Natural and synthetic compounds for glioma treatment based on ROS-mediated strategy.

Glioma is the most frequent and most malignant tumor of the central nervous system (CNS)，accounting for about 50% of all CNS tumor and approximately 80% of the malignant primary tumors in the CNS. Patients with glioma benefit from surgical resection, chemo- and radio-therapy. However these therapeutical strategies do not significantly improve the prognosis, nor increase survival rates owing to restricted drug contribution in the CNS and to the malignant characteristics of glioma. Reactive oxygen species (ROS) are important oxygen-containing molecules that regulate tumorigenesis and tumor progression. When ROS accumulates to cytotoxic levels, this can lead to anti-tumor effects. Multiple chemicals used as therapeutic strategies are based on this mechanism. They regulate intracellular ROS levels directly or indirectly, resulting in the inability of glioma cells to adapt to the damage induced by these substances. In the current review, we summarize the natural products, synthetic compounds and interdisciplinary techniques used for the treatment of glioma. Their possible molecular mechanisms are also presented. Some of them are also used as sensitizers: they modulate ROS levels to improve the outcomes of chemo- and radio-therapy. In addition, we summarize some new targets upstream or downstream of ROS to provide ideas for developing new anti-glioma therapies.

X-rays induced IL-8 production in lung cancer cells via p38/MAPK and NF-κB pathway.

PURPOSE: It is reported inflammatory cytokine interleukin-8 (IL-8) could predict radiation-induced lung toxicity (RILT). RILT is believed to be a consequence of a cascade of cytokine production. It is considered that vascular endothelial cell and macrophages are the mainly source of cytokines. This study was investigated the production of IL-8 from cancer cells induced by X-rays may involve in the radiation-induced inflammation. MATERIALS AND METHODS: We analyzed IL-8 in human lung cancer cell lines after expose to X-rays, and we also detect IL-8 in HUVEC cells and THP1 cells as endothelial cell and macrophage model to identify the change in normal cells after expose. Furthermore, we added the inhibitors to the culture with or without radiation to identify the role of MAPK and NF-κB pathways on the radiation-induced secretion of IL-8. RESULTS: Radiation could induce IL-8 production both in non-lung cancer cells (HUVECs and THP1 cells) and in lung cancer cells (A549 cells, H446 cells, PC-9 cells). Simultaneously, radiation activated p38/MAPK and NF-κB signal pathways in lung cancer cells. Moreover, p38/MAPK inhibitor SB203580 and NF-κB inhibitor BAY11-7082 could block the IL-8 up-regulated by X-rays but JNK inhibitor SP600125, ERK inhibitor U0126, ROS Scavenger NAC could not inhibit this phenomenon. CONCLUSIONS: X-rays could induce IL-8 production in lung cancer cells, which may be related to the activation of p38/MAPK and NF-κB signaling pathway, providing a new point for elucidating the mechanism of radiation pneumonitis.

The role of aldehyde dehydrogenase 1A1 in B-cell non-Hodgkin's lymphoma.

Previously we showed that aldehyde dehydrogenase 1A1 (ALDH1A1) is a new mediator for resistance of DLBCL to CHOP and a facility predictor of clinical prognosis. In the present study, knockdown and inhibitor of ALDH1A1 were applied to identify the role of ALDH1A1 in Raji cells. CCK-8 and clone formation assay were applied to determine the CHOP sensitivity and clone formation ability. Caspase colorimetric assay and Annexin V/FITC staining was performed to determine the degree of apoptosis. Western blot analysis was used to detect the NF-κB/STAT3 signaling proteins and apoptotic-associated proteins. Real-time quantitative PCR (RT-PCR) was used to identify the differential expression of ALDH1A1 between NHL patients and healthy donors. We demonstrated that inhibition of ALDH1A1 increased the sensitivity of Raji cells to CHOP, as indicated by increased cytotoxicity, reduced clonogenicity, activated caspase-3/-9, decreased NF-κB/STAT3 signaling and increased pro-apoptosis signaling, ad increased apoptosis rate. Moreover, we found high ALDH1A1 expression was associated with poor prognosis in NHL patients. Our data revealed the critical role of ALDH1A1 in NHL and provides a theoretical basis for the use of ALDH1A1 inhibitors in NHL patients.

