microRNA-761 induces aggressive phenotypes in triple-negative breast cancer cells by repressing TRIM29 expression

CircDUSP1 regulates tumor growth, metastasis, and paclitaxel sensitivity in triple-negative breast cancer by targeting miR-761/DACT2 signaling axis

Triple-negative breast cancer TNBC) is a malignant tumor with high incidence and high mortality that threaten the health of women worldwide. Circular RNAs (circRNAs) are a new class of noncoding RNAs that participate in the biological processes of various tumors, but the regulatory roles of circRNAs in TNBC have not been fully elucidated. In this study, the expression and characterization of circDUSP1 was detected via quantitative real-time PCR, nuclear-cytoplasmic fractionation assay, and fluorescence in situ hybridization. Then, in vitro and in vivo functional experiments were performed to evaluate the effects of circDUSP1 in TNBC. The interaction among circDUSP1, miR-761, DACT2 were confirmed by dual luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation experiments. We identified the circRNA named circDUSP1 that was inversely correlated with tumorigenesis and progression in TNBC. Overexpression of circDUSP1 significantly attenuated cell proliferation, migration, invasion, and epithelial-mesenchymal transition, while increased the sensitivity of TNBC cells to paclitaxel. In-depth mechanism analysis indicated that circDUSP1 acts as an endogenous sponge of miR-761 to reduce its suppression on target gene DACT2 expression in TNBC. Upregulation of miR-761 or downregulation of DACT2 partially reversed the biological process of TNBC and the prognosis of paclitaxel affected by circDUSP1. Taken together, our findings revealed a role for the regulation of the miR-761/DACT2 axis by circDUSP1 in the biological process of TNBC. These results provided new insights into the biological mechanism and targeted therapy of TNBC.

New insights in ferroptosis: Potential therapeutic targets for the treatment of ischemic stroke

Stroke is a common disease in clinical practice, which seriously endangers people's physical and mental health. The neurovascular unit (NVU) plays a key role in the occurrence and development of ischemic stroke. Different from other classical types of cell death such as apoptosis, necrosis, autophagy, and pyroptosis, ferroptosis is an iron-dependent lipid peroxidation-driven new form of cell death. Interestingly, the function of NVU and stroke development can be regulated by activating or inhibiting ferroptosis. This review systematically describes the NVU in ischemic stroke, provides a comprehensive overview of the regulatory mechanisms and key regulators of ferroptosis, and uncovers the role of ferroptosis in the NVU and the progression of ischemic stroke. We further discuss the latest progress in the intervention of ferroptosis as a therapeutic target for ischemic stroke and summarize the research progress and regulatory mechanism of ferroptosis inhibitors on stroke. In conclusion, ferroptosis, as a new form of cell death, plays a key role in ischemic stroke and is expected to become a new therapeutic target for this disease.

The abnormal expression of circ-ARAP2 promotes ESCC progression through regulating miR-761/FOXM1 axis-mediated stemness and the endothelial-mesenchymal transition

Circular RNAs (circRNAs) belong to a novel class of noncoding RNA that gained more attention in human cancer pathogenesis. The role of circRNA in esophageal squamous cell carcinoma (ESCC) is largely unclear. Present investigation was to characterize new circRNAs regulating ESCC progression and explore the regulatory mechanisms in ESCC. In this study, circRNAs differentially expressed in ESCC and adjacent normal tissues were characterized via high-throughput sequencing. Then the differentially expressed circRNA between ESCC and adjacent normal tissues were investigated using Rt-qPCR. The role of circ-ARAP2 expression on tumor progression were detected in both in vivo and in vitro. Luciferase reporter assays were used to identify the relationships among circ-ARAP2, microRNA (miR)-761 and the cell cycle regulator Forkhead Box M1 (FOXM1). The result of the expression profile analyses regarding human circRNAs in ESCC demonstrated that circ-ARAP2 was up-regulated significantly in both ESCC tissues and cell lines. Downregulation circ-ARAP2 suppressed ESCC proliferation, tumor growth and metastasis in both in vivo and in vitro. The data also suggested that miR-761 and FOXM1 were circ-ARAP2 downstream targets which were confirmed through luciferase reporter analysis. Overexpression of FOXM1 or inhibiting miR-761 restored ESCC cell proliferation and invasion ability after silencing circ-ARAP2. The study also found that circ-ARAP2 influenced the endothelial-mesenchymal transition (EMT) and cancer stem cells differently by regulating miR-761/FOXM1. In one word, the results demonstrated that abnormal circ-ARAP2 expression promoted ESCC progression by regulating miR-761/FOXM1 axis-mediated stemness and EMT.

MiR-106b-5p Attenuates Neuropathic Pain by Regulating the P2X4 Receptor in the Spinal Cord in Mice

The P2X4 receptor (P2X4R) can be upregulated after nerve injury, and its mediated spinal microglial activation makes a critical contribution to pathologically enhanced pain processing in the dorsal horn. Although some studies have partly clarified the mechanism underlying altered P2X4R expression, the specific mechanism is not well understood. MicroRNAs (miRNAs) are small noncoding RNAs which control gene expression by binding with their target mRNAs. Thus, in the present study, we investigated whether miRNA is involved in the pathogenesis of neuropathic pain by regulating P2X4R. Our results showed that P2X4R was upregulated in the spinal dorsal horn of mice following spared nerve injury (SNI), and 69 miRNAs (46 upregulated and 23 downregulated miRNAs) were differentially expressed (fold change > 2.0, P < 0.05). P2X4R was found to be a major target of miR-106b-5p (one of the downregulated miRNAs) using bioinformatics technology; quantitative real-time PCR analysis confirmed the change in expression of miR-106b-5p, and dual-luciferase reporter assays confirmed the correlation between them. Fluorescence in situ hybridization was used to show cell co-localization of P2X4R and miR-106b-5p in the spinal dorsal horn. Transfection with miR-106b-5p mimic into BV2 cells reversed the upregulation of P2X4R induced by lipopolysaccharide (LPS). Moreover, miR-106b-5p overexpression significantly attenuated neuropathic pain induced by SNI, with decreased expression of P2X4R mRNA and protein in the spinal dorsal horn; intrathecal miR-106b-5p antagomir induced pain behaviors, and increased expression of P2X4R in the spinal dorsal horn of naïve mice. These data suggest that miR-106b-5p can serve as an important regulator of neuropathic pain development by targeting P2X4R.

Suppression of MIR31HG affects the functional properties of thyroid cancer cells depending on the miR-761/MAPK1 axis

BACKGROUND

Thyroid cancer is the most prevalent endocrine malignancy. Long non-coding RNA (lncRNA) MIR31HG is abnormally expressed in thyroid cancer tissues. However, the precise, critical role of MIR31HG in thyroid cancer development remains unclear.

