KDM5D inhibits the transcriptional activation of FKBP4 by suppressing the expression of E2F1 in colorectal cancer in males.

Colorectal cancer (CRC) remains the most frequently diagnosed malignancy and also a major contributor to cancer-related death throughout the world. Here, we first revealed the role of histone lysine-specific demethylase 5D (KDM5D) in CRC in males. KDM5D expression in tumor and adjacent tissues of male CRC patients was investigated using immunohistochemistry and RT-qPCR, and the correlation between its expression and patients' prognosis was analyzed. Downregulation of KDM5D in CRC patients was associated with poor prognoses. Overexpression of KDM5D significantly inhibited the growth and metastasis of CRC in vitro and in vivo. The downstream mechanism of KDM5D in CRC was investigated using bioinformatics analysis, and the regulatory relationship was confirmed by ChIP-qPCR and luciferase reporter assays. KDM5D suppressed E2F1 expression by mediating H3K4me3 demethylation. E2F1, highly expressed in CRC, promoted the expression of FKBP4 at the transcriptional level by binding to the FKBP4 promoter. Finally, rescue experiments revealed that overexpression of FKBP4 significantly reversed the inhibitory effect of KDM5D on CRC growth and metastasis. Collectively, KDM5D exerted an anti-tumor and anti-metastatic in CRC through demethylation in E2F1 and suppression of FKBP4 transcription, which might represent a novel target in CRC treatment in male.

Downregulation of miR-326 and its host gene ß-arrestin1 induces pro-survival activity of E2F1 and promotes medulloblastoma growth.

Persistent mortality rates of medulloblastoma (MB) and severe side effects of the current therapies require the definition of the molecular mechanisms that contribute to tumor progression. Using cultured MB cancer stem cells and xenograft tumors generated in mice, we show that low expression of miR-326 and its host gene ß-arrestin1 (ARRB1) promotes tumor growth enhancing the E2F1 pro-survival function. Our models revealed that miR-326 and ARRB1 are controlled by a bivalent domain, since the H3K27me3 repressive mark is found at their regulatory region together with the activation-associated H3K4me3 mark. High levels of EZH2, a feature of MB, are responsible for the presence of H3K27me3. Ectopic expression of miR-326 and ARRB1 provides hints into how their low levels regulate E2F1 activity. MiR-326 targets E2F1 mRNA, thereby reducing its protein levels; ARRB1, triggering E2F1 acetylation, reverses its function into pro-apoptotic activity. Similar to miR-326 and ARRB1 overexpression, we also show that EZH2 inhibition restores miR-326/ARRB1 expression, limiting E2F1 pro-proliferative activity. Our results reveal a new regulatory molecular axis critical for MB progression.

IL-6-induced acetylation of E2F1 aggravates oxidative damage of retinal pigment epithelial cell line.

Oxidative damage in retinal pigment epithelial cells (RPE) is considered to be a crucial pathogenesis of age-related macular degeneration (AMD). Although dysregulation of the DNA repair system has been found in RPE cells of AMD patients, the detailed molecular mechanisms of this dysregulation and their relationship with the intraocular microenvironment of AMD patients remain unclear. Here, we established an RPE model of H2O2-induced oxidative stress and found that Sirtuin 1 (Sirt1)-mediated deacetylation of E2F transcription factor 1 (E2F1) was required for oxidation resistance in RPE cells. Moreover, E2F1 induced the expression of the chromatin-binding protein, high mobility group AT-Hook 1 (HMGA1), which promoted the transcription of glucose 6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the pentose phosphate pathway, to increase NADPH level for antioxidant defense. Interrupting the E2F1/HMGA1/G6PD regulatory axis increased reactive oxygen species (ROS) levels, DNA damage, and apoptosis in RPE cells under oxidative stress. Notably, interleukin 6 (IL-6), an inflammatory cytokine that is known to be upregulated in the intraocular fluid of AMD patients, induced phosphorylation (S47) of Sirt1 by activating PI3K/AKT/mTOR signaling, thereby inhibiting Sirt1 activity and increasing the acetylation of E2F1. Specific inhibitors of PI3K/AKT/mTOR signaling decreased DNA damage and ROS while increasing NADPH in RPE cells. Collectively, our findings demonstrate that IL-6-induced acetylation of E2F1 impairs the antioxidant capacity of RPE cells by disturbing the pentose phosphate pathway, which elucidates a relationship between the intraocular microenvironment and RPE oxidative damage in AMD and provides a possible therapeutic target for AMD.

