Enantioselectivity in the toxicological effects of chiral pesticides: A review

As a special category of pesticides, chiral pesticides have increased the difficulty in investigating pesticide toxicity. Based on their usage, chiral pesticides can be divided into insecticides, herbicides, and fungicides. Over the past decades, great efforts have been made on elucidating their toxicological effects. However, no literature has reviewed the enantioselective toxicity of chiral pesticides since 2014. In recent years, more chiral pesticides have been registered for application. As such, huge research progresses have been achieved in enantioselective toxicity of chiral pesticides. Generally, more researches have remedied the knowledge gap in toxicological effects of old and new chiral pesticides. And the toxicological endpoints being evaluated have become more specific rather than centering on basic toxicity and target organisms. Besides, the underlying mechanisms accounting for the enantioselectivity in toxicological effects of chiral pesticides have been discussed as well. All in all, this review provides the critical knowledge for risk assessments, and help to drive the green-technology of single- or enriched-enantiomer pesticides and formulation of relevant laws and regulations.

The Expression of PRL-3 Correlates With Chromosomal Instability in Colon Cancer and Thyroid Cancer

Background: Phosphatase of regenerating liver (PRL-3) promotes cell invasiveness, but its role in genomic integrity remains unknown. We have reported that PRL-3 recruits to telomeric DNA by RAP1/TRF2 protein. Overexpression of PRL-3 in colon cancer cells and primary fibroblasts promotes structural abnormalities of telomere, telomere deprotection, DNA damage response, chromosomal instability. Aim: To substantiate the previous results and further assess the physiologic relevance of PRL-3 in tumorigenesis, also to explore the prediction role PRL-3 in clinical patients. We detected the expression of PRL-3, telomere length, H3K9me and p-H2AX in the colon cancer and thyroid cancer samples. Methods: We collected 273 colorectal cancer patients and stained with PRL-3 antibody and counterstained with HE. Semiquantitative scoring was performed. Microscopic analysis was done by 2 of the authors. Tissues-chips were obtained from Alenabio (Th802a, thyroid). Results: We retrospectively analyzed a cohort of colorectal cancer tissues (n = 269) stained with anti-PRL-3 (clone 3B6). Although the majority of mitotic cells were bipolar, more multipolar mitoses, an indicator of chromosomal missegregation and chromosomal instability, was observed in PRL-3 positive tissues than in negative tissues (Fig 1A). Also in the PRL-3 positive tissues, more anaphase bridges were detected ( Fig 1A ). These results suggest that PRL-3 levels positively correlate with chromosomal instability in colon cancer tissues. Next, we analyzed 12 freshly dissected colon cancer tissues, with WI38 control and PRL-3-overexpressing cells as reference samples. We detected varying levels of PRL-3 proteins in these tissues, and the level of stably overexpressed PRL-3 in WI38 cells was comparable to some of these tissues. An inverse correlation between PRL-3 and telomere length was revealed, while PRL-3 showed positive correlations with gamma-H2AX and H3K9me3 ( Fig 1B ). We also performed quantitative FISH (qFISH) analysis of telomere length and immunohistochemical staining of PRL-3 with thyroid tissue chips containing 80 samples. We found decreased telomere staining in adenocarcinoma tissues (n = 40) with positive PRL-3 expression, particularly in those of stage I (n = 23) ( Fig 1C ). No correlation was observed in thyroid adenoma (n = 40) or stage II/III/IV adenocarcinoma (n = 17) ( Fig 1C ). With the same thyroid tissue-chip, we evaluated association between PRL-3 and senescence. In stage I thyroid adenocarcinoma tissues, positive staining of PRL-3 correlated with positive H3K9me3 staining, but such correlation was not observed in thyroid adenoma or Stage II/III/IV adenocarcinoma ( Fig 1D ). Conclusion: These results raise the possibility that PRL-3-promoted telomere deprotection and senescence are early events during the development and progression of cancer. Our results uncover a novel role of PRL-3 in tumor development through its adverse impact on telomere homeostasis.[Figure: see text]

Study of T cell subsets and IL-7 protein expression in HIV-1-infected patients after 7 years HAART

Objective

To study the changes in T cell subsets and IL-7 in HIV-1-infected patients after seven years of highly active antiretroviral therapy (HAART).

