New link between RNH1 and E2F1: regulates the development of lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) is a non-small cell carcinoma. Ribonuclease/angiogenin inhibitor 1 (RNH1) exerts multiple roles in virous cancers. E2F1 is a critical transcription factor involved in the LUAD development. Here, we analyze the expression of RNH1 in LUAD patients, investigate the biological function of RNH1 in LUAD, and demonstrate its potential mechanisms through E2F1 in LUAD. METHODS: In the present study, we presented the expression of RNH1 in LUAD based on the database and confirmed it by western blot detection of RNH1 in human LUAD tissues. Lentiviral infection was constructed to silence or overexpress RNH1 in NCI-H1395 and NCI-H1437 cells. We assess the role of RNH1 on proliferation in LUAD cells by MTT assay, colony formation assays, and cell cycle detection. Hoechst staining and flow cytometry were used to evaluate the effects of RNH1 on apoptosis of LUAD cells. The function of RNH1 in invasion and migration was investigated by Transwell assay. Dual luciferase assay, ChIP detection, and pull-down assay were conducted to explore the association of E2F1 in the maintenance of RNH1 expression and function. The regulation of E2F1 on the functions of RNH1 in LUAD cells was explored. Mouse experiments were performed to confirm the in-vivo role of RNH1 in LUAD. mRNA sequencing indicated that RNH1 overexpression altered the expression profile of LUAD cells. RESULTS: RNH1 expression in LUAD tissues of patients was presented in this work. Importantly, RNH1 knockdown improved the proliferation, migration and invasion abilities of cells and RNH1 overexpression produced the opposite effects. Dual luciferase assay proved that E2F1 bound to the RNH1 promoter (-1064 ∼ -1054, -1514 ∼ -1504) to reduce the transcriptional activity of RNH1. ChIP assay indicated that E2F1 DNA was enriched at the RNH1 promoter (-1148 ∼ -943, -1628 ∼ -1423). Pull-down assays also showed the association between E2F1 and RNH1 promoter (-1148 ∼ -943). E2F1 overexpression contributed to the malignant behavior of LUAD cells, while RNH1 overexpression reversed it. High-throughput sequencing showed that RNH1 overexpression induced multiple genes expression changes, thereby modulating LUAD-related processes. CONCLUSION: Our study demonstrates that binding of E2F1 to the RNH1 promoter may lead to inhibition of RNH1 expression and thus promoting the development of LUAD.

H2A.Z chaperones converge on E2F target genes for melanoma cell proliferation.

High levels of H2A.Z promote melanoma cell proliferation and correlate with poor prognosis. However, the role of the two distinct H2A.Z histone chaperone complexes SRCAP and P400-TIP60 in melanoma remains unclear. Here, we show that individual subunit depletion of SRCAP, P400, and VPS72 (YL1) results in not only the loss of H2A.Z deposition into chromatin but also a reduction of H4 acetylation in melanoma cells. This loss of H4 acetylation is particularly found at the promoters of cell cycle genes directly bound by H2A.Z and its chaperones, suggesting a coordinated regulation between H2A.Z deposition and H4 acetylation to promote their expression. Knockdown of each of the three subunits downregulates E2F1 and its targets, resulting in a cell cycle arrest akin to H2A.Z depletion. However, unlike H2A.Z deficiency, loss of the shared H2A.Z chaperone subunit YL1 induces apoptosis. Furthermore, YL1 is overexpressed in melanoma tissues, and its upregulation is associated with poor patient outcome. Together, these findings provide a rationale for future targeting of H2A.Z chaperones as an epigenetic strategy for melanoma treatment.

Microcephaly Gene Mcph1 Deficiency Induces p19ARF-Dependent Cell Cycle Arrest and Senescence.

