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Physiological and pathological vascular remodeling is uniquely driven by mechanical forces from blood flow in which wall shear stress (WSS) mechanosensing by the vascular endothelium plays a pivotal role. This study aimed to determine the novel role for a disintegrin and metalloproteinase 17 (ADAM17) in impaired WSS mechanosensing, which was hypothesized to contribute to aging-associated abnormal vascular remodeling. Without changes in arterial blood pressure and blood flow rate, skeletal muscle resistance arteries of aged mice (30-month-old vs. 12-week-old) exhibited impaired WSS mechanosensing and displayed inward hypertrophic arterial remodeling. These vascular changes were recapitulated by in vivo confined, AAV9-mediated overexpression of ADAM17 in the resistance arteries of young mice. An aging-related increase in ADAM17 expression reduced the endothelial junction level of its cleavage substrate, junctional adhesion molecule-A/F11 receptor (JAM-A/F11R). In cultured endothelial cells subjected to steady WSS ADAM17 activation or JAM-A/F11R knockdown inhibited WSS mechanosensing. The ADAM17-activation induced, impaired WSS mechanosensing was normalized by overexpression of ADAM17 cleavage resistant, mutated JAM-A(V232Y) both in cultured endothelial cells and in resistance arteries of aged mice, in vivo. These data demonstrate a novel role for ADAM17 in JAM-A/F11R cleavage-mediated impaired endothelial WSS mechanosensing and subsequently developed abnormal arterial remodeling in aging. ADAM17 could prove to be a key regulator of WSS mechanosensing, whereby it can also play a role in pathological vascular remodeling in diseases. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11357-021-00476-1.

The fibroblast growth factor 19 gene FGF19 has previously been reported to be amplified in several cancer types and encodes for a key autocrine signaler known to promote tumorigenic growth. Thus, it is imperative to understand which cancers are oncogenically addicted to FGF19 amplification as well as the role it serves in these cancer types. We report for the first time high FGF19 amplification in head and neck squamous cell carcinomas (HNSCC), which is associated with increased autocrine secretion of FGF19 and poor patient outcome in HNSCC. FGF19 amplification corresponded with constitutive activation of FGF receptor 4 (FGFR4)-dependent ERK/AKT-p70S6K-S6 signaling activation in HNSCC cells, and addition of human recombinant FGF19 could promote cell proliferation and soft agar colony formation in HNSCC cells with low FGF19 expression through activation of FGFR4 and downstream signaling cascades. In contrast, FGF19 knockout counteracts the observed effects in HNSCC cells carrying high endogenous FGF19, with knockout of FGF19 significantly suppressing tumor growth in an orthotopic mouse model of HNSCC. Collectively, this study demonstrates that FGF19 gene amplification corresponds with an increased dependency upon FGF19/FGFR4 autocrine signaling in HNSCC, revealing a therapeutic target for this cancer type.

Chronic periodontitis (CP) is a microbial dysbiotic disease linked to increased risk of oral squamous cell carcinomas (OSCCs). To address the underlying mechanisms, mouse and human cell infection models and human biopsy samples were employed. We show that the ‘keystone’ pathogen Porphyromonas gingivalis, disrupts immune surveillance by generating myeloid-derived dendritic suppressor cells (MDDSCs) from monocytes. MDDSCs inhibit CTLs and induce FOXP3 + Tregs through an anti-apoptotic pathway. This pathway, involving pAKT1, pFOXO1, FOXP3, IDO1 and BIM, is activated in humans with CP and in mice orally infected with Mfa1 expressing P. gingivalis strains. Mechanistically, activation of this pathway, demonstrating FOXP3 as a direct FOXO1-target gene, was demonstrated by ChIP-assay in human CP gingiva. Expression of oncogenic but not tumor suppressor markers is consistent with tumor cell proliferation demonstrated in OSCC-P. gingivalis cocultures. Importantly, FimA + P. gingivalis strain MFI invades OSCCs, inducing inflammatory/angiogenic/oncogenic proteins stimulating OSCCs proliferation through CXCR4. Inhibition of CXCR4 abolished Pg-MFI-induced OSCCs proliferation and reduced expression of oncogenic proteins SDF-1/CXCR4, plus pAKT1-pFOXO1. Conclusively, P. gingivalis, through Mfa1 and FimA fimbriae, promotes immunosuppression and oncogenic cell proliferation, respectively, through a two-hit receptor-ligand process involving DC-SIGN+hi/CXCR4+hi, activating a pAKT+hipFOXO1+hiBIM−lowFOXP3+hi and IDO+hi- driven pathway, likely to impact the prognosis of oral cancers in patients with periodontitis.

