miR-34a sensitizes lung cancer cells to cisplatin via p53/miR-34a/MYCN axis

Differences between lung adenocarcinoma and lung squamous cell carcinoma: Driver genes, therapeutic targets, and clinical efficacy

With the rapid advancements in second-generation gene sequencing technologies, a growing number of driver genes and associated therapeutic targets have been unveiled for lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). While they are clinically classified as non-small cell lung cancer (NSCLC), they display distinct genomic features and substantial variations in clinical efficacy, underscoring the need for particular attention. Hence, this review provides a comprehensive overview of the latest advancements in driver genes, epigenetic targets, chemotherapy, targeted therapy, and immunotherapy for LUAD and LUSC. Additionally, it delves into the distinctions in signaling pathways and pivotal facets of clinical management specific to these two categories of lung cancer. Moreover, we furnish pertinent details regarding clinical trials pertaining to driver genes and epigenetics, thus establishing a theoretical foundation for the realization of precision treatments for LUAD and LUSC.

Polyphenols as microRNA modulator in endometrial cancer: implications for apoptosis induction

Endometrial cancer (EC) accounts for approximately 417,336 cases globally, making it the sixth most commonly diagnosed cancer among women. Such factors have led to hesitancy in utilizing aggressive treatments or enrolling older patients in clinical trials. Recent molecular studies have identified unique expression patterns of microRNAs (miRNAs) in endometrial cancer tissue compared to healthy endometrial tissue, highlighting their role in tumorigenesis through pathways that support proliferation, invasion, and metastasis. Polyphenols, bioactive compounds found in a variety of plant-based foods such as fruits, vegetables, tea, and soybeans, have demonstrated diverse physiological benefits, including antioxidant, anti-inflammatory, and anticancer properties. These compounds influence cellular pathways critical to cancer progression, including apoptosis, immune modulation, and inflammation reduction. Emerging evidence suggests that polyphenols may exert anticancer effects in part by modulating miRNAs involved in carcinogenesis. Specifically, compounds like curcumin, quercetin, resveratrol, and genistein have shown potential in targeting oncogenic and tumor-suppressive miRNAs, thereby impacting cellular mechanisms linked to cancer progression. Therefore, this review examines the role of polyphenols in regulating miRNAs within the context of endometrial cancer, focusing on their potential to modulate apoptosis and other cancer hallmarks. By elucidating these mechanisms, this paper aims to contribute to the understanding of polyphenol-mediated miRNA regulation as a promising therapeutic avenue in endometrial cancer management.

Retracted article: MYCN contributes to the sensitization of acute myelogenous leukemia cells to cisplatin by targeting SRY-box transcription factor 4

Xianbao Huang, Ling Qi, Wei Lu, Ziye Li, Wuping Li and Fei Li. MYCN contributes to the sensitization of acute myelogenous leukemia cells to cisplatin by targeting SRY-box transcription factor 4. Bioengineered. 2021 Oct. doi: 10.1080/21655979.2021.1997697.Since publication, significant concerns have been raised about the compliance with ethical policies for human research and the integrity of the data reported in the article.When approached for an explanation, the authors provided some original data but were not able to provide all the necessary supporting information. As verifying the validity of published work is core to the scholarly record's integrity, we are retracting the article. All authors listed in this publication have been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted.'

Evaluation of Long Non-coding RNA (LncRNA) in the Pathogenesis of Chemotherapy Resistance in Cervical Cancer: Diagnostic and Prognostic Approach

Cervical cancer (CC), caused by human papillomavirus (HPV), is a leading cause of female malignancies worldwide. Therefore, understanding the underlying mechanisms of CC development and identifying novel therapeutic targets are significantly important. Cisplatin resistance is a significant challenge in the management of CC. Recent studies highlighted the critical role of long non-coding RNAs (lncRNAs) in modulation of cisplatin resistance. This comprehensive review aims to collect the current understanding roles of lncRNAs and their involvement in cisplatin resistance in CC by highlighting key processes of cancer progression, including apoptosis, proliferation, angiogenesis and epithelial-to-mesenchymal transition (EMT). We discussed the role of lncRNA in CC resistance to cisplatin through molecular pathways and examined gene expression changes. We also discussed treatment strategies and factors that reduce CC resistance to cisplatin by targeting them.

The microRNA-34 Family and Its Functional Role in Lung Cancer

Lung cancer is one of the most common malignant tumors in humans and the leading cause of cancer-related deaths worldwide. The microRNA-34 (miR-34) family is dysregulated in various human cancers and is an important family of tumor suppressor genes among microRNAs. The miR-34 family is downregulated in lung cancer. It inhibits cell proliferation, metastasis, and invasion, arrests the cell cycle, and induces apoptosis or senescence by negatively regulating many oncogenes. It is commonly used to detect and treat lung cancer. This study describes the regulatory role of the miR-34 family in lung cancer and the associated research advances in treatment.

Cell cycle associated miRNAs as target and therapeutics in lung cancer treatment

Lung cancer is the primary cause of cancer related deaths worldwide. Limited therapeutic options and resistance to existing drugs are the major hindrances to the clinical success of this cancer. In the past decade, several studies showed the role of microRNA (miRNA) driven cell cycle regulation in lung cancer progression. Therefore, these small nucleotide molecules could be utilized as promising tools in lung cancer therapy. In this review, we highlighted the recent advancements in lung cancer therapy using cell cycle linked miRNAs. By highlighting the roles of the specific cell cycle core regulators affiliated miRNAs in lung cancer, we further outlined how these miRNAs can be explored in early diagnosis and treatment strategies to prevent lung cancer. With the provided information from our review, more medical efforts can ensure a potential breakthrough in miRNA-based lung cancer therapy.

Polyphenols as Lung Cancer Chemopreventive Agents by Targeting microRNAs

Lung cancer is the second leading cause of cancer-related death worldwide. In recent decades, investigators have found that microRNAs, a group of non-coding RNAs, are abnormally expressed in lung cancer, and play important roles in the initiation and progression of lung cancer. These microRNAs have been used as biomarkers and potential therapeutic targets of lung cancer. Polyphenols are natural and bioactive chemicals that are synthesized by plants, and have promising anticancer effects against several kinds of cancer, including lung cancer. Recent studies identified that polyphenols exert their anticancer effects by regulating the expression levels of microRNAs in lung cancer. Targeting microRNAs using polyphenols may provide a novel strategy for the prevention and treatment of lung cancer. In this review, we reviewed the effects of polyphenols on oncogenic and tumor-suppressive microRNAs in lung cancer. We also reviewed and discussed the potential clinical application of polyphenol-regulated microRNAs in lung cancer treatment.

