The role of miRNAs in pathogenesis, diagnosis, and therapy of Helicobacter pylori infection, gastric cancer-causing bacteria: Special highlights on nanotechnology-based therapy

Helicobacter pylori (H. pylori) infection and consequent inflammation in the stomach are widely recognized as major contributors to gastric cancer (GC) development. Recent investigations have placed considerable emphasis on uncovering the controlling influence of small RNA molecules known as microRNAs (miRNAs) in H. pylori-related diseases, particularly gastric cancer. This review aims to offer a comprehensive understanding of the intricate roles fulfilled by miRNAs in conditions associated with H. pylori infection. Exploring miRNA biogenesis pathways reveals their intimate connection with H. pylori infection, shedding light on the underlying molecular mechanisms driving disease progression and identifying potential intervention targets. An examination of epidemiological data surrounding H. pylori infection, including prevalence, risk factors, and transmission routes, underscores the imperative for preventive measures and targeted interventions. Incorporating insights from miRNA-related research into these strategies holds promise for enhancing their efficacy in controlling H. pylori spread. The symptoms, underlying mechanisms, and virulent characteristics of the bacteria highlight the intricate relationship between H. pylori and host cells, influencing the course of diseases. Within this complex web, miRNAs play pivotal roles, regulating various facets of H. pylori's development. MicroRNAs intricately involved in directing the immune response against H. pylori infection serve as key players in molding host defense mechanisms and impacting the bacterium's evasion tactics. Utilizing this knowledge holds the potential to drive forward groundbreaking therapeutic strategies. The diagnostic and prognostic capabilities of miRNAs in H. pylori infection highlight their effectiveness as non-invasive indicators for identifying diseases and evaluating risk. Integration of miRNA signatures into diagnostic algorithms holds promise for enhancing early detection and management of H. pylori-related diseases. MiRNA-based therapeutics offer a promising avenue for combatting H. pylori-induced gastric cancer, targeting specific molecular pathways implicated in tumorigenesis. H. pylori infection induces dysregulation of several miRNAs that contribute to antibiotic resistance, inflammation, and gastric cancer progression, including downregulation of tumor-suppressive miR-7 and miR-153 and upregulation of oncogenic miR-671-5p and miR-155-5p, which promote carcinogenesis and inflammation. Additionally, H. pylori manipulates host immune responses by upregulating miRNAs such as let-7f-5p, let-7i-5p, miR-146b-5p, and miR-185-5p that suppress HLA class II expression and antigen presentation, facilitating immune evasion and chronic gastritis that predispose to gastric cancer. Future research endeavors should focus on refining these therapeutic modalities and identifying novel targets to optimize clinical outcomes. By elucidating the multifaceted roles of miRNAs in H. pylori infection, this review provides invaluable insights into disease pathogenesis, diagnostics, and therapeutics, and the role of some nanoparticles in combating the H. pylori infection. Continued research efforts are imperative for translating these insights into clinical practice and addressing the global burden of H. pylori-related diseases.

An Updated Review on Dysregulated lncRNAs and their Contribution to the Various Molecular Types of Lung Carcinoma

Lung cancer is correlated with a high death rate, with approximately 1.8 million mortality cases reported worldwide in 2022. Despite development in the control of lung cancer, most cases are detected at higher stages with short survival rates. This reveals a need to recognize novel techniques to treat malignancy and decrease the burden of lung cancer. Long noncoding RNAs (lncRNAs) manage vital cellular and biochemical functions. lncRNAs play crucial roles in transcriptional and translational processes and signaling cascades. Recently, lncRNAs have been reported to be associated with malignancy where their expression is deregulated, leading to abnormal cellular activities and signaling pathways. In various malignancies, including lung cancer, lncRNA deregulation disrupts normal cellular function, promoting tumorigenesis and influencing patient outcomes and treatment responses. Studies have shown that lncRNAs can act as both oncogenes and tumor suppressors, depending on the lung cancer subtype, specifically in Non-small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC). This dual role of lncRNAs as critical biomarkers might provide insights into lung cancer development and progression. lncRNAs have been discussed as key biomarkers in lung cancer. A comprehensive understanding of the biological activities of lncRNAs in NSCLC and SCLC may improve prognosis, diagnosis, and therapeutic methods. Researchers are increasingly interested in lncRNAs as potential diagnostic biomarkers and therapeutic targets in cancer treatment. As researchers continue to explore lncRNAs, their pivotal roles in lung cancer become increasingly evident. This review highlights the function of lncRNAs in lung carcinogenesis and discusses their molecular mechanisms of function.

