Anti-tumor activity and immunogenicity of a succinoglycan riclin.

Natural polysaccharides have attracted considerable interests due to diverse biological activities. Succinoglycan is an extracellular polysaccharide produced by most Agrobacterium strains. Here, we confirmed riclin was a typical succinoglycan by NMR and methylation analysis, and investigated the antitumor effects of riclin in sarcoma 180 tumor-bearing mice. The results showed that riclin inhibited the tumor growth significantly as well as cyclophosphamide (CTX). While CTX caused serious damage to spleen structure, riclin increased the spleen index and promoted lymphocytes proliferation in peripheral blood, spleen and lymph nodes. Riclin decreased splenocytes apoptosis as evidenced by alterations of B-cell lymphoma-2 family proteins and Cleaved Caspase-3 protein. Moreover, 1H nuclear magnetic resonance (NMR)-based metabolomics analysis revealed that riclin partially altered the metabolic profiles of splenocytes. In conclusion, riclin is a succinoglycan that performed strong immunogenicity and suppressed sarcoma growth in mice. Succinoglycan riclin could be a potential antitumor agent for functional food and pharmaceutical purpose.

Antitumor effects of citrinin in an animal model of Sarcoma 180 via cytogenetic mechanisms.

Citrinin (CIT) is a cytotoxic, hepatotoxic, nephrotoxic and cardiotoxic metabolite obtained from Penicillium citrinum, that has been increasingly searched as an anticancer drug candidate. In this study, we assessed the antitumor effects of citrinin, using cytogenetic biomarkers for genotoxicity in Sarcoma 180 (S-180) ascitic fluid cells of mice. Citrinin, extracted from P. citrinum acetonitrile extract, was characterized by LC-MS. Cytotoxic assessment was done through using comet (alkaline version) and micronucleus assays. In S-180 cells, CI50 of CIT was 3.77 µg/mL, while at 12.5 and 100 µg/mL, CIT was as cytotoxic as doxorubicin (2 µg/mL). At 0.5, 1.0 and 2.0 µg/mL, it induced genotoxicity and mutagenicity in S-180 cells, especially at 2 µg/mL, triggering oxidative damage similar to hydrogen peroxide (10 mM). The antitumor effects were evidenced by a marked increase in S-180 cells apoptosis and necrosis due to clastogenic and/or aneugenic cytogenetic effects (micronucleus formation), as well as by induction of nucleoplasm bridges and nuclear buds, culminating in S-180 apoptosis and necrosis. CIT has potential as drug candidate for antitumor purposesbyinvolving cytogenetic mechanisms.

Study on antitumor, antioxidant and immunoregulatory activities of the purified polyphenols from pinecone of Pinus koraiensis on tumor-bearing S180 mice in vivo.

Pinecone polyphenols are bioactive dietary constituents that enhance health and help prevent and treat cancer through improving antioxidant and immunoregulatory activities. This study was designed to investigate the antitumor, antioxidant and immunoregulatory activities of the 40% ethanol eluent of polyphenols from pinecone of pinus koraiensis (PPP-40) in Sarcoma 180 (S180)-bearing mice models in vivo. The results of antitumor activity indicated that PPP-40 significantly inhibited S180 tumor growth and the dose of 150mg/kg exhibited the highest antitumor activity. Moreover, TdT-mediated dUTP nick end labeling (TUNEL) assay results further confirmed the apoptosis of S180 tumor cells. In addition, PPP-40 could obviously promote the expressions of Bax protein and inhibit the Bcl-2 protein, accordingly improve the expressions of activated Caspase-3 as well, which resulted in the activation of mitochondrial apoptotic pathway of tumor cells in S180 mice eventually. The results of antioxidant activity showed that the S180 mice treated with PPP-40 had the higher superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, the more glutathione (GSH) content, and the lower malondialdehyde (MDA) level in plasma comparing with non-treated control group. Moreover, the administration with PPP-40 (150mg/kg) significantly accelerated the proliferation of splenocytes (p<0.01) and increased the monocyte phagocytosis activity in vivo simultaneously. These results revealed that PPP-40 exerts an effective antitumor activity by activating the mitochondrial apoptotic pathway and improving the antioxidant and immunoregulatory activities.

Construction of random tumor transcriptome expression library for creating and selecting novel tumor antigens.

