Identification of microRNA-615-3p as a novel tumor suppressor in non-small cell lung cancer

circ-TFRC downregulation suppresses ovarian cancer progression via miR-615-3p/IGF2 axis regulation

BACKGROUND

Ovarian cancer (OC) is a malignancy among female globally. Circular RNAs (circRNAs) are a family of circular endogenous RNAs generated from selective splicing, which take part in many traits. Former investigation suggested that circ-TFRC was abnormally expressed in breast cancer (BC). Further, the role of circ-TFRC to the progress of OC remains unclear. So, the aim of this study was to reveal the regulatory mechanism of circ-TFRC.

METHODS

Our team made the luciferase reporter assay to validate circ-TFRC downstream target. Transwell migration assay, 5-ethynyl-20-deoxyuridine, and cell counting kit-8 were applied to investigate both proliferation and migration. In vivo tumorigenesis and metastasis assays were performed to investigate the circ-TFRC role in OC.

RESULTS

The outputs elucidated that circ-TFRC expression incremented in OC cells and tissues. circ-TFRC downregulation inhibited OC cell proliferation as well as migration in in vivo and in vitro experiments. The luciferase results validated that miR-615-3p and IGF2 were circ-TFRC downstream targets. IGF2 overexpression or miR-615-3p inhibition reversed OC cell migration after circ-TFRC silencing. Also, IGF2 overexpression reversed OC cell migration and proliferation post miR-615-3p upregulation.

CONCLUSION

Results demonstrate that circ-TFRC downregulation inhibits OC progression and metastasis via IGF2 expression regulation and miR-615-3psponging.

Expression of urinary exosomal miRNA-615-3p and miRNA-3147 in diabetic kidney disease and their association with inflammation and fibrosis

BACKGROUND

Diabetic kidney disease (DKD) is one of the most common chronic complications of type 2 diabetes mellitus (T2DM), and it is particularly important to identify a high-quality method for evaluating disease progression. Urinary exosomes contain microRNA that might promise early diagnostic and monitoring markers of DKD. The present study aimed to identify novel exosome-related markers associated with inflammation and fibrosis to assess the progression of DKD.

METHOD

Exosomes were extracted from the urine of 83 participants to determine the expression levels of miRNA-615-3p and miRNA-3147 in 20 healthy people, 21 patients with T2DM and 42 patients with DKD, as determined by RT-qPCR. The circulating expression level of TGF-β1 was detected by ELISA. Serum Cystatin C was measured by a latex-enhanced immunoturbidimetric method. The correlation analyses were performed for all clinical and laboratory parameters.

RESULT

The expression level of urinary exosomal miRNA-615-3p in DKD patients was significantly higher than that in the control group and the T2DM group by RT-qPCR. The expression of miRNA-3147 showed an upward trend in the three groups of subjects, but it was not statistically significant. The urinary exosomal miRNA-615-3p was positively correlated with serum Cystatin C, plasma TGF-β1, creatinine, BUN, PCR and 24-h urine protein, and negatively correlated with eGFR and albumin. The diagnostic efficacy of urinary exosomal miRNA-615-3p combined with the ACR was higher than that of ACR alone.

CONCLUSIONS

Urinary exosomal miRNA-615-3p may be used as a novel biomarker for evaluating the progression of DKD, and may be involved in the process of inflammation and fibrosis in DKD. The combined diagnosis of urinary exosomal miRNA-615-3p and ACR may be used as more stable and sensitive diagnostic criteria for DKD.

MiRNAs in Lung Cancer: Diagnostic, Prognostic, and Therapeutic Potential

Lung cancer is the dominant emerging factor in cancer-related mortality around the globe. Therapeutic interventions for lung cancer are not up to par, mainly due to reoccurrence/relapse, chemoresistance, and late diagnosis. People are currently interested in miRNAs, which are small double-stranded (20–24 ribonucleotides) structures that regulate molecular targets (tumor suppressors, oncogenes) involved in tumorigeneses such as cell proliferation, apoptosis, metastasis, and angiogenesis via post-transcriptional regulation of mRNA. Many studies suggest the emerging role of miRNAs in lung cancer diagnostics, prognostics, and therapeutics. Therefore, it is necessary to intensely explore the miRNOME expression of lung tumors and the development of anti-cancer strategies. The current review focuses on the therapeutic, diagnostic, and prognostic potential of numerous miRNAs in lung cancer.

