miR-1293, a Candidate for miRNA-Based Cancer Therapeutics, Simultaneously Targets BRD4 and the DNA Repair Pathway.

BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, plays a role in the organization of super-enhancers and transcriptional activation of oncogenes in cancer and is recognized as a promising target for cancer therapy. microRNAs (miRNAs), endogenous small noncoding RNAs, cause mRNA degradation or inhibit protein translation of their target genes by binding to complementary sequences. miRNA mimics simultaneously targeting several tumor-promoting genes and BRD4 may be useful as therapeutic agents of tumor-suppressive miRNAs (TS-miRs) for cancer therapy. To investigate TS-miRs for the development of miRNA-based cancer therapeutics, we performed function-based screening in 10 cancer cell lines with a library containing 2,565 human miRNA mimics. Consequently, miR-1293, miR-876-3p, and miR-6571-5p were identified as TS-miRs targeting BRD4 in this screening. Notably, miR-1293 also suppressed DNA repair pathways by directly suppressing the DNA repair genes APEX1 (apurinic-apyrimidinic endonuclease 1), RPA1 (replication protein A1), and POLD4 (DNA polymerase delta 4, accessory subunit). Concurrent suppression of BRD4 and these DNA repair genes synergistically inhibited tumor cell growth in vitro. Furthermore, administration of miR-1293 suppressed in vivo tumor growth in a xenograft mouse model. These results suggest that miR-1293 is a candidate for the development of miRNA-based cancer therapeutics.

Identification and characterization of transforming growth factor beta-induced in circulating tumor cell subline from pancreatic cancer cell line.

Distant metastasis to liver, lung, brain, or bone occurs by circulating tumor cells (CTC). We hypothesized that a subset of CTC had features that are more malignant than tumor cells at the primary site. We established a highly malignant cell line, Panc-1-CTC, derived from the human pancreatic cancer cell line Panc-1 using an in vivo selection method. Panc-1-CTC cells showed greater migratory and invasive abilities than its parent cell line in vitro. In addition, Panc-1-CTC cells had a higher tumor-forming ability than parent cells in vivo. To examine whether a difference in malignant phenotypes exists between Panc-1-CTC cells and parent cells, we carried out comprehensive gene expression array analysis. As a result, Panc-1-CTC significantly expressed transforming growth factor beta-induced (TGFBI), an extracellular matrix protein, more abundantly than did parent cells. TGFBI is considered to regulate cell adhesion, but its functions remain unclear. In the present study, knockdown of TGFBI reduced cell migration and invasion abilities, whereas overexpression of TGFBI increased both abilities. Moreover, elevated expression of TGFBI was associated with poor prognosis in patients with pancreatic cancer.

miR-544a induces epithelial-mesenchymal transition through the activation of WNT signaling pathway in gastric cancer.

The epithelial-mesenchymal transition (EMT) contributes to cancer progression, as well as the development of normal organs, wound healing and organ fibrosis. We established a cell-based reporter system for identifying EMT-inducing microRNAs (miRNAs) with a gastric cancer (GC) cell line, MKN1, transfected with a reporter construct containing a promoter sequence of VIM in the 5' upstream region of the TurboRFP reporter gene. Function-based screening using this reporter system was performed with a 328-miRNA library, and resulted in the identification miR-544a as an EMT-inducing miRNA. Although miR-544a is already known to be involved in the regulation of CDH1, the mechanism by which EMT occurs remains poorly understood. Herein, we demonstrated that overexpression of miR-544a induces VIM, SNAI1 and ZEB1 expression, and reduces CDH1 expression, resulting in an EMT phenotype. In addition, we found that CDH1 and AXIN2, which are related to the degradation and the translocation of ß-catenin, are direct targets of miR-544a. Subsequently, the reduction of CDH1 and AXIN2 by miR-544a induced the nuclear import of ß-catenin, suggesting that miR-544a may activate the WNT signaling pathway through the stabilization of ß-catenin in nucleus. Our findings raise the possibility that inhibition of miR-544a may be a therapeutic target of metastatic GC.

