An aqueous extract of Limoniastrum guyonianum gall induces anti-tumor effects in melanoma-injected mice via modulation of the immune response

The objectives of this study were to evaluate the in vitro and in vivo anti-tumor potential of the aqueous gall extract (G extract) from Limoniastrum guyonianum and to elucidate its immunological mechanisms, in part, by assessing its effects on the growth of transplanted tumors and the immune response in these tumor-bearing mice. Here, mice were inoculated with B16F10 mouse tumor cells and then treated intraperitoneally with G extract at 25 or 50 mg extract/kg BW for 7, 14, or 21 days. At each timepoint, effects of the extract on the tumor growth, splenocytes proliferation, NK cell activity, and CTL activity among splenocytes isolated from the mice were measured. G extract-induced tumor growth inhibition was associated with characteristic apoptotic changes in the tumor cells, like nuclear condensation. In addition, the extract inhibited melanin synthesis and tyrosinase activity among melanoma cells in a concentration-related manner. G extract did not only significantly inhibit the growth of the transplantable tumor, but also remarkably increased splenocytes proliferation and both NK and CTL activities in tumor-bearing mice. The extract was also seen to have promoted lysosomal activity of host macrophages and gave rise to enhanced cellular anti-oxidant activity in several cell types in mice.     

蝎毒多肽提取物对白血病NOD/SCID小鼠MMP2、MMP9表达的影响

目的:观察蝎毒多肽提取物(PESV)对白血病NOD/SCID小鼠基质金属蛋白酶(MMP)2、MMP9表达的影响,探讨PESV对白血病细胞外基质降解和髓外浸润的干预机制.方法:首先选取急性白血病患者骨髓单个核细胞注入经过铯-137源照射的NOD/SCID小鼠体内,建立人白血病NOD/SCID小鼠髓外浸润模型;再将实验小鼠随机分组,Ⅰ组、Ⅱ组、Ⅲ组分别注射不同浓度的PESV,Ⅳ组为模型组注射生理盐水,另设Ⅴ组为空白对照组,观察各组小鼠外周白细胞计数、血涂片及生存状态;观察4周后处死小鼠,用Real time PCR方法检测小鼠体内MMP2、MMP9表达水平.结果:给药各组小鼠MMP2、MMP9表达水平均明显低于模型组(P < 0.05),且各组间表达水平随给药浓度增加而减低.给药各组小鼠外周血白细胞计数、血涂片及生存状态也均优于模型组.结论:PESV可以抑制白血病NOD/SCID小鼠体内MMP2、MMP9过度表达,对白血病细胞外基质降解和髓外浸润具有明显阻抑作用.     

肝上皮样血管内皮瘤一例

【摘要】 <正>1病例报告患者男,45岁。主因右上腹呈持续性胀痛6个月,伴食欲不振,于2011年5月7日就诊。患者6个月前无明显诱因出现右上腹持续性胀痛,自服抑酸药治疗,症状无缓解,近6个月消瘦明显。发病时无发热、恶心及呕吐,饮食欠佳,睡眠可,二便正常。既往体健,无肝炎、结核病史,无药物过敏史,无手术、外伤及输血史。查体:一般状况可,皮肤黏膜无苍白,巩膜无黄染,腹部膨隆,右侧肋缘下2cm可触及肝脏,     

相思子蛋白P2抗肝癌作用及对端粒酶活性影响

目的研究相思子蛋白P2对肝癌细胞生长的抑制作用及机制。方法体外实验:MTT法检测相思子蛋白P2对人肝癌HepG2细胞增殖的抑制作用。流式细胞仪检测对HepG2细胞周期和细胞凋亡的影响。TRAP-SYBR-Green染色法检测相思子蛋白P2作用前后细胞端粒酶活性的改变。体内实验:相思子蛋白P2 50、75、100μg.kg-1连续灌胃给药10 d,观察对小鼠肝癌H22移植性肿瘤的生长抑制作用。小鼠口服给药急性毒性观察。结果相思子蛋白P2可明显抑制HepG2细胞增殖,IC50值为5.172×10-3 mg.L-1。在5×10-5～1×10-3 mg.L-1剂量作用下,可引起HepG2细胞凋亡。相思子蛋白P2主要将细胞周期滞留在S期,从而抑制了肿瘤细胞增殖。同时可使细胞端粒酶活性明显降低,其下调端粒酶活性的作用随药物浓度的增加而明显增强。相思子蛋白P2对小鼠H22肝癌细胞生长有明显抑制作用,100μg.kg-1抑瘤率达62.47%,且对胸腺和脾脏指数的影响较环磷酰胺小。小鼠口服给药LD50值为6.77 mg.kg-1。结论相思子蛋白P2体内外均可明显抑制肝癌细胞的生长,其抗肿瘤作用可能与下调细胞端粒酶活性、改变细胞周期分布,诱导细胞凋亡有关。     