Novel tumor antigens are necessary for the development of efficient tumor vaccines for overcoming the immunotolerance and immunosuppression induced by tumors. Here, we developed a novel strategy to create tumor antigens by construction of random tumor transcriptome expression library (RTTEL). The complementary DNA (cDNA) from S180 sarcoma was used as template for arbitrarily amplifying gene fragments with random primers by PCR, then ligated to the C-terminal of HSP65 in a plasmid pET28a-HSP for constructing RTTEL in Escherichia coli. A novel antigen of A5 was selected from RTTEL with the strongest immunotherapeutic effects on S180 sarcoma. Adoptive immunotherapy with anti-A5 sera also inhibited tumor growth, further confirming the key antitumor roles of A5-specific antibodies in mice. A5 contains a sequence similar to protein-L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1). The antisera of A5 were verified to cross-react with PCMT1 by Western blotting assay and vice versa. Both anti-A5 sera and anti-PCMT1 sera could induce antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity toward S180 cells by in vitro assay. Further assay with fluorescent staining showed that PCMT1 is detectable on the surface of S180 cells. Summary, the strategy to construct RTTEL is potential for creating and screening novel tumor antigens to develop efficient tumor vaccines. By RTTEL, we successfully created a protein antigen of A5 with significant immunotherapeutic effects on S180 sarcoma by induction of antibodies targeting for PCMT1.

Cytotoxicity and gene expression in sarcoma 180 cells in response to spiky magnetoplasmonic supraparticles.

Multifunctional nanoparticles (NPs) have been designed for a variety of cell imaging and therapeutic applications, and the study of their cellular interactions is crucial to the development of more efficient biomedical applications. Among current nanomaterials, concave core-shell NPs with complex angled geometries are attractive owing to their unique shape-dependent optical and physical properties as well as different tendency for cell interaction. In this study, we investigated the morphology effect of spiky gold-coated iron oxide supraparticles (Fe3O4@Au SPs) on cytotoxicity and global gene expression in sarcoma 180 cells. Cells treated for 7 days with spiky supraparticles (SPs) at concentrations up to 50 µg/mL showed >90% viability, indicating that these NPs were nontoxic. To shed light on the differences in cytotoxicity, we monitored the expression of 33,315 genes using microarray analysis of SP-treated cells. The 171 up-regulated genes and 181 down-regulated genes in spiky SP-treated cells included Il1b, Spp1, Il18, Rbp4, and Il11ra1, where these genes are mainly involved in cell proliferation, differentiation, and apoptosis. These results suggested that the spiky Fe3O4@Au SPs can induce noncytotoxicity and gene expression in tumor cells, which may be a promising cornerstone on which to base related research such as cyto-/genotoxicology of nanomaterials or the design of nanoscale drug carriers.

Cancer resistance as an acquired and inheritable trait.

AIM: To induce cancer resistance in wild-type mice and detect if the resistance could be inherited to the progeny of the induced resistant mice. Furthermore to investigate the spectrum and immunology of this inherited cancer resistance. MATERIALS AND METHODS: Resistance to with live S180 cancer cells in BALB/c mice was induced by immunization with inactivated S180 cancer cells. The immunization was performed by either frozen/thawed or irradiated cancer cells or cell-free ascitic fluid (CFAF). RESULTS: In all instances the induced resistance was demonstrated to be inheritable. The phenotype was named HICR (heritable induced cancer resistance) and was defined as primary resistant progeny from mice immunized with frozen/thawed or irradiated S180 cells or CFAF obtained from mice with S180 induced ascites. Notably, this resistance was transferred from both male and female mice to the offspring of the immunized mice for at least two generations. Although inheritable, the frequency of cancer-resistant pups was lost over a few generations. Cells from the J774A.1 and RAW cancer cell lines did not induce inheritable cancer resistance, and C57BL/6 mice could not pass on cancer resistance fluorescence-activated cell sorting (FACS) analyses of the peritoneal cells revealed an increased fraction of macrophages. In necropsies of resistant mice no histological signs of cancer or other disease was found. CONCLUSION: Only materials derived from S180 cells could give rise to HICR mice. The molecular basis of the resistance is unknown but may involve epigenetic mechanisms. Other examples of inheritability of acquired phenotypic changes exist but, to our knowledge, this is the first demonstration of acquired, inherited cancer resistance.

A selenosemicarbazone complex with copper efficiently down-regulates the 90-kDa heat shock protein HSP90AA1 and its client proteins in cancer cells.