MCPH1 has been identified as the causal gene for primary microcephaly type 1, a neurodevelopmental disorder characterized by reduced brain size and delayed growth. As a multifunction protein, MCPH1 has been reported to repress the expression of TERT and interact with transcriptional regulator E2F1. However, it remains unclear whether MCPH1 regulates brain development through its transcriptional regulation function. This study showed that the knockout of Mcph1 in mice leads to delayed growth as early as the embryo stage E11.5. Transcriptome analysis (RNA-seq) revealed that the deletion of Mcph1 resulted in changes in the expression levels of a limited number of genes. Although the expression of some of E2F1 targets, such as Satb2 and Cdkn1c, was affected, the differentially expressed genes (DEGs) were not significantly enriched as E2F1 target genes. Further investigations showed that primary and immortalized Mcph1 knockout mouse embryonic fibroblasts (MEFs) exhibited cell cycle arrest and cellular senescence phenotype. Interestingly, the upregulation of p19ARF was detected in Mcph1 knockout MEFs, and silencing p19Arf restored the cell cycle and growth arrest to wild-type levels. Our findings suggested it is unlikely that MCPH1 regulates neurodevelopment through E2F1-mediated transcriptional regulation, and p19ARF-dependent cell cycle arrest and cellular senescence may contribute to the developmental abnormalities observed in primary microcephaly.

E2F transcription factors promote tumorigenicity in pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with limited treatment options, illustrating an urgent need to identify new drugable targets in PDACs. OBJECTIVE: Using the similarities between tumor development and normal embryonic development, which is accompanied by rapid cell expansion, we aimed to identify and characterize embryonic signaling pathways that were reinitiated during tumor formation and expansion. METHODS AND RESULTS: Here, we report that the transcription factors E2F1 and E2F8 are potential key regulators in PDAC. E2F1 and E2F8 RNA expression is mainly localized in proliferating cells in the developing pancreas and in malignant ductal cells in PDAC. Silencing of E2F1 and E2F8 in PANC-1 pancreatic tumor cells inhibited cell proliferation and impaired cell spreading and migration. Moreover, loss of E2F1 also affected cell viability and apoptosis with E2F expression in PDAC tissues correlating with expression of apoptosis and mitosis pathway genes, suggesting that E2F factors promote cell cycle regulation and tumorigenesis in PDAC cells. CONCLUSION: Our findings illustrate that E2F1 and E2F8 transcription factors are expressed in pancreatic progenitor and PDAC cells, where they contribute to tumor cell expansion by regulation of cell proliferation, viability, and cell migration making these genes attractive therapeutic targets and potential prognostic markers for pancreatic cancer.

Two sequential gene expression programs bridged by cell division support long-distance collective cell migration.

The precise assembly of tissues and organs relies on spatiotemporal regulation of gene expression to coordinate the collective behavior of cells. In Drosophila embryos, the midgut musculature is formed through collective migration of caudal visceral mesoderm (CVM) cells, but how gene expression changes as cells migrate is not well understood. Here, we have focused on ten genes expressed in the CVM and the cis-regulatory sequences controlling their expression. Although some genes are continuously expressed, others are expressed only early or late during migration. Late expression relates to cell cycle progression, as driving string/Cdc25 causes earlier division of CVM cells and accelerates the transition to late gene expression. In particular, we found that the cell cycle effector transcription factor E2F1 is a required input for the late gene CG5080. Furthermore, whereas late genes are broadly expressed in all CVM cells, early gene transcripts are polarized to the anterior or posterior ends of the migrating collective. We show this polarization requires transcription factors Snail, Zfh1 and Dorsocross. Collectively, these results identify two sequential gene expression programs bridged by cell division that support long-distance directional migration of CVM cells.

Bleomycin induces senescence and repression of DNA repair via downregulation of Rad51.

BACKGROUND: Bleomycin, a potent antitumor agent, is limited in clinical use due to the potential for fatal pulmonary toxicity. The accelerated DNA damage and senescence in alveolar epithelial cells (AECs) is considered a key factor in the development of lung pathology. Understanding the mechanisms for bleomycin-induced lung injury is crucial for mitigating its adverse effects. METHODS: Human lung epithelial (A549) cells were exposed to bleomycin and subsequently assessed for cellular senescence, DNA damage, and double-strand break (DSB) repair. The impact of Rad51 overexpression on DSB repair and senescence in AECs was evaluated in vitro. Additionally, bleomycin was intratracheally administered in C57BL/6 mice to establish a pulmonary fibrosis model. RESULTS: Bleomycin exposure induced dose- and time-dependent accumulation of senescence hallmarks and DNA lesions in AECs. These effects are probably due to the inhibition of Rad51 expression, consequently suppressing homologous recombination (HR) repair. Mechanistic studies revealed that bleomycin-mediated transcriptional inhibition of Rad51 might primarily result from E2F1 depletion. Furthermore, the genetic supplement of Rad51 substantially mitigated bleomycin-mediated effects on DSB repair and senescence in AECs. Notably, decreased Rad51 expression was also observed in the bleomycin-induced mouse pulmonary fibrosis model. CONCLUSIONS: Our works suggest that the inhibition of Rad51 plays a pivotal role in bleomycin-induced AECs senescence and lung injury, offering potential strategies to alleviate the pulmonary toxicity of bleomycin.

