The conflicting role of E2F1 in prostate cancer: A matter of cell context or interpretational flexibility?

Histone demethylase KDM5D represses the proliferation, migration and invasion of hepatocellular carcinoma through the E2F1/TNNC1 axis

OBJECTIVE

This study focused on investigating the mechanism in which the KDM5D/E2F1/TNNC1 axis affected hepatocellular carcinoma (HCC) development.

METHODS

At first, we determined HCC cell proliferation, migration, invasion, and apoptosis, as well as SOD activity, MDA content, and ROS level. ChIP assay was subsequently conducted to examine H3K4me3 modification in the E2F1 promoter region and the binding of E2F1 to the TNNC1 promoter region after KDM5D overexpression. Meanwhile, we performed western blot for testing KDM5D, H3K4me3, and E2F1 expression after KDM5D overexpression in Huh-7 cells. The binding of transcription factor E2F1 to the TNNC1 promoter region was assessed by dual luciferase reporter gene assay. We further observed the tumor growth ability in nude mice transplanted tumor models.

RESULTS

Overexpressed KDM5D suppressed HCC proliferation, migration, and invasion, promoted the apoptosis, suppressed SOD activity, elevated MDA content and ROS level, and promoted ferroptosis. KDM5D suppressed H3K4me3 modification in the E2F1 promoter region and suppressed E2F1 expression in HCC cells. Reduced KDM5D, H3K4me3, and E2F1 expression was found after KDM5D overexpression in Huh-7 cells. Overexpressing E2F1 reversed the inhibitory effects of KDM5D on HCC cell proliferative, migratory, and invasive behaviors. KDM5D repressed TNNC1 transcription by inhibiting E2F1 binding to the TNNC1 promoter. In vivo KDM5D overexpression inhibited HCC development via the E2F1/TNNC1 axis.

CONCLUSION

KDM5D inhibits E2F1 expression by suppressing H3K4me3 modification in the E2F1 promoter region, which in turn suppresses the binding of E2F1 to the TNNC1 promoter region, thus leading to the inhibition of HCC development.

8-Br-cGMP activates HSPB6 and increases the antineoplastic activity of quinidine in prostate cancer

Heat shock protein family B [small] member 6 (HSPB6), widely found in various muscles, has been recently identified as a tumor suppressor gene. However, its role in prostate cancer remains unexplored. Herein, we investigated the expression of HSPB6 in prostate cancer and its association with prognosis. Our findings revealed that HSPB6 downregulation in prostate cancer correlated with a poor prognosis. Moreover, we discovered that HSPB6 can be phosphorylated and activated by 8-Br-cGMP, leading to apoptosis in prostate cancer cells by activating Cofilin. Additionally, we demonstrated that knocking down E2F1 by quinidine administration enhances the transcriptional level of HSPB6. Furthermore, we evaluated the combination of quinidine and 8-Br-cGMP as a potential therapeutic strategy for prostate cancer. Our results revealed that the combined treatment was more effective than either treatment alone in inhibiting the growth of prostate cancer through the HSPB6 pathway, both in vitro and in vivo. Overall, our study provides compelling evidence that HSPB6 suppresses malignant behavior in prostate cancer by inducing apoptosis. The combination of quinidine and 8-Br-cGMP emerges as a promising approach for the treatment of prostate cancer.

Targeting the E2F1/Rb/HDAC1 axis with the small molecule HR488B effectively inhibits colorectal cancer growth

Colorectal cancer (CRC), the third most common cancer worldwide, remains highly lethal as the disease only becomes symptomatic at an advanced stage. Growing evidence suggests that histone deacetylases (HDACs), a group of epigenetic enzymes overexpressed in precancerous lesions of CRC, may represent promising molecular targets for CRC treatment. Histone deacetylase inhibitors (HDACis) have gradually become powerful anti-cancer agents targeting epigenetic modulation and have been widely used in the clinical treatment of hematologic malignancies, while only few studies on the benefit of HDACis in the treatment of CRC. In the present study, we designed a series of small-molecule Thiazole-based HDACis, among which HR488B bound to HDAC1 with a high affinity and exerted effective anti-CRC activity both in vitro and in vivo. Moreover, we revealed that HR488B specifically suppressed the growth of CRC cells by inducing cell cycle G0/G1 arrest and apoptosis via causing mitochondrial dysfunction, reactive oxygen species (ROS) generation, and DNA damage accumulation. Importantly, we noticed that HR488B significantly decreased the expression of the E2F transcription factor 1 (E2F1), which was crucial for the inhibitory effect of HR488B on CRC. Mechanistically, HR488B obviously decreased the phosphorylation level of the retinoblastoma protein (Rb), and subsequently prevented the release of E2F1 from the E2F1/Rb/HDAC1 complex, which ultimately suppressed the growth of CRC cells. Overall, our study suggests that HR488B, a novel and efficient HDAC1 inhibitor, may be a potential candidate for CRC therapy in the future. Furthermore, targeting the E2F1/Rb/HDAC1 axis with HR488B provides a promising therapeutic avenue for CRC.

