FBXW7 in breast cancer: mechanism of action and therapeutic potential

Breast cancer is one of the frequent tumors that seriously endanger the physical and mental well-being in women. F-box and WD repeat domain-containing 7 (FBXW7) is a neoplastic repressor. Serving as a substrate recognition element for ubiquitin ligase, FBXW7 participates in the ubiquitin-proteasome system and is typically in charge of the ubiquitination and destruction of crucial oncogenic proteins, further performing a paramount role in cell differentiation, apoptosis and metabolic processes. Low levels of FBXW7 cause abnormal stability of pertinent substrates, mutations and/or deletions in the FBXW7 gene have been reported to correlate with breast cancer malignant progression and chemoresistance. Given the lack of an effective solution to breast cancer's clinical drug resistance dilemma, elucidating FBXW7's mechanism of action could provide a theoretical basis for targeted drug exploration. Therefore, in this review, we focused on FBXW7's role in a range of breast cancer malignant behaviors and summarized the pertinent cellular targets, signaling pathways, as well as the mechanisms regulating FBXW7 expression. We also proposed novel perspectives for the exploitation of alternative therapies and specific tumor markers for breast cancer by therapeutic strategies aiming at FBXW7.

Expression patterns of AEG-1 in the normal brain

Astrocyte elevated gene-1 (AEG-1) is a well-known oncogene implicated in various types of human cancers, including brain tumors. Recently, AEG-1 has also been reported to play pivotal roles in glioma-associated neurodegeneration and neurodegenerative diseases like Parkinson's disease and amyotrophic lateral sclerosis. However, the normal physiological functions and expression patterns of AEG-1 in the brain are not well understood. In this study, we investigated the expression patterns of AEG-1 in the normal mouse brain and found that AEG-1 is widely expressed in neurons and neuronal precursor cells, but little in glial cells. We observed differential expression levels of AEG-1 in various brain regions, and its expression was mainly localized in the cell body of neurons rather than the nucleus. Additionally, AEG-1 was expressed in the cytoplasm of Purkinje cells in both the mouse and human cerebellum, suggesting its potential role in this brain region. These findings suggest that AEG-1 may have important functions in normal brain physiology and warrant further investigation. Our results may also shed light on the differential expression patterns of AEG-1 in normal and pathological brains, providing insights into its roles in various neurological disorders.

FBXW7 and the Hallmarks of Cancer: Underlying Mechanisms and Prospective Strategies

FBXW7, a member of the F-box protein family within the ubiquitin–proteasome system, performs an indispensable role in orchestrating cellular processes through ubiquitination and degradation of its substrates, such as c-MYC, mTOR, MCL-1, Notch, and cyclin E. Mainly functioning as a tumor suppressor, inactivation of FBXW7 induces the aberrations of its downstream pathway, resulting in the occurrence of diseases especially tumorigenesis. Here, we decipher the relationship between FBXW7 and the hallmarks of cancer and discuss the underlying mechanisms. Considering the interplay of cancer hallmarks, we propose several prospective strategies for circumventing the deficits of therapeutic resistance and complete cure of cancer patients.

Mcl-1 inhibition overcomes BET inhibitor resistance induced by low FBW7 expression in breast cancer

While the promise of bromodomains and extraterminal (BET) protein inhibitors (BETis) is emerging in breast cancer (BC) therapy, resistance in these cells to BETis conspicuously curbs their therapeutic potential. FBW7 is an important tumour suppressor. However, the role of FBW7 in BC is not clear. In the current study, our data indicated that the low expression of FBW7 contributes to the drug resistance of BC cells upon JQ1 treatment. shRNA‐mediated FBW7 silencing in FBW7 WT BC cells suppressed JQ1‐induced apoptosis. Mechanistically, it was revealed that this diminished FBW7 level leads to Mcl‐1 stabilization, while Mcl‐1 upregulation abrogates the killing effect of JQ1. Mcl‐1 knockdown or inhibition resensitized the BC cells to JQ1‐induced apoptosis. Moreover, FBW7 knockdown in MCF7 xenografted tumours demonstrated resistance to JQ1 treatment. The combination of JQ1 with a Mcl‐1 inhibitor (S63845) resensitized the FBW7 knockdown tumours to JQ1 treatment in vivo. Our study paves the way for a novel therapeutic potential of BETis with Mcl‐1 inhibitors for BC patients with a low FBW7 expression.