Absence of E2f1 Negates Pro-osteogenic Impacts of p21 Absence.

Loss of p21 leads to increased bone formation post-injury; however, the mechanism(s) by which this occurs remains undetermined. E2f1 is downstream of p21 and as a transcription factor can act directly on gene expression; yet it is unknown if E2f1 plays a role in the osteogenic effects observed when p21 is differentially regulated. In this study we aimed to investigate the interplay between p21 and E2f1 and determine if the pro-regenerative osteogenic effects observed with the loss of p21 are E2f1 dependent. To accomplish this, we employed knockout p21 and E2f1 mice and additionally generated a p21/E2f1 double knockout. These mice underwent burr-hole injuries to their proximal tibiae and healing was assessed over 7 days via microCT imaging. We found that p21 and E2f1 play distinct roles in bone regeneration where the loss of p21 increased trabecular bone formation and loss of E2f1 increased cortical bone formation, yet loss of E2f1 led to poorer bone repair overall. Furthermore, when E2f1 was absent, either individually or simultaneously with p21, there was a dramatic decrease of the number of osteoblasts, osteoclasts, and chondrocytes at the site of injury compared to p21-/- and C57BL/6 mice. Together, these results suggest that E2f1 regulates the cell populations required for bone repair and has a distinct role in bone formation/repair compared to p21-/-E2f1-/-. These results highlight the possibility of cell cycle and/or p21/E2f1 being potential druggable targets that could be leveraged in clinical therapies to improve bone healing in pathologies such as osteoporosis.

The pRb/RBL2-E2F1/4-GCN5 axis regulates cancer stem cell formation and G0 phase entry/exit by paracrine mechanisms.

The lethality, chemoresistance and metastatic characteristics of cancers are associated with phenotypically plastic cancer stem cells (CSCs). How the non-cell autonomous signalling pathways and cell-autonomous transcriptional machinery orchestrate the stem cell-like characteristics of CSCs is still poorly understood. Here we use a quantitative proteomic approach for identifying secreted proteins of CSCs in pancreatic cancer. We uncover that the cell-autonomous E2F1/4-pRb/RBL2 axis balances non-cell-autonomous signalling in healthy ductal cells but becomes deregulated upon KRAS mutation. E2F1 and E2F4 induce whereas pRb/RBL2 reduce WNT ligand expression (e.g. WNT7A, WNT7B, WNT10A, WNT4) thereby regulating self-renewal, chemoresistance and invasiveness of CSCs in both PDAC and breast cancer, and fibroblast proliferation. Screening for epigenetic enzymes identifies GCN5 as a regulator of CSCs that deposits H3K9ac onto WNT promoters and enhancers. Collectively, paracrine signalling pathways are controlled by the E2F-GCN5-RB axis in diverse cancers and this could be a therapeutic target for eliminating CSCs.

DNA G-Quadruplex in NRP1 Promoter Facilitates SARS-CoV-2 Infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection continues to raise concerns worldwide. Numerous host factors involved in SARS-CoV-2 infection have been identified, but the regulatory mechanisms of these host factor remain unclear. Here, we report the role of G-quadruplexes (G4s) located in the host factor promoter region in SARS-CoV-2 infection. Using bioinformatics, biochemical, and biological assays, we provide evidence for the presence of G4 structures in the promoter regions of SARS-CoV-2 host factors NRP1. Specifically, we focus on two representative G4s in the NRP1 promoter and highlight its importance in SARS-CoV-2 pathogenesis. The presence of the G4 structure greatly increases NRP1 expression, facilitating SARS-CoV-2 entry into cells. Utilizing published single-cell RNA sequencing data obtained from simulated SARS-CoV-2 infection in human bronchial epithelial cells (HBECs), we found that ciliated cells with high levels of NRP1 are prominently targeted by the virus during infection. Furthermore, our study identifies E2F1 act as a transcription factor that binds to G4s. These findings uncover a previously unknown mechanism underlying SARS-CoV-2 infection and suggest that targeting G4 structures could be a potential strategy for COVID-19 prevention and treatment.