E2F1 rs3213150 polymorphism influences cytarabine sensitivity and prognosis in patients with acute myeloid leukemia

Cytarabine (Ara-C) plays an irreplaceable role in the treatment of acute myeloid leukemia (AML). However, there are significant differences in efficacy among patients. Our previous studies found that E2F1 rs3213150 polymorphism was associated with remission rate of Ara-C chemotherapy, but the specific mechanism is not clear. This study aimed to further confirm the correlation between E2F1 rs3213150 polymorphism and Ara-C resistance and prognosis in AML patients, and to provide valuable information for elucidating the molecular mechanisms involved.

METHODS

Rs3213150 genotyping was performed in 922 AML patients by Sanger sequencing, and the effects of different genotypes on chemosensitivity and prognosis were analyzed by Logistic regression and Cox regression. Meanwhile, a prediction model of Ara-C chemotherapy resistance was established. The impact of rs3213150 polymorphism on E2F1 expression level was determined by luciferase reporter gene assay, and differentially expressed genes between patients with different genotypes were identified by RNA sequencing.

RESULTS

Compared with rs3213150 G allele carriers, patients with AA genotype had more obvious Ara-C resistance (41.94% vs. 27.94%, P = 0.002), shorter overall survival (529 d vs. 644 d, P = 0.008) and disease-free survival (519 d vs. 556 d, P = 0.023). Rs3213150G > A mutation resulted in decreased E2F1 expression.

CONCLUSION

E2F1 rs3213150 polymorphism influences the chemosensitivity and prognosis of Ara-C in Chinese AML patients.

Mechanism of E2F1 in the proliferation, migration, and invasion of endometrial carcinoma cells via the regulation of BMI1 transcription

BACKGROUND

Endometrial carcinoma (EC) is the most prevalent gynecological cancer. Transcription factor (TF) regulates a large number of downstream target genes and is a key determinant of all physiological activities, including cell proliferation, differentiation, apoptosis, and cell cycle. The transcription factor E2F1 shows prominent roles in EC. BMI1 is a member of Polycomb suppressor Complex 1 (PRC1) and has been shown to be associated with EC invasiveness. It is currently unclear whether E2F1 can participate in the proliferation, migration, and invasion processes of EC cells by regulating BMI1 transcription.

OBJECTIVE

We investigated whether E2F1 could participate in the proliferation, migration, and invasion processes of EC cells by regulating BMI1 transcription, in order to further clarify the pathogenesis and etiology of EC, and provide reference for identifying potential therapeutic targets and developing effective prevention and treatment strategies for this disease.

METHODS

Human endometrial epithelial cells (hEECs) and human EC cell lines were selected. E2F1 expression was assessed by Western blot. E2F1 was silenced in AN3CA or overexpressed in HEC-1 by transfections, or E2F1 was silenced and BMI1 was overexpressed in AN3CA by cotransfection. Cell proliferation, migration, and invasion were detected by MTT, wound healing, and Transwell assays. The binding sites between E2F1 and BMI1 promoters were predicted through JASPAR website, and the targeted binding was verified by dual-luciferase report and ChIP assays.

RESULTS

E2F1 was up-regulated in human EC cell lines, with its expression highest in AN3CA, and lowest in HEC-1. AN3CA invasion, migration, and proliferation were repressed by E2F1 knockdown, while those of HEC-1 cells were promoted by E2F1 overexpression. E2F1 overexpression increased the activity of wild type BMI1 reporter vector promoter, while this promotion was weakened after mutation of the predicted binding site in the BMI1 promoter. In the precipitated E2F1, BMI1 promoter site level was higher than that of IgG immunoprecipitant. BMI1 silencing suppressed AN3CA cell growth. BMI1 overexpression partially abrogated E2F1 silencing-inhibited EC cell growth.

CONCLUSION

E2F1 promoted EC cell proliferation, invasion, and migration by promoting the transcription of BMI1.

Emerging role of E2F8 in human cancer

E2F8 is a multifaceted transcription factor that plays a crucial role in mediating the hallmarks of cancer, including sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Aberrant E2F8 expression is associated with poor clinical outcomes in most human cancers. However, E2F8 also exhibits tumor-suppressing activity; thus, the role of E2F8 in cell-fate determination is unclear. In this review, we highlight the recent progress in understanding the role of E2F8 in human cancers, which will contribute to building a conceptual framework and broadening our knowledge pertaining to E2F8. This review provides insight into future challenges and perspectives regarding the translation of biological knowledge into therapeutic strategies for the treatment of cancer.

