miR‑21‑5p confers doxorubicin resistance in gastric cancer cells by targeting PTEN and TIMP3

Alpha-hederin reprograms multi-miRNAs activity and overcome small extracellular vesicles-mediated paclitaxel resistance in NSCLC

Background: Small extracellular vesicles (sEVs) mediate intercellular communication in the tumor microenvironment (TME) and contribute to the malignant transformation of tumors, including unrestricted growth, metastasis, or therapeutic resistance. However, there is a lack of agents targeting sEVs to overcome or reverse tumor chemotherapy resistance through sEVs-mediated TME reprogramming. Methods: The paclitaxel (PTX)-resistant A549T cell line was used to explore the inhibitory effect of alpha-hederin on impeding the transmission of chemoresistance in non-small cell lung cancer (NSCLC) through the small extracellular vesicles (sEVs) pathway. This investigation utilized the CCK-8 assay and flow cytometry. Transcriptomics, Western blot, oil red O staining, and targeted metabolomics were utilized to evaluate the impact of alpha-hederin on the expression of signaling pathways associated with chemoresistance transmission in NSCLC cells before and after treatment. In vivo molecular imaging and immunohistochemistry were conducted to assess how alpha-hederin influences the transmission of chemoresistance through the sEVs pathway. RT-PCR was employed to examine the expression of miRNA and lncRNA in response to alpha-hederin treatment. Results: The resistance to PTX chemotherapy in A549T cells was overcome by alpha-hederin through its dependence on sEV secretion. However, the effectiveness of alpha-hederin was compromised when vesicle secretion was blocked by the GW4869 inhibitor. Transcriptomic analysis for 463 upregulated genes in recipient cells exposed to A549T-derived sEVs revealed that these sEVs enhanced TGFβ signaling and unsaturated fatty acid synthesis pathways. Alpha-hederin inhibited 15 types of unsaturated fatty acid synthesis by reducing the signaling activity of the sEVs-mediated TGFβ/SMAD2 pathway. Further, we observed that alpha-hederin promoted the production of three microRNAs (miRNAs, including miR-21-5p, miR-23a-3p, and miR-125b-5p) and the sorting to sEVs in A549T cells. These miRNAs targeted the TGFβ/SMADs signaling activity in sEVs-recipient cells and sensitized them to the PTX therapy. Conclusion: Our finding demonstrated that alpha-hederin could sensitize PTX-resistant NSCLC cells by sEV-mediated multiple miRNAs accumulation, and inhibiting TGFβ/SMAD2 pathways in recipient cells.

miRNAs as short non-coding RNAs in regulating doxorubicin resistance

The treatment of cancer patients has been prohibited by chemoresistance. Doxorubicin (DOX) is an anti-tumor compound disrupting proliferation and triggering cell cycle arrest via inhibiting activity of topoisomerase I and II. miRNAs are endogenous RNAs localized in cytoplasm to reduce gene level. Abnormal expression of miRNAs changes DOX cytotoxicity. Overexpression of tumor-promoting miRNAs induces DOX resistance, while tumor-suppressor miRNAs inhibit DOX resistance. The miRNA-mediated regulation of cell death and hallmarks of cancer can affect response to DOX chemotherapy in tumor cells. The transporters such as P-glycoprotein are regulated by miRNAs in DOX chemotherapy. Upstream mediators including lncRNAs and circRNAs target miRNAs in affecting capacity of DOX. The response to DOX chemotherapy can be facilitated after administration of agents that are mostly phytochemicals including curcumol, honokiol and ursolic acid. These agents can regulate miRNA expression increasing DOX's cytotoxicity. Since delivery of DOX alone or in combination with other drugs and genes can cause synergistic impact, the nanoparticles have been introduced for drug sensitivity. The non-coding RNAs determine the response of tumor cells to doxorubicin chemotherapy. microRNAs play a key role in this case and they can be sponged by lncRNAs and circRNAs, showing interaction among non-coding RNAs in the regulation of doxorubicin sensitivity.

