Phenotype Of Human Cancer Research Articles

Cytotoxic and Pro-Apoptotic Effects of Leaves Extract of Antiaris africana Engler (Moraceae).

Antiaris africana Engler leaves have been used in Senegalese folk medicine to treat breast cancer. The present study aimed to investigate the anticancer potential of Antiaris africana Engler leaves using several human cancer cell lines. The leaves of Antiaris africana Engler were extracted in parallel with water or 70% ethanol and each extract divided into three parts by successive liquid-liquid extraction with ethyl acetate and butanol. The phytochemical components of the active extract were investigated using ultra-performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (UPLC-DAD-QTOF-MS/MS). The cytotoxic and cytostatic effects of each extract, as well as their fractions, were evaluated in vitro via flow and image cytometry on different human cancer phenotypes, such as breast (MCF-7), pancreas (AsPC-1), colon (SW-620) and acute monocytic leukemia (THP-1). Both hydro-alcoholic and aqueous extracts induced strong apoptosis in MCF-7 cells. The water fraction of the hydro-alcoholic extract was found to be the most active, suppressing the cell growth of MCF-7 in a dose-dependent manner. The half maximum effective concentration (EC50) of this fraction was 64.6 ± 13.7 μg/mL for MCF-7, with equivalent values for all tested phenotypes. In parallel, the apoptotic induction by this fraction resulted in a EC50 of 63.5 ± 1.8 μg/mL for MCF-7, with again equivalent values for all other cellular tested phenotypes. Analysis of this fraction by UPLC-DAD-QTOF-MS/MS led to the identification of hydroxycinnamates as major components, one rutin isomer, and three cardiac glycosides previously isolated from seeds and bark of Antiaris africana Engler and described as cytotoxic in human cancer models. These results provide supportive data for the use of Antiaris africana Engler leaves in Senegal.

NOTCH1 PEST domain variants are responsive to standard of care treatments despite distinct transformative properties in a breast cancer model.

Activating variants in the PEST region of NOTCH1 have been associated with aggressive phenotypes in human cancers, including triple-negative breast cancer (TNBC). Previous studies suggested that PEST domain variants in TNBC patients resulted in increased cell proliferation, invasiveness, and decreased overall survival. In this study, we assess the phenotypic transformation of activating NOTCH1 variants and their response to standard of care therapies. AAV-mediated gene targeting was used to isogenically incorporate 3 NOTCH1 variants, including a novel TNBC frameshift variant, in two non-tumorigenic breast epithelial cell lines, MCF10A and hTERT-IMEC. Two different variants at the NOTCH1 A2241 site (A2441fs and A2441T) both demonstrated increased transformative properties when compared to a non-transformative PEST domain variant (S2523L). These phenotypic changes include proliferation, migration, anchorage-independent growth, and MAPK pathway activation. In contrast to previous studies, activating NOTCH1 variants did not display sensitivity to a gamma secretase inhibitor (GSI) or resistance to chemotherapies. This study demonstrates distinct transformative phenotypes are specific to a given variant within NOTCH1 and these phenotypes do not correlate with sensitivities or resistance to chemotherapies or GSIs. Although previous studies have suggested NOTCH1 variants may be prognostic for TNBC, our study does not demonstrate prognostic ability of these variants and suggests further characterization would be required for clinical applications.

RhoGDI2 induced malignant phenotypes of pancreatic cancer cells via regulating Snail expression.