Anti-tumor metastatic activity of beta-glucan purified from mutated Saccharomyces cerevisiae

The beta-glucans isolated from Saccharomyces cerevisiae (S. cerevisiae) enhance the innate immune system, but there is little evidence for its antitumor activity. To examine the antitumor and immunostimulating activities of beta-glucan (IS-2) purified from mutated S. cerevisiae, we made an experiment on innate immune response against metastasis of cancer cells by comparing with the beta-glucan from wild-type S. cerevisiae. In experimental lung metastasis of colon 26-M3.1 carcinoma or B16-BL6 melanoma cells, prophylactic administration of beta-glucan purified from mutated S. cerevisiae significantly inhibited lung metastasis in a dose-dependent manner. Furthermore, therapeutic administration of IS-2 also significantly inhibited the colon 26-M3.1 cell growth in mice. In an assay of liver and spleen metastasis produced by i.v. inoculation of L5178Y-ML25 lymphoma cells, IS-2 also significantly inhibited metastasis in CDF1 mice. Furthermore, pretreatment with IS-2 two days before tumor inoculation significantly prolonged the survival time of tumor-bearing mice. In an in vitro cytotoxicity analysis, IS-2 (up to 100 microg/ml) did not affect the growth of colon 26-M3.1 cells. In contrast, IS-2 enhanced splenocyte proliferating activity in a dose-dependent manner. Peritoneal macrophages stimulated with IS-2 produced various cytokines, such as IL-1beta, IFN-gamma, and IL-12. In addition, treatment with IS-2 (20 microg/mouse) induced tumoricidal activity of peritoneal macrophages against colon 26-M3.1 cells. In an assay for natural killer (NK) cell activity, IS-2 (20 microg/mouse, i.v.) significantly augmented NK cytotoxicity against Yac-1 tumor cells at 2 days after IS-2 treatment. The depletion of NK cells by injection of rabbit anti-asialo GM1 serum abolished the inhibitory effect of IS-2 on lung metastasis of colon 26-M3.1 cells. These data suggest that IS-2 inhibits tumor metastasis via activation of macrophages and NK cells.     

Oral administration of fluoxetine alters the proliferation/apoptosis balance of lymphoma cells and up-regulates T cell immunity in tumor-bearing mice

Antidepressants have a controversial role with regard to their influence on cancer and immunity. Recently, we showed that fluoxetine administration induces an enhancement of the T-cell mediated immunity in na?ve mice, resulting in the inhibition of tumor growth. Here we studied the effects of fluoxetine on lymphoma proliferation/apoptosis and immunity in tumor bearing-mice. We found an increase of apoptotic cells (active Caspase-3(+)) and a decrease of proliferative cells (PCNA(+)) in tumors growing in fluoxetine-treated animals. In addition, differential gene expressions of cell cycle and death markers were observed. Cyclins D3, E and B were reduced in tumors from animals treated with fluoxetine, whereas the tumor suppressor p53 and the cell cycle inhibitors p15/INK4B, p16/INK4A and p27/Kip1 were increased. Besides, the expression of the antiapoptotic factor Bcl-2 and the proapoptotic factor Bad were lower and higher respectively in these animals. These changes were accompanied by increased IFN-γ and TNF-α levels as well as augmented circulating CD8(+) T lymphocytes in tumor-bearing mice treated with the antidepressant. Therefore, we propose that the up-regulation of T-cell mediated antitumor immunity may be contributing to the alterations of tumor cell proliferation and apoptosis thus resulting in the inhibition of tumor progression.     

