DNA vaccines against cancer

Significant progress made in the field of tumor immunology by the characterization of a large number of tumor antigens, and the better understanding of the mechanisms preventing immune responses to malignancies has led to the extensive study of cancer immunization approaches such as DNA vaccines encoding tumor antigens. This article reviews major aspects of DNA immunization in cancer. It gives a brief history and then discusses the proposed mechanism of action, preclinical and clinical studies, and methods of enhancing the immune responses induced by DNA vaccines.     

吉非替尼联合靶向EGFR DNA疫苗对小鼠Lewis肺癌细胞体内外的抑制作用

目的：探讨吉非替尼（gefitinib）联合靶向EGFR DNA疫苗对小鼠Lewis肺癌体内外的抑制作用。方法：用鸡EGFR与兔IgG Fc段异种融合DNA疫苗pVAX1/cEGFRrFc免疫小鼠制备抗血清,ELISA方法测定抗血清的效价。MTT法检测Lewis细胞的生长情况。建立Lewis肺癌鼠移植瘤模型,随机分为疫苗组、吉非替尼组、吉非替尼+疫苗组和对照组,观察各组小鼠肿瘤体积、重量及生存情况。结果：pVAX1/cEGFRrFc DNA疫苗免疫小鼠后抗EGFR血清效价为1∶1 000。与抗血清组或吉非替尼组相比,抗血清+吉非替尼组可显著抑制Lewis细胞的生长（P<0.05)。体内实验显示,吉非替尼+疫苗组小鼠移植瘤生长缓慢, 荷留小鼠生存率显著提高（P<0.01） 。结论：以EGFR为靶点的DNA疫苗和靶向药物吉非替尼之间具有协同性抗肿瘤作用,DNA疫苗主动免疫可以提高吉非替尼的疗效。     

肺癌疫苗的临床研究现状

肺癌乃临床常见恶性肿瘤,早期多缺乏症状,就诊时已为中晚期,失去手术治疗或根治性放射治疗的机会,只能采用化疗等姑息性治疗措施。可是,含铂类药物标准一线化疗方案只能轻度延长总体生存,与最佳支持治疗相比,中位生存期仅延长了1～2个月。即使在早期患者,手术后也常出现复发,导致治疗失败,而且辅助化疗只能轻度改善总体生存,5年生存率增加了4％～10％,提示肺癌需要新的治疗策略与措施。[第一段]     

Anti-HER-2 DNA vaccine protects Syrian hamsters against squamous cell carcinomas

This paper illustrates the efficacy of DNA vaccination through electroporation in the prevention of oral transplantable carcinoma in Syrian hamsters. At 21 and 7 days before tumour challenge, 19 hamsters were vaccinated with plasmids coding for the extracellular and transmembrane domains of rat HER-2 receptor (EC-TM plasmids), whereas 19 control hamsters were injected intramuscularly with the empty plasmid. Immediately following plasmid injection, hamsters of both groups received two square-wave 25 ms, 375 V cm(-1) electric pulses via two electrodes placed on the skin of the injection area. At day 0, all hamsters were challenged in the submucosa of the right cheek pouch with HER-2-positive HCPC I cells established in vitro from an 7,12-dimethylbenz[a]anthracene-induced oral carcinoma. This challenge gave rise to HER-2-positive buccal neoplastic lesions in 14 controls (73.37%), compared with only seven (36.8%, P<0.0027) vaccinated hamsters. In addition, the vaccinated hamsters displayed both a stronger proliferative and cytotoxic response than the controls and a significant anti-HER-2 antibody response. Most of the hamsters that rejected the challenge displayed the highest antibody titres. These findings suggest that DNA vaccination may have a future in the prevention of HER-2-positive human oral cancer.     

Novel activity of acriflavine against colorectal cancer tumor cells

A high-throughput screen of the cytotoxic activity of 2000 molecules from a commercial library in three human colon cancer cell lines and two normal cell types identified the acridine acriflavin to be a colorectal cancer (CRC) active drug. Acriflavine was active in cell spheroids, indicating good drug penetration and activity against hypoxic cells. In a validation step based on primary cultures of patient tumor cells, acriflavine was found to be more active against CRC than ovarian cancer and chronic lymphocytic leukemia. This contrasted to the activity pattern of the CRC active standard drugs 5-fluorouracil, irinotecan and oxaliplatin. Mechanistic studies indicated acriflavine to be a dual topoisomerase I and II inhibitor. In conclusion, the strategy used seems promising for identification of new diagnosis-specific cancer drugs.     

