MicroRNA-219 is downregulated in non-small cell lung cancer and inhibits cell growth and metastasis by targeting HMGA2

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

HMGA2 regulation by miRNAs in cancer: affecting cancer hallmarks and therapy response

High mobility group A 2 (HMGA2) is a protein that modulates the structure of chromatin in the nucleus. Importantly, aberrant expression of HMGA2 occurs during carcinogenesis, and this protein is an upstream mediator of cancer hallmarks including evasion of apoptosis, proliferation, invasion, metastasis, and therapy resistance. HMGA2 targets critical signaling pathways such as Wnt/β-catenin and mTOR in cancer cells. Therefore, suppression of HMGA2 function notably decreases cancer progression and improves outcome in patients. As HMGA2 is mainly oncogenic, targeting expression by non-coding RNAs (ncRNAs) is crucial to take into consideration since it affects HMGA2 function. MicroRNAs (miRNAs) belong to ncRNAs and are master regulators of vital cell processes, which affect all aspects of cancer hallmarks. Long ncRNAs (lncRNAs) and circular RNAs (circRNAs), other members of ncRNAs, are upstream mediators of miRNAs. The current review intends to discuss the importance of the miRNA/HMGA2 axis in modulation of various types of cancer, and mentions lncRNAs and circRNAs, which regulate this axis as upstream mediators. Finally, we discuss the effect of miRNAs and HMGA2 interactions on the response of cancer cells to therapy. Regarding the critical role of HMGA2 in regulation of critical signaling pathways in cancer cells, and considering the confirmed interaction between HMGA2 and one of the master regulators of cancer, miRNAs, targeting miRNA/HMGA2 axis in cancer therapy is promising and this could be the subject of future clinical trial experiments.

Matched Analyses of Brain Metastases versus Primary Non-Small Cell Lung Cancer Reveal a Unique microRNA Signature

Distant spreading of tumor cells to the central nervous system in non-small cell lung cancer (NSCLC) occurs frequently and poses major clinical issues due to limited treatment options. RNAs displaying differential expression in brain metastasis versus primary NSCLC may explain distant tumor growth and may potentially be used as therapeutic targets. In this study, we conducted systematic microRNA expression profiling from tissue biopsies of primary NSCLC and brain metastases from 25 patients. RNA analysis was performed using the nCounter Human v3 miRNA Expression Assay, NanoString technologies, followed by differential expression analysis and in silico target gene pathway analysis. We uncovered a panel of 11 microRNAs with differential expression and excellent diagnostic performance in brain metastasis versus primary NSCLC. Five microRNAs were upregulated in brain metastasis (miR-129-2-3p, miR-124-3p, miR-219a-2-3p, miR-219a-5p, and miR-9-5p) and six microRNAs were downregulated in brain metastasis (miR-142-3p, miR-150-5p, miR-199b-5p, miR-199a-3p, miR-199b-5p, and miR-199a-5p). The differentially expressed microRNAs were predicted to converge on distinct target gene networks originating from five to twelve core target genes. In conclusion, we uncovered a unique microRNA profile linked to two target gene networks. Our results highlight the potential of specific microRNAs as biomarkers for brain metastasis in NSCLC and indicate plausible mechanistic connections.

Effects of HMGA2 gene silencing on cell cycle and apoptosis in the metastatic renal carcinoma cell line ACHN

Objective

To explore the role of high mobility group AT-hook 2 (HMGA2) in the regulation of the cell cycle and apoptosis.

Methods

The renal carcinoma cell line ACHN was transiently transfected with small interfering RNA to knock down the expression of the HMGA2 gene. Cell cycle analysis was undertaken using flow cytometry. The mRNA and protein levels of HMGA2, E2F transcription factor 1 (E2F1), cyclin D1, cyclin dependent kinase 6 (CDK6), B-cell lymphoma-2 (Bcl-2), caspase-3 and caspase-9 were analysed using reverse transcription quantitative real-time polymerase chain reaction and Western blot analysis.

Results

The mRNA and protein levels of HMGA2 were significantly higher in renal carcinoma cell lines compared with the human renal proximal tubular epithelial cell line HKC. After HMGA2 gene-specific silencing, more cells entered the G₀/G₁ phase, while fewer cells entered the G₂/M phase; and the cells exhibited early and late apoptosis. HMGA2 gene-specific silencing significantly reduced the mRNA and protein levels of E2F1, cyclin D1, CDK6 and Bcl-2; and increased the mRNA and protein levels of caspase-3 and caspase-9.