METHODS

MIR31HG, microRNA (miR)-761 and mitogen-activated protein kinase 1 (MAPK1) were quantified by quantitative real-time PCR (qRT-PCR) and immunoblotting. Cell viability, proliferation, apoptosis, invasion and migration abilities were evaluated by MTS, 5-Ethynyl-2'-Deoxyuridine (EdU), flow cytometry, transwell and wound-healing assays, respectively. Dual-luciferase reporter assays were used to validate the direct relationship between miR-761 and MIR31HG or MAPK1.

RESULTS

MIR31HG was overexpressed in human thyroid cancer, and its overexpression predicted poor prognosis. Suppression of MIR31HG impeded cell proliferation, invasion and migration, as well as promoted cell apoptosis in vitro, and diminished the growth of xenograft tumors in vivo. Mechanistically, MIR31HG targeted and regulated miR-761. Moreover, miR-761 was identified as a molecular mediator of MIR30HG function in regulating thyroid cancer cell behaviors. MAPK1 was established as a direct and functional target of miR-761 and MAPK1 knockdown phenocopied miR-761 overexpression in impacting thyroid cancer cell behaviors. Furthermore, MIR31HG modulated MAPK1 expression by competitively binding to miR-761 via the shared binding sequence.

CONCLUSION

Our findings demonstrate that MIR31HG targets miR-761 to regulate the functional behaviors of thyroid cancer cells by upregulating MAPK1, highlighting a strong rationale for developing MIR31HG as a novel therapeutic target against thyroid cancer.

Targeting regulated cell death (RCD) with small-molecule compounds in triple-negative breast cancer: a revisited perspective from molecular mechanisms to targeted therapies

Triple-negative breast cancer (TNBC) is a subtype of human breast cancer with one of the worst prognoses, with no targeted therapeutic strategies currently available. Regulated cell death (RCD), also known as programmed cell death (PCD), has been widely reported to have numerous links to the progression and therapy of many types of human cancer. Of note, RCD can be divided into numerous different subroutines, including autophagy-dependent cell death, apoptosis, mitotic catastrophe, necroptosis, ferroptosis, pyroptosis and anoikis. More recently, targeting the subroutines of RCD with small-molecule compounds has been emerging as a promising therapeutic strategy, which has rapidly progressed in the treatment of TNBC. Therefore, in this review, we focus on summarizing the molecular mechanisms of the above-mentioned seven major RCD subroutines related to TNBC and the latest progress of small-molecule compounds targeting different RCD subroutines. Moreover, we further discuss the combined strategies of one drug (e.g., narciclasine) or more drugs (e.g., torin-1 combined with chloroquine) to achieve the therapeutic potential on TNBC by regulating RCD subroutines. More importantly, we demonstrate several small-molecule compounds (e.g., ONC201 and NCT03733119) by targeting the subroutines of RCD in TNBC clinical trials. Taken together, these findings will provide a clue on illuminating more actionable low-hanging-fruit druggable targets and candidate small-molecule drugs for potential RCD-related TNBC therapies.

Long noncoding RNA ADIRF antisense RNA 1 upregulates insulin receptor substrate 1 to decrease the aggressiveness of osteosarcoma by sponging microRNA-761

An increasing number of studies have supported the critical regulatory actions of long noncoding RNAs (lncRNAs) in osteosarcoma (OS). However, the detailed roles of adipogenesis regulatory factor-antisense RNA 1 (ADIRF-AS1) in OS have not been comprehensively described. Hence, we first detected ADIRF-AS1 expression in OS and evaluated its clinical significance. Functional experiments were then performed to determine the modulatory role of ADIRF-AS1 in OS progression. ADIRF-AS1 was found to be overexpressed in OS, and the overall survival of patients with OS who had high ADIRF-AS1 levels was shorter than that of those with low levels. ADIRF-AS1 knockdown led to restricted proliferation, migration, and invasiveness of OS cells and increased apoptosis. Additionally, ADIRF-AS1 downregulation impeded tumor growth in vivo. Mechanistically, ADIRF-AS1 acted as a competitive endogenous RNA for microRNA-761 (miR-761) that siphoned miR-761 away from its target, namely insulin receptor substrate 1 (IRS1), leading to IRS1 overexpression. Rescue experiments showed that low levels of miR-761 or restoration of IRS1 could neutralize the effects of ADIRF-AS1 ablation in OS cells. In summary, ADIRF-AS1 exacerbates the oncogenicity of the OS cells by targeting the miR-761/IRS1 axis. Our findings may aid in the advancement of lncRNA-directed therapeutics for OS.

TRIM29 in Cutaneous Squamous Cell Carcinoma

Tripartite motif (TRIM) proteins play important roles in a wide range of cell physiological processes, such as signal transduction, transcriptional regulation, innate immunity, and programmed cell death. TRIM29 protein, encoded by the ATDC gene, belongs to the RING-less group of TRIM protein family members. It consists of four zinc finger motifs in a B-box domain and a coiled-coil domain, and makes use of the B-box domain as E3 ubiquitin ligase in place of the RING. TRIM29 was found to be involved in the formation of homodimers and heterodimers in relation to DNA binding; additional studies have also demonstrated its role in carcinogenesis, DNA damage signaling, and the suppression of radiosensitivity. Recently, we reported that TRIM29 interacts with keratins and FAM83H to regulate keratin distribution. Further, in cutaneous SCC, the expression of TRIM29 is silenced by DNA methylation, leading to the loss of TRIM29 and promotion of keratinocyte migration. This paper reviews the role of TRIM family proteins in malignant tumors, especially the role of TRIM29 in cutaneous SCC.

TRIM29 regulates the SETBP1/SET/PP2A axis via transcription factor VEZF1 to promote progression of ovarian cancer

Ovarian cancer (OC) is a common gynecological malignant tumor that seriously endangers the health of women worldwide. Tripartite motif containing 29 (TRIM29) is a TRIM family member that is frequently overexpressed in OC. However, the specific role of TRIM29 in OC remains obscure. To investigate the underlying molecular mechanism, a global proteomics analysis identified SET binding protein 1 (SETBP1) as a crucial target of TRIM29. Subsequently, the SETBP1/SET/Protein phosphatase 2 (PP2A) axis was confirmed to be required for the recovery of cancer stem cell (CSC)-like phenotype suppressed by TRIM29 knockdown. Mechanistically, TRIM29 facilitated SETBP1 transcriptional activation via the VEZF1 transcription factor. More importantly, TRIM29 promoted VEZF1 mRNA translation by recruiting RNA binding protein BICC1 to its 3'UTR. The clinical significance was established by the association of TRIM29 and SETBP1 expression with clinicopathological features in OC samples. The SETBP1/SET/PP2A axis driven by TRIM29 via transcription factor VEZF1 is at least one of the primary mechanisms underlying TRIM29 maintenance of the CSC-like characteristics in OC.