Long non­coding RNA DANCR aggravates breast cancer through the miR­34c/E2F1 feedback loop.

Emerging scientific evidence has suggested that the long non­coding (lnc)RNA differentiation antagonizing non­protein coding RNA (DANCR) serves a significant role in human tumorigenesis and cancer progression; however, the precise mechanism of its function in breast cancer remains to be fully understood. Therefore, the objective of the present study was to manipulate DANCR expression in MCF7 and MDA­MB­231 cells using lentiviral vectors to knock down or overexpress DANCR. This manipulation, alongside the analysis of bioinformatics data, was performed to investigate the potential mechanism underlying the role of DANCR in cancer. The mRNA and/or protein expression levels of DANCR, miR­34c­5p and E2F transcription factor 1 (E2F1) were assessed using reverse transcription­quantitative PCR and western blotting, respectively. The interactions between these molecules were validated using chromatin immunoprecipitation and dual­luciferase reporter assays. Additionally, fluorescence in situ hybridization was used to confirm the subcellular localization of DANCR. Cell proliferation, migration and invasion were determined using 5­ethynyl­2'­deoxyuridine, wound healing and Transwell assays, respectively. The results of the present study demonstrated that DANCR had a regulatory role as a competing endogenous RNA and upregulated the expression of E2F1 by sequestering miR­34c­5p in breast cancer cells. Furthermore, E2F1 promoted DANCR transcription by binding to its promoter in breast cancer cells. Notably, the DANCR/miR­34c­5p/E2F1 feedback loop enhanced cell proliferation, migration and invasion in breast cancer cells. Thus, these findings suggested that targeting DANCR may potentially provide a promising future therapeutic strategy for breast cancer treatment.

Aspongopus chinensis ach-miR-276a-3p induces breast cancer cell cycle arrest by targeting APPL2 to regulate the CDK2-Rb-E2F1 signaling pathway.

Breast cancer, the most common cancer, presents a significant challenge to the health and longevity of women. Aspongopus chinensis Dallas is an insect with known anti-breast cancer properties. However, the anti-breast cancer effects and underlying mechanisms have not been elucidated. Exogenous microRNAs (miRNAs), which are derived from plants and animals, have been revealed to have notable capacities for controlling the proliferation of cancerous cells. To elucidate the inhibitory effects of miRNAs derived from A. chinensis and the regulatory mechanism involved in the growth of breast cancer cells, miRNA sequencing was initially employed to screen for miRNAs both in A. chinensis hemolymph and decoction and in mouse serum and tumor tissue after decoction gavage. Subsequently, the experiments were performed to assess the suppressive effect of ach-miR-276a-3p, the miRNA screened out from a previous study, on the proliferation of MDA-MB-231 and MDA-MB-468 breast cancer cell lines in vitro and in vivo. Finally, the regulatory mechanism of ach-miR-276a-3p in MDA-MB-231 and MDA-MB-468 breast cancer cells was elucidated. The results demonstrated that ach-miR-276a-3p notably inhibited breast cancer cell proliferation, migration, colony formation, and invasion and induced cell cycle arrest at the G0/G1 phase. Moreover, the ach-miR-276a-3p mimics significantly reduced the tumor volume and weight in xenograft tumor mice. Furthermore, ach-miR-276a-3p could induce cell cycle arrest by targeting APPL2 and regulating the CDK2-Rb-E2F1 signaling pathway. In summary, ach-miR-276a-3p, derived from A. chinensis, has anti-breast cancer activity by targeting APPL2 and regulating the CDK2-Rb-E2F1 signaling pathway and can serve as a promising candidate anticancer agent.