BACKGROUND: The 90-kDa heat shock protein HSP90AA1 is critical for the stability of several proteins that are important for tumor progression and thus, is a promising target for cancer therapy. Selenosemicarbazone metal complexes have been shown to possess anticancer activity through an unknown molecular mechanism. METHODS: The MTT assay, fluorescence-activated cell sorting, and fluorescent microscopy were used to analyze the mechanism of the anti-cancer activity of the selenosemicarbazone metal complexes. Additionally, RNA-seq was applied to identify transcriptional gene changes, and in turn, the signaling pathways involved in the process of 2-24a/Cu-induced cell death. Last, the expression of HSP90AA1, HSPA1A, PIM1, and AKT proteins in 2-24a/Cu-treated cells were investigated by western blot analysis. RESULTS: A novel selenosemicarbazone copper complex (2-24a/Cu) efficiently induced G2/M arrest and was cytotoxic in cancer cells. 2-24a/Cu significantly induced oxidative stress in cancer cells. Interestingly, although RNA-seq revealed that the transcription of HSP90AA1 was increased in 2-24a/Cu-treated cells, western blotting showed that the expression of HSP90AA1 protein was significantly decreased in these cells. Furthermore, down-regulation of HSP90AA1 led to the degradation of its client proteins (PIM1 and AKT1), which are also cancer therapy targets. CONCLUSION: Our results showed that 2-24a/Cu efficiently generates oxidative stress and down-regulates HSP90AA1 and its client proteins (PIM1, AKT1) in U2os and HeLa cells. These results demonstrate the potential application of this novel copper complex in cancer therapy.

Actin dynamics modulate mechanosensitive immobilization of E-cadherin at adherens junctions.

Mechanical stress is increasingly being shown to be a potent modulator of cell-cell junctional morphologies in developmental and homeostatic processes. Intercellular force sensing is thus expected to be an important regulator of cell signalling and tissue integrity. In particular, the interplay between myosin contractility, actin dynamics and E-cadherin recruitment largely remains to be uncovered. We devised a suspended cell doublet assay to quantitatively assess the correlation between myosin II activity and local E-cadherin recruitment. The single junction of the doublet exhibited a stereotypical morphology, with E-cadherin accumulating into clusters of varied concentrations at the rim of the circular contact. This local recruitment into clusters derived from the sequestration of E-cadherin through a myosin-II-driven modulation of actin turnover. We exemplify how the regulation of actin dynamics provides a mechanism for the mechanosensitive response of cell contacts.

Therapeutic effect of the treatment for colorectal cancer with adenoviral vectors mediated estrogen receptor ß gene therapy combined with thermotherapy.

INTRODUCTION: Our preliminary study on repressing colorectal tumors by recombinant adenoviruses (Ads) delivering the human ERß gene (Ad-ERß) has achieved positive result. METHODS: In this study, hydrophobic fluorescent dyes ICG-Der-01 was entrapped into the N-succinyl-N'-octyl chitosan (SOC) micelles to form the near infrared absorbing dyes SOC-ICG-Der-01 and SOC-ICG-Der-01 mediated near infrared laser (SOC-ICG-Der-01/NIR) thermotherapy was combined with Ad-ERß gene therapy to regress colon cancer in vivo. RESULTS: Firstly, the antitumor efficacies of SOC-ICG-Der-01/NIR thermotherapy were investigated on S180 ascites tumor-bearing mice. Results indicated that, the average tumor volume of SOC-ICG-Der-01/NIR group was the smallest among the three treatment groups. Then, thermotherapy with SOC-ICG-Der-01/NIR combined with Ad-ERß gene therapy to treat HCT-116 colon cancer xenograft model was investigated. Further results demonstrated that, SOC-ICG-Der-01/NIR thermotherapy showed the significantly inhibitory efficiency compared with control group and Ad-ERß enhanced the therapeutic effect of SOC-ICG-Der-01/NIR. CONCLUSION: These findings demonstrated that combined administration of Ad-ERß with SOC-ICG-Der-01/NIR thermotherapy represents a promising colon cancer therapeutic strategy.

In vivo induction of apoptosis by fucoxanthin, a marine carotenoid, associated with down-regulating STAT3/EGFR signaling in sarcoma 180 (S180) xenografts-bearing mice.

