Transcriptomic Characterization, Chemosensitivity and Regulatory Effects of Exosomes in Spontaneous EMT/MET Transitions of Breast Cancer Cells

Research progress of exosomes in drug resistance of breast cancer

Since breast cancer is a heterogeneous disease, there are currently a variety of treatment methods available, including chemotherapy, endocrine therapy, molecular targeted therapy, immunotherapy, radiation therapy, etc. Breast cancer recurrence and metastasis, despite many treatment modalities, constitute a considerable threat to patients' survival time and pose a clinical challenge that is difficult to tackle precisely. Exosomes have a very special and crucial role in the treatment of drug resistance in breast cancer as a carrier of intercellular communication in the tumor microenvironment. Exosomes and breast cancer treatment resistance have been linked in a growing number of clinical investigations in recent years. This paper covers the status of research on exosomes in the treatment of breast cancer drug resistance and offers theoretical guidance for investigating new strategies to treat breast cancer drug resistance.

The role of exosomes in cancer-related programmed cell death

Cancer arises from the growth and division of uncontrolled erroneous cells. Programmed cell death (PCD), or regulated cell death (RCD), includes natural processes that eliminate damaged or abnormal cells. Dysregulation of PCD is a hallmark of cancer, as cancer cells often evade cell death and continue to proliferate. Exosomes nanoscale extracellular vesicles secreted by different types of cells carrying a variety of molecules, including nucleic acids, proteins, and lipids, to have indispensable role in the communication between cells, and can influence various cellular processes, including PCD. Exosomes have been shown to modulate PCD in cancer cells by transferring pro- or antideath molecules to neighboring cells. Additionally, exosomes can facilitate the spread of PCD to surrounding cancer cells, making them promising in the treatment of various cancers. The exosomes' diagnostic potential in cancer is also an active area of research. Exosomes can be isolated from a wide range of bodily fluids and tissues, such as blood and urine, and can provide a noninvasive way to monitor cancer progression and treatment response. Furthermore, exosomes have also been employed as a delivery system for therapeutic agents. By engineering exosomes to carry drugs or other therapeutic molecules, they can be targeted specifically to cancer cells, reducing toxicity to healthy tissues. Here, we discussed exosomes in the diagnosis and prevention of cancers, tumor immunotherapy, and drug delivery, as well as in different types of PCD.

Improving targeted small molecule drugs to overcome chemotherapy resistance

BACKGROUND

Conventional cancer treatments face the challenge of therapeutic resistance, which causes poor treatment outcomes. The use of combination therapies can improve treatment results in patients and is one of the solutions to overcome this challenge. Chemotherapy is one of the conventional treatments that, due to the non-targeted and lack of specificity in targeting cancer cells, can cause serious complications in the short and long-term for patients by damaging healthy cells. Also, the employment of a wide range of strategies for chemotherapy resistance by cancer cells, metastasis, and cancer recurrence create serious problems to achieve the desired results of chemotherapy. Accordingly, targeted therapies can be used as a combination treatment with chemotherapy to both cause less damage to healthy cells, which as a result, they reduce the side effects of chemotherapy, and by targeting the factors that cause therapeutic challenges, can improve the results of chemotherapy in patients.

RECENT FINDINGS

Small molecules are one of the main targeted therapies that can be used for diverse targets in cancer treatment due to their penetration ability and characteristics. However, small molecules in cancer treatment are facing obstacles that a better understanding of cancer biology, as well as the mechanisms and factors involved in chemotherapy resistance, can lead to the improvement of this type of major targeted therapy.

CONCLUSION

In this review article, at first, the challenges that lead to not achieving the desired results in chemotherapy and how cancer cells can be resistant to chemotherapy are examined, and at the end, research areas are suggested that more focusing on them, can lead to the improvement of the results of using targeted small molecules as an adjunctive treatment for chemotherapy in the conditions of chemotherapy resistance and metastasis of cancer cells.