Conclusion

The HMGA2 gene may be involved in the tumorigenesis and development of renal cancer, thus inhibiting HMGA2 gene expression might provide a potential therapeutic target in the future.

MicroRNA-Mediated Regulation of the Virus Cycle and Pathogenesis in the SARS-CoV-2 Disease

In the last few years, microRNA-mediated regulation has been shown to be important in viral infections. In fact, viral microRNAs can alter cell physiology and act on the immune system; moreover, cellular microRNAs can regulate the virus cycle, influencing positively or negatively viral replication. Accordingly, microRNAs can represent diagnostic and prognostic biomarkers of infectious processes and a promising approach for designing targeted therapies. In the past 18 months, the COVID-19 infection from SARS-CoV-2 has engaged many researchers in the search for diagnostic and prognostic markers and the development of therapies. Although some research suggests that the SARS-CoV-2 genome can produce microRNAs and that host microRNAs may be involved in the cellular response to the virus, to date, not enough evidence has been provided. In this paper, using a focused bioinformatic approach exploring the SARS-CoV-2 genome, we propose that SARS-CoV-2 is able to produce microRNAs sharing a strong sequence homology with the human ones and also that human microRNAs may target viral RNA regulating the virus life cycle inside human cells. Interestingly, all viral miRNA sequences and some human miRNA target sites are conserved in more recent SARS-CoV-2 variants of concern (VOCs). Even if experimental evidence will be needed, in silico analysis represents a valuable source of information useful to understand the sophisticated molecular mechanisms of disease and to sustain biomedical applications.

miR-219a-5p enhances the radiosensitivity of non-small cell lung cancer cells through targeting CD164

Lung cancer is one of the leading causes of cancer-associated mortality. Non-small cell lung carcinoma (NSCLC) accounts for 70–85% of the total cases of lung cancer. Radioresistance frequently develops in NSCLC in the middle and later stages of radiotherapy. We investigated the role of miR-219a-5p in radioresistance of NSCLC. miR-219a-5p expression in serum and lung tissue of lung cancer patients was lower than that in control. Compared with radiosensitive (RS) NSCLC patients, miR-219a-5p expression was decreased in serum and lung tissue in radioresistant patients. miR-219a-5p expression level was negatively associated with radioresistance in NSCLC cell lines. Up-regulation of miR-219a-5p increased radiosensitivity in radioresistant NSCLC cells in vitro and in vivo. Down-regulation of miR-219a-5p decreased radiosensitivity in radiosensitive A549 and H358 cells. miR-219a-5p could directly bind in the 3′UTR of CD164 and negatively regulated CD164 expression. CD164 expression was higher in radioresistant NSCLC tissues than RS tissues. Up-regulation of CD164 significantly inhibited miR-219a-5p-induced regulation of RS in radioresistant A549 and H358 cells. Down-regulation of CD164 significantly inhibited the effect of anti-miR-219a-5p on radiosensitive A549 and H358 cells. miR-219a-5p or down-regulation of CD164 could increase apoptosis and γ-H2A histone family member X (γ-H2AX) expression in radioresistant cells in vitro and in vivo. Up-regulation of CD164 could inhibit the effect of miR-219a-5p on apoptosis and γ-H2AX expression. Our results indicated that miR-219a-5p could inhibit CD164, promote DNA damage and apoptosis and enhance irradiation-induced cytotoxicity. The data highlight miR-219a-5p/CD164 pathway in the regulation of radiosensitivity in NSCLC and provide novel targets for potential intervention.

Silencing lung cancer genes using miRNAs identified by 7mer-seed matching

Lung cancer (LC) is the main cause of cancer-associated deaths in both men and women globally with a very high mortality rate. The microRNAs (miRNAs) are a class of noncoding RNAs consisting of 18-25 nucleotides. They inhibit translation of protein through binding to complementary target mRNAs. The non-coding miRNAs are recognized as potent biomarkers for detection, development and treatment of malignancy. In this study, we screened a set of 12 genes over expressed in small cell lung cancer, non small cell lung cancer and the genes involved in both categories and their binding sites for human miRNAs as no work was reported yet. Screening of human miRNAs revealed that a few genes showed numerous miRNA binding sites. Free energy values of mRNA sequences revealed that they might acquire compact folded structure causing complexity for miRNAs to interact. GC content in the target site was relatively higher than that of their flanks. It was observed through analysis of cosine similarity metric and compAI parameters that the genes related to lung cancer were encoded with non optimal codons and thus might be translationally less efficient for producing polypeptides. Gene ontology analysis was carried out to understand the diverse functions of these 12 genes.

