Tumor Progression In Xenograft Models Research Articles

Anticancer function of microRNA‐30e is mediated by negative regulation of HELLPAR, a noncoding macroRNA, and genes involved in ubiquitination and cell cycle progression in prostate cancer

Prostate cancer (PCa) progression relies on androgen receptor (AR) function, making AR a top candidate for PCa therapy. However, development of drug resistance is common, which eventually leads to development of castration‐resistant PCa. This warrants a better understanding of the pathophysiology of PCa that facilitates the aberrant activation of key signaling pathways including AR. MicroRNAs (miRNAs) function as regulators of cancer progression as they modulate various cellular processes. Here, we demonstrate a multidimensional function of miR‐30e through the regulation of genes involved in various signaling pathways. We noted loss of miR‐30e expression in prostate tumors, which, when restored, led to cell cycle arrest, induction of apoptosis, improved drug sensitivity of PCa cells and reduced tumor progression in xenograft models. We show that experimental upregulation of miR‐30e reduces expression of mRNAs including AR, FBXO45, SRSF7 and MYBL2 and a novel long noncoding RNA (lncRNA) HELLPAR, which are involved in cell cycle, apoptosis and ubiquitination, and the effects could be rescued by inhibition of miR‐30e expression. RNA immunoprecipitation analysis confirmed direct interactions between miR‐30e and its RNA targets. We noted a newly identified reciprocal relationship between miR‐30e and HELLPAR, as inhibition of HELLPAR improved stabilization of miR‐30e. Transcriptome profiling and quantitative real‐time PCR (qRT‐PCR) validation of miR‐30e‐expressing PCa cells showed differential expression of genes involved in cell cycle progression, apoptosis and ubiquitination, which supports our in vitro study. This study demonstrates an integrated function of miR‐30e on dysregulation of miRNA/lncRNA/mRNA axes that may have diagnostic and therapeutic significance in aggressive PCa.

ERK inactivation enhances stemness of NSCLC cells via promoting Slug-mediated epithelial-to-mesenchymal transition.

Rationale: The mitogen-activated protein kinase pathway (MAPK) is one of the major cancer-driving pathways found in non-small cell lung cancer (NSCLC) patients. ERK inhibitors (ERKi) have been shown to be effective in NSCLC patients with MAPK pathway mutations. However, like other MAPK inhibitors, ERKi rarely confers complete and durable responses. The mechanism of tumor relapse after ERKi treatment is yet defined.Methods: To best study the mechanism of tumor relapse after ERK inhibitor treatment in NSCLC patients, we treated various NSCLC cell lines and patient-derived xenograft (PDX) with ERK inhibitors and evaluated the enrichment of cancer stem cell (CSC) population. We then performed a Next-generation sequencing (NGS) to identify potential pathways that are responsible for the CSC enrichment. Further, the involvement of specific pathways was examined using molecular and cellular methods. Finally, we investigated the therapeutic benefits of ERKi treatment combined with JAK/STAT pathway inhibitor using cellular and xenograft NSCLC models.Results: We found that ERKi treatment expands the CSC population in NSCLC cells through enhanced epithelial-to-mesenchymal transition (EMT)-mediated cancer cell dedifferentiation. Mechanistically, ERK inactivation induces EMT via pSTAT3-mediated upregulation of Slug, in which, upregulation of miR-204 and downregulation of SPDEF, a transcription repressor of Slug, are involved. Finally, the JAK/STAT pathway inhibitor Ruxolitinib blocks the ERK inactivation-induced EMT and CSC expansion, as well as the tumor progression in xenograft models after ERKi treatment.Conclusions: This study revealed a potential tumor relapse mechanism of NSCLC after ERK inhibition through the unintended activation of the EMT program, ascertained the pSTAT-miR-204-SPDEF-Slug axis, and provided a promising combination inhibitor approach to prevent tumor relapse in patients.

Suppressing MDSC Infiltration in Tumor Microenvironment Serves as an Option for Treating Ovarian Cancer Metastasis.

