Colon Cancer Cell Line DLD-1 Research Articles

KIT Signaling Promotes Growth of Colon Xenograft Tumors in Mice and Is Up-Regulated in a Subset of Human Colon Cancers

Receptor tyrosine kinase (RTK) inhibitors have advanced colon cancer treatment. We investigated the role of the RTK KIT in development of human colon cancer. An array of 137 patient-derived colon tumors and their associated xenografts were analyzed by immunohistochemistry to measure levels of KIT and its ligand KITLG. KIT and/or KITLG was stably knocked down by expression of small hairpin RNAs from lentiviral vectors in DLD1, HT29, LS174T, and COLO320 DM colon cancer cell lines, and in UM-COLON#8 and POP77 xenografts; cells transduced with only vector were used as controls. Cells were analyzed by real-time quantitative reverse transcription polymerase chain reaction, single-cell gene expression analysis, flow cytometry, and immunohistochemical, immunoblot, and functional assays. Xenograft tumors were grown from control and KIT-knockdown DLD1 and UM-COLON#8 cells in immunocompromised mice and compared. Some mice were given the RTK inhibitor imatinib after injection of cancer cells; tumor growth was measured based on bioluminescence. We assessed tumorigenicity using limiting dilution analysis. KIT and KITLG were expressed heterogeneously by a subset of human colon tumors. Knockdown of KIT decreased proliferation of colon cancer cell lines and growth of xenograft tumors in mice compared with control cells. KIT knockdown cells had increased expression of enterocyte markers, decreased expression of cycling genes, and, unexpectedly, increased expression of LGR5 associated genes. No activating mutations in KIT were detected in DLD1, POP77, or UM-COLON#8 cells. However, KITLG-knockdown DLD1 cells formed smaller xenograft tumors than control cells. Gene expression analysis of single CD44(+) cells indicated that KIT can promote growth via KITLG autocrine and/or paracrine signaling. Imatinib inhibited growth of KIT(+) colon cancer organoids in culture and growth of xenograft tumors in mice. Cancer cells with endogenous KIT expression were more tumorigenic in mice. KIT and KITLG are expressed by a subset of human colon tumors. KIT signaling promotes growth of colon cancer cells and organoids in culture and xenograft tumors in mice via its ligand, KITLG, in an autocrine or paracrine manner. Patients with KIT-expressing colon tumors can benefit from KIT RTK inhibitors.

Targeting the neurokinin-1 receptor inhibits growth of human colon cancer cells.

The substance P (SP)/neurokinin-1 receptor (NK1R) complex and the Wnt cascade are pivotal signaling pathways in the regulation of cell growth and hence, potent targets for future anticancer therapies. However, while the Wnt cascade has long been associated with colon cancer, little is known about the expression of the NK1R complex as a potential target in this tumor and its molecular basis in tumorigenesis in general. We treated the human colon cancer cell lines LiM6 and DLD1 with the NK1R antagonist and the clinical drug aprepitant (AP) and analyzed both growth response and downstream mechanisms using MTT-assay, reverse phase protein array (RPPA), western blot, Super TOP/FOP, confocal microscopy, and sphere formation ability (SFA) assays. Following NK1R blockage, we found significant growth inhibition of both colon cancer cell lines. When analyzing downstream mechanisms, we found a striking inhibition of the canonical Wnt pathway represented by decreased Super TOP/FOP and increased membrane stabilization of β-catenin. This effect was independent from baseline Wnt activity and mutational status of β-catenin. Further, treatment of colon cancer cells grown under cancer stem cell (CSC) conditions reduced sphere formation in both number and size after a single treatment period. We show that the NK1R can be a potent anticancer target in colon cancer and that NK1R antagonists could potentially serve as future anticancer drugs. This effect was seen not only in primary cancer cells but, for the first time, also in CSC-like cells, potentially including these cells in a therapeutic effect. Also, we describe the robust inhibition of canonical Wnt signaling through targeting the SP/NK1R signaling cascade. These findings give important insight into the molecular mechanisms of the SP/NK1R complex as a critical component in tumorigenesis and could help to identify future anticancer therapies for colon and other Wnt-activated cancers.