Epigenetic activation of METTL14 promotes docetaxel resistance in prostate cancer by promoting pri-microRNA-129 maturation.

The development of resistance to Docetaxel (DTX) compromises its therapeutic efficacy and worsens the prognosis of prostate cancer (PCa), while the underlying regulatory mechanism remains poorly understood. In this study, METTL14 was found to be upregulated in DTX-resistant PCa cells and PCa tissues exhibiting progressive disease during DTX therapy. Furthermore, overexpression of METTL14 promoted the development of resistance to DTX in both in vitro and in vivo. Interestingly, it was observed that the hypermethylation of the E2F1 targeting site within DTX-resistant PCa cells hindered the binding ability of E2F1 to the promoter region of METTL14, thereby augmenting its transcriptional activity. Consequently, this elevated expression level of METTL14 facilitated m6A-dependent processing of pri-miR-129 and subsequently led to an increase in miR-129-5p expression. Our study highlights the crucial role of the E2F1-METTL14-miR-129-5p axis in modulating DTX resistance in PCa, underscoring METTL14 as a promising therapeutic target for DTX-resistant PCa patients.

Hsa_circ_0007990 promotes breast cancer growth via inhibiting YBX1 protein degradation to activate E2F1 transcription.

Breast cancer (BC) is the most commonly diagnosed malignant tumour in females worldwide. Although remarkable advances in early detection and treatment strategies have led to decreased mortality, recurrence and metastasis remain the major causes of cancer death in BC patients. Increasing evidence has demonstrated that circular RNAs (circRNAs) play critical roles in cancer progression. However, the detailed biological functions and molecular mechanisms of circRNAs in BC are unclear. The aim of this study was to investigate the possible role of circRNAs in the progression of BC. Differentially expressed circRNAs in BC were identified by integrating breast tumour-associated somatic CNV data and circRNA high-throughput sequencing. Aberrant hsa_circ_0007990 expression and host gene copy number were detected in BC cell lines via quantitative polymerase chain reaction (qPCR). The expression level of hsa_circ_0007990 in BC tissues was validated by in situ hybridization (ISH). Loss- and gain-of-function experiments were performed in vitro and in vivo, respectively, to explore the potential biological function of hsa_circ_0007990 in BC. The underlying mechanisms of hsa_circ_0007990 were investigated through MS2 RNA pull-down, RNA immunoprecipitation, RNA fluorescence in situ hybridization, immunofluorescence, chromatin immunoprecipitation and luciferase reporter assays. The levels of hsa_circ_0007990 were elevated in BC tissues and cell lines, an effect that was partly due to host gene copy number gains. Functional assays showed that hsa_circ_0007990 promoted BC cell growth. Mechanistically, hsa_circ_0007990 could bind to YBX1 and inhibit its degradation by preventing ubiquitin/proteasome-dependent degradation, thus enhancing the expression of the cell cycle-associated gene E2F1. Rescue experiments suggested that hsa_circ_0007990 promoted BC progression through YBX1. In general, our study demonstrated that hsa_circ_0007990 modulates the ubiquitination and degradation of YBX1 protein and further regulates E2F1 expression to promote BC progression. We explored the possible function and molecular mechanism of hsa_circ_0007990 in BC and identified a novel candidate target for the treatment of BC.

E2F1 promotes cell migration in hepatocellular carcinoma via FNDC3B.

FNDC3B (fibronectin type III domain containing 3B) is highly expressed in hepatocellular carcinoma (HCC) and other cancer types, and fusion genes involving FNDC3B have been identified in HCC and leukemia. Growing evidence suggests the significance of FNDC3B in tumorigenesis, particularly in cell migration and tumor metastasis. However, its regulatory mechanisms remain elusive. In this study, we employed bioinformatic, gene regulation, and protein-DNA interaction screening to investigate the transcription factors (TFs) involved in regulating FNDC3B. Initially, 338 candidate TFs were selected based on previous chromatin immunoprecipitation (ChIP)-seq experiments available in public domain databases. Through TF knockdown screening and ChIP coupled with Droplet Digital PCR assays, we identified that E2F1 (E2F transcription factor 1) is crucial for the activation of FNDC3B. Overexpression or knockdown of E2F1 significantly impacts the expression of FNDC3B. In conclusion, our study elucidated the mechanistic link between FNDC3B and E2F1. These findings contribute to a better understanding of FNDC3B in tumorigenesis and provide insights into potential therapeutic targets for cancer treatment.

