Increased metastasis with loss of E2F2 in Myc-driven tumors

Comprehensive review regarding the association of E2Fs with the prognosis and immune infiltrates in human head and neck squamous cell carcinoma

E2F transcription factors (E2Fs) are a group of genes that encode a family of transcription factors. They have been identified as being involved in the tumor progression of various cancer types. However, little is known about the expression level, genetic variation, molecular mechanism, and prognostic value and immune infiltration of different E2Fs in HNSCC.In this study, we utilized multiple databases to investigate the mRNA expression level, genetic alteration, and biological function of E2Fs in HNSCC patients. Then, the relationship between E2Fs expression and its association with the occurrence, progress, prognosis, and immune cell infiltration in patients with HNSCC was evaluated. We found that all eight E2Fs were higher expressed in HNSCC tissues than in normal tissues, and the expression levels of E2F1/2/3/4/5/6/8 were also associated with the stage and grade of HNSCC. The abnormal expression of E2F1/2/4/8 in HNSCC patients is related to the clinical outcome. The expression of E2Fs was statistically correlated with the immune cell infiltration in HNSCC and the infiltration of B cells and CD8+ T cells were positively associated with better OS in HNSCC patients. Furthermore, we verified the E2F2 at the tissue level in the validation experiment. Our study may provide novel insights into the choice of immunotherapy targets and potential prognostic biomarkers in HNSCC patients.

Manipulating PTPRD function with ectodomain antibodies

Protein tyrosine phosphatases (PTPs) are critical regulators of signal transduction but have yet to be exploited fully for drug development. Receptor protein tyrosine phosphatase δ (RPTPδ/PTPRD) has been shown to elicit tumor-promoting functions, including elevating SRC activity and promoting metastasis in certain cell contexts. Dimerization has been implicated in the inhibition of receptor protein tyrosine phosphatases (RPTPs). We have generated antibodies targeting PTPRD ectodomains with the goal of manipulating their dimerization status ectopically, thereby regulating intracellular signaling. We have validated antibody binding to endogenous PTPRD in a metastatic breast cancer cell line, CAL51, and demonstrated that a monoclonal antibody, RD-43, inhibited phosphatase activity and induced the degradation of PTPRD. Similar effects were observed following chemically induced dimerization of its phosphatase domain. Mechanistically, RD-43 triggered the formation of PTPRD dimers in which the phosphatase activity was impaired. Subsequently, the mAb-PTPRD dimer complex was degraded through lysosomal and proteasomal pathways, independently of secretase cleavage. Consequently, treatment with RD-43 inhibited SRC signaling and suppressed PTPRD-dependent cell invasion. Together, these findings demonstrate that manipulating RPTP function via antibodies to the extracellular segments has therapeutic potential.

E2F2 serves as an essential prognostic biomarker and therapeutic target for human renal cell carcinoma by presenting "E2F2/miR-16-5p/SPTLC1" schema

BACKGROUND

Renal cell carcinoma (RCC) is a common malignant tumor of the urinary system with high mortality and morbidity. Although E2F2, a classical transcription factor implicated in cell cycle, has been shown to foster tumorigenesis in several human cancers, it could not draw a satisfy answer referring to precise downstream signaling axis in RCC development yet.

METHODS

Based on the publicly available data from TCGA database, expression patterns of E2F2, SPTLC1 and miR-16-5p were identified, either with the ability to predict the prognosis of patients with RCC, which was further validated in 38 paired RCC tissues and matched adjacent tissues by RT-qPCR and Western blot, respectively. Their cellular biofunctions were evaluated using MTT, EdU, Colony formation and transwell assays. Chromatin immunoprecipitation (ChIP) and luciferase reporter assay were employed to certain the exquisite core transcription regulatory circuitry of E2F2/miR-16-5p/SPTLC1 in RCC progression, which was also determined in xenograft tumor model.