It is still a big puzzle how ovarian cancer cells and the tumor microenvironment (TME) attract lymphocytes infiltration for facilitating metastasis, a leading cause of death from gynecological malignancies. Using genome-wide LncRNA microarray assay, here we report that a LncRNA associated with ovarian cancer metastasis (LncOVM) is highly correlated with poor prognosis and survival. LncOVM interacts with and stabilizes PPIP5K2 by suppressing ubiquitinated degradation to promote complement C5 secretion from ovarian cancer cells. The TME-enriched complement C5 attracts myeloid-derived suppressor cells (MDSCs) infiltration in TME to facilitate metastasis. Knockdown of LncOVM or PPIP5K2 inhibits tumor progression in xenograft models. Application of C5aR antibody or inhibitor (CCX168) inhibits MDSC recruitment and restores the suppression of tumorigenesis and metastasis in vivo. Our study reveals that suppression of ovarian cancer metastasis can be achieved by targeting MDSC infiltration in TME through disrupting LncOVM-PPIP5K2-complement axis, providing an option for treating ovarian cancer patients.

Areca nut extract (ANE) inhibits the progression of hepatocellular carcinoma cells via activation of ROS production and activation of autophagy

Hepatocellular carcinoma (HCC) is a worldwide health problem. Currently, there is no effective therapeutic strategy for HCC patients. Chewing areca nut is closely associated with oral cancer and liver cirrhosis. The therapeutic effect of areca nut extract (ANE) on HCC is unknown. Our results revealed that ANE treatment caused a reduction in cell viability and an increase in cell apoptosis and suppressed tumor progression in xenograft models. ANE-treated didn't induce liver tumor in nude mice. For mechanism dissection, ANE treatment caused ROS-mediated autophagy and lysosome formation. Pretreatment with an ROS inhibitor, aminoguanidine hemisulfate (AGH), abolished ANE-induced ROS production. ANE treated cells caused an increase in light chain 3 (LC3)-I to -II conversion, anti-thymocyte globulin 5+12 (ATG5+12), and beclin levels, and apoptosis related-protein changes (an increases in BAX, cleaved poly(ADP-ribose) polymerase (c-PARP), and a decrease in the Bcl-2 level). In conclusion, our study demonstrated that the ANE may be a new potential compound for HCC therapy.

ABL001, a Bispecific Antibody Targeting VEGF and DLL4, with Chemotherapy, Synergistically Inhibits Tumor Progression in Xenograft Models.

Delta-like-ligand 4 (DLL4) is a promising target to augment the effects of VEGF inhibitors. A simultaneous blockade of VEGF/VEGFR and DLL4/Notch signaling pathways leads to more potent anti-cancer effects by synergistic anti-angiogenic mechanisms in xenograft models. A bispecific antibody targeting VEGF and DLL4 (ABL001/NOV1501/TR009) demonstrates more potent in vitro and in vivo biological activity compared to VEGF or DLL4 targeting monoclonal antibodies alone and is currently being evaluated in a phase 1 clinical study of heavy chemotherapy or targeted therapy pre-treated cancer patients (ClinicalTrials.gov Identifier: NCT03292783). However, the effects of a combination of ABL001 and chemotherapy on tumor vessels and tumors are not known. Hence, the effects of ABL001, with or without paclitaxel and irinotecan were evaluated in human gastric or colon cancer xenograft models. The combination treatment synergistically inhibited tumor progression compared to each monotherapy. More tumor vessel regression and apoptotic tumor cell induction were observed in tumors treated with the combination therapy, which might be due to tumor vessel normalization. Overall, these findings suggest that the combination therapy of ABL001 with paclitaxel or irinotecan would be a better clinical strategy for the treatment of cancer patients.

Upregulation of PACE4 in prostate cancer is not dependent on E2F transcription factors.

Recent studies in prostate cancer have identified PACE4, a proprotein convertase enzyme, as an emerging therapeutic target. Inhibition of PACE4-altCT, an oncogenic isoform of PACE4, using molecular or pharmacological approaches results in decreased cell proliferation and tumor progression in xenograft models. Although several validations have confirmed PACE4-altCT as a novel therapeutic target, the transcriptional regulation of PACE4 isoforms and mechanism of action remain a challenge. Previously, it has been reported that the human PACE4 promoter possesses potential binding sites for the E2F family of transcription factors, all of which are involved in cell cycle regulation and synthesis of DNA in mammalian cells. Therefore, we attempted to conduct in-depth evaluation of E2Fs on PACE4 and PACE4 isoform expression in prostate cancer. We conducted in vitro molecular silencing studies in various prostate cancer cell lines and determined the change in PACE4 expression levels. The results clearly show that the E2Fs alone do not alter PACE4 expression.

