Gastrointestinal Cancer Cells Research Articles

Cyclopamine tartrate, an inhibitor of Hedgehog signaling, strongly interferes with mitochondrial function and suppresses aerobic respiration in lung cancer cells.

BackgroundAberrant Hedgehog (Hh) signaling is associated with the development of many cancers including prostate cancer, gastrointestinal cancer, lung cancer, pancreatic cancer, ovarian cancer, and basal cell carcinoma. The Hh signaling pathway has been one of the most intensely investigated targets for cancer therapy, and a number of compounds inhibiting Hh signaling are being tested clinically for treating many cancers. Lung cancer causes more deaths than the next three most common cancers (colon, breast, and prostate) combined. Cyclopamine was the first compound found to inhibit Hh signaling and has been invaluable for understanding the function of Hh signaling in development and cancer. To find novel strategies for combating lung cancer, we decided to characterize the effect of cyclopamine tartrate (CycT), an improved analogue of cyclopamine, on lung cancer cells and its mechanism of action.MethodsThe effect of CycT on oxygen consumption and proliferation of non-small-cell lung cancer (NSCLC) cell lines was quantified by using an Oxygraph system and live cell counting, respectively. Apoptosis was detected by using Annexin V and Propidium Iodide staining. CycT’s impact on ROS generation, mitochondrial membrane potential, and mitochondrial morphology in NSCLC cells was monitored by using fluorometry and fluorescent microscopy. Western blotting and fluorescent microscopy were used to detect the levels and localization of Hh signaling targets, mitochondrial fission protein Drp1, and heme-related proteins in various NSCLC cells.ResultsOur findings identified a novel function of CycT, as well as another Hh inhibitor SANT1, to disrupt mitochondrial function and aerobic respiration. Our results showed that CycT, like glutamine depletion, caused a substantial decrease in oxygen consumption in a number of NSCLC cell lines, suppressed NSCLC cell proliferation, and induced apoptosis. Further, we found that CycT increased ROS generation, mitochondrial membrane hyperpolarization, and mitochondrial fragmentation, thereby disrupting mitochondrial function in NSCLC cells.ConclusionsTogether, our work demonstrates that CycT, and likely other Hh signaling inhibitors, can interrupt NSCLC cell function by promoting mitochondrial fission and fragmentation, mitochondrial membrane hyperpolarization, and ROS generation, thereby diminishing mitochondrial respiration, suppressing cell proliferation, and causing apoptosis. Our work provides novel mechanistic insights into the action of Hh inhibitors in cancer cells.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2200-x) contains supplementary material, which is available to authorized users.

The role of microRNA in esophageal squamous cell carcinoma.

MicroRNAs (miRNA) are 22-nucleotide non-coding RNAs that post-transcriptionally regulate gene expression by base pairing to partially complementary sequences in the 3'-untranslated region of their target messenger RNA. Altered miRNA expression also changes the expression of oncogenes and tumor suppressors, affecting the proliferation, apoptosis, motility and invasibility of gastrointestinal cancer cells, including the cells of esophageal squamous cell carcinoma (ESCC). It has been suggested that various miRNA expression profiles may provide useful biomarkers and therapeutic targets, but to date few studies have been published on the role of miRNA in ESCC. In this review we summarize the identification and characterization of miRNAs involved in ESCC and discuss their potential as biomarkers and therapeutic targets.

Chemoprevention of Low-Molecular-Weight Citrus Pectin (LCP) in Gastrointestinal Cancer Cells

Background & Aims: Low-molecular-weight citrus pectin (LCP) is a complex polysaccharide that displays abundant galactosyl (i.e., sugar carbohydrate) residues. In this study, we evaluated the anti-tumor properties of LCP that lead to Bcl-xL -mediated dampening of apoptosis in gastrointestinal cancer cells.Methods: We used AGS gastric cancer and SW-480 colorectal cancer cells to elucidate the effects of LCP on cell viability, cell cycle and apoptosis in cultured cells and tumor xenografts.Results: Significantly decreased cell viabilities were observed in LCP treated AGS and SW-480 cells (P<0.05). Cell cycle-related protein expression, such as Cyclin B1, was also decreased in LCP treated groups as compared to the untreated group. The AGS or SW-480 cell-line tumor xenografts were significantly smaller in the LCP treated group as compared the untreated group (P<0.05). LCP treatment decreased Galectin-3 (GAL-3) expression levels, which is an important gene in cancer metastasis that results in reversion of the epithelial-mesenchymal transition (EMT), and increased suppression of Bcl-xL and Survivin to promote apoptosis. Moreover, results demonstrated synergistic tumor suppressor activity of LCP and 5-FU against gastrointestinal cancer cells both in vivo and in vitro.Conclusions: LCP effectively inhibits the growth and metastasis of gastrointestinal cancer cells, and does so in part by down-regulating Bcl-xL and Cyclin B to promote apoptosis, and suppress EMT. Thus, LCP alone or in combination with other treatments has a high potential as a novel therapeutic strategy to improve the clinical therapy of gastrointestinal cancer.