RNA m5C modification upregulates E2F1 expression in a manner dependent on YBX1 phase separation and promotes tumor progression in ovarian cancer.

5-Methylcytosine (m5C) is a common RNA modification that modulates gene expression at the posttranscriptional level, but the crosstalk between m5C RNA modification and biomolecule condensation, as well as transcription factor-mediated transcriptional regulation, in ovarian cancer, is poorly understood. In this study, we revealed that the RNA methyltransferase NSUN2 facilitates mRNA m5C modification and forms a positive feedback regulatory loop with the transcription factor E2F1 in ovarian cancer. Specifically, NSUN2 promotes m5C modification of E2F1 mRNA and increases its stability, and E2F1 binds to the NSUN2 promoter, subsequently reciprocally activating NSUN2 transcription. The RNA binding protein YBX1 functions as the m5C reader and is involved in NSUN2-mediated E2F1 regulation. m5C modification promotes YBX1 phase separation, which upregulates E2F1 expression. In ovarian cancer, NSUN2 and YBX1 are amplified and upregulated, and higher expression of NSUN2 and YBX1 predicts a worse prognosis for ovarian cancer patients. Moreover, E2F1 transcriptionally regulates the expression of the oncogenes MYBL2 and RAD54L, driving ovarian cancer progression. Thus, our study delineates a NSUN2-E2F1-NSUN2 loop regulated by m5C modification in a manner dependent on YBX1 phase separation, and this previously unidentified pathway could be a promising target for ovarian cancer treatment.

Blocking the E2F transcription factor 1/high-mobility group box 2 pathway enhances the intervention effects of α-santalol on the malignant behaviors of liver cancer cells.

In view of the tumor-inhibiting effect of α-santalol in various cancers and the role of E2F transcription factor 1 (E2F1) as an important target for anticancer research, this study investigates the relation between α-santalol and E2F1, as well as the effect of α-santalol on liver cancer progression and the corresponding mechanism. Concretely, liver cancer cells were treated with different concentrations of α-santalol. The IC50 value of α-santalol was determined using Probit regression analysis. Then, transcription factors that are targeted by α-santalol and differentially expressed in liver cancer were screened out. The clinicopathological impact of E2F1 and its targets were evaluated and predicted. The expressions of E2F1 and high-mobility group box 2 (HMGB2) and their correlation in the liver cancer tissues were analyzed by bioinformatics. The effects of E2F1 and HMGB2 on the biological characteristics of liver cancer cells were examined through loss/gain-of-function and molecular assays. With the extension of treatment time, the inhibitory effects of 10 µmol/L and 20 µmol/L α-santalol on cancer cell survival rate were enhanced (P < 0.001). E2F1 and HMGB2 were highly expressed and positively correlated in liver cancer tissues (P < 0.05). High E2F1 expression was correlated with large tumors and high TNM stages (P < 0.05). E2F1 knockdown promoted the effects of α-santalol on dose-dependently inhibiting viability, colony formation, invasion and migration (P < 0.05). Moreover, E2F1 knockdown reduced the IC50 value and HMGB2 level, while HMGB2 overexpression produced opposite effects. HMGB2 overexpression and E2F1 knockdown mutually counteracted their effects on the IC50 value and on the viability and apoptosis of α-santalol-treated liver cancer cells (P < 0.01). Collectively, blocking the E2F1/HMGB2 pathway enhances the intervention effects of α-santalol on the proliferation, migration and invasion of liver cancer cells.

Analysis of E2F1 single-nucleotide polymorphisms reveals deleterious non-synonymous substitutions that disrupt E2F1-RB protein interaction in cancer.

