MicroRNA-421-targeted PDCD4 regulates breast cancer cell proliferation

Human Bone Marrow Mesenchymal Stem Cells-Derived Exosomal miRNA-21-5p Inhibits Lidocaine-Induced Apoptosis in SH-SY5Y Neuroblastoma Cells

Background

Local anesthetic lidocaine is one of the most common pain therapies, but high concentration of lidocaine induced neurotoxicity and its mechanism is unclear. Exosomal microRNAs (miRNAs) is implicated in neuronal diseases, but its role in lidocaine induced neurotoxicity remains to be elucidated.

Methods

All the experiments were performed at Huzhou Key Laboratory of Molecular Medicine, Huzhou City, Jiangsu Province, China in 2022. Lidocaine was used to induce apoptosis of SH-SY5Y cells. Exosomes isolated from bone marrow mesenchymal stem cells (BMSC-exos) were used to co-treat SH-SY5Y cells with lidocaine. Cell apoptosis was measured using a flow cytometer. PKH-67 Dye was used for exosome uptake assay. miR-21-5p mimics/inhibitors, or negative controls were transfected with Lipo2000 to study its effect on lid-induced injury. Interactions between miR-21-5p and PDCD4 was analyzed by luciferase reporter assay.

Results

Administration of BMSC-exo protected SH-SY5Y cells against lidocaine induced apoptosis. Suppressing miR-21-5p dramatically enhanced PDCD4, but miR-21-5p overexpression sharply down-regulated PDCD4. Mechanism study showed that miR-21-5p bound to 3'-UTR of PDCD4 to inhibit it. Suppressing miR-21-5p reversed the effect of BMSC-exo on Lid-induced injury. Results also indicate that miR-21-5p regulated lidocaine-induced injury through targeting PDCD4.

Conclusion

BMSC-exos protected SH-SY5Y cells against lidocaine induced apoptosis through miR-21-5p by targeting PDCD4, which may develop new strategy in the management of lidocaine-induced neurotoxicity.

Integration of TE Induces Cancer Specific Alternative Splicing Events

Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.

Genomic Analyses of Non-Coding RNAs Overlapping Transposable Elements and Its Implication to Human Diseases

It is estimated that up to 80% of the human genome is transcribed into RNA molecules but less than 2% of the genome encodes the proteins, and the rest of the RNA transcripts that are not translated into protein are called non-coding RNAs (ncRNAs). Many studies have revealed that ncRNAs have biochemical activities as epigenetic regulators at the post-transcriptional level. Growing evidence has demonstrated that transposable elements (TEs) contribute to a large percentage of ncRNAs’ transcription. The TEs inserted into certain parts of the genome can act as alternative promoters, enhancers, and insulators, and the accumulation of TEs increases genetic diversity in the human genome. The TEs can also generate microRNAs, so-called miRNA-derived from transposable elements (MDTEs), and are also implicated in disease progression, such as infectious diseases and cancer. Here, we analyzed the origin of ncRNAs and reviewed the published literature on MDTEs related to disease progression.

CircRNA ITCH: Insight Into Its Role and Clinical Application Prospect in Tumor and Non-Tumor Diseases

CircRNA E3 ubiquitin protein ligase (ITCH) (circRNA ITCH, circ-ITCH), a stable closed-loop RNA derived from the 20q11.22 region of chromosome 20, is a new circRNA discovered in the cytoplasm in recent decades. Studies have shown that it does not encode proteins, but regulates proteins expression at different levels. It is down-regulated in tumor diseases and is involved in a number of biological activities, including inhibiting cell proliferation, migration, invasion, and promoting apoptosis. It can also alter disease progression in non-tumor disease by affecting the cell cycle, inflammatory response, and critical proteins. Circ-ITCH also holds a lot of promise in terms of tumor and non-tumor clinical diagnosis, prognosis, and targeted therapy. As a result, in order to aid clinical research in the hunt for a new strategy for diagnosing and treating human diseases, this study describes the mechanism of circ-ITCH as well as its clinical implications.