Effects of oxymatrine on the proliferation of human liver cancer Bel-7404 cells: A protocol of systematic review and meta-analysis.

BACKGROUND: This study will examine the effects of oxymatrine on the proliferation of human liver cancer Bel-7404 cells (HLCBC). METHODS: This study will search electronic bibliographic databases available in PUBMED, EMBASE, Cochrane Library, Scopus, Cumulative Index to Nursing and Allied Health Literature, China Biology Medicine, and China National Knowledge Infrastructure. We attempt to search case-controlled studies (CCSs) or randomized controlled studies (RCSs) pertaining to HLCBC from their inception to the February 29, 2020 without limitations of language and publication time. We will include any CCSs or RCSs on exploring oxymatrine on the proliferation of HLCBC. We will assess the methodological quality of CCSs by Newcastle-Ottawa Scale, and RCSs by Cochrane risk of bias tool. Review Manager 5.3 software will be utilized for statistical analysis. RESULTS: The current study will summarize most recent eligible studies to investigate the effects of oxymatrine on the proliferation of HLCBC. CONCLUSION: Its results may provide reliable scientific evidence on effects of oxymatrine on the proliferation of HLCBC. SYSTEMATIC REVIEW REGISTRATION: INPLASY202040026.

Context-Dependent Functions of E2F1: Cell Cycle, Cell Death, and DNA Damage Repair in Cortical Neurons.

DNA damage has been reported to induce cell cycle-related neuronal death. This is significant as aberrant cell cycle re-entry of mature, post-mitotic neurons contributes to neurodegeneration. In this study, we investigate how DNA damage elicited by exposure to the topoisomerase I inhibitor camptothecin (CPT) leads to cycle-related death of cultured cortical neurons and examine the function of E2F1 in this process. CPT treatment induced cell cycle initiation of cortical neurons and elevated the expression of certain cell cycle components (e.g., cyclin D1, CDK4, E2F1) but failed to drive S phase entry or DNA synthesis. The arrest in the cell cycle is explained by the elevated expression of the CDK inhibitor p21Cip1. Though its level was increased after CPT treatment, E2F1 did not drive treated neurons into the G1-S phase transition. E2F1 overexpression led to cell cycle activation and acute neuronal apoptosis without detectable entry of the neurons into S phase. ChIPseq analysis demonstrated that E2F1 predominantly occupies positions on or near the promoters of cell cycle related genes. Instead, in CPT-treated neurons, E2F1 preferentially regulated DNA repair related genes. Our study reveals that the functions of E2F1 in postmitotic neurons are context-dependent and offers novel insights into the role of E2F1 in DNA damage induced cycle-related neuronal death.

Protein expression profiles and prognostic value of E2F family members in clear cell renal cell carcinoma.

The derangement of the cell cycle facilitates uncontrolled cell proliferation and acquisition of genetic alterations favorable for malignancy. However, the protein expression profiles of E2 F family cell cycle regulators in clear cell renal cell carcinoma (ccRCC) have not yet been thoroughly investigated. In this study, we aimed to examine the protein expression profiles and prognostic value of E2 F1, E2 F3, and E2 F4 in ccRCC cases. The immunohistochemical expression of E2 F1, E2 F3, and E2 F4 was quantitatively scored in 180 ccRCC tumor tissues and 79 normal kidney tissues. The prognostic implications of these E2 F members were determined. We found that ccRCC tumor cells showed higher nuclear expression of E2 F1, E2 F3 and E2 F4 than normal kidney samples. High E2 F1 and E2 F3 expression in tumor cells was associated with poor prognostic factors of ccRCC, whereas high E2 F4 correlated with beneficial prognostic factors. High expression of E2 F1 and E2 F3 in tumor cells was correlated with a poor overall and recurrence-free survival, while high E2 F4 expression did not. In conclusion, E2 F1, E2 F3 and E2 F4 may function as oncogenes during tumorigenesis of ccRCC, although they contribute to the progression of ccRCC in different ways. Additional studies are required to clarify the conflicting role of E2 F4 in the tumor evolution of ccRCC.

