5-Fluorouracil upregulates the activity of Wnt signaling pathway in CD133-positive colon cancer stem-like cells

Background and Objective:CD133-positive colon cancer stem like cells (CSLCs) are resistant to the conventional cytotoxic drug 5-fluorouracil (5-FU).Wnt signaling pathway plays important roles in colon cancer carcinogenesis and metastasis, and regulates the self-renewal capacity of CSLCs.In the present study, we explored the impact of 5-FU on Wnt signaling pathway of CD133-positive colon CSLCs, and the relation between Wnt signaling pathway and drug resistance of CD133-positive colon CSLCs.Methods:Magnetic activation cell separation was used to collect CD133-positive cells from colon cancer cell line DLD1, which was transfected with luciferase reporter for Wnt signaling activity.The activity of Wnt signaling pathway was compared between CD133-positive and CD133-negative cells.After the treatment with 1 μg/mL of 5-FU, the cell proliferation rates of DLD1 cells, CD133-positive cells, and CD133-negative cells were compared.After the treatment with 1 μg/mL and 10 μg/mL of 5-FU for 48 h, Wnt activity was compared between CD133-positive and CD133-negative cells.The expression of CD133 and cell apoptosis of CD133-positive cells was detected after exposure to 50 ng/mL of dickkopf (DKK)-1, a Wnt pathway inhibitor.Results:After the treatment with 5-FU, the cell proliferation rate of CD133-positive cells was higher than that of CD133-negative cells and the sensitivity of CD133-positive cells to 5-FU decreased.Wnt activity was higher in CD133-positive cells than in CD133-negative cells [(46.3±0.3)% vs.(33.9±2.7)%, P=0.009].After the treatment with 1 μg/mL and 10 μg/mL of 5-FU, Wnt activity of CD133-positive cells was (90.1±10.0)% (P=0.012) and (52.9±2.5)% (P=0.047), respectively, whereas that of CD133-negative cells was (35.5±3.3)% (P=0.434) and (26.5±0.4)% (P=0.046), respectively.CD133 expression in CD133-positive cells decreased from (87.2±5.3)% to (60.6±3.1)% (P=0.022) after treatment with DKK-1, whereas the cell apoptosis rate increased from (11.8±0.2)% to (28.3±0.6)% (P=0.013).Conclusions:Wnt activity is higher in CD133-positive DLD1 cells than in CD133-negative DLD1 cells.5-FU can upregulate Wnt activity of CD133-positive colon CSLCs.Blocking Wnt activity may reverse drug sensitivity of CD133-positive cells to 5-FU.

Targeting STAT3 with SH-4-54 suppresses stemness and chemoresistance in cancer stem-like cells derived from colorectal cancer

BACKGROUND Over the years,the numbers of treatment options for colorectal cancer(CRC)have increased,leading to notable improvements in the overall survival of CRC patients.Although therapy may initially yield positive results,the development of drug resistance can result in treatment failure and cancer recurrence.This resistance is often attributed to the presence of cancer stem cells(CSCs).These CSCs not only contribute to therapeutic resistance but also play crucial roles in the initiation and development of tumor metastasis.AIM To investigate the antitumor effects of SH-4-54,which are mediated by targeting CSCs relative to treatment outcomes.METHODS CSCs were enriched by culturing CRC cells in serum-free medium.Hallmarks of stemness and IL-6/JAK2/STAT3 signaling were detected by Western blotting.Indicators of CSC malignancy,including proliferation,invasion,and tumor formation,were measured.RESULTS In this study,we employed SH-4-54,which exhibits anticancer activity in solid tumors through targeting the SH2 domain of both the signal transducer and activator of transcription(STAT)3 and the STAT5,and evaluated its effects on stemness and chemoresistance in colorectal CSCs.As expected,SH-4-54 treatment inhibited the phosphorylation of STAT3(p-STAT3)and decreased the percentage of ALDH1A1-positive CRC cells.The addition of SH-4-54 dissociated colorectal spheroids and decreased the expression of stemness markers,including ALDH1A1,CD44 and Nanog.SH-4-54 treatment decreased IL-6/JAK2/STAT3 signaling by inhibiting p-STAT3 and thus inhibited spheroid formation by SW480 and LoVo cells.Moreover,SH-4-54 treatment inhibited indicators of malignancy,including cell proliferation,invasion,and tumor formation,in CSCs in vitro and in vivo.Notably,SH-4-54 treatment significantly increased chemosensitivity to oxaplatin.CONCLUSION Taken together,these results indicate that SH-4-54 is a promising molecule that exerts antitumor effects on colorectal CSCs by inhibiting STAT3 signaling.

