miR-224-5p inhibits proliferation,migration, and invasion by targeting PIK3R3/AKT3 in uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Accumulating investigations have identified the aberrant expression of miRNAs (microRNAs) in UM, such as miR-181, miR-20a, miR-144, miR-146a. The purpose of this study is to investigate the biological function of miR-224-5p in UM. The expression of miR-224-5p, PIK3R3, and AKT3 in 30 tumor tissues and paired adjacent noncancerous tissues were analyzed using Western blot analysis and quantitative real-time polymerase chain reaction (qRT-PCR) assays. Cell proliferation assay, transwell assay, and wound healing assay were used to measure the effects of miR-224-5p on the motility of UM in vitro. Western blot analysis and luciferase assays were used to detect the expression of PIK3R3 and AKT3 as miR-224-5p downstream targets. The results of Western blot analysis and qRT-PCR assays indicated that the expression of miR-224-5p was lower in UM tissues compared to normal tissue, while the expression of PIK3R3 and AKT3 were simultaneously increased. Upregulation of miR-224-5p significantly inhibited capacities of proliferation, invasion, and migration of OCM-1A cells and decreased expression of PIK3R3 and AKT3. Luciferase assay demonstrated PIK3R3 and AKT3 as downstream targets of miR-224-5p. Moreover, upregulating PIK3R3 and AKT3 restrained miR-224-5p-induced inhibition of the motility of OCM-1A cells. Thus, our study proved that miR-224-5p was involved in proliferation, invasion, and migration of UM cells via regulation the expression of PIK3R3 and AKT3. And the results also established a miR-224-5p/PIK3R3/PI3K/AKT axis in the regulation of UM progression, providing an experimental basis for further exploring the miR-224-5p as a therapeutic and diagnosis target for patients with UM.     

KDM5B promotes self-renewal of hepatocellular carcinoma cells through the microRNA-448–mediated YTHDF3/ITGA6 axis

Histone methylation plays important roles in mediating the onset and progression of various cancers, and lysine-specific demethylase 5B (KDM5B), as a histone demethylase, is reported to be an oncogene in hepatocellular carcinoma (HCC). However, the mechanism underlying its tumorigenesis remains undefined. Hence, we explored the regulatory role of KDM5B in HCC cells, aiming to identify novel therapeutic targets for HCC. Gene Expression Omnibus database and StarBase were used to predict important regulatory pathways related to HCC. Then, the expression of KDM5B and microRNA-448 (miR-448) in HCC tissues was detected by RT-qPCR and Western blot analysis. The correlation between KDM5B and miR-448 expression was analysed by Pearson's correlation coefficient and ChIP experiments, and the targeting of YTH N6-methyladenosine RNA binding protein 3 (YTHDF3) by miR-448 was examined by luciferase assay. Additionally, the effect of KDM5B on the proliferation, migration, invasion and apoptosis as well as tumorigenicity of transfected cells was assessed using ectopic expression and depletion experiments. KDM5B was highly expressed in HCC cells and was inversely related to miR-448 expression. KDM5B demethylated H3K4me3 on the miR-448 promoter and thereby inhibited the expression of miR-448, which in turn targeted YTHDF3 and integrin subunit alpha 6 (ITGA6) to promote the malignant phenotype of HCC. Moreover, KDM5B accelerated HCC progression in nude mice via the miR-448/YTHDF3/ITGA6 axis. Our study uncovered that KDM5B regulates the YTHDF3/ITGA6 axis by inhibiting the expression of miR-448 to promote the occurrence of HCC.     

Simvastatin treatment promotes proliferation of human dental pulp stem cells via modulating PI3K/AKT/miR-9/KLF5 signalling pathway