Potential of tumor-suppressive miR-596 targeting LGALS3BP as a therapeutic agent in oral cancer.

The incidence and mortality statistics for oral squamous cell carcinoma (OSCC) were 10th and 12th, respectively, in human cancers diagnosed worldwide in 2008. In this study, to identify novel tumor-suppressive microRNAs (TS-miRNAs) and their direct targets in OSCC, we performed methylation-based screening for 43 miRNAs encoded by 46 miRNA genes located within 500 bp downstream of 40 CpG islands and genome-wide gene expression profiling in combination with a prediction database analysis, respectively, in 18 cell lines, resulting in the identification of a novel TS-miRNA miR-596 directly targeting LGALS3BP/Mac-2 BP/90K. DNA hypermethylation of CpG island located 5'-upstream of miR-596 gene was frequently observed in OSCC cell lines (100% of 18 cell lines) and primary OSCC cases (46.2 and 76.3% of 26 Japanese and 38 Thais primary cases, respectively) in a tumor-specific manner. The ectopic transfection of double-stranded RNA (dsRNA) mimicking miR-596 or specific small interfering RNA for LGALS3BP significantly induced growth inhibition and apoptosis in cell lines lacking miR-596 expression or overexpressing LGALS3BP, respectively, in a manner associated with a suppression of ERK1/2 phosphorylation. Moreover, we also mention the effect of dsRNA mimicking miR-596 on the growth of an OSCC cell line in vivo. Our findings define a central role for miR-596 in OSCC and suggest the potential of miR-596 as an anticancer agent for miRNA replacement therapy in OSCC.

Identification of a Biallelic Missense Variant in Gasdermin D (c.823G > C, p.Asp275His) in a Patient of Atypical Gorham-Stout Disease in a Consanguineous Family.

Gorham-Stout disease (GSD), also called vanishing bone disease, is a rare osteolytic disease, frequently associated with lymphangiomatous tissue proliferation. The causative genetic background has not been noted except for a case with a somatic mutation in KRAS. However, in the present study, we encountered a case of GSD from a consanguineous family member. Whole-exome sequencing (WES) analysis focusing on rare recessive variants with zero homozygotes in population databases identified a homozygous missense variant (c.823G > C, p.Asp275His) in gasdermin D (GSDMD) in the patient and heterozygous in his unaffected brother. Because this variant affects the Asp275 residue that is involved in proteolytic cleavage by caspase-11 (as well as -4 and -5) to generate an activating p30 fragment required for pyroptotic cell death and proinflammation, we confirmed the absence of this cleavage product in peripheral monocytic fractions from the patient. A recent study indicated that a shorter p20 fragment, generated by further cleavage at Asp88, has a cell-autonomous function to suppress the maturation of osteoclasts to resorb bone matrix. Thus, the present study suggests for the first time the existence of hereditary GSD cases or novel GSD-like diseases caused by GSDMD deficiency. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

YAP is a candidate oncogene for esophageal squamous cell carcinoma.

Yes-associated protein (YAP), the nuclear effector of the Hippo pathway, is a key regulator of organ size and a candidate human oncogene located at chromosome 11q22. Since we previously reported amplification of 11q22 region in esophageal squamous cell carcinoma (ESCC), in this study we focused on the clinical significance and biological functions of YAP in this tumor. Frequent overexpression of YAP protein was observed in ESCC cells including those with a robust amplicon at position 11q22. Overexpression of the YAP protein was frequently detected in primary tumors of ESCC as well. Patients with YAP-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors, and YAP positivity was independently associated with a worse outcome in the multivariate analysis. Further analyses in cells in which YAP was either overexpressed or depleted confirmed that cell proliferation was promoted in a YAP isoform-independent but YAP expression level-dependent manner. YAP depletion inhibited cell proliferation mainly in the G(0)-G(1) phase and induced an increase in CDKN1A/p21 transcription but a decrease in BIRC5/survivin transcription. Our results indicate that YAP is a putative oncogene in ESCC and it represents a potential diagnostic and therapeutic target.

miR-766-5p Targets Super-Enhancers by Downregulating CBP and BRD4.