Dissecting the Roles of PDCD4 in Breast Cancer

The human programmed cell death 4 (PDCD4) gene was mapped at chromosome 10q24 and encodes the PDCD4 protein comprised of 469 amino acids. PDCD4 inhibits protein translation PDCD4 inhibits protein translation to suppress tumor progression, and its expression is frequently decreased in breast cancer. PDCD4 blocks translation initiation complex by binding eIF4A via MA-3 domains or by directly binding 5’ mRNA internal ribosome entry sites with an RNA binding domain to suppress breast cancer progression and proliferation. Numerous regulators and biological processes including non-coding RNAs, proteasomes, estrogen, natural compounds and inflammation control PDCD4 expression in breast cancer. Loss of PDCD4 expression is also responsible for drug resistance in breast cancer. HER2 activation downregulates PDCD4 expression by activating MAPK, AKT, and miR-21 in aromatase inhibitor-resistant breast cancer cells. Moreover, modulating the microRNA/PDCD4 axis maybe an effective strategy for overcoming chemoresistance in breast cancer. Down-regulation of PDCD4 is significantly associated with short overall survival of patients, which suggests that PDCD4 may be an independent prognostic marker for breast cancer.

Interplay Between Non-Coding RNAs and Programmed Cell Death Proteins

Programmed cell death (PDCD) family of proteins includes at least 12 members, function of seven of them being more investigated. These members are PDCD1, PDCD2, PDCD4, PDCD5, PDCD6, PDCD7 and PDCD10. Consistent with the important roles of these proteins in the regulation of apoptosis, dysregulation of PDCDs is associated with diverse disorders ranging from intervertebral disc degeneration, amyotrophic lateral sclerosis, immune thrombocytopenia, type 1 diabetes, congenital hypothyroidism, Alzheimer’s disease to different types of cancers. More recently, the interaction between non-coding RNAs and different members of PDCD family is being discovered. In the current study, we described the functional interactions between PDCDs and two classes of non-coding RNAs, namely microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). miR-21 and miR-183 are two miRNAs whose interactions with PDCDs have been assessed in different contexts. The lncRNAs interaction with PDCDs is mainly assessed in the context of neoplasia indicating the role of MALAT1, MEG3, SNHG14 and LINC00473 in this process.

Long Noncoding RNA GAS5 in Breast Cancer: Epigenetic Mechanisms and Biological Functions

Long noncoding RNAs (lncRNAs) have been identified as contributors to the development and progression of cancer through various functions and mechanisms. LncRNA GAS5 is downregulated in multiple cancers and acts as a tumor suppressor in breast cancer. GAS5 interacts with various proteins (e.g., E2F1, EZH2, and YAP), DNA (e.g., the insulin receptor promoter), and various microRNAs (miRNAs). In breast cancer, GAS5 binds with miR-21, miR-222, miR-221-3p, miR-196a-5p, and miR-378a-5p that indicates the presence of several elements for miRNA binding (MREs) in GAS5. Mediated by the listed miRNAs, GAS5 is involved in the upregulation of a number of mRNAs of suppressor proteins such as PTEN, PDCD4, DKK2, FOXO1, and SUFU. Furthermore, the aberrant promoter methylation is involved in the regulation of GAS5 gene expression in triple-negative breast cancer and some other carcinomas. GAS5 can stimulate apoptosis in breast cancer via diverse pathways, including cell death receptors and mitochondrial signaling pathways. GAS5 is also a key player in the regulation of some crucial signal pathways in breast cancer, such as PI3K/AKT/mTOR, Wnt/β-catenin, and NF-κB signaling. Through epigenetic and other mechanisms, GAS5 can increase sensitivity to multiple drugs and improve prognosis. GAS5 is thus a promising target in the treatment of breast cancer patients.