Abstract 280: Synthetic lethality of KDM1A and mTOR inhibitors: A novel combination therapy for endometrial cancer

Abstract Background: Endometrial cancer (EC) is the sixth most common cancer in women. Annually 63,230 new cases are diagnosed with 11,350 deaths estimated in the USA. Currently, advanced EC therapies remain palliative and new therapeutic strategies are urgently needed. Common risk factors include exposure to high levels of estrogen, obesity, and alterations in genetic and epigenetic factors. The lysine-specific demethylase-1A (KDM1A/LSD1) regulates gene expression programs by changing the epigenetic histone marks at the gene promoters. Emerging studies provided the evidence that KDM1A is overexpressed in EC. In studies examining the synthetic lethality of KDM1A inhibition on chemotherapy drug sensitivity, we made an unexpected discovery that KDM1A inhibition potentiate activity of mTOR inhibitors. In this study, we tested the hypothesis that inhibition of KDM1A could sensitize EC to mTOR inhibitor therapy. Methods: To study the significance of KDM1A inhibition on chemotherapy drug sensitivity, we performed MTT assays to screen 119 FDA approved drugs using KDM1A knockdown HEC1A and RL95 EC cell lines. Effect of KDM1A knockdown or KDM1A inhibitor (NCD-38) therapy on EC cells was examined using MTT cell viability assays and clonogenic survival assays. The effect on cell migration was examined using scratch wound healing assay. Mechanistic studies were conducted using RNA-seq, western blot, qRT-PCR, and IHC analysis. The in vivo efficacy of NCD-38 and sirolimus on EC progression was studied using mouse xenograft models. Results: Studies using 119 FDA approved drugs identified that mTOR inhibitors sirolimus and temsirolimus has potent synthetic lethality on KDM1A knockdown cells compared to control cells. Cell viability and survival assays demonstrated that KDM1A knockdown or inhibition in combination with sirolimus synergistically reduced cell viability and the survival of EC cells. Further, combination of KDM1A inhibitor and sirolimus reduced the migration of EC cells. Western blot analysis demonstrated that knockdown or inhibition of KDM1A attenuated the activation of mTOR signaling cascade in EC cells. RNA-seq and gene set enrichment analysis identified the down regulation of E2F pathway and DNA replication pathways in KDM1A and mTOR inhibitor treated cells compared to control cells. Further, combination of NCD-38 and sirolimus significantly reduced the in vivo tumor progression in xenograft models. IHC analysis of tumors revealed the downregulation of proliferation marker Ki67 and phosphorylation of mTOR signaling molecules in combination treated tumors compared to vehicle treated tumors. Conclusions: The results from these studies provide compelling evidence that KDM1A inhibition sensitizes EC cells to mTOR inhibitors, and the use of KDM1A inhibitor in conjunction with mTOR inhibitors may be an attractive therapy for advanced EC patients. Citation Format: Prabhakar Pitta-Venkata, Bridgitte Palacios, Yihong Chen, Suryavathi Viswanadhapalli, Uday P. Pratap, Yiliao Luo, Mengxing Li, Kristin Altwegg, Xiaonan Li, Takayoshi Suzuki, Rajeshwar Rao Tekmal, Edward Kost, Gangadhara Reddy Sareddy. Synthetic lethality of KDM1A and mTOR inhibitors: A novel combination therapy for endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 280.