Methods

Seventy-five individuals were included in this study (25 with effective HAART, 18 with ineffective HAART, 17 untreated HIV+ patients, and 15 volunteers in the HIV negative control group). The counts of CD4⁺, CD8⁺, CD8/CD38⁺, and CD8/HLADR⁺ T cells as well as the IL-7 protein expression was measured at 5 time points during a period of seven years in patients starting HAART (baseline) and in the HIV negative control group. The expression of CD127 on CD3⁺ T cells was measured by flow cytometry at a single time point (after 7 years) in patients with HAART and was compared with untreated HIV+ patients and the HIV negative control group.

Results

At baseline CD4⁺ T cell counts of HIV-1-infected patients were lower than that in the control group (p < 0.01), whereas the CD8⁺, CD8/HLADR⁺ and CD8/CD38⁺ T cell counts were higher than those in the control group (p <0.01). After seven years of effective HAART, the CD4⁺ T cell counts had increased and the CD8⁺ T cell count had decreased, although not to the normal levels (p < 0.05). Both the CD8/HLADR⁺ and CD8/CD38⁺ T cell counts had gradually approached those of the control group (p > 0.05). In the ineffective HAART group, the CD8/CD38⁺ T cell count had not decreased significantly, and CD8/HLADR⁺ T cell count gradually decreased. Before treatment, IL-7 serum levels of patients were significantly higher than that in the control group (p < 0.01). After seven years of effective HAART, IL-7 levels had gradually decreased, but were still higher than in the control group (p < 0.01). The CD127 expression on CD3⁺ CD8⁺ T cells in effective HAART patients was higher than in untreated HIV+ patients (p < 0.05), but was lower than that in the control group (p < 0.05). CD127 expression on CD3⁺ CD4+ T cells was not significantly different among the control group, untreated HIV+ patients and effective HAART group.

Conclusion

After seven years of effective HAART, the quantity and capacity of T cell subsets and IL-7 in HIV-1-infected patients had been partially restored, and the abnormal immune activation has significantly diminished.

Overexpression of phosphatase of regenerating liver-3 in breast cancer: association with a poor clinical outcome

BACKGROUND

Increasing evidence has suggested that phosphatase of regenerating liver-3 (PRL-3) plays an important role in cancer cell migration, invasion and metastasis. However, the correlation between the PRL-3 expression and clinical outcome in breast cancer has not been investigated.

PATIENTS AND METHODS

Using a PRL-3-specific monoclonal antibody 3B6, PRL-3 expression was assessed by immunohistochemistry in tumor tissues from 382 breast cancer patients with a median follow-up of 65 months.

RESULTS

We found that 34.8% patients expressed a high level of PRL-3 protein in their tumors. Patients with a high level of PRL-3 in the tumor had a worse disease-specific survival (DSS) rate than those with a low level of PRL-3 (74.0% versus 84.9%, P = 0.011), and PRL-3 remained an independent prognostic marker for DSS (HR 1.8, 95% CI 1.1-2.9, P = 0.019) in multivariate analysis. More importantly, in 219 node-negative patients, PRL-3 showed a significant correlation with DSS in univariate analysis (P = 0.014) and retained a borderline significance (HR 2.65, 95% CI 0.92-7.64, P = 0.071) in multivariate analysis.

CONCLUSIONS

Our results suggest that PRL-3 may serve as an unfavorable prognostic marker in breast cancer, especially for patients with node-negative diseases. Thus, our findings may provide useful information for individualized therapy in the clinical setting.

