ABSTRACT
Oncolytic viruses armed with therapeutic transgenes of interest show great potential in cancer immunotherapy. Here, a novel oncolytic adenovirus carrying a signal regulatory protein-α (SIRPα)-IgG1 Fc fusion gene (termed SG635-SF) was constructed, which could block the CD47 'don't eat me' signal of cancer cells. A strong promoter sequence (CCAU) was chosen to control the expression of the SF fusion protein, and a 5/35 chimeric fiber was utilized to enhance the efficiency of infection. As a result, SG635-SF was found to specifically proliferate in hTERT-positive cancer cells and largely increased the abundance of the SF gene. The SF fusion protein was effectively detected, and CD47 was successfully blocked in SK-OV3 and HO8910 ovarian cancer cells expressing high levels of CD47. Although the ability to induce cell cycle arrest and cell death was comparable to that of the control empty SG635 oncolytic adenovirus in vitro, the antitumor effect of SG635-SF was significantly superior to that of SG635 in vivo. Furthermore, CD47 was largely blocked and macrophage infiltration distinctly increased in xenograft tissues of SK-OV3 cells but not in those of CD47-negative HepG2 cells, indicating that the enhanced antitumor effect of SG635-SF was CD47-dependent. Collectively, these findings highlight a potent antitumor effect of SG635-SF in the treatment of CD47-positive cancers.
Subject(s)
Antigens, Differentiation/metabolism , CD47 Antigen/immunology , Immunoglobulin G/metabolism , Immunotherapy/methods , Macrophages/immunology , Ovarian Neoplasms/immunology , Receptors, Immunologic/metabolism , Adenoviridae/genetics , Adenoviridae/metabolism , Animals , Antigens, Differentiation/genetics , CD47 Antigen/genetics , CD47 Antigen/metabolism , Cell Cycle Checkpoints/immunology , Cell Death/immunology , Cell Line, Tumor , Cytotoxicity Tests, Immunologic , Female , Humans , Immunoglobulin G/genetics , Macrophages/metabolism , Male , Mice , Mice, Inbred BALB C , Mice, Nude , Ovarian Neoplasms/genetics , Ovarian Neoplasms/metabolism , Phagocytosis/genetics , Phagocytosis/immunology , Receptors, Immunologic/genetics , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Telomerase/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Effective control of non-small-cell lung cancer (NSCLC) remains clinically challenging, especially during advanced stages of the disease. This study developed an adoptive T-cell treatment through expression of a chimeric antigen receptor (CAR) to target human epidermal growth factor receptor (EGFR) in NSCLC. We optimized the non-viral piggyBac transposon system to engineer human T cells for the expression of EGFR-CAR, consisting of EGFR scFv, transmembrane domain, and intracellular 4-1BB-CD3ζ signaling domains. The modified CAR T cells exhibited expansion capability and anticancer efficacy in a time- and antigen-dependent manner in vitro as well as regression of EGFR-positive human lung cancer xenografts in vivo. EGFR-CAR T therapy is a promising strategy to improve the efficacy and potency of the adoptive immunotherapy in NSCLC. Moreover, EGFR-CAR T therapy could become a clinical application for NSCLC patients in the future.
