Exploring ecological effects of arsenic and cadmium combined exposure on cropland soil: from multilevel organisms to soil functioning by multi-omics coupled with high-throughput quantitative PCR.

Arsenic (As) and cadmium (Cd) pose potential ecological threats to cropland soils; however, few studies have investigated their combined effects on multilevel organisms and soil functioning. Here, we used collembolans and soil microbiota as test organisms to examine their responses to soil As and Cd co-contamination at the gene, individual, and community levels, respectively, and further uncovered ecological relationships between pollutants, multilevel organisms, and soil functioning. At the gene level, collembolan transcriptome revealed that elevated As concentrations stimulated As-detoxifying genes AS3MT and GST, whereas the concurrent Cd restrained GST gene expression. At the individual level, collembolan reproduction was sensitive to pollutants while collembolan survival wasn't. At the community level, significant but inconsistent correlations were observed between the biodiversity of different soil keystone microbial clusters and soil As levels. Moreover, soil functioning related to nutrient (e.g., carbon, nitrogen, phosphorus, and sulfur) cycles was inhibited under As and Cd co-exposure only through the mediation of plant pathogens. Overall, these findings suggested multilevel bioindicators (i.e., AS3MT gene expression in collembolans, collembolan reproduction, and biodiversity of soil keystone microbial clusters) in cropland soils co-contaminated with As and Cd, thus improving the understanding of the ecotoxicological impact of heavy metal co-contamination on soil ecosystems.

Ascorbic acid-mediated reactive oxygen species homeostasis modulates the switch from tapetal cell division to cell differentiation in Arabidopsis.

The major antioxidant L-ascorbic acid (AsA) plays important roles in plant growth, development, and stress responses. However, the importance of AsA concentration and the regulation of AsA metabolism in plant reproduction remain unclear. In Arabidopsis (Arabidopsis thaliana) anthers, the tapetum monolayer undergoes cell differentiation to support pollen development. Here, we report that a transcription factor, DEFECTIVE IN TAPETAL DEVELOPMENT AND FUNCTION 1 (TDF1), inhibits tapetal cell division leading to cell differentiation. We identified SKEWED5-SIMILAR 18 (SKS18) as a downstream target of TDF1. Enzymatic assays showed that SKS18, annotated as a multicopper oxidase-like protein, has ascorbate oxidase activity, leading to AsA oxidation. We also show that VITAMIN C DEFECTIVE1 (VTC1), an AsA biosynthetic enzyme, is negatively controlled by TDF1 to maintain proper AsA contents. Consistently, either knockout of SKS18 or VTC1 overexpression raised AsA concentrations, resulting in extra tapetal cells, while SKS18 overexpression in tdf1 or the vtc1-3 tdf1 double mutant mitigated their defective tapetum. We observed that high AsA concentrations caused lower accumulation of reactive oxygen species (ROS) in tapetal cells. Overexpression of ROS scavenging genes in tapetum restored excess cell divisions. Thus, our findings demonstrate that TDF1-regulated AsA balances cell division and cell differentiation in the tapetum through governing ROS homeostasis.

[Prevention from PICC-related venous thrombosis in the upper limbs of malignant tumor patients with moxibustion combined with plucking at Jiquan (HT 1): a randomized controlled trial].