Inhibitors of the PI3K/AKT/mTOR pathway in human malignancies; trend of current clinical trials

The phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway regulates proliferation, survival and metabolism, and its dysregulation is one of the most frequent oncogenic events across human malignancies. Over the last two decades, there has been significant focus on the clinical development of PI3K pathway inhibitors. More than 40 different inhibitors of this axis have reached various stages of clinical trials, but only a few of them have been approved by the Food and Drug Administration (FDA) for cancer treatment. These clinical results, however, could be improved given the importance of PI3K signaling in cancer and its role in linking cancer growth with metabolism. In this systematic review, after a glance at PI3K/AKT/mTOR pathway and its different inhibitors, we retrieved registered clinical trials evaluating the efficacy and safety of PI3K/AKT/mTOR inhibitors on Clinicaltrials.gov. Following the extraction of the data, finally we analyzed 2250 included studies in multiple steps, beginning with an overview and moving on to the details about type of malignancies, inhibitors, and treatment strategies. We also took a closer look at more than 100 phase III-IV clinical trials to pinpoint promising therapies, hoping that presenting a comprehensive picture of current clinical trials casts a flash of light on what remains to be done in future clinical trials of PI3K/AKT/mTOR inhibitors in human malignancies.

Integrated multi-omics analyses and functional validation reveal TTK as a novel EMT activator for endometrial cancer

BACKGROUND

Cancer-testis antigens (CTAs) are often expressed in tumor and testicular tissues but not in other normal tissues. To date, there has been no comprehensive study of the expression and clinical significance of CTA genes associated with endometrial cancer (EC) development. Additionally, the clinical relevance, biological role, and molecular mechanisms of the CTA gene TTK protein kinase (TTK) in EC are yet to be fully understood.

METHODS

Using bioinformatics methods, we comprehensively investigated the genomic, transcriptomic, and epigenetic changes associated with aberrant TTK overexpression in EC samples from the TCGA database. We further investigated the mechanisms of the lower survival associated with TTK dysregulation using single-cell data of EC samples from the GEO database. Cell functional assays were used to confirm the biological roles of TTK in EC cells.

RESULTS

We identified 80 CTA genes that were more abundant in EC than in normal tissues, and high expression of TTK was significantly linked with lower survival in EC patients. Furthermore, ROC analysis revealed that TTK could accurately distinguish stage I EC tissues from benign endometrial samples, suggesting that TTK has the potential to be a biomarker for early EC detection. We found TTK overexpression was more prevalent in EC patients with high-grade, advanced tumors, serous carcinoma, and TP53 alterations. Furthermore, in EC tissue, TTK expression showed a strong positive correlation with EMT-related genes. With single-cell transcriptome data, we identified a proliferative cell subpopulation with high expression of TTK and known epithelial-mesenchymal transition (EMT)-related genes and transcription factors. When proliferative cells were grouped according to TTK expression levels, the overexpressed genes in the TTK^high group were shown to be functionally involved in the control of chemoresistance. Utilizing shRNA to repress TTK expression in EC cells resulted in substantial decreases in cell proliferation, invasion, EMT, and chemoresistance. Further research identified microRNA-21 (miR-21) as a key downstream regulator of TTK-induced EMT and chemoresistance. Finally, the TTK inhibitor AZ3146 was effective in reducing EC cell growth and invasion and enhancing the apoptosis of EC cells generated by paclitaxel.

CONCLUSION

Our findings establish the clinical significance of TTK as a new biomarker for EC and an as-yet-unknown carcinogenic function. This present study proposes that the therapeutic targeting of TTK might provide a viable approach for the treatment of EC.

Analysis of the regulatory mechanisms of prognostic immune factors in thyroid cancer

Objective

To explore the regulatory mechanism of immune prognostic factors in thyroid cancer.

