Enhanced inhibition of tumour growth and metastasis, and induction of antitumour immunity by IL-2-IgG2b fusion protein

Chimera of IL-2 linked to light chain of anti-IL-2 mAb mimics IL-2/anti-IL-2 mAb complexes both structurally and functionally

IL-2/anti-IL-2 mAb immunocomplexes were described to have dramatically higher activity than free IL-2 in vivo. We designed protein chimera consisting of IL-2 linked to light chain of anti-IL-2 mAb S4B6 through flexible oligopeptide spacer (Gly(4)Ser)(3). This protein chimera mimics the structure of IL-2/S4B6 mAb immunocomplexes but eliminates general disadvantages of immunocomplexes like possible excess of either IL-2 or anti-IL-2 mAb and their dissociation to antibody and IL-2 at low concentrations. This novel kind of protein chimera is characterized by an intramolecular interaction between IL-2 and binding site of S4B6 mAb similarly as in IL-2/S4B6 mAb immunocomplexes. Our protein chimera has biological activity comparable to IL-2/S4B6 mAb immunocomplexes in vitro, as shown by stimulation of proliferation of purified and activated OT-I CD8(+) T cells. The protein chimera exerts higher stimulatory activity to drive expansion of purified CFSE-labeled OT-I CD8(+) T cells activated by an injection of a low dose of SIINFEKL peptide than IL-2/S4B6 mAb immunocomplexes in vivo.

Stability of the recombinant anti‑erbB2 scFv‑Fc‑interleukin‑2 fusion protein and its inhibition of HER2‑overexpressing tumor cells

The anti‑erbB2 scFv‑Fc‑IL‑2 fusion protein (HFI) is the basis for development of a novel targeted anticancer drug, in particular for the treatment of HER2‑positive cancer patients. HFI was fused with the anti‑erbB2 antibody and human IL‑2 by genetic engineering technology and by antibody targeting characteristics of HFI. IL‑2 was recruited to target cells to block HER2 signaling, inhibit or kill tumor cells, improve the immune capacity, reduce the dose of antibody and IL‑2 synergy. In order to analyse HFI drug ability, HFI plasmid stability was verified by HFI expression of the trend of volume changes. Additionally, HFI could easily precipitate and had progressive characteristics and thus, the buffer system of the additive phosphate‑citric acid buffer, arginine, Triton X‑100 or Tween‑80, the establishment of a microfiltration, ion exchange, affinity chromatography and gel filtration chromatography‑based purification process were explored. HFI samples were obtained according to the requirements of purity, activity and homogeneity. In vivo, HFI significantly delayed HER2 overexpression of non‑small cell lung cancer (Calu‑3) in human non‑small cell lung cancer xenografts in nude mice, and the inhibition rate was more than 60% (P<0.05) in the group treated with 1 mg/kg the HFI dose; HFI significantly inhibited HER2 expression of breast cancer (FVB/neu) transgenic mouse tumor growth in 1 mg/kg of the HFI dose group, and in the following treatment the 400 mm3 tumors disappeared completely. Combined with other HFI test data analysis, HFI not only has good prospects, but also laid the foundation for the development of antibody‑cytokine fusion protein‑like drugs.

Soluble Axl is generated by ADAM10-dependent cleavage and associates with Gas6 in mouse serum

Axl receptor tyrosine kinase exists as a transmembrane protein and as a soluble molecule. We show that constitutive and phorbol 12-myristate 13-acetate-induced generation of soluble Axl (sAxl) involves the activity of disintegrin-like metalloproteinase 10 (ADAM10). Spontaneous and inducible Axl cleavage was inhibited by the broad-spectrum metalloproteinase inhibitor GM6001 and by hydroxamate GW280264X, which is capable of blocking ADAM10 and ADAM17. Furthermore, murine fibroblasts deficient in ADAM10 expression exhibited a significant reduction in constitutive and inducible Axl shedding, whereas reconstitution of ADAM10 restored sAxl production, suggesting that ADAM10-mediated proteolysis constitutes a major mechanism for sAxl generation in mice. Partially overlapping 14-amino-acid stretch deletions in the membrane-proximal region of Axl dramatically affected sAxl generation, indicating that these regions are involved in regulating the access of the protease to the cleavage site. Importantly, relatively high circulating levels of sAxl are present in mouse sera in a heterocomplex with Axl ligand Gas6. Conversely, two other family members, Tyro3 and Mer, were not detected in mouse sera and conditioned medium. sAxl is constitutively released by murine primary cells such as dendritic and transformed cell lines. Upon immobilization, sAxl promoted cell migration and induced the phosphorylation of Axl and phosphatidylinositol 3-kinase. Thus, ADAM10-mediated generation of sAxl might play an important role in diverse biological processes.

Antibody engineering for therapeutics

With the acceptance of antibodies as therapeutics, a diversity of engineered antibody forms have been created to improve their efficacy, including enhancing the effector functions of full-length antibodies, delivering toxins to kill cells or cytokines in order to stimulate the immune system, and bispecific antibodies to target multiple receptors. After years of in vitro investigation, many of these are now moving into clinical trials and are showing promise. A potential new type of effector function for antibodies, that is, the generation of reactive oxygen species that may effect inflammation or bacterial killing, has been elucidated. In addition, the field has expanded beyond a concentration on immunoglobulin G to include immunoglobulin A antibodies as potential therapeutics.

Comparison of therapeutic efficacy between tumor-derived heat shock protein 70 and interleukine-2

AIM

To compare and analyze the therapeutic effect of tumor-derived heat shock protein 70 and globally accepted interleukin-2, to evaluate the anti-tumor capacity of HSP70, and to provide significant information for HSP70 administration to treat human cancers.

METHODS

Cell Culture, techniques for protein extraction and purification, SDS-PAGE, Western-blot and animal experiment were used in this study.

RESULTS

Both IL-2 and HSP70 showed therapeutic effect in tumor-bearing mice. The best effect was observed in 100 000 U IL-2 and 10 μg HSP70 administrations, and partial efficacy was found in 50000 U IL-2 and 5 μg HSP70 administrations. The effect of 100000 U IL-2 was nearly as good as that of 5 μg HSP70. About 40 % mice receiving HSP70 10 μg administration survived over 90 days, the average survival period of this group was over 56.8 days, whereas the control group was 17.3 days, IL-2 50 000 group, 26.3 days, IL-2 100 000 group, 36.6 days, and 5 μg HSP70 group, 27.7 days. Significant difference was found (P<0.05) when compared with the HSP70 10 μg group and control group.

CONCLUSION

HSP70 has a specific anti-tumor effect and obviously exceeded IL-2 .Those data provide significant information for the treatment of human cancers.