CircIL4R activates the PI3K/AKT signaling pathway via the miR-761/TRIM29/PHLPP1 axis and promotes proliferation and metastasis in colorectal cancer

BACKGROUND

Accumulating studies have revealed that aberrant expression of circular RNAs (circRNAs) is widely involved in the tumorigenesis and progression of malignant cancers, including colorectal cancer (CRC). Nevertheless, the clinical significance, levels, features, biological function, and molecular mechanisms of novel circRNAs in CRC remain largely unexplored.

METHODS

CRC-related circRNAs were identified through bioinformatics analysis and verified in clinical specimens by qRT-PCR and in situ hybridization (ISH). Then, in vitro and in vivo experiments were performed to determine the clinical significance of, functional roles of, and clinical characteristics associated with circIL4R in CRC specimens and cells. Mechanistically, RNA pull-down, fluorescence in situ hybridization (FISH), luciferase reporter, and ubiquitination assays were performed to confirm the underlying mechanism of circIL4R.

RESULTS

CircIL4R was upregulated in CRC cell lines and in sera and tissues from CRC patients and was positively correlated with advanced clinicopathological features and poor prognosis. Functional experiments demonstrated that circIL4R promotes CRC cell proliferation, migration, and invasion via the PI3K/AKT signaling pathway. Mechanistically, circIL4R was regulated by TFAP2C and competitively interacted with miR-761 to enhance the expression of TRIM29, thereby targeting PHLPP1 for ubiquitin-mediated degradation to activate the PI3K/AKT signaling pathway and consequently facilitate CRC progression.

CONCLUSIONS

Our findings demonstrate that upregulation of circIL4R plays an oncogenic role in CRC progression and may serve as a promising diagnostic and prognostic biomarker for CRC detection and as a potential therapeutic target for CRC treatment.

Variation of Long Non-Coding RNA And mRNA Profiles in Breast Cancer Cells With Influences of Adipocytes

Background

It is well known that obesity is one of the risks for incurrence and development in breast cancer patients. Long non-coding RNAs (lncRNAs) are reported to participate in the composition of tumor microenvironment and to regulate breast cancer cell metabolic activities. However, there was rare study focused on the lncRNAs in breast cancer with the influences of adipocytes. The study aimed to investigate lncRNAs expression profiles and discover potential biomarkers to predict the incidence and progression of adipocyte-associated-breast cancer.

Methods

We co-cultured adipocytes with breast cancer cells and profiled the expression of lncRNAs as well as mRNAs by using the RNA-sequencing method. Wound Healing, Migration assays and Invasion assays were applied to verify the invasion and metastasis of cancer cells.

Results

MDA-MB-231/Hpa-V and SK-BR-3/Hpa-V cells showed elevated migration and invasiveness compared to the control group. A sum of 371 mRNAs (181 upregulated and 190 downregulated) and 850 lncRNAs(414 upregulated and 436 downregulated) were differentially expressed in MDA-MB-231/Hpa-V comparing to MDA-MB-231(P < 0.05; |log2 (fold change)|>1.2). GO enrichment, KEGG pathway and interaction networks demonstrated that differentially expressed lncRNAs were involved in functional categories, such as material metabolism, which might lead to the progression of breast cancer.

Conclusion

Our study detected a lncRNA profile in breast cancer cells affecting by adipocytes and provided a better understanding of the tumor microenvironment. LncRNAs may be helpful to predict the therapeutic responses and prognosis of obese breast cancer patients.

TRIM29 Reverses Oxaliplatin Resistance of P53 Mutant Colon Cancer Cell

Background

Oxaliplatin is the first-choice chemotherapy method for patients with advanced colon cancer. However, its resistance leads to treatment failure for many patients. In our experiments, we aim to elucidate the associations among TRIM29 protein, mutant P53, and the resistance of colon cancer cells to oxaliplatin.

Methods

HCT116 and HT-29 cells were cultured and transfected with plasmids pIRES2-ZsGreen1-TRIM29-flag. Western blot and real-time qRT-PCR were utilized to examine the protein and mRNA expressions of TRIM29 and other related markers, respectively. MTT assay was utilized to determine the cell growth rate and generate the inhibition curve. Continuous culture in low-concentration oxaliplatin was conducted to construct oxaliplatin-resistant cell lines. The coimmunoprecipitation method and immunofluorescence detection were used to examine the interaction between TRIM29 and mutant P53 protein in HT29 cells.

Results

We successfully transfected pIRES2-ZsGreen1-TRIM29-flag into HCT116 and HT29 cells, which were utilized in the whole experiments. TRIM29 significantly increased the sensitivity of P53 mutant colon cancer cell HT29 to oxaliplatin. The oxaliplatin-resistant model of P53 mutant colon cancer cell HT29 was successfully constructed. TRIM29 physically bound with mutant P53 and retained it in the cytoplasm from the nucleus, which inhibited its transcription function of downstream genes such as MDR1. In addition, TRIM29 successfully reversed the resistance of HT29-OX resistant cell model to oxaliplatin.

Conclusion

In mutant P53 colon cancer cell HT29, TRIM29 greatly increased the sensitivity of HT29 to oxaliplatin and reverse oxaliplatin resistance. The underlying mechanism is TRIM29 may increase the sensitivity of HT29 to oxaliplatin by blocking the transcriptional function of mutant P53, which inhibits the transcription function of its downstream gene such as MDR1.

Imbalance of Molecular Module of TINCR-miR-761 Promotes the Metastatic Potential of Early Triple Negative Breast Cancer and Partially Offsets the Anti-Tumor Activity of Luteolin

Background

Triple negative breast cancer (TNBC) poses a great threat to patient prognosis. LncRNA-miRNA is a molecular module formed by a long non-coding RNA (LncRNA) and a microRNA (miRNA) that mediates the metastatic potential of tumours such as TNBC, and luteolin (LU) is a natural compound with anti-TNBC activity.

Objective

We aim to explore the regulatory mechanism of terminal differentiation-induced non-coding RNA (TINCR)-miR-761 molecular module in early TNBC, as well as its influence on anti-tumor activity of LU.

