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ABSTRACT: IL-24 (interleukin-24) is a promising, multi-functional anti-cancer agent able to selectively induce tumor cell apoptosis while sparing normal cells. Additionally, IL-24 can enhance the immune response to tumors and suppress tumor angiogenesis. In this study, we introduced IL-24 into the oncolytic adenovirus, Ad·sp·E1A((Δ24))·E1B((Δ55))·IL-24. in which E1A was engineered to target Rb (retinoblastoma) deficient or dysfunctional tumors. The survivin promoter (sp), was used to drive expression of IL-24, thereby allowing it to target most tumors. Finally, the 55 KDa gene of E1B was also deleted, thereby preventing replication in normal cells.
Ad·sp·E1A((Δ24))·E1B((Δ55))·IL-24 showed enhanced antitumor effects over the E1, singly regulated oncolytic adenovirus, ONYX-015, in in vitro experiments. Furthermore, Ad·sp·E1A((Δ24))·E1B((Δ55))·IL-24 could effectively inhibit the progression of NCI-H460 lung carcinoma xenografts in nude mice.
The antitumor effect of Ad·sp·E1A((Δ24))·E1B((Δ55))·IL-24 was assessed by MTT assay and crystal violet staining in a panel of tumor cells. Cell staining and western blotting for caspase activation were used to assess apoptosis. We assessed the antitumor effects of Ad·sp·E1A((Δ24))·E1B((Δ55))·IL-24 in a xenograft model.
This is the first study to use an E1A and E1B triple regulated oncolytic adenovirus vector carrying IL-24 to treat large tumors. We attained efficient antitumor effects both in vitro and in vivo, which provides an experimental foundation for clinical cancer therapy.
Cancer biology & therapy 08/2010; 10(3):242-50. · 2.64 Impact Factor
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ABSTRACT: B8Gly is absolutely conserved in insulins during evolution. Moreover, its corresponding position is always occupied by a Gly residue in other members of insulin superfamily. Previous work showed that Ala replacement of B8Gly significantly decreased both the activity and the foldability of insulin. However, the effects of substitution are complicated, and different replacements sometimes cause significantly different results. To analyze the effects of B8 replacement by different amino acids, three new insulin/single-chain insulin mutants with B8Gly replaced by Ser, Thr or Leu were prepared by protein engineering, and both their foldability and activity were analyzed. In general, replacement of B8Gly by other amino acids causes significant detriment to the foldability of single-chain insulin: the conformations of the three B8 mutants are essentially different from that of wild-type molecules as revealed by circular dichroism; their disulfide stabilities in redox buffer are significantly decreased; their in vitro refolding efficiencies are decreased approximately two folds; the structural stabilities of the mutants with Ser or Thr substitution are decreased significantly, while Leu substitution has little effect as measured by equilibrium guanidine denaturation. As far as biological activity is concerned, Ser replacement of B8Gly has only a moderate effect: its insulin receptor-binding activity is 23% of native insulin. But Thr or Leu replacement produces significant detriment: the receptor-binding potencies of the two mutants are less than 0.2% of native insulin. The present results suggest that Gly is likely the only applicable natural amino acid for the B8 position of insulin where both foldability and activity are concerned.
Acta Biochimica et Biophysica Sinica 11/2005; 37(10):673-9. · 1.38 Impact Factor
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ABSTRACT: Insulin contains three disulfide bonds, one intrachain bond, A6-A11, and two interchain bonds, A7-B7 and A20-B19. Site-directed mutagenesis results (the two cysteine residues of disulfide A7-B7 were replaced by serine) showed that disulfide A7-B7 is crucial to both the structure and activity of insulin. However, chemical modification results showed that the insulin analogs still retained relatively high biological activity when A7Cys and B7Cys were modified by chemical groups with a negative charge. Did the negative charge of the modification groups restore the loss of activity and/or the disturbance of structure of these insulin analogs caused by deletion of disulfide A7-B7? To answer this question, an insulin analog with both A7Cys and B7Cys replaced by Glu, which has a long side-chain and a negative charge, was prepared by protein engineering, and its structure and activity were analyzed. Both the structure and activity of the present analog are very similar to that of the mutant with disulfide A7-B7 replaced by Ser, but significantly different from that of wild-type insulin. The present results suggest that removal of disulfide A7-B7 will result in serious loss of biological activity and the native conformation of insulin, even if the disulfide is replaced by residues with a negative charge.
Biological Chemistry 01/2005; 385(12):1171-5. · 2.96 Impact Factor
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ABSTRACT: The single-chain insulin (PIP) can spontaneously fold into native structure through preferred kinetic intermediates. During refolding, pairing of the first disulfide A20-B19 is highly specific, whereas pairing of the second disulfide is likely random because two two-disulfide intermediates have been trapped. To get more details of pairing property of the second disulfide, four model peptides of possible folding intermediates with two disulfides were prepared by protein engineering, and their properties were analyzed. The four model peptides were named [A20-B19, A7-B7]PIP, [A20-B19, A6-B7]PIP, [A20-B19, A6-A11]PIP, and [A20-B19, A7-A11]PIP according to their remaining disulfides. The four model peptides all adopt partially folded structure with moderate conformational differences. In redox buffer, the disulfides of the model peptides are more easily reduced than those of the wild-type PIP. During in vitro refolding, the reduced model peptides share similar relative folding rates but different folding yields: The refolding efficiency of the reduced [A20-B19, A7-A11]PIP is about threefold lower than that of the other three peptides. The present results indicate that the folding intermediates corresponding to the present model peptides all adopt partially folded conformation, and can be formed during PIP refolding, but the chance of forming the intermediate with disulfide [A20-B19, A7-A11] is much lower than that of forming the other three intermediates.
Protein Science 12/2003; 12(11):2412-9. · 2.80 Impact Factor