Peptidoglycans promotes human leukemic THP-1 cell apoptosis and differentiation.

The innate immune system coordinates the inflammatory response to pathogens. To do so, its cells must discriminate self from non-self utilizing receptors that identify molecules synthesized exclusively by microbes. Toll- like receptors have a crucial role in the detection of microbial infection in mammals and insects. In mammals, they have evolved to recognize conserved products unique to microbial metabolism. These include lipopolysaccharide (LPS), lipotechoic acids, and peptidoglycans (PGN). We show here that TLRs, including TLR2, are expressed on the THP-1 human leukemia cell line. Activation of TLR2 signaling in THP-1 by PGN induces the synthesis of various soluble factors and proteins including interleukin-1ß, interleukin-8 and TNF-α and apoptosis of THP-1 with PGN dose and time dependence. Moreover , in this study we show that PGN induces apoptosis of THP-1 cells in a TNF-α-dependent manner. These findings indicate that TLR2 signaling results in a cascade leading to tumor apoptosis and differentiation, which may suggest new clinical prospects using TLR2 agonists as cytotoxic agents in certain cancers.

Spaceflight alters the gene expression profile of cervical cancer cells.

Our previous study revealed that spaceflight induced biological changes in human cervical carcinoma Caski cells. Here, we report that 48A9 cells, which were subcloned from Caski cells, experienced significant growth suppression and exhibited low tumorigenic ability after spaceflight. To further understand the potential mechanism at the transcriptional level, we compared gene expression between 48A9 cells and ground control Caski cells with suppression subtractive hybridization (SSH) and reverse Northern blotting methods, and analyzed the relative gene network and molecular functions with the Ingenuity Pathways Analysis (IPA) program. We found 5 genes, SUB1, SGEF, MALAT-1, MYL6, and MT-CO2, to be up-regulated and identified 3 new cDNAs, termed B4, B5, and C4, in 48A9 cells. In addition, we also identified the two most significant gene networks to indicate the function of these genes using the IPA program. To our knowledge, our results show for the first time that spaceflight can reduce the growth of tumor cells, and we also provide a new model for oncogenesis study.

Immunogenicity and efficacy of a DNA vaccine encoding a human anti-idiotype single chain antibody against nasopharyngeal carcinoma.

G22, an anti-idiotype single chain antibody screened from human nasopharyngeal carcinoma phage anti-idiotype antibody library, has been already identified by He et al. G22 DNA vaccine was produced by cloning G22 gene and inserting the cloned gene into pcDNA3.1. To investigate the immunogenicity of pcDNA3.1-G22, C57BL/6 mice were immunized with the vaccine, pcDNA3.1 and PBS individually and the antibody response, T cell phenocyte at the 15th, 22th, 29th, 36th day after the last immunity were detected. In the tumor protection experiment, the immunized mice were then challenged with CMT-93-G22 cells or CMT-93-mock cells. The tumor size and the survival time of the animals were compared between these groups. The results showed that DNA vaccine pcDNA3.1-G22 could raise G22-specific humoral and cellular immune responses. Furthermore, pcDNA3.1-G22 could prolong the survival time and lessen the tumor size of the CMT-93-G22-bearing mice but had no protection effect on the mice attacked by CMT-93-mock cells. These results were expected to lay foundation for further studies on the clinical application of pcDNA3.1-G22 DNA vaccine.

Gamma-aminobutyric acid promotes human hepatocellular carcinoma growth through overexpressed gamma-aminobutyric acid A receptor alpha 3 subunit.