The Prognosis of Cancer Depends on the Interplay of Autophagy, Apoptosis, and Anoikis within the Tumor Microenvironment

Within the tumor microenvironment, the fight between the immune system and cancer influences tumor transformation. Metastasis formation is an important stage in the progression of cancer. This process is aided by cellular detachment and resistance to anoikis, which are achieved by altering intercellular signaling. Autophagy, specifically pro-survival autophagy, aids cancer cells in developing treatment resistance. Numerous studies have shown that autophagy promotes tumor growth and resistance to anoikis. To regulate protective autophagy, cancer-related genes phosphorylate both pro- and anti-apoptotic proteins. Apoptosis, a type of controlled cell death, eliminates damaged or unwanted cells. Anoikis is a type of programmed cell death in which cells lose contact with the extracellular matrix. The dysregulation of these cellular pathways promotes tumor growth and spread. Apoptosis, anoikis, and autophagy interact meticulously and differently depending on the cellular circumstances. For instance, autophagy can protect cancer cells from apoptosis by removing cellular components that are damaged and might otherwise trigger apoptotic pathways. Similarly, anoikis dysregulation can trigger autophagy by causing cellular harm and metabolic stress. In order to prevent or treat metastatic disease, specifically, targeting these cellular mechanisms may present a promising prospect for cancer therapy. This review discourses the state of our understanding of the molecular and cellular mechanisms underlying tumor transformation and the establishment of metastatic tumors. To enhance the prognosis for cancer, we highlight and discuss potential therapeutic approaches that target these processes and genes involved in them.

The role of extracellular vesicles in circulating tumor cell-mediated distant metastasis

Current research has demonstrated that extracellular vesicles (EVs) and circulating tumor cells (CTCs) are very closely related in the process of distant tumor metastasis. Primary tumors are shed and released into the bloodstream to form CTCs that are referred to as seeds to colonize and grow in soil-like distant target organs, while EVs of tumor and nontumor origin act as fertilizers in the process of tumor metastasis. There is no previous text that provides a comprehensive review of the role of EVs on CTCs during tumor metastasis. In this paper, we reviewed the mechanisms of EVs on CTCs during tumor metastasis, including the ability of EVs to enhance the shedding of CTCs, protect CTCs in circulation and determine the direction of CTC metastasis, thus affecting the distant metastasis of tumors.

Role of identified proteins in the proteome profiles of CDK4/6 inhibitor-resistant breast cancer cell lines

Abemaciclib (Ab) and palbociclib (Pb) are CDK4/6 inhibitors used to cure advanced breast cancer (BC). However, acquired resistance is a major challenge. The molecular mechanisms and signature proteins of therapy resistance for Ab and Pb drugs need to be explored. Here we developed resistant cells for Ab and Pb drugs in MCF-7 cell lines and explored the mechanisms and signature proteins of therapy resistance in BC. Proteome profiling was performed using the label-free proteome-orbitrap-fusion-MS-MS technique. Gene ontology (GO)-terms, KEGG pathways and network analysis were performed for the proteome data. Drug-resistant cells showed increased drug tolerance, enhanced colony formation potential and an increased gap-healing tendency for the respective drug. Up-regulation of survival genes (BCL-2 and MCL-1) and down-regulation of apoptosis inducers were observed. Drug-resistance markers (MDR-1 and ABCG2 (BCRP)) along with ESR-1, CDK4, CDK6, and cyclin-D1 genes were up-regulated in resistant cells. A total of 237 and 239 proteins were found to be differentially expressed in the Ab and Pb-resistant cells, respectively. Down-regulated proteins induce apoptosis signalling and nucleotide metabolisms and restrict EGFR signalling; however, up-regulated proteins induce Erk, wnt-β-catenin, VEGFR-PI3K-AKT, glucose transportation, and hypoxia signalling pathways and regulate hydrogen peroxide signalling pathways. The panel of identified proteins associated with these pathways might have characteristics of molecular signature and new drug targets for overcoming drug resistance in breast cancer.

PLGA Nanoparticles Containing VCAM-1 Inhibitor Succinobucol and Chemotherapeutic Doxorubicin as Therapy against Primary Tumors and Their Lung Metastases