Reducing metastasis ability of gastric cancer cell line by targeting MMP16 using miR-193a-5p and 5-FU

PURPOSE

Co-administration of microRNAs and chemotherapy drugs effectively treats several cancers. The current study sought to investigate the function of matrix metalloproteinase 16 (MMP16) and miR-193a-5p in the pathogenesis of gastric cancer (GC).

MATERIALS/METHODS

Sixty-five surgical patients, 15 receiving 5-fluorouracil (5-FU), provided GC and adjacent non-cancerous tissue. Following that, qPCR was used to assess the expression levels of MMP16 and miR-193a-5p in GC cells. The impact of miR-193a-5p and 5-FU administration on MMP16 mRNA expression was evaluated using qRT-PCR and Western blotting. MTT and Scratch tests were also conducted to assess their effects on cell viability and migration. Moreover, a rescue experiment using an MTT assay was performed. Using flow cytometry, the apoptotic rate was calculated. Finally, it was evaluated how MMP16 and miR-193a-5p related to the clinicopathological characteristics of the patients.

RESULTS

The current study found that while MMP16 expression increased in GC patients (P ​< ​0.0001), miR-193a-5p expression significantly decreased (P ​< ​0.001). MMP16 down-regulation was another effect of miR-193a-5p replacement, particularly when 5-FU was added (P ​< ​0.01). In addition, this study found that miR-193a-5p, by concentrating on MMP16, decreased the migration of GC cells brought on by MMP16. In GC cell lines, miR-193 and 5-FU induce apoptosis, with the 5-FU being more pronounced when combined with mir-193, according to flow cytometry results. A strong correlation was also found between clinicopathological traits associated with MMP16 and miR-193a-5p.

CONCLUSIONS

These findings suggest that miR-193a-5p, in conjunction with 5-FU, down-regulates MMP16 in GC, where it suppresses tumor growth.

Three possible diagnostic biomarkers for gastric cancer: miR-362-3p, miR-362-5p and miR-363-5p

Aim: MicroRNAs can be regarded as biomarkers for gastric cancer (GC) diagnosis in the early stages. This study assesses the expression levels of miR-362-3p, miR-362-5p and miR-363-5p as potential biomarkers for GC.Materials & methods: The expression levels of the miRNAs in 90 pairs of GC and adjacent normal tissue samples were analyzed by quantitative real-time reverse transcription PCR (qRT-PCR) and some bioinformatics tools were utilized for analyzing the target genes and possible molecular pathways in which these miRNAs participate.Results & conclusion: There was a significant overexpression of the miRNAs in GC cells and an outstanding correlation between their overexpression with some clinicopathological features of the patients.