With the development of new materials and technologies, it is possible to access gene function and drug metabolism using a three-dimensional (3D) cell culture system, which is more suitable for mimicking the in vivo microenvironment of cultured tumor cells ex vivo. SeedEZ is a novel and versatile tool that allows culturing of different types of cells with user convenience and in a desired sequence. This system provides a bridge between traditional 2D culture and animal experiments. Here, we provide two examples demonstrating how to evaluate cancer cell growth by the SeedEZ 3D scaffold and cancer cell invasion by the SeedEZ 3D ring, in order to promote understanding of the necessity of this novel cell culture system.

The DNA binding protein and chromatin structural regulator DEK regulate many cellular processes. These include proliferation, differentiation, apoptosis, senescence, DNA repairing and the maintenance of stem cell phenotype. DEK is increasingly recognized as a crucial player in many steps of cancer initiation and progression, and is precisely regulated by abundant promoting and inhibiting factors directly or indirectly. DEK may serve as an architectural modulating protein to regulate the expression and function of multiple human genes in cancer cells. In this article we have reviewed the specificities and complexities of DEK in the regulation of transcription factors and global chromatin, including its biologic roles in malignant cells, and summarized the current research. The possible use of DEK as a diagnostic marker and drug target in the prevention or treatment of tumors is also discussed.

Head and neck squamous cell carcinoma (HNSCC) represents only 4% of all cancers in the US, but the adverse impact of this disease on health quality is dramatic. There has been little improvement in HNSCC treatment outcomes in decades, and a better understanding of the molecular biology of HNSCC is urgently needed to facilitate the design of anti-HNSCC therapies. The mitochondrial ATPase family AAA-domain containing protein 3A (ATAD3A) has been demonstrated as an oncogene in breast and lung cancer. However, nothing has been reported regarding its role in HNSCC. We report here that loss of ATAD3A expression inhibits HNSCC cell growth as evidenced by reduced cell proliferation and decreased the ability of colony formation and anchorage-independent growth in soft agar, whereas gain of ATAD3A expression counteracts the observed effects. Overexpression of a Walker A dead mutant of ATAD3A (ATAD3AK358) leads to a suppression in HNSCC cell growth and lipids synthesis, suggesting a potent dominant-negative effect of defective ATP-binding of ATAD3A. In line with the in vitro data, overexpression of ATAD3A facilities tumor growth in an orthotopic mouse model of HNSCC. In contrast, inhibition of ATAD3A function by knockout of ATAD3A or expression of ATAD3AK358 induces significant repression of tumor growth. These findings indicate that the mitochondrial protein ATAD3A plays an oncogenic role in HNSCC, and abrogating its ATP-binding ability may represent a promising regimen for better treatment of patients with HNSCC. Citation Format: Liwei Lang, Tiffany Lam, Alex Chen, Chole Shay, Yong Teng. The essential role of ATP binding to the mitochondrial protein ATAD3A in driving oncogenesis of head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2406.