MicroRNA miR-3646 promotes malignancy of lung adenocarcinoma cells by suppressing sorbin and SH3 domain-containing protein 1 via the c-Jun NH2-terminal kinase signaling pathway

Lung adenocarcinoma (LUAD) is a highly malignant tumor. In this study, we examined the role of miR-3646 and its underlying mechanism in the progression of LUAD. The expression of miR-3646 and sorbin and SH3 domain-containing protein 1 (SORBS1) in LUAD tissues and cells was evaluated by quantitative reverse transcription-polymerase chain reaction. LUAD cell adhesion, proliferation, apoptosis was determined. The targeting relationship between SORBS1 and miR-3646 was verified by dual luciferase and RNA pull-down assays. In vivo assays were performed to verify the in vitro results. The expression of miR-3646 was found to be upregulated in LUAD tissues and cells. MiR-3646 overexpression stimulated the proliferation and adhesion of LUAD cells but inhibite d apoptosis, whereas a miR-3646 inhibitor produced the opposite results. Furthermore, the inhibitory effect of miR-3646 inhibitor was verified in vivo. SORBS1, a target gene identified downstream of miR-3646, was downregulated in LUAD tissues and cells. Additionally, increased SORBS1 inhibited the malignant phenotypes of LUAD cells, which was restored by miR-3646 upregulation. Additionally, western blot analysis revealed that SORBS1 ectopic expression disrupted the JNK signaling pathway, and this effect was restored by miR-3646 overexpression. Thus, this study revealed that miR-3646 promotes LUAD cell proliferation and adhesion, and reduces apoptosis by directly downregulating SORBS1 via the JNK signaling pathway. Investigation of the molecular mechanism of LUAD carcinogenesis revealed that miR-3646 may serve as a biomarker for LUAD treatment.in vivo

HOTTIP downregulation reduces neuronal damage and microglial activation in Parkinson's disease cell and mouse models

HOXA transcript at the distal tip (HOTTIP), a newly identified long noncoding RNA, has been shown to exhibit anti-inflammatory effects and inhibit oxygen-glucose deprivation-induced neuronal apoptosis. However, its role in Parkinson’s disease (PD) remains unclear. 1-Methyl-4-phenylpyridium (MPP⁺) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were used to establish PD models in SH-SY5Y and BV2 cells and in C57BL/6 male mice, respectively. In vitro, after HOTTIP knockdown by sh-HOTTIP transfection, HOTTIP and FOXO1 overexpression promoted SH-SY5Y apoptosis, BV2 microglial activation, proinflammatory cytokine expression, and nuclear factor kappa-B and NACHT, LRR and PYD domains-containing protein 3 inflammasome activation. Overexpression of miR-615-3p inhibited MPP⁺-induced neuronal apoptosis and microglial inflammation and ameliorated HOTTIP- and FOXO1-mediated nerve injury and inflammation. In vivo, HOTTIP knockdown alleviated motor dysfunction in PD mice and reduced neuronal apoptosis and microglial activation in the substantia nigra. These findings suggest that inhibition of HOTTIP mitigates neuronal apoptosis and microglial activation in PD models by modulating miR-615-3p/FOXO1. This study was approved by the Ethics Review Committee of the Affiliated Hospital of Qingdao University, China (approval No. UDX-2018-042) in June 2018.

miRNAs in lung cancer. A systematic review identifies predictive and prognostic miRNA candidates for precision medicine in lung cancer