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been shown to contribute to the aggressive phenotypes of human cancers, such as tumor metastasis and chemoresistance. This study aimed to assess the effects of RhoGDI2 on tumor progression and chemoresistance in pancreatic cancer cells. The expression of RhoGDI2 in pancreatic cancer cells was detected by Western blot analysis. Gain-of-function and loss-of-function approaches were done to examine the malignant phenotypes of the RhoGDI2-expressing or RhoGDI2-depleting cells. The correlation between RhoGDI2 and Snail was also analyzed. Differential expression of RhoGDI2 protein in pancreatic cancer cell lines was identified. Gain-of-function and loss-of-function experiments showed that RhoGDI2 induced the malignant phenotypes of pancreatic cancer cells, including proliferation, migration, invasion, and gemcitabine (GEM) chemoresistance. The upregulation of RhoGDI2 stimulated the expression of Snail, resulting in the altered expression of epithelial marker E-cadherin and mesenchymal marker Vimentin, which were characteristics of the tumorigenic activity of epithelial-mesenchymal transition. The expression of RhoGDI2 and Snail was upregulated in clinical tumor samples, and higher expression of RhoGDI2 or Snail was significantly associated with poor patient survival in pancreatic ductal adenocarcinoma (PDAC). The findings indicated that RhoGDI2 promoted GEM resistance and tumor progression in pancreatic cancer and that RhoGDI2 might be a potential therapeutic target in patients with PDAC.

Recurrent mutations in topoisomerase IIα cause a previously undescribed mutator phenotype in human cancers

Topoisomerases nick and reseal DNA to relieve torsional stress associated with transcription and replication and to resolve structures such as knots and catenanes. Stabilization of the yeast Top2 cleavage intermediates is mutagenic in yeast, but whether this extends to higher eukaryotes is less clear. Chemotherapeutic topoisomerase poisons also elevate cleavage, resulting in mutagenesis. Here, we describe p.K743N mutations in human topoisomerase hTOP2α and link them to a previously undescribed mutator phenotype in cancer. Overexpression of the orthologous mutant protein in yeast generated a characteristic pattern of 2- to 4-base pair (bp) duplications resembling those in tumors with p.K743N. Using mutant strains and biochemical analysis, we determined the genetic requirements of this mutagenic process and showed that it results from trapping of the mutant yeast yTop2 cleavage complex. In addition to 2- to 4-bp duplications, hTOP2α p.K743N is also associated with deletions that are absent in yeast. We call the combined pattern of duplications and deletions ID_TOP2α. All seven tumors carrying the hTOP2α p.K743N mutation showed ID_TOP2α, while it was absent from all other tumors examined (n = 12,269). Each tumor with the ID_TOP2α signature had indels in several known cancer genes, which included frameshift mutations in tumor suppressors PTEN and TP53 and an activating insertion in BRAF. Sequence motifs found at ID_TOP2α mutations were present at 80% of indels in cancer-driver genes, suggesting that ID_TOP2α mutagenesis may contribute to tumorigenesis. The results reported here shed further light on the role of topoisomerase II in genome instability.

SMYD2 suppresses p53 activity to promote glucose metabolism in cervical cancer

Reprogrammed energy metabolism, especially the Warburg effect, is emerged as a hallmark of cancer. The protein lysine methyltransferase SMYD2 functions as an oncogene and is implicated in various malignant phenotypes of human cancers. However, the role of SMYD2 in tumor metabolism is still largely unknown. Here, we report that SMYD2 is highly expressed in human cervical cancer and its aberrant expression is linked to a poor prognosis. Bioinformatic analysis revealed a novel link between SMYD2 expression and aerobic glycolysis. Through loss-of-function experiments, we demonstrated that SMYD2 knockdown or inhibition induced a metabolic shift from aerobic glycolysis to oxidative phosphorylation, as evidenced by glucose uptake, lactate production, extracellular acidification, and the oxygen consumption rate. In contrast, SMYD2 overexpression promoted glycolytic metabolism in cervical cancer cells. Moreover, SMYD2 was required for tumor growth in cervical cancer and this oncogenic activity was largely glycolysis-dependent. Mechanistically, SMYD2 altered the methylation status of p53 and inhibited its transcriptional activity. Genetic silencing of p53 largely abrogated the effects of SMYD2 in promoting aerobic glycolysis. Taken together, our findings reveal a novel function of SMYD2 in regulating the Warburg effect in cervical cancer.

Genomics-Guided Drawing of Molecular and Pathophysiological Components of Malignant Regulatory Signatures Reveals a Pivotal Role in Human Diseases of Stem Cell-Associated Retroviral Sequences and Functionally-Active hESC Enhancers.