Long noncoding RNA DLX6-AS1 accelerates the glioma carcinogenesis by competing endogenous sponging miR-197-5p to relieve E2F1.

Long noncoding RNAs (lncRNAs) participate in numerous of human cancer tumorigenesis. Nevertheless, the in-depth molecular mechanism that lncRNAs regulate the gliomagenesis is still ambiguous. In this research, our study invests energy in the biologic roles of lncRNA DLX6-AS1 on the glioma tumorigenesis. Here, we demonstrated that DLX6-AS1 expression was both high-expressed in the glioma cells and tissue, and the overexpression of DLX6-AS1 was clinically correlated with the poor outcome of glioma patients. In the cellular functional assays, silenced DLX6-AS1 expression by siRNAs inhibited the proliferation, invasion and tumor growth in vitro and in vivo, while the enhanced DLX6-AS1 expression by plasmids promotes them. The bioinformatics predictive tools, luciferase reporter assay and correlation analysis found that miR-197-5p could both target the 3'-UTR of DLX6-AS1 as well as E2F1 gene, constructing DLX6-AS1-miR-197-5p-E2F1 axis. Moreover, receiver operating characteristic (ROC) curve analysis revealed that lncRNA DLX6-AS1 has valuable diagnostic value clinical diagnose for the glioma patients (AUC = 0.736). Overall, our finding supports that DLX6-AS1 accelerates the glioma carcinogenesis by competing endogenous sponging miR-197-5p to relieve E2F1, acting as a novel therapeutic target for glioma.

Juvenile hormone promotes locust fat body cell polyploidization and vitellogenesis by activating the transcription of Cdk6 and E2f1.

Juvenile hormone (JH) is known to promote cell polyploidization for insect vitellogenesis and egg production, but the underlying mechanisms remain poorly understood. Using the migratory locust Locusta migratoria as a model system, we report here that the expression of cyclin-dependent kinase 6 (Cdk6) and adenovirus E2 factor-1 (E2f1), the core mediators in cell cycle progression is regulated by JH and its receptor Methoprene-tolerant (Met). JH acts through its receptor complex comprised of Met and Taiman to directly activate the transcription of Cdk6 and E2f1. Depletion of Cdk6 or E2f1 results in significantly decreased ploidy, precocious mitotic entry and increased cell numbers in the fat body, accompanied by substantial reduction of Vitellogenin gene expression, blocked ovarian growth and arrested oocyte maturation. These findings indicate a crucial role of Cdk6 and E2f1 in JH-regulated polyploidization and vitellogenesis as well as a novel regulatory machinery for endocycling in insects.

EZH2 is upregulated in the proliferation centers of CLL/SLL lymph nodes.

Lymph node involvement of chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) is characterised by the diffuse infiltration of small neoplastic lymphocytes, which is accompanied by the presence of proliferation centres (PCs) comprising prolymphocytes and paraimmunoblasts. There is increasing evidence of accumulation of various molecular alterations in the tumour cells of PCs, which may explain why extended PCs are related to a less favourable prognosis. To further characterize PCs, we compared the expression level of EZH2 protein, the overexpression of which has recently been recognized as poor prognostic factor in CLL/SLL, in the PCs and the intervening small cell areas in lymph nodes of 15 patients with CLL/SLL. We also investigated the mutational profile of EZH2 and the expression of its upstream regulators c-Myc, E2F1, pRB and miR-26a. Our results showed a significantly increased expression of EZH2 in the PCs. No EZH2 mutations were detected, however, overexpression of c-Myc, E2F1 and pRb proteins as well as reduced expression of the tumor suppressor miR-26a were demonstrated in the PCs. In summary our findings indicate that EZH2 pathway is significantly upregulated in the PCs of CLL/SLL lymph nodes, providing further evidence for the distinguished biological features of the PCs.

hsa-mir183/EGR1-mediated regulation of E2F1 is required for CML stem/progenitor cell survival.