Synthesis, characterization and in vitro evaluation of a series of novel polyrotaxane-based delivery system for artesunate

A series of novel artesunate-polyrotaxanes (ATS-PRs) with folic acid capped, in which artesunate (ATS) was covalently bound to a cyclodextrin (CD) of the polyrotaxane (PR), were synthesized and were characterized by NMR, XRD, TG and DSC. The cytotoxicities of ATS-PRs on human colon cancer cell lines HT-29, SW480, HTC116 and DLD-1 showed that their antitumor activities were better than that of artesunate (ATS) and dihydroartemisinin (DHA). These ATS-PRs may provide a useful approach to the development of a highly effective drug candidate for the chemotherapy of human colon cancer.

Differentiation-inducing factor-3 inhibits intestinal tumor growth in vitro and in vivo

Differentiation-inducing factor-1 (DIF-1) produced by Dictyostelium discoideum strongly inhibits the proliferation of various types of cancer cells by suppression of the Wnt/β-catenin signal transduction pathway. In the present study, we examined the effect of differentiation-inducing factor-3 (DIF-3), a monochlorinated metabolite of DIF-1 that is also produced by D. discoideum, on human colon cancer cell lines HCT-116 and DLD-1. DIF-3 strongly inhibited cell proliferation by arresting the cell cycle at the G0/G1 phase. DIF-3 reduced the expression levels of cyclin D1 and c-Myc by facilitating their degradation via activation of GSK-3β in a time and dose-dependent manner. In addition, DIF-3 suppressed the expression of T-cell factor 7-like 2, a key transcription factor in the Wnt/β-catenin signaling pathway, thereby reducing the mRNA levels of cyclin D1 and c-Myc. Subsequently, we examined the in vivo effects of DIF-3 in Mutyh−/− mice with oxidative stress-induced intestinal cancers. Repeated oral administration of DIF-3 markedly reduced the number and size of cancers at a level comparable to that of DIF-1. These data suggest that DIF-3 inhibits intestinal cancer cell proliferation in vitro and in vivo, probably by mechanisms similar to those identified in DIF-1 actions, and that DIF-3 may be a potential novel anti-cancer agent.

Efficient apoptosis and necrosis induction by proteasome inhibitor: bortezomib in the DLD-1 human colon cancer cell line.

The inhibition of the 26S proteasome evokes endoplasmic reticulum stress, which has been shown to be implicated in the antitumoral effects of proteasome inhibitors. The cellular and molecular effects of the proteasome inhibitor—bortezomib—on human colon cancer cells are as yet poorly characterized. Bortezomib selectively induces apoptosis in some cancer cells. However, the nature of its selectivity remains unknown. Previously, we demonstrated that, in contrast to normal fibroblasts, bortezomib treatment evoked strong effect on apoptosis of breast cancer cells incubated in hypoxic and normoxic conditions. The study presented here provides novel information on the cellular effects of bortezomib in DLD-1 colon cancer cells line. We observe twofold higher percentage of apoptotic cells incubated for 48 h with 25 and 50 nmol/l of bortezomib in hypoxic conditions and four-, fivefold increase in normoxic conditions in comparison to control cells, incubated without bortezomib. It is of interest that bortezomib evokes strong effect on necrosis of DLD-1 colon cancer cell line. We observe the sixfold increase in necrosis of DLD-1 cells incubated with 25 or 50 nmol/l of bortezomib for 48 h in hypoxia and fourfold increase in normoxic conditions in comparison to adequate controls. We suggest that bortezomib may be candidates for further evaluation as chemotherapeutic agents for human colon cancer.