The treatment of malignant tumors is usually accompanied by poor prognosis due to metastasis of tumor cells. Hence, it is crucial to enhance anti-metastasis efficacy when anti-tumor treatments are conducted. It has been reported that the vascular cell adhesion molecule-1 (VCAM-1) is highly expressed on the surface of tumor cells and plays an essential role in the metastasis of tumor cells. Thus, reducing VCAM-1 expression offers hope for inhibiting the metastasis of tumor cells. Evidence has shown that succinobucol (Suc) can selectively and efficiently inhibit VCAM-1 expression. Inspired by these, we designed dual drug-loaded PLGA nanoparticles (Co-NPs) to co-deliver VCAM-1 inhibitor Suc and the chemotherapeutic doxorubicin (Dox) which could both effectively suppress primary melanoma and its lung metastases. Co-NPs were composed of PLGA encapsulated Suc and Dox as hydrophobic cores and DSPE-mPEG₂₀₀₀ as surface modification materials. With an appropriate particle size (122.4 nm) and a negatively charged surface (-6.77 mV) we could achieve prolonged blood circulation. The in vitro experiments showed that Co-NPs had potent cytotoxicity against B16F10 cells and could significantly inhibit VCAM-1 expression and migration of B16F10 cells. Additionally, the in vivo experiments showed that Co-NPs could efficiently suppress not only primary melanoma but also its lung metastases. In conclusion, PLGA nanoparticles containing VCAM-1 inhibitor Suc and chemotherapeutic Dox as therapy against primary tumors and their lung metastases provides a promising drug delivery strategy for the treatment of metastatic malignant tumors.

Tumor-Derived Exosomes Modulate Primary Site Tumor Metastasis

Tumor-derived exosomes (TDEs) are actively produced and released by tumor cells and carry messages from tumor cells to healthy cells or abnormal cells, and they participate in tumor metastasis. In this review, we explore the underlying mechanism of action of TDEs in tumor metastasis. TDEs transport tumor-derived proteins and non-coding RNA to tumor cells and promote migration. Transport to normal cells, such as vascular endothelial cells and immune cells, promotes angiogenesis, inhibits immune cell activation, and improves chances of tumor implantation. Thus, TDEs contribute to tumor metastasis. We summarize the function of TDEs and their components in tumor metastasis and illuminate shortcomings for advancing research on TDEs in tumor metastasis.

Targeting polarized phenotype of microglia via IL6/JAK2/STAT3 signaling to reduce NSCLC brain metastasis

Tumor-associated macrophages have emerged as crucial factors for metastases. Microglia are indispensable components of the brain microenvironment and play vital roles in brain metastasis (BM). However, the underlying mechanism of how activated microglia promote brain metastasis of non-small cell lung cancer (NSCLC) remains elusive. Here, we purified cell lines with brain-metastatic tropism and employed a co-culture system to reveal their communication with microglia. By single-cell RNA-sequencing and transcriptome difference analysis, we identified IL6 as the key regulator in brain-metastatic cells (A549-F3) to induce anti-inflammatory microglia via JAK2/STAT3 signaling, which in turn promoted the colonization process in metastatic A549-F3 cells. In our clinical samples, patients with higher levels of IL6 in serum showed higher propensity for brain metastasis. Additionally, the TCGA (The Cancer Genome Atlas) data revealed that NSCLC patients with a lower level of IL6 had a longer overall survival time compared to those with a higher level of IL6. Overall, our data indicate that the targeting of IL6/JAK2/STAT3 signaling in activated microglia may be a promising new approach for inhibiting brain metastasis in NSCLC patients.

Ferroptosis Activation Scoring Model Assists in Chemotherapeutic Agents’ Selection and Mediates Cross-Talk With Immunocytes in Malignant Glioblastoma

Gliomas are aggressive tumors in the central nervous system and glioblastoma is the most malignant type. Ferroptosis is a programmed cell death that can modulate tumor resistance to therapy and the components of tumor microenvironment. However, the relationship between ferroptosis, tumor immune landscape, and glioblastoma progression is still elusive. In this work, data from bulk RNA-seq analysis, single cell RNA-seq analysis, and our own data (the Xiangya cohort) are integrated to reveal their relationships. A scoring system is constructed according to ferroptosis related gene expression, and high scoring samples resistant to ferroptosis and show worse survival outcome than low scoring samples. Notably, most of the high scoring samples are aggressive glioblastoma subtype, mesenchymal, and classical, by calculating RNA velocity. Cross-talk between high scoring glioblastoma cells and immunocytes are explored by R package ‘celltalker’. Ligand–receptor pairs like the TRAIL or TWEAK signaling pathway are identified as novel bridges implying how ferroptosis modulate immunocytes’ function and shape tumor microenvironment. Critically, potential drugs target to high scoring samples are predicted, namely, SNX2112, AZ628, and bortezomib and five compounds from the CellMiner database. Taken together, ferroptosis associates with glioblastoma aggressiveness, cross-talk with immunocytes and offer novel chemotherapy strategy.

