SW480 Colon Cancer Cells Research Articles

EGF ligand fused to truncated Pseudomonas�aeruginosa exotoxin�A specifically targets and inhibits EGFR‑positive cancer cells

Cancer cells have been known to overexpress the epidermal growth factor receptor (EGFR) and hence relevant multiple‑targeted therapies have been developed, with a recent clinical application of the antibody‑mediated inhibition of the EGFR. However, this strategy is not useful in cancer cells with mutations in KRAS; a GTPase downstream of EGFR which constitutively activates the pathway without EGF stimulation. Furthermore, mutations in EGFR also reduce the binding of monoclonal antibodies and thereby render them ineffective. In the present study, we designed a chimeric EGF protein fused to the truncated N‑terminal domainfragment of Pseudomonasaeruginosa exotoxinA (EGF‑ETA), which has ADP‑ribosylation activity and induces apoptosis. The EGF‑ETA protein was expressed in E.coli as a His‑tagged fusion. Our results showed that EGF‑ETA significantly inhibited the proliferation of EGFR‑positive A431 epidermoid carcinoma (IC50 27ng/ml) and HN5 head and neck squamous cell carcinoma (IC50 36ng/ml) cells. However, its effect on cancer cells with little or no EGFR expression was limited (A549‑IC50 1,000ng/ml; MCF‑7‑IC50>10,000ng/ml). Compared to cetuximab, EGF‑ETA was highly potent in its killing capacity of HN5 cancer cells at 1,000ng/ml, while cetuximab had little effect at 1,000ng/ml. Furthermore, EGF‑ETA was just as potent in HCT116 (KRAS G13D) and SW480 (KRAS G12V) colon cancer cell lines harbouring KRAS hyperactivating mutations when compared to KRAS wild‑type HT29 colon cancer cells. Finally, co‑incubation of EGF‑ETA with an anti‑EGF antibody abrogated its effect on the EGFR‑positive A431 cells. Our results show that the chimeric EGF‑ETA toxin is extremely effective against EGFR‑positive cancers and raises the potential to further develop this chimera for use in targeting EGFR‑positive tumours resistant to monoclonal antibodies.

Propofol Promotes Activity and Tumor-Killing Ability of Natural Killer Cells in Peripheral Blood of Patients with Colon Cancer.

BackgroundWe investigated the effect of propofol on activities and tumor-killing ability of natural killer (NK) cells in patients with colon cancer.Material/MethodsTwenty colon cancer patients and 20 healthy subjects were included. Peripheral blood (5 ml) was collected from all patients and healthy subjects. NK cells in peripheral blood were separated by negative screening using immunomagnetic beads. Flow cytometry was used to determine expression of activated receptors, inhibitory receptors, killing effector molecules, and proliferation-associated markers on NK cell surfaces. After in vitro treatment with propofol for 24 h, expression of activated receptors, inhibitory receptors, killing effector molecules, and proliferation-associated markers on NK cell surfaces was examined again. In addition, the tumor-killing effect of NK cells was studied by co-culture with K562 cells or colon cancer SW620 cells at a ratio of 1: 1.ResultsThe number of NK cells in peripheral blood from colon cancer patients was increased compared with healthy subjects, but activities and proliferation ability of the NK cells were decreased. The tumor-killing effect of NK cells isolated from colon cancer patients was decreased. Of note, propofol promoted activation of NK cells from colon cancer patients. In addition, propofol increased expression of tumor-killing effector molecules by NK cells and the proliferation ability of NK cells. Propofol also enhanced the killing effect of NK cells on colon cancer cells.ConclusionsThe present study demonstrates that propofol promotes the activity and tumor-killing ability of NK cells in peripheral blood of patients with colon cancer.

Distinct substrate specificities of human GlcNAc-6-sulfotransferases revealed by mass spectrometry–based sulfoglycomic analysis