Tumor-derived extracellular vesicles for the active targeting and effective treatment of colorectal tumors in vivo

Colorectal cancer remains one of the main causes of cancer-related deaths worldwide. Although numerous nanomedicine formulations have been developed to tackle the disease, their low selectivity still limits effective therapeutic outcomes. In this study, we isolated extracellular vesicles (EVs) from CT26 colorectal cancer cells and 4T1 murine mammary carcinoma cells, loaded them with the chemotherapeutic agent (doxorubicin, DOX). Then we evaluated the cellular uptake of the extracellular vesicles both in 2D monolayer and 3D tumor spheroid setups using confocal laser scanning microscope and flow cytometry. In vivo tumor homing of the extracellular vesicles was verified on CT26 tumor bearing BALB/c mice using in vivo imaging system. Finally, in vivo therapeutic effects were evaluated and compared using the same animal models treated with five doses of EV formulations. CT26-EV-DOX exhibited excellent biocompatibility, a high drug-loading capacity, controlled drug release behavior, and a high capability for targeting colorectal cancer cells. In particular, we verified that CT26-EV-DOX could preferentially be up taken by their parent cells and could effectively target and penetrate 3D tumor spheroids resembling colorectal tumors in vivo in comparison with their 4T1 derived EV partner. Additionally, treatment of colorectal tumor-bearing BALB/c mice with of CT26-EV-DOX significantly inhibited the growth of the tumors during the treatment course. The developed CT26-EV-DOX nanoparticles may present a novel and effective strategy for the treatment of colorectal cancer.     

Adjuvant effect of docetaxel on HPV16 L2E6E7 fusion protein vaccine in a mouse model

We previously demonstrated that the antineoplastic agent docetaxel enhanced the immune response to an influenza vaccine. This study evaluated the adjuvant effect of docetaxel (DOC) on the therapeutic efficacy of HPV16 L2E6E7 fusion protein (HPV-LFP) in mice inoculated with TC-1 cells. The results demonstrated that docetaxel significantly enhanced the therapeutic effect of HPV-LFP on TC-1 cell-induced tumors in mice. The injection of HPV-LFP in combination with docetaxel in TC-1 tumor-bearing mice significantly reduced tumor volume and weight, and a greater percent survival was detected than mice treated with HPV-LFP alone. The inhibition of tumors was associated with significantly increased serum antigen-specific IgG and isotypes, activated CTLs, increased IFN-γ-secreting T cells, and decreased Treg cells and IL-10-secreting cells in spleen. In addition, down-regulation of IL-10, VEGF and STAT3, up-regulation of IFN-γ and decreased Treg cells in the tumor microenvironment may also important contributing factors to the antitumor effect. It may be valuable to use a DOC-containing water to dilute HPV-LFP powder before injection in patients because of its excellent adjuvant effect on HPV-LFP and solubility in water.     

红芪总多糖对荷S180瘤小鼠的抑瘤作用及其机制的研究

目的研究红芪总多糖(THPS)单用及与环磷酰胺(CTX)合用对荷瘤小鼠的抑瘤作用,并探讨其机制。方法昆明种小鼠90只,随机分10只为正常对照组,其余80只小鼠接种S180瘤株后随机分为荷瘤对照组、CTX组、THPS高、中、低剂量[400、200、100mg/(kg.d)]组及各与CTX合用组共8组。正常对照组和荷瘤对照组给予生理盐水,其余各组给予相应剂量THPS及CTX治疗,观察肿瘤的体积变化。14d后处死小鼠,观察瘤质量、抑瘤率;血球计数仪检测外周血白细胞、血小板、红细胞及血红蛋白;流式细胞仪检测CD3+T细胞和NK细胞。结果与荷瘤对照组相比,中剂量THPS明显抑制小鼠S180瘤质量增长(P<0.01)及体积增加(P<0.05),提高NK细胞水平(P<0.05)。与CTX组相比,THPS与CTX合用后,各剂量组均能明显抑制CTX所致的白细胞数量下降(P<0.01);而只有中剂量的THPS与CTX合用能够降低肿瘤的质量(P<0.05),并能明显抑制CTX所致的CD3+T细胞(P<0.01)和NK细胞(P<0.05)数量下降。结论中剂量的THPS能抑制S180瘤生长,具有降低CTX免疫抑制和骨髓抑制的作用,其机制与提高T细胞和NK细胞介导的免疫应答有关。     