Methods

The serum was collected from TNBC patients in early stage to detect the expression of TINCR and miR-761 using RT-PCR. Transwell method was applied for the determination of cell migration and invasion, Western blot for epithelial–mesenchymal transition (EMT), flow cytometry (FCM) for cell apoptosis, and dual luciferase reporter and RNA pull-down experiment for the verification of the targeted relationship between TINCR and miR-761.

Results

Both TINCR and miR-761 were up-regulated in the serum of patients with early TNBC and the area under the curve (AUC) of the two for distinguishing TNBC from BC was not less than 0.850. In the cell function tests, down-regulation of TINCR or miR-761 notably suppressed the metastatic potentials (cell migration, invasion and EMT) of TNBC cells were remarkably inhibited, while up-regulation of TINCR or miR-761 notably promoted the metastatic potentials. We also confirmed that TINCR acts as the molecular sponge of miR-761, and has positive regulation on it. Besides, LU can significantly down-regulate TINCR and miR-761, and partially offset the anti-TNBC activity of LU when they were abnormally up-regulated, which was mainly reflected in the decrease of anti-proliferation and pro-apoptotic ability of LU against TNBC.

Conclusion

There is an imbalance of TINCR-miR-761 molecular module in early TNBC, which may be a potential new therapeutic target of TNBC.

Triterpenoid Saponin AG8 from Ardisia gigantifolia stapf. Induces Triple Negative Breast Cancer Cells Apoptosis through Oxidative Stress Pathway

Triple-negative breast cancers (TNBCs) are associated with poor patient survival because of the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expressions. Our previous studies have shown that the triterpenoid saponin AG8 from Ardisia gigantifolia stapf. inhibits the proliferation of MDA-MB-231 cells. In this study, the effects of AG8 were further analyzed in different TNBC cell types: MDA-MB-231, BT-549, and MDA-MB-157 cells. AG8 inhibited the viability of MDA-MB-231, BT-549, and MDA-MB-157 cells in a dose-dependent manner and showed stronger cytotoxicity to African American (AA) and mesenchymal (M) subtypes than Caucasian (CA) and mesenchymal stem-like (MSL) subtypes, respectively. AG8 impaired the uptake of MitoTracker Red CMXRos by the mitochondria of TNBC cells in a dose-dependent manner, and this was recovered by N-acetyl-l-cysteine (NAC). AG8 affected GSH, SOD, and MDA levels of TNBC cells, but different TNBC subtypes had different sensitivities to AG8 and NAC. In addition, we found that AG8 increased the Bax/Bcl-2 ratio and the levels of cytoplasmic cytochrome c and significantly decreased phosphorylation of ERK and AKT in BT549 and MDA-MB-157 cells. AG8 elicited its anticancer effects through ROS generation, ERK and AKT activation, and by triggering mitochondrial apoptotic pathways in TNBC cells. AG8 had selective cytotoxic effects against the AA and M TNBC subtypes and markedly induced MDA-MB-157 (AA subtype) cell apoptosis through pathways that were not associated with ROS, which was different from the other two subtypes. The underlying mechanisms should be further investigated.

Long Noncoding RNA KCNQ1OT1 Confers Gliomas Resistance to Temozolomide and Enhances Cell Growth by Retrieving PIM1 From miR-761

Many studies have found that the dysregulation of long noncoding RNA (lncRNA) contributed to cancer initiation, progression, and recurrence via multiple signaling pathways. However, the underlying mechanisms of lncRNA in temozolomide (TMZ)-resistant gliomas were not well understood, hindering the improvement of TMZ-based therapies. The present study demonstrated that the lncRNA KCNQ1OT1 increased in TMZ-resistant glioma cells compared to the TMZ-sensitive cells. The introduction of KCNQ1OT1 promoted cell viability, clonogenicity, and rhodamine 123 efflux while hampering TMZ-induced apoptosis. Moreover, KCNQ1OT1 directly sponged miR-761, which decreased in TMZ-resistant sublines. The overexpression of miR-761 attenuated cell viability and clonogenicity, while triggering apoptosis and rhodamine 123 accumulation post-TMZ exposure, leading to a response to TMZ. The interaction between miR-761 and 3'-untranslated region of PIM1 attenuated PIM1-mediated signaling cascades. Furthermore, the knockdown of KCNQ1OT1 augmented the TMZ-induced tumor regression in TMZ-resistant U251 mouse models. Briefly, the present study evaluated that KCNQ1OT1 conferred TMZ resistance by releasing PIM1 expression from miR-761, resulting in the upregulation of PIM-mediated MDR1, c-Myc, and Survivin. The present findings demonstrated that the interplay of KCNQ1OT1: miR-761: PIM1 regulated chemoresistance in gliomas and provided a promising therapeutic target for TMZ-resistant glioma patients.

Circular RNA La-related RNA-binding protein 4 correlates with reduced tumor stage, as well as better prognosis, and promotes chemosensitivity to doxorubicin in breast cancer

OBJECTIVE

We aimed to evaluate the correlation of circular RNA La-related RNA-binding protein 4 (circ-LARP4) with tumor characteristics and prognosis, and its effect on chemosensitivity in breast cancer.

METHODS

Circ-LARP4 from tumor and adjacent tissues of 283 female breast cancer patients underwent resection was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Tumor features, disease-free survival (DFS), and overall survival (OS) were recorded. In vitro, circ-LARP4 in human normal mammary epithelial cells (HMEC) and breast cancer cell lines was detected by RT-qPCR. MCF-7 and MDA-MB-231 cells were transfected with circ-LARP4 overexpression plasmid (as OE-Circ group) and control overexpression plasmid (as OE-Control group). Relative cell viability under different concentrations of doxorubicin was measured.

RESULTS

Circ-LARP4 was decreased in tumor tissues than adjacent tissues (P < .001). Tumor circ-LARP4 negatively correlated with tumor size (P = .001), T stage (P = .009), N stage (P = .006), and TNM stage (P < .001), whereas positively correlated with DFS (P = .004) and OS (P < .001). In vitro, circ-LARP4 was decreased MCF-7, BT474, MDA-MB-231, and MDA-MB-468 cell lines than HMEC (all P < .001). Relatively cell viability of MCF-7 cells (at 20 nmol/L [P < .05], 40 nmol/L [P < .01], 80 nmol/L [P < .05] of doxorubicin) and MDA-MB-231 cells (at 120 nmol/L [P < .05], 240 nmol/L [P < .05] of doxorubicin) was decreased in OE-Circ group than OE-Control group. IC50 value of doxorubicin was decreased in OE-Circ group than OE-Control group in MCF-7 and MDA-MB-231 cell lines (both P < .01).

CONCLUSION

Circ-LARP4 was a potential prognostic biomarker, which might improve the management of breast cancer.

