Therapeutic Target For Malignancy Research Articles

Serum nectin-2 and nectin-4 are diagnostic in lung cancer: which is superior?

Nectins are immunoglobulin-like molecules that are involved in cell to cell adhesion by forming tight junctions and homophilic/heterophilic interactions. This study aimed to analyze serum nectin‑2 and nectin‑4 levels in lung cancer patients and to evaluate the prognostic, diagnostic and predictive strengths. Data from 74lung cancer patients were retrospectively examined and enzyme-linked immunosorbent assays (ELISA) were used to measure serum nectin‑2 and nectin‑4 concentrations. Atotal number of 40age and sex-adjusted healthy controls were also enrolled in the study. The median serum nectin‑2 and nectin‑4 levels of the patients were significantly higher than those of controls (p < 0.001); however, neither biomarker was found to be associated with clinicopathological parameters, (p > 0.05), and furthermore they were found not to be correlated with either overall survival or progression-free survival (p > 0.05). Even though both markers showed high diagnostic values, serum nectin‑2 was found superior to both serum nectin‑4 and serum nectin-2 + nectin‑4 combinations in the diagnosis of lung cancer according to higher sensitivity, specificity and predictive values. Serum nectin‑2 and nectin‑4 might be used in lung cancer diagnosis but the diagnostic importance of nectin‑2 is higher. The prognostic and predictive strengths in cancer are controversial. Furthermore, the interactions with tumor microenvironments and the potentials as therapeutic targets for malignancies have yet to be elucidated.

LCN2-interacting proteins and their expression patterns in brain tumors

Lipocalin 2 (LCN2) is a member of the lipocalin family. Elevated expression of LCN2 has been observed in many human tumors, suggesting it might be a potential biomarker and/or therapeutic target in malignancies. In this study, we aimed to explore LCN2 interacting proteins through bioinformatics, as well as their biological functions. Protein-protein interaction networks (PPIN) were constructed using LCN2 and its interacting proteins as the core node. These PPINs were scale free biological networks in which LCN2 and its interacting proteins could connect or cross-talk with at least one partner protein. Both functional and KEGG pathway enrichment analyses identified the known and potential biological functions of the PPIN, such as cell migration and cancer-related pathways. Expression levels of the PPIN proteins, as well as their expression correlations, in five types of brain tumor, were analyzed and integrated into the PPIN to illustrate a dynamic change. A significant correlation was found between the survival time of glioblastoma patients and the expression level of 10 genes (LCN2, MMP9, MMP2, PDE4DIP, L2HGDH, HNRNPA1, DDX31, LOXL2, FAM60A and RNF25). Taken together, our results suggest that LCN2 and its interacting proteins are mostly differentially expressed and have a distinguishing co-expression pattern. They might promote proliferation and migration via cell migration signaling and cancer-related pathways. LCN2 and its interacting proteins might be potential biomarkers in glioblastoma.

Distinct expression and prognostic value of members of the epidermal growth factor receptor family in ovarian cancer.

BackgroundIncreased aberrant expression or activation of the epidermal growth factor receptor (EGFR) family members has been reported in a wide range of cancers, and the EGFR family of tyrosine kinases has emerged as an important therapeutic target in malignancies. However, the expression patterns and exact roles of each distinct EGFR family member, which contribute to tumorigenesis and progression of ovarian cancer (OC), are yet to be elucidated.Materials and methodsIn the current study, we report the distinct expression and prognostic value of EGFR family members in patients with OC by analyzing a series of databases including ONCOMINE, Gene Expression Profiling Interactive Analysis, Kaplan–Meier plotter, cBioPortal, and Database for Annotation, Visualization and Integrated Discovery .ResultsIt was found that in patients with OC, mRNA expression levels of ERBB2/3/4 were significantly upregulated, whereas the transcription levels of EGFR were downregulated. Aberrant EGFR expression and ERBB2/3/4 mRNA levels were associated with OC prognosis.ConclusionThese results suggest that EGFR and ERBB3/4 are distinct prognostic biomarkers and may be potential targets for OC. These results may be beneficial to better understand the molecular underpinning of OC and may be useful to develop tools for more accurate OC prognosis and for promoting the development of EGFR-targeted inhibitors for OC treatment.

Long noncoding RNAs in the mTOR signaling network: biomarkers and therapeutic targets.