A DNA vaccine against ERBB2 impairs chemical carcinogenesis in random-bred hamsters

Vaccines against oncoantigens halt early neoplastic lesions in several cancer-prone, genetically engineered mouse models, whereas their ability to prevent chemical carcinogenesis has not been explored. This is a significant issue, as exposure to chemical mutagens is responsible for a substantial percentage of cancers worldwide. Here, we show that the archetypal oncoantigen ERBB2 is transiently overexpressed in Syrian hamsters during the early stages of 7,12-dimethylbenz[α]anthracene (DMBA)-induced oral carcinogenesis. Repeated DNA vaccinations against ERBB2 significantly reduce the number, size, and severity of oral lesions in a manner directly proportional to the anti-ERBB2 antibody response. These results support the prospects of vaccines as a fresh strategy in the management of individuals at risk for exposure to defined carcinogenic agents.     

A novel DNA vaccine containing four mimicry epitopes for gastric cancer

Gastric cancer is one of the most common malignant tumors in China. This paper focuses on the development of a DNA vaccine containing four mimotopes of MG7Ag for gastric cancer (multi-epitope vaccine). By inoculating BALB/c mice, the vaccine was characterized and compared with a similar vaccine containing only one mimotope (mono-epitope vaccine) and other controls. Cellular ELISA indicated that serum titer of antibody against MG7Ag was significantly higher in mice immunized with the multi-epitope vaccine than that in the group immunized with the mono-epitope vaccine (0.8627 vs 0.6754, P < 0.05). And ELISPOT assay showed that the number of INF-gamma spots induced by multi-epitope vaccine was significantly larger than that of the group immunized with mono-epitope vaccine(93.3 vs 70.7, P < 0.05). Two weeks after tumor challenge, the weight of tumor in each mouse was evaluated, and the tumor masses formed in the mice immunized with multi-epitope vaccine were markedly smaller than those formed in the mice immunized with mono-epitope vaccine. These studies demonstrated that both humoral and cellular response were induced by the two vaccines and the efficiency of multi-epitope vaccine is stronger than that of the mono-epitope vaccine.     

A DNA vaccine expressing tyrosinase-related protein-2 induces T-cell-mediated protection against mouse glioblastoma

A mouse glioblastoma cell line, termed GL261, was shown to express high levels of proteins involved in melanin biosynthesis such as the tyrosinase-related protein-2 (TRP-2), which is commonly overexpressed in melanoma cells. Mice injected with GL261 cells developed a CD8(+) T-cell response to TRP-2 and a DNA vaccine expressing human (h)TRP-2 induced CD8(+) T cells that recognized TRP-2 expressed by GL261 cells indicating that this melanoma-associated antigen may be suited for active immunotherapy of glioblastoma. Mice vaccinated with a DNA vaccine expressing TRP-2 were partially protected against subcutaneous, intravenous, or intracerebral challenge with the glioblastoma cells. Vaccine-induced protection against intracerebral challenge required both CD4(+) and CD8(+) T cells. Vaccine efficacy was enhanced upon addition of IL-12 as a genetic adjuvant. These results indicate that this well-defined melanoma-associated antigen can induce an adaptive immune response, which limits the intracerebral progression of a glioblastoma.     

cEGFR-rFc融合DNA疫苗抗小鼠黑素移植瘤的效果

目的:构建cEGFR-rFc融合DNA疫苗, 观察其对小鼠黑素移植瘤的抑制作用.方法:以异种同源鸡EGFR(chicken EGFR,cEGFR)膜外部分与兔疫球蛋白IgG的Fc段(rabbit IgG Fc,rFc)为基础构建真核表达载体pVAX1/cEGFR-rFc,脂质体法转染黑素瘤B16 细胞,免疫荧光法检测融合蛋白在B16细胞中的表达;以融合DNA疫苗免疫C57BL/6J小鼠,Western blotting法检测融合蛋白在小鼠体内的稳定表达.疫苗免疫小鼠接种B16黑素瘤细胞,14 d后处死部分小鼠,取出瘤体称重,计算抑瘤率;同时观察小鼠荷瘤后的生存率;ELASIA法检测DNA疫苗免疫小鼠血清抗EGFR抗体滴度,流式细胞仪测定小鼠脾细胞淋巴细胞亚群.结果:成功构建融合DNA疫苗pVAX1/ cEGFR-rFc,重组载体转染B16细胞后能检测到融合蛋白显著表达,疫苗免疫小鼠后能检测融合蛋白体内稳定表达.融合DNA疫苗能够延缓小鼠黑素移植瘤的生长,抑瘤率为54%(P<0.01);能延长荷瘤小鼠的生存期(疫苗组小鼠接种瘤细胞后30 d的生存率为40%);融合DNA疫苗诱发小鼠产生高滴度抗EGFR抗体(效价1∶1 000)和T细胞免疫(疫苗组小鼠脾脏CD8 T淋巴细胞数目显著增加, P<0.01).结论:cEGFR-rFc融合DNA疫苗能产生有效对抗黑素瘤B16细胞的免疫效应.     

