Identification of tumor associated single-chain Fv by panning and screening antibody phage library using tumor cells

Monoclonal antibodies MC3 and MC5 can be used as a tool for screening colorectal cancer

MC3 and MC5 are both colorectal cancer-specific MAbs previously prepared in our laboratory that can detect colorectal cancer with high sensitivity and specificity. Thus far the distribution of MC3-Ag and MC5-Ag in colorectal cancer remains largely unknown. In the present study, we have firstly found that the expression of MC3-Ag and MC5-Ag was higher in moderate-differentiated and poor-differentiated colorectal cancer tissue than that in well-differentiated colorectal cancer tissue by immunohistochemistry. The expression of MC5-Ag in colorectal cancer tissue without metastasis was found to be significantly less than that in tissue accompanied with metastasis. However, the expression of MC3-Ag in colorectal cancer tissue without metastasis was found similar to that in tissue accompanied with metastasis. The results showed that MC3-Ag and MC5-Ag might play important roles in colorectal carcinogenesis and that MC3 and MC5 could be used as a tool for screening colorectal cancer.

Isolation of specific and biologically active peptides that bind cells from patients with acute myeloid leukemia (AML)

Purpose

In a departure from conventional strategies to improve treatment outcome for myeloid malignancies, we report the isolation of leukemia-specific peptides using a phage display library screened with freshly obtained human myeloid leukemia cells.

Results

A phage display library was screened by 5 rounds of biopanning with freshly isolated human AML cells. Individual colonies were randomly picked and after purification, biologic activity (growth and differentiation) on fresh AML cells was profiled. Ten peptides were synthesized for further biological studies. Multiple peptides were found to selectively bind to acute myeloid leukemia (AML) cells. The peptides bound to leukemia cells, were internalized and could induce proliferation and/or differentiation in the target patient cells. Two of the peptides, HP-A2 and HP-G7, appeared to have a novel mechanism of inducing differentiation since they did not cause G1 arrest in cycling cells even as the expression of the differentiation marker CD11b increased.

Conclusion

Peptide induced differentiation of leukemia cells offers a novel treatment strategy for myeloid malignancies, whereas their ability to induce proliferation could be harnessed to make cells more sensitive to chemotherapy. Conceptually, these leukemia specific peptides can also be used to refine diagnosis, document minimal residual disease, and selectively deliver toxins to malignant cells.

Bird's-eye view on gastric cancer research of the past 25 years

This paper provides a bird's-eye view of our 25-year research work on gastric cancer, including both exploration of pathogenesis and preclinical or clinical applications of diagnosis and treatment. Although there have been achievements and reasons for applause, there are, nonetheless, more failings and teachings. Some problems that we experienced 25 years ago are still problems we have to face today. We are absolutely not singing the same old tune. Looking back makes us wiser and our way smoother. Although it is a long and arduous way to further study gastric cancer, we are willing to devote ourselves to it.

Clinical efficacy and mechanism of oxaliplatin in treating human gastric carcinoma

AIM

To evaluate the therapeutic effect of oxaliplatin on human gastric carcinoma and to explore the mechanisms.

METHODS

22 cases of stage IV gastric carcinoma patients received 4-6 (mean 4.6) cycles of first line combined chemotherapy with oxaliplatin (oxaliplatin 85 mg/m², ivgtt, 1 h, d 1; leukovorin 200 mg/m², iv, gtt, 1 h, d 1-5; 5-FU 300 mg/m², iv, d 1-2; 5-FU, continuously iv, gtt, 48 h; 1 cycle/2w). Response rate, progression-free survival (PFS), total survival time, toxic side effects were evaluated. The inhibitory effect of oxaliplatin on human gastric cell line SGC-7901 was calculated by MTT and IC50 was measured. Flow cytometry and TUNEL were applied to evaluate the apoptosis of cell line induced by the drug. The expression of caspase-3 mRNA was detected by RT-PCR.

RESULTS

Total response (complete and partial) occurred in 9 (40.9%) patients. Mean PFS was 4.2 months and mean total survival time was 7.2 months. Cumulative neurotoxicity (all grade I-II), vomiting and diarrhea, myelosuppression appeared in 93.5%, 20%, 32.9% of the patients, respectively. Apoptosis index was elevated after incubating with 1 mmol/L oxaliplatin for 30 min, but without statistic significance (P>0.05), but was much higher both by flowcytometry and TUNEL with statistical significance (P<0.05) after incubating with 1 mmol/L oxaliplatin for 2 days. Caspase-3 mRNA expression was elevated in oxaliplatin treated cells and correlated with apoptosis induced by the drug.

CONCLUSION

Oxaliplatin is effective and well-tolerated on human advanced gastric carcinoma. Oxaliplatin could significantly inhibit the growth of human gastric cell line SGC-7901, inducing caspase-3 mRNA expression and cell apoptosis.

Development of an oral DNA vaccine against MG7-Ag of gastric cancer using attenuated salmonella typhimurium as carrier

AIM: To develop an oral DNA vaccine against gastric cancer and evaluate its efficacy in mice.

METHODS: The genes of the MG7-Ag mimotope and a universal Th epitope (Pan-DR epitope, PADRE) were included in the PCR primers. By PCR, the fusion gene of the two epitopes was amplified. The fusion gene was confirmed by sequencing and was then cloned into pcDNA3.1 (+) plasmid. The pcDNA3.1 (+)-MG7/PADRE was used to transfect an attenuated Salmonella typhimurium. C57BL/6 mice were orally immunized with 1 × 10⁸ cfu Salmonella transfectants. Salmonella harboring the empty pcDNA3.1 (+) plasmid and phosphate buffer saline (PBS) were used as negative controls. At the 6th week, serum titer of MG7-Ag specific antibody was detected by ELISA. At the 8th week cellular immunity was detected by an unprimed proliferation test of the spleenocytes by using a [³H]-thymidine incorporation assay. Ehrlich ascites carcinoma cells expressing MG7-Ag were used as a model in tumor challenge assay to evaluate the protective effect of the vaccine.

RESULTS: Serum titer of antibody against MG7-Ag was significantly higher in mice immunized with the vaccine than that in control groups (0.841 vs 0.347, P < 0.01; 0.841 vs 0.298, P < 0.01), while in vitro unprimed proliferation assay of the spleenocytes showed no statistical difference between those three groups. Two weeks after tumor challenge, 2 in 7 immunized mice were tumor free, while all the mice in the control groups showed tumor formation.

CONCLUSION: Oral DNA vaccine against the MG7-Ag momitope of gastric cancer is immunogenic. It can induce significant humoral immunity against tumor in mice, and the vaccine has partially protective effects.

Expression of 1A6 gene and its correlation with intestinal gastric carcinoma

AIM: To investigate the expression of 1A6 gene in the lesions during the development of intestinal gastric carcinoma.

METHODS: One hundred and thirty-six cases of intestinal metaplasia (IM) from surgical resections and biopsy were classified by mucous staining. Expression of 1A6 in all cases was detected using immunohistochemical S-P method.

RESULTS: The positive rates of 1A6 in normal and superficial gastritis (SG), severe atrophic gastritis (SAG), type I, II, III IM, dysplasia (Dys) and intestinal gastric carcinoma (IGC) were 12.2%, 16.7%, 7.1%, 22.6%, 47.8%, 46.9% and 60.8%, respectively. A significant difference among type III IM and SG, SAG, type I and II IM was found (P < 0.01), the difference between type III and Dys, IGC being not significant.

CONCLUSION: As a new tumor-related gene, expression of 1A6 may be an effective parameter to predict the malignant transformation of precancerous lesion to gastric carcinoma.