miR-30 decreases multidrug resistance in human gastric cancer cells by modulating cell autophagy

Autophagy mediated immune response regulation and drug resistance in cancer

Autophagy is a critical regulator of cellular homeostasis. The proteins involved in autophagy orchestrate the functions to strike the balance between cell survival and cell death in context-specific situations like aging, infections, inflammation and most importantly carcinogenesis. One of the major dead-locks in cancer treatment is the development of resistance to the available drugs (multi-drug resistance) as well as immune-suppressions in patients. Different studies over time have shown that autophagy is being involved in chemotherapy by working hand in hand with apoptosis or drug resistance through proliferative signals. Resistance to various drugs, such as, Cisplatin, Vincristine, Tamoxifen (TAM) occurs by epigenetic modifications, changed expression levels of microRNAs (miRNAs/miRs), and long non-coding RNAs (lncRNAs), which are regulated by the aberrant autophagy levels in lung, and breast cancers. More interestingly in the tumour microenvironment the immune suppressor cells also bring in autophagy in different pathway regulations either helping or opposing the whole carcinogenesis process. Macrophages, T cells, B cells, dendritic cells (DCs), neutrophils, and fibroblasts show involvement of autophagy in their differentiation and development in the tumor microenvironment (TME). Here, this extensive review for the first time tries to bring under a single canopy, several recent examples of autophagy-mediated immune regulations and autophagy-mediated epigenetically regulated drug resistance in different types of cancers.

Overexpression of miR‑424‑5p reduces cisplatin resistance by downregulating SMURF1 in gastric cancer

Chemoresistance is a major obstacle in the treatment of gastric cancer (GC). Notably, aberrant expression of microRNAs (miRs) is closely related to tumor development and progression. In the present study, the role of miR-424-5p in the chemoresistance of GC was investigated. Reverse transcription-quantitative PCR was used to detect the expression levels of miR-424-5p in tissues and different cell lines. Cell viability and apoptosis were detected via a Cell Counting Kit-8 assay, western blotting and flow cytometry. The targeting relationship between miR-424-5p and SMAD-specific E3 ubiquitin protein ligase 1 (SMURF1) was verified via dual-luciferase reporter assays and the molecular mechanism was investigated by western blotting. The results revealed that miR-424-5p was expressed at low levels in GC tissues and cell lines, and that low miR-424-5p expression was associated with poor N stage and worse prognosis, especially in patients who received adjuvant chemotherapy. Further experiments revealed that the overexpression of miR-424-5p reduced cisplatin (CDDP) resistance and promoted GC cell apoptosis, whereas inhibiting miR-424-5p had the opposite effect. Mechanistically, it was found that miR-424-5p downregulated the expression of SMURF1 to regulate the expression of ING2 and p53, thereby modulating CDDP resistance in GC. In summary, the present study demonstrated that miR-424-5p may serve an important regulatory role in CDDP resistance in GC, and could be a potential diagnostic biomarker and therapeutic target for GC chemoresistance.

MicroRNA-mediated autophagy and drug resistance in cancer: mechanisms and therapeutic strategies

This paper provides an exhaustive overview of the intricate interplay between microRNAs (miRNAs) and autophagy in the context of human cancers, underscoring the pivotal role these non-coding RNAs play in modulating autophagic pathways and their implications for cancer development, progression, and resistance to therapy. MiRNAs, as critical regulators of gene expression post-transcription, influence various biological processes, including autophagy, a catabolic mechanism essential for cellular homeostasis, stress response, and survival. The review meticulously delineates the mechanisms through which miRNAs impact autophagy by targeting specific genes and signaling pathways, thereby affecting cancer cell proliferation, metastasis, and response to chemotherapy. It highlights several miRNAs with dual roles, acting either as oncogenes or tumor suppressors based on the cellular context and the specific autophagic pathways they regulate. The paper further explores the therapeutic potential of targeting miRNA-autophagy axis, offering insights into novel strategies for cancer treatment through modulation of this axis. Emphasizing the complexity of the miRNA-autophagy relationship, the review calls for more in-depth studies to unravel the nuanced regulatory networks between miRNAs and autophagy in cancer, which could pave the way for the development of innovative therapeutic interventions and diagnostic tools.