Vascular endothelial growth factor: acting as an autocrine growth factor for human gastric adenocarcinoma cell MGC803

Vascular endothelial growth factor (VEGF) is known to be a highly specific mitogen for endothelial cells through two high-affinity tyrosine kinase receptors, VEGFR-1 and VEGFR-2, which are almost specifically expressed in endothelial cells. However, recent findings showed that VEGF receptors may also expressed by nonendothelial cells, especially by tumor cells. To further understand the functional expression of VEGF receptors by nonendothelial cells, our preliminary screening detected the expression of VEGFR-2 in 115 different paraffin-embedded cancer specimens including 35 cases of bladder tumor, 30 cases of breast cancer, 25 cases of intestinal cancer, and 25 cases of lung cancer with immunohistochemistry. The results showed that VEGFR-2 was widely expressed in different tumor tissues. By reverse transcription PCR, NCI-H23, NCI-H460, MGC803, MDA-MB-231, 293, and MCF7 cells were evaluated for the mRNA expression of both VEGF and VEGFR-2. The data indicated that all these tumor cell lines expressed detectable amounts of VEGF mRNA, but only 293, MCF7, and MGC803 cells coexpressed VEGFR-2. Immunoblot analysis also demonstrated the expression of VEGFR-2 at protein level. We further demonstrate that exogenous rhVEGF(165) could stimulate cell growth in MGC803, a tumor cell line derived from gastric adenocarcinoma, in a dose- and time-dependent manner. Furthermore, the antibodies against rhVEGF(165) and VEGFR-2 could block rhVEGF(165)-mediated proliferation of MGC803 cells. These unexpected results provided direct evidence that VEGF may act as an autocrine growth factor to induce the proliferation of gastric adenocarcinoma cells as well as tumor angiogenic cells, thus suggesting a promising tumor therapeutic application based upon the VEGF system.

[Mycoplasma infection in human gastriointestinal carcinoma tissues]

OBJECTIVE

To explore the association between the carcinoma and mycoplasma infection by immunohistochemistry.

METHODS

Antigen of anti-tumor monoclonal antibody PD4 was identified as mycoplasma hyorhinis. Using immunohistochemistry to study archived paraffin-embedded gastriointestinal tract carcinomas tissue. The PCR was applied to amplify the mycoplasma DNA for confirming immunohistochemistry results.

RESULTS

It was showed that mycoplasma was present in 56% (50/90 cases) of gastric carcinoma. The cancer tissues with high differentiation had a higher mycoplasma infection ratio than that of low differentiation cancer tissues. (P < 0.05). In control cases, mycoplasma infection was 28% (18/49) in chronic superficial gastritis, 30% (14/46) in gastric ulcer and 37% (18/49) in intestinal metaplasia of the stomach. Mycoplasma infection was 55.1% (32/58) in colon carcinoma and 20.9% (10/49) in adenomarous polyp (P < 0.005). It seems that colon carcinoma tissues with slight pathological grade had a higher percent of mycoplasma infection than that of cancer tissues with moderate and heavy pathological grade (P < 0.05).

CONCLUSION

The high infection of mycoplasmas in carcinoma tissues suggest an association between mycoplasma and cancer. The mechanism involved in oncogenesis by mycoplasmas remains to be elucidated.

Molecular cloning of a tumor-associated antigen recognized by monoclonal antibody 3H11