AIM: To investigate the expression pattern of gamma-aminobutyric acid A (GABAA) receptors in hepatocellular carcinoma (HCC) and indicate the relationship among gamma-aminobutyric acid (GABA), gamma-aminobutyric acid A receptor alpha3 subunit (GABRA3) and HCC. METHODS: HCC cell line Chang, HepG2, normal liver cell line L-02 and 8 samples of HCC tissues and paired non-cancerous tissues were analyzed with semiquantitative polymerase chain reaction (PCR) for the expression of GABAA receptors. HepG2 cells were treated with gamma-aminobutyric acid (GABA) at serial concentrations (0, 1, 10, 20, 40 and 60 micromol/L), and their proliferating abilities were analyzed with the 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell doubling time test, colon formation assay, cell cycle analysis and tumor planted in nude mice. Small interfering RNA was used for knocking down the endogenous GABRA3 in HepG2. Proliferating abilities of these cells treated with or without GABA were analyzed. RESULTS: We identified the overexpression of GABRA3 in HCC cells. Knockdown of endogenous GABRA3 expression in HepG2 attenuated HCC cell growth, suggesting its role in HCC cell viability. We determined the in vitro and in vivo effect of GABA in the proliferation of GABRA3-positive cell lines, and found that GABA increased HCC growth in a dose-dependent manner. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRA3-expressing HepG2 cells, but not GABRA3-knockdown HepG2 cells. This means that GABA stimulates HepG2 cell growth through GABRA3. CONCLUSION: GABA and GABRA3 play important roles in HCC development and progression and can be a promising molecular target for the development of new diagnostic and therapeutic strategies for HCC.

Autoantibodies as potential biomarkers for nasopharyngeal carcinoma.

Autoantibody signatures, as new biomarkers, may improve the early detection of nasopharyngeal carcinoma (NPC). We constructed a T7 phage cDNA library from mixed NPC tissues, and we isolated 31 tumor-associated proteins using biopan enrichment techniques with sera from NPC patients and from healthy population. DNA sequence analysis showed that among 31 phage-displayed proteins, 22 have sequence identity with known or putative tumor-associated proteins. The results of immunochemical reactivity of patients' sera with phage-expressed proteins showed enrichment in the number of immunogenic phage clones in the biopanning process and also confirmed that antibodies were present in the sera of patients but not in the sera of healthy donors. The autoantibody against phage-expressed protein MAGE, HSP70, Fibronectin, and CD44 measured by ELISA had greater predictive value than that against EBNA-1, respectively. The antibody levels against MAGE in sera positively correlated with the clinical stages of NPC, and the antibody levels against other three proteins partly correlated with the clinical stages of NPC. Our studies suggested that the autoantibodies against tumor-associated antigens in the sera of NPC patients could be used as a screening test for NPC. Studies of the corresponding proteins may have significances in tumor biology, novel drug development, and immunotherapy.

[Detection of autoantibodies in the sera of nasopharyngeal carcinoma patients].

OBJECTIVE: To investigate whether there are autoantibodies to nasopharyngeal carcinoma (NPC) in the sera of patients and to find new NPC biomarkers. METHODS: Cell plate of Epstein Barr virus negative NPC cell line CNE1 was prepared, and difference between 32 NPC patient sera and 54 normal sera was analyzed by ELISA. We extracted the total protein of CNE1, and analyzed whether there were specific proteins to react with NPC sera by Western blot. RESULTS: The average absorbance values of serum antibody in NPC patients (0.904+/-0.032) were significantly higher than those of normal serum antibody absorbance values (0.736+/-0.028) (P< 0.01). The analysis with Western blot showed there were positive bands,and some of these were unanimous bands, but the intensity increased, and some of these were new bands compared with the normal sera. These positive bands may be NPC tumor-associated antigens or NPC tumor-specific antigens. CONCLUSION: Autoantibodies that react with NPC exist in the sera of NPC patients, but they do not react with Epstein-Barr virus. It provides the basis to seek the tumor biomarkers in NPC sera.

[Selection and characterization of human scFv antibodies against hepatocellular carcinoma].