OBJECTIVE: To observe the clinical effect of moxibustion combined with plucking technique at Jiquan (HT 1) for preventing peripherally inserted central catheter (PICC)-related venous thrombosis in the upper limbs of malignant tumor patients. METHODS: A total of 80 malignant tumor patients undergoing PICC were randomized into an observation group and a control group, 40 cases in each one. In the control group, the routine care for PICC was exerted. In the observation group, besides the routine care, moxibustion combined with plucking technique at Jiquan (HT 1) was added. Mild moxibustion was exerted along the venous distribution of PICC (avoiding the entry site) for 10 to 15 min, and then, the circling moxibustion was applied to Quchi (LI 11), Xuehai (SP 10) and Tianfu (LU 3), 3 to 5 min at each acupoint. Finally, plucking technique was given at Jiquan (HT 1) for 5 to 10 min. This combined therapy was intervened since the 2nd day of PICC placement, once daily, 5 times a week, for 3 weeks totally. The incidence of the PICC-related venous thrombosis in the upper limbs was compared between the two groups on day 42 of placement. On day 2, 7, 14, 21, 28, 35 and 42 of PICC placement, the peak systolic velocity (PSV) and the end-diastolic velocity (EDV) of the subclavicular vein on the placement side were observed separately in the two groups. RESULTS: The incidence of the PICC-related venous thrombosis in the upper limbs in the observation group was lower than that in the control group (2.5% [1/40] vs 17.5% [7/40], P<0.05). From day 7 to 35 of PICC placement, PSV of the subclavicular vein on the placement side was higher than that on the day 2 of PICC placement in the observation group (P<0.05). On day 28 and 42 of PICC placement, PSV of the subclavicular vein on the placement side was lower than that on the day 2 of PICC placement in the control group (P<0.05). In the observation group, EDV of the subclavicular vein on the placement side was higher than that on the day 2 of PICC placement from day 7 to 28 of PICC placement (P<0.05). In the control group, EDV of the subclavicular vein on the placement side from day 28 to 42 of PICC placement was lower than that on the day 2 of PICC placement (P<0.05). From day 7 to 42 of PICC placement, PSV and EDV of the subclavicular vein on the placement side in the observation group were all higher than those in the control group (P<0.01, P<0.05). CONCLUSION: The combined treatment of moxibustion with plucking technique at Jiquan (HT 1) can effectively prevent PICC-related venous thrombosis in the upper limbs and improve venous blood flow velocity in malignant tumor patients.

Room-temperature ppb-level SO2 gas sensors based on RGO/WO3 and MWCNTs/WO3 nanocomposites.

ppb-level SO2 gas sensors for use at room temperature were fabricated using an in situ one-pot polyol method combined with metal organic decomposition (MOD) of nanocomposite films of multi-walled carbon nanotubes/WO3 (MWCNTs/WO3) and reduced graphene oxide/WO3 (RGO/WO3) on an alumina substrate. Comparative gas sensing results showed that the SO2 gas sensor based on the RGO/WO3 nanocomposite film exhibited a higher response compared with the MWCNTs/WO3 nanocomposite film and pristine WO3 film, sensing SO2 gas at very low (ppb-level) concentrations at room temperature. The SO2 gas sensor based on the RGO/WO3 nanocomposite film also had fast response and recovery times, good reproducibility, and the lowest detection limit. The formation of new conducting pathways and the spread of the depletion layers at the interface of the doped MWCNTs or RGO and the WO3 matrix upon interaction with SO2 gas were responsible for the enhanced response.

Retraction Note to: Effect of miR-451 on the Biological Behavior of the Esophageal Carcinoma Cell Line EC9706.

The Editor-in-Chief has retracted this article [1] because Figure 8 overlaps with Figure 6b of [2] and Figure 6 overlaps with Figure 3 of [3] and Figure 3 of [4].

Effects of Bifidobacterium infantis on cytokine-induced neutrophil chemoattractant and insulin-like growth factor-1 in the ileum of rats with endotoxin injury.