Methods

Based on the TCGA database and GEO database, this study used bioinformatics methods to study the potential regulatory mechanism of thyroid cancer prognosis, analyzed the differentially expressed genes and differential miRNAs between thyroid cancer and normal paracancerous tissues by R software, and constructed lasso risk factors. The immune prognostic factors of thyroid cancer were obtained from the model, and the miRDB website was used to predict the possibility of differential miRNA target binding of the immune prognostic factors and correlation analysis was performed, and finally verified by cell experiments.

Results

There were 1413 differentially expressed genes between thyroid cancer and normal paracancerous tissues, among which 21 immune-related genes were prognostic factors with significant differences in expression; lasso risk model obtained AKAP12, APOC1, TIMP3, ADAMTS9, ANK2, HTRA3, SYNDIG1 , ADAMTS5 and DACT1 were nine prognostic factors. A total of 58 differential miRNAs were found in thyroid cancer tissues and non-cancerous tissues. The possibility of differential miRNA targeting and binding of immune prognostic factors on the miRDB website and cell experiments was analyzed.

Conclusions

The potential miRNA regulatory mechanism of immune prognostic factors in thyroid cancer has been explored.

METTL3 m6A-dependently promotes miR-21-5p maturation to accelerate choriocarcinoma progression via the HIF1AN-induced inactivation of the HIF1A/VEGF pathway

BACKGROUND

Gestational choriocarcinoma is a highly malignant neoplastic disease derived from pathological changes in trophoblastic cells. Recent evidences have shown that N6-methyladenosine (m6A) modifications play important role in modulating the development of multiple cancers, but the detailed mechanisms by which m6A-mediated choriocarcinoma progression have not been fully delineated.

OBJECTIVES

This study aimed to investigate the role of m6A in choriocarcinoma and reveal its underlying molecular mechanisms.

METHODS

The expression of METTL3, miR-21-5p and HIF1AN was detected using RT-qPCR in tissues and cells. The protein expression of METTL3, HIF1AN, HIF1A and VEGF were measured by western blot. The luciferase reporter assays and RNA immunoprecipitation (RIP) were used to verify the relationship between miR-21-5p and HIF1AN. The CCK-8, colony formation and transwell assays were used to detected cell proliferation and cell migration, respectively.

RESULTS

Here, we demonstrated that the m6A methyltransferase-like 3 (METTL3) was aberrantly high-expressed in the clinical choriocarcinoma tissues and choriocarcinoma cell lines compared to the corresponding normal counterparts. The following functional experiments verified that silencing of METTL3 suppressed cell proliferation, migration, epithelial-mesenchymal transition (EMT) and tumorigenesis in vitro and in vivo to hamper the aggressiveness of choriocarcinoma. Next, the mechanical experiments confirmed that METTL3 promoted the maturation of miR-21-5p in an m6A-dependent manner, and elevated miR-21-5p subsequently degraded its downstream hypoxia-inducible factor asparagine hydroxylase (HIF1AN) by targeting its 3' untranslated regions (3'-UTR), resulting in the activation of the tumor-promoting HIF1A/VEGF pathway. Finally, the rescuing experiments verified that METTL3 ablation-induced inhibitory effects on the malignant phenotypes in choriocarcinoma were all abrogated by both miR-21-5p overexpression and HIF1AN downregulation.

CONCLUSIONS

Collectively, this study firstly reported the involvement of the METTL3/m6A/miR-21-5p/HIF1AN signaling cascade in regulating the progression of choriocarcinoma, which provided novel biomarkers for the diagnosis and treatment of this disease.

Fuzheng Kang' ai decoction inhibits cell proliferation, migration and invasion by modulating mir-21-5p/human phosphatase and tensin homology deleted on chromosome ten in lung cancer cells

OBJECTIVE

To elucidate the potential molecular mechanism by which Fuzheng Kang'ai decoction (, FZKA) inhibits proliferation, migration, and invasion of lung cancer cells.