Cancer is a medical condition that is caused by the abnormal growth and division of cells, leading to the formation of tumors. The E2F1 and RB pathways are critical in regulating cell cycle, and their dysregulation can contribute to the development of cancer. In this study, we analyzed experimentally reported SNPs in E2F1 and assessed their effects on the binding affinity with RB. Out of 46, nine mutations were predicted as deleterious, and further analysis revealed four highly destabilizing mutations (L206W, R232C, I254T, A267T) that significantly altered the protein structure. Molecular docking of wild-type and mutant E2F1 with RB revealed a docking score of -242 kcal/mol for wild-type, while the mutant complexes had scores ranging from -217 to -220 kcal/mol. Molecular simulation analysis revealed variations in the dynamics features of both mutant and wild-type complexes due to the acquired mutations. Furthermore, the total binding free energy for the wild-type E2F1-RB complex was -64.89 kcal/mol, while those of the L206W, R232C, I254T, and A267T E2F1-RB mutants were -45.90 kcal/mol, -53.52 kcal/mol, -55.67 kcal/mol, and -61.22 kcal/mol, respectively. Our study is the first to extensively analyze E2F1 gene mutations and identifies candidate mutations for further validation and potential targeting for cancer therapeutics.

E2F1-EP300 co-activator complex potentiates immune escape in nasopharyngeal carcinoma through the mediation of MELK.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is characterized by a highly suppressive microenvironment that protects tumor cells against immune attack and facilitates tumor progression. MELK is upregulated in various tumors, whereas its function in the immune escape remains largely unknown. In this study, we investigated the role of MELK during immune escape in NPC. METHODS: Differentially expressed genes were filtered using GEO datasets and PPI network analysis. NPC cell colony formation and motility were examined, and the impact of CD8⁺ T cells on NPC cells was evaluated. A xenograft model was constructed to detect the growth of tumor cells and the T-cell phenotype of tumor infiltration. ChIP-qPCR and dual-luciferase assays were used to verify the transcriptional regulation of MELK by EP300/E2F1. FINDINGS: MELK was overexpressed in NPC, and sh-MELK suppressed the clonogenic ability, migration, and invasion of NPC cells and promoted the killing effects of CD8⁺ T cells. These in vitro findings were reproduced in vivo. EP300 synergized E2F1 to regulate the transcription of MELK in NPC cells. Loss of EP300 or E2F1 reverted the malignant phenotype of NPC cells and promoted the immune effect of CD8⁺ T cells. MELK further suppressed the immune effect of CD8⁺ T cells in the presence of sh-E2F1. INTERPRETATION: EP300 coordinated with E2F1 to promote the transcription of MELK which promoted the growth of NPC cells and repressed the killing effect of CD8⁺ T cells. Blockage of MELK may be a potential way to suppress the immune escape of NPC cells.

NEIL3 promotes cell proliferation of ccRCC via the cyclin D1-Rb-E2F1 feedback loop regulation.

Nei endonuclease VIII-like 3 (NEIL3), a novel tumor-related gene, is differentially expressed and involved in pathophysiological processes in multiple tumors. However, the potential biological functions and molecular mechanisms of NEIL3 in human clear cell renal cell carcinoma (ccRCC) have not been identified. In this research, we demonstrated that NEIL3, transcriptionally activated by E2F1, served as an oncogene to facilitate cell proliferation and cell cycle progression and contribute to tumorigenesis via the cyclin D1-Rb-E2F1 feedback loop in ccRCC. First, we found that NEIL3 expression was upregulated in ccRCC tissues and cell lines compared with matched adjacent nontumor tissues and renal tubular epithelial cells and was also positively correlated with adverse clinicopathological characteristics, such as advanced cancer stages and higher tumor grades, and acted as an independent prognostic marker in ccRCC. Mechanistically, we demonstrated that NEIL3 promoted cell proliferation, DNA replication and cell cycle progression in vitro and tumor growth in vivo. Furthermore, we found that NEIL3 overexpression activated the cyclin D1-Rb-E2F1 pathway, and the E2F1 upregulation transcriptionally activated NEIL3 expression, thus forming a feedback loop. In addition, there was a positive correlation between NEIL3 and E2F1 expression in clinical specimens of ccRCC. Taken together, our results suggest that NEIL3 serves as a proto-oncogene in ccRCC and presents as a novel candidate for ccRCC diagnosis and treatment.