Repetitive DNA sequences (repeats) colonized two-third of human genome and a majority of repeats comprised of transposable genetic elements (TE). Evolutionary distinct categories of TE represent nucleic acid sequences that are repeatedly copied from and pasted into chromosomes at multiple genomic locations and acquired a multitude of regulatory functions. Here, genomics-guided maps of stemness regulatory signatures were drawn to dissect the contribution of TE to clinical manifestations of malignant phenotypes of human cancers. From patients’ and physicians’ perspectives, the clinical definition of a tumor’s malignant phenotype could be restricted to the early diagnosis of sub-types of malignancies with the increased risk of existing therapy failure and high likelihood of death from cancer. It is the viewpoint from which the understanding of stemness and malignant regulatory signatures is considered in this contribution. Genomics-guided analyses of experimental and clinical observations revealed the pivotal role of human stem cell-associated retroviral sequences (SCARS) in the origin and pathophysiology of clinically-lethal malignancies. SCARS were defined as the evolutionary- and biologically-related family of genomic regulatory sequences, the principal physiological function of which is to create and maintain the stemness phenotype during human preimplantation embryogenesis. For cell differentiation to occur, SCARS expression must be silenced and SCARS activity remains repressed in most terminally-differentiated human cells which are destined to perform specialized functions in the human body. Epigenetic reprogramming, de-repression, and sustained activity of SCARS results in various differentiation-defective phenotypes. One of the most prominent tissue- and organ-specific clinical manifestations of sustained SCARS activities is diagnosed as a pathological condition defined by a consensus of morphological, molecular, and genetic examinations as the malignant growth. Here, contemporary evidence are acquired, analyzed, and reported defining both novel diagnostic tools and druggable molecular targets readily amenable for diagnosis and efficient therapeutic management of clinically-lethal malignancies. These diagnostic and therapeutic approaches are based on monitoring of high-fidelity molecular signals of continuing SCARS activities in conjunction with genomic regulatory networks of thousands’ functionally-active embryonic enhancers affecting down-stream phenotype-altering genetic loci. Collectively, reported herein observations support a model of SCARS-activation triggered singular source code facilitating the intracellular propagation and intercellular (systemic) dissemination of disease states in the human body.

Hedgehog Signaling and Truncated GLI1 in Cancer.

The hedgehog (HH) signaling pathway regulates normal cell growth and differentiation. As a consequence of improper control, aberrant HH signaling results in tumorigenesis and supports aggressive phenotypes of human cancers, such as neoplastic transformation, tumor progression, metastasis, and drug resistance. Canonical activation of HH signaling occurs through binding of HH ligands to the transmembrane receptor Patched 1 (PTCH1), which derepresses the transmembrane G protein-coupled receptor Smoothened (SMO). Consequently, the glioma-associated oncogene homolog 1 (GLI1) zinc-finger transcription factors, the terminal effectors of the HH pathway, are released from suppressor of fused (SUFU)-mediated cytoplasmic sequestration, permitting nuclear translocation and activation of target genes. Aberrant activation of this pathway has been implicated in several cancer types, including medulloblastoma, rhabdomyosarcoma, basal cell carcinoma, glioblastoma, and cancers of lung, colon, stomach, pancreas, ovarian, and breast. Therefore, several components of the HH pathway are under investigation for targeted cancer therapy, particularly GLI1 and SMO. GLI1 transcripts are reported to undergo alternative splicing to produce truncated variants: loss-of-function GLI1ΔN and gain-of-function truncated GLI1 (tGLI1). This review covers the biochemical steps necessary for propagation of the HH activating signal and the involvement of aberrant HH signaling in human cancers, with a highlight on the tumor-specific gain-of-function tGLI1 isoform.