METHODS

Varying FZKA concentrations were used to manage lung cancer cells (A549 and PC9). We employed: cell counting kit-8 (CCK-8) and plate clone for-mation assays to examine the cell viability; flow cytometry (FCM) to analyze the cycle arrest; transwell and wound-healing assays to assess the cell invasion and migration, respectively. Further, a quantitative real-time polymerase chain reaction (qRT-PCR) assay was adopted to evaluate the miR-21-5p expression. For protein expression analysis, we employed the Western blot technique. Recombinant miR-21-5p overexpression adenovirus vector harboring GFP was constructed and transfected into A549 and PC9, after which we explored the effect of FZKA on miR-21-5p overexpression.

RESULTS

Notably, treatment with FZKA inhibited viability, clone-formation ability, invasion, and migration of lung cancer cells. Mechanistically, FZKA markedly suppressed miR-21-5p expression but elevated the human phosphatase and tensin homology deleted on chromosome ten (PTEN) protein level in both A549 and PC9 cells. Over-expression of miR-21-5p lowered PTEN protein expression. Besides, overexpressed miR-21-5p levels with adenovirus antagonized FZKA-upregulated PTEN protein expression.

CONCLUSION

The present study demonstrates how FZKA modulates cell biological behaviors, for instance, it impedes the proliferation by upregulating PTEN expression with miR-21-5p as the target. These findings unveil the potential novel molecular mechanisms from the microRNA aspect by which FZKA suppresses the growth of human lung cancer cells.

The Molecular Roles and Clinical Implications of Non-Coding RNAs in Gastric Cancer

Gastric cancer (GC) is one of the most common malignancies in the world. It is also the fifth most common cancer in China. In recent years, a large number of studies have proved that non-coding RNAs (ncRNAs) can regulate cell proliferation, invasion, metastasis, apoptosis, and angiogenesis. NcRNAs also influence the therapeutic resistance of gastric cancer. NcRNAs mainly consist of miRNAs, lncRNAs and circRNAs. In this paper, we summarized ncRNAs as biomarkers and therapeutic targets for gastric cancer, and also reviewed their role in clinical trials and diagnosis. We sum up different ncRNAs and related moleculars and signaling pathway in gastric cancer, like Bcl-2, PTEN, Wnt signaling. In addition, the potential clinical application of ncRNAs in overcoming chemotherapy and radiotherapy resistance in GC in the future were also focused on.

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.

Serum exosomal miRNA from endometriosis patients correlates with disease severity

Purpose

Exosomes are vesicles secreted by cells that contain a wide variety of biomolecules, including proteins or nucleic acids. MicroRNAs (miRNAs), which are commonly found in exosomes, are known to play important roles in the pathophysiology of endometriosis.

Methods

This study investigated the miRNA expression profile of serum exosomes from women with endometriosis in comparison with normal controls as well as the possible role of identified miRNAs in the pathogenesis of endometriosis. Exosomes with a diameter between 60 and 100 nm were identified by their expression of exosomal marker proteins CD9 and CD63.

Results

Microarray miRNA expression profiling analysis revealed that 26 genes were significantly up-regulated and 19 genes were significantly down-regulated in serum exosomes from endometriosis patients compared with normal controls. These differentially expressed miRNAs were mainly enriched in the regulation of cellular development, metabolism, and involved in the regulation of the MAPK and PI3k-Akt pathways. qRT-PCR analysis verified the differential expression of three miRNAs, miR-26b-5p, miR-215-5p, and miR-6795-3p.

Conclusion

Further analysis indicated that these differentially expressed miRNAs in serum exosomes may be involved in the pathogenesis of endometriosis and are related to the severity and certain symptoms of endometriosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06227-z.

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-21 in the Cancers of the Digestive System and Its Potential Role as a Diagnostic, Predictive, and Therapeutic Biomarker

MicroRNAs (miRNAs) are small non-coding RNAs. They can regulate the expression of their target genes, and thus, their dysregulation significantly contributes to the development of cancer. Growing evidence suggests that miRNAs could be used as cancer biomarkers. As an oncogenic miRNA, the roles of miR-21 as a diagnostic and prognostic biomarker, and its therapeutic applications have been extensively studied. In this review, the roles of miR-21 are first demonstrated via its different molecular networks. Then, a comprehensive review on the potential targets and the current applications as a diagnostic and prognostic cancer biomarker and the therapeutic roles of miR-21 in six different cancers in the digestive system is provided. Lastly, a brief discussion on the challenges for the use of miR-21 as a therapeutic tool for these cancers is added.