Intracellular pH imaging in cancer cells in vitro and tumors in vivo using the new genetically encoded sensor SypHer2

BackgroundMeasuring intracellular pH (pHi) in tumors is essential for the monitoring of cancer progression and the response of cancer cells to various treatments. The purpose of the study was to develop a method for pHi mapping in living cancer cells in vitro and in tumors in vivo, using the novel genetically encoded indicator, SypHer2. MethodsA HeLa Kyoto cell line stably expressing SypHer2 in the cytoplasm was used, to perform ratiometric (dual excitation) imaging of the probe in cell culture, in 3D tumor spheroids and in tumor xenografts in living mice. ResultsUsing SypHer2, pHi was demonstrated to be 7.34±0.11 in monolayer HeLa cells in vitro under standard cultivation conditions. An increasing pHi gradient from the center to the periphery of the spheroids was displayed. We obtained fluorescence ratio maps for HeLa tumors in vivo and ex vivo. Comparison of the map with the pathomorphology and with hypoxia staining of the tumors revealed a correspondence of the zones with higher pHi to the necrotic and hypoxic areas. ConclusionsOur results demonstrate that pHi imaging with the genetically encoded pHi indicator, SypHer2, can be a valuable tool for evaluating tumor progression in xenograft models. General significanceWe have demonstrated, for the first time, the possibility of using the genetically encoded sensor SypHer2 for ratiometric pH imaging in cancer cells in vitro and in tumors in vivo. SypHer2 shows great promise as an instrument for pHi monitoring able to provide high accuracy and spatiotemporal resolution.

Efficacy of Combined Histone Deacetylase and Checkpoint Kinase Inhibition in a Preclinical Model of Human Burkitt Lymphoma.

Checkpoint kinase inhibition has been studied as a way of enhancing the effectiveness of DNA-damaging agents. More recently, histone deacetylase inhibitors have shown efficacy in several cancers, including non-Hodgkin lymphoma. To evaluate the effectiveness of this combination for the treatment of lymphoma, we examined the combination of AR42, a histone deacetylase inhibitor, and checkpoint kinase 2 (CHEK2) inhibitor II in vitro and in vivo. The combination resulted in up to 10-fold increase in potency in five Burkitt lymphoma cell lines when compared with either drug alone. Both drugs inhibited tumor progression in xenograft models, but the combination was more effective than either agent alone, resulting in regression of established tumors. No toxicity was observed. These results suggest that the combination of histone deacetylase inhibition and checkpoint kinase inhibition represent an effective and nontoxic treatment option that should be further explored in preclinical and clinical studies.

Abstract C173: APE1/Ref-1-STAT3 dual-targeting synergize to effectively inhibit pancreatic cancer cell survival.

Abstract Pancreatic cancer remains a largely incurable disease, with patients facing the worst 5-year survival rate of any cancer. The challenge is to identify the molecular effectors that critically regulate the survival of pancreatic ductal adenocarcinoma (PDAC) cells, to devise effective molecular-targeted strategies that can prevent or minimize the selection of resistant tumor variants, and overcome the protective role of the tumor-associated fibrosis and stroma. Increasing evidence supports the need for strategies targeting multiple molecular effectors in PDAC. Thus, a strategy is to identify critical molecules that regulate multiple signaling mediators (as transcription factors), and on intracellular mechanisms with direct effects on multiple pathways (as antioxidant and redox mediators) critical for PDAC functions. APE1/Ref-1 is a dual function protein, which in addition to DNA repair activity also exerts redox control of transcription factors, including NF- B, p53, AP-1, CREB, HIF-1 and others. Treatment with E3330, a unique small molecule redox signaling inhibitor that recognizes an alternate, redox active conformation of APE1/Ref-1, markedly inhibits the DNA binding and transcriptional activity of NF-κB, AP-1, and HIF-1. Our previous work established APE1/Ref-1 as a potential molecular target in pancreatic cancer. We demonstrated that human adenocarcinoma and peri-pancreatic metastases exhibit increased APE1/Ref-1 expression, and blocking APE1/Ref-1 redox activity delays tumor progression in xenograft models of PDAC, including patient-derived tumor cells. STAT3 is a transcription factor that regulates critical cell functions and has been shown to play important roles in several cancers. STAT3 signaling has been implicated in pancreatic cancer biology, namely by mediating or regulating cell survival, proliferation, tumor angiogenesis and metastasis. Although STAT3 signaling can be engaged and modulated by different processes, the mechanisms regulating STAT3 transcriptional activity in PDAC cells are largely unknown, namely the impact of oxidative stress and its redox status. A recent report demonstrated that STAT3 activity is under redox control and identified the critical oxidation-sensitive cysteines in the STAT3 DNA binding domain. However, the modifier of STAT3 which converts it from an oxidized to a reduced form was not identified. It has been shown that APE1/Ref-1 physically interacts with STAT3 on the VEGF promoter and enhances IL-6-induced DNA binding activity of STAT3 in HepG2 cells. However, it is unknown whether APE-1/Ref-1 is involved in the redox control of STAT3 activity, and whether the cellular redox status affects STAT3 signaling in PDAC cells. Here, we demonstrate that APE1/Ref-1 redox activity regulates the STAT3 DNA binding and transcriptional activity using gene silencing, overexpression of WT or redox-defective APE1/Ref-1, and redox-selective pharmacological inhibition. Blockade of APE1/Ref-1 redox synergizes with STAT3 selective antagonists to markedly inhibit the proliferation and survival of human PDAC cells, inducing cell apoptosis. These studies identify the mechanism by which APE1/Ref-1 regulates STAT3 signaling, and establishes the rationale for the development of APE1/STAT3 dual-targeting strategies for the treatment of pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C173.

