A Novel Mechanism of Doxorubicin Resistance and Tumorigenesis Mediated by MicroRNA-501-5p-Suppressed BLID

More than 2,500 coding genes in the human reference gene set still have unsettled status

In 2018 we analysed the three main repositories for the human proteome, Ensembl/GENCODE, RefSeq and UniProtKB. They disagreed on the coding status of one of every eight annotated coding genes. The analysis inspired bilateral collaborations between annotation groups. Here we have repeated our analysis with updated versions of the three reference coding gene sets. Superficially, little appears to have changed. Although there are slightly fewer genes predicted as coding overall, the three groups still disagree on the status of 2,606 annotated genes. However, a comparison without read-through genes and immunoglobulin fragments shows that the three reference sets have merged or reclassified more than 700 genes since the last analysis and that just 0.6% of Ensembl/GENCODE coding genes are not also annotated by the other two reference sets. We used eight features indicative of non-coding genes to examine the 21,873 coding genes annotated across the three reference sets. We found that more than 2,000 had one or more potential non-coding features. While some of these genes will be protein coding, we believe that most are likely to be non-coding genes or pseudogenes. Our results suggest that annotators still vastly overestimate the number of true coding genes.

miR-199a and miR-199b facilitate diffuse gastric cancer progression by targeting Frizzled-6

Pathological markers that can monitor the progression of gastric cancer (GC) may facilitate the diagnosis and treatment of patients with diffuse GC (DGC). To identify microRNAs (miRNAs) that can differentiate between early and advanced DGC in the gastric mucosa, miRNA expression profiling was performed using the NanoString nCounter method in human DGC tumors. Ectopic expression of miR-199a and miR-199b (miR-199a/b) in SNU601 human GC cells accelerated the growth rate, viability, and motility of cancer cells and increased the tumor volume and weight in a mouse xenograft model. To study their clinicopathological roles in patients with GC, miR-199a/b levels were measured in human GC tumor samples using in situ hybridization. High miR-199a/b expression level was associated with enhanced lymphovascular invasion, advanced T stage, and lymph-node metastasis. Using the 3'-untranslated region (UTR) luciferase assay, Frizzled-6 (FZD6) was confirmed to be a direct target of miR-199a/b in GC cells. siRNA-mediated depletion of FZD6 enhanced the motility of SNU601 cells, and addback of FZD6 restored cancer cell motility stimulated by miR-199a/b. In conclusion, miR-199a/b promotes DGC progression by targeting FZD6, implying that miR-199a/b can be used as prognostic and diagnostic biomarkers for the disease.

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.

RNU12 inhibits gastric cancer progression via sponging miR-575 and targeting BLID

Gastric cancer (GC) is one of the major causes of cancer deaths with 5-year survival ratio of 20%. RNU12 is one of long noncoding RNAs (lncRNAs) regulating the tumor progression. However, how RNU12 affecting GC is not clear. qRT-PCR was utilized for determining the RNU12 expression in cell lines, 113 cases of paired gastric cancer (GC) and their adjacent normal gastric tissues. The biofunction alterations of RNU12 were assessed by its overexpression or knockdown in GC cells. MTT and cloning assay were assayed for the cell proliferation, the flow cytometry for the detection of cell cycle and the wound healing assay (WHA) and transwell invasion assay (TIA) for examining the migration and invasion of cells. The expressions of a set of genes related proliferation and migration were investigated with the Western Blotting (WB). RNA immunoprecipitation (RIP), biotinylated RNA pull-down and dual luciferase reporter tests were used to detect the interactions of RNU12 with miR-575/BLID. The in vivo proliferation and migration ability of RNU12 infected cells were determined in zebrafish system. This study revealed that RNU12 inhibited proliferation, invasion and metastasis by sponging of miR-575 and regulating the downstream BLID and modulated EMT of GC cells. The RNU12/miR-575/BLID axis is likely to be the prognosis biomarkers and drug targets of GC.

Apigenin alleviates resistance to doxorubicin in breast cancer cells by acting on the JAK/STAT signaling pathway

BACKGROUND

Breast cancer is the most frequent cancer among women. Despite the effectiveness of Doxorubicin (DOX) as a chemotherapeutic for the treatment of breast cancer, the therapy-resistance remains unsolvable. Apigenin is a natural dietary flavonoid with potential anticancer activities. Our study's intention was to evaluate the effect of Apigenin on DOX resistance in MCF-7 cells.

