miR-508-5p regulates multidrug resistance of gastric cancer by targeting ABCB1 and ZNRD1

Mechanism of cisplatin resistance in gastric cancer and associated microRNAs

Gastric cancer (GC) is a common malignant tumor with high morbidity and mortality rates that seriously affects human health worldwide. Although surgery is currently the preferred clinical treatment for GC, chemotherapy remains the first choice for perioperative treatment, adjuvant therapy, and palliative care for patients with advanced GC. Cisplatin (DDP) is an antineoplastic agent that has been used clinically for decades, and it is the first-line chemotherapy for many solid tumors. However, the therapeutic efficacy of DDP is often limited by resistance and the complexity of its resistance mechanisms, which involve multiple proteins and signaling pathways. It is well documented that a variety of microRNAs (miRNAs) differentially expressed in DDP-resistant GC cells play important roles in regulating or reversing DDP resistance via various pathways. In this review, we first provide an introduction to the cytotoxicity and major resistance mechanisms of DDP in GC and then discuss the role and mechanism of miRNAs in regulating the DDP resistance process in GC cells. This work demonstrates the potential of relevant miRNAs to become diagnostic and prognostic biomarkers for gastric cancer and targets of action to enhance chemosensitivity and provides directions for future research.

microRNA-301b-3p from mesenchymal stem cells-derived extracellular vesicles inhibits TXNIP to promote multidrug resistance of gastric cancer cells

OBJECTIVE

MicroRNAs (miRNAs) from mesenchymal stem cells (MSC)-derived extracellular vesicles (MSCs-EVs), including exosomes, are known to participate in different diseases. However, the function of miR-301b-3p from MSCs-EVs on the chemoresistance of gastric cancer (GC) cells remains poorly characterized. Thus, we aim to explore the role of MSCs-EVs-derived miR-301b-3p in multidrug resistance of GC cells.

METHODS

Cisplatin (DDP)/vincristine (VCR)-resistant and sensitive GC clinical samples were harvested to detect expression of miR-301b-3p and thioredoxin interacting protein (TXNIP). MSCs were respectively transfected with miR-301b-3p oligonucleotides and/or TXNIP plasmids to extract the EVs, which were then co-cultured with multidrug-resistant GC cells. Then, P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP), IC50, proliferation, migration, and apoptosis of resistant GC cells were determined. The tumor growth was observed in nude mice. Targeting relationship between miR-301b-3p and TXNIP was confirmed.

RESULTS

miR-301b-3p was upregulated, and TXNIP was downregulated in DDP/VCR-resistant GC tissues and cells. MSC-EVs induced drug resistance, proliferation, and migration and inhibited apoptosis of DDP/VCR-resistant GC cells in vitro, as well as facilitated tumor growth in vivo. Inhibition of miR-301b-3p or upregulation of TXNIP reversed the promoting effect of MSC-EVs on DDP/VCR resistant GC cells to DDP/VCR resistance and malignant behaviors. The effects of MSC-EVs carrying miR-301b-3p inhibition on DDP/VCR-resistant GC cells were reversed by TXNIP downregulation. TXNIP was confirmed as a target gene of miR-301b-3p.

CONCLUSION

miR-301b-3p from MSCs-EVs inhibits TXNIP to promote multidrug resistance of GC cells, providing a novel insight for chemotherapy in GC.

Role of non-coding RNAs as new therapeutic targets in regulating the EMT and apoptosis in metastatic gastric and colorectal cancers

Colorectal cancer (CRC) and gastric cancer (GC), are the two most common cancers of the gastrointestinal tract, and are serious health concerns worldwide. The discovery of more effective biomarkers for early diagnosis, and improved patient prognosis is important. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), can regulate cellular processes such as apoptosis and the epithelial-mesenchymal transition (EMT) leading to progression and resistance of GC and CRC tumors. Moreover these pathways (apoptosis and EMT) may serve as therapeutic targets, to prevent metastasis, and to overcome drug resistance. A subgroup of ncRNAs is common to both GC and CRC tumors, suggesting that they might be used as biomarkers or therapeutic targets. In this review, we highlight some ncRNAs that can regulate EMT and apoptosis as two opposite mechanisms in cancer progression and metastasis in GC and CRC. A better understanding of the biological role of ncRNAs could open up new avenues for the development of personalized treatment plans for GC and CRC patients.

miR-508-5p serves as an anti-oncogene by targeting S100A16 to regulate AKT signaling and epithelial-mesenchymal transition process in lung adenocarcinoma cells

BACKGROUND

Our aim was to expose the effect of miR-508-5p on the developmental and biological behaviour of lung adenocarcinoma (LUAC).

METHODS

The KM plotter was used to analyze the survival significance of miR-508-5p and S100A16 expression in LUAC patients. qRT-PCR was performed to detect the expression of miR-508-5p and S100A16 in LUAC tissue and LUAC cell lines. CCK8, colony formation and Transwell were performed to evaluate the effects of miR-508-5p and S100A16 on cell proliferation and metastasis. Dual luciferase reporter assay was used to verify that S100A16 were targets of miR-508-5p. Western blot analysis was performed to analyze protein expression.

RESULTS

Results showed that low miR-508-5p expression in LUAC tissues indicated poorer overall survival of LUAC patients and miR-508-5p was downregulated in LUAC cell lines compared to the normal human lung epithelial cell line. miR-508-5p mimics could inhibit A549 cell proliferation and metastasis abilities, while miR-508-5p Antagomir showed the opposite effect. We identified S100A16 as one direct target of miR-508-5p, and rescuing S100A16 expression could reverse the effect of miR-508-5p mimics on A549 cell proliferation and metastasis. miR-508-5p could involve the coordination of AKT signaling and epithelial-mesenchymal transition (EMT) progress using western-blot assays and rescuing S100A16 expression could reverse the inhibited AKT signaling and EMT progress induced by miR-508-5p mimics.

CONCLUSIONS

We found that miR-508-5p targeted S100A16 to regulate AKT signaling and EMT progress in A549 cells, resulting in impaired cell proliferation and metastasis activity, suggesting that miR-508-5p might be a promising therapeutic target and an important diagnostic and prognostic marker for improved LUAC therapeutic schedule.

Restoration of miR-648 overcomes 5-FU-resistance through targeting ET-1 in gastric cancer cells in-vitro

BACKGROUND

Endothelin-1 (ET-1) is a peptide overexpressed in gastric cancer (GC) and linked to carcinogenesis and resistance to chemotherapy. Applying microRNAs (miRNAs/miRs) to downregulate ET-1 and reverse resistance to commonly used chemotherapy drugs such as 5-fluorouracil (5-FU) is practical.