Sulfated glycans are known to be involved in several glycan-mediated cell adhesion and recognition pathways. Our mRNA transcript analyses on the genes involved in synthesizing GlcNAc-6-O-sulfated glycans in human colon cancer tissues indicated that GlcNAc6ST-2 (CHST4) is preferentially expressed in cancer cells compared with nonmalignant epithelial cells among the three known major GlcNAc-6-O-sulfotransferases. On the contrary, GlcNAc6ST-3 (CHST5) was only expressed in nonmalignant epithelial cells, whereas GlcNAc6ST-1 (CHST2) was expressed equally in both cancerous and nonmalignant epithelial cells. These results suggest that 6-O-sulfated glycans that are synthesized only by GlcNAc6ST-2 may be highly colon cancer-specific, as supported by immunohistochemical staining of cancer cells using the MECA-79 antibody known to be relatively specific to the enzymatic reaction products of GlcNAc6ST-2. By more precise MS-based sulfoglycomic analyses, we sought to further infer the substrate specificities of GlcNAc6STs via a definitive mapping of various sulfo-glycotopes and O-glycan structures expressed in response to overexpression of transfected GlcNAc6STs in the SW480 colon cancer cell line. By detailed MS/MS sequencing, GlcNAc6ST-3 was shown to preferentially add sulfate onto core 2-based O-glycan structures, but it does not act on extended core 1 structures, whereas GlcNAc6ST-1 prefers core 2-based O-glycans to extended core 1 structures. In contrast, GlcNAc6ST-2 could efficiently add sulfate onto both extended core 1- and core 2-based O-glycans, leading to the production of unique sulfated extended core 1 structures such as R-GlcNAc(6-SO3-)β1-3Galβ1-4GlcNAc(6-SO3-)β1-3Galβ1-3GalNAcα, which are good candidates to be targeted as cancer-specific glycans.

Long noncoding RNA kcna3 inhibits the progression of colorectal carcinoma through down-regulating YAP1 expression

Long non-coding RNAs (lncRNAs) regulate diverse cellular processes, and their anomalous expression exert an essential role in the progression of many kinds of cancers, including colorectal carcinoma (CRC). The objective of this study was to investigate the role of lncRNA kcna3 and its underlying mechanism in CRC progression. The expression of lncRNA kcna3 in human CRC tissues and the adjacent non-tumor tissues was evaluated by RT-PCR. The correlations between lncRNA kcna3 expression levels and the overall survival (OS), as well as the clinicopathological features of CRC patients were analyzed. Gain-of-function and loss-of-function experiments were used to evaluate the effects of lncRNA kcna3 on the proliferation, apoptosis, migration, invasion and tumorigenesis of colon cancer SW620 cells. We found that lncRNA kcna3 was lowly expressed in CRC tissues, and its low expression was closely associated with patients’ higher TNM grade and the higher occurrence rate of lymphatic metastasis and distant metastasis, as well as shorter OS. Enhanced expression of lncRNA kcna3 inhibited SW620 cells’ proliferation, migration and invasion, and induced cell apoptosis in vitro, and repressed CRC tumor growth in vivo. Whereas knockdown of lncRNA kcna3 showed the opposite results. Mechanistically, up-regulation of lncRNA kcna3 decreased YAP1 protein expression and accelerated its degradation. The effects of lncRNA kcna3 overexpression on cell growth and tumorigenesis inhibition and apoptosis promotion were weakened when the expression of YAP1 was up-regulated. In conclusion, this study revealed that lncRNA kcna3 exerts a tumor-inhibit role in CRC progression through down-regulating YAP1 expression, indicating that lncRNA kcna3/YAP1 might be served as a new prognostic biomarker and therapeutic target for CRC.

Upregulation of PD‑L1 expression by resveratrol and piceatannol in breast and colorectal cancer cells occurs via HDAC3/p300‑mediated NF‑κB signaling.

Programmed cell death ligand 1 (PD-L1) expressed in cancer cells interacting with its receptor programmed cell death 1 (PD-1) expressed in immune cells represents a regulatory axis linked to the suppression and evasion of host immune functions. The blockade of PD-1/PD-L1 interaction using monoclonal antibodies has emerged as an effective therapy for several solid tumors; however, durable response has been observed in a subset of patients with PD-L1-positive tumors. Thus, the understanding of the mechanisms responsible for the expression of PD-L1 in tumor cells may help to improve the response to PD-L1 blockade therapies. In this study, we investigated whether resveratrol, a grape-derived stilbenoid with immunoregulatory activity, modulates the expression of PD-L1 in breast and colorectal cancer cells. The surface expression of PD-L1 was determined by flow cytometry in cancer cells treated with resveratrol and/or piceatannol. Each stilbenoid alone induced PD-L1 and when used in combination, elicited a synergistic upregulation of PD-L1 in some cell lines. The induction of PD-L1 by the combined use of stilbenoids was most pronounced in the Cal51 triple-negative breast cancer (TNBC) and SW620 colon cancer cells. The observed induction of PD-L1 was transcriptionally mediated by nuclear factor (NF)-κB, as shown by NF-κB reporter assays, the nuclear accumulation of the p65 subunit of NF-κB, inhibition by the IKK inhibitor, BMS-345541, and histone the modification inhibitors, resminostat, entinostat or anacardic acid. Combined treatment with resveratrol and piceatannol also decreased tumor cell survival as indicated by the upregulation of the DNA damaging marker, γH2AX, the cleavage of caspase 3, the downregulation of the survival markers, p38-MAPK/c-Myc, and G1-to-S cell cycle arrest.