RESULTS

Consistent with the public TCGA database, E2F2 was significantly increased in RCC tissues and cells, indicating shorter overall survival. Mechanistically, E2F2 served as a transcriptional activator of miR-16-5p, thus accounting for its negative regulation on SPTLC1 expression. E2F2 knockdown-mediated suppressive biofunctions on RCC cells were rescued by miR-16-5p mimics, while this effect was abolished again by SPTLC1 overexpression. Role of E2F2 on RCC tumorigenesis via the miR-16-5p/SPTLC1 axis was verified both in vitro and in vivo.

CONCLUSION

E2F2 promoted RCC progression via the miR-16-5p/SPTLC1 axis, which may represent a novel prognostic and therapeutic biomarker for RCC.

Silencing TRAIP suppresses cell proliferation and migration/invasion of triple negative breast cancer via RB-E2F signaling and EMT

TRAIP, as a 53 kDa E3 ubiquitin protein ligase, is involved in various cellular processes and closely related to the occurrence and development of tumors. At present, few studies on the relationship between TRAIP and triple negative breast cancer (TNBC) were reported. Bioinformatic analysis and Western blot, immunohistochemistry (IHC), CCK-8, colony formation, flow cytometry, wound healing, Transwell, and dual-luciferase reporter assays were performed, and xenograft mouse models were established to explore the role of TRAIP in TNBC. This study showed that the expression of TRAIP protein was upregulated in TNBC tissues and cell lines. Silencing of TRAIP significantly inhibited the proliferation, migration, and invasion of TNBC cells, whereas opposite results were observed in the TRAIP overexpression. In addition, TRAIP regulated cell proliferation, migration, and invasion through RB-E2F signaling and epithelial mesenchymal transformation (EMT). MiR-590-3p directly targeted the TRAIP 3'-UTR, and its expression were lower in TNBC tissues. Its mimic significantly downregulated the expression of TRAIP and subsequently suppressed cell proliferation, migration, and invasion. Rescue experiments indicated that TRAIP silencing reversed the promotion of miR-590-3p inhibitor on cell proliferation, migration, and invasion. TRAIP overexpression could also reverse the inhibition of miR-590-3p mimic on tumorigenesis. Finally, TRAIP knockdown significantly inhibited tumor growth and metastasis in animal experiments. In conclusion, TRAIP is an oncogene that influences the proliferation, migration, and invasion of TNBC cells through RB-E2F signaling and EMT. Therefore, TRAIP may be a potential therapeutic target for TNBC.

Prognostic Values of E2F1/2 Transcriptional Expressions in Chromophobe Renal Cell Carcinoma Patients: Evidence from Bioinformatics Analysis

Background

Numerous studies on the E2F transcription factors have led to increasing insights that E2Fs could be an important driver of the formation and progression of many human cancers. Little is known about the function of distinct E2Fs in chromophobe renal cell carcinoma (chRCC).

Methods

We utilized the UALCAN, GEPIA, Cancer Genome Atlas (TCGA) database, cBioPortal, Metascape, STRING, Cytoscape, GeneMANIA, TIMER, TISIDB, GSCALite, and MEXPRESS databases to investigate the transcription level, genetic alteration, methylation, and biological function of E2Fs in chRCC patients, and its association with the occurrence, progress, prognosis, and immune cell infiltration in patients with chRCC.

Results

We found that E2F1/2/4/7/8 were more expressed in chRCC tissues than in normal tissues, while the expression of E2F5/6 was lower in the former than in the latter, and the expression levels of E2F1/2/4/5/6//7/8 were also associated with the histological parameters of chRCC, including T-stage and N-stage. Higher expression of E2F1/2/7/8 was found to be significantly correlated with worse overall survival (OS) in chRCC patients. Cox regression and time-dependent ROC analysis further suggested that E2F1/2 could be the potential independent biomarkers for chRCC prognosis. Besides, a moderate mutation rate of E2Fs (34%) was noticed in chRCC, and the genetic mutations in E2Fs were associated with poor survival of chRCC patients. We noticed that the expression of E2Fs was statistically correlated with the immune cell infiltration in chRCC. Moreover, we also found that the expression of E2F1 was significantly correlated with tumor-infiltrating lymphocytes and immunomodulators, E2F7 expression was associated with MHC molecules, and the expression of E2F1/8 was correlated to their methylation levels.