Silencing of Long Non-coding RNA LINC01106 Represses Malignant Behaviors of Gastric Cancer Cells by Targeting miR-34a-5p/MYCN Axis

Long non-coding RNA LINC01106 is an lncRNA aberrantly expressed in gastric cancer (GC). However, the accurate function remains unclear. The objective of this investigation is to explore detailed regulatory mechanism of lncRNA LINC01106 in GC. The expression of lncRNA LINC01106, MYCN, and miR-34a-5p was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was examined using MTT assay. Migratory and invasive abilities of GC cells were evaluated by transwell assay. The targeting relation among lncRNA LINC01106, MYCN, and miR-34a-5p was tested by dual-luciferase reporter (DLR) assay. Relative protein expression of MYCN was assessed via western blot. Besides, a xenograft mouse model was established to assess the role of LINC01106 in GC in vivo. LncRNA LINC01106 and MYCN expression were boosted and miR-34a-5p expression was reduced in GC cells and tissues compared to their controls. Functionally, decreased lncRNA LINC01106 or increased miR-34a-5p restrained GC cells in viability, invasion, and migration in vitro. LINC01106 down-regulation suppressed tumor growth of mice in vivo. In terms of mechanism, lncRNA LINC01106 directly targeted miR-34a-5p and was inversely correlated with miR-34a-5p. MYCN was targeted by miR-34a-5p and was inversely correlated with miR-34a-5p. There was a positive correlation between LINC01106 and MYCN. LINC01106 knockdown led to the suppression of cell invasion, migration, and viability, whereas these effects caused by LINC01106 knockdown were reversed by miR-34a-5p down-regulation or MYCN up-regulation in GC cells. Silencing of lncRNA LINC01106 attenuated cell viability, invasion, and migration by sponging miR-34a-5p to target MYCN in GC.

MicroRNA-625-3p improved proliferation and involved chemotherapy resistance via targeting PTEN in high grade ovarian serous carcinoma

Objective

High-grade serous ovarian cancer (HGSOC) is an aggressive gynaecological malignancy and associated with poor prognosis. Here we examined the effects of miR-625-3p on proliferation, treatment, migration and invasion in HGSOC.

Methods

The proliferation of HGSOC cells was evaluated by MTT assay. Transwell assay was performed to examine migration and matrigel assay were used to assess invasion. The effect of miR-625-3p on cisplatin-induced apoptosis was investigated by Caspase-Glo3/7 assay. The dual-luciferase reporter assay was carried out to confirm the potential binding site.

Results

Overexpression of miR-625-3p promoted proliferation, and increased migration and invasion in HGSOC cells. MiR-625-3p significantly inhibited cisplatin sensitivity in HGSOC cells. Meanwhile, miR-625-3p decreased cisplatin-induced apoptosis by regulation of BAX and Bcl-2 expression. Furthermore, aberrant expression of miR-625-3p changed PTEN expression by directly binding to 3’UTR of PTEN. Further study showed miR-625-3p expression was higher in human HGSOC tissue than normal ovarian tissues and associated with higher clinical stage.

Conclusions

miR-625-3p promotes HGSOC growth, involves chemotherapy resistance and might serve as a potential biomarker to predict chemotherapy response and prognosis in HGSOC.

Metformin Increases Sensitivity of Melanoma Cells to Cisplatin by Blocking Exosomal-Mediated miR-34a Secretion

Melanoma, also known as malignant melanoma, is a type of cancer derived from the pigment-containing cells known as melanocytes. Cisplatin (CDDP) is widely used in the treatment of different types of tumors with high response rates, but it generally has low efficiency in melanoma. This study aimed to investigate whether metformin could sensitize the melanoma cell line A375 to cisplatin. Our results for the first time indicated that CDDP increased the miR-34a secretion by exosomes in melanoma A375 cells, which was, at least partially, related to the cisplatin resistance of melanoma cells. Moreover, metformin significantly sensitized A375 cells to cisplatin. Mechanistically, metformin significantly blocked the exosome-mediated miR-34a secretion induced by cisplatin. Our study not only reveals a novel mechanism that exosomal secretion of miR-34a is involved in the cisplatin resistance of melanoma cells but also provides a promising therapeutic strategy by synergistic addition of metformin.

MiRNAs as Anti-Angiogenic Adjuvant Therapy in Cancer: Synopsis and Potential

Angiogenesis is a key mechanism for tumor growth and metastasis and has been a therapeutic target for anti-cancer treatments. Intensive vascular growth is concomitant with the rapidly proliferating tumor cell population and tumor outgrowth. Current angiogenesis inhibitors targeting either one or a few pro-angiogenic factors or a range of downstream signaling molecules provide clinical benefit, but not without significant side effects. miRNAs are important post-transcriptional regulators of gene expression, and their dysregulation has been associated with tumor progression, metastasis, resistance, and the promotion of tumor-induced angiogenesis. In this mini-review, we provide a brief overview of the current anti-angiogenic approaches, their molecular targets, and side effects, as well as discuss existing literature on the role of miRNAs in angiogenesis. As we highlight specific miRNAs, based on their activity on endothelial or cancer cells, we discuss their potential for anti-angiogenic targeting in cancer as adjuvant therapy and the importance of angiogenesis being evaluated in such combinatorial approaches.

The role of non-coding RNAs in chemotherapy for gastrointestinal cancers

Gastrointestinal (GI) cancers, including colorectal, gastric, hepatic, esophageal, and pancreatic tumors, are responsible for large numbers of deaths around the world. Chemotherapy is the most common approach used to treat advanced GI cancer. However, chemoresistance has emerged as a critical challenge that prevents successful tumor elimination, leading to metastasis and recurrence. Chemoresistance mechanisms are complex, and many factors and pathways are involved. Among these factors, non-coding RNAs (ncRNAs) are critical regulators of GI tumor development and subsequently can induce resistance to chemotherapy. This occurs because ncRNAs can target multiple signaling pathways, affect downstream genes, and modulate proliferation, apoptosis, tumor cell migration, and autophagy. ncRNAs can also induce cancer stem cell features and affect the epithelial-mesenchymal transition. Thus, ncRNAs could possibly act as new targets in chemotherapy combinations to treat GI cancer and to predict treatment response.

