The microRNA feedback regulation of p63 in cancer progression

Epigenetic Alterations from Barrett's Esophagus to Esophageal Adenocarcinoma

Barrett's esophagus (BE) is a disease entity that is a sequela of chronic gastroesophageal reflux disease that may result in esophageal adenocarcinoma (EAC) due to columnar epithelial dysplasia. The histological degree of dysplasia is the sole biomarker frequently utilized by clinicians. However, the cost of endoscopy and the fact that the degree of dysplasia does not progress in many patients with BE diminish the effectiveness of histological grading as a perfect biomarker. Multiple or more quantitative biomarkers are required by clinicians since early diagnosis is crucial in esophageal adenocancers, which have a high mortality rate. The presence of epigenetic factors in the early stages of this neoplastic transformation holds promise as a predictive biomarker. In this review, current studies on DNA methylations, histone modifications, and noncoding RNAs (miRNAs) that have been discovered during the progression from BE dysplasia to EAC were collated.

The p53 Family Members p63 and p73 Roles in the Metastatic Dissemination: Interactions with microRNAs and TGFβ Pathway

TP53 (TP53), p73 (TP73), and p63 (TP63) are members of the p53 transcription factor family, which has many activities spanning from embryonic development through to tumor suppression. The utilization of two promoters and alternative mRNA splicing has been shown to yield numerous isoforms in p53, p63, and p73. TAp73 is thought to mediate apoptosis as a result of nuclear accumulation following chemotherapy-induced DNA damage, according to a number of studies. Overexpression of the nuclear ΔNp63 and ΔNp73 isoforms, on the other hand, suppresses TAp73's pro-apoptotic activity in human malignancies, potentially leading to metastatic spread or inhibition. Another well-known pathway that has been associated to metastatic spread is the TGF pathway. TGFs are a family of structurally related polypeptide growth factors that regulate a variety of cellular functions including cell proliferation, lineage determination, differentiation, motility, adhesion, and cell death, making them significant players in development, homeostasis, and wound repair. Various studies have already identified several interactions between the p53 protein family and the TGFb pathway in the context of tumor growth and metastatic spread, beginning to shed light on this enigmatic intricacy.

microRNA-205 in prostate cancer: Overview to clinical translation

Prostate cancer (PrCa) is the most common type of cancer among men in the United States. The metastatic and advanced PrCa develops drug resistance to current regimens which accounts for the poor management. microRNAs (miRNAs) have been well-documented for their diagnostic, prognostic, and therapeutic roles in various human cancers. Recent literature confirmed that microRNA-205 (miR-205) has been established as one of the tumor suppressors in PrCa. miR-205 regulates number of cellular functions, such as proliferation, invasion, migration/metastasis, and apoptosis. It is also evident that miR-205 can serve as a key biomarker in diagnostic, prognostic, and therapy of PrCa. Therefore, in this review, we will provide an overview of tumor suppressive role of miR-205 in PrCa. This work also outlines miR-205's specific role in targeted mechanisms for chemosensitization and radiosensitization in PrCa. A facile approach of delivery paths for successful clinical translation is documented. Together, all these studies provide a novel insight of miR-205 as an adjuvant agent for reducing the widening gaps in clinical outcome of PrCa patients.

EZH2 regulates a SETDB1/ΔNp63α axis via RUNX3 to drive a cancer stem cell phenotype in squamous cell carcinoma

Enhancer of zeste homolog 2 (EZH2) and SET domain bifurcated 1 (SETDB1, also known as ESET) are oncogenic methyltransferases implicated in a number of human cancers. These enzymes typically function as epigenetic repressors of target genes by methylating histone H3 K27 and H3-K9 residues, respectively. Here, we show that EZH2 and SETDB1 are essential to proliferation in 3 SCC cell lines, HSC-5, FaDu, and Cal33. Additionally, we find both of these proteins highly expressed in an aggressive stem-like SCC sub-population. Depletion of either EZH2 or SETDB1 disrupts these stem-like cells and their associated phenotypes of spheroid formation, invasion, and tumor growth. We show that SETDB1 regulates this SCC stem cell phenotype through cooperation with ΔNp63α, an oncogenic isoform of the p53-related transcription factor p63. Furthermore, EZH2 is upstream of both SETDB1 and ΔNp63α, activating these targets via repression of the tumor suppressor RUNX3. We show that targeting this pathway with inhibitors of EZH2 results in activation of RUNX3 and repression of both SETDB1 and ΔNp63α, antagonizing the SCC cancer stem cell phenotype. This work highlights a novel pathway that drives an aggressive cancer stem cell phenotype and demonstrates a means of pharmacological intervention.