Simvastatin serves as an effective therapeutic potential in the treatment of dental disease via alternating proliferation of dental pulp stem cells. First, western-blot and real-time quantitative PCR were used to detect the effect of simvastatin or LY294002 on the expression levels of AKT, miR-9 and KLF5, or determine the effect of miR-9. Simvastatin, KLF5 and AKT significantly enhanced the proliferation of pulp stem cells, whilst this effect induced by simvastatin was suppressed by LY294002, AKT siRNA, KLF5 siRNA and miR-9, and simvastatin dose-dependently upregulated the expression of PI3K. Furthermore, simvastatin upregulated PI3K and p-AKT expression in a concentration-dependent manner. LY294002 abrogated the upregulation of p-AKT expression levels induced by simvastatin, and LY294002 induced the miR-9 expression and simvastatin dose-dependently inhibited the expression of miR-9, by contrast, LY294002 reduced the KLF5 expression and simvastatin dose-dependently promoted the expression of KLF5. And using computational analysis, KLF5 was found to be a candidate target gene of miR-9, and which was further verified using luciferase assay. Finally, the level of KLF5 in cells was much lower following the transfection with miR-9 and KLF5 siRNA, and the level of AKT mRNA in cells was significantly inhibited after transfection with AKT siRNA than control. These findings suggested simvastatin could promote the proliferation of pulp stem cells, possibly by suppressing the expression of miR-9 via activating the PI3K/AKT signalling pathway, and the downregulation of miR-9 upregulated the expression of its target gene, KLF5, which is directly responsible for the enhanced proliferation of pulp stem cells.     

Retracted: MicroRNA-99b suppresses human cervical cancer cell activity by inhibiting the PI3K/AKT/mTOR signaling pathway

Cervical cancer is common cancer among women with high morbidity. MicroRNAs (miRs) are involved in the progression and development of cervical cancer. This study aimed to explore the effect of miR-99b-5p (miR-99b) on invasion and migration in cervical cancer through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway. The microarray-based analysis was used to screen out differentially expressed miRNAs. Expression of miR-99b, PI3K, AKT, mTOR, and ribosomal protein S6 kinase (p70S6K) was determined in both cervical cancer tissues and paracancerous tissues. Next, alteration of miR-99b expression in cervical cancer was conducted to evaluate levels of PI3K, AKT, mTOR, p70S6K matrix metallopeptidase 2, epithelial cell adhesion molecule, and intercellular adhesion molecule 1, as well as the effect of miR-99b on cell proliferation, invasion, migration, cell cycle distribution, and apoptosis. The results demonstrated that miR-99b expression was decreased and levels of PI3K, AKT, mTOR, and p70S6K were elevated in cervical cancer tissues. More important, overexpressed miR-99b repressed the PI3K/AKT/mTOR signaling pathway, inhibited cell proliferation, invasion, and migration, blocked cell cycle entry, and promoted apoptosis in cervical cancer. These results indicate that miR-99b attenuates the migration and invasion of human cervical cancer cells through downregulation of the PI3K/AKT/mTOR signaling pathway, which provides a therapeutic approach for cervical cancer treatment.     

KDM5A silencing transcriptionally suppresses the FXYD3-PI3K/AKT axis to inhibit angiogenesis in hepatocellular cancer via miR-433 up-regulation

Hepatocellular cancer (HCC) has been reported to belong to one of the highly vascularized solid tumours accompanied with angiogenesis of human umbilical vein endothelial cells (HUVECs). KDM5A, an attractive drug target, plays a critical role in diverse physiological processes. Thus, this study aims to investigate its role in angiogenesis and underlying mechanisms in HCC. ChIP-qPCR was utilized to validate enrichment of H3K4me3 and KDM5A on the promotor region of miR-433, while dual luciferase assay was carried out to confirm the targeting relationship between miR-433 and FXYD3. Scratch assay, transwell assay, Edu assay, pseudo-tube formation assay and mice with xenografted tumours were conducted to investigate the physiological function of KDM5A-miR-433-FXYD3-PI3K-AKT axis in the progression of HCC after loss- and gain-function assays. KDM5A p-p85 and p-AKT were highly expressed but miR-433 was down-regulated in HCC tissues and cell lines. Depletion of KDM5A led to reduced migrative, invasive and proliferative capacities in HCC cells, including growth and a lowered HUVEC angiogenic capacity in vitro. Furthermore, KDM5A suppressed the expression of miR-433 by demethylating H3K4me3 on its promoterregion. miR-433 negatively targeted FXYD3. Depleting miR-433 or re-expressing FXYD3 restores the reduced migrative, invasive and proliferative capacities, and lowers the HUVEC angiogenic capacity caused by silencing KDM5A. Therefore, KDM5A silencing significantly suppresses HCC tumorigenesis in vivo, accompanied with down-regulated miR-433 and up-regulated FXYD3-PI3K-AKT axis in tumour tissues. Lastly, KDM5A activates the FXYD3-PI3K-AKT axis to enhance angiogenesis in HCC by suppressing miR-433.     

