MiR-7 deficiency promotes Th1 polarization of CD4⁺T cells and enhances the antitumor effect in adoptive cell therapy for lung cancer

Adoptive-cell-therapy (ACT) is important therapeutic approach against cancer. We previously showed that miR-7 deficiency endowed CD4⁺T cells with hyperactivation status in liver injury. However, whether CD4⁺T cells with miR-7 deficiency could elicit antitumor effect in ACT is still unclear. Naïve CD4⁺CD62L^hi T cells were purified from CD45.2 WT or CD45.2 miR-7^def mice and transferred into syngeneic CD45.1WT mice bearing with lung tumor cells. The infiltration and function of T cells were measured by FCM and immunofluorescence assay. And naïve CD4⁺CD62L^hi T cells were purified from CD45.2 WT or CD45.2 miR-7^def mice, then the cells were activated with CD3 antibody plus CD28 antibody in vitro for 24 h. Then, the cultured supernatant of LLC tumor cells or cytokines IFN-γ and IL-12 was added to establish Th1 polarization. Under these conditions, Th1 polarization-related molecules in these cells were analyzed by flow cytometry. Our data demonstrated a significant reduction in the growth and metastasis of lung cancer cells in the miR-7^def CD4⁺T cell-transferred group, accompanied by a significant enhancement in the infiltration, proliferation, activation, and Th1 polarization of CD4⁺ T cells. Moreover, we observed the proliferation; activation of tumor-infiltrating CD8⁺ T cells was significantly increased in the local tumor of the CD45.2 miR-7^def CD4⁺ T cell-transferred group, compared to the CD45.2 WT CD4⁺ T cell-transferred group. It is noteworthy that MAPK4, a target molecule of miR-7, was upregulated in CD4⁺ T cells from lung tumor tissues, resulting in an altered transduction of phosphorylation of NF-κB as well as AKT and ERK in vivo and in vitro. miR-7 deficiency promoted Th1-polarization of CD4⁺ T cells and elicited effective antitumor immune responses in ACT.