USP28: Oncogene or Tumor Suppressor? A Unifying Paradigm for Squamous Cell Carcinoma

Squamous cell carcinomas are therapeutically challenging tumor entities. Low response rates to radiotherapy and chemotherapy are commonly observed in squamous patients and, accordingly, the mortality rate is relatively high compared to other tumor entities. Recently, targeting USP28 has been emerged as a potential alternative to improve the therapeutic response and clinical outcomes of squamous patients. USP28 is a catalytically active deubiquitinase that governs a plethora of biological processes, including cellular proliferation, DNA damage repair, apoptosis and oncogenesis. In squamous cell carcinoma, USP28 is strongly expressed and stabilizes the essential squamous transcription factor ΔNp63, together with important oncogenic factors, such as NOTCH1, c-MYC and c-JUN. It is presumed that USP28 is an oncoprotein; however, recent data suggest that the deubiquitinase also has an antineoplastic effect regulating important tumor suppressor proteins, such as p53 and CHK2. In this review, we discuss: (1) The emerging role of USP28 in cancer. (2) The complexity and mutational landscape of squamous tumors. (3) The genetic alterations and cellular pathways that determine the function of USP28 in squamous cancer. (4) The development and current state of novel USP28 inhibitors.

The foggy world(s) of p63 isoform regulation in normal cells and cancer

The p53 family member p63 exists as two major protein variants (TAp63 and ΔNp63) with distinct expression patterns and functional properties. Whilst downstream target genes of p63 have been studied intensively, how p63 variants are themselves controlled has been relatively neglected. Here, we review advances in understanding ΔNp63 and TAp63 regulation, highlighting their distinct pathways. TAp63 has roles in senescence and metabolism, and in germ cell genome maintenance, where it is activated post-transcriptionally by phosphorylation cascades after DNA damage. The function and regulation of TAp63 in mesenchymal and haematopoietic cells is less clear but may involve epigenetic control through DNA methylation. ΔNp63 functions to maintain stem/progenitor cells in various epithelia and is overexpressed in squamous and certain other cancers. ΔNp63 is transcriptionally regulated through multiple enhancers in concert with chromatin modifying proteins. Many signalling pathways including growth factors, morphogens, inflammation, and the extracellular matrix influence ΔNp63 levels, with inconsistent results reported. There is also evidence for reciprocal regulation, including ΔNp63 activating its own transcription. ΔNp63 is downregulated during cell differentiation through transcriptional regulation, while post-transcriptional events cause proteasomal degradation. Throughout the review, we identify knowledge gaps and highlight discordances, providing potential explanations including cell-context and cell-matrix interactions. Identifying individual p63 variants has roles in differential diagnosis and prognosis, and understanding their regulation suggests clinically approved agents for targeting p63 that may be useful combination therapies for selected cancer patients. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Unveiling the ups and downs of miR-205 in physiology and cancer: transcriptional and post-transcriptional mechanisms

miR-205 plays important roles in the physiology of epithelia by regulating a variety of pathways that govern differentiation and morphogenesis. Its aberrant expression is frequently found in human cancers, where it was reported to act either as tumor-suppressor or oncogene depending on the specific tumor context and target genes. miR-205 expression and function in different cell types or processes are the result of the complex balance among transcription, processing and stability of the microRNA. In this review, we summarize the principal mechanisms that regulate miR-205 expression at the transcriptional and post-transcriptional level, with particular focus on the transcriptional relationship with its host gene. Elucidating the mechanisms and factors regulating miR-205 expression in different biological contexts represents a fundamental step for a better understanding of the contribution of such pivotal microRNA to epithelial cell function in physiology and disease, and for the development of modulation strategies for future application in cancer therapy.