As an evolutionarily conserved serine/threonine kinase of the phosphoinositide 3-kinase (PI3K) related kinase family, the mechanistic/mammalian target of rapamycin (mTOR) plays vital roles in the PI3K/AKT/mTOR pathway, participating in different cellular processes including cell survival, metabolism and proliferation. Aberrant activity of this signaling pathway may lead to oncogenesis. Over the last two decades, great progress has been made in the understanding of mTOR activation and how its response is counteracted for maintaining tissue homeostasis. Besides regulatory proteins and microRNAs, long noncoding RNA (lncRNA) is another emerging critical layer of the intricate modulatory architecture for the control of the mTOR signaling circuit. Also, the production of numerous lncRNAs is induced by mTOR treatment. These findings offer new perspectives for designing novel diagnostic and therapeutic strategies. In this review, we summarize the interactions between the mTOR signaling pathway and lncRNAs in the development and progression of various types of tumors, focusing on the mechanisms of these interactions, and also discuss the potential use of lncRNAs as biomarkers and therapeutic targets for malignancies.

LncRNA HOTTIP promotes papillary thyroid carcinoma cell proliferation, invasion and migration by regulating miR-637.

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Besides, increasing evidence has demonstrated that long non-coding RNA (lncRNA) HOTTIP played a crucial role in cancer pathogenesis. MiR-637-mediated Akt1 was involved in cell growth, invasion and migration in various malignancies. This study was aimed to investigate the potential biological effect and regulatory mechanism of HOTTIP on cell proliferation, invasion and migration in PTC. Expression of HOTTIP, miR-637 and Akt1 were determined by quantitative RT-PCR (qRT-PCR) and western blotting in PTC tissues, normal tissues, PTC cells (TPC-1 and HTH83) or non-tumor thyroid cells (Nthy-ori 3-1). Cell proliferation, invasion and migration following HOTTIP knockdown were investigated in PTC cells. The target of HOTTIP was validated by RNA immunoprecipitation (RIP) and pull-down assay. Moreover, a xenograft model was performed. HOTTIP was upregulated in human PTC tissues and PTC cell lines. In addition, HOTTIP knockdown inhibited the proliferation, invasion and migration in vitro together with in vivo tumorigenesis of PTC cells. Additionally, HOTTIP knockdown downregulated Akt1 expression and suppressed cell proliferation, invasion and migration in PTC cells by regulating miR-637. In contrast, miR-637 inhibitor reversed above-mentioned tendencies caused by HOTTIP knockdown. HOTTIP is a potential oncogene in PTC and may serve as a therapeutic target for malignancies.

Radionuclide imaging of VEGFR2 in glioma vasculature using biparatopic affibody conjugate: proof-of-principle in a murine model.

Vascular endothelial growth factor receptor-2 (VEGFR2) is a key mediator of angiogenesis and therefore a promising therapeutic target in malignancies including glioblastoma multiforme (GBM). Molecular imaging of VEGFR2 expression may enable patient stratification for antiangiogenic therapy. The goal of the current study was to evaluate the capacity of the novel anti-VEGFR2 biparatopic affibody conjugate (ZVEGFR2-Bp2) for in vivo visualization of VEGFR2 expression in GBM.Methods: ZVEGFR2-Bp2 coupled to a NODAGA chelator was generated and radiolabeled with indium-111. The VEGFR2-expressing murine endothelial cell line MS1 was used to evaluate in vitro binding specificity and affinity, cellular processing and targeting specificity in mice. Further tumor targeting was studied in vivo in GL261 glioblastoma orthotopic tumors. Experimental imaging was performed.Results: [111In]In-NODAGA-ZVEGFR2-Bp2 bound specifically to VEGFR2 (KD=33±18 pM). VEGFR2-mediated accumulation was observed in liver, spleen and lungs. The tumor-to-organ ratios 2 h post injection for mice bearing MS1 tumors were approximately 11 for blood, 15 for muscles and 78 for brain. Intracranial GL261 glioblastoma was visualized using SPECT/CT. The activity uptake in tumors was significantly higher than in normal brain tissue. The tumor-to-cerebellum ratios after injection of 4 µg [111In]In-NODAGA-ZVEGFR2-Bp2 were significantly higher than the ratios observed for the 40 µg injected dose and for the non-VEGFR2 binding size-matched conjugate, demonstrating target specificity. Microautoradiography of cryosectioned CNS tissue was in good agreement with the SPECT/CT images.Conclusion: The anti-VEGFR2 affibody conjugate [111In]In-NODAGA-ZVEGFR2-Bp2 specifically targeted VEGFR2 in vivo and visualized its expression in a murine GBM orthotopic model. Tumor-to-blood ratios for [111In]In-NODAGA-ZVEGFR2-Bp2 were higher compared to other VEGFR2 imaging probes. [111In]In-NODAGA-ZVEGFR2-Bp2 appears to be a promising probe for in vivo noninvasive visualization of tumor angiogenesis in glioblastoma.

