Retrovirus-mediated gene transfer of human endostatin inhibits growth of human liver carcinoma cells SMMC7721 in nude mice

MR reporter gene imaging of endostatin expression and therapy

PURPOSE

The aim of this study is to monitor endostatin gene expression and therapy using transferrin receptor (TfR) as reporter gene and transferrin conjugate of ultrasmall supramagnetic iron oxide nanoparticle (Tf-USPIO) as magnetic resonance (MR) reporter probe.

PROCEDURE

A retroviral plasmid (pLP-LNCX) encoding mouse endostatin and TfR was constructed, and packaged with a titer of 4 × 10(7)colony-forming units per millimeter. MDA-MB-231 breast tumors were established in BALB/c mice by subcutaneous injection of 2 × 10(6) MDA-MB-231 cells. Mice were intratumorally injected with recombinant retrovirus and imaged with MR using Tf-USPIO. Western blot, Prussian blue, and immunohistochemical staining were performed to validate the magnetic resonance imaging results. The antitumor effect of retro-endostatin (ES)-TfR was also evaluated by intratumoral injection of the viral vector.

RESULTS

The expression of both endostatin and TfR genes in MDA-MB-231 cells after retroviral transfection was confirmed by Western blot and flow cytometry. Tf-USPIO conjugate binds specifically to cells stably transfected with retro-ES-TfR. After intravenous injection of the Tf-USPIO conjugate, there was a more pronounced decrease in T2 relaxation time in tumors treated with retro-ES-TfR than in tumors treated with empty retrovirus retro-LNCX. The expression of ES gene significantly delayed the growth of MDA-MB-231 tumor and reduction of microvessel density and VEGF level as compared to those without viral transfection or transfected with empty retro-LNCX vector.

CONCLUSIONS

Endostatin therapeutic gene expression was visualized successfully using TfR reporter gene and Tf-USPIO MR reporter probe, which indicates that MR reporter gene imaging may be valuable in gene therapy to evaluate therapeutic gene expression and treatment efficacy.

Effective gene-viral therapy for telomerase-positive cancers by selective replicative-competent adenovirus combining with endostatin gene

Gene-viral therapy, which uses replication-selective transgene-expressing viruses to manage tumors, can exploit the virtues of gene therapy and virotherapy and overcome the limitations of conventional gene therapy. Using a human telomerase reverse transcriptase-targeted replicative adenovirus as an antiangiogenic gene transfer vector to target new angiogenesis and making use of its unrestrained proliferation are completely new concepts in tumor management. CNHK300-mE is a selective replication transgene-expressing adenovirus constructed to carry mouse endostatin gene therapeutically. Infection with CNHK300-mE was associated with selective replication of the adenovirus and production of mouse endostatin in telomerase-positive cancer cells. Endostatin secreted from a human gastric cell line, SGC-7901, infected with CNHK300-mE was significantly higher than that infected with nonreplicative adenovirus Ad-mE in vitro (800 +/- 94.7 ng/ml versus 132.9 +/- 9.9 ng/ml) and in vivo (610 +/- 42 ng/ml versus 126 +/- 13 ng/ml). Embryonic chorioallantoic membrane assay showed that the mouse endostatin secreted by CNHK300-mE inhibited angiogenesis efficiently and also induced distortion of pre-existing vasculature. CNHK300-mE exhibited a superior suppression of xenografts in nude mice compared with CNHK300 and Ad-mE. In summary, we provided a more efficient gene-viral therapy strategy by combining oncolysis with antiangiogenesis.

Gonadotropin hormone-releasing hormone analog induces apoptosis in human hepatocarcinoma cell in vitro

AIM

To induce apoptosis of human cultured hepatocellular carcinoma (HCC) cell line SMMC-7721 by GnRH-analog alarelin, and to provide the experimental evidence for GnRH-A in endocrinotherapy of HCC.

METHODS

MTT assay, transmission electron microscopy and DNA end labeling method were used to identify apoptosis of cultured human hepatocellular carcinoma cells treated by alarelin.

RESULTS

SMMC-7721 cell line was induced by alarelin in 10-9 mol/L concentration. The induction of apoptosis was dose-effect dependent. Under electron microscopy we could identify the earlier and later stage of apoptotic cells, and chromatin condensation, as well as apoptosis body formation. DNA end labeling method showed that alarelin could induce apoptosis of HCC cells (0.29±0.06 vs 0.11±0.03), and their apoptosis body formations were observed. Compared with control group, the TUNEL index was increased significantly in alarelin treated groups (P <0.05).

CONCLUSION

GnRH-analog alarelin can induce apoptosis of cultured human HCC cell line SMMC-7721, and it plays a potential role in the treatment of human HCC.

Experimental study on therapeutic effect of in vivo expression of Cell I-Hep II recombinant polypeptide of fibronectin on murine H22 hepatocellular carcinoma

AIM: To investigate the inhibitory effect of in vivo expression of expressing plasmid pCH510 of recombinant fibronectin polypeptide (CH50) on hepatocellular carcinoma and the improved therapeutic effect of pCH510 in combination with chemotherapeutic agents and Hsp70-H22 hepatocarcinoma antigen peptide on tumor.

METHODS: Mice were inoculated with H22 hepatocarcinoma cells. The chemotactic effect of the expression of plasmid pCH510 on immunocytes was observed after in vivo transfection, tissue slicing and HE staining. Inhibitory effect of transfection with pCH510 on murine tumor originated from different inoculative doses was observed. The inhibitory effect of immediate transfection with pCH510 after chemotherapy on tumor was compared with that of transfection 5 days after chemotherapy. The change of function and amount of mouse peritoneal macrophages and the peripheral blood immunocytes resulted from administration of chemotherapeutic agents were detected. The peptides mixture was prepared from H22 hepatocarcinoma cells. pCH510 + Hsp70-H22 antigen peptides were injected into tumor-bearing mice with or without chemotherapy, to observe the inhibitory effects on tumor.

RESULTS: At the tumor tissue site injected with pCH510, there were a great number of immunocytes which mainly were macrophages, lymphocytes and neutrophils. Transfection of plasmid pCH510 inhibited significantly the murine tumor induced by different inoculative doses. The inhibitory effect was negatively correlated with the inoculative dose. The therapeutic effect was not improved by immediate transfection with pCH510 after chemotherapy, but was significantly improved by transfection with pCH510 5 days after chemotherapy. Chemotherapeutic agent decreased the number of immunocytes and suppressed their activation in vivo. After injection of drug, the amount of immunocytes was the lowest from d 1 to d 3 and returned to normal level on the 10^th day. Transfection with plasmid pCH510 alone could inhibit tumor induced by the inoculation with 10⁴ H22 cells. The tumor originated from the inoculation with 10⁵ H22 cells was inhibited by pCH510 + Hsp70-H22 antigen peptides and that from the inoculation with 10⁶ H22 cells was inhibited by pCH510 + Hsp70-H22 antigen peptides in combination with chemotherapeutic agents.

CONCLUSION: In vivo expression of pCH510 recruits immune cells, inhibits tumor growth, and enhances the efficacy of chemotherapy. But the proper timing of combining chemotherapy with pCH510 must be taken into great account. The synergism of pCH510 and Hsp70-H22 peptides can improve the efficacy, which could be further enhanced if they are used following chemotherapy. Chemotherapeutic agent + pCH510 + Hsp70-H22 peptides is a promising therapeutic approach of combination treatment of tumor.