The Recurrent-Specific Regulation Network of Prognostic Stemness-Related Signatures in Low-Grade Glioma

Gliomas including astrocytomas, oligodendrogliomas, mixed oligoastrocytic, and mixed glioneuronal tumors are an important group of brain tumors. Based on the 2016 WHO classification for tumors in the central nervous system, gliomas were classified into four grades, from I to IV, and brain lower grade glioma (LGG) consists of grade II and grade III. Patients with LGG may undergo recurrence, which makes clinical treatment tough. Stem cell-like features of cancer cells play a key role in tumor's biological behaviors, including tumorigenesis, development, and clinical prognosis. In this article, we quantified the stemness feature of cancer cells using the mRNA stemness index (mRNAsi) and identified stemness-related key genes based on correlation with mRNAsi. Besides, hallmark gene sets and translate factors (TFs) which were highly related to stemness-related key genes were identified. Therefore, a recurrency-specific network was constructed and a potential regulation pathway was identified. Several online databases, assay for transposase-accessible chromatin using sequencing (ATAC-seq), single-cell sequencing analysis, and immunohistochemistry were utilized to validate the scientific hypothesis. Finally, we proposed that aurora kinase A (AURKA), positively regulated by Non-SMC Condensin I Complex Subunit G (NCAPG), promoted E2F target pathway in LGG, which played an important role in LGG recurrence.

Cellular Landscapes of Nondiseased Human Cardiac Valves From End-Stage Heart Failure-Explanted Heart

BACKGROUND

Exploring the mechanisms of valvular heart disease at the cellular level may be useful to identify new therapeutic targets; however, the comprehensive cellular landscape of nondiseased human cardiac valve leaflets remains unclear.

METHODS

The cellular landscapes of nondiseased human cardiac valve leaflets (5 aortic valves, 5 pulmonary valves, 5 tricuspid valves, and 3 mitral valves) from end-stage heart failure patients undergoing heart transplantation were explored using single-cell RNA sequencing. Bioinformatics was used to identify the cell types, describe the cell functions, and investigate cellular developmental trajectories and interactions. Differences among the 4 types of cardiac valves at the cellular level were summarized. Pathological staining was performed to validate the key findings of single-cell RNA sequencing. An integrative analysis of our single-cell data and published genome-wide association study-based and bulk RNA sequencing-based data provided insights into the cell-specific contributions to calcific aortic valve diseases.

RESULTS

Six cell types were identified among 128 412 cells from nondiseased human cardiac valve leaflets. Valvular interstitial cells were the largest population, followed by myeloid cells, lymphocytes, valvular endothelial cells, mast cells, and myofibroblasts. The 4 types of cardiac valve had distinct cellular compositions. The intercellular communication analysis revealed that valvular interstitial cells were at the center of the communication network. The integrative analysis of our single-cell RNA sequencing data revealed key cellular subpopulations involved in the pathogenesis of calcific aortic valve diseases.

CONCLUSIONS

The cellular landscape differed among the 4 types of nondiseased cardiac valve, which might explain their differences in susceptibility to pathological remodeling and valvular heart disease.

LncRNA BBOX1-AS1 promotes pituitary adenoma progression via sponging miR-361-3p/E2F1 axis

Pituitary adenoma is one of the most common intracranial tumors, more and more studies have shown that long non-coding RNA (lncRNA) plays a very important role in pituitary adenoma. However, there are few reports on the function of lncRNA BBOX1-AS1 in pituitary adenomas, and further exploration is needed. The objective of this research is to figure out what function BBOX1-AS1 plays in pituitary adenoma and how it regulates it. The expression of the E2F1, miR-361-3p and BOX1-AS1 genes was measured using a quantitative real-time PCR method. The functional involvement of BBOX1-AS1 in pituitary adenoma was examined utilizing the Transwell assay, western blot assays and the cell counting kit-8. RNA immunoprecipitation and luciferase reporter assays revealed that miR-361-3p binds to E2F1 or BBOX1-AS1. In addition, in-vivo assays were carried out. The expression of BBOX1-AS1 in pituitary adenoma tissues and cells has been increased, according to our findings. Furthermore, it is also noted that downregulation of BBOX1-AS1causes the inhibition of pituitary adenoma cells which result in invasion, apoptosis and proliferation, as well as boosting tumor development in vivo . In addition, BBOX1-AS1 knockdown inhibited tumor development in vivo . We identify BBOX1-AS1 bind to miR-361-3p and to suppress its expression in a negative way. Moreover, miR-361-3p has been shown to bind with E2F1 and inhibit its expression. E2F1 also corrected miR-361-3p-mediated cell invasion, proliferation and apoptosis in BBOX1-AS1-dysregulated pituitary adenoma cells in rescue tests. BBOX1-AS1 increases pituitary adenoma malignant activity by sponging miR-361-3p to upregulate E2F1 expression, which may lead to a new path in pituitary adenoma therapeutic attempts.

xCT contributes to colorectal cancer tumorigenesis through upregulation of the MELK oncogene and activation of the AKT/mTOR cascade