Limonin inhibits the stemness of cancer stem-like cells derived from colorectal carcinoma cells potentially via blocking STAT3 signaling

BACKGROUND Limonin is one of the most abundant active ingredients of Tetradium ruticarpum.It exerts antitumor effects on several kinds of cancer cells.However,whether limonin exerts antitumor effects on colorectal cancer(CRC)cells and cancer stem-like cells(CSCs),a subpopulation responsible for a poor prognosis,is unclear.AIM To evaluate the effects of limonin on CSCs derived from CRC cells.METHODS CSCs were collected by culturing CRC cells in serum-free medium.The cytotoxicity of limonin against CSCs and parental cells(PCs)was determined by cholecystokinin octapeptide-8 assay.The effects of limonin on stemness were detected by measuring stemness hallmarks and sphere formation ability.RESULTS As expected,limonin exerted inhibitory effects on CRC cell behaviors,including cell proliferation,migration,invasion,colony formation and tumor formation in soft agar.A relatively low concentration of limonin decreased the expression stemness hallmarks,including Nanog andβ-catenin,the proportion of aldehyde dehydrogenase 1-positive CSCs,and the sphere formation rate,indicating that limonin inhibits stemness without presenting cytotoxicity.Additionally,limonin treatment inhibited invasion and tumor formation in soft agar and in nude mice.Moreover,limonin treatment significantly inhibited the phosphorylation of STAT3 at Y705 but not S727 and did not affect total STAT3 expression.Inhibition of Nanog andβ-catenin expression and sphere formation by limonin was obviously reversed by pretreatment with 2μmol/L colievlin.CONCLUSION Taken together,these results indicate that limonin is a promising compound that targets CSCs and could be used to combat CRC recurrence and metastasis.

Hallmarks in colorectal cancer:Angiogenesis and cancer stem-like cells

Carcinogenesis is a multistep process that requires the accumulation of various genetic and epigenetic aberrations to drive the progressive malignant transformation of normal human cells.Two major hallmarks of carcinogenesis that have been described are angiogenesis and the stem cell characteristic of limitless replicative potential.These properties have been targeted over the past decade in the development of therapeutic treatments for colorectal cancer(CRC),one of the most commonly diagnosed and lethal cancers worldwide.The treatment of solid tumor cancers such as CRC has been challenging due to the heterogeneity of the tumor itself and the chemoresistance of the malignant cells.Furthermore,the same microenvironment that maintains the pool of intestinal stem cells that contribute to the continuous renewal of the intestinal epithelia also provides the necessary conditions for proliferative growth of cancer stem-like cells.These cancer stem-like cells are responsible for the resistance to therapy and cancer recurrence,though they represent less than 2.5%of the tumor mass.The stromal environment surrounding the tumor cells,referred to as the tumor niche,also supports angiogenesis,which supplies the oxygen and nutrients needed for tumor development.Anti-angiogenic therapy,such as with bevacizumab,a monoclonal antibody against vascular-endothelial growth factor,significantly prolongs the survival of metastatic CRC patients.However,such treatments are not completely curative,and a large proportion of patient tumors retain chemoresistance or show recurrence.This article reviews the current knowledge regarding the molecular phenotype of CRC cancer cells,as well as discusses the mechanisms contributing to their maintenance.Future personalized therapeutic approaches that are based on the interaction of the carcinogenic hallmarks,namely angiogenic and proliferative attributes,could improve survival and decrease adverse effects induced by unnecessary chemotherapy.

Cancer stem-like cells directly participate in vasculogenic mimicry channels in triple-negative breast cancer