FBP1 enhances the radiosensitivity by suppressing glycolysis via the FBXW7/mTOR axis in nasopharyngeal carcinoma cells

AIMS

The high glycolysis state of tumor cells is closely related to radioresistance. Fructose-1,6-bisphosphatase (FBP1) can regulate aerobic glycolysis and exerts tumor suppressor effects in many cancers, but its role in nasopharyngeal carcinoma (NPC) remains to be investigated.

MATERIALS AND METHODS

RT-qPCR was used to measure FBP1 mRNA level. Glucose consumption, lactic acid production and ATP level was determined to evaluate glycolysis. The sensitivity of NPC cells to radiation was analyzed by MTT assay. Apoptosis was performed using flow cytometry. Gain- and loss-of function assays were carried out to explore the specific role of FBP1 and FBXW7 (F-box and WD repeat domain-containing 7) in NPC cell functions. The interactions between FBXW7 and FBP1 or mTOR were validated with co-immunoprecipitation assay. The in vivo experiments with xenografts were used to evaluate the role of FBP1 in tumor growth.

KEY FINDINGS

FBP1 expression was lower in NPC tissues and cells than in normal controls and nasopharyngeal epithelial cells. Human recombinant FBP1 (rh-FBP1) treatment suppressed glycolysis in NPC cells. Besides, silencing FBP1 weakened the radiosensitivity and alleviated radiation-induced apoptosis and DNA damage by promoting glycolysis. Mechanism exploration found that FBP1 promoted FBXW7 protein level through suppressing the autoubiquitination of FBXW7. Then, FBXW7 restrained mTOR level by facilitating mTOR ubiquitination, thereby suppressing glycolysis and promoting radiation-induced apoptosis and DNA damage. Furthermore, overexpressing FBP1 in vivo hindered tumor growth and enhanced the antitumor activity of radiation.

SIGNIFICANCE

FBP1 promoted the radiosensitivity in NPC cells by inhibiting glycolysis through the FBXW7/mTOR axis.

Repression of FBXW7 by HES5 contributes to inactivation of the TGF-β signaling pathway and alleviation of endometriosis

Endometriosis (EMS) is a gynecologic disorder associated with infertility and characterized by the endometrial-type mucosa outside the uterine cavity. Currently available treatment modalities are limited to undesirable effects. Thus, in the present study, we sought to study the pathogenesis mechanism of EMS. For this purpose, the ectopic and eutopic endometrial tissues were resected from 86 patients with EMS and 54 infertile patients without EMS, respectively. The regulatory mechanism among HES family bHLH transcription factor 5 (HES5), transforming growth factor-beta (TGF-β)-induced factor 1 (TGIF1), F-box, and WD repeat domain containing 7 (FBXW7) was studied by performing co-immunoprecipitation, dual-luciferase reporter gene assay, and chromatin immunoprecipitation, respectively. A mouse model of EMS was established to verify the aforementioned regulatory mechanism in vivo. Upregulation of HES5 and TGIF1, as well as downregulation of FBXW7, was observed in EMS endometrial tissues and human endometrial stromal cells (hESCs), respectively. The overexpression of HES5 was found to suppress the FBXW7 transcription and TGIF1 degradation, resulting in the inactivation of the TGF-β signaling pathway, as well as inhibition of hESC proliferation and invasion, thereby enhancing apoptosis. Results from a mouse model of EMS showed that the presence of HES5 contributed to the alleviation of EMS. Collectively, we attempted to provide a mechanistic insight into the unrecognized roles of the HES5/FBXW7 in EMS progression.