Neurokinin-1 receptor antagonists as antitumor drugs in gastrointestinal cancer: A new approach.

Gastrointestinal (GI) cancer is the term for a group of cancers affecting the digestive system. After binding to the neurokinin-1 (NK-1) receptor, the undecapeptide substance P (SP) regulates GI cancer cell proliferation and migration for invasion and metastasis, and controls endothelial cell proliferation for angiogenesis. SP also exerts an antiapoptotic effect. Both SP and the NK-1 receptor are located in GI tumor cells, the NK-1 receptor being overexpressed. By contrast, after binding to the NK-1 receptor, NK-1 receptor antagonists elicit the inhibition (epidermal growth factor receptor inhibition) of the proliferation of GI cancer cells in a concentration-dependent manner, induce the death of GI cancer cells by apoptosis, counteract the Warburg effect, inhibit cancer cell migration (counteracting invasion and metastasis), and inhibit angiogenesis (vascular endothelial growth factor inhibition). NK-1 receptor antagonists are safe and well tolerated. Thus, the NK-1 receptor could be considered as a new target in GI cancer and NK-1 receptor antagonists (eg, aprepitant) could be a new promising approach for the treatment of GI cancer.

Abstract A084: Identification of mutation-reactive T cells in patients with gastrointestinal cancers

Abstract New immunotherapeutic advances for common epithelial cancers relies on our ability to stimulate T lymphocytes against specific tumour antigens (Ag). Next-generation sequencing now allows rapid identification of somatic cancer mutations that can lead to the expression of mutated Ag. We hypothesize that gastrointestinal cancer metastases are infiltrated by T cells recognizing tumour mutated Ag. Our aim is to set up an experimental platform to screen for and study the frequency and function of mutation-reactive T cells, while characterizing novel tumour mutated Ag. To do this, we used two cancer cell lines generated from a liver metastasis of a gastric cancer patient. The cell line A was recognized by an autologous CD8+ T cell clone infiltrating the patient's metastasis, restricted by HLA C*0701, while cell line B was not recognized by the same clone despite its expression of the HLA C*0701. The CD8+ T cell clone was not reactive to a large panel of HLA-C*0701 expressing gastrointestinal cancer cell lines, reinforcing the hypothesis that the Ag recognized was unique to the autologous gastric cancer cell line. Exome and transcriptome sequencing was performed to compare the mutated genes differentially expressed by cancer cell line A and B. A total of 27 mutated Ag were selected as candidates: 26 Ag only expressed by cell line A, and one Ag overexpressed by cell line A. To screen for reactivity of the CD8+ T cell clone to mutated Ag, 25 amino acid (aa) mini-genes containing the mutation flanked upstream and downstream by normal aa were synthesised and cloned in tandem into 3 expression plasmids. A control sequence from the MAGE-A12 gene containing an epitope restricted by HLA-C*0701was included in each tandem minigene (TMG) construct. The mRNA from these 3 TMG constructs were in vitro transcribed and electroporated into CD40-activated B cells expressing HLA C*0701, used as antigen presenting cells. Co-culture assays are ongoing, using the CD8+ T cell clones as effectors and T cells transduced with a MAGE-A12-specific TCR as control. For the detection of mutation-reactive T cells, the sensitivity of TMG expression is compared to pulsing mutated peptides on B cells. Taking advantage of the differential recognition of two cancer cell lines by an autologous CD8+ T cell clone, we have established a bioinformatics approach based on next-generation sequencing to obtain a list of candidate mutated Ag and we have designed an experimental system to assess their recognition by T cells. This platform will allow us to study the function of T cells reactive against metastatic gastrointestinal cancers and should lead to the discovery of new tumour Ag. Gaining a better understanding of T cells reactive to gastrointestinal cancers should ultimately contribute to the development of immunotherapies for these common malignancies. Citation Format: Mélissa Mathieu, Sandy Pelletier, David Laperrière, Sylvie Mader, Simon Turcotte. Identification of mutation-reactive T cells in patients with gastrointestinal cancers. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A084.