Colorectal cancer (CRC) is one of the most commonly diagnosed and deadly malignant tumors globally, and its occurrence and progression are closely related to the poor histological features and complex molecular characteristics among patients. It is urgent to identify specific biomarkers for effective treatment of CRC. In this study, we performed comprehensive experiments to validate the role of xCT expression in CRC tumorigenesis and stemness and confirmed xCT knockdown significantly suppressed the proliferation, migration, and stemness of CRC cells in vitro and effectively inhibited CRC tumorigenesis and metastasis in vivo. In addition, bioinformatic analysis and luciferase assays were used to identify E2F1 as a critical upstream transcription factor of SLC7A11 (the gene encoding for xCT) that facilitated CRC progression and cell stemness. Subsequent RNA sequencing, western blotting, rescue assay, and immunofluorescence assays revealed MELK directly co-expressed with xCT in CRC cells, and its upregulation significantly attenuated E2F1/xCT-mediated tumorigenesis and stemness in CRC. Further molecular mechanism exploration confirmed that xCT knockdown may exert an antitumor effect by controlling the activation of MELK-mediated Akt/mTOR signaling. Erastin, a specific inhibitor of xCT, was also proven to effectively inhibit CRC tumorigenesis and cell stemness. Altogether, our study showed that E2F1/xCT is a promising therapeutic target of CRC that promotes tumorigenesis and cell stemness. Erastin is also an effective antitumoral agent for CRC.

Harnessing the Heterogeneity of Prostate Cancer for Target Discovery Using Patient-Derived Explants

Simple Summary

There is a widespread push toward more biologically relevant pre-clinical models of prostate cancer that can improve the discovery and translation of new drugs and biomarkers for this disease. Patient-derived explant culture is an innovative pre-clinical model that utilizes surgical prostate cancer specimens in a way that retains the architecture, microenvironment and heterogeneity of prostate tumors—factors that critically influence cell behavior and response to therapy. With increasing tissue complexity comes increasing complexity of analysis. The aim of this study was to provide critical information for the successful application and analysis of the patient-derived prostate cancer explant model.

Abstract

Prostate cancer is a complex and heterogeneous disease, but a small number of cell lines have dominated basic prostate cancer research, representing a major obstacle in the field of drug and biomarker discovery. A growing lack of confidence in cell lines has seen a shift toward more sophisticated pre-clinical cancer models that incorporate patient-derived tumors as xenografts or explants, to more accurately reflect clinical disease. Not only do these models retain critical features of the original tumor, and account for the molecular diversity and cellular heterogeneity of prostate cancer, but they provide a unique opportunity to conduct research in matched tumor samples. The challenge that accompanies these complex tissue models is increased complexity of analysis. With over 10 years of experience working with patient-derived explants (PDEs) of prostate cancer, this study provides guidance on the PDE method, its limitations, and considerations for addressing the heterogeneity of prostate cancer PDEs that are based on statistical modeling. Using inhibitors of the molecular chaperone heat shock protein 90 (Hsp90) as an example of a drug that induces robust proliferative response, we demonstrate how multi-omics analysis in prostate cancer PDEs is both feasible and essential for identification of key biological pathways, with significant potential for novel drug target and biomarker discovery.

Positive regulation of ataxia-telangiectasia-mutated protein (ATM) by E2F transcription Factor 1 (E2F-1) in cisplatin-resistant nasopharyngeal carcinoma cells

Objective

To explore the mechanism of E2F transcription Factor 1 (E2F-1)-mediated ataxia-telangiectasia-mutated protein (ATM) in cisplatin (DDP)-resistant nasopharyngeal carcinoma (NPC).

Methods

E2F-1 and ATM expression was assessed in DDP-resistant NPC cell lines (CNE2/DDP and HNE1/DDP) and parental cells. Then, DDP-resistant NPC cells were transfected with control shRNA (short hairpin RNA) or E2F-1 shRNAs with or without ATM lentiviral activation particles. The half maximal inhibitory concentration (IC50) was evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, and the cell cycle and cell proliferation were measured by flow cytometry and EdU staining, respectively. In addition, the expression of genes and proteins was quantified by quantitative reverse-transcription polymerase chain reaction (qRT–PCR) and western blotting, respectively.

Results

Both E2F-1 and ATM expression in DDP-resistant NPC cells was much higher than that in parental cells. E2F-1 shRNA reduced ATM expression in DDP-resistant NPC cells, but ATM overexpression had no significant effect on E2F-1. ATM overexpression enhanced DDP resistance in DDP-resistant NPC cells with increased IC50 values, which was reversed by E2F-1 inhibition. Meanwhile, ATM overexpression resulted in upregulation of ABCA2 and ABCA5 in DDP-resistant NPC cells, induced elevations in the transition of the cells into S-phase, and increased cell proliferation with enhanced expression of cyclin E1, CDK2, and Ki67, which was reversed by E2F-1 shRNAs.

Conclusion

Downregulation of E2F-1, possibly by regulating ATM, could block the cell cycle in the G1 phase and reduce the proliferation of CNE2/DDP cells, thereby reversing the resistance of human NPC cells to DDP.