Conclusion

Our results provide novel insights for selecting the prognostic biomarkers for chRCC and suggest that E2F1/2 could act as potential prognostic biomarkers for the survival of chRCC patients. However, more in-depth experiments are required to identify the underlying mechanisms and verify the clinical value of E2F1/2 in the prognosis of chRCC.

Mechanisms of circular RNA circ_0066147 on pancreatic cancer progression

Background

The purpose of the study was to explore the precise parts of circ_0066147 (circular RNA [circRNA] scm-like with four mbt domains 1, circSFMBT1) in pancreatic cancer (PC) progression.

Methods

Ribonuclease R assay was used to confirm the stability of circ_0066147. circ_0066147, miR-326 and E2F transcription factor 2 (E2F2) expression levels was detected by quantitative reverse-transcription polymerase chain reaction or Western blot. Cell proliferation, apoptosis, migration and invasion abilities were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, flow cytometry, wound-healing and transwell assays, respectively. Targeted relationships among circ_0066147, miR-326 and E2F2 were verified by the dual-luciferase reporter or RNA pull-down assay.

Results

circ_0066147 expression was upregulated in PC tissues and cells. circ_0066147 knockdown inhibited PC cell proliferation, migration, invasion and enhanced apoptosis in vitro, as well as weakened tumor growth in vivo. Mechanistically, circ_0066147 directly targeted miR-326 and circ_0066147 modulated E2F2 expression by miR-326. miR-326 mediated the regulation of circ_0066147 in PC cell behaviors in vitro. Furthermore, E2F2 was a functional target of miR-326 in modulating PC cell behaviors in vitro.

Conclusion

circ_0066147 regulated PC malignant progression in part depending on the miR-326/E2F2 axis, illuminating circ_0066147 was a potential prognostic marker and therapeutic target for PC management.

Transcriptional E2F1/2/3/6 as potential prognostic biomarkers in cutaneous melanoma

Although the abnormal expression of members of the E2F family has been reported to participate in carcinogenesis in many human types of cancer, the bioinformatics role of the E2F family in melanoma is unknown. This research was designed to detect the expression, methylation, prognostic value and potential effects of the E2F family in melanoma. We investigated E2F family mRNA expression from the Oncomine and GEPIA databases and their methylation status in the MethHC database. Meanwhile, we detected the relative E2F family expression levels by qPCR and immunohistochemistry. Kaplan-Meier Plotter was used to draw survival analysis charts, and gene functional enrichment analyses were applied through cBioPortal database analysis. E2F1/2/3/4/5/6 mRNA and proteins were clearly upregulated in cutaneous melanoma patients, and high expression levels of E2F1/2/3/6 were statistically related to high methylation levels. Increased mRNA expression of E2F1/2/3/6 was related to lower overall survival rates (OS) and disease-free survival (DFS) in cutaneous melanoma cases. Meanwhile, E2F1/2/3/6 carried out these effects through regulating multiple signaling pathways, including the MAPK, PI3K-Akt and p53 signaling pathways. Taking together, our findings suggest that E2F1/2/3/6 could act as potential targets for precision therapy in cutaneous melanoma patients.