Cell Behavior of Non-Small Cell Lung Cancer Is at EGFR and MicroRNAs Hands

Lung cancer is a complex disease associated with gene mutations, particularly mutations of Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) and epidermal growth factor receptor (EGFR). Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the two major types of lung cancer. The former includes most lung cancers (85%) and are commonly associated with EGFR mutations. Several EGFR-tyrosine kinase inhibitors (EGFR-TKIs), including erlotinib, gefitinib, and osimertinib, are effective therapeutic agents in EGFR-mutated NSCLC. However, their effectiveness is limited by the development (acquired) or presence of intrinsic drug resistance. MicroRNAs (miRNAs) are key gene regulators that play a profound role in the development and outcomes for NSCLC via their role as oncogenes or oncosuppressors. The regulatory role of miRNA-dependent EGFR crosstalk depends on EGFR signaling pathway, including Rat Sarcoma/Rapidly Accelerated Fibrosarcoma/Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 (Ras/Raf/MEK/ERK1/2), Signal Transducer and Activator of Transcription (STAT), Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-kB), phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), Janus kinase 1 (JAK1), and growth factor receptor-bound protein 2 (GRB2). Dysregulated expression of miRNAs affects sensitivity to treatment with EGFR-TKIs. Thus, abnormalities in miRNA-dependent EGFR crosstalk can be used as diagnostic and prognostic markers, as well as therapeutic targets in NSCLC. In this review, we present an overview of miRNA-dependent EGFR expression regulation, which modulates the behavior and progression of NSCLC.

A Focus on Regulatory Networks Linking MicroRNAs, Transcription Factors and Target Genes in Neuroblastoma

Neuroblastoma (NB) is a tumor of the peripheral sympathetic nervous system that substantially contributes to childhood cancer mortality. NB originates from neural crest cells (NCCs) undergoing a defective sympathetic neuronal differentiation and although the starting events leading to the development of NB remain to be fully elucidated, the master role of genetic alterations in key oncogenes has been ascertained: (1) amplification and/or over-expression of MYCN, which is strongly associated with tumor progression and invasion; (2) activating mutations, amplification and/or over-expression of ALK, which is involved in tumor initiation, angiogenesis and invasion; (3) amplification and/or over-expression of LIN28B, promoting proliferation and suppression of neuroblast differentiation; (4) mutations and/or over-expression of PHOX2B, which is involved in the regulation of NB differentiation, stemness maintenance, migration and metastasis. Moreover, altered microRNA (miRNA) expression takes part in generating pathogenetic networks, in which the regulatory loops among transcription factors, miRNAs and target genes lead to complex and aberrant oncogene expression that underlies the development of a tumor. In this review, we have focused on the circuitry linking the oncogenic transcription factors MYCN and PHOX2B with their transcriptional targets ALK and LIN28B and the tumor suppressor microRNAs let-7, miR-34 and miR-204, which should act as down-regulators of their expression. We have also looked at the physiologic role of these genetic and epigenetic determinants in NC development, as well as in terminal differentiation, with their pathogenic dysregulation leading to NB oncogenesis.

Two Worlds Colliding: The Interplay Between Natural Compounds and Non-Coding Transcripts in Cancer Therapy

Cancer is a devastating disease and has recently become the leading cause of death in western countries, representing an immense public health burden. When it comes to cancer treatment, chemotherapy is one of the main pillars, especially for advanced stage tumors. Over the years, natural compounds have emerged as one of the most valuable resources for new chemotherapies. It is estimated that more than half of the currently used chemotherapeutic agents are derived from natural compounds. Usually, natural compounds are discovered empirically and an important limitation of introducing new anti-cancer natural products is lack of knowledge with regard to their mechanism of action. Recent data has proven that several natural compounds may function via modulating the expression and function of non-coding RNAs (ncRNAs). NcRNAs are a heterogenous class of RNA molecules which are usually not translated into proteins but have an important role in gene expression regulation and are involved in multiple tumorigenic processes, including response/resistance to pharmacotherapy. In this review, we will discuss how natural compounds function via ncRNAs while summarizing the available data regarding their effects on over 15 types of cancer. Moreover, we will critically analyze the current advances and limitations in understanding the way natural compounds exert these health-promoting effects by acting on ncRNAs. Finally, we will propose several hypotheses that may open new avenues and perspectives regarding the interaction between natural compounds and ncRNAs, which could lead to improved natural compound-based therapeutic strategies in cancer.

The comprehensive landscape of miR-34a in cancer research

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

miR-34a and miR-200c Have an Additive Tumor-Suppressive Effect on Breast Cancer Cells and Patient Prognosis

Breast cancer is the most common women's malignancy in the world and, for subgroups of patients, treatment outcomes remain poor. Thus, more effective therapeutic strategies are urgently needed. MicroRNAs (miRNAs) have emerged as promising therapeutic tools and targets, as they play significant roles in regulating key cellular processes by suppressing gene expression. However, additive opportunities involving miRNAs have been underexplored. For example, both miR-34a and miR-200c individually suppress the development of different types of cancer, but the cellular effects of their combined actions remain unknown. Here, we show that miR-34a and miR-200c levels are reduced in breast tumors compared to adjacent normal tissues and that this additively predicts poor patient survival. In addition, in cell lines, miR-34a and miR-200c additively induce apoptosis and cell cycle arrest, while also inhibiting proliferation, invasion, migration, stemness and epithelial-to-mesenchymal transition (EMT). Mechanistically, both miRNA-34a and miR-200c directly target HIF1-α and subsequently downregulate VEGFR, MMP9 and CXCR4, although combined miRNA-34a and miR-200c delivery suppresses mouse xenograft tumor development as effectively as individual delivery. We establish a model, supported by in vitro and clinical data, which collectively suggest that the co-delivery of miR-34a and miR-200c represents a promising novel therapeutic strategy for breast cancer patients.