Breast Cancer Stem Cell-Derived ANXA6-Containing Exosomes Sustain Paclitaxel Resistance and Cancer Aggressiveness in Breast Cancer

Continuous chemotherapy pressure-elicited annexin-A6 (ANXA6)-containing exosome (ANXA6-exo) secretion contributes to paclitaxel (PTX) resistance in breast cancer (BC), but the molecular mechanisms are not fully elucidated. The present study managed to investigate this issue and found that ANXA6-exo promoted PTX resistance and cancer progression in BC cells in a Yes-associated protein 1 (YAP1)-dependent manner. Specifically, the parental PTX-sensitive BC (PS-BC) cells were exposed to continuous low-dose PTX to generate PTX-resistant BC (PR-BC) cells, and we found that BC stem cells tended to be enriched in the descendent PR-BC cells in contrast with the PS-BC cells. In addition, PR-BC cell-derived exosomes were featured with highly expressed ANXA6, and ANXA6-exo delivered ANXA6 to promote cell migration, growth, autophagy, and stemness in PS-BC cells. Interestingly, ANXA6-exo increased PTX resistance in PS-BC cells via inducing autophagy, and the effects of ANXA6-exo on PTX resistance in PS-BC cells were abrogated by co-treating cells with the autophagy inhibitor 3-methyladenine. Moreover, the underlying mechanisms were uncovered, and we evidenced that ANXA6-exo up-regulated YAP1 to promote Hippo pathway dysregulation, and the promoting effects of ANXA6-exo on PTX resistance and cancer aggressiveness in BC cells were abrogated by silencing YAP1. Taken together, this study firstly elucidated the underlying mechanisms by which BCSC-derived ANXA6-exo facilitated BC progression and PTX resistance, which might help to develop novel treatment strategies for BC in clinic.

Conservation of Epithelial-to-Mesenchymal Transition Process in Neural Crest Cells and Metastatic Cancer

Epithelial to mesenchymal transition (EMT) is a highly conserved cellular process in several species, from worms to humans. EMT plays a fundamental role in early embryogenesis, wound healing, and cancer metastasis. For neural crest cell (NCC) development, EMT typically results in forming a migratory and potent cell population that generates a wide variety of cell and tissue, including cartilage, bone, connective tissue, endocrine cells, neurons, and glia amongst many others. The degree of conservation between the signaling pathways that regulate EMT during development and metastatic cancer (MC) has not been fully established, despite ample studies. This systematic review and meta-analysis dissects the major signaling pathways involved in EMT of NCC development and MC to unravel the similarities and differences. While the FGF, TGFβ/BMP, SHH, and NOTCH pathways have been rigorously investigated in both systems, the EGF, IGF, HIPPO, Factor Receptor Superfamily, and their intracellular signaling cascades need to be the focus of future NCC studies. In general, meta-analyses of the associated signaling pathways show a significant number of overlapping genes (particularly ligands, transcription regulators, and targeted cadherins) involved in each signaling pathway of both systems without stratification by body segments and cancer type. Lack of stratification makes it difficult to meaningfully evaluate the intracellular downstream effectors of each signaling pathway. Finally, pediatric neuroblastoma and melanoma are NCC-derived malignancies, which emphasize the importance of uncovering the EMT events that convert NCC into treatment-resistant malignant cells.

Exosomes and breast cancer drug resistance

Drug resistance is a daunting challenge in the treatment of breast cancer (BC). Exosomes, as intercellular communicative vectors in the tumor microenvironment, play an important role in BC progression. With the in-depth understanding of tumor heterogeneity, an emerging role of exosomes in drug resistance has attracted extensive attention. The functional proteins or non-coding RNAs contained in exosomes secreted from tumor and stromal cells mediate drug resistance by regulating drug efflux and metabolism, pro-survival signaling, epithelial–mesenchymal transition, stem-like property, and tumor microenvironmental remodeling. In this review, we summarize the underlying associations between exosomes and drug resistance of BC and discuss the unique biogenesis of exosomes, the change of exosome cargo, and the pattern of release by BC cells in response to drug treatment. Moreover, we propose exosome as a candidate biomarker in predicting and monitoring the therapeutic drug response of BC and as a potential target or carrier to reverse the drug resistance of BC.