Background Metastatic lung cancer is a life-threatening condition that develops when cancer in another area of the body metastasizes, or spreads, to the lung. Despite advances in our understanding of primary lung oncogenesis, the biological basis driving the progression from primary to metastatic lung cancer remains poorly characterized. Methods Genetic knockdown of the particular genes in cancer cells were achieved by lentiviral-mediated interference. Invasion potential was determined by Matrigel and three-dimensional invasion. The secretion of matrix metalloproteinase 2 (MMP2) and MMP9 were measured by ELISA. Protein levels were assessed by Western blotting and immunohistochemistry. Protein-protein interactions were determined by immunoprecipitation. An experimental mouse model was generated to investigate the gene regulation in tumor growth and metastasis. Results Nck-associated protein 1 (NAP1/NCKAP1) is highly expressed in primary non-small-cell lung cancer (NSCLC) when compared with adjacent normal lung tissues, and its expression levels are strongly associated with the histologic tumor grade, metastasis and poor survival rate of NSCLC patients. Overexpression of NAP1 in lowly invasive NSCLC cells enhances MMP9 secretion and invasion potential, whereas NAP1 silencing in highly invasive NSCLC cells produces opposing effects in comparison. Mechanistic studies further reveal that the binding of NAP1 to the cellular chaperone heat shock protein 90 (HSP90) is required for its protein stabilization, and NAP1 plays an essential role in HSP90-mediated invasion and metastasis by provoking MMP9 activation and the epithelial-to-mesenchymal transition in NSCLC cells. Conclusions Our insights demonstrate the importance and functional regulation of the HSP90-NAP1 protein complex in cancer metastatic signaling, which spur new avenues to target this interaction as a novel approach to block NSCLC metastasis. Electronic supplementary material The online version of this article (10.1186/s13046-019-1124-0) contains supplementary material, which is available to authorized users.

Background A promising arsenal of histone deacetylase (HDAC)-targeted treatment has emerged in the past decade, as the abnormal targeting or retention of HDACs to DNA regulatory regions often occurs in many cancers. Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies worldwide associated with poor overall survival in late-stage patients. HDAC inhibitors have great potential to treat this devastating disease; however, few has been studied regarding the beneficial role of HDAC inhibition in anti-HNSCC therapy and the underlying molecular mechanisms remain elusive. Methods Cell migration and invasion were examined by wound closure and Transwell assays. Protein levels and interactions were assessed by Western blotting and immunoprecipitation. HDAC activity was measured with the fluorometric HDAC Activity Assay. Phospho-receptor tyrosine kinase (RTK) profiling was determined by the Proteome Profiler Human Phospho-RTK Array. Results ADP-ribosylation factor 1 (Arf1), a small GTPase coordinating vesicle-mediated intracellular trafficking, can be inactivated by HDAC inhibitors through histone acetylation-independent degradation of epidermal growth factor receptor (EGFR) in HNSCC cells. Mechanistically, high levels of Arf1 activity are maintained by binding to phosphorylated EGFR which is localized on HNSCC cell plasma membrane. Decreased EGFR phosphorylation is associated with reduced EGFR protein levels in the presence of TSA, which inactivates Arf1 and eventually inhibits invasion in HNSCC cells. Conclusions Our insights explore the critical role of EGFR-Arf1 complex in driving HNSCC progression, and demonstrate the selective action of HDAC inhibitors on this specific axis for suppressing HNSCC invasion. This novel finding represents the first example of modulating the EGFR-Arf1 complex in HNSCC by small molecule agents. Electronic supplementary material The online version of this article (10.1186/s13046-019-1080-8) contains supplementary material, which is available to authorized users.

Fibroblast growth factor receptor 4 (FGFR4), a tyrosine kinase receptor for FGFs, is involved in diverse cellular processes, including the regulation of cell proliferation, differentiation, migration, metabolism, and bile acid biosynthesis. High activation of FGFR4 is strongly associated with the amplification of its specific ligand FGF19 in many types of solid tumors and hematologic malignancies, where it acts as an oncogene driving the cancer development and progression. Currently, the development and therapeutic evaluation of FGFR4-specific inhibitors, such as BLU9931 and H3B-6527, in animal models and cancer patients, are paving the way to suppress hyperactive FGFR4 signaling in cancer. This comprehensive review not only covers the recent discoveries in understanding FGFR4 regulation and function in cancer, but also reveals the therapeutic implications and applications regarding emerging anti-FGFR4 agents. Our aim is to pinpoint the potential of FGFR4 as a therapeutic target and identify new avenues for advancing future research in the field.

Phosphofructokinase-1 (PFK-1), a rate-determining enzyme of glycolysis, is an allosteric enzyme that regulates the oxidation of glucose in cellular respiration. Glycolysis phosphofructokinase platelet (PFKP) is the platelet isoform and works as an important mediator of cell metabolism. Considering that PFKP is a crucial player in many steps of cancer initiation and metastasis, we reviewed the specificities and complexities of PFKP and its biological roles in human diseases, especially malignant tumors. The possible use of PFKP as a diagnostic marker or a drug target in the prevention or treatment of cancer is also discussed.