Novel target antigens for dendritic cell-based immunotherapy against ovarian cancer

Identification of tumor-specific target antigens has been a major hurdlefor the treatment of malignant disease by vaccination or immunotherapy. A second challenge has been the induction of therapeutically effective immune responses to these ‘self’ antigens. The recent recognition of dendritic cells as powerful antigen-presenting cells capable of inducing primary T-cell responses in vitro and in vivo – in combination with identification of tumor-specific antigens – has generated widespread interest in dendritic cell-based immunotherapy against a wide variety of tumors. In this review, a series of recently identified novel ovarian tumor antigens is discussed, and the potential for therapeutic dendritic cell vaccination targeted against these antigens is assessed.     

Novel target antigens for dendritic cell-based immunotherapy against ovarian cancer

Identification of tumor-specific target antigens has been a major hurdle for the treatment of malignant disease by vaccination or immunotherapy. A second challenge has been the induction of therapeutically effective immune responses to these 'self' antigens. The recent recognition of dendritic cells as powerful antigen-presenting cells capable of inducing primary T-cell responses in vitro and in vivo--in combination with identification of tumor-specific antigens--has generated widespread interest in dendritic cell-based immunotherapy against a wide variety of tumors. In this review, a series of recently identified novel ovarian tumor antigens is discussed, and the potential for therapeutic dendritic cell vaccination targeted against these antigens is assessed.     

Novel disubstituted chrysene as a potent agent against colon cancer

Research on polycyclic aromatic hydrocarbons and their derivatives has received significant attention from the scientific community. The present study involved the synthesis of several novel 6,12-disubstituted chrysene derivatives. Nitration of chrysene with nitric acid produced 6,12-dinitrochrysene which when reduced yielded 6,12-diaminochrysene. A coupling reaction of 6,12-diaminochrysene with an acid in the presence of isobutylchloroformate produced amide. The reduction of amide produced an amine. The amino was converted to a hydrochloride salt. The new compounds were characterized through different types of analytical data. One of these compounds demonstrated marked activity in vivo against a colon cancer cell line. Inhibition of the growth of this tumor was best noted at day 20 when each treatment regimen inhibited the average tumor volume by 50%. In a number of in vivo tests in various regimens, the hydrochloride salt demonstrated consistent inhibition of the growth of the cancer HT-29 cell line. Despite the research progress in polycyclic aromatic compounds, the use of these types of molecules as anticancer agents has not been reported systematically.     

Bio-nanoparticle based therapeutic vaccine induces immunogenic response against triple negative breast cancer

Triple negative breast cancer (TNBC) is more aggressive and has a poorer prognosis than other sub-types of breast tumors. This study elucidates how aspartate beta-hydroxylase (ASPH) network promotes drug resistance, and immunotherapy targeting ASPH may improve the efficacy of Doxorubicin (DOX) therapy. An orthotopic model of breast cancer generated by 4T1 cells in immunocompetent mice was used to explore efficacy of immunotherapy in combination with DOX chemotherapy. We evaluated mRNA and protein expression in cultured tumor cells and tissue, as well as assessed cell proliferation, apoptosis, soluble factors/cytokine production, immune cell population diversity and function. We observed that ASPH expression enables TNBC cells to exhibit primary resistance to DOX induced single-/double-strand breaks (SSB/DSB) and enhanced proliferation and survival. Specific bio-nanoparticle based therapeutic vaccine (BNP-TV) promoted ASPH uptake by and maturation of DCs. This BNP-TV combined with DOX induces immunogenic cell death (ICD) in orthotopic xenograft tumors and significantly suppressed primary mammary tumor growth and distant multi-organ metastases. Immunogenic cell death induced by BNP-TV targeting ASPH combined with DOX provides opportunities to treat a highly resistant and metastatic form of breast cancer.     