Regulatory MicroRNAs in T2DM and Breast Cancer

MicroRNAs orchestrate the tight regulation of numerous cellular processes and the deregulation in their activities has been implicated in many diseases, including diabetes and cancer. There is an increasing amount of epidemiological evidence associating diabetes, particularly type 2 diabetes mellitus, to an elevated risk of various cancer types, including breast cancer. However, little is yet known about the underlying molecular mechanisms and even less about the role miRNAs play in driving the tumorigenic potential of the cell signaling underlying diabetes pathogenesis. This article reviews the role of miRNA in bridging the diabetes–breast cancer association by discussing specific miRNAs that are implicated in diabetes and breast cancer and highlighting the overlap between the disease-specific regulatory miRNA networks to identify a 20-miRNA signature that is common to both diseases. Potential therapeutic targeting of these molecular players may help to alleviate the socioeconomic burden on public health that is imposed by the type 2 diabetes mellitus (T2DM)–breast cancer association.

Circ_0003266 sponges miR-503-5p to suppress colorectal cancer progression via regulating PDCD4 expression

BACKGROUND

Circular RNAs (circRNAs) feature prominently in tumor progression. However, the biological function and molecular mechanism of circ_0003266 in colorectal cancer (CRC) require further investigation.

METHODS

Circ_0003266 expression in 46 pairs CRC tissues / adjacent tissues, and CRC cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR); after circ_0003266 was overexpressed or knocked down in CRC cells, cell proliferation, apoptosis, migration, and invasion were evaluated by the cell counting kit-8 (CCK-8), flow cytometry, and Transwell assays, respectively; the interaction among circ_0003266, miR-503-5p, and programmed cell death 4 (PDCD4) was confirmed using bioinformatics analysis and dual-luciferase reporter assay; PDCD4 protein expression in CRC cells was quantified using Western blot.

RESULTS

Circ_0003266 was significantly lowly expressed in CRC tissues and cell lines. Circ_0003266 overexpression markedly repressed CRC cell proliferation, migration, and invasion, and accelerated the cell apoptosis, but its overexpression promoted the malignant phenotypes of CRC cells. PDCD4 was a direct target of miR-503-5p and circ_0003266 promoted PDCD4 expression by competitively sponging miR-503-5p.

CONCLUSION

Circ_0003266 suppresses the CRC progression via sponging miR-503-5p and regulating PDCD4 expressions, which suggests that circ_0003266 may serve as a novel target for the treatment of CRC.

Circular RNA RHOT1 promotes progression and inhibits ferroptosis via mir-106a-5p/STAT3 axis in breast cancer

To explore the effect of circRHOT1 on breast cancer progression and the underlying mechanism. Significantly, our data revealed that the depletion of circRHOT1 was able to repress the proliferation and induce the apoptosis of breast cancer cells. CircRHOT1 knockdown could remarkably inhibit the invasion and migration in the breast cancer cells. Meanwhile, the depletion of circRHOT1 enhanced the erastin-induced inhibition effect on cell growth of breast cancer cells. The circRHOT1 knockdown notably increased the levels of reactive oxygen species (ROS), iron, and Fe²⁺ in breast cancer cells. Mechanically, circRHOT1 was able to sponge microRNA-106a-5p (miR-106a-5p) and inhibited ferroptosis by down-regulating miR-106a-5p in breast cancer cells. Besides, miR-106a-5p induced ferroptosis by targeting signal transducer and activator of transcription 3 (STAT3) in the system. Moreover, the overexpression of STAT3 and miR-106a-5p inhibitor could reverse circRHOT1 knockdown-mediated breast cancer progression. Functionally, circRHOT1 promoted the tumor growth of breast cancer in vivo. In conclusion, we discovered that circRHOT1 contributed to malignant progression and attenuated ferroptosis in breast cancer by the miR-106a-5p/STAT3 axis. Our finding provides new insights into the mechanism by which circRHOT1 promotes the development of breast cancer. CircRHOT1 and miR-106a-5p may serve as potential targets for breast cancer therapy.

Genomic instability-derived plasma extracellular vesicle-microRNA signature as a minimally invasive predictor of risk and unfavorable prognosis in breast cancer

Background

Breast cancer (BC) is the most frequently diagnosed cancer and the leading cause of cancer-associated deaths in women. Recent studies have indicated that microRNA (miRNA) regulation in genomic instability (GI) is associated with disease risk and clinical outcome. Herein, we aimed to identify the GI-derived miRNA signature in extracellular vesicles (EVs) as a minimally invasive biomarker for early diagnosis and prognostic risk stratification.