METHODS

The current study sought to evaluate the miR-648 expression in GC and any plausibility of its replacement, either with or without the combination of chemo agents to downregulate ET-1 expression through interaction with its target gene. To this end, miR-648 and ET-1 expression levels were assessed in GC tissues and adjacent non-tumor tissues driven from 65 patients who had already undergone surgery, fifteen of which had received 5-FU before surgery. The impact of miR-648 and chemo agents on ET-1 expression was measured using qPCR and Western blotting. Further, an MTT assay was conducted to assess its association with cell viability. Ultimately, the association of miR-648 and ET-1 with clinicopathological characteristics was evaluated.

RESULTS

The current study revealed that miR-648 was considerably down-regulated, while ET-1 was substantially up-regulated in patients with GC. The 5-FU caused a significant increase in miR-648 and reduced ET-1 expression. It was also determined that overexpression of miR-648 suppressed ET-1 production, notably when combined with 5-FU, leading to survival reduction. These results further showed that miR-648 replacement could sensitize chemoresistant GC cells. Besides, a significant association between ET-1 and miR-648 with clinicopathological features was discovered CONCLUSIONS: miR-648 replacement may serve as a potential oncosuppressive therapeutic approach that warrants further investigation to translate into an effective GC treatment.

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

PITPNA-AS1/miR-98-5p to Mediate the Cisplatin Resistance of Gastric Cancer

Gastric cancer (GC) is the most deadly gastrointestinal malignancy with high incidence and mortality. Although, molecular mechanisms which drive gastric cancer progression are extensively investigated, the roles of long noncoding RNA (lncRNA) in gastric cancer growth and drug sensitivity remain unclear. Platinum is a mainstay to treat gastric cancer, and platinum resistance always leads to the local recurrence of gastric cancer. Therefore, it is important to identify biomarkers or therapeutic targets to sensitize gastric cancer to platinum. In this study, we employ noncoding RNA sequencing and found that lncRNA PITPNA-AS1 is overexpressed in gastric cancer tissues and associated with poor survival of gastric cancer patients. Kockdown of PITPNA-AS1 in gastric cancer cells significantly inhibited cell growth and triggered apoptotic cell death in gastric cancer cells. Also, cisplatin treatment could decrease PITPNA-AS1 levels in gastric cancer cells through inhibiting H3K27ac. Besides, PITPNA-AS1 is elevated in cisplatin-resistant gastric cancer cells and tissues, PITPNA-AS1 knockdown could sensitize gastric cancer cells to cisplatin treatment. Furthermore, we identified that PITPNA-AS1 directly interacts and inhibits miR-98-5p. Therefore, PITPNA-AS1 could be served as a potential biomarkers and curative therapeutic targets for gastric cancer progression.

Novel biomarkers of microRNAs in gastric cancer; an overview from diagnosis to treatment

The fourth frequent disease in the world and the second cause of cancer-related death is gastric cancer (GC). In this way, over 80% of diagnoses are made in the middle to advanced degrees of the disease, underscoring the requirement for innovative biomarkers that can be identified quickly. Meaningly, biomarkers that can complement endoscopic diagnosis and be used to detect patients with a high risk of GC are desperately needed. These biomarkers will allow for the accurate prediction of therapy response and prognosis in GC patients, as well as the development of an optimal treatment strategy for each individual. Conspicoiusly, microRNAs (miRNAs) and small noncoding RNA regulates the expression of target mRNA and thereby modifies critical biological mechanisms. According to the data, abnormally miRNAs expression in GC is linked to tumor growth, carcinogenesis, aggression and distant metastasis. Importantly, miRNA expression patterns and next-generation sequencing (NGS) can also be applied to analyze kinds of tissues and cancers. Given the high death rates and poor prognosis of GC, and the absence of a clinical diagnostic factor that is adequately sensitive to GC, research into novel sensitive and specific markers for GC diagnosis is critical. In this review,we evaluate the latest research findings that suggest the feasibility and clinical utility of miRNAs in GC.

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

The Roles of microRNAs in Cancer Multidrug Resistance

Simple Summary

The resistance of neoplastic cells to multiple drugs is a serious problem in cancer chemotherapy. The molecular causes of multidrug resistance in cancer are largely known, but less is known about the mechanisms by which cells deliver phenotypic changes that resist the attack of anticancer drugs. The findings of RNA interference based on microRNAs represented a breakthrough in biology and pointed to the possibility of sensitive and targeted regulation of gene expression at the post-transcriptional level. Such regulation is also involved in the development of multidrug resistance in cancer. The aim of the current paper is to summarize the available knowledge on the role of microRNAs in resistance to multiple cancer drugs.

Abstract

Cancer chemotherapy may induce a multidrug resistance (MDR) phenotype. The development of MDR is based on various molecular causes, of which the following are very common: induction of ABC transporter expression; induction/activation of drug-metabolizing enzymes; alteration of the expression/function of apoptosis-related proteins; changes in cell cycle checkpoints; elevated DNA repair mechanisms. Although these mechanisms of MDR are well described, information on their molecular interaction in overall multidrug resistance is still lacking. MicroRNA (miRNA) expression and subsequent RNA interference are candidates that could be important players in the interplay of MDR mechanisms. The regulation of post-transcriptional processes in the proteosynthetic pathway is considered to be a major function of miRNAs. Due to their complementarity, they are able to bind to target mRNAs, which prevents the mRNAs from interacting effectively with the ribosome, and subsequent degradation of the mRNAs can occur. The aim of this paper is to provide an overview of the possible role of miRNAs in the molecular mechanisms that lead to MDR. The possibility of considering miRNAs as either specific effectors or interesting targets for cancer therapy is also analyzed.

LOC102724163 promotes breast cancer cell proliferation and invasion by stimulating MUC19 expression

Breast cancer (BC) is a malignant disease and the most commonly diagnosed cancer in women. Numerous studies have previously verified the important role of long non-coding RNAs in a number of biological processes in BC. In the present study, analysis of The Cancer Genome Atlas database and reverse transcription-quantitative PCR demonstrated that LOC102724163 expression levels were significantly upregulated in BC tissues compared to matched adjacent normal tissues and were associated with an unfavorable prognosis in patients with BC. Gain or loss of function assays indicated that overexpression of LOC102724163 significantly increased tumorgenicity in vivo and cell migration, proliferation and invasion in vitro. In the mechanistical aspect, LOC102724163 sponged microRNA (miR)-508-5p to elevate MUC19 expression. Additionally, rescue assays ascertained the function of the LOC102724163/miR-508-5p/MUC19 axis in the proliferation and invasion of BC cells. To the best of our knowledge, this is the first study to have demonstrated that LOC102724163 may act as a competing endogenous RNA to control MUC19 expression levels by competitively sponging miR-508-5p to modulate BC progression. Therefore, the present study has provided new insights into BC diagnosis and treatment.