Inhibitory role of bone marrow mesenchymal stem cells-derived exosome in non-small-cell lung cancer: microRNA-30b-5p,EZH2 and PI3K/AKT pathway

Exosomal microRNA (miRNA) exerts potential roles in non-small-cell lung cancer (NSCLC). The current study elucidated the role of miR-30b-5p shuttled by bone marrow mesenchymal stem cells (BMSCs)-derived exosomes in treating NSCLC. Bioinformatics analysis was performed with NSCLC-related miRNA microarray GSE169587 and mRNA data GSE74706 obtained for collection of the differentially expressed miRNAs and mRNAs. The relationship between miR-30b-5p and EZH2 was predicted and confirmed. Exosomes were isolated from BMSCs and identified. BMSCs-derived exosomes overexpressing miR-30b-5p were used to establish subcutaneous tumorigenesis models to study the effects of miR-30b-5p, EZH2 and PI3K/AKT signalling pathway on tumour growth. A total of 86 BMSC-exo-miRNAs were differentially expressed in NSCLC. Bioinfomatics analysis found that BMSC-exo-miR-30b-5p could regulate NSCLC progression by targeting EZH2, which was verified by in vitro cell experiments. Besides, the target genes of miR-30b-5p were enriched in PI3K/AKT signalling pathway. Animal experiments validated that BMSC-exo-miR-30b-5p promoted NSCLC cell apoptosis and prevented tumorigenesis in nude mice via EZH2/PI3K/AKT axis. Collectively, the inhibitory role of BMSC-derived exosomes-loaded miR-30b-5p in NSCLC was achieved through blocking the EZH2/PI3K/AKT axis.     

Downregulation of MUC15 by miR-183-5p.1 promotes liver tumor-initiating cells properties and tumorigenesis via regulating c-MET/PI3K/AKT/SOX2 axis

Mucin 15 (MUC15) is reportedly aberrant in human malignancies, including hepatocellular carcinoma (HCC). However, the role of MUC15 in the regulation of liver tumor-initiating cells (T-ICs) remains unknown. Here, we report that expression of MUC15 is downregulated in liver T-ICs, chemoresistance and recurrent HCC samples. Functional studies reveal that MUC15 inhibits hepatoma cells self-renewal, malignant proliferation, tumorigenicity, and chemoresistance. Mechanistically, MUC15 interacts with c-MET and subsequently inactivates the PI3K/AKT/SOX2 signaling pathway. Moreover, we find that miR-183-5p.1 directly targets MUC15 3′-UTR in liver T-ICs. Coincidentally, SOX2 feedback inhibits MUC15 expression by directly transactivating miR-183-5p.1, thus completing a feedforward regulatory circuit in liver T-ICs. Importantly, MUC15/c-MET/PI3K/AKT/SOX2 axis determines the responses of hepatoma cells to lenvatinib treatment, and MUC15 overexpression abrogated lenvatinib resistance. Analysis of patient cohort, patient-derived tumor organoids and patient-derived xenografts further suggests that the MUC15 may predict lenvatinib benefits in HCC patients. Collectively, our findings suggest the crucial role of the miR-183-5p.1/MUC15/c-MET/PI3K/AKT/SOX2 regulatory circuit in regulating liver T-ICs properties, suggesting potential therapeutic targets for HCC.Subject terms: Cancer stem cells, Tumour biomarkers, Liver cancer     

Tumor suppressor miR-139-5p targets Tspan3 and regulates the progression of acute myeloid leukemia through the PI3K/Akt pathway

Dysregulation of microRNAs is closely implicated in the initiation and progression of human cancers including acute myeloid leukemia (AML). Though miR-139-5p was reported to be a potent tumor suppressor in adult AML, its underlying molecular mechanism in AML remains to be further defined. Herein, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis were conducted to determine the expressions of miR-139-5p and tetraspanin3 (Tspan3) in AML patients and cells. Luciferase reporter assay, qRT-PCR, and Western blot analysis were carried out to detect the interaction between miR-139-5p and Tspan3. Cell proliferation, cell cycle distribution, invasion, and migration were evaluated by cell counting kit-8, flow cytometry, transwell invasion, and migration assays, respectively. Western blot analysis was conducted to determine phosphorylated-protein kinase B (Akt) and Akt levels. We found that a significant reduction in miR-139-5p expression and a prominent increase in Tspan3 expression were observed in AML patients and cells. Tspan3 was confirmed as a direct target of miR-139-5p and was negatively modulated by miR-139-5p. Rescue experiments showed that overexpression of miR-139-5p constrained cell proliferation, invasion and migration capabilities, and induced cell cycle arrest at the S phase in AML cells, which were partially reversed by Tspan3 overexpression. In addition, we found that miR-139-5p suppressed the phosphoinositide 3-kinase (PI3K)/Akt pathway in AML cells by targeting Tspan3. In conclusion, our study concluded that miR-139-5p suppressed the leukemogenesis in AML cells by targeting Tspan3 through inactivation of the PI3K/Akt pathway, providing a better understanding of AML progression.     

