exos, which might be mitigated by the inhibition of miR-532-5p in BMSCs-Exos. The gain-of-function results suggested that the direct overexpression of miR-532-5p in NPCs could inhibit TNF-α-induced increase of apoptotic process, activation of apoptotic proteins, imbalance of anabolism/catabolism levels, and accumulation of collagen I. In addition, RASSF5 was demonstrated to be a target of miR-532-5p. Knockdown of RASSF5 could decrease the apoptotic cells and reduce the activated apoptotic protein levels in TNF-α-induced NPCs. Overall, these data indicate that exosomes from BMSCs may suppress TNF-α-induced apoptosis, ECM degradation, and fibrosis deposition in NPCs through the delivery of miR-532-5p via targeting RASSF5. This work provides a promising therapeutic strategy for the progress of IDD.

Porphyromonas gingivalis Promotes the Proliferation and Migration of Esophageal Squamous Cell Carcinoma through the miR-194/GRHL3/PTEN/Akt Axis

Recent studies have revealed that Porphyromonas gingivalis is closely related to the occurrence and progression of esophageal squamous cell carcinoma (ESCC). However, the underlying mechanism of P. gingivalis in ESCC has not been well elucidated. To explore the mechanism of P. gingivalis infection in ESCC, cellular proliferation, invasion, and migration models of KYSE-30 and KYSE-150 cells infected by P. gingivalis at a multiplicity of infection (MOI) of 10 were established. The results showed that P. gingivalis infection could drastically increase the proliferation, invasion, and migration ability of ESCC. Furthermore, the results of high-throughput sequencing showed that miR-194 was considerably upregulated in infected cells compared with control cells, which was further verified by qRT-PCR. The inhibition or overexpression of miR-194 had a significant effect on KYSE-30 and KYSE-150 cell migration and invasion. Additionally, the levels of GRHL3 and PTEN were decreased in P. gingivalis-infected esophageal cancer cells compared with uninfected esophageal cancer cells. Furthermore, dual-luciferase experiments confirmed that GRHL3 is a direct target of miR-194. In addition, the GRHL3-related pathway was investigated, and the levels of GRHL3 and PTEN were downregulated while the level of p-Akt was upregulated after P. gingivalis infection. Taken together, these findings indicated that P. gingivalis might promote ESCC proliferation and migration via the miR-194/GRHL3/PTEN/Akt signaling axis.

Grainyhead-Like Genes Family May Act as Novel Biomarkers in Colon Cancer

OBJECTIVE

The Grainyhead-like (GRHL) genes family were reported to participate in the development of a number of diseases. This study was designed to investigate the role of GRHL genes family in colon cancer (CC).

METHODS

In this study, the transcriptional levels of GRHL genes family in patients with CC from GEPIA were explored. Meanwhile, the immunohistochemical data of the GRHL genes family were also obtained in the HPA database. Additionally, we re-identified the mRNA of these genes via real-time PCR. Furthermore, the association between the levels of GRHL genes and stage plot as well as survival condition including overall survival and disease-free survival of patients with CC was analyzed. Finally, by transfecting with specific-siRNA, clone formation assay was performed to observe the role of GRHL genes family in the proliferation of SW480 human colon cancer cells.

RESULTS

We found that the mRNA and protein levels of GRHL1, GRHL2 and GRHL3 were significantly higher in CC tissues than in normal colon tissues. Additionally, GRHL1, GRHL2 and GRHL3 were significantly associated with the stages of CC. The Kaplan-Meier plotter showed that the low levels of GRHL1, GRHL2 and GRHL3 conferred a better overall survival of patients with CC while the high levels of GRHL1 and GRHL3 were associated with poor disease-free survival. Knockdown of GRHL1, GRHL2 and GRH L3 siHgnificantly inhibited the ability of colony formation of human colon cancer cells.

CONCLUSION

Our study demonstrated that GRHL genes are involved in the prognosis and survival in patients with CC, the inhibition of which may suppress the proliferation of colon cancer cells.

The secretome of skin cancer cells activates the mTOR/MYC pathway in healthy keratinocytes and induces tumorigenic properties

Cutaneous squamous cell carcinoma (cSCC) is the most prominent tumor of non-melanoma skin cancers and the most aggressive tumor among keratinocyte carcinoma of the skin, showing a high potential for local invasion and metastasis. The cSCC incidences increased dramatically in recent years and the disease occurs more commonly than any other malignancy. The secretome of cancer cells is currently the focus of many studies in order to identify new marker proteins for different types of cancer and to investigate its influence on the tumor microenvironment. In our study we evaluated whether the secretome of cSCC cells has an impact on keratinocytes, the surrounding tissue cells of cSCC. Therefore, we analyzed and compared the secretome of human A431 cancer cells and of HaCaT keratinocytes by mass spectrometry. In a second experiment, keratinocytes were exposed to the secretome of A431 cells and vice versa and the transcriptome was analyzed by next-generation sequencing. HaCaT cells incubated with A431 conditioned medium revealed a significantly activated mammalian target of rapamycin pathway with a concomitant increase in proliferation and migration. In conclusion, our data demonstrate the impact of the secretome of cancer cells on the transcription machinery of the cells surrounding the tumor, leading to a tumorigenic cell fate.

Meta-Analysis of Grainyhead-Like Dependent Transcriptional Networks: A Roadmap for Identifying Novel Conserved Genetic Pathways

The Drosophila grainyhead (grh) and vertebrate Grainyhead-like (Grhl) transcription factors are among the most critical genes for epithelial development, maintenance and homeostasis, and are remarkably well conserved from fungi to humans. Mutations affecting grh/Grhl function lead to a myriad of developmental and adult onset epithelial disease, such as aberrant skin barrier formation, facial/palatal clefting, impaired neural tube closure, age-related hearing loss, ectodermal dysplasia, and importantly, cancers of epithelial origin. Recently, mutations in the family member GRHL3 have been shown to lead to both syndromic and non-syndromic facial and palatal clefting in humans, particularly the genetic disorder Van Der Woude Syndrome (VWS), as well as spina bifida, whereas mutations in mammalian Grhl2 lead to exencephaly and facial clefting. As transcription factors, Grhl proteins bind to and activate (or repress) a substantial number of target genes that regulate and drive a cascade of transcriptional networks. A multitude of large-scale datasets have been generated to explore the grh/Grhl-dependent transcriptome, following ablation or mis-regulation of grh/Grhl-function. Here, we have performed a meta-analysis of all 41 currently published grh and Grhl RNA-SEQ, and microarray datasets, in order to identify and characterise the transcriptional networks controlled by grh/Grhl genes across disparate biological contexts. Moreover, we have also cross-referenced our results with published ChIP and ChIP-SEQ datasets, in order to determine which of the critical effector genes are likely to be direct grh/Grhl targets, based on genomic occupancy by grh/Grhl genes. Lastly, to interrogate the predictive strength of our approach, we experimentally validated the expression of the top 10 candidate grhl target genes in epithelial development, in a zebrafish model lacking grhl3, and found that orthologues of seven of these (cldn23, ppl, prom2, ocln, slc6a19, aldh1a3, and sod3) were significantly down-regulated at 48 hours post-fertilisation. Therefore, our study provides a strong predictive resource for the identification of putative grh/grhl effector target genes.

Pten loss in Lgr5+ hair follicle stem cells promotes SCC development

Accumulating data support that tissue stem cells give rise to cancer cells. Hair follicle stem cells (HFSCs) undergo cyclic quiescence and activation and may sever as the origin of cutaneous squamous cell carcinoma (SCC). Pten is a tumor suppressor gene that is frequently mutated in hereditary cancer syndromes such as Cowden disease, which is featured with papillomatosis in cutaneous tissues and hyperkeratosis in the acral region of the skin. Additionally, mice with keratinocyte-specific Pten deficiency (k5-Pten^-/- mice) show epidermal hyperplasia and spontaneous tumor formation. However, the impact of Pten mutation in HFSCs, such as in Lgr5⁺ HFSCs, on SCC formation is unclear.