Apoptotic Effects of Quercitrin on DLD-1 Colon Cancer Cell Line

Quercetin, which is the most abundant bioflavonoid compound, is mainly present in the glycoside form of quercitrin. Although different studies indicated that quercitrin is a potent antioxidant, the action of this compound is not well understood. In this study, we investigated whether quercitrin has apoptotic and antiproliferative effects in DLD-1 colon cancer cell lines. Time and dose dependent antiproliferative and apoptotic effects of quercitrin were subsequently determined by WST-1 cell proliferation assay, lactate dehydrogenase (LDH) cytotoxicity assay, detection of nucleosome enrichment factor, changes in caspase-3 activity, loss of mitochondrial membrane potential (MMP) and also the localization of phosphatidylserine (PS) in the plasma membrane. There were significant increases in caspase-3 activity, loss of MMP, and increases in the apoptotic cell population in response to quercitrin in DLD-1 colon cancer cells in a time- and dose-dependent manner. These results revealed that quercitrin has antiproliferative and apoptotic effects on colon cancer cells. Quercitrin activity supported with in vivo analyses could be a biomarker candicate for early colorectal carcinoma.

Loss of lamin B1 results in prolongation of S phase and decondensation of chromosome territories.

Nuclear lamin B1 (LMNB1) constitutes one of the major structural proteins in the lamina mesh. We silenced the expression of LMNB1 by RNA interference in the colon cancer cell line DLD-1 and showed a dramatic redistribution of H3K27me3 from the periphery to a more homogeneous nuclear dispersion. In addition, we observed telomere attrition and an increased frequency of micronuclei and nuclear blebs. By 3D-FISH analyses, we demonstrated that the volume and surface of chromosome territories were significantly larger in LMNB1-depleted cells, suggesting that LMNB1 is required to maintain chromatin condensation in interphase nuclei. These changes led to a prolonged S phase due to activation of Chk1. Finally, silencing of LMNB1 resulted in extensive changes in alternative splicing of multiple genes and in a higher number of enlarged nuclear speckles. Taken together, our results suggest a mechanistic role of the nuclear lamina in the organization of chromosome territories, maintenance of genome integrity and proper gene splicing.

Inhibition of microRNA-31-5p protects human colonic epithelial cells against ionizing radiation

MicroRNAs (miRNAs), endogenous non-coding small RNAs, are sensitive to environmental changes, and their differential expression is important for adaptation to the environment. However, application of miRNAs as a clinical prognostic or diagnostic tool remains unproven. In this study we demonstrate a chronic/persistent change of miRNAs from the plasma of a colorectal cancer susceptible mouse model (CPC;Apc) about 250 days after exposure to a simulated solar particle event (SPE). Differentially expressed miRNAs were identified compared to unirradiated control mice, including miR-31-5p, which we investigated further. To address the cellular function of miR-31-5p, we transfected a miR-31-5p mimic (sense) or inhibitor (antisense) into immortalized human colonic epithelial cells followed by gamma-irradiation. A miR-31-5p mimic sensitized but a miR-31-5p inhibitor protected colonic epithelial cells against radiation induced killing. We found that the miR-31-5p mimic inhibited the induction of hMLH1 expression after irradiation, whereas the miR-31-5p inhibitor increased the basal level of hMLH1 expression. The miR-31-5p inhibitor failed to modulate radiosensitivity in an hMLH1-deficient HCT116 colon cancer cell line but protected HCT116 3–6 and DLD-1 (both hMLH1-positive) colon cancer cell lines. Our findings demonstrate that miR-31-5p has an important role in radiation responses through regulation of hMLH1 expression. Targeting this pathway could be a promising therapeutic strategy for future personalized anti-cancer radiotherapy.