Abstract A38: In vitro and in vivo characterization of a novel NEK2 inhibitor MBM5 for the treatment of gastrointestinal cancer

Abstract NEK2 is a conserved mitotic regulator critical for centrosome splitting and correct chromosome segregation. Aberrant expression of NEK2 has been found in a variety of human cancers, making it an attractive molecular target for the design of novel anticancer therapeutics. Here we report the discovery of a novel small molecule NEK2 inhibitor, MBM5, for the treatment of gastrointestinal cancer cells. A series of compounds have been synthesized to determine their potency against NEK2. Through in vitro kinase assay, we found that compound MBM5 exhibited a significant inhibitory effect on the kinase activity of NEK2. MBM5 also demonstrated strong inhibition on proliferation of a broad spectrum of tumor cells, especially gastrointestinal cancer cells (IC50&amp;lt;1 μM). Treating cells with MBM5 triggered a significant accumulation of cells at G2/M phase and a modest accumulation of cells with &amp;gt;4N DNA content. By releasing cells from the G1/S boundary, we found that the progression from G2/M to G1 phases were completely abrogated in the presence of MBM5. In consistence, we further observed that MBM5 induced chromosomal misalignment in metaphase and slightly increased the level of multinucleated cells, confirming the perturbed mitotic progression. And these was correlated with MBM5-inhibited phosphorylation of Hec1 and Histone 3. Over time, the accumulation of chromosomal abnormalities led to apoptosis, as evidenced by the increased population of Annexin-V/PI positive cells, the up-regulated expression of cleaved-caspase 3 and the cleavage of PARP. In vivo daily treatment with MBM5 (ip, 20 mg/kg, 3 weeks) significantly inhibited the growth of MGC-803 gastric tumor and HCT-116 colonal tumor xenografts. Altogether, this study demonstrates that MBM5 interfered with NEK2 functions both in cells and tumor xenografts, thus showing its potential in anti-cancer treatment regimens. Citation Format: Yanfen Fang, Xiongwen Zhang, Wenhao Hu, Yannan Kong, Hong Wang, Mengli Zhu. In vitro and in vivo characterization of a novel NEK2 inhibitor MBM5 for the treatment of gastrointestinal cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A38.

Cytotoxic activities of Amaryllidaceae alkaloids against gastrointestinal cancer cells

Oncological diseases are one of the leading causes of death in the developed countries and the increase of its prevalence seems to be inevitable. In most cases oncological patients die due to resistance of cancer to therapy, metastasis and dissemination of cancer cells into vital organs. The standard treatment covers surgical intervention, radiotherapy and/or chemotherapy.

Abstract B1-57: HER2+ cancer dependence on PI3K vs. MAPK signaling pathways is predicted by expression of 3 protein biomarkers, and informs optimal combination treatment strategies

Abstract Human cancers are incredibly diverse with regard to molecular aberrations, dependence on oncogenic signaling pathways, and responses to pharmacological intervention. In this work we sought to quantify how cellular dependence on the canonical PI3K vs. MAPK pathways varies across HER2+ cancers, and how such dependence affects responses to targeted therapies. A panel of 18 HER2+ (ERBB2-amplified) cell lines covering a variety of indications was used to characterize the diversity within this oncogene-defined cancer. In vitro video microscopy was used to monitor cell growth responses to combinations of AKT (MK2206) and MEK (GSK1120212; trametinib) inhibitors, and Luminex-based quantitative proteomics to profile expression of HER-family receptors and intracellular signaling components. We find that HER2+ cell lines can be functionally classified by PI3K vs. MAPK pathway dependence, and this dependence is accurately predicted by a combination of protein measurements comprising EGFR, ErbB3, and the cyclin-dependent kinase inhibitor p27 (CDKN1B). Expression of these biomarkers varied by tissue, such that HER2+ lung, ovarian, and gastrointestinal cancer cell lines are preferentially dependent upon MAPK signaling, while breast cancers were primarily PI3K-dependent. mRNA expression patterns of these markers were consistent between immortalized cell lines and clinical samples (TCGA), and predicted differential sensitivity to multiple drugs in the Genomics of Drug Sensitivity in Cancer (GDSC) database, including AKT and MEK inhibitors, as well as agents targeting metabolism (AMPK, MTOR), stress response (HDAC) and cell cycle control (CHK, and CDK). To further assess how PI3K vs. MAPK pathway dependence affects responses to combinations of clinically-relevant therapies, we utilized a multi-scale model of HER2+ cancer linking cell signaling to proliferation and survival. Growth inhibitory responses to combinations of drugs targeting the ErbB signaling network were simulated across a diverse population of synthetic tumors. Activating mutations in the PI3K and MAPK pathways (PIK3CA and KRAS) and expression of the HER3 ligand Heregulin determined sensitivity to combinations of inhibitors against HER2 (lapatinib), HER3 (MM-111), AKT (MK-2206) and MEK (trametinib), in addition to the standard of care trastuzumab (Herceptin). These biomarker-response predictions were combined into a six-arm decision tree, and predictions validated by in vitro profiling of combination drug responses in a secondary panel of HER2+ cell lines. In summary, this work demonstrates that HER2+ cancers are both molecularly and functionally diverse, and suggests that measurement of this minimal set of three protein biomarkers could inform combination regimen design for this class of cancers. More broadly, the computational strategy presented for identifying effective combinations and predictive biomarkers may be extendable to other human cancers. Citation Format: Daniel C. Kirouac, Jinyan Du, Johanna j. Lahdenranta, Charlotte Mcdongh, Ulrik Nielsen. HER2+ cancer dependence on PI3K vs. MAPK signaling pathways is predicted by expression of 3 protein biomarkers, and informs optimal combination treatment strategies. [abstract]. In: Proceedings of the AACR Special Conference on Computational and Systems Biology of Cancer; Feb 8-11 2015; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(22 Suppl 2):Abstract nr B1-57.