Methods: We established experiments with wildtype and Lgr5-CreER; Pten^flox/flox mice, and used DMBA/TPA two-stage skin carcinogenesis model to explore the effect of Pten loss in Lgr5⁺ HFSCs of 3 weeks old mice in skin carcinogenesis. In vitro experiments (cell culture and protein expression analysis) are employed to investigate molecular mechanisms involved.

Results: Pten loss in Lgr5⁺ HFSCs promoted SCC formation, which was attenuated in TNF^-/- mice. Notably, β-catenin loss in Lgr5⁺ HFSCs decreased the formation of SCC. In addition, Pten loss in cultured epidermal stem cells upregulated the levels of both phospho-Akt and β-catenin.

Conclusion: Pten loss in Lgr5⁺ cells induced Akt/β-catenin signaling, and SCCs can subsequently be raised as progeny from these primed Lgr5⁺ stem cells.

Structural basis of gene regulation by the Grainyhead/CP2 transcription factor family

Grainyhead (Grh)/CP2 transcription factors are highly conserved in multicellular organisms as key regulators of epithelial differentiation, organ development and skin barrier formation. In addition, they have been implicated as being tumor suppressors in a variety of human cancers. Despite their physiological importance, little is known about their structure and DNA binding mode. Here, we report the first structural study of mammalian Grh/CP2 factors. Crystal structures of the DNA-binding domains of grainyhead-like (Grhl) 1 and Grhl2 reveal a closely similar conformation with immunoglobulin-like core. Both share a common fold with the tumor suppressor p53, but differ in important structural features. The Grhl1 DNA-binding domain binds duplex DNA containing the consensus recognition element in a dimeric arrangement, supporting parsimonious target-sequence selection through two conserved arginine residues. We elucidate the molecular basis of a cancer-related mutation in Grhl1 involving one of these arginines, which completely abrogates DNA binding in biochemical assays and transcriptional activation of a reporter gene in a human cell line. Thus, our studies establish the structural basis of DNA target-site recognition by Grh transcription factors and reveal how tumor-associated mutations inactivate Grhl proteins. They may serve as points of departure for the structure-based development of Grh/CP2 inhibitors for therapeutic applications.

Targeted Therapy Against the Cell of Origin in Cutaneous Squamous Cell Carcinoma

Squamous cell carcinomas (SCC), including cutaneous SCCs, are by far the most frequent cancers in humans, accounting for 80% of all newly diagnosed malignancies worldwide. The old dogma that SCC develops exclusively from stem cells (SC) has now changed to include progenitors, transit-amplifying and differentiated short-lived cells. Accumulation of specific oncogenic mutations is required to induce SCC from each cell population. Whilst as fewer as one genetic hit is sufficient to induce SCC from a SC, multiple events are additionally required in more differentiated cells. Interestingly, the level of differentiation correlates with the number of transforming events required to induce a stem-like phenotype, a long-lived potential and a tumourigenic capacity in a progenitor, a transient amplifying or even in a terminally differentiated cell. Furthermore, it is well described that SCCs originating from different cells of origin differ not only in their squamous differentiation status but also in their malignant characteristics. This review summarises recent findings in cutaneous SCC and highlights transforming oncogenic events in specific cell populations. It underlines oncogenes that are restricted either to stem or differentiated cells, which could provide therapeutic target selectivity against heterogeneous SCC. This strategy may be applicable to SCC from different body locations, such as head and neck SCCs, which are currently still associated with poor survival outcomes.

MicroRNA Dysregulation in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and it can be locally invasive and metastatic to distant sites. MicroRNAs (miRNAs or miRs) are endogenous, small, non-coding RNAs of 19–25 nucleotides in length, that are involved in regulating gene expression at a post-transcriptional level. MicroRNAs have been implicated in diverse biological functions and diseases. In cancer, miRNAs can proceed either as oncogenic miRNAs (onco-miRs) or as tumor suppressor miRNAs (oncosuppressor-miRs), depending on the pathway in which they are involved. Dysregulation of miRNA expression has been shown in most of the tumors evaluated. MiRNA dysregulation is known to be involved in the development of cutaneous squamous cell carcinoma (CSCC). In this review, we focus on the recent evidence about the role of miRNAs in the development of CSCC and in the prognosis of this form of skin cancer.

mTOR Signalling in Head and Neck Cancer: Heads Up

The mammalian target of rapamycin (mTOR) signalling pathway is a central regulator of metabolism in all cells. It senses intracellular and extracellular signals and nutrient levels, and coordinates the metabolic requirements for cell growth, survival, and proliferation. Genetic alterations that deregulate mTOR signalling lead to metabolic reprogramming, resulting in the development of several cancers including those of the head and neck. Gain-of-function mutations in EGFR, PIK3CA, and HRAS, or loss-of-function in p53 and PTEN are often associated with mTOR hyperactivation, whereas mutations identified from The Cancer Genome Atlas (TCGA) dataset that potentially lead to aberrant mTOR signalling are found in the EIF4G1, PLD1, RAC1, and SZT2 genes. In this review, we discuss how these mutant genes could affect mTOR signalling and highlight their impact on metabolic processes, as well as suggest potential targets for therapeutic intervention, primarily in head and neck cancer.

Knockdown of GRHL2 inhibited proliferation and induced apoptosis of colorectal cancer by suppressing the PI3K/Akt pathway

Grainyhead-like 2 (GRHL2) transcription factor is implicated in many types of cancers. However, the role of GRHL2 in colorectal cancer (CRC) has not been fully understood. The present study aimed to evaluate the expression and functional roles of GRHL2 in CRC. The expression of GRHL2 in normal human intestinal epithelial cells and colorectal cancer cells was measured by qRT-PCR and western blot. For knockdown of GRHL2, two small interfere RNAs (siRNAs) targeting GRHL2 or control siRNA was transfected into CRC cell lines (HCT116 and HT29). For GRHL2 overexpression, the GRHL2-overexpressing vector or empty lentiviral vector was infected into HCT116 and HT29 cells. Cell proliferation was measured by MTT assay. Cell apoptosis rate was analyzed by flow cytometry. The expression of proliferating cell nuclear antigen (PCNA), Bax, and Bcl-2 was detected by western blot. We found that GRHL2 was upregulated in CRC cells compared to normal human intestinal epithelial cells. Knockdown of GRHL2 inactivated the PI3K/Akt pathway in HCT116 and HT29 cells. Knockdown of GRHL2 inhibited cell viability, elevated the apoptosis rates, suppressed the expression of PCNA and Bcl-2, and induced the expression of Bax in HCT116 and HT29 cells, and these effects were reversed by activation of the PI3K/Akt pathway. Inhibition of PI3K/Akt pathway blocked the effects of GRHL2 overexpression on cell proliferation and apoptosis. In conclusion, GRHL2 acted as an oncoprotein through regulating cell proliferation and apoptosis in CRC cells. The PI3K/Akt pathway was closely involved in the effects of GRHL2. Therefore, GRHL2 might be a therapeutic target for the CRC treatment.

MicroRNA-498 promotes proliferation and migration by targeting the tumor suppressor PTEN in breast cancer cells

Triple negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and high mortality rate. The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) plays an important role in cell proliferation and cell migration by negatively regulating the PI3K/Akt pathway. PTEN is downregulated by microRNAs in multiple cancers. However, few microRNAs have been reported to directly target PTEN in TNBC. In this study, microRNAs predicted to target PTEN were screened by immunoblotting and luciferase reporter assays. Expression levels of microRNA-498 (miR-498) were measured by TaqMan microRNA assays. We performed clonogenic, cell cycle and scratch wound assays to examine the oncogenic role of miR-498. We demonstrated that miR-498 directly targeted the 3'untranslated region of PTEN mRNA and reduced PTEN protein levels in TNBC cells. Compared with the non-tumorigenic breast epithelial cell line MCF-10A, TNBC cell lines overexpressed miR-498. Moreover, miR-498 promoted cell proliferation and cell cycle progression in TNBC cells in a PTEN-dependent manner. Suppressing miR-498 overexpression impaired the oncogenic effects of miR-498 on cell proliferation and cell migration. This study identified a novel microRNA (miR-498) overexpressed in TNBC cells and its oncogenic role in suppressing PTEN. These results provide new insight into the downregulation of PTEN and indicate a potential therapeutic target for treating TNBC.