miR‑454‑3p inhibits non‑small cell lung cancer cell proliferation and metastasis by targeting TGFB2

Accumulating studies have suggested that microRNAs (miRs) play a significant role in lung cancer development and progression, especially in non-small cell lung cancer (NSCLC). The present study aimed to investigate the associations between miR-454-3p and NSCLC progression. qPCR assay was applied to examine the expression of miR-454-3p and transforming growth factor-β2 (TGFB2) in tissues and cell lines. CCK-8 and EdU assays were used to detect cell proliferation. Wound-healing and Transwell assays were conducted to assess cell migration and invasion. Western blotting assay was performed to explore the protein levels of epithelial-mesenchymal transition (EMT) markers. The interaction between miR-454-3p and TGFB2 was investigated with a luciferase reporter assay. miR-454-3p was downregulated in NSCLC tissues and NSCLC cell lines. miR-454-3p overexpression led to the suppression of proliferation, migration, and invasion in A549 and NCI-H1650 cells. In addition, the overexpression of miR-454-3p in A549 and NCI-H1650 cells significantly inhibited EMT. TGFB2 was revealed to be a direct target of miR-454-3p by using TargetScan database and luciferase reporter assay. TGFB2 was observed to be upregulated in NSCLC tissues and cell lines. Further mechanistic studies revealed that the inhibitory effects of miR-454-3p on NSCLC were reversed upon overexpression of TGFB2. These findings provided strong evidence that miR-454-3p suppressed NSCLC cell proliferation and metastasis by targeting TGFB2. The study suggests that targeting miR-454-3p could be a promising strategy for treating NSCLC.

The Impact of Air Pollution Exposure on the MicroRNA Machinery and Lung Cancer Development

Small non-coding RNA molecules (miRNAs) play an important role in the epigenetic regulation of gene expression. As these molecules have been repeatedly implicated in human cancers, they have been suggested as biomarkers of the disease. Additionally, miRNA levels have been shown to be affected by environmental pollutants, including airborne contaminants. In this review, we searched the current literature for miRNAs involved in lung cancer, as well as miRNAs deregulated as a result of exposure to air pollutants. We then performed a synthesis of the data and identified those molecules commonly deregulated under both conditions. We detected a total of 25 miRNAs meeting the criteria, among them, miR-222, miR-21, miR-126-3p, miR-155 and miR-425 being the most prominent. We propose these miRNAs as biomarkers of choice for the identification of human populations exposed to air pollution with a significant risk of developing lung cancer.

miR-219a suppresses human trophoblast cell invasion and proliferation by targeting vascular endothelial growth factor receptor 2 (VEGFR2)

OBJECTIVE

Vascular endothelial growth factor (VEGF) plays a critical role in regulating trophoblast cell invasion and proliferation, involved in a variety of pregnancy complications, such as spontaneous abortion and pre-eclampsia. Numerous studies have revealed that microRNAs (miRNAs) are participated in a series of molecular processes that regulate cell function, such as cell invasion, proliferation, and apoptosis. Vascular endothelial growth factor receptor 2 (VEGFR2), a receptor of VEGF, has been shown to be involved in trophoblast function. However, the relation between miRNA and VEGFR2 and their role in trophoblast function remain to be elucidated.

METHODS

The effect of miR-219a on the trophoblast function has been explored using luciferase reporter, transwell, qRT-PCR, western blot, bromodeoxyuridine (BrdU), ELISA, immunofluorescent staining, and tube formation assays.

RESULTS

In the current study, we observed that through targeted inhibition of VEGFR2 expression by miR-219a, the function of VEGFR2 as well as the downstream PI3K/AKT/NF-κB signaling pathway were suppressed, leading to suppression of trophoblastic proliferation and invasion. Moreover, upregulation of VEGFR2 restored the miR-219a-inhibited cell proliferation, invasion, and tube formation.

CONCLUSIONS

These results revealed that miR-219a played crucial roles in negatively regulating trophoblastic proliferation and invasion by suppression of the PI3K/AKT/NF-κB signaling pathway by targeting VEGFR2, therefore serving as a potential treatment method for the complications of pregnancy caused by trophoblastic dysregulation.