Chronic myeloid leukemia (CML) stem/progenitor cells (SPCs) express a transcriptional program characteristic of proliferation, yet can achieve and maintain quiescence. Understanding the mechanisms by which leukemic SPCs maintain quiescence will help to clarify how they persist during long-term targeted treatment. We have identified a novel BCR-ABL1 protein kinase-dependent pathway mediated by the upregulation of hsa-mir183, the downregulation of its direct target early growth response 1 (EGR1), and, as a consequence, upregulation of E2F1. We show here that inhibition of hsa-mir183 reduced proliferation and impaired colony formation of CML SPCs. Downstream of this, inhibition of E2F1 also reduced proliferation of CML SPCs, leading to p53-mediated apoptosis. In addition, we demonstrate that E2F1 plays a pivotal role in regulating CML SPC proliferation status. Thus, for the first time, we highlight the mechanism of hsa-mir183/EGR1-mediated E2F1 regulation and demonstrate this axis as a novel, critical factor for CML SPC survival, offering new insights into leukemic stem cell eradication.

MiR-205-5p and miR-342-3p cooperate in the repression of the E2F1 transcription factor in the context of anticancer chemotherapy resistance.

High rates of lethal outcome in tumour metastasis are associated with the acquisition of invasiveness and chemoresistance. Several clinical studies indicate that E2F1 overexpression across high-grade tumours culminates in unfavourable prognosis and chemoresistance in patients. Thus, fine-tuning the expression of E2F1 could be a promising approach for treating patients showing chemoresistance. Methods: We integrated bioinformatics, structural and kinetic modelling, and experiments to study cooperative regulation of E2F1 by microRNA (miRNA) pairs in the context of anticancer chemotherapy resistance. Results: We showed that an enhanced E2F1 repression efficiency can be achieved in chemoresistant tumour cells through two cooperating miRNAs. Sequence and structural information were used to identify potential miRNA pairs that can form tertiary structures with E2F1 mRNA. We then employed molecular dynamics simulations to show that among the identified triplexes, miR-205-5p and miR-342-3p can form the most stable triplex with E2F1 mRNA. A mathematical model simulating the E2F1 regulation by the cooperative miRNAs predicted enhanced E2F1 repression, a feature that was verified by in vitro experiments. Finally, we integrated this cooperative miRNA regulation into a more comprehensive network to account for E2F1-related chemoresistance in tumour cells. The network model simulations and experimental data indicate the ability of enhanced expression of both miR-205-5p and miR-342-3p to decrease tumour chemoresistance by cooperatively repressing E2F1. Conclusions: Our results suggest that pairs of cooperating miRNAs could be used as potential RNA therapeutics to reduce E2F1-related chemoresistance.

E2F1 silencing inhibits migration and invasion of osteosarcoma cells via regulating DDR1 expression.

In the present study, knockdown of E2F1 impaired the migration and invasion of osteosarcoma cells. Further analysis showed that E2F1 knockdown decreased the expression of discoidin domain receptor 1 (DDR1) which plays a crucial role in many fundamental processes such as cell differentiation, adhesion, migration and invasion. Luciferase and ChIP assays confirmed that E2F1 silencing attenuated the expression of DDR1 through disrupting E2F1-mediated transcription of DDR1 in osteosarcoma cells. Similarly with the effect of E2F1 silencing, DDR1 knockdown weakened the migratory and invasive capabilities of osteosarcoma cells; while overexpression of DDR1 resulted in a significant increase of cell motility and invasiveness, even after knocking down E2F1. Interestingly, inactivation of E2F1/DDR1 pathway by shRNA weakened STAT3 signaling and subsequently suppressed the epithelial-mesenchymal transition (EMT) of osteosarcoma cells, as shown with decreased vimentin, MMP2, MMP9, and increased E­cadherin. Consistently, high expressions of E2F1 and DDR1 observed in osteosarcoma tissues were related to TNM stage and metastasis. In addition, high level of E2F1 or DDR1 was associated with poor prognosis in osteosarcoma patients. These results suggest that E2F1/DDR1/STAT3 pathway is critical for malignancy of osteosarcoma, which may provide a novel prognostic indicator or approach for osteosarcoma therapy.