MiR-330-Mediated Regulation of SH3GL2 Expression Enhances Malignant Behaviors of Glioblastoma Stem Cells by Activating ERK and PI3K/AKT Signaling Pathways

MicroRNAs are currently considered as an active and rapidly evolving area for the treatment of tumors. In this study, we elucidated the biological significance of miR-330 in glioblastoma stem cells (GSCs) as well as the possible molecular mechanisms. SH3GL2 is mainly distributed in the central nervous system and considered to be a tumor suppressor in many tumors. In the present study, we identified miR-330 as a potential regulator of SH3GL2 and we found that it was to be inversely correlated with SH3GL2 expression in GSCs which were isolated from U87 cell lines. The expression of miR-330 enhanced cellular proliferation, promoted cell migration and invasion, and dampened cell apoptosis. When the GSCs were co-transfected with the plasmid containing short hairpin RNA directed against human SH3GL2 gene and miR-330 mimic, we found that miR-330 promoted the malignant behavior of GSCs by down-regulating the expression of SH3GL2. Meanwhile, the ERK and PI3K/AKT signaling pathways were significantly activated, leading to the decreased expression of apoptotic protein and increased expression of anti-apoptotic protein. Furthermore, in orthotopic mouse xenografts, the mice given stable over-expressed SH3GL2 cells co-transfected with miR-330 knockdown plasmid had the smallest tumor sizes and longest survival. In conclusion, these results suggested that miR-330 negatively regulated the expression of SH3GL2 in GSCs, which promoted the oncogenic progression of GSCs through activating ERK and PI3K/AKT signaling pathways. The elucidation of these mechanisms will provide potential therapeutic approaches for human glioblastoma.     

Tumor-derived extracellular vesicles shuttle c-Myc to promote gastric cancer growth and metastasis via the KCNQ1OT1/miR-556-3p/CLIC1 axis

Gastric cancer (GC) is a heterogeneous disease with poor prognosis. Tumor-derived extracellular vesicles (EVs) assume a role in intercellular communication by carrying various molecules, including proteins, RNA, and DNAs, which has been identified to exhibit oncogenic effect in GC. Therefore, this research aimed to figure out whether tumor-derived EVs transmit c-Myc to orchestrate the growth and metastasis of GC. KCNQ1OT1, microRNA (miR)-556-3p and CLIC1 expression of GC tissues was detected through RT-qPCR. EVs were isolated from GC cells, followed by RT-qPCR and Western blot analysis of c-Myc expression in EVs and GC cells. Next, GC cells were incubated with EVs or transfected with a series of mimic, inhibitor, or siRNAs to assess their effects on cell viability, migrative, invasive, and apoptotic potential. Relationship among c-Myc, KCNQ1OT1, miR-556-3p, and CLIC1 was evaluated by dual-luciferase reporter assay. PI3K/AKT pathway-related proteins were assessed through Western blot analysis. KCNQ1OT1 and CLIC1 were highly expressed but miR-556-3p in GC tissues. c-Myc was high-expressed in tumor-derived EVs and GC cells. Mechanistically, c-Myc could induce KCNQ1OT1 expression, and KCNQ1OT1 bound to miR-556-3p that negatively targeted CLIC1 to inactivate PI3K/AKT pathway. Tumor-derived EVs, EVs-c-Myc, KCNQ1OT1 or CLIC1 overexpression, or miR-556-3p inhibition promoted GC cell proliferative, invasive, and migrative capacities but repressed their apoptosis through activating PI3K/AKT pathway. Collectively, tumor-derived EVs carrying c-Myc activated KCNQ1OT1 to downregulate miR-556-3p, thus elevating CLIC1 expression to activate the PI3K/AKT pathway, which facilitated the growth and metastasis of GC.Subject terms: Cancer, Biotechnology     

Circ_0005615 promotes cervical cancer cell growth and metastasis by modulating the miR-138-5p/KDM2A axis