Methamphetamine Enhances HIV-1 Replication in CD4+ T-Cells via a Novel IL-1β Auto-Regulatory Loop

Methamphetamine (Meth) abuse is a worldwide public health problem and contributes to HIV-1 pathobiology and poor adherence to anti-retroviral therapies. Specifically, Meth is posited to alter molecular mechanisms to provide a more conducive environment for HIV-1 replication and spread. Enhanced expression of inflammatory cytokines, such as Interleukin-1β (IL-1β), has been shown to be important for HIV-1 pathobiology. In addition, microRNAs (miRNAs) play integral roles in fine-tuning the innate immune response. Notably, the effects of Meth abuse on miRNA expression are largely unknown. We studied the effects of Meth on IL-1β and miR-146a, a well-characterized member of the innate immune signaling network. We found that Meth induces miR-146a and triggers an IL-1β auto-regulatory loop to modulate innate immune signaling in CD4⁺ T-cells. We also found that Meth enhances HIV-1 replication via IL-1 signaling. Our results indicate that Meth activates an IL-1β feedback loop to alter innate immune pathways and favor HIV-1 replication. These observations offer a framework for designing targeted therapies in HIV-infected, Meth using hosts.

microRNA cluster MC-let-7a-1~let-7d promotes autophagy and apoptosis of glioma cells by down-regulating STAT3

Background

Accumulating evidence has highlighted the correlation between microRNAs (miRNAs) and the progression of glioma. However, the role of miR cluster MC‐let‐7a‐1 ~ let‐7d in glioma remains elusive. Thus, the current study aimed to investigate the effect of miR cluster MC‐let‐7a‐1 ~ let‐7d on glioma progression.

Methods and Results

Microarray data analysis provided data indicating the involvement of miR cluster MC‐let‐7a‐1 ~ let‐7d in glioma via STAT3. The expression of let‐7a‐1, let‐7d, let‐7f‐1, and miR cluster MC‐let‐7a‐1 ~ let‐7d was diminished in the glioma tissues and the cell lines. Additionally, our results revealed that STAT3 was a target gene of let‐7d, let‐7a‐1, and let‐7f‐1, which was further verified by the dual‐luciferase reporter gene assay. Moreover, STAT3 expression was negatively mediated by let‐7a‐1, let‐7d, and let‐7f‐1. Up‐regulated miR cluster MC‐let‐7a‐1 ~ let‐7d or silenced STAT3 suppressed cell proliferation but accelerated cell apoptosis and autophagy. Moreover, restrained tumor growth was identified in the nude mice treated with miR cluster MC‐let‐7a‐1 ~ let‐7d mimics or STAT3 siRNA.

Conclusion

Taken together, the miR cluster MC‐let‐7a‐1 ~ let‐7d promotes glioma cell autophagy and apoptosis by repressing STAT3. The current study highlights the potential of the miR cluster MC‐let‐7a‐1 ~ let‐7d as biomarkers and promising treatment strategies for glioma.

Molecular Mechanisms of p63-Mediated Squamous Cancer Pathogenesis

The p63 gene is a member of the p53/p63/p73 family of transcription factors and plays a critical role in development and homeostasis of squamous epithelium. p63 is transcribed as multiple isoforms; ΔNp63α, the predominant p63 isoform in stratified squamous epithelium, is localized to the basal cells and is overexpressed in squamous cell cancers of multiple organ sites, including skin, head and neck, and lung. Further, p63 is considered a stem cell marker, and within the epidermis, ΔNp63α directs lineage commitment. ΔNp63α has been implicated in numerous processes of skin biology that impact normal epidermal homeostasis and can contribute to squamous cancer pathogenesis by supporting proliferation and survival with roles in blocking terminal differentiation, apoptosis, and senescence, and influencing adhesion and migration. ΔNp63α overexpression may also influence the tissue microenvironment through remodeling of the extracellular matrix and vasculature, as well as by enhancing cytokine and chemokine secretion to recruit pro-inflammatory infiltrate. This review focuses on the role of ΔNp63α in normal epidermal biology and how dysregulation can contribute to cutaneous squamous cancer development, drawing from knowledge also gained by squamous cancers from other organ sites that share p63 overexpression as a defining feature.