Antiproliferative activity of New Zealand propolis and phenolic compounds vs human colorectal adenocarcinoma cells

New Zealand propolis is a “European” type propolis obtained by honey bees mainly from exudates of poplar. European type propolis is known to have anti-inflammatory and anti-cancer properties and this activity has been attributed to some of the main constituents such as chrysin and CAPE (caffeic acid phenethyl ester). As part of our studies on how New Zealand propolis might benefit gastro-intestinal health, we carried out in vitro bioactivity-guided fractionation of “Bio30™” propolis using both anti-inflammatory (TNF-α, COX-1, COX-2) and anti-colon cancer (DLD-1 colon cancer cell viability) assays; and determined the phenolic compounds responsible for the activity. The New Zealand wax-free Bio30™ propolis tincture solids had very high levels of the dihydroflavonoids pinocembrin and pinobanksin-3-O-acetate, and high levels of the dimethylallyl, benzyl and 3-methyl-3-butenyl caffeates relative to CAPE. The DLD-1 assays identified strong anti-proliferative activity associated with these components as well as chrysin, galangin and CAPE and a number of lesser known or lower concentration compounds including benzyl ferulate, benzyl isoferulate, pinostrobin, 5-phenylpenta-2,4-dienoic acid and tectochrysin. The phenolic compounds pinocembrin, pinobanksin-3-O-acetate, tectochrysin, dimethylallyl caffeate, 3-methyl-3-butenyl caffeate, benzyl ferulate and benzyl isoferulate also showed good broad spectrum activity in anti-proliferative assays against three other gastro-intestinal cancer cell lines; HCT-116 colon carcinoma, KYSE-30 oesophageal squamous cancer, and NCI-N87 gastric carcinoma. Activity is also observed in anti-inflammatory assays although it appears to be limited to one of the first cytokines in the inflammatory cascade, TNF-α.

Design, synthesis, and anticancer evaluation of long-chain alkoxylated mono-carbonyl analogues of curcumin

Curcumin is a nontoxic phenolic compound that modulates the activity of several cellular targets that have been linked with cancers and other chronic diseases. However, the efficacy of curcumin in the clinic has been limited by its poor bioavailability and rapid metabolism in vivo. We have previously reported the design and discovery of series of 5-carbon linker-containing mono-carbonyl analogues of curcumin (MACs) as anti-cancer agents. In continuation of our ongoing research, we designed and synthesized 37 novel long-chain alkoxylated MACs for anti-cancer evaluation here. The MTS assay was used to determine the cytotoxicity of compounds in gastrointestinal cancer cells. Compounds 5, 28, and 29 showed strongest inhibition against gastric cancer cell proliferation and were subjected to further analysis. The effects of 5, 28, and 29 on cell apoptosis were measured by flow cytometry. Expression levels of Bcl-2, cleaved poly ADP-ribose polymerase (PARP), and pro-caspase-3 were detected by western blotting. Compounds 5, 28, and 29 induced apoptosis in human gastric carcinoma cells, increased PARP cleavage, and decreased expression of Bcl-2 and pro-caspase-3 protein. We then showed that compound 28, which possessed the strongest activity among the test compounds in vitro, exhibited significant tumor inhibition in SGC7901-driven xenograft mouse model. Taken together, the novel compound 28 could be further explored as an effective anticancer agent for the treatment of human gastric cancer.