1748 ANGIOTENSIN II TYPE 1 RECEPTOR AND MICROVESSEL DENSITY PREDICT THE EARLY INTRAVESICAL RECURRENCE IN BLADDER CANCER

You have accessJournal of UrologyBladder Cancer: Superficial1 Apr 20111748 ANGIOTENSIN II TYPE 1 RECEPTOR AND MICROVESSEL DENSITY PREDICT THE EARLY INTRAVESICAL RECURRENCE IN BLADDER CANCER Suguru Shirotake, Akira Miyajima, Takeo Kosaka, Takahiro Maeda, Nobuyuki Tanaka, Eiji Kikuchi, and Mototsugu Oya Suguru ShirotakeSuguru Shirotake Tokyo, Japan More articles by this author , Akira MiyajimaAkira Miyajima Tokyo, Japan More articles by this author , Takeo KosakaTakeo Kosaka Tokyo, Japan More articles by this author , Takahiro MaedaTakahiro Maeda Tokyo, Japan More articles by this author , Nobuyuki TanakaNobuyuki Tanaka Tokyo, Japan More articles by this author , Eiji KikuchiEiji Kikuchi Tokyo, Japan More articles by this author , and Mototsugu OyaMototsugu Oya Tokyo, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2075AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES It has recently been reported that the angiotensin II type 1 receptor (AT1R) is expressed in several tumors and involved in tumor angiogenesis. We have previously reported that AT1R was expressed in bladder cancer (BCa) cells in vivo and that AT1R blockade inhibited tumor progression in xenograft models. However, no study has investigated the role of AT1R expression and microvessel density (MVD) in bladder cancer. The aim of the present study was to examine whether AT1R expression and MVD in BCa correlate with a particular focus on intravesical recurrence and progression. METHODS Clinical tissue samples were obtained from 108 patients (non-muscle invasive BCa (NMIBC) 79 cases and muscle invasive BCa (MIBC) 29 cases, low grade 54 cases and high grade 54 cases) undergoing primary TUR for bladder tumor between January 1995 and December 2002. The mean duration of follow-up of the cases was 84 months (range, 26–174 months). Histologically, all specimens were diagnosed as urothelial carcinoma. AT1R and CD34 as MVD were immunostained for all specimens. Clinical and pathological characteristics were reviewed retrospectively. RESULTS MVD was higher in MIBC (34.4 ± 4.1 /0.25 mm2) than in NMIBC (17.4 ± 1.1 /0.25 mm2, p<0.0001). AT1R expression was higher in MIBC (p=0.0004) and high grade (p=0.0063) than in NMIBC and low grade. The higher expression of AT1R was significantly associated with MVD (p<0.05). In NMIBC, univariate analysis could not demonstrate that AT1R expression and MVD were correlated with the progression to MIBC (p=0.27, p=0.17), however, the factors significantly affecting intravesical recurrence-free survival (iRFS) in univariate analysis were AT1R (p=0.02), MVD (p<0.0001), tumor multiplicity (p=0.0007), and BCG intravesical instillation after TUR (p=0.0026). Multivariate analysis revealed that tumor multiplicity and no BCG treatment after TUR were independent predictors of 5-year iRFS, while AT1R (p=0.001, HR 7.8, 95%CI 2.26–26.98) and MVD (p=0.01, HR 4.0, 95%CI 1.38–11.51) were independent predictors of 1-year iRFS. Furthermore multivariate analysis revealed that AT1R and MVD were independent predictors of RFS after BCG treatment in 26 cases of NMIBC (p=0.0012, HR 3.2, 95%CI 0.55–19.25, p=0.0011, HR 4.4, 95%CI 0.90–21.18). CONCLUSIONS Our results suggest that AT1R expression as well as MVD was related to early intravesical recurrence in NMIBC, and that NMIBC cases with higher MVD and AT1R may require stricter follow-up for earlier intravesical recurrence and the response to BCG intravesical instillation. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e701-e702 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Suguru Shirotake Tokyo, Japan More articles by this author Akira Miyajima Tokyo, Japan More articles by this author Takeo Kosaka Tokyo, Japan More articles by this author Takahiro Maeda Tokyo, Japan More articles by this author Nobuyuki Tanaka Tokyo, Japan More articles by this author Eiji Kikuchi Tokyo, Japan More articles by this author Mototsugu Oya Tokyo, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