Knockdown of lncRNA ZFAS1-suppressed non-small cell lung cancer progression via targeting the miR-150-5p/HMGA2 signaling

Non-small cell lung cancer (NSCLC) is the main type of lung malignancy. Early diagnosis and treatments for NSCLC are far from satisfactory due to the limited knowledge of the molecular mechanisms regarding NSCLC progression. Long noncoding RNA (lncRNA) ZNFX1 antisense RNA1 (ZFAS1) has been implicated for its functional role in the progression of malignant tumors. This study aimed to determine the ZFAS1 expression from lung cancer clinical samples and to explore the molecular mechanisms underlying ZFAS1-modulated NSCLC progression. Experimental assays revealed that clinical samples and cell lines of lung malignant tumors showed an upregulation of ZFSA1. ZFAS1 expression was markedly upregulated in the lung tissues from patients with advanced stage of this malignancy. The loss-of-function assays showed that knockdown of ZFAS1-suppressed NSCLC cell proliferative, as well as invasive potentials, increased NSCLC cell apoptotic rates in vitro and also attenuated tumor growth of NSCLC cells in the nude mice. Further experimental evidence showed that ZFAS1 inversely affected miR-150-5p expression and positively affected high-mobility group AT-hook 2 (HMGA2) expression in NSCLC cell lines. MiR-150-5p inhibition or HMGA2 overexpression counteracted the effects of ZFAS1 knockdown on NSCLC cell proliferative, invasive potentials and apoptotic rates. In light of examining the clinical lung cancer samples, miR-150-5p expression was downregulated and the HMGA2 expression was highly expressed in the lung cancer tissues compared with normal ones; the ZFAS1 expression showed a negative correlation with miR-150-5p expression but a positive correlation with HMGA2 expression in lung cancer tissues. To summarize, we, for the first time, demonstrated the inhibitory effects of ZFAS1 knockdown on NSCLC cell progression, and the results from mechanistic studies indicated that ZFAS1-mediated NSCLC progression cells via targeting miR-150-5p/HMGA2 signaling.

Regulatory noncoding RNAs and the major histocompatibility complex

The Major Histocompatibility Complex (MHC) is a 4 Mbp genomic region located on the short arm of chromosome 6. The MHC region contains many key immune-related genes such as Human Leukocyte Antigens (HLAs). There has been a growing realization that, apart from MHC encoded proteins, RNAs derived from noncoding regions of the MHC-specifically microRNAs (miRNAs) and long noncoding RNAs (lncRNAs)-play a significant role in cellular regulation. Furthermore, regulatory noncoding RNAs (ncRNAs) derived from other parts of the genome fine-tune the expression of many immune-related MHC proteins. Although the field of ncRNAs of the MHC is a research area that is still in its infancy, ncRNA regulation of MHC genes has already been shown to be vital for immune function, healthy pregnancy and cellular homeostasis. Dysregulation of this intricate network of ncRNAs can lead to serious perturbations in homeostasis and subsequent disease.

XB130, regulated by miR-203, miR-219, and miR-4782-3p, mediates the proliferation and metastasis of non-small-cell lung cancer cells

XB130 is a novel adapter protein that behaves as a tumor promoter or suppressor mediating cell proliferation and metastasis in the development of different human tumors. Altered expression of XB130 has been verified in human non-small cell-lung cancer (NSCLC). However, the exact effect of XB130 on NSCLC is not well-understood. In this study, we investigated the biological function and posttranscriptional regulation of XB130 in NSCLC. First, the effects of XB130 silence on NSCLC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) were examined. Then the targeting relationship between XB130 and miR-203, miR-219, or miR-4782-3p was demonstrated by dual-luciferase reporter assay. Finally, the effects of miR-203, miR-219, and miR-4782-3p on NSCLC cell function were studied, respectively. We found that XB130 silence significantly inhibited cell growth, migration and invasion, and reversed EMT. Furthermore, XB130 was posttranscriptionally regulated by miR-203, miR-219, and miR-4782-3p. Overexpression of miR-203, miR-219, or miR-4782-3p inhibited cell growth, migration and invasion, and reversed EMT, just like the role of XB130 in NSCLC cells, whereas the suppressive effects of microRNA (miRNA) overexpression were weakened by miRNA inhibitors or ectopic expression of XB130 in NSCLC cells. These data demonstrate that XB130 is posttranscriptionally regulated by miR-203, miR-219, and miR-4782-3p and mediates the proliferation and metastasis of NSCLC cells.