BACKGROUND: The digestive tract is the maximal immunizing tissue in the body, and mucosal integrity and functional status of the gut is very important to maintain a healthy organism. Severe infection is one of the most common causes of gastrointestinal dysfunction, and the pathogenesis is closely related to endotoxemia and intestinal barrier injury. Bifidobacterium is one of the main probiotics in the human body that is involved in digestion, absorption, metabolism, nutrition, and immunity. Bifidobacterium plays an important role in maintaining the intestinal mucosal barrier integrity. This study investigated the protective mechanism of Bifidobacterium during ileal injury in rats. AIM: To investigate the effects of Bifidobacterium on cytokine-induced neutrophil chemoattractant (CINC) and insulin-like growth factor 1 (IGF-1) in the ileum of rats with endotoxin injury. METHODS: Preweaning rats were randomly divided into three groups: Control (group C), model (group E) and treatment (group T). Group E was intraperitoneally injected with lipopolysaccharide (LPS) to create an animal model of intestinal injury. Group T was intragastrically administered Bifidobacterium suspension 7 d before LPS. Group C was intraperitoneally injected with normal saline. The rats were killed at 2, 6 or 12 h after LPS or physiological saline injection to collect ileal tissue samples. The expression of ileal CINC mRNA was evaluated by reverse transcription-polymerase chain reaction (RT-PCR), and expression of ileal IGF-1 protein and mRNA was detected by immunohistochemistry and RT-PCR, respectively. RESULTS: The ileum of rats in Group C did not express CINC mRNA, ileums from Group E expressed high levels, which was then significantly decreased in Group T (F = 23.947, P < 0.05). There was no significant difference in CINC mRNA expression at different times (F = 0.665, P > 0.05). There was a high level of IGF-1 brown granules in ileal crypts and epithelial cells in Group C, sparse staining in Group E, and dark, dense brown staining in Group T. There was a significant difference between Groups C and E and Groups E and T (P < 0.05). There was no significant difference in IGF-1 protein expression at different times (F = 1.269, P > 0.05). IGF-1 mRNA expression was significantly different among the three groups (P < 0.05), though not at different times (F = 0.086, P > 0.05). CONCLUSION: Expression of CINC mRNA increased in the ileum of preweaning rats with endotoxin injury, and exogenous administration of Bifidobacterium reduced CINC mRNA expression. IGF-1 protein and mRNA expression decreased in the ileum of preweaning rats with endotoxin injury, and exogenous administration of Bifidobacterium prevented the decrease in IGF-1 expression. Bifidobacterium may increase IGF-1 expression and enhance intestinal immune barrier function in rats with endotoxin injury.

Effect of miR-451 on the biological behavior of the esophageal carcinoma cell line EC9706.

BACKGROUND: MicroRNAs play important roles in coordinating a variety of cellular processes. Abnormal expression of miRNAs has been linked to several cancers. However, the functional role of miR-451 in esophageal squamous cell carcinoma remains unclear. AIMS: The present study explored the effects of miR-451 on the biological behavior of the esophageal carcinoma cell line EC9706. METHODS: Synthetic miR-451 mimics were transfected into EC9706 cells using Lipofectamine™ 2000. The expression of miR-451 was analyzed by RT-PCR and the expressions of Bcl-2, AKT and phosphorylated AKT were analyzed by Western blotting. The MTT assay, soft agar colony formation assay, transwell assay and FACS were used to assess the effect of miR-451 on EC9706 cell proliferation, invasion, metastasis and apoptosis. Tumor growth was assessed by subcutaneous inoculation of cells into BALB/c nude mice. RESULTS: In comparison to the controls, a significant increase in the expression of miR-451 was associated with significantly decreased expressions of Bcl-2, AKT and p-AKT, and a significant increase in the apoptosis rate. The number of cell clones was significantly decreased by miR-451 expression, which also caused the inhibition of cell proliferation. The average number of cells penetrating the matrigel was significantly lower than the controls. Injection of miR-451 inhibited tumor growth in a xenograft model. CONCLUSIONS: Upregulated expression of miR-451 induced apoptosis and suppressed cell proliferation, invasion and metastasis in the esophageal carcinoma cell line EC9706. In addition, injection of miR-451 inhibited tumor growth in a xenograft model of esophageal cancer.

[Construction and activities of suilysin mutants].