MicroRNA-761 suppresses remodeling of nasal mucosa and epithelial-mesenchymal transition in mice with chronic rhinosinusitis through LCN2

Background

Chronic rhinosinusitis (CRS) is characterized by persistent symptomatic inflammation of the nasal passage and sinus mucosa. Various microRNAs (miRs) have been implicated in CRS. Hence, the current study was conducted to explore the effect of microRNA-761 (miR-761) on remodeling of nasal mucosa and epithelial–mesenchymal transition (EMT).

Methods

Bioinformatics analysis was initially performed to predict the differentially expressed genes (DEGs) associated with CRS. Gene targeting relationship between miR-761 and lipocalin 2 (LCN2) was analyzed by bioinformatics analysis and verified using dual-luciferase reporter gene assay. Histopathological analyses of the nasal mucosa tissues were conducted via hematoxylin–eosin (HE) and alcian blue (AB)-periodic acid Schiff (PAS) staining. ELISA was employed to determine the IL-8 and MMP-9 levels. To define downstream pathway of miR-761, levels of proteins related to LCN2/Twist1 signaling pathway were assessed. Additionally, the effects of miR-761 on EMT, proliferation, and apoptosis were determined.

Results

LCN2 was highly expressed in CRS. LCN2 was a target of miR-761. miR-761 overexpression or LCN2 silencing decreased IL-8 and MMP-9 levels and morphological changes in nasal epithelial tissue from CRS mice. Overexpressed miR-761 or silenced LCN2 decreased the expression of LCN2 and Twist1, indicating LCN2/Twist1 signaling pathway was inactivated. Moreover, miR-761 overexpression or LCN2 silencing reduced the expression of N-cadherin and vimentin, while increased that of E-cadherin, suggesting inhibition of EMT. Furthermore, miR-761 overexpression or LCN2 silencing promoted cell proliferation and inhibited cell apoptosis in CRS.

Conclusion

Taken together, miR-761 suppressed the remodeling of nasal mucosa through inhibition of LCN2 and the LCN2/Twist1 signaling pathway.

Systematic characterization of non-coding RNAs in triple-negative breast cancer

Triple‐negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer with negativity for oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2). Non‐coding RNAs (ncRNAs) make up most of the transcriptome and are widely present in eukaryotic cells. In recent years, emerging evidence suggests that ncRNAs, mainly microRNAs (miRNAs), long ncRNAs (lncRNAs) and circular RNAs (circRNAs), play prominent roles in the tumorigenesis and development of TNBC, but the functions of most ncRNAs have not been fully described. In this review, we systematically elucidate the general characteristics and biogenesis of miRNAs, lncRNAs and circRNAs, discuss the emerging functions of these ncRNAs in TNBC and present future perspectives in clinical practice.

lncRNA-TINCR Functions as a Competitive Endogenous RNA to Regulate the Migration of Mesenchymal Stem Cells by Sponging miR-761

Mounting evidences have indicated that terminal differentiation-induced lncRNA (TINCR) contributes to various cellular processes, such as proliferation, apoptosis, autophagy, migration, invasion, and metastasis. However, the function of TINCR in regulating migration of MSCs is largely unknown. In this study, the effects of TINCR on the migration of rat MSCs from the bone marrow were studied by Transwell assays and wound healing assays. Our results suggested that TINCR positively regulated migration of rMSCs. miR-761 mimics suppressed rMSC migration, whereas miR-761 inhibitor promoted migration. Target prediction analysis tools and dual-luciferase reporter gene assay identified Wnt2 as a direct target of miR-761. miR-761 could inhibit the expression of Wnt2. Further, the investigation about the function of TINCR in miR-761-induced migration of rMSCs was completed. These results demonstrated that TINCR took part in the regulation of miR-761-induced migration in rMSCs through the regulation of Wnt2 and its Wnt2 signaling pathway. Taken together, our results demonstrate that lncRNA-TINCR functions as a competitive endogenous RNA (ceRNA) to regulate the migration of rMSCs by sponging miR-761 which modulates the role of Wnt2. These findings provide evidence that lncRNA-TINCR has a chance to serve as a potential target for enhancing MSC homing through the miR-761/Wnt2 signaling pathway.

Identification of a potential prognostic lncRNA-miRNA-mRNA signature in endometrial cancer based on the competing endogenous RNA network

Endometrial cancer is one of the most common gynecological malignant tumors. The roles of competing endogenous RNAs (ceRNAs) in this disease, however, remain unclear. In this study, we constructed a ceRNA network to reveal the core ceRNAs in endometrial cancer. Differentially expressed genes were summarized from The Cancer Genome Atlas database, whereupon 140 genes were identified for building the network. Further correlation, survival, and enrichment analyses suggested that these genes may help towards elucidating the molecular mechanisms of endometrial cancer. After validation of the findings with the GSE17025 data set, LINC00958, microRNA-761, and DOLPP1 were highlighted as the critical genes in the ceRNA network. Our work suggests that LINC00958 may regulate DOLPP1 by "sponging" miR-761 in endometrial cancer.

MicroRNA-761 targets FGFR1 to suppress the malignancy of osteosarcoma by deactivating PI3K/Akt pathway

Purpose

MicroRNA-761 (miR-761) has been reported to be deregulated in many types of human cancers and play important roles in cancer genesis and progression. However, the biological roles of miR-761 in osteosarcoma (OS) and the underlying mechanisms remain largely unknown.

Methods

The expression of miR-761 in OS tissues and cell lines was analyzed using RT-qPCR. A series of gain-of-function tests were performed, and status of malignancy was evaluated on basis of proliferation, migration, invasion, and apoptosis using different assays to determine the regulatory roles of miR-761 in OS cells in vivo and in vitro. Notably, the mechanisms underlying the action of miR-761 in the pathogenesis of OS were investigated using bioinformatic analysis, luciferase reporter assay, RT-qPCR and Western blotting.

Results

The results showed that miR-761 expression was decreased in OS tissues and cell lines and is closely correlated with clinical stage and distant metastasis in OS patients. Patients with OS having low miR-761 expression showed worse prognosis compared to OS patients with high miR-761 expression. Restoring the miR-761 expression level decreased OS cell proliferation, migration, and invasion in vitro; promoted cell apoptosis in vitro; and impaired tumor growth in vivo. In addition, fibroblast growth factor receptor 1 (FGFR1) was found as a direct target gene of miR-761 in OS cells. Furthermore, silencing FGFR1 expression stimulated the tumor-suppressing roles of miR-761 upregulation in OS cells, whereas the activity of miR-761 overexpression in OS cells was abolished by the restoration of FGFR1 expression. Moreover, restoration of miR-761 expression deactivated the PI3K/Akt pathway in vitro and in vivo.