Butyrate upregulates the TLR4 expression and the phosphorylation of MAPKs and NK-κB in colon cancer cell in vitro.

Microbiota and its induced inflammation in colorectal mucosa have been considered risk factors for the development of colorectal carcinogenesis. Previous studies demonstrated that the coexisting elements of microbiota in the gut, such as short chain fatty acids (SCFAs) and lipopolysaccharides (LPS), which exhibited regulatory effects on the intestinal epithelial cells individually. Unfortunately, the association between butyrate and the toll-like receptor (TLR) signaling pathway in the development of colon cancer is not fully elucidated. In the present study, by culturing human colon cancer SW480 cells or mouse colon cancer CT26 cells with butyrate and/or TLR4 ligand LPS in vitro, it was identified that butyrate suppressed the growth and promoted apoptosis of these cancer cells. Notably, the expression levels of TLR4 and CD14 were markedly increased on these butyrate-treated cells, but not on LPS-alone treated cells. Additionally, butyrate treatment induced the phosphorylation of extracellular signal-regulated kinase, tumor protein 38, c-Jun NH2-terminal kinase and nuclear factor-κB (NF-κB) p65, and then promoted the pro-inflammatory cytokine tumor necrosis factor-α, but not interleukin 6 secretion in SW480 and CT26 cells. Therefore, butyrate treatment regulates the expression of TLR4, mitogen-activated protein kinase and NF-κB signal pathway activation and pro-inflammatory response in vitro. Although the exact mechanisms have not been fully explored, these results suggested that butyrate and LPS-TLR4 signaling mediated innate immunity in colon cancer cells through two distinct but inter-regulated pathways. Thus, butyrate can further initiate innate immunity against tumor cells by upregulating the TLR4 expression and activation to preserve intestinal homeostasis.

Inositol hexaphosphate limits the migration and the invasiveness of colorectal carcinoma cells in vitro.

Inositol hexaphosphate (IP6), also known as phytic acid, has been shown to exhibit anticancer effects in a number of preclinical tumor models. IP6 decreases proliferation by arresting cells in the G0/G1phase, inhibits iron-mediated oxidative reactions, enhances differentiation and stimulates apoptosis. The present study attempted to characterize the effect of IP6 on the migration and adhesion of colon cancer SW620 cells. IP6 was assessed at concentrations of 0.2 and 1mM during 12, 24 and 48h of exposure. Migration ability was measured with the real-time xCELLigence Real-Time Cell Analyzer Dual Purpose system. The expression of mRNA and proteins involved in migration and cancer progression [epithelial cell adhesion molecule, intercellular adhesion molecule-1, β-catenin, N-cadherin, E-cadherin, matrix metalloproteinase(MMP)-2 and MMP-9] was determined by reverse transcription-quantitative polymerase chain reaction and western blot analysis. The changes in the expression and subcellular localization of E-cadherin were determined by indirect immunofluorescence. IP6 induced a decrease in the migration ability of the tested SW620 cell line. IP6-treated cells also showed decreased expression of N-cadherin, increased levels of E-cadherin and decreased expression of MMP-2 and MMP-9. These results indicated that IP6 has potential to modulate the migration ability and expression of markers associated with invasion in SW620 cells; however, further analysis is necessary to obtain a detailed understanding of the mechanism of action.

Identification of potential small-molecule protein-protein inhibitors of cancer metastasis by 3D epitope-based computational screening.

In cancer cells exposed to extracellular pressure or shear stress, AKT1-FAK interaction drives focal adhesion kinase (FAK) phosphorylation, leading to force-activated cancer cell adhesion and metastasis. Blocking the AKT1-FAK interaction is therefore an attractive target for cancer therapy, avoiding the side effects of global FAK inhibition. Starting with our previous identification of a short FAK peptide that binds AKT1, we identified a series of small-molecule inhibitor candidates using a novel approach for inhibiting protein-protein interactions. Using a 3D structural fragment of the FAK peptide as the query, millions of drug-like, commercially available molecules were screened to identify a subset mimicking the volume and chemistry of the FAK fragment to test for their ability to block pressure-sensitive FAK phosphorylation by AKT1. Two compounds reduced the stimulation of FAK phosphorylation in response to extracellular pressure in human SW620 colon cancer cells without affecting basal FAK phosphorylation. Thus, using a 3D protein interaction epitope as a novel query for ligand-based virtual screening can successfully identify small-molecules that show promise in modulating cancer cell adhesion and metastasis.