AIM: To construct the suilysin mutant without hemolytic activity and evaluate its functions. METHODS: The proline in 353 site of suilysin was site-directed mutated to alanine, leucine and valine, respectively. The recombinant mutants were renaturated and purified by immobilized metal ion affinity chromatography, and the purified proteins were evaluated in the hemolytic activity and immunogenicity. RESULTS: We obtained three mutants, SLY(P353A), SLY(P353L) and SLY(P353V). The SLY(P353V) mutant had non-hemolytic activity. Western blotting and animal experiments showed that SLY(P353V) mutant still had immunogenicity. CONCLUSION: Suilysin mutant SLY(P353V) has no hemolytic activity but remains immunogenicity.

[Expression, purification and protective antigen analysis of cell wall protein MRP of Streptococcus suis type 2].

AIM: To amplify the mrp gene of Streptococcus suis type 2 05ZYH33, express it in E.coli BL21 in order to acquire high purity recombinant protein MRP, then evaluate the protective antigen of recombinant protein MRP. METHODS: Using PCR technology to obtain the product of mrp gene of 05ZYH33, and then cloned it into the expression vector pET28a(+). The recombinant protein was purified by affinity chromatography, later immunized New Zealand rabbit to gain anti-serum, then test the anti-serum titer by ELISA. The opsonophagocytic killing test demonstrated the abilities of protective antigen of MRP. RESULTS: The truncated of MRP recombinant protein in E.coli BL21 expressed by inclusion bodies, and purified it in high purity. After immunoprotection, the survival condition of CD-1 was significantly elevated. The survival rate of wild-type strain 05ZYH33 in blood was apparently decreased after anti-serum opsonophagocyticed, but the mutant delta; MRP showed no differences. CONCLUSION: MRP represent an important protective antigen activity.

RNAi-induced K-Ras gene silencing suppresses growth of EC9706 cells and enhances chemotherapy sensitivity of esophageal cancer.

To analyze the growth, proliferation, apoptosis, invasiveness and chemotherapy sensitivity of EC9706 cells after K-Ras gene silencing, an expression carrier pSilencer-siK-Ras was constructed, and the EC9706 cell line was transfected using a liposome technique. Six groups were established: Control, siRNA NC (transfected with empty vector pSilencer2.1); Ras siRNA (transfected with pSilencer-siK-Ras2); Paclitaxel; Paclitaxel + siRNA NC; and Ras siRNA +Paclitaxel. After the treatment, RT-PCR, Western blotting, MTT assay, flow cytometry and the Transwell technique were used to assess expression of K-Ras mRNA and protein in EC9706 cells, as well as cell growth, proliferation, apoptosis and invasiveness. The effect of Paclitaxel chemotherapy was also tested. pSilencer-siK-Ras2 effectively down-regulated expression of K-Ras mRNA and protein in EC9706 cells, growth being significantly inhibited. Flow cytometry indicated obvious apoptosis of cells in the experimental group, with arrest in the G1 phase; cell migration ability was also reduced. After pSilencer-siK-Ras2 transfection or the addition of Paclitaxel, EC9706 cells were suppressed to different extents; the suppressive effect was strengthened by combined treatment. The results suggested that RNAi-induced K-Ras gene silencing could enhance chemotherapy sensitivity of esophageal cancer.

[Expression, purification and activity assay of Streptococcus suis serotype 2 cell wall protein SSU1664].

AIM: To amplify the SSU1664 gene from Streptococcus suis serotype 2 strain 05ZY, to express the gene in E.coli, and to evaluate the activities of the recombinant protein. METHODS: SSU1664 gene was amplified by PCR using primers according to 05ZY genome sequences and cloned into the expression vector. The recombinant protein was purified by affinity chromatography and its immunogen activities were tested by Western blot and ELISA. RESULTS: SSU1664 gene could solublely express in E.coli BL21(DE3). Western blot analysis showed that the recombinant protein could react with rat serum immunized with Streptococcus suis, but not with non-immunized rat serum. ELISA assay showed that anti-SSU1664 IgM content in Streptococcus suis-infected patient was significantly higher than that in healthy donors. CONCLUSION: The recombinant SSU1664 protein has immunogen activity and might be one promising Streptococcus suis vaccine candidate and diagnosis marker of Streptococcus suis early infection.