MicroRNA-25 Exerts an Oncogenic Function by Regulating the Ubiquitin Ligase Fbxw7 in Hepatocellular Carcinoma

BACKGROUND

MicroRNA (miRNA) expression abnormalities are implicated in tumor progression. Previous reports have indicated that microRNA-25 (miR-25) acts as a tumor suppressor or oncogene in diverse cancers. However, its molecular mechanisms in hepatocellular carcinoma (HCC) are still unclear. F-box and WD repeat domain 7 (Fbxw7) is a critical tumor suppressor and is one of the most important deregulated proteins of the ubiquitin-proteasome system in cancer. Our objective was to elucidate the role of miR-25 and Fbxw7 in HCC and to clarify the mechanism by which Fbxw7 is regulated.

METHODS

Fbxw7 expression was estimated in 210 fixed paraffin-embedded HCC samples by immunohistochemistry, and miR-25 expression was evaluated in 142 frozen HCC tissue samples by quantitative real-time PCR. Oncogenic functions of miR-25 and its role in the regulation of Fbxw7 expression were assayed in vitro.

RESULTS

miR-25 was overexpressed in HCC tissue compared with adjacent normal tissue and significantly correlated with a poorer prognosis. Moreover, it was inversely correlated with Fbxw7 expression in HCC tissues. Furthermore, miR-25 inhibition significantly reduced the proliferation, migration, and invasion of HCC cells in vitro.

CONCLUSION

miR-25 may promote tumor progression in HCC patients by repression of Fbxw7 and could serve as a promising molecular target for HCC treatment.

Lifetime Impact of Cow's Milk on Overactivation of mTORC1: From Fetal to Childhood Overgrowth, Acne, Diabetes, Cancers, and Neurodegeneration

The consumption of cow's milk is a part of the basic nutritional habits of Western industrialized countries. Recent epidemiological studies associate the intake of cow's milk with an increased risk of diseases, which are associated with overactivated mechanistic target of rapamycin complex 1 (mTORC1) signaling. This review presents current epidemiological and translational evidence linking milk consumption to the regulation of mTORC1, the master-switch for eukaryotic cell growth. Epidemiological studies confirm a correlation between cow's milk consumption and birthweight, body mass index, onset of menarche, linear growth during childhood, acne vulgaris, type 2 diabetes mellitus, prostate cancer, breast cancer, hepatocellular carcinoma, diffuse large B-cell lymphoma, neurodegenerative diseases, and all-cause mortality. Thus, long-term persistent consumption of cow's milk increases the risk of mTORC1-driven diseases of civilization. Milk is a highly conserved, lactation genome-controlled signaling system that functions as a maternal-neonatal relay for optimized species-specific activation of mTORC1, the nexus for regulation of eukaryotic cell growth, and control of autophagy. A deeper understanding of milk´s impact on mTORC1 signaling is of critical importance for the prevention of common diseases of civilization.

MicroRNA-497-5p Functions as a Modulator of Apoptosis by Regulating Metadherin in Ovarian Cancer

Ovarian cancer (OC) has a high mortality rate among women worldwide. However, even with the advances in detection and therapeutics, the number of cases is increasing worldwide. Increasingly, microRNAs (miRNAs), including miR-497-5p, have been implicated in the progression of many cancers, but the role of miR-497-5p in OC remains unknown. The purpose of this study was to investigate the underlying molecular mechanism of miR-497-5p in OC. Herein, we find that miR-497-5p is down-regulated in OC tissues, and overexpression of miR-497-5p enhances apoptosis in OC cells. The increased apoptosis was correlated with enhanced expression of apoptosis-related proteins. MiR-497-5p directly bound the 3'-untranslated region of metadherin (MTDH), leading to the reduction of MTDH in mRNA and protein levels. Moreover, MTDH knockout promoted the apoptosis of OC cells. Taken together, we conclude that miR-497-5p contributes to cell apoptosis in OC by regulating MTDH.