Experimental design

Integrative analysis of miRNA expression and somatic mutation profiles was performed to identify GI-associated miRNAs. Then, we constructed a discovery and validation study with multicenter prospective cohorts. The GI-derived miRNA signature (miGISig) was developed in the TCGA discovery cohort (n = 261), and was subsequently independently validated in internal TCGA validation (n = 261) and GSE22220 (n = 210) cohorts for prognosis prediction, and in GSE73002 (n = 3966), GSE41922 (n = 54), and in-house clinical exosome (n = 30) cohorts for diagnostic performance.

Results

We identified a GI-derived three miRNA signature (MIR421, MIR128-1 and MIR128-2) in the serum extracellular vesicles of BC patients, which was significantly associated with poor prognosis in all the cohorts tested and remained as an independent prognostic factor using multivariate analyses. When integrated with the clinical characteristics, the composite miRNA-clinical prognostic indicator showed improved prognostic performance. The miGISig also showed high accuracy in differentiating BC from healthy controls with the area under the receiver operating characteristics curve (ROC) with 0.915, 0.794 and 0.772 in GSE73002, GSE41922 and TCGA cohorts, respectively. Furthermore, circulating EVs from BC patients in the in-house cohort harbored elevated levels of miGISig, with effective diagnostic accuracy.

Conclusions

We report a novel GI-derived three miRNA signature in EVs, as an excellent minimally invasive biomarker for the early diagnosis and unfavorable prognosis in BC.

Targeting of KDM5A by miR-421 in Human Ovarian Cancer Suppresses the Progression of Ovarian Cancer Cells

PURPOSE

The retinoblastoma binding protein RBP2 (KDM5A) is a histone demethylase that promotes cell growth in many human cancers. A series of functional experiments were conducted to explore the role of miR-421/KDM5A in ovarian cancer cells and their underlying molecular mechanisms.

MATERIALS AND METHODS

Public microarray databases were analyzed to assess KDM5A and miR-421 expression in ovarian cancer. KDM5A was predicted to be a target of miR-421 using software analysis. The expression of the miR-421/KDM5A regulatory axis in ovarian cancer and the mechanisms of its effects on proliferation, migration, and invasion of ovarian cancer cell lines were investigated.

RESULTS

Compared with normal ovarian tissues, the expression of KDM5A mRNA and protein was elevated (P<0.05), and miR-421 expression was reduced in ovarian cancer tissue (P<0.05). miR-421 was found to bind specifically to the KDM5A gene. Silencing KDM5A or overexpressing miR-421 significantly inhibited proliferation, migration, and invasion of OVCAR-8 and SKOV-3 cells. Similarly, compared with nude mice injected with cells transfected with empty capsids, the in vivo proliferation rate of OVCAR-8 cells after miR-421 overexpression was reduced significantly.

CONCLUSION

The miR-421/KDM5A regulatory axis plays an important role in the development and progression of ovarian cancer cells.

Long non-coding RNA DLEUI promotes papillary thyroid carcinoma progression by sponging miR-421 and increasing ROCK1 expression

We investigated the role of long non-coding RNA DLEU1 (deleted in lymphocytic leukemia 1) in the progression of papillary thyroid carcinoma (PTC). DLEU1 levels were higher in PTC cell lines (BHP5-16, TPC-1,8505C, and SW1736) and patient tissues (n=54) than in a human thyroid follicular epithelial cell line (Nthy-ori3-1) or adjacent normal thyroid tissues. High DLEU1 expression correlated positively with lymph node metastasis and advanced clinical stages in PTC patients. Bioinformatics, dual luciferase reporter, and RNA pulldown assays confirmed that DLEU1 directly binds to miR-421. Moreover, bioinformatics and dual luciferase reporter assays showed that miR-421 directly binds to the 3'untranslated region of the rho-related coiled-coil kinase 1 (ROCK1) in TPC-1 cells. PTC patient tissues and cell lines showed high ROCK1 mRNA and protein levels as well as low miR-421 levels. CCK-8, flow cytometry, wound healing, and Transwell invasion assays demonstrated that DLEU1 silencing decreases TPC-1 cell proliferation, survival and progression, but they can be rescued by miR-421 knockdown or ROCK1 overexpression. DLEU1 knockdown in TPC-1 cells decreased in vivo xenograft tumor size and weight compared to controls in nude mice. These findings demonstrate that DLEU1 promotes PTC progression by sponging miR-421 and increasing ROCK1 expression.