The ATPase family AAA-domain containing protein 3A (ATAD3A), a nuclear-encoded mitochondrial enzyme, is involved in diverse cellular processes, including mitochondrial dynamics, cell death and cholesterol metabolism. Overexpression and/or mutation of the ATAD3A gene have been observed in different types of cancer, associated with cancer development and progression. The dysregulated ATAD3A acts as a broker of a mitochondria-endoplasmic reticulum connection in cancer cells, and inhibition of this enzyme leads to tumor repression and enhanced sensitivity to chemotherapy and radiation. As such, ATAD3A is a promising drug target in cancer treatment.

Cisplatin is well-known for its damaging effect on nuclear DNA, leading to cell death due to blockage of DNA replication and transcription, but this activity cannot fully explain why cisplatin displays cytotoxicity in post-mitotic tissues, suggesting other mechanisms may be in play. Many studies have challenged the current model of cisplatin resistance, however, the precise mechanism behind is still unknown. Here, we report that the mitochondrial protein ATAD3A functions as an oncogene in oral squamous cell carcinoma (OSCC), promoting cell proliferation and enhancing the ability of colony formation and anchorage-independent growth. Moreover, ATAD3A is involved in cisplatin resistance in OSCC, and knockdown of ATAD3A enhanced the sensitivity of OSCC cells to cisplatin. It appears that ATAD3A-mediated cisplatin resistance is regulated by other mechanisms rather than its expression levels, as evidenced by overexpression of a Walker A (WA) dead mutant of ATAD3A leads to a suppression in OSCC cell growth and resensitizes cisplatin-resistant OSCC cells to this drug, indicating a potent dominant-negative effect of defective ATP-binding of ATAD3A in chemotherapy. Our study demonstrates for the first time that ATAD3A plays an oncogenic role in OSCC and abrogating its ATP-binding ability may represent a promising regimen for better treatment of patients with OSCC, especially for those who suffer from cisplatin-resistance. Citation Format: Liwei Lang, Leslie Duncan, Caleb Jensen, Chloe Shay, Yong Teng. The mitochondrial protein ATAD3A promotes cisplatin resistance in oral squamous cell carcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-130.

Ilaprazole is a novel proton pump inhibitor that provides effective and long lasting inhibition of intragastric acid secretion. The objectives of this study were to investigate the pharmacokinetics, pharmacodynamics, and safety of intravenous ilaprazole after multiple administrations in healthy Chinese subjects. This was an open-label and multiple-dose clinical study. Ten healthy Chinese subjects received 10 mg ilaprazole infusion once daily for 5 days. Helicobacter pylori status was examined. Blood samples were collected and intragastric pH was recorded for 24 h. Safety was assessed throughout the study. There was no accumulation after multiple administrations. The mean steady-state half-life and clearance were comparable to those following single administration. Ilaprazole provided sustainable and significant intragastric pH control in terms of percentage time at pH >4, pH >6 within 24 h and mean 24-h pH values. The pH value within 24 h was affected by Helicobacter pylori infection in subjects with continuous infusion. Intravenous ilaprazole was safe and there were no serious adverse events. Intravenous ilaprazole provided stable pharmacokinetics and pharmacodynamics at a dose of 10 mg once daily for 5 days, and was well tolerated in healthy subjects.

Spanning from the mitochondria’s outer surface to the inner membrane, the nuclear-encoded protein ATAD3A maintains vital roles in regulating mitochondrial dynamics, homeostasis, metabolism, and interactions with the endoplasmic reticulum. Recently, elevated levels of ATAD3A have been reported in several types of cancer and to be tightly correlated with cancer development and progression, including increased cancer cell potential of proliferation, metastasis, and resistance to chemotherapy and radiotherapy. In the current review, we reveal ATAD3A as the link between mitochondrial functions and cancer biology and the accumulating evidence presenting ATAD3A as an attractive target for the development of novel cancer therapy to inhibit aberrant cancer metabolism and progression.