Lung cancer (LC) is the leading cause of cancer-related death worldwide and miRNAs play a key role in LC development. To better diagnose LC and to predict drug treatment responses we evaluated 228 articles encompassing 16,697 patients and 12,582 healthy controls. Based on the criteria of ≥3 independent studies and a sensitivity and specificity of >0.8 we found blood-borne miR-20a, miR-10b, miR-150, and miR-223 to be excellent diagnostic biomarkers for non-small cell LC whereas miR-205 is specific for squamous cell carcinoma. The systematic review also revealed 38 commonly regulated miRNAs in tumor tissue and the circulation, thus enabling the prediction of histological subtypes of LC. Moreover, theranostic biomarker candidates with proven responsiveness to checkpoint inhibitor treatments were identified, notably miR-34a, miR-93, miR-106b, miR-181a, miR-193a-3p, and miR-375. Conversely, miR-103a-3p, miR-152, miR-152-3p, miR-15b, miR-16, miR-194, miR-34b, and miR-506 influence programmed cell death-ligand 1 and programmed cell death-1 receptor expression, therefore providing a rationale for the development of molecularly targeted therapies. Furthermore, miR-21, miR-25, miR-27b, miR-19b, miR-125b, miR-146a, and miR-210 predicted response to platinum-based treatments. We also highlight controversial reports on specific miRNAs. In conclusion, we report diagnostic miRNA biomarkers for in-depth clinical evaluation. Furthermore, in an effort to avoid unnecessary toxicity we propose predictive biomarkers. The biomarker candidates support personalized treatment decisions of LC patients and await their confirmation in randomized clinical trials.

MiR-199a-5p-HIF-1α-STAT3 Positive Feedback Loop Contributes to the Progression of Non-Small Cell Lung Cancer

Background: Non-small cell lung cancer (NSCLC) is the most common malignancy worldwide. MiR-199a-5p has been reported to play important roles in multiple tumors, inclusive of NSCLC. However, little is definitively known pertaining to its explicit mechanism of action in NSCLC. Methods: The expressions of miR-199a-5p and hypoxia-inducible factor-1α (HIF-1α) mRNA were quantified employing qRT-PCR. H1299 and A549 cells were transiently transfected with miR-199a-5p mimics or inhibitors. Then, CCK-8 assays, flow cytometry analysis, and Transwell assay were performed for detecting cell proliferation, cell cycle, apoptosis, migration, and invasion of NSCLC cells, respectively. HIF-1α, signal transducer and activator of transcription 3 (STAT3), and p-STAT3 expressions were detected via Western blotting. Bioinformatic analysis and dual-luciferase assay were performed to investigate the interactions among miR-199a-5p, HIF-1α, and STAT3. Xenograft models were established with nude mice for further analyzing the bevacizumab resistance of NSCLC cells. Results: MiR-199a-5p expression was markedly attenuated in NSCLC tissues and cell lines. Overexpression of miR-199a-5p repressed the proliferation, migration, and invasion but induced the apoptosis of NSCLC cells. HIF-1α was identified as a direct target of miR-199a-5p. There was a positive feedback loop among miR-199a-5p, HIF-1α, and STAT3. Co-transfection of HIF-1α or STAT3 overexpression plasmids counteracted the effects of miR-199a-5p. In vivo experiments indicated that the feedback loop was in association with the bevacizumab resistance of NSCLC cells. Conclusion: MiR-199a-5p blocked the progression of NSCLC and sensitized NSCLC cells to bevacizumab by suppressing HIF-1α and STAT3, while the HIF-1α/STAT3 axis suppressed the expression of miR-199a-5p, which forms a positive feedback loop to promote the sustaining progression of NSCLC.

microRNAs Mediated Regulation of the Ribosomal Proteins and its Consequences on the Global Translation of Proteins