Potential miRNAs for miRNA-Based Therapeutics in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNAs that can post-transcriptionally regulate the genes involved in critical cellular processes. The aberrant expressions of oncogenic or tumor suppressor miRNAs have been associated with cancer progression and malignancies. This resulted in the dysregulation of signaling pathways involved in cell proliferation, apoptosis and survival, metastasis, cancer recurrence and chemoresistance. In this review, we will first (i) provide an overview of the miRNA biogenesis pathways, and in vitro and in vivo models for research, (ii) summarize the most recent findings on the roles of microRNAs (miRNAs) that could potentially be used for miRNA-based therapy in the treatment of breast cancer and (iii) discuss the various therapeutic applications.

Five miRNAs-mediated PIEZO2 downregulation, accompanied with activation of Hedgehog signaling pathway, predicts poor prognosis of breast cancer

Roles of Piezo-type mechanosensitive ion channel component 2 (PIEZO2) in cancer remain largely unknown. Herein, we explored PIEZO2 expression, prognosis and underlying mechanisms in cancer. Breast was selected as the candidate as its relatively higher expression level of PIEZO2 than other human tissues. Next, we identified a decreased expression of PIEZO2 in breast cancer compared with normal controls, and found that PIEZO2 expression positively correlated with estrogen receptor (ER) and progesterone receptor (PR) status but negatively correlated with human epidermal growth factor receptor 2 (HER2) status, Nottingham Prognostic Index (NPI) score, Scarff-Bloom-Richardson (SBR) grade, basal-like and triple-negative status. Subsequent analysis revealed that high expression of PIEZO2 had a favorable prognosis in breast cancer. 182 miRNAs were predicted to target PIEZO2. Among these miRNAs, five miRNAs (miR-130b-3p, miR-196a-5p, miR-301a-3p, miR-421 and miR-454-3p) possess the greatest potential in targeting PIEZO2. 109 co-expressed genes of PIEZO2 were identified. Pathway enrichment analysis showed that these genes were enriched in Hedgehog signaling pathway, including Cell adhesion molecule-related/downregulated by oncogenes (CDON). CDON expression was decreased in breast cancer and downregulation of CDON indicated a poor prognosis. Altogether, these findings suggest that decreased expression of PIEZO2 may be utilized as a prognostic biomarker of breast cancer.

MiR-421 Is Overexpressed and Promotes Cell Proliferation in Non-Small Cell Lung Cancer

BACKGROUND

Lung cancer is the main cause of cancer--related deaths worldwide, and the overall 5-year survival rate of non-small cell lung cancer (NSCLC) remained low. -MicroRNAs had been confirmed to be an important regulator in tumor progression, and they could serve as either tumor promoters or suppressors in NSCLC.

OBJECTIVES

To identify the novel cancer-specific biomarkers for NSCLC patients, which may be useful to monitor tumor progression and improve NSCLC patients' survival.

METHOD

The expression profile of miR-421 was analyzed in NSCLC samples using public datasets, including The Cancer Genome Atlas and GSE102286. The expression level of miR-421 was detected by reverse transcription-polymerase chain reaction. Cell proliferation and cell cycle were detected by Cell Counting Kit assay, flow cytometry assay, respectively. Kyoto Encyclopedia of Genes and Genomes analysis were applied to determine the biological roles of miR-421, based on the online DAVID system. Statistical comparisons between groups of normalized data were performed using t test or Mann-Whitney U test according to the test condition.