Significance of serum neural precursor cell-expressed developmentally downregulated protein 9 in melanoma.

Neural precursor cell-expressed developmentally downregulated protein 9 (NEDD9) is a promoter for various cellular functions that result in tumorigenesis. The aim of the present study was to analyse the serum levels of NEDD9 in melanoma patients in order to evaluate its prognostic, predictive and diagnostic value. Data from 112 melanoma patients were retrospectively analyzed and ELISA assays were used to measure serum NEDD9 concentration. The median serum NEDD9 levels of the patients were significantly higher compared with those of the controls. Serum NEDD9 was not found to be associated with any of the clinicopathological parameters, and was also not found to be prognostic for survival in melanoma. Therefore, serum NEDD9 may be of diagnostic value in melanoma, but its usefulness in prognosis remains controversial. The important role of NEDD9 in tumor angiogenesis necessitates efforts to elucidate its interactions with the tumor microenvironment and its potential as a therapeutic target for malignancies.

Targeting HOX/PBX dimers in cancer.

The HOX and PBX gene families encode transcription factors that have key roles in establishing the identity of cells and tissues in early development. Over the last 20 years it has become apparent that they are also dysregulated in a wide range of solid and haematological malignancies and have a predominantly pro-oncogenic function. A key mode of transcriptional regulation by HOX and PBX proteins is through their interaction as a heterodimer or larger complex that enhances their binding affinity and specificity for DNA, and there is growing evidence that this interaction is a potential therapeutic target in malignancies that include prostate, breast, renal, ovarian and lung cancer, melanoma, myeloma, and acute myeloid leukaemia. This review summarizes the roles of HOX and PBX genes in cancer and assesses the therapeutic potential of HOX/PBX dimer inhibition, including the availability of biomarkers for its application in precision medicine.

274 - Targeting of Mutant KRAS Driven Tumors by a Novel Small Molecule is Associated with ROS-Driven Mitophagy and Changes in Mitochondrial Morphology

Since its discovery in human cancers, mutant RAS remains as one of the most common genetic lesions found in many cancers such as lung, pancreatic and colorectal carcinoma. Given its widespread occurrence in cancer, mutant RAS is an unequivocal therapeutic target in malignancies and remains a subject of intense interest hitherto. Nevertheless, no successful RAS inhibitor has been identified despite the many years of unwavering effort. We recently reported the death-inducing activity of a small-molecule compound, C1, which is capable of triggering ROS-dependent autophagy-associated cell death. Using heterozygous mutant KRAS expressing HCT116 cells as well as wildtype (WT) KRAS expressing HT29, we showed that C1 selectively targets mutant KRAS expressing cells while sparing cells expressing WT KRAS. Importantly, scavenging of reactive oxygen species (ROS) as well as genetic knockdown and pharmacological inhibition of mutant KRAS and AKT suppressed C1-induced reactive oxygen species (ROS) production and restored clonogenic survival of HCT116 cells. These findings indicate that C1-induced cell death in mutant KRAS expressing cells is dependent on a paradoxical activation of mutant KRAS, downstream AKT and increased of intracellular ROS level. Nevertheless, the subsequent death-inducing pathway that stems from the increase of intracellular ROS is still poorly understood. Given the increasing evidence showing the inextricability between ROS and mitochondrial dynamics, we examined the protein machinery regulating mitochondrial morphology. Preliminary data suggests an increase in mitochondrial fission activity as indicated by increased translocation of DRP1 from cytosol to mitochondria and auto-cleavage of OPA1. In addition, we have also observed increased accumulation of LC3-II at the mitochondria indicating the presence of mitophagy. As oxidative stress is an important mediator of mitophagy, we speculate that increased mitochondrial fission activity may be an important step to ROS-induced mitophagy and subsequent cell death.