Construction of a nomogram for predicting HNSCC distant metastasis and identification of EIF5A as a hub gene

Patients with distant metastasis of head and neck squamous cell carcinoma (HNSCC) often have a poor prognosis. However, early diagnosis of distant metastasis is challenging in clinical practice, and distant metastasis is often only detected in the late stages of tumor metastasis through imaging techniques. In this study, we utilized data from HNSCC patients collected from the TCGA database. Patients were divided into distant metastasis and nonmetastasis groups based on the tumor-node-metastasis (TNM) stage. We analyzed the differentially expressed genes between the two groups (DM/non-M DEGs) and their associated lncRNAs and generated a predictive model based on 23 lncRNAs that were significantly associated with the occurrence of distant metastasis in HNSCC patients. On this basis, we built a nomogram to predict the distant metastasis of HNSCC patients. Moreover, through WGCNA and Cytoscape software analysis of DM/non-M DEGs, we identified the gene most closely related to HNSCC distant metastasis: EIF5A. Our findings were validated using GEO data; EIF5A expression was significantly increased in the tumor tissues of HNSCC patients with distant metastasis. We then predicted miRNAs that can directly bind to EIF5A via the TargetScan and miRWalk websites, intersected them with differentially expressed miRNAs in the two groups from the TCGA cohort, and identified the only overlapping miRNA, miR-424; we predicted the direct binding site of EIF5A and miR-424 via the miRWalk website. Immunohistochemistry further revealed high expression of EIF5A in the primary tumor tissue of HNSCC patients with distant metastasis. These results provide a new perspective for the early diagnosis of distant metastasis in HNSCC patients and the study of the mechanisms underlying HNSCC distant metastasis.

Bibliometric and visualized analysis of global research on microRNAs in gastric cancer: from 2013 to 2023

Gastric cancer (GC) imposes a heavy burden on global public health, and microRNAs (miRNAs) play a crucial role in the diagnosis and treatment of GC. Therefore, it is necessary to clarify the hotspots and frontiers in the field of miRNAs in GC to guide future research. A total of 2,051 publications related to miRNAs in GC from January 2013 to December 2023 were searched from the Web of Science Core Collection database. CiteSpace was used to identify research hotspots and delineate developmental trends. In the past decade, China, Nanjing Medical University, and Ba Yi were the most contributing research country, institute, and author in this field, respectively. The role of miRNAs as biomarkers in GC, the mechanism of miRNAs in the progression of GC, and the impact of the mutual effects between miRNAs and Helicobacter pylori on GC have been regarded as the research hotspots. The mechanisms of miRNAs on glucose metabolism and the application of the roles of circular RNAs as miRNA sponges in GC treatment will likely be frontiers. Overall, this study called for strengthened cooperation to identify targets and therapeutic regimes for local specificity and high-risk GC types, and to promote the translation of research results into clinical practice.

The regulation roles of miRNAs in Helicobacter pylori infection

Helicobacter pylori is a kind of Gram-negative bacteria that parasitizes on human gastric mucosa. Helicobacter pylori infection is very common in human beings, which often causes gastrointestinal diseases, including chronic gastritis, duodenal ulcer and gastric cancer. MicroRNAs are a group of endogenous non-coding single stranded RNAs, which play an important role in cell proliferation, differentiation, autophagy, apoptosis and inflammation. In recent years, relevant studies have found that the expression of microRNA is changed after Helicobacter pylori infection, and then regulate the biological process of host cells. This paper reviews the regulation role of microRNAs on cell biological behavior through different signal pathways after Helicobacter pylori infection.

Helicobacter pylori regulated microRNA map of human gastric cells

BACKGROUND

Helicobacter pylori is an infection of concern for its chronic colonization leading to peptic ulcers and gastric cancer. In recent times, microRNAs have been extensively studied to understand their role in the pathogenesis of this bacteria in diverse contexts of gastric diseases. The current analysis reports the microRNA-mRNA interactions that are associated with effective survival and virulence of this pathogen.

MATERIALS AND METHODS

We convened differentially regulated human microRNAs responsive to H. pylori infection (HP-hDEmiRs) at different multiplicity of infection and time points in human gastric cell lines through retrospective data mining of experimental studies. In view of the molecular disparity of clinical samples and animal models, data from tissue, serum/plasma, urine, and ascites were excluded. Further, we utilized diverse bioinformatics approaches to retrieve experimentally validated, high-confidence targets of the HP-hDEmiRs to analyze the microRNA-mRNA interactions that are relevant to H. pylori pathogenesis.