Mechanisms of Action And Clinical Implications of MicroRNAs in the Drug Resistance of Gastric Cancer

Gastric cancer (GC) is one of the most common malignant tumors of digestive systems worldwide, with high recurrence and mortality. Chemotherapy is still the standard treatment option for GC and can effectively improve the survival and life quality of GC patients. However, with the emergence of drug resistance, the clinical application of chemotherapeutic agents has been seriously restricted in GC patients. Although the mechanisms of drug resistance have been broadly investigated, they are still largely unknown. MicroRNAs (miRNAs) are a large group of small non-coding RNAs (ncRNAs) widely involved in the occurrence and progression of many cancer types, including GC. An increasing amount of evidence suggests that miRNAs may play crucial roles in the development of drug resistance by regulating some drug resistance-related proteins as well as gene expression. Some also exhibit great potential as novel biomarkers for predicting drug response to chemotherapy and therapeutic targets for GC patients. In this review, we systematically summarize recent advances in miRNAs and focus on their molecular mechanisms in the development of drug resistance in GC progression. We also highlight the potential of drug resistance-related miRNAs as biomarkers and therapeutic targets for GC patients.

microRNAs in cancer chemoresistance: The sword and the shield

Cancer is a multifactorial disease and one of the leading causes of mortality worldwide. Cancer cells develop multiple strategies to reduce drug sensitivity and eventually lead to chemoresistance. Chemoresistance is initiated either by intrinsic factors or due to the prolonged use of chemotherapeutics as acquired resistance. Further, chemoresistance is also one of the major reasons behind tumor recurrence and metastasis. Therefore, overcoming chemoresistance is one of the primary challenges in cancer therapy. Several mechanisms are involved in chemoresistance. Among them, the key role of ABC transporters and tumor microenvironment have been well studied. Recently, microRNAs (miRNAs) regulation in tumor development, metastasis, and chemotherapy has got wider interest due to its role in regulating genes involved in cancer progression and therapy. Noncoding RNAs, including miRNAs, have been associated with the regulation of tumor-suppressor and tumor-promoter genes. Further, miRNA can also be used as a reliable diagnostic and prognostic marker to predict the stage and types of cancer. Recent evidences have revealed that miRNAs regulation also influences the function of drug transporters and the tumor microenvironment, which affects chemosensitivity to cancer cells. Therefore, miRNAs can be a promising target to reverse back chemosensitivity in cancer cells. This review comprehensively discusses the mechanisms involved in cancer chemoresistance and its regulation by miRNAs.

Non-Coding RNAs in Gastric Cancer: From Malignant Hallmarks to Clinical Applications

Gastric cancer (GC) is one of the most lethal malignancies worldwide. However, the molecular mechanisms underlying gastric carcinogenesis remain largely unknown. Over the past decades, advances in RNA-sequencing techniques have greatly facilitated the identification of various non-coding RNAs (ncRNAs) in cancer cells, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Accumulating evidence has revealed that ncRNAs are essential regulators in GC occurrence and development. However, ncRNAs represent an emerging field of cancer research, and their complex functionality remains to be clarified. Considering the lack of viable biomarkers and therapeutic targets in GC, further studies should focus on elucidating the intricate relationships between ncRNAs and GC, which can be translated into clinical practice. In this review, we summarize recent research progress on how ncRNAs modulate the malignant hallmarks of GC, especially in tumor immune escape, drug resistance, and stemness. We also discuss the promising applications of ncRNAs as diagnostic biomarkers and therapeutic targets in GC, aiming to validate their practical value for clinical treatment.

Application of Gold Nanoparticle-Based Materials in Cancer Therapy and Diagnostics

Several metal nanoparticles have been developed for medical application. While all have their benefits, gold nanoparticles (AuNPs) are ideal in cancer therapy and diagnosis as they are chemically inert and minimally toxic. Several studies have shown the potential of AuNPs in the therapeutic field, as photosensitizing agents in sonochemical and photothermal therapy and as drug delivery, as well as in diagnostics and theranostics. Although there is a significant number of reviews on the application of AuNPs in cancer medicine, there is no comprehensive review on their application both in therapy and diagnostics. Therefore, considering the high number of studies on AuNPs’ applications, this review summarizes data on the application of AuNPs in cancer therapy and diagnostics. In addition, we looked at the influence of AuNPs’ shape and size on their biological properties. We also present the potential use of hybrid materials based on AuNPs in sonochemical and photothermal therapy and the possibility of their use in diagnostics. Despite their potential, the use of AuNPs and derivatives in cancer medicine still has some limitations. In this review, we provide an overview of the biological, physicochemical, and legal constraints on using AuNPs in cancer medicine.

Current Advances and Outlook in Gastric Cancer Chemoresistance: A Review

BACKGROUND

Surgical resection of the lesion is the standard primary treatment of gastric cancer. Unfortunately, most patients are already in the advanced stage of the disease when they are diagnosed with gastric cancer. Alternative therapies, such as radiation therapy and chemotherapy, can achieve only very limited benefits. The emergence of cancer drug resistance has always been the major obstacle to the cure of tumors. The main goal of modern cancer pharmacology is to determine the underlying mechanism of anticancer drugs.

OBJECTIVE

Here, we mainly review the latest research results related to the mechanism of chemotherapy resistance in gastric cancer, the application of natural products in overcoming the chemotherapy resistance of gastric cancer, and the new strategies currently being developed to treat tumors based on immunotherapy and gene therapy.

CONCLUSION

The emergence of cancer drug resistance is the main obstacle in achieving alleviation and final cure for gastric cancer. Mixed therapies are considered to be a possible way to overcome chemoresistance. Natural products are the main resource for discovering new drugs specific for treating chemoresistance, and further research is needed to clarify the mechanism of natural product activity in patients. .