Cytotoxic activities of Amaryllidaceae alkaloids against gastrointestinal cancer cells

The treatment of many diseases is highly dependent on natural products and natural products can also be used as design templates for future anticancer drugs. Thirteen Amaryllidaceae alkaloids possessing α-crinane, β-crinane, galantamine, lycorine and tazettine-type skeleton have been isolated in our laboratory, and their cytotoxicity against p53-mutated gastrointestinal cancer cells were evaluated. At the same time, healthy small intestine cells were used to determine overall toxicity against noncancerous cells. In this study, we demonstrated that haemanthamine, haemanthidine and lycorine showed strong cytotoxicity against p53-mutated Caco-2 and HT-29 colorectal adenocarcinoma cells as quantified in terms of IC50 values. We for the first time observed approximately 20 times higher IC50values against normal intestine epithelial cells FHs-74 Int after haemanthamine and lycorine treatment when compared with Caco-2 and HT-29 cancer cells. In conclusion, our data indicate that α-C2 bridged haemanthamine may be perspective anticancer drug candidate for further semisynthetic modification and structure-activity relationship study.

Abstract 3474: The effect of forced expression of k-ras mutation on gastrointestinal cancer cells and IGF-IR targeting therapy

Abstract Background &amp; Aims: Mutation in k-ras plays important roles in both the progression and the resistance for anti-EGFR therapy in gastrointestinal tumors. Insulin-like growth factor-I receptor (IGF-IR) signaling is required for carcinogenicity and proliferation of many tumors. We have previously shown successful therapy for gastrointestinal cancer cell lines with k-ras mutation using recombinant adenoviruses expressing dominant negative IGF-IR (IGF-IR/dn) and an anti-IGF-IR monoclonal antibody. In this study, we sought to evaluate the effect of k-ras mutation on gastrointestinal cancer cell lines and IGF-IR targeting therapies for those cells. Methods: We made stable transfectants of mutated k-ras in gastrointestinal cancer cell lines. We assessed the effect of forced expression of mutated k-ras on proliferartion, apoptosis induction, migration, and invasion in gastrointestinal cancer cell lines. Then we assessed the anti-tumor effect of IGF-IR/dn on mutated k-ras transfctomas. Results: Overexpression of mutated k-ras let gastrointestinal cancer cell lines be more agrressive phenotypes, such as more proliferative, more anti-apoptotic, more movable, and more invasive. IGF-IR/dn inhibited cell growth, colony formation, migration, and invasion, but induceed apoptosis of gastrointestinal cancer cells with or without mutated k-ras expression. Conclusions: K-ras mutation might be inportant for progressive phonotype in gastrointestinal cancers. IGF-IR might be a good molecular therapeutic target for gastrointestinal cancers even if k-ras is mutated. Citation Format: Yasushi Adachi, Yasutaka Matsunaga, Yasushi Sasaki, Katsuhiko Nosho, Hiroyuki Yamamoto, Yoshiaki Arimura, Takao Endo, Yasuo Kato, Takashi Tokino, David P. Carbone, Yasuhisa Shinomura. The effect of forced expression of k-ras mutation on gastrointestinal cancer cells and IGF-IR targeting therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3474. doi:10.1158/1538-7445.AM2015-3474

Abstract LB-007: Synergistic inhibition of human gastric and colorectal cancers by Bromelain and N-acetylcysteine: An in vivo study

Abstract Mucin is well understood to be an adverse prognostic factor in some cancers. We previously reported that a combination of Bromelain (BR) and N-acetylcysteine (NAC) were synergistic in dissolving pseudomyxoma peritonei mucin, had direct in vitro cytotoxic effects on some gastrointestinal cancer cells and sensitized them to some chemotherapy agents. In the present study, we aimed to evaluate the growth-inhibitory effect of BR and NAC as single agent or combination therapy in nude mice models of gastrointestinal cancer. Nude mice received 2 million and 1 million cells of MKN45 (gastric) and LS174T (colorectal) by intraperitoneal injection. At day 14 and 7 post inoculation for MKN45 and LS174T cells, respectively, animals were intraperitoneally administrated BR (3, 6 mg/kg), NAC (300, 500 mg/kg) or their combination every other day over 12 days for MKN45 and 17 days for LS174T models. At the end of the study, the animals were euthanized, the number of peritoneal nodules and their weight were collected, and the peritoneal tumors were subjected to immunohistochemistry for evaluation of MUC2. No toxicity was observed during the experiment. At necropsy, highly significant reductions in the number of tumor nodules and tumor burden were observed, in particular in the combination group, where almost complete inhibition in LS174T group was found. There was more than 95% and 70% decreases in tumor burden and tumor nodules, respectively, in LS174T group after combination treatment. For MKN45 model, the reductions in tumor burden and tumor nodules in combination groups were more than 60% and 70%, respectively. Performing immunohistochemistry on tumor samples, MUC2 staining of the LS174T xenografts showed a greater than 60% reduction of cytoplasmic staining. To the best of our knowledge, this is the first report of the in vivo use of this combination with synergistic inhibition of human gastric and colorectal cancers. The combination of BR and NAC in mucin secreting gastrointestinal tumors is interesting and could be of potential value in peritoneal cancer. Citation Format: Afshin Amini, Samar Masoumi-Moghaddam, Anahid Ehteda, Winston Liauw, Javed Akhter, Krishna Pilai, David L. Morris. Synergistic inhibition of human gastric and colorectal cancers by Bromelain and N-acetylcysteine: An in vivo study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-007. doi:10.1158/1538-7445.AM2015-LB-007