ΔNp63 in squamous cell carcinoma: defining the oncogenic routes affecting epigenetic landscape and tumour microenvironment

Squamous cell carcinoma (SCC) is a treatment‐refractory tumour which arises from the epithelium of diverse anatomical sites such as oesophagus, head and neck, lung and skin. Accumulating evidence has revealed a number of genomic, clinical and molecular features commonly observed in SCC of distinct origins. Some of these genetic events culminate in fostering the activity of ΔNp63, a potent oncogene which exerts its pro‐tumourigenic effects by regulating specific transcriptional programmes to sustain malignant cell proliferation and survival. In this review, we will describe the genetic and epigenetic determinants underlying ΔNp63 oncogenic activities in SCC, and discuss some relevant transcriptional effectors of ΔNp63, emphasizing their impact in modulating the crosstalk between tumour cells and tumour microenvironment (TME).

TP63 Transcripts Play Opposite Roles in Chicken Skeletal Muscle Differentiation

Tumor protein 63 (TP63) comprises multiple isoforms and plays an important role during embryonic development. It has been shown that TP63 knockdown inhibits myogenic differentiation, but which isoform is involved in the underlying myogenic regulation remains uncertain. Here, we found that two transcripts of TP63, namely, TAp63α and ΔNp63α, are expressed in chicken skeletal muscle. These two transcripts have distinct expression patterns and opposite functions in skeletal muscle development. TAp63 has higher expression in skeletal muscle than in other tissues, and its expression is gradually upregulated during chicken primary myoblast differentiation. ΔNp63 can be expressed in multiple tissues and exhibits stable expression during myoblast differentiation. TAp63α overexpression inhibits myoblast proliferation, induces cell cycle arrest, and enhances myoblast differentiation. However, although ΔNp63α has no significant effect on cell proliferation, the overexpression of ΔNp63α inhibits myoblast differentiation. Using isoform-specific overexpression assays following RNA-sequencing, we identified potential downstream genes of TAp63α and ΔNp63α in myoblast. Bioinformatics analyses and experimental verification results showed that the differentially expressed genes (DEGs) between the TAp63α and control groups were enriched in the cell cycle pathway, whereas the DEGs between the ΔNp63α and control groups were enriched in muscle system process, muscle contraction, and myopathy. These findings provide new insights into the function and expression of TP63 during skeletal muscle development, and indicate that one gene may play two opposite roles during a single cellular process.

Role of p53 circuitry in tumorigenesis: A brief review

Maintenance of genome integrity under the stressed condition is paramount for normal functioning of cells in the multicellular organisms. Cells are programmed to protect their genome through specialized adaptive mechanisms which will help decide their fate under stressed conditions. These mechanisms are the outcome of activation of the intricate circuitries that are regulated by the p53 master protein. In this paper, we provided a comprehensive review on p53, p53 homologues and their isoforms, including a description about the ubiquitin-proteasome system emphasizing its role in p53 regulation. p53 induced E3(Ub)-ligases are an integral part of the ubiquitin-proteasome system. This review outlines the roles of important E3(Ub)-ligases and their splice variants in maintaining cellular p53 protein homeostasis. It also covers up-to-date and relevant information on small molecule Mdm2 inhibitors originated from different organizations. The review ends with a discussion on future prospects and investigation directives for the development of next-generation modulators as p53 therapeutics.