Loss of GRHL3 leads to TARC/CCL17-mediated keratinocyte proliferation in the epidermis

Identifying soluble factors that influence epidermal integrity is critical for the development of preventative and therapeutic strategies for disorders such as ichthyosis, psoriasis, dermatitis and epidermal cancers. The transcription factor Grainyhead-like 3 (GRHL3) is essential for maintaining barrier integrity and preventing development of cutaneous squamous cell carcinoma (SCC); however, how loss of this factor, which in the skin is expressed exclusively within suprabasal epidermal layers triggers proliferation of basal keratinocytes, had thus far remained elusive. Our present study identifies thymus and activation-regulated chemokine (TARC) as a novel soluble chemokine mediator of keratinocyte proliferation following loss of GRHL3. Knockdown of GRHL3 in human keratinocytes showed that of 42 cytokines examined, TARC was the only significantly upregulated chemokine. Mouse skin lacking Grhl3 presented an inflammatory response with hallmarks of TARC activation, including heightened induction of blood clotting, increased infiltration of mast cells and pro-inflammatory T cells, increased expression of the pro-proliferative/pro-inflammatory markers CD3 and pSTAT3, and significantly elevated basal keratinocyte proliferation. Treatment of skin cultures lacking Grhl3 with the broad spectrum anti-inflammatory 5-aminosalicylic acid (5ASA) partially restored epidermal differentiation, indicating that abnormal keratinocyte proliferation/differentiation balance is a key driver of barrier dysfunction following loss of Grhl3, and providing a promising therapeutic avenue in the treatment of GRHL3-mediated epidermal disorders.

Large-scale transcriptome-wide association study identifies new prostate cancer risk regions

Although genome-wide association studies (GWAS) for prostate cancer (PrCa) have identified more than 100 risk regions, most of the risk genes at these regions remain largely unknown. Here we integrate the largest PrCa GWAS (N = 142,392) with gene expression measured in 45 tissues (N = 4458), including normal and tumor prostate, to perform a multi-tissue transcriptome-wide association study (TWAS) for PrCa. We identify 217 genes at 84 independent 1 Mb regions associated with PrCa risk, 9 of which are regions with no genome-wide significant SNP within 2 Mb. 23 genes are significant in TWAS only for alternative splicing models in prostate tumor thus supporting the hypothesis of splicing driving risk for continued oncogenesis. Finally, we use a Bayesian probabilistic approach to estimate credible sets of genes containing the causal gene at a pre-defined level; this reduced the list of 217 associations to 109 genes in the 90% credible set. Overall, our findings highlight the power of integrating expression with PrCa GWAS to identify novel risk loci and prioritize putative causal genes at known risk loci.

MicroRNA-340 inhibits squamous cell carcinoma cell proliferation, migration and invasion by downregulating RhoA

BACKGROUND

MicroRNAs are reported to play an important role in tumor growth and metastasis, including squamous cell carcinoma (SCC). Accumulative evidence has revealed that dysregulated miR-340 expression contributed to the carcinogenesis and development of various cancers.

OBJECTIVE

The aim of the current study was to investigate the role and the underlying mechanism of miR-340 in SCC cell proliferation, migration and invasion.

METHODS

Quantitative real-time PCR was performed to examine the expression of miR-340 in SCC tissues and cell lines. The function of miR-340 in SCC was investigated through Cell Counting Kit-8, wound healing, transwell migration and invasion assays. Bioinformatics analysis, luciferase reporter assay, western blotting and immunohistochemical analysis were conducted to predict and confirm the target gene of miR-340.

RESULTS

In the present study, we first found that miR-340 was significantly decreased in both SCC tissues and cell lines. Moreover, ectopic expression of miR-340 remarkably attenuated SCC cell proliferation, migration and invasion, whereas inhibition of endogenous miR-340 promoted SCC cell proliferation, migration and invasion in vitro. Our subsequent bioinformatics analysis and luciferase reporter assay showed that RhoA was a novel direct target of miR-340 in SCC cells, and the knockdown of RhoA expression rescued the effects of miR-340 inhibition on SCC cell proliferation, migration and invasion. More importantly, the expression of RhoA and miR-340 was negatively correlated in SCC tissues.

CONCLUSION

Our findings demonstrate the tumor suppressor role of miR-340 in SCC by directly regulating RhoA. Therefore, restoration of miR-340 expression can be a potential therapeutic approach for SCC treatment.

Selection and Application of Tissue microRNAs for Nonendoscopic Diagnosis of Barrett's Esophagus

BACKGROUND & AIMS

MicroRNA (miRNA) is highly stable in biospecimens and provides tissue-specific profiles, making it a useful biomarker of carcinogenesis. We aimed to discover a set of miRNAs that could accurately discriminate Barrett's esophagus (BE) from normal esophageal tissue and to test its diagnostic accuracy when applied to samples collected by a noninvasive esophageal cell sampling device.

METHODS

We analyzed miRNA expression profiles of 2 independent sets of esophageal biopsy tissues collected during endoscopy from 38 patients with BE and 26 patients with normal esophagus (controls) using Agilent microarray and Nanostring nCounter assays. Consistently up-regulated miRNAs were quantified by real-time polymerase chain reaction in esophageal tissues collected by Cytosponge from patients with BE vs without BE. miRNAs were expressed from plasmids and antisense oligonucleotides were expressed in normal esophageal squamous cells; effects on proliferation and gene expression patterns were analyzed.

RESULTS

We identified 15 miRNAs that were significantly up-regulated in BE vs control tissues. Of these, 11 (MIR215, MIR194, MIR 192, MIR196a, MIR199b, MIR10a, MIR145, MIR181a, MIR30a, MIR7, and MIR199a) were validated in Cytosponge samples. The miRNAs with the greatest increases in BE tissues (7.9-fold increase in expression or more, P < .0001: MIR196a, MIR192, MIR194, and MIR215) each identified BE vs control tissues with area under the curve (AUC) values of 0.82 or more. We developed an optimized multivariable logistic regression model, based on expression levels of 6 miRNAs (MIR7, MIR30a, MIR181a, MIR192, MIR196a, and MIR199a), that identified patients with BE with an AUC value of 0.89, 86.2% sensitivity, and 91.6% specificity. Expression level of MIR192, MIR196a, MIR199a, combined that of trefoil factor 3, identified patients with BE with an AUC of 0.93, 93.1% sensitivity, and 93.7% specificity. Hypomethylation was observed in the promoter region of the highly up-regulated cluster MIR192-MIR194. Overexpression of these miRNAs in normal esophageal squamous cells increased their proliferation, via GRHL3 and PTEN signaling.

CONCLUSIONS

In analyses of miRNA expression patterns of BE vs non-BE tissues, we identified a profile that can identify Cytosponge samples from patients with BE with an AUC of 0.93. Expression of MIR194 is increased in BE samples via epigenetic mechanisms that might be involved in BE pathogenesis.