miR-20b and miR-125a promote tumorigenesis in radioresistant esophageal carcinoma cells

Radiation therapy is an effective method in the management of esophageal cancer. MicroRNAs (miRNAs) have been reported to play an important role in tumorigenesis. However, the roles of specific miRNAs in radioresistant esophageal cancer remain to be investigated. In present study, the relative expression level of miR-20b-5p and miR-125a-5p were evaluated by quantitative Real-time polymerase chain reaction. Cell counting Kit-8 assay, wound-healing assay, transwell assay were used to assess cell proliferation, cell migration and cell invasion. TUNEL and Annexin V-FITC assays were applied to evaluate cell apoptosis. Dual-luciferase reporter gene assay was conducted to identify direct targets of miRNAs. The protein expression level was assessed by Western blot. The results indicated that miR-20b-5p was increased in radioresistant KYSE-150R cells compared with KYSE-150 cells, whereas miR-125a-5p was downregulated. MiR-20b-5p upregulation promoted cell proliferation, migration, invasion, and the EMT process, and decreased apoptosis by negatively regulating PTEN. MiR-125a-5p inhibited cell proliferation, migration, invasion, the EMT process and it induced apoptosis by negatively regulating IL6R. These data indicate that miR-20b-5p and miR-125a-5p promote tumorigenesis in radioresistant KYSE-150R cells and have the potential to be used as novel therapeutic targets for the treatment of esophageal cancer.

Circular RNA circVAPA promotes chemotherapy drug resistance in gastric cancer progression by regulating miR-125b-5p/STAT3 axis

BACKGROUND

Gastric cancer (GC) is a prevalent malignancy, leading to a high incidence of cancer-associated death. Cisplatin (DDP)-based chemotherapy is the principal therapy for clinical GC treatment, but DDP resistance is a severe clinical challenge and the mechanism remains poorly understood. Circular RNAs (circRNAs) have been identified to play crucial roles in modulating the chemoresistance of gastric cancer cells.

AIM

To explore the effect of circVAPA on chemotherapy resistance during GC progression.

METHODS

The effect of circVAPA on GC progression and chemotherapy resistance was analyzed by MTT assay, colony formation assay, Transwell assay, wound healing assay, and flow cytometry analysis in GC cells and DDP resistant GC cell lines, and tumorigenicity analysis in nude mice in vivo. The mechanism was investigated by luciferase reporter assay, quantitative real-time PCR, and Western blot analysis.

RESULTS

CircVAPA expression was up-regulated in clinical GC tissues compared with normal samples. CircVAPA depletion inhibited proliferation, migration, and invasion and increased apoptosis of GC cells. The expression of circVAPA, STAT3, and STAT3 downstream genes was elevated in DDP resistant SGC7901/DDP cell lines. CircVAPA knockdown attenuated the DDP resistance of GC cells. Mechanically, circVAPA was able to sponge miR-125b-5p, and miR-125b-5p could target STAT3 in the GC cells. MiR-125b-5p inhibitor reversed circVAPA depletion-enhanced inhibitory effect of DDP on GC cells, and STAT3 knockdown blocked circVAPA overexpression-induced proliferation of DDP-treated SGC7901/DDP cells. The depletion of STAT3 and miR-125b-5p inhibitor reversed circVAPA depletion-induced GC cell apoptosis. Functionally, circVAPA contributed to the tumor growth of SGC7901/DDP cells in vivo.

CONCLUSION

CircVAPA promotes chemotherapy resistance and malignant progression in GC by miR-125b-5p/STAT3 signaling. Our findings present novel insights into the mechanism by which circVAPA regulates chemotherapy resistance of GC cells. CircVAPA and miR-125b-5p may be considered as the potential targets for GC therapy.