Sesamol suppresses cyclooxygenase-2 transcriptional activity in colon cancer cells and modifies intestinal polyp development in ApcMin/+ mice

Excessive prostaglandin production by cyclooxygenase-2 in stromal and epithelial cells is a causative factor of colorectal carcinogenesis. Thus, compounds which inhibit cyclooxygenase-2 transcriptional activity in colon epithelial cells could be candidates for anti-carcinogenic agents. A cyclooxygenase-2 transcriptional activity in the human colon cancer cell line DLD-1 has been measured using a β-galactosidase reporter gene system. Using this system, we demonstrated that the decrease in basal cyclooxygenase-2 transcriptional activities at 100 µM sesamol, one of the lignans in sesame seeds, was 50%. Other compounds in sesame seeds such as sesamin, sesamolin, ferulic acid, and syringic acid did not exhibit significant suppression of cyclooxygenase-2 transcriptional activity at up to 100 µM. In a following experiment, 6-week-old male Min mice, Apc-deficient mice, were divided into a non-treated and 500 ppm sesamol groups. At the age of 15 weeks, it was found that treatment with sesamol decreased the number of polyps in the middle part of small intestine to 66.1% of the untreated value. Moreover, sesamol suppressed cyclooxygenase-2 and cytosolic prostaglandin E2 synthase mRNA in the polyp parts. The present findings may demonstrate the novel anti-carcinogenetic property of sesamol, and imply that agents that can suppress cyclooxygenase-2 expression may be useful cancer chemopreventive agents.

Kisspeptin Effect on Endothelial Monocyte Activating Polypeptide II (EMAP-II)-Associated Lymphocyte Cell Death and Metastases in Colorectal Cancer Patients

Kisspeptin is an antimetastatic agent in some cancers that has also been associated with lymphoid cell apoptosis, a phenomenon favoring metastases. Our aim was to determine the association of kisspeptin with lymphocyte apoptosis and the presence of metastases in colorectal cancer patients. Blood was drawn from 69 colon cancer patients and 20 healthy volunteers. Tissue specimens from healthy and pathological tissue were immunohistochemically analyzed for kisspeptin and endothelial monocyte activating polypeptide II (EMAP-II) expression. Blood EMAP-II and soluble Fas ligand (sFasL) levels were examined by an enzyme-linked immunosorbent assay method. The kisspeptin and EMAP-II expression and secretion levels in the DLD-1 and HT-29 colon cancer cell lines were examined by quantitative real-time polymerase chain reaction, Western analysis and enzyme-linked immunosorbent assay, whereas lymphocyte viability was assessed by flow cytometry. The effect of kisspeptin on the viability of colon cancer cells was examined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]. Exogenous, synthetic and naturally produced, kisspeptin induces through the G-protein-coupled receptor 54 (GPR54; also known as the kisspeptin receptor) the EMAP-II expression and secretion in colon cancer cell lines, inducing in vitro lymphocyte apoptosis, as verified by the use of an anti-EMAP-II antibody. These results were reversed with the use of kisspeptin inhibitors and by kisspeptin-silencing experiments. Tumor kisspeptin expression was associated with the tumor EMAP-II expression (p < 0.001). Elevated kisspeptin and EMAP-II expression in colon cancer tissues was associated with lack of metastases (p < 0.001) in colon cancer patients. These data indicate the antimetastatic effect of tumor-elevated kisspeptin in colon cancer patients that may be mediated by the effect of kisspeptin on EMAP-II expression in colon cancer tumors in patients with normal serum EMAP-II levels. These findings provide new insight into the role of kisspeptin in the context of metastases in colon cancer patients.