p53-Mediated oligodendrocyte apoptosis initiates demyelination after compressed spinal cord injury by enhancing ER-mitochondria interaction and E2F1 expression.

Oligodendrocyte apoptosis mediated demyelination is a pathological change characteristic of compressed spinal cord injury (CSCI). However, the mechanism of demyelination due to oligodendrocyte apoptosis is not known. In this study, after successfully establishing a rat CSCI model using a custom-made compressor, we investigated the pathological changes, MBP expression, as well as apoptosis-related protein (p53, active caspase-3) expression to determine whether or not apoptosis and demyelination occurred after injury. To understand the possible mechanism of oligodendrocyte apoptosis, caspase-12 and cytochrome C were analyzed to explore the relationship between oligodendrocyte apoptosis and endoplasmic reticulum(ER)-mitochondria interaction. The transcription factor, E2F1, was also detected by immunofluorescence and Western blot assays. The results showed that CSCI increased the expression levels of p53, E2F1 and active caspase-3 followed by the swelling and breakdown of myelin sheaths. The number of myelinated nerve fibers also decreased with down-regulated expression of MBP. Expression levels of caspase-12 and cytochrome C were enhanced along with a reduction in the number of oligodendrocytes. After treatment of CSCI in rats with Pifithrin-µ(PFT-µ), a specific inhibitor of p53, pathomorphological changes of myelin sheath improved significantly. Expression levels of E2F1, active caspase-3, caspase-12 and cytochrome C were down-regulated, consistent with reduced the number of apoptotic oligodendrocytes. These results demonstrated that over-expression of p53 could mediate oligodendrocyte apoptosis thus resulting in demyelination in two ways; by enhancing ER-mitochondria interaction and by triggering the E2F1 mediated apoptosis pathway.

KLF6 Suppresses Metastasis of Clear Cell Renal Cell Carcinoma via Transcriptional Repression of E2F1.

The transcription factor KLF6 has an essential role in the development and metastasis of multiple human cancers. Paradoxically, KLF6 expression was found to be attenuated in primary metastatic clear cell renal cell carcinoma (ccRCC), such that it is unclear how KLF6 affects malignant progression in this setting. In this study, we demonstrate that KLF6 attenuation in renal cells is sufficient to promote E2F1-mediated epithelial-mesenchymal transition and metastatic prowess. In a mouse xenograft model of human ccRCC, silencing KLF6 increased tumor cell proliferation and malignant character, whereas E2F1 silencing reversed these properties. These effects were corroborated in a metastatic model system, where we observed a greater number of pulmonary metastatic lesions formed by ccRCC cells where KLF6 was silenced and E2F1 enforced. Analysis of clinical specimens of ccRCC revealed that low levels of KLF6 and high levels of E2F1 correlated closely with ccRCC development. Overall, our results established the significance of activating the KLF6-E2F1 axis in aggressive ccRCC, defining a novel critical signaling mechanism that drives human ccRCC invasion and metastasis. Cancer Res; 77(2); 330-42. ©2016 AACR.

Expression and prognostic value of E2F activators in NSCLC and subtypes: a research based on bioinformatics analysis.