[Purification and biological activities analysis of streptococcus suis Serotype 2 suilysin].

AIM: To explore the purification methods of wild-type and recombinant suilysin and to evaluate their biological activities. METHODS: Wild-type suilysin was purified by ammonium sulfate precipitation, anion-exchange chromatography and hydrophobic chromatography in turn, while recombinant suilysin was first refolded and purified by immobilized metal ion affinity chromatography, and further purified by Thiopropyl Sepharose 6B. The biological activities were evaluated by hemolysis test, cytotoxicity assay. RESULTS: Both prepared wild-type and recombinant suilysin, with purify over 90%, have hemolysis activity and could injure target cells at high concentration while cholesterol could completely inhibit their activities. CONCLUSION: Recombinant suilysin has similar biological activities with wild-type suilysin, and this work contributed to further study the functions of suilysin on pathogenesis of steptococcus suis.

In vivo and in vitro antitumor effects of a staphylococcal enterotoxin A mutant (SEA-H61D).

In this study, we evaluated SEA-H61D, a staphylococcal enterotoxin A mutant without emetic activity, as an antitumor agent in vitro and in vivo. It showed that SEA-H61D could significantly inhibit the growth of many cancer cell lines in vitro at very low concentrations by activating human peripheral blood mononuclear cells (PBMCs). CD4+ and CD8+ T lymphocytes could be activated at a dose between 125 and 500 µg/kg. Systemic administration of SEA-H61D in vivo significantly inhibited tumor growth, with the treated group undergoing tumor necrosis and showing a strong infiltration of lymphocytes to the tumor area.

Development of colloidal gold-based immunochromatographic assay for rapid detection of Streptococcus suis serotype 2.

To develop colloidal gold immunochromatographic strips for the direct detection of the Streptococcus suis serotype 2 antigen, colloidal gold was prepared by reduction of a gold salt with sodium citrate and coupled with polyclonal antibody against S. suis serotype 2. The optimal concentrations of the capture antibody and the coating antibody were determined to be 22mug/mL and 2.0mg/mL, respectively, and that of the blocking buffer was determined to be 1.5% bovine serum albumin. Different serotypes of S. suis and other related bacteria were used to evaluate the sensitivity, specificity, and stability of the immunochromatographic strips. The detection sensitivity was found to be as high as 10(6)CFU/mL. There was no cross-reaction of the antibodies with other serotypes of S. suis (except with SS1/2, which shares some common sugar residues or antigenic determinants with serotype 2) and other related bacteria. In conclusion, we developed colloidal gold immunochromatographic strips that had high sensitivity and specificity. This method proved to be feasible, convenient, rapid, and effective for detecting S. suis serotype 2.

[Ginsenoside Rg3 induces apoptosis of human lung squamous cell carcinoma SK-MES-1 cell line].

OBJECTIVE: To investigate the effect of ginsenoside Rg3 on the apoptosis and survivin expression in human lung squamous cell carcinoma cell line SK-MES-1. METHODS: SK-MES-1 cells were divided into Rg3 treatment group, blank control group and positive control (arsenic trioxide) group. The apoptotic rate of the cells in each group was determined using flow cytometry, and the expression of survivin protein and mRNA was detected by immunocytochemistry and RT-PCR, respectively. RESULTS: A 48-h treatment with Ginsenoside Rg3 induced increased apoptotic rate of SK-MES-1 cells in a dose-dependent manner. Ginsenoside Rg3 significantly downregulated the expressions of survivin protein and mRNA as compared with the expression levels in the blank control group (P<0.05). CONCLUSION: Ginsenoside Rg3 can induce the apoptosis of SK-MES-1 cells, the mechanism of which may involve inhibited survivin expression.