Methylation-dependent and -independent roles of EZH2 synergize in CDCA8 activation in prostate cancer

Cell division cycle-associated 8 (CDCA8) is a component of chromosomal passenger complex (CPC) that participates in mitotic regulation. Although cancer-related CDCA8 hyperactivation has been widely observed, its molecular mechanism remains elusive. Here, we report that CDCA8 overexpression maintains tumorigenicity and is associated with poor clinical outcome in patients with prostate cancer (PCa). Notably, enhancer of zeste homolog 2 (EZH2) is identified to be responsible for CDCA8 activation in PCa. Genome-wide assays revealed that EZH2-induced H3K27 trimethylation represses let-7b expression and thus protects the let-7b-targeting CDCA8 transcripts. More importantly, EZH2 facilitates the self-activation of E2F1 by recruiting E2F1 to its own promoter region in a methylation-independent manner. The high level of E2F1 further promotes transcription of CDCA8 along with the other CPC subunits. Taken together, our study suggests that EZH2-mediated cell cycle regulation in PCa relies on both its methyltransferase and non-methyltransferase activities.

Overexpression of Stathmin 1 Predicts Poor Prognosis and Promotes Cancer Cell Proliferation and Migration in Ovarian Cancer

Purpose

The aim of this study was to investigate the expression of stathmin 1 (STMN1) in ovarian cancer and its effect on prognosis. The effect and mechanism of STMN1 on the proliferation and migration of ovarian cancer cells were also investigated.

Methods

Expression of STMN1 was measured by immunohistochemical staining in ovarian cancer tissues. The effects of STMN1 on the proliferation and migration capacity of ovarian cancer were evaluated using Cell Counting Kit-8 (CCK-8) assays, colony formation assays, immunofluorescence staining, wound healing assays, and Transwell assays. Transcription factors were predicted by bioinformatic analysis of TCGA database.

Results

STMN1 was upregulated in ovarian cancer tissues as compared to paracancerous tissues and associated with shorter overall survival. STMN1 expression significantly correlated with FIGO staging and tumor differentiation (P < 0.05). Furthermore, STMN1 promoted proliferation and migration in ovarian cancer cell lines. Bioinformatic analysis revealed that STMN1 was potentially regulated by E2F transcription factors. Then, we found that E2F1 regulated the expression of STMN1 and affected proliferation.

Conclusion

STMN1 is overexpressed in ovarian cancer, and its high expression suggests a poor prognosis. STMN1 promotes the proliferation and migration of ovarian cancer and is regulated by E2F1. Thus, STMN1 may serve as a negative prognostic factor and possible target for the treatment of ovarian cancer patients.

Identification of the Expression and Clinical Significance of E2F Family in Clear Cell Renal Cell Carcinoma

Background

Multiple studies have identified that E2F transcriptions act as important regulators for the tumorigenesis and progression of several human cancers. However, little is known about the function of E2Fs in clear cell renal cell carcinoma (ccRCC).

Methods

We firstly investigated the expression levels, genetic alteration, and biological function of E2Fs in patients with ccRCC and the connections between the immune cell infiltration and the overall survivals of ccRCC patients with the E2Fs expression levels based on UALCAN, The Cancer Genome Atlas database, Gene Expression Profiling Interactive Analysis, TIMER, STRING, GSCALite and cBioPortal databases.

Results

Results revealed that the expression levels of E2F1/2/3/4/6/7/8 were markedly upregulated in patients with ccRCC, while the expression of E2F5 displayed an opposite trend. We also experimentally validated the overexpression of E2F3/4/7 in human ccRCC tissues and ccRCC cell lines. Furthermore, the high E2F1/2/3/4/7/8 expression levels were clearly associated with worse pathological characteristics of ccRCC, including high pathological stage, poor molecular subtypes and high tumor grade. Meanwhile, high expression levels of E2F1/2/4/7/8 were evidently associated with worse overall survivals (OSs) and progression-free survivals (PFSs) of patients harboring ccRCC. Univariate and multivariate analyses illustrated that the expressions of E2F4/5/7 were independent factors associated with the OSs and PFSs of patients with ccRCC. Meanwhile, the mutations in E2Fs were also significantly related to poor OSs and PFSs of patients with ccRCC. Mechanically, the E2Fs genes synergistically promoted the progression of ccRCC by accelerating the cell cycle and inhibiting DNA damage response and apoptosis after performing the protein structure, functional enrichment, and PPI network analyses. In addition, E2Fs genes were also significantly associated with tumor immune cells infiltration and the drug sensitivity in ccRCC.

Conclusion

As a result, E2F4/7 were highly expressed in ccRCC and significantly associated with worse pathological characteristics of ccRCC, including high pathological stage, poor molecular subtypes and high tumor grade, tumor immune cell infiltration, and drug sensitivity, consequently translating into poor OSs and PFSs of patients with ccRCC. Our results indicated that E2F4/7 could be potential biomarkers and therapeutic targets of ccRCC patients.

A novel ferroptosis-related gene prognostic index for prognosis and response to immunotherapy in patients with prostate cancer

BACKGROUND

Prostate cancer (PCa) is among the leading causes of cancer death worldwide. Ferroptosis refers to an iron-dependent form of regulated cell death and is involved in prostate tumorigenesis. A few ferroptosis-related gene signatures have been developed to predict the prognosis for PCa patients. However, previous signatures were typically established based on biochemical recurrence-free survival, which has proven not to be a good surrogate for overall survival (OS). This study aimed to construct a novel ferroptosis-related gene prognostic index (FRGPI) to predict disease-free survival (DFS) and response to immunotherapy for PCa patients after radical prostatectomy.