Novel mechanism for invasion and metastasis involving metabolic enzymes in intractable cancer cells

Cancer metabolism characterizes the malignant behavior of tumors. Pyruvate kinase M2 (PKM2), a key player in maintaining aerobic glycolysis, stimulates tumor growth by controlling the Warburg effect. It has been shown that PKM2 translocates into the nucleus to regulate the transcriptions of numerous down-stream genes, including PDK1 and LDHA. To investigate the significance of PKM2 in epithelial-mesenchymal transition (EMT), a biological process which promotes the metastasis of cancer cells, we induced EMT in gastrointestinal cancer cells using TGFβ and EGF in vitro. After EMT induction, E-cadherin was down-regulated, whereas Vimentin was up-regulated. PKM2 expression was increased at both the transcriptional and the translational level, and PKM2 translocated into the nucleus. Immunohistochemical staining of PKM2 revealed that PKM2 positivity correlated significantly with lymph node metastasis and distant organ metastasis of gastrointestinal cancer. The present results indicate that nuclear PKM2 plays a crucial role in controlling invasion and metastasis.

Abstract 198: Helicobacter pylori infection via miR-328 suppression and CD44 expression in gastric mucosa causes gastric cancer initiation and progression

Abstract Backgrounds: We previously revealed that CD44, cancer stem-like marker, interacts with xCT, a glutamate-cystine transporter, and controls the intracellular level of reduced glutathione. Helicobacter pylori (HP) infection is known to be a major cause of gastric cancer and be associated with increased expression of CD44 on gastric epithelial cells, but precise mechanism of CD44 up-regulation still has uncertain. On the other hand, microRNAs (miRNAs) are noncoding RNAs that regulate molecular pathways in cancer by targeting various genes. The aim of the current study was to identify the miRNA regulating CD44 expression in H. pylori-infected gastric mucosa during the development of preneoplastic lesions. Methods and Results: To investigate the regulation of CD44 through miRNA, we performed 384 miRNA quantitative RT-PCR array analyses in six human gastrointestinal cancer cell lines that differ in CD44 expression status. We identified miR-328 which is predicted as CD44-targeted and established the functional relationship between miR-328 and CD44. MiR-328 overexpression decreased CD44 expression and led to inhibition of cancer cell growth and impairing chemo- and ROS (reactive oxygen species) - resistance. We performed luciferase assay using vectors containing CD44 3′- UTR, which might be directly bound by miR-328, using the miRanda algorithm, and the results indicated that miR-328 regulated CD44 expression by directly targeting its 3′-UTR. We polarized THP-1 that human monocytic leukemia cell line to M1- and M2 macrophages, and detected ROS production of its by using 2′,7′-dichlorofluorescein diacetate, and ROS induced miR-328 down-regulation and CD44 up-regulation by co-culture gastric cancer cell lines with M1- and M2-polarized THP-1 macrophages. We further analyzed the association between miR-328-CD44 pathway and HP infection in human gastric mucosa. We identified that HP infection correlated with miR-328 down-regulation and CD44 up-regulation. Lastly, we examined the DNA methylation of the miR-328 5′-flanking region by bisulfite pyrosequencing in human gastric mucosa, but HP infection were not related with the DNA methylation level in this region. Conclusions: We show that inflammatory response with HP infection causes CD44 expression via miR-328 suppression, resulting in cancer initiation and progression, but HP infection was unrelated to the DNA methylation in the miR-328 5′-flanking region. Citation Format: Keisuke Miyake, Takatsugu Ishimoto, Hidetaka Sugihara, Kojiro Eto, Daisuke Izumi, Junji Kurashige, Yukiharu Hiyoshi, Shiro Iwagami, Yoshifumi Baba, Yuji Miyamoto, Naoya Yoshida, Hideo Baba. Helicobacter pylori infection via miR-328 suppression and CD44 expression in gastric mucosa causes gastric cancer initiation and progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 198. doi:10.1158/1538-7445.AM2015-198

Contribution of Dual Oxidase 2 (DUOX2) to Hyper-Radiosensitivity in Human Gastric Cancer Cells.