AIM: To construct a fully human anti-hepatoma single-chain phage antibody library, select the anti-hepatoma scFv from it and identify its characteristics. METHODS: A fully human scFv-displaying phage library was constructed by using phage antibody library technique in combination with in vitro immunization and EBV transformation. The library was subjected to three rounds of positive and negative cell panning and enrichment and then it was selected by ELISA. The binding specificity of phage antibodies with hepatoma carcinoma cells was confirmed by immunohistochemistry. RESULTS: After scFv genes being cloned into vector Fuse5 and transformed into E.coli MC1061 via electroporation, a phage antibody library containing 1.0 x 10(8) TU (transduced unit) was obtained through tetracycline-resistant screening. After panning, enrichment and testing by ELISA, 3 phage antibody clones reacting more strongly to HepG(2) than QSG-7701 were picked out of 2798 clones. One clone, SA3, was further analysed after DNA sequencing. The results of immunohistochemistry with cultured cells were similar to those of ELISA. SA3 reacted specifically to hepatoma cells in most human hepatoma tissue sections but in few human normal liver tissue sections. The distinction of positive rates is of a great statistical significance. CONCLUSION: A fully human anti-hepatoma scFv fusion phage library has been constructed. ELISA and immunohistochemistry results conform SA3 specifically bind with hepatoma carcinoma cells. The scFv fragment against hepatoma may be further developed and applied in clinical diagnosis and therapy of liver cancer.

BMI-1 autoantibody in serum as a new potential biomarker of nasopharyngeal carcinoma.

BMI-1 is overexpressed in a variety of cancers, which can activate the immune system to produce antibodies in tumor tissues. In this study, we isolated phage expressing BMI-1 protein by screening of a mixture of nasopharyngeal carcinoma (NPC) cDNA T7 phage library and found that the antibody against BMI-1 was elevated in the sera from NPC patients. BMI-1 mRNA was overexpressed at different levels in seven NPC cell lines compared with normal nasopharyngeal epithelial cell line NP69. Histochemistry showed that patient sera were more reactive with BMI-1 than normal sera. Antibody affinity assay using sera from 40 NPC patients and 54 controls showed that BMI-1 antibody was significantly greater in patient sera than in normal controls (patient 0.791 +/- 0.025 and normal 0.488 +/- 0.042; P < 0.001) and the BMI-1 autoantibody be significantly related with the progress of NPC (Benign versus LNPC P=0.001; LNPC versus MNPC P=0.047). Analysis of the results with logistic regression and receiver operating characteristics (ROC) curves showed that BMI-1 antibody was a modest marker for NPC (sensitivity 0.74 and specificity 0.73; AUC = 0.8044). The showed that BMI-1 antibody as a potential marker of NPC may be rational, and could have diagnostic and prognostic value.

[Biological properties of Caski cell lines induced by exposing to the space environment].

OBJECTIVE: To investigate the biological properties of Caski cell lines induced by exposing to the space environment. METHODS: Caski cells were carried in "Shen Zhou IV" airship. After 7 days of spaceflight, cells survived and were monocoloned, and the experimental methods such as cell morphological observation, the cell proliferation assay, flow cytometry cell cycle analysis, the soft agar assay, and tumorigenesis assay were used to analyze cell growth characteristics and malignant phenotypes. RESULTS: Altogether 1440 strains subclonal cell lines were established and 4 strains were screened. Compared with the control group, mutated cells appeared to have multiple cell morphological changes. Strains numbered 44F10 and 17E3 were screened due to their increased cell proliferation and tumorigenesis, and their cell cycles were induced to progress from G(1) to S phase, while strains 48A9 and 31F2 were opposite to 44F10 and 17E3 in cytological events. The average population double time of ground nomal control group, ground simulant control group, strains numbered 44F10, 17E3, 48A9 and 31F2 groups were 56.54, 58.44, 52.96, 51.46, 101.76 and 88.47h, respectively; compared with the control group, the average double time of strains numbered 44F10 and 17E3 was decline, but with no statistical significance. However, compared with the control groups, the average double time of 48A9 and 31F2 was significant increased (P<0.05). The colony formation rates were 9.7%, 9.3%, 14.7%, 12.1%, 0 and 0.1%, respectively, and the difference between the ground control groups and the other groups was significant (P<0.01); 6 groups of above-mentioned Caski cells were inoculated subcutaneously in Babl/c nude mice respectively. Forty-seven days later, the formed tumors in the nude mice were statistically analyzed and tested. The average weight of tumors of the above-mentioned groups was 0.066, 0.066, 0.175, 0.249, 0.011 and 0.018g. The difference between the ground control groups and other groups was significant (P<0.05). CONCLUSION: Spaceflight may affect the physiological characteristics of tumor cells and the variation is complicated.

