Pharmacokinetics of radioimmunotherapeutic agent of direct labeling mAb 188Re-HAb18

Study of Apoptosis Induced by 188Re-DTPA-DG in MCF-7 Breast Carcinoma and A549 Pulmonary Carcinoma Cells

OBJECTIVE

To evaluate apoptosis induced by rehenium-188-labeled diethylenetriamine pentaacetic acid-glucosamine (188Re-DTPA-DG) in MCF-7 breast carcinoma cells and A549 pulmonary carcinoma cells.

METHODS

Through the use of flow cytometry (FCM) with CBA software to detect apoptosis, cells of both the MCF-7 and A549 cell lines were divided into groups exposed to 188Re-DTPA-DG, 188Re-perrhenate (188ReO4-), and saline, respectively. The first two groups were further divided into subgroups on the basis of their exposure to radioactivity at 37, 55.5, or 74 kBq/mL, with the saline-exposed group divided into three corresponding subgroups. Each subgroup was introduced into 5 replicate wells of a culture plate, and the morphology of the cells in each well was determined by flow cytometry at 6-hour intervals for 18 hours. In order to determine the affinity of 188Re-DTPA-DG for tumor tissue, the biodistribution of the radiolabeled agent was assessed in breast tumor-bearing nude mice.

RESULTS

Change in morphology of the cell nucleus was more evident in the 188Re-DTPA-DG-treated than in the 188ReO4--treated group, and no change in nuclear morphology was seen in the saline-exposed group. The study data suggested that there was a greater ratio of apoptotic to nonapoptotic cells among the 188Re-DTPA-DG-treated than among the 188ReO4--treated or saline-exposed cells (p<0.01), and a greater change in cell-nuclear morphology in the 188Re-DTPA-DG-treated than in the 188ReO4--treated cells. Furthermore, 188Re-DTPA-DG had a more significant apoptosis-inducing effect on both MCF-7 and A549 cells than did 188ReO4-. The biodistribution study in tumor-bearing nude mice showed that the concentration of 188Re-DTPA-DG in tumor tissue was much higher than in normal tissue, that 188Re-DTPA-DG was rapidly cleared from the blood, and that the main route of its clearance was via the kidneys.

CONCLUSIONS

188Re-DTPA-DG has a significant apoptotic effect on carcinoma cells. 188Re-DTPA-DG is an effective radiopharmaceutical for intratumoral radiation therapy.

Preparation and functional characterization of the monoclonal antibody HAb18Gedomab1

AIM: To obtain mouse anti-human monoclonal antibodies against recombinant extracellular domain of HAb18G (HAb18Ged), and to analyze and identify its character and biological function.

METHODS: Balb/c mice were immunized with HAb18Ged. Hybridoma cell was screened by cell fusion and subcloning approach. The monoclonal antibody in the ascites was purified by ion exchange chromatography and was identified by fluorescence-activated cell sorting analysis (FACs) and immunohistochemistry. Gelatin zymography and collagenase type I zymography were used to analyze the effects of HAb18Gedomab1 on activation and production of matrix metalloproteinase (MMPs); Matrigel-boyden degradation chamber method was used to evaluate the infiltrative cells ratio.

RESULTS: A hybridoma cell HAb18Gedomab1 stably secreting anti-HAb18Ged monoclonal antibody was obtained. The titer of this McAb in ascites was 1:10⁶. The purity of the McAb was higher than 90%. The McAb belonged to IgG1 subclass. HAb18Gedomab1 showed high specificity and affinity to the antigen of FHCC-98 cell membrane and the tissue of hepatocellular carcinoma. The McAb induced production and activation of MMP-2, MMP-9, MMP-1 and MMP-8 in mouse fibroblast cells (3T3), and also promoted the degradation of reconstituted basement membrane.

CONCLUSION: HAb18Gedomab1 can bind specifically to HAb18Ged protein. The McAb can also induce production and activation of MMPs and promote the degradation of reconstituted basement membrane.

Construction of a universal expression vector for human-mouse chimeric Fab antibody and expression of chimeric Fab antibody against human hepatoma associated antigen HAb18G

AIM: To construct a universal expression vector for human-mouse chimeric Fab antibody and to use it for construction and expression of human-mouse chimeric Fab antibody against human hepatoma associated antigen HAb18G.

METHODS: Human IgG3 CH1 and Cκgenes were amplified by PCR with Specific primers and cloned into vector pComb3 to construct a human-mouse chimeric Fab antibody universal expression vector pComb3C. Then, the V_κ and V_H genes of mAb HAb18 were amplified by PCR using Specific primers and cloned into the expression vector pComb3-cFab. After gIII was cut away, the secretory expression vector pComb3C/cFab containing chimeric Fab antibody gene of HAb18 was constructed and transfected into competent E. Coli. And then, the antibody induction expression by IPTG was conducted. The locaeization of expression products was detected by sandwich ELISA. Finally, The expression product was purified by affinity chromatography and the antigen-binding Specificity and affinity of the expression product were tested by ELISA and immunofluorescence staining.