Whole-abdominal radiotherapy (WART) is a primary method for managing gastrointestinal cancers that have disseminated into intra-abdominal tissues. While effective, this approach is limited because of the increased toxicity to normal tissue associated with combined WART and full-dose chemotherapy regimens. Recent studies have demonstrated a survival advantage in a novel treatment paradigm that allows for the safe use of full-dose systemic chemotherapy in combination with low-dose fractionated radiotherapy (LDFRT). Traditionally, radiation doses greater than 120 cGy have been used in radiotherapy because lower doses were thought to be ineffective for tumor therapy. However, we now know that LDFRT can produce hyper-radiosensitivity (HRS), a phenomenon where cells undergo apoptosis at radiation doses as low as 15 cGy, in a number of proliferating cells. The objectives of our current study were to determine whether LDFRT can induce HRS in gastrointestinal cancer cells and to identify biomarkers of chemopotentiation by LDFRT. Our data indicate that three consecutive daily fractions of 15 cGy produced HRS in gastric cancer cells and potentiated a modified regimen of docetaxel, cisplatin and 5'-fluorouracil (mDCF). Colony survival assays indicated that 15 cGy was sufficient to kill 90% of the cells when LDFRT was combined with mDCF whereas a dose almost 10 times higher (135 cGy) was needed to achieve the same rate when using conventional radiotherapy alone. RT(2) PCR Profiler™ array analysis indicated that this combined regimen upregulated dual oxidase 2 (DUOX2), an enzyme functioning in the production of hydrogen peroxide, without upregulating genes involved in DNA repair. Moreover, downregulation of DUOX2 increased radioresistance at every radiation dose tested. In addition, our data indicate that reactive oxygen species (ROS) increase up to 3.5-fold in cells exposed to LDFRT and mDCF. Furthermore, inhibition of NADPH oxidase abrogated the killing efficiency of this combined regimen. Taken together these data suggest that chemopotentiation by LDFRT in gastric cancer cells may be due, at least in part, to increased ROS production (DUOX2) without upregulation of the DNA repair machinery. These data thus provide a rationale for further explorations of potential clinical applications of LDFRT, such as in WART, as a chemopotentiator for advanced and metastatic gastric cancers.

Dimethyl fumarate induces necroptosis in colon cancer cells through GSH depletion/ROS increase/MAPKs activation pathway.

Dimethyl fumarate (DMF) is a newly approved drug for the treatment of relapsing forms of multiple sclerosis and relapsing-remitting multiple sclerosis. Here, we investigated the effects of DMF and its metabolites mono-methylfumarate (MMF and methanol) on different gastrointestinal cancer cell lines and the underlying molecular mechanisms involved. Cell viability was measured by the MTT or CCK8 assay. Protein expressions were measured by Western blot analysis. LDH release, live- and dead-cell staining, intracellular GSH levels, and mitochondrial membrane potential were examined by using commercial kits. DMF but not MMF induced cell necroptosis, as demonstrated by the pharmacological tool necrostatin-1, transmission electron microscopy, LDH and HMGB1 release in CT26 cells. The DMF-induced decrease in cellular GSH levels as well as cell viability and increase in reactive oxygen species (ROS) were inhibited by co-treatment with GSH and N-acetylcysteine (NAC) in CT26 cells. DMF activated JNK, p38 and ERK MAPKs in CT26 cells and JNK, p38 and ERK inhibitors partially reversed the DMF-induced decrease in cell viability. GSH or NAC treatment inhibited DMF-induced JNK, p38, and ERK activation in CT26 cells. DMF but not MMF increased autophagy responses in SGC-7901, HCT116, HT29 and CT26 cancer cells, but autophagy inhibition did not prevent the DMF-induced decrease in cell viability. DMF but not its metabolite MMF induced necroptosis in colon cancer cells through a mechanism involving the depletion of GSH, an increase in ROS and activation of MAPKs.