A Computational Framework to Infer Prostate Cancer-Associated Long Noncoding RNAs and Analyses for Identifying a Competing Endogenous RNA Network

Background: Prostate cancer (PC) is the second leading cause of cancer death after lung cancer in men. Current biomarkers are ineffective for the treatment and management of the disease. Long noncoding RNAs (lncRNAs) are a heterogeneous group of transcripts that are involved in complex gene expression regulatory networks. Although lncRNAs have been suggested to be promising as future biomarkers, the connection between the majority of lncRNAs and human disease remains to be elucidated. One approach to elucidate the roles of lncRNAs in disease is through the development of computational models. For example, a novel computational model termed HyperGeometric distribution for LncRNA-Disease Association (HGLDA) has been developed. Such models need to be developed on a tumor-specific basis to better suit the particular problem. Methods: In this study, we constructed a potential pipeline through two models, HGLDA and pathway-based using data from several databases. To validate the obtained data, the expression levels of selected lncRNAs were investigated quantitatively in the DU-145, LNCaP, and PC3 PC cell lines using quantitative real-time PCR. Results: We obtained a number of lncRNAs from both models, many of which were filtered through several databases that ultimately resulted in identification of six high-value lncRNA targets. Their expression was correlated with one important component of the PI3K pathway, known to be related to PC. Conclusion: Through the assembly of a lncRNA-miRNAs-mRNA competing endogenous RNA network, we successfully predicted lncRNAs interfering with miRNAs and coding genes related to PC.

The related miRNAs involved in doxorubicin resistance or sensitivity of various cancers: an update

Doxorubicin (DOX) is an effective chemotherapy agent against a wide variety of tumors. However, intrinsic or acquired resistance diminishes the sensitivity of cancer cells to DOX, which leads to a cancer relapse and treatment failure. Resolutions to this challenge includes identification of the molecular pathways underlying DOX sensitivity/resistance and the development of innovative techniques to boost DOX sensitivity. DOX is classified as a Topoisomerase II poison, which is cytotoxic to rapidly dividing tumor cells. Molecular mechanisms responsible for DOX resistance include effective DNA repair and resumption of cell proliferation, deregulated development of cancer stem cell and epithelial to mesenchymal transition, and modulation of programmed cell death. MicroRNAs (miRNAs) have been shown to potentiate the reversal of DOX resistance as they have gene-specific regulatory functions in DOX-responsive molecular pathways. Identifying the dysregulation patterns of miRNAs for specific tumors following treatment with DOX facilitates the development of novel combination therapies, such as nanoparticles harboring miRNA or miRNA inhibitors to eventually prevent DOX-induced chemoresistance. In this article, we summarize recent findings on the role of miRNAs underlying DOX sensitivity/resistance molecular pathways. Also, we provide latest strategies for utilizing deregulated miRNA patterns as biomarkers or miRNAs as tools to overcome chemoresistance and enhance patient's response to DOX treatment.

miR-4486 enhances cisplatin sensitivity of gastric cancer cells by restraining the JAK3/STAT3 signalling pathway

Along with the occurrence of cisplatin resistance, treatment on gastric cancer (GC) becomes difficult. Therefore, researches on new therapeutic methods to revert cisplatin resistance are becoming increasingly urgent. qRT-PCR was used to quantify the expression of miR-4486, JAK3 in SGC-7901 or SGC-7901/DDP cell lines. WB was utilized to analyze the expression of JAK3, STAT3 and p-STAT3 in SGC-7901/DDP cell lines. CCK-8 assay was used to determine the IC₅₀ of cisplatin on both cell lines and cell viability of SGC-7901/DDP cell lines. The target relationship between miR-4486 and JAK3 was determined by luciferase assay. MiR-4486 expression on apoptosis of SGC-7901/DDP cell lines was determined by flow cytometry. qRT-PCR testified that miR-4486 decreased in SGC-7901/DDP cells, and the expression of miR-4486 mimic increased significantly compared with miR-4486 NC. By CCK-8 assay, the IC₅₀ of cisplatin on both cell lines were 9 μg/mL and 81.3 μg/mL, and overexpression of miR-4486 decreased the viability of SGC-7901/DDP cells. Compared with DDP group, the expression of miR-4486 accelerated SGC-7901/DDP cells apoptosis. Dual-luciferase assay suggested that JAK3 was the target gene of miR-4486. qRT-PCR and WB proved that miR-4486/JAK3 axis inhibit the activation of JAK3/STAT3 pathway, and JAK3 overexpression can partly reverse this. As shown by CCK-8 and flow cytometry, miR-4486 overexpression decreased viability and stimulated apoptosis of SGC-7901/DDP cells. However, JAK3 overexpression can also partly revert this. miR-4486 overexpression could decrease viability and improve apoptosis of SGC-7901/DDP cells to revert its cisplatin-resistance, and the mechanism may be related to JAK3/STAT3 signalling pathway.

miR-324-3p and miR-508-5p expression levels could serve as potential diagnostic and multidrug-resistant biomarkers in childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is one of the most frequent hematological malignancies in children, representing approximately 25 % of all pediatric cancers. Despite striking advances in ALL treatments, a small population of patients does not still respond to chemotherapy, raising the number of deaths in children. ABC transporters are one of the major causes of multidrug resistance (MDR) in cancers and overexpression of ABCA3 is directly associated with increased chemo-resistance in pediatric ALL. Here, we aimed to identify the microRNAs (miRNAs) which may regulate the expression of ABCA3 in childhood ALL. Bone marrow samples from a total of 50 ALLs and 59 controls were collected and after in silico and literature search, miR-324-3p and miR-508-5p were nominated from a list of putative miRNAs targeting ABCA3. Our qPCR analysis showed a low expression profile of selected miRNAs in pediatric ALL patients compared with non-cancer controls. Furthermore, we found that both miR-324-3p and miR-508-5p were significantly differentially expressed between patients with positive and negative minimal residual disease (MRD + vs MRD-) after one year of chemotherapy while only miR-508-5p was underexpressed in relapsed ALL patients. Additionally, a negative correlation was identified between the expression of these two miRNAs and ABCA3, supporting the regulatory effect of them on drug resistance through interacting with ABCA3. Overall, we suggested miR-324-3p and miR-508-5p as potential diagnostic and drug-resistant biomarkers in pediatric ALL. Moreover, our findings presented miR-508-5p to behave as a promising relapsed indicator in childhood ALL which can be applied in the development of novel therapeutic strategies.

