Overexpression of Soluble Human Thymosin Alpha 1 in Escherichia coli

Truncated human LMP-1 triggers differentiation of C2C12 cells to an osteoblastic phenotype in vitro

LIM mineralization protein-1 (LMP-1) is a novel intracellular osteoinductive protein that has been shown to induce bone formation both in vitro and in vivo. LMP-1 contains an N-terminal PDZ domain and three C-terminal LIM domains. In this study, we investigated whether a truncated form of human LMP-1 (hLMP-1[t]), lacking the three C-terminal LIM domains, triggers the differentiation of pluripotent myoblastic C(2)C(12) cells to the osteoblast lineage. C(2)C(12) cells were transiently transduced with Ad5-hLMP-1(t)-green fluorescent protein or viral vector control. The expression of hLMP-1(t) RNA and the truncated protein were examined. The results showed that hLMP-1(t) blocked myotube formation in C(2)C(12) cultures and significantly enhanced the alkaline phosphatase (ALP) activity. In addition, the expressions of ALP, osteocalcin, and bone morphogenetic protein (BMP)-2 and BMP-7 genes were also increased. The induction of these key osteogenic markers suggests that hLMP-1(t) can trigger the pluripotent myoblastic C2C12 cells to differentiate into osteoblastic lineage, thus extending our previous observation that LMP-1 and LMP-1(t) enhances the osteoblastic phenotype in cultures of cells already committed to the osteoblastic lineage. Therefore, C(2)C(12) cells are an appropriate model system for the examination of LMP-1 induction of the osteoblastic phenotype and the study of mechanisms of LMP-1 action.

Co-application of ricin A chain and a recombinant adenovirus expressing ricin B chain as a novel approach for cancer therapy

AIM

To develop a novel ricin-based approach for the safe and effective therapy of cancer.

METHODS

The ricin A chain (RTA) was expressed in Escherichia coli in the form of a 6XHis-tagged fusion protein and purified with Ni(2+)-NTA affinity resin. A replication-deficient ricin B chain (RTB)-expression adenovirus green fluorescence protein (AdGFP-RTB) was constructed. RTA and AdGFP-RTB were tested for cytotoxicity either individually or in combination in human cell lines HEK293, HeLa, SMMC7721, and HL7702. Cell viability was determined with trypan blue staining or MTT assay.

RESULTS

The expression and release of RTB, as well as the entry of RTA into AdGFP-RTB-infected cells were confirmed. When RTA and AdGFP-RTB was used individually, neither was toxic to the cells. When they were applied together, significant cell death was observed in all of the cell lines tested. The cell-killing effect correlated with the amount of RTA protein used, with cell mortality at about 60% at 4.8 mu g RTA in combination with AdGFP-RTB at 100 pfu/cell. No major cell killing was seen when RTA was used in combination with a control adenovirus AdGFP. The treatment of healthy HeLa cells with the virusfree supernatant from AdGFP-RTB/RTA-treated HeLa cells resulted in cell death, suggesting the formation of RTA/RTB complex, and a potential by-stander effect.

CONCLUSION

The new approach was successful in vitro. Further modifications of the adenovirus vector, as well as an in vivo study are needed to confirm its potential in cancer therapy.