Low E2F2 activity is associated with high genomic instability and PARPi resistance

The E2F family, classically known for a central role in cell cycle, has a number of emerging roles in cancer including angiogenesis, metabolic reprogramming, metastasis and DNA repair. E2F1 specifically has been shown to be a critical mediator of DNA repair; however, little is known about DNA repair and other E2F family members. Here we present an integrative bioinformatic and high throughput drug screening study to define the role of E2F2 in maintaining genomic integrity in breast cancer. We utilized in vitro E2F2 ChIP-chip and over expression data to identify transcriptional targets of E2F2. This data was integrated with gene expression from E2F2 knockout tumors in an MMTV-Neu background. Finally, this data was compared to human datasets to identify conserved roles of E2F2 in human breast cancer through the TCGA breast cancer, Cancer Cell Line Encyclopedia, and CancerRx datasets. Through these methods we predict that E2F2 transcriptionally regulates mediators of DNA repair. Our gene expression data supports this hypothesis and low E2F2 activity is associated with a highly unstable tumor. In human breast cancer E2F2, status was also correlated with a patient's response to PARP inhibition therapy. Taken together this manuscript defines a novel role of E2F2 in cancer progression beyond cell cycle and could impact patient treatment.

Molecular subtyping and genomic profiling expand precision medicine in refractory metastatic triple-negative breast cancer: the FUTURE trial

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease, and molecular subtyping may result in improved diagnostic precision and targeted therapies. Our previous study classified TNBCs into four subtypes with putative therapeutic targets. Here, we conducted the FUTURE trial (ClinicalTrials.gov identifier: NCT03805399), a phase Ib/II subtyping-based and genomic biomarker-guided umbrella trial, to evaluate the efficacy of these targets. Patients with refractory metastatic TNBC were enrolled and stratified by TNBC subtypes and genomic biomarkers, and assigned to one of these seven arms: (A) pyrotinib with capecitabine, (B) androgen receptor inhibitor with CDK4/6 inhibitor, (C) anti PD-1 with nab-paclitaxel, (D) PARP inhibitor included, (E) and (F) anti-VEGFR included, or (G) mTOR inhibitor with nab-paclitaxel. The primary end point was the objective response rate (ORR). We enrolled 69 refractory metastatic TNBC patients with a median of three previous lines of therapy (range, 1–8). Objective response was achieved in 20 (29.0%, 95% confidence interval (CI): 18.7%–41.2%) of the 69 intention-to-treat (ITT) patients. Our results showed that immunotherapy (arm C), in particular, achieved the highest ORR (52.6%, 95% CI: 28.9%–75.6%) in the ITT population. Arm E demonstrated favorable ORR (26.1%, 95% CI: 10.2%–48.4% in the ITT population) but with more high grade (≥ 3) adverse events. Somatic mutations of TOP2A and CD8 immunohistochemical score may have the potential to predict immunotherapy response in the immunomodulatory subtype of TNBC. In conclusion, the phase Ib/II FUTURE trial suggested a new concept for TNBC treatment, demonstrating the clinical benefit of subtyping-based targeted therapy for refractory metastatic TNBC.

Cross-talk between myeloid-derived suppressor cells and Mucin1 in breast cancer vaccination: On the verge of a breakthrough

Although breast cancer is one of the leading troublesome cancers, the available therapeutic options have not fulfilled the desired outcomes. Immune-based therapy has gained special attention for breast cancer treatment. Although this approach is highly tolerable, its low response rate has rendered it as an undesirable approach. This review aims to describe the essential oncogenic pathways involved in breast cancer, elucidate the immunosuppression and oncogenic effect of Mucin1, and introduce myeloid-derived suppressor cells, which are the main culprits of anti-tumoral immune response attenuation. The various auto-inductive loops between Mucin1 and myeloid-derived suppressor cells are focal in the suppression of anti-tumoral immune responses in patients with breast cancer. These cross-talks between the Mucin1 and myeloid-derived suppressor cells can be the underlying causes of immunotherapy's impotence for patients with breast cancer. This approach can pave the road for the development of a potent vaccine for patients with breast cancer and is translated into clinical settings.

