Colon Cancer Cell Line CT26 Research Articles

Synthesis and characterization of magnetic nanoparticle-embedded multi-functional polymeric micelles for MRI-guided gene delivery

Superparamagnetic iron oxide nanoparticle (SPION)-based diagnostic properties with accompanying therapeutics such as drugs or genes have been explored for improvement of their therapeutic efficacy. Positively charged SPION-loaded polymersomes was prepared to deliver genes to the target sites; this process was concomitantly monitored by magnetic resonance imaging (MRI). The surface characteristics and morphology were respectively measured by dynamic light scattering and transmission electron microscopy. The complex between the polymer and the pDNA was confirmed by a gel retardation assay. The transfection efficiency and cytotoxicity in vitro were tested by treating of the CT-26 colon cancer cell line with luciferase-expressing plasmids/SPION complex. MRI was also used to check the detectability of SPION in vitro and in vivo. A SPION-loaded polymersome carrying genetic materials was delivered and then accumulated in the tumor site of the murine colon cancer xenograft model after intravenous injection, possibly through a passive targeting mechanism. The accumulation was monitored using clinical MRI. This result indicates that the SPION-loaded polymersome can be applied to MR imageguided gene therapy. Open image in new window

Haematoporphyrin Based Photodynamic Therapy Combined with Hyperthermia Provided Effective Therapeutic Vaccine Effect against Colon Cancer Growth in Mice

Photodynamic therapy (PDT) has become an attractive option used in tumor treatment via its direct tumoricidal activities or its immune-boosting activities. On the other hand, heat shock protein 70 has been found to be largely associated with the establishment of anti-tumor activities offered by hyperthermia treated tumor cells. In the present study, we found that injection of tumor-bearing mice with colon cancer cell line CT-26 treated with haematoporphyrin based photodynamic therapy (hematoporphyrin monomethyl ether based PDT, HMME-PDT) together with hyperthermia demonstrated the most effective therapeutic effects against tumor growth, followed by cells treated by hyperthermia alone. CT-26 cells treated only with HMME-PDT failed to provide any therapeutic effects, although significant cell death was induced by HMME-PDT. Compared to hyperthermia treatment, HMME-PDT induced more efficient surface localization of HSP70 on CT-26 cells which correlated with efficient activation of cytolytic CD8 T cells and with effective anti-tumor responses. Thus, our study demonstrated that the surface expression of HSP70 may play a more important role than the total expression or release of this molecule in the activation of immune responses. And our study offered a novel modified PDT approach to the treatment of tumor cells intrinsically low on HSP70 expression.

Tumor-Associated Antigen Expressing Listeria monocytogenes Induces Effective Primary and Memory T-Cell Responses Against Hepatic Colorectal Cancer Metastases

PurposeDespite advances in therapy for the treatment of metastatic colorectal cancer, many patients die of hepatic disease. Current immunotherapeutic strategies are likely limited by inhibitory signals from the tumor. To successfully eliminate tumor deposits within an organ, an appropriate immunologic milieu to amplify antitumor responses must be developed.MethodsWe used a murine model utilizing the CT26 colon cancer cell line to analyze primary and memory tumor-specific T-cell responses induced by an attenuated actin A and internalin B deleted immunodominant tumor-associated antigen expressing strain of Listeria monocytogenes for the treatment of metastatic colorectal cancer.ResultsTreatment of mice bearing established hepatic metastases with this L. monocytogenes strain led to the generation of a strong initial tumor-specific cytotoxic CD8+ T-cell response that successfully treated 90% of animals. Tumor antigen-specific central and effector memory T cells were also generated and protected against tumor rechallenge. These cell populations, when measured before and after tumor rechallenge, showed a marked expansion of antigen-specific effector CD8+ effector memory T cells. This strain of L. monocytogenes was able to down-modulate the expression of the immune checkpoint molecule, PD-1, within the tumor microenvironment but had variable effects on CTLA-4 expression.ConclusionsThis L. monocytogenes strain generated a highly effective antitumor T-cell response, providing a basis for the development of this vaccine platform in patients with liver metastases.Electronic supplementary materialThe online version of this article (doi:10.1245/s10434-011-2037-0) contains supplementary material, which is available to authorized users.