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

PTB-Associated Splicing Factor (PSF) Is a PPARγ-Binding Protein and Growth Regulator of Colon Cancer Cells

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor that plays an essential role in cell proliferation, apoptosis, and inflammation. It is over-expressed in many types of cancer, including colon, stomach, breast, and lung cancer, suggesting that regulation of PPARγ might affect cancer pathogenesis. Here, using a proteomic approach, we identify PTB-associated splicing factor (PSF) as a novel PPARγ-interacting protein and demonstrate that PSF is involved in several important regulatory steps of colon cancer cell proliferation. To investigate the relationship between PSF and PPARγ in colon cancer, we evaluated the effects of PSF expression in DLD-1 and HT-29 colon cancer cell lines, which express low and high levels of PPARγ, respectively PSF affected the ability of PPARγ to bind, and expression of PSF siRNA significantly suppressed the proliferation of colon cancer cells. Furthermore, PSF knockdown induced apoptosis via activation of caspase-3. Interestingly, DLD-1 cells were more susceptible to PSF knockdown-induced cell death than HT-29 cells. Our data suggest that PSF is an important regulator of cell death that plays critical roles in the survival and growth of colon cancer cells. The PSF-PPARγ axis may play a role in the control of colorectal carcinogenesis. Taken together, this study is the first to describe the effects of PSF on cell proliferation, tumor growth, and cell signaling associated with PPARγ.

Spheroid cells derived from human colon cancer cells exhibit epithelial to mesenchymal transition characteristics

Objective To investigate the similarities between cancer stem cells and epithelial mes- enchymal transition （EMT） cells in spheroid cells. Methods Generate cancer spheroid cells from colon cancer cell line DLD-1 in serum free medium （SFM） and to investigate the expression of colon cancer stem cells markers such as CD133, CD166,1eucine-rich-repeat-containing G-protein-coupled receptor 5 （ Lgr5 ） and the numbers of CD133^＋ cells. In addition, the capacity of migration,invasion and tumorigenicity in vivo and in vitro were confirmed by transwell assay, colony formation assay and mouse xenograft model respec- tively. Moreover, the expression of EMT-related genes was detected by real-time quantitative polymerase chain reaction （Real-time PCR） and Western blotting. Results The spheroid cells exhibit higher migra- tion,invasion,colony-formation and tumorigenicity properties. The CD133^＋ subpopulation was increased in spheroid cells. Moreover, the colon cancer stem cell markers such as CD133, CD166, Lgr5 and mesenchymal genes such as Vimentin and Snail were increased while ZO-1 decreased in spheroid cells. Surprisingly, E- cadherin-the key mediator of EMT was higher expressed too. Conclusion Although the E-cadherin was in- creased expression, considered the experiments in vitro and in vivo, we thought that E-cadherin may be not the sole cause of the malignant files in spheroid cells. Moreover, the spheroid cells exhibit cancer stem cells nrooerties and EMT Characteristics. Key words: Colon cancer; Cancer stem cell; Epithelial mesenchymal transition

Transcriptional Regulation ofFucosyltransferase 1Gene Expression in Colon Cancer Cells

The α1,2-fucosyltransferase I (FUT1) enzyme is important for the biosynthesis of H antigens, Lewis B, and Lewis Y. In this study, we clarified the transcriptional regulation of FUT1 in the DLD-1 colon cancer cell line, which has high expression of Lewis B and Lewis Y antigens, expresses the FUT1 gene, and shows α1,2-fucosyltransferase (FUT) activity. 5′-rapid amplification of cDNA ends revealed a FUT1 transcriptional start site −10 nucleotides upstream of the site registered at NM_000148 in the DataBase of Human Transcription Start Sites (DBTSS). Using the dual luciferase assay, FUT1 gene expression was shown to be regulated at the region −91 to −81 nt to the transcriptional start site, which contains the Elk-1 binding site. Site-directed mutagenesis of this region revealed the Elk-1 binding site to be essential for FUT1 transcription. Furthermore, transfection of the dominant negative Elk-1 gene, and the chromatin immunoprecipitation (CHIp) assay, supported Elk-1-dependent transcriptional regulation of FUT1 gene expression in DLD-1 cells. These results suggest that a defined region in the 5′-flanking region of FUT1 is critical for FUT1 transcription and that constitutive gene expression of FUT1 is regulated by Elk-1 in DLD-1 cells.