Lung cancer cells and their sensitivity/resistance to cisplatin chemotherapy: Role of microRNAs and upstream mediators

Cisplatin (CP) is a well-known chemotherapeutic agent with excellent clinical effects. The anti-tumor activity of CP has been demonstrated in different cancers such as breast, cervical, reproductive, lung, brain, and prostate cancers. However, resistance of cancer cells to CP chemotherapy has led to its failure in eradication of cancer cells, and subsequent death of patients with cancer. Fortunately, much effort has been put to identify molecular pathways and mechanisms involved in CP resistance/sensitivity. It seems that microRNAs (miRs) are promising candidates in mediating CP resistance/sensitivity, since they participate in different biological aspects of cells such as proliferation, migration, angiogenesis, and differentiation. In this review, we focus on miRs and their regulation in CP chemotherapy of lung cancer, as the most malignant tumor worldwide. Oncogenic miRs trigger CP resistance in lung cancer cells via targeting various pathways such as Wnt/β-catenin, Rab6, CASP2, PTEN, and Apaf-1. In contrast, onco-suppressor miRs inhibit oncogene pathways such as STAT3 to suppress CP resistance. These topics are discussed to determine the role of miRs in CP resistance/sensitivity. We also describe the upstream modulators of miRs such as lncRNAs, circRNAs, NF-κB, SOX2 and TRIM65 and their association with CP resistance/sensitivity in lung cancer cells. Finally, the effect of anti-tumor plant-derived natural compounds on miR expression during CP sensitivity of lung cancer cells is discussed.

LncRNAs and miRNAs participate in determination of sensitivity of cancer cells to cisplatin

Cisplatin is an extensively used chemotherapeutic substance for various types of human malignancies including sarcomas, carcinomas and lymphomas. Yet, the vast application of this drug is hampered by the emergence of chemoresistance in some treated patients. Several mechanisms such as degradation of the membrane transporters by cisplatin have been implicated in the pathogenesis of this event. Recent researches have also indicated the role of long non-coding RNAs (lncRNAs) as well as micoRNAs (miRNAs) in the emergence of resistance to cisplatin in several cancer types. For instance, up-regulation of miR-21 has been associated with resistance to this agent in ovarian cancer, oral squamous cell cancer, gastric malignancy and non-small cell lung cancer (NSCLC). On the other hand, down-regulation of miR-218 has been implicated in emergence of chemoresistance in breast cancer and esophageal squamous cell carcinoma. MALAT1 is implicated in the chemoresistance of bladder cancer cells, NSCLC, gastric cancer and cervical cancer. Most notably, the expression profile of resistance-associated miRNAs and lncRNAs can predict overall survival of cancer patients. Mechanistic assays have revealed that interference with expression of some miRNAs and lncRNAs can reverse the resistance phenotype in cancer cells. In this paper, we review the scientific writings on the role of lncRNAs and miRNAs in the evolution of chemoresistance to cisplatin in cancer cells.

Wnt/β‑catenin signaling: Causes and treatment targets of drug resistance in colorectal cancer (Review)

Colorectal cancer (CRC) is the third most common malignant tumor in humans. Chemotherapy is used for the treatment of CRC. However, the effect of chemotherapy remains unsatisfactory due to drug resistance. Growing evidence has shown that the presence of highly metastatic tumor stem cells, regulation of non-coding RNAs and the tumor microenvironment contributes to drug resistance mechanisms in CRC. Wnt/β-catenin signaling mediates the chemoresistance of CRC in these three aspects. Therefore, the present study analyzed the abundant evidence of the contribution of Wnt/β-catenin signaling to the development of drug resistance in CRC and discussed its possible role in improving the chemosensitivity of CRC, which may provide guidelines for its clinical treatment.

A comparison between the effects of over-expression of miRNA-16 and miRNA-34a on cell cycle progression of mesothelioma cell lines and on their cisplatin sensitivity

The prognosis of patients affected by malignant pleural mesothelioma (MPM) is presently poor and no therapeutic strategies have improved their survival yet. Introduction of miRNA mimics to restore their reduced or absent functionality in cancer cells is considered an important opportunity and a combination of miR's might be even more effective. In the present study, miR-16 and miR-34a were transfected, singularly and in combination, in MPM cell lines H2052 and H28, and their effects on cell proliferation and sensitivity to cisplatin are reported. Interestingly, the overexpression of both miRs, alone or combined, slows down the cell cycle progression, modulates the p53 and HMGB1 expression and increases the sensitivity of cells to cisplatin, producing a marked impairment of cell proliferation and strengthening the apoptotic effect of the drug. However, the co-overexpression of the two miRs results more effective only in the regulation of the cell cycle, but does not enhance the sensitivity of MPM cells to cisplatin. Consequently, although the potential of miR-16 and miR-34a is confirmed, we must conclude that their combination does not improve the response of MPM to chemotherapy.

The role of miR-34 in cancer drug resistance

Resistance to conventional chemotherapy remains a major cause of cancer relapse and cancer-related deaths. Therefore, there is an urgent need to overcome resistance barriers. To improve cancer treatment approaches, it is critical to elucidate the basic mechanisms underlying drug resistance. Increasingly, the mechanisms involving micro-RNAs (miRNAs) are studied because miRNAs are also considered practical therapeutic options due to high degrees of specificity, efficacy, and accuracy, as well as their ability to target multiple genes at the same time. Years of research have firmly established miR-34 as a key tumor suppressor miRNA whose target genes are involved in drug resistance mechanisms. Indeed, numerous articles show that low levels of circulating miR-34 or tumor-specific miR-34 expression are associated with poor response to chemotherapy. In addition, elevation of inherently low miR-34 levels in resistant cancer cells effectively restores sensitivity to chemotherapeutic agents. Here, we review this literature, also highlighting some contradictory observations. In addition, we discuss the potential utility of miR-34 expression as a predictive biomarker for chemotherapeutic drug response. Although caution needs to be exercised, miR-34 is emerging as a biomarker that could improve cancer precision medicine.

Expression of miRNA in 5-FU resistant esophageal cancer

Fluoropyrimidine plus platinum (FP) are chemotherapeutic drugs that are most frequently used to treat esophageal squamous cell carcinoma (ESCC). However, drug resistance often occurs, and the mechanisms of resistance to 5-FU is yet to be determined. The role of micro (mi)RNAs has been well established in a variety of human cancers. The aim of the present study was to investigate the expression profile of ESCC, revealing the differential expression between ESCC and 5-FU resistant ESCC. The establishment of a 5-FU resistant (5-FUR) cell lines model provides a way of analyzing the expression of miRNAs in drug resistance. The miRNA expression indicated 50 miRNAs that were upregulated in TE10-5-FUR compared with TE10, while 119 miRNAs were downregulated. The TE11-5-FUR demonstrated 140 miRNAs were upregulated compared with TE11, which exhibited 12 downregulated miRNAs. Both cell lines share the 2 candidate upregulated miRNAs (miR-146a and miR-483-5p) and 5 downregulated miRNAs (miR-34a, miR-141, miR-200b, miR-200c and miR-205). Further studies are required to analyze and evaluate the function of the miRNAs.