High Mobility Group A (HMGA): Chromatin Nodes Controlled by a Knotty miRNA Network

High mobility group A (HMGA) proteins are oncofoetal chromatin architectural factors that are widely involved in regulating gene expression. These proteins are unique, because they are highly expressed in embryonic and cancer cells, where they play a relevant role in cell proliferation, stemness, and the acquisition of aggressive tumour traits, i.e., motility, invasiveness, and metastatic properties. The HMGA protein expression levels and activities are controlled by a connected set of events at the transcriptional, post-transcriptional, and post-translational levels. In fact, microRNA (miRNA)-mediated RNA stability is the most-studied mechanism of HMGA protein expression modulation. In this review, we contribute to a comprehensive overview of HMGA-targeting miRNAs; we provide detailed information regarding HMGA gene structural organization and a comprehensive evaluation and description of HMGA-targeting miRNAs, while focusing on those that are widely involved in HMGA regulation; and, we aim to offer insights into HMGA-miRNA mutual cross-talk from a functional and cancer-related perspective, highlighting possible clinical implications.

CircRNA CDR1as knockdown inhibits progression of non-small-cell lung cancer by regulating miR-219a-5p/SOX5 axis

BACKGROUND

Circular RNAs (circRNAs) participate in the development of human cancers by regulating multiple cell processes. CircRNA antisense to the cerebellar degeneration-related protein 1 transcript (circCDR1as) expression is dysregulated in many cancers, including non-small-cell lung cancer (NSCLC). However, the mechanism by which circCDR1as mediates the development of NSCLC remains unknown.

METHODS

A total of 30 paired cancer and normal tissues were collected from patients with NSCLC. The expression levels of circCDR1as, microRNA (miR)-219a-5p and Sex determining region Y-box protein 5 (SOX5) were measured in tissues or cells by quantitative real-time polymerase chain reaction or western blot. Cell viability, apoptosis, migration and invasion were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, colony formation, flow cytometry and transwell assays, respectively. The target relationship between miR-219a-5p and circCDR1as or SOX5 was validated by dual-luciferase reporter assay.

RESULTS

CircCDR1as expression was elevated in NSCLC tissues and cells in comparison to the matched controls. Interference of circCDR1as led to obvious inhibition of cell viability, migration and invasion and increase of apoptosis in NSCLC cells. MiR-219a-5p acted as a target of circCDR1as and miR-219a-5p downregulation attenuated the regulatory effect of circCDR1as silencing on NSCLC progression. Moreover, miR-219a-5p targeted SOX5 to repress the progression of NSCLC in vitro. Besides, circCDR1as knockdown reduced the expression of SOX5 by increasing miR-219a-5p level.

CONCLUSION

Knockdown of circCDR1as inhibited the progression of NSCLC by decreasing cell viability, migration and invasion and increasing apoptosis by upregulating miR-219a-5p and downregulating SOX5.

The combination of bevacizumab/Avastin and erlotinib/Tarceva is relevant for the treatment of metastatic renal cell carcinoma: the role of a synonymous mutation of the EGFR receptor

Metastatic clear cell renal cell carcinomas (mRCC) over-express the vascular endothelial growth factor (VEGF). Hence, the anti-VEGF antibody bevacizumab/Avastin (BVZ) combined with interferon alpha (IFN) was approved for the treatment of mRCC. However, approval was lost in July 2016 due to the absence of sustained efficacy. We previously showed that BVZ accelerates tumor growth in experimental models of mRCC in mice, results in part explained by down-regulation of the phospho tyrosine phosphatase receptor kappa (PTPRκ) in tumor cells. The epidermal growth factor receptor (EGFR) is a direct target of PTPRκ. Its down-regulation leads to constitutive activation of EGFR, an observation which prompted us to test the effect of the EGFR inhibitor erlotinib/Tarceva (ERLO) in addition to BVZ/IFN. The influence of the long non-coding RNA, EGFR-AS1, on ERLO efficacy was also addressed.