METHODS

Gene expression and clinicopathological data on PCa patients were obtained from the TCGA database. Ferroptosis-related hub genes associated with DFS of PCa patients were identified by an in-depth bioinformatics analysis using a novel and comprehensive algorithm based on functional enrichment, consensus clustering, weighted gene co-expression network analysis (WGCNA), and protein-protein interaction (PPI) network construction. The FRGPI was established on the basis of the genes selected using multivariate cox regression analysis and further validated in two additional PCa cohorts. Next, the clinicopathological, molecular, and immune profiles were characterized and compared between FRGPI-high and FRGPI-low subgroups. Finally, the predictive role of the FRGPI in response to immunotherapy was estimated using a metastatic urothelial cancer cohort treated with an anti-PD-L1 agent.

RESULTS

The FRGPI was constructed based on four genes (E2F1, CDC20, TYMS, and NUP85), and FRGPI-high patients had worse DFS than FRGPI-low patients. Multivariate cox regression analysis revealed that FRGPI could act as an independent prognostic factor for PCa patients after radical prostatectomy. A prognostic nomogram comprising the FRGPI and other clinicopathological parameters was established to predict the DFS for PCa patients quantitatively. In addition, comprehensive results demonstrated that high FRGPI scores showed a significantly positive correlation with worse clinicopathological features, higher mutation counts, increased frequency of copy number variations (CNVs), higher homologous recombination deficiency (HRD) and immune scores, higher mRNAsi, and more importantly, enhanced sensitivity to immunotherapy.

CONCLUSIONS

FRGPI is not only a promising and robust prognostic biomarker, but also a potential indicator of immunotherapeutic outcomes for PCa patients after radical prostatectomy.

FOXO1 inhibits prostate cancer cell proliferation via suppressing E2F1 activated NPRL2 expression

Previous studies in our lab suggest that nitrogen permease regulator 2-like (NPRL2) upregulation in prostate cancer is associated with malignant behavior and poor prognosis. However, the underlying mechanisms of NPRL2 dysregulation remain poorly understood. This study aimed to explore the transcription factors (TFs) contributing to NPRL2 dysregulation in prostate cancer. Potential TFs were identified using prostate tissue/cell-specific chromatin immunoprecipitation (ChIP)-seq data collected in the Cistrome Data Browser and Signaling Pathways Project. Dual-luciferase assay and ChIP-qPCR assay were conducted to assess the binding and activating effect of TFs on the gene promoter. Cell Counting Kit-8 and colony formation assays were performed to assess cell proliferation. Results showed that E2F1 is a TF that bound to the NPRL2 promoter and activated its transcription. NPRL2 inhibition significantly alleviated E2F1 enhanced cell proliferation. Kaplan-Meier survival analysis indicated that E2F1 upregulation was associated with unfavorable progression-free survival and disease-specific survival. FOXO1 interacted and E2F1 in both PC3 and LNCaP cells and weakened the binding of E2F1 to the NPRL2 promoter. Functionally, FOXO1 overexpression significantly slowed the proliferation of PC3 and LNCaP cells and also decreased E2F1 enhanced cell proliferation. In summary, this study revealed a novel FOXO1/E2F1-NPRL2 regulatory axis in prostate cancer. E2F1 binds to the NPRL2 promoter and activates its transcription, while FOXO1 interacts with E2F1 and weakens its transcriptional activating effects. These findings help expand our understanding of the prostate cancer etiology and suggest that the FOXO1/E2F1-NPRL2 signaling axis might be a potential target.

Exosomal miRNA-205 promotes breast cancer chemoresistance and tumorigenesis through E2F1

Breast cancer (BC) is a common malignant tumor in females. The challenge in treating BC is overcoming chemoresistance. Exosome-mediated transfer of miRNAs is a molecule-shuttle in intercellular communication. Thus, we aimed to investigate whether exosomal miRNA-205 could affect chemoresistance and tumorigenesis in recipient tumor cells and to elucidate the underlying mechanism in vivo and in vitro. Microarray and qRT-PCR assays demonstrated that miRNA-205 was upregulated in tamoxifen resistance MCF-7/TAMR-1 (M/T) cells and M/T cell-derived exosomes (M/T-Exo). The M/T-Exo was internalized by human BC cells (BCCs), causing increased expression of miRNA-205 in BCCs. Coculturing with M/T-Exo promoted tamoxifen resistance, proliferation, migration, and invasion while suppressed apoptosis in recipient BCCs, which were associated with activating the caspase pathway and phosphorylating Akt. Luciferase reporter assays showed that miRNA-205 directly targeted E2F Transcription Factor 1 (E2F1) in BCCs. Furthermore, knockdown of miRNA-205 or overexpression of E2F1 reversed the roles of M/T-Exo in BCCs. In vivo experiments showed that the intratumoral injection of M/T-Exo caused greater tamoxifen resistance and larger tumor size relative to mice treated with miRNA-205-knockdown or E2F1-overexpressing BCCs. Together, the results suggest that exosomal miRNA-205 may promote tamoxifen resistance and tumorigenesis in BC through targeting E2F1 in vivo and in vitro.