E2F activators (E2F1-3) codify a family of transcription factors (TFs) in higher eukaryotes. E2F activators are involved in the cell cycle regulation and synthesis of DNA in mammalian cells, and their overexpression has been detected in many human cancers. However, their clinical significance has not been deeply researched in non-small-cell lung cancer (NSCLC), and bioinformatics analysis has never been reported to explore their clinical role in NSCLC. In the current study, we investigated the expression and prognostic value of E2F activators in NSCLC patients through the "TCGA datasets" and the "Kaplan-Meier plotter" (KM plotter) database. Hazard ratio (HR), 95 % confidence intervals, and log-rank P were calculated. Compared with normal tissue samples, E2F activators were overexpressed in NSCLC tissues, in lung adenocarcinoma (LUAD) tissues, and in lung squamous cell carcinoma (LUSC) tissues. In NSCLC patients, E2F1 expression was significantly correlated with age, sex, and tumor stage. E2F2 expression was found to be significantly correlated with sex and tumor size. We further demonstrated that E2F1 and E2F2 overexpressions were significantly associated with poor prognosis. In LUAD patients, E2F1 expression was significantly correlated with tumor size and tumor stage. E2F2 expression was significantly correlated with lymph node status and tumor stage. E2F1 and E2F2 overexpression showed a significant association with poor prognosis, while E2F3 overexpression was significantly correlated to better prognosis. In LUSC patients, E2F1 was concluded to be significantly correlated with tumor stage. However, E2F activators were not found to be correlated to prognosis.

Functional Studies on Primary Tubular Epithelial Cells Indicate a Tumor Suppressor Role of SETD2 in Clear Cell Renal Cell Carcinoma.

SET domain-containing 2 (SETD2) is responsible for the trimethylation of histone H3 lysine36 (H3K36me3) and is one of the genes most frequently mutated in clear cell renal cell carcinoma (ccRCC). It is located at 3p21, one copy of which is lost in the majority of ccRCC tumors, suggesting that SETD2 might function as a tumor suppressor gene. However, the manner in which loss of SETD2 contributes to ccRCC development has not been studied in renal primary tubular epithelial cells (PTECs). Therefore, we studied the consequences of SETD2 knockdown through lentiviral shRNA in human PTECs. Consistent with its known function, SETD2 knockdown (SETD-KD) led to loss of H3K36me3 in PTECs. In contrast to SETD2 wild-type PTECs, which have a limited proliferation capacity; the SETD2-KD PTECs continued to proliferate. The expression profiles of SETD2-KD PTECs showed a large overlap with the expression profile of early-passage, proliferating PTECs, whereas nonproliferating PTECs showed a significantly different expression profile. Gene set enrichment analysis revealed a significant enrichment of E2F targets in SETD2-KD and proliferating PTECs as compared with nonproliferating PTECs and in proliferating PTEC compared with SETD2-KD. The SETD2-KD PTECs maintained low expression of CDKN2A and high expression of E2F1, whereas their levels changed with continuing passages in untreated PTECs. In contrast to the nonproliferating PTECs, SETD2-KD PTECs showed no ß-galactosidase staining, confirming the protection against senescence. Our results indicate that SETD2 inactivation enables PTECs to bypass the senescence barrier, facilitating a malignant transformation toward ccRCC.

Mitochondrial ribosomal protein S18-2 is highly expressed in endometrial cancers along with free E2F1.

Endometrial cancer (EC) is one of the most frequent causes of cancer death among women in developed countries. Histopathological diagnosis and imaging techniques for EC are limited, thus new prognostic markers are needed to offer patients the best treatment and follow-up.In the present paper we showed that the level of mitochondrial ribosomal protein MRPS18-2 (S18-2) increased in EC compared with the normal endometrium and hyperplasia, based on a study of 42 patient biopsies. Importantly, high expression of free E2F1 in EC correlates well with high S18-2 expression. The EC cell line HEC-1-A, which overexpresses S18-2 constitutively, showed an increased proliferation capacity in vitro and in vivo (in SCID mice). Moreover, pan-keratin, beta-catenin and E-cadherin signals are diminished in these cells, compared to the parental HEC-1-A line, in contrast to vimentin signal that is increased. This may be associated with epithelial-mesenchymal cell transition (EMT).We conclude that high expression of S18-2 and free E2F1, and low pan-keratin, beta-catenin, and E-cadherin signals might be a good set of prognostic markers for EC.