Combined Replenishment of miR-34a and let-7b by Targeted Nanoparticles Inhibits Tumor Growth in Neuroblastoma Preclinical Models

Neuroblastoma (NB) tumor substantially contributes to childhood cancer mortality. The design of novel drugs targeted to specific molecular alterations becomes mandatory, especially for high-risk patients burdened by chemoresistant relapse. The dysregulated expression of MYCN, ALK, and LIN28B and the diminished levels of miR-34a and let-7b are oncogenic in NB. Due to the ability of miRNA-mimics to recover the tumor suppression functions of miRNAs underexpressed into cancer cells, safe and efficient nanocarriers selectively targeted to NB cells and tested in clinically relevant mouse models are developed. The technology exploits the nucleic acids negative charges to build coated-cationic liposomes, then functionalized with antibodies against GD₂ receptor. The replenishment of miR-34a and let-7b by NB-targeted nanoparticles, individually and more powerfully in combination, significantly reduces cell division, proliferation, neoangiogenesis, tumor growth and burden, and induces apoptosis in orthotopic xenografts and improves mice survival in pseudometastatic models. These functional effects highlight a cooperative down-modulation of MYCN and its down-stream targets, ALK and LIN28B, exerted by miR-34a and let-7b that reactivate regulatory networks leading to a favorable therapeutic response. These findings demonstrate a promising therapeutic efficacy of miR-34a and let-7b combined replacement and support its clinical application as adjuvant therapy for high-risk NB patients.

Decitabine and all-trans retinoic acid synergistically exhibit cytotoxicity against elderly AML patients via miR-34a/MYCN axis

This study aimed to investigate the efficacy and mechanism of decitabine (DAC) and all-trans retinoic acid (ATRA) in elderly acute myeloid leukemia (AML) patients and cultured cells. Our clinical trial enrolled 36 elderly patients who were judged ineligible for conventional chemotherapy, receiving DAC and ATRA regimen (DAC 20 mg/m² days 1-5; ATRA 20 mg/m² days 4-28 in the first cycle and days 1-28 in the subsequent cycle). Treated with a median of 3 cycles (range 1-6), 44.4 % of patients achieved complete remission (CR), 11.1 % achieved CR with incomplete peripheral count recovery (CRi) and 13.9 % achieved partial remission (PR). The median overall survival (OS) was 12.1 months; the 1-year and 2-year OS rates were 49.6 % and 17.2 %. In addition, our in vitro studies indicated that the antineoplastic activities of DAC and ATRA mutually reinforced, which induced growth inhibition, cell cycle arrest and apoptosis of AML cells. Meanwhile, we found DAC and ATRA inhibited DNMT1, activated miR-34a via promoter hypomethylation, down-regulated its target MYCN and thus exerted a synergistic antineoplastic effect. In conclusion, DAC plus ATRA regimen might be effective and well-tolerated for elderly patients partially through modulating miR-34a/MYCN axis.

Multiple Copies in T-Cell Malignancy 1 (MCT-1) Promotes the Stemness of Non-Small Cell Lung Cancer Cells via Activating Interleukin-6 (IL-6) Signaling through Suppressing MiR-34a Expression

Background

Although the oncogenic roles of multiple copies in T-cell malignancy 1 (MCT-1) have been revealed in multiple cancers, its effects on non-small cell lung cancer (NSCLC) progression are still uncertain. This study aimed to reveal the effects of MCT-1 on the stem cell-like traits of NSCLC cells.

Material/Methods

Western blot, real-time quantitative polymerase chain reaction (RT-qPCR), spheroid forming ability, and ALDH1 (aldehyde dehydrogenase 1) activity analysis were carried out to examine the effects of MCT-1/micrRNa-34 (miR-34a)/interleukin-6 (IL-6) on the stem cell-like characteristics of lung cancer cells.

Results

MCT-1 knockdown reduced the spheroid forming ability, characterized as the decreased spheroid size and number. Additionally, MCT-1 knockdown decreased the expression of the NSCLC stemness markers and the activity of ALDH1. Moreover, MCT-1 knockdown decreased IL-6 secretion that promotes NSCLC cell stemness. Furthermore, MCT-1 knockdown increased the level of miR-34a, which attenuated the stemness of NSCLC cells through targeting IL-6R (IL-6 receptor) expression.

Conclusions

These results suggest MCT-1/miR-34a/IL-6/IL-6R axis is responsible for MCT-1-mediated effects on NSCLC cell stemness.

c-Myc Acts as a Competing Endogenous RNA to Sponge miR-34a, in the Upregulation of CD44, in Urothelial Carcinoma

MicroRNAs (miRNAs) have been shown to play a crucial role in the progression of human cancers, including urothelial carcinoma (UC), the sixth-most common cancer in the world. Among them, miR-34a has been implicated in the regulation of cancer stem cells (CSCs); however, its role in UC has yet to be fully elucidated. In this study, bioinformatics and experimental analysis confirmed that miR-34a targets CD44 (a CSC surface marker) and c-Myc (a well-known cell cycle regulator) in UC. We found that, surprisingly, most UC cell lines and patient samples did express miR-34a, although epigenetic silencing by promoter hypermethylation of miR-34a expression was observed only in UMUC3 cells, and a subset of patient samples. Importantly, overexpression of c-Myc, a frequently amplified oncogene in UC, was shown to upregulate CD44 expression through a competing endogenous RNA (ceRNA) mechanism, such that overexpression of the c-Myc 3'UTR upregulated CD44, and vice versa. Importantly, we observed a positive correlation between the expression of c-Myc and CD44 in clinical samples obtained from UC patients. Moreover, overexpression of a dominant-negative p53 mutant downregulated miR-34a, but upregulated c-Myc and CD44, in UC cell lines. Functionally, the ectopic expression of miR-34a was shown to significantly suppress CD44 expression, and subsequently, suppression of cell growth and invasion capability, while also reducing chemoresistance. In conclusion, it appears that aberrant promoter methylation, and c-Myc-mediated ceRNA mechanisms, may attenuate the function of miR-34a, in UC. The tumor suppressive role of miR-34a in controlling CSC phenotypes in UC deserves further investigation.