METHODS

DOX-resistant MCF-7 cell line (MCF-7R) was developed by treating MCF-7 cells with increasing concentrations of DOX (0-100 µM). The viability of cell lines was assayed using MTT method. Quantitative polymerase chain reaction method was performed to measure multidrug-resistance 1 (MDR1) gene expression level. The expression of MDR1, Janus kinase 2 (JAK2) and Signal transducer and activator of transcription 3 (STAT3) proteins were determined by western blotting.

RESULTS

MCF-7R cell line showed resistance to DOX in comparison to MCF-7 cells. Apigenin had a significant effect on the reduction of viability of both MCF-7 and MCF-7R cell lines. However, DOX-resistance in the MCF-7 cell line was considerably decreased due to the co-treatment of MCF-7R cells with Apigenin. This natural compound also downregulated the expression of MDR1 at mRNA and protein levels both in resistant and non-resistant cells. Apigenin significantly prohibited the phosphorylation and activation of JAK2 and STAT3 proteins both in MCF-7 and MCF-7R cell lines.

CONCLUSIONS

The present results suggested, for the first time, Apigenin as an ideal therapeutic for ameliorating DOX resistance in breast cancer. These data also proposed a novel mechanism for the anti-resistance activity of Apigenin by regulating the JAK2/STAT3/MDR1 axis.

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.

Gastrointestinal cancer drug resistance: the role of exosomal miRNAs

Resistance of gastrointestinal (GI) cancer cells to therapeutic agents are one of the major problems in treating this type of cancer. Although the exact mechanism of drug resistance has not yet been fully elucidated, various factors have been identified as contributing factors involved in this process. Several studies have revealed the role of exosomes, especially exosomal microRNAs (miRNAs), in GI tumorigenesis, invasion, angiogenesis, and drug resistance. Exosomes, a type of small extracellular vesicles (EVs), are originated from endosomes and are released into the extracellular environment and body fluids by different cell types. Exosomes mediate cell-cell communication by transferring different cargos, including miRNAs, between parent and recipient cells. Therefore, identifying these exosomal miRNAs and their functions in GI cancers might provide new clues to further explore the secret of this process and thus help in drug-resistance management. This review article will discuss the roles of exosomal miRNAs and their mechanisms of action in drug resistance of different types of GI cancer cells (e.g., stomach, esophagus, liver, pancreas, and colon) to therapeutic agents.

The Emerging Role of Exosomes in Cancer Chemoresistance

Chemoresistance is an impending challenge in cancer treatment. In recent years, exosomes, a subtype of extracellular vesicles with a diameter of 40-150 nm in bloodstream and other bio-fluids, have attracted increasing interest. Exosomes contain proteins, nucleic acids, and lipids, which act as important signaling molecules. Many reports indicate that exosomes play critical roles in chemoresistance through intercellular interactions, including drug removal from cells, transfer of drug resistance phenotypes to other cancer cells, and the increase in plastic stem cell subsets. Exosomes can reflect the physiological and pathological state of parent cells. Owing to their elevated stability, specificity, and sensitivity, exosomes are served as biomarkers in liquid biopsies to monitor cancer chemoresistance, progression, and recurrence. This review summarizes the exosome-mediated mechanisms of cancer chemoresistance, as well as its role in reversing and monitoring chemoresistance. The scientific and technological challenges and future applications of exosomes are also explored.

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.

Role of Exosomal Non-coding RNAs in Gastric Cancer: Biological Functions and Potential Clinical Applications

Gastric cancer (GC) is one of the most common fatal cancers worldwide. The communication between GC and other cells in the GC microenvironment directly affects GC progression. Recently, exosomes have been revealed as new players in intercellular communication. They play an important role in human health and diseases, including cancer, owing to their ability to carry various bioactive molecules, including non-coding RNAs (ncRNAs). NcRNAs, including micro RNAs, long non-coding RNAs, and circular RNAs, play a significant role in various pathophysiological processes, especially cancer. Increasing evidence has shown that exosomal ncRNAs are involved in the regulation of tumor proliferation, invasion, metastasis, angiogenesis, immune regulation, and treatment resistance in GC. In addition, exosomal ncRNAs have promising potential as diagnostic and prognostic markers for GC. Considering the biocompatibility of exosomes, they can also be used as biological carriers for targeted therapy. This review summarizes the current research progress on exosomal ncRNAs in gastric cancer, focusing on their biological role in GC and their potential as new biomarkers for GC and therapeutics. Our review provides insight into the mechanisms involved in GC progression, which may provide a new point cut for the discovery of new diagnostic markers and therapeutic strategies.

