ABSTRACT
Drugs targeting immune checkpoint are used for cancer treatment, but resistance to single drug may occur. Combination therapy blocking multiple checkpoints simultaneously can improve clinical outcome. Therefore, we designed a recombinant protein rPC to block multiple targets, which consists of extracellular domains of programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). The coding sequence was inserted into expression vector and stably transfected into HEK293 cells. The culture supernatant was collected and rPC was affinity-purified. Real-time quantitative PCR was used to evaluate the expression levels of ligands for PD-1 and CTLA-4 in several human cancer cell lines. The binding of rPC with cancer cells was examined by immunofluorescence cell staining, the influence of rPC on cancer cell growth was assayed by CCK-8. The results showed that rPC could be expressed and secreted by stably transfected HEK293 cells, the purified rPC could bind to lung cancer NCI-H226 cells which have high levels of ligands for PD-1 and CTLA-4, no direct impact on cancer cell growth could be observed by rPC treatment. The recombinant protein rPC can be functionally assayed further for developing novel immunotherapeutic drugs for cancer.
Subject(s)
Animals , Humans , CTLA-4 Antigen , Genetics , Cell Proliferation , HEK293 Cells , Lung Neoplasms , Metabolism , Programmed Cell Death 1 Receptor , Genetics , Protein Binding , Protein Domains , Genetics , Recombinant Fusion Proteins , Genetics , MetabolismABSTRACT
Ribonucleotide reductase ( RR ) is a rate-limiting enzyme, and it is responsible for reducing ribonucleotides to their corresponding deoxyribonucleotides , which are the building blocks required for DNA replication and repair .Recent studies have revealed that RR activity is associated with DNA replication in virus , and RR inhibitors have been used for clinical antiviral treatment .This paper reviews research progress on RR and its inhibitors , including the classification , structure and function of RR; the classification, mechanism and clinical application of RR inhibitors in antiviral therapy and the future prospects of RR inhibitors .