Exosomes Derived from miR-214-Enriched Bone Marrow-Derived Mesenchymal Stem Cells Regulate Oxidative Damage in Cardiac Stem Cells by Targeting CaMKII

Cardiac stem cells (CSCs) have emerged as one of the most promising stem cells for cardiac protection. Recently, exosomes from bone marrow-derived mesenchymal stem cells (BMSCs) have been found to facilitate cell proliferation and survival by transporting various bioactive molecules, including microRNAs (miRs). In this study, we found that BMSC-derived exosomes (BMSC-exos) significantly decreased apoptosis rates and reactive oxygen species (ROS) production in CSCs after oxidative stress injury. Moreover, a stronger effect was induced by exosomes collected from BMSCs cultured under hypoxic conditions (Hypoxic-exos) than those collected from BMSCs cultured under normal conditions (Nor-exos). We also observed greater miR-214 enrichment in Hypoxic-exos than in Nor-exos. In addition, a miR-214 inhibitor or mimics added to modulate miR-214 levels in BMSC-exos revealed that exosomes from miR-214-depleted BMSCs partially reversed the effects of hypoxia-induced exosomes on oxidative damage in CSCs. These data further confirmed that miR-214 is the main effector molecule in BMSC-exos that protects CSCs from oxidative damage. miR-214 mimic and inhibitor transfection assays verified that CaMKII is a target gene of miR-214 in CSCs, with exosome-pretreated CSCs exhibiting increased miR-214 levels but decreased CaMKII levels. Therefore, the miR-214/CaMKII axis regulates oxidative stress-related injury in CSCs, such as apoptosis, calcium homeostasis disequilibrium, and excessive ROS accumulation. Collectively, these findings suggest that BMSCs release miR-214-containing exosomes to suppress oxidative stress injury in CSCs through CaMKII silencing.

Thyroid Hormone Receptors Regulate the Expression of microRNAs with Key Roles in Skin Homeostasis

BACKGROUND

MicroRNAs (miRNAs) play a unique role in posttranscriptional regulation of gene expression and control different aspects of skin development, homeostasis, and disease. Although it is generally accepted that thyroid hormone signaling is important in skin pathophysiology, the role of their nuclear receptors (TRs) in cutaneous miRNA expression has yet to be explored.

METHODS

RNAseq was used to compare the skin miRnome of wild-type mice and genetically modified mice lacking both TRα1 and TRβ, the main thyroid hormone binding isoforms. Changes in miRNAs with a crucial role in skin physiopathology were confirmed by stem-loop quantitative polymerase chain reaction in both total skin and isolated keratinocytes, and the levels of their target mRNAs were evaluated by real-time polymerase chain reaction.

RESULTS

The skin of TRα1/TRβ knockout mice displays altered levels of >50 miRNAs. Among the downregulated species are several miRNAs, including miR-21, miR-31, miR-34, and miR-203, with crucial roles in skin homeostasis. TRα1 appears to be the main isoform responsible for their regulation. Increased levels of gene transcripts previously shown to be bona fide targets of these miRNAs are also found in the skin and keratinocytes of TR-deficient mice. This suggests that multiple miRNAs that are downregulated in the absence of TRs cooperate to regulate gene expression in the skin.

CONCLUSIONS

The miRNAs reduced in TRα1/TRβ knockout mice are known to play crucial roles in epidermal proliferation, hair cycling, wound healing, stem-cell function, and tumor development, all processes altered in the absence of TRs. These results suggest that their regulation could contribute to the skin defects found in these mice and to the skin disorders associated with altered thyroid status in humans.

Threonine 454 phosphorylation in Grainyhead-like 3 is important for its function and regulation by the p38 MAPK pathway

The mammalian Grainyhead-like 3 (GRHL3) transcription factor is essential for epithelial development and plays a protective role against squamous cell carcinoma of the skin and of the oral cavity. A single nucleotide polymorphism (SNP) in GRHL3, rs141193530 (p.P455A), is associated with non-melanoma skin cancer in human patients. Moreover, it is known that this SNP, as well as another variant, rs41268753 (p.T454M), are associated with nonsyndromic cleft palate and that rs41268753 negatively affects GRHL3 transcriptional activity. These SNPs are located in adjacent codons of the GRHL3 gene, and the occurrence of either SNP abolishes a putative threonine-proline phosphorylation motif at T454 in the encoded protein. The role of phosphorylation in regulating mammalian GRHL function is currently unknown. In this work we show that GRHL3 is phosphorylated at several residues in a human keratinocyte cell line, among them at T454. This site is essential for the full transcriptional activity of GRHL3. The T454 residue is phosphorylated by p38 MAPK in vitro and activation of p38 signaling in cells causes an increase in GRHL3 activity. The regulation of GRHL3 function by this pathway is dependent on T454, as the substitution of T454 with methionine inhibits the activation of GRHL3. Taken together, our results show that T454 is one of the phosphorylated residues in GRHL3 in keratinocytes and this residue is important for the upregulation of GRHL3 transcriptional activity by the p38 pathway.

The microRNA landscape of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is a keratinocyte-derived skin tumor. It is the second-most-common cancer affecting the Caucasian population and is responsible for >20% of all skin-cancer-related deaths. The estimated incidence of non-melanoma skin cancer in the USA is >1000000 cases per year, of which roughly 20-30% are squamous cell carcinoma. To better understand and treat this challenging cancer, current research focuses on development of novel strategies to improve the understanding of tumor biogenesis on an individual basis. microRNAs are becoming important biomarkers in the diagnosis, prognosis and treatment of cSCC. This review describes the current knowledge on miRNA expression in cSCC and its role as a biomarker for personalized medicine.

Coordinated expression and genetic polymorphisms in Grainyhead-like genes in human non-melanoma skin cancers

BACKGROUND

The Grainyhead-like (GRHL) transcription factors have been linked to many different types of cancer. However, no previous study has attempted to investigate potential correlations in expression of different GRHL genes in this context. Furthermore, there is very little information concerning damaging mutations and/or single nucleotide polymorphisms in GRHL genes that may be linked to cancer.

METHODS

DNA and RNA were extracted from human non-melanoma skin cancers (NMSC) and adjacent normal tissues (n = 33 pairs of samples). The expression of GRHL genes was measured by quantitative real time PCR. Regulation of GRHL expression by miRNA was studied using cell transfection methods and dual-luciferase reporter system. Targeted deep sequencing of GRHL genes in tumor samples and control tissues were employed to search for mutations and single nucleotide polymorphisms. Single marker rs141193530 was genotyped with pyrosequencing in additional NMSC replication cohort (n = 176). Appropriate statistical and bioinformatic methods were used to analyze and interpret results.

RESULTS

We discovered that the expression of two genes - GRHL1 and GRHL3 - is reduced in a coordinated manner in tumor samples, in comparison to the control healthy skin samples obtained from the same individuals. It is possible that both GRHL1 and GRHL3 are regulated, at least to some extent, by different strands of the same oncogenic microRNA - miR-21, what would at least partially explain observed correlation. No de novo mutations in the GRHL genes were detected in the examined tumor samples. However, some single nucleotide polymorphisms in the GRHL genes occur at significantly altered frequencies in the examined group of NMSC patients.

CONCLUSIONS

Non-melanoma skin cancer growth is accompanied by coordinated reduced expression of epidermal differentiation genes: GRHL1 and GRHL3, which may be regulated by miR-21-3p and -5p, respectively. Some potentially damaging single nucleotide polymorphisms in GRHL genes occur with altered frequencies in NMSC patients, and they may in particular impair the expression of GRHL3 gene or functioning of encoded protein. The presence of these polymorphisms may indicate an increased risk of NMSC development in affected people.

Knockdown of GRHL3 inhibits activities and induces cell cycle arrest and apoptosis of human colorectal cancer cells

The Grainyhead-like 3 (GRHL3) is involved in epidermal barrier formation, neural tube closure and wound repair. Previous studies have suggested that GRHL3 has been linked to many different types of cancers. However, to date, its effects on human colorectal cancer (CRC) has not been clarified yet. Our microarray analysis has indicated predominant GRHL3 expression in CRC. The purpose of this study was to investigate the expression and significance of GRHL3 in CRC tumorigenesis using CRC tissues and paired paracancerous tissues, as well as using distinct CRC cell lines (HT29 and DLD1). We observed increased GRHL3 expression at both mRNA and protein levels in CRC tissues and CRC cell lines using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Moreover, silencing GRHL3 with siRNA could suppress CRC cell proliferation, viability and migration in vitro. We also found that knockdown of GRHL3 could promote cell cycle arrest at G₀/G₁ phase in HT29 cells and DLD1 cells, and induce cell apoptosis in HT29 cells. Together, our study revealed the down-regulation of GRHL3 in vitro could inhibit CRC cell activity and trigger cell cycle arrest at G₀/G₁ phase and apoptosis.