Gypenoside LI arrests the cell cycle of breast cancer in G0/G1 phase by down-regulating E2F1

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino, a traditional medicine in China, has been widely used for the treatment of various diseases. Gypenoside LI (Gyp LI) is a major constituent from steamed G. pentaphyllum. Previous studies have shown that gypnenoside LI possess inhibitory effect on the growth of many cancer cells. However, its pharmacological effect in breast cancer and the mechanism have not been reported yet.

AIM OF THE STUDY

To investigate the anti-breast cancer activity of gypenoside LI and underlying mechanisms of gypenoside LI in MDA-MB-231 and MCF-7 cells.

MATERIAL/METHODS

The cytotoxicity of gypenoside LI was determined by MTT, colony-formation and three-dimensional spheroid assay. The migration, cell apoptosis and the cell cycle were investigated through cell morphology observation, flow cytometry analysis and key proteins detection. The anticancer mechanisms of gypenoside LI were detected by RNA sequencing (RNA-seq) and Gene Set Enrichment Analysis (GSEA) transcriptome analysis.

RESULTS

Gypenoside LI inhibited cell proliferation, migration, induced cell apoptosis and cell cycle arrest. Gypenoside LI arrested cell cycle at G0/G1 phase by regulating E2F1. It also inhibited tumor proliferation by regulating the expression of ERCC6L. Interestingly, we found that E2F1 siRNA also down-regulated the expression of ERCC6L. Gypenoside LI showed potential anti-breast cancer cells activity, especially on triple-negative breast cancer cells.

CONCLUSIONS

These data indicate that gypenoside LI could inhibit human breast cancer cells through inhibiting proliferation and migration, inducing apoptosis, arresting cell cycle at G0/G1 phase by regulating E2F1. It could be used as potential multi-target chemopreventive agents for cancer.

Identifying an lncRNA-Related ceRNA Network to Reveal Novel Targets for a Cutaneous Squamous Cell Carcinoma

Simple Summary

The exact functions and molecular mechanism of lncRNAs, acting as competitive endogenous RNAs in a cutaneous squamous cell carcinoma, remain unexplored. The present study was conducted to identify the differentially expressed lncRNAs and mRNAs and establish the lncRNA-related competing endogenous RNA networks associated with a cutaneous squamous cell carcinoma. A competing endogenous RNA network consisting of 137 miRNA-lncRNA and 221 miRNA-mRNA pairs was constructed. As for the functional analysis of the mRNAs in the network, a FoxO signaling pathway, an autophagy and cellular senescence were the top enrichment terms based on the Kyoto Encyclopedia of Genes and Genomes analysis. We identified five core mRNAs and built a core mRNA-associated competing endogenous RNA network. Finally, one lncRNA HLA-F-AS1 and three mRNAs named AGO4, E2F1 and CCND1 in the core mRNA-associated competing endogenous RNA network were validated with the same expression patterns. The core mRNAs and their associated lncRNAs may provide potential therapeutic targets for cutaneous squamous cell carcinomas.

Abstract

A cutaneous squamous cell carcinoma (cSCC) derived from keratinocytes is the second most common cause of non-melanoma skin cancer. The accumulation of the mutational burden of genes and cellular DNA damage caused by the risk factors (e.g., exposure to ultraviolet radiation) contribute to the aberrant proliferation of keratinocytes and the formation of a cSCC. A cSCC encompasses a spectrum of diseases that range from recursor actinic keratosis (AK) and squamous cell carcinoma (SCC) in situ (SCCIS) to invasive cSCCs and further metastatic SCCs. Emerging evidence has revealed that lncRNAs are involved in the biological process of a cSCC. According to the ceRNA regulatory theory, lncRNAs act as natural miRNA sponges and interact with miRNA response elements, thereby regulating the mRNA expression of their down-stream targets. This study was designed to search for the potential lncRNAs that may become potential therapeutic targets or biomarkers of a cSCC. Considering the spirit of the study to be adequately justified, we collected microarray-based datasets of 19 cSCC tissues and 12 normal skin samples from the GEO database (GSE42677 and GSE45164). After screening the differentially expressed genes via a limma package, we identified 24 differentially expressed lncRNAs (DElncRNAs) and 3221 differentially expressed mRNAs (DEmRNAs). The miRcode, miRTarBase, miRDB and TargetScan databases were used to predict miRNAs that could interact with DElncRNAs and DEmRNAs. A total of 137 miRNA-lncRNA and 221 miRNA-mRNA pairs were retained in the ceRNA network, consisting of 31 miRNAs, 11 DElncRNAs and 155 DEmRNAs. For the functional analysis, the top enriched biological process was enhancer sequence-specific DNA binding in Gene Ontology (GO) terms. The FoxO signaling pathway, autophagy and cellular senescence were the top enrichment terms based on a Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The combination of a STRING tool and Cytoscape software (plug-in MCODE) identified five core mRNAs and built a core mRNA-associated ceRNA network. The expression for five identified core mRNAs and their related nine lncRNAs was validated using the external dataset GSE7553. Finally, one lncRNA HLA-F-AS1 and three mRNAs named AGO4, E2F1 and CCND1 were validated with the same expression patterns. We speculate that lncRNA HLA-F-AS1 may sponge miR-17-5p or miR-20b-5p to regulate the expression of CCND1 and E2F1 in the cSCC. The present study may provide potential diagnostic and therapeutic targets for cSCC patients.