MicroRNAs as the critical regulators of autophagy-mediated cisplatin response in tumor cells

Chemotherapy is one of the most common therapeutic methods in advanced and metastatic tumors. Cisplatin (CDDP) is considered as one of the main first-line chemotherapy drugs in solid tumors. However, there is a high rate of CDDP resistance in cancer patients. Multi-drug resistance (MDR) as one of the main therapeutic challenges in cancer patients is associated with various cellular processes such as drug efflux, DNA repair, and autophagy. Autophagy is a cellular mechanism that protects the tumor cells toward the chemotherapeutic drugs. Therefore, autophagy regulatory factors can increase or decrease the chemotherapy response in tumor cells. MicroRNAs (miRNAs) have a pivotal role in regulation of autophagy in normal and tumor cells. Therefore, in the present review, we discussed the role of miRNAs in CDDP response through the regulation of autophagy. It has been reported that miRNAs mainly increased the CDDP sensitivity in tumor cells by inhibition of autophagy. PI3K/AKT signaling pathway and autophagy-related genes (ATGs) were the main targets of miRNAs in the regulation of autophagy-mediated CDDP response in tumor cells. This review can be an effective step to introduce the miRNAs as efficient therapeutic options to increase autophagy-mediated CDDP sensitivity in tumor cells.

Regulation of autophagy by non-coding RNAs in gastric cancer

Autophagy is a conserved cellular self-digesting process that degrades obsoleting proteins and cellular components and plays a crucial role in the tumorigenesis, metastasis, and drug resistance of various tumors such as gastric cancer (GC). As a hotspot in molecular biology, non-coding RNAs (ncRNAs) are involved in the regulation of multiple biological processes, such as autophagy. Increasing evidence indicate that various ncRNAs exert double roles in the initiation and progression of GC, either serve as oncogenes or tumor suppressors. Recent studies have shown that some ncRNAs could modulate autophagy activity in GC cells, which would affect the malignant transformation and drug resistance. Whether the function of ncRNAs in GC is dependent on autophagy is undefined. Therefore, identifying the underlying moleculr targets of ncRNAs in autophagy pathways and the role of ncRNA-regulated autophagy in GC could develop new treatment interventions for this disease. This review summarizes the autophagy process and its role in GC, and the regulatory mechanisms of ncRNAs, as well as focuses on the dual role of ncRNAs-mediated autophagy in GC, for the development of potential therapeutic strategies in GC patients.

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.

Contribution of MicroRNAs in Chemoresistance to Cisplatin in the Top Five Deadliest Cancer: An Updated Review

Cisplatin (DDP) is a well-known anticancer drug used for the treatment of numerous human cancers in solid organs, including bladder, breast, cervical, head and neck squamous cell, ovarian, among others. Its most important mode of action is the DNA-platinum adducts formation, inducing DNA damage response, silencing or activating several genes to induce apoptosis; these mechanisms result in genetics and epigenetics modifications. The ability of DDP to induce tumor cell death is often challenged by the presence of anti-apoptotic regulators, leading to chemoresistance, wherein many patients who have or will develop DDP-resistance. Cancer cells resist the apoptotic effect of chemotherapy, being a problem that severely restricts the successful results of treatment for many human cancers. In the last 30 years, researchers have discovered there are several types of RNAs, and among the most important are non-coding RNAs (ncRNAs), a class of RNAs that are not involved in protein production, but they are implicated in gene expression regulation, and representing the 98% of the human genome non-translated. Some ncRNAs of great interest are long ncRNAs, circular RNAs, and microRNAs (miRs). Accumulating studies reveal that aberrant miRs expression can affect the development of chemotherapy drug resistance, by modulating the expression of relevant target proteins. Thus, identifying molecular mechanisms underlying chemoresistance development is fundamental for setting strategies to improve the prognosis of patients with different types of cancer. Therefore, this review aimed to identify and summarize miRs that modulate chemoresistance in DDP-resistant in the top five deadliest cancer, both in vitro and in vivo human models.