DNA vaccines against cancer: From genes to therapy

After an erratic history, there is at last a clear opportunity for mobilizing an immune attack against cancer cells. The new strategies are dependent on the techniques of molecular biology, which are able both to identify potential target tumor antigens at the gene level, and to help to unravel the complexities of immune mechanisms required. Vaccine delivery systems can also be genetic, with DNA vaccines able to act as viral mimics and enter several antigen processing pathways. Rational vaccine designs can be rapidly tested in models and selected for pilot clinical trials. One difficulty faced by tumor antigens is that they may be weak, and therefore fail to engage the immune system. Attaching genes encoding alert signals appears to solve this problem. We have focused initially on idiotypic determinants of B-cell tumors, where the encoding variable region genes can induce protective anti-idiotypic immunity if delivered as a fusion protein with a fragment of Tetanus toxin. This model may have relevance for alternative tumor antigens. A clinical trial of patients with lymphoma is in progress, and wider application may be limited only by the ability to bring patients into clinical remission prior to vaccination.     

树突状细胞瘤苗对自体肺癌细胞的杀伤作用

目的: 利用非小细胞肺癌(nonsmallcell lung cancer; NSCLC)患者的树突状细胞(dendritic cell,DC)负载自体肿瘤抗原制备DCCIK(cytokine induced killer cell)瘤苗,观察其在体外对患者自身肿瘤细胞的杀伤作用。方法:提取NSCLC患者外周血单个核细胞(peripheral blood mononuc     

pIRES-CEA-HSP70核酸疫苗诱导杀伤结肠癌细胞的研究

目的:观察核酸疫苗pIRES-CEA-HSP70诱导小鼠产生的细胞免疫应答,以探索结肠癌术后复发的防治新途径。方法:将pIRES、pIRES-CEA、pIRES-HSP70、pIRES-CEA-HSP70制作核酸疫苗免疫小鼠,采用MTT比色法,检测小鼠脾淋巴细胞对结肠癌细胞CW-2的杀伤效应。结果:核酸疫苗pIRES-CEA-HSP70免疫组的小鼠脾淋巴细胞,在效靶比50∶1、25∶1、12.5∶1、6.25∶1下,对CW-2的杀伤率分别为(35.43±3.88)%(、26.88±3.17)%(、20.33±1.92)%(、15.55±0.76)%,均明显高于其余3组,差异有统计学显著性(P<0.01)。pIRES、pIRES-CEA、pIRES-HSP70 3组杀伤率差异无显著性(P>0.05)。结论:核酸疫苗pIRES-CEA-HSP70可诱导小鼠产生特异性细胞免疫应答,为其用于结肠癌的治疗提供实验基础。     

Mage-b vaccine delivered by recombinant Listeria monocytogenes is highly effective against breast cancer metastases

New therapies are needed that target breast cancer metastases. In previous studies, we have shown that vaccination with pcDNA3.1-Mage-b DNA vaccine is effective against breast cancer metastases. In the study presented here, we have further enhanced the efficacy of Mage-b vaccination through the improved delivery of the vaccine using recombinant Listeria monocytogenes (LM). Three overlapping fragments of Mage-b as well as the complete protein-encoding region of Mage-b have been expressed as a fusion protein with a truncated non-cytolytic form of listeriolysin O (LLO) in recombinant LM. These different Mage-b vaccine strains were preventively tested for their efficacy against breast cancer metastases in a syngeneic mouse tumour model 4T1. The LM-LLO-Mage-b/2nd, expressing position 311-660 of the cDNA of Mage-b, was the most effective vaccine strain against metastases in the 4T1 mouse breast tumour model. Vaccination with LM-LLO-Mage-b/2nd dramatically reduced the number of metastases by 96% compared with the saline group and by 88% compared with the vector control group (LM-LLO), and this correlated with strong Mage-b-specific CD8 T-cell responses in the spleen, after restimulation with Mage-b. However, no effect of LM-LLO-Mage-b/2nd was observed on 4T1 primary tumours, which may be the result of a complete absence of Mage-b-specific immune responses in the draining lymph nodes. Vaccination with LM-LLO-Mage-b/2nd could be an excellent follow-up after removal of the primary tumour, to eliminate metastases and residual tumour cells.