Cervical cancer (CC) is a highly fatal gynecological malignancy due to its high metastasis and recurrence rate. Circular RNA (circRNA) has been regarded as a regulator of CC. However, the underlying molecular mechanism of circ_0005615 in CC remains unclear. The levels of circ_0005615, miR-138-5p, and lysine demethylase 2A (KDM2A) were measured using qRT-PCR or western blot. Cell proliferation was assessed by Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine, and colony formation experiments. Cell invasion and migration were tested by transwell assay and wound healing assay. Flow cytometry and Caspase-Glo 3/7 Assay kit were used to analyze cell apoptosis. The expression of proliferation-related and apoptosis-related markers was detected by western blot. The binding relationships among circ_0005615, miR-138-5p, and KDM2A were verified by dual-luciferase reporter assay or RNA immunoprecipitation assay. Xenograft assay was applied to detect the effect of circ_0005615 in vivo. Circ_0005615 and KDM2A were upregulated, while miR-138-5p was downregulated in CC tissues and cells. Circ_0005615 knockdown retarded cell proliferation, migration, and invasion, while promoting apoptosis. Besides, circ_0005615 sponged miR-138-5p, and miR-138-5p could target KDM2A. miR-138-5p inhibitor reversed the regulation of circ_0005615 knockdown on CC cell growth and metastasis, and KDM2A overexpression also abolished the inhibitory effect of miR-138-5p on CC cell growth and metastasis. In addition, we also discovered that circ_0005615 silencing inhibited CC tumor growth in vivo. Circ_0005615 acted as a tumor promoter in CC by regulating the miR-138-5p/KDM2A pathway.     

Hsa_circ_0003596 enhances the development of cell renal clear cell carcinoma through the miR-502-5p/IGF1/PI3K/AKT axis

Accumulating research findings have shown that circular RNAs (circRNAs) play an indispensable role in tumorigenesis and tumor progression. The current study aimed to explore the role and modulatory mechanism of hsa_circ_0003596 in clear cell renal cell carcinoma (ccRCC). Quantitative real-time polymerase chain reaction was adopted to detect the expression of hsa_circ_0003596 in ccRCC tissue and cell lines. 5-Ethynyl-2′-deoxyuridine, cell counting kit 8 and the colony formation assay were utilized to assess the proliferation potential of the ccRCC cells. Transwell along with wound healing assays were adopted to quantify infiltration coupled with the migration potential of the cells. The current research study found that the circRNA hsa_circ_0003596 was overexpressed in ccRCC tissue and cell lines. Further, result showed that hsa_circ_0003596 was associated with distant metastasis of renal cancer. Notably, the knockdown of hsa_circ_0003596 can lower the proliferation, infiltration and migration potential of ccRCC cells. The results of in vivo experiments found that the reduction of hsa_circ_0003596 significantly hampered the growth of tumors in mice. In addition, it was evident that hsa_circ_0003596 acts as a “molecular sponge” for miR-502-5p to upregulate the expression of the microRNA-502-5p (miR-502-5p) target insulin-like growth factor 1 (IGF1R). Furthermore, it was found that the phosphatidylinositol 3-kinase (PI3K)/AKT signaling was the downstream cascade of hsa_circ_0003596/miR-502-5p/IGF1R cascade, which is partly responsible for the cancer-promoting effect. Overall, the results of the present study showed that hsa_circ_0003596 facilitated the proliferation, infiltration and migration of ccRCC through the miR-502-5p/IGF1R/PI3K/AKT axis. Therefore, it was evident that hsa_circ_0003596 can serve as a possible biomarker and therapeutic target against ccRCC.     

FoxP3-miR-150-5p/3p suppresses ovarian tumorigenesis via an IGF1R/IRS1 pathway feedback loop