Super-enhancers (SE) are clusters of transcription enhancers that drive gene expression. SEs are typically characterized by high levels of acetylation of histone H3 lysine 27 (H3K27ac), which is catalyzed by the histone lysine acetyltransferase CREB binding protein (CBP). Cancer cells frequently acquire tumor-specific SEs at key oncogenes, such as MYC, which induce several hallmarks of cancer. BRD4 is recruited to SEs and consequently functions as an epigenetic reader to promote transcription of SE-marked genes in cancer cells. miRNAs can be potent candidates for nucleic acid therapeutics for cancer. We previously identified miR-766-5p as a miRNA that downregulated MYC expression and inhibited cancer cell growth in vitro. In this study, we show that miR-766-5p directly targets CBP and BRD4. Concurrent suppression of CBP and BRD4 cooperatively downregulated MYC expression in cancer cells but not in normal cells. Chromatin immunoprecipitation analysis revealed that miR-766-5p reduced levels of H3K27ac at MYC SEs via CBP suppression. Moreover, miR-766-5p suppressed expression of a BRD4-NUT fusion protein that drives NUT midline carcinoma. In vivo administration of miR-766-5p suppressed tumor growth in two xenograft models. Collectively, these data suggest that targeting SEs using miR-766-5p-based therapeutics may serve as an effective strategy for the treatment of MYC-driven cancers. SIGNIFICANCE: This study demonstrates that miR-766-5p targets CBP and BRD4, which can mitigate the protumorigenic consequences of SEs and oncogenic fusion proteins.

Suppression of MET Signaling Mediated by Pitavastatin and Capmatinib Inhibits Oral and Esophageal Cancer Cell Growth.

Despite increasing knowledge on oral and esophageal squamous cell carcinoma (OSCC and ESCC), specific medicines against both have not yet been developed. Here, we aimed to find novel anticancer drugs through functional cell-based screening of an FDA-approved drug library against OSCC and ESCC. Pitavastatin, an HMGCR inhibitor, emerged as an anticancer drug that inhibits tumor growth by downregulating AKT and ERK signals in OSCC and ESCC cells. One of the mechanisms by which pitavastatin inhibits cell growth might be the suppression of MET signaling through immature MET due to dysfunction of the Golgi apparatus. Moreover, the sensitivity of tumor growth to pitavastatin might be correlated with GGPS1 expression levels. In vivo therapeutic models revealed that the combination of pitavastatin with capmatinib, a MET-specific inhibitor, dramatically reduced tumor growth. Our findings suggest that GGPS1 expression could be a biomarker in cancer therapy with pitavastatin, and the combination of pitavastatin with capmatinib might be a promising therapeutic strategy in OSCC and ESCC. IMPLICATIONS: This study provides new insight into the mechanism of pitavastatin as an anticancer drug and suggests that the combination of pitavastatin with capmatinib is a useful therapeutic strategy in OSCC and ESCC.

Concurrent targeting of MAP3K3 and BRD4 by miR-3140-3p overcomes acquired resistance to BET inhibitors in neuroblastoma cells.