The MicroRNA-Based Strategies to Combat Cancer Chemoresistance via Regulating Autophagy

Chemoresistance frequently occurs in cancer treatment, which results in chemotherapy failure and is one of the most leading causes of cancer-related death worldwide. Understanding the mechanism of chemoresistance and exploring strategies to overcome chemoresistance have become an urgent need. Autophagy is a highly conserved self-degraded process in cells. The dual roles of autophagy (pro-death or pro-survival) have been implicated in cancers and chemotherapy. MicroRNA (miRNA) is a class of small non-coding molecules that regulate autophagy at the post-transcriptional level in cancer cells. The association between miRNAs and autophagy in cancer chemoresistance has been emphasized. In this review, we focus on the dual roles of miRNA-mediated autophagy in facilitating or combating chemoresistance, aiming to shed lights on the potential role of miRNAs as targets to overcome chemoresistance.

Potential Therapeutic Action of Autophagy in Gastric Cancer Managements: Novel Treatment Strategies and Pharmacological Interventions

Gastric cancer (GC), second most leading cause of cancer-associated mortality globally, is the cancer of gastrointestinal tract in which malignant cells form in lining of the stomach, resulting in indigestion, pain, and stomach discomfort. Autophagy is an intracellular system in which misfolded, aggregated, and damaged proteins, as well as organelles, are degraded by the lysosomal pathway, and avoiding abnormal accumulation of huge quantities of harmful cellular constituents. However, the exact molecular mechanism of autophagy-mediated GC management has not been clearly elucidated. Here, we emphasized the role of autophagy in the modulation and development of GC transformation in addition to underlying the molecular mechanisms of autophagy-mediated regulation of GC. Accumulating evidences have revealed that targeting autophagy by small molecule activators or inhibitors has become one of the greatest auspicious approaches for GC managements. Particularly, it has been verified that phytochemicals play an important role in treatment as well as prevention of GC. However, use of combination therapies of autophagy modulators in order to overcome the drug resistance through GC treatment will provide novel opportunities to develop promising GC therapeutic approaches. In addition, investigations of the pathophysiological mechanism of GC with potential challenges are urgently needed, as well as limitations of the modulation of autophagy-mediated therapeutic strategies. Therefore, in this review, we would like to deliver an existing standard molecular treatment strategy focusing on the relationship between chemotherapeutic drugs and autophagy, which will help to improve the current treatments of GC patients.

MicroRNA-30 inhibits the growth of human ovarian cancer cells by suppressing RAB32 expression

Introduction

MicroRNAs (miRs) exhibit the potential to act as therapeutic targets for the management of human cancers including ovarian cancer. The role of microRNA-30 (miR-30) via modulation of RAB32 expression has not been studied in ovarian cancer. Consistently, the present study was designed to characterize the molecular role of miR-30/RAB32 axis in human ovarian cancer.

Methods

Cell viability was determined by MTT assay. Expression analysis was carried out by qRT-PCR. Dual luciferase assay was used to confirm the interaction between miR-30 and RAB32. Scratch-heal and transwell chamber assays were used to monitor the cell migration and invasion. Western blotting and immunofluorescence assays were used to determine the protein expression.

Results

The results revealed significant (p < 0.05) downregulation of miR-30 in human ovarian cancer cell lines. Overexpression of miR-30 in ovarian SK-OV-3 and A2780 cancer cells significantly (p < 0.05) inhibited their proliferation. Besides, ovarian cancer cells overexpressing miR-30 showed significantly (p < 0.05) lower migration and invasion. The miR-30 upregulation also altered the expression pattern of marker proteins of epithelial–mesenchymal transition in ovarian cancer cells. In silico analysis predicted RAB32 as the molecular target of miR-30 at post-transcriptional level. The silencing of RAB32 mimicked the tumor-suppressive effects of miR-30 overexpression in ovarian cancer cells. Nonetheless, overexpression of RAB32 could prevent the tumor-suppressive effects of miR-30 on SK-OV-3 and A2780 cancer cells.

Conclusion

Taken together, the results suggest the tumor-suppressive role of miR-30 and point towards the therapeutic utility of miR-30/RAB32 molecular axis in the management of ovarian cancer

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.

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. .

lncRNA DLEU2 promotes gastric cancer progression through ETS2 via targeting miR-30a-5p

Background

Gastric cancer (GC) remains an important cancer worldwide. Further understanding of the molecular mechanisms of gastric carcinogenesis will enhance the diagnosis and treatment of GC.