HIF1A expression correlates with increased tumor immune and stromal signatures and aggressive phenotypes in human cancers

Although many studies have revealed essential roles of HIF1A (hypoxia inducible factor 1 subunit alpha) in regulating various pathways associated with cancer development, a systematic investigation of associations of HIF1A expression with tumor immunity, the tumor microenvironment and other tumor phenotypes in pan-cancer is lacking. Using cancer genomics datasets of 10 cancer cohorts from the Cancer Genome Atlas (TCGA) program, we investigated associations of HIF1A expression with tumor immune and stromal signatures, and various tumor phenotypes, including cell proliferation, stemness, epithelial-mesenchymal transition (EMT), tumor purity, oncogenic signaling, and clinical outcomes. HIF1A upregulation was found to be associated with increased immune and stromal signatures, aggressive phenotypes, and worse survival rates in various cancers. Moreover, HIF1A upregulation was not only associated with activation of various oncogenic signaling pathways, but also with increased tumor suppressive signatures, including apoptosis and anti-tumor immune response, indicative of a dual role of HIF1A in cancer development. However, HIF1A expression showed a stronger correlation with immune-inhibiting signatures than with immune-promoting signatures. Furthermore, HIF1A expression was found to be positively associated with both tumor immune infiltration and PD-L1 expression, indicating that tumors with elevated expression of HIF1A may exhibit a more active immunotherapy response. This indication was substantiated in a kidney cancer cohort receiving anti-PD-1/PD-L1 immunotherapy. HIF1A upregulation correlates with increased tumor immune and stromal signatures and aggressive phenotypes in human cancers. Our analysis may provide new insights into the role of HIF1A in tumor biology and clinical management.

Tissue and Cell-Free DNA-Based Epigenomic Approaches for Cancer Detection.

Over 9 million people die of cancer each year worldwide, reflecting the unmet need for effective biomarkers for both cancer diagnosis and prognosis. Cancer diagnosis is complex because the majority of malignant tumors present with long periods of latency and lack of clinical presentation at early stages. During carcinogenesis, premalignant cells experience changes in their epigenetic landscapes, such as differential DNA methylation, histone modifications, nucleosome positioning, and higher orders of chromatin changes that confer growth advantage and contribute to determining the biologic phenotype of human cancers. Recent progress in microarray platforms and next-generation sequencing approaches has allowed the characterization of abnormal epigenetic patterns genome wide in a large number of cancer cases. The sizable amount of processed data also comes with challenges regarding data management and assessment for effective biomarker exploration to be further applied in prospective clinical trials. Epigenetics-based single or panel tests of genes are being explored for clinical management to fulfill unmet needs in oncology. The advance of these tests to the clinical routine will depend on rigorous, extensive, and independent validation in well-annotated cohort of patients and commercial development of clinical routine-friendly and adequate procedures. In this review we discuss the analytic validation of tissue and cell-free DNA-based epigenomic approaches for early cancer detection, diagnosis, and treatment monitoring and the clinical utility of candidate epigenetic alterations applied to colorectal, glioblastoma, breast, prostate, bladder, and lung cancer management.

Abstract 5381: Understanding the genesis and oncogenic consequences of tandem duplicator phenotypes in human cancers