The Emerging Role of Liquid Biopsy in Gastric Cancer

(1) Background: Liquid biopsy (LB) is a novel diagnostic method with the potential of revolutionizing the prevention, diagnosis, and treatment of several solid tumors. The present paper aims to summarize the current knowledge and explore future possibilities of LB in the management of metastatic gastric cancer. (2) Methods: This narrative review examined the most recent literature on the use of LB-based techniques in metastatic gastric cancer and the current LB-related clinical trial landscape. (3) Results: In gastric cancer, the detection of circulating cancer cells (CTCs) has been recognized to have a prognostic role in all the disease stages. In the setting of localized disease, cell-free DNA (cfDNA) and circulating tumor DNA (ctDNA) qualitative and quantitative detection have the potential to inform on the risk of cancer recurrence and metastatic dissemination. In addition, gastric cancer-released exosomes may play an essential part in metastasis formation. In the metastatic setting, the levels of cfDNA show a positive correlation with tumor burden. There is evidence that circulating tumor microemboli (CTM) in the blood of metastatic patients is an independent prognostic factor for shorter overall survival. Gastric cancer-derived exosomal microRNAs or clonal mutations and copy number variations detectable in ctDNA may contribute resistance to chemotherapy or targeted therapies, respectively. There is conflicting and limited data on CTC-based PD-L1 verification and cfDNA-based Epstein-Barr virus detection to predict or monitor immunotherapy responses. (4) Conclusions: Although preliminary studies analyzing LBs in patients with advanced gastric cancer appear promising, more research is required to obtain better insights into the molecular mechanisms underlying resistance to systemic therapies. Moreover, validation and standardization of LB methods are crucial before introducing them in clinical practice. The feasibility of repeatable, minimally invasive sampling opens up the possibility of selecting or dynamically changing therapies based on prognostic risk or predictive biomarkers, such as resistance markers. Research is warranted to exploit a possible transforming area of cancer care.

The role of miRNAs and lncRNAs in conferring resistance to doxorubicin

Doxorubicin is a chemotherapeutic agent that inhibits topoisomerase II, intercalates within DNA base pairs and results in oxidative DNA damage, thus inducing cell apoptosis. Although it is effective in the treatment of a wide range of human cancers, the emergence of resistance to this drug can increase tumour growth and impact patients' survival. Numerous molecular mechanisms and signalling pathways have been identified that induce resistance to doxorubicin via stimulation of cell proliferation, cell cycle switch and preclusion of apoptosis. A number of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) have also been identified that alter sensitivity to doxorubicin. Understanding the particular impact of these non-coding RNAs in conferring resistance to doxorubicin has considerable potential to improve selection of chemotherapeutic regimens for cancer patients. Moreover, modulation of expression of these transcripts is a putative strategy for combating resistance. In the current paper, the influence of miRNAs and lncRNAs in the modification of resistance to doxorubicin is discussed.

Clinical crosstalk between microRNAs and gastric cancer (Review)

Globally, there were over 1 million new gastric cancer (GC) patients in 2018 and GC has become the sixth most common cancer worldwide. GC caused 783,000 deaths worldwide in 2018, making it the third most deadly cancer type. miRNAs are short (~22 nucleotides in length) non‑coding RNA molecules, which can regulate gene expression passively at a post‑transcriptional level. There are more and more in‑depth studies on miRNAs. There are numerous conclusive evidences that there is an inseparable link between miRNAs and GC. miRNAs can affect the entire process of GC, including the oncogenesis, development, diagnosis, treatment and prognosis of GC. Although many miRNAs have been linked to GC, few can be applied to clinical practice. This review takes the clinical changes of GC as a clue and summarizes the miRNAs related to GC that have confirmed the mechanism of action in the past three years. Through in‑depth study and understanding of the mechanism of those miRNAs, we predict their possible clinical uses, and suggest some new insights to overcome GC.