[The effects of ginsenosides Rg3 on the expressions of VEGF and KDR in human lung squamous cancer cells].

OBJECTIVE: To investigate the inhibitive effects of Ginsenosides Rg3 (GS-Rg3) in the process of tumor angiogenesis and the effects on the expressions of VEGF and its receptor KDR in human lung squamous cancer SK-MES-1 cell line. METHODS: Human lung cancer SK-MES-1 cells were cultured in vitro and immunocytochemistry and RT-PCR methods were used to detect the effects of different concentrations of Rg3 on the expressions of VEGF and KDR on SK-MES-1 cells. RESULTS: The immunocytochemistry results showed that the positive rates of VEGF protein in different group of SK-MES-1 cells were 81.33 +/- 9.04, 61.80 +/- 7.98, 43.80 +/- 5.25, 29.77 +/- 8.04, respectively. The positive rates of KDR protein in different group of SK-MES-1 cells were 65.51 +/- 7.45, 51.73 +/- 9.21, 34.87 +/- 6.15, 22.04 +/- 5.11, respectively. There were significant differences between each group. RT-PCR results suggested that with the increase of the concentration of Rg3, VEGF and KDR amplified bands gradually weakened. There were significant differences between each group. CONCLUSION: GS-Rg3 can down-regulate the expressions of KDR and VEGF protein and their mRNA in human lung squamous cancer SK-MES-1 cells. It may be one of the mechanisms in the process of inhibiting tumor angiogenesis.

Proteome analysis of Streptococcus suis serotype 2.

Outbreaks in humans, caused by Streptococcus suis serotype 2 (SS2), were reported in 1998 and 2005 in China. However, the mechanism of SS2-associated infection remains unclear. For the first time, a 2-D gel approach combined with MS was used to establish a comprehensive 2-D reference map for aiding our understanding of the pathogenicity of SS2. The identification of 694 out of 834 processed spots revealed 373 proteins. Most of the identified proteins were located in the cytoplasm and were involved in energy metabolism, protein synthesis, and cellular processes. Proteins that were abundant in the 2-DE gels could be linked mainly to housekeeping functions in carbohydrate metabolism, protein quality control and translation. 2-DE of secretory proteins was performed using IPG strips of pH 4-7. Among the 102 protein spots processed, 87 spots representing 77 proteins were successfully identified. Some virulence-associated proteins of SS2 were found, including arginine deiminase, ornithine carbamoyl-transferase, carbamate kinase, muramidase-released protein precursor, extracellular factor, and suilysin. Enolase and endopeptidase have been proposed as putative virulence-associated factors in this study. The 2-D reference map might provide a powerful tool for analyzing the virulence factor and the regulatory network involved in the pathogenicity of this microorganism.

[Prokaryotic expression, purification of HSP65-MUC1 VNTR2 fusion protein and primary research on its tumoricidal effect].

AIM: To express the HSP65-MUC1 VNTR(2) in E.coli and to evaluate its activity of inhibiting tumor growth in vivo. METHODS: HSP65 and MUC1 VNTR(2) were generated by PCR method and sub-cloned to pET28a(+) to construct the recombinant expression vector HSP65-MUC1 VNTR(2)-pET28a(+). E.coli BL21(DE3) bearing the plasmid was induced with IPTG for protein production. Target protein was characterized by Western blot with monoclonal antibody and purified by Q-Sepharose ion-exchange chromatography and gel filtration. The murine cancer cell linejB16 that transfected by human gene MUC1 was utilized to construct the model of carcinoma, and the tumor growth inhibition activities of HSP65-MUC1VNTR(2) was evaluated in mice C57BL/6. RESULTS: The gene HSP65 and MUC1 VNTR(2) confirmed by sequence analysis matched respectively with BCG HSP65 and human gene MUC1 VNTRs in GenBank exactly. The reconstructed vector HSP65-MUC1 VNTR(2)-pET28a could express target protein stably in the soluble fraction of bacterial extract. The purity of HSP65-MUC1 VNTR(2) protein could be above 95% after purification by Q ion-exchange chromatography and gel filtration. The result of Western blot with monoclonal antibody showed positive. The results of prophylactic immunization with HSP65-MUC1 VNTR(2) fusion protein showed that experiment all groups had significantly higher tumor inhibition rates than that of control group. CONCLUSION: In summary, HSP65-MUC1 VNTR(2) fusion protein was solubly expressed in prokaryotic expression system and its tumor growth inhibition activity was evaluated primarily. The result indicated that the fusion protein could inhibit the MUC1 positive tumor growth significantly. It can be used in the future research as the cancer vaccine.