Neuroblastoma (NB) harboring MYCN amplification is a refractory disease with a poor prognosis. As BRD4, an epigenetic reader belonging to the bromodomain and extra terminal domain (BET) family, drives transcription of MYCN in NB cells, BET inhibitors (BETis) are considered useful for NB therapy. However, clinical trials of BETis suggested that early acquired resistance to BETis limits their therapeutic benefit. MicroRNAs are small non-coding RNAs that mediate post-transcriptional silencing of target genes. We previously identified miR-3140-3p as a potent candidate for nucleic acid therapeutics for cancer, which directly targets BRD4. We demonstrated that miR-3140-3p suppresses tumor cell growth in MYCN-amplified NB by downregulating MYCN and MYC through BRD4 suppression. We established BETi-acquired resistant NB cells to evaluate the mechanism of resistance to BETi in NB cells. We revealed that activated ERK1/2 stabilizes MYCN protein by preventing ubiquitin-mediated proteolysis via phosphorylation of MYCN at Ser62 in BETi-acquired resistant NB cells, thereby attenuating the effects of BETi in these cells. miR-3140-3p efficiently downregulated MYCN expression by directly targeting the MAP3K3-ERK1/2 pathway in addition to BRD4 suppression, inhibiting tumor cell growth in BETi-acquired resistant NB cells. This study suggests that miR-3140-3p has the potential to overcome resistance to BETi in NB.

Isolation and characterisation of lymphatic endothelial cells from lung tissues affected by lymphangioleiomyomatosis.

Lymphangioleiomyomatosis (LAM) is a rare pulmonary disease characterised by the proliferation of smooth muscle-like cells (LAM cells), and an abundance of lymphatic vessels in LAM lesions. Studies reported that vascular endothelial growth factor-D (VEGF-D) secreted by LAM cells contributes to LAM-associated lymphangiogenesis, however, the precise mechanisms of lymphangiogenesis and characteristics of lymphatic endothelial cells (LECs) in LAM lesions have not yet been elucidated. In this study, human primary-cultured LECs were obtained both from LAM-affected lung tissues (LAM-LECs) and normal lung tissues (control LECs) using fluorescence-activated cell sorting (FACS). We found that LAM-LECs had significantly higher ability of proliferation and migration compared to control LECs. VEGF-D significantly promoted migration of LECs but not proliferation of LECs in vitro. cDNA microarray and FACS analysis revealed the expression of vascular endothelial growth factor receptor (VEGFR)-3 and integrin α9 were elevated in LAM-LECs. Inhibition of VEGFR-3 suppressed proliferation and migration of LECs, and blockade of integrin α9 reduced VEGF-D-induced migration of LECs. Our data uncovered the distinct features of LAM-associated LECs, increased proliferation and migration, which may be due to higher expression of VEGFR-3 and integrin α9. Furthermore, we also found VEGF-D/VEGFR-3 and VEGF-D/ integrin α9 signaling play an important role in LAM-associated lymphangiogenesis.

Frequent silencing of protocadherin 17, a candidate tumour suppressor for esophageal squamous cell carcinoma.

Protocadherins are a subfamily of the cadherin superfamily, but little is known about their functions. We identified a homozygous loss of protocadherin (PCDH) 17 in the course of a program to screen a panel of esophageal squamous cell carcinoma (ESCC) cell lines for genomic copy number aberrations. PCDH17 messenger RNA was expressed in normal esophageal tissue but not in the majority of ESCC cell lines without a homozygous deletion of this gene and restored in gene-silenced ESCC cells after treatment with 5-aza-2'-deoxycytidine. The DNA methylation status of the PCDH17 CpG island correlated inversely with the PCDH17 expression, and a putative methylation target region showed promoter activity. The methylation of the PCDH17 promoter was also associated with the silencing of gene expression in primary ESCC partly. Among primary ESCC cases, the silencing of PCDH17 protein expression was associated with a poorer differentiation status of ESCC cells and possibly with prognosis in a subset of this tumour. Restoration of PCDH17 expression in ESCC cells reduced cell proliferation and migration/invasion. These results suggest that silencing of PCDH17 expression through hypermethylation of the promoter or other mechanisms leads to loss of its tumour-suppressive activity, which may be a factor in the carcinogenesis of a subgroup of ESCCs.

Neutrophil Elastase Facilitates Tumor Cell Intravasation and Early Metastatic Events.