Substantial interindividual and limited intraindividual genomic diversity among tumors from men with metastatic prostate cancer.

Tumor heterogeneity may reduce the efficacy of molecularly guided systemic therapy for cancers that have metastasized. To determine whether the genomic alterations in a single metastasis provide a reasonable assessment of the major oncogenic drivers of other dispersed metastases in an individual, we analyzed multiple tumors from men with disseminated prostate cancer through whole-exome sequencing, array comparative genomic hybridization (CGH) and RNA transcript profiling, and we compared the genomic diversity within and between individuals. In contrast to the substantial heterogeneity between men, there was limited diversity among metastases within an individual. The number of somatic mutations, the burden of genomic copy number alterations and aberrations in known oncogenic drivers were all highly concordant, as were metrics of androgen receptor (AR) activity and cell cycle activity. AR activity was inversely associated with cell proliferation, whereas the expression of Fanconi anemia (FA)-complex genes was correlated with elevated cell cycle progression, expression of the E2F transcription factor 1 (E2F1) and loss of retinoblastoma 1 (RB1). Men with somatic aberrations in FA-complex genes or in ATM serine/threonine kinase (ATM) exhibited significantly longer treatment-response durations to carboplatin than did men without defects in genes encoding DNA-repair proteins. Collectively, these data indicate that although exceptions exist, evaluating a single metastasis provides a reasonable assessment of the major oncogenic driver alterations that are present in disseminated tumors within an individual, and thus may be useful for selecting treatments on the basis of predicted molecular vulnerabilities.

A novel small molecule agent displays potent anti-myeloma activity by inhibiting the JAK2-STAT3 signaling pathway.

The oncogenic STAT3 signaling pathway is emerging as a promising target for the treatment of multiple myeloma (MM). In the present study, we identified a novel STAT3 inhibitor SC99 in a target-based high throughput screen. SC99 inhibited JAK2-STAT3 activation but had no effects on other transcription factors such as NF-κB, and kinases such as AKT, ERK, and c-Src that are in association with STAT3 signaling pathway. Furthermore, SC99 downregulated the expression of STAT3-modulated genes, including Bcl-2, Bcl-xL, VEGF, cyclin D2, and E2F-1. By inhibiting the STAT3 signaling, SC99 induced MM cell apoptosis which could be partly abolished by the ectopic expression of STAT3. Furthermore, SC99 displayed potent anti-MM activity in two independent MM xenograft models in nude mice. Oral administration of SC99 led to marked decrease of tumor growth within 10 days at a daily dosage of 30 mg/kg, but did not raise toxic effects. Taken together, this study identified a novel oral JAK2/STAT3 inhibitor that could be developed as an anti-myeloma agent.

miR-449a enhances radiosensitivity through modulating pRb/E2F1 in prostate cancer cells.

miR-449a, a novel tumor suppressor, is deregulated in various malignancies, including prostate cancer. Overexpression of miR-449a induces cell cycle arrest, apoptosis, and senescence, but its role in response to ionizing radiation and underlying molecular mechanism are still unknown. Here, we report that miR-449a enhances radiation-induced G2/M phase arrest and apoptosis through modulating pRb/E2F1 and sensitizes prostate cancer cells to X-ray radiation. In wild-type Rb PC-3 cells, overexpression of miR-449a enhances radiation-induced G2/M arrest and apoptosis and promotes the sensitivity to X-ray radiation. While mutant Rb DU-145 cells are resistant to the X-ray radiation despite in the presence of miR-449a. The cell cycle distribution of DU-145 cells is not significantly altered by miR-449a in the response to ionizing radiation. Furthermore, elevated miR-449a downregulates cell cycle regulator CDC25A and oncogene HDAC1. By targeting genes involved in controlling pRb/E2F1 activity, miR-449a regulates cell cycle progression and apoptosis and consequently enhances the radiosensitivity of PC-3 cells. Thus, miR-449a, as a miRNA component of the Rb pathway, promotes the radiosensitivity of PC-3 cells through regulating pRb/E2F1.