Objective: Vasculogenic mimicry(VM) channels that are lined by tumor cells are a functional blood supply in malignant tumors.However, the role of VM-initiating cells remains poorly understood. Cancer stem-like cells(CSCs) are positively correlated with VM. In this study, triple-negative breast cancer(TNBC) enriched with CSCs was used to investigate the relationship between VM and CSCs.Methods: The expression of several CSC markers was detected by immunohistochemistry in 100 human breast cancer samples.The clinical significance of CSC markers and the relationship between VM, CSCs, breast cancer subtypes, and VM-associated proteins were analyzed. CD133+ and ALDH+ human and mouse TNBC cells were isolated by FACS to examine the ability of VM formation and the spatial relationship between VM and CSCs.Results: CSCs were associated with TNBC subtype and VM in human invasive breast cancer. CSCs in TNBC MDA-MB-231 cells formed more VM channels and expressed more molecules promoting VM than the non-TNBC MCF-7 cells in vitro. MDA-MB-231 cells that encircled VM channels on Matrigel expressed CD133. Moreover, CSCs were located near VM channels in the 3D reconstructed blood supply system in human TNBC grafts. The CD133+ and ALDH+ cells isolated from TA2 mouse breast cancer formed more VM channels in vivo.Conclusions: CSCs line VM channels directly. Additionally, CSCs provide more VM-related molecules to synergize VM formation. The signaling pathways that control CSC differentiation may also be potential treatment targets for TNBC.

Sox2 enhances the tumorigenicity and chemoresistance of cancer stem-like cells derived from gastric cancer

Gastric cancer stem-like cells（GCSCs） have been identified to possess the ability of self-renewal and tumor initi-ation.However,the mechanisms involved remain largely unknown.Here,we isolated and characterized the GCSCs by side population（SP） sorting procedure and cultured sphere cells（SC） from human gastric cancer cell lines SGC-7901,BGC-823,MGC-803,HGC-27 and MKN-28.The sorting and culture assay revealed that SP cells proliferated in an asymmetric division manner.In addition,SP cells exhibited a higher potential of spheroid colony formation and greater drug resistance than non-SP cells（NSP）.Moreover,the SC were found with enhanced capabilities of drug resistance in vitro and tumorigenicity in vivo.Sox2 mRNA and protein was highly and significantly overex-pressed in the SP cells and SC.Importantly,downregulation of Sox2 with siRNA obviously reduced spheroid colony formation and doxorubicin efflux,as well as increased apoptosis rate in sphere cells in vitro and suppressed tumori-genicity in vivo.These results suggest that both SP cells and cultured SC enrich with GCSCs and that Sox2 plays a pivotal role in sustaining stem cell properties and might be a potential target for gastric cancer therapy.

Xiaotan Sanjie decoction attenuates tumor angiogenesis by manipulating Notch-1-regulated proliferation of gastric cancer stem-like cells

AIM: To determine the underlying mechanisms of action and influence of Xiaotan Sanjie (XTSJ) decoction on gastric cancer stem-like cells (GCSCs).

Sphere-forming-like cells(squamospheres) with cancer stem-like cell traits from VX2 rabbit buccal squamous cell carcinoma

Previous studies have demonstrated that spheroid type cells grown under suspension culture conditions have cancer stem cell（CSC） traits in a number of cancers, but this phenomenon has not yet been reported in the VX2 rabbit oral cancer model. Hence, this study aimed to study the spheroid cells from VX2 rabbit buccal squamous cell carcinomas（SCCs） and assess their CSC characteristics. Five adult male New Zealand white outbred rabbits were used to generate VX2 rabbit buccal SCC. Sphere-forming cell culture was performed for the VX2 rabbit buccal SCC specimens. The self-renewal capability; cluster of designation（CD） 44, CD133, acetaldehyde dehydrogenase 1（ALDH1）, B cell-specific Moloney murine leukemia virus integration site 1（Bmi-1）, Nestin, octamer-binding transcription factor 4（Oct4）and reduced expression protein-1（Rex-1） expression with reverse transcription-polymerase chain reaction（RT-PCR）; chemoresistance to cisplatin and 5-fluorouracil; and in vivo tumorigenicity of spheroid cell transplantation in nude mice were evaluated to determine the CSC characteristics of the resulting spheroid cells. We successfully obtained spheroid cells from the VX2 rabbit OSCC tissues. The spheroid cells exhibited CSC traits, including the expression of CSC and stem cell markers（CD44, Bmi-1, Nestin, Oct4 and Rex-1）, capacity to generate new spheroid colonies within 1 week of reseeding from single-dissociated spheroid cells, chemoresistance capacity and generation of tumour xenografts（with histological features resembling those of the original VX2 rabbit buccal SCC） from the transplantation of 103 undifferentiated spheroid cells into nude mice. In summary, we demonstrated that spheroid cells with CSC cell traits can be derived from VX2 rabbit buccal SCCs, indicating that this animal cancer model is applicable for studying CSCs in human oral cancers.