Functional roles of neutrophil elastase (NE) have not been examined in distinct steps of the metastatic cascade. NE, delivered to primary tumors as a purified enzyme or within intact neutrophils or neutrophil granule content, enhanced human tumor cell intravasation and subsequent dissemination via NE-mediated formation of dilated intratumoral vasculature. These effects depended on picomole range of NE activity, sensitive to its natural inhibitor, α1PI. In Elane-negative mice, the lack of NE decreased lung retention of human tumor cells in experimental metastasis. Furthermore, NE was essential for spontaneous metastasis of murine carcinoma cells in a syngeneic orthotopic model of oral cancer. NE also induced tumor cell survival and migration via Src/PI3K-dependent activation of Akt signaling, vital for tumor cell dissemination in vivo. Together, our findings implicate NE, a potent host enzyme specific for first-responding innate immune cells, as directly involved in early metastatic events and a potential target for therapeutic intervention.

Overexpression of SMYD2 relates to tumor cell proliferation and malignant outcome of esophageal squamous cell carcinoma.

Although we have identified two putative targets, ATF3 and CENPF, for a frequently gained/amplified region around 1q32-q41 in esophageal squamous cell carcinoma (ESCC), it is possible that other amplification targets remain to be identified. In this study, we tested whether SET and MYND domain-containing protein 2 (SMYD2), located between those two genes and encoding a lysine methyltransferase for histone H3K36 and p53K370 that regulates transcription and inhibits transactivation activity, respectively, acts as a cancer-promoting gene through activation/overexpression in ESCC. Frequent overexpression of SMYD2 messenger RNA and protein was observed in KYSE150 cells with remarkable amplification at 1q32-41.1 and other ESCC cell lines (11/43 lines, 25.6%). Overexpression of SMYD2 protein was frequently detected in primary tumor samples of ESCC (117/153 cases, 76.5%) as well and significantly correlated with gender, venous invasion, the pT category in the tumor-lymph node-metastases classification and status of recurrence. Patients with SMYD2-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors, and SMYD2 positivity was independently associated with a worse outcome in the multivariate analysis. Knockdown of SMYD2 expression inhibited and ectopic overexpression of SMYD2 promoted the proliferation of ESCC cells in a TP53 mutation-independent but SMYD2 expression-dependent manner. These findings suggest that SMYD2 plays an important role in tumor cell proliferation through its activation/overexpression and highlight its usefulness as a prognosticator and potential therapeutic target in ESCC.

Massive computational identification of somatic variants in exonic splicing enhancers using The Cancer Genome Atlas.

Owing to the development of next-generation sequencing (NGS) technologies, a large number of somatic variants have been identified in various types of cancer. However, the functional significance of most somatic variants remains unknown. Somatic variants that occur in exonic splicing enhancer (ESE) regions are thought to prevent serine and arginine-rich (SR) proteins from binding to ESE sequence motifs, which leads to exon skipping. We computationally identified somatic variants in ESEs by compiling numerous open-access datasets from The Cancer Genome Atlas (TCGA). Using somatic variants and RNA-seq data from 9635 patients across 32 TCGA projects, we identified 646 ESE-disrupting variants. The false positive rate of our method, estimated using a permutation test, was approximately 1%. Of these ESE-disrupting variants, approximately 71% were located in the binding motifs of four classical SR proteins. ESE-disrupting variants occurred in proportion to the number of somatic variants, but not necessarily in the specific genes associated with the biological processes of cancer. Existing bioinformatics tools could not predict the pathogenicity of ESE-disrupting variants identified in this study, although these variants could cause exon skipping. We demonstrated that ESE-disrupting nonsense variants tended to escape nonsense-mediated decay surveillance. Using integrated analyses of open access data, we could specifically identify ESE-disrupting variants. We have generated a powerful tool, which can handle datasets without normal samples or raw data, and thus contribute to reducing variants of uncertain significance because our statistical approach only uses the exon-junction read counts from the tumor samples.

Fibroblast growth factor signals regulate transforming growth factor-ß-induced endothelial-to-myofibroblast transition of tumor endothelial cells via Elk1.