TFAP2A-induced SLC2A1-AS1 promotes cancer cell proliferation

Long non-coding RNAs (lncRNAs) are involved in the occurrence and development of human cancers including lung adenocarcinoma (LUAD). SLC2A1-AS1 is a novel lncRNA that has been reported to be exceptionally expressed in several cancer types. However, the expression and role of SLC2A1-AS1 in cancer remains largely unclear. In this study, it was revealed that lncRNA SLC2A1-AS1 was notably over-expressed in LUAD and was closely correlated with patients' overall survival (OS). Knockdown of SLC2A1-AS1 could significantly restrain cell proliferation of LUAD in vitro, while over-expression of SLC2A1-AS1 had the accelerative effect. SLC2A1-AS1 enriched in the cytoplasm of LUAD cells could directly bind to miR-508-5p and negatively regulate its level. The inhibitory effect of miR-508-5p on LUAD cell proliferation was in part abrogated by SLC2A1-AS1 manipulation. Moreover, the transcription factor activating enhancer binding protein 2 α (TFAP2A) was highly expressed in LUAD and predicted worse patients' OS. TFAP2A could directly bind to the promoter region of SLC2A1-AS1 encoding gene and positively regulate the transcription of SLC2A1-AS1 in LUAD cells. Furthermore, TFAP2A-induced SLC2A1-AS1 promoted cell proliferation of lung squamous cell carcinoma (LUSC) and pancreatic adenocarcinoma (PAAD). Collectively, these findings suggest that TFAP2A-mediated lncRNA SLC2A1-AS1 works as an oncogene to drive cancer cell proliferation.

HOXA13, Negatively Regulated by miR-139-5p, Decreases the Sensitivity of Gastric Cancer to 5-Fluorouracil Possibly by Targeting ABCC4

Purpose

Chemoresistance remains a major challenge in the therapy of gastric cancer (GC). The homeobox (HOX) gene family has gained attention in carcinogenesis and chemoresistance. Here, this study aimed to explore the mechanism of HOXA13 in GC chemoresistance.

Methods

Quantitative real-time PCR (qRT-PCR) and Western blot were used to evaluate the expression of HOXA13 in GC tissues. The Kaplan–Meier plotter database was mined for prognosis analysis of GC patients with different HOXA13 expression receiving 5-Fluorouracil (5-FU) therapy. The effects of HOXA13 on sensitivity of GC cells to 5-FU were investigated by Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2’-deoxyuridine (EdU) incorporation, flow cytometry and experiment in vivo. RNA-Sequencing analysis was performed to explore the underlying mechanism of HOXA13-mediated 5-FU resistance in GC. Chromatin immunoprecipitation (ChIP) and rescue experiments were applied to determine the relationship between HOXA13 and ABCC4. Luciferase reporter assay was performed to assess interaction of miR-139-5p and HOXA13.

Results

HOXA13 was upregulated in GC and its high expression was associated with poor prognosis of GC patients with 5-FU treatment. Overexpression of HOXA13 impaired the inhibitory effects of 5-FU on GC cells proliferation in vitro and vivo, and knockdown of HOXA13 exacerbated 5-FU-induced GC cells apoptosis. Mechanistically, HOXA13, directly targeted by miR-139-5p in GC, might upregulate ABCC4 expression, thereby accentuating 5-FU resistance of GC cells.

Conclusion

Our study suggests that HOXA13 attenuates 5-FU sensitivity of GC possibly by upregulating ABCC4. Thus, targeting HOXA13 would provide a novel prospective into the potential therapeutic strategy for reversing chemoresistance.

Recent advances of miRNAs in the development and clinical application of gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors. The mechanism of how GC develops is vague, and therapies are inefficient. The function of microRNAs (miRNAs) in tumorigenesis has attracted the attention from many scientists. During the development of GC, miRNAs function in the regulation of different phenotypes, such as proliferation, apoptosis, invasion and metastasis, drug sensitivity and resistance, and stem-cell-like properties. MiRNAs were evaluated for use in diagnostic and prognostic predictions and exhibited considerable accuracy. Although many problems exist for the application of therapy, current studies showed the antitumor effects of miRNAs. This paper reviews recent advances in miRNA mechanisms in the development of GC and the potential use of miRNAs in the diagnosis and treatment of GC.

Hsa-miR-34a-5p reverses multidrug resistance in gastric cancer cells by targeting the 3'-UTR of SIRT1 and inhibiting its expression

Multidrug resistance (MDR) is a major obstacle to chemotherapy, which leads to ineffective chemotherapy, an important treatment strategy for gastric cancer (GC). The abnormality of microRNAs (miRNAs) is critical to the occurrence and progression of MDR in various tumors. In this study, hsa-miR-34a-5p was found to be decreased in multidrug resistant GC cells SGC-7901/5-Fluorouracil (SGC-7901/5-Fu) compared to the parental SGC-7901 cells. Overexpression of hsa-miR-34a-5p in SGC-7901/5-Fu cells promoted apoptosis and decreased migration and invasiveness after chemotherapy. In addition, overexpression of hsa-miR-34a-5p suppressed the growth of drug-resistant tumor in vivo. The mechanism of the effects of hsa-miR-34a-5p could include the regulation of the expression of Sirtuin 1 (SIRT1), P-glycoprotein (P-gp) or Multidrug resistance-related protein 1 (MRP1) through direct binding to the 3'-untranslated region (UTR) of SIRT1. Functional gain-and-loss experiments indicated that hsa-miR-34a-5p enhances the chemotherapy sensitivity of MDR GC cells by inhibiting SIRT1, P-gp and MRP1. In conclusion, hsa-miR-34a-5p can reverse the MDR of GC cells by inhibiting the expression of SIRT1, P-gp or MRP1.

The Sensitivity Prediction of Neoadjuvant Chemotherapy for Gastric Cancer

The overall efficacy of neoadjuvant chemoradiotherapy (NACT) for locally advanced gastric cancer (LAGC) has been recognized. However, the response rate of NACT is limited due to tumor heterogeneity. For patients who are resistant to NACT, not only the operation timing will be postponed, patients will also suffer from the side effects of it. Thus, it is important to develop a comprehensive strategy and screen out patients who may be sensitive to NACT. This article summarizes the related research progress on the sensitivity prediction of NACT for GC in the following aspects: microRNAs, metabolic enzymes, exosomes, other biomarkers; inflammatory indicators, and imageological assessments. The results showed that there were many studies on biomarkers, but no unified conclusion has been drawn. The inflammatory indicators are related to the survival and prognosis of patients under NACT. For imageological assessments such as CT, MRI, and PET, with careful integration and optimization, they will have unique advantages in early screening for patients who are sensitive to NACT.