Ovarian cancer (OC) causes more deaths than any other gynecological cancer. Many cellular pathways have been elucidated to be associated with OC development and progression. Specifically, the insulin-like growth factor 1 receptor/insulin receptor substrate 1 (IGF1R/IRS1) pathway participates in OC development. Moreover, accumulating evidence has shown that microRNA deregulation contributes to tumor initiation and progression. Here, our study aimed to investigate the molecular functions and regulatory mechanisms of miR-150, specifically, in OC. We found that the expression of miR-150-5p/3p and their precursor, mir-150, was downregulated in OC tissues; lower mir-150 levels were associated with poor OC patient outcomes. Ectopic mir-150 expression inhibited OC cell growth and metastasis in vitro and in vivo. Furthermore, both IRS1 and IGF1R were confirmed as direct targets of miR-150-5p/3p, and the miR-150-IGF1R/IRS1 axis exerted antitumor effects via the PI3K/AKT/mTOR pathway. Forkhead box protein 3 (FoxP3) positively regulated the expression of miR-150-5p/3p by binding to the mir-150 promoter. In turn, the PI3K/AKT/mTOR pathway downregulated FoxP3 and miR-150-5p/3p. Taken together, these findings indicate that a complex FoxP3-miR-150-IGF1R/IRS1-PI3K/AKT/mTOR feedback loop regulates OC pathogenesis, providing a novel mechanism for miR-150 as a tumor suppressor miRNA in OC.Subject terms: Cancer, Translational research     

Timosaponin AIII inhibits metastasis of renal carcinoma cells through suppressing cathepsin C expression by AKT/miR-129-5p axis

Timosaponin AIII (TSAIII) is a steroidal saponin that exerts anticancer activity on various cancer cells. In this study, we explore the effects of TSAIII on renal cell carcinoma (RCC) cells. Our findings show that TSAIII treatment (<8 μM) insignificantly influenced cell viability and cell cycle distribution of human RCC cell lines 786-O, A-498, and ACHN. Further observations revealed that TSAIII inhibited migration and invasion of 786-O and A-498 cells, as well as significantly decreased the production and expression of cathepsin C (CTSC) in both the cell types. Kinase cascade analysis exhibited that PI3K/AKT activation was inhibited, but PTEN expression was increased, in response to TSAIII treatments. Combining TSAIII and PI3K inhibitors, LY294002 synergically reduced the migration and invasion of 786-O and A-498 cells, as well as decreased the CTSC expression in both the cell types. We also observed that miR-129-5p bound to CTSC gene and suppressed the expression of CTSC and demonstrated that the miR-129-5p expression was synergically enhanced by TSAIII and LY294002. In addition, pretreatment with antago-miR-129-5p significantly restored the CTSC expression and the migration and invasion of TSAIII-treated 786-O cells. In conclusion, our findings reveal that TSAIII inhibits the metastatic properties of RCC cells, contributing to the inhibition of PI3K/AKT and the increase of miR-129-5p and the subsequent downregulation of CTSC. This suggests that TSAIII has significant antimetastatic activity against RCC cells and may be beneficial to RCC treatments.     

Extracellular vesicles-encapsulated let-7i shed from bone mesenchymal stem cells suppress lung cancer via KDM3A/DCLK1/FXYD3 axis

Accumulating evidence has suggested that extracellular vesicles (EVs) play a crucial role in lung cancer treatment. Thus, we aimed to investigate the modulatory role of bone marrow mesenchymal stem cell (BMSC)-EV-derived let-7i and their molecular mechanism in lung cancer progression. Microarray-based analysis was applied to predict lung cancer-related miRNAs and their downstream genes. RT-qPCR and Western blot analyses were conducted to determine Let-7i, lysine demethylase 3A (KDM3A), doublecortin-like kinase 1 (DCLK1) and FXYD domain-containing ion transport regulator 3 (FXYD3) expressions, after which dual-luciferase reporter gene assay and ChIP assay were used to identify the relationship among them. After loss- and gain-of-function assays, the effects of let-7i, KDM3A, DCLK1 and FXYD3 on the biological characteristics of lung cancer cells were assessed. Finally, tumour growth in nude mice was assessed by xenograft tumours in nude mice. Bioinformatics analysis screened out the let-7i and its downstream gene, that is KDM3A. The findings showed the presence of a high expression of KDM3A and DCLK1 and reduced expression of let-7i and FXYD3 in lung cancer. KDM3A elevated DCLK1 by removing the methylation of H3K9me2. Moreover, DCLK1 suppressed the FXYD3 expression. BMSC-EV-derived let-7i resulted in the down-regulation of KDM3A expression and reversed its promoting role in lung cancer development. Consistently, in vivo experiments in nude mice also confirmed that tumour growth was suppressed by the BMSC-EV-derived let-7i. In conclusion, our findings demonstrated that the BMSC-EV-derived let-7i possesses an inhibitory role in lung cancer progression through the KDM3A/DCLK1/FXYD3 axis, suggesting a new molecular target for lung cancer treatment.