KDM5c Promotes Colon Cancer Cell Proliferation Through the FBXW7-c-Jun Regulatory Axis

KDM5c is a histone demethylase that specifically demethylates trimethylated and dimethylated H3 Lys-4 to play a central role in transcriptional repression. C-Jun is a proto-oncogene and promotes cell proliferation when ectopically accumulated, but can be ubiquitinated by SCF (FBXW7), leading to its degradation. FBXW7 is an E3 ubiquitin ligase of c-Jun, and exhibits carcinostasis in colon cancer. Here, we report that overexpression of KDM5c in human colon cancer cells results in attenuated FBXW7 transcription and accumulated c-Jun protein, leading to increased proliferation of colon cancer cells. We show that overexpression of KDM5c can result in increased c-Jun protein levels and decreased ubiquitin levels, with no significant change in mRNA levels of c-Jun. KDM5c overexpression blocks the ubiquitin-proteasome proteolytic pathway of c-Jun by down-regulating the expression of FBXW7. KDM5c down-regulation of FBXW7 occurs by demethylation of H3K4me3 at TSS and downstream of the FBXW7 gene. And interaction of KDM5c with H3K4me3 downstream of FBXW7 gene may be followed by recruitment of DNMT3b to methylate the spatially close CpG island located near the FBXW7 TSS. This methylation represses FBXW7 gene expression, which can reduce c-Jun degradation via the ubiquitin-proteasome pathway. TCGA database analysis revealed high expression of KDM5c in colon cancer tissues. KDM5c expression in colon cancer was correlated with poor overall survival of patients in the first 7 years. Data from TCGA showed that high expression of KDM5c was correlated with high DNA methylation of the FBXW7 gene, but was not positively correlated with methylation of the Jun gene. These results suggest that KDM5c regulation of colon cell proliferation is mainly mediated by the KDM5c-FBXW7-c-Jun axis.

MiR-128 suppresses metastatic capacity by targeting metadherin in breast cancer cells

Background

Breast cancer, the most common cancer in women worldwide, causes the vast majority of cancer-related deaths. Undoubtedly, tumor metastasis and recurrence are responsible for more than 90 percent of these deaths. MicroRNAs are endogenous noncoding RNAs that have been integrated into almost all the physiological and pathological processes, including metastasis. In the present study, the role of miR-128 in breast cancer was investigated.

Results

Compared to the corresponding adjacent normal tissue, the expression of miR-128 was significantly suppressed in human breast cancer specimens. More importantly, its expression level was reversely correlated to histological grade of the cancer. Ectopic expression of miR-128 in the aggressive breast cancer cell line MDA-MB-231 could inhibit cell motility and invasive capacity remarkably. Afterwards, Metadherin (MTDH), also known as AEG-1 (Astrocyte Elevated Gene 1) and Lyric that implicated in various aspects of cancer progression and metastasis, was further identified as a direct target gene of miR-128 and its expression level was up-regulated in clinical samples as expected. Moreover, knockdown of MTDH in MDA-MB-231 cells obviously impaired the migration and invasion capabilities, whereas re-expression of MTDH abrogated the suppressive effect caused by miR-128.

Conclusions

Overall, these findings demonstrate that miR-128 could serve as a novel biomarker for breast cancer metastasis and a potent target for treatment in the future.

Downregulation of miR-182-5p inhibits the proliferation and invasion of triple-negative breast cancer cells through regulating TLR4/NF-κB pathway activity by targeting FBXW7

Background

To investigate the role of miR-182-5p in the proliferation and invasion of triple-negative breast cancer (TNBC) cells, as well as the underlying mechanism.