Long noncoding RNA lncTCF7, induced by IL-6/STAT3 transactivation, promotes hepatocellular carcinoma aggressiveness through epithelial-mesenchymal transition.

BackgroundAccumulating evidence suggests the pro-inflammatory cytokine interleukin-6 (IL-6) in tumor microenvironment may promote the development of hepatocellular carcinoma (HCC). However, the underlying mechanism remains largely unknown.MethodsThe expression and promoter activity of lncTCF7 were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and luciferase reporter assay. The function of the STAT3 binding site in the lncTCF7 promoter region was tested by luciferase reporter assay with nucleotide substitutions. The binding of STAT3 to the lncTCF7 promoter was confirmed by chromatin immunoprecipitation assay (CHIP) in vivo. The effects of decreasing STAT3 with small interference RNA and inhibiting STAT3 activation by small molecular inhibitor on lncTCF7 expression were also determined.ResultsWe demonstrate that IL-6 could induce lncTCF7 expression in a time- and dose-dependent manner, and we showed that IL-6 transcriptionally activated the expression of lncTCF7 in HCC cells by activating STAT3, a transcription activator which binds to promoter regions of lncTCF7. Furthermore, knocking-down STAT3 and inhibiting STAT3 activation reduced lncTCF7 expression. Importantly, RNA interference-based attenuation of lncTCF7 prevented IL-6-induced EMT and cell invasion.ConclusionThus, these data provides evidence to the existence of an aberrant IL-6/STAT3/ lncTCF7 signaling axis that leads to HCC aggressiveness through EMT induction, which could be novel therapeutic targets in malignancies.

PI3 kinase is indispensable for oncogenic transformation by the V560D mutant of c-Kit in a kinase-independent manner.

Oncogenic mutants of c-Kit are often found in mastocytosis, gastrointestinal stromal tumors and acute myeloid leukemia. The activation mechanism of the most commonly occurring mutation, D816V in exon 17 of c-Kit, has been well-studied while other mutations remain fairly uncharacterized in this respect. In this study, we show that the constitutive activity of the exon 11 mutant V560D is weaker than the D816V mutant. Phosphorylation of downstream signaling proteins induced by the ligand for c-Kit, stem cell factor, was stronger in c-Kit/V560D expressing cells than in cells expressing c-kit/D816V. Although cells expressing c-Kit/V560D showed increased ligand-independent proliferation and survival compared to wild-type c-Kit-expressing cells, these biological effects were weaker than in c-Kit/D816V-expressing cells. In contrast to cells expressing wild-type c-Kit, cells expressing c-Kit/V560D were independent of Src family kinases for downstream signaling. However, the independence of Src family kinases was not due to a Src-like kinase activity that c-Kit/D816V displayed. Point mutations that selectively block the association of PI3 kinase with c-Kit/V560D inhibited ligand-independent activation of the receptor, while inhibition of the kinase activity of PI3 kinase with pharmacological inhibitors did not affect the kinase activity of the receptor. This suggests a lipid kinase-independent key role of PI3 kinase in c-Kit/V560D-mediated oncogenic signal transduction. Thus, PI3 kinase is an attractive therapeutic target in malignancies induced by c-Kit mutations independent of its lipid kinase activity.

Advancing drug therapy for brain tumours: a current review of the pro-inflammatory peptide Substance P and its antagonists as anti-cancer agents.

Evidence for the involvement of the Substance P (SP)/NK1 receptor system in the development and progression of cancer strongly supports its potential as a therapeutic target in malignancies. Novel strategies for approaching cancer treatment are urgently required particularly with regard to tumours of the central nervous system (CNS), which are notoriously difficult to effectively treat and associated with extremely poor prognosis for many patients. This is due, in part, to the presence of the highly specialised blood-brain barrier, which is known to restrict common treatments such as chemotherapy and hinder early tumour diagnosis. Additionally, tumours of the CNS are difficult to surgically resect completely, often contributing to the resurgence of the disease many years later. Interestingly, despite the presence of the blood-brain barrier, circulating tumour cells are able to gain entry to the brain and form secondary brain tumours; however, the underlying mechanisms of this process remain unclear. Tachykinins, in particular Substance P, have been implicated in early blood-brain barrier disruption via neurogenic inflammation in a number of other CNS pathologies. Recent evidence also suggests that Substance P may play a central role in the development of CNS tumours. It has been well established that a number of tumour cells express Substance P, NK1 receptors and mRNA for the tachykinin NK1 receptor. This increase in the Substance P/NK1 receptor system is known to induce proliferation and migration of tumour cells as well as stimulate angiogenesis, thus contributing to tumour progression. Accordingly, the NK1 receptor antagonist presents a novel target for anti-cancer therapy for which a number of patents have been filed. This review will examine the role of Substance P in the development of CNS tumours and its potential application as an anti-cancer agent.