The tumor microenvironment contains various components, including cancer cells, tumor vessels, and cancer-associated fibroblasts, the latter of which are comprised of tumor-promoting myofibroblasts and tumor-suppressing fibroblasts. Multiple lines of evidence indicate that transforming growth factor-ß (TGF-ß) induces the formation of myofibroblasts and other types of mesenchymal (non-myofibroblastic) cells from endothelial cells. Recent reports show that fibroblast growth factor 2 (FGF2) modulates TGF-ß-induced mesenchymal transition of endothelial cells, but the molecular mechanisms behind the signals that control transcriptional networks during the formation of different groups of fibroblasts remain largely unclear. Here, we studied the roles of FGF2 during the regulation of TGF-ß-induced mesenchymal transition of tumor endothelial cells (TECs). We demonstrated that auto/paracrine FGF signals in TECs inhibit TGF-ß-induced endothelial-to-myofibroblast transition (End-MyoT), leading to suppressed formation of contractile myofibroblast cells, but on the other hand can also collaborate with TGF-ß in promoting the formation of active fibroblastic cells which have migratory and proliferative properties. FGF2 modulated TGF-ß-induced formation of myofibroblastic and non-myofibroblastic cells from TECs via transcriptional regulation of various mesenchymal markers and growth factors. Furthermore, we observed that TECs treated with TGF-ß were more competent in promoting in vivo tumor growth than TECs treated with TGF-ß and FGF2. Mechanistically, we showed that Elk1 mediated FGF2-induced inhibition of End-MyoT via inhibition of TGF-ß-induced transcriptional activation of α-smooth muscle actin promoter by myocardin-related transcription factor-A. Our data suggest that TGF-ß and FGF2 oppose and cooperate with each other during the formation of myofibroblastic and non-myofibroblastic cells from TECs, which in turn determines the characteristics of mesenchymal cells in the tumor microenvironment.

LTBP3 promotes early metastatic events during cancer cell dissemination.

Latent transforming growth factor ß (TGFß)-binding proteins (LTBPs) are important for the secretion, activation, and function of mature TGFß, especially so in cancer cell physiology. However, specific roles of the LTBPs remain understudied in the context of the primary tumor microenvironment. Herein, we investigated the role of LTBP3 in the distinct processes involved in cancer metastasis. By using three human tumor cell lines of different tissue origin (epidermoid HEp-3 and prostate PC-3 carcinomas and HT-1080 fibrosarcoma) and several metastasis models conducted in both mammalian and avian settings, we show that LTBP3 is involved in the early dissemination of primary cancer cells, namely in the intravasation step of the metastatic cascade. Knockdown of LTBP3 in all tested cell lines led to significant inhibition of tumor cell intravasation, but did not affect primary tumor growth. LTBP3 was dispensable in the late steps of carcinoma cell metastasis that follow tumor cell intravasation, including vascular arrest, extravasation, and tissue colonization. However, LTBP3 depletion diminished the angiogenesis-inducing potential of HEp-3 cells in vivo, which was restorable by exogenous delivery of LTBP3 protein. A similar compensatory approach rescued the dampened intravasation of LTBP3-deficient HEp-3 cells, suggesting that LTBP3 regulates the induction of the intravasation-supporting angiogenic vasculature within developing primary tumors. Using our recently developed microtumor model, we confirmed that LTBP3 loss resulted in the development of intratumoral vessels with an abnormal microarchitecture incompatible with efficient intravasation of HEp-3 carcinoma cells. Collectively, these findings demonstrate that LTBP3 represents a novel oncotarget that has distinctive functions in the regulation of angiogenesis-dependent tumor cell intravasation, a critical process during early cancer dissemination. Our experimental data are also consistent with the survival prognostic value of LTBP3 expression in early-stage head and neck squamous cell carcinomas, further indicating a specific role for LTBP3 in cancer progression toward metastatic disease.