RNA editing enzyme ADAR1 governs the circadian expression of P-glycoprotein in human renal cells by regulating alternative splicing of the ABCB1 gene

The expression and function of some xenobiotic transporters vary according to the time of the day, causing the dosing time-dependent changes in drug disposition and toxicity. P-glycoprotein (P-gp), encoded by the ABCB1 gene, is highly expressed in the kidneys and functions in the renal elimination of various drugs. The elimination of several P-gp substrates was demonstrated to vary depending on administration time, but the underlying mechanism remains unclear. We found that adenosine deaminase acting on RNA (ADAR1) was involved in the circadian regulation of P-gp expression in human renal proximal tubular epithelial cells (RPTECs). After synchronization of the cellular circadian clock by dexamethasone treatment, the expression of P-gp exhibited a significant 24-h oscillation in RPTECs, but this oscillation was disrupted by the downregulation of ADAR1. Although ADAR1 catalyzes adenosine-to-inosine (A-to-I) RNA editing in double-stranded RNA substrates, no significant ADAR1-regulated editing sites were detected in the human ABCB1 transcripts in RPTECs. On the other hand, downregulation of ADAR1 induced alternative splicing in intron 27 of the human ABCB1 gene, resulting in the production of retained intron transcripts. The aberrant spliced transcript was sensitive to nonsense-mediated mRNA decay, leading to the decreased stability of ABCB1 mRNA and prevention of the 24-h oscillation of P-gp expression. These findings support the notion that ADAR1-mediated regulation of alternative splicing of the ABCB1 gene is a key mechanism of circadian expression of P-gp in RPTECs, and the regulatory mechanism may underlie the dosing time-dependent variations in the renal elimination of P-gp substrates.

ChrXq27.3 miRNA cluster functions in cancer development

MicroRNAs (miRNAs) regulate the expression of their target genes post-transcriptionally; thus, they are deeply involved in fundamental biological processes. miRNA clusters contain two or more miRNA-encoding genes, and these miRNAs are usually coexpressed due to common expression mechanisms. Therefore, miRNA clusters are effective modulators of biological pathways by the members coordinately regulating their multiple target genes, and an miRNA cluster located on the X chromosome q27.3 region has received much attention in cancer research recently. In this review, we discuss the novel findings of the chrXq27.3 miRNA cluster in various types of cancer.

The chrXq27.3 miRNA cluster contains 30 mature miRNAs synthesized from 22 miRNA-encoding genes in an ~ 1.3-Mb region. The expressions of these miRNAs are usually negligible in many normal tissues, with the male reproductive system being an exception. In cancer tissues, each miRNA is dysregulated, compared with in adjacent normal tissues. The miRNA-encoding genes are not uniformly distributed in the region, and they are further divided into two groups (the miR-506-514 and miR-888-892 groups) according to their location on the genome. Most of the miRNAs in the former group are tumor-suppressive miRNAs that are further downregulated in various cancers compared with normal tissues. miR-506-3p in particular is the most well-known miRNA in this cluster, and it has various tumor-suppressive functions associated with the epithelial–mesenchymal transition, proliferation, and drug resistance. Moreover, other miRNAs, such as miR-508-3p and miR-509-3p, have similar tumor-suppressive effects. Hence, the expression of these miRNAs is clinically favorable as prognostic factors in various cancers. However, the functions of the latter group are less understood. In the latter group, miR-888-5p displays oncogenic functions, whereas miR-892b is tumor suppressive. Therefore, the functions of the miR-888–892 group are considered to be cell type- or tissue-specific.

In conclusion, the chrXq27.3 miRNA cluster is a critical regulator of cancer progression, and the miRNAs themselves, their regulatory mechanisms, and their target genes might be promising therapeutic targets.

Long Noncoding RNA MALAT1 Promotes Colorectal Cancer Progression by Acting as a ceRNA of miR-508-5p to Regulate RAB14 Expression

Accumulating evidence suggested that lncRNA MALAT1 plays critical roles in the commencement and progression of malignant cancers. Nevertheless, the function of MALAT1 in colorectal cancer (CRC) remains largely unknown. In the present study, we reported that MALAT1 expression is significantly upregulated in CRC and correlated with advanced TNM stage, lymph node metastasis, and worse prognosis in patients. Functional assays revealed that MALAT1 knockdown reduced CRC cell growth and invasion abilities in vitro. Mechanistically, we discovered that MALAT1 may serve as a competing endogenous RNA (ceRNA) to miR-508-5p in CRC progression. Bioinformatics analysis and luciferase assays confirmed that RAB14 acts as a target of miR-508-5p. In addition, downregulation of RAB14 reduced the progression of CRC. Collectively, our findings indicated that MALAT1 could promote CRC progress by sponging miR-508-5p and enhancing RAB14 expression, which provides a therapeutic target in CRC treatment.

Non-coding RNAs underlying chemoresistance in gastric cancer

BACKGROUND

Gastric cancer (GC) is a major health issue in the Western world. Current clinical imperatives for this disease include the identification of more effective biomarkers to detect GC at early stages and enhance the prevention and treatment of metastatic and chemoresistant GC. The advent of non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs) and long-non coding RNAs (lncRNAs), has led to a better understanding of the mechanisms by which GC cells acquire features of therapy resistance. ncRNAs play critical roles in normal physiology, but their dysregulation has been detected in a variety of cancers, including GC. A subset of ncRNAs is GC-specific, implying their potential application as biomarkers and/or therapeutic targets. Hence, evaluating the specific functions of ncRNAs will help to expand novel treatment options for GC.

CONCLUSIONS

In this review, we summarize some of the well-known ncRNAs that play a role in the development and progression of GC. We also review the application of such ncRNAs in clinical diagnostics and trials as potential biomarkers. Obviously, a deeper understanding of the biology and function of ncRNAs underlying chemoresistance can broaden horizons toward the development of personalized therapy against GC.

A Potential Tumor Suppressor Gene Named miR-508-5p Inhibited the Proliferation and Invasion of Human Melanoma Cells by Targeting KIT

Melanoma is the main death cause of human skin cancer. Increasing evidences demonstrate that microRNAs act as key roles in mediating tumor occurrence and progression. MiR-508-5p has proved to participate in the development of various types of human malignancies. However, the role of miR-508-5p in melanoma remained unclear. In in vitro study, miR-508-5p level in peripheral blood samples of patients with melanoma and human melanoma A375 cells was downregulated compared to that in normal peripheral blood samples or normal human epidermal melanocytes (MHEM). MiR-508-5p overexpression significantly inhibited the cell proliferation, migration and invasion in A375 cells, and thus inhibiting KIT expression at both gene and protein levels. Furthermore, western blot analysis showed miR-508-5p reduced cell proliferation by targeting KIT to modulate RAS/RAF/MEK/ERK pathway. Taken together, we speculated that miR-508-5p functioned as an important suppressor in human melanoma by targeting KIT, suggesting miR-508-5p might be a promising tumor suppressor gene for further target therapies from bench to clinic.