Ribosomal proteins (RPs) are mostly derived from the energy-consuming enzyme families such as ATP-dependent RNA helicases, AAA-ATPases, GTPases and kinases, and are important structural components of the ribosome, which is a supramolecular ribonucleoprotein complex, composed of Ribosomal RNA (rRNA) and RPs, coordinates the translation and synthesis of proteins with the help of transfer RNA (tRNA) and other factors. Not all RPs are indispensable; in other words, the ribosome could be functional and could continue the translation of proteins instead of lacking in some of the RPs. However, the lack of many RPs could result in severe defects in the biogenesis of ribosomes, which could directly influence the overall translation processes and global expression of the proteins leading to the emergence of different diseases including cancer. While microRNAs (miRNAs) are small non-coding RNAs and one of the potent regulators of the post-transcriptional gene expression, miRNAs regulate gene expression by targeting the 3' untranslated region and/or coding region of the messenger RNAs (mRNAs), and by interacting with the 5' untranslated region, and eventually finetune the expression of approximately one-third of all mammalian genes. Herein, we highlighted the significance of miRNAs mediated regulation of RPs coding mRNAs in the global protein translation.

MicroRNA-615-5p regulates the proliferation and apoptosis of breast cancer cells by targeting HSF1

Breast cancer, which commonly occurs in the epithelium of the mammary gland, is a malignant tumor. MicroRNAs are involved in various cancer-associated processes, and microRNA-615-5p has been identified to be decreased in the pathological tissues from patients with breast cancer. In the present study, the possible mechanism of microRNA-615-5p in the progression of breast cancer was investigated in order to identify potential novel targets for clinical treatment. Heat shock factor 1 (HSF1) was identified as a predictive target gene of microRNA-615-5p using TargetScan analysis. The expression levels of microRNA-615-5p and its target gene, HSF1, were measured in breast cancer tissues and normal adjacent tissues. Additionally, the effects of microRNA-615-5p on MCF-7 breast cancer cell growth and apoptosis were examined. Furthermore, the interaction between HSF1 and microRNA-615-5p was investigated by a dual luciferase gene reporter assay. The expression levels of HSF1 were measured following transfection with microRNA-615-5p or pcDNA3.1-HSF1. Finally, the expression levels of proliferation- and apoptosis-associated factors such as B-cell lymphoma 2 (Bcl-2), cyclin D1, proliferating cell nuclear antigen (PCNA) and bcl-2-like protein 4 (Bax) were determined. The results demonstrated that lower microRNA-615-5p expression and higher HSF1 mRNA expression were present in tumor tissues compared with adjacent tissues (P<0.01). HSF1 was verified as a direct target of microRNA-615-5p using the dual luciferase gene reporter assay. In comparison with untransfected control and mimic-transfected negative control (NC) cells, MCF-7 cells transfected with microRNA-615-5p mimics exhibited reduced cell proliferation and increased apoptosis (P<0.01). However, the overexpression of HSF1 using a vector reversed the suppression of HSF1 induced by microRNA-615-5p mimics (P<0.01). The mRNA and protein expression levels of Bax were significantly increased, whereas those of Bcl-2, cyclin D1 and PCNA were decreased in the cells transfected with microRNA-615-5p mimics compared with the control and NC cells (P<0.01). Collectively, the present study indicated that microRNA-615-5p may mediate the progression of breast cancer by targeting HSF1.

Long noncoding RNA HOTTIP promotes the metastatic potential of ovarian cancer through the regulation of the miR-615-3p/SMARCE1 pathway

Upregulation of lncRNA HOXA transcript at the distal tip (HOTTIP) plays important roles in cancer progression. Nevertheless, its functions in the growth and metastasis of ovarian carcinoma are unknown. In this study, we demonstrated overexpression of HOTTIP in ovarian cancer cell lines and clinical tissues. Further, we showed that higher level of HOTTIP was associated with poor survival of ovarian cancer patients. Notably, HOTTIP silencing restrained proliferation, migration, and invasiveness of ovarian carcinoma cells. On the other hand, upregulation of HOTTIP remarkably exacerbated the aggressive traits of ovarian carcinoma cells. In addition, HOTTIP served as a sponge of miR-615-3p to upregulate SMARCE1 level. Further, upregulation of miR-615-3p or downregulation of SMARCE1 reversed the carcinogenic impacts of HOTTIP in ovarian cancer. HOTTIP and miR-615-3p expression levels in ovarian cancer cells were negatively correlated, whereas HOTTIP and SMARCE1 expression levels were positively correlated. In nude mice, downregulation of HOTTIP reduced cell growth in vivo. In summary, lncRNA HOTTIP promotes the growth and metastatic phenotypes of ovarian cancer via regulating miR-615-3p/SMARCE1 pathway.

