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Treatment with lentiviral vectors encoding shRNA against interleukin 10 modulates the immunosuppressive activity of murine colon carcinoma-associated myeloid-derived suppressor cells.

ABSTRACT: Myeloid-derived suppressor cells (MDSCs) are potent suppressors of antitumor immunity and their accumulation is often associated with poor prognosis. The aim of the present study was to determine the mechanisms of action of lentiviral vectors encoding short hairpin (sh)RNA against interleukin-10 (IL-10), with particular emphasis on their influence on the activity of tumor-derived MDSCs. Lentiviral vectors encoding shRNA against IL-10 (shIL-10 LVs) were utilized to silence the expression of IL-10 either in MDSCs that were generated ex vivo from bone marrow cells cultured in the presence of supernatant from MC38 colon carcinoma cells, or in situ in the MC38 murine colon carcinoma environment. Although monocytic MDSCs (M-MDSCs) transduced with shIL-10 LVs exhibited increased suppressor activity, transduction of polymorphonuclear MDSCs (PMN-MDSCs) appeared to reduce their ability to inhibit T lymphocyte functions. Analysis of EGFP expression in MC38 tumors revealed that intratumorally inoculated shIL-10 LVs transduced tumor-infiltrating myeloid cells with the highest efficiency and, led to a decreased IL-10 level in the tumor microenvironment. However, the effect was accompanied by increased influx of PMN-MDSCs into tumors observed both on the 6th and on the 10th day after shIL-10 LV injections. Nevertheless, it was noted that suppressor activity of myeloid cells isolated from tumors was dependent on the efficiency of tumor-derived PMN-MDSC transduction with shIL-10 LVs. The increased percentage of transduced PMN-MDSCs on the 10th day was associated with diminished immunosuppressive activity of tumor-derived myeloid cells and an elevated ratio of cytotoxic T lymphocytes to M-MDSCs. The obtained data indicated that treatment with shIL-10 LVs may result in modulation of the immunosuppressive activity of MC38 colon carcinoma-derived MDSCs.

SUBMITTER: Anger-Gora N

PROVIDER: S-EPMC8190769 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Myeloid-derived suppressor cells (MDSCs) are potent suppressors of immune function and may play a key role in the development and progression of metastatic cancers. Aerobic exercise has been shown to have anticancer effects, yet the mechanisms behind this protection are largely unknown. Therefore, we examined the effects of physical activity on MDSC accumulation and function. METHODS:Female BALB/c mice were assigned to one of two primary groups: sedentary tumor (SED+TUM) or wheel run tumor (WR+TUM). After 6 weeks of voluntary wheel running, all animals were randomly subdivided into 4 different timepoint groups; 16, 20, 24, and 28 days post-tumor injection. All mice were inoculated with 4T1 mammary carcinoma cells in the mammary fat pad and WR groups continued to run for the specified time post-injection. Spleen, blood, and tumor samples were analyzed using flow cytometry to assess proportions of MDSCs. RESULTS:Cells expressing MDSC biomarkers were detected in the spleen, blood, and tumor beginning at d16. However, since there was no evidence of immunosuppressive function until d28, we refer to them as immature myeloid cells (IMCs). Compared to SED+TUM, levels of IMCs in the spleen were significantly lower (p < 0.05) in WR+TUM at day 16 (33.0 ± 5.2%; 23.1 ± 10.2% of total cells, respectively) and day 20 (33.9 ± 8.1%; 24.3 ± 5.1% of total cells, respectively). Additionally, there were fewer circulating IMCs in WR+TUM at day 16 and MDSC levels were significantly lower (p < 0.05) in the tumor at day 28 in WR+TUM. Additionally, a non-significant 62% and 26% reduction in metastatic lung nodules was observed at days 24 and 28, respectively. At day 28, MDSCs harvested from SED+TUM significantly suppressed CD3+CD4+ T cell proliferation (3.2 ± 1.3 proliferation index) while proliferation in WR+TUM MDSC co-cultures (5.1 ± 1.7 proliferation index) was not different from controls. CONCLUSIONS:These findings suggest that physical activity may delay the accumulation of immunosuppressive MDSCs providing a broader window of opportunity for interventions with immunotherapies.

Project description:Metastatic relapse of breast cancer and other tumor types usually occurs several years after surgical resection of the primary tumor. Early dissemination of tumor cells followed by an extended period of dormancy is thought to explain this prevalent clinical behavior. By using a gain-of-function retroviral cDNA screen in the mouse, we found that Coco, a secreted antagonist of TGF-beta ligands, induces solitary mammary carcinoma cells that have extravasated in the lung stroma to exit from dormancy. Mechanistic studies demonstrate that Coco awakens dormant metastasis-initiating cells by blocking stroma-derived Bone Morphogenetic Proteins. Inhibition of canonical BMP signaling reverses the commitment to differentiation of these cells and enhances their self-renewal and tumor-initiation capacity. Expression of Coco induces a discrete gene expression signature strongly associated with metastatic relapse to the lung but not to the bone or brain in primary patients’ samples. Accordi ngly, silencing of Coco does not inhibit metastasis to the bone or brain in mouse models. These findings suggest that metastasis-initiating cells require the self-renewal capability typically associated with stem cells in order to exit from dormancy and identify Coco as a master regulator of this process. The Affymetrix HG-U133A and Agilent platforms, which were used to build MSK82 [GSE2603], EMC192 [GSE12276], EMC286 [GSE2034], and NKI295 [van 't Veer et al., 2002; van de Vijver et al.,2002; Fan et al., 2006] datasets, do not contain probes for Coco, preventing a direct analysis of the correlation of the expression of Coco with metastatic relapse. We therefore examined the changes in gene expression caused by silencing of Coco in MDA-MB231 cells in vitro and used the resulting signature as a proxy of Coco expression. Compare the gene expression profile between shscramble with shCoco knockingdown MDA-MB231 cells Coco shRNA #2 corresponds to TRCN0000149666 and Coco shRNA #4 corresponds to TRCN0000148148.

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Treatment with lentiviral vectors encoding shRNA against interleukin 10 modulates the immunosuppressive activity of murine colon carcinoma-associated myeloid-derived suppressor cells.

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