Identification of novel ΔNp63α-regulated miRNAs using an optimized small RNA-Seq analysis pipeline

Advances in high-throughput sequencing have enabled profiling of microRNAs (miRNAs), however, a consensus pipeline for sequencing of small RNAs has not been established. We built and optimized an analysis pipeline using Partek Flow, circumventing the need for analyzing data via scripting languages. Our analysis assessed the effect of alignment reference, normalization method, and statistical model choice on biological data. The pipeline was evaluated using sequencing data from HaCaT cells transfected with either a non-silencing control or siRNA against ΔNp63α, a p53 family member protein which is highly expressed in non-melanoma skin cancer and shown to regulate a number of miRNAs. We posit that 1) alignment and quantification to the miRBase reference provides the most robust quantitation of miRNAs, 2) normalizing sample reads via Trimmed Mean of M-values is the most robust method for accurate downstream analyses, and 3) use of the lognormal with shrinkage statistical model effectively identifies differentially expressed miRNAs. Using our pipeline, we identified previously unrecognized regulation of miRs-149-5p, 18a-5p, 19b-1-5p, 20a-5p, 590-5p, 744-5p and 93-5p by ΔNp63α. Regulation of these miRNAs was validated by RT-qPCR, substantiating our small RNA-Seq pipeline. Further analysis of these miRNAs may provide insight into ΔNp63α's role in cancer progression. By defining the optimal alignment reference, normalization method, and statistical model for analysis of miRNA sequencing data, we have established an analysis pipeline that may be carried out in Partek Flow or at the command line. In this manner, our pipeline circumvents some of the major hurdles encountered during small RNA-Seq analysis.

The miR-124-p63 feedback loop modulates colorectal cancer growth

Among the diverse co-regulatory relationships between transcription factors (TFs) and microRNAs (miRNAs), feedback loops have received the most extensive research attention. The co-regulation of TFs and miRNAs plays an important role in colorectal cancer (CRC) growth. Here, we show that miR-124 can regulate two isoforms of p63, TAp63 and ΔNp63, via iASPP, while p63 modulates signal transducers and activators of transcription 1 (STAT1) expression by targeting miR-155. Moreover, STAT1 acts as a regulator of CRC growth by targeting miR-124. Taken together, these results reveal a feedback loop between miRNAs and TFs. This feedback loop comprises miR-124, iASPP, STAT1, miR-155, TAp63 and ΔNp63, which are essential for CRC growth. Moreover, this feedback loop is perturbed in human colon carcinomas, which suggests that the manipulation of this microRNA-TF feedback loop has therapeutic potential for CRC.

Analysis of tissue and circulating microRNA expression during metaplastic transformation of the esophagus

Genetic changes involved in the metaplastic progression from squamous esophageal mucosa toward Barrett's metaplasia and adenocarcinoma are almost unknown. Several evidences suggest that some miRNAs are differentially expressed in Barrett's esophagus (BE) and esophageal adenocarcinoma. Among these, miR-143, miR-145, miR-194, miR-203, miR-205, miR-215 appear to have a key role in metaplasia and neoplastic progression. The aim of this study was to analyze deregulated miRNAs in serum and esophageal mucosal tissue biopsies to identify new biomarkers that could be associated with different stages of esophageal disease. Esophageal mucosal tissue biopsies and blood samples were collected and analyzed for BE diagnosis. Quantitative Real-time PCR was used to compare miRNA expression levels in serum and 60 disease/normal-paired tissues from 30 patients diagnosed with esophagitis, columnar-lined oesophagus (CLO) or BE. MiRNA expression analysis showed that miR-143, miR-145, miR-194 and miR-215 levels were significantly higher, while miR-203 and miR-205 were lower in BE tissues compared with their corresponding normal tissues. Esophageal mucosa analysis of patients with CLO and esophagitis showed that these miRNAs were similarly deregulated but to a lesser extent keeping the same trend and CLO appeared as intermediate step between esophagitis and BE. Analysis on circulating miRNA levels confirmed that miR-194 and miR-215 were significantly upregulated in both BE and CLO compared to esophagitis, while miR-143 was significantly upregulated only in the Barrett group. These findings suggest that miRNAs may be involved in neoplastic/metaplastic progression and miRNA analysis might be useful for progression risk prediction as well as for monitoring of BE/CLO patients.

miR-340 and ZEB1 negative feedback loop regulates TGF-β- mediated breast cancer progression

MicroRNAs act as key regulators in carcinogenesis and progression in various cancers. In present study, we explored the role of miR-340 in the breast cancer progression. Our results showed that overexpression of miR-340 inhibits breast cancer cell proliferation and invasion, whereas depletion of miR-340 promotes breast cancer progression. Molecularly, ZEB1 was identified as a target gene of miR-340 and miR-340 suppressed the expression of ZEB1 by directly binding to the 3′-UTR of ZEB1. Furthermore, ZEB1 transcriptionally suppresses miR-340 expression. The negative feedback loop regulated TGF-β-mediated breast cancer progression. In conclusion, our data suggested that miR-340 acted as a tumor suppressor in breast cancer progression.