Histone deacetylase (HDAC)-targeted treatment has the great potential to treat head and neck squamous cell carcinoma (HNSCC). However, little has been reported regarding the beneficial role of HDAC inhibition in anti-HNSCC therapy and the underlying molecular mechanisms remain elusive. Here, we demonstrate that ADP-ribosylation factor 1 (Arf1), a small GTPase coordinating vesicle-mediated intracellular trafficking, can be inactivated by HDAC inhibitors TSA and PXD101, through histone acetylation-independent degradation of epidermal growth factor receptor (EGFR) in HNSCC cells. Mechanistically, activated Arf1 (GTP-Arf1) is maintained by binding to phosphorylated EGFR on the cancer cell plasma membrane. Decreased EGFR phosphorylation is associated with reduced EGFR protein levels in the presence of HDAC inhibitors, which inactivates Arf1 and eventually inhibits its dependent invasion in HNSCC cells. This novel finding represents the first example of modulating the EGFR-Arf1 complex in HNSCC by small-molecule agents. Our insights not only explore the critical role of the EGFR-Arf1 complex in driving HNSCC progression, but also shed light onto the molecular events accounting for HDAC-targeted therapy. Citation Format: Leilei He, Lixia Gao, Liwei Lang, Chloe Shay, Yong Teng. Inactivating the EGFR-Arf1 axis by HDAC-targeted therapy to suppress invasiveness of head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B09.

Background Inhibition of metastasis of head and neck squamous cell carcinoma (HNSCC) is one of the most important challenges in cancer treatment. Src, a non-receptor tyrosine kinase, has been implicated as a key promoter in tumor progression and metastasis of HNSCC. However, Src therapy for HNSCC is limited by lack of efficient in vivo delivery and underlying mechanisms remain elusive. Methods Src knockdown cells were achieved by lentiviral-mediated interference. Cell migration and invasion were examined by wound healing and Transwell assays. Protein levels were determined by Western blot and/or immunohistochemistry. The Src inhibitor saracatinib was loaded into self-assembling nanoparticles by the solvent evaporation method. An experimental metastasis mouse model was generated to investigate the drug efficacy in metastasis. Results Blockade of Src kinase activity by saracatinib effectively suppressed invasion and metastasis of HNSCC. Mechanistic assessment of the drug effects in HNSCC cells showed that saracatinib induced suppression of Src-dependent invasion/metastasis through downregulating the expression levels of Vimentin and Snail proteins. In tests in mice, saracatinib loaded into the novel multifunctional nanoparticles exhibited superior effects on suppression of HNSCC metastasis compared with the free drug, which is mainly attributed to highly specific and efficient tumor-targeted drug delivery system. Conclusions These findings and advances are of great importance to the development of Src-targeted nanomedicine as a more effective therapy for metastatic HNSCC. Electronic supplementary material The online version of this article (10.1186/s13045-018-0623-3) contains supplementary material, which is available to authorized users.

The incidence rate of head and neck squamous cell carcinoma (HNSCC) has steadily increased over the past decade. However, treatment options for metastatic HNSCC are often limited and the 5‐year survival rate has remained static. Therefore, the development and assessment of more efficient but less toxic therapeutic strategies is an unmet need for treatment of more extensive HNSCC. Here, we report that CYT997, a novel microtubule‐disrupting agent, exerts strong activity in inhibiting HNSCC cell invasion and metastasis. The loss of invasion capacity by CYT997 was accompanied by an associated increase in cell adhesion and the reversal of epithelial‐mesenchymal transition (EMT). Increased expression of E‐cadherin protein and decreased expression of Vimentin protein became evident in HNSCC cells following CYT997 exposure, which were consistently observed in HNSCC xenografts from the mice receiving CYT997. Moreover, the capacity of invasive HNSCC cells to form pulmonary metastases was significantly blocked with CYT997 treatment, indicating that the diminishment of EMT traits contributes to CYT997‐suppressed metastasis. Intriguingly, CYT997 impaired intracellular ATP levels in HNSCC cells, at least in part, through its inhibitory effect on the mitochondrial protein IF1. The addition of ATP attenuated CYT997‐induced suppression of cell invasion, coupled with down‐regulation of E‐Cadherin and up‐regulation of Vimentin. These findings support a critical role of ATP levels in cell invasion and metastasis under the influence of CYT997. Collectively, our data unveil the mechanism involved in mediating CYT997 action, and provide preclinical rationale for possible clinical application of CYT997 as a novel therapeutic strategy against aggressive HNSCC.