RESULTS

A total of 39 HP-hDEmiRs that showed unidirectional expression of either overexpression or downregulation were identified to modulate 23 targets explicitly studied under this infection. We also identified 476 experimentally validated targets regulated by at least 4 of the HP-hDEmiRs. In addition to the pathways prior-associated with H. pylori infection, the microRNA-mRNA interactome analysis identified several cellular processes and pathways highly associated with cell cycle, cell division, migration, and carcinogenesis.

CONCLUSION

This study generated a platform to study the mechanisms utilized by this pathogen using microRNAs as surrogate.

Alterations in the expression levels of long intergenic non-coding RNA APOC1P1-3 in cervical cancer tissue samples

lncRNAs play a crucial role in the carcinogenesis process. Thus, they have been recognized as the potential therapeutic and diagnostic biomarkers of cancers. This study assessed the alteration in the expression of APOC1P1-3 lncRNA in cancerous tissues compared to their adjacent non-tumorous tissues sampled from cervical cancer patients. one hundred fifteen pairs of cancerous and adjacent non-cancerous biopsy of cervical cancer specimens were collected. RNA isolation and cDNA synthesis were carried out. The qRT-PCR was used to assess the changes in the expression of APOC1P1-3 lncRNA. Moreover, the biomarker function of the lncRNA and the correlations between APOC1P1-3 and clinicopathological parameters were measured. The APOC1P1-3 expression was significantly increased in cervical cancer specimens as compared to adjacent non-tumorous specimens (p < 0.0001). A significant association was also observed between APOC1P1-3 expression and lymph node involvement (p = 0.031). Additionally, APOC1P1-3 expression demonstrated a significant association with the depth of tumor invasion (p = 0.035), and squamous type of cervical cancer (p = 0.019). The overexpression of APOC1P1-3 was significantly observed in patients younger than 50 years old as compared to another age group (p = 0.033). The results of ROC curve exhibited that APOC1P1-3 with area under the curve (AUC), specificity, and sensitivity of 0.96, 93.91%, and 78.26%, respectively can be considered as a potential biomarker. Regarding overexpression of APOC1P1-3 in human cervical cancer samples, this lncRNA may be considered as an oncogenic factor in cervical cancer patients. Besides, APOC1P1-3 may be a possible biomarker for the diagnosis and treatment of cervical cancer patients.

Antisense long non-coding RNAs in gastric cancer

Gastric cancer is a global health problem with high mortality. The incidence of gastric cancer has significant regional differences. Helicobacter pylori (H. pylori) infection and its interaction with epigenetics are closely related to the occurrence of gastric cancer. It is of great significance to explore the early diagnosis and effective therapeutic targets of gastric cancer. Emerging evidence indicates that antisense long non-coding RNAs (lncRNAs) are closely associated with various biological and functional aspects of gastric cancer. However, diverse antisense lncRNAs in gastric cancer have not been compiled and discussed. In this review, we summarize the predisposing factors and compile the interaction between H. pylori and epigenetics in gastric cancer. Moreover, we focus on the underlying molecular mechanism and regulatory role of each antisense lncRNA in gastric cancer. In addition, we provide a new insight into the potential diagnosis and treatment of antisense lncRNAs in gastric cancer.

Biomarker Characterization and Prediction of Virulence and Antibiotic Resistance from Helicobacter pylori Next Generation Sequencing Data

The Gram-negative bacterium Helicobacter pylori colonizes c.a. 50% of human stomachs worldwide and is the major risk factor for gastric adenocarcinoma. Its high genetic variability makes it difficult to identify biomarkers of early stages of infection that can reliably predict its outcome. Moreover, the increasing antibiotic resistance found in H. pylori defies therapy, constituting a major human health problem. Here, we review H. pylori virulence factors and genes involved in antibiotic resistance, as well as the technologies currently used for their detection. Furthermore, we show that next generation sequencing may lead to faster characterization of virulence factors and prediction of the antibiotic resistance profile, thus contributing to personalized treatment and management of H. pylori-associated infections. With this new approach, more and permanent data will be generated at a lower cost, opening the future to new applications for H. pylori biomarker identification and antibiotic resistance prediction.