Methods

qRT-PCR was used to detect the level of miR-182-5p in tissues and cells. CCK-8 assay, flow cytometry, and Transwell assay were performed to detect cell proliferation, apoptosis rate, and invasion, respectively. Pearson correlation analysis was used to determine the correlation between miR-182-5p and its predicted target gene FBXW7, and the target of miR-182-5p was identified by dual-luciferase reporter gene assay. ELISA assay was used to examine the levels of cytokines in the culture supernatant of tumor cells. Western blot analysis was used to detect the expressions of FBXW7, TLR4, and NF-κB) pathways in tumor cells.

Results

In MDA-MB-231 and BT-549 cells, downregulation of miR-182-5p significantly inhibited cell proliferation and invasion and promoted tumor cell apoptosis. Pearson correlation analysis showed that miR-182-5p had a negative correlation with FBXW7. Dual-luciferase reporter gene assay showed that miR-182-5p could directly target FBXW7. Further studies showed that FBXW7 overexpression significantly inhibited cell proliferation and invasion and increased the apoptosis rate. Downregulation of miR-182-5p significantly reduced the levels of TNF-α, IL-1 β, IL-6, and IL-18 in the culture supernatant, and decreased the activity of TLR4/NF-κB pathway in tumor cells, while downregulation of FBXW7 significantly inhibited the effect of miR-182-5p on tumor cells.

Conclusions

Downregulation of miR-182-5p inhibits TLR4/NF-κB pathway activity by increasing FBXW7 expression, thereby suppressing the proliferation and invasion of TNBC cells.

Adenovirus-mediated anti-AEG-1 ScFv expression driven by stathmin promoter inhibits tumor growth in cervical cancer

Background

Astrocyte-elevated gene-1 (AEG-1) is over-expressed in many cancer cells and has multiple key functions in tumor initiation and progression. Currently, targeted-AEG-1 siRNA is one of the most common techniques to down-regulate AEG-1 expression, but the lack of tumor specificity and available delivery system make it difficult to enter clinical trials.

Methods

In this study, we creatively developed an adenovirus-mediated anti-AEG-1 single-chain antibody fragment (ScFv) expression system driven by a tumor specific promoter, and experimented with it in human cervical carcinoma cells to investigate the effect on tumor’s proliferation and apoptosis.

Results

The results showed that of HeLa and SiHa cells treated with this recombinant anti-AEG-1 ScFv adenovirus not only inhibited cell growth, but induced apoptosis both in vitro and in vivo. Furthermore, we also observed that the expressions of several apoptosis-related genes like Akt 1 and c-Myc decreased, while NF-κB (p65) and cleaved caspase 3 increased on protein levels in vivo.

Conclusion

We concluded that stathmin promoter-driving anti-AEG-1 ScFv adenoviral system may be a breakthrough for its dual-specificity, and serve as an adjuvant tumor specific therapy method in the treatment for human cervical cancers.

Cell proliferation is induced in renal cell carcinoma through miR-92a-3p upregulation by targeting FBXW7

Renal cell carcinoma (RCC) is the most common type of kidney cancer whose incidence has gradually increased worldwide. MicroRNAs (miRNAs) represent a type of short endogenous non-coding RNA containing approximately 22 nucleotides, which are capable of regulating mRNAs at the post-transcriptional level in human cells. miRNAs have been demonstrated to mediate gene expression by influencing important regulatory genes. Accumulating evidence indicates that certain miRNAs are involved in RCC development. The present study investigated the underlying mechanism and functional role of miR-92a-3p in RCC cells using reverse transcription-quantitative polymerase chain reaction, western blotting, 3′ UTR luciferase assay, cell proliferation assay and soft agar assay. The results demonstrated that miR-92a-3p expression level is significantly upregulated in RCC tissues and cell lines; however, F-box and WD repeat domain containing 7 (FBXW7) expression level was significantly downregulated in RCC tissues and cell lines. Subsequently, whether FBXW7 could be considered as a direct target of miR-92a-3p in RCC cells was investigated. The results demonstrated that miR-92a-3p overexpression significantly promoted RCC cell proliferation and colony formation. Conversely, miR-92a-3p downregulation significantly inhibited RCC cell proliferation and colony formation. In addition, FBXW7 knockdown significantly enhanced RCC cell proliferation and colony formation. Conversely, FBXW7 overexpression significantly inhibited RCC cell proliferation and colony formation. Collectively, these results demonstrated that miR-92a-3p/FBXW7 pathway may represent a novel strategy and therapeutic target for RCC.