Brain tumors:Cancer stem-like cells interact with tumor microenvironment

Cancer stem-like cells(CSCs)with potential of self-renewal drive tumorigenesis.Brain tumor microenvironment(TME)has been identified as a critical regulator of malignancy progression.Many researchers are searching new ways to characterize tumors with the goal of predicting how they respond to treatment.Here,we describe the striking parallels between normal stem cells and CSCs.We review the microenvironmental aspects of brain tumors,in particular composition and vital roles of immune cells infiltrating glioma and medulloblastoma.By highlighting that CSCs cooperate with TME via various cellular communication approaches,we discuss the recent advances in therapeutic strategies targeting the components of TME.Identification of the complex and interconnected factors can facilitate the development of promising treatments for these deadly malignancies.

Inhibition of self-renewal and differentiation of HT-29 cells-derived cancer stem-like cells by scutellarin via Hedgehog signaling pathway

OBJECTIVE To investigate the inhibitory effect of scutellarin on the self-renewal and differentiation of HT-29 cells-derived cancer stem-like cells(HT-29CSC)in vitro and in vivo,and to explore its mechanism.METHODS The effect of scutellarin on the growth of HT-29CSC was determined by 3D Culture assay.The effect of scutellarin on growth and transformation of HT-29CSC was probed by soft agar colony formation assay.The effect of scutellarin on the differentiation of HT-29CSC was determined by serum induction differentiation assay in vitro.The effects of scutellarin on the expressions of marker gene Lgr5,target gene c-Myc,proliferation gene CK20 and Nanog gene were measured by quantitative real-time RT-PCR.Investigate the effect of scutellarin on the expression of c-Myc,Gli1,and Lgr5 protein by Western blotting.A subcutaneous xenograft model of colon cancer in nude mice was established and administered by intraperitoneal injection.The change of body weight and tumor size of nude mice were observed every two days.Investi⁃gate the effects of scutellarin on the growth of xenograft tumors in nude mice.The expression of CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki67,CK20,Nanog gene in tumors were measured by quantitative real-time RT-PCR.The expression of c-Myc,Gli1,Lgr5,CD133,Ki67 protein were measured by Western blotting.RESULTS Scutellarin can inhibit the growth of HT-29CSC in 3D culture.Compared with the solvent control group,scutellarin can significantly inhibit the growth and transformation and differentiation of HT-29CSC in vitro(P<0.01).The expression levels of marker genes Lgr5,target gene c-Myc,proliferation gene CK20 and Nanog in HT-29CSC were down-regulated by scutellarin.Scutellarin can reduce the expression of c-Myc,Gli1,and Lgr5 protein in HT-29CSC.Scutellarin can inhibit the growth of colon cancer xenografts,lower CD133,Lgr5,Gli1,Ptch1,c-Myc,Ki67,CK20,and Nanog mRNA level of xenograft tumors,reduce the expression of c-Myc,Gli1,Lgr5,CD133,and Ki67 protein of xenograft tumors in nude mice.CONCLUSION Scutellarin,which is the main component of scutellaria barbata,can inhibit the differentiation of HT-29CSC and the mechanism is to inhibit the activity of Hedgehog signaling pathway.

Effect of soy saponin on the growth of human colon cancer cells

AIM:To investigate the effect of extracted soybean saponins on the growth of human colon cancer cells.METHODS:WiDr human colon cancer cells were treated with 150,300,600 or 1200 ppm of soy saponin to determine the effect on cell growth,cell morphology,alkaline phosphatase(AP) and protein kinase C(PKC) activities,and P53 protein,c-Fos and c-Jun gene expression.RESULTS:Soy saponin decreased the number of viable cells in a dose-dependent manner and suppressed 12-Otetradecanol-phorbol-13-acetate-stimulated PKC activity(P < 0.05).Cells treated with saponins developed cytoplasmic vesicles and the cell membrane became rougher and more irregular in a dose-dependent manner,and eventually disassembled.At 600 and 1200 ppm,the activity of AP was increased(P < 0.05).However,the apoptosis markers such as c-Jun and c-Fos were not significantly affected by saponin.CONCLUSION:Soy saponin may be effective in preventing colon cancer by affecting cell morphology,cell proliferation enzymes,and cell growth.