Conclusion

These results suggest that miR-761 plays anti-cancer roles in OS by directly targeting FGFR1 and deactivating the PI3K/Akt pathway. The newly identified miR-761/FGFR1/PI3K/Akt pathway partially illustrates the mechanism of OS pathogenesis and presents a novel candidate therapeutic target for antitumor therapy.

LncRNA FENDRR suppresses the progression of NSCLC via regulating miR-761/TIMP2 axis

To explore the roles of long noncoding RNA (lncRNA) FOXF1 Adjacent Non-Coding Developmental Regulatory RNA (FENDRR) in human non-small cell lung cancer (NSCLC). The levels of FENDRR in NSCLC cells and tissues were analyzed using qRT-PCR assay. The growth and colony formation abilities of NSCLC cell were analyzed by the MTT and colony formation tests. The mobility and invasiveness of NSCLC cell were analyzed using the wound closure and Transwell invasion assay. The impact of FENDRR on the tumor growth of NSCLC cells in vivo was detected using xenograft model. Bioinformatics analysis and luciferase reporter gene bioassay were selected to identify the bindings sites between miR-761 and FENDRR. Additional, the results of Transwell invasion and colony formation experiments indicated that FENDRR inhibited the aggressiveness of NSCLC depend on miR-761. Tissue inhibitor of metalloproteinase 2 (TIMP2) was identified as the downstream target of miR-761 and its level was positively regulated by FENDRR. Cotransfection assays using A549 and H1975 cells future implied that downexpression of TIMP2 rescued the aggressiveness phenotypes of NSCLC cell inhibited by FENDRR. Altogether, we demonstrated that lncRNA FENDRR suppressed the progression of NSCLC via binding to miR-761 and regulating TIMP2 expression.

MicroRNA-761 inhibits the metastasis of gastric cancer by negatively regulating Ras and Rab interactor 1

Gastric cancer (GC), the second most common malignant cancer worldwide, gives rise to a number of cancer-associated fatalities annually. Accumulating evidence has shown that microRNAs (miRs) may serve as oncogenes or tumor suppressors in GC development. The aim of this study was to discover the expression, function and mechanism of miR-761 in GC progression. First, the findings revealed that the expression level of miR-761 was significantly decreased in GC cell lines and tissues. The functional studies showed that miR-761 in GC cells inhibited tumor proliferation and metastasis. In the mechanistic study, through an online database search and luciferase assay, Ras and Rab interactor 1 (RIN1), which has been demonstrated as an oncogene in various types of cancer, including GC, was identified as a target of miR-761. Notably, miR-761 expression was demonstrated to be negatively correlated with RIN1 mRNA levels in GC tissues. Simultaneously, overexpression of RIN1 partially rescued the inhibitory effect of miR-761 mimic in the GC cells. The present study provided new insights into the role of miR-761 in the progression of GC, and implicated the potential application of miR-761 in GC cell therapy.

ATDC promotes the growth and invasion of hepatocellular carcinoma cells by modulating GSK-3β/Wnt/β-catenin signalling

Accumulating evidence has suggested that the ataxia telangiectasia group D complementing (ATDC) gene is an emerging cancer-related gene in multiple human cancer types. However, little is known about the role of ATDC in hepatocellular carcinoma (HCC). In this study, we aimed to investigate the expression level, biological function and underlying mechanism of ATDC in HCC. The expression of ATDC in HCC cells was detected by quantitative real-time polymerase chain reaction and western blot analysis. Cell growth was determined by cell counting kit-8 assay and colony formation assay. Cell invasion was assessed by Transwell invasion assay. The activation status of Wnt/β-catenin signalling was evaluated by the luciferase reporter assay. Functional experiments showed that the silencing of ATDC expression significantly suppressed the growth and invasion of HCC cells, whereas the overexpression of ATDC promoted the growth and invasion of HCC cells in vitro. Moreover, we showed that ATDC overexpression promoted the phosphorylation of glycogen synthase kinase (GSK)-3β and resulted in the activation of Wnt/β-catenin signalling. Notably, the inhibition of GSK-3β activity significantly abrogated the tumour suppressive effect of ATDC silencing, while the silencing of β-catenin partially reversed the oncogenic effect of ATDC overexpression. Taken together, these findings reveal an oncogenic role of ATDC in HCC and show that the suppression of ATDC impedes the growth and invasion of HCC cells associated with the inactivation of Wnt/β-catenin signalling. Our study suggests that ATDC may serve as a potential therapeutic target for HCC.

Triple Negative Breast Cancer Profile, from Gene to microRNA, in Relation to Ethnicity

Breast cancer is the most frequent cause of cancer-related deaths among women worldwide. It is classified into four major molecular subtypes. Triple-negative breast cancers (TNBCs), a subgroup of breast cancer, are defined by the absence of estrogen and progesterone receptors and the lack of HER-2 expression; this subgroup accounts for ~15% of all breast cancers and exhibits the most aggressive metastatic behavior. Currently, very limited targeted therapies exist for the treatment of patients with TNBCs. On the other hand, it is important to highlight that knowledge of the molecular biology of breast cancer has recently changed the decision-making process regarding the course of cancer therapies. Thus, a number of new techniques, such as gene profiling and sequencing, proteomics, and microRNA analysis have been used to explore human breast carcinogenesis and metastasis including TNBC, which consequently could lead to new therapies. Nevertheless, based on evidence thus far, genomics profiles (gene and miRNA) can differ from one geographic location to another as well as in different ethnic groups. This review provides a comprehensive and updated information on the genomics profile alterations associated with TNBC pathogenesis associated with different ethnic backgrounds.

circLARP4 induces cellular senescence through regulating miR-761/RUNX3/p53/p21 signaling in hepatocellular carcinoma

Circular RNAs (circRNAs), a novel class of non-coding RNAs, have emerged as indispensable modulators in human malignancies. Aberrant cellular senescence is a phenotype observed in various cancers. The association of circRNAs with cellular senescence in tumors is yet to determined. Here, we investigated the role of circLARP4 in cellular senescence and cell proliferation in hepatocellular carcinoma (HCC). Downregulated circLARP4 level was observed in HCC tissues and cell lines. Low expression level of circLARP4 independently predicted poor survival outcome. Gain-of-function and loss-of-function assays demonstrated that circLARP4 suppressed HCC cell proliferation, mediated cell cycle arrest and induced senescence in vitro. Levels of p53 and p21, 2 key regulatory molecules in cellular senescence, were increased in circLARP4-overexpressed HCC cells and decreased in circLARP4-silenced HCC cells. In vivo experiments further confirmed the tumor-suppressing activity of circLARP4. Further mechanistic studies showed that circLARP4 dampened HCC progression by sponging miR-761, thereby promoting the expression level of RUNX3 and activating the downstream p53/p21 signaling. Our study revealed the role of circLARP4/miR-761/RUNX3/p53/p21 signaling in HCC progression, providing a potential survival predictor and therapeutic candidate for HCC.