Negative feedback between TAp63 and Mir-133b mediates colorectal cancer suppression

Background

TAp63 is known as the most potent transcription activator and tumor suppressor. microRNAs (miRNAs) are increasingly recognized as essential components of the p63 pathway, mediating downstream post-transcriptional gene repression. The aim of present study was to investigate a negative feedback loop between TAp63 and miR-133b.

Results

Overexpression of TAp63 inhibited HCT-116 cell proliferation, apoptosis and invasion via miR-133b. Accordingly, miR-133b inhibited TAp63 expression through RhoA and its downstream pathways. Moreover, we demonstrated that TAp63/miR-133b could inhibit colorectal cancer proliferation and metastasis in vivo and vitro.

Materials and Methods

We evaluated the correlation between TAp63 and miR-133b in HCT-116 cells and investigated the roles of the TAp63/miR-133b feedback loop in cell proliferation, apoptosis and metastasis via MTT, flow cytometry, Transwell, and nude mouse xenograft experiments. The expression of TAp63, miR-133b, RhoA, α-tubulin and Akt was assessed via qRT-PCR, western blot and immunofluorescence analyses. miR-133b target genes were identified through luciferase reporter assays.

Conclusions

miR-133b plays an important role in the anti-tumor effects of TAp63 in colorectal cancer. miR-133b may represent a tiemolecule between TAp63 and RhoA, forming a TAp63/miR-133b/RhoA negative feedback loop, which could significantly inhibit proliferation, apoptosis and metastasis.

ΔNp63α induces the expression of FAT2 and Slug to promote tumor invasion

Tumor invasion can be induced by changes in gene expression that alter cell phenotype. The transcription factor ΔNp63α promotes basal-like breast cancer (BLBC) migration by inducing the expression of the mesenchymal genes Slug and Axl, which confers cells with a hybrid epithelial/mesenchymal state. However, the extent of the ΔNp63α regulated genes that support invasive behavior is not known. Here, using gene expression analysis, ChIP-seq, and functional testing, we find that ΔNp63α promotes BLBC motility by inducing the expression of the atypical cadherin FAT2, the vesicular binding protein SNCA, the carbonic anhydrase CA12, the lipid binding protein CPNE8 and the kinase NEK1, along with Slug and Axl. Notably, lung squamous cell carcinoma migration also required ΔNp63α dependent FAT2 and Slug expression, demonstrating that ΔNp63α promotes migration in multiple tumor types by inducing mesenchymal and non-mesenchymal genes. ΔNp63α activation of FAT2 and Slug influenced E-cadherin localization to cell-cell contacts, which can restrict spontaneous cell movement. Moreover, live-imaging of spheroids in organotypic culture demonstrated that ΔNp63α, FAT2 and Slug were essential for the extension of cellular protrusions that initiate collective invasion. Importantly, ΔNp63α is co-expressed with FAT2 and Slug in patient tumors and the elevated expression of ΔNp63α, FAT2 and Slug correlated with poor patient outcome. Together, these results reveal how ΔNp63α promotes cell migration by directly inducing the expression of a cohort of genes with distinct cellular functions and suggest that FAT2 is a new regulator of collective invasion that may influence patient outcome.