Abstract 2944: Decline in arylsulfatase B (N-acetylgalactosamine-4-sulfatase) leads to increased expression of the transmembrane glycoprotein GPNMB

Abstract The enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase), which removes 4-sulfate groups from chondroitin-4-sulfate (C4S) and dermatan sulfate, is reduced in malignant human epithelial breast, colonic, and prostate cells and tissues. Lower ARSB immunohistochemical scores have been associated with shorter intervals to recurrence in paired cases of prostate cancer and with propensity for metastasis in malignant colonic cells. The transmembrane glycoprotein GPNMB has been shown to be increased in malignant melanoma, glioblastoma multiforme, and mammary carcinoma, and is a target of antibody therapy in triple-negative breast cancers. In the ARSB-deficient mouse, cDNA microarray of prostate tissue demonstrated 9.53-fold increase in expression of GPNMB, compared to age- and gender- matched C57BL/6J wild-type controls. Measurements by ELISA of GPNMB protein in the ARSB-null mouse liver and prostate tissues showed significant increases, compared to C57BL/6J wild-type controls. In the liver of female ARSB-deficient mice, the gpnmb increased to 47.1 ± 5.7 ng/mg protein from 8.5 ± 1.2 ng/mg protein in the control mouse liver (n=5 in each group), and similar six-fold increases occurred in the male ARSB-null mouse liver. Prostate gpnmb increased more that three-fold, and serum levels in female and male null mice were significantly greater. When ARSB was silenced by siRNA in the normal human prostate stromal cell line (WPMY-1), GPNMB increased from 3.6 ± 0.3 ng/mg protein to 18.3 ± 1.1 ng/mg protein, and in the normal human prostate epithelial cell line (WPE1-NB14) from 4.8 ± 0.4 to 24.7 ± 1.6 ng/mg protein. Similarly in the human hepatic cell line, HepG2, GPNMB increased greater than five-fold. Decline in ARSB leads to increased chondroitin-4-sulfation and reduced galectin-3 binding to C4S, enabling increased nuclear translocation of galectin-3. We have shown that the increase in nuclear galectin-3 following decline in ARSB impacts on transcriptional events mediated by AP-1 in human epithelial cells, including increases in HIF-1α and versican. However, in the prostate stromal and epithelial cell lines, AP-1 inhibitors, including a c-Jun mimetic peptide and an oligonucleotide inhibitor of c-Fos DNA-binding, did not reduce the increase in GPNMB expression that followed ARSB silencing. Although the mechanism for the decline in GPNMB expression is unknown at this time, the findings support a critical role for ARSB in vital cell processes and suggest that ARSB may be useful as a therapeutic target in malignancy. Citation Format: Sumit Bhattacharyya, Leo Feferman, Joanne Kramer Tobacman. Decline in arylsulfatase B (N-acetylgalactosamine-4-sulfatase) leads to increased expression of the transmembrane glycoprotein GPNMB. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2944. doi:10.1158/1538-7445.AM2014-2944

63P - Fatty Acid Composition of Tissue Cultured Breast Carcinoma: Effect of Stearoyl-Coa Desaturase-1 (SCD-1) Inhibitor

Introduction: Stearoyl-CoA desaturase 1 (SCD1) has been introduced as a novel therapeutic target in malignancies, including breast cancer. The present study was designed to investigate the effect of pharmacologic inhibition of SCD1 on fatty acid profile in tissue explant culture of human breast cancer, and also to compare these effects with those in adjacent non-neoplastic breast tissue.