Superparamagnetic Iron Oxide Nanoparticles-Loaded Polymersome-Mediated Gene Delivery Guided by Enhanced Magnetic Resonance Signal

Positively charged superparamagnetic iron oxide nanoparticle (SPION)-loaded polymersome was prepared in order to deliver genes to the target sites, which was monitored by magnetic resonance imaging (MRI), concomitantly. The transfection efficiency in vitro was tested by treating CT-26 colon cancer cell line with luciferase-expressing plasmids/SPION complex. MRI was also used to check the detectability of SPION in vitro and in vivo. SPION-loaded polymersome, carrying genetic materials, was delivered and then accumulated at the tumor site of the murine colon cancer xenograft model after intravenous injection, possibly through a passive targeting mechanism. Clinical MRI monitored this accumulation. This result indicates that the SPION-loaded polymersomecan be applied to MR image-guided gene therapy.

Development and verification of CEA positive CT26 colon cancer cell line

To establish a colon cancer cell line with stable expression of carcinoembryonic antigen(CEA). Recombinant lentivirus conjugated with CEACAM5 cDNA were used to transfect wild CT26 cells. Antibiotics were given for 2 weeks to select CEA positive cells. A single transfected clone was obtained using limiting dilution. The 7th and 14th passages of cells cultured in vitro were detected for CEACAM5 mRNA by RT-PCR, and protein by western blot. The location of CEACAM5 expression was examined using fluorescent microscope and immunocytochemistry. The 14th passage cells were injected subcutaneously into mice to create BALB/c model and CEACAM5 protein was detected by in vivo fluorescence image analysis system and immunohistochemistry. CEACAM5 mRNA and protein were found in the 7th and 14th passages of CT26CEA cells, which were proved to locate in the cytoplasm by fluorescence microscope and immunohistochemistry. Abundant CEACAM5 protein was found in subcutaneous tumors by in vivo fluorescence image analysis system and immunohistochemistry. Colon cancer cell line CT26 with stable expression of CEA in vitro and in mice can be used as a suitable tool to facilitate research on the impact and mechanism of CEA on colon cancer under normal immune environment.

W1950 A Combined Oral Regimen of EGCG and Silibinin Inhibited the Subcutaneous Growth of the CT-26 Colon Cancer Cell Line and Had NO Adverse Effect on Abdominal or Gastric Wound Healing

W1950 A Combined Oral Regimen of EGCG and Silibinin Inhibited the Subcutaneous Growth of the CT-26 Colon Cancer Cell Line and Had NO Adverse Effect on Abdominal or Gastric Wound Healing

Abstract 2935: Modulation of immune checkpoint B7-H1/B7-DC/PD-1 interaction in combination with live attenuated Listeria monocytogenes expressing a tumor associated antigen effectively treats hepatic colorectal cancer metastases