Interplay between ΔNp63 and miR-138-5p regulates growth, metastasis and stemness of oral squamous cell carcinoma

TP63 acts as a master regulator in epithelia development and in the progression of various cancers, but its role in oral cancer pathogenesis remains unknown. This study aimed to explore the role of TP63 in the progression of oral squamous cell carcinoma (OSCC). This study shows that ΔNp63, the predominant isoform of TP63, is significantly upregulated in OSCC tissues and cell lines compared with their normal counterparts, and its expression is closely correlated with pathological differentiation, lymph node metastasis and clinical stage in patients with OSCC. The overexpression of ΔNp63 promotes growth, metastasis and stem-like properties in OSCC cells, and ΔNp63 depletion significantly represses OSCC cellular phenotypes in vitro and in vivo. The ΔNp63 isoform transcriptionally suppresses miR-138-5p expression; restoration of miR-138-5p expression partially abolishes the effect of upregulating ΔNp63. This study also demonstrates that miR-138-5p directly targets ΔNp63, resulting in crosstalk with ΔNp63. The correlation between ΔNp63 and miR-138-5p was further validated in OSCC tissues and was found to be significantly associated with the prognosis of patients with OSCC. Therefore, our data reveal that the interplay between ΔNp63 and miR-138-5p promotes OSCC progression by regulating cell growth, metastasis and stemness.

Insights into the involvement of noncoding RNAs in 5-fluorouracil drug resistance

5-Fluorouracil is a classic chemotherapeutic drug that is widely used to treat various cancers. However, patients often exhibit primary or acquired drug resistance during treatment with 5-fluorouracil chemotherapy. 5-Fluorouracil resistance is a multifactorial event that involves abnormal enzyme metabolism, transport deregulation, cell cycle disorders, apoptosis resistance, and mismatch repair deficiency. Despite advancements in bioresearch technologies in the past several decades, the molecular mechanisms of 5-fluorouracil resistance have not been completely clarified. Recently, microarray analyses have shown that noncoding RNAs (i.e. microRNAs and long noncoding RNAs) play a vital role in 5-fluorouracil resistance in multiple cancer cell lines. These noncoding RNAs can function as oncogenes or tumor suppressors, contributing to 5-fluorouracil drug resistance. In this review, we discuss the effects of microRNAs on 5-fluorouracil sensitivity via targeting of metabolic enzymes, the cell cycle, apoptosis, autophagy, the epithelial–mesenchymal transition, and cancer stem cells. In particular, we focus on summarizing current knowledge on the molecular mechanisms through which long noncoding RNAs mediate 5-fluorouracil drug resistance. Moreover, we describe the specific microRNAs that may function as markers for prediction of chemotherapeutic response to 5-fluorouracil. This review will help to improve the current understanding of how to reverse 5-fluorouracil resistance and may facilitate the establishment of new strategies for alleviating drug resistance in the future.

Predictive value of p63, ki-67, and survivin expression in oral leukoplakia: A tissue microarray study

The aim of this study was to analyze the immunohistochemical expression of survivin, ki-67, and p63 in oral leukoplakic lesions, histopathologically differentiated into dysplastic and nondysplastic. A tissue microarray containing 57 samples of biopsies from clinically classified lesions, such as leukoplakia, was immunolabeled for survivin, ki-67, and p63. Samples were scored for percentage of positively stained. Scores were designated as follows: low = less than 25% of positive cells; and high = more than 25% of positive cells. On performing histopathological diagnosis, 20 dysplastic lesions and 37 nondysplastic lesions were seen, in which female patients (56.1%) were predominant with an average age of 58.27 years. The study showed a high expression of 37.5% for survivin, 43.7% for ki-67, and 88.2% for p63 in dysplastic lesions. However, there was a high expression of 16.7% for survivin, 16.7% for ki-67, and 92% for p63 in nondysplastic lesions. There is a positive correlation of expression among the three antibodies. In the association of immunoreactivity, in both dysplastic and nondysplastic lesions, increased expression of survivin reflects on the increased expression of ki-67, and there is an overexpression of p63. In leukoplakia, the expression of survivin associated with that of ki-67 reinforces the assumption that all these lesions are potentially malignant, regardless of histopathology; and the overexpression of p63 may indicate carcinogenic potential. These findings may help in the treatment of patients with this type of lesion.

KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1

Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity.

