Jiajie Tu

Growth arrest‐specific transcript 5 represses endometrial cancer development by promoting antitumor function of tumor‐associated macrophages

AbstractThe tumor‐suppressor role of long noncoding RNA (lncRNA) growth arrest‐specific transcript 5 (GAS5) has been proven in various types of cancer. However, the specific function of GAS5 in tumor‐associated macrophages (TAMs) of endometrial cancer (EC) is elusive. Quantitative PCR results showed that GAS5 expression decreased in EC tissues and primary TAMs from EC tumors. Tumor‐associated macrophage infiltration was significantly positively associated with the developmental stage of EC. Direct coculture of GAS5‐overexpressing TAMs and EC cells showed that GAS5 enhanced phagocytosis, antigen presentation, and activation of cytotoxic T cells, and repressed “Don’t eat me” signals between TAMs and EC cells. Tumor formation in immunodeficient mice showed that GAS5‐overexpressing macrophages could repress EC formation in vivo. GAS5 promoted M1 polarization by activating the microRNA‐21– phosphatase and tensin homolog (PTEN)–AKT signaling pathway and directly repressing the nuclear accumulation and phosphorylation of oncogenic yes‐associated protein 1 (YAP1) in TAMs. GAS5 inhibited the development of EC from both innate and adaptive immunity by transforming TAMs from a protumor to an antitumor phenotype. These antitumor effects of GAS5 on TAMs were mediated by the activation of the miR‐21‐PTEN‐AKT pathway and inhibition of YAP1.

IL-21 promotes the anti-tumor effect of anti-CD47 chimeric antigen receptor macrophages in ovarian cancer

Macrophages play a key role in immunity against solid tumors. However, their development and clinical applications are limited by their difficult-to-transfect nature, low proliferative capacity, and easily changing polarization states. The combination of chimeric antigen receptor (CAR) technology with macrophages to form chimeric antigen receptor macrophages (CAR-Ms) is an emerging strategy for adoptive cell therapy. In our previous study, we confirmed that anti-CD47 CAR-Ms have potential for ovarian cancer treatment. Here, we demonstrated that the introduction of IL-21 significantly increases the tumor-suppressive effect of anti-CD47 CAR-Ms against ovarian cancer. Specifically, IL-21-modified CAR-Ms with second-generation CARs targeting CD47 showed potent tumor cell-killing activity, both in vitro and in vivo, through direct and indirect pathways (direct phagocytosis and activation of cytotoxic T lymphocytes). In addition, an IL-21 modification significantly enhanced the tumor microenvironmental regulation of immunosuppression mediated by anti-CD47 CAR-Ms in vivo, thereby improving their therapeutic efficacy in a mouse model of ovarian cancer, without any obvious adverse effects. Taken together, these results suggest that anti-CD47 CAR-Ms combined with IL-21 is a promising treatment strategy for ovarian cancer.

The application of HER2 and CD47 CAR-macrophage in ovarian cancer

Abstract Background The chimeric antigen receptor (CAR)-T therapy has a limited therapeutic effect on solid tumors owing to the limited CAR-T cell infiltration into solid tumors and the inactivation of CAR-T cells by the immunosuppressive tumor microenvironment. Macrophage is an important component of the innate and adaptive immunity, and its unique phagocytic function has been explored to construct CAR macrophages (CAR-Ms) against solid tumors. This study aimed to investigate the therapeutic application of CAR-Ms in ovarian cancer. Methods In this study, we constructed novel CAR structures, which consisted of humanized anti-HER2 or CD47 scFv, CD8 hinge region and transmembrane domains, as well as the 4-1BB and CD3ζ intracellular domains. We examined the phagocytosis of HER2 CAR-M and CD47 CAR-M on ovarian cancer cells and the promotion of adaptive immunity. Two syngeneic tumor models were used to estimate the in vivo antitumor activity of HER2 CAR-M and CD47 CAR-M. Results We constructed CAR-Ms targeting HER2 and CD47 and verified their phagocytic ability to ovarian cancer cells in vivo and in vitro. The constructed CAR-Ms showed antigen-specific phagocytosis of ovarian cancer cells in vitro and could activate CD8+ cytotoxic T lymphocyte (CTL) to secrete various anti-tumor factors. For the in vivo model, mice with human-like immune systems were used. We found that CAR-Ms enhanced CD8+ T cell activation, affected tumor-associated macrophage (TAM) phenotype, and led to tumor regression. Conclusions We demonstrated the inhibition effect of our constructed novel HER2 CAR-M and CD47 CAR-M on target antigen-positive ovarian cancer in vitro and in vivo, and preliminarily verified that this inhibitory effect is due to phagocytosis, promotion of adaptive immunity and effect on tumor microenvironment.