Recent insight into the role of FBXW7 as a tumor suppressor

FBXW7 (also known as Fbw7, Sel10, hCDC4, or hAgo) is a tumor suppressor and the most frequently mutated member of the F-box protein family in human cancers. FBXW7 functions as the substrate recognition component of an SCF-type E3 ubiquitin ligase. It specifically controls the proteasome-mediated degradation of many oncoproteins such as c-MYC, NOTCH, KLF5, cyclin E, c-JUN, and MCL1. In this review, we summarize the molecular and biological features of FBXW7 and its substrates as well as the impact of mutations of FBXW7 on cancer development. We also address the clinical potential of anticancer therapy targeting FBXW7.

Hsa_circ_RNA_0011780 Represses the Proliferation and Metastasis of Non-Small Cell Lung Cancer by Decreasing FBXW7 via Targeting miR-544a

Purpose

Circular RNA (circRNA) is involved in the development of various cancers. However, whether circRNA can inhibit the tumorigenesis of non-small cell lung cancer (NSCLC) is still unclear. We aimed to explore the epigenetic function of tumor-suppressive circRNA (hsa_circ_RNA_0011780) and its downstream regulatory factors in NSCLC.

Patients and Methods

Quantitative polymerase chain reaction (qPCR) was used to evaluate hsa_circ_11780 expression in NSCLC tissues and cell lines. The impact of high hsa_circ_11780 expression on overall survival in patients with NSCLC was tested using the Log rank test. The association between decreased hsa_circ_11780 expression and clinicopathological features in patients with NSCLC was analyzed using the Chi-squared test. In vitro cell proliferation and apoptosis were assayed using the cell counting kit-8 (CCK-8) and flow cytometry, respectively. Mice xenograft models were used to determine the tumor promoting effects of hsa_circ_11780 on NSCLC in vivo. The underlying regulatory mechanism was predicted by bioinformatics and verified by a dual-luciferase reporter assay, RNA transfection, qPCR, and Western blotting. The correlation between miR-544a and hsa_circ_11780 expression was verified using Spearman correlation coefficient.

Results

The expression of hsa_circ_11780 in NSCLC tissues and cell lines strongly declined. Low hsa_circ_11780 expression is more likely to present in patients with a large tumor size (>3cm), distant metastasis, and poor overall survival. hsa_circ_11780 overexpression strongly inhibited proliferation, migration, and invasion of NSCLC cells (H226 and A549) in vitro and inhibited tumor growth in vivo. Furthermore, hsa_circ_11780 repressed miR-544a function by competitively binding to the complementary sites of miR-544a. miR-544a released by the declining expression of hsa_circ_11780 reduced the protein concentration of F-Box and WD repeat domain containing 7 (FBXW7) in NSCLC cells.

Conclusion

FBXW7 expression mediated by the hsa_circ_11780/miR-544a axis is markedly associated with the proliferation, migration, and invasion of NSCLC, resulting in decreased survival. These findings suggest that this regulatory axis may serve as a novel therapeutic target in NSCLC.

Ivermectin inhibits canine mammary tumor growth by regulating cell cycle progression and WNT signaling

Background

Mammary gland tumor is the most common spontaneous tumor in intact female dogs, and its poor prognosis remains a clinical challenge. Ivermectin, a well-known anti-parasitic agent, has been implicated as a potential anticancer agent in various types of human cancer. However, there are no reports evaluating the antitumor effects of ivermectin in canine mammary tumor. Here, we investigated whether ivermectin was able to inhibit canine mammary tumor development and explored the related mechanisms.