Identification and functional screening of microRNAs highly deregulated in colorectal cancer.

MicroRNAs (miRNAs) constitute a robust regulatory network with post-transcriptional regulatory efficiency for almost one half of human coding genes, including oncogenes and tumour suppressors. We determined the expression profile of 667 miRNAs in colorectal cancer (CRC) tissues and paired non-tumoural tissues and identified 42 differentially expressed miRNAs. We chose miR-215, miR-375, miR-378, miR-422a and miR-135b for further validation on an independent cohort of 125 clinically characterized CRC patients and for in vitro analyses. MiR-215, miR-375, miR-378 and miR-422a were significantly decreased, whereas miR-135b was increased in CRC tumour tissues. Levels of miR-215 and miR-422a correlated with clinical stage. MiR-135b was associated with higher pre-operative serum levels of CEA and CA19-9. In vitro analyses showed that ectopic expression of miR-215 decreases viability and migration, increases apoptosis and promotes cell cycle arrest in DLD-1 and HCT-116 colon cancer cell lines. Similarly, overexpression of miR-375 and inhibition of miR-135b led to decreased viability. Finally, restoration of miR-378, miR-422a and miR-375 inhibited G1/S transition. These findings indicate that miR-378, miR-375, miR-422a and miR-215 play an important role in CRC as tumour suppressors, whereas miR-135b functions as an oncogene; both groups of miRNA contribute to CRC pathogenesis.

Quantitative Structural Activity Relationship Studies for In Silico Prediction of In Vitro Cytotoxicity of NSAIDs in Colon Cancer Cell Lines

Non-steroidal anti-inflammatory drugs (NSAIDs) are evolving as the prototypical chemopreventive agents against colon cancer, an opinion nowadays reinforced by a substantial form of epidemiological, animal, and basic science data. Apart from their preventive role in the prophylaxis and management of colon cancer, NSAIDs at lower doses are widely employed in permutation with conventional anticancer drugs in order to reduce the dose related cytotoxic effects and to impart additive or synergistic therapeutic effect. In vitro cell-based cytotoxicity assays are effective techniques for hit ranking and lead optimization at the early stage of drug discovery. The present study has been focused on in silico screening and prediction of in vitro cytotoxicity (or growth inhibitory activity, GI50) of heterogeneous group of NSAIDs having flexibility in structure and cytotoxicity activity against DLD-1 and SW-480 colon cancer cell lines using 3DQSAR (3-dimensional quantitative structural activity relationship) SOMFA (self-organizing molecular field analysis) studies. Analysis of 3D-QSAR models through electrostatic and shape grids provide useful information about the steric, electrostatic potential contributions along with the combination of log P, total dipole moment and molar refractivity (MR) on GI50. The results obtained provided an insight on NSAIDs with optimum in vitro cytotoxicity activity and improved therapeutic profile. Keywords: NSAIDs, DLD-1 cells, SW-480 cells, COX-2 inhibitors, Colon cancer, sigmoidoscopy, colonoscopy, cohort, high-throughput, prostaglandin-mediated angiogenesis

MicroRNA-143 down-regulates Hexokinase 2 in colon cancer cells

BackgroundMicroRNAs (miRNAs) are well recognized as gene regulators and have been implicated in the regulation of development as well as human diseases. miR-143 is located at a fragile site on chromosome 5 frequently deleted in cancer, and has been reported to be down-regulated in several cancers including colon cancer.MethodsTo gain insight into the role of miR-143 in colon cancer, we used a microarray-based approach in combination with seed site enrichment analysis to identify miR-143 targets.ResultsAs expected, transcripts down-regulated upon miR-143 overexpression had a significant enrichment of miR-143 seed sites in their 3'UTRs. Here we report the identification of Hexokinase 2 (HK2) as a direct target of miR-143. We show that re-introduction of miR-143 in the colon cancer cell line DLD-1 results in a decreased lactate secretion.ConclusionWe have identified and validated HK2 as a miR-143 target. Furthermore, our results indicate that miR-143 mediated down-regulation of HK2 affects glucose metabolism in colon cancer cells. We hypothesize that loss of miR-143-mediated repression of HK2 can promote glucose metabolism in cancer cells, contributing to the shift towards aerobic glycolysis observed in many tumors.