Monoclonal antibody (MAb) 3H11 can bind specifically to different cancer cells from different tissues. MAb 3H11 labeled with radioactive isotopes has been used clinically to detect primary cancer and metastatic cancer. Molecular cloning of the antigen recognized by MAb 3H11 is important in studying tumor occurrence and in developing new biotherapy for cancer. Using MAb 3H11, we screened cDNA library made from the human gastric cancer cell line MGC 803, which reacts with MAb 3H11, and isolated one positive clone specifically recognized by the antibody. The insert cDNA fragment was 0.5 kb. After recombining with glutathione-S-transferase expression vector pGEX-4T, the cDNA fragment could be expressed into a fusion protein that specifically reacted with MAb 3H11. Moreover, the fusion protein could competitively inhibit MAb 3H11 binding to MGC 803 cells. Based on the nucleotide sequence of the cDNA fragment, the full length of the cDNA (2156 bp) was obtained by Rapid-Amplification-cDNA-End (RACE) and nested PCR. Its reading frame was 1767 bp encoding a protein of 589 amino acids. Sequence analysis indicated that there is no highly homologous gene in the GenBank. Northern blot and RT-PCR showed that the mRNA of MAb 3H11 antigen was extensively distributed in embryonic tissue and in different cancerous tissues, but not in corresponding normal tissues. Moreover, in producing antibodies to the antigen expressed prokaryotically, we found that the immunogenicity of the antigen was low in mammalian. Thus we believe that this novel antigen acts as an expression regulator in embryo cells and regains expression in tumor cells. In addition, this antigen is characterized by low differentiation and high proliferation. Molecular function of the antigen needs to be investigated.

[Selection and characterization of human antibodies against vascular endothelial growth factor from human phage display antibody library]

OBJECTIVE

To select anti-VEGF (vascular endothelial growth factor) antibodies (Fab fragments) from human phage display antibody library and to identify their specification and activities.

METHODS

Human immunoglobulin heavy chain and light chain genes were separately amplified by RT-PCR from human peripheral lymphocytes using family specific primers and signal sequences of immunoglobulin. Human antibody library was constructed by phage display technology, and phage Fab antibodies to VEGF were screened from this library. ELISA, Western blot and (3)H-thymidine incorporation assays were used for the specification and neutralization activities of these Fab antibodies. Sequencing analysis was carried out for further identification of the antibodies.

RESULTS

The repertoire of human phage display Fab library was 1.5 x 10(8). After 4 round panning with VEGF(121), 280 clones were checked for their binding activities with ELISA and 12 clones could bind to VEGF(121) specifically. Western blot demonstrated that bacterially expressed soluble Fab could specifically recognize VEGF. Results of (3)H- thymidine incorporation showed that one clone of soluble Fab could neutralize the mitogenic activity of VEGF(165) on HUVEC. Sequencing analysis showed that the obtained V(H) gene belonged to human VH6 subgroup and the light chain was VJC rearranged human VL4 gene.

CONCLUSIONS

Human anti-VEGF antibodies can be obtained from human phage display library, which provides a basis for preparation of high affinity human anti-VEGF monoclonal antibodies through antibody engineer technique.

Coexpression of vascular endothelial growth factor and its receptor KDR on gastric adenocarcinoma MGC803 cell line and stimulation of exogenous VEGF(165) to MGC803 cells

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is an angiogenic factor playing an important role in tumor growth. VEGF/VPF interacts with endothelial cells by way of two high-affinity receptor tyrosine kinases: flt-1 and KDR. The vast majority of published studies have described expression of the VPF/VEGF receptors specifically in endothelial cells. To elucidate the further function of VEGF in solid tumor development, the coexpression of VEGF and KDR in gastric adenocarcinoma MGC803 cell lines was shown by reverse transcription polymerase chain reaction (RT-PCR). The MGC803 tumor cells could also be strongly immunostained for KDR by immunocytochemistry. It was further demonstrated that exogenous VEGF(165) can stimulate the MGC803 cell growth in both dose-dependent and time-dependent manners by(3)H-thymidine incorporation. Furthermore, anti-VEGF(165) monoclonal antibody and anti-KDR monoclonal antibody could dose-dependently block the VEGF(165)-induced cell growth. These results provided new evidence that VEGF could cause autocrine stimulation to the proliferation of gastric adenocarcinoma cells.