Mis-expression of grainyhead-like transcription factors in zebrafish leads to defects in enveloping layer (EVL) integrity, cellular morphogenesis and axial extension

The grainyhead-like (grhl) transcription factors play crucial roles in craniofacial development, epithelial morphogenesis, neural tube closure, and dorso-ventral patterning. By utilising the zebrafish to differentially regulate expression of family members grhl2b and grhl3, we show that both genes regulate epithelial migration, particularly convergence-extension (CE) type movements, during embryogenesis. Genetic deletion of grhl3 via CRISPR/Cas9 results in failure to complete epiboly and pre-gastrulation embryonic rupture, whereas morpholino (MO)-mediated knockdown of grhl3 signalling leads to aberrant neural tube morphogenesis at the midbrain-hindbrain boundary (MHB), a phenotype likely due to a compromised overlying enveloping layer (EVL). Further disruptions of grhl3-dependent pathways (through co-knockdown of grhl3 with target genes spec1 and arhgef19) confirm significant MHB morphogenesis and neural tube closure defects. Concomitant MO-mediated disruption of both grhl2b and grhl3 results in further extensive CE-like defects in body patterning, notochord and somite morphogenesis. Interestingly, over-expression of either grhl2b or grhl3 also leads to numerous phenotypes consistent with disrupted cellular migration during gastrulation, including embryo dorsalisation, axial duplication and impaired neural tube migration leading to cyclopia. Taken together, our study ascribes novel roles to the Grhl family in the context of embryonic development and morphogenesis.

Stage-dependent therapeutic efficacy in PI3K/mTOR-driven squamous cell carcinoma of the skin

Cutaneous squamous cell carcinoma (SCC) is a recurrent cancer that is prevalent in predisposed subjects such as immunosuppressed patients and patients being treated for other malignancies. Model systems to trial therapies at different stages of SCC development are lacking, therefore precluding efficient therapeutic interventions. Here, we have disrupted the expression of the tumor suppressor GRHL3 to induce loss of PTEN and activation of the PI3K/mTOR signaling pathway in mice and human skin, promoting aggressive SCC development. We then examined the potential for targeting PI3K/mTOR and an oncogenic driver miR-21, alone and in combination, for the prevention and treatment of SCC during the initiation, promotion/progression and establishment stages. Treatment with PI3K/mTOR inhibitors completely prevented tumor initiation, and these inhibitors significantly delayed the course of papilloma progression to malignancy. However, established SCC did not undergo any growth regression, indicating that this therapy is ineffective in established cancers. Mechanistically, the resistant SCCs displayed increased miR-21 expression in mice and humans where antagonists of miR-21 rescued expression levels of GRHL3/PTEN, but the combination of miR-21 antagonism with PI3K/mTOR inhibition resulted in acquired SCC resistance in part via c-MYC and OCT-4 upregulation. In conclusion, our data provide molecular evidence for the efficacy of targeting oncogenic drivers of SCC during the initiation and promotion stages and indicate that combination therapy may induce an aggressive phenotype when applied in the establishment stage.

miR-21 Inhibitors Modulate Biological Functions of Gastric Cancer Cells via PTEN/PI3K/mTOR Pathway

Gastric cancer is one of the most common malignancy in the world. microRNAs (miRNAs) are naturally occurring noncoding RNA that control gene expression by targeting messenger RNA (mRNA) for post-transcriptional repression or cleavage. This study focused on a specific miRNA, miR-21, which was overexpressed in gastric cancer and examined the effects of miR-21 inhibitor on biological functions of gastric cancer cells and its possible mechanism. Gastric cancer cells MKN74 were treated with miR-21 inhibitor, negative control, and blank control. Cell proliferation, colony formation, migration, and invasion were assessed. Real-time PCR and western blot were applied to examine the expression of phosphatase and tens in homolog deleted on chromosome ten (PTEN)/PI3K/mTOR pathway molecules. miR-21 inhibitor markedly suppressed proliferation, migration, invasion, and colony formation of gastric cancer cells. Anti-miR-21 treatment also reduced the expression ratio of B cell lymphoma 2 (Bcl-2)/Bax. Furthermore, miR-21 inhibition was associated with increased expression of PTEN, which in turn decreased the ratios of S235/236, S240/244, and p-AK/AKT in gastric cancer cells. Inhibiting miR-21 modulates biological functions of gastric cancer cells via PTEN/PI3K/mTOR pathway and miR-21 inhibitor may provide a novel therapeutic strategy for gastric cancer.

Towards topical microRNA-directed therapy for epidermal disorders

There remains an unmet dermatological need for innovative topical agents that achieve better longterm outcomes with fewer side effects. Modulation of the expression and activity of microRNA (miRNAs) represents an emerging translational framework for the development of such innovative therapies because changes in the expression of one miRNA can have wide-ranging effects on diverse cellular processes associated with disease. In this short review, the roles of miRNA in epidermal development, psoriasis, cutaneous squamous cell carcinoma and re-epithelisation are highlighted. Consideration is given to the delivery of oligonucleotides that mimic or inhibit miRNA function using vehicles such as cell penetrating peptides, spherical nucleic acids, deformable liposomes and liquid crystalline nanodispersions. Formulation of miRNA-directed oligonucleotides with such skin-penetrating epidermal agents will drive the development of RNA-based cutaneous therapeutics for deployment as primary or adjuvant therapies for epidermal disorders.

Inhibition of miR-23a increases the sensitivity of lung cancer stem cells to erlotinib through PTEN/PI3K/Akt pathway

Epidermal growth factor receptor-targeted tyrosine kinase inhibitors (EGFR-TKIs) have become first-line drugs used for non-small cell lung cancer (NSCLC) treatment. However, drug resistance to EGFR-TKIs will be developed inevitably due to the repeated use of these drugs. In the present study, we isolated cancer stem cells (CSCs) from the PC9 NSCLC cell line. We then observed that the PC9 CSCs showed significant resistance to erlotinib compared with the PC9 non-CSCs. Erlotinib failed to suppress the phosphorylation of PI3K and AKT in PC9 CSCs, although the EGFR was inhibited sufficiently. Mechanically, we observed aberrant upregulation of microRNA-23a (miR-23a) and downregulation of PTEN in PC9 CSCs compared to PC9 non-CSCs. Luciferase reporter assays proved that PTEN was the target of miR-23a in PC9 CSCs. Furthermore, knockdown of miR-23a enhanced the antitumor effect of erlotinib by increasing the expression of PTEN. In addition, transfection with miR-23a inhibitors promoted the erlotinib-dependent inhibition of PI3K/AKT pathway, thus, suppressing the proliferation and inducing apoptosis in PC9 CSCs. These results propose that upregulation of miR-23a is a potential mechanism associated with resistance to EGFR-TKIs in lung cancer stem cells. Inhibition of miR-23a serves as a novel therapeutic strategy to eliminate the EGFR-TKIs resistance of lung cancer stem cells.

Transcriptional mechanisms coordinating tight junction assembly during epithelial differentiation

Epithelial tissues form a selective barrier via direct cell-cell interactions to separate and establish concentration gradients between the different compartments of the body. Proper function and formation of this barrier rely on the establishment of distinct intercellular junction complexes. These complexes include tight junctions, adherens junctions, desmosomes, and gap junctions. The tight junction is by far the most diverse junctional complex in the epithelial barrier. Its composition varies greatly across different epithelial tissues to confer various barrier properties. Thus, epithelial cells rely on tightly regulated transcriptional mechanisms to ensure proper formation of the epithelial barrier and to achieve tight junction diversity. Here, we review different transcriptional mechanisms utilized during embryogenesis and disease development to promote tight junction assembly and maintenance of intercellular barrier integrity. We focus particularly on the Grainyhead-like transcription factors and ligand-activated nuclear hormone receptors, two central families of proteins in epithelialization.