Mice lacking genes involving in the DNA-damage response (DDR) are often tumor prone owing to genome instability caused by oncogenic challenges. Previous studies demonstrate that activating transcription factor 3 (ATF3), a common stress sensor, can activate the tumor suppressor p53 and regulate expression of p53 target genes upon DNA damage. However, whether ATF3 contributes to the maintenance of genome stability and tumor suppression remains unknown. Here we report that Atf3-deficient (Atf3-/-) mice developed spontaneous tumors, and died significantly earlier than wild-type (Atf3+/+) mice. Consistent with these results, Atf3-/- mouse embryonic fibroblasts (MEFs) had more aberrant chromosomes and micronuclei, and were genetically unstable. Whereas we demonstrated that ATF3 activated p53 and promoted its pro-apoptotic activity in mouse thymi and small intestines, the chromosomal instability caused by Atf3 deficiency was largely dependent on the regulation of p53 by ATF3. Interestingly, loss of Atf3 also promoted spontaneous tumorigenesis in Trp53+/- mice, but did not affect tumor formation in Trp53-/- mice. Our results thus provide the first genetic evidence linking ATF3 to the suppression of the early development of cancer, and underscore the importance of ATF3 in the maintenance of genome integrity.

This work aimed to evaluate a method to detect the residual ricin in animal tissues. Immunoprecipitation and sandwich enzyme-linked immunosorbent assay (ELISA) were used to detect ricin in the tissues of intoxicated mice. The monoclonal antibodies (Mabs) 4C13 and 3D74 were used to assay the whole ricin molecules via sandwich ELISA. Mab 4C13 was conjugated with Sepharose 4B to capture ricin or ricin A chain by immunoprecipitation. Mice injected intravenously with ricin at the dosage of 5 microg/mouse were killed at different time points after intoxication. The serum, liver, kidney, lung, and intestine were harvested. High levels of ricin were found in serum and liver samples at each poisoning time point by sandwich ELISA, suggesting the possibility of determining ricin intoxication by detecting residual ricin in the serum. However, this method turned out to be ineffective for examining ricin in the kidney, lung, and intestine of poisoned mice. Although the same tissue samples of intoxicated mice were analyzed by immunoprecipitation, positive bands were found. This indicated that some components in the kidney, lung, and intestine could bind with ricin and interfere in its binding activity with the coated antibody. Immunoprecipitation could be used to measure the existence of ricin in these samples.

OBJECTIVE To investigate the inhibitory activity of HIF-1 by triptolide and manasaantin A, two cell-based models with luciferase report gene assay were established. METHOD Two cell-based models of HIF-1 were used to evaluate HIF-1 inhibition activity of triptolide and manasaantin A. Secreted VEGF expression induced by hypoxia was detected by ELISA with two compounds. The growth inhibition of different solid tumor cell lines was measured by the MTT assay. RESULT The expression of firefly luciferase was induced by hypoxia in U251-HRE and T47D-HRE cells. U251-HRE model was suitable for the detection of HIF-1 inhibition activity of triptolide. The IC50 of triptolide on HIF-1 activity was (3.4 +/- 0.5) x 10(-8) mol x L(-1). The report gene assay using T47D cells co-transfected with pGL2-TK-HRE and pRL-CMV showed more sensitive inhibition activity of HIF-1 on manassantin A than that of detected by U251-HRE model. The IC50 of manassantin A on HIF-1 activity was (2.4 +/- 0.6) x 10(-8) mol x L(-1). HIF-1 target gene VEGF was also inhibited by test compounds on protein level in T47D cells. Manasaantin A showed selective inhibition on the growth of human solid cancer cell lines, especially on breast cancer and pancreatic cancer cells. Meanwhile, triplotide showed strong proliferation inhibition activity on all tested cell lines. CONCLUSION It is very important to select a suitable cell-based report gene assay of HIF-1 for screening of different kinds of inhibitor.