Abstract Genome-scale instability configurations in cancer genomes are commonly found across different types of cancers. We and others have described an enrichment of head-to-tail somatic segmental tandem duplications (TDs) in primarily breast and ovarian cancers, a configuration known as the Tandem Duplicator Phenotype (TDP). Here, we perform a meta-analysis of 2,717 human cancer genomes, representing 30 different tumor types and refine the TDP classification based on the identification of highly specific and recurrent TD span profiles. Overall, we identify the TDP as a highly recurrent chromosomal instability configuration, occurring in 14% of the cancer genomes examined. The TDP is remarkably prevalent in triple negative breast cancer (50%), ovarian cancer (55%), and uterine cancers (45%), but is infrequent in most other cancer types. In TDP tumors, TD span sizes can be classified into three major discrete intervals with modal values of 10 Kb, 230 Kb, and 1.7 Mb. TDPs with a dominant TD modal span size of 10 Kb are strongly associated with conjoint TP53 mutations and BRCA1 deficiency across different tumor types. TDPs with larger span sizes (230 Kb and 1.7 Mb) are associated with CCNE1 pathway activation and CRKRS/CDK12 gene disruptions. We proved the driver role of the conjoint abrogation of the BRCA1 and TP53 genes for the induction of TDP cancers with the 10 Kb predominant span peak by generating mammary cancers with a Tandem Duplicator Phenotype of the ~10 Kb TD span configuration type in genetically modified mouse models harboring deleterious mutations in only these same two genes. Lastly, we describe how heterogeneous combinations of tumor suppressors and chromatin topologically associating domains are disrupted, and oncogene and tissue-specific super enhancers are duplicated as a consequence of TD formation in TDP tumors. In summary, our work unifies a number of observations around a specific cancer genomic signature, shows how a number of genetic drivers converge on creating the tandem duplicator phenotype, and how the downstream consequences of the TDs generate oncogenic diversity that allows for further formation of genetic subgroups. The implications of TDP-based stratification for therapy response are currently under investigation. Citation Format: Francesca Menghi, Floris Barthel, Vinod Yadav, Ming Tang, Bo Ji, Gregory Carter, Jos Jonkers, Roel Verhaak, Ralph Scully, Ed Liu. Understanding the genesis and oncogenic consequences of tandem duplicator phenotypes in human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5381.

Glioblastoma Model Using Human Cerebral Organoids

SUMMARYWe have developed a cancer model of gliomas in human cerebral organoids that allows direct observation of tumor initiation as well as continuous microscopic observations. We used CRISPR/Cas9 technology to target an HRasG12V-IRES-tdTomato construct by homologous recombination into the TP53 locus. Results show that transformed cells rapidly become invasive and destroy surrounding organoid structures, overwhelming the entire organoid. Tumor cells in the organoids can be orthotopically xenografted into immunodeficient NOD/SCID IL2RG−/− animals, exhibiting an invasive phenotype. Organoid-generated putative tumor cells show gene expression profiles consistent with mesenchymal subtype human glioblastoma. We further demonstrate that human-organoid-derived tumor cell lines or primary human-patient-derived glioblastoma cell lines can be transplanted into human cerebral organoids to establish invasive tumor-like structures. Our results show potential for the use of organoids as a platform to test human cancer phenotypes that recapitulate key aspects of malignancy.

Protein phosphatase 1B dephosphorylates Rho guanine nucleotide dissociation inhibitor 1 and suppresses cancer cell migration and invasion

Rho GTPases control a wide range of cellular processes, and their deregulation is associated with promotion of an aggressive and metastatic tumor phenotype in human cancers. Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays a key role in regulating the activity of Rho GTPases. However, the underlying mechanisms are still unclear. In this study, we show that protein phosphatase 1B (PPM1B) interacts with RhoGDI1 and functions as its phosphatase. Ectopic expression of PPM1B results in dephosphorylation of RhoGDI1 and, thereby, abates the activation of RhoA, Rac1 and CDC42 by epidermal growth factor (EGF). PPM1B overexpression in Hs578T and SKBR3 human breast cancer cells decreases their motility and invasiveness in vitro and cancer metastasis in vivo. In contrast, knockdown of PPM1B in MCF-7 and MDA-MB-468 human breast cancer cells that express endogenous PPM1B enhances EGF-induced RhoGDI1 phosphorylation, activation of Rho GTPases, and cancer cell migration and invasion. Knockdown of RhoA or Rac1 by siRNA reverses the enhanced cell migration seen after PP1MB depletion. Collectively, these results indicate that PPM1B negatively regulates cancer cell motility and invasiveness through dephosphorylating RhoGDI1.