Abstract 2436: Anti-cancer effect by combination treatment of CDK and HSP90 inhibitors through HIF1α inhibition

Abstract Hypoxia-inducible factor 1α (HIF1α) is the main mediator of the adaptive response to intra-tumoral hypoxia. HIF1α overexpression contributes to tumor angiogenesis, cancer cell survival and metastasis. Thus, targeting HIF1α provides new opportunities for cancer therapy. We have previously shown that cyclin-dependent kinase 1 (CDK1) stabilizes HIF1α through direct phosphorylation of its Ser668 residue in a Von Hippel-Lindau (VHL)-independent or p53-independent manner both under hypoxia and at G2/M under normoxia (Warfel et al., Cell Cycle, 2013). Because heat shock protein 90 (HSP90) is a VHL-independent HIF1α stabilizer, we hypothesized CDK and CDK inhibitor effects in the stabilization/destabilization mechanism. We found that CDK1 inhibition disrupts the interaction between HSP90 and HIF1α. Moreover, administration of the CDK1 inhibitor, Ro-3306, partially reversed a heat shock (40°C) response dependent increase in the level of HIF1α, which suggests that CDK1 activity may contribute to HSP90-mediated HIF1α stabilization. Combination treatment with both HSP90 inhibitor and CDK1 inhibition/knockdown decreased HIF1α level more robustly than either single treatment. Dual inhibition of CDK1 and HSP90 not only synergistically decreased cell viability but also remarkably reduced colony formation of HCT116 colon cancer cells. Previously we have also shown that similar to CDK1, CDK4 plays a role in HIF1α stabilization as well. This led us to investigate the effect of CDK4/HSP90 dual inhibition on colorectal cancer cells. The combination treatment of CDK4 knockdown/inhibition and HSP90 inhibition reduced the level of HIF1α in various cancer cell lines (e.g., colorectal, glioblastoma, prostate cancers). The FDA-approved CDK4 inhibitor palbociclib along with ganetespib synergistically inhibited cell viability in SW480 colon cancer cells under hypoxia or normoxia. No reduction in cell viability was noted in WI38 normal cells under normoxia at similar concentrations. In addition, we tested the therapeutic potential of the dual CDKi/HSP90i therapy in vivo. The combination treatment of palbociclib and ganetespib inhibited tumor growth in the HT29 colon cancer cell xenograft mouse model at relatively low doses. Immunohistochemistry staining of the tumor samples revealed higher levels of apoptosis, lower levels of VEGF expression and reduced microvessel formation in the combination treatment group. Our findings provide a compelling rationale for a therapeutic strategy to target HIF1α through the combination of CDK and HSP90 inhibitors in cancer therapy. Citation Format: Shuai Zhao, Lanlan Zhou, David T. Dicker, Wafik S. El-Deiry. Anti-cancer effect by combination treatment of CDK and HSP90 inhibitors through HIF1α inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2436.

Abstract LB-177: Quantification of cell signaling proteins by immuno-MALDI

Abstract Introduction. To improve cancer patient stratification and overcome the drawbacks of currently used approaches to assess signaling pathway proteins, we set out to develop immuno-matrix assisted laser ionization/desorption (iMALDI) assays combined with a phosphatase-based phosphopeptide quantitation (PPQ) approach to measure PI3K/AKT/mTOR pathway activity. Specifically, we targeted the C-terminal tryptic peptides of AKT1 and AKT2 due to their involvement in full kinase activation. Methods. Following trypsin digestion of cell lysate, stable isotope-labeled standard (SIS) peptides are added. After splitting the solution, one aliquot is treated with phosphatase. Bead-coupled antibodies enrich the non-phosphorylated target peptides, which are washed and spotted onto a MALDI plate, and acidic MALDI matrix elutes the peptides. The resulting light/heavy ratios of both aliquots allow the calculation of protein expression levels and peptide phosphorylation stoichiometry. Results. The iMALDI assays were validated for linear range and accuracy, as well as interference screening, requiring only ~50 µg of total cell or tissue lysate protein to quantify both AKT1 and AKT2 expression levels and phosphorylation stoichiometry. CVs of technical replicates were found to consistently be below 10%. We were able to quantify AKT1 and AKT2 from various cell lines and fresh frozen tumor samples, including SW480 and HCT116 colon cancer cell lines, MDA-MB-231 breast cancer cells, and colon cancer and breast cancer tumor lysates. Further, a direct comparison of matched fresh frozen and formalin-fixed paraffin-embedded (FFPE) tissues showed that the expression levels and phosphorylation stoichiometry quantified differ depending on the tissue preservation method, and that phosphorylation stoichiometries above 30% occur in only a small subset of samples. A direct comparison of four pairs of normal and adjacent tumor tissues showed elevated AKT1 phosphorylation stoichiometry of ~40% in a colorectal cancer liver metastasis, and significantly elevated AKT1 (3.6-fold) and AKT2 (2.2-fold) expression levels in a surgical breast tumor sample. Future directions. In a next step, patient-derived mouse xenograft tissue samples, collected after specific drug treatment, will be analyzed, and the AKT results will be correlated to genomic data to answer the hypothesis whether the AKT expression levels and phosphorylation stoichiometries correlate with response to treatment. Citation Format: Robert Popp, René P. Zahedi, André LeBlanc, Yassene Mohammed, Adriana Aguilar-Mahecha, Oliver Pötz, Mark Basik, Gerald Batist, Christoph H. Borchers. Quantification of cell signaling proteins by immuno-MALDI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-177.