Methods

The expression of DLEU2 and ETS2 was analyzed in several GC cell lines using GEPIA online analyze, qRT-PCR and immunohistochemistry. The biological behavior of GC cells was detected by CCK8, clone formation, transwell, wound healing, western blot, and flow cytometry assay. More in-depth mechanisms were studied.

Results

DLEU2 was significantly up-regulated in GC tissues and cell lines. The expression of DLEU2 was significantly associated with pathological grading and TNM stage of GC patients. Furthermore, knockdown of DLEU2 inhibited the proliferation, migration, and invasion of AGS and MKN-45 cells, while overexpression of DLEU2 promoted the proliferation, migration, and invasion of HGC-27 cells. MiR-30a-5p could directly bind to the 3’ UTR region of ETS2. Moreover, DLEU2 bound to miR-30a-5p through the same binding site, which facilitated the expression of ETS2. Knockdown of DLEU2 reduced the protein level of intracellular ETS2 and inhibited AKT phosphorylation, while overexpression of DLEU2 induced the expression of ETS2 and the phosphorylation of AKT. ETS2 was highly expressed in GC tissues. The expression of ETS2 was significantly associated with age, pathological grading, and TNM stage. ETS2 overexpression promoted cell proliferation and migration of AGS and MKN-45 cells. Furthermore, ETS2 overexpression rescued cell proliferation and migration inhibition induced by DLEU2 down-regulation and miR-30a-5p up-regulation in AGS and MKN-45 cells.

Conclusions

DLEU2 is a potential molecular target for GC treatment.

MicroRNAs are involved in the development and progression of gastric cancer

MicroRNAs (miRNAs) are recognized as an essential component of the RNA family, exerting multiple and intricate biological functions, particularly in the process of tumorigenesis, proliferation, and metastatic progression. MiRNAs are altered in gastric cancer (GC), showing activity as both tumor suppressors and oncogenes, although their true roles have not been fully understood. This review will focus upon the recent advances of miRNA studies related to the regulatory mechanisms of gastric tumor cell proliferation, apoptosis, and cell cycle. We hope to provide an in-depth insight into the mechanistic role of miRNAs in GC development and progression. In particular, we summarize the latest studies relevant to miRNAs' impact upon the epithelial-mesenchymal transition, tumor microenvironment, and chemoresistance in GC cells. We expect to elucidate the molecular mechanisms involving miRNAs for better understanding the etiology of GC, and facilitating the development of new treatment regimens for the treatment of GC.

MicroRNAs as the critical regulators of cisplatin resistance in gastric tumor cells

Combined chemotherapeutic treatment is the method of choice for advanced and metastatic gastric tumors. However, resistance to chemotherapeutic agents is one of the main challenges for the efficient gastric cancer (GC) treatment. Cisplatin (CDDP) is used as an important regimen of chemotherapy for GC which induces cytotoxicity by interfering with DNA replication in cancer cells and inducing their apoptosis. Majority of patients experience cisplatin-resistance which is correlated with tumor metastasis and relapse. Moreover, prolonged and high-dose cisplatin administrations cause serious side effects such as nephrotoxicity, ototoxicity, and anemia. Since, there is a high rate of recurrence after CDDP treatment in GC patients; it is required to clarify the molecular mechanisms associated with CDDP resistance to introduce novel therapeutic methods. There are various cell and molecular processes associated with multidrug resistance (MDR) including drug efflux, detoxification, DNA repair ability, apoptosis alteration, signaling pathways, and epithelial-mesenchymal transition (EMT). MicroRNAs are a class of endogenous non-coding RNAs involved in chemo resistance of GC cells through regulation of all of the MDR mechanisms. In present review we have summarized all of the miRNAs associated with cisplatin resistance based on their target genes and molecular mechanisms in gastric tumor cells. This review paves the way of introducing a miRNA-based panel of prognostic markers to improve the efficacy of chemotherapy and clinical outcomes in GC patients. It was observed that miRNAs are mainly involved in cisplatin response of gastric tumor cells via regulation of signaling pathways, autophagy, and apoptosis.

Facing Cell Autophagy in Gastric Cancer - What Do We Know so Far?