[Antitumor immune response to cervix carcinoma in mice induced by HPV16 E6 DNA vaccines].

OBJECTIVE: To investigate the effect of HPV16E6 DNA vaccines on inducing the antitumor immune response to cervix carcinoma in vivo. METHODS: We prepared pCB/HPV16E6 DNA vaccines to prevent and treat 615 modle mice transplanted E6 + U14 in vivo respectively. Survival and tumor sizes of all mice were recorded and their lymphnodes and lung's metastases were detected by microscopic observation. The cytotoxicity of the spleen T cells of those mice immuned with HPV E6 DNA vaccines against the E6 U14 and U14 was detected by MTT assay. RESULTS: HPV16 E6 DNA vaccines prevented the transplanted tumor growth effectively in inbred strain mice and cured some tumor-bearing mice (P < 0. 001). Pathological results showed that the number of lymphodes with metastases foci decreased in the preventing group (P < 0.05). HPV16 E6 DNA vaccines induced special and higher cytotoxicity T lymphocytes against the E6 + U14 (P < 0.001). CONCLUSION: HPV16 E6 DNA vaccines can induce antitumor immune protection of the mice against E6 + U14 cells, suggesting that the vaccines may be effective in preventing and treating cervix cancer after an operation.

Transfection of colorectal cancer cells with chemokine MCP-3 (monocyte chemotactic protein-3) gene retards tumor growth and inhibits tumor metastasis.

AIM: To evaluate the possibility of the induction of anti-tumor immune response by transfecting the colorectal cancer cells with chemokine MCP-3 gene. METHODS: Mouse MCP-3 gene was transduced into mouse colorectal cancer cells CMT93 by using of Liposome. G418-resistant clones were selected and the MCP-3 mRNA expression was detected by RT-PCR. The chemotactic activity of MCP-3 in the cell culture supernatant was detected by Chemotaxis assay. The tumorigenicity of wild type CMT93 and CMT93 gene transfectants were detected by in vivo experiments. The immune cell infiltrations in tumor tissue and tumor metastasis were detected histopathologically. RESULTS: MCP-3 mRNA expression was detected by RT-PCR in gene-transfected cells (CMT93/MCP-3), but not in control groups. And MCP-3 secreted in the cell culture supernatant possessed chemotatic activity. The results from in vivo experiments showed that the tumorigenicity of CMT93/MCP-3 had not decreased, but the tumors derived from CMT93/MCP-3 cells grew more slowly than those from CMT93 cells (1.021+/-0.253) cm(2) vs (1.769+/-0.371) cm(2), P<0.05) or CMT93/mock cells (1.021+/-0.253) cm(2) vs (1.680 +/-0.643)cm(2), P<0.05). Histophathological results showed few immune cells infiltrating in the tumor tissue derived from the controls. In the tumor tissue derived from CMT93/MCP-3, infiltrating immune cells increased. In addition, no tumor metastasis was found in all mice inoculated with CMT93/MCP-3 tumor cells. But all mice had tumor metastasis in CMT93 controls and 4 in 5 mice had tumor metastasis in CMT93/mock controls. CONCLUSION: The results suggested that the transfection of chemokine MCP-3 gene could promote the induction of anti-colorectal cancer immunity, but the tumor growth could not be inhibited completely by merely MCP-3 gene transfection.