RESULTS

In this study, we focused on exploring the roles of miR-421 in NSCLC prognosis and growth. The present study for the first time showed that miR-421 was overexpressed in NSCLC and associated with a shorter overall survival time of patients with NSCLC. Bioinformatics analysis revealed miR-421 was involved in transcription, cell cycle, and insulin signaling pathway regulation. Furthermore, a gain of function assay showed that overexpression of miR-421 could promote NSCLC cell proliferation and cell cycle progression.

CONCLUSIONS

Our findings suggest that miR-421 might be a promising prognostic and therapeutic target for NSCLC.

Aberrant Expression Of PDCD4/eIF4A1 Signal Predicts Postoperative Recurrence For Early-Stage Oral Squamous Cell Carcinoma

Background

Programmed cell death 4 (PDCD4) as a tumor suppressor gene inhibits growth and metastasis of cancer cells, which involved with eIF4A1, the inhibitor of translation initiation. Although the prognosis of early-stage oral squamous cell carcinoma (OSCC) is generally better, but many patients occur recurrence after surgery. Understanding the clinical expression pattern of PDCD4/eIF4A1 signal would provide diagnostic biomarker and target therapy premise for early-stage OSCC patients.

Methods

Immunohistochemical analysis was performed on 69 early-stage (T1/2N0M0) OSCC samples to evaluate temporal expression and prognostic value of eIF4A1 and PDCD4 in early-stage OSCC according to cell types and microlocalization. The correlations between PDCD4/eIF4A1 signal and Ki-67, postoperative recurrence and metastasis were determined.

Results

We found that PDCD4 was presented in tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs) but absent in fibroblast-like cells (FLCs). eIF4A1 was only presented in TCs. PDCD4^TCs was negative associated with eIF4A1^TCs in tumor center, and patients with low PDCD4^TCs or high eIF4A1^TCs had poorer differentiation. Moreover, aberrant PDCD4/eIF4A1 signal led to higher Ki-67 level. Interestingly, patients with low expressed PDCD4^TILs had better prognosis, indicating the function heterogeneity of PDCD4 in different cell types. Furthermore, low PDCD4 ^TCs and high eIF4A1^TCs predicted higher postoperative recurrence rate and are significant independent risk factors for early-stage OSCC.

Conclusion

Patients with low PDCD4^TCs and high eIF4A1^TCs have higher recurrence rate and poor clinical outcome. Of note, PDCD4^TILs exerts contradictory function. Thus, PDCD4/eIF4A1 targeting therapeutics should consider the function heterogeneity of PDCD4.

MicroRNA-421 confers paclitaxel resistance by binding to the KEAP1 3'UTR and predicts poor survival in non-small cell lung cancer

MicroRNAs regulate post-transcriptional gene expression and play important roles in multiple cellular processes. In this study, we found that miR-421 suppresses kelch-like ECH-associated protein 1(KEAP1) expression by targeting its 3'-untranslated region (3'UTR). A Q-PCR assay demonstrated that miR-421 is overexpressed in non-small cell lung cancer (NSCLC), especially in A549 cells. Consistently, the level of miR-421 was higher in clinical blood samples from lung cancer patients than in those from normal healthy donors, suggesting that miR-421 is an important lung cancer biomarker. Interestingly, overexpression of miR-421 reduced the level of KEAP1 expression, which further promoted lung cancer cell migration and invasion, as well as inhibited cell apoptosis both in vivo and in vitro. Furthermore, knockdown of miR-421 expression with an antisense morpholino oligonucleotide (AMO) increased ROS levels and treatment sensitivity to paclitaxel in vitro and in vivo, indicating that high miR-421 expression may at least partly account for paclitaxel tolerance in lung cancer patients. To find the upstream regulator of miR-421, one of the candidates, β-catenin, was knocked out via the CRISPR/Cas9 method in A549 cells. Our data showed that inhibiting β-catenin reduced miR-421 levels in A549 cells. In addition, β-catenin upregulation enhanced miR-421 expression, indicating that β-catenin regulates the expression of miR-421 in lung cancer. Taken together, our findings reveal the critical role of miR-421 in paclitaxel drug resistance and its upstream and downstream regulatory mechanisms. Therefore, miR-421 may serve as a potential molecular therapeutic target in lung cancer, and AMOs may be a potential treatment strategy.

