Utilization of novel lectin-conjugated Au nanoparticles as Thomsen-Friedenreich onco-antigen target for in vitro cytotoxicity and apoptosis induction in leukemic cell line.

Leukemia is a tumor of blood-forming tissues including bone marrow and lymphatic nodes, which comprise biologically distinct subgroups. In the present study, Au NPs-PEG-Lectin was prepared as a drug targeting system for potential Thomsen-Friedenreich antigen (TF-Ag) presented on the surface of leukemic cells to induce cytotoxicity. Gold nanoparticles were prepared using citrate reduction method and conjugated with lectin via SH-PEG-COOH. The conjugate was characterized using UV/Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential, and Scanning electron microscopy (SEM) with subsequent applications for cytotoxicity, cell cycle analysis, and apoptosis. Immunophenotypically blood samples from patients with acute lymphoblastic leukemia (ALL) were positively expressed CD45, CD95 dim expression, and low CD176 (TF-Ag) expression. Samples of acute myeloid leukemia (AML) confirmed the expression of all markers. Au NPs-PEG-Lectin conjugate showed an average size of 35.82 nm with zeta potential of -27.33 with accelerated lectin release from the conjugate at acidic pH. Au NPs-PEG-Lectin demonstrated the highest and most significant cytotoxic activity against HL-60 and K562 with IC50 of 132.5 and 314.8 µg mL-1, respectively. Flow cytometric analysis revealed induction of HL-60 cell apoptosis upon conjugate treatment in a dose-dependent pattern up to 51.03 % with no sign of necrosis with cell cycle arrest at G0/G1 phase. HL-60 cells treated with Au NPs-PEG-Lectin exhibited inter-nucleosomal DNA fragmentation. Morphologically, Phospho-Histone/BrdU dual staining indicated that Au NPs-PEG-Lectin initiated HL-60 arrest at G0/G1 phase. Taken together, molecular docking verified the possible interaction between lectin amino acids and different hydroxy groups within TF-Ag forming hydrogen bonds.

Therapeutic efficacy of the humanized JAA-F11 anti-Thomsen-Friedenreich antibody constructs H2aL2a and H3L3 in human breast and lung cancer xenograft models.

The Thomsen-Friedenreich antigen (TF-Ag-α) is found on ~85% of human carcinomas but is cryptic on normal tissue. The humanized highly specific hJAA-F11-H2aL2a and -H3L3 antibodies target TF-Ag-α without binding to TF-Ag-beta (found on surface glycolipids of some normal cells). The relative affinity of H3L3 is 17 times that of H2aL2a, which would seem to favor superior efficacy, however, increased affinity can result in less tumor penetration. To assess the potential therapeutic efficacy of these antibodies, four human cancer- mouse xenograft models were treated with H2aL2a and H3L3. The tumor xenograft models used were human non-small cell lung cancer, H520, and small cell lung cancer, HTB171 in nude mice and human triple negative breast cancer, MDA-MB-231 and HCC1806 in SCID mice. H2aL2a significantly decreased tumor growth in both breast and both lung cancer models. H2aL2a showed statistically equal or better efficacy than H3L3 and has superior production capabilities. These results suggest that H2aL2a may be superior as a naked antibody, as an antibody drug conjugate or as a radiolabeled antibody, however the higher affinity of H3L3 may lead to better efficacy in bi-specific therapies in which the binding is decreased due to the presence of only one TF-Ag-α binding site.

The Potential Action of Thomsen-Friedenreich Monoclonal Antibody (A78-G/A7) in Thyroid Cancer.

BACKGROUND: Thomsen-Friedenreich antibody (TF-Ab) is a specific antibody against the Thomsen-Friedenreich antigen (TF-Ag). At present, studies on a number of other tumors have shown that TF-Ab can effectively inhibit metastasis and induce apoptosis in tumor cells. However, the role of TF-Ab in thyroid cancer (TC) remains unclear. MATERIALS AND METHODS: Normal subjects and patients with primary papillary TC with or without lymph node metastasis were tested for TF-Ab expression by enzyme-linked immunosorbent assays (ELISAs). Immunofluorescence was used to assess the expression of TF-Ag in thyroid papillary carcinoma with or without lymph node metastasis and undifferentiated cancer tissues. To evaluate the role of TF-Ab in TC, the effects of TF monoclonal antibody (mAb A78-G/A7) on cell biological function were investigated by MTT assays, flow cytometry, adhesion assays and transwell experiments. RESULTS: Compared with normal individuals, TF-Ab levels in patients with TC were decreased, but no changes were observed with respect to lymph node metastasis. The expression of TF-Ag in TC tissues was relatively higher than that detected in adjacent tissues, but it was not affected by the presence or absence of lymph node metastasis. Upon treatment mAb A78-G/A7 treating, TC cell cycles were affected, meanwhile the abilities to adhere, invade and migrate were also significantly reduced. CONCLUSION: The results of the present study showed that mAb A78-G/A7 could affect the invasion and migration of all assayed TC cell lines. The effects of mAb A78-G/A7 on the cell cycle, adhesion, invasion and migration of TC cells were more significant than those observed for proliferation and apoptosis.