Z-100, an immunomodulatory arabinomannan extracted from Mycobacterium tuberculosis strain Aoyama B, augments anti-tumor activities of X-ray irradiation against B16 melanoma in association with the improvement of type 1T cell responses

In this study, the effects of combination therapy consisting of X-ray irradiation and Z-100 on the survival time of C57BL/6 mice inoculated with B16F10 melanoma were investigated. Survival time was significantly prolonged in B16F10 melanoma-bearing mice treated with the X-ray irradiation (5 Gy) and Z-100 (10 mg/kg s.c.) combination therapy compared with mice irradiated with X-rays alone. The weight of primary tumors and number of metastatic colonies were also significantly suppressed by the combination therapy compared with that in the X-ray irradiation group. These results indicated that Z-100 could enhance the anti-tumor effects of radiotherapy against B16F10 melanoma. On the other hand, the survival time of CD4 knockout mice bearing the same tumors was not prolonged by the combination therapy compared with mice irradiated with X-rays alone, suggesting that CD4+ cells are partly involved in augmentation of the anti-tumor effect of radiotherapy by Z-100. In addition, type 1 cytokine (IL-2, IFN-gamma) production was significantly increased and type 2 cytokine (IL-4, IL-10) production was significantly suppressed in the tumor-bearing mice treated with the combination therapy compared with the X-ray irradiation group. Moreover, interleukin-12 production by CD11c+ cells was also significantly increased in mice treated with the combination therapy compared with the X-ray irradiation group. These results indicate that Z-100 augmented the anti-tumor effects of X-ray irradiation. Moreover, we demonstrated that the effects of Z-100 were expressed at least in part, by the improvement of the T cell responses from type 2-dominant to type 1-dominant via up-regulation of IL-12 production.     

Biological activities and antitumor mechanism of an immunopotentiating organogermanium compound, Ge-132 (review)

The biological activities and antitumor mechanism of an immunopotentiator, Ge-132, is reviewed herein. Ge-132 exhibited antitumor activity against certain syngeneic and allogeneic experimental tumors. It was shown that T-cells and macrophages were involved when tumor-bearing mice were protected by the compound. This protective effect could be transferred to tumor-bearing mice, not treated with the compound, by a macrophage fraction and serum specimens obtained from Ge-132-treated mice. Interferon gamma (IFN gamma) was detected in the circulation of Ge-132-treated mice and when sera obtained from Ge-132-treated mice were treated with anti-IFN gamma antiserum in vitro, the antitumor activity was abolished. On the other hand, in mice treated with anti-IFN gamma antiserum, Ge-132 did not induce serum IFN and failed to protect against death due to ascites tumor progression. The in vivo administration of monoclonal anti-Thy 1.2 antibody prevented the expression of the antitumor activity of Ge-132. However, serum specimens obtained from Ge-132-treated mice effectively inhibited the tumor growth of T-cell-depleted mice bearing ascites tumors. Since it has been reported that T-lymphocytes produce IFN gamma, this suggested that Ge-132 may first stimulate T-cells to produce IFN gamma in the expression of the observed antitumor efficacy. In addition, sera obtained from Ge-132-treated mice did not show any antitumor activity in mice depleted of macrophage functions. Additionally, passive transfer of macrophages from mice treated with these serum specimens to tumor-bearing mice also resulted in the inhibition of tumor growth. Pretreatment of these serum specimens with anti-IFN gamma antiserum effectively prevented the generation of cytotoxic macrophages. Also, tumor-bearing mice treated exogenously with this antiserum did not differ significantly in survival as compared to controls, despite the administration of Ge-132. Furthermore, the antitumor activity of Ge-132 was detected in NK cell-depleted mice. Therefore, the antitumor mechanism of Ge-132 in the murine ascites tumor system may be expressed as follows: (a) Ge-132 stimulates T-cells to induce IFN gamma when mice are treated orally with the compound, (b) IFN gamma activates macrophages to become cytotoxic, and (c) the cytotoxic macrophages eliminate tumor cells.     