Oncogenic heterogeneous nuclear ribonucleoprotein D-like promotes the growth of human colon cancer SW620 cells via its regulation of cell-cycle.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins. Heterogeneous nuclear ribonucleoprotein D-like (HNRPDL) is a member of this family. Though aberrant expression of HNRPDL has been reported in a few cancers, whether HNRPDL is deregulated in colon cancer patients and what role this protein plays in these cells are not known yet. In this study, we found that HNRPDL was significantly up-regulated in colon cancer specimens than control. We also demonstrated that HNRPDL silencing inhibited the growth of SW620 cells both in vitro and in vivo. Conversely, we constructed a retroviral vector to deliver HNRPDL into non-malignant NIH-3T3 cells and injected these cells into nude mice. HNRPDL-overexpressing NIH-3T3 cells generated tumors in nude mice but not the control cells. Mechanistically, HNRPDL promoted cell-cycle progression associated with enhanced expressions of cyclin D3 and Ki-67 but decreased expressions of p53 and p21. Taken together, our data demonstrate that HNRPDL is aberrantly expressed in colon cancer cells, which promotes the growth of these cells by activating cell-cycle progression.

WDR5 supports colon cancer cells by promoting methylation of H3K4 and suppressing DNA damage

BackgroundKMT2/MLL proteins are commonly overexpressed or mutated in cancer and have been shown to support cancer maintenance. These proteins are responsible for methylating histone 3 at lysine 4 and promoting transcription and DNA synthesis; however, they are inactive outside of a multi-protein complex that requires WDR5. WDR5 has been implicated in cancer for its role in the COMPASS complex and its interaction with Myc; however, the role of WDR5 in colon cancer has not yet been elucidated.MethodsWDR5 expression was evaluated using RT-qPCR and western blot analysis. Cell viability and colony forming assays were utilized to evaluate the effects of WDR5 depletion or inhibition in colon cancer cells. Downstream effects of WDR5 depletion and inhibition were observed by western blot.ResultsWDR5 is overexpressed in colon tumors and colon cancer cell lines at the mRNA and protein level. WDR5 depletion reduces cell viability in HCT116, LoVo, RKO, HCT15, SW480, SW620, and T84 colon cancer cells. Inhibition of the WDR5:KMT2/MLL interaction using OICR-9429 reduces cell viability in the same panel of cell lines albeit not to the same extent as RNAi-mediated WDR5 depletion. WDR5 depletion reduced H3K4Me3 and increased phosphorylation of H2AX in HCT116, SW620, and RKO colon cancer cells; however, OICR-9429 treatment did not recapitulate these effects in all cell lines potentially explaining the reduced toxicity of OICR-9429 treatment as compared to WDR5 depletion. WDR5 depletion also sensitized colon cancer cells to radiation-induced DNA damage.ConclusionsThese data demonstrate a clear role for WDR5 in colon cancer and future studies should examine its potential to serve as a therapeutic target in cancer. Additional studies are needed to fully elucidate if the requirement for WDR5 is independent of or consistent with its role within the COMPASS complex. OICR-9429 treatment was particularly toxic to SW620 and T84 colon cancer cells, two cell lines without mutations in WDR5 and KMT2/MLL proteins suggesting COMPASS complex inhibition may be particularly effective in tumors lacking KMT2 mutations. Additionally, the ability of WDR5 depletion to amplify the toxic effects of radiation presents the possibility of targeting WDR5 to sensitize cells to DNA-damaging therapies.