Previous in vitro researches have showed that fucoxanthin, a natural carotenoid isolated from sargassum, can inhibit proliferation or induce apoptosis in human neuroblastoma, hepatoma, leukemia, colon carcinoma, prostate cancer or urinary bladder cancer cells. But the precise mechanism by which fucoxanthin exerts anticarcinogenic effects is not yet fully understood. In this study, we performed an in vivo study to investigate the anti-tumor effect and mechanisms of fucoxanthin on xenografted sarcoma 180 (S180) in mice. Results revealed that fucoxanthin significantly inhibited the growth of sarcoma at the dose of 50 or 100 mg/kg. TUNEL analysis showed that the number of positive cells in the fucoxanthin-treated group was higher than that in the control group. Western blotting analysis also revealed the suppressed expression of bcl-2 and enhanced expression of cleaved caspase-3 by fucoxanthin. In addition, immunohistochemistry analysis and Western blotting analysis showed that fucoxanthin significantly decreased the expressions of survivin and vascular endothelial growth factor (VEGF). Most importantly, fucoxanthin inhibited the expressions of the epidermal growth factor receptor (EGFR) and STAT3 and phosphorylated STAT3 proteins. These results indicated that in vivo induction of apoptosis by fucoxanthin is associated with down-regulating STAT3/EGFR signaling in S180 xenografts-bearing mice.

Administration of vitamin E prevents thymocyte apoptosis in murine sarcoma S180 tumor bearing mice.

Many reports claimed that thymic involution occurred in tumor bearing host, which led to a reduction of proliferation in T cells and an impaired immune system. In this study, murine sarcoma S180 tumor cells were used to establish tumor model. There was distinct apoptosis in thymus of the S180 tumor bearing host after 3-week tumor inoculation. High level reactive oxygen species generation was detected in thymocytes of S180 tumor bearers. Vitamin E, a potent antioxidant, was oral administrated to S180 tumor bearing mice in order to eliminate redundant ROS in the host and evaluate the effect against thymic apoptosis. Intact thymic structure and less apoptosis of thymocytes demonstrated that partial restoration of thymuses in S180 tumor bearing mice after 3­week VE treatment. Besides, VE treatment normalized ROS level, MDA level and SOD level of S180 tumor bearers. Thus, it could be concluded that thymic involution prevented by VE treatment in S180 tumor bearing mice was mainly due to inhibition of apoptosis in thymus and elimination of ROS over­production in the host.

Chitooligosaccharides and N-acetyl-D-glucosamine stimulate peripheral blood mononuclear cell-mediated antitumor immune responses.

The aim of the present study was to evaluate the anticancer effects of chitooligosaccharides (COS) and N-acetyl-D-glucosamine (NAG), as well as to investigate the possible mechanisms involved. MTT assay and flow cytometry were used to evaluate the effect of various concentrations of COS and NAG on the proliferation and differentiation of peripheral blood mononuclear cells (PBMCs). In addition, sarcoma 180 cells were transplanted into mice to establish a tumor model. COS and NAG were administered by gavage of various doses. The tumor inhibition rate, thymus and spleen indexes, natural killer (NK) cell activity, and interleukin-2 (IL-2) and interferon-γ (IFN-γ) serum levels were detected. Vascular endothelial growth factor (VEGF) expression levels, an important marker of angiogenesis, were also detected. As shown by immunohistochemistry, VEGF mRNA expression was decreased following treatment with COS and NAG, indicating that COS and NAG have an inhibitory effect on the expression of VEGF. The results from this study indicate that COS administered at a dose of 100 mg/kg and NAG at a dose of 300 mg/kg or 500 mg/kg can not only promote the differentiation of PBMCs and the secretion of IL-2 and IFN-γ, but can also inhibit the expression of VEGF mRNA in sarcoma 180 tumors. Our results show that the antitumor and immunoregulatory effects of COS and NAG are dose-dependent. Furthermore, the antitumor effect is achieved by the improvement of immunoregulation indirectly.

Suppression of tumor growth by systemic delivery of anti-VEGF siRNA with cell-penetrating peptide-modified MPEG-PCL nanomicelles.

Small interfering RNAs (siRNAs) have potential applications for many diseases, such as cancer, since siRNAs can specifically silence disease-associated genes. However, effective siRNA carriers need to be developed to overcome the low siRNA stability in vivo, to form stable complexes and to facilitate intracellular uptake. In this study, to develop a carrier for systemic siRNA delivery, we prepared methoxy poly(ethylene glycol) (MPEG)/polycaprolactone (PCL) diblock copolymers conjugated with a cell-penetrating peptide, Tat, via a disulfide linkage, and evaluated their ability as an siRNA carrier. The particle size of MPEG-PCL-SS-Tat/siRNA complexes was approximately 100-200 nm. The cellular uptake ability after transfection with FAM-siRNA with MPEG-PCL-SS-Tat was significantly higher than that with FAM-siRNA only. MPEG-PCL-SS-Tat did not induce substantial cytotoxicity. Intravenous injection of MPEG-PCL-SS-Tat/anti-vascular endothelial growth factor (VEGF) siRNA (siVEGF) complexes achieved a high anti-tumor effect in tumor-bearing mice. These results suggest that MPEG-PCL-SS-Tat is a potentially effective siRNA carrier for silencing genes in vitro and in vivo.