Results

Ivermectin inhibited the growth of canine mammary tumor cell lines in a dose- and time-dependent manner. The antitumor effects induced by ivermectin were associated with cell cycle arrest at G1 phase via down-regulation of CDK4 and cyclin D1 expression, with no significant induction of apoptosis. Furthermore, significantly reduced β-catenin nuclear translocation was observed after treatment with ivermectin, resulting in the inactivation of WNT signaling. Consistent with the results in vitro, a significant suppression of tumor growth by ivermectin was observed in canine mammary tumor xenografts.

Conclusion

Ivermectin, as a promising anti-cancer agent, inhibits the growth of canine mammary tumor by regulating cell cycle progression and WNT signaling.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-2026-2) contains supplementary material, which is available to authorized users.

MiR322 mediates cardioprotection against ischemia/reperfusion injury via FBXW7/notch pathway

Myocardial ischemia/reperfusion (MI/R) causes loss of cardiomyocytes via oxidative stress-induced cardiomyocyte apoptosis. miR322, orthologous to human miR-424, was identified as an ischemia-induced angiogenic miRNA, but its cellular source and function in the setting of acute MI/R remains largely unknown. Using LacZ-tagged miR322 cluster reporter mice, we observed that vascular endothelial cells are the major cellular source of the miR322 cluster in adult hearts. Moreover, miR322 levels were significantly reduced in the heart at 24 h after MI/R injury. Intramyocardial injection of mimic-miR322 significantly diminished cardiac apoptosis (as determined by expression levels of active caspase 3 by Western blot analysis and immunostaining for TUNEL) and reduced infarct size by about 40%, in association with reduced FBXW7 and increased active Notch 1 levels in the ischemic hearts. FBXW7, which is an ubiquitin ligase that is crucial for activated Notch1 turnover, was identified as a direct target of miR322 via FBXW7 3'UTR reporter assay. Co-injection of FBXW7 plasmid with mimic-miR322 in ischemic hearts abolished the effect of mimic-miR322 to reduce apoptosis and infarct size in MI/R hearts. These data identify FBXW7 as a direct target of miR322 and suggest that miR322 could have potential therapeutic application for cardioprotection against ischemia/reperfusion-induced injury.

The targeting of MTDH by miR‑145‑5p or miR‑145‑3p is associated with prognosis and regulates the growth and metastasis of prostate cancer cells

Studies have rarely been conducted on the role of miRNAs in prostate cancer (PCa) cell progression by directly targeting MTDH, at least to the best of our knowledge. Thus, the present study aimed to identify miRNAs closely related with metadherin (MTDH) and to determine their roles in PCa. For this purpose, the expression levels of MTDH in PCa tissues and cell lines were examined by RT‑qPCR, immunohistochemistry and western blot analysis. By cell transfection, MTDH was either overexpressed in the normal prostate epithelial cell lines or silenced in tumor cell lines to determine cell viability, invasion and migration. Bioinformatics analysis, RT‑qPCR, western blot analysis, dual‑luciferase reporter assay and MTT assay were performed to identify direct the target of MTDH and to examine tumor cell viability. Rescue experiments using the PC‑3 and LNCaP cells were carried out by MTT assay, scratch wound assay, Transwell assay, RT‑qPCR and western blot analysis. Experiments were also conducted using 46 PCa human cancer and adjacent tissues, as wells as on 501 cases of PCa from the TCGA database. It was confirmed that the overexpression of MTDH was associated with a poor prognosis of patients. The overexpression of MTDH was found to promote the viability, invasion and migration of PCa cells. miR‑145‑5p and miR‑145‑3p identified from 16 miRNAs were found to be closely related to PCa and to be the targets of MTDH. Both these miRNAs were found to significantly suppress the growth and metastasis of PCa cells by negatively regulating the expression of MTDH. On the whole, the findings of this study demonstrate that MTDH functions as an oncogene in PCa and the inhibition of MTDH by miR‑145‑5p or miR‑145‑3p suppressed the growth and metastasis of PCa cells. The miR‑145‑5p/MTDH and miR‑145‑3p/MTDH pathways may thus become novel treatment targets for PCa.

