Fang Guo

Synthesis of the next-generation therapeutic antibodies that combine cell targeting and antibody-catalyzed prodrug activation

An obstacle in the utilization of catalytic Abs for selective prodrug activation in cancer therapy has been systemic tumor targeting. Here we report the generation of catalytic Abs that effectively target tumor cells with undiminished prodrug activation capability. Ab conjugates were prepared by covalent conjugation of an integrin αvβ3-targeting antagonist to catalytic Ab 38C2 through either sulfide groups of cysteine residues generated by reduction of the disulfide bridges in the hinge region or surface lysine residues not involved in the catalytic activity. Using flow cytometry, the Ab conjugates were shown to bind efficiently to integrin αvβ3-expressing human breast cancer cells. The Ab conjugates also retained the retro-aldol activity of their parental catalytic Ab 38C2, as measured by methodol and doxorubicin (dox) prodrug activation. Complementing these Ab conjugates, an evolved set of dox prodrugs was designed and synthesized. Dox prodrugs that showed higher stability and lower toxicity were evaluated both in the presence and absence of the integrin αvβ3-targeting 38C2 conjugates for cell-killing efficacy by using human breast cancer cells. Our study reveals that cell targeting and prodrug activation capabilities can be efficiently combined for selective chemotherapy with novel dox prodrugs.

Ultrastructural changes and localization of nitri oxide synthase in rat lung induced by endotoxin administration

To evaluate the relationship between pulmonary damage and the induction of nitric oxide synthase (NOS) in endotoxin shock, we injected 10mg/kg ofE. coli endotoxin intraperitoneally to Wistar male rats and observed the changes of the lung during the following 8h by electron microscopy, immunoelectron microscopy, and in situ hybridization. Morphological observation revealed infiltration of macrophages, aggregation of neutrophil in stasis in vascular lumens, and intraalveolar hemorrhage accompanied by epithelial damage. Endothelial constitutive NOS (ecNOS) was immunohistochemically localized in the endoplasmic reticulum of the endothelium of pulmonary arteries and in the cytoplasm of bronchial epithelial cells of control rats. After endotoxin administration, inducible NOS (iNOS) was detected in vascular endothelial cells, vascular smooth muscle cells, bronchial epithelial cells, bronchial smooth muscle cells, alveolar epithelial cells, and macrophages. Reverse transcription polymerase cham reaction (RTPCR) confirmed the expression of ecNOS mRNA and iNOS mRNA in the lung in endotoxin-treated rats and controls. In situ hybridization showed that ecNOS mRNA was expressed in vascular endothelial cells of pulmonary arteries in control rats. After endotoxin administration, iNOS mRNA was expressed in vascular endothelial cells. vascular smooth muscle cells, bronchial epithelial cells, alveolar epithelial cells, and macrophages that had infiltrated the alveolar and perivascular regions. After endotoxin administration, morphological changes and NO overproduction were observed, and it is concluded that NO may play an important role in maintaining the homeostasis of the bloodair barrier in pulmonary structures.

Ultrastructural study of the mechanism of perineural extension in pancreatic cancer

Nerve invasion is one of the biological features of pancreatic cancer, and its mechanism remains to be determined. In this paper, we report on 37 pancreatic cancer specimens observed by immunohistochemical and electron microscopical techniques. The results showed that pancreatic cancer directly invaded and destroyed the perineurium. At the early stage of disease, the peripheral nerve and synaptic membrane were easily destroyed by cancer cells, and invasion and metastasis continuously advanced along the perineural space and central side of nerves. These results suggest that the soft tissue and nerve plexus on the dorsal region of the pancreas may contribute to the recurrence of pancreatic cancer after duodenopancreatectomy.