Epigenetic therapy with the histone methyltransferase EZH2 inhibitor 3-deazaneplanocin A inhibits the growth of cholangiocarcinoma cells

Enhancer of zeste homolog 2 (EZH2) is involved in malignant transformation and the biological aggressiveness of several human malignancies. Growing evidence indicates that EZH2 may be an appropriate therapeutic target for malignancies, including cholangiocarcinoma. Recently, an S-adenosyl-L-homocysteine hydrolase inhibitor, 3-deazaneplanocin A (DZNep) was shown to deplete and inhibit EZH2. The aim of this study was to determine the effect of DZNep and the combination of gemcitabine and DZNep in cholangiocarcinoma cells. The effects of DZNep and its combination with gemcitabine were assessed in the cholangiocarcinoma cell lines RBE and TFK-1. DZNep depleted the cellular levels of EZH2 and inhibited the associated histone H3 lysine 27 trimethylation. DZNep treatment resulted in the inhibition of proliferation in the cholangiocarcinoma cell lines, and the combination of DZNep and gemcitabine showed synergistic inhibition of cell proliferation. DZNep induced apoptosis and G1 phase cell cycle arrest in cholangiocarcinoma cells, and the combination of DZNep and gemcitabine enhanced the induced apoptosis and G1 arrest when compared with gemcitabine alone. Inhibition of cell proliferation by DZNep was partially associated with upregulation of p16INK4a and p17KIP1. The present study shows that DZNep inhibits cell proliferation by inducing G1 arrest and apoptosis. These results indicate that an epigenetic therapy that pharmacologically targets EZH2 via DZNep may constitute a novel approach for the treatment of cholangiocarcinoma.

Mitochondrial matrix proteases as novel therapeutic targets in malignancy

Although mitochondrial function is often altered in cancer, it remains essential for tumor viability. Tight control of protein homeostasis is required for the maintenance of mitochondrial function, and the mitochondrial matrix houses several coordinated protein quality control systems. These include three evolutionarily conserved proteases of the AAA+ superfamily-the Lon, ClpXP and m-AAA proteases. In humans, these proteases are proposed to degrade, process and chaperone the assembly of mitochondrial proteins in the matrix and inner membrane involved in oxidative phosphorylation, mitochondrial protein synthesis, mitochondrial network dynamics and nucleoid function. In addition, these proteases are upregulated by a variety of mitochondrial stressors, including oxidative stress, unfolded protein stress and imbalances in respiratory complex assembly. Given that tumor cells must survive and proliferate under dynamic cellular stress conditions, dysregulation of mitochondrial protein quality control systems may provide a selective advantage. The association of mitochondrial matrix AAA+ proteases with cancer and their potential for therapeutic modulation therefore warrant further consideration. Although our current knowledge of the endogenous human substrates of these proteases is limited, we highlight functional insights gained from cultured human cells, protease-deficient mouse models and other eukaryotic model organisms. We also review the consequences of disrupting mitochondrial matrix AAA+ proteases through genetic and pharmacological approaches, along with implications of these studies on the potential of these proteases as anticancer therapeutic targets.

Abstract 2190: cIAP2 as a therapeutic target in malignancies.

Abstract [Introduction] Inhibition of the apoptotic pathway is one of the factors that may be responsible for carcinogenesis and drug resistance, and the inhibitor of apoptosis protein (IAP) family is thought to prevent apoptosis through inhibition of caspases and pro-caspases and may affect anti-cancer drug sensitivity. [Purposes] The purpose of this study is to clarify the roles of cellular inhibitor of apoptosis 2 (cIAP2) gene, which is a member of IAP family, on apoptosis and 5-FU sensitivity in cancer cells. [Methods and Results] The expression profiles of human colon cancer cell line DLD-1, its 5-FU-resistant subclone DLD-1/FU and further 21 types of colon cancer cell lines were compared. 50% inhibitory concentration (IC50) of 5-FU in DLD-1/FU was over 100 times higher than that in DLD-1. With the analysis of expression profiles among 23 genes, we found that cIAP2 gene was up-regulated in DLD-1/FU compared with DLD-1 and other cell lines with low IC50. Next, the role of the cIAP2 gene was investigated for 5-FU resistance using RNA interference. The down-regulation of cIAP2 efficiently enhanced 5-FU sensitivity, the activation of caspase 3/7 and apoptosis under exposure to 5-FU. The immunohistochemistry of cIAP2 in cancer and corresponding normal tissues from colorectal cancer patients in stage III revealed that cIAP2 was more frequently expressed in cancer tissues than in normal tissues, and cIAP2-positive patients had a trend toward early recurrence after 5-FU-based chemotherapy. [Conclusion] IAPs are reported to be abnormally regulated and expressed in the majority of human malignancies at elevated levels. Among them, cIAP2 should be a possible therapeutic target in malignancies, especially in colorectal cancer. Citation Format: Koh Miura, Hideaki Karasawa, Wataru Fujibuchi, Shinobu Ohnuma, Michiaki Unno. cIAP2 as a therapeutic target in malignancies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2190. doi:10.1158/1538-7445.AM2013-2190