The Effects of Liquor Spirits on RNA Pol III Genes and Cell Growth of Human Cancer Lines

Alcohol consumption is a major health issue and associated with human cancers, such as liver and breast cancers. Alcohol was classed as carcinogen to human by IARC. We have performed in vivo and in vitro studies which demonstrate that diluted ethanol promotes cell proliferation and transformation and tumor formation. Consumption of liquor spirits (white wines) is a popular behavior. However, it is unclear whether liquor spirits affect cellular phenotypes of human cancers. At present study, we used diluted ethanol and liquor spirits (Sample #1 and Sample #2) to determine the changes in RNA polymerase III-dependent gene (Pol III gene) transcription, cell growth and colony formation in the different human cancer lines. The results indicate that low concentration of ethanol increases RNA Pol III gene transcription and rate of cell growth. However, both liquor spirits (Sample #1 and Sample #2) inhibit the activity of RNA Pol III genes and repress cell proliferation of the cancer lines, compared to diluted ethanol. The liquor spirits reduce the rate of colony formation of human breast cancer cells and esophageal carcinoma cells. The inhibitions of the liquor spirits to RNA Pol III genes, cell growth and colony formation are in a dose-dependent manner. These new findings suggest that the liquor spirits contain some active components to repress Pol III gene transcription and cell growth caused by ethanol in different human cancer cells.

Metabolic Reprogramming of Triple-Negative Breast Cancer: The Role of miRNAs

AbstractMicroRNAs (miRNAs) are well known to influence the expression of the genes that regulate critical cellular functions. Various reports have suggested that they play critical roles in breast cancer metabolism through the regulation of various metabolic pathways, including the metabolism of glucose, lipids, glycolysis and the mitochondrial tricarboxylic acid cycle (TCA). miRNAs regulate the metabolic process by targeting key molecules (enzymes, kinases transporters) or by modifying the expression of key transcription molecules. In addition, miRNAs can indirectly regulate mRNA translation by targeting chromatin-remodeling enzymes. Furthermore, miRNAs influence the expression of both oncogenes and tumor suppressors and have a major impact on PI3K/AKT, HIF, and MYC signal transduction, which contributes to the metabolic phenotype in human cancer. Although human epidermal growth factor and endocrine therapies have been effective in treating breast cancer, for locally advanced and distant metastases mortality remains high. Drug resistance and recurrence remain major hurdles for advanced breast cancer therapy. Given the critical influence of metabolic reprogramming in the progression of neoplasm, tumorigenesis and metastasis, research should focus on novel targets of metabolic enzymes to reverse drug resistance and improve overall survival rates. Blocking the miRNAs that contribute to metabolic reprogramming or the use of exogenous miRNAs as antisense oligonucleotides, may be an effective way to treat aggressive, chemo-resistant cancers. This review summarizes current knowledge on the mechanism of action of miRNAs in altering the metabolism of cancer cells and presents possible therapeutic approaches to treating breast cancers that are resistant to current drugs.

Human PBMC-transferred murine MHC class I/II-deficient NOG mice enable long-term evaluation of human immune responses.

Immunodeficient mice engrafted with human peripheral blood cells are promising tools for in vivo analysis of human patient individual immune responses. However, when human peripheral blood mononuclear cells (PBMCs) are transferred into NOG (NOD/Shi-scid, IL-2rg null) mice, severe graft versus host disease (GVHD) hinders long term detailed analysis. Administration of human PBMCs into newly developed murine MHC class I- and class II-deficient NOG (NOG-dKO; NOG- Iab, B2m-double-knockout) mice showed sufficient engraftment of human immune cells with little sign of GVHD. Immunization with influenza vaccine resulted in an increase in influenza-specific human IgG Ab, indicating induction of antigen-specific B cells in the NOG-dKO mice. Immunization with human dendritic cells pulsed with HLA-A2 restricted cytomegalovirus peptide induced specific cytotoxic T cells, indicating the induction of antigen-specific T cells in the NOG-dKO mice. Adoptive cell therapies (ACTs) using melanoma antigen recognized by T cells (MART-1)-specific TCR-transduced activated T cells showed strong tumor growth inhibition in NOG-dKO mice without any sign of GVHD accompanied by preferential expansion of the transferred MART-1-specific T cells. ACTs using cultured human melanoma infiltrating T cells also showed anti-tumor effects against autologous melanoma cells in NOG-dKO mice, in which changes in human cancer phenotypes by immune intervention, such as increased CD271 expression, could be evaluated. Therefore, NOG-dKO mice are useful tools for more detailed analysis of both the induction and effector phases of T-cell and B-cell responses for a longer period than regular NOG mice.