Abstract 5226: Potential anti-tumor effect of a small molecule dipeptidyl peptidase inhibitor, 4175, in colorectal cancer

Abstract Introduction: Cetuximab is an effective therapeutic agent in a number of malignancies. Current data indicates that about 30% of colorectal cancer patients bearing mutated K-ras do not benefit from this agent. A possible mechanism of the antitumor effect of cetuximab is mediated through antibody-dependent cell-mediated cytotoxicity (ADCC). The present study is aimed to investigate the potential activity of Ari-4175, a broad -spectrum inibitor of prolyl peptidases and a potent immune stimulator in the treatment of K-ras mutant colorectal cancer xenografts as a single agent or in combination with cetuximab. Methods: The effect of Ari-4175 alone or in combination with cetuximab was evaluated both in vitro and in vivo. In vitro, the proliferation of K-ras mutant colon cancer cell lines DLD-1 and HCT-116 was detected after three days of culture in the medium containing various concentrations of Ari-4175 or cetuximab. In vivo, nude mice bearing DLD-1 or HCT-116 xenograft tumors were randomly divided into four groups, control, Ari-4175 alone, cetuximab alone and Ari-4175 plus cetuximab. Ari-4175 was administered orally at 100 ug, q.d or b.i.d and cetuximab was injected i.p at 200 ug per week. Tumor measurements were conducted twice a week. Peripheral blood was collected from the mice before the treatment or after 7 to 14 days of the treatment. CD16 expression on NK cells was monitored by flow cytometry. Results: Ari-4175 (10 nM ∼ 200 uM) alone or in combination with cetuximab did not show significant cytotoxicity on either DLD-1 or HCT-116 in cell culture. However, the growth of both DLD-1 and HCT-116 tumors were significantly blocked by the application of Ari-4175 in a dose-dependent manner. The combination of Ari-4175 with cetuximab lead to a further decrease in tumor size although not statistically significant, probably due to lower number of animals. Cetuximab alone did not show any therapeutic effect on HCT-116 xenograft but did have moderate efficacy on DLD-1 tumors. Treatment with Ari-4175 also increased the level of CD16 on mouse NK cells. Conclusion: The prolyl peptidase inhibitor, Ari-4175, showed anti-tumor effect in K-ras mutant colorectal cancer xengrafts when given alone or in combination with cetuximab. The therapeutic effect of 4175 might partially be due to the augmentation of ADCC through elevating expression of CD16 (FcγRIIIA) on NK cells. Our study provides the basis of testing Ari-4175 in a clinical trial. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5226. doi:1538-7445.AM2012-5226

Abstract 4528: Adiponectin receptor 2 is negatively associated with lymph node metastasis of colorectal cancer