BRD4 promotes p63 and GRHL3 expression downstream of FOXO in mammary epithelial cells

Bromodomain-containing protein 4 (BRD4) is a member of the bromo- and extraterminal (BET) domain-containing family of epigenetic readers which is under intensive investigation as a target for anti-tumor therapy. BRD4 plays a central role in promoting the expression of select subsets of genes including many driven by oncogenic transcription factors and signaling pathways. However, the role of BRD4 and the effects of BET inhibitors in non-transformed cells remain mostly unclear. We demonstrate that BRD4 is required for the maintenance of a basal epithelial phenotype by regulating the expression of epithelial-specific genes including TP63 and Grainy Head-like transcription factor-3 (GRHL3) in non-transformed basal-like mammary epithelial cells. Moreover, BRD4 occupancy correlates with enhancer activity and enhancer RNA (eRNA) transcription. Motif analyses of cell context-specific BRD4-enriched regions predicted the involvement of FOXO transcription factors. Consistently, activation of FOXO1 function via inhibition of EGFR-AKT signaling promoted the expression of TP63 and GRHL3. Moreover, activation of Src kinase signaling and FOXO1 inhibition decreased the expression of FOXO/BRD4 target genes. Together, our findings support a function for BRD4 in promoting basal mammary cell epithelial differentiation, at least in part, by regulating FOXO factor function on enhancers to activate TP63 and GRHL3 expression.

Roles of Grainyhead-like transcription factors in cancer

The mammalian homologs of the D. melanogaster Grainyhead gene, Grainyhead-like 1-3 (GRHL1, GRHL2 and GRHL3), are transcription factors implicated in wound healing, tubulogenesis and cancer. Their induced target genes encode diverse epithelial cell adhesion molecules, while mesenchymal genes involved in cell migration and invasion are repressed. Moreover, GRHL2 suppresses the oncogenic epithelial-mesencyhmal transition, thereby acting as a tumor suppressor. Mechanisms, some involving established cancer-related signaling/transcription factor pathways (for example, Wnt, TGF-β, mir200, ZEB1, OVOL2, p63 and p300) and translational implications of the Grainyhead proteins in cancer are discussed in this review article.

Grainyhead-like Transcription Factors in Craniofacial Development

Craniofacial development in vertebrates involves the coordinated growth, migration, and fusion of several facial prominences during embryogenesis, processes governed by strict genetic and molecular controls. A failure in any of the precise spatiotemporal sequences of events leading to prominence fusion often leads to anomalous facial, skull, and jaw formation-conditions termed craniofacial defects (CFDs). Affecting approximately 0.1% to 0.3% of live births, CFDs are a highly heterogeneous class of developmental anomalies, which are often underpinned by genetic mutations. Therefore, identifying novel disease-causing mutations in genes that regulate craniofacial development is a critical prerequisite to develop new preventive or therapeutic measures. The Grainyhead-like ( GRHL) transcription factors are one such gene family, performing evolutionarily conserved roles in craniofacial patterning. The antecedent member of this family, Drosophila grainyhead ( grh), is required for head skeleton development in fruit flies, loss or mutation of Grhl family members in mouse and zebrafish models leads to defects of both maxilla and mandible, and recently, mutations in human GRHL3 have been shown to cause or contribute to both syndromic (Van Der Woude syndrome) and nonsyndromic palatal clefts. In this review, we summarize the current knowledge regarding the craniofacial-specific function of the Grainyhead-like family in multiple model species, identify some of the major target genes regulated by the Grhl transcription factors in craniofacial patterning, and, by examining animal models, draw inferences as to how these data will inform the likely roles of GRHL factors in human CFDs comprising palatal clefting. By understanding the molecular networks regulated by Grhl2 and Grhl3 target genes in other systems, we can propose likely pathways that mediate the effects of these transcription factors in human palatogenesis.

Phosphoinositide 3-Kinase-Dependent Signalling Pathways in Cutaneous Squamous Cell Carcinomas

Cutaneous squamous cell carcinoma (cSCC) derives from keratinocytes in the epidermis and accounts for 15–20% of all cutaneous malignancies. Although it is usually curable by surgery, 5% of these tumours metastasise leading to poor prognosis mostly because of a lack of therapies and validated biomarkers. As the incidence rate is rising worldwide it has become increasingly important to better understand the mechanisms involved in cSCC development and progression in order to develop therapeutic strategies. Here we discuss some of the evidence indicating that activation of phosphoinositide 3-kinases (PI3Ks)-dependent signalling pathways (in particular the PI3Ks targets Akt and mTOR) has a key role in cSCC. We further discuss available data suggesting that inhibition of these pathways can be beneficial to counteract the disease. With the growing number of different inhibitors currently available, it would be important to further investigate the specific contribution of distinct components of the PI3Ks/Akt/mTOR pathways in order to identify the most promising molecular targets and the best strategy to inhibit cSCC.

Long-Lived Epidermal Cancer-Initiating Cells

Non-melanomatous skin cancers (NMSCs), which include basal and squamous cell carcinoma (BCC and SCC respectively), represent a significant burden on the population, as well as an economic load to the health care system; yet treatments of these preventable cancers remain ineffective. Studies estimate that there has been a 2-fold increase in the incidence of NMSCs between the 1960s and 1980s. The increase in cases of NMSCs, as well as the lack of effective treatments, makes the need for novel therapeutic approaches all the more necessary. To rationally develop more targeted treatments for NMSCs, a better understanding of the cell of origin, in addition to the underlying pathophysiological mechanisms that govern the development of these cancers, is urgently required. Research over the past few years has provided data supporting both a "bottom up" and "top down" mechanism of tumourigenesis. The "bottom up" concept involves a cancer stem cell originating in the basal compartment of the skin, which ordinarily houses the progenitor cells that contribute towards wound healing and normal cell turnover of overlying epidermal skin layers. The "top down" concept involves a more differentiated cell undergoing genetic modifications leading to dedifferentiation, giving rise to cancer initiating cells (CICs). This review explores both concepts, to paint a picture of the skin SCC cell of origin, the underlying biology, and also how this knowledge might be exploited to develop novel therapies.

Alternative splicing and start sites: Lessons from the Grainyhead-like family

The two main mechanisms that expand the proteomic output of eukaryotic genes are alternative splicing and alternative translation initiation signals. Despite being essential to generate isoforms of gene products that create functional diversity during development, the impact of these mechanisms on fine-tuning regulatory gene networks is still underappreciated. In this review, we use the Grainyhead-like (Grhl) family as a case study to illustrate the importance of isoforms when investigating transcription factor family function during development and disease, and highlight the potential for differential modulation of downstream target genes. We provide insights into the importance of considering alternative gene products when designing, undertaking, and analysing primary research, and the effect that isoforms may have on development. This review also covers known mutations in Grhl family members, and postulates how genetic changes may dictate transcriptional specificity between the Grhl family members. It also contrasts and compares the available literature on the function and importance of the Grhl isoforms, and highlights current gaps in our understanding of their regulatory gene networks in development and disease.