Targeting cancer-specific glycans by cyclic peptide lectinomimics.

The transformation from normal to malignant phenotype in human cancers is associated with aberrant cell-surface glycosylation. Thus, targeting glycosylation changes in cancer is likely to provide not only better insight into the roles of carbohydrates in biological systems, but also facilitate the development of new molecular probes for bioanalytical and biomedical applications. In the reported study, we have synthesized lectinomimics based on odorranalectin 1; the smallest lectin-like cyclic peptide isolated from the frog Odorrana grahami skin, and assessed the ability of these peptides to bind specific carbohydrates on molecular and cellular levels. In addition, we have shown that the disulfide bond found in 1 can be replaced with a lactam bridge. However, the orientation of the lactam bridge, peptides 2 and 3, influenced cyclic peptide's conformation and thus these peptides' ability to bind carbohydrates. Naturally occurring 1 and its analog 3 that adopt similar conformation in water bind preferentially L-fucose, and to a lesser degree D-galactose and N-acetyl-D-galactosamine, typically found within the mucin O-glycan core structures. In cell-based assays, peptides 1 and 3 showed a similar binding profile to Aleuria aurantia lectin and these two peptides inhibited the migration of metastatic breast cancer cell lines in a Transwell assay. Altogether, the reported data demonstrate the feasibility of designing lectinomimics based on cyclic peptides.

Abstract 2900: Sigma-1 receptor control tumorigenic and stem cell-like phenotype in human cancers

Abstract Tumor-initiating stem-like cancer cells drive tumor progression, metastasis and treatment failure. Understanding the pathways driving self-renewal and expansion of cancer stem-like cells (CSCs) in human cancers may provide actionable therapeutic targets for developing novel treatment strategies. Metabolic reprogramming and mitochondrial homeostasis are emerging as key features of CSCs. The sigma-1 receptor (Sig-1R) is a ligand-activated chaperone protein localized at the ER-mitochondria membrane and involved in inter-organelle signaling, mitochondrial homeostasis and stress response. Sig-1R is up-regulated in many human cancers, although its role in tumorigenesis is unclear. Here, we examined the role of Sig-1R on survival and expansion of cancer cells with stem-like properties using genetic knockdown and selective pharmacological antagonists. Transient and stable depletion of Sig-1R using small interfering RNAs (siRNAs) and short hairpin RNAs (shRNAs), respectively, affected clonogenic and tumor-sphere forming capability of prostate cancer cell lines. Cell proliferation and viability under standard culture conditions were minimally affected. Selective high affinity Sig-1R antagonists also suppressed clonogenicity and tumor-sphere formation, reproducing the effects of genetic depletion. Notably, stable Sig-1R knockdown with shRNAs drastically reduced development of tumor xenografts in mice, indicating a reversal of tumorigenic and stem-like properties upon depletion of Sig-1R. Sig-1R knockdown impaired mitochondrial function with reduced mitochondrial membrane potential (flow cytometry JC-1 assay) and respiratory capacity (Seahorse Mito Stress assay). These effects were more evident under metabolic stress induced by glucose starvation and were associated with drastic changes in morphology and intracellular distribution of mitochondria. Similar metabolic effects were seen with selective Sig-1R antagonists. These findings indicate that Sig-1R sustains tumorigenic properties by enhancing mitochondrial homeostasis and metabolic adaptability of stem-like cancer cells ensuring their long-term survival and self-renewal capability. Targeting the Sig-1R with selective antagonists could be an innovative approach to cancer treatment capable of preventing survival and expansion of tumor-initiating stem-like cancer cells in human cancers. Citation Format: Gianluca Civenni, Martina Marchetti, Shusil Pandit, Celeste De Monte, Federica Sereni, Jessica Merulla, Sabrina Zadic, Marco Losa, Sara Allegrini, Domenico Albino, Sarah Mapelli, Erik Laurini, Bernhard Wunsch, Sabrina Pricl, Giuseppina M. Carbone, Carlo V. Catapano. Sigma-1 receptor control tumorigenic and stem cell-like phenotype in human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2900. doi:10.1158/1538-7445.AM2017-2900