Opposing effect of IFNgamma and IFNalpha on expression of NKG2 receptors: negative regulation of IFNgamma on NK cells

The effector functions of natural killer (NK) cells are regulated by integrated signals across an array of stimulatory and inhibitory receptors interacting with target cell surface ligands. The regulatory effect of interferon-alpha (IFNalpha) and interferon-gamma (IFNgamma) on expression of the family of NKG2 receptors, stimulatory NKG2D receptor and inhibitory NKG2A receptor, and cytolysis of the target tumor cells (MICA+ and HLA-E+) were studied. Results show that IFNgamma and IFNalpha influence NK cell function differently. Interferon-alpha stimulates expression of stimulatory NKG2D receptors and inhibits the expression of inhibitory NKG2A receptors on NK cells. Contrary to the stimulatory effect of IFNalpha, IFNgamma inhibits cytolysis by NK cells of tumor cells expressing MICA or HLA-E cell surface proteins. Blocking NKG2D or NKG2A receptor activity with monoclonal antibodies partly attenuates the inhibitory effect of IFNgamma while promoting the effects of IFNalpha on NK cytolysis. These results show for the first time that IFNgamma negatively regulates NK cells through NKG2 receptors, and that the balance between stimulatory and inhibitory signals through the NKG2 family of receptors may be controlled by two opposing interferons. Modulating the balance between stimulatory and inhibitory signals through cell surface receptors on NK cells may open a new approach to NK cell-based biotherapy for cancer and infectious diseases.     

N-acetyl-D-glucosamine-coated polyamidoamine dendrimer promotes tumor-specific B cell responses via natural killer cell activation

N-acetyl-D-glucosamine-coated polyamidoamine dendrimer (GN8P), exerting high binding affinity to rodent recombinant NKR-P1A and NKR-P1C activating proteins, was shown previously to delay the development of rat colorectal carcinoma as well as mouse B16F10 melanoma, and to potentiate antigen-specific antibody formation in healthy C57BL/6 mice via NK cell stimulation. In this study, we investigated whether GN8P also modulates tumor-specific B cell responses. Serum anti-B16F10 melanoma IgG levels, IgG2a mRNA expression, antibody dependent cell-mediated cytotoxicity (ADCC), and counts of plasma as well as antigen presenting B cells were evaluated in tumor-bearing C57BL/6 mice treated with GN8P and in respective controls. To reveal the mechanism of GN8P effects, the synthesis of interferon-gamma (IFN-γ) and interleukin-4 (IL-4), cytokines involved in regulation of immunoglobulin class switch, was determined. The GN8P treatment significantly elevated IgG, and particularly IgG2a, response against B16F10 melanoma, which led to augmented ADCC reaction. The significant increase in production of IFN-γ, which is known to support IgG2a secretion, was observed solely in NK1.1 expressing cell populations, predominantly in NK cells. Moreover, GN8P raised the number of plasma cells, and promoted antigen presenting capacity of I-A/I-E-positive B lymphocytes by up-regulation of their CD80 and CD86 co-stimulatory molecule expression. These results indicate that GN8P-induced enhancement of tumor-specific antibody formation is triggered by NK cell activation, and contributes to complexity of anticancer immune response involving lectin-saccharide interaction.     