Mechanisms of Multidrug Resistance in Cancer Chemotherapy

Cancer is one of the main causes of death worldwide. Despite the significant development of methods of cancer healing during the past decades, chemotherapy still remains the main method for cancer treatment. Depending on the mechanism of action, commonly used chemotherapeutic agents can be divided into several classes (antimetabolites, alkylating agents, mitotic spindle inhibitors, topoisomerase inhibitors, and others). Multidrug resistance (MDR) is responsible for over 90% of deaths in cancer patients receiving traditional chemotherapeutics or novel targeted drugs. The mechanisms of MDR include elevated metabolism of xenobiotics, enhanced efflux of drugs, growth factors, increased DNA repair capacity, and genetic factors (gene mutations, amplifications, and epigenetic alterations). Rapidly increasing numbers of biomedical studies are focused on designing chemotherapeutics that are able to evade or reverse MDR. The aim of this review is not only to demonstrate the latest data on the mechanisms of cellular resistance to anticancer agents currently used in clinical treatment but also to present the mechanisms of action of novel potential antitumor drugs which have been designed to overcome these resistance mechanisms. Better understanding of the mechanisms of MDR and targets of novel chemotherapy agents should provide guidance for future research concerning new effective strategies in cancer treatment.

Noncoding RNAs in gastric cancer: implications for drug resistance

Gastric cancer is the fourth most common malignancy and the third leading cause of cancer-related deaths worldwide. Advanced gastric cancer patients can notably benefit from chemotherapy including adriamycin, platinum drugs, 5-fluorouracil, vincristine, and paclitaxel as well as targeted therapy drugs. Nevertheless, primary drug resistance or acquisition drug resistance eventually lead to treatment failure and poor outcomes of the gastric cancer patients. The detailed mechanisms involved in gastric cancer drug resistance have been revealed. Interestingly, different noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), are critically involved in gastric cancer development. Multiple lines of evidences demonstrated that ncRNAs play a vital role in gastric cancer resistance to chemotherapy reagents and targeted therapy drugs. In this review, we systematically summarized the emerging role and detailed molecular mechanisms of ncRNAs impact drug resistance of gastric cancer. Additionally, we propose the potential clinical implications of ncRNAs as novel therapeutic targets and prognostic biomarkers for gastric cancer.

Propofol facilitates cisplatin sensitivity via lncRNA MALAT1/miR-30e/ATG5 axis through suppressing autophagy in gastric cancer

AIMS

Recently, chemoresistance has been recognized as an obstacle in the treatment of gastric cancer (GC). The aim of this study was to investigate the biological functions and underlying mechanisms of propofol in GC chemoresistance.

MAIN METHODS

CCK-8 assay, flow cytometry and immunofluorescent staining were performed to assess the IC₅₀ concentration, cell apoptosis and autophagy activity of cisplatin in both GC chemosensitive cells (SGC7901) and chemoresistant cells (SGC7901/CDDP). The expression pattern of MALAT1 in GC cells was detected by qRT-PCR. The shRNAs and overexpressing plasmids were employed for the loss or gain-of-function. Dual-luciferase reporter assay was subjected to verify the binding relationship between MALAT1 and miR-30e. Besides, ATG5 mRNA and protein levels were determined using qRT-PCR and western blot analysis. Furthermore, GC xenograft mice model was established to validate the in vitro findings.

KEY FINDINGS

Chemoresistant GC cells presented higher IC₅₀ of cisplatin, increased autophagy activity and stronger expression of MALAT1. The application of propofol promoted cell apoptosis and reduced the activity of autophagy through downregulating MALAT1. Silencing of MALAT1 inhibited chemo-induced autophagy, whereas MALAT1 overexpression promoted autophagy in GC cells. Mechanistic researches demonstrated that MALAT1 could bind with miR-30e to regulate ATG5 expression, thus causing the suppression of autophagy. In vivo GC xenograft model treated with both propofol and cisplatin also showed significantly decreased tumor size and weight, which was enhanced by knockdown of MALAT1.

SIGNIFICANCE

Altogether, our study revealed a novel mechanism of propofol of lncRNA MALAT1/miR-30e/ATG5 mediated autophagy-related chemoresistance in GC, casting new lights on the understanding of propofol.

MicroRNA-106a-3p Induces Apatinib Resistance and Activates Janus-Activated Kinase 2 (JAK2)/Signal Transducer and Activator of Transcription 3 (STAT3) by Targeting the SOCS System in Gastric Cancer

Background

MicroRNA (miR)-106a was involved in the tumorigenesis and highly expressed in gastric cancer. Required apatinib resistance greatly limits its efficacy in patients. Thus, the aim of the present study was to investigate the potential role of miR-106a-3p in gastric cancer cells with apatinib-resistance.

Material/Methods

The expression of miR-106a-3p was quantified by real-time quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8) assay was performed to analyze the sensitivity of gastric cancer cells to apatinib. The expression of relevant drug-resistant proteins was detected by western blot. We searched Targetscan6.2 to find out the target gene of miR-106a-3p. Luciferase reporter assay was used to analyze whether miR-106a-3p bound to relevant gene of SOCS family. The SOCS2, SOCS4, and SOCS5 were qualified by western blot, and their mRNA levels were detected by RT-qPCR. Further, JAK2, STAT3, and their phosphorylation levels were detected by western blot.

Results

The results showed that the expression of miR-106a-3p was increased in apatinib-resistant gastric cancer, while miR-106a-3p inhibitor reduced the drug-resistance of SGC-7901-AP cells to apatinib. Dual luciferase reporter gene assay suggested that SOCS2, SOCS4, and SOCS5 were target genes of miR-106a-3p. The relevant SOCS genes silencing reversed the effects of miR-106a-3p inhibitor on decreasing the apatinib resistance of SGC-7901-AP cells, while the phosphorylation level of JAK and STAT reduced by miR-106a-3p inhibitor were increased.

Conclusions

miR-106a-3p induces apatinib resistance and activates JAK2/STAT3 by targeting SOCS system in gastric cancer. miR-106a-3p/SOCS plays a potent role in gastric cancer cell resistance to apatinib.

Research Progress in microRNA-Based Therapy for Gastric Cancer

Gastric cancer (GC) is one of the leading causes of tumor-related mortality. In addition to surgery and endoscopic resection, systemic therapy remains the main treatment option for GC, especially for advanced-stage disease and for cases not suitable for surgical therapy. Hence, improving the efficacy of systemic therapy is still an urgent problem to overcome. In the past decade, the essential roles of microRNAs (miRNAs) in tumor treatment have been increasingly recognized. In particular, miRNAs were recently shown to reverse the resistance to chemotherapy drugs such as 5-fluorouracil, cisplatin, and doxorubicin. Synthesized nanoparticles loaded with mimics or inhibitors of miRNAs can directly target tumor cells to suppress their growth. Moreover, exosomes may serve as promising safe carriers for mimics or inhibitors of miRNAs to treat GC. Some miRNAs have also been shown to play roles in the mechanism of action of other anti-tumor drugs. Therefore, in this review, we highlight the research progress on microRNA-based therapy in GC and discuss the challenges and prospects associated with this strategy. We believe that microRNA-based therapy has the potential to offer a clinical benefit to GC patients, and this review would contribute to and motivate further research to promote this field toward this ultimate goal.