Tu1973 The Novel Observation of Irreversible Electroporation Phenomenon on Gastrointestinal Cancer Cells in Physiological Conditions, With Sub-Micrometer Resolution by Scanning Ion Conductance Microscopy

G A A b st ra ct s enhanced MEK/ERK activation coincided with those that inhibited mTORC2-mediated Akt phosphorylation on Ser473, suggesting a role of mTORC2. Knockdown of Rictor markedly increased baseline levels of ERK phosphorylation and treatment with NVP-BEZ235 did not produce further enhancement of ERK activation. These results imply that Rictor or mTORC2 exerts feedback inhibition of the MEK/ERK pathway in pancreatic cancer cells. Conclusion: We propose that dual PI3K/mTOR inhibitors suppress a novel negative feedback loop mediated by mTORC2 thereby leading to enhanced MEK/ERK pathway activity in pancreatic cancer cells.

P5.10 - Bromelain and N-acetylcysteine inhibit proliferation and survival of gastrointestinal cancer cells: significance of combination therapy

ABSTRACT Bromelain and N-acetylcysteine (NAC) are two natural, sulfhydryl-containing compounds with good safety profiles which have been investigated for their benefits and application in health and disease. In the present study, the efficacy of bromelain and NAC in single agent and combination treatment of human gastrointestinal carcinoma cells was evaluated in vitro and underlying mechanisms of effect were explored. The growth-inhibitory effects of bromelain and NAC, on their own and in combination, on a panel of human gastrointestinal carcinoma cell lines, including MKN45, KATO-III, HT29-5F12 & -5M21 and LS174T, were assessed by SRB. Moreover, the influence of the treatment on the expression of a range of regulators of cell cycle and survival was investigated by Western blot. The presence of apoptosis was also examined by TUNEL assay. Bromelain and NAC significantly inhibited cell proliferation, more potently in combination therapy. Drug-drug interaction in combination therapy was predominantly synergistic or additive. Mechanistically, apoptotic bodies were detected in treated cells by TUNEL assay. Western blot analysis revealed diminution of cyclins A, B and D, the emergence of immunoreactive subunits of caspases 3, 7, 8 and cleaved PARP, withering or cleavage of procaspase-9, overexpression of cytochrome c, reduced expression of anti-apoptotic Bcl-2 and pro-survival phospho-Akt, the emergence of the autophagosomal marker LC3-II and deregulation of other autophagy-related proteins, including Atg3, 5, 7, 12 and Beclin 1. These results were more prominent in combination therapy. We report for the first time growth-inhibitory and cytotoxic effects of bromelain and NAC, in particular in combination, on gastrointestinal cancer cell lines with different phenotypes and characteristics. These effects apparently resulted from cell cycle arrest, apoptosis and autophagy. Towards the development of novel strategies for the enhancement of microscopic cytoreduction, our results lay the basis for further evaluation of this formulation in locoregional approaches to peritoneal surface malignancies and carcinomatosis.

Clinicopathological significance of nuclear factor (erythroid-2)-related factor 2 (Nrf2) expression in gastric cancer.

BackgroundThe transcription factor nuclear factor (erythroid-2)–related factor 2 (Nrf2) was originally identified as a critical regulator of intracellular anti-oxidants and of phase II detoxification enzymes through its transcriptional up-regulation of many anti-oxidant response element (ARE)-containing genes. Nrf2 protects not only normal cells but also cancer cells from cellular stress, and enhances cancer cell survival. Some studies have shown that Nrf2 expression in cancer patients has clinical significance. However, there has been no comprehensive analysis of the nuclear expression level of Nrf2 in gastrointestinal cancer cells. In this study we aimed to immunohistochemically evaluate the expression of Nrf2, and to assess its clinical significance in gastric cancer.MethodsA total of 175 gastric cancer patients who received R0 gastrectomy with standard lymph node dissection were enrolled. We immunohistochemically evaluated Nrf2 expression in the paraffin-embedded surgically resected specimens of these 175 patients. Group differences were analyzed using the χ2 test, Fisher’s exact test, and the Mann–Whitney U test. Associations between Nrf2 expression and clinicopathological features, including clinical outcome, were assessed using univariate and multivariate analyses, and Kaplan-Meier curves with the log-rank test, respectively.ResultsNrf2 immunoreactivity was predominantly identified in the nucleus of gastric cancer cells. Nrf2 positivity was closely associated with tumor size, tumor depth, lymph node metastases, lymphovascular invasion, histology and stage (p < 0.05 for all). A log-rank test indicated that the overall survival of the Nrf2-positive group was significantly poorer than that of the Nrf2-negative group (p < 0.01). And, positive Nrf2 expression was significantly associated with resistance to 5FU-based adjuvant chemotherapy (p = 0.024).ConclusionsNrf2 expression was positively associated with aggressive tumor behavior in gastric cancer. This result suggests that Nrf2 expression in gastric cancer is a potential indicator of worse prognosis.