Host miRNAs-microbiota interactions in gastric cancer

It is widely acknowledged that gastric cancer seriously affects the quality of life and survival of patients. The correlation between the microbiota and gastric cancer has attracted extensive attention in recent years, nonetheless the specific mechanism of its impact on gastric cancer remain largely unclear. Recent studies have shown that in addition to its role in the host’s inflammatory and immune response, the microbiota can also affect the occurrence and development of gastric cancer by affecting the expression of miRNAs. This paper brings together all currently available data on miRNAs, microbiota and gastric cancer, and preliminarily describes the relationship among them.

An updated review of the contribution of noncoding RNAs to the progression of gastric cancer stem cells: Molecular mechanisms of viability, invasion, and chemoresistance of gastric cancer stem cells

Gastric cancer (GC) is a leading cause of death and cancer mortality in the world, with poor survival for cases with higher stages of GC. During the past decade, GC stem cells (GCSCs) - a group of cancer cells- have been the focus of numerous cancer researches. GCSCs have the capability of self-renewal and are identified to be participated in GC development, invasion, chemoresistance, and tumor relapse. Research projects have indicated the main activities of noncoding RNAs in cellular pathways. Micro (mi)RNAs and lncRNAs play important functions in the modulation of different cellular pathways in the post-transcriptional form, through their dysregulated expression in several cancers, including GC. In this paper, we highlight the impact of dysregulated expression of micro-and lncRNAs and their downstream transcripts on GCSCs. Data collection about the progression of GCSCs may be beneficial for the introduction of new insights to the GC treatment.

PVT1 and ZFAS1 lncRNAs expressions and their biomarker value in gastric cancer tissue sampling among Iranian population

BACKGROUND

lncRNAs are modulatory factors with critical function in the tumorigenesis pathways, introducing them as promising therapeutic and diagnostic biomarkers for different cancers. This study is thus aimed to evaluate the differences in PVT1 and ZFAS1 gene expression in tumorous tissues as compared with adjacent healthy non-tumorous biopsies of gastric cancer cases.

METHODS

One hundred two pairs of tumorous and adjacent non-tumorous biopsies of GC cases were sampled. RNA isolation and cDNA production were carried out. The qRT-PCR was performed to evaluate the expression of PVT1 and ZFAS1 genes. Moreover, the associations between PVT1 or ZFAS1 and clinicopathological characteristics as well as the biomarker roles of the lncRNAs were assessed.

RESULTS

The PVT1 and ZFAS1 expressions showed a significant increase and decrease in GC samples as compared with non-cancerous tissues, respectively. PVT1 expression was significantly associated with and lymph-node involvement (p = 0.0007). Moreover, ZFAS1 expression demonstrated a significant association with lymph-node involvement (p = 0.0005), and tumor size >5 cm (p = 0.003). The findings of the ROC curve revealed that PVT1 and ZFAS1 may act as a possible biomarker with AUC of 0.71 and 0.79, specificity of 78.43% and 79.41%, and sensitivity of 55.88% and 64.71%.

CONCLUSIONS

Regarding upregulation of PVT1 and downregulation of ZFAS1 in human GC samples, these genes may respectively act as oncogenic and tumor-suppressive factors in GC cases. Furthermore, PVT1 and ZFAS1 can be considered as possible biomarkers for the detection and treatment of GC cases.