当归多糖锝标记物在癌细胞中摄取及荷瘤鼠体内显像研究

目的：研究HepG2和PC3荷瘤鼠是否影响当归多糖的肝靶向性。方法：当归多糖核素锝标记;^99mTc-DTPA-ASP体内SPECT/CT成像;检测HepG2和PC3对^99mTc-DTPA-ASP的摄取率;构建HepG2和PC3 2种裸鼠腋下移植瘤模型,通过SPECT显像来研究荷瘤鼠模型对当归多糖体内分布的影响。结果：细胞摄取实验结果显示,随着孵育时间的延长,肝癌细胞HepG2和非肝癌细胞PC3对当归多糖的摄取率逐渐增加,并在4 h后达到稳定,约为4.3%,说明2种癌细胞对当归多糖无明显特异性吸收。SPECT显像结果显示,荷瘤鼠注射^99mTc-DTPA-ASP后,2种模型肿瘤组织部分在SPECT图中出现显影,但亮度接近血液本底,且肝脏亮斑亮度几乎不受影响,说明移植瘤模型不影响当归多糖的体内分布。结论：癌细胞对当归多糖的低摄取率及荷瘤鼠显像肿瘤组织的弱亮斑,说明锝标记当归多糖探针探测体内肿瘤能力较弱,同时肿瘤组织不影响当归多糖的肝靶向性。     

脾多肽注射液增强胃癌大鼠脾脏免疫杀伤细胞活性的机制

目的 探讨脾多肽注射液增加胃癌大鼠脾脏免疫杀伤细胞活性的机制。方法 取75只大鼠,其中60只用N-甲基-N-硝基-亚硝基胍（MNNG）诱导建立大鼠胃癌模型,采用随机数表法将其分为模型组和低、中、高剂量组;剩余15只健康大鼠给予正常饮用水为对照组。第36周起,低、中、高剂量组分别尾静脉注射0.06,0.18,0.54 mL·kg^-1脾多肽注射液,对照组和模型组尾静脉注射生理盐水,每日1次,持续35 d。处死大鼠后观察胃组织病理学变化;对比各组脾脏指数、脾脏NK细胞杀伤活性;对比各组胃组织及脾脏中NK细胞占比及其表面活化受体（NKG2D）的表达、胃组织中NKG2D配体组织相容性复合体Ⅰ类相关基因A （MICA） mRNA及蛋白相对表达量。结果 模型组胃黏膜固有层有大量炎性细胞浸润,癌化细胞多,黏膜腺体排列严重紊乱;低、中、高剂量组胃黏膜固有层炎性细胞减少,黏膜腺体排列紊乱,癌细胞数量减少,其中中剂量组减少最为显著;脾脏指数、脾脏NK细胞杀伤活性、脾脏及胃组织中NK细胞占比及NKG2D表达、MICA mRNA和蛋白相对表达量组间比较,对照组最高,中剂量组其次,低、高剂量组稍低,模型组最低,并且除低、高剂量组之间比较差异无统计学意义外,其他每2组间比较差异均有统计学意义（P<0.05）。结论 脾多肽注射液可增强胃癌大鼠脾脏NK细胞杀伤活性,其中0.18 mL·kg^-1的脾多肽注射液增强效果最佳,可能与促进NK细胞增生、上调NK细胞活化性受体NKG2D及其配体MICA mRNA和蛋白表达有关。     

The anti-lung cancer activity of SEP is mediated by the activation and cytotoxicity of NK cells via TLR2/4 in vivo

Strongylocentrotus nudus egg polysaccharide (SEP) has been reported to display antitumor activity. However, the effects of SEP and its underlying mechanism in the treatment of lung cancer remain unclear, particularly with an immunodeficient mouse model of human non-small cell lung cancer (NSCLC). In the present study, we investigated the anti-lung cancer effects of SEP and its underlying mechanism of action in both Lewis lung cancer (LLC)-bearing C57/BL6J mice and human NSCLC H460-bearing nude mice. Although SEP showed no inhibitory effects on tumor cells in vitro, it markedly stimulated the percentage of CD3−NK1.1⁺ cells and natural killer (NK) cell cytotoxicity in the spleens of nude mice and C57/BL6J mice. In LLC-bearing mice, SEP not only inhibited tumor growth but also promoted NK-mediated cytotoxicity, the NK1.1⁺ cell population, and IL-2 and IFN-γ secretion. SEP significantly suppressed H460 growth in nude mice, which was abrogated by the selective depletion of NK cells via the intraperitoneal injection of anti-asialo GM-1 antibodies. Furthermore, anti-TLR2/4 antibodies blocked both SEP and NK cell binding and SEP-induced perforin secretion. SEP-induced proliferation and IFN-γ secretion by NK cells in wild type mice were partially impaired in TLR2 or TLR4 knockout mice. These results suggest that SEP-promoted NK cytotoxicity, which was partially mediated via TLR2 and TLR4, was the main contributing factor to lung cancer inhibition in vivo and that SEP may be a potential immunotherapy candidate for the treatment of lung cancer.     