Autophagy is a process by which misfolded proteins and damaged organelles in the lysosomes of tumor cells were degraded reusing decomposed substances and avoiding accumulation of large amounts of harmful substances. Here, the role of autophagy in the development of malignant transformation of gastric tumors, and the underlying mechanisms involved in autophagy formation, and the application of targeted autophagy in the treatment of gastric cancer were summarized.

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.

miR-26b enhances the sensitivity of hepatocellular carcinoma to Doxorubicin via USP9X-dependent degradation of p53 and regulation of autophagy

Multi-drug resistance is a major challenge to hepatocellular carcinoma (HCC) treatment, and the over-expression or deletion of microRNA (miRNA) expression is closely related to the drug-resistant properties of various cell lines. However, the underlying molecular mechanisms remain unclear. CCK-8, EdU, flow cytometry, and transmission electron microscopy were performed to determine cell viability, proliferation, apoptosis, autophagic flow, and nanoparticle characterization, respectively. In this study, the results showed that the expression of miR-26b was downregulated following doxorubicin treatment in human HCC tissues. An miR-26b mimic enhanced HCC cell doxorubicin sensitivity, except in the absence of p53 in Hep3B cells. Delivery of the proteasome inhibitor, MG132, reversed the inhibitory effect of miR-26b on the level of p53 following doxorubicin treatment. Tenovin-1 (an MDM2 inhibitor) protected p53 from ubiquitination-mediated degradation only in HepG2 cells with wild type p53. Tenovin-1 pretreatment enhanced HCC cell resistance to doxorubicin when transfected with an miR-26b mimic. Moreover, the miR-26b mimic inhibited doxorubicin-induced autophagy and the autophagy inducer, rapamycin, eliminated the differences in the drug sensitivity effect of miR-26b. In vivo, treatment with sp94dr/miR-26b mimic nanoparticles plus doxorubicin inhibited tumor growth. Our current data indicate that miR-26b enhances HCC cell sensitivity to doxorubicin through diminishing USP9X-mediated p53 de-ubiquitination caused by DNA damaging drugs and autophagy regulation. This miRNA-mediated pathway that modulates HCC will help develop novel therapeutic strategies.

The Dual Role of Autophagy in Cancer Development and a Therapeutic Strategy for Cancer by Targeting Autophagy

Autophagy is a delicate intracellular degradation process that occurs due to diverse stressful conditions, including the accumulation of damaged proteins and organelles as well as nutrient deprivation. The mechanism of autophagy is initiated by the creation of autophagosomes, which capture and encapsulate abnormal components. Afterward, autophagosomes assemble with lysosomes to recycle or remove degradative cargo. The regulation of autophagy has bipolar roles in cancer suppression and promotion in diverse cancers. Furthermore, autophagy modulates the features of tumorigenesis, cancer metastasis, cancer stem cells, and drug resistance against anticancer agents. Some autophagy regulators are used to modulate autophagy for anticancer therapy but the dual roles of autophagy limit their application in anticancer therapy, and present as the main reason for therapy failure. In this review, we summarize the mechanisms of autophagy, tumorigenesis, metastasis, cancer stem cells, and resistance against anticancer agents. Finally, we discuss whether targeting autophagy is a promising and effective therapeutic strategy in anticancer therapy.

The Role of Autophagy in Gastric Cancer Chemoresistance: Friend or Foe?

Gastric cancer is the third most common cause of cancer-related death worldwide. Drug resistance is the main inevitable and vital factor leading to a low 5-year survival rate for patients with gastric cancer. Autophagy, as a highly conserved homeostatic pathway, is mainly regulated by different proteins and non-coding RNAs (ncRNAs) and plays dual roles in drug resistance of gastric cancer. Thus, targeting key regulatory nodes in the process of autophagy by small molecule inhibitors or activators has become one of the most promising strategies for the treatment of gastric cancer in recent years. In this review, we provide a systematic summary focusing on the relationship between autophagy and chemotherapy resistance in gastric cancer. We comprehensively discuss the roles and molecular mechanisms of multiple proteins and the emerging ncRNAs including miRNAs and lncRNAs in the regulation of autophagy pathways and gastric cancer chemoresistance. We also summarize the regulatory effects of autophagy inhibitor and activators on gastric cancer chemoresistance. Understanding the vital roles of autophagy in gastric cancer chemoresistance will provide novel opportunities to develop promising therapeutic strategies for gastric cancer.