Metabolic Constrains Rule Metastasis Progression

Metastasis formation accounts for the majority of tumor-associated deaths and consists of different steps, each of them being characterized by a distinctive adaptive phenotype of the cancer cells. Metabolic reprogramming represents one of the main adaptive phenotypes exploited by cancer cells during all the main steps of tumor and metastatic progression. In particular, the metabolism of cancer cells evolves profoundly through all the main phases of metastasis formation, namely the metastatic dissemination, the metastatic colonization of distant organs, the metastatic dormancy, and ultimately the outgrowth into macroscopic lesions. However, the metabolic reprogramming of metastasizing cancer cells has only recently become the subject of intense study. From a clinical point of view, the latter steps of the metastatic process are very important, because patients often undergo surgical removal of the primary tumor when cancer cells have already left the primary tumor site, even though distant metastases are not clinically detectable yet. In this scenario, to precisely elucidate if and how metabolic reprogramming drives acquisition of cancer-specific adaptive phenotypes might pave the way to new therapeutic strategies by combining chemotherapy with metabolic drugs for better cancer eradication. In this review we discuss the latest evidence that claim the importance of metabolic adaptation for cancer progression.

The Biology of Exosomes in Breast Cancer Progression: Dissemination, Immune Evasion and Metastatic Colonization

In recent decades, the study of exosome biology has gained growing interest, representing an active area of cancer research with many potential clinical applications. Exosomes are small lipid bilayer particles released by cells with pleiotropic functions that have been reported to regulate the complex intracellular pathway involved in all steps of breast cancer development—from initiation to progression toward a metastatic dissemination. Particularly, the role of these microvesicles has been explored in metastasis, which represents the leading cause of breast cancer morbidity and mortality worldwide. Reports highlight that the plasticity of breast cancer cells, fundamental for the establishment of distant metastasis, may be in part attributed to exosome-carried signals shared between adjacent cells and long-distance cells in the body. In the present review, we will discuss the functions of exosomes in the metastatic breast cancer process and secondary site outgrowth. The possibility to decode the exosome functions in advanced diseases may offer new opportunities for early detection, molecular targeted therapies and exosome-based therapeutics in breast cancer.

Enrichment of CD44 in Exosomes From Breast Cancer Cells Treated With Doxorubicin Promotes Chemoresistance

Exosomes secreted from tumor cells can remodel the tumor environment by promoting tumor metastasis and multidrug resistance. The aim of this study was to analyze the proteome profile of the breast cancer line resistant to doxorubicin resistance (MCF-7/ADR) by liquid chromatography linked to tandem mass spectrometry assay (LC-MS/MS). Our results revealed that DOX increases the exosomes release from MCF-7/ADR cells and the exosome-mediated proteins intercellular transfer in breast cancer chemoresistance regulation. The expression of the candidate target exosomic CD44 in DOX-resistant cells (A/Exo) was higher than in parental breast cancer cells (S/Exo), and the increasing levels of exosomic CD44 (21.65-fold) were higher than those of cellular CD44 (6.55-fold) (all p < 0.05). Similar results were obtained in clinical samples; exosomal CD44 in the serum of nonresponders was significantly higher than that in the chemotherapy-responsive group (p < 0.05). Also, we modified the MCF-7-derived exosomes loaded with siRNA against CD44 to observe the effects of targeting reduced CD44 expression in luminal A breast cancer cells. Exosome-siRNA targeted CD44 (Exos-siCD44) could efficiently silence its expression. When cocultured on Exos-siCD44, breast cancer cells exhibited reduced cell proliferation and enhanced susceptibility to DOX. The same phenomenon was observed in mice. In conclusion, breast cancer cells could spread resistance capacity by the intercellular transfer of proteins, especially CD44, via exosomes.