Influence of lipid components on gene delivery by polycation liposomes: Transfection efficiency, intracellular kinetics and in vivo tumor inhibition.

Transfection efficiency of non-viral gene vectors is influenced by many factors, including chemical makeup, cellular uptake pathway and intracellular delivery. To investigate the effect of lipid saturation on transfection efficiency of polycation liposomes (PCLs), a soybean phospholipids (SPL), egg phospholipids (EPL) and hydrogenated soybean phosphatidylcholine (HSPC) series was used to prepare PCLs. Testing these PCLs in a luciferase assay indicated that with increasing saturation (SPL

Development of cell-penetrating peptide-modified MPEG-PCL diblock copolymeric nanoparticles for systemic gene delivery.

To develop a safe and efficient systemic non-viral gene vector, methoxy poly(ethylene glycol) (MPEG)/poly(epsilon-caprolactone) (PCL) diblock copolymers conjugated with a Tat analog through the ester or disulfide linkage were synthesized and their suitability as a systemic non-viral gene carrier evaluated. The physicochemical properties of the MPEG-PCL diblock copolymers were determined by GPC, (1)H NMR and FT-IR spectroscopy. The particle sizes and in vitro (COS7 and S-180 cells) transfection efficiencies and cytotoxicity were evaluated. Furthermore, the luciferase activity was then determined in various tissues after intravenous injection of MPEG-PCL-SS-Tat/pCMV-Luc complex into mice bearing S-180 cells. The particle sizes of the MPEG-PCL-Tat copolymers with or without pDNA were about 40 and 60nm, respectively. The luciferase activity in COS7 cells transfected with pCMV-Luc with MPEG-PCL-ester-Tat or MPEG-PCL-SS-Tat was higher than that with pDNA only. MPEG-PCL-SS-Tat greatly increased the transfection efficiency compared to MPEG-PCL-ester-Tat in COS7 and S-180 cells. In an in vitro cytotoxicity test MPEG-PCL-SS-Tat did not induce any remarkable cytotoxicity. In an in vivo experiment, the synthesized MPEG-PCL-SS-Tat copolymers promoted the delivery and expression of pDNA into tumor tissue in tumor-bearing mice. In conclusion, this vector might be applicable as a tumor-targeting non-viral systemic gene carrier in the clinical setting.

The spectrum of resistance in SR/CR mice: the critical role of chemoattraction in the cancer/leukocyte interaction.

BACKGROUND: Spontaneous regression/complete resistance (SR/CR) mice are a unique colony of mice that possess an inheritable, natural cancer resistance mediated primarily by innate cellular immunity. This resistance is effective against sarcoma 180 (S180) at exceptionally high doses and these mice remain healthy. METHODS: In this study, we challenged SR/CR mice with additional lethal transplantable mouse cancer cell lines to determine their resistance spectrum. The ability of these transplantable cancer cell lines to induce leukocyte infiltration was quantified and the percentage of different populations of responding immune cells was determined using flow cytometry. RESULTS: In comparison to wild type (WT) mice, SR/CR mice showed significantly higher resistance to all cancer cell lines tested. However, SR/CR mice were more sensitive to MethA sarcoma (MethA), B16 melanoma (B16), LL/2 lung carcinoma (LL/2) and J774 lymphoma (J774) than to sarcoma 180 (S180) and EL-4 lymphoma (EL-4). Further mechanistic studies revealed that this lower resistance to MethA and LL/2 was due to the inability of these cancer cells to attract SR/CR leukocytes, leading to tumor cell escape from resistance mechanism. This escape mechanism was overcome by co-injection with S180, which could attract SR/CR leukocytes allowing the mice to resist higher doses of MethA and LL/2. S180-induced cell-free ascites fluid (CFAF) co-injection recapitulated the results obtained with live S180 cells, suggesting that this chemoattraction by cancer cells is mediated by diffusible molecules. We also tested for the first time whether SR/CR mice were able to resist additional cancer cell lines prior to S180 exposure. We found that SR/CR mice had an innate resistance against EL-4 and J774. CONCLUSIONS: Our results suggest that the cancer resistance in SR/CR mice is based on at least two separate processes: leukocyte migration/infiltration to the site of cancer cells and recognition of common surface properties on cancer cells. The infiltration of SR/CR leukocytes was based on both the innate ability of leukocytes to respond to chemotactic signals produced by cancer cells and on whether cancer cells produced these chemotactic signals. We found that some cancer cells could escape from SR/CR resistance because they did not induce infiltration of SR/CR leukocytes. However, if infiltration of leukocytes was induced by co-injection with chemotactic factors, these same cancer cells could be effectively recognized and killed by SR/CR leukocytes.