The Tetraspanin CD151 Is Required for Met-dependent Signaling and Tumor Cell Growth

CD151, a transmembrane protein of the tetraspanin family, is implicated in the regulation of cell-substrate adhesion and cell migration through physical and functional interactions with integrin receptors. In contrast, little is known about the potential role of CD151 in controlling cell proliferation and survival. We have previously shown that β4 integrin, a major CD151 partner, not only acts as an adhesive receptor for laminins but also as an intracellular signaling platform promoting cell proliferation and invasive growth upon interaction with Met, the tyrosine kinase receptor for hepatocyte growth factor (HGF). Here we show that RNAi-mediated silencing of CD151 expression in cancer cells impairs HGF-driven proliferation, anchorage-independent growth, protection from anoikis, and tumor progression in xenograft models in vivo. Mechanistically, we found that CD151 is crucially implicated in the formation of signaling complexes between Met and β4 integrin, a known amplifier of HGF-induced tumor cell growth and survival. CD151 depletion hampered HGF-induced phosphorylation of β4 integrin and the ensuing Grb2-Gab1 association, a signaling pathway leading to MAPK stimulation and cell growth. Accordingly, CD151 knockdown reduced HGF-triggered activation of MAPK but not AKT signaling cascade. These results indicate that CD151 controls Met-dependent neoplastic growth by enhancing receptor signaling through β4 integrin-mediated pathways, independent of cell-substrate adhesion.

The Role of PPARγ in the Cyclooxygenase Pathway in Lung Cancer

Decreased expression of peroxisome proliferator activated receptor-γ (PPARγ) and high levels of the proinflammatory enzyme cyclooxygenase-2 (COX-2) have been observed in many tumor types. Both reduced (PPARγ) expression and elevated COX-2 within the tumor are associated with poor prognosis in lung cancer patients, and recent work has indicated that these signaling pathways may be interrelated. Synthetic (PPARγ) agonists such as the thiazolidinedione (TZD) class of anti-diabetic drugs can decrease COX-2 levels, inhibit growth of non-small-cell lung cancer (NSCLC) cells in vitro, and block tumor progression in xenograft models. TZDs alter the expression of COX-2 and consequent production of the protumorigenic inflammatory molecule prostaglandin E2 (PGE2) through both (PPARγ) dependent and independent mechanisms. Certain TZDs also reduce expression of PGE2 receptors or upregulate the PGE2 catabolic enzyme 15-prostaglandin dehydrogenase. As several COX-2 enzymatic products have antitumor properties and specific COX-2 inhibition has been associated with increased risk of adverse cardiac events, directly reducing the effects or concentration of PGE2 may provide a more safe and effective strategy for lung cancer treatment. Understanding the mechanisms underlying these effects may be helpful for designing anticancer therapies. This article summarizes recent research on the relationship between (PPARγ), TZDs, and the COX-2/PGE2 pathways in lung cancer.