ATDC mediates a TP63-regulated basal cancer invasive program

Basal subtype cancers are deadly malignancies but the molecular events driving tumor lethality are not completely understood. Ataxia-Telangiectasia Group D Complementing gene (ATDC, also known as TRIM29), is highly expressed and drives tumor formation and invasion in human bladder cancers but the factor(s) regulating its expression in bladder cancer are unknown. Molecular subtyping of bladder cancer has identified an aggressive basal subtype which shares molecular features of basal/squamous tumors arising in other organs and is defined by activation of a TP63-driven gene program. Here we demonstrate that ATDC is linked with expression of TP63 and highly expressed in basal bladder cancers. We find that TP63 binds to transcriptional regulatory regions of ATDC and KRT14 directly, increasing their expression, and that ATDC and KRT14 execute a TP63-driven invasive program. In vivo, ATDC is required for TP63-induced bladder tumor invasion and metastasis. These results link TP63 and the basal gene expression program to ATDC and to aggressive tumor behavior. Defining ATDC as a molecular determinant of aggressive, basal cancers may lead to improved biomarkers and therapeutic approaches.

Identification of FOXM1 as a specific marker for triple‑negative breast cancer

The present study aimed to identify the therapeutic role of the forkhead box M1 (FOXM1)-associated pathway in triple-negative breast cancer (TNBC). Using a Cancer Landscapes-based analysis, a gene regulatory network model was constructed. The present results demonstrated that FOXM1 occupies a key position in gene networks and is a critical regulatory gene in breast cancer. Using breast carcinoma gene expression data from The Cancer Genome Atlas, it was identified that FOXM1 expression was increased in the basal-like breast cancer subtype compared with other breast cancer subtypes. RNA-sequencing analysis of MDA-MB-231 cells treated with 4 and 10 µl/ml Thiostrepton identified 662 and 5,888 significantly differentially expressed genes, respectively. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses demonstrated that FOXM1 was highly associated with multiple biological processes and was markedly associated with metabolic pathways in TNBC. The use of Search Tool for the Retrieval of Interacting Genes/Proteins provided a critical assessment and integration of protein-protein interactions, and demonstrated the multiple important functions of FOXM1 in TNBC. Real-time cell analysis, reverse transcription-quantitative polymerase chain reaction and immunofluorescence staining were used to assess the anti-tumor activity of Thiostrepton in TNBC cells in vitro. The present results identified that suppression of FOXM1 using Thiostrepton inhibited MDA-MB-231 cell proliferation and the expression of cell cycle-associated genes, including cyclin A2, cyclin B2, checkpoint kinase 1, centrosomal protein 55 and polo like kinase 1. Immunofluorescence staining analysis demonstrated that vimentin, filamentous actin and zinc finger E-box-binding homeobox 1 were all decreased following treatment with Thiostrepton. Furthermore, a BALB/C nude mouse subcutaneous xenograft model was used to verify the function of FOXM1 in vivo. The present results demonstrated that FOXM1 inhibition significantly suppressed MDA-MB-231 cell tumorigenesis in vivo. Overall, the present results suggested that FOXM1 is a key gene that serves important roles in multiple biological processes in TNBC and that it may serve as a novel therapeutic target in TNBC.

Functional Linkage of RKIP to the Epithelial to Mesenchymal Transition and Autophagy during the Development of Prostate Cancer

Raf kinase inhibitor protein (RKIP) plays a critical role in many signaling pathways as a multi-functional adapter protein. In particular, the loss of RKIP’s function in certain types of cancer cells results in epithelial to mesenchymal transition (EMT) and the promotion of cancer metastasis. In addition, RKIP inhibits autophagy by modulating LC3-lipidation and mTORC1. How the RKIP-dependent inhibition of autophagy is linked to EMT and cancer progression is still under investigation. In this study, we investigated the ways by which RKIP interacts with key gene products in EMT and autophagy during the progression of prostate cancer. We first identified the gene products of interest using the corresponding gene ontology terms. The weighted-gene co-expression network analysis (WGCNA) was applied on a gene expression dataset from three groups of prostate tissues; benign prostate hyperplasia, primary and metastatic cancer. We found two modules of highly co-expressed genes, which were preserved in other independent datasets of prostate cancer tissues. RKIP showed potentially novel interactions with one EMT and seven autophagy gene products (TGFBR1; PIK3C3, PIK3CB, TBC1D25, TBC1D5, TOLLIP, WDR45 and WIPI1). In addition, we identified several upstream transcription modulators that could regulate the expression of these gene products. Finally, we verified some RKIP novel interactions by co-localization using the confocal microscopy analysis in a prostate cancer cell line. To summarize, RKIP interacts with EMT and autophagy as part of the same functional unit in developing prostate cancer.

Metformin inhibits human breast cancer cell growth by promoting apoptosis via a ROS-independent pathway involving mitochondrial dysfunction: pivotal role of superoxide dismutase (SOD)

PURPOSE

Despite a growing body of evidence indicating a potential efficacy of the anti-diabetic metformin as anti-cancer agent, the exact mechanism underlying this efficacy has remained largely unknown. Here, we aimed at assessing putative mechanisms associated with the ability of metformin to reduce the proliferation and migration of breast cancer cells.

METHODS

A battery of in vitro assays including MTT, colony formation, NBT and scratch wound healing assays were performed to assess the viability, proliferation, anti-oxidative potential and migration of breast cancer-derived MCF-7, MDA-MB-231 and T47D cells, respectively. Reactive oxygen species (ROS) assays along with fluorescence microscopy were used to assess apoptotic parameters. Quantification of SOD, Bcl-2, Bax, MMPs, miR-21 and miR-155 expression was performed using qRT-PCR.

RESULTS

We found that metformin inhibited the growth, proliferation and clonogenic potential of the breast cancer-derived cells tested. ROS levels were found to be significantly reduced by metformin and, concomitantly, superoxide dismutase (SOD) isoforms were found to be upregulated. Mitochondrial dysfunction was observed in metformin treated cells, indicating apoptosis. In metastatic MDA-MB-231 cells, migration was found to be suppressed by metformin through deregulation of the matrix metalloproteinases MMP-2 and MMP-9. The oncogenic microRNAs miR-21 and miR-155 were found to be downregulated by metformin, which may be correlated with the suppression of cell proliferation and/or migration.