Publisher Correction: miR-3140 suppresses tumor cell growth by targeting BRD4 via its coding sequence and downregulates the BRD4-NUT fusion oncoprotein.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

miR-3140 suppresses tumor cell growth by targeting BRD4 via its coding sequence and downregulates the BRD4-NUT fusion oncoprotein.

Bromodomain Containing 4 (BRD4) mediates transcriptional elongation of the oncogene MYC by binding to acetylated histones. BRD4 has been shown to play a critical role in tumorigenesis in several cancers, and the BRD4-NUT fusion gene is a driver of NUT midline carcinoma (NMC), a rare but highly lethal cancer. microRNAs (miRNAs) are endogenous small non-coding RNAs that suppress target gene expression by binding to complementary mRNA sequences. Here, we show that miR-3140, which was identified as a novel tumor suppressive miRNA by function-based screening of a library containing 1090 miRNA mimics, directly suppressed BRD4 by binding to its coding sequence (CDS). miR-3140 concurrently downregulated BRD3 by bind to its CDS as well as CDK2 and EGFR by binding to their 3' untranslated regions. miR-3140 inhibited tumor cell growth in vitro in various cancer cell lines, including EGFR tyrosine kinase inhibitor-resistant cells. Interestingly, we found that miR-3140 downregulated the BRD4-NUT fusion protein and suppressed in vitro tumor cell growth in a NMC cell line, Ty-82 cells. Furthermore, administration of miR-3140 suppressed in vivo tumor growth in a xenograft mouse model. Our results suggest that miR-3140 is a candidate for the development of miRNA-based cancer therapeutics.

JPO1/CDCA7, a novel transcription factor E2F1-induced protein, possesses intrinsic transcriptional regulator activity.

JPO1/CDCA7 was originally identified as a c-Myc-responsive gene that participates in neoplastic transformation. Here, we report the identification of JPO1/CDCA7 as a direct transcriptional target of transcription factor E2F1. We demonstrated that overexpression of E2F1 by adenoviral-mediated gene transfer upregulated JPO1/CDCA7 mRNA expression in human cells. Analysis of human and mouse JPO1/CDCA7 promoter constructs showed that an E2F-responsive sequence was necessary for E2F1-induced activation of the JPO1/CDCA7 gene transcription. Among the members of the E2F family, E2F1 to E2F4, but not E2F5 or E2F6, activated the JPO1/CDCA7 reporter construct. Chromatin immunoprecipitation analysis demonstrated that E2F1, E2F2, and E2F4 specifically bound to an E2F-responsive sequence of the human JPO1/CDCA7 gene. Like JPO2/R1, which has a homologous transcriptional regulator domain, the C-terminal cysteine-rich region of JPO1/CDCA7 protein induced transcriptional activity in a mammalian one-hybrid assay. Taken together, our results suggest that JPO1/CDCA7 is a unique transcription regulator whose expression is activated by E2F1 as well as c-Myc.

miR-509-5p and miR-1243 increase the sensitivity to gemcitabine by inhibiting epithelial-mesenchymal transition in pancreatic cancer.

The epithelial-mesenchymal transition (EMT) contributes to various processes in cancer progression, such as metastasis and drug resistance. Since we have already established a cell-based reporter system for identifying EMT-suppressive microRNAs (miRNAs) in the pancreatic cancer cell line Panc1, we performed a function-based screening assay by combining this reporter system and a miRNA library composed of 1,090 miRNAs. As a result, we identified miR-509-5p and miR-1243 as EMT-suppressive miRNAs, although the mechanisms for EMT-suppression induced by these miRNAs have yet to be clarified. Herein, we demonstrated that overexpression of miR-509-5p and miR-1243 increased the expression of E-cadherin through the suppression of EMT-related gene expression and that drug sensitivity increased with a combination of each of these miRNAs and gemcitabine. Moreover, miR-509-5p was associated with worse overall survival in patients with pancreatic cancer and was identified as an independently selected predictor of mortality. Our findings suggest that miR-509-5p and miR-1243 might be novel chemotherapeutic targets and serve as biomarkers in pancreatic cancer.