RESULTS: Human IgG3 CH1 and Cκgenes were correctly inserted into vector pComb3 by nucleotide sequencing and restriction endonucleases digestion, with the size of 324bp and 333 bp, and chimeric Fab gene of mAb HAb18 was successfully constructed and expressed in E. Coli. The molecular mass of expression product was about 45 ku. It was mainly located in the periplasm. The results of ELISA and immunofluorescence staining showed that the expressed chimeric Fab contained human antibody fragment and had Specific antigen-binding activity, and its affinity was about 10% of parental antibody HAb18.

CONCLUSION: We have successfully constructed a universal expression vector for human-mouse chimeric Fab antibody. Based on this result, a small molecule of chimeric Fab antibody against human hepatoma is prepared, which lays a foundation for its further application into diagnosis and therapy of human hepatocellular carcinoma.

Inhibitory effects of antisense RNA of HAb18G/CD147 on invasion of hepatocellular carcinoma cells in vitro

AIM: To study the inhibitory effects of antisense RNA of HAb18G/CD147 on invasion of hepatocellular carcinoma (HCC) cells in vitro.

METHODS: Antisense RNA of HAb18G/CD147 vector PCI-asHAb18G was constructed by reversely inserting HAb18G/CD147 cDNA to eukaryotic expression vector PCI-neo. The HCC cell line HHCC was transfected by PCI-asHAb18G via cation liposome. Expression of HAb18G/CD147 of transfected cells selected by G418 (geneticin) was observed by immuno-histochemical SP staining and FACS (fluorescence activated cell sorting). Gelatin zymography was used to determine the effect of PCI-asHAb18G on reducing secretions of MMP-2 and MMP-9 of the transfected cells. Boyden chamber was employed to test the invasion of HCC cells in vitro.

RESULTS: The construction of antisense RNA vector PCI-asHAb18G was verified correct by partial nucleotide sequencing and restricted endonuclease digestion. The expression of HAb18G/CD147 in transfected HHCC was inhibited by PCI-asHAb18G. Secretions of MMP-2 and MMP-9 of transfected HHCC were reduced and the invasion of transfected HHCC was inhibited compared to HHCC, respectively.

CONCLUSION: Invasion of HCC cells can be inhibited by antisense RNA of HAb18G/CD147. HAb18G/CD147 may be used as a potential target of drugs for anti-invasion and metastasis of HCC.

Effects of HAb18G/CD147 antagonistic peptides on invasion and metastasis of HCC

AIM: To obtain the antagonistic peptides that have effect to prevent metastasis of Hepatocellular Carcinoma(HCC).

METHODS: Nine pieces of high affinity peptides (AP-1-AP-9) were obtained by pure HAb18G/CD147 antigen to panning phage displayed random peptide library. MTT assay was used to test toxicity of AP-1-AP-9 on human hepatocellular carcinoma cell (HHCC); Gelatin zymogram was used to analyze the effects of AP-1-AP-9 on activation and production of matrix metalloproteinase (MMPs); Matrigel-boyden chamber method was used to evaluate inhibitory abilities of AP-1-AP-9 on tumor cell invasion and metastasis; Inhibitory effect of AP-1-AP-9 on HHCC adhesion to extracellular matrix protein and fb cells were investigated. The influences of AP-1-AP-9 on HHCC chemotaxis migration were also tested.

RESULTS: AP-1-AP-9 has no toxicity on HHCC; AP-1, AP-6 and AP-9 could inhibit production and activation of MMP-2; the amounts of infiltrative cells in AP-1, 3, 6, 7, 8, 9 experimental groups are significantly less than that in control group (P < 0.05), and inhibition rate was 78.22%, 90.1%, 62.83%, 56.44%, 68.32%, 81.19%, respectively; AP-1-AP-9 had no effects on HHCC adhesion to matrigel and fibronectin (FN), whereas AP-3 and AP-9 could inhibit HHCC adhesion to collagen Ⅳand laminin(LN), AP-1, AP-6 and AP-9 could inhibit HHCC adhesion to fb. AP-6 could inhibit chemotaxis migration of HHCC with the inhibitory rate of 54% without statistical significance (P > 0.05).

CONCLUSION: HAb18G/CD147 antagonistic peptides (AP-1-AP-9) have inhibitory effects on many aspects or steps associated with metastasis of HCC, which provides avenue to explore medication for preventing metastasis of HCC.

Current treatment for liver metastases from colorectal cancer

The liver is the commonest site of distant metastasis of colorectal cancer and nearly half of the patients with colorectal cancer ultimately develop liver involved during the course of their diseases. Surgery is the only therapy that offers the possibility of cure for patients with hepatic metastatic diseases. Five-year survival rates after resection of all detectable liver metastases can be up to 40%. Unfortunately, only 25% of patients with colorectal liver metastases are candidates for liver resection, while the others are not amenable to surgical resection. Regional therapies such as radiofrequency ablation and cryotherapy may be offered to patients with isolated unresectable metastases but no extrahepatic diseases. Hepatic artery catheter chemotherapy and chemoembolization and portal vein embolization are often used for the patients with extensive liver metastases but without extrahepatic diseases, which are not suitable for regional ablation. For the patients with metastatic colorectal cancer beyond the liver, systemic chemotherapy is a more appropriate choice. Immunotherapy is also a good option when other therapies are used in combination to enhance the efficacy. Selective internal radiation therapy is a new radiation method which can be used in patients given other routine therapies without effects.