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.

microRNA-30a arbitrates intestinal-type early gastric carcinogenesis by directly targeting ITGA2

BACKGROUND

Spasmolytic polypeptide-expressing metaplasia (SPEM) is considered a precursor lesion of intestinal metaplasia and intestinal-type gastric cancer (GC), but little is known about microRNA alterations during metaplasia and GC developments. Here, we investigate miR-30a expression in gastric lesions and identify its novel target gene which is associated with the intestinal-type GC.

METHODS

We conducted in situ hybridization and qRT-PCR to determine miR-30a expression in gastric tissues. miR-30a functions were determined through induction or inhibition of miR-30a in GC cell lines. A gene microarray was utilized to confirm miR-30a target genes in GC, and siRNA-mediated target gene suppression and immunostaining were performed. The Cancer Genome Atlas data were utilized to validate gene expressions.

RESULTS

We found down-regulation of miR-30a during chief cell transdifferentiation into SPEM. MiR-30a level was also reduced in the early stage of GC, and its level was maintained in advanced GC. We identified a novel target gene of miR-30a and ITGA2, and our results showed that either ectopic expression of miR-30a or ITGA2 knockdown suppressed GC cell proliferation, migration, and tumorigenesis. Levels of ITGA2 inversely correlated with levels of miR-30a in human intestinal-type GC.

CONCLUSION

We found down-regulation of miR-30a in preneoplastic lesions and its tumor-suppressive functions by targeting ITGA2 in GC. The level of ITGA2, which functions as an oncogene, was up-regulated in human GC. The results of this study suggest that coordination of the miR-30a-ITGA2 axis may serve as an important mechanism in the development of gastric precancerous lesions and intestinal-type GC.

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.

Promotion of miR-221-5p on the Sensitivity of Gastric Cancer Cells to Cisplatin and Its Effects on Cell Proliferation and Apoptosis by Regulating DDR1

Purpose

This research aimed to explore the role of miR-221-5p on the sensitivity of gastric cancer cells to cisplatin, and the proliferation and invasion of gastric cancer cells by regulating DDR1.

Patients and Methods

Altogether 69 patients who treated with radical gastrectomy from January 2014 to January 2016 were collected. With the agree of the patients, 69 gastric carcinoma and 69 adjacent tissues were taken, respectively, during the operation, and gastric carcinoma and human gastric mucosa cells were purchased. RT-PCR was used for detection of the expression level of miR-221-5p and DDR1. Wound healing assay and CCK-8 assay were used for exploration of the cell migration and viability. Western blot and double luciferase reporter gene were performed to determine the target gene of miR-221-5p.

Results

It was showed that miR-221-5p expression was decreased in GC tissues and cell lines. The high expression of miR-221-5p reduced the resistance of GC cells to cisplatin and inhibited the proliferation and migration of gastric cancer cells. The high expression of miR-221-5p promoted the proliferation, invasion and migration of GC cells. In addition, we found that DDR1 was a direct target gene of miR-221-5p in GC cells. We found that DDR1 expression increased in gastric carcinoma. Moreover, there was a negative correlation of DDR1 with the expression level of miR-221-5p. The increase of miR-221-5p increased the chemosensitivity of GC cells to cisplatin, and inhibited the proliferation, invasion, migration and EMT of GC cells by targeting DDR1.

Conclusion

The above research indicated that miR-221-5p may be a target for enhancing cisplatin chemotherapy sensitivity in gastric cancer patients.

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.

microRNAs Tune Oxidative Stress in Cancer Therapeutic Tolerance and Resistance

Relapsed disease following first-line therapy remains one of the central problems in cancer management, including chemotherapy, radiotherapy, growth factor receptor-based targeted therapy, and immune checkpoint-based immunotherapy. Cancer cells develop therapeutic resistance through both intrinsic and extrinsic mechanisms including cellular heterogeneity, drug tolerance, bypassing alternative signaling pathways, as well as the acquisition of new genetic mutations. Reactive oxygen species (ROSs) are byproducts originated from cellular oxidative metabolism. Recent discoveries have shown that a disabled antioxidant program leads to therapeutic resistance in several types of cancers. ROSs are finely tuned by dysregulated microRNAs, and vice versa. However, mechanisms of a crosstalk between ROSs and microRNAs in regulating therapeutic resistance are not clear. Here, we summarize how the microRNA-ROS network modulates cancer therapeutic tolerance and resistance and direct new vulnerable targets against drug tolerance and resistance for future applications.