β-Catenin gene promoter hypermethylation by reactive oxygen species correlates with the migratory and invasive potentials of colon cancer cells.

Over half of the colon cancer patients suffer from cancer-related events, mainly metastasis. Loss of β-catenin activity has previously been found to facilitate cancer cell dissociation and migration. Here, we aimed to investigate whether epigenetic silencing of β-catenin induces human colon cancer cell migration and/or invasion. HCT-116, Caco-2, HT-29 and SW620 cell migration and invasion capacities were assessed using scratch wound healing and Matrigel invasion assays, respectively. Confocal microscopy, qRT-PCR and Western blotting were performed to determine gene expression levels, whereas methylation-specific quantitative real-time PCR was used to assess the extent of β-catenin gene (CTNNB1) promoter methylation after treatment of the cells with TPA, hydrogen peroxide, 5-aza-2'-deoxycytidine and/or VAS2870. We found that treatment of HT-29 and Caco-2 cells (differentiated and low metastatic) with 12-O-tetradecanoyl phorbol-13-acetate (TPA; a tumor promoter) suppressed E-cadherin and β-catenin expression at both the mRNA and protein levels and, in addition, enhanced cell migration. Furthermore, we found that the CTNNB1 gene promoter methylation levels were higher in the more invasive HCT-116 and SW620 colon cancer cells than in HT-29 and CCD-841 (normal colon epithelial) cells. We also found that TPA or hydrogen peroxide induced CTNNB1 gene promoter methylation to a higher extent in HT-29 and CCD-841 cells than in HCT-116 and SW620 cells, and that the degree of CTNNB1 gene promoter methylation positively correlated with cell dissociation and migration. In addition, we found that co-treatment with 5-aza-2'-deoxycytidine (decitabine, a DNA methyl transferase inhibitor) and VAS2870 (a NADPH oxidase inhibitor) almost completely blocked the invasion of TPA-treated HT-29 and TPA-untreated HCT-116 and SW620 cells, and that these inhibitions surpassed those of the cells treated with decitabine or VAS2870 alone. From our data we conclude that the extent of CTNNB1 gene promoter methylation by reactive oxygen species correlates with the migratory and invasive abilities of colon cancer cells. Our results suggest that epigenetic regulation of CTNNB1 may serve as a novel avenue to block colon cancer cell migration and invasion.

Cytotoxic, Anti-Proliferative and Apoptosis Activity of l-Amino Acid Oxidase from Malaysian Cryptelytrops purpureomaculatus (CP-LAAO) Venom on Human Colon Cancer Cells.

The aim of this study is to investigate the potential anti-cancer activity of l-amino acid oxidase (CP-LAAO) purified from the venom of Cryptelytrops purpureomaculatus on SW480 and SW620 human colon cancer cells. Mass spectrometry guided purification was able to identify and purify CP-LAAO. Amino acid variations identified from the partial protein sequence of CP-LAAO may suggest novel variants of these proteins. The activity of the purified CP-LAAO was confirmed with o-phenyldiamine (OPD)-based spectrophotometric assay. CP-LAAO demonstrated time- and dose-dependent cytotoxic activity and the EC50 value was determined at 13 µg/mL for both SW480 and SW620 cells. Significant increase of caspase-3 activity, reduction of Bcl-2 levels, as well as morphological changes consistent with apoptosis were demonstrated by CP-LAAO. Overall, these data provide evidence on the potential anti-cancer activity of CP-LAAO from the venom of Malaysian C. purpureomaculatus for therapeutic intervention of human colon cancer.

A Bayesian statistical analysis of stochastic phenotypic plasticity model of cancer cells

The phenotypic plasticity of cancer cells has received special attention in recent years. Even though related models have been widely studied in terms of mathematical properties, a thorough statistical analysis on parameter estimation and model selection is still very lacking. In this study, we present a Bayesian approach which is devised to deal with the data sets containing both mean and variance information of relative frequencies of cancer stem cells (CSCs). Both Gibbs sampling and Metropolis-Hastings (MH) algorithm are used to perform point and interval estimations of cell-state transition rates between CSCs and non-CSCs. Extensive simulations demonstrate the validity of our model and algorithm. By applying this method to a published data on SW620 colon cancer cell line, the model selection favors the phenotypic plasticity model, relative to conventional hierarchical model of cancer cells. Further quantitative analysis shows that, in the presence of phenotypic equilibrium, the variance data greatly influences the time-variant pattern of the parameters. Moreover, it is found that the occurrence of self-renewal of CSCs shows a strong negative correlation with de-differentiation rate from non-CSCs to CSCs, suggesting a balancing mechanism in the heterogenous population of cancer cells.