MicroRNA-424-5p enhances chemosensitivity of breast cancer cells to Taxol and regulates cell cycle, apoptosis, and proliferation

Combination therapy has been considered as a potential method to overcome the BC chemoresistance. MicroRNAs (miRs) have been suggested as a therapeutic factor in the combination therapy of BC. This project aimed at examining the possible activity and molecular function of miR-424-5p and Taxol combination in the human BC cell line. MDA-MB-231 cells were treated with miR-424-5p mimics and Taxol, in a combined manner or separately. We used the MTT test for assessing the cell proliferation. In addition, flow-cytometry was used for evaluating apoptosis and cell-cycle. Expression levels of underlying molecular factors of miR-424-5p were assessed using western-blotting and qRT-PCR. The obtained results demonstrated that miR-424-5p repressed BC cell proliferation and sensitized these cells to Taxol treatment through the induction of apoptosis. Further investigations showed that miR-424-5p might increase BC chemosensitivity through the regulation of apoptosis-related factors including P53, Caspase-3, Bcl-2, and Bax as well as the proliferation-related gene c-Myc. Moreover, miR-424-5p restoration in combination with Taxol treatment decreased the colony formation by regulating Oct-4 and led to G2 arrest via modulating Cdk-2 expression. Western-blotting demonstrated that miR-424-5p may perform its anti-chemoresistance role by regulating the PD-L1 expression and controlling PTEN/PI3K/AKT/mTOR. Overall, the upregulation of miR-424-5p was indicated to upregulate the sensitivity of BC cells to treatment with Taxol. MiR-424-5p might regulate the chemosensitivity of the BC cell line by modulating PD-L1 and controlling the PTEN/mTOR axis. Therefore, the combination of miR-424-5p with Taxol would represent a novel procedure to treat against BC.

The Unique Microbiome and Immunity in Pancreatic Cancer

ABSTRACT

Microorganisms can help maintain homeostasis in humans by providing nutrition, maintaining hormone balance, and regulating inflammatory responses. In the case of imbalances, these microbes can cause various diseases, even malignancy. Pancreatic cancer (PC) is characterized by high tumor invasiveness, distant metastasis, and insensitivity to traditional chemotherapeutic drugs, and it is confirmed that PC is closely related to microorganisms. Recently, most studies based on clinical samples or case reports discussed the positive or negative relationships between microorganisms and PC. However, the specific mechanisms are blurry, especially the involved immunological pathways, and the roles of beneficial flora have usually been ignored. We reviewed studies published through September 2020 as identified using PubMed, MEDLINE, and Web of Science. We mainly introduced the traits of oral, gastrointestinal, and intratumoral microbes in PC and summarized the roles of these microbes in tumorigenesis and tumoral development through immunological pathways, in addition to illustrating the relationships between metabolic diseases with PC by microorganism. In addition, we identified microorganisms as biomarkers for early diagnosis and immunotherapy. This review will be significant for greater understanding the effect of microorganisms in PC and provide more meaningful guidance for future clinical applications.

miR-424: A novel potential therapeutic target and prognostic factor in malignancies

microRNAs are endogenous, noncoding RNAs. Showing both tumor-suppressive and oncogenic characteristics, miRNAs can regulate important processes in malignancies. This review aimed at highlighting the recent studies on the contribution of miR-424 to the modulation of carcinogenesis and exploring its probable clinical effectiveness in the diagnosis and therapy of malignancies. The data were extracted from all papers published from 2013 until 2020. Mature miR-424 leads to the degradation of its target transcripts or the suppression of translation via binding to the molecular targets. miR-424 is involved in modulating p53, PI3K/Akt, Wnt, and other molecular pathways, thereby regulating cellular growth, apoptosis, differentiation, chemoresistance, and cancer immunity. miR-424 was introduced as a tumor-suppressive miR in numerous types of cancers while as an oncogene in several cancers. Regarding the cancer dependent role of miR-424, it may be a prognostic and diagnostic biomarker and a potential candidate for the treatment of cancers.