Role of E2Fs and mitotic regulators controlled by E2Fs in the epithelial to mesenchymal transition

The epithelial-to-mesenchymal transition (EMT) is a complex cellular process in which epithelial cells acquire mesenchymal properties. EMT occurs in three biological settings: development, wound healing and fibrosis, and tumor progression. Despite occurring in three independent biological settings, EMT signaling shares some molecular mechanisms that allow epithelial cells to de-differentiate and acquire mesenchymal characteristics that confer cells invasive and migratory capacity to distant sites. Here we summarize the molecular mechanism that delineates EMT and we will focus on the role of E2 promoter binding factors (E2Fs) in EMT during tumor progression. Since the E2Fs are presently undruggable due to their control in numerous pivotal cellular functions and due to the lack of selectivity against individual E2Fs, we will also discuss the role of three mitotic regulators and/or mitotic kinases controlled by the E2Fs (NEK2, Mps1/TTK, and SGO1) in EMT that can be useful as drug targets.

Impact statement

The study of the epithelial to mesenchymal transition (EMT) is an active area of research since it is one of the early intermediates to invasion and metastasis—a state of the cancer cells that ultimately kills many cancer patients. We will present in this review that besides their canonical roles as regulators of proliferation, unregulated expression of the E2F transcription factors may contribute to cancer initiation and progression to metastasis by signaling centrosome amplification, chromosome instability, and EMT. Since our discovery that the E2F activators control centrosome amplification and mitosis in cancer cells, we have identified centrosome and mitotic regulators that may represent actionable targets against EMT and metastasis in cancer cells. This is impactful to all of the cancer patients in which the Cdk/Rb/E2F pathway is deregulated, which has been estimated to be most cancer patients with solid tumors.

PTPRT and PTPRD Deleterious Mutations and Deletion Predict Bevacizumab Resistance in Metastatic Colorectal Cancer Patients

Background: Bevacizumab-based regimens are used as standard treatments for colorectal cancer. Unfortunately, there are no established predictive markers for bevacizumab response. Methods: Tumor samples from 36 metastatic colorectal cancer patients treated with bevacizumab plus chemotherapy were analyzed by next-generation sequencing of all coding exons of more than 400 genes. Single gene and signaling pathway analyses were performed to correlate genomic data with response. Results: Among the genes most frequently mutated in our cohort, only mutations in PTPRT, a phosphatase involved in JAK/STAT signaling, were associated with response status, with deleterious mutations being enriched in non-responders. Pathway analysis revealed that deleterious mutations in genes of the JAK/STAT pathway, namely in PTPRT and the related gene PTPRD, correlated with resistance. Mutations in RTK/PI3K/RAS, Wnt and TGFβ pathways did not associate with response. Lack of response was observed in all patients with deleterious mutations or copy number loss of PTPRT/PTPRD (n = 10), compared to only 30.8% (n = 8) of patients without such alterations (relative risk, 3.25; 95% CI, 1.83–5.79, p = 0.0003). Similarly, PTPRT/PTPRD deleterious alterations were associated with shorter progression-free survival, an association that was retained in multivariate analysis (HR, 3.33; 95% CI, 1.47–7.54; p = 0.0038). Conclusion: Deleterious alterations in PTPRT/PTPRD are potential biomarkers for bevacizumab resistance.

MiR-490-5p inhibits the metastasis of hepatocellular carcinoma by down-regulating E2F2 and ECT2

We intended to evaluate miR-490-5p expression in hepatocellular carcinoma (HCC) tissues and detect the potential targets of miR-490-5p. In vitro experiments were conducted to further investigate the biological function of miR-490-5p on HCC cell metastasis. We investigated the abnormally expressed miRNAs in HCC tissues, and the miR-490-5p expression level was detected by qRT-PCR. E2F2 and ECT2 were proved to be the potential targets of miR-490-5p by luciferase reporter assay. The expression levels of E2F2 and ECT2 were determined using Western blot. Transwell assay was used to analyse the impact of miR-490-5p on metastasis of HCC cells. Four high-expressed miRNAs, and seven low-expressed miRNAs, including miR-490-5p, were detected in HCC tissues. The expression level of miR-490-5p was connected with the tumor size, tumor node metastasis (TNM) stage, and survival ratio of HCC patients. E2F2 and ECT2 were the targets of miR-490-5p, and miR-490-5p inhibited HCC cell metastasis through down-regulating the expressions of E2F2 and ECT2. The over-expressed miR-490-5p could restrain the metastasis of HCC cells by down-regulating E2F2 and ECT2 expression levels.