An effective vaccine against colon cancer in mice:Use of recombinant adenovirus interleukin-12 transduced dendritic cells

AIM： To investigate the effect of a vaccine with recombinant adenovirus interleukin-12 （AdVIL-12） transduced dendritic cells （DCs） against colon cancer in mice. METHODS： DCs and AdVIL-12 were incubated together at different time intervals and at different doses. Supernatant was collected and tested for IL-12 by enzyme-linked immunosorbent assay （ELISA）. In order to determine whether tumor cell lysate-pulsed （TP） AdVIL-12/DCs enhance therapeutic potential in the established tumor model, CT26 colon tumor cells were implanted subcutaneously （s.c.） in the midflank of naive BALB/c mice. Tumor-bearing mice were injected with a vaccination of CT26 TP AdVIL-12/DCs on d 3 and 10. As a protective colon tumor model, naive BALB/c mice were immunized s.c. in their abdomens with CT26 TP AdVIL-12/DCs twice at seven day intervals. After the immunization on d 7, the mice were challenged with a lethal dose of CT26 tumor cells and survival times were evaluated. Subsequently, cytotoxic T lymphocyte （CTL） activity and interferon gamma （IFNy） secretion was evaluated in the immunized mice, and assayed CTL ex vivo. RESULTS： Murine DCs were retrovirally transduced with AdVIL-12 efficiency, and the AdVIL-12 transduced DCs secreted a high level of IL-12 （AdVIL-12/DCs, 615.27 ± 42.3 pg/mL vs DCs, 46.32 ± 7.29 pg/mL, P 〈 0.05）. Vaccination with CT26 TP AdVIL-12/DCs could enhance anti-tumor immunity against CT26 colon tumor in murine therapeutic models （tumor volume on d 19：CT26 TP AdVIL-12/DCs 107 ± 42 mm^3 vs CT26 TP DCs 383± 65 mm^3, P 〈 0.05） and protective models. Moreover, the CT26 TP AdVIL-12/DC vaccination enhances tumor-specific CTL activity, producing high levels of IFN7 in immunized mice. Ex vivo primed T cells with AdVIL-12/DCs were able to induce more effective CTL activity than in primed T cells with CT26 TP/DCs （E：T = 100：1, 69.49% ± 6.11% specific lysis vs 37.44% ＋ 4.32% specific lysis, P 〈 0.05）.CONCLUSION： Vaccination with recombinant AdVIL-12 transduced DC pulsed tumor cell lysate enhance antitumor immunity specific to colon cancer in mice.

miR-93 suppresses proliferation and colony formation of human colon cancer stem cells

AIM： TO identify differentially expressed microRNAs （miRNAs） in human colon cancer stem cells （SW1116csc） and study their function in SW1116csc proliferation. METHODS： SW1116csc were isolated from the human colon cancer cell line, SW1116 and cultured in serum- free medium. A miRNA microarray was used to detect differential expression profiles of rniRNAs in SW1116csc and SW1116 cells. Real-time quantitative polymerase chain reaction （PCR） was performed to verify the dif- ferential expression of candidate miRNAs obtained from the microarray. Target mRNAs of differentially expressed miRNAs were predicted with target predic- tion tools, miRNA expression plasmids were transfected into SW1116csc using Lipofectamine 2000 reagent. Cell proliferation curves were generated with trypan blue staining, and the colony formation rate of transfected cells was measured with the soft agar colony formation assay. Expression of target mRNAs and proteins from differentially expressed miRNAs were detected using reverse transcription （RT）-PCR and western blotting.RESULTS： Compared with expression in SW1116 cells, 35 miRNAs （including hsa-miR-192, hsa-miR-29b, hsa-miR-215, hsa-miR-194, hsa-miR-33a and hsa- miR-32） were upregulated more than 1.5-fold, and 11 miRNAs （including hsa-miR-93, hsa-miR-1231, hsa- miRPlus-F1080, hsa-miR-524-3p, hsa-miR-886-3p and hsa-miR-561） were downregulated in SW1116csc. The miRNA microarray results were further validated with quantitative RT-PCR. miR-93 was downregulated, and its predicted mRNA targets included BAMBI, CCND2, CDKNIA, HDACS, KIF23, MAP3K9, MAP3K11, MYCN, PPARD, TLE4 and ZDHHCl. Overexpressed miR-93 sig- nificantly inhibited cell proliferation and colony forma- tion by SW1116csc. Furthermore, miR-93 negatively regulated the mRNA and protein levels of HDAC8 and TLE4. CONCLUSION： Some miRNAs were differentially ex- pressed during differentiation of SW1116csc into SW1116 cells, miR-93 may inhibit SW1116csc proliferation and colony formation.