[Active immunity for anti-colorectal cancer induced by chemokine MCP-3 gene transfection].

BACKGROUND & OBJECTIVE: Chemokines play an important role in the infiltration of immune cells to tumor tissues. Anti-tumor immune response had been elicited in many tumor models by the chemokine gene transfection. The aim of this study was to evaluate the possibility of inducing anti-colorectal cancer active immune response by transfection of mouse colorectal cancer CMT93 cells with chemokine MCP-3 gene. METHODS: Mouse MCP-3 gene was transduced into mouse colorectal cancer cells CMT93 by using of liposome. G418-resistant clones were selected and the MCP-3 mRNA expression was detected by RT-PCR. The chemotactic activity of MCP-3 in the cell culture supernatant was detected by chemotaxis assay. In vivo experiments were performed to observe the tumorigenicity of wild type CMT93 and MCP-3 gene modified tumor cells. The immune cell infiltration in tumor tissues and tumor metastasis were detected histopathologically. RESULTS: RT-PCR detection showed MCP-3 was expressed in MCP-3 gene-transfected G418-resistant clones(CMT93/MCP-3), but not in wild type CMT93. In chemotaxis assay, the results showed that the cell culture supernatant of CMT93/MCP-3 possess obviously chemotactic activity. The chemotactic index of the CMT93/MCP-3 supernatant was 5.57(P < 0.05). The supernatants from the control groups did not possessed the chemotactic activity. In vivo experiments showed that the tumorigenicity of CMT93/MCP-3 had not decreased significantly compared to wild type CMT93, but the tumors grew more slowly from CMT93/MCP-3 than from the controls (P < 0.05). In the tumor tissue from CMT93/MCP-3, obvious infiltrated immune cells were found, and few immune cells infiltrated in the tumor tissue from the controls. In the mice inoculated with CMT93/MCP3 tumor cells, tumor metastasis was inhibited significantly, its metastasis rate was 0(0/7), lower than that of CMT93 (100%, 4/4) and CMT93/mock (80%, 4/5) (P < 0.05). CONCLUSION: Transfection with chemokine MCP-3 gene can induce anti-colorectal cancer active immune response, but the tumor growth cannot be inhibited completely by merely MCP-3 gene transfection.

[Primary characterization and sequence analysis of anti-colorectal cancer phage fusion antibodies].

OBJECTIVE: To identify 5 phage fusion antibodies against colorectal cancer from in vitro immunized phage library and analyze their sequences. METHODS: Cell ELISA, immunohistochemistry, DNA sequencing and computer analysis were employed. RESULTS: Five clones of phage antibodies were tested by cell ELISA, and all of them reacted to human colorectal cancer cell lines, human embryo kidney endothelial cell line and some tumor cell lines, but not to mouse-original cell lines. They also reacted weakly to human hepatic cell lines. The binding specificity of the phage antibodies for colorectal cancer cells was confirmed by immunohistochemistry with cultured cells and colorectal carcinoma and colon tissue sections. They reacted to colorectal carcinoma cell lines, human embryo kidney endothelial cell lines and nasopharyngeal carcinoma cell lines. CH273 reacted specifically to colorectal cancer cells in human colorectal carcinoma sections but not to any of the cells in human colon sections. The 5 clones were further analyzed after their DNA sequencing. The sequences of CH723, CH209 and CHA12 were identical. The lengths of CH273, CH205 and CH723 were 732 bp, 366 bp and 723 bp, respectively. The VDJ regions of CH273, CH205 and CH723 belonged to VH3-30-D1-26-JH3-linker-V1-13-JL2, VH1-46-D6-13-JH3 and VH3-30-D1-26-JH3-linker-L2-J kappa 2, respectively. CONCLUSIONS: Phage antibodies binding to colorectal tissues and cells are confirmed, on which human anti-tumor ScFv and VH fragments may be further developed and applied to clinical therapy.

Expression of B7 costimulation molecules by colorectal cancer cells reducestumorigenicity and induces anti-tumor immunity.