Pharmacokinetics and Pharmacodynamics of a 13-mer LNA-inhibitor-miR-221 in Mice and Non-human Primates

Locked nucleic acid (LNA) oligonucleotides have been successfully used to efficiently inhibit endogenous small noncoding RNAs in vitro and in vivo. We previously demonstrated that the direct miR-221 inhibition by the novel 13-mer LNA-i-miR-221 induces significant antimyeloma activity and upregulates canonical miR-221 targets in vitro and in vivo. To evaluate the LNA-i-miR-221 pharmacokinetics and pharmacodynamics, novel assays for oligonucleotides quantification in NOD.SCID mice and Cynomolgus monkeys (Macaca fascicularis) plasma, urine and tissues were developed. To this aim, a liquid chromatography/mass spectrometry method, after solid-phase extraction, was used for the detection of LNA-i-miR-221 in plasma and urine, while a specific in situ hybridization assay for tissue uptake analysis was designed. Our analysis revealed short half-life, optimal tissue biovailability and minimal urine excretion of LNA-i-miR-221 in mice and monkeys. Up to 3 weeks, LNA-i-miR-221 was still detectable in mice vital organs and in xenografted tumors, together with p27 target upregulation. Importantly, no toxicity in the pilot monkey study was observed. Overall, our findings indicate the suitability of LNA-i-miR-221 for clinical use and we provide here pilot data for safety analysis and further development of LNA-miRNA-based therapeutics for human cancer.

ΔNp63α attenuates tumor aggressiveness by suppressing miR-205/ZEB1-mediated epithelial-mesenchymal transition in cervical squamous cell carcinoma

Cervical cancer is one of the most common female cancers worldwide. Although the therapeutic outcomes of patients with early-stage cervical cancer have been significantly improved in the past decades, tumor metastasis and recurrence remain the major causes of cervical cancer-related deaths. In cervical squamous cell carcinoma (SCC), the aberrant activation of epithelial-mesenchymal transition (EMT), a crucial process in invasion and metastasis of epithelial cancer, could promote lymph nodal metastasis and recurrence, and predicts poor prognosis. In this study, we show that the expression levels of EMT markers, β-catenin and Vimentin, are associated with the p63 isoform ΔNp63α in SCC by using immunohistochemistry staining and analysis. Compared to the control SiHa cells (SiHa-NC), the expression of E-cadherin and β-catenin are upregulated, while Vimentin and ZEB1 are downregulated in the constructed SiHa cell line with stable ΔNp63α overexpression (SiHa-ΔNp63α). Besides, the migration and invasion abilities are also suppressed in SiHa-ΔNp63α cells with a typical epithelial morphology with cobblestone-like shape, suggesting that ΔNp63α is a vital EMT repressor in SCC cells. In addition, the involvement of miR-205/ZEB1 axis in the inhibition effect of ΔNp63α on EMT program is revealed by a miRNA array and confirmed by the subsequent transfection of the miR-205 mimic and antagomir. Moreover, SCC patients with low ΔNp63α expression and high EMT level show more frequent metastasis and recurrence as well as reduced overall survival. Therefore, EMT program and its vital repressor ΔNp63α could be used as biomarkers for tumor metastasis and recurrence in cervical cancer.

miRTarBase 2016: updates to the experimentally validated miRNA-target interactions database

MicroRNAs (miRNAs) are small non-coding RNAs of approximately 22 nucleotides, which negatively regulate the gene expression at the post-transcriptional level. This study describes an update of the miRTarBase (http://miRTarBase.mbc.nctu.edu.tw/) that provides information about experimentally validated miRNA-target interactions (MTIs). The latest update of the miRTarBase expanded it to identify systematically Argonaute-miRNA-RNA interactions from 138 crosslinking and immunoprecipitation sequencing (CLIP-seq) data sets that were generated by 21 independent studies. The database contains 4966 articles, 7439 strongly validated MTIs (using reporter assays or western blots) and 348 007 MTIs from CLIP-seq. The number of MTIs in the miRTarBase has increased around 7-fold since the 2014 miRTarBase update. The miRNA and gene expression profiles from The Cancer Genome Atlas (TCGA) are integrated to provide an effective overview of this exponential growth in the miRNA experimental data. These improvements make the miRTarBase one of the more comprehensively annotated, experimentally validated miRNA-target interactions databases and motivate additional miRNA research efforts.