MicroRNAs and Epigenetics Strategies to Reverse Breast Cancer

Breast cancer is a sporadic disease with genetic and epigenetic components. Genomic instability in breast cancer leads to mutations, copy number variations, and genetic rearrangements, while epigenetic remodeling involves alteration by DNA methylation, histone modification and microRNAs (miRNAs) of gene expression profiles. The accrued scientific findings strongly suggest epigenetic dysregulation in breast cancer pathogenesis though genomic instability is central to breast cancer hallmarks. Being reversible and plastic, epigenetic processes appear more amenable toward therapeutic intervention than the more unidirectional genetic alterations. In this review, we discuss the epigenetic reprogramming associated with breast cancer such as shuffling of DNA methylation, histone acetylation, histone methylation, and miRNAs expression profiles. As part of this, we illustrate how epigenetic instability orchestrates the attainment of cancer hallmarks which stimulate the neoplastic transformation-tumorigenesis-malignancy cascades. As reversibility of epigenetic controls is a promising feature to optimize for devising novel therapeutic approaches, we also focus on the strategies for restoring the epistate that favor improved disease outcome and therapeutic intervention.

The Regulatory Role of Non-coding RNAs on Programmed Cell Death Four in Inflammation and Cancer

Programmed cell death 4 (PDCD4) is a tumor suppressor gene implicated in many cellular functions, including transcription, translation, apoptosis, and the modulation of different signal transduction pathways. The downstream mechanisms of PDCD4 have been well-discussed, but its upstream regulators have not been systematically summarized. Noncoding RNAs (ncRNAs) are gene transcripts with no protein-coding potential but play a pivotal role in the regulation of the pathogenesis of solid tumors, cardiac injury, and inflamed tissue. In recent studies, many ncRNAs, especially microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), were found to interact with PDCD4 to manipulate its expression through transcriptional regulation and function as oncogenes or tumor suppressors. For example, miR-21, as a classic oncogene, was identified as the key regulator of PDCD4 by targeting its 3′-untranslated region (UTR) to promote tumor proliferation, migration, and invasion in colon, breast, and bladder carcinoma. Therefore, we reviewed the recently emerging pleiotropic regulation of PDCD4 by ncRNAs in cancer and inflammatory disorders and aimed to shed light on the mechanisms of associated diseases, which could be conducive to the development of novel treatment strategies for PDCD4-induced diseases.

Lidocaine inhibits cervical cancer cell proliferation and induces cell apoptosis by modulating the lncRNA-MEG3/miR-421/BTG1 pathway

This study aimed to explore the effect of lidocaine on the growth of cervical cancer cells (HeLa) and the underlying molecular mechanisms. Cell counting kit-8 (CCK-8) and flow cytometry (FCM) were used to detect the cell viability and apoptosis of cervical cancer cells after lidocaine treatment. Lidocaine inhibited cell viability and promoted apoptosis in HeLa cells. Long noncoding RNA maternally expressed gene 3 (lncRNA-MEG3) was significantly downregulated in cervical cancer cells, and lidocaine increased the expression of lncRNA-MEG3 in HeLa cells. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR), CCK-8, and FCM assays were used to test indicators. MEG3-shRNA promoted the cell viability and inhibited apoptosis, while the effect of lidocaine was the opposite. The effects of lidocaine on HeLa cells were reversed by MEG3-shRNA. The level of miR-421 in cervical cancer and normal cervical cells was detected using qRT-PCR. The MEG3-plasmid could inhibit cell viability and induce cell apoptosis, but these effects were reversed by miR-421 upregulation. Hence, lidocaine suppressed tumor growth by regulating cell viability and inducing apoptosis. The results indicated that BTG anti-proliferation factor 1 (BTG1) was a direct target of miR-421. HeLa cells were transfected with inhibitor control, miR-421 inhibitor, control-shRNA, or BTG1-shRNA. The negative effects of the miR-421 inhibitor or knockdown BTG1 on cell viability and apoptosis were identified using CCK-8 assay and FCM. The miR-421 inhibitor improved cervical cancer progression by regulating BTG1 expression. The results suggested that lidocaine inhibited the growth of cervical cancer cells by modulating the lncRNA-MEG3/miR-421/BTG1 signaling pathway, providing opportunities for treating cervical cancer.