Dual Role of Bacteria in Carcinoma: Stimulation and Inhibition

Although what unifies the carcinogenic microorganisms has not been determined by multiple studies, the role of bacteria in the development of neoplasms has not been properly elucidated. In this review, we discuss links between the bacterial species and cancer, with focus on immune responses for the stimulation of tumor cells such as induction of inflammation. Finally, we will describe the potential therapeutic strategies of bacteria on target tumors to improve treatment while mitigating adverse reactions. Cancer is a series of genetic changes that transform normal cells into tumor cells. These changes come from several reasons, including smoking, drinking alcohol, sunlight, exposure to chemical or physical factors, and finally chronic infection with microorganisms, including bacteria. In fact, bacterial infections are not carcinogenic, but recently it was discovered that the association between bacteria and cancer is through two mechanisms, the first stimulating chronic inflammation and the second producing carcinogenic metabolites. While bacteria are carcinogenic agents also, they have a dual role eliminating and removing tumor cells. However, the traditional cancer treatments that include chemotherapy, radiotherapy, surgery, and immunotherapy increase the chances of survival, and there are many side effects of these therapies, including the high toxicity of tissues and normal cells, could not penetrate the tumor cells, and resistance of these therapies by tumor cells. Therefore, the world has turned to an alternative solution, which is the use of genetically engineered microorganisms; thus, the use of living bacteria targeting cancerous cells is the unique option to overcome these challenges. Bacterial therapies, whether used alone or combination with chemotherapy, give a positive effect to treat multiple conditions of cancer. Also, bacteria can be used as vectors for drug, gene, or therapy, and this is a great step to treat cancer. Thus, we review the mechanisms underlying the interaction of the microbiota residents with cancer. Cancer-associated bacteria differ from those in healthy human and are linked with gene-expression profile. We also discuss how live bacteria interact with tumor microenvironments to induce tumor regression through colonization and spread. Finally, we provide past and ongoing clinical trials that include bacteria targeting tumors.

Tumor suppressive activity of miR-424-5p in breast cancer cells through targeting PD-L1 and modulating PTEN/PI3K/AKT/mTOR signaling pathway

AIMS

MicroRNAs (miRs) are key modulators of cellular processes such as proliferation, apoptosis, as well as anti-cancer immune responses. Here, we evaluated the role of miR-424-5p in breast cancer (BC) and investigated its effects on T cell-related immune response.

MAIN METHODS

BC tissues and cell lines were prepared and the expression of miR-424-5p and PD-L1, as well as the underlying molecular pathways, were assessed via qRT-PCR and western blotting. The MTT assay and flow cytometry were used to assess the effect of miR-424-5p on proliferation, apoptosis, autophagy, and cell cycle progression. The co-culture of T cells with MDA-MB-231 was performed for evaluating the role of miR-424-5p in rescuing T cell exhaustion.

KEY FINDINGS

The results indicated the down-regulation of miR-424-5p and up-regulation of PD-L1 expression in BC tissue specimens. MiR-424-5p transfection into PD-L1 overexpressing MDA-MB-231 cells decreased the expression of PD-L1. Also, miR-424-5p could reduce MDA-MB-231 cell viability through modulating apoptosis and autophagy pathways. Furthermore, miR-424-5p transfection leads to decreased colony formation and increased cell number at the G2/M phase. Western blot analysis illustrated that miR-424-5p could exert its anti-proliferative effect via modulating PTEN/PI3K/AKT/mTOR pathway. Moreover, it was demonstrated that suppression of PD-L1 by miR-424-5p could participate in regulating the expression of effector cytokines in T cells.

SIGNIFICANCE

MiR-424-5p could be considered as a potential tumor-suppressor miR in regulating BC cellular growth, apoptosis, and T cell-related immune response through targeting PD-L1, and its downstream mediators. Therefore, we recognized miR-424-5p as a promising candidate for miR restoration therapy in BC patients.