Abstract Introduction: The successful eradication of tumor deposits by immunotherapy requires the generation of an appropriate primary and memory immune effector immune response as well as the establishment of a tumor micro-environment within that organ to target, traffic and amplify the appropriate immune response. B7-H1 is expressed on dendritic cells (DCs), macrophages, T/B cells and on various cancer cell lines. B7-H1 when bound to its T-cell receptor, programmed death-1 (PD-1) induces a negative regulatory signal inhibiting T cell responses. These are particularly attractive targets of therapy in metastatic colorectal cancer as the cancer and the liver microenvironment express B7H1, while tumor infiltrating CD8+ T cells express PD-1. It appears that cancer is able to exploit the B7H1-PD-1 inhibitory mechanism thus making the blockade of this interaction capable of enhancing our already validated vaccine platform of doubly attenuated Listeria Monocytogenes (LM). Methods and Results: Isolated hepatic metastases were generated in Balb/c mice and treated with intraperitoneal injections of 0.1 x LD50 of LM on postoperative days 3, 6, 9. In addition, intravenous injection of a mouse anti-mouse B7-H1 blocking antibody was given on days 4,7,10 and compared to mice given vaccine alone, antibody alone, and no treatment. We analyzed immune cell populations in the liver with flow cytometry to define the activity, specificity and kinetics. After blockade of B7-H1 we performed survival analysis and in vitro studies for T cell proliferation of activated T cells. Results: Mice treated with LM and B7-H1 showed a 60% survival, LM alone showed 30% survival, while antibody alone and untreated mice did not survive (Figure 1). We first demonstrated B7-H1 expression on colon cancer cell line CT26. We then found CD8+ T cells and conventional dendritic cells (cDC) treated with LM, showed an up-regulation of B7-H1. However, these receptors upregulation were both abgrogated when combined with B7H1 blocking antibody. When B7H1 blocking antibody was used alone, there was a decrease in B7H1 expression but an increased expression on PD-1 on CD8+ T cells. T cell proliferation assay in vitro showed sustained T cell activity with B7-H1 blockade even in the presence of tumor. Conclusion Blockade of B7-H1 is an effective method of overcoming immune evasion and improves the efficacy of LM vaccine in the treatment of metastatic colorectal cancer to the liver. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2935.

Chloroquine Inhibits Colon Cancer Cell Growth In Vitro and Tumor Growth In Vivo via Induction of Apoptosis

The present study was to investigate the anticancer effect of chloroquine on proliferation of mouse colon cancer cell line CT26 in vivo and in vitro and the possible mechanism. We found that chloroquine inhibited CT26 proliferation by concentration- and time-dependent manner. This effect was associated with apoptosis induction and decreased level of phosphorylated p42/44 mitogen-activated protein kinase and phosphorylated Akt. The in vivo study showed chloroquine-reduced tumor volume and prolonged survival time in CT26-bearing mice. These observations indicated chloroquine could inhibit CT26 proliferation by inducing apoptosis both in vitro and in vivo, providing its chemotherapeutic potential of human cancers.

Active chinese mistletoe lectin-55 enhances colon cancer surveillance through regulating innate and adaptive immune responses

To investigate the potential role of active Chinese mistletoe lectin-55 (ACML-55) in tumor immune surveillance. In this study, an experimental model was established by hypodermic inoculating the colon cancer cell line CT26 (5 x 10(5) cells) into BALB/c mice. The experimental treatment was orally administered with ACML-55 or PBS, followed by the inoculation of colon cancer cell line CT26. Intracellular cytokine staining was used to detect IFN-gamma production by tumor antigen specific CD8+ T cells. FACS analysis was employed to profile composition and activation of CD4+, CD8+, gammadelta T and NK cells. Our results showed, compared to PBS treated mice, ACML-55 treatment significantly delayed colon cancer development in colon cancer-bearing Balb/c mice in vivo. Treatment with ACML-55 enhanced both Ag specific activation and proliferation of CD4+ and CD8+ T cells, and increased the number of tumor Ag specific CD8+ T cells. It was more important to increase the frequency of tumor Ag specific IFN-gamma producing-CD8+ T cells. Interestingly, ACML-55 treatment also showed increased cell number of NK, and gammadeltaT cells, indicating the role of ACML-55 in activation of innate lymphocytes. Our results demonstrate that ACML-55 therapy can enhance function in immune surveillance in colon cancer-bearing mice through regulating both innate and adaptive immune responses.