MicroRNA-Based Combinatorial Cancer Therapy: Effects of MicroRNAs on the Efficacy of Anti-Cancer Therapies

The susceptibility of cancer cells to different types of treatments can be restricted by intrinsic and acquired therapeutic resistance, leading to the failure of cancer regression and remission. To overcome this problem, a combination therapy has been proposed as a fundamental strategy to improve therapeutic responses; however, resistance is still unavoidable. MicroRNA (miRNAs) are associated with cancer therapeutic resistance. The modulation of dysregulated miRNA levels through miRNA-based therapy comprising a replacement or inhibition approach has been proposed to sensitize cancer cells to other anti-cancer therapies. The combination of miRNA-based therapy with other anti-cancer therapies (miRNA-based combinatorial cancer therapy) is attractive, due to the ability of miRNAs to target multiple genes associated with the signaling pathways controlling therapeutic resistance. In this article, we present an overview of recent findings on the role of therapeutic resistance-related miRNAs in different types of cancer. We review the feasibility of utilizing dysregulated miRNAs in cancer cells and extracellular vesicles as potential candidates for miRNA-based combinatorial cancer therapy. We also discuss innate properties of miRNAs that need to be considered for more effective combinatorial cancer therapy.

MiR-26b suppresses hepatocellular carcinoma development by negatively regulating ZNRD1 and Wnt/β-catenin signaling

Previous studies have indicated that Zinc ribbon domain-containing 1 (ZNRD1) is attributed to the carcinogenesis of human tumors. However, the role of ZNRD1 and its regulation in hepatocellular carcinoma (HCC) are still largely unclear. In this study, we examined the expression profiles of ZNRD1 in HCC tissues by immunohistochemistry (IHC) and publicly datasets analysis. In vitro and in vivo experiments were conducted to identify the function of ZNRD1 in HCC. In addition, miRNA potentially targeting ZNRD1 was predicted by bioinformatics analysis and further verified via in vitro experiments. Our results revealed that ZNRD1 was frequently upregulated in HCC tissues compared with that in nontumor tissues. High ZNRD1 expression in HCC tissues was positively associated with advanced tumor stage and poor prognosis. Function experiments showed that knockdown of ZNRD1 inhibited cell growth and invasion in vitro, and suppressed tumor development in vivo. Moreover, ZNRD1 promoted the activation of Wnt/β-catenin signaling pathway in HCC. Importantly, miR-26b directly inhibited the transcription activity of ZNRD1. Overexpression of ZNRD1 dramatically abolished the inhibitory effects of miR-26b on HCC cells. Taken together, our results uncover a novel mechanistic role for miR-26b/ZNRD1 axis in HCC, proposing ZNRD1 inhibition as a potent therapeutic strategy for hepatocellular carcinoma.

miR-625 reverses multidrug resistance in gastric cancer cells by directly targeting ALDH1A1

Background: microRNAs (miRNAs) are emerging as critical regulators of multidrug resistance (MDR) in gastric cancer, a major cause of chemotherapy failure. miR-625 is downregulated in gastric cancer and negatively associated with metastasis. In the current study, we aimed to investigate whether miR-625 regulates MDR in gastric cancer.

Methods: The level of miR-625 in gastric cancer cells with or without MDR was quantified by quantitative reverse transcription PCR (qRT-PCR) analysis. The sensitivity of gastric cancer cells to chemotherapeutic agents was assessed by MTT assay. The protein expression was determined by Western blot analysis, and the luciferase reporter assay was applied to confirm miR-625 regulation of the potential target.

Results: miR-625 is downregulated in MDR gastric cancer cells compared with chemosensitive counterparts. In addition, miR-625 increases the sensitivity and promotes apoptosis of gastric cancer cells when treated with different chemotherapeutic agents. Moreover, miR-625 directly targets the aldehyde dehydrogenase 1A1 (ALDH1A1), and importantly, the restoration of ALDH1A1 expression rescues miR-625 effects on MDR in gastric cancer cells.

Conclusion: miR-625 reverses MDR in gastric cancer cells by targeting ALDH1A1. Hence, our study identifies miR-625 as a novel regulator of MDR in gastric cancer cells, and implicates its potential application for overcoming MDR in gastric cancer chemotherapy.

MiR-876-5p regulates gastric cancer cell proliferation, apoptosis and migration through targeting WNT5A and MITF

MicroRNAs (miRNAs) are reported to play critical roles in various cancers. Recently, mounting miRNAs are found to exert oncogenic or tumor inhibitory role in gastric cancer (GC), however, their potential molecular mechanism in GC remains ill-defined. Currently, we aimed to elucidate the functional and mechanistic impacts of a novel miRNA on GC cellular process. The significant down-regulation of miR-876-5p in GC cells attracted our attention. In function, we performed gain-of-function assays and found that miR-876-5p overexpression repressed proliferative, anti-apoptotic and migratory abilities and epithelial–mesenchymal transition (EMT) of GC cells. By applying bioinformatics prediction and mechanism experiments, we verified that miR-876-5p could double-bind to the 3′ untranslated regions (3′UTRs) of Wnt family member 5A (WNT5A) and melanogenesis associated transcription factor (MITF), thus regulating their mRNA and protein levels. Both WNT5A and MITF were highly expressed in GC cells. Additionally, we conducted loss-of-function assays and confirmed the oncogenic roles of WNT5A and MITF in GC. Finally, rescue assay uncovered a fact that miR-876-5p suppressed GC cell viability and migration, but induced cell apoptosis via targeting WNT5A and MITF. Taken together, we might offer a valuable evidence for miR-876-5p role in GC development.

Emerging targets in cancer drug resistance

Drug resistance is a complex phenomenon that frequently develops as a failure to chemotherapy during cancer treatment. Malignant cells increasingly generate resistance to various chemotherapeutic drugs through distinct mechanisms and pathways. Understanding the molecular mechanisms involved in drug resistance remains an important area of research for identification of precise targets and drug discovery to improve therapeutic outcomes. This review highlights the role of some recent emerging targets and pathways which play critical role in driving drug resistance.