CF101 enhances the apoptotic effect of chemotherapy on colon and pancreatic carcinoma cell lines: Molecular mechanisms involved

3173 Background: The A3 adenosine Gi protein-coupled receptor is highly expressed in tumor as compared to normal cells. Targeting the A3 adenosine receptor (A3AR) with the highly selective agonist CF101 induces growth inhibition of colon carcinoma and other tumor cell types via down-regulation of PKB/Akt and NF-kB. High expression level of these two signaling proteins is associated with the development of chemo-resistance in various tumor cell types, thus it prompted us to explore whether CF101 would enhance the anti-tumor effect of chemotherapy. Methods: HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cell lines were used. Cells were cultured for 48h in the presence of 5-FU (0.625 μM), oxaliplatin (0.5 μM) or gemcitabine (0.02 mM) and CF101 (10nM) was introduced for an additional 24h. Proliferation assay (MTT) and protein expression profile were conducted at 72h. In vivo studies included nude mice that were inoculated with the tumor cells. Treatment with chemotherapy alone or in combination with CF101 was initiated when tumor reached a size of 150 mm3. Tumor size was monitored each 4 days and study was terminated after 35 days. Results: In HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cells, CF101 enhanced the cytotoxic effect of 5-FU, oxaliplatin and gemcitabine in vitro by 20% 25% and 32% respectively (P<0.01). The molecular mechanism involved a marked decrease in the level of PKB/Akt and NF-kB followed by an increase in caspase-3 level resulting in apoptosis, as observed by DNA ladder analysis. In xenograft models of HCT-116 colon carcinoma, CF101 doubled the time to tumor progression (p<0.002) when given in combination with 5-FU. Conclusions: CF101 enhanced the chemotherapeutic effect in vitro and doubled the time to tumor progression in xenograft models. It is thus suggested that CF101 may be further developed as an add-on treatment to chemotherapy for colon and pancreatic carcinoma. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Can-Fite BioPharma

CF101 enhances the apoptotic effect of chemotherapy on colon and pancreatic carcinoma cell lines: Molecular mechanisms involved

3173 Background: The A3 adenosine Gi protein-coupled receptor is highly expressed in tumor as compared to normal cells. Targeting the A3 adenosine receptor (A3AR) with the highly selective agonist CF101 induces growth inhibition of colon carcinoma and other tumor cell types via down-regulation of PKB/Akt and NF-kB. High expression level of these two signaling proteins is associated with the development of chemo-resistance in various tumor cell types, thus it prompted us to explore whether CF101 would enhance the anti-tumor effect of chemotherapy. Methods: HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cell lines were used. Cells were cultured for 48h in the presence of 5-FU (0.625 μM), oxaliplatin (0.5 μM) or gemcitabine (0.02 mM) and CF101 (10nM) was introduced for an additional 24h. Proliferation assay (MTT) and protein expression profile were conducted at 72h. In vivo studies included nude mice that were inoculated with the tumor cells. Treatment with chemotherapy alone or in combination with CF101 was initiated when tumor reached a size of 150 mm3. Tumor size was monitored each 4 days and study was terminated after 35 days. Results: In HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cells, CF101 enhanced the cytotoxic effect of 5-FU, oxaliplatin and gemcitabine in vitro by 20% 25% and 32% respectively (P<0.01). The molecular mechanism involved a marked decrease in the level of PKB/Akt and NF-kB followed by an increase in caspase-3 level resulting in apoptosis, as observed by DNA ladder analysis. In xenograft models of HCT-116 colon carcinoma, CF101 doubled the time to tumor progression (p<0.002) when given in combination with 5-FU. Conclusions: CF101 enhanced the chemotherapeutic effect in vitro and doubled the time to tumor progression in xenograft models. It is thus suggested that CF101 may be further developed as an add-on treatment to chemotherapy for colon and pancreatic carcinoma. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Can-Fite BioPharma