The pilot study of anti-tumor effects versus immunosuppression of Staphylococcal Enterotoxin C.

Superantigens tremendously activate T lymphocytes by recognizing the particular region on TCR Vbeta, by which cytotoxic T cells can be well armed to kill tumor cells. However, the obstacle exists in the fact that immunosuppression is induced adversely. Staphylococcal enterotoxins (SEs) are pyrogenic superantigens who invoke T lymphocytes cytotoxicity at a very low dosage where their endotoxic activity diminishes. Despite that the elaborate mechanisms are largely unknown, tumoricidal capacity of SEA and SEB has been well studied. In this study, we devoted our attention to evaluate Staphylococcal Enterotoxin C (SEC) regarding its tumoricidal activity versus immunosuppression. We proved with flow cytometry that SEC treatment on C57 mice resulted in a boost of the differentiation of T lymphocytes into CD4(+), CD8(+) subpopulations. In vitro, SEC causes increased IFNgamma release from human PBMC. Furthermore, in coculture SEC-treated human PBMC led to more death of cancer cell lines from a variety of origins. Systemic SEC treatment in mouse and rabbit models significantly decreases tumor growth. In tumor-bearing rabbits, tumor necrosis and strong infiltration of lymphocytes into tumor tissue were observed; the rabbits also benefit with less metastasic cancer cells in the lung. In the meantime, the induced cell immune responses, both T cell differentiation and PBMC IFNgamma release, declined as SEC concentration rose. Tumor growth data obtained from animal models are in accordance with the changes in immunity, in which tumor growth ceased to respond to high dosage SEC as it did to lower dosage. These observations on SEC investigation, particularly in aspect of dosage-related immunosuppression, are of significance to SEC therapeutic potential to cancer. Molecular mechanism underlying these findings warrants further intensive investigation.

Targeting of hepatoma cell and suppression of tumor growth by a novel 12mer peptide fused to superantigen TSST-1.

Hepatocellular carcinoma (HCC), one of the most common and malignant tumors worldwide, is unresponsive to any of the available therapies. Using intact HCC cells as therapeutic targets, we isolated a novel peptide, denoted HCC79 (KSLSRHDHIHHH), from a phage display peptide library. HCC79 can bind to hepatoma cell membranes with high affinity and specificity. Remarkably, competitive binding assays demonstrated that HCC79 competed with HAb25, a specific antibody for HCC, in binding to hepatoma cells. The corresponding synthetic peptide did not inhibit tumor proliferation directly, but repressed tumor invasion significantly in a cell migration assay. Moreover, we explored the potential of the selected peptide to deliver a superantigen (SAg) to cancer cells, to attain a significant cell-targeting effect. When the peptide is fused to the TSST-1 SAg, the resulting fusion protein could bind to hepatoma cells with high affinity in vitro and improved the tumor inhibition effect by activating T lymphocyte cells in vitro and in vivo, compared with TSST-1 alone. Taken together, our results indicate that this peptide and its future derivatives may have the potential to be developed into highly specific therapeutic agents against cancer.