Inhibitory effects of chitooligosaccharides on tumor growth and metastasis

Chitooligosaccharides (COS) are hydrolyzed products of chitosan and have been proven to exhibit various biological functions. The objectives of this study were to evaluate the anti-tumor growth, anti-metastatic potency and related pathways of COS extracted from fungi. In in vitro studies, we found that COS significantly inhibited human hepatocellular carcinoma (HepG2) cell proliferation, reduced the percentage of S-phase and decreased DNA synthesis rate in COS-treated HepG2 cells. Expressions of cell cycle-related genes were analyzed and the results indicated that p21 was up-regulated, while PCNA, cyclin A and cdk-2 were down-regulated. Moreover, we also found that the activity of metastatic related protein (MMP-9) could be inhibited by COS in Lewis lung carcinoma (LLC) cells. In in vivo studies, we found that COS inhibited the tumor growth of HepG2 xenografts in severe combined immune deficient (SCID) mice. In a LLC-bearing mouse tumor growth and lung metastasis model, COS inhibited tumor growth and the number of lung colonies in LLC-bearing mice as well as the lung metastasis, and it prolonged the survival time of the LLC-mice. These results suggest a potential anti-tumor growth and anti-metastatic potency of COS in cancer chemoprevention.     

Formaldehyde exposure impairs the function and differentiation of NK cells

We investigated the cytotoxic effects of formaldehyde (FA) on lymphocytes. FA-exposed mice showed a profound reduction not only in the number of natural killer (NK) cells but also in the expression of NK cell-specific receptors, but these mice did not exhibit decreases in the numbers of T or B lymphocytes. FA exposure also induced decreases in NK cytolytic activity and in the expression of NK cell-associated genes, such as IFN-γ, perforin and CD122. To determine the effect of FA on tumorigenicity, C57BL/6 mice were subcutaneously injected with B16F10 melanoma cells after FA exposure. The mass of the B16F10 tumor and the concentration of extravascular polymorphonuclear leukocytes were greater than those in unexposed tumor-bearing control mice. The number and cytolytic activity of NK cells were also reduced in B16F10 tumor-bearing mice exposed to FA. To determine how FA reduces the NK cell number, NK precursor (pNK) cells were treated with FA, and the differentiation status of the NK cells was analyzed. NK cell differentiation was impaired by FA treatment in a concentration-dependent manner. These findings indicate that FA exposure may promote tumor progression by impairing NK cell function and differentiation.     

Attenuated Salmonella typhimurium carrying shRNA-expressing vectors elicit RNA interference in murine bladder tumors

Aim:

To examine whether attenuated Salmonella typhimurium (S typhimurium) could be used as an anti-cancer agent or a tumor-targeting vehicle for delivering shRNA-expressing pDNA into cancer cells in a mouse tumor model.

Methods:

Mouse bladder transitional cancer cell line (BTT-T739) expressing GFP was used, in which the GFP expression level served as an indicator of RNA interference (RNAi). BTT-T739-GFP tumor-bearing mice (4–6 weeks) were treated with S typhimurium carrying plasmids encoding shRNA against gfp or scrambled shRNA. The mRNA and protein expression levels of GFP were assessed 5 d after the bacteria administration, and the antitumor effects of S typhimurium were evaluated.

Results:

In BTT-T739-GFP tumor-bearing mice, S typhimurium (1×10⁹ cfu, po) preferentially accumulated within tumors for as long as 40 d, and formed a tumor-to-normal tissue ratio that exceeded 1000/1. S typhimurium carrying plasmids encoding shRNA against gfp inhibited the expression of GFP in tumor cells by 73.4%. Orally delivered S typhimurium significantly delayed tumor growth and prolonged the survival of tumor-bearing mice.

Conclusion:

This study demonstrates that attenuated S typhimurium can be used for both delivering shRNA-expressing vectors into tumor cells and eliciting RNAi, thus exerting anti-tumor activity, which may represent a new strategy for the treatment of solid tumors.