Antibacterial activity and in vitro anti-tumor activity of the extract of the larvae of the housefly ( Musca domestica)

One of the significant characteristics of traditional Chinese medicine is the use of insects, other terrestrial arthropods and their products as drugs. In the present work, the extract of housefly ( Musca domestica) larvae was studied by an agar well diffusion assay and minimum bactericidal concentration (MBC) determination for detection of antimicrobial activity and by MTT assay method to test its in vitro anti-tumor activity. In our studies, the extract inhibited six tested bacterial pathogens and Escherichia coli Jm109, a gene-modified strain resistant to ampicillin with the MBCs ranging from 200 to 1600 μg/ml, while Gram-positive bacteria were more sensitive than Gram-negative bacteria. The extract showed high in vitro anti-tumor activity against human colon cancer cell line CT26 with the IRs ranging from 62 to 89%. The extract of housefly larvae inoculated with Shigella dysenteriae 51302 exhibited higher antibacterial activity and in vitro anti-tumor activity than that of native larvae, which may indicate the same principle involved in the use of Bombyx mori larvae infected with silk moth fungus Beauveria bassiana and Hepialis larvae infected with Cordiceps fungus in the traditional Chinese medicine. Both extracts did not show any coagulation activity and haemolysis activity against rabbit erythrocytes at 500 and 1000 μg/ml. The results support its use in the traditional Chinese medicine, and warrant the further identification of the active molecule in the housefly larvae.

B cell response to tumor antigens is associated with depletion of B progenitors in murine colocarcinoma

Background B cells that produce antibodies to autologous tumor antigens have been found in patients with colon cancer; the significance of this phenomenon remains unknown. Normally, the elimination of autoreactive B cells occurs in the bone marrow during their maturation. We studied the production of antibodies to syngeneic tumor antigens and the maturation of bone marrow B cells in experimental colocarcinoma model. Methods BALB/c mice and syngeneic CT26 colon cancer cell line were used. Reactivity of serum antibodies was tested in Western blot analysis and flow cytometry against CT26 antigens. The number of bone marrow B lineage cells was evaluated with specific antibodies and flow cytometry analysis. Results A significant decrease in the number of B cell precursors occurred in tumor-bearing mice; it normalized 3 weeks after the removal of CT26 tumors. The number of mature B cells was normal. Serum antibodies from tumor-bearing mice recognized intracellular and not surface antigens of CT26 cells. Conclusion Experimental colon cancer induces B cell response to intracellular, but not surface, tumor cell antigens and restricts the B cell repertoire by depleting their precursors.

Possible effect of pneumoperitoneum on the spreading of colon cancer tumor cells.

By using a murine hepatic metastatic model, we tried to investigate the possible influence of gas insufflation in colon cancer cells spreading from the portal system to the liver. After transducing the human placental ALP gene into murine colon cancer cell line CT26, we successfully selected a clone of CT26/DAP that would yield a specific color following histochemical staining. Fifty mice were assigned into two groups, receiving either an intrasplenic injection of 10(6) CT26/DAP cells alone or the cells followed by intra-abdominal helium insufflation with the pressure of 15 cm H2O for ten minutes. Five mice in each group were used to observe their survival and the other mice were killed at four different time periods: 10 minutes, 24 hours, 48 hours, and 72 hours following cell injection. The livers and spleens were removed for histochemical staining. By counting the numbers of specific dark reddish spots of CT26/DAP cells, we could estimate the number of tumor cells on the hepatic surface. At the very beginning following tumor cell injection, we found a significantly greater number of tumor cells on the hepatic surface in mice with gas insufflation (6354 +/- 1072 vs. 2133 +/- 223, respectively; P = 0.012). But the difference of these two groups became smaller and smaller as time went by. The number of tumor cells on the hepatic surface would reach the lowest level at postoperative 48 hours, and the tumor foci then began to grow both in size and number. The above patterns of dynamic change in tumor cell distribution were similar in mice both with and without gas insufflation. Average survival was slightly shorter in mice with gas insufflation, but the difference was not statistically significant. Pneumoperitoneum caused by gas insufflation may increase tumor cell spread from the portal system to the liver at the very beginning stage; however, there was no significant difference in long-term survival between mice with and without gas insufflation in this murine animal model.