Effective in vitro and in vivo gene delivery by the combination of liposomal bubbles (bubble liposomes) and ultrasound exposure.

Gene delivery with a physical mechanism using ultrasound (US) and nano/microbubbles is expected as an ideal system in terms of delivering plasmid DNA noninvasively into a specific target site. We developed novel liposomal bubbles (Bubble liposomes (BLs)) containing the lipid nanobubbles of perfluoropropane which were utilized for contrast enhancement in ultrasonography. BLs were smaller in diameter than conventional microbubbles and induced cavitation upon exposure ultrasound. In addition, when coupled with US exposure, BLs could deliver plasmid DNA into various types of cells in vitro and in vivo. The transfection efficiency with BLs and US was higher than that with conventional lipofection method. Therefore, the combination of BLs and US might be an efficient and novel nonviral gene delivery system.

Proteomic analysis reveals upregulation of RKIP in S-180 implanted BALB/C mouse after treatment with ascorbic acid.

Tumor cells have an invasive and metastatic phenotype that is the main cause of death for cancer patients. Tumor establishment and penetration consists of a series of complex processes involving multiple changes in gene expression. In this study, intraperitoneal administration of a high concentration of ascorbic acid inhibited tumor establishment and increased survival of BALB/C mice implanted with S-180 sarcoma cancer cells. To identify proteins involved in the ascorbic acid-mediated inhibition of tumor progression, changes in the liver proteome associated with ascorbic acid treatment of BALB/C mice implanted with S-180 were investigated using two-dimensional gel electrophoresis and mass spectrometry. Eleven protein spots were identified whose expression was different between control and ascorbic acid treatment groups. In particular, Raf kinase inhibitory protein (RKIP) and annexin A5 expression were quantitatively up-regulated. The increase in RKIP protein level was detected in the tumor tissue and accompanied by an increase in mRNA level. Our results suggest a possibility that these proteins are related to the ascorbic acid-mediated suppression of tumor formation.

Whole tumor cell vaccine with irradiated S180 cells as adjuvant.

Whole tumor cell vaccines have been widely studied and remain promising cancer immunotherapies. In the present study, we discovered that vaccination with irradiated mouse sarcoma S180 tumor cells stimulated robust antitumor immunity to autologous tumor cells in both syngenic and allogenic mice. The antitumor activity requires both T and B cells, but not NK cells. When a mouse lung carcinoma (TC-1) whole tumor cell vaccine was combined with the S180 vaccine, the antitumor immunity against live TC-1 tumor cells is significantly enhanced compared to a TC-1 whole cell vaccine alone. This antitumor immunity not only prevents live tumor challenge but also eradicates existing tumor cells. A similar phenomenon was also observed when S180 vaccine was combined with LL2 Lewis lung carcinoma tumor cells. Therefore, S180 vaccine may serve as an adjuvant for other whole tumor cell vaccines.

[Effects of Sargassum confusum polysaccharide on the expression of p53 and Rb genes in mouse sarcoma S180 cells].

OBJECTIVE: To investigate effects of Sargassum confusum polysaccharide (SP) on the expressions of p53 and Rb genes. METHODS: The mice bearing S180 sarcoma were treated with abdominal SP injection at the daily dose of 50, 100 or 200 mg/kg for 10 consecutive days, The mice injected with 0.85% saline served as the negative control group and those with 5-fluorouracil (5-FU) injection as the positive control group. The tumor weight was measured to calculate the tumor inhibition rate. RT-PCR and Western blotting were used to detect the expression levels of p53 and Rb genes at the mRNA and protein levels, respectively. RESULTS: The 10-day SP treatment at 50, 100 and 200 mg/kg resulted in tumor growth inhibition rates of 30.5%, 47.6% and 63.5%, respectively. SP treatment upregulated the mRNA expressions and increased the protein levels of p53 and Rb in the tumors. CONCLUSION: SP has inhibitory effect against S180 sarcoma in vivo and can increase the expression levels of p53 and Rb genes at both the mRNA and protein levels.