Colon cancer stem cells:Controversies and perspectives

Tumors have long been viewed as a population in which all cells have the equal propensity to form new tumors,the so called conventional stochastic model.The cutting-edge theory on tumor origin and progression,tends to consider cancer as a stem cell disease.Stem cells are actively involved in the onset and maintenance of colon cancer.This review is intended to examine the state of the art on colon cancer stem cells(CSCs),with regard to the recent achievements of basic research and to the corresponding translational consequences.Specific prominence is given to the hypothesized origin of CSCs and to the methods for their identification.The growing understanding of CSC biology is driving the optimization of novel anti-cancer targeted drugs.

Therapeutic implications of colon cancer stem cells

Colorectal cancer is the second most common cause of cancer-related death in many industrialized countries and is characterized by a heterogenic pool of cells with distinct differentiation patterns. Recently, the concept that cancer might arise from a rare population of cells with stem cell-like properties has received support with regard to several solid tumors, including colorectal cancer. According to the cancer stem cell hypothesis, cancer can be considered a disease in which mutations either convert normal stem cells into aberrant counterparts or cause a more differentiated cell to revert toward a stem cell-like behaviour; either way these cells are thought to be responsible for tumor generation and propagation. The statement that only a subset of cells drives tumor formation has major implications for the development of new targeted therapeutic strategies aimed at eradicating the tumor stem cell population. This review will focus on the biology of normal and malignant colonic stem cells, which might contribute to our understanding of the mechanisms responsible for tumor development and resistance to therapy.

Proteome of human colon cancer stem cells:A comparative analysis

AIM： To isolate and identify the biological characteristics of human colon cancer stem cells （SW1116 cells） and further study their proteome. METHODS： SW1116 cells were isolated and cultured with a serum-free medium （SFM）. Sphere formation was assayed to observe the formation of colon cancer stem cell spheres. SW1116 cells were inoculated into a serum-containing medium for observing their differentiation characteristics. Proliferation curve and cross-resistance of SWl116 cells to different drugs were detected by MTT. Percentage of SP cells in SW1116 cells was detected with Hoechst33342 staining. Telomerase activity in SW1116cells was checked by polymerase chain reaction （PCR）-enzyme linked immunosorbent assay. Expressions of stem cell relevant genes and proteins were detected by reverse transcription-PCR and Western blot, respectively. Total protein was isolated from SW1116 cells by two-dimensional gel electrophoresis （2-DE） and differentially expressed proteins were identified by tandem mass spectrometry （MALDI-TOF/TOF）. RESULTS： The isolated SW1116 cells presented as spheroid and suspension growths in SFM with a strong self-renewal, proliferation, differentiation and drug-resistance ability. The percentage of SP cells in SW1116 cells was 38.9%. The SW1116 cells co-expressed the CD133 and CD29 proteins. The telomerase activity in SW1116 cells was increased. The expressions of different stem cell relevant genes and proteins were detected. The proteomic analysis showed that the 26 protein spots were differently expressed in SW1116 cells and 10 protein spots were identified as ubiquitin fusion- degradation l-like protein, nuclear chloride channel protein, tubulin 13, Raichu404X, stratifin, F-actin cap- ping protein α-1 subunit, eukaryotic translation elongation factor 1 delta isoform 2, hypothetical protein, glyceraldehyde-3-phosphate dehydrogenase and guanine nucleotide binding protein 13 polypeptide 2-like 1, respectively. CONCLUSION： SW1116 cells are biologically characterized by self-renewal, proliferation and differentiation, and the differently expressed proteins in SW1116 cells may be essential for isolating cancer stem cells.

Upregulated CD133 expression in tumorigenesis of colon cancer cells

AIM: To analyze the upregulated CD133 expression in tumorigenesis of primary colon cancer cells. METHODS: Upregulated CD133 expression in tumorigenesis of colorectal cancer cell lines (Lovo, Colo205, Caco-2, HCT116 and SW620) was analyzed by flow cytometry. Human colon cancer tissue samples were stained with anti-human CD133. SW620 cells were sorted according to the CD133 expression level measured by fluorescence-activated cell sorting. Spheroids of colorectal cancer cells were cultured with the hanging drop. Expression of CD133 and Lgr5 in spheroids of colorectal cancer cells and monolayer culture was detected by RT-qPCR. Spheroids of colorectal cancer cells were analyzed using anti-human CD133 with immunohistochemical staining. RESULTS: CD133 antigen was expressed in colorectal cancer cell lines (Lovo, Colo205, Caco-2, HCT116 and SW620) as well as in primary and metastatic human colon cancer tissues. However, the CD133 was differently expressed in these cell lines and tissues. The expression levels of CD133 and Lgr5 were significantly higher in spheroids of parental, CD133hi and CD133-cells than in their monolayer culture at the mRNA level (P < 0.05). Immunohistochemical staining of spheroids of CD133-cells showed that CD133 was highly expressed in colorectal cancer cell lines. CONCLUSION: Upregulated CD133 expression plays a role in tumorigenesis colorectal cancer cells, which may promote the expression of other critical genes that can drive tumorigenesis.