AdipoR1-mediated miR-3908 inhibits glioblastoma tumorigenicity through downregulation of STAT2 associated with the AMPK/SIRT1 pathway

A prospective method of treatment for cancer is to inhibit oncogene signaling pathways with microRNA (miRNA or miR). In the present study, whether the expression of STAT2, AdipoR1/AMPK/SIRT1 pathway of glioma is regulated by miR-3908 was explored. To confirm whether the predicted miR-3908 is matched with STAT2 and AdipoR1, 3'UTR luciferase activity of STAT2 and AdipoR1 was assessed. In the presence of the mimics or inhibitors of miR-3908, cell function of glioma cells, such as proliferation, growth, migration, invasion and apoptosis were analyzed. The expression of AdipoR1 and its downstream AMPK/SIRT1 pathway proteins or STAT2 were examined. Luciferase reporter analysis showed that miR-3908 directly target STAT2 and AdipoR1. miR-3908 suppressed expression of STAT2 or AdipoR1 and downregulated AdipoR1 pathway genes, including AMPK, p-AMPK and SIRT1. miR-3908 inhibited tumorigenicity, migration, growth and invasion in glioma cell lines U251 and U87 as well as increased apoptosis of these cells. The pathways related to tumorigenicity and tumor progression, STAT2 and AdipoR1/AMPK/SIRT1 could be restrained by miR-3908. In conclusion, restoration of miR-3908 expression induced suppression of cancer progression and glioblastoma tumorigenicity. The present study discovered novel tumorigenesis associated with miR-3908, which may represent a new target in treatment for glioblastoma.

Biomarker significance of plasma and tumor miR-21, miR-221, and miR-106a in osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and young adults. Despite the use of surgery and multi-agent chemotherapy, osteosarcoma patients who have a poor response to chemotherapy or develop relapses have a dismal outcome. Identification of biomarkers for active disease may help to monitor tumor burden, detect early relapses, and predict prognosis in these patients. In this study, we examined whether circulating miRNAs can be used as biomarkers in osteosarcoma patients. We performed genome-wide miRNA profiling on a discovery cohort of osteosarcoma and control plasma samples. A total of 56 miRNAs were upregulated and 164 miRNAs were downregulated in osteosarcoma samples when compared to control plasma samples. miR-21, miR-221 and miR-106a were selected for further validation based on their known biological importance. We showed that all three circulating miRNAs were expressed significantly higher in osteosarcoma samples than normal samples in an independent cohort obtained from the Children’s Oncology Group. Furthermore, we demonstrated that miR-21 was expressed significantly higher in osteosarcoma tumors compared with normal bone controls. More importantly, lower expressions of miR-21 and miR-221, but not miR-106a, significantly correlated with a poor outcome. In conclusion, our results indicate that miR-21, miR-221 and miR-106a were elevated in the circulation of osteosarcoma patients, whereas tumor expressions of miR-21 and miR-221 are prognostically significant. Further investigation of these miRNAs may lead to a better prognostic method and potential miRNA therapeutics for osteosarcoma.

Phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog as therapeutic targets in breast cancer

Breast cancer is the most commonly diagnosed cancer among women in Turkey and worldwide. It is considered a heterogeneous disease and has different subtypes. Moreover, breast cancer has different molecular characteristics, behaviors, and responses to treatment. Advances in the understanding of the molecular mechanisms implicated in breast cancer progression have led to the identification of many potential therapeutic gene targets, such as Breast Cancer 1/2, phosphatidylinositol 3-kinase catalytic subunit alpha, and tumor protein 53. The aim of this review is to summarize the roles of phosphatidylinositol 3-kinase regulatory subunit 1 (alpha) (alias p85α) and phosphatase and tensin homolog in breast cancer progression and the molecular mechanisms involved. Phosphatase and tensin homolog is a tumor suppressor gene and protein. Phosphatase and tensin homolog antagonizes the phosphatidylinositol 3-kinase/AKT signaling pathway that plays a key role in cell growth, differentiation, and survival. Loss of phosphatase and tensin homolog expression, detected in about 20%-30% of cases, is known to be one of the most common tumor changes leading to phosphatidylinositol 3-kinase pathway activation in breast cancer. Instead, the regulatory subunit p85α is a significant component of the phosphatidylinositol 3-kinase pathway, and it has been proposed that a reduction in p85α protein would lead to decreased negative regulation of phosphatidylinositol 3-kinase and hyperactivation of the phosphatidylinositol 3-kinase pathway. Phosphatidylinositol 3-kinase regulatory subunit 1 protein has also been reported to be a positive regulator of phosphatase and tensin homolog via the stabilization of this protein. A functional genetic alteration of phosphatidylinositol 3-kinase regulatory subunit 1 that results in reduced p85α protein expression and increased insulin receptor substrate 1 binding would lead to enhanced phosphatidylinositol 3-kinase signaling and hence cancer development. Phosphatidylinositol 3-kinase regulatory subunit 1 underexpression was observed in 61.8% of breast cancer samples. Therefore, expression/alternations of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog genes have crucial roles for breast cancer progression. This review will summarize the biological roles of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog in breast cancer, with an emphasis on recent findings and the potential of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog as a therapeutic target for breast cancer therapy.

Impact of microRNA dynamics on cancer hallmarks: An oral cancer scenario

MicroRNAs are endogenous small noncoding RNAs that negatively regulate gene expression at posttranscriptional level. The discovery of microRNAs has identified a new layer of gene regulation mechanisms, which play a pivotal role in development as well as in various cellular processes, such as proliferation, differentiation, cell growth, and cell death. Deregulated microRNA expression favors acquisition of cancer hallmark traits as well as transforms the tumor microenvironment, leading to tumor development and progression. Many recent studies have revealed altered expression of microRNAs in oral carcinoma with several microRNAs shown to have key biological role in tumorigenesis functioning either as tumor suppressors or as tumor promoters. MicroRNA expression levels correlate with clinicopathological variables and have a diagnostic and prognostic value in oral carcinoma. For these reasons, microRNA has been a hot topic in oral cancer research for the last few years. In this review, we attempt to summarize the present understanding of microRNA deregulation in oral carcinoma, their role in acquiring cancer hallmarks, and their potential diagnostic and prognostic value for oral cancer management.

Expression and significance of GRHL2 in esophageal cancer

Esophageal cancer (EC) is one of the most common causes of cancer-related mortality in the world. Although much effort has been made to improve the 5-year survival rate of patients with EC, it still remains low due to diagnosis at an advanced stage, aggressive local invasion, early metastasis, and resistance to chemotherapy. Although grainyhead-like 2 (GRHL2) has attracted interest since it has been recently identified as a novel suppressor of the epithelial–mesenchymal transition, clinical values of GRHL2 and its relationship with the metastasis-related factors, such as hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF), remain unclear. In order to investigate the expression of GRHL2, HIF-1α, and VEGF, and their correlation with angiogenesis in EC, 63 patients with EC were examined. The expression of GRHL2, HIF-1α, and VEGF in tumor tissues was higher than that in adjacent tissues and was associated with tumor differentiation. GRHL2 expression was significantly correlated with lymph node metastasis and invasion depth, whereas VEGF expression was associated with tumor (TNM) stage. A significant correlation was found between the expression of GRHL2 and HIF-1α. The patients expressing low GRHL2 and high HIF-1α showed significant reduction in both overall survival rate and disease-free survival rate. The results demonstrated that abnormal expression of GRHL2 is common in EC, and low expression of GRHL2 accompanied by a high expression of HIF-1α indicates poor prognosis.

Grainyhead-like 3 (Grhl3) deficiency in brain leads to altered locomotor activity and decreased anxiety-like behaviors in aged mice

The highly conserved Grainyhead-like (Grhl) family of transcription factors, comprising three members in vertebrates (Grhl1-3), play critical regulatory roles during embryonic development, cellular proliferation, and apoptosis. Although loss of Grhl function leads to multiple neural abnormalities in numerous animal models, a comprehensive analysis of Grhl expression and function in the mammalian brain has not been reported. Here they show that only Grhl3 expression is detectable in the embryonic mouse brain; particularly within the habenula, an organ known to modulate repressive behaviors. Using both Grhl3-knockout mice (Grhl3^-/- ), and brain-specific conditional deletion of Grhl3 in adult mice (Nestin-Cre/Grhl3^flox/flox ), they performed histological expression analyses and behavioral tests to assess long-term effects of Grhl3 loss on motor co-ordination, spatial memory, anxiety, and stress. They found that complete deletion of Grhl3 did not lead to noticeable structural or cell-intrinsic defects in the embryonic brain; however, aged Grhl3 conditional knockout (cKO) mice showed enlarged lateral ventricles and displayed marked changes in motor function and behaviors suggestive of decreased fear and anxiety. They conclude that loss of Grhl3 in the brain leads to significant alterations in locomotor activity and decreased self-inhibition, and as such, these mice may serve as a novel model of human conditions of impulsive behavior or hyperactivity. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 775-788, 2017.