Transcription factor compensation during mammary gland development in E2F knockout mice

The E2F transcription factors control key elements of development, including mammary gland branching morphogenesis, with several E2Fs playing essential roles. Additional prior data has demonstrated that loss of individual E2Fs can be compensated by other E2F family members, but this has not been tested in a mammary gland developmental context. Here we have explored the role of the E2Fs and their ability to functionally compensate for each other during mammary gland development. Using gene expression from terminal end buds and chromatin immunoprecipitation data for E2F1, E2F2 and E2F3, we noted both overlapping and unique mammary development genes regulated by each of the E2Fs. Based on our computational findings and the fact that E2Fs share a common binding motif, we hypothesized that E2F transcription factors would compensate for each other during mammary development and function. To test this hypothesis, we generated RNA from E2F1^-/-, E2F2^-/- and E2F3^+/- mouse mammary glands. QRT-PCR on mammary glands during pregnancy demonstrated increases in E2F2 and E2F3a in the E2F1^-/- mice and an increase in E2F2 levels in E2F3^+/- mice. During lactation we noted that E2F3b transcript levels were increased in the E2F2^-/- mice. Given that E2Fs have previously been noted to have the most striking effects on development during puberty, we hypothesized that loss of individual E2Fs would be compensated for at that time. Double mutant mice were generated and compared with the single knockouts. Loss of both E2F1 and E2F2 revealed a more striking phenotype than either knockout alone, indicating that E2F2 was compensating for E2F1 loss. Interestingly, while E2F2 was not able to functionally compensate for E2F3^+/- during mammary outgrowth, increased E2F2 expression was observed in E2F3^+/- mammary glands during pregnancy day 14.5 and lactation day 5. Together, these findings illustrate the specificity of E2F family members to compensate during development of the mammary gland.

Stat3 accelerates Myc induced tumor formation while reducing growth rate in a mouse model of breast cancer

Elevated Myc expression has been noted in basal breast cancer but therapies targeting Myc directly are lacking. It is therefore critical to characterize the interaction of Myc with other genes and pathways to uncover future potential therapeutic strategies. In this study, we bioinformatically predicted a role for Stat3 in Myc induced mammary tumors and tested it using mouse models. During normal mammary function, loss of Stat3 in Myc transgenic dams resulted in lethality of pups due to lactation deficiencies. We also observed that deletion of Stat3 in the mammary glands of MMTV-Myc mice unexpectedly resulted in increased and earlier hyperplasia and expedited tumorigenesis. However, despite arising earlier, Myc tumors lacking Stat3 grew more slowly with alterations in the resulting histological subtypes, including a dramatic increase in EMT-like tumors. We also observed that these tumors had impaired angiogenesis and a slight decrease in lung metastases. This metastatic finding is distinct from previously published findings in both MMTV-Neu and MMTV-PyMT mouse models. Together, the literature and our current research demonstrate that Stat3 can function as an oncogene or as a tumor repressor depending on the oncogenic driver and developmental context.