Mir-421 in plasma as a potential diagnostic biomarker for precancerous gastric lesions and early gastric cancer

Objective

MicroRNA (miR)-421 plays a key role in cancer progression. It has been reported that circulating miR-421may be a potential tumor marker for the diagnosis of several cancers. However, the role of miR-421 in plasma as a potential biomarker in the diagnosis of precancerous gastric lesions (Pre) and early-stage gastric cancer (GC) remains poorly understood. In this study, we investigated miR-421 in plasma as a novel potential biomarker for the detection of precancerous gastric lesions and early-stage (GC).

Materials & Methods

The miRNA content was determined by quantitative real-time polymerase chain reaction (qRT-PCR). MiR-421 content in all subjects was normalized by endogenous miRNA (miR-16). The diagnostic value of miR-421 for Pre and GC was assessed by comparing receiver operating characteristic (ROC) analysis with traditional tumor markers, including CEA, CA125, CA153, CA211 and CA50. The correlation between the expression of miR-421 and the pathological characteristics of Pre and GC was analyzed.

Results

Elevated expression of miR-421 in plasma can robustly distinguish the normal population from Pre and GC cases, especially in the early stages of gastric cancer cases (all p < 0.05). The ROC analyses showed that the area under the ROC curve (AUC), sensitivity, accuracy and Youden index of miR-421 were superior to traditional tumor markers (CEA, CA125, CA153, CA211, and CA50) in GC diagnosis, while its specificity was higher than CEA, CA153 and CA50 (all p < 0.05). MiR-421 in plasma had higher AUC value than AFP, CA153, CA211 and CA50 in the diagnosis of Pre (all p < 0.05), while specificity, accuracy and Youden index of miR-421 was only lower than CA211. The efficiency of miR-421 in the diagnosis of GC was significantly higher than that of CA211 and CA50, and it was significantly higher than CA153, CA211 and CA50 in the diagnosis of Pre (all p < 0.05). In addition, up-regulation of miR-421 occurred initially in precancerous gastric lesions as well as in the early stage of GC.

Conclusions

Overexpression of plasma miR-421 is a novel biomarker for the detection of precancerous lesions and early gastric cancer.

miR-338-3p Is Regulated by Estrogens through GPER in Breast Cancer Cells and Cancer-Associated Fibroblasts (CAFs)

Estrogens acting through the classic estrogen receptors (ERs) and the G protein estrogen receptor (GPER) regulate the expression of diverse miRNAs, small sequences of non-coding RNA involved in several pathophysiological conditions, including breast cancer. In order to provide novel insights on miRNAs regulation by estrogens in breast tumor, we evaluated the expression of 754 miRNAs by TaqMan Array in ER-negative and GPER-positive SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) upon 17β-estradiol (E2) treatment. Various miRNAs were regulated by E2 in a peculiar manner in SkBr3 cancer cells and CAFs, while miR-338-3p displayed a similar regulation in both cell types. By METABRIC database analysis we ascertained that miR-338-3p positively correlates with overall survival in breast cancer patients, according to previous studies showing that miR-338-3p may suppress the growth and invasion of different cancer cells. Well-fitting with these data, a miR-338-3p mimic sequence decreased and a miR-338-3p inhibitor sequence rescued the expression of genes and the proliferative effects induced by E2 through GPER in SkBr3 cancer cells and CAFs. Altogether, our results provide novel evidence on the molecular mechanisms by which E2 may regulate miR-338-3p toward breast cancer progression.