Wnt/Planar Cell Polarity Signaling: New Opportunities for Cancer Treatment

Cancer cells are addicted to a large spectrum of extracellular cues implicated in initiation, stem cell renewal, tumor growth, dissemination in the body, and resistance to treatment. Wingless/Int-1 (Wnt) ligands and their associated signaling cascades contribute to most of these processes, paving the way for opportunities in therapeutic development. The developmental Wnt/planar cell polarity (PCP) pathway is the most recently described branch of Wnt signaling strongly implicated in cancer development at early and late stages. We describe here some of the latest knowledge accumulated on this pathway and the pending questions, present the most convincing findings about its role in cancer, and review the most promising strategies currently designed to target its components.

Stable Binding of the Conserved Transcription Factor Grainy Head to its Target Genes Throughout Drosophila melanogaster Development

It has been suggested that transcription factor binding is temporally dynamic, and that changes in binding determine transcriptional output. Nonetheless, this model is based on relatively few examples in which transcription factor binding has been assayed at multiple developmental stages. The essential transcription factor Grainy head (Grh) is conserved from fungi to humans, and controls epithelial development and barrier formation in numerous tissues. Drosophila melanogaster, which possess a single grainy head (grh) gene, provide an excellent system to study this conserved factor. To determine whether temporally distinct binding events allow Grh to control cell fate specification in different tissue types, we used a combination of ChIP-seq and RNA-seq to elucidate the gene regulatory network controlled by Grh during four stages of embryonic development (spanning stages 5-17) and in larval tissue. Contrary to expectations, we discovered that Grh remains bound to at least 1146 genomic loci over days of development. In contrast to this stable DNA occupancy, the subset of genes whose expression is regulated by Grh varies. Grh transitions from functioning primarily as a transcriptional repressor early in development to functioning predominantly as an activator later. Our data reveal that Grh binds to target genes well before the Grh-dependent transcriptional program commences, suggesting it sets the stage for subsequent recruitment of additional factors that execute stage-specific Grh functions.

Targeting of Ras-mediated FGF signaling suppresses Pten-deficient skin tumor

Deficiency in PTEN (phosphatase and tensin homolog deleted on chromosome 10) is the underlying cause of PTEN hamartoma tumor syndrome and a wide variety of human cancers. In skin epidermis, we have previously identified an autocrine FGF signaling induced by loss of Pten in keratinocytes. In this study, we demonstrate that skin hyperplasia requires FGF receptor adaptor protein Frs2α and tyrosine phosphatase Shp2, two upstream regulators of Ras signaling. Although the PI3-kinase regulatory subunits p85α and p85β are dispensable, the PI3-kinase catalytic subunit p110α requires interaction with Ras to promote hyperplasia in Pten-deficient skin, thus demonstrating an important cross-talk between Ras and PI3K pathways. Furthermore, genetic and pharmacological inhibition of Ras-MAPK pathway impeded epidermal hyperplasia in Pten animals. These results reveal a positive feedback loop connecting Pten and Ras pathways and suggest that FGF-activated Ras-MAPK pathway is an effective therapeutic target for preventing skin tumor induced by aberrant Pten signaling.

Mice lacking the conserved transcription factor Grainyhead-like 3 (Grhl3) display increased apposition of the frontal and parietal bones during embryonic development

BACKGROUND

Increased apposition of the frontal and parietal bones of the skull during embryogenesis may be a risk factor for the subsequent development of premature skull fusion, or craniosynostosis. Human craniosynostosis is a prevalent, and often serious embryological and neonatal pathology. Other than known mutations in a small number of contributing genes, the aetiology of craniosynostosis is largely unknown. Therefore, the identification of novel genes which contribute to normal skull patterning, morphology and premature suture apposition is imperative, in order to fully understand the genetic regulation of cranial development.

RESULTS

Using advanced imaging techniques and quantitative measurement, we show that genetic deletion of the highly-conserved transcription factor Grainyhead-like 3 (Grhl3) in mice (Grhl3 ^-/- ) leads to decreased skull size, aberrant skull morphology and premature apposition of the coronal sutures during embryogenesis. Furthermore, Grhl3 ^-/- mice also present with premature collagen deposition and osteoblast alignment at the sutures, and the physical interaction between the developing skull, and outermost covering of the brain (the dura mater), as well as the overlying dermis and subcutaneous tissue, appears compromised in embryos lacking Grhl3. Although Grhl3 ^-/- mice die at birth, we investigated skull morphology and size in adult animals lacking one Grhl3 allele (heterozygous; Grhl3 ^+/- ), which are viable and fertile. We found that these adult mice also present with a smaller cranial cavity, suggestive of post-natal haploinsufficiency in the context of cranial development.

CONCLUSIONS

Our findings show that our Grhl3 mice present with increased apposition of the frontal and parietal bones, suggesting that Grhl3 may be involved in the developmental pathogenesis of craniosynostosis.

In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

BACKGROUND Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. MATERIAL AND METHODS PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. RESULTS PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. CONCLUSIONS PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis.

Identification of a novel PPARβ/δ/miR-21-3p axis in UV-induced skin inflammation

Although excessive exposure to UV is widely recognized as a major factor leading to skin perturbations and cancer, the complex mechanisms underlying inflammatory skin disorders resulting from UV exposure remain incompletely characterized. The nuclear hormone receptor PPARβ/δ is known to control mouse cutaneous repair and UV-induced skin cancer development. Here, we describe a novel PPARβ/δ-dependent molecular cascade involving TGFβ1 and miR-21-3p, which is activated in the epidermis in response to UV exposure. We establish that the passenger miRNA miR-21-3p, that we identify as a novel UV-induced miRNA in the epidermis, plays a pro-inflammatory function in keratinocytes and that its high level of expression in human skin is associated with psoriasis and squamous cell carcinomas. Finally, we provide evidence that inhibition of miR-21-3p reduces UV-induced cutaneous inflammation in ex vivo human skin biopsies, thereby underlining the clinical relevance of miRNA-based topical therapies for cutaneous disorders.

Phosphorylated mTOR is associated to androgen receptor expression in early triple-negative breast cancer

The significance of phosphorylated mTOR (p-mTOR) expression is unknown in triple-negative breast carcinoma (TNBC). The aims of the present study were to assess the expression of p-mTOR in early TNBC and to evaluate possible correlations between androgen receptor (AR) expression, clinicopathological parameters and disease outcome. Between January 2009 and December 2013, all consecutive patients who were diagnosed and completed the treatment of invasive TNBC at our institution were eligible for this analysis. Patients with stage IV disease were excluded. The evaluation of p-mTOR immunohistochemical staining was semi-quantitatively considering both the percentage of positive tumor cells (range, 0-100%) and staining intensity (range, 0-3+). Ninety-eight TNBC patients were included. Approximately 33% of cases were p-mTOR positive and there was no association between positive immunostaining for p-mTOR and DFS (p=0.74) and OS (p=0.81). p-mTOR positivity was associated with small tumor size (p=0.03) and AR expression (p=0.04). High expression of p-mTOR may drive tumor proliferation in almost one third of TNBC. The biological association between mTOR activation and AR pathway suggests that there may exist a subgroup of TNBC in which the combination of both AR antagonism and mTOR inhibition should have a synergistic effect on cell growth and tumor progression.