FBXW7 in Cancer: What Has Been Unraveled Thus Far?

: The FBXW7 (F-box with 7 tandem WD40) protein encoded by the gene FBXW7 is one of the crucial components of ubiquitin ligase called Skp1-Cullin1-F-box (SCF) complex that aids in the degradation of many oncoproteins via the ubiquitin-proteasome system (UPS) thus regulating cellular growth. FBXW7 is considered as a potent tumor suppressor as most of its target substrates can function as potential growth promoters, including c-Myc, Notch, cyclin E, c-JUN, and KLF5. Its regulators include p53, C/EBP-δ, Numb, microRNAs, Pin 1, Hes-5, BMI1, Ebp2. Mounting evidence has indicated the involvement of aberrant expression of FBXW7 for tumorigenesis. Moreover, numerous studies have also shown its role in cancer cell chemosensitization, thereby demonstrating the importance of FBXW7 in the development of curative cancer therapy. This comprehensive review emphasizes on the targets, functions, regulators and expression of FBXW7 in different cancers and its involvement in sensitizing cancer cells to chemotherapeutic drugs.

Lobaplatin inhibits breast cancer progression, cell proliferation while it induces cell apoptosis by downregulating MTDH expression

Objective

Lobaplatin shows antitumor activity against a wide range of tumors, including metastatic breast cancer (BCa). The overexpression of metadherin (MTDH) is associated with poor prognosis of BCa patients. This study was designed to investigate the effect of lobaplatin on MCF-7 cell proliferation and its association with MTDH expression.

Patients and methods

Clinical treatment for BCa using lobaplatin, in combination with other general chemotherapy drugs, was administered to 32 BCa patients. The safety, effectiveness, and prognosis in lobaplatin-treated BCa patients were compared with those in controls (n=32). In vitro experiments were performed in MCF-7 cells to investigate the effect of lobaplatin on cell proliferation, apoptosis, and MTDH expression.

Results

We found the intraoperative local chemotherapy using lobaplatin was safe and effective for BCa treatment, in comparison with the patients administered general chemotherapy drugs. Treatment of MCF-7 cell cultures with lobaplatin significantly reduced cell proliferation and increased cell apoptotic percentage. The expression of MTDH and Bcl-2 was inhibited by lobaplatin and that of Bax was increased by lobaplatin. Moreover, we observed the inhibition of MTDH by shRNA reduced cell proliferation and enhanced cell apoptosis.

Conclusion

Lobaplatin was a safe and effective adjuvant chemotherapy for BCa. The effect of lobaplatin on inhibiting MCF-7 cell proliferation and inducing cell apoptosis might be, as least in part, mediated by suppressing the expression of oncogene MTDH.

Metadherin is an apoptotic modulator in prostate cancer through miR-342-3p regulation

Prostate cancer is the second most common cancer in men worldwide. This study focused to clarify the roles of Metadherin (MTDH) and miR-342-3p in prostate cancer. We identified that MTDH was up-regulated and miR-342-3p was down-regulated in the prostate tissues, and there is an inverse correlation between MTDH and miR-342-3p. Functional studies revealed that miR-342-3p directly targets MTDH via binding to the 3' untranslated regions (UTRs) in the prostate cancer cells. Moreover, we also found MTDH overexpression in DU145 and PC3 cells inhibited apoptosis. Subsequently, miR-342-3p has been revealed to reverse the MTDH effect on the cellular apoptosis in the further studies. Our results indicate that MTDH repress apoptosis of prostate cancer in vitro and provides a new strategy for human prostate cancer therapy in the future.