Given that aberrant gene expression is widely spread in cancer, there is an imperative need of developing reliable high-throughput drug screening (HTS) platforms in search of lead compounds that can rectify abnormal expression of cancer-driving genes for treating this deadly disease. Although it has been demonstrated that reporter gene assays are useful in the identification of transcription-targeted lead compounds, these assays are often unreliable and can yield high rates of false compounds due to the facts that reporter genes are driven by cloned promoters and localized in foreign chromatin environments. While cloned promoters lack essential cis-regulatory elements (e.g., enhancers) far removed from transcription start sites, foreign chromatin environment can alter gene expression in a way atypical to endogenous genes. To address these limitations, we employed emerging genome-editing tools to develop a novel reporter-based HTS assay whereby the reporter gene is inserted immediately downstream of the coding region of an endogenous gene, and thereby co-expressed bicistronically with the endogenous gene as a single transcript under the control of the native transcriptional regulatory machinery. As a proof-of-principle, we first employed the CRISPR-Cas9 system to knock a fused selection gene tk-ble (encoding Zeocin resistance for selection for targeting events and thymidine kinase for negative selection for the removal of the selection gene, respectively) flanked by a wild-type and a mutated FRT fragment into the eukaryotic translation initiation factor 4E (EIF4E) gene locus, and then replaced the selection gene with a firefly luciferase (FLuc), or a Renilla luciferase (RLuc), by cassette exchange mediated by the recombinase Flp. We demonstrated that the FLuc gene was expressed as single transcripts with EIF4E by Northern blotting, and responded to chemical treatments in a way analog to the endogenous EIF4E gene. Using the cells carrying bicistronic FLuc reporter, we screened a chemical library containing 4,800 compounds for small molecules inhibitory for EIF4E expression, and identified 11 hits, out of which 6 compounds were validated to decrease EIF4E expression by qRT-PCR. While the 5 false-positive compounds were likely yielded due to their direct inhibition of FLuc activity, 4 of these false positives could be readily identified by an orthogonal assay using recombinant cells carrying RLuc in the same EIF4E locus. Therefore, our results have demonstrated that screening assays based on bicistronic in-situ reporters are more reliable, and powerful in searching for transcription-targeted lead compounds with high confidence. Citation Format: Liwei Lang, Chunhong Yan. A novel bicistronic reporter-based high-throughput screening platform for discovery of transcription-targeted lead compounds. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1348.

The dineolignan manassantin A from Saururaceae was recently identified as a hypoxia-inducible factor 1 (HIF-1) inhibitor, but its in-vivo anti-tumor effect has not been explored. We synthesized a series of manassantin A derivatives, and found that replacing the central tetrahydrofuran moiety with a cyclopentane ring yielded a compound (LXY6006) with increased HIF-1-inhibitory activity yet decreased stereochemically complexity amenable to a simplified synthesis scheme. LXY6006 inhibited HIF-1α nuclear accumulation induced by hypoxia, and inhibited cancer cell growth as a consequence of G2/M arrest. Oral administration of LXY6006 significantly inhibited growth of breast, lung, and pancreatic tumors implanted in nude mice. These results indicate that LXY6006 represents a novel class of agents targeting a broad range of human cancers.

Summary Although transgene-based reporter gene assays have been used to discover small molecules targeting expression of cancer-driving genes, the success is limited due to the fact that reporter gene expression regulated by incomplete cis -acting elements and foreign epigenetic environments does not faithfully reproduce chemical responses of endogenous genes. Here, we present an internal ribosome entry site-based strategy for bicistronically co-expressing reporter genes with an endogenous gene in the native gene locus, yielding an in situ reporter assay closely mimicking endogenous gene expression without disintegrating its function. This strategy combines the CRISPR-Cas9-mediated genome-editing tool with the recombinase-mediated cassette-exchange technology, and allows for rapid development of orthogonal assays for excluding false hits generated from primary screens. We validated this strategy by developing a screening platform for identifying compounds targeting oncogenic eIF4E, and demonstrated that the novel reporter assays are powerful in searching for transcription-targeted lead compounds with high confidence.