Methods: The effect of BVZ/IFN/ERLO was tested on the growth of experimental tumors in nude mice. The presence of germline mutation in the EGFR was evaluated on cell lines and primary RCC cells. In vitro translation and transfections of expression vectors coding the wild-type or the EGFR mutated gene in HEK-293 cells were used to test the role of EGFR mutation of the ERLO efficacy. Correlation between EGFR/EGFR-AS1 expression and survival was analyzed with an online available data base (TCGA).

Results: Tumor growth was strongly reduced by the triple combination BVZ/IFN/ERLO and linked to reduced levels of pro-angiogenic/pro-inflammatory cytokines of the ELR+CXCL family and to subsequent inhibition of vascularization, a decreased number of lymphatic vessels and polarization of macrophages towards the M1 phenotype. Cells isolated from surgical resection of human tumors presented a range of sensitivity to ERLO depending on the presence of a newly detected mutation in the EGFR and to the presence of EGFR-AS1.

Conclusions: Our results point-out that the BVZ/IFN/ERLO combination deserves testing for the treatment of mRCC that have a specific mutation in the EGFR.

LncRNA HCP5 promotes triple negative breast cancer progression as a ceRNA to regulate BIRC3 by sponging miR-219a-5p

Emerging evidence has suggested that long noncoding RNAs (lncRNA) involved in the development and progression of cancer. Triple negative breast cancer (TNBC) was an aggressive type of breast cancer with high rates of cancer recurrence and metastasis. The pathogenesis of TNBC is largely unknown. Recent studies suggested that lncRNA HCP5 plays an important role in carcinogenesis. The purpose of this study was to examine the function and mechanism of HCP5 in TNBC. We observed that HCP5 was upregulated in TNBC cell lines and specimens. HCP5 knockdown induced TNBC cell apoptosis, and inhibited cell proliferation and orthotopic xenograft tumor growth. RNA sequencing and antibody array suggested that HCP5 achieves its functions through regulating apoptosis pathway. Bioinformatics, luciferase and RIP experiments proved that both HCP5 and BIRC3 could competitively bind to miR‐219a‐5p. Increased BIRC3 and decreased miR‐219a‐5p were observed in TNBC tissues and cell lines. We then performed gain‐ and loss‐of‐function studies as well as rescue experiments in TNBC cells. The decrease of proliferation and migration due to HCP5 knockdown could be rescued when miR‐219a‐5p inhibitor or BIRC3 was transfected and vice versa. Our study suggested that lncRNA HCP5 promotes TNBC progression as a ceRNA to regulate BIRC3 by sponging miR‐219a‐5p. In a word, we revealed a new signaling pathway to mediate TNBC, and provided HCP5 as a new target for improving treatment of TNBC.

Metformin, a first-line drug for type 2 diabetes mellitus, disrupts the MALAT1/miR-142-3p sponge to decrease invasion and migration in cervical cancer cells

The molecular mechanisms underlying the anti-neoplastic properties of metformin, a first-line drug for type 2 diabetes, remain elusive. To explore the novel anti-neoplastic mechanisms of metformin, the transwell chamber and wound-healing assays were used to evaluate its effects on the migration and invasion of human cervical cancer cells. Real-time PCR and Western blotting were used to measure the gene and protein expression, respectively, of microRNA (miRNA) miR-142-3p, long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), and high-mobility group AT-hook 2 (HMGA2). The dual-luciferase reporter assay system was used to examine the direct interaction between miR-142-3p and lncRNA MALAT1 and HMGA2. Immunofluorescence was used to detect the protein expression of HMGA2. In addition, tumor xenografts in a nude mouse model were developed to evaluate the anti-tumor efficacy of metformin. We found that metformin could suppress cervical cancer migration and invasion. During the process of tumor metastasis, miR-142-3p was significantly upregulated, whereas lncRNA MATAL1 and HMGA2 were suppressed by metformin. The binding site that allow the direct interaction between miR-142-3p and MALAT1 were located in the 3' untranslated region (3' UTR) of lncRNA MATAL1 and HMGA2 at base pairs (bp) 4452-5255, while that between miR-142-3p and HMGA2 was located at bp 1562-2521 of HMGA2. Metformin markedly inhibited the growth and angiogenesis of SiHa xenografts in nude mice. In conclusion, this study provides evidence that metformin can prevent the MALAT1/miR-142-3p sponge from developing anti-neoplastic properties in human cervical cancer cells and cervical cancer cell xenografts in nude mice. Thus, our findings demonstrate the novel anti-tumor effects of metformin in cervical cancer.