Epigenetic therapy with 3-deazaneplanocin A, an inhibitor of the histone methyltransferase EZH2, inhibits growth of non-small cell lung cancer cells

EZH2 (enhancer of zeste homolog 2) is the catalytic subunit of PRC2 (polycomb repressive complex 2), which mediates histone methyltransferase activity and functions as transcriptional repressor involved in gene silencing. EZH2 is involved in malignant transformation and biological aggressiveness of several human malignancies. We previously demonstrated that non-small cell lung cancers (NSCLCs) also overexpress EZH2 and that high expression of EZH2 correlates with poor prognosis. Growing evidence indicates that EZH2 may be an appropriate therapeutic target in malignancies, including NSCLCs. Recently, an S-adenosyl-l-homocysteine hydrolase inhibitor, 3-Deazaneplanocin A (DZNep), has been shown to deplete and inhibit EZH2. The aim of this study was to determine the effect of DZNep in NSCLC cells. Knockdown of EZH2 by small-interfering RNA (siRNA) resulted in decreased growth of four NSCLC cell lines. MTT assays demonstrated that DZNep treatment resulted in dose-dependent inhibition of proliferation in the NSCLC cell lines with a half maximal inhibitory concentration (IC50) ranging from 0.08 to 0.24μM. Immortalized but non-cancerous bronchial epithelial and fibroblast cell lines were less sensitive to DZNep than the NSCLC cell lines. Soft agarose assays demonstrated that anchorage-independent growth was also reduced in all three NSCLC cell lines that were evaluated using this assay. Flow cytometry analysis demonstrated that DZNep induced apoptosis and G1 cell cycle arrest in NSCLC cells, which was partially associated with cyclin A decrease and p27Kip1 accumulation. DZNep depleted cellular levels of EZH2 and inhibited the associated histone H3 lysine 27 trimethylation. These results indicated that an epigenetic therapy that pharmacologically targets EZH2 via DZNep may constitute a novel approach to treatment of NSCLCs.

CIAP2 as a therapeutic target in colorectal cancer and other malignancies

Colorectal cancer is one of the most common malignancies worldwide and 70% of tumors are resectable, but patients with metastatic diseases cannot be cured with current treatment modalities. Inhibition of the apoptotic pathway is one of the factors that may be responsible for carcinogenesis and drug resistance, and the inhibitor of apoptosis protein (IAP) family is thought to prevent apoptosis through inhibition of direct caspases and pro-caspases. Recently an increasing amount of evidence has been accumulated regarding cIAP2 and other IAP proteins of the antiapoptotic pathway and NF-κB signal transduction. IAPs are abnormally regulated and expressed in the majority of human malignancies at elevated levels. As a result, they have recently been reported to be therapeutic targets. The downregulation of cIAP2 efficiently enhances apoptosis through the activation of caspase 3/7 and 5-fluorouracil (5-FU) sensitivity in colorectal cancer cells exposed to 5-FU. This report reviews the evidence for cIAP2 and other IAP molecules as a therapeutic target for malignancies including colorectal cancer. So far, the information on colorectal cancer is limited; so this study includes other malignancies as well, in order to summarize the current knowledge of drug development targeting IAP molecules and provide an overview of the future course.

Clusterin: a new therapeutic target for malignancies

Clusterin is a multifunctional protein which plays important roles in various pathophysiologi-cal processes. Close relation between clusterin and apoptosis of malignancies is found in many studies. Clusterin is expected to become a new therapeutic target for malignancies. Studies that focus on clusterin as a therapeutic target for malignancies have become a hot issue in oncology research. Key words: Neoplasms; Clusterin; Therapy