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 in Gastric Cancer Development: Mechanisms and Biomarkers

Gastric cancer (GC) is one of the most common and difficult diseases to treat. The study of signaling pathway regulation by microRNA provides information on the mechanisms of GC development and is the basis for biomarker creation. In this study, a circuit of microRNA interactions with signaling pathways was constructed. The microRNAs, associated with metastasis and chemoresistance, are described. In most cases, microRNAs in GC regulate the Wnt/β-catenin, PI3K/AKT/mTOR, RAS/RAF/ERK/MAPK, NF-kB, TGF-β, and JAK/STAT pathways. Part of the microRNA acts on several target genes that function in different pathways. This often leads to an intensification of the induced processes. MicroRNAs have also been described that have the opposite effect on different pathways, causing different functional consequences. By acting on several target genes, or genes associated with several pathways, microRNAs can function in a signaling network. MicroRNAs associated with metastasis most often interact with the Wnt/β-catenin pathway. MicroRNAs affecting chemoresistance, in most cases, affect the regulators of apoptosis and are associated with the PI3K/AKT/mTOR pathway. The characteristics of microRNAs proposed as candidates for GC biomarkers were analyzed. The currently developed diagnostic and prognostic panels of microRNAs are also considered.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

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.

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.

Effects of BCc1 nanoparticle and its mixture with doxorubicin on survival of murine 4T1 tumor model

Background: Our previous findings showed that BCc1, a nanoparticle designed based on nanochelating technology, can be considered a new anti-cancer nanoparticle if confirmed by complementary studies.

Goal: In the present study, we investigated the effects of the BCc1 nanoparticle alone on some gene expressions influencing the apoptosis pathway, and also the effect of the mixture of BCc1 nanoparticle and doxorubicin on survival.

Method: Using an in vitro study, the effects of the BCc1 nanoparticle on Bax, Bcl2, p53, Caspase7 and p21 gene expressions were assessed after a 24-h treatment using real-time PCR in MCF-7 and MEFs; in addition, using an in vivo study, 4T1 tumor-bearing female Balb/c mice were treated with different doses of the BCc1 nanoparticle and doxorubicin alone and together and then their mean and median survival was evaluated.

Result: The results showed that the BCc1 nanoparticle increased gene expressions of RB, p53, Caspase7, p21, and Bax and decreased gene expressions of Bcl2 in MCF-7 significantly, but no change was observed in MEFs expressions. The findings revealed that the BCc1 nanoparticle, when used orally, had the highest mean and median survival time. A mixture of a high dose of the BCc1 nanoparticle (1 mg/kg) and a low dose of doxorubicin (0.1 mg/kg) showed synergistic effects on enhanced life span, while doxorubicin dose was prescribed approximately 50 times less than the murine applicable dose (5 mg/kg).

Conclusion: Our results demonstrated that the BCc1 nanoparticle not only has the potential to become a novel nanomedicine for cancer therapy, but it can also provide the basis of a new medicine for cancer management when mixed with a lower applicable dose of doxorubicin.

Exosomal transfer of miR-501 confers doxorubicin resistance and tumorigenesis via targeting of BLID in gastric cancer

Exosomal transfer of oncogenic miRNAs can enhance recipient cell growth, metastasis and chemoresistance. Currently we found that microRNA-501-5p (miR-501) was overexpressed in doxorubicin-resistant gastric cancer (GC) SGC7901/ADR cell-secreted exosomes (ADR Exo) than that in SGC7901 cell-secreted exosomes (7901 Exo). ADR Exo was internalized by SGC7901, and a Cy3-miR-501 mimic was transferred from SGC7901/ADR to SGC7901 via exosomes. ADR Exo conferred doxorubicin resistance, proliferation, migration and invasion abilities to negative control miRNA inhibitor-expressing GC cells, whereas it inhibited apoptosis. MiR-501 knockdown or BH3-like motif-containing protein, cell death inducer (BLID) overexpression could reverse the effects of ADR Exo on recipient cells. SGC7901 cells cocultured with SGC7901/ADR prior to treatment with GW4869 or transfection of a miR-501 inhibitor were sensitive to doxorubicin and exhibited attenuated proliferation, migration and invasion and increased apoptosis. The intratumoral injection of ADR Exo into negative control miRNA inhibitor-expressing SGC7901 cells induced rapid subcutaneous tumor growth and resistance to doxorubicin compared to that of miR-501 knockdown or BLID-overexpressing cells. This effect is possibly achieved by exosomal miR-501-induced downregulation of BLID, subsequent inactivation of caspase-9/-3 and phosphorylation of Akt. Exosomal miR-501 might be a therapeutic target for GC.