Isolation of anti-tumor monoclonal antibodies targeting on MICA/B α3 domain by single B cell technology for colon cancer therapy.

Colon cancer (CC) is one of the most common gastrointestinal malignancies. Effectiveness of the existing therapies is limited. Immunotherapy is a promising complementary treatment approach for CC. Major histocompatibility complex class I-related protein A and B (MICA/B) are ligands for NK cells. Shedding of MICA/B from the surface of tumor cells by cleavage of MICA/B at the membrane proxial region in MICA/B α3 structural domain is one of immune evasion strategies leading to escape of cancer cells from immunosurveillance. In this study, we generated a panel of MICA/B monoclonal antibodies (mAbs) and identified one of mAbs, mAb RDM028, that had high binding affinity to MICA/B and recognized a site on MICA/B α3 structural domain that is critically important for cleavage of MICA/B. Our study has further demonstrated that RDM028 augmented the surface expression of MICA/B on HCT-116 human CC cells by inhibiting the MICA/B shedding resulting in the enhanced cyotoxicity of NK cells against HCT-116 human CC cells and mediated anti-tumor activity in nude mouse model of colon cancer. These results indicate that mAb RDM028 could be explored for developing as an effective immuno therapy against CC by targeting the MICA/B α3 domain to promot immunosurveillance mediated by MICA/B-NKG2D interaction.

Structural analysis and blood-enriching effects comparison based on biological potency of Angelica sinensis polysaccharides.

Angelica sinensis is a long-standing medicine used by Chinese medical practitioners and well-known for its blood-tonic and blood-activating effects. Ferulic acid, ligustilide, and eugenol in Angelica sinensis activate the blood circulation; however, the material basis of their blood-tonic effects needs to be further investigated. In this study, five homogeneous Angelica sinensis polysaccharides were isolated, and their sugar content, molecular weight, monosaccharide composition, and infrared characteristics determined. Acetylphenylhydrazine (APH) and cyclophosphamide (CTX) were used as inducers to establish a blood deficiency model in mice, and organ indices, haematological and biochemical parameters were measured in mice. Results of in vivo hematopoietic activity showed that Angelica sinensis polysaccharide (APS) could elevate erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF), and interleukin-3 (IL-3) serum levels, reduce tumor necrosis factor-α (TNF-α) level in mice, and promote hematopoiesis in the body by regulating cytokine levels. Biological potency test results of the in vitro blood supplementation indicated strongest tonic activity for APS-H2O, and APS-0.4 has the weakest haemopoietic activity. The structures of APS-H2O and APS-0.4 were characterized, and the results showed that APS-H2O is an arabinogalactan glycan with a main chain consisting of α-1,3,5-Ara(f), α-1,5- Ara(f), ß-1,4-Gal(p), and ß-1,4-Gal(p)A, and two branched chains of ß-t-Gal(p) and α-t-Glc(p) connected to each other in a (1→3) linkage to α-1,3,5-Ara(f) on the main chain. APS-0.4 is an acidic polysaccharide with galacturonic acid as the main chain, consisting of α-1,4-GalA, α-1,2-GalA, α-1,4-Gal, and ß-1,4-Rha. In conclusion, APS-H2O can be used as a potential drug for blood replenishment in patients with blood deficiency, providing a basis for APS application in clinical treatment and health foods, as well as research and development of new polysaccharide-based drugs.