miR-615 Fine-Tunes Growth and Development and Has a Role in Cancer and in Neural Repair

MicroRNAs (miRNAs) are small noncoding RNAs that function as epigenetic modulators regulating almost any gene expression. Similarly, other noncoding RNAs, as well as epigenetic modifications, can regulate miRNAs. This reciprocal interaction forms a miRNA-epigenetic feedback loop, the deregulation of which affects physiological processes and contributes to a great diversity of diseases. In the present review, we focus on miR-615, a miRNA highly conserved across eutherian mammals. It is involved not only during embryogenesis in the regulation of growth and development, for instance during osteogenesis and angiogenesis, but also in the regulation of cell growth and the proliferation and migration of cells, acting as a tumor suppressor or tumor promoter. It therefore serves as a biomarker for several types of cancer, and recently has also been found to be involved in reparative processes and neural repair. In addition, we present the pleiad of functions in which miR-615 is involved, as well as their multiple target genes and the multiple regulatory molecules involved in its own expression. We do this by introducing in a comprehensible way the reported knowledge of their actions and interactions and proposing an integral view of its regulatory mechanisms.

Downregulation of hsa-microRNA-204-5p and identification of its potential regulatory network in non-small cell lung cancer: RT-qPCR, bioinformatic- and meta-analyses

Background

Pulmonary malignant neoplasms have a high worldwide morbidity and mortality, so the study of these malignancies using microRNAs (miRNAs) has attracted great interest and enthusiasm. The aim of this study was to determine the clinical effect of hsa-microRNA-204-5p (miR-204-5p) and its underlying molecular mechanisms in non-small cell lung cancer (NSCLC).

Methods

Expression of miR-204-5p was investigated by real-time quantitative PCR (RT-qPCR). After data mining from public online repositories, several integrative assessment methods, including receiver operating characteristic (ROC) curves, hazard ratios (HR) with 95% confidence intervals (95% CI), and comprehensive meta-analyses, were conducted to explore the expression and clinical utility of miR-204-5p. The potential objects regulated and controlled by miR-204-5p in the course of NSCLC were identified by estimated target prediction and analysis. The regulatory network of miR-204-5p, with its target genes and transcription factors (TFs), was structured from database evidence and literature references.

Results

The expression of miR-204-5p was downregulated in NSCLC, and the downtrend was related to gender, histological type, vascular invasion, tumor size, clinicopathologic grade and lymph node metastasis (P<0.05). MiR-204-5p was useful in prognosis, but was deemed unsuitable at present as an auxiliary diagnostic or prognostic risk factor for NSCLC due to the lack of statistical significance in meta-analyses and absence of large-scale investigations. Gene enrichment and annotation analyses identified miR-204-5p candidate targets that took part in various genetic activities and biological functions. The predicted TFs, like MAX, MYC, and RUNX1, interfered in regulatory networks involving miR-204-5p and its predicted hub genes, though a modulatory loop or axis of the miRNA-TF-gene that was out of range with shortage in database prediction, experimental proof and literature confirmation.

Conclusions

The frequently observed decrease in miR-204-5p was helpful for NSCLC diagnosis. The estimated target genes and TFs contributed to the anti-oncogene effects of miR-204-5p.