Elevated COX-2 Expression Promotes Angiogenesis Through EGFR/p38-MAPK/Sp1-Dependent Signalling in Pancreatic Cancer

Cyclooxygenase-2 (COX-2) was stated to be overexpression in various human malignancies associating with angiogenesis, metastasis and chemoresistence. Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease displaying many of these characteristics. A common abnormality of PDAC is overexpression of specificity protein-1 (Sp1), which was said to correlate with malignant phenotypes of human cancers. Using RNA-seq data from The Cancer Genome Atlas (TCGA), we found that Sp1 expression was positively correlated with that of COX-2 in PDAC, and that the inhibition or overexpression of Sp1 in PDAC cells leads to decreased or elevated COX-2 expression. Luciferase reporter gene and chromatin immunoprecipitation (ChIP) assays revealed that elevated transcription of COX-2 requires Sp1 binding to sequence positions around −245/−240 of COX-2 promoter. Activated epidermal growth factor receptor (EGFR) and downstream p38 mitogen-activated protein kinase (p38-MAPK) were also profoundly altered in PDAC. The inhibition of EGFR/p38-MAPK signaling resulted in reduced Sp1 activation, decreased COX-2 and vascular endothelial growth factor (VEGF) expression. Thus, Sp1 could transcriptionally activate COX-2 expression in a process relies on activated EGFR/p38-MAPK signaling. Finally, we found that the inhibition of COX-2 leads to decreased angiogenesis in a process dependent on VEGF, which link COX-2 to angiogenesis in PDAC.

Melittin inhibits the invasion of MCF-7 cells by downregulating CD147 and MMP-9 expression.

Tumor invasion and metastasis are the critical steps in determining the aggressive phenotype of human cancers. Melittin, a major component of bee venom, has been reported to induce apoptosis in several cancer cells. However, the mechanisms of melittin involvement in cancer invasion and metastasis remain unclear. Our previous study indicated that melittin inhibits cyclophilin A (CypA), a ubiquitously distributed peptidylprolyl cis-trans isomerase, in macrophage cells. In the present study, the Transwell assay results showed that melittin may downregulate the invasion level of MCF-7 cells in a dose-dependent manner. Additionally, it was also found, using flow cytometry and reverse transcription-polymerase chain reaction, that melittin decreased the expression of cluster of differentiation (CD)147 and matrix metallopeptidase-9 (MMP-9), whereas CypA upregulated the expression of CD147 and MMP-9. Overall, the present study indicated that melittin decreased the invasion level of MCF-7 cells by downregulating CD147 and MMP-9 by inhibiting CypA expression. The results of the present study provide an evidence for melittin in anticancer therapy and mechanisms.

Recapitulating Human Gastric Cancer Pathogenesis: Experimental Models of Gastric Cancer.

This review focuses on the various experimental models to study gastric cancer pathogenesis, with the role of genetically engineered mouse models (GEMMs) used as the major examples. We review differences in human stomach anatomy compared to the stomachs of the experimental models, including the mouse and invertebrate models such as Drosophila and C. elegans. The contribution of major signaling pathways, e.g., Notch, Hedgehog, AKT/PI3K is discussed in the context of their potential contribution to foregut tumorigenesis. We critically examine the rationale behind specific GEMMs, chemical carcinogens, dietary promoters, Helicobacter infection, and direct mutagenesis of relevant oncogenes and tumor suppressor that have been developed to study gastric cancer pathogenesis. Despite species differences, more efficient and effective models to test specific genes and pathways disrupted in human gastric carcinogenesis have yet to emerge. As we better understand these species differences, "humanized" versions of mouse models will more closely approximate human gastric cancer pathogenesis. Towards that end, epigenetic marks on chromatin, the gut microbiota, and ways of manipulating the immune system will likely move center stage, permitting greater overlap between rodent and human cancer phenotypes thus providing a unified progression model.