Interaction of 14-3-3σ with KCMF1 suppresses the proliferation and colony formation of human colon cancer stem cells

AIM: To investigate the biological function of 14-3-3σ protein and to look for proteins that interact with 14-3-3σ protein in colon cancer stem cells. METHODS: Reverse transcription polymerase chain reaction was performed to amplify the 14-3-3σ gene from the mRNA of colon cancer stem cells. The gene was then cloned into the pGEM-T vector. After being sequenced, the target gene 14-3-3σ was cut from the pGEM-T vector and cloned into the pGBKT7 yeast expression plasmid. Then, the bait plasmid pGBKT7-14-3-3σ was transformed into the yeast strain AH109. After the expression of the pGBKT7-14-3-3σ fusion protein in the AH109 yeast strain was accomplished, a yeast two-hybrid screening assay was performed by mating AH109 with Y187 that contained a HeLa cDNA library plasmid. The interaction between the 14-3-3σ protein and the proteins obtained from positive colonies was further confirmed by repeating the yeast two-hybridscreen. After extracting and sequencing the plasmids from the positive colonies, we performed a bioinformatics analysis. A coimmunoprecipitation assay was performed to confirm the interaction between 14-3-3σ and the proteins obtained from the positive colonies. Finally, we constructed 14-3-3σ and potassium channel modulatory factor 1 (KCMF1) siRNA expression plasmids and transfected them into colon cancer stem cells. RESULTS: The bait plasmid pGBKT7-14-3-3σ was constructed successfully, and the 14-3-3σ protein had no toxic or autonomous activation effect on the yeast. Nineteen true-positive colonies were selected and sequenced, and their full-length sequences were obtained. We searched for homologous DNA sequences for these sequences from GenBank. Among the positive colonies, four coding genes with known functions were obtained, including KCMF1 , quinone oxidore-ductase (NQO2 ), hydroxyisobutyrate dehydrogenase (HIBADH ) and 14-3-3σ . For the subsequent coimmu-noprecipitation assay, the plasmids PCDEF-Flag-14-3-3σ, PCDEF-Myc-KCMF1, PCDEF-Myc-NQO2 and PCDEF-Myc-HIBADH were successfully constructed, and the sequences were further confirmed by DNA sequencing. The Fugene 6 reagent was used to transfect the plasmids, and fluorescence-activated cell sorting analysis showed the transfection efficiency was 97.8% after 48 h. The HEK 293FT cells showed the stable expression of the PCDEF-Flag-14-3-3σ, PCDEF-Myc-KCMF1, PCDEF-Myc-NQO2 and PCDEF-Myc-HIBADH plasmids. After anti-Myc antibody immunoprecipitation with Myc-KCMF1, Myc-NQO2 and Myc-HIBADH from cell lysates, the presence of Flag-14-3-3σ protein in the immuno-precipitated complex was determined by western blot analysis. The knock-down expression of the 14-3-3σ and KCMF1 proteins significantly inhibited cell proliferation and colony formation of SW1116csc. CONCLUSION: Genes of the proteins that interactedwith 14-3-3σ were successfully screened from a HeLa cDNA library. KCMF1 and 14-3-3σ protein may affect the proliferation and colony formation of human colon cancer stem cells.