Epigenetic reader BRD4 inhibition as a therapeutic strategy to suppress E2F2-cell cycle regulation circuit in liver cancer

Deregulation of the epigenome component affects multiple pathways in the cancer phenotype since the epigenome acts at the pinnacle of the hierarchy of gene expression. Pioneering work over the past decades has highlighted that targeting enzymes or proteins involved in the epigenetic regulation is a valuable approach to cancer therapy. Very recent results demonstrated that inhibiting the epigenetic reader BRD4 has notable efficacy in diverse cancer types. We investigated the potential of BRD4 as a therapeutic target in liver malignancy. BRD4 was overexpressed in three different large cohort of hepatocellular carcinoma (HCC) patients as well as in liver cancer cell lines. BRD4 inhibition by JQ1 induced anti-tumorigenic effects including cell cycle arrest, cellular senescence, reduced wound healing capacity and soft agar colony formation in liver cancer cell lines. Notably, BRD4 inhibition caused MYC-independent large-scale gene expression changes in liver cancer cells. Serial gene expression analyses with SK-Hep1 liver cancer cells treated with JQ1 to delineate the key player of BRD4 inhibition identified E2F2 as the first line of downstream direct target of BRD4. Further experiments including chromatin immunoprecipitation (ChIP) assay and loss of function study confirmed E2F2 as key player of BRD4 inhibition. Overexpressed E2F2 is a crucial center of cell cycle regulation and high expression of E2F2 is significantly associated with poor prognosis of HCC patients. Our findings reveal BRD4-E2F2-cell cycle regulation as a novel molecular circuit in liver cancer and provide a therapeutic strategy and innovative insights for liver cancer therapies.

miR-99a reveals two novel oncogenic proteins E2F2 and EMR2 and represses stemness in lung cancer

Lung cancer is one of the most aggressive tumours with very low life expectancy. Altered microRNA expression is found in human tumours because it is involved in tumour growth, progression and metastasis. In this study, we analysed microRNA expression in 47 lung cancer biopsies. Among the most downregulated microRNAs we focussed on the miR-99a characterisation. In vitro experiments showed that miR-99a expression decreases the proliferation of H1650, H1975 and H1299 lung cancer cells causing cell cycle arrest and apoptosis. We identified two novel proteins, E2F2 (E2F transcription factor 2) and EMR2 (EGF-like module-containing, mucin-like, hormone receptor-like 2), downregulated by miR-99a by its direct binding to their 3′-UTR. Moreover, miR-99a expression prevented cancer cell epithelial-to-mesenchymal transition (EMT) and repressed the tumourigenic potential of the cancer stem cell (CSC) population in both these cell lines and mice tumours originated from H1975 cells. The expression of E2F2 and EMR2 at protein level was studied in 119 lung cancer biopsies. E2F2 and EMR2 are preferentially expressed in adenocarcinomas subtypes versus other tumour types (squamous and others). Interestingly, the expression of E2F2 correlates with the presence of vimentin and both E2F2 and EMR2 correlate with the presence of β-catenin. Moreover, miR-99a expression correlates inversely with E2F2 and directly with β-catenin expression in lung cancer biopsies. In conclusion, miR-99a reveals two novel targets E2F2 and EMR2 that play a key role in lung tumourigenesis. By inhibiting E2F2 and EMR2, miR-99a represses in vivo the transition of epithelial cells through an EMT process concomitantly with the inhibition of stemness features and consequently decreasing the CSC population.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

Clinical performance of E2Fs 1-3 in kidney clear cell renal cancer, evidence from bioinformatics analysis

Extensive research on the E2F transcription factor family has led to numerous insights that E2Fs were involved not only in proliferation and tumorigenesis but also in apoptosis and differentiation. In the present study, we analyzed the differential expression of E2Fs1-3 genes, and also evaluated the impact of E2Fs 1-3 genes expression on clinical outcome from the Cancer Genome Atlas (TCGA) database. The results showed that E2F1, E2F2 and E2F3 expression was increased in KIRC tissues than matched normal tissues (E2F1, P < 0.001; E2F2, P < 0.001, E2F3, P = 0.001), respectively. E2F1, E2F2 and E2F3 were significantly different in metastasis status, lymph node status, stage, and T stage in KIRC patients (all P < 0.01). E2F1 and E2F2 had the sensitivity of 96.1% and 93.1% and the specificity of 87.2% and 91.7% in discriminating KIRC from normal controls. High E2F1, E2F2 and E2F3 expression were correlated to worsen overall survival (all P < 0.01), and high E2F3 expression had worse disease free survival (P = 0.0404). Multivariate Cox regression analysis revealed that E2F1 and E2F3 were independent prognostic factors for overall survival. Taken together, E2F1 and E2F2 may serve as valuable diagnostic markers for KIRC. Moreover, E2F1, E2F2 and E2F3 could provide valuable prognostic information for KIRC patients.