[Advancement of E2F1 in Common Tumors]

细胞周期相关转录因子E2F1（E2F transcription factor 1）是细胞周期相关转录因子E2F家族成员之一，主要参与包括细胞周期进展、DNA修复、DNA复制、细胞分化，增殖和凋亡等多种细胞过程。E2F1在全身多种肿瘤组织和细胞中呈高表达，起着促癌基因的作用，E2F1表达上调与肿瘤的发生、发展、转移及预后密切相关。因此，E2F1有望成为肿瘤治疗的新靶点。本文就E2F1在目前常见肿瘤中的最新研究进展做一综述。

Powerful quantifiers for cancer transcriptomics

Every day, investigators find a new link between a form of cancer and a particular alteration in the sequence or/and expression level of a key gene, awarding this gene the title of “biomarker”. The clinician may choose from numerous available panels to assess the type of cancer based on the mutation or expression regulation (“transcriptomic signature”) of “driver” genes. However, cancer is not a “one-gene show” and, together with the alleged biomarker, hundreds other genes are found as mutated or/and regulated in cancer samples. Regardless of the platform, a well-designed transcriptomic study produces three independent features for each gene: Average expression level, expression variability and coordination with expression of each other gene. While the average expression level is used in all studies to identify what genes were up-/down-regulated or turn on/off, the other two features are unfairly ignored. We use all three features to quantify the transcriptomic change during the progression of the disease and recovery in response to a treatment. Data from our published microarray experiments on cancer nodules and surrounding normal tissue from surgically removed tumors prove that the transcriptomic topologies are not only different in histopathologically distinct regions of a tumor but also dynamic and unique for each human being. We show also that the most influential genes in cancer nodules [the Gene Master Regulators (GMRs)] are significantly less influential in the normal tissue. As such, “smart” manipulation of the cancer GMRs expression may selectively kill cancer cells with little consequences on the normal ones. Therefore, we strongly recommend a really personalized approach of cancer medicine and present the experimental procedure and the mathematical algorithm to identify the most legitimate targets (GMRs) for gene therapy.

High glucose may promote the proliferation and metastasis of hepatocellular carcinoma via E2F1/RRBP1 pathway

AIMS

Diabetes is considered as one of the important risks in the progression of Hepatocellular carcinoma(HCC). Ribosome binding protein 1 (RRBP1), a rough endoplasmic reticulum protein, plays an essential role in diabetes and various cancer. E2F transcription factor 1 (E2F1), an upstream transcription factor of RRBP1, shows promoting tumor progression effect in multifarious cancers. In this research, we tried to identify whether regulating E2F1/RRBP1 pathway could inhibit the proliferation and metastasis of HepG2 cells induced by high glucose.

MAIN METHODS

Proteomic, bioinformatics, molecular biology including RT-qPCR and Western blot, cell biology containing Cell Counting Kit-8 (CCK-8), wound healing assay and transwell assay, and biochemistry analyses incorporating Luciferase assay and CHIP assay were used in this study.

KEY FINDINGS

High glucose promoted the proliferation and metastasis of HepG2 cells through up-regulating the expression of RRBP1. Bioinformatics analysis predicted that E2F1 might be the transcription factor of RRBP1. Knocking-down of E2F1 down-regulated mRNA and protein expression levels of RRBP1 in HepG2 cells significantly and suppressed the proliferation, migration and invasion of cells remarkably, Reverse effect was observed in cells that E2F1 was overexpressed. Meanwhile, luciferase and CHIP assay determined that E2F1 could bind to the RRBP1 promoter and promote the transcription of RRBP1. Finally, rescue assay verified the important role of RRBP1/E2F1 axis in the process of HepG2 cells proliferation and metastasis.

SIGNIFICANCE

All of the above provided possibility to improve the efficiency of HCC complicated with diabetes treatment by regulating the E2F1/RRBP1 pathway.

New relationship of E2F1 and BNIP3 with caveolin-1 in lung cancer-associated fibroblasts

In recent years, studies have found that E2F1, a downstream effector of caveolin‐1 (Cav‐1), participates in tumor cell metabolic reprogramming. E2F1 modulates mitochondrial fusion and mitophagy. Bioinformatic analysis has identified the E2F1‐MFN2 axis as a regulator of mitophagy. Our data establish a new novel paradigm for regulation of the tumor cell metabolic reprogramming pathway by Cav‐1 that is operationally linked and mutually dependent on the transcriptional activation of E2F1 and induces mitophagy with BNIP3 in cancer‐associated fibroblasts (CAFs).