CONCLUSIONS

Our data indicate that metformin may play a pivotal role in modulating the anti-oxidant system, including the SOD machinery, in breast cancer-derived cells. Our observations were validated by in silico analyses, indicating a close interaction between SOD and metformin. We also found that metformin may inhibit breast cancer-derived cell proliferation through apoptosis induction via the mitochondrial pathway. Finally, we found that metformin may modulate the pro-apoptotic Bax, anti-apoptotic Bcl-2, MMP-2, MMP-9, miR-21 and miR-155 expression levels. These findings may be instrumental for the clinical management and/or (targeted) treatment of breast cancer.

Hsa_circ_0007534/miR-761/ZIC5 regulatory loop modulates the proliferation and migration of glioma cells

Increasing evidences demonstrate the essential roles of circular RNAs (circRNAs) in human cancers. However, the study about the functions of circRNAs in glioma remains very limited. In the present study, we found that circRNA hsa_circ_0007534 was highly expressed in glioma tissues compared to normal brain tissues. Furthermore, we found that knockdown of hsa_circ_0007534 significantly inhibited the proliferation and migration of glioma cells. In mechanism, we showed that hsa_circ_0007534 could sponge miR-761 to repress its availability in glioma cells. We found that inhibition of miR-761 could rescue the suppressed proliferation and migration of glioma cells by hsa_circ_0007534 knockdown. Moreover, we explored the downstream mechanism and found that ZIC5 was a target of miR-761. We showed that hsa_circ_0007534 promoted the expression of ZIC5 by inhibiting miR-761 in glioma cells. And restoration of ZIC5 expression significantly reversed the effects of hsa_circ_0007534 knockdown on glioma cell proliferation and migration. In summary, our results demonstrated that hsa_circ_0007534 serves as an oncogene in glioma via promoting ZIC5 expression by repressing miR-761 availability. Our results suggested that hsa_circ_0007534/miR-761/ZIC5 regulatory loop might be a promising therapeutic target for glioma treatment.

Extracellular vesicle-encapsulated microRNA-761 enhances pazopanib resistance in synovial sarcoma

The development of drug resistance in tumor cells leads to relapse and distant metastasis. Secreted microRNAs (miRNAs) enclosed in extracellular vesicles (EVs) can act as intercellular messengers. The objective of our study was to elucidate the role of secreted miRNAs to better understand the regulatory network underlying pazopanib-resistance in synovial sarcoma cells. We performed a comprehensive analysis of secreted miRNA abundance in pazopanib treated/untreated synovial sarcoma cells from four different cell lines (SYO-1, HS-SYII, 1273/99, and YaFuSS) using microarray technology, and discovered miR-761 in EVs as a potential biomarker of pazopanib-resistance in synovial sarcoma. Furthermore, we showed that miR-761 putatively targeted three proteins, thyroid hormone receptor interactor 6 (TRIP6), lamin A/C (LMNA), and NAD-dependent protein deacetylase sirtuin-3 (SIRT3). Knockdown of any of these proteins was shown in previous studies to confer increased resistance to chemotherapeutic agents. Our findings provide new insight into the potential role of miR-761, an EV-secreted miRNA from synovial sarcoma cells, making it a potential candidate for use in sarcoma therapy in the future.

Diterpenoid natural compound C4 (Crassin) exerts cytostatic effects on triple-negative breast cancer cells via a pathway involving reactive oxygen species

PURPOSE

Triple-negative breast cancers (TNBC) lack expression of three common cell surface receptors, i.e., estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). Accordingly, TNBCs are associated with fewer treatment options and a relatively poor prognosis. Having screened a National Cancer Institute natural compound library, the purpose of this study was to investigate the bioactivity of compound C4 (Crassin) in TNBC cells.

METHODS

Cell viability assays were performed in two TNBC cell lines, MDA-MB-231 and 4T1, following C4 treatment in the presence or absence of the antioxidant N-acetyl-L-cysteine (NAC). Phosphorylation of Akt and ERK was assessed by Western blotting. Apoptosis, necrosis, autophagy, necroptosis, ferroptosis and cytostasis assays were performed to explain viability deficits resulting from C4 exposure.

RESULTS

We found that the viability of the TNBC cells tested decreased in a concentration- and time-dependent fashion following C4 treatment. This decrease coincided with an unexpected increase in the expression of the cell survival effectors pAkt and pERK. In addition, we found that both the decreased cell viability and the increased pAkt/pERK levels could be rescued by the antioxidant NAC, suggesting a central role for reactive oxygen species (ROS) in the mechanism of action of C4. Necrosis, apoptosis, necroptosis and ferroptosis could be ruled out as cell death mechanisms. Instead, we found that C4 induced cytostasis downstream of ROS activation. Finally, we observed a synergistic effect between C4 and the chemotherapeutic drug doxorubicin in TNBC cells.

CONCLUSIONS

From our in vitro data we conclude that C4 exerts cytostatic effects on triple-negative breast cancer cells via a pathway involving reactive oxygen species. Its potential value in combination with cytotoxic therapies merits deeper investigation in pre-clinical models.

MicroRNA-761 promotes the sensitivity of colorectal cancer cells to 5-Fluorouracil through targeting FOXM1

Resistance to chemotherapy is a big challenge for treatment of patients with colorectal cancer; however; the mechanism underlying chemoresistance in colorectal cancer cell has not been elucidated. MicroRNAs (miRNAs) are new players in the development of drug chemoresistance. In our study, we indicated that overexpression of miR-761 promoted the sensitivity of colorectal cancer cells to 5-Fluorouracil (5-FU). miR-761 expression was downregulated in colorectal cancer cell lines and tissues. miR-761 expression was lower in patients with low grade than in patients with high grade. In additon, we showed that elevated expression of miR-761 suppressed colorectal cancer cell proliferation, cell cycle, colony formation and cell invasion. We identified that FOXM1 was a direct target gene of miR-761 in colorectal cancer cell. FOXM1 expression was upregulated in colorectal cancer tissues compare to the adjacent non-tumor tissues. MiR-761 expression was negatively associated with the expression of FOXM1 in colorectal cancer tissues. Elevated expression of FOXM1 suppressed the sensitivity of miR-761-overexpressing HT29 cells to 5-FU. We also indicated that FOXM1 overexpression promoted cell proliferation, cycle and invasion of miR-761-overexpressing HT29 cells. These data suggested that miR-761 played a tumor suppressor miRNA in colorectal cancer progression and reduced miR-761 expression might be a major mechanism for 5-FU resistance in colorectal cancer cell.