The effect of antibody against vascular endothelial growth factor on tumor growth and metastasis

Vascular endothelial growth factor (VEGF), a very important in the process of tumor angiogenesis, was chosen as a target in a study to determine whether manipulation of angiogenesis with antibody against VEGF may interrupt tumor growth and metastasis. Anti-VEGF antibody was obtained from immunized rabbits, purified on an affinity column, and identified as neutralized antibody by Mile's assay. IVTA2MA891, a murine spontaneous breast cancer with a high rate of metastasis in lung in TA2 x 615 F1 mice, was chosen as an animal model in this study, because of the high expression of VEGF in the primary tumor as well as in the lung metastatic tumor. The anti-VEGF antibody could inhibit growth of S180 sarcoma in a dose-dependent manner, and the inhibition rate could reach 41.0% with a dose of 200 microg mouse(-1) day(-1). Anti-VEGF antibody could inhibit tumor growth by 76.2% in nude mice bearing human gastric cancer (MGC 803). When anti-VEGF antibody was combined with 131I-3H11, a murine monoclonal antibody conjugated with 131I, only one of five nude mice developed tumor and 84.0% more inhibition of tumor growth was obtained in comparison with treatment by 131I-3H11 alone. The growth of the primary tumor was inhibited by 44.0% and the number and size of the metastatic foci in the lungs were reduced by 73.0% and 83.7% respectively in the animal model, with a high rate of metastasis in lung. The anti-VEGF antibody may be potentially useful for clinical treatment of cancer and metastasis.

[Induction of apoptosis in human gastric carcinoma cell line MGC-803 by monoclonal antibody PD4]

OBJECTIVE

To examine if monoclonal antibody PD4 (McAb PD4) which identifies a surface antigen of 40 kD (P40) expressed in gastric carcinoma cells could induce tumor cell apoptosis.

METHODS

The antibody was tested for its effect on cell cycle and cell injury in gastric carcinoma cell MGC-803 by flow cytometry, DNA electrophoresis and TdT assay. Fas antigen expression in MGC-803 was also examined.

RESULTS

McAb PD4 could block tumor cell proliferation cycle and trigger cell death by inducing apoptosis, but expression of Fas antigen in MGC-803 cells was negative.

CONCLUSION

P40 is a tumor associated antigen which is distinct from Fas antigen. Molecular cloning of P40 will clarify the pathway and mechanism of apoptosis induced by this monoclonal antibody.

[The effect of antibody against vascular endothelial growth factor (VEGF) on tumor metastasis]

OBJECTIVE

To study whether manipulation of angiogenesis with antibody against vascular endothelial growth factor (VEGF) may interrupt the tumor growth and metastasis.

METHODS

IV TA2MA 891 is a murine spontaneous breast cancer with high rate of metastasis in lung in (TA2x615) F1 mice, and it was chosen as an animal model in this study because of the high expression of VEGF in primary tumor as well as in lung metastatic tumor. The mice were injected with anti-VEGF polyclonal antibody at a dose of 200 micrograms/mouse/day from day 9 to 23 following s.c. tumor inoculation and sacrificed on day 26.

RESULTS

The growth of primary tumor was inhibited by 44.0% and the number and size of metastatic foci in the lungs were inhibited by 73.0% and 83.7% respectively.

CONCLUSION

The antibody against human VEGF may be a potentially effective antimetastasis agent for the treatment of patients with lung metastasis.

[Construction, expression and activity of a single chain antibody to gastric cancer cells]

OBJECTIVE

To construct single chain antibody from McAb 3H11, which has been successfully used in clinical radioimmunoimage, for its widel application in biological treatment of human cancer.

METHOD

Reversetranscription and polymerize chain reaction (RT-PCR) were used to clone the V region genes of McAb 3H11 (VH, VL). The cloned VH and VL were sequenced and recombined through a (Gly4Ser) 3 linker. The constructed single chain antibody gene was joined with glutathione-S-transferase gene (gst) and its fusion proteins (GS3H11) were expressed in E. coli. The activity of GS3H11 was characterized with competition experiments after its denature and renature treatment.

RESULTS

The recombinant GS3H11 was highly produced in inclusion bodies and the activity was recovered after being renatured. The competition experiments showed that GS3H11 could competitively inhibit the McAb 3H11 binding to gastric tumor cells MGC803. The inhibition was complete when the molecular ratio of GS3H11 to McAb 3H11 reached to 30:1. However, the GS3H11 did not interfere in binding of McAb PD4 and 3G9 to MGC803.