Non-coding RNA in drug resistance of gastric cancer

Gastric cancer (GC) is the third leading cause of cancer-related mortality worldwide. The poorly prognosis and survival of GC are due to diagnose in an advanced, non-curable stage and with a limited response to chemotherapy. The acquisition of drug resistance accounts for the majority of therapy failure of chemotherapy in GC patients. Although the mechanisms of anticancer drug resistance have been broadly studied, the regulation of these mechanisms has not been completely understood. Accumulating evidence has recently highlighted the role of non-coding RNAs (ncRNAs), including long non-coding RNAs and microRNAs, in the development and maintenance of drug resistance due to their regulatory features in specific genes involved in the chemoresistant phenotype of GC. We review the literature on ncRNAs in drug resistance of GC. This review summarizes the current knowledge about the ncRNAs’ characteristics, their regulation of the genes involved in chemoresistance and their potential as targeted therapies for personalized treatment in resistant GC.

miR-361 enhances sensitivity to 5-fluorouracil by targeting the FOXM1-ABCC5/10 signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of most common malignancies worldwide. 5-fluorouracil (5-FU) is a mainstay of CRC treatment, particularly in patients with advanced stages of the disease; however, 5-FU-based chemotherapy is not always effective and may result in progression of the disease. The present study investigated several candidate microRNAs (miRs) in parental and 5-FU-resistant HCT116 and HT29 cells, and identified miR-361 as a novel regulator of chemosensitivity. Overexpression of miR-361 enhanced the 5-FU susceptibility of parental and resistant HCT116 and HT29 cells in vitro. Impaired colony formation capacity and increased cell apoptosis (as determined via flow cytometry) was observed in resistant HCT116 and HT29 cells. Furthermore, forkhead box M1 (FOXM1) was identified as a target gene of miR-361 using a dual-luciferase reporter assay, western blotting and reverse transcription-quantitative PCR. Additionally, FOXM1 knockdown improved the cytotoxicity of 5-FU in resistant CRC. ATP binding cassette subfamily C members 5 and 10 (ABCC5/10) were found to be downstream effectors of miR-361. In conclusion, miR-361 increased chemosensitivity, at least in part, via modulation of FOXM1-ABCC5/10. miR-361 may serve as a potential therapeutic target for patients with CRC.

The microRNA in ventricular remodeling: the miR-30 family

Ventricular remodeling (VR) is a complex pathological process of cardiomyocyte apoptosis, cardiac hypertrophy, and myocardial fibrosis, which is often caused by various cardiovascular diseases (CVDs) such as hypertension, acute myocardial infarction, heart failure (HF), etc. It is also an independent risk factor for a variety of CVDs, which will eventually to damage the heart function, promote cardiovascular events, and lead to an increase in mortality. MicroRNAs (miRNAs) can participate in a variety of CVDs through post-transcriptional regulation of target gene proteins. Among them, microRNA-30 (miR-30) is one of the most abundant miRNAs in the heart. In recent years, the study found that the miR-30 family can participate in VR through a variety of mechanisms, including autophagy, apoptosis, oxidative stress, and inflammation. VR is commonly found in ischemic heart disease (IHD), hypertensive heart disease (HHD), diabetic cardiomyopathy (DCM), antineoplastic drug cardiotoxicity (CTX), and other CVDs. Therefore, we will review the relevant mechanisms of the miR-30 in VR induced by various diseases.

miR‑1 reverses multidrug resistance in gastric cancer cells via downregulation of sorcin through promoting the accumulation of intracellular drugs and apoptosis of cells