Low‑intensity ultrasound enhances the chemosensitivity of hepatocellular carcinoma cells to cisplatin via altering the miR‑34a/c‑Met axis

Recently, the use of low-intensity ultrasound (LIUS) combined with chemotherapeutic agents is widely used in clinical practice, mainly for the treatment of cancer; however, the mechanisms as to how LIUS enhances the antitumor effects of these agents are not fully understood. The aim of the present study was to explore the synergistic antitumor effects and mechanisms of cisplatin (DDP) combined with LIUS (LIUS-DDP) in hepatocellular carcinoma (HCC). We reported that LIUS effectively enhanced Huh7 and HCCLM3 cell sensitivity to a low concentration of DDP. Reverse transcription-quantitative polymerase chain reaction analysis revealed that LIUS could increase the expression of microRNA-34a (miR-34a) in HCC cells following DDP treatment. In addition, LIUS-DDP significantly increased intracellular reactive oxygen species (ROS) levels in vitro, and the upregulation of miR-34a induced by LIUS-DDP was reversed by the ROS scavenger N-acetylcysteine, suggesting that LIUS upregulates the expression of miR-34a via production of ROS. In addition, knockdown of miR-34a in HCC cells significantly suppressed the synergistic effects of LIUS-DDP treatment. Conversely, overexpression of miR-34a enhanced these synergistic effects. The results of a dual-luciferase assay indicated that c-Met, a well-known oncogene, was a target of miR-34a. We also determined that LIUS-DDP treatment inhibited the expression of c-Met, possibly due to increased ROS production, which upregulated miR-34a expression. Furthermore, overexpression of c-Met reversed the synergistic effects of LIUS-DDP treatment. Our findings suggest that LIUS could enhance the chemosensitivity of HCC cells to DDP by altering the miR-34a/c-Met axis. Therefore, DDP combined with LIUS may be a potential therapeutic application for the clinical treatment of patients with HCC.

Evaluation of the diagnostic and therapeutic roles of non-coding RNA and cell proliferation related gene association in hepatocellular carcinoma

Micro RNA-34a-5p (miR-34a-5p) is an important molecule that can act as a modulator of tumor growth. It controls expression of a plenty of proteins controlling cell cycle, differentiation and apoptosis and opposing processes that favor viability of cancer cells, their metastasis and resistance to chemotherapy. Bioinformatics analysis indicated that minichromosome maintenance protein 2 (MCM2) is a target gene of miR-34a-p. In this study, RT-qPCR was employed to detect the expression of miR-34a-5p and MCM2 in 10 hepatocellular carcinoma (HCC) tissues. The functional role of miR-34a-5p in HCC was investigated and the interaction between miR-34a-5p and MCM2 was explored. Results showed miR-34a-5p expression in HCC tissues was significantly lower than in non HCC liver tissues (P < 0.05), but MCM2 expression in HCC tissues was markedly higher than in non HCC liver tissues (P < 0.05). In addition, miR-34a-5p expression was negatively related to MCM2 expression. To confirm effect of miR-34a-5p on tumor growth and its possible effect on MCM2, miR-34a-5p mimic and inhibitor was transfected into HCC cell lines (HepG2). MTS assay, showed miR-34a-5p over-expression could inhibit the proliferation of HCC cells. RT-qPCR was done to detect the expression of miR-34a-5p and MCM2 in HepG2 cells before and after transfection. Results showed that MCM2 expression in HCC tissues was markedly lower in mimic transfected group than in inhibitor transfected group and control group (P < 0.05) while miR-34a-5p expression in HepG2 cells was significantly higher in mimic transfected group than in inhibitor transfected group and control group (P < 0.05). Thus, miR-34a-5p may inhibit the proliferation of HCC cells via regulating MCM2 expression. These findings provide an evidence for the emerging role of microRNAs as diagnostic markers and therapeutic targets in HCC.

Extremely Low Organ Toxicity and Strong Antitumor Activity of miR-34-Regulated Oncolytic Coxsackievirus B3

Oncolytic virotherapies have emerged as new modalities for cancer treatment. We previously reported that coxsackievirus B3 (CVB3) is a novel oncolytic virus (OV) with a strong ability to lyse human non-small cell lung cancer cells; however, its non-specific toxicity against normal cells remains to be resolved. To improve its safety profile, microRNA target sequences complementary to miR-34a/c, which is expressed preferentially in normal cells, were inserted into the 5′ UTR or 3′ UTR of the CVB3 genome. In the presence of miR-34a/c, the gene-modified CVB3 could not replicate in normal cells. We also found that the pathogenicity of CVB3 was reduced to a greater extent by targeting miR-34a than miR-34c; in addition, it was more effective to insert the target sequences into the 3′ UTR rather than the 5′ UTR of the viral genome. Ultimately, we developed a double-miR-34a targeting virus (53a-CVB) by inserting miR-34a targets in both the 5′ UTR and 3′ UTR of the virus. 53a-CVB was minimally toxic to cells in normal tissue, but maintained nearly its full oncolytic activity in mice xenografted with human lung cancer. 53a-CVB is the first miR-34-regulated OV and represents a promising platform for the development of safe and effective anti-cancer therapies.

LIMD2 targeted by miR‑34a promotes the proliferation and invasion of non‑small cell lung cancer cells

A previous study indicated that LIM domain containing 2 (LIMD2) is an oncogene in a variety of human cancers, including breast, bladder and thyroid cancers, and melanoma; however, the role of LIMD2 in non‑small cell lung cancer (NSCLC) remains largely unknown. In the present study, by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis, it was demonstrated that LIMD2 was significantly upregulated in NSCLC tissues compared with adjacent normal tissues. Consistently, LIMD2 was also upregulated in NSCLC cell lines. Furthermore, the present study reported that knockdown of LIMD2 significantly inhibited the proliferation and invasion of H1299 and A549 cells by Cell Counting Kit‑8 and Transwell assays. In addition, the expression of LIMD2 was determined to be regulated by microRNA (miR)‑34a in the present study. RT‑qPCR and western blot analysis indicated that overexpression of miR‑34a notably reduced the mRNA and protein expression levels of LIMD2 in H1299 and H549 cells. Additionally, the present study reported an inverse correlation between the expression of LIMD2 and miR‑34a in NSCLC tissues. A luciferase reporter assay also demonstrated that miR‑34a directly targeted the mRNA expression of LIMD2 in NSCLC cells. Finally, miR‑34a was revealed to possess a tumor suppressive role in NSCLC cells. Collectively, the results of the present study revealed that LIMD2 promoted NSCLC progression and was regulated by miR‑34a.