Long non-coding RNA HOTTIP promotes hypoxia-induced glycolysis through targeting miR-615-3p/HMGB3 axis in non-small cell lung cancer cells

Increased glycolysis under hypoxic stress is a fundamentally important feature of non-small cell lung cancer (NSCLC) cells, but molecular mechanisms of hypoxia on glycolysis remain elusive. Herein, we aimed to explore whether lncRNAs and miRNAs are involved in the glycolytic reprogramming under hypoxic conditions. The levels of HOXA transcript at the distal tip (HOTTIP), miR-615-3p and high mobility group box 3 (HMGB3) mRNA were assessed by qRT-PCR. Western blot was performed to determine the protein expression of hexokinase 2 (HK-2) and HMGB3. Glucose consumption and lactate production were analyzed using a respective assay kit. The targeted correlation between miR-615-3p and HOTTIP or HMGB3 was verified using dual-luciferase reporter and RNA immunoprecipition assays. Our data revealed that HOTTIP was upregulated and miR-615-3p was downregulated in NSCLC tissues and cells. Hypoxia induced glycolysis, increased HOTTIP and HMGB3 mRNA levels and repressed miR-615-3p expression in NSCLC cells. HOTTIP deficiency or miR-615-3p expression restoration repressed hypoxia-induced glycolysis. Moreover, HOTTIP acted as a molecular sponge for miR-615-3p and HMGB3 was a direct target of miR-615-3p. The inhibitory effect of HOTTIP deficiency on glycolysis under hypoxic exposure was reversed by miR-615-3p restoration. Additionally, HOTTIP regulated HMGB3 expression by acting as a molecular sponge of miR-615-3p in NSCLC cells. In conclusion, our study suggested that HOTTIP might promote glycolysis under hypoxic conditions at least partly through regulating miR-615-3p/HMGB3 axis in NSCLC cells. Targeting HOTTIP might be a promising therapeutic strategy for NSCLC treatment.

MiR-889 promotes cell growth in human non-small cell lung cancer by regulating KLF9

Currently, non-small cell lung cancer (NSCLC) is still the most common malignancy worldwide. Although miR-889 has been reported to play an important role in various malignancies, the physiological function of miR-889 in NSCLC remains unknown. This paper places emphasis on the influence of miR-889 on the development and progression of non-small cell lung cancer. To detect the expression level of miR-889 in NSCLC tissues and cell lines, quantitative real-time polymerase chain reaction (qRT-PCR) assay and In Situ Hybridization (ISH) were adopted in this study. Cell proliferation and colony forming ability were examined by Cell Counting Kit-8 (CCK-8) and colony formation assays. Furthermore, transwell experiments were conducted to determine the influence of miR-889 on migration. KLF9 expression was evaluated by qRT-PCR and Western blotting. First, miR-889 expression was increased in the cancer tissues of non-small cell lung cancer patients (n = 40) compared with adjacent tissues. Subsequently, knockdown of miR-889 significantly inhibited cell proliferation and migration, while overexpression of miR-889 had the opposite effect. KLF9 may be a potential target of miR-889. In addition, upregulation of miR-889 promotes tumorigenesis in vitro, and KLF9 protein levels are also reduced. The current study suggests that miR-889 may play a potential therapeutic role for NSCLC by targeting KLF9 to control NSCLC proliferation and migration.

MiR-615 inhibits cell proliferation, migration and invasion by targeting EGFR in human glioblastoma

MiR-615 and epidermal growth factor receptor (EGFR) are associated with a number of disease processes and pathogenesis. However, little is known about the mechanisms of miR-615 and EGFR in human glioblastoma multiforme (GBM). Here, we found that down-regulation of miR-615 expression occurred in GBM tissues and cells, and was inversely correlated with overall survival, relapse-free survival, WHO grade as well as EGFR expression. We further determined that miR-615 functions as a tumor suppressor by inhibiting GBM cell proliferation, cell cycle, migration and invasion, and promoting cell apoptosis. In-vivo assay validated the inhibition effect of miR-615 on tumor growth and EGFR expression. Luciferase reporter assays demonstrated that miR-615 targeted the 3'-untranslated region (3'-UTR) of EGFR. Besides, over-expression of EGFR reversed the inhibition effects of miR-615, while silencing of EGFR aggravated these inhibition effects. In conclusions, we identified that miR-615 plays a tumor suppressor role in GBM cell proliferation, migration and invasion by targeting EGFR expression, and miR-615 may act as a novel biomarker for early diagnosis or therapeutic targets of GBM.