Abstract [Background] Adiponectin is a hormone secreted by the adipose tissue. Two receptors of adiponectin, namely AdipoR1 and AdipoR2, are known, but their expression and function in tumor tissue are not yet well characterized. It is proverbial that under hypoxic condition, cancer cells acquire invasive and metastatic potentials and also resistance to therapy. Although adiponectin is reported to exert inhibitory effect on various cancer types, the regulation of AdipoRs by the hypoxic environment, nor on the effect of hypoxia on the inhibitory effect of adiponectin on cancer cells were investigated. Thus, we aimed to investigate the expression of adiponectin receptors in colorectal cancer tissues, and their clinicopathological implications. Moreover, we investigated on the mechanism underlying the regulation of AdipoRs by the hypoxic stress in colon cancer cells. [Methods] Surgically resected specimens from 48 patients with colorectal cancer, receiving surgical operation in the period between November 2008 and July 2009, were analyzed. The study was approved by the Human Ethics Committee of the University of Tokyo. The mRNA expressions of AdipoR1 and AdipoR2 were evaluated by real-time RT-PCR in cancer tissues and the matched normal counterparts. For the in vitro experiments, the human colon cancer cell line DLD-1 was cultured either under normoxia (21% O2) or hypoxia (1% O2), and the changes in the expression of AdipoRs were evaluated. Also, the effect of adiponectin on the proliferative activity of DLD-1 was assessed by the MTS assay. [Results] The mean age of the patients was 66.79±11.85 years. The levels of expression of both AdipoR1/AdipoR2 were significantly lower in cancer specimens compared with normal mucosa (0.966±0.392, vs1.366±0.408, p&amp;lt;0.001 and 0.918±0.309 vs1.596±0.459, P&amp;lt;0.001, respectively for AdipoR1 and AdipoR2). The mRNA levels of AdipoR1 and AdipoR2 showed a tendency of decrease in tumors with nodal metastases and the difference was significant with AdipoR2 (p&amp;lt;0.05). Culture under hypoxia resulted in a significant upregulation of the expression levels of both adiponectin receptors on DLD-1. Also, the inhibitory effect of adiponectin on the proliferative activity of DLD-1 was potentiated under hypoxia, compared to normoxia. [Conclusion] In colorectal cancer tissue, the expression levels of both adiponectin receptors were downregulated, and the expression of AdipoR2 was associated with nodal metastases. The hypoxic environment caused up-regulation of the expression of both adiponectin receptors on colon cancer cells, consequently potentiating the inhibitory effect of adiponectin. Taking these facts, we hypothesized that, under hypoxic condition, through up-regulation of adiponectin receptor, colon cancer cells become more sensitive to adiponectin, and those cells that do not up-regulate the expression of these receptors, are more aggressive, with higher metastatic potential. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4528. doi:1538-7445.AM2012-4528

Antitumor activities of ATP-competitive inhibitors of mTOR in colon cancer cells

BackgroundThe mammalian target of rapamycin (mTOR) is frequently activated in colon cancers due to mutations in the phosphatidylinositol 3-kinase (PI3K) pathway. Targeting mTOR with allosteric inhibitors of mTOR such as rapamycin reduces colon cancer progression in several experimental models. Recently, a new class of mTOR inhibitors that act as ATP-competitive inhibitors of mTOR, has been developed. The effectiveness of these drugs in colon cancer cells has however not been fully characterized.MethodsLS174T, SW480 and DLD-1 colon cancer cell lines were treated with PP242 an ATP-competitive inhibitor of mTOR, NVP-BEZ235, a dual PI3K/mTOR inhibitor or rapamycin. Tumor cell growth, proliferation and survival were assessed by MTS assay, 5-bromo-2'-deoxyuridine (BrDU) incorporation or by quantification of DNA fragmentation respectively. In vivo, the anticancer activity of mTOR inhibitors was evaluated on nude mice bearing colon cancer xenografts.ResultsPP242 and NVP-BEZ235 reduced the growth, proliferation and survival of LS174T and DLD-1 colon cancer cells more efficiently than rapamycin. Similarly, PP242 and NVP-BEZ235 also decreased significantly the proliferation and survival of SW480 cells which were resistant to the effects of rapamycin. In vivo, PP242 and NVP-BEZ235 reduced the growth of xenografts generated from LS174T and SW480 cells. Finally, we also observed that the efficacy of ATP-competitive inhibitors of mTOR was enhanced by U0126, a MEK inhibitor.ConclusionsTaken together, these results show that ATP-competitive inhibitors of mTOR are effective in blocking colon cancer cell growth in vitro and in vivo and thus represent a therapeutic option in colon cancer either alone or in combination with MEK inhibitors.