The Network of Non-coding RNAs in Cancer Drug Resistance

Non-coding RNAs (ncRNAs) have been implicated in most cellular functions. The disruption of their function through somatic mutations, genomic imprinting, transcriptional and post-transcriptional regulation, plays an ever-increasing role in cancer development. ncRNAs, including notorious microRNAs, have been thus proposed to function as tumor suppressors or oncogenes, often in a context-dependent fashion. In parallel, ncRNAs with altered expression in cancer have been reported to exert a key role in determining drug sensitivity or restoring drug responsiveness in resistant cells. Acquisition of resistance to anti-cancer drugs is a major hindrance to effective chemotherapy and is one of the most important causes of relapse and mortality in cancer patients. For these reasons, non-coding RNAs have become recent focuses as prognostic agents and modifiers of chemo-sensitivity. This review starts with a brief outline of the role of most studied non-coding RNAs in cancer and then highlights the modulation of cancer drug resistance via known ncRNAs based mechanisms. We identified from literature 388 ncRNA-drugs interactions and analyzed them using an unsupervised approach. Essentially, we performed a network analysis of the non-coding RNAs with direct relations with cancer drugs. Within such a machine-learning framework we detected the most representative ncRNAs-drug associations and groups. We finally discussed the higher integration of the drug-ncRNA clusters with the goal of disentangling effectors from downstream effects and further clarify the involvement of ncRNAs in the cellular mechanisms underlying resistance to cancer treatments.

MicroRNA in lung cancer: role, mechanisms, pathways and therapeutic relevance

Lung cancer is the cardinal cause of cancer-related deaths with restricted recourse of therapy throughout the world. Clinical success of therapies is not very promising due to - late diagnosis, limited therapeutic tools, relapse and the development of drug resistance. Recently, small ∼20-24 nucleotides molecules called microRNAs (miRNAs) have come into the limelight as they play outstanding role in the process of tumorigenesis by regulating cell cycle, metastasis, angiogenesis, metabolism and apoptosis. miRNAs essentially regulate gene expression via post-transcriptional regulation of mRNA. Nevertheless, few studies have conceded the role of miRNAs in activation of gene expression. A large body of data generated by numerous studies is suggestive of their tumor-suppressing, oncogenic, diagnostic and prognostic biomarker roles in lung cancer. They have also been implicated in regulating cancer cell metabolism and resistance or sensitivity towards chemotherapy and radiotherapy. Further, miRNAs have also been convoluted in regulation of immune checkpoints - Programmed death 1 (PD-1) and its ligand (PD-L1). These molecules play a significant role in tumor immune escape leading to the generation of a microenvironment favouring tumor growth and progression. Therefore, it is imperative to explore the expression of miRNA and understand its relevance in lung cancer and development of anti-cancer strategies (anti - miRs, miR mimics and micro RNA sponges). In view of the above, the role of miRNA in lung cancer has been dissected and the associated mechanisms and pathways are discussed in this review.

miR-34a Regulates Multidrug Resistance via Positively Modulating OAZ2 Signaling in Colon Cancer Cells

Although aberrant expression of miR-34a, an essential tumor suppressor miRNA, has been frequently observed in colon cancer (CCa), whether miR-34a can regulate CCa progression by modulating other facets of this malignancy (such as multidrug resistance, MDR) remains unknown. Here, we report for the first time that miR-34a expression was significantly downregulated in clinical CCa samples from oxaliplatin-resistant patients and in experimentally established multidrug-resistant CCa cells. By using histoculture drug response assay, we further confirmed that clinical CCa samples with lower miR-34a expression appeared to be more resistant to chemotherapy. Functionally, ectopic expression of exogenous miR-34a resensitized multidrug-resistant HCT-8/OR cells to oxaliplatin treatment, whereas miR-34a inhibition augmented the oxaliplatin resistance in chemosensitive HCT-8 cells. Mechanistically, miR-34a positively regulated the mRNA stability of the ornithine decarboxylase antizyme 2 (OAZ2) by directly targeting its three prime untranslated region (3′UTR). Consequently, suppression of the expression of miR-34a/OAZ2 signaling by chemotherapeutic agents significantly enhanced the activation of MDR-associated ATP-binding cassette (ABC) transporters and antiapoptosis pathways, thus leading to MDR development in CCa cells. Collectively, our combined analysis reveals a critical role of miR-34a/OAZ2 cascade in conferring a proper cellular response to CCa chemotherapy.

Shikonin-mediated up-regulation of miR-34a and miR-202 inhibits retinoblastoma proliferation

Retinoblastoma (RB) is an ocular tumor that occurs mainly in children. The pathogenesis of RB is not well understood, and its treatment strategies are very limited. Shikonin is widely reported as an anti-tumor agent. However, its effect on RB is still unknown. MTT assay was performed to detect the proliferation ability of two RB cell lines, Y-79 and WERI-Rb-1, upon treatment with Shikonin. Colony formation assay was conducted to examine the clonogenic ability of Shikonin-treated cells. Real-time PCR and western blotting were performed for expression analysis of miRNAs and MYCN, respectively. Luciferase activity assay was conducted to test the inhibition mechanism of miR-34a and miR-202 on MYCN. Shikonin could effectively inhibit the proliferation of RB cells and upregulate the expressions of miR-34a and miR-202. MiR-34a and miR-202 could directly target the mRNA degradation of oncogene MYCN, and the inhibitory effect of Shikonin was largely weakened by restoring the MYCN protein expression. Shikonin-mediated up-regulation of miR-34a and miR-202 inhibits RB proliferation, partially mediated through MYCN.

MicroRNA‑34a inhibits liver cancer cell growth by reprogramming glucose metabolism

MicroRNAs (miRs) have been proposed as minimally invasive prognostic markers for various types of cancer, including liver cancer, which is one of the most common cancers worldwide. In the present study, the expression of miR-34a in human liver cancer tissues and cell lines was evaluated and the effects of miR-34a on cell proliferation, invasion and glycolysis in hepatocellular carcinoma (HCC) cells were determined. The results indicated that miR-34a was downregulated in human liver cancer tissues. Overexpression of miR-34a significantly inhibited liver cancer cell proliferation and clone formation. In terms of the underlying mechanism, miR-34a was indicated to negatively regulate the expression of lactate dehydrogenase A (LDHA), which consequently inhibited LDHA-dependent glucose uptake in the cancer cells, as well as cell proliferation and invasion. Collectively, these data suggest that miR-34a functions as a negative regulator of glucose metabolism and may serve as a novel marker for liver cancer prognosis.