Role of Exosomal miRNAs and the Tumor Microenvironment in Drug Resistance

Tumor microenvironment (TME) is composed of different cellular populations, such as stromal, immune, endothelial, and cancer stem cells. TME represents a key factor for tumor heterogeneity maintenance, tumor progression, and drug resistance. The transport of molecules via extracellular vesicles emerged as a key messenger in intercellular communication in the TME. Exosomes are small double-layered lipid extracellular vesicles that can carry a variety of molecules, including proteins, lipids, and nucleic acids. Exosomal miRNA released by cancer cells can mediate phenotypical changes in the cells of TME to promote tumor growth and therapy resistance, for example, fibroblast- and macrophages-induced differentiation. Cancer stem cells can transfer and enhance drug resistance in neighboring sensitive cancer cells by releasing exosomal miRNAs that target antiapoptotic and immune-suppressive pathways. Exosomes induce drug resistance by carrying ABC transporters, which export chemotherapeutic agents out of the recipient cells, thereby reducing the drug concentration to suboptimal levels. Exosome biogenesis inhibitors represent a promising adjunct therapeutic approach in cancer therapy to avoid the acquisition of a resistant phenotype. In conclusion, exosomal miRNAs play a crucial role in the TME to confer drug resistance and survivability to tumor cells, and we also highlight the need for further investigations in this promising field.

The Exosome And Breast Cancer Cell Plasticity

Cancer cell plasticity is the ability of cancer cells to reversibly interchange between distinct cell status, which plays a key role in cancer progression. Cancer cell plasticity is now known to be shaped by the secreted nanoparticles termed exosomes which transport proteins and lipids as well as nucleic acids. These aspects have emerged as key determinants of tumor progression and targeting, with approaches such as immunotherapy showing promise in the clinic. While significant strides have been made in this research area, some very interesting questions still warrant more and deeper investigation. We provide a review of the interplay between exosomes and breast cancer cell plasticity, and the potential implication in metastases and drug-resistance.

Proteomic Technology "Lens" for Epithelial-Mesenchymal Transition Process Identification in Oncology

The epithelial-mesenchymal transition (EMT) is a complex transformation process that induces local and distant progression of many malignant tumours. Due to its complex array of proteins that are dynamically over-/underexpressed during this process, proteomic technologies gained their place in the EMT research in the last years. Proteomics has identified new molecular pathways of this process and brought important insights to develop new therapy targets. Various proteomic tools and multiple combinations were developed in this area. Out of the proteomic technology armentarium, mass spectrometry and array technologies are the most used approaches. The main characteristics of the proteomic technology used in this domain are high throughput and detection of minute concentration in small samples. We present herein, using various proteomic technologies, the identification in cancer cell lines and in tumour tissue EMT-related proteins, proteins that are involved in the activation of different cellular pathways. Proteomics has brought besides standard EMT markers (e.g., cell-cell adhesion proteins and transcription factors) other future potential markers for improving diagnosis, monitoring evolution, and developing new therapy targets. Future will increase the proteomic role in clinical investigation and validation of EMT-related biomarkers.

Exosomal MiR-744 Inhibits Proliferation and Sorafenib Chemoresistance in Hepatocellular Carcinoma by Targeting PAX2

BACKGROUND Hepatocellular carcinoma (HCC) is a commonly occurring liver malignancy. Its prognosis remains unsatisfactory. Accumulating evidence has revealed that exosomal microRNAs (miRNAs) act as biomarkers and play crucial roles in the advancement of HCC. The current study explored the biological role and fundamental mechanism of exosomal miR-744 in HCC. MATERIAL AND METHODS The serum exosomes of HCC patients were isolated by differential ultracentrifugation. MiR-744 expression in HCC tissues, cell lines and serum exosomes were detected by quantitative real-time polymerase chain reaction (qRT-PCR). EdU (5-ethynyl-2'-deoxyuridine) assay and Cell Counting Kit-8 (CCK-8) assay were conducted to show the impacts of miR-744 or exosomal miR-744 on proliferation and sorafenib resistance in HepG2 cells. The target of miR-744 was ascertained by regulating the level of miR-744 in HepG2 cells. RESULTS MiR-744 is downregulated in HCC tissues and cell lines as well as in exosomes derived from patient serum and HepG2 cells. Additionally, downregulated miR-744 promotes HepG2 cell proliferation and inhibits the chemosensitivity of HepG2 cells to sorafenib. PAX2 was identified as the functional target of miR-744. Interestingly, miR-744 is decreased in exosomes derived from sorafenib-resistant HepG2 cells. Furthermore, when treated with the miR-744-enriched exosomes, the proliferation of HepG2 cells was significantly suppressed, and the sorafenib resistance was reduced. CONCLUSIONS MiR-744 has an imperative role in the propagation and chemoresistance of HCC. Serum exosomal miR-744 might act as a biomarker of HCC, and exosomal miR-744 might offer an innovative strategy for HCC treatment.