miR-615-3p promotes proliferation and migration and inhibits apoptosis through its potential target CELF2 in gastric cancer

Gastric cancer incidence is relatively higher in China than that in developed countries; however, molecular mechanisms considering the initiation and progression of gastric cancer are still unclear. For decades, numerous microRNAs have been found to regulate a wide range of biological functions in gastric cancer. However, the oncogenic function of miR-615-3p in gastric cancer has not been reported to date. With the help of gene and microRNA chips in 10 patients, we were able to screen differential expressed genes and microRNAs compared with normal gastric tissues. After that, online bioinformatics analysis tools were used to predict microRNAs' potential targets. As a result, miR-615-3p and its potential target, CELF2, were selected for further experiments. QRT-PCR and western blot results indicated the aberrant high expression of miR-615-3p and low expression of CELF2 in gastric cancer both in vivo and in vitro. Moreover, miR-615-3p expression correlated to T and M stage. Up regulation of miR-615-3p inhibited the apoptosis, promoted proliferation and migration and led to the down-regulation of CELF2. Meanwhile, down-regulation of miR-615-3p resulted in anti-tumor effects. Immunochemistry staining of CELF2 showed its association with T, N and M stage. In addition, overexpression of CELF2 could reverse miR-615-3p's oncogenic functions stated before. These findings indicate that miR-615-3p promotes gastric cancer proliferation and migration by suppressing CELF2 expression for the first time, providing clues for future clinical practices.

MicroRNA 615-3p Inhibits the Tumor Growth and Metastasis of NSCLC via Inhibiting IGF2

MicroRNAs are essential regulators of cancer-associated genes at the posttranscriptional level, and their expression is altered in cancer tissues. Herein we sought to identify the regulation of miR-615-3p in NSCLC progression and its mechanism. miR-615-3p expression was significantly downregulated in NSCLC tissue compared to control normal tissue. Exogenous overexpression of miR-615-3p inhibited the growth and metastasis of NSCLC cells. In addition, the in vivo mouse xenograft model showed that overexpression of miR-615-3p inhibited NSCLC growth and lung metastasis, whereas decreased expression of miR-615-3p caused an opposite outcome. Furthermore, we revealed that insulin-like growth factor 2 (IGF2) expression was negatively correlated with the miR-615-3p level in NSCLC specimens, and IGF2 knockdown mimicked the effect of miR-615-3p inhibition on NSCLC cell proliferation, migration, and invasion. In addition, overexpression of IGF2 rescued the inhibition of miR-615-3p in NSCLC cells. Together, our results indicated that miR-615-3p played important roles in the regulation of NSCLC growth and metastasis by targeting IGF2.

miR-615 Inhibits Prostate Cancer Cell Proliferation and Invasion by Directly Targeting Cyclin D2

Previous studies have reported that miR-615 exerts a tumor suppressor role in some tumors, such as esophageal squamous cell carcinoma and non-small cell lung cancer. However, the role of miR-615 in prostate cancer has not been defined. Here we found that miR-615 was downregulated in prostate cancer tissues and cell lines. Overexpression of miR-615 in PC-3 cells significantly inhibited cellular proliferation, migration, and invasion. Moreover, overexpression of miR-615 delayed tumor growth in vivo. In terms of mechanism, we found that cyclin D2 (CCND2) is a target gene of miR-615 in prostate cancer. We showed that miR-615 could bind to the 3′-UTR region of CCND2 mRNA and inhibit its expression. There was a negative correlation between the expression of miR-615 and CCND2 in prostate cancer tissues. Moreover, restoration of cyclin D2 abolished the inhibitory effects of miR-615 on the proliferation, migration, and invasion of prostate cancer cells. Taken together, our study identified miR-615 as a tumor suppressor by targeting cyclin D2 in prostate cancer.