Project description:Given that TREX1-deficient tumor cells showed a growth delay in immunocompetent but not immunodeficient hosts, we characterize the consequences of CT26 tumor-intrinsic TREX1 loss on the host immune system by performing single-cell RNA sequencing on intra-tumoral immune cells sorted from control and TREX1 KO CT26 tumors.
Project description:T cell infiltration is essential for immune checkpoint inhibitors to be effective in treating solid cancers. Through a bioinformatic pipeline, we identified a target gene SUN1 that might relate to modulating immune cell infiltration and immune response. Thus, we generated one Sun1_knockout CT26 cell line (Sun1_KO) using CRISPR-Cas9. By performing multiome single nuclei sequencing using tumors grown in syngeneic model, we set out to understand how mouse Sun1 can affect the regulatory network in tumor cells in vivo.
Project description:T cell infiltration is essential for immune checkpoint inhibitors to be effective in treating solid cancers. Through a bioinformatic pipeline, we identified a target gene SUN1 that might relate to modulating immune cell infiltration and immune response. Thus, we generated one Sun1_knockout CT26 cell line (Sun1_KO) and two control CT26 cell lines (Sun1_Control) using CRISPR-Cas9. By performing RNA-seq on cultured cells, tumors grown in syngeneic model, and purified tumor cells from tumors grown in syngeneic model, we set out to understand how mouse Sun1 can affect immune-related pathways and immune cell infiltration and anti-PD1 efficacy in BALB/c mice.
Project description:Goal: Microsatellite-instable (MSI) tumors are one of the few cancers that respond to immune checkpoint blockade (ICB); however, the mechanism of MSI status development is unclear. Here, we report that protein phosphatase 2A (PP2A) deletion or inactivation converted cold microsatellite-stable (MSS) into MSI tumors. Objectives: Using RNA sequencing data of three CT26-shppp2r1a data and a CT26-scr data, we demonstrate that these intestinal tumors display differential core driver pathways.
Project description:Recently, attenuated Semliki Forest virus vector VA7 completely eliminated type I interferon (IFN) unresponsive human U87 glioma xenografts while IFN responsive mouse GL261 and CT-2A gliomas proved refractory to the oncolytic virotherapy. Here we describe in two clones of a well established Balb/c mouse tumor cell line, CT26 murine colon carcinoma, diametrically opposed IFN responsiveness and sensitivity to oncolytic virus. Both CT26WT and CT26LacZ clones secreted biologically active type I IFN in vitro upon infection but virus replication was self-limiting only in CT26WT cells. Total transcriptome sequencing (RNA-Seq) and western blotting experiments revealed that in sharp contrast to CT26LacZ cells, CT26WT cells had strong constitutive expression of 56 different genes associated with pattern recognition and type I interferon signaling pathways, spanning two reported anti-RNA virus gene signatures and22 genes that have been reported to have direct anti-Alphaviral activity. Correspondingly, only CT26LacZ tumors were infectable in vivo, resulting in rapid central necrosis of the tumors by 96 hours post infection and complete tumor eradication both in immunocompetent and in SCID mice. CT26LacZ tumor eradication by oncolysis induced 100% protective immunity against homologous CT26LacZ challenge but only 50% protection against heterologous CT26WT challenge, indicating LacZ immune dominance over shared antigens. We believe the two clone CT26 system described herein constitutes a challenging yet realistic model for clonally and immunologically heterogeneous cancer where a strong therapy efficacy bias toward sensitive tumor subpopulations might falsely predict therapeutic success on a broad patient scale highlighting the necessity of successful pre-screening for responsive tumors. RNA-Seq in CT26 tumor cell line
Project description:Expression of miRNAs in an EBV-positive B-cell strain, 28-2. 28-2 are infected with a derivative of the B-958 strain of EBV, which expresses eGFP constitutively and LMP1 fused to mRFP from its native promoter. Single cells were sorted by flow cytometry for their levels of LMP1-mRFP (5% expressing the lowest levels of LMP1-mRFP or 5% expressing the highest levels of LMP1-mRFP)
Project description:Selenium has cancer preventive activity that is mediated, in part, through selenoproteins. The role of the 15 kDa selenoprotein (Sep15) in colon cancer was assessed by preparing and using mouse colon CT26 cells stably transfected with shRNA constructs targeting Sep15. Metabolic 75Se-labeling and Northern and Western blot analyses revealed that more than 90% of Sep15 was knocked down. Growth of the resulting Sep15-deficient CT26 cells was reduced (p<0.01) and cells formed significantly (p<0.001) fewer colonies in soft agar compared to control CT26 cells. Whereas most (14/15) BALB/c mice injected with control cells developed tumors, few (3/30) mice injected with Sep15 knockdown cells developed tumors (p<0.0001). The ability to form pulmonary metastases had similar results. Mice injected with the plasmid-transfected control cells had >250 lung metastases/mouse; however, mice injected with the Sep15 knockdown cells only had 7.8 +/- 5.4 metastases. To investigate molecular targets affected by Sep15 status, gene expression patterns between control and knockdown CT26 cells were compared. Ingenuity Pathways Analysis was used to analyze the 1045 genes that were significantly (p<0.001) affected by Sep15 deficiency. The highest scored biological functions were cancer and cellular growth and proliferation. Consistent with these observations, subsequent analyses revealed a G2/M cell cycle arrest in Sep15 CT26 knockdown cells. In contrast, to CT26 cells Sep15 knockdown in Lewis Lung Carcinoma (LLC1) cells did not affect anchorage-dependent or M-bM-^@M-^Sindependent cell growth. These data suggest tissue specificity in the cancer protective effects of Sep15 knockdown, which are mediated, at least in part, by influencing the cell cycle. mRNA was isolated from plasmid-transfected control and shSep15 knockdown CT26 cells (three replicates of each). Microarray analysis was performed on Affymetrix Mouse 430_2 gene chips. Three arrays were analyzed from different mRNA samples for each construct.