Gastric cancer (GC) is one of the most common cancers worldwide and results in the second greatest rate of cancer-associated mortality globally. Multidrug resistance (MDR) often develops during the chemotherapy, resulting in the failure of treatment. To investigate the molecular mechanism of MDR, the roles of microRNA (miR)-1 were studied in GC. Reverse transcription-quantitative polymerase chain reaction and western blotting were used to investigate the expression levels of miR-1 and sorcin in SGC7901/ADM and SGC7901/VCR cell lines. The effect of miR-1 on the half maximal inhibitory concentration (IC₅₀), cell apoptosis rates and drug accumulation was uncovered by MTT assay and flow cytometric analysis. Furthermore, dual-luciferase assay and western blotting were used to determine the target of miR-1 in GC. It was demonstrated that miR-1 was highly downregulated in MDR GC cell lines, including SGC7901/ADM and SGC7901/VCR. Overexpression of miR-1 in MDR GC cells decreased IC₅₀, but increased the cell apoptosis rates and promoted the drug accumulation in cancer cells. Dual-luciferase activity assay indicated that sorcin was the target of miR-1 in GC. In addition, overexpression of sorcin could partially reverse the effect of miR-1 in MDR GC cells. The role of miR-1 in MDR GC cells makes it a potential therapeutic target for a successful clinical outcome.

Induction/reversal of drug resistance in gastric cancer by non-coding RNAs (Review)

Gastric cancer (GC) is one of the most prevalent and malignant types of cancer worldwide. In China, it is the second most common type of cancer and the malignancy with the highest incidence and mortality rate. Chemotherapy for GC is not always effective due to the development of drug resistance. Drug resistance, which is frequently observed in GC, undermines the success rate of chemotherapy and the survival of patients with GC. The dysregulation of non‑coding RNAs (ncRNAs), primarily microRNAs (miRNAs or miRs) and long non‑coding RNAs (lncRNAs), is involved in the development of GC drug resistance via numerous mechanisms. These mechanisms contribute to the involvement of a large and complex network of ncRNAs in drug resistance. In this review, we focus on and summarize the latest research on the specific mechanisms of action of miRNAs and lncRNAs that modulate drug resistance in GC. In addition, we discuss future prospects and clinical applications of ncRNAs as potential targeted therapies against the chemoresistance of GC.

MicroRNA-mediated redox regulation modulates therapy resistance in cancer cells: clinical perspectives

BACKGROUND

Chemotherapy and radiation therapy are the most common types of cancer therapy. The development of chemo/radio-resistance remains, however, a major obstacle. Altered redox balances are among of the main factors mediating therapy resistance. Therefore, redox regulatory strategies are urgently needed to overcome this problem. Recently, microRNAs have been found to act as major redox regulatory factors affecting chemo/radio-resistance. MicroRNAs play critical roles in regulating therapeutic resistance through the regulation of antioxidant enzymes, redox-sensitive signaling pathways, cancer stem cells, DNA repair mechanisms and autophagy.

CONCLUSIONS

Here, we summarize current knowledge on microRNA-mediated redox regulatory mechanisms underlying chemo/radio-resistance. This knowledge may form a basis for a better clinical management of cancer patients.

miR-6852 serves as a prognostic biomarker in colorectal cancer and inhibits tumor growth and metastasis by targeting TCF7

MicroRNAs (miRs) are have been demonstrated to serve important functions in the genesis of human cancer, including colorectal cancer (CRC). The role of miR-6852 in CRC remains unknown. In this study, it was demonstrated that miR-6852 was underexpressed in CRC tissues compared with adjacent normal tissues. Moreover, the expression of miR-6852 was negatively correlated with CRC metastasis, whereas positively correlated with patient prognosis. It was revealed that the overexpression of miR-6852 significantly inhibited the proliferation and invasion of CRC cells. miR-6852 overexpression reduced CRC cells in the S phase. TCF7 was identified to be a direct target of miR-6852 in CRC cells. Overexpression of miR-6852 significantly inhibited the mRNA and protein levels of TCF7 in CRC cells. Furthermore, TCF7 was highly expressed in CRC tissues and cell lines. TCF7 expression was negatively correlated with miR-6852 levels in CRC tissues. Finally, knockdown of TCF7 significantly suppressed the proliferation and invasion of CRC cells. Taken together, the results of the present study indicated that miR-6852 serves as a tumor suppressor in CRC through targeting TCF7.