CONCLUSION

The specific binding activity of McAb 3H11 is retained in single chain antibody which is potentially useful for therapeutic application.

Differential response of the Ras exchange factor, Ras-GRF to tyrosine kinase and G protein mediated signals

Ras-GRF, a guanine-nucleotide exchange factor that activates Ras p21, was tested for its ability to couple to either tyrosine kinase or heterotrimeric G protein signal transduction pathways. Ras-GRF failed to bind the SH2 and SH3 containing adaptor protein Grb2, either in vitro or in vivo. Furthermore, Ras-GRF did not form a stable complex with activated EGF receptor. However, as has been shown previously (Cen et al., 1994), the presence of Ras-GRF in NIH3T3 cells enhanced the activation of Ras induced by serum stimulation. A similar effect was not observed with PDGF stimulation. Moreover, serum stimulation lead to the hyperphosphorylation of Ras-GRF. Both the serum induced super-activation of Ras, and the hyperphosphorylation of Ras-GRF were blocked by pretreatment of cells with the Gi,o inhibitor pertussis toxin, but not by pretreatment with the tyrosine kinase inhibitor genistein. These results suggest that Ras-GRF has the capacity to mediate Ras activation initiated by signals using heterotrimeric G proteins.

Molecular cloning of cDNAs encoding a guanine-nucleotide-releasing factor for Ras p21

The stimulation of a variety of cell surface receptors promotes the accumulation of the active, GTP-bound form of Ras proteins in cells. This is a critical step in signal transduction because inhibition of Ras activation by anti-Ras antibodies or dominant inhibitory Ras mutants blocks many of the effects of these receptors on cellular function. To reach the active GTP-bound state, Ras proteins must first release bound GDP. This rate-limiting step in GTP binding is thought to be catalysed by a guanine-nucleotide-releasing factor (GRF). Here we report the cloning of complementary DNAs from a rat brain library that encode a approximately 140K GRF for Ras p21 (p140Ras-GRF). Its carboxy-terminal region is similar to that of CDC25, a GRF for Saccharomyces cerevisiae RAS. This portion of Ras-GRF accelerated the release of GDP from RasH and RasN p21 in vitro, but not from the related RalA, or CDC42Hs GTP-binding proteins. A region in the amino-terminal end of Ras-GRF is similar to both the human breakpoint cluster protein, Bcr, and the dbl oncogene product, a guanine-nucleotide-releasing factor for CDC42Hs. An understanding of Ras-GRF function will enhance our knowledge of the many signal transduction pathways mediated by Ras proteins.

[Tissue distribution of red blood cells treated with X-ray contrast media in rats]

Tissue distribution of red blood cells (RBC) that were treated with X-ray contrast media was investigated in rats. The contrast medium mixed with an equivolume of 51Cr-labelled RBC was administered to the internal carotid artery in a dose of 200 microliters/rat; and the radioactivity in the brain, lung and spleen were determined. The contrast medium mixed with an equivolume of blood was administered to the right atrium in a dose of 4 ml/kg, and the hemoglobin content in the lung and changes in pulmonary and circulatory functions were determined. In the ionic contrast medium (meglumine diatrizoate)-treated group, the radioactivity in the brain remained 30 to 50 times higher compared with the nonionic contrast medium (iopamidol)- and saline-treated group until 15 min after infusion. The radioactivity in the spleen increased and the radioactivity and hemoglobin content in the lung decreased time-dependently in the diatrizoate-treated group, whereas iopamidol- and saline-treated groups exhibited constantly low values during the experimental period. Changes in the airway pressure, pulmonary arterial pressure, systemic blood pressure and heart rate were similar after intra-atrial administration of diatrizoate mixed with blood and diatrizoate mixed with saline. These results suggest that the ionic contrast medium affects the RBC and causes a microcirculatory disturbance in the brain.