Impact of 5-Fu/oxaliplatin on mouse dendritic cells and synergetic effect with a colon cancer vaccine

Objective： The aim of the present study was to investigate the effects of 5-fluorouracil（5-Fu） and oxaliplatin on the function and activation pathways of mouse dendritic cells（DCs）, and to clarify whether 5-Fu/oxaliplatin combined with the CD1d-MC38/α-galactosylceramide（α-GC） tumor vaccine exhibits synergistic effects on the treatment of colon cancer in mice.Methods： The combination of the Toll like receptor（TLR） ligands and/or 5-Fu/oxaliplatin was added into myeloid-derived DCs in vitro culture. DC phenotypic changes were detected by flow cytometry, and the secretion of DC cytokines was detected by cytometric bead array（CBA）. A MC38 mouse colon cancer model was constructed and the DCs were isolated from the spleen, tumor tissue and lymph nodes following intraperitoneal injection of 5-Fu/oxaliplatin. The cell phenotypes were detected by flow cytometry. The tumor infiltrating leukocytes,splenocytes and lymph node cells were co-cultured with the dead MC38 tumor cells, and the secretion levels of interferon-γ（IFN-γ） were detected. 5-Fu/oxaliplatin combined with our previously developed CD1d-MC38/α-GC tumor vaccine was used to inhibit the growth of MC38 colon cancer in mice, and the tumor growth rate and survival time were recorded.Results： 5-Fu/oxaliplatin exerted no significant effect on the expression of the stimulating phenotypes of DCs in vitro, while it could reduce the expression of programmed death ligand 1/2（PD-L1/L2） and promote interleukin-12（IL-12） secretion by DCs. Furthermore 5-Fu/oxaliplatin was beneficial to the differentiation of T-helper 1（Th1） cells. 5-Fu/oxaliplatin further enhanced the stimulating phenotypic expression of DCs in tumor bearing mice, decreased PD-L1/L2 expression, and specifically activated the lymphocytes. The CD1d-MC38/α-GC tumor vaccine combined with 5-Fu/oxaliplatin could exert a synergistic role that resulted in a significant delay of the tumor growth rate, and an increase in the survival time of tumor bearing mice.Conclusions： 5-Fu/oxaliplatin decreased the expression of the DC inhibitory phenotypes PD-L1/L2, promoted DC phenotypic maturation in tumor bearing mice, activated the lymphocytes of tumor bearing mice, and exerted synergistic effects with the CD1d-MC38/α-GC colon cancer tumor vaccine.

Modulators affecting the immune dialogue between human immune and colon cancer cells

The link between chronic inflammation and colorectal cancer has been well established. The events proceeding along tumorigenesis are complicated and involve cells activated at the cancer microenvironment, tumor infiltrating polymorphonuclears, immune cells including lymphocyte subtypes and peripheral blood mononuclear cells(PBMC), as well as tumor-associated macrophages. The immune cells generate inflammatory cytokines, several of them playing a crucial role in tumorigenesis. Additional factors, such as gene expression regulated by cytokines, assembling of tumor growth- and transforming factors, accelerated angiogenesis, delayed apoptosis, contribute all to initiation, development and migration of tumor cells. Oxygen radical species originating from the inflammatory area promote cell mutation and cancer proliferation. Tumor cells may over-express pro-inflammatory mediators that in turn activate immune cells for inflammatory cytokines production. Consequently, an immune dialogue emerges between immune and cancer cells orchestrated through a number of activated molecular pathways. Cytokines, encompassing migration inhibitory factor, transforming growth factor beta 1, tumor necrosisfactor-α, Interleukin(IL)-6, IL-10, IL-12, IL-17, IL-23 have been reported to be involved in human cancer development. Some cytokines, namely IL-5, IL-6, IL-10, IL-22 and growth factors promote tumor development and metastasis, and inhibit apoptosis via activation of signal transducer activator transcription-3 transcription factor. Colon cancer environment comprises mesenchymal, endothelial and immune cells. Assessment of the interaction between components in the tumor environment and malignant cells requires a reconsideration of a few topics elucidating the role of chronic inflammation in carcinogenesis, the function of the immune cells expressed by inflammatory cytokine production, the immunomodulation of cancer cells and the existence of a cross-talk between immune and malignant cells leading to a balance in cytokine production. It is conceivable that the prevalence of anti-inflammatory cytokine production by PBMC in the affected colonic mucosa will contribute to the delay, or even to halt down malignant expansion. Targeting the interplay between immune and cancer cells by mediators capable to alter cytokine secretion toward increased anti-inflammatory cytokine release by PBMC and tumor associated macrophages, may serve as an additional strategy for treatment of malignant diseases. This review will focus on the inflammatory events preceding tumorigenesis in general, and on a number of modulators capable to affect colon cancer cell-induced production of inflammatory cytokines by PBMC through alteration of the immune crosstalk between PBMC and cancer cells.