AIM:To study the tumorigenicity of colorectal cancer cells transfected with B7 gene and the anti-tumor immunity induced by B7 gene modified colorectal cancer cells.METHODS:B7 gene was transfected into mouse colon cancer cell line CMT93.The transfectants were selected in DMEM containing 800mg/L G418, and B7 molecules were detected by immunohistochemistry.Experiments in vivo include: (1)5X10(6) B7(+) CMT93 cells were inoculated into the back of C57BL/6 mice subcutanously to determine their tumorigenicity (n = 4). As control, wild type CMT93 cells were inoculated the same as the experimental group (n= 3). (2) The mice primed by B7(+) CMT93 cells whose tumors vanished were rechallenged with wild type CMT93 to observe the immune protection of these mice against the wild type CMT93 (n = 4). Non-primed 4 native mice inoculated with wild type CMT93 were used as control.With in vivo cytotoxicity assay, the mice were immunized with B7 (+) CMT93 or the wild type CMT93 by intraperitoneal injection (n = 4X2). The spleen cells and the abdominal cavity infiltrating lymphocytes were obtained and cultured for two days. Cytotoxicity of these cells against the B7 gene modified or wild type CMT93 was detected by MTT assay.RESULTS:B7 high expression clones were obtained after the transfection of the B7 gene into CMT93 cells by electroporation. Immunohistochemistry results showed mainly membrance staining and partly cytoplasm staining in B7 gene transfected CMT93 cells. in vivo experiments: (1)After the inoculation of the B7(+) CMT93 cells in the back of C57BL/6 mice, they lost their tumorigenicity greatly (P < 0.01). All the small tumors growing in the early period in the experimental group vanished in one month, and the tumors in control group grew progressively. (2) No tumors were found in all 4 mice primed by B7(+) CMT93 cells after they were rechallenged with wild type CMT93. In the control group all mice had grown tumors (P < 0.05). In vitro cytotoxicity assay, the CTLs induced by B7(+) CMT93 had a higher cytotoxity against the wild type CMT93 than that induced by wild type CMT93 (P < 0.05), and the cytotoxity of CTLs induced by B7(+) CMT93 against B7(+) CMT93 cells was higher than that against wild type CMT93 cells (P < 0.05).CONCLUSION:The results suggest that the expression of costimulation B7 molecules by colorectal cancer cells can decrease their tumorigenicity greatly, and the B7 molecule can augment the activation of the CTLs against colorectal cancer, and it plays an important role in CTL effector function as well.

Radioimmunoimaging of colorectal cancer using (99m)Tc labeled monoclonal antibody.

AIM:To determine whether Hb3 and its fragment F(ab')(2) have practical value in radioimmunoimaging of colorectal cancer.METHODS:Intact Hb3 was purified by hydroxylapatite chromatography.The fragment F(ab') (2) was prepared by cold digestion and purified as intact Hb3.Hb3 and its fragment F(ab') (2) were labeled with 99mTc by direct labeling method using SnCl(2) as reducing agent. The radioactive doses ranged from 15 to 40 mCi.The imaging was accomplished by single photon emission computered tomograph (SPECT) with imaging time ranging from 2.5 to 48 hours. In this study, 10 patients were selected. Among them, 7 were administered with intact Hb3, and 3 with F(ab') (2) fragment. All the patients were diagnosed as having colorectal adenocarcinoma.RESULTS:After purification, intact Hb3 and its fragment F(ab') (2) were fit for radioimmunoimaging. The percentage of labeling of (99m)Tc to Hb3 or F(ab') (2) was 80.6%-91.5%. Among the 10 patients, 3 of 7 patients administered with intact Hb3 had positive scans, the other 4 had negative scans, and 2 of 3 patients administered with F(ab') (2)had positive scans, the other 1 had negative scans.CONCLUSION:The results showed that both intact Hb3 and its F(ab') (2) have some practical value in radioimmunoimaging of colorectal cancer, and the effects of imaging with F(ab') (2) was better than that with intact Hb3.