Proliferation and invasion of colon cancer cells are suppressed by knockdown of TOP2A.

Recent research has shown that TOP2A plays an important role in the tumorigenesis of many malignancies, such as breast cancer, ovarian cancer, and prostate cancer. However, few studies have been conducted on TOP2A expression and functions in colon cancer. In the present study, we found that TOP2A expression was obviously elevated in colon cancer tissues compared to adjacent non-cancerous tissues. Depletion of TOP2A in HCT116 and SW480 colon cancer cells by transfection of specific small interfering RNA significantly suppressed proliferation and inhibited invasion of cells, even induced apoptosis as indicated by both MTT assay, Annexin V/propidium iodide staining, and Transwell assay. Furthermore, we explored the underlying mechanisms. Knockdown of TOP2A not only affects the expression of cell apoptosis-related (Bcl-2 and Bax) and invasion-related proteins (MMP-2 and MMP-9), but also reduced the phosphorylation levels of ERK and AKT. In conclusion, we showed that TOP2A was upregulated in colon cancer tissue samples and that TOP2A may serve as an oncogene in colon cancer.

The role of Her2-Nrf2 axis in induction of oxaliplatin resistance in colon cancer cells

Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a pivotal role in promoting chemoresistance by regulation of antioxidants and detoxification enzymes. Her2 is a member of tyrosine kinase receptor family with a key function in resistance of cancer cells to chemotherapeutics. The aim of this study was to investigate the possible cross talk between Nrf2 and Her2 mediated signaling pathways in development of oxaliplatin resistance in colon cancer cells. We first generated oxaliplatin-resistant LS174T and SW480 colon cancer cells with different Her2 expression levels by employing IC50 concentrations followed by a resting period. We evaluated the viability and apoptosis of the cells by MTT and flow cytometry assays, respectively. Nrf2 and Her2 gene expression levels were examined by qRT-PCR. The morphology analysis and combination index calculation were performed using the ImagJ and CompuSyn softwares, respectively. Development of resistant cells revealed a marked increase in half maximal inhibitory concentration (IC50) value from 3.95 ± 0.92 μM to 29.27 ± 3.13 μM in SW480 cells and 377 ± 46 nM to 9.59 ± 0.76 μM in LS174T cells with a significant change in morphology of the cells from elongated to small round shape (p < 0.05). Her2 expression level was increased in both types of resistant cells, but the Nrf2 expression was increased in LS174T resistant (LS174T/Res) cells and decreased in SW480/Res cells which were consistent with the level of resistance in these cells (25 fold increase in IC50 value in LS174T/Res cells versus 7 fold increase in this value in SW480/Res cells). Inhibition of either Nrf2 or Her2 alone and in combination caused a significant increase in oxaliplatin-induced cytotoxicity and apoptosis with maximum effects in SW480/Res cells with low Her2 and Nrf2 expression levels. Altogether, our results suggest that inhibition of Nrf2 signaling in colon cancer patients with Her2 overexpression can be considered as an important strategy to overcome oxaliplatin resistance.

Chemodiversity of Cirsium fruits: Antiproliferative lignans, neolignans and sesquineolignans as chemotaxonomic markers

While analyzing the fruit composition of nine European Cirsium species representing three sections (i.e., Cephalonoplos, Chamaeleon and Eriolepis), four lignans, three neolignans and three sesquineolignans were determined and used as chemotaxonomic markers. Among them, desmethyl balanophonin and desmethyl picrasmalignan were determined for the first time in the plant kingdom, as the main metabolites of the Chamaeleon section. Prebalanophonin and prepicrasmalignan, identified so far exclusively in C. eriophorum, were also confirmed in C. boujartii and C. vulgare, highlighting the chemotaxonomic significance of these compounds in the Eriolepis section. The antiproliferative assay of the compounds isolated from their optimum sources, confirmed a dose-dependent inhibitory effect of the structures bearing the 4′,7-epoxy moiety (balanophonin, picrasmalignan, desmethyl balanophonin, desmethyl picrasmalignan) against SW480 colon cancer cells, while those bearing the 4′,7-dihydroxy motif (prebalanophonin, prepicrasmalignan) were inactive.

LncRNA MALAT1 induces colon cancer development by regulating miR-129-5p/HMGB1 axis.