Mouse Models of Breast Cancer Share Amplification and Deletion Events with Human Breast Cancer

Breast tumor heterogeneity has been well documented through the use of multiplatform -omic studies in human tumors. However, there is no integrative database to capture the heterogeneity within mouse models of breast cancer. This project identifies genomic copy number alterations (CNAs) in 600 tumors across 27 major mouse models of breast cancer through the application of a predictive algorithm to publicly available gene expression data. It was found that despite the presence of strong oncogenic drivers in most mouse models, CNAs are extremely common but heterogeneous both between models and within models. Many mouse CNA events are largely conserved in human tumors and in the mouse we show that they are associated with secondary tumor characteristics such as tumor histology, metastasis, as well as enhanced oncogenic signaling. These data serve as an important resource in guiding investigators when choosing a mouse model to understand the gene copy number changes relevant to human breast cancer.

Targeting the RB-E2F pathway in breast cancer

Mutations of the retinoblastoma tumor-suppressor gene (RB1) or components regulating the CDK-RB-E2F pathway have been identified in nearly every human malignancy. Re-establishing cell cycle control through cyclin-dependent kinase (CDK) inhibition has therefore emerged as an attractive option in the development of targeted cancer therapy. The most successful example of this today is the use of the CDK4/6 inhibitor palbociclib combined with aromatase inhibitors for the treatment of estrogen receptor-positive breast cancers. Multiple studies have demonstrated that the CDK-RB-E2F pathway is critical for the control of cell proliferation. More recently, studies have highlighted additional roles of this pathway, especially E2F transcription factors themselves, in tumor progression, angiogenesis and metastasis. Specific E2Fs also have prognostic value in breast cancer, independent of clinical parameters. We discuss here recent advances in understanding of the RB-E2F pathway in breast cancer. We also discuss the application of genome-wide genetic screening efforts to gain insight into synthetic lethal interactions of CDK4/6 inhibitors in breast cancer for the development of more effective combination therapies.

Downregulated miR-31 level associates with poor prognosis of gastric cancer and its restoration suppresses tumor cell malignant phenotypes by inhibiting E2F2

The miRNA microarray analysis showed that miR-31 was reduced in gastric cancer. This study further assessed miR-31 expression and role of miR-31 in gastric cancer tissues and cell lines. The data showed that miR-31 expression was down-regulated in 40 cases of gastric cancer tissues compared to the adjacent normal tissues, and low expression of miR-31 was associated with poor tumor differentiation, lymph node metastasis, advanced T stage and worse overall survival of gastric cancer patients. Ectopic expression of miR-31 reduced tumor cell viability, enhanced apoptosis, arrested tumor cells at G1 transition, and reduced tumor cell migration and invasion in SGC-7901 and MGC-803 gastric cell lines in vitro. Enforced expression of miR-31 also inhibited growth of engrafted tumors in vivo. Luciferase reporter assays and western blot revealed that E2F2 is the direct target of miR-31. E2F2 expression was upregulated in gastric cancer tissues, and inversely associated with miR-31 levels, while knockdown of E2F2 expression mimicked miR-31 anti-tumor activity in gastric cancer cells, but the ectopic expression of E2F2 rescued the miR-31-mediated inhibition in gastric cell lines. Taken together, these results demonstrated that miR-31 acts as a crucial tumor suppressive activity by inhibiting E2F2s expression. Thus, miR-31 might be a candidate therapeutic target for gastric cancer patients.