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: Promising Roles in Cancer Therapy

MicroRNAs (miRNA) are small non-coding RNAs that act as one of the main regulators of gene expression. They are involved in maintaining a proper balance of diverse processes, including differentiation, proliferation, and cell death in normal cells. Cancer biology can also be affected by these molecules by modulating the expression of oncogenes or tumor suppressor genes. Thus, miRNA based anticancer therapy is currently being developed either alone or in combination with chemotherapy agents used in cancer management, aiming at promoting tumor regression and increasing cure rate. Access to large quantities of RNA agents can facilitate RNA research and development. In addition to currently used in vitro methods, fermentation-based approaches have recently been developed, which can cost-effectively produce biological RNA agents with proper folding needed for the development of RNA-based therapeutics. Nevertheless, a major challenge in translating preclinical studies to clinical for miRNA-based cancer therapy is the efficient delivery of these agents to target cells. Targeting miRNAs/anti-miRNAs using antibodies and/or peptides can minimize cellular and systemic toxicity. Here, we provide a brief review of miRNA in the following aspects: biogenesis and mechanism of action of miRNAs, the role of miRNAs in cancer as tumor suppressors or oncogenes, the potential of using miRNAs as novel and promising therapeutics, miRNA-mediated chemo-sensitization, and currently utilized methods for the in vitro and in vivo production of RNA agents. Finally, an update on the viral and non-viral delivery systems is addressed.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

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.

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.

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.

TIMP-3 as a therapeutic target for cancer

Tissue inhibitor of metalloproteinase-3 (TIMP-3), a secreted glycoprotein, plays an important role in carcinogenesis. It can bind to many proteinases to suppress their activity and thus protect the extracellular matrix from degradation. TIMP-3 may have many anticancer properties, including apoptosis induction and antiproliferative, antiangiogenic, and antimetastatic activities. This review summarizes the structure, proteinase inhibition ability, genetic and epigenetic regulation, cancer therapy potential, and contribution to cancer development of TIMP-3. Furthermore, in this review we discuss its potential as a biomarker for predicting cancer progression and the current state of drugs that target TIMP-3, either alone or in combination with clinical treatment. In conclusion, TIMP-3 can be a biomarker of cancer and a potential target for cancer therapy. This review article can serve as a basis to understand how to modulate TIMP-3 levels as a drug target of cancers.

MiR-21/PTEN signaling modulates the chemo-sensitivity to 5-fluorouracil in human lung adenocarcinoma A549 cells

An aberrant expression of microRNA-21 (miR-21) has been found in multiple human cancers, including lung carcinoma. Our work aims at investigating the role of miR-21 in human lung adenocarcinoma A549 cells and cells treated with 5-fluorouracil and their potential molecular mechanisms. A549 cells were transfected with an miR-21 mimic, an miR-21 inhibitor, and their respective negative controls using Lipofectamine 2000. Real-time quantitative PCRs (qRT-PCRs) was applied to evaluate the cells' miR-21 expression levels. EdU incorporation and a cell viability assay were used to confirm the cell proliferation. Flow cytometry was performed to analyze the effects of miR-21 on the A549 cell cycle determination. Using fl ow cytometry and western blot analysis, we measured the A549 cell apoptosis and necrosis and the potential mechanism. Our findings demonstrated that the overexpression of miR-21 decreased 5-fluorouracil-induced apoptosis and necrosis, and the opposite effects were obtained by the suppression of miR-21. Further, we found that the phosphatase and tensin homologue (PTEN) was regulated by the alteration of miR-21 in A549 cells treated with 5-fluorouracil. Finally, we co-transfected an miR-21 mimic or/and PTEN into A549 cells and found that the anti-apoptotic effects of the miR-21 mimic on the A549 cells could be reversed by overexpressing PTEN. Our present work indicated the involvement of the miR-21/PTEN axis in the 5-fluorouracil-induced cell apoptosis of NSCLC. Therefore, the inhibition of the miRNA-21/PTEN pathway may be a novel therapeutic target to block 5-fluorouracil-induced chemotherapy resistance in NSCLC.

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.