Recent studies have exhibited significant roles of lncRNAs in various tumors' development, including colon cancer. Our study focused on the biological roles of lncRNA MALAT1 in colon cancer. In our study, it was demonstrated that MALAT1 was upregulated in human colon cancer cell lines including Lovo, HCT116, SW480, and HT29 cells compared to the normal human intestinal epithelial HIEC cells. Moreover, we observed that miR-129-5p was downregulated in colon cancer cells with a significant increase of HMGB1 expression. Inhibition of MALAT1 can inhibit the proliferation of colon cancer SW480 and HCT116 cells and next, bioinformatics analysis was used to predict the target microRNA of MALAT1. miR-129-5p was identified and confirmed as a direct regulator of MALAT1 and it was shown that miR-129-5p mimics were able to restrain the progression of colon cancer cells. In addition, high motility group box protein 1 (HMGB1), was predicted as a mRNA target of miR-129-5p. Furthermore, we found that MALAT1 exerted its biological functions through regulating HMGB1 by sponging miR-129-5p in vitro. Silencing MALAT1 greatly inhibited HMGB1 expression which can be reversed by miR-129-5p inhibitors. It was indicated in our investigation that MALAT1 may serve as a competing endogenous lncRNA (ceRNA) to mediate HMGB1 by sponging miR-129-5p in colon cancer. Taken together, our results indicated that MALAT1/miR-129-5p/HMGB1 axis could be provided as an important prognostic biomarker in colon cancer development.

Role and mechanism of Annexin A9 in the proliferation of human colon carcinoma cell line SW620

Objective To investigate the role of Annexin A9 (ANXA9) in the proliferation of human colon cancer cell line SW620 and the underlying mechanism. Methods The expression of ANXA9 in human colon cancer cell lines HT29, SW620, SW480, LoVo and SW1116 was detected by real-time quantitative polymerase chain reaction (Real-time PCR) and Western blotting. SW620 cell lines with the strongest expression of ANXA9 was transfected with 40 nmol/L ANXA9-small interfering RNA (siRNA) to inhibit the expression of ANXA9. Cell counting kit-8 (CCK-8) assay and flow cytometry (FCM) were correspondingly used to examine the effect of transfection on the activity and cell cycle of SW620 cells. The expression of proliferating cell nuclear antigen (PCNA), Cyclin D, Cyclin E, p21 and p16 was detected by Real-time PCR and Western blotting. Results The mRNA and protein expression levels of ANXA9 in SW620 cells were the highest in human colon cancer cell lines HT29, SW620, SW480, LoVo and SW1116 and mRNA expressions were as following: 0.027±0.004, 0.041±0.005, 0.028±0.003, 0.033±0.003, 0.025±0.005; protein expressions were as following: 0.287±0.076, 1.246±0.103, 0.326±0.040, 0.387±0.097, 0.295±0.064 (F=8.212, P=0.003; F=81.728, P=0.000). Expressions of ANXA9 mRNA and protein in transfection group, control group, blank group were (0.209±0.016, 0.317±0.104), (0.957±0.070, 0.647±0.155), (1.031±0.171, 0.727±0.145). The ANXA9 mRNA and protein expression in the transfection group was significantly lower than in the control and blank group (F=54.072, P=0.000; F=7.601, P=0.023). Results of CCK-8 showed that cell activity in transfection group, control group, blank group was as following: 24 h (0.605±0.024, 0.612±0.022, 0.628±0.027), 48 h (0.810±0.049, 1.196±0.118, 1.308±0.070), 72 h (1.145±0.070, 1.531±0.062, 1.454±0.081). Cell activity in transfection group were significantly lower than the control and blank group (F=38.742, P=0.000; F=32.56, P=0.000). The percentage of cells in G0/G1 phase, G2/M phase, S phase was (66.870±3.850)%, (15.060±2.480)%, (18.080±1.420)% in transfection group; 50.070±3.370)%, (32.520±2.500)%, (17.410±0.920)% in control group; (48.740±2.170)%, (32.390±1.820)%, (19.210±0.390)% in blank group. The percentage of G0/G1 phase cells in the transfection group increased (F=29.752, P=0.001), and the proportion of G2/M phase decreased (F=57.860, P=0.000), while the proportion of S phase cells had no significant change (F=1.568, P=0.284). The expression of Cyclin D1 and Cyclin E1 was significantly lower after ANXA9-siRNA transfection (mRNA: F=462.821, 5.512, P=0.000, 0.044; protein: F=15.148, 8.300, P=0.005, 0.019), and that of p21 was significantly increased (mRNA: F=6.742, P=0.032; protein: (F=21.230, P=0.002). Conclusion ANXA9 may participate in the proliferation of colon cancer cell line SW620 possibly through the expression of Cyclin D1, Cyclin E1, p21. Key words: Colon cancer; Annexin A9; Proliferation