Network analysis of microRNAs, genes and their regulation in diffuse and follicular B-cell lymphomas

MicroRNAs (miRs) are short non-coding regulatory RNAs that control gene expression at the post-transcriptional level and play an important role in cancer development and progression, acting either as oncogenes or as tumor suppressors. Identification of aberrantly expressed miRs in patients with hematological malignancies as compared to healthy individuals has suggested that these molecules may serve as novel clinical diagnostic and prognostic biomarkers.

We conducted a systematic literature review of articles published between 2007 and 2017 and re-analyzed experimentally-validated human miR expression signatures in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) from various biological sources (tumor tissue, peripheral blood, bone marrow and cell lines). A unique miR expression pattern was observed for each disease. Compared to healthy individuals, 61 miRs were aberrantly expressed in DLBCL and 85 in FL; 20-30% of aberrantly expressed miRs overlapped between the two lymphoma subtypes.

Analysis of integrative positive and negative miRNA-mRNA relationships using the Ingenuity Pathway Analysis (IPA) system revealed 970 miR-mRNA pairs for DLBCL and 90 for FL. Through gene ontology analysis, we found potential regulatory pathways that are deregulated in DLBCL and FL due to improper expression of miR target genes. By comparing the expression level of the aberrantly expressed miRs in DLBCL to their expression levels in other malignancies, we identified seven miRs that are aberrantly expressed in DLBCL tumor tissues (miR-15a, miR-16, miR-17, miR-106, miR-21, miR-155 and miR-34a-5p). This specific expression pattern may be a potential diagnostic tool for DLBCL.

PAI-1/PIAS3/Stat3/miR-34a forms a positive feedback loop to promote EMT-mediated metastasis through Stat3 signaling in Non-small cell lung cancer

AIM

This study intented to clarify the intracellular effect of PAI-1 on Non-small cell lung cancer (NSCLC) metastasis and the precise mechanism involved.

METHODS

The metastatic properties of NSCLC cells were determined by transwell assays and wound-healing assay in vitro. The mRNA and protein expressions of genes were analyzed by Real-time qPCR and western blot, respectively. Pulmonary metastasis model of NSCLC cells was established to evaluate the pro-metastasis effect of PAI-1 and anti-metastatic effect of miR-34a in vivo. The gene targets of miR-34a were confirmed by luciferase reporter assays. Chromatin immunoprecipitation assay was employed to detect the transcriptional regulation of miR-34a. Co-immunoprecipitation assay was performed to observe the interaction of proteins.

RESULTS

PAI-1, which was elevated in NSCLC patients with recurrence and metastasis, augmented NSCLC metastasis and was negatively related to the prognosis of NSCLC. miR-34a, which was decreased in NSCLC patients with metastasis, attenuated NSCLC metastasis and was positively correlated with the prognosis of NSCLC. Moreover, PAI-1 was identified as the target gene of miR-34a and activated the Stat3 signaling pathway to promote epithelial-mesenchymal transition (EMT) in NSCLC cells. PAI-1 interacted with PIAS3 to regulate Stat3-dependent gene expression and miR-34a was transcriptionally suppressed by Stat3 to form a positive regulatory loop through Stat3 signaling.

CONCLUSION

Our findings suggest that PAI-1 and miR-34a, which can be clinically utilized as biomarkers for the clinical prognosis or diagnosis of NSCLC, are potential targets for the treatment of NSCLC.

Predictive relevance of miR-34a, miR-224 and miR-342 in patients with advanced squamous cell carcinoma of the lung undergoing palliative chemotherapy

Attributing to their pathophysiological role and stability in biological samples, microRNAs (miRNAs) have the potential to become valuable predictive markers for non-small cell lung cancer (NSCLC). Samples of biopsy tissue constitute suitable material for miRNA profiling with the aim of predicting the effect of palliative chemotherapy. The present study group included 81 patients (74 males, 7 females, all smokers or former smokers) with the squamous cell carcinoma (SCC) histological subtype of NSCLC at a late stage (3B or 4). All patients received palliative chemotherapy based on platinum derivatives in combination with paclitaxel or gemcitabine. The expression of 17 selected miRNAs was measured by reverse transcription-quantitative polymerase chain reaction in tumor tissue macrodissected from formalin-fixed paraffin-embedded (FFPE) tissue samples. To predict the effect of palliative chemotherapy, the association between gene expression levels and overall survival (OS) time was analyzed. From the 17 miRNAs of interest, low expression levels of miR-342 and high expression levels of miR-34a and miR-224 were associated with a reduced OS time in subgroups of patients based on smoking status and treatment modality. Using cluster analysis, associations between combinations of miR-34a, -224 and -342 expression levels with patient survival were identified. The present study revealed that patients with the simultaneous high expression of miR-224 and -342 had a similar prognostic outcome to those with the low expression of miR-224 and -342, which was significantly reduced, compared with patients exhibiting high expression of either miR-224 or miR-342 with low expression of the other. We hypothesize that the effect of a particular miRNA is dependent on the expression level of other members of the miRNA network. This finding appears to complicate survival analyses based on individual miRNAs as markers. In conclusion, the present study provides evidence that specific miRNAs were associated with OS time, which may be candidate predictors for the effectiveness of palliative treatment in SCC lung cancer patients. This objective can be better achieved by combining more markers together than by using individual miRNAs.

The MYCN Protein in Health and Disease

MYCN is a member of the MYC family of proto-oncogenes. It encodes a transcription factor, MYCN, involved in the control of fundamental processes during embryonal development. The MYCN protein is situated downstream of several signaling pathways promoting cell growth, proliferation and metabolism of progenitor cells in different developing organs and tissues. Conversely, deregulated MYCN signaling supports the development of several different tumors, mainly with a childhood onset, including neuroblastoma, medulloblastoma, rhabdomyosarcoma and Wilms’ tumor, but it is also associated with some cancers occurring during adulthood such as prostate and lung cancer. In neuroblastoma, MYCN-amplification is the most consistent genetic aberration associated with poor prognosis and treatment failure. Targeting MYCN has been proposed as a therapeutic strategy for the treatment of these tumors and great efforts have allowed the development of direct and indirect MYCN inhibitors with potential clinical use.